JP4462387B1 - Refrigeration equipment - Google Patents

Abstract

In a refrigeration apparatus for supplying refrigeration oil of an oil separator to a plurality of compressors together with an intermediate pressure refrigerant, a storage amount of the refrigeration oil in each compressor is ensured.
In a refrigerant circuit (20), a variable capacity compressor (40a) sucks refrigerant from a first suction pipe (51), and a second fixed capacity compressor (40c) from a third suction pipe (53). Inhale refrigerant. The refrigeration oil in each oil separator (47a to 47c) flows into the compressors (40a to 40c) together with the intermediate pressure refrigerant through the oil return pipe (54) and the main injection pipe (61). During normal operation, the controller (200) adjusts the opening degree of each injection motor operated valve (64a to 64c) so that the temperature of the refrigerant discharged from the corresponding compressor becomes a predetermined target value. When the first suction pipe (51) is at a lower pressure than the third suction pipe (53), the controller temporarily reduces the opening of the first injection motor-operated valve (64a) than during normal operation, The opening degree of the third injection motor-operated valve (64c) is temporarily enlarged as compared with that during normal operation.
[Selection] Figure 1

Description

  The present invention is a refrigeration apparatus that performs so-called intermediate pressure injection for supplying intermediate pressure refrigerant to a compressor, and in particular, supplies refrigerating machine oil separated from refrigerant discharged from the compressor together with intermediate pressure refrigerant to the compressor. About things.

  Conventionally, a refrigeration apparatus including a refrigerant circuit that performs a refrigeration cycle is known. This type of refrigeration apparatus is widely used in refrigerators such as refrigerators and freezers that store foods, air conditioners that heat and cool indoors, and the like.

  Patent Document 1 discloses a refrigeration apparatus provided with a heat source unit, an internal unit, and an indoor unit. The refrigerant circuit of the refrigeration apparatus includes a first compressor, a second compressor, and a heat source side heat exchanger housed in the heat source unit, an in-compartment expansion valve and in-house heat housed in the in-compartment unit. The exchanger is connected to the indoor expansion valve and the indoor heat exchanger housed in the indoor unit.

  Specifically, the high-pressure lines extending from the discharge sides of the first compressor and the second compressor are joined and connected to the heat source side heat exchanger and the indoor heat exchanger in a switchable manner. A first low-pressure line extending from the suction side of the first compressor is configured to be connectable to the internal heat exchanger via the internal expansion valve. A second low-pressure line extending from the suction side of the second compressor is configured to be connectable to the indoor heat exchanger via the indoor expansion valve. During operation of the refrigeration system, the inside of the freezer is cooled by the internal heat exchanger, and at the same time, indoor air conditioning is performed by the indoor heat exchanger.

  In the refrigerant circuit of the refrigeration apparatus disclosed in Patent Document 1, an oil separator is provided on the discharge side of the first compressor and the second compressor, and an oil return extending from an oil outlet of the oil separator is provided. The pipe is connected to the injection pipe. The injection pipe is for injecting an intermediate pressure refrigerant into the first compressor and the second compressor, and the main pipe branched from a high-pressure line connected to the outlet side of the heat source side heat exchanger; And a plurality of branch pipes which are further branched from the main pipe and connected to the intermediate ports of the first compressor and the second compressor one by one.

  During the operation of the first compressor and the second compressor, the oil separator separates the refrigerating machine oil from the discharged refrigerant mixed with the refrigerating machine oil discharged from the first compressor and the second compressor. The refrigerating machine oil separated from the discharged refrigerant by the oil separator flows into the injection pipe through the oil return pipe, joins with the refrigerant flowing through the injection pipe, and then returns to the first compressor and the second compressor. .

JP 2008-076017 A

  However, when the refrigeration oil in the oil separator is returned to the first compressor and the second compressor using the injection pipe as in the refrigeration apparatus disclosed in Patent Document 1, the first compression is performed. More refrigeration oil may return to one of the compressor and the second compressor.

  That is, in the conventional refrigeration apparatus, the low-pressure line of the refrigerant circuit is composed of the first and second low-pressure lines, and the pressure of the first and second low-pressure lines (that is, the pressure of the refrigerant flowing through the low-pressure line). ) Is determined by the evaporation pressure of the use side heat exchanger connected to each low pressure line. On the other hand, normally, the evaporation pressure of the refrigerant in the internal heat exchanger that cools the inside of the refrigerator is lower than the evaporation pressure of the refrigerant in the indoor heat exchanger that cools the room. Therefore, when the pressures in the first and second low pressure lines are compared, the first low pressure line to which the internal heat exchanger is connected is usually lower during indoor cooling.

  Thus, if the pressures of the first low pressure line and the second low pressure line are different, the pressure of the intermediate port of the compressor connected to each low pressure line is also different. For this reason, during indoor cooling, the pressure of the intermediate port of the first compressor is lower than the pressure of the intermediate port of the second compressor, and the lower pressure of the intermediate port (that is, the first compressor). The amount of refrigerating machine oil sent back from the oil separator increases. As a result, the amount of refrigerating machine oil stored in the second compressor decreases, and the second compressor may be damaged due to poor lubrication.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a refrigerating machine oil that includes a plurality of compressors, performs intermediate pressure injection to each compressor, and is separated from refrigerant discharged from each compressor. In the refrigeration system that supplies the refrigerant together with the intermediate pressure refrigerant to each compressor, the storage amount of the refrigeration oil in all the compressors is secured to prevent damage to each compressor and improve the reliability of the refrigeration apparatus. is there.

  The first invention is directed to a refrigeration apparatus, and includes a refrigerant circuit (20) that performs a refrigeration cycle. The refrigerant circuit (20) includes a first evaporator (91) and a second evaporator (81, 44), a first compressor (40a) that sucks refrigerant evaporated in the first evaporator (91), and a second compressor (40a) that sucks refrigerant evaporated in the second evaporator (81, 44) ( 40c), a condenser (44, 81) into which refrigerant discharged from the first compressor (40a) and the second compressor (40c) flows, a main injection pipe (61) through which intermediate pressure refrigerant flows, A first branch pipe (62a) connecting the injection pipe (61) to the first compressor (40a), and a second branch pipe connecting the main injection pipe (61) to the second compressor (40c). An injection circuit (60) having a branch pipe (62c) and a refrigerant discharged from the first compressor (40a) and the second compressor (40c). An oil return circuit (49) for supplying separated refrigeration oil to the main injection pipe (61) is provided, and the refrigerant flow rate in the first branch pipe (62a) and the second branch pipe (62c) Is further provided with a flow rate adjusting mechanism (250) that performs a normal operation for adjusting the physical quantity for control to a predetermined control target value. In the present invention, the flow rate adjusting mechanism (250) includes a condition that the suction refrigerant pressure of the first compressor (40a) is higher than the suction refrigerant pressure of the second compressor (40c), and When the determination condition is satisfied with one of the conditions that the pressure of the suction refrigerant of the first compressor (40a) is equal to or higher than the pressure of the suction refrigerant of the second compressor (40c), An operation of increasing the refrigerant flow rate in the first branch pipe (62a) than during the normal operation and decreasing the refrigerant flow rate in the second branch pipe (62c) than during the normal operation is an oil distribution operation. When intermittently executed and the determination condition is not satisfied, the refrigerant flow rate in the first branch pipe (62a) is decreased as compared with that during the normal operation, and the refrigerant flow rate in the second branch pipe (62c). The above normal operation to increase the operation of the oil Intermittently executed as distribution for operation.

  In the first invention, the intermediate pressure refrigerant is supplied to the first compressor (40a) and the second compressor (40c) by the injection circuit (60). The intermediate pressure refrigerant flowing through the first branch pipe (62a) is supplied to the compression chamber in the middle of compression of the first compressor (40a). The intermediate pressure refrigerant flowing through the second branch pipe (62c) is supplied to the compression chamber in the middle of compression of the second compressor (40c). The intermediate pressure refrigerant has a higher pressure than the refrigerant sucked into the first compressor (40a) (suction refrigerant) and the refrigerant sucked into the second compressor (40c) (suction refrigerant). The refrigerant has a lower pressure than both the refrigerant discharged from the compressor (40a) and the refrigerant discharged from the second compressor (40c).

  In the first invention, refrigerating machine oil is supplied from the oil return circuit (49) to the main injection pipe (61) of the injection circuit (60). The refrigeration oil that has flowed into the main injection pipe (61) flows into the first compressor (40a) together with the intermediate pressure refrigerant through the first branch pipe (62a), and passes through the second branch pipe (62c). And flows into the second compressor (40c) together with the intermediate pressure refrigerant.

  In the first invention, the flow rate adjusting mechanism (250) adjusts the refrigerant flow rate in the first branch pipe (62a) and the refrigerant flow rate in the second branch pipe (62c). When the refrigerant flow rate in the first branch pipe (62a) increases or decreases, the amount of refrigerating machine oil supplied to the first compressor (40a) together with the intermediate pressure refrigerant also increases or decreases accordingly. Further, when the refrigerant flow rate in the second branch pipe (62c) increases or decreases, the amount of refrigerating machine oil supplied to the second compressor (40c) together with the intermediate pressure refrigerant also increases or decreases accordingly.

  In the first invention, the flow rate adjusting mechanism (250) intermittently performs the oil distribution operation. The flow rate adjusting mechanism (250) executes different operations as the oil distribution operation when the determination condition is satisfied and when the determination condition is not satisfied.

  If the determination condition is satisfied, the pressure in the compression chamber in the middle of compression in the first compressor (40a) is higher than the pressure in the compression chamber in the middle of compression in the second compressor (40c), and the first compressor (40a ), It can be estimated that the refrigeration oil is more likely to return to the second compressor (40c). Therefore, the flow rate adjusting mechanism (250) of the first invention increases the refrigerant flow rate in the first branch pipe (62a) as compared with that during normal operation as the oil distribution operation when the determination condition is satisfied, An operation for decreasing the refrigerant flow rate in the branch pipe (62c) than during the normal operation is performed. During this oil distribution operation, the flow rates of the intermediate pressure refrigerant and the refrigeration oil flowing from the first branch pipe (62a) to the first compressor (40a) are increased compared to those during normal operation, and the second branch pipe The flow rates of the intermediate pressure refrigerant and the refrigerating machine oil flowing into the second compressor (40c) from (62c) are reduced compared to during normal operation. Therefore, in the state where the determination condition is satisfied, the amount of refrigerating machine oil stored in the first compressor (40a) decreases while the flow rate adjusting mechanism (250) is performing normal operation. It increases while the adjustment mechanism (250) is performing the oil dispensing operation. The flow rate adjusting mechanism (250) recovers the refrigerating machine oil storage amount in the first compressor (40a) by temporarily stopping the normal operation and executing the oil distribution operation, and thereafter performing the normal operation. Resume.

  When the determination condition is not satisfied, the pressure in the compression chamber in the middle of compression in the second compressor (40c) is higher than the pressure in the compression chamber in the middle of compression in the first compressor (40a), and the second compressor (40c ), It can be estimated that the refrigeration oil is more likely to return to the first compressor (40a). Therefore, the flow rate adjusting mechanism (250) of the first invention reduces the refrigerant flow rate in the first branch pipe (62a) as compared with that during normal operation as the oil distribution operation when the determination condition is not satisfied, The operation of increasing the refrigerant flow rate in the branch pipe (62c) than during normal operation is performed. During the oil distribution operation, the flow rates of the intermediate pressure refrigerant and the refrigerating machine oil flowing from the first branch pipe (62a) to the first compressor (40a) are smaller than those during normal operation, and the second branch pipe The flow rates of the intermediate pressure refrigerant and the refrigerating machine oil flowing into the second compressor (40c) from (62c) are increased compared to during normal operation. Therefore, in the state where the determination condition is not satisfied, the amount of refrigerating machine oil stored in the second compressor (40c) decreases while the flow rate adjusting mechanism (250) is performing the normal operation. It increases while the adjustment mechanism (250) is performing the oil dispensing operation. The flow rate adjusting mechanism (250) recovers the refrigerating machine oil storage amount in the second compressor (40c) by temporarily stopping the normal operation and executing the oil distribution operation, and thereafter performs the normal operation. Resume.

  In a second aspect based on the first aspect, the flow rate adjusting mechanism (250) includes a first flow rate adjusting valve (64a) provided in the first branch line (62a) and the second branch line. A second flow rate control valve (64c) provided in (62c), and the first flow rate control valve (64a) and the second flow rate control valve (64c) so that the control physical quantity becomes a predetermined control target value. An opening degree control unit (220) for controlling the opening degree, and the opening degree control unit (220) performs the first flow rate control valve (64a) as an oil distribution operation when the determination condition is satisfied. ) To increase the degree of opening of the second flow rate control valve (64c) or to reduce the degree of opening of the second flow rate control valve (64c) than during normal operation. As an operation for oil distribution when not established, the opening degree of the first flow rate control valve (64a) is reduced more than that during the normal operation. And work, the second flow control valve the opening of (64c) and executes the one or both of the operation to expand than during the normal operation.

  In the second invention, the flow rate adjusting mechanism (250) includes a first flow rate adjusting valve (64a), a second flow rate adjusting valve (64c), and an opening degree control unit (220). The opening degree control unit (220) adjusts the opening degree of the first flow rate control valve (64a) in order to adjust the refrigerant flow rate in the first branch pipe (62a), and the refrigerant in the second branch pipe (62c). In order to adjust the flow rate, the opening degree of the second flow rate control valve (64c) is adjusted.

  In the case where the determination condition is satisfied, the flow rate adjusting mechanism (250) of the second aspect of the invention includes an operation for expanding the opening of the first flow rate adjusting valve (64a) than during normal operation, and a second flow rate adjusting valve (64c). ) Is performed as an oil distributing operation. In the injection circuit (60), the intermediate pressure refrigerant and the refrigerating machine oil flowing through the main injection pipe (61) are divided and flow into the first branch pipe (62a) and the second branch pipe (62c). For this reason, both the operation of expanding the opening of the first flow rate control valve (64a) than during normal operation and the operation of reducing the opening of the second flow rate control valve (64c) than during normal operation are performed. Even when only one of these two operations is performed, the refrigerant flow rate in the first branch pipe (62a) increases and the refrigerant flow rate in the second branch pipe (62c) decreases.

  In the case where the determination condition is not satisfied, the flow rate adjusting mechanism (250) of the second invention is configured to reduce the opening degree of the first flow rate adjusting valve (64a) as compared with that during normal operation, and the second flow rate adjusting valve (64c). ) Is performed as an oil distribution operation. As described above, in the injection circuit (60), the intermediate pressure refrigerant and the refrigeration oil flowing through the main injection pipe (61) are divided into the first branch pipe (62a) and the second branch pipe (62c). To do. For this reason, both the operation | movement which reduces the opening degree of a 1st flow control valve (64a) from normal operation, and the operation | movement which expands the opening degree of a 2nd flow control valve (64c) rather than a normal operation are performed. Even when only one of these two operations is performed, the refrigerant flow rate in the first branch pipe (62a) decreases and the refrigerant flow rate in the second branch pipe (62c) increases.

  In a third aspect based on the second aspect, the opening degree control unit (220) uses the temperature or superheat degree of the refrigerant discharged from the first compressor (40a) as the first control physical quantity. The opening degree of the first flow rate control valve (64a) is adjusted so that the first control physical quantity becomes the first control target value, and the temperature or superheat degree of the refrigerant discharged from the second compressor (40c). Is used as the second control physical quantity, and the opening of the second flow rate control valve (64c) is adjusted so that the second control physical quantity becomes the second control target value, and the normal operation is performed. In some cases, the first and second control target values are set to predetermined normal target values to adjust the opening degree of the first flow rate control valve (64a) and the second flow rate control valve (64c). When the opening degree of the first flow rate control valve (64a) is increased during the oil distribution operation as compared with that during the normal operation, the first control When the value is set to a value lower than the normal target value and the opening degree of the first flow rate control valve (64a) is reduced during the oil distributing operation than during the normal operation, the first control is performed. When the target value is set to a value higher than the normal target value and the opening of the second flow rate control valve (64c) is increased during the oil distribution operation than during the normal operation, the second value is set. When the control target value is set to a value lower than the normal target value and the opening degree of the second flow rate control valve (64c) is reduced during the oil distribution operation than during the normal operation, the second The control target value is set to a value higher than the normal target value.

  In a fourth aspect based on the first aspect, the flow rate adjusting mechanism (250) uses the temperature or superheat degree of the refrigerant discharged from the first compressor (40a) as a first control physical quantity. The refrigerant flow rate in the first branch pipe (62a) is adjusted so that the first control physical quantity becomes the first control target value, and the temperature or superheat degree of the refrigerant discharged from the second compressor (40c) is adjusted. Used as the second control physical quantity, the refrigerant flow rate in the second branch pipe (62c) is adjusted so that the second control physical quantity becomes the second control target value.

  In the third and fourth inventions, the opening degree control unit (220) uses the temperature or superheat degree of the refrigerant discharged from the first compressor (40a) or the degree of superheat as the first physical quantity for control. The second flow rate control valve (64c) is adjusted by adjusting the opening degree of the flow rate control valve (64a) and using the temperature or superheat degree of the refrigerant discharged from the second compressor (40c) as the second control physical quantity. ) Is adjusted. During the normal operation, the opening degree control unit (220) sets both the first control target value and the second control target value to the normal target value. In other words, during the normal operation, the opening degree control unit (220) adjusts the opening degree of the first flow rate control valve (64a) so that the first control physical quantity becomes the normal target value, and performs the second control purpose. The opening degree of the second flow rate control valve (64c) is adjusted so that the physical quantity becomes the normal target value.

  In general, in a compressor in which intermediate pressure refrigerant is supplied to a compression chamber in the middle of compression, the temperature or superheat of the refrigerant discharged from the compressor decreases as the flow rate of intermediate pressure refrigerant supplied to the compressor increases. The lower the flow rate of the intermediate pressure refrigerant supplied to the compressor, the higher it becomes.

  For this reason, when the first control target value is made lower than the normal target value, the refrigerant flow rate in the first branch pipe (62a) is increased to lower the temperature or superheat degree of the refrigerant discharged from the first compressor (40a). Therefore, the opening degree of the first flow rate control valve (64a) is expanded more than during normal operation. Further, when the first control target value is set higher than the normal target value, the refrigerant flow rate in the first branch pipe (62a) is decreased to increase the temperature or superheat degree of the refrigerant discharged from the first compressor (40a). In addition, the opening of the first flow rate control valve (64a) is reduced more than during normal operation.

  Similarly, when the second control target value is made lower than the normal target value, the refrigerant flow rate in the second branch pipe (62c) is increased, and the temperature or superheat degree of the refrigerant discharged from the second compressor (40c) is increased. In order to lower it, the opening degree of the second flow rate control valve (64c) is expanded more than during normal operation. Further, when the second control target value is set higher than the normal target value, the refrigerant flow rate in the second branch pipe (62c) is decreased to increase the temperature or superheat degree of the refrigerant discharged from the second compressor (40c). In addition, the opening of the second flow rate control valve (64c) is reduced more than during normal operation.

  Therefore, the opening degree control unit (220) of the third invention changes the first control target value from the normal target value during the oil distribution operation, thereby changing the opening degree of the first flow rate control valve (64a). The opening degree of the second flow rate control valve (64c) is increased or decreased from the opening degree during the normal operation by increasing or decreasing the opening degree during the normal operation and changing the second control target value from the normal target value.

  In a fifth aspect based on the first aspect, the refrigerant circuit (20) includes a refrigerant evaporated in the first evaporator (91) and a refrigerant evaporated in the second evaporator (81, 44). A third compressor (40b) that selectively sucks one of the two is provided, and the injection circuit (60) includes a third compressor (61) that connects the main injection pipe (61) to the third compressor (40b). A branch pipe (62b) is provided, and the oil return circuit (49) is separated from the refrigerant discharged from the first compressor (40a), the second compressor (40c), and the third compressor (40b). Refrigeration oil is supplied to the main injection pipe (61). In the present invention, the flow rate adjusting mechanism (250) includes a first flow rate adjusting valve (64a) provided in the first branch conduit (62a) and a second flow rate adjusting valve (62c) provided in the second branch conduit (62c). 2 flow rate control valve (64c), third flow rate control valve (64b) provided in the third branch pipe (62b), and the first flow rate control so that the physical quantity for control becomes a predetermined control target value. An opening degree control unit (220) for controlling the opening degree of the valve (64a), the second flow rate adjustment valve (64c), and the third flow rate adjustment valve (64b). In the present invention, the opening degree control unit (220) is configured such that the determination condition is satisfied when the third compressor (40b) sucks the refrigerant evaporated in the first evaporator (91). As the oil distribution operation, the opening of the first flow rate control valve (64a) and the third flow rate control valve (64b) is expanded more than that during the normal operation, and the second flow rate control valve (64c) One or both of the operations of reducing the opening as compared with the normal operation are executed, and the first flow rate control valve (64a) and the third flow rate control valve ( One or both of the operation of reducing the opening degree of 64b) than during the normal operation and the action of increasing the opening degree of the second flow rate control valve (64c) than during the normal operation are performed, and the third The compressor (40b) sucks the refrigerant evaporated in the second evaporator (81, 44). In the state, as the oil distribution operation when the determination condition is satisfied, the operation of expanding the opening of the first flow rate control valve (64a) than during the normal operation, and the second flow rate control valve (64c) And the first flow rate control valve as an oil distribution operation when one or both of the operations of reducing the opening of the third flow rate control valve (64b) than in the normal operation is performed and the determination condition is not satisfied. An operation of reducing the opening of (64a) than during the normal operation and an operation of expanding the opening of the second flow rate control valve (64c) and the third flow rate control valve (64b) than during the normal operation. Run one or both.

  In the fifth invention, the intermediate pressure refrigerant flowing through the third branch pipe (62b) is supplied to the compression chamber in the middle of compression of the third compressor (40b). The refrigeration oil that has flowed from the oil return circuit (49) into the main injection pipe (61) flows into the third compressor (40b) through the third branch pipe (62b). When the refrigerant flow rate in the third branch pipe (62b) increases or decreases, the amount of refrigerating machine oil supplied to the third compressor (40b) together with the intermediate pressure refrigerant also increases or decreases accordingly.

  The flow rate adjusting mechanism (250) of the fifth invention includes a first flow rate adjusting valve (64a), a second flow rate adjusting valve (64c), a third flow rate adjusting valve (64b), and an opening degree control unit (220). . The opening degree control unit (220) adjusts the opening degree of the first flow rate control valve (64a) in order to adjust the refrigerant flow rate in the first branch pipe (62a), and the refrigerant in the second branch pipe (62c). Adjust the opening of the second flow control valve (64c) to adjust the flow rate, and adjust the opening of the third flow control valve (64b) to adjust the refrigerant flow rate in the third branch pipe (62b). To do.

  In a state where the third compressor (40b) and the first compressor (40a) suck the refrigerant evaporated in the first evaporator (91), the pressure in the compression chamber in the middle of the compression in the third compressor (40b) is It is estimated that the pressure in the compression chamber during compression in the first compressor (40a) is substantially equal. Therefore, when the determination condition is satisfied in this state, the refrigerating machine oil is more likely to return to the second compressor (40c) than the first compressor (40a) and the third compressor (40b). Can be estimated. Therefore, when the determination condition is satisfied in this state, the opening degree control unit (220) of the fifth invention is normally operating the opening degree of the first flow rate control valve (64a) and the third flow rate control valve (64b). One or both of the operation for further expanding the operation and the operation for reducing the opening of the second flow rate adjustment valve (64c) than during the normal operation are performed as the oil distribution operation. On the other hand, if the determination condition is not satisfied in this state, the refrigeration oil is more likely to return to the first compressor (40a) and the third compressor (40b) than to the second compressor (40c). Can be estimated. Therefore, when the determination condition is not satisfied in this state, the opening degree control unit (220) of the present invention sets the opening degree of the first flow rate adjustment valve (64a) and the third flow rate adjustment valve (64b) more than during normal operation. One or both of the operation of reducing and the operation of expanding the opening of the second flow rate control valve (64c) than during the normal operation are executed as the oil distribution operation.

  In the injection circuit (60) of the fifth aspect of the invention, the intermediate pressure refrigerant and the refrigeration oil flowing through the main injection pipe (61) are fed into the first branch pipe (62a), the second branch pipe (62c), and the third branch. It flows into the pipe (62b). For this reason, the opening of the first flow rate control valve (64a) and the third flow rate control valve (64b) is larger than that during normal operation, and the opening amount of the second flow rate control valve (64c) is higher than during normal operation. The refrigerant flow rate in the first branch pipe (62a) and the third branch pipe (62b) is not only when both of the operations to reduce the pressure are executed, but also when only one of these two operations is executed. The refrigerant flow rate increases in the second branch pipe (62c). As a result, the flow rate of refrigeration oil flowing from the first branch pipe (62a) to the first compressor (40a) and the flow volume of refrigeration oil flowing from the third branch pipe (62b) to the third compressor (40b). And the flow rate of the refrigeration oil flowing into the second compressor (40c) from the second branch pipe (62c) decreases. Further, the opening of the first flow rate control valve (64a) and the third flow rate control valve (64b) is reduced more than that during normal operation, and the opening amount of the second flow rate control valve (64c) is lower than that during normal operation. The refrigerant flow rate in the first branch pipe (62a) and the third branch pipe (62b) decreases not only when both of the expanding actions are executed, but also when only one of these two actions is executed. And the refrigerant | coolant flow rate in a 2nd branch pipe (62c) increases. As a result, the flow rate of refrigeration oil flowing from the first branch pipe (62a) to the first compressor (40a) and the flow volume of refrigeration oil flowing from the third branch pipe (62b) to the third compressor (40b). And the flow rate of the refrigeration oil flowing into the second compressor (40c) from the second branch pipe (62c) increases.

  When the third compressor (40b) and the second compressor (40c) suck the refrigerant evaporated in the second evaporator (81, 44), the pressure of the compression chamber in the middle of the compression in the third compressor (40b) Is estimated to be approximately equal to the pressure in the compression chamber during compression in the second compressor (40c). Therefore, when the determination condition is satisfied in this state, the refrigerating machine oil is more likely to return to the second compressor (40c) and the third compressor (40b) than to the first compressor (40a). Can be estimated. Therefore, when the determination condition is satisfied in this state, the opening degree control unit (220) of the fifth aspect of the invention includes an operation for expanding the opening degree of the first flow rate control valve (64a) than during the normal operation, One or both of the operations of reducing the opening degree of the flow rate control valve (64c) and the third flow rate control valve (64b) than during the normal operation are executed as the oil distribution operation. On the other hand, if the determination condition is not satisfied in this state, the refrigerating machine oil is more likely to return to the first compressor (40a) than the second compressor (40c) and the third compressor (40b). Can be estimated. Therefore, when the determination condition is not satisfied in this state, the opening degree control unit (220) of the present invention performs the operation for reducing the opening degree of the first flow rate adjustment valve (64a) than during the normal operation, and the second flow rate adjustment. One or both of the operations of expanding the opening degree of the valve (64c) and the third flow rate control valve (64b) than during the normal operation are executed as the oil distribution operation.

  As described above, in the injection circuit (60) of the fifth aspect of the invention, the intermediate pressure refrigerant and the refrigeration oil flowing through the main injection pipe (61) are supplied to the first branch pipe (62a) and the second branch pipe (62c). ) And the third branch pipe (62b). For this reason, the operation of expanding the opening of the first flow control valve (64a) than during normal operation and the opening of the second flow control valve (64c) and the third flow control valve (64b) than during normal operation. The refrigerant flow rate in the first branch pipe (62a) increases and the second branch pipe (62a) increases not only when both contracting actions are executed but also when only one of these two actions is executed. The refrigerant flow rate in 62c) and the third branch pipe (62b) decreases. As a result, the flow rate of the refrigeration oil flowing from the first branch pipe (62a) to the first compressor (40a) increases, and the refrigeration flowing from the second branch pipe (62c) to the second compressor (40c). The flow rate of the machine oil and the flow rate of the refrigeration oil flowing into the third compressor (40b) from the third branch pipe (62b) are reduced. Further, the operation of reducing the opening of the first flow rate control valve (64a) than during normal operation, and the opening of the second flow rate control valve (64c) and the third flow rate control valve (64b) than during normal operation. Not only when both of the expanding operations are performed, but also when only one of these two operations is performed, the refrigerant flow rate in the first branch pipe (62a) decreases, and the second branch pipe (62c ) And the third branch pipe (62b) increase in refrigerant flow rate. As a result, the flow rate of the refrigeration oil flowing into the first compressor (40a) from the first branch pipe (62a) decreases, and the refrigeration flowing into the second compressor (40c) from the second branch pipe (62c). The flow rate of the machine oil and the flow rate of the refrigerating machine oil flowing into the third compressor (40b) from the third branch pipe (62b) increase.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the flow rate adjusting mechanism (250) sets the duration of the oil distribution operation to the time of the first compressor (40a). The pressure increases as the difference between the pressure of the suction refrigerant and the pressure of the suction refrigerant of the second compressor (40c) increases.

  In the sixth invention, the flow rate adjusting mechanism (250) adjusts the duration of the oil distribution operation. The greater the difference between the pressure of the suction refrigerant of the first compressor (40a) and the pressure of the suction refrigerant of the second compressor (40c), the greater the flow from the first branch pipe (62a) to the first compressor (40a). The difference between the flow rate of the refrigerating machine oil and the flow rate of the refrigerating machine oil flowing into the second compressor (40c) from the second branch pipe (62c) also increases. Therefore, the flow rate adjusting mechanism (250) extends the duration of the oil distribution operation as the difference between the suction refrigerant pressure of the first compressor (40a) and the suction refrigerant pressure of the second compressor (40c) increases. Then, the amount of the refrigerating machine oil flowing in during the oil distribution operation is increased to the lower one of the suction refrigerant pressures of the first compressor (40a) and the second compressor (40c).

  In a seventh aspect based on any one of the first to sixth aspects, the main injection pipe (61) is provided in the injection circuit (60) so as to expand the high-pressure refrigerant into an intermediate-pressure refrigerant. And an intermediate pressure side expansion valve (63), and a high-pressure liquid refrigerant flowing from the condenser (44,81) toward at least one of the first evaporator (91) and the second evaporator (81,44). Is connected to a heat exchanger (65) for supercooling that cools the intermediate pressure refrigerant flowing through the main injection pipe (61) by heat exchange, and is connected to the first compressor (40a) and the second compressor. When both compressors (40c) are in operation, the opening of the intermediate pressure side expansion valve (63) so that the pressure of the intermediate pressure refrigerant flowing through the main injection pipe (61) becomes a predetermined target pressure. Adjusting one of the first compressor (40a) and the second compressor (40c). When the other is stopped, the intermediate pressure side expansion valve (63) is opened so that the superheat degree of the intermediate pressure refrigerant flowing out of the supercooling heat exchanger (65) becomes a predetermined target superheat degree. An intermediate pressure control unit (225) for adjusting the degree is provided.

  In the seventh invention, the intermediate pressure side expansion valve (63) and the supercooling heat exchanger (65) are connected to the injection circuit (60). In the main injection pipe (61), the intermediate pressure refrigerant flowing out from the intermediate pressure side expansion valve (63) is supplied to the supercooling heat exchanger (65). In the supercooling heat exchanger (65), the high-pressure liquid refrigerant flowing out of the condenser (44, 81) is cooled by the intermediate-pressure refrigerant. The opening degree of the intermediate pressure side expansion valve (63) is adjusted by the intermediate pressure control unit (225). When the opening of the intermediate pressure side expansion valve (63) is changed, the pressure of the intermediate pressure refrigerant flowing through the main injection pipe (61) changes.

  Here, when both the first compressor (40a) and the second compressor (40c) are in operation, depending on the opening of the intermediate pressure side expansion valve (63), the intermediate flow through the main injection pipe (61) The pressure of the pressurized refrigerant may be lower than the pressure in the compression chamber in the middle of compression in one of the first compressor (40a) and the second compressor (40c), and in that case, an injection circuit ( 60) The refrigerant flows backward. Therefore, in this case, the intermediate pressure control section (225) of the seventh aspect of the invention provides the intermediate pressure side expansion valve (63) so that the pressure of the intermediate pressure refrigerant flowing through the main injection pipe (61) becomes a predetermined target pressure. Adjust the opening. If the target pressure is set to an appropriate value, the intermediate pressure refrigerant is reliably supplied to both the first compressor (40a) and the second compressor (40c).

  On the other hand, when only one of the first compressor (40a) and the second compressor (40c) is in operation and the other is stopped, the injection circuit (60 ) The refrigerant will not flow back to Therefore, in this case, the intermediate pressure control unit (225) according to the seventh aspect of the invention is arranged so that the superheat degree of the intermediate pressure refrigerant flowing out from the supercooling heat exchanger (65) becomes a predetermined target superheat degree. Adjust the opening of the expansion valve (63). If the target superheat degree is set to an appropriate value, the high-pressure liquid refrigerant is sufficiently cooled in the supercooling heat exchanger (65).

  In the present invention, the flow rate adjusting mechanism (250) intermittently performs the oil distribution operation. The flow rate adjusting mechanism (250) executes different operations as the oil distribution operation when the determination condition is satisfied and when the determination condition is not satisfied.

  As described above, when the determination condition is satisfied, it can be estimated that the refrigerating machine oil is more likely to return to the second compressor (40c) than the first compressor (40a). Therefore, in this case, the flow rate adjusting mechanism (250) of the present invention increases the refrigerant flow rate in the first branch pipe (62a) than during normal operation, and the refrigerant flow rate in the second branch pipe (62c) is normally operated. The operation of decreasing the inside is intermittently executed as the oil distribution operation. During this oil distribution operation, the flow rate of the refrigerating machine oil flowing into the first compressor (40a) from the first branch pipe (62a) increases more than during normal operation. Therefore, if this oil distribution operation is executed when the determination condition is satisfied, the amount of refrigerating machine oil stored in the first compressor (40a) that has decreased during the normal operation can be recovered.

  If the determination condition is not satisfied, it can be estimated that the refrigeration oil is more likely to return to the first compressor (40a) than to the second compressor (40c). Therefore, in this case, the flow rate adjusting mechanism (250) of the present invention reduces the refrigerant flow rate in the first branch pipe (62a) than during normal operation, and the refrigerant flow rate in the second branch pipe (62c) is normally operated. The operation to increase more than the inside is intermittently executed as the oil distribution operation. During the oil distribution operation, the flow rate of the refrigeration oil flowing from the second branch pipe (62c) to the second compressor (40c) is increased as compared with the normal operation. Therefore, if this oil distribution operation is executed when the determination condition is not satisfied, the amount of refrigerating machine oil stored in the second compressor (40c) that has decreased during the normal operation can be recovered.

  As described above, according to the present invention, the flow rate adjusting mechanism (250) performs the oil distribution operation, thereby reducing the amount of refrigerating machine oil stored in both the first compressor (40a) and the second compressor (40c). It can be secured sufficiently. Therefore, according to the present invention, damage due to poor lubrication of the first compressor (40a) and the second compressor (40c) can be avoided in advance, and the reliability of the refrigeration apparatus (10) is improved. be able to.

  In the second invention, the first flow rate control valve (64a) is provided in the first branch pipe (62a), and the second flow rate control valve (64c) is provided in the second branch pipe (62c). The opening degree of the flow rate control valve (64a) and the second flow rate control valve (64c) is adjusted by the opening degree control unit (220). Therefore, according to the present invention, the flow rate of the refrigerating machine oil supplied together with the intermediate pressure refrigerant from the first branch pipe (62a) to the first compressor (40a) and the second compression from the second branch pipe (62c). The flow rate of the refrigerating machine oil supplied to the compressor (40c) together with the intermediate pressure refrigerant can be reliably controlled by adjusting the opening of the first flow rate control valve (64a) and the second flow rate control valve (64c). It becomes possible.

  In the third aspect of the invention, the opening degree control unit (220) sets the control target value to the normal target value during normal operation, and sets the first flow rate control valve (64a) and the second flow rate control valve (64c). While adjusting the opening, set the control target value to a value different from the normal target value during the oil distribution operation, and adjust the opening of the first flow control valve (64a) and the second flow control valve (64c) To do. Therefore, according to the present invention, the opening degree of the first flow rate control valve (64a) and the second flow rate control valve (64c) during the oil distribution operation is reliably changed from the value during the normal operation, and the oil distribution operation is performed. The refrigerant flow rate in the first branch pipe (62a) and the second branch pipe (62c) can be reliably increased or decreased from the value during normal operation.

  In the refrigerant circuit (20) of the fifth aspect of the invention, the first compressor (40a) and the third compressor (40b) suck the refrigerant evaporated in the first evaporator (91), and the second compressor (40c ) Sucks the refrigerant evaporated in the second evaporator (81, 44), and the first compressor (40a) sucks the refrigerant evaporated in the first evaporator (91), and the second compressor (40c) ) And the third compressor (40b) can be switched between sucking the refrigerant evaporated in the second evaporator (81, 44). And the opening degree control part (220) of this invention performs two types of operation | movement suitable for each of these two states, oil distribution of the 3rd flow control valve (64b) corresponding to a 3rd compressor (40b). Execute as an operation. Therefore, according to the present invention, the third compressor (40b) that selectively sucks the refrigerant evaporated in the first evaporator (91) and the refrigerant evaporated in the second evaporator (81, 44) is also provided. A sufficient amount of refrigerating machine oil can be secured there, and damage to the third compressor (40b) due to insufficient lubrication can be avoided.

  In the sixth invention, the flow rate adjusting mechanism (250) increases the duration of the oil distribution operation by increasing the pressure difference between the suction refrigerant of the first compressor (40a) and the suction refrigerant of the second compressor (40c). Extend as you do. Therefore, according to the present invention, the duration of the oil distribution operation is increased as the difference between the refrigerating machine oil storage amount in the first compressor (40a) and the refrigerating machine oil storage amount in the second compressor (40c) increases. It can be made long, and a sufficient amount of refrigerating machine oil can be secured in both the first compressor (40a) and the second compressor (40c).

  In the seventh aspect of the invention, when both the first compressor (40a) and the second compressor (40c) are in operation, the intermediate pressure control unit (225) controls the intermediate pressure flowing through the main injection pipe (61). The opening degree of the intermediate pressure side expansion valve (63) is adjusted so that the pressure of the refrigerant becomes a predetermined target pressure. For this reason, if the target pressure is set to an appropriate value, the intermediate pressure refrigerant can be reliably supplied to both the first compressor (40a) and the second compressor (40c). Further, when only one of the first compressor (40a) and the second compressor (40c) is in operation, the intermediate pressure control unit (225) causes the intermediate pressure refrigerant to flow out of the supercooling heat exchanger (65). The degree of opening of the intermediate pressure side expansion valve (63) is adjusted so that the degree of superheat of becomes a predetermined target degree of superheat. For this reason, if the target superheat degree is set to an appropriate value, the high-pressure liquid refrigerant can be sufficiently cooled in the supercooling heat exchanger (65).

It is a refrigerant circuit diagram which shows the structure of the freezing apparatus of Embodiment 1. FIG. 3 is a refrigerant circuit diagram illustrating an operation during a cooling operation in a first mode in the refrigeration apparatus of Embodiment 1. FIG. 3 is a refrigerant circuit diagram illustrating an operation during a second mode cooling operation in the refrigeration apparatus of the first embodiment. 3 is a refrigerant circuit diagram illustrating an operation during normal heating operation in the refrigeration apparatus of Embodiment 1. FIG. It is a refrigerant circuit diagram which shows the operation | movement in the heat | fever recovery heating driving | operation in the refrigerating device of Embodiment 1. FIG. 2 is a block diagram illustrating a configuration of a controller according to the first embodiment. It is a figure which shows operation | movement of the time setting part of the controller of Embodiment 1. FIG. It is a control flowchart which shows the opening degree control operation | movement of the 1st injection motor operated by the controller of Embodiment 1. It is a control flowchart which shows the opening degree control operation | movement of the 2nd injection motor operated by the controller of Embodiment 1. It is a control flowchart which shows the opening degree control operation | movement of the 3rd injection motor operated by the controller of Embodiment 1. FIG. 6 is a block diagram illustrating a configuration of a controller according to a second embodiment. It is a control flowchart which shows the opening degree control operation | movement of the 1st injection motor valve which the motor operated valve control part of Embodiment 2 performs. It is a control flowchart which shows the operation | movement which a motor operated valve control part performs in step ST36 of FIG. It is a control flowchart which shows the opening degree control operation | movement of the 2nd injection motor operated by the motor operated valve control part of Embodiment 2. It is a control flowchart which shows the operation | movement which a motor operated valve control part performs in step ST56 of FIG. It is a control flowchart which shows the opening degree control operation | movement of the 3rd injection motor valve which the motor operated valve control part of Embodiment 2 performs. FIG. 17 is a control flow diagram showing an operation performed by the electric valve control unit in step ST86 of FIG. It is a control flowchart which shows the opening degree control operation | movement of the expansion valve for supercooling which the intermediate pressure control part of Embodiment 2 performs.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 of the Invention
A first embodiment of the present invention will be described. The refrigeration apparatus (10) of the present embodiment is installed, for example, in a convenience store or the like, and performs air conditioning in the store and cooling of a showcase or the like.

  As shown in FIG. 1, the refrigeration apparatus (10) of this embodiment includes an outdoor unit (11), an air conditioning unit (12), a refrigeration unit (13), a refrigeration unit (14), and a booster unit (15 ) And one each. The number of these units is merely an example. The outdoor unit (11) is installed outdoors. The air conditioning unit (12) is installed in a store such as a sales floor. The refrigeration unit (13) is installed in a refrigerated showcase and cools the interior of the refrigerator. The refrigeration unit (14) is installed in a refrigeration showcase and cools the interior of the refrigerator. The booster unit (15) is installed in the vicinity of the freezer showcase.

  The outdoor unit (11) has an outdoor circuit (30), the air conditioning unit (12) has an air conditioning circuit (80), the refrigeration unit (13) has a refrigeration circuit (90), and the refrigeration unit (14). The refrigeration circuit (100) and the booster unit (15) accommodate the booster circuit (110), respectively. In the refrigeration apparatus (10), the refrigerant circuit (20) is formed by connecting the air conditioning circuit (80), the refrigeration circuit (90), the refrigeration circuit (100), and the booster circuit (110) with piping. Is configured.

<Outdoor unit, outdoor circuit>
The outdoor circuit (30) includes a variable capacity compressor (40a) as a first compressor, a first fixed capacity compressor (40b) as a third compressor, and a second fixed capacity as a second compressor. And a compressor (40c). These three compressors (40a, 40b, 40c) are all hermetic scroll compressors.

  The electric motor of the variable capacity compressor (40a) is driven by alternating current supplied from an inverter not shown. When the output frequency of the inverter is changed, the rotational speed of the electric motor of the variable capacity compressor (40a) changes, and the operating capacity of the variable capacity compressor (40a) changes. On the other hand, the electric motors of the first fixed capacity compressor (40b) and the second fixed capacity compressor (40c) are driven by alternating current directly supplied from a commercial power source. In the first fixed-capacity compressor (40b) and the second fixed-capacity compressor (40c), the rotation speed of each electric motor becomes a value corresponding to the frequency of the alternating current supplied from the commercial power source, and each operating capacity is constant. Become.

  The outdoor circuit (30) is provided with an outdoor heat exchanger (44), an outdoor expansion valve (45), a receiver (46), and a supercooling heat exchanger (65) one by one. Two liquid side closing valves (55, 57) and two gas side closing valves (56, 58) are provided. Further, the outdoor circuit (30) is provided with three four-way switching valves (41, 42, 43).

  The outdoor heat exchanger (44) is a fin-and-tube heat exchanger, and exchanges heat between the refrigerant and outdoor air. The outdoor expansion valve (45) is an electronic expansion valve with a variable opening. The supercooling heat exchanger (65) is a plate heat exchanger having a plurality of first flow paths (66) and a plurality of second flow paths (67), and a refrigerant flowing through the first flow path (66). Heat exchange with the refrigerant flowing through the second flow path (67). Each four-way switching valve (41, 42, 43) has a first state in which the first port communicates with the third port and the second port communicates with the fourth port (state shown by a solid line in FIG. 1). Then, the first port communicates with the fourth port and the second port communicates with the third port (a state indicated by a broken line in FIG. 1).

  A discharge pipe (50) is connected to the discharge side of each compressor (40a, 40b, 40c). Specifically, the discharge pipe (50) has three inlet end branches, the first branch pipe is on the discharge side of the variable capacity compressor (40a), and the second branch pipe is the first fixed. A third branch pipe is connected to the discharge side of the second fixed capacity compressor (40c) on the discharge side of the capacity compressor (40b). The outlet end on the discharge side is connected to the first port of the first four-way switching valve (41). Each branch pipe of the discharge pipe (50) is provided with one oil separator (47a, 47b, 47c) and one check valve (CV1, CV2, CV3). In each branch pipe of the discharge pipe (50), check valves (CV1, CV2, CV3) are arranged downstream of the oil separators (47a, 47b, 47c). These check valves (CV1, CV2, CV3) allow refrigerant to flow from the compressor (40a, 40b, 40c) to the first four-way switching valve (41) and prevent refrigerant from flowing in the reverse direction. To do.

  A first suction pipe (51) is connected to the suction side of the variable capacity compressor (40a). Specifically, the first suction pipe (51) has two outlet end branches, the first branch pipe is connected to the suction side of the variable capacity compressor (40a), and the second branch pipe. Is connected to the fourth port of the third four-way selector valve (43). A check valve (CV4) is provided in the second branch pipe of the first suction pipe (51). The check valve (CV4) allows the refrigerant to flow toward the third four-way switching valve (43) and prevents the refrigerant from flowing in the reverse direction. The inlet end of the first suction pipe (51) is connected to the second gas side stop valve (58).

  The outlet end of the second suction pipe (52) is connected to the suction side of the first fixed capacity compressor (40b). The inlet end of the second suction pipe (52) is connected to the third port of the third four-way switching valve (43).

  A third suction pipe (53) is connected to the suction side of the second fixed capacity compressor (40c). Specifically, the third suction pipe (53) has two outlet end branches, the first branch pipe is connected to the suction side of the second fixed capacity compressor (40c), A branch pipe is connected to the third port of the third four-way switching valve (43). A check valve (CV5) is provided in the second branch pipe of the third suction pipe (53). The check valve (CV5) allows the refrigerant to flow toward the third four-way switching valve (43) and prevents the refrigerant from flowing in the reverse direction. The inlet end of the third suction pipe (53) is connected to the second port of the second four-way switching valve (42).

  The first four-way switching valve (41) has a second port at the fourth port of the second four-way switching valve (42), and a third port at the gas side end of the outdoor heat exchanger (44). The 4th port is connected to the 1st gas side stop valve (56), respectively. The second four-way switching valve (42) has its first port connected to the downstream side of each check valve (CV1, CV2, CV3) in the discharge pipe (50), and its third port is sealed. Yes. The first port of the third four-way selector valve (43) is connected to the downstream side of each check valve (CV1, CV2, CV3) in the discharge pipe (50) via the high pressure introduction pipe (38). .

  One end of the first connection pipe (31) is connected to the liquid side end of the outdoor heat exchanger (44). The other end of the first connection pipe (31) is connected to the top of the receiver (46). The first connection pipe (31) is provided with a solenoid valve (SV1) and a check valve (CV6) in this order from one end to the other end. The check valve (CV6) allows the refrigerant to flow from the outdoor heat exchanger (44) to the receiver (46) and prevents the refrigerant from flowing in the reverse direction.

  One end of the second connection pipe (32) is connected to the bottom of the receiver (46). The other end of the second connection pipe (32) is connected to the second liquid side stop valve (57). Moreover, the 1st flow path (66) of the heat exchanger for subcooling (65) is arrange | positioned in the middle of the 2nd connection piping (32).

  One end of a third connection pipe (33) is connected to the first liquid side stop valve (55). The other end of the third connection pipe (33) is connected between the check valve (CV6) and the receiver (46) in the first connection pipe (31). The third connection pipe (33) is provided with a check valve (CV7). The check valve (CV7) allows the refrigerant to flow from the first liquid side closing valve (55) to the receiver (46) and prevents the refrigerant from flowing in the reverse direction.

  One end of the fourth connection pipe (34) is connected between the receiver (46) and the supercooling heat exchanger (65) in the second connection pipe (32). The other end of the fourth connection pipe (34) is connected between the first liquid side stop valve (55) and the check valve (CV7) in the third connection pipe (33). The fourth connection pipe (34) is provided with a check valve (CV8). The check valve (CV8) allows the refrigerant to flow from one end to the other end of the fourth connection pipe (34) and prevents the refrigerant from flowing in the reverse direction.

  One end of the fifth connection pipe (35) is connected between the supercooling heat exchanger (65) and the second liquid side shut-off valve (57) in the second connection pipe (32). The other end of the fifth connection pipe (35) is connected between the outdoor heat exchanger (44) and the solenoid valve (SV1) in the first connection pipe (31). The fifth connection pipe (35) is provided with a check valve (CV9) and an outdoor expansion valve (45) in order from one end to the other end. The check valve (CV9) allows the refrigerant to flow from one end to the other end of the fifth connection pipe (35) and prevents the refrigerant from flowing in the reverse direction.

  One end of the sixth connection pipe (36) is connected between the check valve (CV9) and the outdoor expansion valve (45) in the fifth connection pipe (35). The other end of the sixth connection pipe (36) is connected between the check valve (CV6) and the receiver (46) in the first connection pipe (31). The sixth connection pipe (36) is provided with a check valve (CV10). The check valve (CV10) allows the refrigerant to flow from one end to the other end of the sixth connection pipe (36) and prevents the refrigerant from flowing in the reverse direction.

  One end of a seventh connection pipe (37) is connected to the upper part of the receiver (46). The other end of the seventh connection pipe (37) is connected to the downstream side of the supercooling heat exchanger (65) in the main injection pipe (61) of the injection circuit (60) described later. The seventh connection pipe (37) is provided with a solenoid valve (SV2).

  The outdoor circuit (30) is provided with an injection circuit (60). The injection circuit (60) includes a main injection pipe (61), a first injection pipe (62a) which is a first branch pipe, and a second injection pipe (62b) which is a third branch pipe. And a third injection conduit (62c) which is a second branch conduit.

  One end of the main injection pipe (61) is connected between the supercooling heat exchanger (65) and the second liquid side shut-off valve (57) in the second connection pipe (32). One end of each injection pipe (62a, 62b, 62c) is connected to the other end of the main injection pipe (61). The main injection pipe (61) has, in order from one end to the other, the second flow path (67) of the supercooling heat exchanger (65) and the supercooling expansion valve that is an intermediate pressure side expansion valve. (63) is provided. The supercooling expansion valve (63) is an electronic expansion valve having a variable opening.

  The other end of the first injection pipe (62a) is for the variable capacity compressor (40a), the other end of the second injection pipe (62b) is for the first fixed capacity compressor (40b), and for the third injection. The other end of the pipe (62c) is connected to the second fixed capacity compressor (40c). In the variable capacity compressor (40a), the first injection pipe (62a) can communicate with the compression chamber in the middle of compression. In the first fixed capacity compressor (40b), the second injection pipe (62b) can communicate with the compression chamber in the middle of compression. In the second fixed capacity compressor (40c), the third injection conduit (62c) can communicate with the compression chamber in the middle of compression.

  The first injection conduit (62a) is provided with a first injection motor-operated valve (64a) which is a first flow control valve. The second injection conduit (62b) is provided with a second injection motor-operated valve (64b) which is a third flow rate adjusting valve. The third injection conduit (62c) is provided with a third injection motor-operated valve (64c) which is a second flow rate adjusting valve. Each injection motorized valve (64a, 64b, 64c) is an electronic expansion valve with variable opening, and adjusts the flow rate of refrigerant supplied from the injection circuit (60) to each compressor (40a, 40b, 40c). To do.

  An oil return pipe (54) is connected to the injection circuit (60). The oil return pipe (54) has an outlet end connected to the downstream side of the supercooling heat exchanger (65) in the main injection pipe (61) of the injection circuit (60). The oil return pipe (54) has an inlet end branching into three branch pipes, the first branch pipe being the first oil separator (47a) and the second branch pipe being the second oil separator. A third branch pipe is connected to the third oil separator (47c) to the vessel (47b). Each branch pipe is provided with a check valve (CV11, CV12, CV13) and a capillary tube (48a, 48b, 48c). In each branch pipe, the capillary tubes (48a, 48b, 48c) are arranged downstream of the check valves (CV11, CV12, CV13). Each check valve (CV11, CV12, CV13) allows the flow of the refrigerating machine oil flowing out from the oil separators (47a, 47b, 47c), and blocks the flow of the refrigerating machine oil in the reverse direction. The oil return pipe (54) and the three oil separators (47a, 47b, 47c) provided in the discharge pipe (50) constitute an oil return circuit (49).

  The outdoor circuit (30) is provided with a plurality of temperature sensors and pressure sensors.

  Each branch pipe of the discharge pipe (50) has one discharge pipe temperature sensor (74a, 74b, 74c) between the compressor (40a, 40b, 40c) and the oil separator (47a, 47b, 47c). It is attached. The first discharge pipe temperature sensor (74a) measures the temperature of the branch pipe connected to the variable capacity compressor (40a) as a physical quantity indicating the temperature of the refrigerant discharged from the variable capacity compressor (40a). The second discharge pipe temperature sensor (74b) measures the temperature of the branch pipe connected to the first fixed capacity compressor (40b) as a physical quantity indicating the temperature of the refrigerant discharged from the first fixed capacity compressor (40b). To do. The third discharge pipe temperature sensor (74c) measures the temperature of the branch pipe connected to the second fixed capacity compressor (40c) as a physical quantity indicating the temperature of the refrigerant discharged from the second fixed capacity compressor (40c). To do. A high pressure sensor (70) is connected to the discharge pipe (50). The high pressure sensor (70) measures the pressure of the refrigerant discharged from each compressor (40a, 40b, 40c) and flowing through the discharge pipe (50).

  A first suction pipe (51) temperature sensor (75) is attached to the assembly portion of the first suction pipe (51). The first suction pipe (51) temperature sensor (75) uses the first suction pipe (51) as a physical quantity indicating the temperature of the refrigerant flowing in the first suction pipe (51) toward the variable capacity compressor (40a). Measure the temperature. The first low pressure sensor (71) is connected to the assembly portion of the first suction pipe (51). The first low pressure sensor (71) measures the pressure of the refrigerant flowing in the first suction pipe (51) toward the variable capacity compressor (40a).

  A second suction pipe temperature sensor (76) is attached to the assembly portion of the third suction pipe (53). The second suction pipe temperature sensor (76) uses the temperature of the third suction pipe (53) as a physical quantity indicating the temperature of the refrigerant flowing in the third suction pipe (53) toward the second fixed capacity compressor (40c). Measure. The second low pressure sensor (72) is connected to the assembly portion of the third suction pipe (53). The second low pressure sensor (72) measures the pressure of the refrigerant flowing in the third suction pipe (53) toward the second fixed capacity compressor (40c).

  An injection pipe temperature sensor (77) is attached downstream of the supercooling heat exchanger (65) in the main injection pipe (61) of the injection circuit (60). The injection pipe temperature sensor (77) measures the temperature of the injection circuit (60) as a physical quantity indicating the temperature of the refrigerant flowing in the injection circuit (60) toward the compressors (40a, 40b, 40c). An intermediate pressure sensor (73) is connected to the downstream side of the supercooling heat exchanger (65) in the main injection pipe (61) of the injection circuit (60). The intermediate pressure sensor (73) measures the pressure of the refrigerant flowing toward the compressors (40a, 40b, 40c) in the main injection pipe (61) of the injection circuit (60).

  The outdoor unit (11) is provided with an outdoor fan (79) that is a heat source side fan and an outdoor temperature sensor (78). The outdoor fan (79) supplies outdoor air to the outdoor heat exchanger (44). The outdoor temperature sensor (78) measures the temperature of the outdoor air sent to the outdoor heat exchanger (44) by the outdoor fan (79).

<Air conditioning unit, air conditioning circuit>
The air-conditioning circuit (80) has a liquid-side end connected to the first liquid-side shut-off valve (55) of the outdoor circuit (30) via the first liquid-side connecting pipe (21), and a gas-side end thereof connected to the first gas. Each is connected to the first gas side shut-off valve (56) of the outdoor circuit (30) via the side connection pipe (22). In the air conditioning circuit (80), an air conditioning expansion valve (82) and an air conditioning heat exchanger (81) that are use side heat exchangers are provided in that order from the liquid side end to the gas side end. Yes. The air conditioning expansion valve (82) is an electronic expansion valve with variable opening. The air conditioner heat exchanger (81) is a fin-and-tube heat exchanger, and exchanges heat between the refrigerant and room air.

  Two temperature sensors are attached to the air conditioning circuit (80). A gas refrigerant temperature sensor (84) is attached between the air-conditioning heat exchanger (81) and the gas side end in the air-conditioning circuit (80). The gas refrigerant temperature sensor (84) is a pipe constituting the air conditioning circuit (80) as a physical quantity indicating the temperature of the refrigerant flowing between the air conditioning heat exchanger (81) and the gas side end in the air conditioning circuit (80). Measure the temperature. A heat exchanger temperature sensor (85) is attached to the heat transfer tubes constituting the heat exchanger for air conditioning (81). The heat exchanger temperature sensor (85) determines the temperature of the heat transfer tube as a physical quantity indicating the temperature of the refrigerant (that is, the evaporation temperature or the condensation temperature) undergoing phase change in the heat transfer tube of the air conditioning heat exchanger (81). measure.

  The air conditioning unit (12) is provided with an air conditioning fan (83) and an indoor temperature sensor (86). The air conditioning fan (83) supplies room air from the sales floor to the air conditioning heat exchanger (81). The indoor temperature sensor (86) measures the temperature of indoor air sent to the air conditioning heat exchanger (81) by the air conditioning fan (83).

<Refrigeration unit, refrigeration circuit>
The refrigeration circuit (90) has its liquid side end connected to the second liquid side shut-off valve (57) of the outdoor circuit (30) via the second liquid side connecting pipe (23), and its gas side end to the second gas. Each is connected to the second gas side shut-off valve (58) of the outdoor circuit (30) via the side connection pipe (24). In the refrigeration circuit (90), a refrigeration solenoid valve (93), a refrigeration expansion valve (92), and a refrigeration heat exchanger (91) are provided in that order from the liquid side end to the gas side end. It has been. The refrigeration expansion valve (92) is a temperature automatic expansion valve provided with a temperature sensitive cylinder. The refrigeration heat exchanger (91) is a fin-and-tube heat exchanger, and exchanges heat between the refrigerant and the air inside the refrigerated showcase.

  The refrigeration unit (13) is provided with a refrigeration fan (94) and a refrigeration internal temperature sensor (95). The refrigeration fan (94) supplies the air inside the refrigerated showcase to the refrigeration heat exchanger (91). The refrigerator internal temperature sensor (95) measures the temperature of the internal air sent to the refrigerator heat exchanger (91) by the refrigerator fan (94).

<Refrigeration unit, refrigeration circuit>
The refrigeration circuit (100) has its liquid side end connected to the second liquid side shut-off valve (57) of the outdoor circuit (30) via the second liquid side connection pipe (23), and its gas side end connected to the pipe. Are respectively connected to the booster circuits (110). The refrigeration circuit (100) is provided with a refrigeration solenoid valve (103), a refrigeration expansion valve (102), and a refrigeration heat exchanger (101) in that order from the liquid side end to the gas side end. It has been. The freezing expansion valve (102) is a temperature automatic expansion valve provided with a temperature sensitive cylinder. The refrigeration heat exchanger (101) is a fin-and-tube heat exchanger, and exchanges heat between the refrigerant and the internal air of the refrigeration showcase.

  The refrigeration unit (14) is provided with a refrigeration fan (104) and a freezer internal temperature sensor (105). The freezing fan (104) supplies the air in the freezer showcase to the freezing heat exchanger (101). The freezer compartment temperature sensor (105) measures the temperature of the compartment air sent to the freezer heat exchanger (101) by the freezer fan (104).

<Booster unit, booster circuit>
One end of the booster circuit (110) is connected to the gas side end of the refrigeration circuit (100) via a pipe, and the other end is connected to the second gas of the outdoor circuit (30) via the second gas side connecting pipe (24). Each is connected to a side closing valve (58). The booster circuit (110) is provided with a booster compressor (111), an oil separator (112), and a check valve (CV14) in order from one end to the other end.

  The booster compressor (111) is a hermetic scroll compressor. The electric motor of the booster compressor (111) is driven by alternating current supplied from an inverter not shown. When the output frequency of the inverter is changed, the rotational speed of the electric motor of the booster compressor (111) changes, and the operating capacity of the booster compressor (111) changes. The check valve (CV14) allows the refrigerant to flow from the booster compressor (111) toward the second gas side communication pipe (24) and prevents the refrigerant from flowing in the reverse direction.

  The booster circuit (110) is provided with an oil return pipe (113) and a bypass pipe (114). One end of the oil return pipe (113) is connected to the oil separator (112), and the other end is connected to the upstream side of the booster compressor (111) in the booster circuit (110). The oil return pipe 2 is provided with a capillary tube (115). One end of the bypass pipe (114) is upstream of the booster compressor (111) in the booster circuit (110), and the other end is the oil separator (112) and check valve (CV14) in the booster circuit (110). Connected between. The bypass pipe (114) is provided with a check valve (CV15). The check valve (CV15) allows the refrigerant to flow from one end to the other end of the bypass pipe (114) and prevents the refrigerant from flowing in the reverse direction.

<controller>
A controller (200) receives the detection value of each sensor (70-78) mentioned above, and controls operation | movement of a freezing apparatus (10) based on them.

  For example, in the controller (200), the opening adjustment of each injection motor operated valve (64a, 64b, 64c) is performed based on the detection value of each discharge pipe temperature sensor (74a, 74b, 74c). That is, the controller (200) uses the temperature of the refrigerant discharged from each compressor (40a, 40b, 40c) as a physical quantity for control, and the actual value detected by each discharge pipe temperature sensor (74a, 74b, 74c). Is adjusted to the predetermined control target value by adjusting the opening degree of each injection motor operated valve (64a, 64b, 64c).

  Specifically, the controller (200) uses the temperature of the refrigerant discharged from the variable capacity compressor (40a) as the first physical quantity for control, and the detected value of the first discharge pipe temperature sensor (74a) falls within a predetermined temperature range. The opening degree of the first injection motor-operated valve (64a) is adjusted so that The controller (200) uses the temperature of the refrigerant discharged from the first fixed capacity compressor (40b) as the second physical quantity for control, and the detected value of the second discharge pipe temperature sensor (74b) falls within a predetermined temperature range. The opening degree of the second injection motor-operated valve (64b) is adjusted as follows. The controller (200) uses the temperature of the refrigerant discharged from the second fixed capacity compressor (40c) as the third physical quantity for control, and the detected value of the third discharge pipe temperature sensor (74c) falls within a predetermined temperature range. The opening degree of the third injection motor-operated valve (64c) is adjusted as follows.

  When the temperature of the refrigerant discharged from the compressor (40a, 40b, 40c) (that is, the detected value of the discharge pipe temperature sensor (74a, 74b, 74c)) exceeds the predetermined temperature range, the controller (200) Increase the opening of the injection motor operated valve (64a, 64b, 64c) corresponding to the compressor (40a, 40b, 40c) and increase the supply amount of intermediate pressure refrigerant to the compressor (40a, 40b, 40c) As a result, the temperature of the refrigerant discharged from the compressor (40a, 40b, 40c) is lowered.

  On the other hand, when the temperature of the refrigerant discharged from the compressor (40a, 40b, 40c) is below a predetermined temperature range, the controller (200) displays the injection motor-operated valve corresponding to the compressor (40a, 40b, 40c). The refrigerant discharged from the compressor (40a, 40b, 40c) is reduced by reducing the opening of (64a, 64b, 64c) and reducing the amount of intermediate pressure refrigerant supplied to the compressor (40a, 40b, 40c). Increase the temperature.

  Here, since the operating frequency of the variable capacity compressor (40a) (that is, the frequency of the alternating current supplied to the electric motor) is variable, the temperature of the discharged refrigerant tends to be lower than a predetermined temperature range. . This is because when the operating frequency of the variable capacity compressor (40a) is lowered, the time during which the compression chamber in the middle of compression communicates with the first injection pipe (62a) becomes longer, and from the first injection pipe (62a) This is because the amount of intermediate pressure refrigerant flowing into the compression chamber increases.

  Therefore, when the operating capacity of the variable capacity compressor (40a) is reduced (that is, when the operating frequency is lowered), the temperature of the discharged refrigerant is lowered, so that the first injection motor operated valve according to this temperature change. Reduce the opening of (64a). Thereby, a large amount of intermediate pressure refrigerant is prevented from flowing into the compression chamber in the middle of compression of the variable capacity compressor (40a).

  As shown in FIG. 6, the controller (200) includes a target setting unit (205), an adjustment unit (210), and a time setting unit (215). Details of the target setting unit (205), the adjustment unit (210), and the time setting unit (215) will be described later.

  The controller (200) constitutes an opening degree control unit that individually controls the opening degree of each injection motor operated valve (64a, 64b, 64c). The controller (200) constitutes a flow rate adjusting mechanism (250) together with the injection motor operated valves (64a, 64b, 64c) provided in the injection circuit (60).

-Driving action-
The operation of the refrigeration apparatus (10) will be described. The refrigeration apparatus (10) of the present embodiment performs various operations. Here, the cooling operation, the normal heating operation, and the heat recovery heating operation among the operations performed in the refrigeration apparatus (10) will be described. Note that, as will be described later, in the cooling operation, the normal heating operation, and the heat recovery heating operation, the refrigerator air (13) and the refrigeration unit (14) cool the internal air.

<Cooling operation>
The cooling operation of the refrigeration apparatus (10) will be described with reference to FIG.

  In the refrigerant circuit (20) during the cooling operation, a refrigeration cycle is performed by circulating the refrigerant. At that time, in the refrigerant circuit (20). The outdoor heat exchanger (44) operates as a condenser (that is, a radiator), and the heat exchanger for air conditioning (81), the heat exchanger for refrigeration (91), and the heat exchanger for refrigeration (101) are evaporators. Works as. In the heat exchanger for air conditioning (81) operating as the second evaporator, the evaporation temperature of the refrigerant is set to 5 ° C., for example. In the refrigeration heat exchanger (91) operating as the first evaporator, the evaporation temperature of the refrigerant is set to, for example, −5 ° C. In the refrigeration heat exchanger (101), the evaporation temperature of the refrigerant is set to, for example, -20 ° C.

  In the cooling operation, the first four-way switching valve (41) and the second four-way switching valve (42) are set to the first state. The third four-way switching valve (43) is set to the first state when the refrigerant flowing into the outdoor circuit (30) from the second gas side communication pipe (24) is sucked into the first fixed capacity compressor (40b). When the refrigerant flowing into the outdoor circuit (30) from the first gas side communication pipe (22) is sucked into the first fixed capacity compressor (40b), the second state is set. Here, a case where the third four-way selector valve (43) is set to the first state will be described as an example.

  In the cooling operation, the outdoor expansion valve (45) is set to a fully closed state, and the air conditioning expansion valve (82), the supercooling expansion valve (63), the first injection motor operated valve (64a), and the second injection. The opening degree of the motor operated valve (64b) and the third injection motor operated valve (64c) is appropriately adjusted. The controller (200) adjusts the opening degree of the air conditioning expansion valve (82), each injection motor operated valve (64a, 64b, 64c), and the supercooling expansion valve (63). Further, in the cooling operation, the solenoid valve (SV1) is opened and the solenoid valve (SV2) is closed.

  The high-pressure refrigerant discharged from the variable capacity compressor (40a), the first fixed capacity compressor (40b), and the second fixed capacity compressor (40c) to the discharge pipe (50) is the first four-way switching valve (41). It flows into the outdoor heat exchanger (44) through, and dissipates heat to the outdoor air supplied by the outdoor fan (79) to condense. The high-pressure refrigerant that has flowed out of the outdoor heat exchanger (44) passes through the receiver (46) and flows into the second connection pipe (32). After that, a part of the refrigerant flowing through the second connection pipe (32) flows into the first liquid side connection pipe (21) through the fourth connection pipe (34), and the rest flows through the supercooling heat exchanger ( 65) flows into the first flow path (66). The refrigerant flowing into the first flow path (66) of the supercooling heat exchanger (65) is cooled by the intermediate pressure refrigerant flowing through the second flow path (67), and the degree of supercooling increases. A part of the refrigerant flowing out of the first flow path (66) of the supercooling heat exchanger (65) and flowing through the second connection pipe (32) flows into the injection circuit (60), and the rest is the second. It flows into the liquid side connecting pipe (23).

  The high-pressure refrigerant that has flowed into the first liquid side communication pipe (21) is decompressed when passing through the air conditioning expansion valve (82) and then flows into the air conditioning heat exchanger (81), and the air conditioning fan (83) It absorbs heat from the room air supplied by and evaporates. The air conditioning unit (12) supplies the air cooled in the air conditioning heat exchanger (81) to the room. The refrigerant flowing out of the air conditioning heat exchanger (81) flows into the outdoor circuit (30) through the first gas side communication pipe (22), and then switches to the first four-way switching valve (41) and the second four-way switching. After passing through the valve (42) in order, it flows into the third suction pipe (53). The refrigerant flowing into the third suction pipe (53) is sucked into the second fixed capacity compressor (40c). The second fixed capacity compressor (40c) compresses the sucked refrigerant and then discharges it to the discharge pipe (50).

  Part of the high-pressure refrigerant that has flowed into the second liquid side communication pipe (23) flows into the refrigeration circuit (90), and the rest flows into the refrigeration circuit (100).

  The refrigerant flowing into the refrigeration circuit (90) is decompressed when passing through the refrigeration expansion valve (92), then flows into the refrigeration heat exchanger (91), and is supplied by the refrigeration fan (94). It absorbs heat from the internal air and evaporates. The refrigeration unit (13) supplies the air cooled in the refrigeration heat exchanger (91) to the inside of the refrigerated showcase. The refrigerant that has flowed out of the refrigeration heat exchanger (91) flows into the second gas side communication pipe (24).

  The refrigerant flowing into the refrigeration circuit (100) is decompressed when passing through the refrigeration expansion valve (102), then flows into the refrigeration heat exchanger (101), and is supplied by the refrigeration fan (104). It absorbs heat from the internal air and evaporates. The refrigeration unit (14) supplies the air cooled in the refrigeration heat exchanger (101) to the inside of the refrigeration showcase. The refrigerant flowing out of the refrigeration heat exchanger (101) flows into the booster circuit (110) and is sucked into the booster compressor (111). The booster compressor (111) compresses the sucked refrigerant and discharges it. The refrigerant discharged from the booster compressor (111) flows into the second gas side communication pipe (24) and merges with the refrigerant flowing out from the refrigeration circuit (90).

  The refrigerant flowing through the second gas side communication pipe (24) flows into the first suction pipe (51) of the outdoor circuit (30). Part of the refrigerant flowing through the first suction pipe (51) is sucked into the variable capacity compressor (40a), and the rest passes through the third four-way switching valve (43) and the second suction pipe (52) in this order. It is sucked into the first fixed capacity compressor (40b). Both the variable capacity compressor (40a) and the first fixed capacity compressor (40b) compress the sucked refrigerant and discharge it to the discharge pipe (50).

  The high-pressure liquid refrigerant that has flowed into the injection circuit (60) is reduced in pressure when passing through the supercooling expansion valve (63) to become a gas-liquid two-phase intermediate pressure refrigerant. The intermediate pressure refrigerant flows into the second flow path (67) of the supercooling heat exchanger (65), absorbs heat from the refrigerant flowing through the first flow path (66), and evaporates. The intermediate pressure refrigerant that has flowed out of the supercooling heat exchanger (65) passes through the main injection pipe (61) and flows into the three injection pipes (62a, 62b, 62c). It flows into the compression chamber in the middle of compression in the compressor (40a, 40b, 40c).

  By the way, in each compressor (40a, 40b, 40c), refrigeration oil is stored in the casing, and this refrigeration oil is utilized for lubrication of a compression mechanism. A part of the refrigerating machine oil used for lubricating the compression mechanism is discharged from the compressors (40a, 40b, 40c) together with the compressed high-pressure refrigerant.

  The refrigeration oil contained in the refrigerant (discharged refrigerant) discharged from the variable capacity compressor (40a) is separated from the gas refrigerant in the oil separator (47a). The refrigeration oil contained in the refrigerant (discharged refrigerant) discharged from the first fixed capacity compressor (40b) is separated from the gas refrigerant in the oil separator (47b). The refrigeration oil contained in the refrigerant (discharged refrigerant) discharged from the second fixed capacity compressor (40c) is separated from the gas refrigerant in the oil separator (47c).

  The refrigeration oil separated from the discharged refrigerant in each oil separator (47a, 47b, 47c) flows into the main injection pipe (61) through the oil return pipe (54). The refrigeration oil that has flowed into the main injection pipe (61) is divided into three injection pipes (62a, 62b, 62c) along with the intermediate pressure refrigerant, and then flows into each compressor (40a, 40b, 40c). It flows into the compression chamber in the middle of compression.

  The refrigeration apparatus (10) of the present embodiment can execute the first mode cooling operation shown in FIG. 2 and the second mode cooling operation shown in FIG.

  In the cooling operation in the first mode, the third four-way switching valve (43) is set to the first state (see FIG. 2). As described above, in the cooling operation in the first mode, the variable capacity compressor (40a) and the first fixed capacity compressor (40b) suck the low-pressure refrigerant flowing through the first suction pipe (51), and the second fixed capacity. The compressor (40c) sucks the low-pressure refrigerant flowing through the third suction pipe (53). That is, in the cooling operation in the first mode, the variable capacity compressor (40a) and the first fixed capacity compressor (40b) suck the refrigerant evaporated in the refrigeration heat exchanger (91), and the second fixed capacity compressor (40c) sucks the refrigerant evaporated in the heat exchanger (81) for air conditioning.

  In the cooling operation in the second mode, the third four-way switching valve (43) is set to the second state (see FIG. 3). In the cooling operation in the second mode, the variable capacity compressor (40a) sucks the low-pressure refrigerant flowing through the first suction pipe (51), and the first fixed capacity compressor (40b) and the second fixed capacity compressor (40c). Sucks the low-pressure refrigerant flowing through the third suction pipe (53). That is, in the cooling operation in the second mode, the variable capacity compressor (40a) sucks the refrigerant evaporated in the refrigeration heat exchanger (91), and the first fixed capacity compressor (40b) and the second fixed capacity compressor. (40c) sucks the refrigerant evaporated in the heat exchanger (81) for air conditioning.

<Normal heating operation>
The normal heating operation of the refrigeration apparatus (10) will be described with reference to FIG.

  In the refrigerant circuit (20) during normal heating operation, a refrigeration cycle is performed by circulating the refrigerant. At that time, usually in the heating circuit. The heat exchanger for air conditioning (81) operates as a condenser (that is, a radiator), and the outdoor heat exchanger (44), the refrigeration heat exchanger (91), and the refrigeration heat exchanger (101) are evaporators. Works as. In the outdoor heat exchanger (44) operating as the second evaporator, the refrigerant evaporation temperature is set to 0 ° C., for example. In the refrigeration heat exchanger (91) operating as the first evaporator, the evaporation temperature of the refrigerant is set to, for example, −5 ° C. In the refrigeration heat exchanger (101), the evaporation temperature of the refrigerant is set to, for example, -20 ° C. Note that the evaporation temperature of the refrigerant in the outdoor heat exchanger (44) changes according to the outdoor air temperature. For this reason, the evaporating temperature of the refrigerant in the outdoor heat exchanger (44) may be set to, for example, −10 ° C. in the severe winter season when the outdoor temperature is below freezing.

  Specifically, in the normal heating operation, the first four-way switching valve (41) is set to the second state, and the second four-way switching valve (42) is set to the first state. Here, a case where the third four-way selector valve (43) is set to the first state will be described as an example.

  In the normal heating operation, the outdoor expansion valve (45), the air conditioning expansion valve (82), the supercooling expansion valve (63), the first injection motor valve (64a), and the second injection motor valve (64b) And the opening degree of the third injection motor-operated valve (64c) is appropriately adjusted. In the controller (200), the expansion valve control section (201) adjusts the opening of the outdoor expansion valve (45), and the discharge temperature control section (203) opens the opening of each injection motor operated valve (64a, 64b, 64c). The supercooling control unit (204) adjusts the opening degree of the supercooling expansion valve (63). Furthermore, in the normal heating operation, both solenoid valves (SV1, SV2) are closed.

  The high-pressure refrigerant discharged from the variable capacity compressor (40a), the first fixed capacity compressor (40b), and the second fixed capacity compressor (40c) to the discharge pipe (50) is the first four-way switching valve (41). Passes through the first gas side shut-off valve (56) and then flows into the air conditioning heat exchanger (81), dissipates heat to the indoor air supplied by the air conditioning fan (83), and condenses. The air conditioning unit (12) supplies the air heated in the air conditioning heat exchanger (81) to the room.

  The refrigerant flowing out of the air conditioning heat exchanger (81) passes through the air conditioning expansion valve (82) and then flows into the outdoor circuit (30) through the first liquid side connecting pipe (21), and then the third connection. It flows into the receiver (46) through the pipe (33). The refrigerant flowing out from the receiver (46) to the second connection pipe (32) flows into the first flow path (66) of the supercooling heat exchanger (65) and flows through the second flow path (67). Cooling by the pressure refrigerant increases the degree of supercooling. A part of the refrigerant flowing out from the first flow path (66) of the supercooling heat exchanger (65) flows into the fifth connection pipe (35), and the rest continues to flow through the second connection pipe (32). . A part of the refrigerant flowing through the second connection pipe (32) toward the second liquid side shut-off valve (57) flows into the injection circuit (60), and the remaining part is the second liquid side connection pipe (23). Flow into.

  The refrigerant flowing into the fifth connection pipe (35) is decompressed when passing through the outdoor expansion valve (45), then flows into the outdoor heat exchanger (44), and is supplied by the outdoor fan (79). It absorbs heat and evaporates. The refrigerant flowing out of the outdoor heat exchanger (44) sequentially passes through the first four-way switching valve (41) and the second four-way switching valve (42), and then flows into the third suction pipe (53) to be second fixed. It is sucked into the capacity compressor (40c). The second fixed capacity compressor (40c) compresses the sucked refrigerant and then discharges it to the discharge pipe (50).

  Part of the high-pressure refrigerant that has flowed into the second liquid side communication pipe (23) flows into the refrigeration circuit (90), and the rest flows into the refrigeration circuit (100). The refrigerant flowing into the refrigeration circuit (90) is reduced in pressure when passing through the refrigeration expansion valve (92), and then flows into the refrigeration heat exchanger (91) in the same manner as during the cooling operation. It absorbs heat from the internal air supplied by (94) and evaporates, and then flows into the second gas side connecting pipe (24). On the other hand, the refrigerant flowing into the refrigeration circuit (100) is decompressed when passing through the refrigeration expansion valve (102), and then flows into the refrigeration heat exchanger (101) in the same manner as during the cooling operation. It absorbs heat from the internal air supplied by the fan (104) and evaporates, and is then compressed by the booster compressor (111) and then flows into the second gas side connecting pipe (24). A part of the refrigerant flowing through the second gas side connecting pipe (24) is sucked into the variable capacity compressor (40a) and the rest is the first fixed capacity compressor, as in the cooling operation in the first mode. Inhaled to (40b). Both the variable capacity compressor (40a) and the first fixed capacity compressor (40b) compress the sucked refrigerant and discharge it to the discharge pipe (50).

  The refrigerant flowing into the injection circuit (60) is depressurized when passing through the supercooling expansion valve (63) and then flows into the second flow path (67) of the supercooling heat exchanger (65). It absorbs heat from the refrigerant flowing through the first flow path (66) and evaporates. The intermediate pressure refrigerant that has flowed out of the supercooling heat exchanger (65) is mixed with the refrigeration oil supplied from the oil separators (47a, 47b, 47c) through the oil return pipe (54), and then each compressor. It flows into the compression chamber in the middle of compression at (40a, 40b, 40c).

  The refrigeration apparatus (10) of the present embodiment can execute a heating operation in the first mode and a heating operation in the second mode.

  In the heating operation in the first mode, the third four-way switching valve (43) is set to the first state (see FIG. 4). As described above, in the heating operation in the first mode, the variable capacity compressor (40a) and the first fixed capacity compressor (40b) suck the low-pressure refrigerant flowing through the first suction pipe (51), and the second fixed capacity. The compressor (40c) sucks the low-pressure refrigerant flowing through the third suction pipe (53). That is, in the heating operation in the first mode, the variable capacity compressor (40a) and the first fixed capacity compressor (40b) suck the refrigerant evaporated in the refrigeration heat exchanger (91), and the second fixed capacity compressor. (40c) sucks the refrigerant evaporated in the outdoor heat exchanger (44).

  In the heating operation in the second mode, the third four-way switching valve (43) is set to the second state. In the heating operation in the second mode, the variable capacity compressor (40a) sucks the low-pressure refrigerant flowing through the first suction pipe (51), and the first fixed capacity compressor (40b) and the second fixed capacity compressor (40c). Sucks the low-pressure refrigerant flowing through the third suction pipe (53). That is, in the heating operation in the second mode, the variable capacity compressor (40a) sucks the refrigerant evaporated in the refrigeration heat exchanger (91), and the first fixed capacity compressor (40b) and the second fixed capacity compressor. (40c) sucks the refrigerant evaporated in the outdoor heat exchanger (44).

<Heat recovery heating operation>
The heat recovery heating operation of the refrigeration apparatus (10) will be described with reference to FIG.

  In the refrigerant circuit (20) during the heat recovery heating operation, a refrigeration cycle is performed by circulating the refrigerant. At that time, in the heat recovery heating operation, the heat exchanger for air conditioning (81) operates as a condenser (that is, a radiator), and the heat exchanger for refrigeration (91) and the heat exchanger for refrigeration (101) evaporate. The outdoor heat exchanger (44) is deactivated. In the heat recovery operation, the outdoor fan (79) is stopped because the outdoor heat exchanger (44) is stopped. Further, during the heat recovery heating operation, the second fixed capacity compressor (40c) is stopped.

  Specifically, in the heat recovery heating operation, the first four-way switching valve (41) is set to the second state, the second four-way switching valve (42) is set to the first state, and the third four-way switching valve (43). Is set to the first state.

  In the normal heating operation, the outdoor expansion valve (45) is set to a fully closed state, and the air conditioning expansion valve (82), the supercooling expansion valve (63), the first injection motor operated valve (64a), the second The opening degrees of the injection motor operated valve (64b) and the third injection motor operated valve (64c) are appropriately adjusted. Further, in the heat recovery heating operation, both solenoid valves (SV1, SV2) are closed.

  The high-pressure refrigerant discharged from the variable capacity compressor (40a) and the first fixed capacity compressor (40b) to the discharge pipe (50) passes through the first four-way switching valve (41) and then passes through the first gas-side closing valve (56 ) Through the air-conditioning heat exchanger (81), radiates heat to the indoor air supplied by the air-conditioning fan (83), and condenses. The air conditioning unit (12) supplies the air heated in the air conditioning heat exchanger (81) to the room. The refrigerant flowing out of the air conditioning heat exchanger (81) passes through the air conditioning expansion valve (82) and then flows into the outdoor circuit (30) through the first liquid side connecting pipe (21), and then the third connection. It flows into the receiver (46) through the pipe (33).

  The refrigerant flowing out from the receiver (46) to the second connection pipe (32) flows into the first flow path (66) of the supercooling heat exchanger (65) and flows through the second flow path (67). Cooling by the pressure refrigerant increases the degree of supercooling. A part of the refrigerant flowing out from the first flow path (66) of the supercooling heat exchanger (65) flows into the injection circuit (60), and the rest flows into the second liquid side connecting pipe (23). .

  Part of the high-pressure refrigerant that has flowed into the second liquid side communication pipe (23) flows into the refrigeration circuit (90), and the rest flows into the refrigeration circuit (100). The refrigerant flowing into the refrigeration circuit (90) is reduced in pressure when passing through the refrigeration expansion valve (92), and then flows into the refrigeration heat exchanger (91) in the same manner as during the cooling operation. It absorbs heat from the internal air supplied by (94) and evaporates, and then flows into the second gas side connecting pipe (24). On the other hand, the refrigerant flowing into the refrigeration circuit (100) is decompressed when passing through the refrigeration expansion valve (102), and then flows into the refrigeration heat exchanger (101) in the same manner as during the cooling operation. It absorbs heat from the internal air supplied by the fan (104) and evaporates, and is then compressed by the booster compressor (111) and then flows into the second gas side connecting pipe (24). A part of the refrigerant flowing through the second gas side communication pipe (24) is sucked into the variable capacity compressor (40a) and the rest is sent to the first fixed capacity compressor (40b), as in the cooling operation. Inhaled. Both the variable capacity compressor (40a) and the first fixed capacity compressor (40b) compress the sucked refrigerant and discharge it to the discharge pipe (50).

  The refrigerant flowing into the injection circuit (60) is depressurized when passing through the supercooling expansion valve (63) and then flows into the second flow path (67) of the supercooling heat exchanger (65). It absorbs heat from the refrigerant flowing through the first flow path (66) and evaporates. The intermediate pressure refrigerant flowing out of the supercooling heat exchanger (65) is mixed with the refrigeration oil supplied from the first and second oil separators (47a, 47b) through the oil return pipe (54), and then It flows into the compression chamber in the middle of compression in the 1st and 2nd compressors (40a, 40b).

-Controller control action-
As described above, the controller (200) includes the target setting unit (205), the adjustment unit (210), and the time setting unit (215) (see FIG. 6).

  The target setting unit (205) sets a discharge temperature target value that is a target value of the discharge temperature of each compressor (40a, 40b, 40c). The target setting unit (205) includes a first setting unit (206) and a second setting unit (207).

  The first setting unit (206) is configured to reduce the pressure of the first suction pipe (51) (that is, the detected value of the first low pressure sensor (71)) and the pressure of the third suction pipe (53) (that is, the second low pressure sensor ( 72) and the discharge refrigerant temperature of the compressors (40a, 40b, 40c) that draw refrigerant from the first suction pipe (51) and the third suction pipe (53) having the lowest pressure. This target value (discharge temperature target value) is set to a value higher than the normal target value Tdm during normal operation. The first setting unit (206) performs this operation as an oil distribution operation.

  The second setting unit (207) is configured to detect the pressure of the first suction pipe (51) (that is, the detected value of the first low pressure sensor (71)) and the pressure of the third suction pipe (53) (that is, the second low pressure sensor ( 72) and the discharge refrigerant temperature of the compressor (40a, 40b, 40c) that sucks refrigerant from the higher pressure of the first suction pipe (51) and the third suction pipe (53). The target value (discharge temperature target value) is set to a value lower than the normal target value Tdm during normal operation. The second setting unit (207) performs this operation as an oil distribution operation.

  The adjustment unit (210) is configured so that each compressor (40a, 40b, 40c) has a discharge temperature target value set by the target setting unit (205). The opening degree of the injection motor-operated valve (64a, 64b, 64c) corresponding to is adjusted.

  The time setting unit (215) sets the duration of the oil distribution operation. As shown in FIG. 7, the time setting unit (215) has a pressure difference ΔLP that is an absolute value of a difference between the detection value LP1 of the first low-pressure sensor (71) and the detection value LP2 of the second low-pressure sensor (72). The larger the value, the longer the duration of the oil distribution operation.

  The time setting unit (215) alternately sets the determination parameter F to “0” and “1”. When the determination parameter F = 0, the controller (200) performs a normal operation of setting the discharge temperature target value of the compressor (40a, 40b, 40c) to the normal target value Tdm. On the other hand, when the determination parameter F = 1, the controller (200) performs an oil distribution operation for setting the discharge temperature target value of the compressor (40a, 40b, 40c) to a value different from the normal target value Tdm.

  The control cycle in FIG. 7 is a cycle in which the time setting unit (215) switches the determination parameter F between “0” and “1”. For example, in the case of 1.5 ≦ ΔLP <2.25, the time setting unit (215) sets the determination parameter F = 0 over (10−1.5) × t1 seconds, and then 1.5 × t1 seconds. Then, the determination parameter F = 1 is set, and then the determination parameter F = 0 is performed again. The value of “t1” in FIG. 7 is set to “120”, for example.

  Next, the opening degree control operation of each injection motor operated valve (64a, 64b, 64c) performed by the controller (200) will be described with reference to the control flow charts of FIGS.

<Opening control of motor valve for first injection>
FIG. 8 is a control flowchart showing an operation in which the controller (200) controls the opening degree of the first injection motor operated valve (64a).

  In step ST1, it is determined whether or not at least one of the first condition and the second condition is satisfied. Here, the first condition is that the discharge superheat degree Tdsh1 calculated using the detection values of the first discharge pipe temperature sensor (74a) and the high pressure sensor (70) is smaller than a predetermined discharge superheat degree upper limit value Tdshs (Tdsh1 < Tdshs), and the detection value Td1 of the first discharge pipe temperature sensor (74a) is further lower than the discharge temperature lower limit value Tdmin set to a value lower than the normal target value Tdm (Td1 <Tdmin), and the injection pipe temperature sensor The intermediate refrigerant superheat degree Tgsh calculated using the detected value of (77) and the intermediate pressure sensor (73) is smaller than the predetermined intermediate superheat degree upper limit value Tgshm (Tgsh <Tgshm).

  The first condition is to determine whether or not the variable capacity compressor (40a) is in an abnormal wet operation (that is, an operation in which the wetness of the refrigerant sucked into the variable capacity compressor (40a) becomes too high). It is a condition to do. Here, the discharge superheat upper limit value Tdshs is set in a range in which the variable capacity compressor (40a) does not fall into an abnormal wet operation. Further, the discharge temperature lower limit value Tdmin is determined that the variable capacity compressor (40a) is in an abnormal wet operation when the detection value Td1 of the first discharge pipe temperature sensor (74a) falls below the discharge temperature lower limit value Tdmin. It is set to a value that allows it.

  The second condition is a condition that the detected value Td1 of the first discharge pipe temperature sensor (74a) is higher than the discharge temperature upper limit value Tdmax set to a value higher than the normal target value Tdm (Td1> Tdmax).

  This second condition determines whether or not the variable capacity compressor (40a) is in an abnormal superheat operation (that is, an operation in which the degree of superheat of the refrigerant discharged from the variable capacity compressor (40a) becomes too high). It is a condition to do. Here, the discharge temperature upper limit value Tdmax indicates that the variable capacity compressor (40a) is in an abnormal overheating operation when the detection value Td1 of the first discharge pipe temperature sensor (74a) exceeds the discharge temperature upper limit value Tdmax. It is set to a value that can be determined.

  If at least one of the first condition and the second condition is satisfied in step ST1, it is determined that the variable capacity compressor (40a) is performing an abnormal wet operation or an abnormal wet operation, and the process proceeds to step ST2. .

  In step ST2, it is determined whether or not the second condition is satisfied. If the second condition is satisfied, the process proceeds to step ST3. In step ST3, the change amount dpls of the opening value of the first injection motor-operated valve (64a) is calculated based on the current opening value EV3pls of the first injection motor-operated valve (64a). Here, if the current opening degree value EV3pls is large, the change amount dpls also increases. If the current opening degree value EV3pls is small, the change amount dpls also decreases. Next, in step ST9, a value obtained by adding the change amount dpls calculated in step ST3 to the current opening value EV3pls of the first injection motor-operated valve (64a) is set as a new opening value EV3pls. As a result, the opening degree of the first injection motor-operated valve (64a) increases, the flow rate of the intermediate pressure refrigerant flowing from the first injection pipe (62a) into the variable capacity compressor (40a) increases, and the variable capacity The degree of superheat of the refrigerant discharged from the compressor (40a) is reduced. As a result, the abnormal overheating operation of the variable capacity compressor (40a) is avoided.

  On the other hand, if the second condition is not satisfied in step ST2, the process proceeds to step ST4. In step ST4, the change amount dpls of the opening value of the first injection motor-operated valve (64a) is calculated based on the current opening value EV3pls of the first injection motor-operated valve (64a). Here, if the current opening degree value EV3pls is large, the change amount dpls also increases. If the current opening degree value EV3pls is small, the change amount dpls also decreases. Next, in step ST9, a value obtained by subtracting the change amount dpls calculated in step ST4 from the current opening value EV3pls of the first injection motor-operated valve (64a) is set as a new opening value EV3pls. As a result, the opening degree of the first injection motor-operated valve (64a) decreases, the flow rate of the intermediate pressure refrigerant flowing from the first injection conduit (62a) into the variable capacity compressor (40a) decreases, and the variable capacity The degree of superheat of the refrigerant discharged from the compressor (40a) increases. As a result, the continuation of abnormal wet operation of the variable capacity compressor (40a) is avoided.

  On the other hand, if both the first condition and the second condition are not satisfied in step ST1, the operation of the variable capacity compressor (40a) is a normal operation that is neither an abnormal wet operation nor an abnormal wet operation. It moves to step ST5.

  In step ST5, a condition that both the variable capacity compressor (40a) connected to the first suction pipe (51) and the second fixed capacity compressor (40c) connected to the third suction pipe (53) are in operation. And whether or not the condition that the determination parameter F is “1” (F = 1) is determined. If these two conditions are satisfied, the process proceeds to step ST6, and if not, the process proceeds to step ST7.

  In step ST6, the detection value LP1 of the first low-pressure sensor (71) (that is, the actual measurement value of the pressure of the first suction pipe (51)) and the detection value LP2 of the second low-pressure sensor (72) (that is, the third suction port). Comparison with the actual pressure value of the pipe (53) is performed. If the detected value LP1 of the first low-pressure sensor (71) is equal to or lower than the detected value LP2 of the second low-pressure sensor (72) (LP1 ≦ LP2), the discharge temperature target value a of the variable capacity compressor (40a) is normally set. A value Tdm + ΔT higher than the target value Tdm is set. If the detected value LP1 of the first low pressure sensor (71) is larger than the detected value LP2 of the second low pressure sensor (72) (LP1> LP2), the discharge temperature target value a of the variable capacity compressor (40a) is the normal target. A value Tdm−ΔT lower than the value Tdm is set. On the other hand, in step ST7, the discharge temperature target value of the variable capacity compressor (40a) is set to the normal target value Tdm.

  Thus, in step ST6, the determination condition is that LP1 ≦ LP2. In step ST6, when this determination condition is satisfied (when LP1 ≦ LP2), the discharge temperature target value a of the variable capacity compressor (40a) is set to a value higher than the normal target value Tdm. When the determination condition is not satisfied (when LP1> LP2), the discharge temperature target value a of the variable capacity compressor (40a) is set to a value lower than the normal target value Tdm.

In step ST6, the determination condition may be that LP1 <LP2.
In this case, in step ST6, when this determination condition is satisfied (when LP1 <LP2), the discharge temperature target value a of the variable capacity compressor (40a) is set to a value higher than the normal target value Tdm, When this determination condition is not satisfied (when LP1 ≧ LP2), the discharge temperature target value a of the variable capacity compressor (40a) is set to a value lower than the normal target value Tdm.

  Next, in step ST8, the difference (Td1−) between the detected value Td1 of the first discharge pipe temperature sensor (74a) and the discharge temperature target value a of the variable capacity compressor (40a) set in step ST6 or step ST7. Based on a), the change amount dpls of the opening value of the first injection motor operated valve (64a) is calculated. Note that the smaller the difference (Td1-a), the smaller the change amount dpls.

  Next, in step ST9, a value obtained by adding the change amount dpls calculated in step ST8 to the current opening value EV3pls of the first injection motor-operated valve (64a) is set as a new opening value EV3pls. Then, the opening degree of the first injection motor-operated valve (64a) is set to this new opening degree value EV3pls.

  In step ST9, a lower limit is set for the opening value EV3pls of the first injection motor operated valve (64a). Therefore, the first injection motor-operated valve (64a) is not fully closed. In the present embodiment, the lower limit value of the opening value EV3pls is set to “43”. The opening value EV3pls in the state where the first injection motor-operated valve (64a) is fully opened is “480”.

  The processing from step ST5 to step ST9 corresponds to the control operation of the adjustment unit (210). With this operation, the discharge temperature of the variable capacity compressor (40a) can be maintained at a predetermined target value. Further, a series of operations from step ST5 to step ST6 to step ST9 corresponds to an oil distribution operation, and a series of operations from step ST5 to step ST7 to step ST9 corresponds to a normal operation.

  When step ST9 ends, the process returns to step ST1, and the determination in step ST1 is performed again. Then, the processing from step ST1 to step ST9 is repeated.

<Opening control of the second injection motorized valve>
FIG. 9 is a control flow diagram illustrating an operation in which the controller (200) controls the opening degree of the second injection motor-operated valve (64b).

  The opening control operation of the second injection motor-operated valve (64b) and the opening control operation of the first injection motor-operated valve (64a) are the same control operations except for a part thereof. The difference between the two is that the variable capacity compressor (40a) corresponding to the first injection motor-operated valve (64a) sucks refrigerant from the first suction pipe (51) exclusively, while the second injection motor-operated valve (40a) This is because the first fixed capacity compressor (40b) corresponding to 64b) selectively sucks the refrigerant from one of the first suction pipe (51) and the third suction pipe (53). That is, in the above-described cooling operation and normal heating operation, the first fixed capacity compressor (40b) sucks the refrigerant from the first suction pipe (51) during the first mode and the third fixed mode compressor (40b) during the second mode. Intake refrigerant from suction pipe (53).

  Steps ST10 to ST13 and step ST19 in the control flowchart shown in FIG. 9 correspond to steps ST1 to ST4 and step ST8 in the control flowchart shown in FIG. The operations from step ST10 to step ST13 and step ST19 in FIG. 9 are the same as the variable capacity compressor (40a), the first discharge pipe temperature sensor (74a) in steps ST1 to ST4 and step ST8 in FIG. The first injection motor-operated valve (64a) is replaced with a first fixed capacity compressor (40b), a second discharge pipe temperature sensor (74b), and a second injection motor-operated valve (64b), respectively. Further, the operation in step ST14 shown in FIG. 9 is the same as the operation in step ST5 shown in FIG.

  In the control flow diagram shown in FIG. 9, steps ST15 to ST17 are performed instead of step ST6 of FIG. That is, if it is determined in step ST15 that the first mode is being performed (that is, the first fixed capacity compressor (40b) is in a state of sucking refrigerant from the first suction pipe (51)), the process proceeds to step ST16. The same operation as step ST6 in FIG. 8 is performed. On the other hand, if it is determined in step ST15 that the first mode is not being performed (that is, the first fixed capacity compressor (40b) is in the second mode for sucking refrigerant from the third suction pipe (53)), step ST17 is performed. Move on.

  In step ST17, the detection value LP1 of the first low-pressure sensor (71) is compared with the detection value LP2 of the second low-pressure sensor (72). If the detected value LP1 of the first low-pressure sensor (71) is equal to or lower than the detected value LP2 of the second low-pressure sensor (72) (LP1 ≦ LP2), the discharge temperature target value a of the first fixed capacity compressor (40b). Is set to a value Tdm-ΔT lower than the normal target value Tdm. If the detected value LP1 of the first low-pressure sensor (71) is larger than the detected value LP2 of the second low-pressure sensor (72) (LP1> LP2), the discharge temperature target value a of the first fixed capacity compressor (40b) is A value Tdm + ΔT higher than the normal target value Tdm is set.

  Thus, in step ST16 and step ST17, the determination condition is that LP1 ≦ LP2, and when this determination condition is satisfied (when LP1 ≦ LP2) and when the determination condition is not satisfied (LP1 > LP2), the discharge temperature target value a of the first fixed capacity compressor (40b) is set to a different value. In these steps ST16 and ST17, LP1 <LP2 is set as a determination condition. When this determination condition is satisfied (when LP1 <LP2), and when the determination condition is not satisfied (LP1 ≧ LP2). The discharge temperature target value a of the first fixed capacity compressor (40b) may be set to a different value.

  In step ST20, the change amount dpls of the opening value of the second injection motor-operated valve (64b) calculated in step ST12, step ST13, or step ST19 is used. In this step ST20, a value obtained by adding the change amount dpls to the current opening value EV4pls of the second injection motor operated valve (64b) is set as a new opening value EV4pls. Then, the opening of the second injection motor-operated valve (64b) is set to this new opening value EV4pls.

  In step ST20, the lower limit value of the new opening value EV4pls is set to a different value between the first mode and the second mode. Specifically, when one of the condition that the determination parameter F = 1 and the first mode is being satisfied, and the condition that the determination parameter F = 0 is satisfied, the second injection motor operated valve (64b) The lower limit value of the opening value EV4pls is set to “43”. On the other hand, when the condition that the determination parameter F = 1 and the second mode is being satisfied, the lower limit value of the opening value EV4pls of the second injection motor-operated valve (64b) is set to “200”.

  In the opening control operation of the second injection motor operated valve (64b) performed by the controller (200), a series of operations from step ST14 to step ST15 through step ST15 and step ST16, and step ST14 to step ST15 and step ST17 are performed. A series of operations from step ST20 to step ST20 corresponds to an oil distribution operation, and a series of operations from step ST14 to step ST18 to step ST20 corresponds to a normal operation.

<Opening control of third injection motorized valve>
FIG. 10 is a control flow diagram showing an operation in which the controller (200) controls the opening degree of the third injection motor-operated valve (64c).

  The opening control operation of the third injection motor-operated valve (64c) and the opening control operation of the first injection motor-operated valve (64a) are the same control operations except for a part thereof. The difference between the two is that the variable capacity compressor (40a) corresponding to the first injection motor-operated valve (64a) sucks refrigerant from the first suction pipe (51) exclusively, whereas the third injection motor-operated valve (40a) This is because the second fixed capacity compressor (40c) corresponding to 64c) sucks the refrigerant exclusively from the third suction pipe (53).

  Steps ST21 to ST24 and step ST28 in the control flowchart shown in FIG. 10 correspond to steps ST1 to ST4 and step ST8 in the control flowchart shown in FIG. The operations from step ST21 to step ST24 and step ST28 in FIG. 10 are the same as the variable capacity compressor (40a), the first discharge pipe temperature sensor (74a) in steps ST1 to ST4 and step ST8 in FIG. The first injection motor-operated valve (64a) is replaced with a second fixed capacity compressor (40c), a third discharge pipe temperature sensor (74c), and a third injection motor-operated valve (64c), respectively. Further, the operation in step ST25 shown in FIG. 10 is the same as the operation in step ST5 shown in FIG.

  In the control flow diagram of FIG. 10, step ST26 is performed instead of step ST6 of FIG.

  In step ST26, the detection value LP1 of the first low-pressure sensor (71) is compared with the detection value LP2 of the second low-pressure sensor (72). If the detected value LP1 of the first low pressure sensor (71) is equal to or lower than the detected value LP2 of the second low pressure sensor (72) (LP1 ≦ LP2), the discharge temperature target value a of the second fixed capacity compressor (40c). Is set to a value Tdm-ΔT lower than the normal target value Tdm. If the detected value LP1 of the first low-pressure sensor (71) is larger than the detected value LP2 of the second low-pressure sensor (72) (LP1> LP2), the discharge temperature target value a of the second fixed capacity compressor (40c) is A value Tdm + ΔT higher than the normal target value Tdm is set.

  Thus, in step ST26, the determination condition is that LP1 ≦ LP2, and when this determination condition is satisfied (when LP1 ≦ LP2) and when the determination condition is not satisfied (LP1> LP2) The discharge temperature target value a of the second fixed capacity compressor (40c) is set to a different value. In step ST26, LP1 <LP2 is set as a determination condition. When this determination condition is satisfied (when LP1 <LP2), the determination condition is not satisfied (when LP1 ≧ LP2). Thus, the discharge temperature target value a of the second fixed capacity compressor (40c) may be set to a different value.

  In step ST29, the change amount dpls of the opening value of the third injection motor-operated valve (64c) calculated in step ST23, step ST24, or step ST28 is used. In this step ST29, a value obtained by adding the change amount dpls to the current opening value EV5pls of the third injection motor operated valve (64c) is set as a new opening value EV5pls. Then, the opening degree of the third injection motor-operated valve (64c) is set to this new opening degree value EV5pls.

  In step ST29, the lower limit value of the new opening value EV5pls is set to a different value when the determination parameter is “1” and when it is “0”. Specifically, when the determination parameter F = 0, the lower limit value of the opening value EV5pls of the third injection motor-operated valve (64c) is set to “43”. On the other hand, when the determination parameter F = 1, the lower limit value of the opening value EV5pls of the third injection motor operated valve (64c) is set to “200”.

  In the opening control operation of the third injection motor operated valve (64c) performed by the controller (200), a series of operations from step ST25 to step ST26 to step ST29 corresponds to an oil distribution operation, and step ST25 to step ST27. A series of operations from step ST29 to step ST29 correspond to normal operations.

-Effect of Embodiment 1-
In the present embodiment, the controller (200) constituting the opening degree control unit of the flow rate adjusting mechanism (250) intermittently performs the oil distribution operation. The controller (200) uses the condition that the detection value LP1 of the first low-pressure sensor (71) is equal to or less than the detection value LP2 (LP1 ≦ LP2) of the second low-pressure sensor (72), and the determination condition is satisfied And a different operation is executed as an oil distribution operation when the determination condition is not satisfied.

  As described above, when the determination condition is satisfied, it can be estimated that the refrigerating machine oil is more likely to return to the second fixed capacity compressor (40c) than the variable capacity compressor (40a). Therefore, in this case, the controller (200) increases the refrigerant flow rate in the first injection pipe (62a) than during normal operation, and the refrigerant flow rate in the third injection pipe (62c) is higher than during normal operation. The decreasing operation is intermittently executed as the oil distribution operation. During this oil distribution operation, the flow rate of the refrigerating machine oil flowing into the variable capacity compressor (40a) from the first injection pipe (62a) increases compared to during normal operation. Therefore, if this oil distribution operation is executed when the determination condition is satisfied, the amount of refrigerating machine oil stored in the variable capacity compressor (40a) reduced during the normal operation can be recovered.

  When the determination condition is not satisfied, it can be estimated that the refrigeration oil is more likely to return to the variable capacity compressor (40a) than the second fixed capacity compressor (40c). Therefore, the controller (200) operates to decrease the refrigerant flow rate in the first injection pipe (62a) than during normal operation and increase the refrigerant flow rate in the third injection pipe (62c) than during normal operation. Are intermittently executed as an oil distribution operation. During this oil distribution operation, the flow rate of the refrigerating machine oil flowing from the third injection pipe (62c) into the second fixed capacity compressor (40c) increases as compared to during normal operation. Therefore, if this oil distribution operation is executed when the determination condition is not satisfied, the amount of refrigerating machine oil stored in the second fixed capacity compressor (40c) that has decreased during the normal operation can be recovered.

  As described above, according to the present embodiment, the controller (200) performs the oil distribution operation, whereby the refrigerating machine oil storage amount in both the variable capacity compressor (40a) and the second fixed capacity compressor (40c). Can be secured sufficiently. Therefore, according to this embodiment, damage due to poor lubrication of the variable capacity compressor (40a) and the second fixed capacity compressor (40c) can be avoided in advance, and the reliability of the refrigeration apparatus (10) can be avoided. Can be improved.

  In the present embodiment, the controller (200) sets the control target value to the normal target value Tdm during normal operation and sets the first injection motor-operated valve (64a) and the third injection motor-operated valve (64c). While adjusting the opening, the control target value is set to a value different from the normal target value Tdm during the oil distribution operation, and the first injection motor valve (64a) and the third injection motor valve (64c) are opened. Adjust the degree. Therefore, according to the present embodiment, the opening degree of the first injection motor-operated valve (64a) and the third injection motor-operated valve (64c) during the oil distribution operation is reliably changed from the value during the normal operation, The refrigerant flow rate in the first injection pipe (62a) and the third injection pipe (62c) during the distribution operation can be reliably increased or decreased from the value during the normal operation.

  In the refrigerant circuit (20) of the present embodiment, the first mode and the second mode can be switched in each of the cooling operation and the normal heating operation. For example, in the cooling operation in the first mode, the variable capacity compressor (40a) and the first fixed capacity compressor (40b) suck the refrigerant evaporated in the refrigeration heat exchanger (91), and the second fixed capacity compressor (40c) sucks the refrigerant evaporated in the air conditioning heat exchanger (81). In the second mode of cooling operation, the variable capacity compressor (40a) removes the refrigerant evaporated in the refrigeration heat exchanger (91). The first fixed capacity compressor (40b) and the second fixed capacity compressor (40c) suck the refrigerant evaporated in the air conditioning heat exchanger (81). Then, the controller (200) of the present embodiment selects either the operation suitable for the first mode or the operation suitable for the second mode as the oil distribution operation for the second injection motor operated valve (64b). And execute. Therefore, according to the present embodiment, the first fixed capacity compressor (40b) that selectively sucks the refrigerant evaporated in the refrigeration heat exchanger (91) and the refrigerant evaporated in the air conditioning heat exchanger (81). In addition, a sufficient amount of refrigerating machine oil can be secured, and damage to the first fixed capacity compressor (40b) due to insufficient lubrication can be avoided.

  Further, the controller (200) of the present embodiment increases the duration of the oil distribution operation as the difference between the detection value LP1 of the first low pressure sensor (71) and the detection value LP2 of the second low pressure sensor (72) increases. Extend. Therefore, according to the present embodiment, the oil distribution operation increases as the difference between the refrigerating machine oil storage amount in the variable capacity compressor (40a) and the refrigerating machine oil storage amount in the second fixed capacity compressor (40c) increases. The duration time can be increased, and a sufficient amount of refrigerating machine oil can be secured in both the variable capacity compressor (40a) and the second fixed capacity compressor (40c).

<< Embodiment 2 of the Invention >>
A second embodiment of the present invention will be described. The refrigeration apparatus (10) of this embodiment is obtained by changing the configuration of the controller (200) in the first embodiment. Here, the controller (200) of the present embodiment will be described.

  As shown in FIG. 11, the controller (200) of the present embodiment includes an electric valve control unit (220) and an intermediate pressure control unit (225). Further, the electric valve control unit (220) is provided with a determination parameter setting unit (221). In the present embodiment, the motor-operated valve control unit (220) constitutes an opening degree control unit. The motor-operated valve control unit (220) constitutes a flow rate adjusting mechanism (250) together with the motor-operated valves for injection (64a, 64b, 64c) provided in the injection circuit (60).

  The motor-operated valve control unit (220) uses the superheat degree of the refrigerant discharged from each compressor (40a, 40b, 40c) as a physical quantity for control, and uses the superheat degree (discharge) of each compressor (40a, 40b, 40c). The opening degree of each injection motor-operated valve (64a, 64b, 64c) is individually adjusted so that the degree of superheat) becomes a predetermined control target value. Specifically, the electric valve controller (220) calculates the degree of superheat of the refrigerant discharged from the variable capacity compressor (40a) using the detection values of the first discharge pipe temperature sensor (74a) and the high pressure sensor (70). The opening degree of the first injection motor-operated valve (64a) is adjusted so that the calculated discharge superheat degree becomes the control target value. The motor-operated valve control unit (220) calculates the degree of superheat of the refrigerant discharged from the first fixed capacity compressor (40b) using the detection values of the second discharge pipe temperature sensor (74b) and the high pressure sensor (70). The opening degree of the second injection motor-operated valve (64b) is adjusted so that the calculated discharge superheat degree becomes the control target value. The motor-operated valve controller (220) calculates the degree of superheat of the refrigerant discharged from the second fixed capacity compressor (40c) using the detection values of the third discharge pipe temperature sensor (74c) and the high pressure sensor (70). The opening degree of the third injection motor-operated valve (64c) is adjusted so that the calculated discharge superheat degree becomes the control target value.

  Furthermore, the motor-operated valve control unit (220) adjusts the opening of the motor-operated injection valve (64a to 64c) while the corresponding compressor (40a to 40c) is in operation, and the corresponding compressor (40a to 40c) Hold the injection motorized valves (64a to 64c) in a fully closed state. In other words, the motor-operated valve control unit (220) performs the opening control operation of the first injection motor-operated valve (64a) during operation of the variable capacity compressor (40a), and while the variable capacity compressor (40a) is stopped. The first injection motor-operated valve (64a) is held fully closed. The motor-operated valve control unit (220) controls the opening degree of the second injection motor-operated valve (64b) during the operation of the first fixed-capacity compressor (40b), and the first fixed-capacity compressor (40b) During the stop, the second injection motor-operated valve (64b) is held fully closed. The motor-operated valve controller (220) controls the opening degree of the third injection motor-operated valve (64c) during the operation of the second fixed-capacity compressor (40c), and the second fixed-capacity compressor (40c) During the stop, the third injection motor-operated valve (64c) is held fully closed.

  The determination parameter setting unit (221) alternately sets the determination parameter F to “0” and “1”. Specifically, the determination parameter setting unit (221) changes the determination parameter F to “1” and sets the determination parameter F to “1” when 17 minutes have elapsed since the determination parameter F was set to “0”. When 3 minutes have elapsed from the time point, the operation of returning the determination parameter F to “0” is repeated. That is, the determination parameter setting unit (221) repeatedly performs an operation of holding the determination parameter F at “0” for 17 minutes and holding the determination parameter F at “1” for the subsequent 3 minutes. .

  Although details will be described later, when the determination parameter F = 0, the motor-operated valve control unit (220) performs a normal operation of setting the target value of the discharge superheat degree of the compressor (40a, 40b, 40c) to the normal target value. . In addition, when the determination parameter F = 1, the motor-operated valve control section (220) sets the target value of the discharge superheat degree of the compressor (40a, 40b, 40c) to a value different from the normal target value. I do.

  The intermediate pressure control unit (225) performs an opening degree control operation of the supercooling expansion valve (63). The intermediate pressure control unit (225) adjusts the opening degree of the supercooling expansion valve (63) based on the detected value MP of the intermediate pressure sensor (73), and the subcooling heat exchanger (65). The operation of adjusting the opening degree of the supercooling expansion valve (63) based on the superheat degree SHm of the intermediate pressure refrigerant flowing out from the second flow path (67) is selectively executed.

−Control operation of motorized valve control unit−
An operation performed by the electric valve control unit (220) of the controller (200) will be described. As described above, the motor-operated valve control unit (220) individually adjusts the opening degree of each injection motor-operated valve (64a, 64b, 64c). Note that the temperature and superheat values shown below are merely examples.

<Opening control of motor valve for first injection>
The opening degree control of the first injection motor-operated valve (64a) by the motor-operated valve controller (220) will be described with reference to the control flowcharts of FIGS. Although details will be described later, the motor-operated valve control unit (220) uses the degree of superheat of the refrigerant discharged from the variable capacity compressor (40a) as a control physical quantity as shown in the control flow diagram of FIG. The opening degree of the first injection motor-operated valve (64a) is adjusted so as to be a predetermined control target value.

  In step ST31 of FIG. 12, the motor-operated valve control unit (220) determines whether or not all three conditions are satisfied. The first condition of step ST31 is a condition that the superheat degree (discharge superheat degree Tdsh1) of the refrigerant discharged from the variable capacity compressor (40a) is less than 15 ° C. (Tdsh1 <15 ° C.). The second condition of step ST31 is a condition that the temperature of the refrigerant discharged (discharge temperature Td1) of the variable capacity compressor (40a) is less than 60 ° C. (Td1 <60 ° C.). The third condition of step ST31 is a condition that the superheat degree SHm of the intermediate pressure refrigerant flowing out from the second flow path (67) of the supercooling heat exchanger (65) is less than 5 ° C. (SHm <5 ° C.). is there. The superheat degree SHm of the intermediate pressure refrigerant is calculated using the detection values of the injection pipe temperature sensor (77) and the intermediate pressure sensor (73).

  In Step ST31, when all of the first condition, the second condition, and the third condition are satisfied, it can be estimated that the wetness of the refrigerant sucked into the variable capacity compressor (40a) is too high. Therefore, in this case, the motor-operated valve control unit (220) proceeds to step ST32 and forcibly reduces the opening degree of the first injection motor-operated valve (64a). As a result, the flow rate of the intermediate pressure refrigerant flowing from the first injection pipe (62a) into the variable capacity compressor (40a) decreases, and the discharge temperature Td1 of the variable capacity compressor (40a) increases.

  On the other hand, when at least one of the first condition, the second condition, and the third condition is not satisfied in step ST31, the wetness of the refrigerant sucked into the variable capacity compressor (40a) is not so high. Can be estimated. Therefore, in this case, the motor-operated valve control unit (220) proceeds to step ST33.

  In step ST33, the electric valve control unit (220) determines whether or not the condition that the discharge temperature Td1 of the variable capacity compressor (40a) exceeds 100 ° C. (Td1> 100 ° C.) is satisfied. When this condition is satisfied, it can be determined that the discharge temperature Td1 of the variable capacity compressor (40a) is excessively increased. Therefore, in this case, the motor-operated valve control unit (220) proceeds to step ST34 and forcibly increases the opening of the first injection motor-operated valve (64a). As a result, the flow rate of the intermediate pressure refrigerant flowing into the variable capacity compressor (40a) from the first injection pipe (62a) increases, and the discharge temperature Td1 of the variable capacity compressor (40a) decreases.

  On the other hand, if the condition of (Td1> 100 ° C.) is not satisfied in step ST33, it can be determined that there is no need to forcibly lower the discharge temperature Td1 of the variable capacity compressor (40a), so the routine proceeds to step ST35.

  In step ST35, the electric valve control unit (220) determines whether or not a condition that both the variable capacity compressor (40a) and the second fixed capacity compressor (40c) are in operation is satisfied. Then, when this condition is satisfied, the motor-operated valve control unit (220) proceeds to step ST36 and performs the opening degree control for oil distribution shown in the control flowchart of FIG. This opening control for oil distribution will be described later.

  On the other hand, if the above condition in step ST35 is not satisfied, it can be determined that the variable capacity compressor (40a) is operating and the second fixed capacity compressor (40c) is stopped. This is because the motor-operated valve controller (220) controls the opening degree of the first injection motor-operated valve (64a) only while the variable capacity compressor (40a) is in operation. When the second fixed capacity compressor (40c) is stopped, the third injection motor-operated valve (64c) is fully closed, and the second fixed capacity compressor (40c) is supplied from the oil return circuit (49). ) Refrigerator oil does not flow into. Therefore, in this case, the motor-operated valve control unit (220) controls the first injection motor-operated valve (64a) so that the discharge superheat degree Tdsh1 of the variable capacity compressor (40a) becomes a predetermined target value (here, 25 ° C.). ) Is adjusted.

  The opening degree control for oil distribution performed in step ST36 will be described with reference to the control flowchart of FIG.

  In step ST41 of FIG. 13, the motor-operated valve control unit (220) detects the detected value LP1 of the first low-pressure sensor (71) (that is, the measured value of the pressure of the first suction pipe (51)) and the second low-pressure sensor ( 72) and the detected value LP2 (that is, the actually measured value of the pressure of the third suction pipe (53)). Then, the motor-operated valve control unit (220) determines whether the determination condition that the detection value LP1 of the first low-pressure sensor (71) is higher than the detection value LP2 of the second low-pressure sensor (72) (LP1> LP2) is satisfied. . In step ST41, the condition that the detection value LP1 of the first low-pressure sensor (71) is equal to or greater than the detection value LP2 of the second low-pressure sensor (72) (LP1 ≧ LP2) may be the determination condition.

  When the determination condition is satisfied in step ST41 (that is, when LP1> LP2), the motor-operated valve control unit (220) proceeds to step ST42. In step ST42, the motor-operated valve control unit (220) determines whether or not the determination parameter F = 1. When the determination parameter F = 1, the motor-operated valve control unit (220) proceeds to step ST43 and performs an oil distribution operation. On the other hand, when the determination parameter F ≠ 1 (that is, F = 0), the motor-operated valve control unit (220) proceeds to step ST44 and performs a normal operation.

  In step ST44, the electric valve control unit (220) sets the control target value of the discharge superheat degree Tdsh1 of the variable capacity compressor (40a) to the normal target value “25 ° C.”, and the discharge superheat degree Tdsh1 is 25. The opening degree of the first injection motor-operated valve (64a) is adjusted so that the temperature becomes ° C. The electric valve control unit (220) executes this operation as a normal operation.

  On the other hand, in step ST43, the motor-operated valve controller (220) sets the control target value of the discharge superheat degree Tdsh1 of the variable capacity compressor (40a) to “20 ° C.” lower than the normal target value, and this discharge superheat degree. The opening degree of the first injection motor-operated valve (64a) is adjusted so that Tdsh1 becomes 20 ° C. The electric valve controller (220) executes this operation as an oil distribution operation. When the target value of the discharge superheat degree Tdsh1 is lowered from the normal target value by this oil distribution operation, the opening degree of the first injection motor-operated valve (64a) is expanded as compared with the normal operation, and the first injection pipe line The flow rate of the intermediate pressure refrigerant in (62a) increases compared to that during normal operation.

  When the determination condition is not satisfied in step ST41 (that is, when LP1 ≦ LP2), the motor-operated valve control unit (220) proceeds to step ST45. In step ST45, the electric valve control unit (220) determines whether or not the determination parameter F = 1. When the determination parameter F = 1, the motor-operated valve control unit (220) proceeds to step ST46 and performs an oil distribution operation. On the other hand, when the determination parameter F ≠ 1 (that is, F = 0), the motor-operated valve control unit (220) proceeds to step ST47 and performs normal operation.

  In step ST47, the electric valve control section (220) sets the control target value of the discharge superheat degree Tdsh1 of the variable capacity compressor (40a) to the normal target value “25 ° C.”, and the discharge superheat degree Tdsh1 is 25. The opening degree of the first injection motor-operated valve (64a) is adjusted so that the temperature becomes ° C. The electric valve control unit (220) executes this operation as a normal operation. That is, the electric valve control unit (220) performs the same operation as step ST44.

  On the other hand, in step ST46, the electric valve control unit (220) sets the control target value of the discharge superheat degree Tdsh1 of the variable capacity compressor (40a) to “30 ° C.” higher than the normal target value, and this discharge superheat degree. The opening degree of the first injection motor-operated valve (64a) is adjusted so that Tdsh1 is 30 ° C. The electric valve controller (220) executes this operation as an oil distribution operation. When the target value of the discharge superheat degree Tdsh1 is raised from the normal target value by this oil distribution operation, the opening degree of the first injection motor-operated valve (64a) is reduced as compared with the normal operation, and the first injection pipe line The flow rate of the intermediate pressure refrigerant in (62a) is reduced as compared with that during normal operation.

  When the operation of step ST32, step ST34, step ST36, or step ST37 in the control flow diagram of FIG. 12 ends, the motor-operated valve control unit (220) returns to step ST31 again. Then, the motor-operated valve control unit (220) repeatedly executes the operations shown in the control flowcharts of FIGS. 12 and 13 every 10 to 20 seconds, for example.

<Opening control of third injection motorized valve>
The opening control of the third injection motor-operated valve (64c) by the motor-operated valve controller (220) will be described with reference to the control flowcharts of FIGS. Although the details will be described later, the motor-operated valve control unit (220) uses the degree of superheat of the refrigerant discharged from the second fixed capacity compressor (40c) as a control physical quantity, as shown in the control flow diagram of FIG. The opening degree of the third injection motor-operated valve (64c) is adjusted so that the degree becomes a predetermined control target value.

  In step ST81 of FIG. 16, the motor-operated valve control unit (220) performs the same operation as that of step ST31 in FIG. 12 on the second fixed capacity compressor (40c). That is, the motor-operated valve control unit (220) has the first condition that the discharge superheat degree Tdsh3 of the second fixed capacity compressor (40c) is less than 15 ° C. (Tdsh3 <15 ° C.), the second fixed capacity compressor (40c). ) Discharge temperature Td3 is less than 60 ° C. (Td3 <60 ° C.) and the superheat SHm of the intermediate pressure refrigerant flowing out of the supercooling heat exchanger (65) is less than 5 ° C. (SHm The success or failure of the third condition <5 ° C.) is determined.

  In step ST81, when all of the first condition, the second condition, and the third condition are satisfied, it can be estimated that the wetness of the refrigerant sucked into the second fixed capacity compressor (40c) is too high. . Therefore, in this case, the motor-operated valve control unit (220) proceeds to step ST82 and forcibly reduces the opening of the third injection motor-operated valve (64c). As a result, the flow rate of the intermediate pressure refrigerant flowing from the third injection pipe (62c) to the second fixed capacity compressor (40c) decreases, and the discharge temperature Td3 of the second fixed capacity compressor (40c) increases. .

  On the other hand, if at least one of the first condition, the second condition, and the third condition is not satisfied in step ST81, the wetness of the refrigerant sucked into the second fixed capacity compressor (40c) is so much. It can be estimated that it is not high. Therefore, in this case, the electric valve control unit (220) proceeds to step ST83.

  In step ST83, the electric valve control unit (220) determines whether or not the condition that the discharge temperature Td3 of the second fixed capacity compressor (40c) exceeds 100 ° C. (Td3> 100 ° C.) is satisfied. If this condition is satisfied, it can be determined that the discharge temperature Td3 of the second fixed capacity compressor (40c) has risen too much. Therefore, in this case, the motor-operated valve control unit (220) proceeds to step ST84 and forcibly increases the opening of the third injection motor-operated valve (64c). As a result, the flow rate of the intermediate pressure refrigerant flowing from the third injection pipe (62c) to the second fixed capacity compressor (40c) increases, and the discharge temperature Td3 of the second fixed capacity compressor (40c) decreases. .

  On the other hand, if the condition of (Td3> 100 ° C.) is not satisfied in step ST83, it can be determined that there is no need to forcibly lower the discharge temperature Td3 of the second fixed capacity compressor (40c), so the routine proceeds to step ST85. .

  In step ST85, the electric valve control unit (220) determines whether or not a condition that both the variable capacity compressor (40a) and the second fixed capacity compressor (40c) are operating is satisfied. When this condition is satisfied, the motor-operated valve control unit (220) proceeds to step ST86 and performs oil distribution opening control shown in the control flowchart of FIG. This opening control for oil distribution will be described later.

  On the other hand, if the above condition in step ST85 is not satisfied, it can be determined that the second fixed capacity compressor (40c) is operating and the variable capacity compressor (40a) is stopped. This is because the motor-operated valve controller (220) controls the opening degree of the third injection motor-operated valve (64c) only during the operation of the second fixed capacity compressor (40c). When the variable capacity compressor (40a) is stopped, the first injection motor-operated valve (64a) is fully closed, and the refrigerating machine oil is transferred from the oil return circuit (49) to the variable capacity compressor (40a). Does not flow. The operating capacity of the second fixed capacity compressor (40c) is fixed at the maximum capacity. Therefore, in this case, the motor-operated valve control unit (220) sets the third injection motor-operated valve (64c) to fully open.

  The opening degree control for oil distribution performed in step ST86 will be described with reference to the control flowchart of FIG.

  In step ST91 of FIG. 17, the motor-operated valve control unit (220) compares the detection value LP1 of the first low-pressure sensor (71) with the detection value LP2 of the second low-pressure sensor (72). Then, the motor-operated valve control unit (220) determines whether the determination condition that the detection value LP1 of the first low-pressure sensor (71) is higher than the detection value LP2 of the second low-pressure sensor (72) (LP1> LP2) is satisfied. . In step ST91, the condition that the detection value LP1 of the first low-pressure sensor (71) is equal to or greater than the detection value LP2 of the second low-pressure sensor (72) (LP1 ≧ LP2) may be the determination condition.

  When the determination condition is satisfied in step ST91 (that is, when LP1> LP2), the motor-operated valve control unit (220) proceeds to step ST92. In step ST92, the electric valve control unit (220) determines whether or not the determination parameter F = 1. When the determination parameter F = 1, the motor-operated valve control unit (220) proceeds to step ST93 and performs an oil distribution operation. On the other hand, when the determination parameter F ≠ 1 (that is, F = 0), the motor-operated valve control unit (220) proceeds to step ST94 and performs normal operation.

  In step ST94, the electric valve control unit (220) sets the control target value of the discharge superheat degree Tdsh3 of the second fixed capacity compressor (40c) to the normal target value “25 ° C.”, and this discharge superheat degree Tdsh3. The opening degree of the third injection motor-operated valve (64c) is adjusted so that becomes 25 ° C. The electric valve control unit (220) executes this operation as a normal operation.

  On the other hand, in step ST93, the motor-operated valve control unit (220) sets the control target value of the discharge superheat degree Tdsh3 of the second fixed capacity compressor (40c) to “30 ° C.” higher than the normal target value. The opening degree of the third injection motor-operated valve (64c) is adjusted so that the degree of superheat Tdsh3 becomes 30 ° C. The electric valve controller (220) executes this operation as an oil distribution operation. When the target value of the discharge superheat degree Tdsh3 is raised from the normal target value by this oil distribution operation, the opening degree of the third injection motor-operated valve (64c) is reduced as compared with the normal operation, and the third injection pipe line The flow rate of the intermediate pressure refrigerant in (62c) decreases compared to that during normal operation.

  When the determination condition is not satisfied in step ST91 (that is, when LP1 ≦ LP2), the motor-operated valve control unit (220) proceeds to step ST95. In step ST95, the electric valve control unit (220) determines whether or not the determination parameter F = 1. When the determination parameter F = 1, the motor-operated valve control unit (220) proceeds to step ST96 and performs an oil distribution operation. On the other hand, when the determination parameter F ≠ 1 (that is, F = 0), the motor-operated valve control unit (220) proceeds to step ST97 and performs a normal operation.

  In step ST97, the electric valve controller (220) sets the control target value of the discharge superheat degree Tdsh3 of the second fixed capacity compressor (40c) to the normal target value “25 ° C.”, and this discharge superheat degree Tdsh3. The opening degree of the third injection motor-operated valve (64c) is adjusted so that becomes 25 ° C. The electric valve control unit (220) executes this operation as a normal operation. That is, the electric valve control unit (220) performs the same operation as in step ST94.

  On the other hand, in step ST96, the motor-operated valve control unit (220) sets the control target value of the discharge superheat degree Tdsh3 of the second fixed capacity compressor (40c) to “20 ° C.” lower than the normal target value. The opening degree of the third injection motor-operated valve (64c) is adjusted so that the degree of superheat Tdsh3 becomes 20 ° C. The electric valve controller (220) executes this operation as an oil distribution operation. When the target value of the discharge superheat degree Tdsh3 is lowered from the normal target value by this oil distribution operation, the opening degree of the third injection motor-operated valve (64c) is expanded as compared with the normal operation, and the third injection pipe line The flow rate of the intermediate pressure refrigerant in (62c) increases compared to that during normal operation.

  When the operation of step ST82, step ST84, step ST86, or step ST87 in the control flow diagram of FIG. 16 ends, the motor-operated valve control unit (220) returns to step ST81 again. Then, the motor-operated valve control unit (220) repeatedly executes the operations shown in the control flowcharts of FIGS. 16 and 17 every 10 to 20 seconds, for example.

<Opening control of the second injection motorized valve>
The opening degree control of the second injection motor-operated valve (64b) by the motor-operated valve controller (220) will be described with reference to the control flowcharts of FIGS. Although details will be described later, the motor-operated valve control unit (220) uses the degree of superheat of the refrigerant discharged from the first fixed capacity compressor (40b) as a physical quantity for control as shown in the control flow diagram of FIG. The opening degree of the second injection motor-operated valve (64b) is adjusted so that the degree becomes a predetermined control target value.

  Steps ST51 to ST54 in FIG. 14 are operations corresponding to steps ST31 to ST34 in FIG. That is, in step ST51, the motor-operated valve control unit (220) performs the same operation as in step ST31 of FIG. 12 using the discharge superheat degree Tdsh2 and the discharge temperature Td2 of the first fixed capacity compressor (40b). In step ST52, the motor-operated valve control unit (220) performs the same operation as step ST32 in FIG. 12 for the second injection motor-operated valve (64b). In step ST53, the motor-operated valve controller (220) performs the same operation as in step ST33 of FIG. 12 using the discharge temperature Td2 of the first fixed capacity compressor (40b). In step ST54, the motor-operated valve controller (220) performs the same operation as step ST34 in FIG. 12 for the second injection motor-operated valve (64b).

  When the condition (Td2> 100 ° C.) in step ST53 is not satisfied, the motor-operated valve control unit (220) proceeds to step ST55. In step ST55, the electric valve control unit (220) determines whether or not a condition that both the variable capacity compressor (40a) and the second fixed capacity compressor (40c) are operating is satisfied. When this condition is satisfied, the motor-operated valve control unit (220) proceeds to step ST56 and performs the oil distribution opening degree control shown in the control flowchart of FIG. This opening control for oil distribution will be described later. On the other hand, when the above-mentioned conditions in step ST55 are not satisfied, the motor-operated valve control unit (220) proceeds to step ST57 and sets the second injection motor-operated valve (64b) to fully open.

  The opening degree control for oil distribution performed in step ST56 will be described with reference to the control flowchart of FIG.

  In step ST61 of FIG. 15, the motor-operated valve control unit (220) compares the detection value LP1 of the first low-pressure sensor (71) with the detection value LP2 of the second low-pressure sensor (72). Then, the motor-operated valve control unit (220) determines whether the determination condition that the detection value LP1 of the first low-pressure sensor (71) is higher than the detection value LP2 of the second low-pressure sensor (72) (LP1> LP2) is satisfied. . In step ST61, the condition that the detection value LP1 of the first low-pressure sensor (71) is equal to or greater than the detection value LP2 of the second low-pressure sensor (72) (LP1 ≧ LP2) may be the determination condition.

  When the determination condition is satisfied in step ST61 (that is, when LP1> LP2), the motor-operated valve control unit (220) proceeds to step ST62. In step ST62, the electric valve control unit (220) determines whether or not the determination parameter F = 1. When the determination parameter F = 1, the motor-operated valve control unit (220) proceeds to step ST63 and performs an oil distribution operation. On the other hand, when the determination parameter F ≠ 1 (that is, F = 0), the motor-operated valve control unit (220) proceeds to step ST66 and performs normal operation.

  In step ST66, the electric valve control unit (220) sets the control target value of the discharge superheat degree Tdsh2 of the first fixed capacity compressor (40b) to the normal target value “25 ° C.”, and this discharge superheat degree Tdsh2 The opening of the second injection motor-operated valve (64b) is adjusted so that becomes 25 ° C. The electric valve control unit (220) executes this operation as a normal operation.

  On the other hand, in step ST63, the motor-operated valve control unit (220) determines whether or not it is in the first mode. When the motor-operated valve control unit (220) is in the first mode, the process proceeds to step ST64, and when it is not in the first mode (that is, in the second mode), the process proceeds to step ST65.

  During the first mode, the first fixed capacity compressor (40b) sucks the refrigerant from the first suction pipe (51). That is, the pressure of the refrigerant sucked into the first fixed capacity compressor (40b) is substantially equal to the pressure of the refrigerant sucked into the variable capacity compressor (40a). Therefore, in step ST64, the motor-operated valve control unit (220) performs the same operation as in step ST43 in FIG. That is, the electric valve control unit (220) sets the control target value of the discharge superheat degree Tdsh2 of the first fixed capacity compressor (40b) to “20 ° C.” lower than the normal target value, and the discharge superheat degree Tdsh2 is The opening degree of the second injection motor-operated valve (64b) is adjusted to 20 ° C. When the target value of the discharge superheat degree Tdsh2 is lowered from the normal target value by this oil distribution operation, the opening degree of the second injection motor-operated valve (64b) is expanded as compared with the normal operation, and the second injection pipe line The flow rate of the intermediate-pressure refrigerant in (62b) increases compared to that during normal operation.

  On the other hand, in the second mode, the first fixed capacity compressor (40b) sucks the refrigerant from the third suction pipe (53). That is, the pressure of the refrigerant sucked into the first fixed capacity compressor (40b) is substantially equal to the pressure of the refrigerant sucked into the second fixed capacity compressor (40c). Therefore, in step ST65, the electric valve control unit (220) performs the same operation as in step ST93 in FIG. That is, the electric valve control unit (220) sets the control target value of the discharge superheat degree Tdsh2 of the first fixed capacity compressor (40b) to “30 ° C.” higher than the normal target value, and the discharge superheat degree Tdsh2 is The opening degree of the second injection motor-operated valve (64b) is adjusted to 30 ° C. When the target value of the discharge superheat degree Tdsh2 is raised from the normal target value by this oil distribution operation, the opening degree of the second injection motor-operated valve (64b) is reduced as compared with the normal operation, and the second injection pipe line The flow rate of the intermediate pressure refrigerant in (62b) decreases compared to that during normal operation.

  When the determination condition is not satisfied in step ST61 (that is, when LP1 ≦ LP2), the motor-operated valve control unit (220) proceeds to step ST67. In step ST67, the electric valve control unit (220) determines whether or not the determination parameter F = 1. When the determination parameter F = 1, the motor-operated valve control unit (220) proceeds to step ST68 and performs an oil distribution operation. On the other hand, when the determination parameter F ≠ 1 (that is, F = 0), the motor-operated valve control unit (220) proceeds to step ST71 and performs a normal operation.

  In step ST71, the motor-operated valve control unit (220) sets the control target value of the discharge superheat degree Tdsh2 of the first fixed capacity compressor (40b) to the normal target value “25 ° C.”, and this discharge superheat degree Tdsh2 The opening degree of the second injection motor-operated valve (64b) is adjusted so that becomes 25 ° C. That is, in step ST71, the electric valve controller (220) performs the same operation as in step ST66. The electric valve control unit (220) executes this operation as a normal operation.

  On the other hand, in step ST68, the motor-operated valve control unit (220) determines whether or not it is in the first mode. When the motor-operated valve control unit (220) is in the first mode, the process proceeds to step ST69, and when not in the first mode (that is, in the second mode), the process proceeds to step ST70.

  During the first mode, the first fixed capacity compressor (40b) sucks the refrigerant from the first suction pipe (51). That is, the pressure of the refrigerant sucked into the first fixed capacity compressor (40b) is substantially equal to the pressure of the refrigerant sucked into the variable capacity compressor (40a). Therefore, in step ST69, the electric valve control unit (220) performs the same operation as in step ST46 of FIG. That is, the electric valve control unit (220) sets the control target value of the discharge superheat degree Tdsh2 of the first fixed capacity compressor (40b) to “30 ° C.” higher than the normal target value, and the discharge superheat degree Tdsh2 is The opening degree of the second injection motor-operated valve (64b) is adjusted to 30 ° C. When the target value of the discharge superheat degree Tdsh2 is raised from the normal target value by this oil distribution operation, the opening degree of the second injection motor-operated valve (64b) is reduced as compared with the normal operation, and the second injection pipe line The flow rate of the intermediate pressure refrigerant in (62b) decreases compared to that during normal operation.

  On the other hand, in the second mode, the first fixed capacity compressor (40b) sucks the refrigerant from the third suction pipe (53). That is, the pressure of the refrigerant sucked into the first fixed capacity compressor (40b) is substantially equal to the pressure of the refrigerant sucked into the second fixed capacity compressor (40c). Therefore, in step ST70, the electric valve control unit (220) performs the same operation as in step ST96 of FIG. That is, the electric valve control unit (220) sets the control target value of the discharge superheat degree Tdsh2 of the first fixed capacity compressor (40b) to “20 ° C.” lower than the normal target value, and the discharge superheat degree Tdsh2 is The opening degree of the second injection motor-operated valve (64b) is adjusted to 20 ° C. When the target value of the discharge superheat degree Tdsh2 is lowered from the normal target value by this oil distribution operation, the opening degree of the second injection motor-operated valve (64b) is increased as compared with the normal operation, and the second injection pipe line The flow rate of the intermediate-pressure refrigerant in (62b) increases compared to that during normal operation.

  When the operation of step ST52, step ST54, step ST56, or step ST57 in the control flow diagram of FIG. 14 ends, the motor-operated valve control unit (220) returns to step ST51 again. Then, the motor-operated valve control unit (220) repeatedly executes the operations shown in the control flowcharts of FIGS. 14 and 15 every 10 to 20 seconds, for example.

<Effects obtained by the oil return operation of the motorized valve controller>
First, for example, when normal heating operation is performed in the severe winter season when the outside air temperature is below freezing, the refrigerant evaporation temperature in the outdoor heat exchanger (44) is lower than the refrigerant evaporation temperature in the refrigeration heat exchanger (91). In such a case, the detection value LP1 of the first low-pressure sensor (71) is higher than the detection value LP2 of the second low-pressure sensor (72). That is, the pressure of the refrigerant sucked into the variable capacity compressor (40a) becomes higher than the pressure of the refrigerant sucked into the second fixed capacity compressor (40c). For this reason, in the variable capacity compressor (40a), the pressure in the compression chamber in the middle of compression communicating with the first injection pipe (62a) is changed in the second fixed capacity compressor (40c) by the third injection pipe (62c). The pressure in the compression chamber in the middle of compression communicating with Further, the compression ratio in the variable capacity compressor (40a) is smaller than the compression ratio in the second fixed capacity compressor (40c).

  On the other hand, when the determination parameter F = 0, the motor-operated valve control unit (220) performs a normal operation. That is, in this case, the motor-operated valve control unit (220) opens the opening of the first injection motor-operated valve (64a) so that the discharge superheat degree Tdsh1 of the variable capacity compressor (40a) becomes the normal target value (25 ° C.). (See step ST44 of FIG. 13), the third injection motor-operated valve (64c) is opened so that the discharge superheat degree Tdsh3 of the second fixed capacity compressor (40c) becomes the normal target value (25 ° C.). The degree is adjusted (see step ST94 in FIG. 17). Therefore, the flow rate of the intermediate pressure refrigerant flowing from the first injection pipe (62a) to the variable capacity compressor (40a) is changed from the third injection pipe (62c) to the second fixed capacity compressor (40c). It becomes less than the flow rate of the intermediate pressure refrigerant flowing in. As a result, during normal operation, the flow rate of the refrigeration oil flowing from the first injection pipe (62a) into the variable capacity compressor (40a) is changed from the third injection pipe (62c) to the second fixed capacity compression. The flow rate of the refrigerating machine oil flowing into the compressor (40c) becomes smaller, and the refrigerating machine oil storage amount in the variable capacity compressor (40a) decreases.

  Therefore, when the normal operation continues for a predetermined time (17 minutes in this embodiment) in a state where the detection value LP1 of the first low-pressure sensor (71) is higher than the detection value LP2 of the second low-pressure sensor (72), The motor-operated valve control unit (220) temporarily stops the normal operation and executes the oil distribution operation in order to increase the amount of refrigerating machine oil stored in the variable capacity compressor (40a). Specifically, the electric valve controller (220) lowers the control target value of the discharge superheat degree Tdsh1 of the variable capacity compressor (40a) from the normal target value (25 ° C.) to 20 ° C. (see step ST43 in FIG. 13). ), The control target value of the discharge superheat degree Tdsh3 of the second fixed capacity compressor (40c) is raised from the normal target value (25 ° C.) to 30 ° C. (see step ST93 in FIG. 17).

  The determination parameter setting unit (221) of the electric valve control unit (220) holds the value of the determination parameter F at “1” for a predetermined time (3 minutes in the present embodiment). For this reason, the motor-operated valve control unit (220) of the present embodiment performs the oil distribution operation for 3 minutes, and then stops the oil distribution operation and resumes the normal operation.

  When the control target value of the discharge superheat degree Tdsh1 of the variable capacity compressor (40a) is lowered to 20 ° C., the opening degree of the first injection motor-operated valve (64a) is larger than that during normal operation. On the other hand, when the control target value of the discharge superheat degree Tdsh3 of the second fixed capacity compressor (40c) is raised to 30 ° C., the opening degree of the third injection motor-operated valve (64c) is smaller than that during normal operation. For this reason, the flow rates of the intermediate pressure refrigerant and the refrigeration oil supplied from the first injection pipe (62a) to the variable capacity compressor (40a) are increased, and the second fixed capacity is supplied from the third injection pipe (62c). The flow rates of the intermediate pressure refrigerant and the refrigerating machine oil supplied to the compressor (40c) are reduced. As a result, the amount of refrigerating machine oil stored in the variable capacity compressor (40a) is increased, and the amount of refrigerating machine oil stored in the second fixed capacity compressor (40c) is also maintained at an appropriate value.

  Next, when performing the cooling operation, the refrigerant evaporating temperature in the air conditioning heat exchanger (81) is higher than the refrigerant evaporating temperature in the refrigeration heat exchanger (91), so that the second low pressure sensor (72) The detection value LP2 becomes higher than the detection value LP1 of the first low-pressure sensor (71). That is, the pressure of the refrigerant sucked into the second fixed capacity compressor (40c) becomes higher than the pressure of the refrigerant sucked into the variable capacity compressor (40a). Therefore, the pressure in the compression chamber in the middle of compression communicating with the third injection pipe (62c) in the second fixed capacity compressor (40c) is changed to the first injection pipe (62a) in the variable capacity compressor (40a). The pressure in the compression chamber in the middle of compression communicating with Further, the compression ratio in the second fixed capacity compressor (40c) is smaller than the compression ratio in the variable capacity compressor (40a).

  On the other hand, when the determination parameter F = 0, the motor-operated valve control unit (220) performs a normal operation. That is, in this case, the motor-operated valve control unit (220) opens the opening of the first injection motor-operated valve (64a) so that the discharge superheat degree Tdsh1 of the variable capacity compressor (40a) becomes the normal target value (25 ° C.). (See step ST47 in FIG. 13), the third injection motor-operated valve (64c) is opened so that the discharge superheat degree Tdsh3 of the second fixed capacity compressor (40c) becomes the normal target value (25 ° C.). The degree is adjusted (see step ST97 in FIG. 17). Therefore, the flow rate of the intermediate pressure refrigerant flowing from the third injection pipe (62c) to the second fixed capacity compressor (40c) is changed from the first injection pipe (62a) to the variable capacity compressor (40a). It becomes less than the flow rate of the intermediate pressure refrigerant flowing in. As a result, during normal operation, the flow rate of the refrigeration oil flowing from the third injection pipe (62c) to the second fixed capacity compressor (40c) is variable compression from the first injection pipe (62a). The flow rate of the refrigerating machine oil flowing into the machine (40a) becomes smaller, and the refrigerating machine oil storage amount in the second fixed capacity compressor (40c) decreases.

  Therefore, when the normal operation continues for a predetermined time (17 minutes in this embodiment) in a state where the detection value LP2 of the second low-pressure sensor (72) is higher than the detection value LP1 of the first low-pressure sensor (71), The motor-operated valve control unit (220) temporarily stops the normal operation and executes the oil distribution operation in order to increase the amount of refrigerating machine oil stored in the second fixed capacity compressor (40c). Specifically, the electric valve controller (220) raises the control target value of the discharge superheat degree Tdsh1 of the variable capacity compressor (40a) from the normal target value (25 ° C.) to 30 ° C. (see step ST46 in FIG. 13). ), The control target value of the discharge superheat degree Tdsh3 of the second fixed capacity compressor (40c) is lowered from the normal target value (25 ° C.) to 20 ° C. (see step ST96 in FIG. 17).

  When the control target value of the discharge superheat degree Tdsh1 of the variable capacity compressor (40a) is raised to 30 ° C., the opening degree of the first injection motor-operated valve (64a) is smaller than that during normal operation. On the other hand, when the control target value of the discharge superheat degree Tdsh3 of the second fixed capacity compressor (40c) is lowered to 20 ° C., the opening degree of the third injection motor operated valve (64c) becomes larger than that during normal operation. For this reason, the flow rates of the intermediate pressure refrigerant and the refrigerating machine oil supplied from the third injection pipe (62c) to the second fixed capacity compressor (40c) are increased, and the variable capacity is supplied from the first injection pipe (62a). The flow rates of the intermediate pressure refrigerant and the refrigerating machine oil supplied to the compressor (40a) are reduced. As a result, the amount of refrigerating machine oil stored in the second fixed capacity compressor (40c) is increased, and the amount of refrigerating machine oil stored in the variable capacity compressor (40a) is also maintained at an appropriate value.

  The motor-operated valve controller (220) also performs an oil distribution operation for the second injection motor-operated valve (64b).

  During the first mode, the first fixed capacity compressor (40b) sucks refrigerant from the first suction pipe (51) in the same manner as the variable capacity compressor (40a). For this reason, when the normal operation is executed in the state where the detection value LP1 of the first low-pressure sensor (71) is higher than the detection value LP2 of the second low-pressure sensor (72) during the first mode, the first injection pipe The refrigerant flow rate in the passage (62a) and the second injection pipeline (62b) is smaller than the refrigerant flow rate in the third injection pipeline (62c), and the variable capacity compressor (40a) and the first fixed capacity compressor ( The amount of refrigerant stored in 40b) will decrease. Therefore, in this case, the motor-operated valve controller (220) operates to lower the control target value of the discharge superheat degree Tdsh2 of the first fixed capacity compressor (40b) from the normal target value (25 ° C.) to 20 ° C. (FIG. 15). Step ST64) is temporarily executed as an oil distribution operation, and the amount of refrigerant stored in the first fixed capacity compressor (40b) is increased.

  Further, when the normal operation is executed in the state where the detection value LP2 of the second low-pressure sensor (72) is higher than the detection value LP1 of the first low-pressure sensor (71) during the first mode, the third injection conduit The refrigerant flow rate in (62c) is less than the refrigerant flow rate in the first injection pipe (62a) and the second injection pipe (62b), and the amount of refrigerant stored in the second fixed capacity compressor (40c) is reduced. I will do it. Therefore, in this case, the motor-operated valve controller (220) raises the control target value of the discharge superheat degree Tdsh2 of the first fixed capacity compressor (40b) from the normal target value (25 ° C.) to 30 ° C. (FIG. 15). Step ST69) is temporarily executed as an oil distribution operation. As a result, the refrigerant flow rate in the second injection conduit (62b) decreases, the refrigerant flow rate in the third injection conduit (62c) increases, and the amount of refrigerant stored in the second fixed capacity compressor (40c) increases. To increase.

  On the other hand, during the second mode, the first fixed capacity compressor (40b) sucks the refrigerant from the third suction pipe (53) in the same manner as the second fixed capacity compressor (40c). For this reason, if the normal operation is executed in the state where the detection value LP1 of the first low-pressure sensor (71) is higher than the detection value LP2 of the second low-pressure sensor (72) during the second mode, the first injection pipe The refrigerant flow rate in the passage (62a) is smaller than the refrigerant flow rate in the second injection pipe (62b) and the third injection pipe (62c), and the refrigerant storage amount in the variable capacity compressor (40a) is reduced. Go. Therefore, in this case, the motor-operated valve controller (220) raises the control target value of the discharge superheat degree Tdsh2 of the first fixed capacity compressor (40b) from the normal target value (25 ° C.) to 30 ° C. (FIG. 15). Step ST65) is temporarily executed as an oil distribution operation. As a result, the refrigerant flow rate in the second injection pipeline (62b) decreases, the refrigerant flow rate in the first injection pipeline (62a) increases, and the refrigerant storage amount in the variable capacity compressor (40a) increases. .

  Further, when the normal operation is performed in the second mode in a state where the detection value LP2 of the second low-pressure sensor (72) is higher than the detection value LP1 of the first low-pressure sensor (71), the second injection conduit (62b) and the refrigerant flow rate in the third injection pipeline (62c) are smaller than the refrigerant flow rate in the first injection pipeline (62a), and the refrigerant storage amount in the first fixed capacity compressor (40b) is reduced. I will do it. Therefore, in this case, the motor-operated valve controller (220) operates to lower the control target value of the discharge superheat degree Tdsh2 of the first fixed capacity compressor (40b) from the normal target value (25 ° C.) to 20 ° C. (FIG. 15). Step ST70) is temporarily executed as an oil distribution operation. As a result, the refrigerant flow rate in the second injection pipe (62b) increases, and the refrigerant storage amount in the first fixed capacity compressor (40b) increases.

-Control operation of intermediate pressure control section-
An operation performed by the intermediate pressure control unit (225) of the controller (200) will be described. As described above, the intermediate pressure control unit (225) adjusts the opening degree of the supercooling expansion valve (63). The control operation performed by the intermediate pressure control unit (225) will be described with reference to the control flowchart of FIG.

  In Step ST101, the intermediate pressure control unit (225) determines whether or not a condition that both the variable capacity compressor (40a) and the second fixed capacity compressor (40c) are operating is satisfied. The intermediate pressure control unit (225) proceeds to step ST102 when this condition is satisfied, and proceeds to step ST103 when this condition is not satisfied.

  In step ST102, the intermediate pressure control unit (225) determines that the detected value MP of the intermediate pressure sensor (73) (that is, the measured value of the pressure of the intermediate pressure refrigerant flowing through the main injection pipe (61)) is a predetermined target intermediate pressure. The opening degree of the supercooling expansion valve (63) is adjusted so as to be MPs.

  Here, when both the variable capacity compressor (40a) and the second fixed capacity compressor (40c) are in operation, both the variable capacity compressor (40a) and the second fixed capacity compressor (40c) are operated. It is necessary to flow in the intermediate pressure refrigerant. For this purpose, the pressure of the intermediate pressure refrigerant flowing through the main injection pipe (61) is changed between the pressure of the compression chamber in the middle of compression communicating with the first injection pipe (62a) in the variable capacity compressor (40a), In the two-fixed capacity compressor (40c), it is necessary to set a value higher than both of the pressures in the compression chambers in the middle of compression communicating with the third injection pipe (62c).

  On the other hand, the pressure in the compression chamber in the middle of compression in the variable capacity compressor (40a) can be estimated from the pressure of the refrigerant sucked into the variable capacity compressor (40a), and in the second fixed capacity compressor (40c). The pressure in the compression chamber during compression can be estimated from the pressure of the refrigerant sucked into the second fixed capacity compressor (40c). Therefore, the intermediate pressure control unit (225) uses the detection value LP1 of the first low-pressure sensor (71) and the detection value LP2 of the second low-pressure sensor (72) to connect the variable capacity compressor (40a) to the second fixed compressor. A value of the target intermediate pressure MPs that allows the intermediate pressure refrigerant to flow into both of the capacity compressors (40c) is calculated, and the subcooling expansion valve (63) is opened using the calculated target intermediate pressure MPs. Adjust the degree. Therefore, during the operation of both the variable capacity compressor (40a) and the second fixed capacity compressor (40c), both the variable capacity compressor (40a) and the second fixed capacity compressor (40c) are injected. The intermediate pressure refrigerant is reliably supplied from the circuit (60).

  In step ST103, the intermediate pressure control unit (225) determines that the superheat degree SHm of the intermediate pressure refrigerant flowing out from the second flow path (67) of the supercooling heat exchanger (65) is a predetermined target value (in this embodiment). The opening degree of the supercooling expansion valve (63) is adjusted so that the temperature becomes 5 ° C. In the state where only one of the variable capacity compressor (40a) and the second fixed capacity compressor (40c) is in operation, the pressure of the intermediate pressure refrigerant flowing through the main injection pipe (61) is the variable capacity compressor (40a). ) And the second fixed capacity compressor (40c), whichever is being operated, the pressure is necessarily higher than the pressure in the compression chamber in the middle of compression communicating with the injection pipes (62a, 62c). That is, in this state, it is not necessary to adjust the opening degree of the subcooling expansion valve (63) in consideration of the pressure of the intermediate pressure refrigerant flowing through the main injection pipe (61).

  Therefore, in this case, the intermediate pressure control unit (225) adjusts the opening degree of the supercooling expansion valve (63) so that the superheat degree SHm of the intermediate pressure refrigerant becomes the target value. As a result, the flow rate of the intermediate pressure refrigerant supplied to the second flow path (67) of the supercooling heat exchanger (65) is maintained at a sufficient value as required, and the supercooling heat exchanger (65) The high-pressure refrigerant flowing through the first channel (66) can be reliably cooled.

<< Other Embodiments >>
-First modification-
In each of the above embodiments, the opening degree of one of the first injection motor-operated valve (64a) and the third injection motor-operated valve (64c) is larger than that during normal operation, and the other opening degree is larger than that during normal operation. The reducing operation is executed as an oil distribution operation.

  On the other hand, in each of the above-described embodiments, only one opening of the first injection motor-operated valve (64a) and the third injection motor-operated valve (64c) is enlarged as compared with that during normal operation to increase the other opening. The operation of keeping the same value as that during the normal operation may be executed as the oil distribution operation. For example, when only the opening of the first injection motor-operated valve (64a) is enlarged and the opening of the third injection motor-operated valve (64c) is kept at the same value as during normal operation, the first injection conduit The refrigerant flow rate in (62a) increases, and accordingly, the refrigerant flow rate in the third injection pipe (62c) decreases.

  Further, in each of the above-described embodiments, only one opening of the first injection motor-operated valve (64a) and the third injection motor-operated valve (64c) is reduced as compared with the normal operation, and the other opening is operated normally. The operation of keeping the same value as the inside may be executed as the oil distribution operation. For example, when reducing the opening of the third injection motor operated valve (64c) while maintaining the opening of the first injection motor operated valve (64a) at the same value as during normal operation, the third injection conduit is used. The refrigerant flow rate in (62c) decreases, and accordingly, the refrigerant flow rate in the first injection pipe (62a) increases.

-Second modification-
In each of the above embodiments, each injection pipe (62a to 62c) is provided with an injection motor valve (64a, 64b, 64c) whose opening degree is variable, and the opening of the injection motor valve (64a, 64b, 64c). Is adjusted to adjust the flow rate of refrigerant in each injection pipe (62a to 62c). On the other hand, an openable / closable electromagnetic valve may be provided in each injection pipe (62a to 62c), and the refrigerant flow rate in each injection pipe (62a to 62c) may be adjusted by this solenoid valve. In this case, the refrigerant flow rate in each of the injection conduits (62a to 62c) is adjusted by changing the time during which the solenoid valve is kept open. That is, when increasing the refrigerant flow rate in the injection pipelines (62a to 62c), the time for holding the electromagnetic valve in the open state is lengthened. Conversely, when the refrigerant flow rate in the injection pipelines (62a to 62c) is decreased, the time for holding the solenoid valve in the open state is shortened.

-Third modification-
In each of the above embodiments, all of the injection conduits (62a, 62b, 62c) of the injection circuit (60) are provided with the injection motor operated valves (64a, 64b, 64c). It is also possible to provide an injection motor-operated valve only in the injection conduit. That is, for example, when only the cooling pressure of the first suction pipe (51) or the third suction pipe (53) is known in advance, such as when performing only the cooling operation of the second embodiment, the pressure is low. The injection motor-operated valve (64a) may be provided only in the injection pipe (62a) connected to the compressor (40a) that sucks the refrigerant from the other suction pipe (51).

  As described above, the present invention is useful for a refrigerating apparatus that supplies refrigerating machine oil separated from refrigerant discharged from a compressor to a compressor together with an intermediate pressure refrigerant.

10 Refrigeration equipment
20 Refrigerant circuit
40a Variable capacity compressor (first compressor)
40b 1st fixed capacity compressor (3rd compressor)
40c 2nd fixed capacity compressor (2nd compressor)
44 Outdoor heat exchanger (condenser, second evaporator)
49 Oil return circuit
60 Injection circuit
61 Main injection pipeline
62a First injection pipeline (first branch pipeline)
62b Second injection pipe (third branch pipe)
62c 3rd injection pipeline (2nd branch pipeline)
63 Expansion valve for supercooling (intermediate pressure side expansion valve)
64a Motor valve for 1st injection (1st flow control valve)
64b Motor valve for second injection (third flow control valve)
64c Electric valve for third injection (second flow control valve)
65 Heat exchanger for supercooling
81 Heat exchanger for air conditioning (second evaporator, condenser)
91 Heat exchanger for refrigeration (first evaporator)
220 Motorized valve control unit (opening control unit)
225 Intermediate pressure control unit
250 Flow control mechanism

Claims (7)

It has a refrigerant circuit (20) that performs the refrigeration cycle,
The refrigerant circuit (20)
A first evaporator (91);
A second evaporator (81,44);
A first compressor (40a) for sucking refrigerant evaporated in the first evaporator (91);
A second compressor (40c) for sucking the refrigerant evaporated in the second evaporator (81, 44);
A condenser (44, 81) into which refrigerant discharged from the first compressor (40a) and the second compressor (40c) flows;
The main injection pipe (61) through which the intermediate pressure refrigerant flows, the first branch pipe (62a) connecting the main injection pipe (61) to the first compressor (40a), and the main injection pipe (61 ) To the second compressor (40c), an injection circuit (60) having a second branch line (62c);
An oil return circuit (49) for supplying refrigeration oil separated from refrigerant discharged from the first compressor (40a) and the second compressor (40c) to the main injection pipe (61),
A flow rate adjusting mechanism (250) for performing a normal operation for adjusting the refrigerant flow rate in the first branch line (62a) and the second branch line (62c) so that the control physical quantity becomes a predetermined control target value; Prepared,
The flow rate adjusting mechanism (250)
The condition that the pressure of the suction refrigerant of the first compressor (40a) is higher than the pressure of the suction refrigerant of the second compressor (40c), and the pressure of the suction refrigerant of the first compressor (40a) is the first pressure. One of the conditions that the pressure of the refrigerant sucked in the two compressors (40c) is equal to or higher than the determination condition,
When the determination condition is satisfied, the refrigerant flow rate in the first branch pipe (62a) is increased from that during the normal operation, and the refrigerant flow rate in the second branch pipe (62c) is increased from that during the normal operation. Is also intermittently executed as an oil distribution operation.
When the determination condition is not satisfied, the refrigerant flow rate in the first branch pipe (62a) is decreased compared to that during the normal operation, and the refrigerant flow rate in the second branch pipe (62c) is decreased from that during the normal operation. The refrigeration apparatus is characterized by intermittently executing an operation for increasing oil as an oil distribution operation. In claim 1,
The flow rate adjusting mechanism (250)
A first flow control valve (64a) provided in the first branch pipe (62a);
A second flow control valve (64c) provided in the second branch pipe (62c);
An opening degree control unit (220) for controlling the opening degree of the first flow rate adjustment valve (64a) and the second flow rate adjustment valve (64c) so that the control physical quantity becomes a predetermined control target value; And
The opening control unit (220)
As the oil distribution operation when the determination condition is satisfied, an operation of expanding the opening of the first flow rate control valve (64a) than that during the normal operation, and an opening of the second flow rate control valve (64c). Perform one or both of the operations to reduce the above than during normal operation,
As an operation for oil distribution when the determination condition is not satisfied, an operation for reducing the opening of the first flow rate control valve (64a) than that during the normal operation, and an opening of the second flow rate control valve (64c). A refrigeration apparatus that performs one or both of operations for enlarging the above-described operation during normal operation. In claim 2,
The opening control unit (220)
Using the temperature or superheat degree of the refrigerant discharged from the first compressor (40a) as a first control physical quantity, the first flow rate adjustment is performed so that the first control physical quantity becomes a first control target value. Adjust the opening of the valve (64a)
Using the temperature or superheat degree of the refrigerant discharged from the second compressor (40c) as a second control physical quantity, the second flow rate adjustment is performed so that the second control physical quantity becomes a second control target value. Adjusting the opening of the valve (64c)
During the normal operation, the first and second control target values are set to predetermined normal target values, and the opening amounts of the first flow rate control valve (64a) and the second flow rate control valve (64c) are set. While adjusting
When the opening degree of the first flow rate control valve (64a) is expanded during the oil distribution operation as compared with that during the normal operation, the first control target value is set to a value lower than the normal target value. ,
When the opening degree of the first flow rate control valve (64a) is reduced during the oil distribution operation as compared to during the normal operation, the first control target value is set to a value higher than the normal target value. ,
When the opening degree of the second flow rate control valve (64c) is increased during the oil distribution operation as compared with that during the normal operation, the second control target value is set to a value lower than the normal target value. ,
When the opening degree of the second flow rate control valve (64c) is reduced during the oil distribution operation as compared to during the normal operation, the second control target value is set to a value higher than the normal target value. A refrigeration apparatus characterized by that. In claim 1,
The flow rate adjusting mechanism (250)
Using the temperature or superheat degree of the refrigerant discharged from the first compressor (40a) as a first control physical quantity, the first branch pipe is set so that the first control physical quantity becomes the first control target value. Adjusting the refrigerant flow rate in the channel (62a),
Using the temperature or superheat degree of the refrigerant discharged from the second compressor (40c) as the second control physical quantity, the second branch pipe so that the second control physical quantity becomes the second control target value. A refrigeration apparatus that adjusts a refrigerant flow rate in the passage (62c). In claim 1,
The refrigerant circuit (20) includes a third compressor that selectively sucks one of the refrigerant evaporated in the first evaporator (91) and the refrigerant evaporated in the second evaporator (81, 44). 40b)
The injection circuit (60) is provided with a third branch line (62b) for connecting the main injection line (61) to the third compressor (40b),
The oil return circuit (49) is configured to supply refrigeration oil separated from refrigerant discharged from the first compressor (40a), the second compressor (40c), and the third compressor (40b) to the main injection line (61). While supplying to
The flow rate adjusting mechanism (250)
A first flow control valve (64a) provided in the first branch pipe (62a);
A second flow control valve (64c) provided in the second branch pipe (62c);
A third flow control valve (64b) provided in the third branch pipe (62b);
An opening degree for controlling the opening degree of the first flow rate adjustment valve (64a), the second flow rate adjustment valve (64c), and the third flow rate adjustment valve (64b) so that the control physical quantity becomes a predetermined control target value. A control unit (220),
The opening control unit (220)
In a state where the third compressor (40b) sucks the refrigerant evaporated in the first evaporator (91),
As the oil distribution operation when the determination condition is satisfied, an operation of expanding the opening degree of the first flow rate control valve (64a) and the third flow rate control valve (64b) than during the normal operation, Execute one or both of the operations to reduce the opening of the flow control valve (64c) than during normal operation,
As an oil distribution operation when the determination condition is not satisfied, an operation of reducing the opening degree of the first flow rate control valve (64a) and the third flow rate control valve (64b) than during the normal operation, Execute one or both of the operations to increase the opening of the flow control valve (64c) than during normal operation,
In a state where the third compressor (40b) sucks the refrigerant evaporated in the second evaporator (81, 44),
As the oil distribution operation when the determination condition is satisfied, the operation of expanding the opening of the first flow rate control valve (64a) than that during the normal operation, the second flow rate control valve (64c), and the third Execute one or both of the operations to reduce the opening of the flow control valve (64b) than during normal operation,
As the oil distribution operation in the case where the determination condition is not satisfied, the operation of reducing the opening of the first flow rate control valve (64a) than that during the normal operation, the second flow rate control valve (64c), and the third A refrigeration apparatus that performs one or both of operations for enlarging the opening degree of the flow rate control valve (64b) than during the normal operation. In any one of Claims 1 thru | or 5,
The flow rate adjusting mechanism (250)
The duration of the oil distribution operation is extended as the difference between the suction refrigerant pressure of the first compressor (40a) and the suction refrigerant pressure of the second compressor (40c) increases. Refrigeration equipment. In any one of Claims 1 thru | or 6,
The injection circuit (60)
An intermediate pressure side expansion valve (63) provided in the main injection pipe (61) for expanding the high pressure refrigerant into an intermediate pressure refrigerant;
The high-pressure liquid refrigerant flowing from the condenser (44,81) toward at least one of the first evaporator (91) and the second evaporator (81,44) flows through the main injection pipe (61). It is connected to a supercooling heat exchanger (65) that heats and cools the intermediate pressure refrigerant,
When both the first compressor (40a) and the second compressor (40c) are in operation, the pressure of the intermediate pressure refrigerant flowing through the main injection pipe (61) becomes a predetermined target pressure. When the opening of the intermediate pressure side expansion valve (63) is adjusted and one of the first compressor (40a) and the second compressor (40c) is operating and the other is stopped, An intermediate pressure control unit (225) for adjusting the opening of the intermediate pressure side expansion valve (63) so that the superheat degree of the intermediate pressure refrigerant flowing out from the cooling heat exchanger (65) becomes a predetermined target superheat degree; A refrigeration apparatus characterized by comprising:

Images