JP2010025446A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve operating efficiency of a refrigerating device provided with a cooling means for cooling a refrigerant supplied to cooling heat exchangers. <P>SOLUTION: The refrigerating device includes a control means (110) for switching between: a first operation for controlling a refrigerant circuit (4) so that during the cooling operation in which the cooling heat exchangers (64a, 64b) operate as evaporators, when the temperature of the refrigerant cooled by the cooling means (100) is higher than a prescribed reference value, the evaporation temperature of the refrigerant in the cooling heat exchangers (64a, 64b) becomes a first target value; and a second operation for controlling the refrigerant circuit (4) so that when the temperature of the refrigerant cooled by the cooling means (100) is the reference value or less, the evaporation temperature of the refrigerant in the cooling heat exchangers (64a, 64b) becomes a second target value that is higher than the first target value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus provided with cooling means for cooling a refrigerant supplied to a cooling heat exchanger.

  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 that store foods and the like, refrigerators such as freezers, and air conditioners that heat and cool indoors.

Patent Document 1 discloses a refrigeration apparatus provided with an injection pipe for injecting a refrigerant into each compressor of a compression mechanism. The injection pipe is branched with respect to each compressor, and the branched pipe is connected to an intermediate pressure compression chamber of each compressor. The injection pipe is connected to the supercooling heat exchanger just before branching to each compressor. In the supercooling heat exchanger, the refrigerant going to the internal heat exchanger is cooled by the intermediate-pressure refrigerant in the injection pipe.
JP 2007-178052 A

  By the way, in a refrigeration apparatus provided with a cooling means for cooling the refrigerant supplied to the cooling heat exchanger (for example, the injection pipe and the supercooling heat exchanger of Cited Document 1), the cooling is performed by the cooling means according to the operating state. In some cases, the temperature of the cooled refrigerant, that is, the temperature of the refrigerant supplied to the cooling heat exchanger may change. However, in the conventional refrigeration apparatus, it is not considered how to control the refrigerant circuit to improve the operation efficiency of the refrigeration apparatus when the temperature of the refrigerant cooled by the cooling means changes.

  This invention is made | formed in view of this point, The objective is to improve the operating efficiency of the freezing apparatus provided with the cooling means which cools the refrigerant | coolant supplied to a cooling heat exchanger.

  The first invention is a cooling heat exchanger (64a, 64b) for cooling a target space, and a cooling compressor (14a, 86) for sucking refrigerant evaporated in the cooling heat exchanger (64a, 64b). And a refrigerant circuit (4) that circulates refrigerant to perform a refrigeration cycle, and in which the cooling heat exchanger (64a, 64b) operates as an evaporator in the refrigerant circuit (4). Refrigeration equipment (1). The refrigeration apparatus (1) includes a cooling means (100) for cooling the refrigerant supplied to the cooling heat exchanger (64a, 64b) during the cooling operation, and the cooling unit during the cooling operation. When the temperature of the refrigerant cooled by the means (100) becomes higher than a predetermined reference value, the refrigerant circuit (in such a manner that the evaporating temperature of the refrigerant in the cooling heat exchanger (64a, 64b) becomes the first target value. 4) when the temperature of the refrigerant cooled by the cooling means (100) is equal to or lower than the reference value, the evaporation temperature of the refrigerant in the cooling heat exchanger (64a, 64b) is And a control means (110) for switching and performing a second operation for controlling the refrigerant circuit (4) so that the second target value is higher than the one target value.

  In the first invention, the control means (110) switches between the first action and the second action according to the temperature of the refrigerant cooled by the cooling means (100) (hereinafter referred to as “cooled refrigerant”). Do it. The first operation is performed when the temperature of the cooled refrigerant becomes higher than the reference value. In the first operation, the refrigerant circuit (4) is controlled such that the evaporation temperature of the refrigerant in the cooling heat exchanger (64a, 64b) becomes the first target value. On the other hand, the second operation is performed when the temperature of the cooled refrigerant is equal to or lower than the reference value. In the second operation, the temperature of the refrigerant flowing into the cooling heat exchanger (64a, 64b) is lower than that in the first operation. In the second operation, the refrigerant circuit (4) is controlled such that the evaporation temperature of the refrigerant in the cooling heat exchanger (64a, 64b) becomes a second target value higher than that in the first operation.

  Here, when the target value of the evaporating temperature of the refrigerant in the cooling heat exchanger (64a, 64b) becomes high, the refrigerant circuit (4) is arranged so that the flow rate of the refrigerant passing through the cooling heat exchanger (64a, 64b) decreases. Be controlled. For this reason, the cooling compressor (14a, 86) requires less energy for boosting the refrigerant. That is, the energy consumption of the cooling compressor (14a, 86) is reduced. Moreover, when the target value of the refrigerant evaporation temperature in the cooling heat exchanger (64a, 64b) increases, the pressure of the refrigerant sucked in the cooling compressor (14a, 86) increases, and the cooling compressor (14a, 86) Because the pressure difference between the intake refrigerant and the discharge refrigerant becomes small, the target value of the refrigerant evaporation temperature in the cooling heat exchanger (64a, 64b) simply passes through the cooling heat exchanger (64a, 64b) without changing. The energy consumption of the cooling compressor (14a, 86) is reduced as compared with the case where the flow rate of the refrigerant is reduced.

  Further, in the cooling heat exchanger (64a, 64b), the lower the temperature of the refrigerant flowing in, the larger the enthalpy difference between the refrigerant at the inlet and the outlet, so that the refrigerant cooling capacity per unit flow rate becomes higher. For this reason, when the temperature of the refrigerant flowing into the cooling heat exchanger (64a, 64b) becomes low to some extent, even if the flow rate of the refrigerant passing through the cooling heat exchanger (64a, 64b) is reduced, the cooling heat The cooling capacity in the exchangers (64a, 64b) does not change significantly. In the first invention, when the temperature of the refrigerant flowing into the cooling heat exchanger (64a, 64b) is lowered to some extent, the flow rate of the refrigerant passing through the cooling heat exchanger (64a, 64b) is reduced to some extent. The target value of the refrigerant evaporation temperature in the cooling heat exchanger (64a, 64b) is changed to a high value so that the energy consumption of the cooling compressor (14a, 86) is reduced. .

  According to a second aspect of the present invention, in the first aspect, the refrigerant circuit (4) includes a first passage provided with the cooling heat exchanger (64a) and the cooling heat exchanger (64a) in the cooling operation. A low temperature side heat exchanger (64b) in which the refrigerant evaporating temperature is set to a lower value, and a low stage side compressor (86) for compressing the refrigerant evaporated in the low temperature side heat exchanger (64b). In the cooling operation, the refrigerant cooled by the cooling means (100) is transferred to the cooling heat exchanger (64a, 64b) and the low temperature side heat exchanger (64b). The cooling compressor (14a, 86) supplied and compresses the refrigerant discharged from the low-stage compressor (86) together with the refrigerant evaporated in the cooling heat exchanger (64a, 64b), while During the first operation, the control means (110) determines that the refrigerant evaporation temperature in the low temperature side heat exchanger (64b) is the third target. The refrigerant circuit (4) is controlled to be a value, and during the second operation, the refrigerant evaporation temperature in the low temperature side heat exchanger (64b) becomes a fourth target value higher than the third target value. Thus, the refrigerant circuit (4) is controlled.

  In the second aspect of the invention, the refrigerant circuit (4) has a low temperature side in parallel with the cooling heat exchanger (64a), and the refrigerant evaporating temperature is set lower than that of the cooling heat exchanger (64a) in the cooling operation. A heat exchanger (64b) is provided. In the cooling operation, the cooled refrigerant is supplied not only to the cooling heat exchanger (64a) but also to the low temperature side heat exchanger (64b). During the second operation, the temperature of the refrigerant flowing into the low temperature side heat exchanger (64b) is also lower than that during the first operation. Similarly to the cooling heat exchanger (64a), the control means (110) during the second operation is configured so that the refrigerant evaporating temperature in the low temperature side heat exchanger (64b) is higher than that during the first operation. 4) control.

  Here, the refrigerant circuit (4) is controlled so that the flow rate of the refrigerant passing through the low temperature side heat exchanger (64b) decreases when the target value of the refrigerant evaporating temperature increases also in the low temperature side heat exchanger (64b). The For this reason, the energy consumption of the low stage compressor (86) is reduced. In addition, when the target value of the evaporation temperature of the refrigerant in the low-temperature side heat exchanger (64b) increases, the pressure of the refrigerant sucked in the low-stage compressor (86) increases, and the refrigerant sucked in the low-stage compressor (86) Since the pressure difference between the refrigerant and the discharge refrigerant becomes smaller, the flow rate of the refrigerant passing through the low temperature side heat exchanger (64b) is simply reduced without changing the target value of the refrigerant evaporation temperature in the low temperature side heat exchanger (64b). Compared with the case where it does, the energy consumption of the low stage side compressor (86) decreases.

  Moreover, in the low temperature side heat exchanger (64b), the cooling capacity of the refrigerant per unit flow rate increases as the temperature of the flowing refrigerant decreases. For this reason, when the temperature of the refrigerant flowing into the low temperature side heat exchanger (64b) becomes low to some extent, even if the flow rate of the refrigerant passing through the low temperature side heat exchanger (64b) is reduced, the low temperature side heat exchange The cooling capacity in the vessel (64b) does not change much. In the second aspect of the invention, when the temperature of the refrigerant flowing into the low temperature side heat exchanger (64b) becomes low to some extent, the flow rate of the refrigerant passing through the low temperature side heat exchanger (64b) can be reduced to some extent. Focusing on what can be done, the target value of the refrigerant evaporation temperature in the low-temperature side heat exchanger (64b) is changed to a high value so that the energy consumption of the low-stage compressor (86) is reduced.

  In a third aspect based on the first aspect, the refrigerant circuit (4) is provided with a high stage compressor (14) for compressing the refrigerant discharged from the cooling compressor (86). Yes.

  In the third aspect of the invention, in the refrigerant circuit (4) during the cooling operation, the refrigerant evaporated in the cooling heat exchanger (64b) is sucked and compressed by the cooling compressor (86), and the cooling compressor (86) The high-stage compressor (14) sucks and compresses the refrigerant discharged from the compressor. That is, in the refrigerant circuit (4) during the cooling operation, a two-stage compression refrigeration cycle is performed.

  In a fourth aspect of the present invention based on any one of the first to third aspects, the cooling means (100) includes an intermediate pressure compression chamber (73) of the cooling compressor (14a) in the middle of the refrigeration cycle. An injection passage (30) for injecting a refrigerant having a pressure, and an intermediate heat exchanger (30a) for cooling the refrigerant supplied to the cooling heat exchanger (64a, 64b) by the intermediate pressure refrigerant in the injection passage (30) 16, 17).

  In the fourth invention, the cooling means (100) includes the injection passage (30) and the intermediate heat exchangers (16, 17). The injection passage (30) is connected to the intermediate pressure compression chamber (73) of the cooling compressor (14a) and is injected into the intermediate pressure compression chamber (73) of the cooling compressor (14a). The refrigerant flows. In the intermediate heat exchanger (16, 17), the refrigerant supplied to the cooling heat exchanger (64a, 64b) is cooled by exchanging heat with the intermediate-pressure refrigerant in the injection passage (30).

  Here, as the cooling means (100), for example, in the refrigerant circuit (4) that performs two-stage expansion in the cooling operation, an expansion valve (66) that depressurizes the refrigerant from the high pressure of the refrigeration cycle to the intermediate pressure, and the expansion valve ( A combination with a gas-liquid separator (85) that separates the refrigerant reduced to the intermediate pressure in 66) into liquid refrigerant and gas refrigerant is also conceivable (see FIG. 12). In the case of this combination, the lower the pressure of the intermediate refrigerant after passing through the expansion valve (66), the lower the temperature of the refrigerant supplied to the cooling heat exchanger (64a, 64b). Always becomes saturated and does not overcool. In contrast, in the fourth aspect of the invention, since the intermediate heat exchanger (16, 17) is used for cooling the refrigerant supplied to the cooling heat exchanger (64a, 64b), the cooled refrigerant is in a supercooled state. It is possible to Therefore, in the second operation of the fourth invention, it is possible to increase the cooling capacity per unit flow rate of the refrigerant flowing into the cooling heat exchanger (64a, 64b) as compared with the case of the above combination.

  In the present specification, the “intermediate pressure compression chamber (73)” means a compression chamber communicating with the injection passage (30). The internal pressure of the intermediate pressure compression chamber (73) is an intermediate pressure between the high pressure and the low pressure in the refrigeration cycle.

  According to a fifth aspect, in the fourth aspect, the refrigerant circuit (4) includes a high temperature side heat exchanger (54) in which a refrigerant evaporating temperature is set higher than that of the cooling heat exchanger (64a). ) And a high temperature side compressor (14b) that sucks the refrigerant evaporated in the high temperature side heat exchanger (54), and the cooling heat exchanger (64a) and the high temperature side heat exchanger (54) Both the first cooling operation that operates as an evaporator and the second cooling operation in which only the cooling heat exchanger (64a) operates as an evaporator are performed as one of the cooling operations, respectively, while the injection passage ( 30) is connected not only to the intermediate pressure compression chamber (73) of the cooling compressor (14a) but also to the intermediate pressure compression chamber (73) of the high temperature side compressor (14b). 110), in the first cooling operation, the temperature of the refrigerant cooled by the cooling means (100) The first intermediate pressure adjusting operation for controlling the intermediate pressure value of the injection passage (30) so as to be higher than the quasi-value and the first operation are performed. In the second cooling operation, the cooling means (100 ), The second intermediate pressure adjusting operation for controlling the intermediate pressure value of the injection passage (30) so that the temperature of the refrigerant cooled below the reference value is performed, and the second operation is performed.

  In the fifth invention, the first cooling operation in which both the cooling heat exchanger (64a) and the high temperature side heat exchanger (54) operate as an evaporator, and the cooling heat exchanger (64a) only operates as an evaporator. 2 Cooling operation is performed. Here, in the first cooling operation, the evaporation temperature (evaporation pressure) is higher than that of the cooling compressor (14a) that sucks the refrigerant evaporated in the cooling heat exchanger (64a) having the lower evaporation temperature (evaporation pressure). In the high temperature side compressor (14b) that sucks the refrigerant evaporated in the higher high temperature side heat exchanger (54), the internal pressure of the intermediate pressure compression chamber (73) facing the intermediate port becomes higher. For this reason, in order to inject an intermediate pressure refrigerant into both the cooling compressor (14a) and the high temperature side compressor (14b) through the injection passage (30), the intermediate pressure value in the injection passage (30) It is necessary to adjust the intermediate pressure of the high temperature side compressor (14b) to a value higher than the internal pressure of the compression chamber (73). Therefore, in the first cooling operation, the value of the intermediate pressure in the injection passage (30) is adjusted to a certain high value by the first intermediate pressure adjusting operation, and the temperature of the cooled refrigerant becomes higher than the reference value.

  On the other hand, in the second cooling operation, since the high temperature side heat exchanger (54) does not operate as an evaporator, the intermediate pressure value of the injection passage (30) is the compression chamber (the intermediate pressure compression chamber (14b) ( 73) The internal pressure is not limited. Therefore, in the second cooling operation, the value of the intermediate pressure in the injection passage (30) is adjusted to a certain low value by the second intermediate pressure adjusting operation, and the temperature of the cooled refrigerant becomes below the reference value. In the second cooling operation, the second operation for raising the refrigerant evaporation temperature in the cooling heat exchanger (64a) higher than that in the first operation as the temperature of the cooled refrigerant becomes lower than the reference value. Done. In the fifth invention, in the second cooling operation in which the high temperature side heat exchanger (54) is not an evaporator, the value of the intermediate pressure in the injection passage (30) is the high temperature side compressor as in the first cooling operation. Since the internal pressure of the intermediate pressure compression chamber (73) of (14b) is not restricted, reducing the intermediate pressure value of the injection passage (30) reduces the energy consumption of the cooling compressor (14a). A second operation is performed.

  According to a sixth invention, in any one of the first to fifth inventions, when the control means (110) has a cooling load in the cooling heat exchanger (64a, 64b) equal to or higher than a predetermined reference load. Even if the temperature of the refrigerant cooled by the cooling means (100) is equal to or lower than the reference value, the evaporation temperature of the refrigerant in the cooling heat exchanger (64a, 64b) is set without performing the second operation. Set to the first target value.

  In the sixth aspect of the invention, when the cooling load in the cooling heat exchanger (64a, 64b) is equal to or higher than the reference load, the control means (110) is configured so that the control means (110) (2) Without performing the operation, the refrigerant evaporation temperature in the cooling heat exchanger (64a, 64b) is set to the first target value. If the temperature of the cooled refrigerant is set to the first target value below the reference value, the flow rate of the refrigerant passing through the cooling heat exchangers (64a, 64b) is increased compared to the case where the second operation is performed. Only the cooling capacity in the cooling heat exchanger (64a, 64b) becomes high. On the other hand, when the cooling load in the cooling heat exchanger (64a, 64b) is lower than the reference load, the energy consumption of the cooling compressor (14a, 86) is low when the temperature of the cooled refrigerant is below the reference value. A second operation is performed. In the sixth aspect of the invention, when the temperature of the refrigerant after cooling is equal to or lower than the reference value, the cooling capacity in the cooling heat exchanger (64a, 64b) according to the cooling load in the cooling heat exchanger (64a, 64b). The operation in which the energy consumption is higher and the operation in which the energy consumption of the cooling compressor (14a, 86) is reduced are selectively used.

  In a seventh aspect based on any one of the first to sixth aspects, the control means (110) is configured so that the pressure of the refrigerant sucked into the cooling compressor (14a, 86) is equal to the target value. The operating capacity of the cooling compressor (14a, 86) is controlled so as to reach the saturation pressure of the refrigerant.

  In the seventh invention, in the first operation, the cooling compressor (14a, 86) is set so that the suction refrigerant pressure of the cooling compressor (14a, 86) becomes the refrigerant saturation pressure at the first target value. The operating capacity is controlled. In the second operation, the operating capacity of the cooling compressor (14a, 86) is controlled such that the pressure of the refrigerant sucked by the cooling compressor (14a, 86) becomes the saturation pressure of the refrigerant at the second target value. The In the seventh aspect of the invention, the cooling temperature is changed based on the pressure of the refrigerant sucked by the cooling compressor (14a, 86) so that the evaporation temperature of the refrigerant in the cooling heat exchanger (64a, 64b) becomes a predetermined target value. The operating capacity of the compressor (14a, 86) is controlled.

  In the present invention, when the temperature of the refrigerant flowing into the cooling heat exchanger (64a, 64b) is lowered to some extent, the flow rate of the refrigerant passing through the cooling heat exchanger (64a, 64b) can be reduced to some extent. In order to reduce the energy consumption of the cooling compressor (14a, 86), the target value of the refrigerant evaporation temperature in the cooling heat exchanger (64a, 64b) is changed to a high value. Yes. Therefore, compared with the case where the target value of the refrigerant evaporating temperature in the cooling heat exchanger (64a, 64b) is constant even when the temperature of the refrigerant flowing into the cooling heat exchanger (64a, 64b) changes, the refrigeration apparatus The driving efficiency of (1) can be improved.

  In the second aspect of the invention, when the temperature of the refrigerant flowing into the low temperature side heat exchanger (64b) becomes low to some extent, the flow rate of the refrigerant passing through the low temperature side heat exchanger (64b) is reduced to some extent. Focusing on the fact that the energy can be consumed by the low-stage compressor (86), the target value of the refrigerant evaporation temperature in the low-temperature side heat exchanger (64b) is changed to a high value. Therefore, compared with the case where the target value of the evaporating temperature of the refrigerant in the low temperature side heat exchanger (64b) is constant even if the temperature of the refrigerant flowing into the low temperature side heat exchanger (64b) changes, the refrigeration apparatus (1 ) Driving efficiency can be improved.

  In the fourth aspect of the invention, since the degree of supercooling of the refrigerant after cooling can be made relatively large in the second operation, the unit flow rate of the refrigerant flowing into the cooling heat exchanger (64a, 64b) It is possible to increase the cooling capacity relatively large. For this reason, the cooling capacity of the cooling heat exchanger (64a, 64b) is large even if the flow rate of the refrigerant passing through the cooling heat exchanger (64a, 64b) during the second operation is greatly reduced compared to that during the first operation. The difference between the first target value and the second target value can be made relatively large without decreasing. Therefore, since the energy consumption of the cooling compressor (14a) during the second operation can be reduced relatively greatly, the operating efficiency of the refrigeration apparatus (1) can be further improved.

  In the fifth aspect of the invention, in the second cooling operation, the intermediate pressure value in the injection passage (30) is the compression chamber (73) of the intermediate pressure of the high temperature side compressor (14b) as in the first cooling operation. ), The second operation of reducing the energy consumption of the cooling compressor (14a) is performed by reducing the value of the intermediate pressure in the injection passage (30). In the first cooling operation in which the temperature of the cooled refrigerant cannot be lower than the reference value due to the restriction of the internal pressure of the intermediate pressure compression chamber (73) of the high temperature side compressor (14b), the second operation is not performed and the cooling is performed. The second operation is appropriately selected in the second cooling operation in which the temperature of the subsequent refrigerant can be made equal to or lower than the reference value. Therefore, for example, the operating efficiency of the refrigeration apparatus (1) can be improved without causing a problem with respect to the injection operation for injecting the refrigerant into the compression chamber (73) of the intermediate pressure of the compressor (14).

  In the sixth aspect of the invention, when the temperature of the cooled refrigerant is equal to or lower than the reference value, the cooling heat exchanger (64a, 64b) has a cooling load according to the cooling load in the cooling heat exchanger (64a, 64b). The operation in which the cooling capacity is increased and the operation in which the energy consumption of the cooling compressor (14a, 86) is reduced are selectively used. For this reason, although the cooling load in the cooling heat exchanger (64a, 64b) has increased to some extent, the second operation is performed with priority given to reducing the energy consumption of the cooling compressor (14a, 86). It is not performed, and it can avoid leaving the temperature of the object space which a cooling heat exchanger (64a, 64b) cools from desired temperature.

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

  This embodiment is a refrigeration apparatus (1) according to the present invention. The refrigeration apparatus (1) is provided in a convenience store, for example. As shown in FIG. 1, the refrigeration apparatus (1) includes an outdoor unit (10) installed outside the room, an indoor unit (50) that air-conditions the store space, and two internal units ( 60a, 60b) and a booster unit (80). The two internal units (60a, 60b) are composed of a first internal unit (60a) for refrigeration and a second internal unit (60b) for freezing.

  The outdoor unit (10) has an outdoor circuit (11), the indoor unit (50) has an indoor circuit (52), the first internal unit (60a) has a first internal circuit (61a), The internal unit (60b) is provided with a second internal circuit (61b), and the booster unit (80) is provided with a booster circuit (81). In this refrigeration system (1), an outdoor circuit (11), an indoor circuit (52), a first internal circuit (61a), a second internal circuit (61b), and a booster circuit (81) are connected to four connecting pipes. By connecting with (2a, 2b, 3a, 3b), a refrigerant circuit (4) for performing a vapor compression refrigeration cycle is configured. The first internal circuit (61a) and the second internal circuit (61b) are connected in parallel. The second internal circuit (61b) and the booster circuit (81) are connected in series.

  The four connecting pipes (2a, 2b, 3a, 3b) are the first liquid side connecting pipe (2a), the second liquid side connecting pipe (2b), the first gas side connecting pipe (3a), and the second gas. Consists of side connecting piping (3b). One end of the first liquid side communication pipe (2a) is connected to the first liquid side shut-off valve (111) of the outdoor circuit (11), and the other end is connected to the indoor circuit (52). One end of the second liquid side communication pipe (2b) is connected to the second liquid side shut-off valve (112) of the outdoor circuit (11), and the other end branches into two hands to connect with the first internal circuit (61a). It is connected to the second internal circuit (61b). The first gas side communication pipe (3a) has one end connected to the first gas side closing valve (113) of the outdoor circuit (11) and the other end connected to the indoor circuit (52). One end of the second gas side communication pipe (3b) is connected to the second gas side shut-off valve (114) of the outdoor circuit (11), and the other end branches into two hands to connect with the first internal circuit (61a). It is connected to the second internal circuit (61b). The second internal circuit (61b) and the booster circuit (81) are connected by a connection gas pipe (5).

  In the present embodiment, the first passage is configured from the branch point of the second liquid side connecting pipe (2b) to the branch point of the second gas side connecting pipe (3b) via the first internal circuit (61a). is doing. Moreover, the 2nd passage is comprised from the branch location of the 2nd liquid side connection piping (2b) to the branch location of the 2nd gas side connection piping (3b) through the 2nd internal circuit (61b). The first passage and the second passage are parallel to each other.

《Outdoor unit》
The outdoor circuit (11) is provided with a compression mechanism (40), an outdoor heat exchanger (15), and a receiver (gas-liquid separator) (85). The compression mechanism (40) includes a first compressor (14a) having a variable operating capacity, a second compressor (14b) having a fixed operating capacity, and a third compressor (14c) having a fixed operating capacity. Has been. In the compression mechanism (40), the discharge sides of these compressors (14a, 14b, 14c) are connected to each other. Further, these compressors (14a, 14b, 14c) are connected to a third four-way switching valve (33) described later on the suction side.

  Electric power is supplied to the first compressor (14a) via an inverter. The first compressor (14a) is configured such that its operating capacity can be adjusted in stages by changing the output frequency of the inverter. On the other hand, in the second compressor (14b) and the third compressor (14c), the electric motor is always operated at a constant rotational speed, and the operation capacity cannot be changed. The second compressor (14b) and the third compressor (14c) may be compressors with variable operating capacity.

  The first compressor (14a) is an in-compartment compressor that sucks the refrigerant evaporated in the in-compartment units (60a, 60b). The first compressor (14a) is a compressor dedicated to the interior. The second compressor (14b) is an indoor compressor that sucks the refrigerant evaporated in the indoor unit (50) during the cooling operation. The second compressor (14b) is an indoor dedicated compressor. The third compressor (14c) serves as an in-compartment compressor when a third four-way switching valve (33) described later is in the first state, and the third four-way switching valve (33) is the second compressor. Becomes an indoor compressor when in a state. That is, the third compressor (14c) is used both as an internal compressor and an indoor compressor. In the present embodiment, the internal compressors (14a, 14c) constitute a cooling compressor, and the indoor compressors (14b, 14c) constitute a high-temperature side compressor.

  The first compressor (14a), the second compressor (14b), and the third compressor (14c) are the same type of compressor. Each compressor (14) is configured as, for example, a hermetic high-pressure dome type scroll compressor. Each compressor (14) includes a scroll type fluid machine (82) as shown in FIG.

  In this fluid machine (82), a plurality of compression chambers (73) are formed between a fixed scroll wrap (75) and a movable scroll wrap (76). In the fluid machine (82), the refrigerant sucked from the suction port (98) communicating with the suction pipe (57) is compressed, and the compressed refrigerant is discharged from the discharge port (93) communicating with the discharge pipe (56). The Further, the fluid machine (82) is formed with an intermediate port (99) communicating with branch injection pipes (30a, 30b, 30c) described later. The intermediate port (99) opens to an intermediate pressure compression chamber (73) in which refrigerant in the compression stroke exists. Moreover, although not shown in figure, refrigeration oil is stored in the bottom part of the casing of each compressor (14). The refrigerating machine oil is supplied to a sliding portion such as a fluid machine (82), and a part thereof is discharged from the discharge pipe (56) together with the refrigerant.

  In the refrigeration apparatus (1), the temperature of the refrigerant evaporated in the internal units (60a, 60b) is lower than the temperature of the refrigerant evaporated in the indoor unit (50). For this reason, the one where evaporation temperature (evaporation pressure) is higher than the internal compressor (14a, 14c) which sucks the refrigerant evaporated in the internal unit (60a, 60b) with lower evaporation temperature (evaporation pressure) The internal compressor (14b, 14c), which sucks the refrigerant evaporated in the indoor unit (50), has a higher internal pressure in the compression chamber (73) having an intermediate pressure facing the intermediate port (99).

  The first discharge pipe (56a) of the first compressor (14a), the second discharge pipe (56b) of the second compressor (14b), and the third discharge pipe (56c) of the third compressor (14c) are 1 It is connected to the discharge junction pipe (21). The discharge junction pipe (21) is connected to the first four-way switching valve (31). A discharge branch pipe (22) branches off from the discharge junction pipe (21). The discharge branch pipe (22) is connected to the second four-way switching valve (32).

  Each discharge pipe (56) has an oil separator (37a, 37b, 37c), high pressure switch (39a, 39b, 39c) and check valve (CV1, CV2, CV3) in order from the compressor (14) side. And are arranged. Each high pressure switch (39) is configured to urgently stop the compressor (14) when the pressure is abnormally high. Each check valve (CV1, CV2, CV3) is configured to prohibit the flow of refrigerant toward the compressor (14).

  Each oil separator (37) is configured in a closed container shape, and is configured to separate the refrigeration oil from the refrigerant discharged from the compressor (14). In this embodiment, each discharge pipe (56) is provided with an oil separator (37), but each discharge pipe (56) is not provided with an oil separator (37), and the discharge junction pipe (21). An oil separator (37) may be provided.

  A first oil return branch pipe (42) is connected to the first oil separator (37a) of the first discharge pipe (56a), and a second oil separator (37b) of the second discharge pipe (56b) is connected to the first oil separator (37b). A second oil return branch pipe (43) is connected, and a third oil return branch pipe (44) is connected to the third oil separator (37c) of the third discharge pipe (56c). The first oil return branch pipe (42), the second oil return branch pipe (43), and the third oil return branch pipe (44) have a main injection pipe (30d), which will be described later, on the side opposite to the oil separator (37). Is connected to an oil return junction pipe (45) connected to

  Each oil return branch pipe (42, 43, 44) has a check valve (CV12, CV13, which prohibits the flow of refrigeration oil returning to the oil separator (37) in order from the oil separator (37) side. CV14) and capillary tubes (41a, 41b, 41c) for reducing the high pressure refrigerating machine oil to an intermediate pressure. The refrigerating machine oil separated in each oil separator (37) returns to the compression chamber (73) of the intermediate pressure of the compressor (14) through each oil return branch pipe (42, 43, 44) and the like.

  The first suction pipe (57a) of the first compressor (14a) is connected to the second gas side shut-off valve (114). The second suction pipe (57b) of the second compressor (14b) is connected to the second four-way switching valve (32). The third suction pipe (57c) of the third compressor (14c) is connected to the third four-way switching valve (33). A first suction branch pipe (58a) branches off from the first suction pipe (57a). A second suction branch pipe (58b) branches off from the second suction pipe (57b). Both the first suction branch pipe (58a) and the second suction branch pipe (58b) are connected to the third four-way switching valve (33). The first suction branch pipe (58a) and the second suction branch pipe (58b) have check valves (CV7, CV8) for prohibiting the flow of refrigerant from the third four-way switching valve (33) side, respectively. Is provided.

  The outdoor heat exchanger (15) is a cross-fin type fin-and-tube heat exchanger. The outdoor heat exchanger (15) constitutes a heat source side heat exchanger. An outdoor fan (23) that sends outdoor air to the outdoor heat exchanger (15) is provided in the vicinity of the outdoor heat exchanger (15). In the outdoor heat exchanger (15), heat is exchanged between the refrigerant and the outdoor air.

  The gas side of the outdoor heat exchanger (15) is connected to the first four-way switching valve (31). The liquid side of the outdoor heat exchanger (15) is connected to the top of the receiver (85) via the first liquid pipe (24). The first liquid pipe (24) is provided with a check valve (CV9) that prohibits the flow of refrigerant toward the outdoor heat exchanger (15).

  The receiver (85) is configured in a vertically long sealed container shape. In the receiver (85), the high-pressure refrigerant condensed in the outdoor heat exchanger (15) or the like is temporarily stored. In addition to the first liquid pipe (24), a gas vent pipe (48) provided with an openable / closable fourth electromagnetic valve (SV4) is connected to the top of the receiver (85). One end of the second liquid pipe (25) is connected to the bottom of the receiver (85). The other end of the second liquid pipe (25) branches into a first branch pipe (26) and a second branch pipe (27).

  The first branch pipe (26) is connected to the first liquid side stop valve (111). The first branch pipe (26) communicates with the indoor circuit (52) via the first liquid side communication pipe (2a). The first branch pipe (26) is provided with a check valve (CV10) that prohibits the flow of refrigerant toward the second liquid pipe (25). A third branch pipe (28) connected between the check valve (CV9) and the receiver (85) in the first liquid pipe (24) branches from the first branch pipe (26). The third branch pipe (28) is provided with a check valve (CV11) that prohibits the flow of the refrigerant toward the first branch pipe (26).

  The second branch pipe (27) is connected to the second liquid side stop valve (112). The second branch pipe (27) communicates with the internal circuits (61a, 61b) via the second liquid side connecting pipe (2b). A second intermediate heat exchanger (17), which will be described later, is connected to the second branch pipe (27). From the second branch pipe (27), the fourth branch pipe (29) and the injection pipe (30) branch off.

  The fourth branch pipe (29) branches from between the second intermediate heat exchanger (17) and the second liquid side shut-off valve (112). The fourth branch pipe (29) is connected to the second branch pipe (27) at the opposite end of the outdoor heat exchanger (15) and the check valve (CV9) in the first liquid pipe (24). Connected between. The fourth branch pipe (29) is provided with a first outdoor expansion valve (66) constituted by an electronic expansion valve having a variable opening.

  The injection pipe (30) branches from between the branch point of the fourth branch pipe (29) and the second liquid side shut-off valve (112). The injection pipe (30) constitutes an injection passage. The injection pipe (30) includes a main injection pipe (30d) extending from the second branch pipe (27), and a compression chamber (73) of the intermediate pressure of the first compressor (14a) branched from the main injection pipe (30d). A first branch injection pipe (30a) connected to the main injection pipe (30d) and a second branch injection pipe (2) connected to the intermediate pressure compression chamber (73) of the second compressor (14b) 30b) and a third branch injection pipe (30c) branched from the main injection pipe (30d) and connected to the intermediate pressure compression chamber (73) of the third compressor (14c).

  The main injection pipe (30d) is provided with a second outdoor expansion valve (67) constituting decompression means. The second outdoor expansion valve (67) is an electronic expansion valve having a variable opening. In the second outdoor expansion valve (67), the refrigerant flowing from the second branch pipe (27) into the main injection pipe (30d) is reduced to an intermediate pressure in the refrigeration cycle. In the main injection pipe (30d), a gas vent pipe (48) is connected to a position downstream of a second intermediate heat exchanger (17) described later.

  Each branch injection pipe (30a, 30b, 30c) has a check valve (CV4, CV5, CV6), solenoid valve (SV1, SV2, SV3) in order from the compressor (14a, 14b, 14c) side. Is provided. The check valves (CV4, CV5, CV6) prohibit the flow of refrigerant from the compressor (14a, 14b, 14c) side. The solenoid valve (SV1, SV2, SV3) has a compressor (14a, 14b, 14c) connected to the branch injection pipe (30a, 30b, 30c) where the solenoid valve (SV1, SV2, SV3) is connected. Closed when stopped.

  In this embodiment, the first intermediate heat exchanger (16) for cooling the refrigerant supplied to both the indoor heat exchanger (54) and the internal heat exchanger (64), and the indoor heat exchanger (54 ) And a second intermediate heat exchanger (17) for cooling the refrigerant supplied only to the internal heat exchanger (64) among the internal heat exchanger (64). The first intermediate heat exchanger (16) and the second intermediate heat exchanger (17) include a cooling means (100) for cooling the refrigerant supplied to the internal heat exchanger (64) together with the injection pipe (30). ).

  The first intermediate heat exchanger (16) is configured to exchange heat between the refrigerant flowing through the first flow path (16a) and the refrigerant flowing through the second flow path (16b). The first intermediate heat exchanger (16) is constituted by, for example, a double tube heat exchanger. In the first intermediate heat exchanger (16), the first flow path (16a) is connected to the second liquid pipe (25), and the second flow path (16b) formed inside the first flow path (16a). Is connected downstream of the second outdoor expansion valve (67) in the main injection pipe (30d). In the heat exchange in the first intermediate heat exchanger (16), the high-pressure refrigerant in the second liquid pipe (25) is cooled by the intermediate-pressure refrigerant in the main injection pipe (30d).

  The second intermediate heat exchanger (17) is configured to exchange heat between the refrigerant flowing through the first flow path (17a) and the refrigerant flowing through the second flow path (17b). The second intermediate heat exchanger (17) is constituted by, for example, a plate heat exchanger. In the second intermediate heat exchanger (17), the first flow path (17a) is connected to the second branch pipe (27), and the second flow path (17b) is the first intermediate heat exchange in the main injection pipe (30d). Connected downstream of the vessel (16). In the heat exchange in the second intermediate heat exchanger (17), the high-pressure refrigerant in the second branch pipe (27) is cooled by the intermediate-pressure refrigerant in the main injection pipe (30d).

  The first four-way switching valve (31) has a first port (P1) connected to the discharge junction pipe (21) and a second port (P2) connected to the fourth port (P4) of the second four-way switching valve (32). The third port (P3) is connected to the outdoor heat exchanger (15), and the fourth port (P4) is connected to the first gas side shut-off valve (113). The second four-way selector valve (32) has a first port (P1) connected to the discharge branch pipe (22), a second port (P2) connected to the second suction pipe (57b), and a fourth port (P4). Are connected to the second port (P2) of the first four-way selector valve (31), respectively. The third port (P3) of the second four-way selector valve (32) is configured as a closed port. The third four-way selector valve (33) has a first port (P1) connected to the discharge junction pipe (21) and a second port (P2) connected to the third suction pipe (57c). ), The third port (P3) is connected to the second suction branch pipe (58b), and the fourth port (P4) is connected to the first suction branch pipe (58a).

  In each of the first to third four-way selector valves (31, 32, 33), the first port (P1) and the third port (P3) communicate with each other to connect the second port (P2) and the fourth port (P4). ) Communicate with each other (the state indicated by the solid line in FIG. 1), the first port (P1) and the fourth port (P4) communicate with each other, the second port (P2) and the third port (P3) Are configured to be switchable between a second state (a state indicated by a broken line in FIG. 1) in communication with each other.

  The outdoor unit (10) is provided with various sensors. Specifically, the discharge junction pipe (21) is provided with a discharge pressure sensor (18). Each discharge pipe (56) is provided with a discharge temperature sensor (48a, 48b, 48c). The first suction pipe (57a) is provided with a first suction pressure sensor (19a) and a first suction temperature sensor (20a). The second suction pipe (57b) is provided with a second suction pressure sensor (19b) and a second suction temperature sensor (20b). The second branch pipe (27) is provided with a liquid temperature sensor (72). The detection values of these sensors are input to a controller (110) described later.

《Indoor unit》
In the indoor circuit (52), an indoor expansion valve (53) and an indoor heat exchanger (54) are provided in order from the liquid side end to the gas side end. The indoor expansion valve (53) is an electronic expansion valve whose opening degree can be adjusted. The indoor heat exchanger (54) is a cross-fin fin-and-tube heat exchanger. The indoor heat exchanger (54) constitutes a high-temperature side heat exchanger in which the evaporation temperature of the refrigerant is set to a value higher than that of the internal heat exchanger (64). An indoor fan (55) that sends indoor air to the indoor heat exchanger (54) is provided in the vicinity of the indoor heat exchanger (54). In the indoor heat exchanger (54), heat is exchanged between the refrigerant and the room air.

  In the indoor circuit (52), an evaporation temperature sensor (121) is provided in the heat transfer tube of the indoor heat exchanger (54). A gas temperature sensor (123) is provided at the gas side end of the indoor circuit (52). A room temperature sensor (125) for measuring the indoor temperature is provided between the inlet of the indoor unit (50) and the indoor heat exchanger (54). The measured values of these sensors are input to a controller (110) described later.

  In the indoor unit (50), an ice melting operation for melting frost attached to the indoor heat exchanger (54) is performed only when a predetermined condition is satisfied. The predetermined condition is, for example, a condition that the detected value of the evaporation temperature sensor (121) is below a predetermined value (for example, 0 ° C.). In the ice melting operation, the indoor expansion valve (53) is set to the closed state, and the operation of the indoor fan (55) is continued. In this indoor unit (50), the indoor expansion valve (53) is controlled so that frost does not adhere to the indoor heat exchanger (54), but frost has adhered to the indoor heat exchanger (54). In some cases, an ice melting operation is performed as an emergency operation.

<Inside unit>
In the first internal circuit (61a) and the second internal circuit (61b), the internal expansion valve (63a, 63b) and the internal heat exchanger (64a, 64b) are provided. Each internal expansion valve (63a, 63b) is configured by an electronic expansion valve whose opening degree is adjustable.

  Each of the internal heat exchangers (64a, 64b) is configured by a cross fin type fin-and-tube heat exchanger. The internal heat exchanger (64a) of the first internal circuit (61a) constitutes a cooling heat exchanger for cooling the internal space that is the target space. Further, the internal heat exchanger (64b) of the second internal circuit (61b) constitutes a low temperature side heat exchanger in which the evaporation temperature of the refrigerant is set to a lower value than the cooling heat exchanger (64a). Yes. In the vicinity of the internal heat exchangers (64a, 64b), internal fans (65a, 65b) for supplying internal air to the internal heat exchangers (64a, 64b) are provided. In each internal heat exchanger (64a, 64b), heat is exchanged between the refrigerant and the internal air.

  In each internal circuit (61a, 61b), an evaporation temperature sensor (122a, 122b) is provided in the heat transfer tube of the internal heat exchanger (64a, 64b). Gas temperature sensors (124a, 124b) are provided at gas side ends of the internal circuit (61a, 61b). A storage temperature sensor (126) for measuring the temperature in the storage is provided between the suction port of the storage unit (60) and the heat exchanger (64) in the storage. The measured values of these sensors are input to a controller (110) described later.

  In the first internal unit (60a) and the second internal unit (60b), an ice melting operation for melting frost attached to the internal heat exchanger (64) is performed periodically (for example, every 3 hours). To be done. In the ice melting operation, the internal expansion valve (63) is set to the closed state, and the operation of the internal fan (65) is continued. In addition, you may use heating means, such as an electric heater, for the heating of the ice adhering to the internal heat exchanger (64). In the first internal unit (60a) and the second internal unit (60b), since the refrigerant evaporating temperature is low, frost adheres to the internal heat exchanger (64) during operation. For this reason, the ice melting operation is periodically performed.

《Booster unit》
The booster circuit (81) is provided with a booster compressor (86) having a variable operation capacity. The booster compressor (86) constitutes a low-stage compressor that compresses the refrigerant evaporated in the low-temperature heat exchanger (64b). The discharge pipe (78) of the booster compressor (86) is provided with an oil separator (87), a high pressure switch (88), and a check valve (CV15) in order from the booster compressor (86) side. . An oil return pipe (92) provided with a capillary tube (91) is connected to the oil separator (87). The booster circuit (81) is provided with a bypass pipe (95) that bypasses the booster compressor (86). The bypass pipe (95) is provided with a check valve (CV16).

  In the booster circuit (81), a discharge temperature sensor (96) is provided in the discharge pipe (78) of the booster compressor (86). A suction pressure sensor (97) is provided in the suction pipe (79) of the booster compressor (86). The detection values of these sensors are input to a controller (110) described later.

"controller"
The outdoor unit (10) has a controller (110) that controls the operation of the refrigerant circuit (4) by controlling the operating capacity of the compression mechanism (40), the four-way switching valve (31 to 33), etc. It is provided as a means.

  First, superheat degree control which controls the superheat degree of the refrigerant | coolant which passed by the utilization side heat exchanger (54,64) is demonstrated. The controller (110) controls the opening degree of the indoor expansion valve (53) so that the superheat degree of the refrigerant that has passed through the indoor heat exchanger (54) during the cooling operation becomes a target superheat degree (for example, 5 ° C.). Further, the controller (110) opens the opening of the internal expansion valve (63a, 63b) so that the superheat degree of the refrigerant that has passed through the internal heat exchanger (64, 64b) becomes the target superheat degree (for example, 5 ° C). To control.

  Next, the control of the injection operation for injecting the intermediate pressure refrigerant through the injection pipe (30) into the intermediate pressure compression chamber (73) of each compressor (14) of the compression mechanism (40) will be described.

  The controller (110) is configured to switch between a first intermediate pressure adjustment operation and a second intermediate pressure adjustment operation as a control operation of the injection operation. The first intermediate pressure adjustment operation is performed during a first cooling operation (during cooling cooling operation described later) in which both the internal heat exchanger (64) and the indoor heat exchanger (54) operate as an evaporator, and cooling described later. It is performed at the time of operation and at the time of the third cooling and heating operation described later. The second intermediate pressure adjustment operation is performed during a second cooling operation in which only the internal heat exchanger (64) operates as an evaporator (in a refrigeration operation and a first and second cooling and heating operation described later).

  In the first intermediate pressure adjustment operation, the temperature of the refrigerant that has passed through the second intermediate heat exchanger (17), that is, the temperature of the refrigerant cooled by the cooling means (100) is higher than a predetermined reference value. The intermediate pressure value of (30) is controlled. In the controller (110), a first liquid temperature target value (for example, 20 ° C.) that is larger than the reference value is set in advance as a target value for the temperature of the refrigerant that has passed through the second intermediate heat exchanger (17). Yes. The controller (110) during the first intermediate pressure adjustment operation controls the opening degree of the second outdoor expansion valve (67) so that the measured value of the liquid temperature sensor (72) becomes the first liquid temperature target value.

  The first liquid temperature target value is only a predetermined value higher than the internal pressure of the compression chamber (73) of the intermediate pressure of the indoor compressor (14b, 14c) when the intermediate pressure value of the injection pipe (30) is in the cooling operation. It is determined to be a higher value. The first liquid temperature target value is determined in this way when the intermediate pressure value of the injection pipe (30) is less than the internal pressure of the compression chamber (73) of the intermediate pressure of the indoor compressor (14b, 14c). The refrigerant from the injection pipe (30) does not flow into the intermediate pressure compression chamber (73) of the indoor compressor (14b, 14c) and the refrigerating machine oil separated by the oil separator (37) This is because it will not return to (14b, 14c).

  In the second intermediate pressure adjustment operation, the value of the intermediate pressure in the injection passage (30) is controlled so that the temperature of the refrigerant cooled by the cooling means (100) is equal to or lower than the reference value. In the controller (110), a second liquid temperature target value (for example, 5 ° C.) that is smaller than the reference value is set in advance as the target value of the temperature of the refrigerant that has passed through the second intermediate heat exchanger (17). Yes. The controller (110) during the second intermediate pressure adjustment operation controls the opening degree of the second outdoor expansion valve (67) so that the measured value of the liquid temperature sensor (72) becomes the second liquid temperature target value. During the second intermediate pressure adjustment operation, the second outdoor expansion valve (67) is set so that the temperature and pressure of the refrigerant after passing through the second outdoor expansion valve (67) are lower than those during the first intermediate pressure adjustment operation. Is controlled.

  The second liquid temperature target value is a value at which the intermediate pressure value of the injection pipe (30) is higher than the internal pressure of the intermediate pressure compression chamber (73) of the internal compressor (14a, 14c) by a predetermined value. It has been decided. The second liquid temperature target value is determined in this way because the intermediate pressure value of the injection pipe (30) is less than the internal pressure of the compression chamber (73) of the intermediate pressure of the internal compressor (14a, 14c). Then, the refrigerant from the injection pipe (30) does not flow into the intermediate pressure compression chamber (73) of the internal compressor (14a, 14c) and the refrigeration oil separated by the oil separator (37) This is because the compressor (14a, 14c) cannot be returned to. Note that the second liquid temperature target value is such that if the indoor compressor (14b, 14c) is in operation, the intermediate pressure value of the injection pipe (30) is equal to the intermediate pressure of the indoor compressor (14b, 14c). The value is less than the internal pressure of the compression chamber (73).

  Next, control of the operating capacity of the internal compressor (14a, 14c) will be described. In addition, the controller (110) is used only for the first compressor (14a) when the internal load, which is the sum of the cooling loads in the internal heat exchangers (64a, 64b) on the refrigerator side and the freezer side, is relatively small. The operating capacity of the first compressor (14a) is controlled by using the compressor for the interior. When the internal load exceeds the maximum operating capacity of the first compressor (14a), the controller (110) compresses the internal compressor if the third compressor (14c) is an indoor compressor. If the third compressor (14c) is stopped, the third compressor (14c) is started to compress the first compressor (14a) and the third compressor (14c) for internal storage. The operating capacity of the first compressor (14a) is controlled as a machine.

  The controller (110) includes a first target value (for example, −10 ° C.) and a second target value (for example, −8 ° C.) as target values for the refrigerant evaporation temperature in the refrigerator side heat exchanger (64a). Is preset. The second target value is higher than the first target value.

  During the first intermediate pressure adjustment operation, the controller (110) operates the operating capacity of the first compressor (14a) so that the evaporating temperature of the refrigerant in the refrigerator side heat exchanger (64a) becomes the first target value. It is comprised so that the 1st operation | movement which controls may be performed. That is, the controller (110) performs the first operation when the temperature of the refrigerant cooled by the cooling means (100) becomes higher than the reference value. The controller (110) in the first operation is configured so that the measured value of the first suction pressure sensor (19a) that measures the pressure of the suction refrigerant of the first compressor (14a) becomes the saturation pressure of the refrigerant at the first target value. In addition, the operating capacity of the first compressor (14a) is controlled.

  In addition, during the second intermediate pressure adjustment operation, the controller (110) controls the first compressor (14a) so that the evaporation temperature of the refrigerant in the refrigeration side internal heat exchanger (64a) becomes the second target value. The second operation for controlling the operation capacity is performed. That is, the controller (110) performs the second operation when the temperature of the refrigerant cooled by the cooling means (100) is equal to or lower than the reference value. The controller (110) in the second operation controls the operating capacity of the first compressor (14a) so that the measured value of the first suction pressure sensor (19a) becomes the saturation pressure of the refrigerant at the second target value. . In the second operation, the evaporating temperature of the refrigerant in the refrigerator side heat exchanger (64a) is higher than that in the first operation.

  Here, when the target value of the evaporating temperature of the refrigerant in the refrigeration-side internal heat exchanger (64a) increases, the flow rate of the refrigerant passing through the refrigeration-side internal heat exchanger (64a) is decreased. The operating capacity of the compressor (14a) is controlled. For this reason, the internal compressors (14a, 14c) require less energy for boosting the refrigerant. That is, the energy consumption of the internal compressor (14a, 14c) is reduced. Further, when the target value of the refrigerant evaporation temperature in the cooling heat exchanger (64a, 64b) increases, the pressure of the refrigerant sucked in the internal compressor (14a, 14c) increases, and the internal compressor (14a, 64b) 14c) Since the pressure difference between the suction refrigerant and the discharge refrigerant becomes small, the target value of the refrigerant evaporation temperature in the refrigeration side internal heat exchanger (64a) does not change, and the refrigeration side internal heat exchanger is simply changed. Compared with the case where the flow rate of the refrigerant passing through (64a) decreases, the energy consumption of the compressors for storage (14a, 14c) is reduced. Thus, in the second operation, the flow rate of the refrigerant sucked into the internal compressor (14a, 14c) decreases, and the pressure difference between the intake refrigerant and the discharge refrigerant of the internal compressor (14a, 14c). The energy consumption of the in-compartment compressors (14a, 14c) is reduced by reducing.

  Moreover, in the refrigerator internal heat exchanger (64a), the lower the temperature of the refrigerant flowing in, the larger the enthalpy difference between the refrigerant at the inlet and the outlet, so that the refrigerant cooling capacity per unit flow rate becomes higher. For this reason, when the temperature of the refrigerant flowing into the refrigeration side internal heat exchanger (64a) is lowered to some extent, the flow rate of the refrigerant passing through the refrigeration side internal heat exchanger (64a) is reduced. However, the cooling capacity in the refrigerator internal heat exchanger (64a) does not change so much. In the present embodiment, when the temperature of the refrigerant flowing into the refrigeration side internal heat exchanger (64a) is lowered to some extent, the flow rate of the refrigerant passing through the refrigeration side internal heat exchanger (64a) is limited to some extent. Focusing on the fact that it can be reduced, the target value of the refrigerant evaporation temperature in the refrigerator internal heat exchanger (64a) is high so that the energy consumption of the internal compressor (14a, 14c) is reduced Changed to a value.

  Next, control of the operating capacity of the booster compressor (86) will be described.

  The controller (110) includes a third target value (for example, −40 ° C.) and a fourth target value (for example, −38 ° C.) as target values for the refrigerant evaporation temperature in the refrigeration side internal heat exchanger (64b). Is preset. The fourth target value is higher than the third target value.

  During execution of the first operation, the controller (110) controls the operating capacity of the booster compressor (86) so that the refrigerant evaporation temperature in the refrigeration side internal heat exchanger (64b) becomes the third target value. Is configured to do. That is, when the temperature of the refrigerant cooled by the cooling means (100) becomes higher than the reference value, the controller (110) sets the evaporation temperature of the refrigerant in the refrigeration side internal heat exchanger (64b) to the third target. The operating capacity of the booster compressor (86) is controlled so as to be a value. The controller (110) during the first operation is configured so that the measured value of the suction pressure sensor (97) that measures the pressure of the suction refrigerant of the booster compressor (86) becomes the saturation pressure of the refrigerant at the third target value. Control the operating capacity of the compressor (86).

  In addition, the controller (110) operates the capacity of the booster compressor (86) so that the evaporation temperature of the refrigerant in the refrigeration side internal heat exchanger (64b) becomes the fourth target value during the execution of the second operation. Is configured to control. That is, when the temperature of the refrigerant cooled by the cooling means (100) becomes equal to or lower than the reference value, the controller (110) determines that the refrigerant evaporation temperature in the freezer side internal heat exchanger (64b) is the fourth target value. The operating capacity of the booster compressor (86) is controlled so that The controller (110) in the second operation controls the operating capacity of the booster compressor (86) so that the measured value of the suction pressure sensor (97) becomes the refrigerant saturation pressure at the fourth target value. During the second operation, the evaporation temperature of the refrigerant in the refrigeration-side internal heat exchanger (64b) is higher than that during the first operation.

  Here, the booster compression is also performed so that the flow rate of the refrigerant passing through the freezer side internal heat exchanger (64b) decreases when the target value of the refrigerant evaporation temperature increases in the freezer side internal heat exchanger (64b). The operating capacity of the machine (86) is controlled. For this reason, the energy consumption of the booster compressor (86) is reduced. In addition, when the target value of the refrigerant evaporation temperature in the refrigerator side heat exchanger (64b) increases, the pressure of the refrigerant sucked in the booster compressor (86) increases, and the refrigerant sucked in the booster compressor (86) Since the pressure difference of the discharged refrigerant is reduced, the refrigerant evaporating temperature target value in the freezer side internal heat exchanger (64b) simply passes through the freezer side internal heat exchanger (64b) without changing. The booster compressor (86) consumes less energy than when the refrigerant flow rate decreases.

  Further, in the refrigerator side internal heat exchanger (64b), the lower the temperature of the refrigerant flowing in, the larger the enthalpy difference between the refrigerant at the inlet and the outlet, so that the refrigerant cooling capacity per unit flow rate increases. For this reason, when the temperature of the refrigerant flowing into the freezer side internal heat exchanger (64b) is lowered to some extent, the flow rate of the refrigerant passing through the freezer side internal heat exchanger (64b) is reduced. However, the cooling capacity in the freezer side heat exchanger (64b) does not change so much. In the present embodiment, when the temperature of the refrigerant flowing into the low temperature side heat exchanger (64b) is lowered to some extent, the flow rate of the refrigerant passing through the freezer side internal heat exchanger (64b) is reduced to some extent. Focusing on the fact that the energy consumption of the booster compressor (86) is reduced, the target value of the refrigerant evaporating temperature in the refrigeration side internal heat exchanger (64b) is changed to a high value.

  However, even if the controller (110) is in the second intermediate pressure adjustment operation, if the internal load exceeds the predetermined reference load, the controller (110) does not perform the second operation and performs the internal heat exchange on the refrigerator side. The operating capacity of the first compressor (14a) is controlled so that the evaporation temperature of the refrigerant in the compressor (64a) becomes the first target value. In other words, when the internal load becomes equal to or higher than the reference load, even if the temperature of the refrigerant cooled by the cooling means (100) falls below the reference value, the refrigerant evaporates in the refrigerator internal heat exchanger (64a). The target value of temperature is set to the first target value. The controller (110) is used when the difference between the set temperature in the refrigerator cooled by the refrigerator internal heat exchanger (64a) and the actual temperature in the refrigerator is equal to or greater than a predetermined determination value. The inside load is determined to be greater than or equal to the reference load. The measured value of the storage temperature sensor (126) is used as the actual temperature in the storage.

-Driving action-
Next, the operation performed by the refrigeration apparatus (1) will be described for each type of operation. The refrigeration apparatus (1) is configured to be able to set seven types of operation modes. Specifically, <i> cooling operation that only cools the indoor unit (50), <ii> heating operation that only heats the indoor unit (50), and <iii> the first internal unit (60a) and the first Refrigerated refrigeration operation (second cooling operation) that only cools the inside of the warehouse with the two inside units (60b), <iv> Inside the compartment with the first inside unit (60a) and the second inside unit (60b) Cooling and cooling operation (first cooling operation) in which cooling is performed in the indoor unit (50) with cooling of the air, without using the <v> outdoor heat exchanger (15), the first internal unit (60a) and the second storage The first cooling / heating operation (second cooling operation) for cooling the inside of the cabinet in the inner unit (60b) and the heating in the indoor unit (50), <vi> the first cooling / heating operation of the indoor unit (50) When the heating capacity of the indoor unit (50) is insufficient in the second cooling / heating operation (second cooling operation) performed when the heating capacity is excessive, and <vii> the first cooling / heating operation Third cooling heating operation (second cooling operation) is configured to be selectively performed.

<Cooling operation>
In the cooling operation, as shown in FIG. 3, the first four-way switching valve (31) and the second four-way switching valve (32) are both set to the first state, and the second compressor (14b) Driving is performed. Each internal expansion valve (63) is set in a closed state. In the cooling operation, a vapor compression refrigeration cycle in which the outdoor heat exchanger (15) serves as a condenser and the indoor heat exchanger (54) serves as an evaporator is performed. In the cooling operation, the third compressor (14c) is also operated when the cooling capacity is insufficient. At that time, the third four-way selector valve (33) is set to the second state, and the third compressor (14c) constitutes an indoor compressor. The first compressor (14a) is always stopped.

  Specifically, in the cooling operation, the refrigerant discharged from the second compressor (14b) is condensed in the outdoor heat exchanger (15) and flows into the indoor circuit (52) through the receiver (85). In the indoor circuit (52), the refrigerant flowing in is depressurized by the indoor expansion valve (53), and then absorbs heat from the indoor air by the indoor heat exchanger (54) and evaporates. The indoor air cooled by the refrigerant is supplied to the store space. The refrigerant evaporated in the indoor heat exchanger (54) is sucked into the second compressor (14b) and discharged again. In addition, the evaporation temperature of the refrigerant | coolant in an indoor heat exchanger (54) is set, for example to 5 degreeC. This is the same in the following cooling and cooling operations.

<Heating operation>
In the heating operation, as shown in FIG. 4, the second four-way switching valve (31) is set to the second state and the second four-way switching valve (32) is set to the first state. The compressor (14b) is operated. Each internal expansion valve (63) is set in a closed state. In the heating operation, a vapor compression refrigeration cycle is performed in which the indoor heat exchanger (54) serves as a condenser and the outdoor heat exchanger (15) serves as an evaporator. In the heating operation, when the heating capacity is insufficient, the third compressor (14c) is also operated. At that time, the third four-way selector valve (33) is set to the second state. The first compressor (14a) is always stopped.

  Specifically, the refrigerant discharged from the second compressor (14b) flows into the indoor circuit (52), dissipates heat to the indoor air in the indoor heat exchanger (54), and condenses. The room air heated by the refrigerant is supplied to the store space. The refrigerant condensed in the indoor heat exchanger (54) is reduced in pressure by the first outdoor expansion valve (66), then evaporated in the outdoor heat exchanger (15), sucked into the second compressor (14b), and discharged again. Is done.

<Refrigeration operation>
In the refrigeration operation, as shown in FIG. 5, the first compressor (14a) is operated with the first four-way switching valve (31) set to the first state. The indoor expansion valve (53) is set in a closed state. In the refrigeration operation, a vapor compression refrigeration cycle is performed in which the outdoor heat exchanger (15) serves as a condenser and each of the internal heat exchangers (64) serves as an evaporator. In the refrigeration operation, the third compressor (14c) is also operated when the internal cooling capacity is insufficient. At that time, the third four-way selector valve (33) is set to the first state, and the third compressor (14c) constitutes the internal compressor. The second compressor (14b) is always stopped.

  Specifically, in the refrigeration operation, the refrigerant discharged from the first compressor (14a) is condensed in the outdoor heat exchanger (15). The refrigerant condensed in the outdoor heat exchanger (15) is distributed to the first internal circuit (61a) and the second internal circuit (61b) through the receiver (85).

  In the first internal circuit (61a), the inflowing refrigerant is depressurized by the internal expansion valve (63a), and then absorbs heat from the internal air by the internal heat exchanger (64a) to evaporate. The inside air cooled by the refrigerant is supplied to the inside of the refrigerated showcase. In the second internal circuit (61b), the refrigerant that has flowed in is decompressed by the internal expansion valve (63b) and then absorbs heat from the internal air in the internal heat exchanger (64b) to evaporate. The internal air cooled by the refrigerant is supplied into the freezer showcase. The refrigerant evaporated in the internal heat exchanger (64b) is compressed by the booster compressor (86). Then, the refrigerant evaporated in the internal heat exchanger (64a) and the refrigerant compressed by the booster compressor (86) are sucked into the first compressor (14a) and discharged again after joining.

<Cooling and cooling operation>
In the cooling and cooling operation, the first four-way switching valve (31) and the second four-way switching valve (32) are both set to the first state, and the first compressor (14a) and the second compressor (14b ) Is performed. In the cooling / cooling operation, a vapor compression refrigeration cycle is performed in which the outdoor heat exchanger (15) serves as a condenser and the indoor heat exchanger (54) and each internal heat exchanger (64) serve as an evaporator.

  In the cooling / cooling operation, when the cooling capacity of the indoor unit (50) and the cooling capacity of the internal unit (60) are sufficient, the operation of the third compressor (14c) is stopped. Further, when the cooling capacity in the internal unit (60) is insufficient, as shown in FIG. 6, the third four-way selector valve (33) is set to the first state and the third compressor (14c) Driving is performed. In this case, the third compressor (14c) is an internal compressor. When the cooling capacity of the indoor unit (50) is insufficient, as shown in FIG. 7, the third four-way selector valve (33) is set to the second state and the third compressor (14c) is operated. Is done. In this case, the third compressor (14c) is an indoor compressor.

  Specifically, in the cooling and cooling operation, the refrigerant discharged from the first compressor (14a) and the second compressor (14b) is condensed in the outdoor heat exchanger (15). The refrigerant condensed in the outdoor heat exchanger (15) is distributed to the first internal circuit (61a), the second internal circuit (61b), and the indoor circuit (52) via the receiver (85). .

  The refrigerant distributed to the first internal circuit (61a) and the second internal circuit (61b) flows in the same flow as in the refrigeration operation, and is sucked into the first compressor (14a) and discharged again. . The refrigerant distributed to the indoor circuit (52) flows in the same flow as in the cooling operation, is sucked into the second compressor (14b), and is discharged again.

  The cooling / cooling operation is a cooling operation with different evaporating temperatures at which the evaporating temperatures of the refrigerant differ between the indoor heat exchanger (54) and the internal heat exchanger (64a). In the cooling / cooling operation, as shown in FIG. 8, the low pressure of the refrigeration cycle on the refrigeration and freezing side is lower than the low pressure of the refrigeration cycle on the cooling side. The intermediate pressure of the refrigeration cycle on the refrigeration and freezing side is lower than the intermediate pressure of the refrigeration cycle on the cooling side.

<First cooling and heating operation>
In the first cooling / heating operation, as shown in FIG. 9, the first four-way selector valve (31) is set to the second state and the second four-way selector valve (32) is set to the first state. The first compressor (14a) is operated. In the first cooling / heating operation, the third compressor (14c) is also operated when the internal cooling capacity is insufficient. At that time, the third four-way selector valve (33) is set to the first state. In the first cooling and heating operation, a vapor compression refrigeration cycle is performed in which the indoor heat exchanger (54) serves as a condenser and the internal heat exchanger (64) serves as an evaporator. During the first cooling / heating operation, the cooling capacity (evaporation heat amount) of the first internal unit (60a) and the second internal unit (60b) is balanced with the heating capacity (condensation heat amount) of the indoor unit (50). 100% heat recovery is performed.

  Specifically, the refrigerant discharged from the first compressor (14a) dissipates heat to the indoor air and condenses in the indoor heat exchanger (54). The refrigerant condensed in the indoor heat exchanger (54) is distributed to the first internal circuit (61a) and the second internal circuit (61b), respectively. The refrigerant distributed to the first internal circuit (61a) and the second internal circuit (61b) flows in the same flow as in the refrigeration operation, and is sucked into the first compressor (14a) and discharged again. .

<Second cooling and heating operation>
The second cooling / heating operation is performed by switching the second four-way switching valve (32) to the second state as shown in FIG. 10 when the heating capacity is surplus during the first cooling / heating operation. . In the second cooling / heating operation, the outdoor heat exchanger (15) operates as a condenser. The setting during the second cooling / air-heating operation is basically the same as the first cooling / air-heating operation except for the second four-way switching valve (32).

  In the second cooling / heating operation, a part of the refrigerant discharged from the first compressor (14a) flows into the outdoor heat exchanger (15). In the outdoor heat exchanger (15), the refrigerant flowing in dissipates heat to the outdoor air and condenses. The refrigerant condensed in the outdoor heat exchanger (15) merges with the refrigerant condensed in the indoor heat exchanger (54) and is distributed to the first internal circuit (61a) and the second internal circuit (61b), respectively. The In the second cooling and heating operation, the cooling capacity (evaporation heat amount) of the first internal unit (60a) and the second internal unit (60b) and the heating capacity (condensation heat amount) of the indoor unit (50) are balanced. The excess condensation heat is released in the outdoor heat exchanger (15).

<Third cooling and heating operation>
In the third cooling and heating operation, when the heating capacity is insufficient during the first cooling and heating operation, the second four-way switching valve (32) is set to the first state and the first outdoor side is set as shown in FIG. This is done by operating the second compressor (14b) with the expansion valve (66) set to the open state. In the third cooling and heating operation, a vapor compression refrigeration cycle is performed in which the indoor heat exchanger (54) serves as a condenser, and the internal heat exchanger (64) and the outdoor heat exchanger (15) serve as an evaporator.

  In the third cooling / heating operation, the refrigerant condensed in the indoor heat exchanger (54) is not only supplied to the first internal circuit (61a) and the second internal circuit (61b) but also to the outdoor heat exchanger (15). Distributed. The refrigerant distributed to the outdoor heat exchanger (15) is decompressed by the first outdoor expansion valve (66), evaporates in the outdoor heat exchanger (15), and is sucked into the second compressor (14b). It is discharged again. In the third cooling / heating operation, the cooling capacity (evaporation heat amount) of the first internal unit (60a) and the second internal unit (60b) and the heating capacity (condensation heat amount) of the indoor unit (50) are balanced. Instead, the insufficient heat of evaporation is absorbed by the outdoor heat exchanger (15).

<Injection operation>
In the present embodiment, an injection operation is performed in which an intermediate pressure refrigerant is injected into the intermediate pressure compression chamber (73) of the compressor (14) during operation. Hereinafter, during the cooling and cooling operation, the first compressor (14a) and the third compressor (14c) constitute an in-compartment compressor, and the second compressor (14b) constitutes an indoor compressor. The injection operation will be described.

  In the injection operation, the second outdoor expansion valve (67) is set to the open state. When the second outdoor expansion valve (67) is set to the open state, a part of the refrigerant flowing through the second liquid pipe (25) flows into the main injection pipe (30d) as shown in FIG. In the main injection pipe (30d), the temperature of the refrigerant that has flowed is reduced by being reduced to an intermediate pressure by the second outdoor expansion valve (67). The refrigerant decompressed by the second outdoor expansion valve (67) exchanges heat with the refrigerant flowing through the second liquid pipe (25) in the second intermediate heat exchanger (17). In the second intermediate heat exchanger (17), the refrigerant in the main injection pipe (30d) is heated and evaporates, while the refrigerant flowing in the second liquid pipe (25) is cooled to be in a supercooled state. Then, the refrigerant evaporated in the second intermediate heat exchanger (17) is injected into the compression chamber (73) of the intermediate pressure of each compressor (14a, 14b, 14c) through each branch injection pipe (30a, 30b, 30c). Is done.

  In this refrigeration system (1), even in the third cooling / heating operation, the intermediate pressure compression chamber (73) of the internal compressor (14a, 14b) and the intermediate pressure of the indoor compressor (14b, 14c) An injection operation for injecting an intermediate pressure refrigerant into both the compression chambers (73) is performed. In the cooling operation in which only the indoor heat exchanger (54) operates as an evaporator, an injection operation in which an intermediate pressure refrigerant is injected into the intermediate pressure compression chamber (73) of the indoor compressor (14b, 14c) is performed. Is called. In the refrigerator-freezing operation, the first cooling / heating operation, and the second cooling / heating operation in which only the internal heat exchanger (64) operates as an evaporator, the intermediate pressure compression chamber of the internal compressor (14a, 14b) is used. An injection operation for injecting the intermediate pressure refrigerant into (73) is performed.

-Effect of the embodiment-
In this embodiment, when the temperature of the refrigerant flowing into the internal heat exchanger (64a, 64b) is lowered to some extent, the flow rate of the refrigerant passing through the internal heat exchanger (64a, 64b) is reduced to some extent. In view of the fact that the energy consumption of the internal compressor (14a, 14c) and booster compressor (86) is reduced, the evaporation temperature of the refrigerant in the internal heat exchanger (64a, 64b) The target value is changed to a higher value. Therefore, even when the temperature of the refrigerant flowing into the internal heat exchanger (64a, 64b) changes, the target value of the refrigerant evaporation temperature in the internal heat exchanger (64a, 64b) is constant, The operating efficiency of the refrigeration apparatus (1) can be improved.

  In the present embodiment, for example, the cooling means (100) includes an expansion valve (66) for reducing the refrigerant from the high pressure of the refrigeration cycle to the intermediate pressure in the refrigerant circuit (4) performing two-stage expansion in the cooling operation, and the expansion thereof. Compared to the case where the refrigerant reduced to the intermediate pressure by the valve (66) is constituted by a gas-liquid separator (85) that separates the refrigerant into a liquid refrigerant and a gas refrigerant, in the second operation, Since the degree of supercooling can be made relatively large, the cooling capacity per unit flow rate of the refrigerant flowing into the internal heat exchangers (64a, 64b) can be made relatively large. For this reason, even if the flow rate of the refrigerant passing through the internal heat exchanger (64a, 64b) during the second operation is greatly reduced compared to during the first operation, the cooling capacity of the internal heat exchanger (64a, 64b) Can be relatively reduced, and the difference between the first target value and the second target value, or the difference between the third target value and the fourth target value can be made relatively large. Therefore, the energy consumption of the internal compressors (14a, 14c) and the booster compressor (86) during the second operation can be relatively greatly reduced, so that the operating efficiency of the refrigeration apparatus (1) is further improved. be able to.

  In the present embodiment, in the second cooling operation, the intermediate pressure value of the injection pipe (30) is the intermediate pressure compression chamber (73) of the indoor compressor (14b, 14c) as in the first cooling operation. ), The second operation of reducing the energy consumption of the internal compressors (14a, 14c) is performed by reducing the value of the intermediate pressure of the injection pipe (30). The second operation is not performed in the first cooling operation in which the temperature of the refrigerant after cooling cannot be lower than the reference value due to the restriction of the internal pressure of the compression chamber (73) of the intermediate pressure of the indoor compressor (14b, 14c). The second operation is appropriately selected in the second cooling operation in which the temperature of the cooled refrigerant can be made equal to or lower than the reference value. Therefore, for example, the operating efficiency of the refrigeration apparatus (1) can be improved without causing a situation in which the refrigerant is not injected into the compression chamber (73) of the intermediate pressure of the indoor compressor (14b, 14c).

  Here, in order to perform the second operation during the first cooling operation, the value of the intermediate pressure of the injection pipe (30) is changed to the internal pressure of the compression chamber (73) of the intermediate pressure of the indoor compressor (14b, 14c). If lower than this, the refrigeration oil flowing out from the oil separator (37) will not return to the indoor compressors (14b, 14c). And there exists a possibility that refrigeration oil may run short with an indoor compressor (14b, 14c). However, in the present embodiment, the controller (110) does not perform the second operation in the first cooling operation in which the refrigeration oil flowing out from the oil separator (37) cannot be returned to the indoor compressor (14b, 14c). . Therefore, it is possible to improve the operating efficiency of the refrigeration apparatus (1) while avoiding the situation where the refrigeration oil does not return to the indoor compressor (14b, 14c).

  Moreover, in this embodiment, when the temperature of the refrigerant | coolant after cooling becomes below a reference value, according to the cooling load in an internal heat exchanger (64a, 64b), in an internal heat exchanger (64a, 64b) The operation that increases the cooling capacity and the operation that decreases the energy consumption of the internal compressors (14a, 14c) and the booster compressor (86) are used separately. For this reason, the energy consumption of the internal compressor (14a, 14c) and booster compressor (86) is reduced despite the fact that the cooling load in the internal heat exchanger (64a, 64b) is somewhat high. The second operation is not performed in preference to this, and it is possible to avoid leaving the temperature inside the cabinet cooled by the inside heat exchanger (64a, 64b) from a desired temperature.

-Modification 1 of embodiment-
A first modification of the embodiment will be described. In the first modification, as shown in FIG. 12, the cooling means (100) includes a first outdoor expansion valve (66) for reducing the refrigerant from the high pressure of the refrigeration cycle to the intermediate pressure, and the first outdoor expansion valve (66). And a gas-liquid separator (85) for separating the refrigerant depressurized to an intermediate pressure into a liquid refrigerant and a gas refrigerant. The first outdoor expansion valve (66) is disposed between the outdoor heat exchanger (15) and the receiver (85). In the refrigerant circuit (4), two-stage expansion is performed during the cooling operation. The injection pipe (30) is connected to the top of the receiver (85). In the first modification, the temperature of the refrigerant supplied to the internal heat exchangers (64a, 64b) decreases as the pressure of the intermediate refrigerant after passing through the first outdoor expansion valve (66) decreases.

-Modification 2 of embodiment-
A second modification of the embodiment will be described. In the second modification, both of the two internal units (60a, 60b) are freezing internal units. In the above embodiment, the gas side of the first internal unit (60a) is connected to the suction side of the internal compressor (14a, 14c), but as shown in FIG. 2 are connected to the internal circuit (61b) and the booster circuit (81). In this modified example 2, the internal heat exchanger (64) constitutes a cooling heat exchanger, the booster compressor (86) constitutes a cooling compressor, and each compressor (40) ( 14) constitutes the high stage compressor.

<< Other Embodiments >>
You may comprise the said embodiment like the following modifications.

-First modification-
In the first modification, the compression mechanism (40) may be constituted by two compressors as shown in FIG. In this case, the third four-way selector valve (33) is set to the first state in the refrigeration / freezing operation, the first cooling / heating operation, and the second cooling / heating operation, and the cooling operation, heating operation, cooling / cooling operation, and third cooling are performed. In the heating operation, the second state is set.

-Second modification-
In the above embodiment, the refrigeration apparatus (1) includes the indoor unit (5) and the internal unit (60a, 60b), but the refrigeration apparatus (1) includes only the internal unit (60a, 60b). Also good.

-Third modification-
In the third modified example, the compressor (14) is constituted by a compressor (a rotary compressor, a swing compressor, etc.) other than the scroll compressor.

-Fourth modification-
In the fourth modification, the refrigeration apparatus (1) may be configured to perform a supercritical cycle in which the high pressure of the refrigeration cycle is set to a value higher than the critical pressure of the refrigerant. In this case, in a normal refrigeration cycle in which the high pressure of the refrigeration cycle is set to a value lower than the critical pressure of the refrigerant, a heat exchanger that serves as a condenser operates as a gas cooler.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for a refrigeration apparatus provided with cooling means for cooling the refrigerant supplied to the cooling heat exchanger.

FIG. 1 is a refrigerant circuit diagram of the refrigeration apparatus according to the embodiment. FIG. 2 is a cross-sectional view of the fluid machine of the compressor according to the embodiment. FIG. 3 is a refrigerant circuit diagram illustrating the flow of the refrigerant during the cooling operation in the embodiment. FIG. 4 is a refrigerant circuit diagram illustrating a refrigerant flow during heating operation in the embodiment. FIG. 5 is a refrigerant circuit diagram illustrating the flow of the refrigerant during the refrigeration operation in the embodiment. FIG. 6 is a refrigerant circuit diagram illustrating a refrigerant flow during the cooling / cooling operation in the embodiment. FIG. 7 is a refrigerant circuit diagram illustrating another refrigerant flow during the cooling / cooling operation in the embodiment. FIG. 8 is a ph diagram during cooling and cooling operation in the embodiment. FIG. 9 is a refrigerant circuit diagram illustrating a refrigerant flow during the first cooling / air-heating operation in the embodiment. FIG. 10 is a refrigerant circuit diagram illustrating a refrigerant flow during the second cooling / air-heating operation in the embodiment. FIG. 11 is a refrigerant circuit diagram illustrating a refrigerant flow during the third cooling / air-heating operation in the embodiment. FIG. 12 is a refrigerant circuit diagram of a refrigeration apparatus according to Modification 1 of the embodiment. FIG. 13 is a refrigerant circuit diagram of a refrigeration apparatus according to Modification 2 of the embodiment. FIG. 14 is a refrigerant circuit diagram of a refrigeration apparatus according to a first modification of the other embodiment.

Explanation of symbols

1 Refrigeration equipment
4 Refrigerant circuit
14a First compressor (cooling compressor)
14b Second compressor (high temperature side compressor)
16 1st intermediate heat exchanger (cooling means)
17 Second intermediate heat exchanger (cooling means)
30 Injection pipe (cooling means, injection passage)
54 Indoor heat exchanger (high temperature side heat exchanger)
64a Internal heat exchanger (cooling heat exchanger)
64b Inside heat exchanger (low temperature side heat exchanger)
86 Booster compressor (low stage compressor)
100 Cooling means
110 Controller (Control means)

Claims (7)

A cooling heat exchanger (64a, 64b) for cooling the target space, and a cooling compressor (14a, 86) for sucking refrigerant evaporated in the cooling heat exchanger (64a, 64b) are provided, It has a refrigerant circuit (4) that circulates refrigerant to perform the refrigeration cycle,
In the refrigeration apparatus in which the cooling operation is performed in which the cooling heat exchanger (64a, 64b) operates as an evaporator in the refrigerant circuit (4).
Cooling means (100) for cooling the refrigerant supplied to the cooling heat exchanger (64a, 64b) during the cooling operation;
During the cooling operation, when the temperature of the refrigerant cooled by the cooling means (100) becomes higher than a predetermined reference value, the evaporation temperature of the refrigerant in the cooling heat exchanger (64a, 64b) is the first target value. A first operation for controlling the refrigerant circuit (4) so that the temperature of the refrigerant cooled by the cooling means (100) is equal to or lower than the reference value, the cooling heat exchanger (64a, 64b) Control means (110) for switching the second operation for controlling the refrigerant circuit (4) so that the evaporation temperature of the refrigerant in the refrigerant reaches a second target value higher than the first target value. A refrigeration apparatus characterized by In claim 1,
In the refrigerant circuit (4), the first passage in which the cooling heat exchanger (64a) is provided and the evaporating temperature of the refrigerant is set to a value lower than that of the cooling heat exchanger (64a) in the cooling operation. A low-temperature side heat exchanger (64b) and a second passage provided with a low-stage compressor (86) for compressing the refrigerant evaporated in the low-temperature side heat exchanger (64b) are provided in parallel with each other;
In the cooling operation, the refrigerant cooled by the cooling means (100) is supplied to the cooling heat exchanger (64a) and the low temperature side heat exchanger (64b), and the cooling compressor (14a) While compressing the refrigerant discharged from the low-stage compressor (86) together with the refrigerant evaporated in the cooling heat exchanger (64a),
The control means (110) controls the refrigerant circuit (4) so that the evaporation temperature of the refrigerant in the low temperature side heat exchanger (64b) becomes a third target value during the first operation, and the second circuit (110). During operation, the refrigerant circuit (4) is controlled such that the evaporation temperature of the refrigerant in the low temperature side heat exchanger (64b) becomes a fourth target value higher than the third target value. . In claim 1,
The refrigerating apparatus, wherein the refrigerant circuit (4) is provided with a high-stage compressor (14) for compressing the refrigerant discharged from the cooling compressor (86). In any one of Claims 1 thru | or 3,
The cooling means (100) includes an injection passage (30) for injecting an intermediate pressure refrigerant in the refrigeration cycle into the intermediate pressure compression chamber (73) of the cooling compressor (14a), and the injection passage (30 And an intermediate heat exchanger (16, 17) for cooling the refrigerant supplied to the cooling heat exchanger (64a, 64b) by the intermediate pressure refrigerant. In claim 4,
The refrigerant circuit (4) includes a high temperature side heat exchanger (54) in which the evaporation temperature of the refrigerant is set higher than that of the cooling heat exchanger (64a), and a high temperature side heat exchanger (54). A high temperature side compressor (14b) for sucking the evaporated refrigerant,
A first cooling operation in which both the cooling heat exchanger (64a) and the high temperature side heat exchanger (54) operate as an evaporator, and a second cooling operation in which only the cooling heat exchanger (64a) operates as an evaporator. Are performed as one of the above cooling operations,
The injection passage (30) is connected not only to the intermediate pressure compression chamber (73) of the cooling compressor (14a) but also to the intermediate pressure compression chamber (73) of the high temperature side compressor (14b),
In the first cooling operation, the control means (110) sets the intermediate pressure value of the injection passage (30) so that the temperature of the refrigerant cooled by the cooling means (100) is higher than the reference value. A first intermediate pressure adjusting operation to be controlled and the first operation are performed, and in the second cooling operation, the injection passage is configured such that the temperature of the refrigerant cooled by the cooling means (100) is equal to or lower than the reference value. A refrigeration apparatus performing a second intermediate pressure adjustment operation for controlling the value of the intermediate pressure in (30) and the second operation. In any one of claims 1 to 5,
When the cooling load in the cooling heat exchanger (64a, 64b) is equal to or higher than a predetermined reference load, the control means (110) has a temperature of the refrigerant cooled by the cooling means (100) equal to or lower than the reference value. Even so, the refrigerant evaporating temperature in the cooling heat exchanger (64a, 64b) is set to the first target value without performing the second operation. In any one of Claims 1 thru | or 6,
The control means (110) controls the cooling compressor (14a, 86) so that the pressure of the refrigerant sucked into the cooling compressor (14a, 86) becomes the saturation pressure of the refrigerant at the target value. A refrigeration apparatus characterized by controlling an operating capacity.

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