JP2010014308A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the overload operating state of a compressing mechanism without lowering an operational capacity of a variable capacity type compressor, in a refrigerating device comprising a refrigerant circuit in which the compressing mechanism composed of the variable capacity type and fixed capacity type compressors, and a plurality of utilization side heat exchangers are connected. <P>SOLUTION: This refrigerating device comprises an injection circuit 30 connecting first injection piping 30e branched from a refrigerant circuit 4, and intermediate ports of second and third compressors 14b, 14c constituting the fixed capacity type compressor, the injection circuit 30 is provided with second and third opening/closing valves 6, 7, and the second and third valves 6, 7 are closed when the compressing mechanism 14 composed of the first, second and third compressors 14a, 14b, 14c is in an overload operating state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus having a refrigerant circuit in which a compression mechanism composed of a plurality of compressors and a plurality of usage-side heat exchangers are connected to perform a refrigeration cycle, and in particular, for avoiding overload operation of the compression mechanism. It is concerned.

  Conventionally, a refrigeration apparatus including a refrigerant circuit that performs a vapor compression refrigeration cycle is known. Among the refrigeration apparatuses, there is an apparatus that performs both an air-conditioning operation that performs indoor air conditioning and a cooling operation that performs refrigeration and freezing of a showcase that houses food or the like (see, for example, Patent Document 1). This refrigeration apparatus is installed in, for example, a convenience store.

  The refrigeration apparatus includes an outdoor unit (heat source side unit) having a compression mechanism including three compressors and an outdoor heat exchanger (heat source side heat exchanger), and an indoor heat exchanger (second use side heat exchanger). An indoor unit (second usage side unit), a refrigeration unit (first usage side unit) having a refrigeration heat exchanger (first usage side heat exchanger), and a refrigeration heat exchanger (first usage side heat exchange). And a refrigeration unit (first use side unit). The indoor unit, the refrigeration unit, and the refrigeration unit are connected to the outdoor unit through a communication pipe.

  The refrigerant circuit includes a first usage system circuit and a second usage system circuit. The first utilization system circuit is configured by connecting an outdoor unit, a refrigeration unit, and a refrigeration unit via a first communication pipe (gas side and liquid side). On the other hand, the second refrigerant system circuit is configured by connecting an outdoor unit and an indoor unit by a second communication pipe (gas side and liquid side). In this configuration, the outdoor unit is shared by the first usage system circuit and the second usage system circuit.

  In this refrigeration apparatus, the refrigerant circulating in each usage-side system circuit can be evaporated at different temperatures. A refrigeration heat exchanger and a refrigeration heat exchanger are fixedly connected to the suction side of one of the three compressors via a first liquid side connection pipe to form a first refrigerant system circuit. In addition, an indoor heat exchanger is fixedly connected to the suction side of the other compressor via a second liquid side connecting pipe to constitute a second refrigerant system circuit. Further, the first liquid side connecting pipe or the second liquid side connecting pipe is selectively connected to the suction side of the remaining one compressor. The discharge pipes of all the compressors are connected to one end of the collective pipe, and the other end of the collective pipe is branched and connected to the first gas side connecting pipe and the second gas side connecting pipe.

In such a refrigeration apparatus, an inverter compressor (variable capacity compressor) is used for the purpose of controlling the capacity of the cooling capacity. However, if all three compressors are configured with inverter compressors, the manufacturing cost of the refrigeration apparatus will increase. Therefore, one of the three compressors is configured with an inverter compressor, and the remaining two units. May be composed of a non-inverter compressor (fixed capacity compressor). And when comprised in this way, the said inverter compressor is connected to the 1st refrigerant | coolant system circuit with a higher priority with respect to capacity control.
Japanese Patent No. 3982548

  By the way, when the high pressure of the refrigerant circuit rises due to an increase in outdoor outside air temperature and the compression mechanism including the three compressors enters an overload operation state, the conventional refrigeration apparatus uses the inverter compressor. The operating frequency was reduced.

  In this way, although the discharge amount of the high-pressure refrigerant in the inverter compressor is reduced and it is easy to avoid the overload operation state, the intake amount of the low-pressure refrigerant in the inverter compressor is also reduced, so the priority for capacity control is high. There is a problem that the heat exchange capacity of the refrigeration heat exchanger and the refrigeration heat exchanger connected to the first refrigerant system circuit of the other side is reduced.

  The present invention has been made in view of such a point, and an object thereof is to include a refrigerant circuit in which a compression mechanism including a variable capacity type and a fixed capacity type compressor and a plurality of use side heat exchangers are connected. Another object of the present invention is to avoid the overload operation state of the compression mechanism without reducing the operation capacity of the variable capacity compressor.

  The first aspect of the invention relates to a compression mechanism (14) comprising a variable capacity compressor (14a) and a fixed capacity compressor (14b, 14c) and a heat source side heat exchange connected to the discharge side of the compression mechanism (14). A heat source side unit (10) having a heat exchanger (15), a first usage side unit (60a, 60b) having a first usage side heat exchanger (64a, 64b), and a second usage side heat exchanger (54 And a second usage side unit (50) connected to the heat source side unit (10) and the first usage side unit (60a, 60b) and the second usage side unit (50). The first usage side heat exchanger (64a, 64b) is connected to the suction side of the variable capacity compressor (14a), and the second usage side is connected to the suction side of the fixed capacity compressor (14b, 14c). A refrigeration apparatus including a refrigerant circuit (4) connected to the side heat exchanger (54) and performing a vapor compression refrigeration cycle is assumed.

  In the refrigeration apparatus, a branch pipe (30e) branched from the high-pressure line (25) through which the refrigerant that has passed through the heat source side heat exchanger (15) of the refrigerant circuit (4) flows, and the branch pipe (30e) are provided. An injection circuit (30) for connecting the branch pipe (30e) and the intermediate port of the fixed displacement compressor (14b, 14c), and the injection circuit (30). The flow rate adjusting means (6, 7) provided between the pressure reducing means (67) and the intermediate port of the fixed capacity compressor (14b, 14c) and the compression mechanism (14) are in an overload operation state The control means (100) for reducing the opening degree of the flow rate adjusting means (6, 7). Here, the intermediate port opens to a compression chamber at an intermediate pressure position in the fixed capacity compressor (14b, 14c).

  In the first invention, the high-pressure refrigerant discharged from the compression mechanism (14) is condensed in the heat source side heat exchanger (15) and then flows into the high-pressure line (25). The high-pressure refrigerant that has flowed into the high-pressure line (25) is diverted, and one flows to each usage-side unit (50, 60a, 60b) and the other flows to the branch pipe (30e). The high-pressure refrigerant that has flowed toward the branch pipe (30e) is depressurized to a predetermined pressure by the depressurizing means (67) to become an intermediate-pressure refrigerant, and then passes through the flow rate adjusting means (6, 7). It flows into the intermediate port of the fixed capacity compressor (14b, 14c).

  The fixed capacity compressor (14b, 14c) is in the middle of sucking and compressing the low-pressure refrigerant flowing out from the second usage side heat exchanger (64a, 64b) of the usage side unit (60a, 60b). The intermediate pressure refrigerant is injected from the intermediate port. Then, after the low-pressure refrigerant in the middle of compression and the intermediate-pressure refrigerant merge, they are further compressed and discharged as high-pressure refrigerant.

  When the control means (100) determines that the compression mechanism (14) is in an overload operation state, the control means (100) reduces the opening of the flow rate adjustment means (6, 7) to reduce the fixed capacity compressor (14b). 14c), the amount of intermediate pressure refrigerant injected can be reduced. As a result, the discharge amount of the high-pressure refrigerant in the fixed capacity compressor (14b, 14c) can be reduced by the amount by which the injection amount of the intermediate-pressure refrigerant is reduced. Due to the decrease in the flow rate of the high-pressure refrigerant, the overload operation state of the compression mechanism (14) can be avoided.

  In a second aspect based on the first aspect, the flow rate adjusting means (6, 7) is constituted by an openable / closable open / close valve (6, 7), and the control means (100) is constituted by the compression mechanism (14 ) Is configured to close the on-off valve (6, 7) when it is determined that it is in an overload operation state.

  In the second invention, when the control means (100) determines that the compression mechanism (14) is in an overload operation state, the fixed displacement compressor is closed by closing the on-off valve (6, 7). It is possible to prevent the intermediate pressure refrigerant from being injected into (14b, 14c). Thus, the relatively inexpensive on-off valve (6, 7) can be used as the flow rate adjusting means (6, 7).

  According to a third invention, in the first or second invention, the control means (100) includes a pressure detection means (18) for detecting a discharge pressure of the compression mechanism (14), and the pressure detection means ( A first overload determination unit (101) is provided that determines that the compression mechanism (14) is in an overload operation state when the detected value of 18) is equal to or greater than a predetermined value.

  In the third invention, based on the discharge pressure of the compression mechanism (14), it can be determined whether or not the compression mechanism (14) is in an overload operation state.

  According to a fourth invention, in any one of the first to third inventions, the control means (100) determines whether the compression mechanism (14) is in an overload operation state. The second overload determination unit (102) includes an operation current detection unit (46) that detects an operation current value of the compression mechanism (14), and includes a determination unit (102). When the detected value of 46) becomes a predetermined value or more, the compression mechanism (14) is determined to be in an overload operation state.

  In the fourth invention, unlike the third invention, it can be determined whether or not the compression mechanism (14) is in an overload operation state based on the operating current value of the compression mechanism (14). .

  According to a fifth invention, in any one of the first to fourth inventions, the decompression side flow path (17b) through which the refrigerant decompressed by the decompression means (67) flows and the high-pressure refrigerant in the refrigerant circuit (4) A supercooling heat exchanger (17) having a flowing high pressure side flow path (17a), the pressure reducing side flow path (17b) being connected to a branch pipe (30e) of the injection circuit (30), and the high pressure side The flow path (17a) is connected to the high-pressure line (25) of the refrigerant circuit (4).

  In the fifth invention, by providing the supercooling heat exchanger (17), the refrigerant depressurized by the depressurizing means (67) is subjected to heat exchange with the high-pressure refrigerant flowing through the refrigerant circuit (4). It can be injected into fixed capacity compressors (14b, 14c).

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the compressor (14a, 14b, 14c) is provided in the discharge pipe (56a, 56b, 56c) and the compressor (14a, 14b, 14c) oil separator (37a, 37b, 37c) that separates the refrigerating machine oil from the discharged refrigerant, and an oil return pipe (43a, 43b, 43c) connected to the oil separator (37a, 37b, 37c) And having one end connected to the oil return pipe (43a, 43b, 43c) and the other end connected to a branch pipe (42) branched from the injection circuit (30), the oil return pipe (43a, 43b, 43c) and an oil return circuit (40) for returning the refrigeration oil to the compressors (14a, 14b, 14c).

  In the sixth aspect of the invention, the refrigerating machine oil separated from the refrigerant discharged by the oil separator (37a, 37b, 37c) is moved through the injection circuit (40) to the intermediate pressure position in each compressor (14a, 14b, 14c). Can be returned to the compression chamber.

  According to the present invention, when it is determined in the control means (100) that the compression mechanism (14) is in an overload operation state, the opening of the flow rate adjusting means (6, 7) is reduced and the fixed The discharge amount of the intermediate pressure refrigerant in the capacity type compressor (14b, 14c) can be reduced. As a result, the discharge amount of the high-pressure refrigerant in the compression mechanism (14) can be reduced without reducing the operation capacity of the variable capacity compressor (14a), and the overload operation of the compression mechanism (14) can be reduced. A state can be avoided.

  Further, according to the second invention, the on-off valve (6, 7) can be used as a flow rate adjusting means (6, 7) for avoiding an overload operation state of the compression mechanism (14). As a result, the cost of the flow rate adjusting means (6, 7) can be reduced.

  Moreover, according to the said 3rd invention, based on the discharge pressure of the said compression mechanism (14), it can be determined whether this compression mechanism (14) is an overload driving | running state. Thereby, the overload operation state of the compression mechanism (14) can be more reliably determined, and the overload operation state can be avoided.

  According to the fourth aspect of the invention, it can be determined whether or not the compression mechanism (14) is in an overload operation state based on the operating current value of the compression mechanism (14). Thereby, the overload operation state of the compression mechanism (14) can be more reliably determined, and the overload operation state can be avoided.

  Further, according to the fifth aspect, the degree of supercooling of the high-pressure refrigerant can be increased while injecting into the fixed capacity compressor (14b, 14c). Thereby, compared with the case where the said supercooling heat exchanger (17) is not provided, it can inject into the said fixed capacity type compressor (14b, 14c), improving the COP of the said refrigeration apparatus (1).

  According to the sixth aspect of the invention, the compressor (14a, 14b, 14c) is injected into the fixed capacity compressor (14b, 14c) via the injection circuit (40), while the refrigerant is injected. Refrigerating machine oil can be returned to Thereby, it is possible to inject the fixed capacity compressor (14b, 14c) while improving the reliability of each compressor (14a, 14b, 14c).

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

  The refrigeration apparatus (1) of this embodiment is installed in a convenience store or the like, and performs cooling of a refrigerator and a freezer and air conditioning in a store at the same time.

  As shown in FIG. 1, the refrigeration apparatus (1) includes a heat source unit (heat source side unit) (10), an air conditioning unit (50), a refrigeration unit (60a), a refrigeration unit (60b), and a controller (control). Means) (100). The heat source unit (10) is provided with a heat source circuit (11). The air conditioning unit (50) is provided with an air conditioning circuit (52). The refrigeration unit (60a) is provided with a refrigeration circuit (61a). The refrigeration unit (60b) is provided with a refrigeration circuit (61b). The refrigeration unit (60a) and the refrigeration unit (60b) are connected in parallel to form a first usage side unit (60a, 60b), and the air conditioning unit (50) is a second usage side unit (50 ).

  In the refrigeration apparatus (1), the first usage side unit (60a, 60b) and the second usage side unit (50) are connected to the heat source unit (10) by a communication pipe. A refrigerant circuit (4) for performing a vapor compression refrigeration cycle is configured.

  Specifically, the connecting pipe is composed of 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 side connecting pipe (3b). Has been.

  One end of the first liquid side connecting pipe (2a) is connected to the first liquid side closing valve (111) of the heat source circuit (11). The other end of the first liquid side communication pipe (2a) is connected to the air conditioning circuit (52). One end of the second liquid side connecting pipe (2b) is connected to the second liquid side closing valve (112) of the heat source circuit (11). The other end of the second liquid side connection pipe (2b) branches into two and is connected to the refrigeration circuit (61a) and the refrigeration circuit (61b), respectively. One end of the first gas side communication pipe (3a) is connected to the first gas side closing valve (113) of the heat source circuit (11), and the other end is connected to the air conditioning circuit (52). One end of the second gas side communication pipe (3b) is connected to the second gas side closing valve (114) of the heat source circuit (11). The other end of the second gas side communication pipe (3b) branches into two and is connected to the refrigeration circuit (61a) and the refrigeration circuit (61b), respectively.

  Then, a refrigeration circuit (61a) and a refrigeration circuit (61b) are connected to the heat source circuit (11) by the second liquid side communication pipe (2b) and the second gas side communication pipe (3b). The utilization system circuit (4a) is configured, and the air conditioning circuit (52) is connected to the heat source circuit (11) by the first liquid side communication pipe (2a) and the first gas side communication pipe (3a). The 2nd utilization system circuit (4b) is comprised.

<Heat source unit>
The heat source circuit (11) of the heat source unit (10) includes three compressors (14a, 14b, 14c) from first to third and three four-way switching valves (first to third) ( 31, 32, 33), heat source heat exchanger (heat source side heat exchanger) (15), receiver (16), supercooling heat exchanger (17), and heat source expansion valve (66) Is provided. The heat source circuit (11) is connected to an injection circuit (30) and an oil return circuit (40).

  The three compressors (14a, 14b, 14c) from the first to the third constitute a compression mechanism (14) of the refrigerant circuit (4), and are arranged on the first utilization system circuit (4a) side. The compressor is divided into a compressor on the second utilization system circuit (4b) side. Specifically, the first compressor (14a) is fixedly used in the first utilization system circuit (4a) for refrigeration / refrigeration in principle, and the third compressor (14c) is in principle used for the air conditioning first. 2 Used in a fixed manner in the utilization system circuit (4b). The second compressor (14b) is used by switching to the first usage system circuit (4a) and the second usage system circuit (4b).

  Each of the first to third compressors (14a, 14b, 14c) is a hermetic high-pressure dome type scroll compressor, and each compressor (14a, 14b, 14c) A compression section having a compression chamber for compressing the refrigerant and an electric motor as a drive section for driving the compression section are provided. The compression chamber is provided with an intermediate port so as to open to an intermediate pressure position of the compression chamber.

  An inverter is connected only to the electric motor of the first compressor (14a), and the number of revolutions of the electric motor can be freely changed within a predetermined range. That is, the first compressor (14a) constitutes a variable capacity compressor whose operating capacity can be increased or decreased by the inverter. The motors of the second and third compressors (14b, 14c) are not provided with an inverter, and the rotation speed of the motors is fixed. That is, the said 2 and 3 compressor (14b, 14c) comprises the fixed capacity type compressor with which the operating capacity was fixed.

  First, second, and third discharge pipes (56a, 56b, and 56c) are connected to the discharge sides of the compressors (14a, 14b, and 14c), respectively. Each discharge pipe (56a, 56b, 56c) is provided with a check valve (CV1, CV2, CV3). These discharge pipes (56a, 56b, 56c) are connected to the first four-way switching valve (31) via a discharge junction pipe (21). Each check valve (CV1, CV2, CV3) is attached in a direction allowing only the flow of refrigerant from each compressor (14a, 14b, 14c) toward the discharge junction pipe (21).

  One end of each of the first, second and third suction pipes (57a, 57b, 57c) is connected to the suction side of each compressor (14a, 14b, 14c). The other end of the first suction pipe (57a) branches into two, one is connected to the third four-way switching valve (33) via the check valve (CV7), and the other is on the second gas side Connected to the shut-off valve (114). The other end of the second suction pipe (57b) is connected to the third four-way switching valve (33). The other end of the third suction pipe (57c) branches into two, one is connected to the third four-way switching valve (33) via a check valve (CV8), and the other is connected to the third suction pipe (57c). 2 is connected to the four-way selector valve (32). The two check valves (CV7, CV8) are attached in directions that allow only the refrigerant flow toward the third four-way selector valve (33).

  Each of the four-way switching valves (31, 32, 33) has four ports from first to fourth. The first four-way switching valve (31) has a first port as the discharge junction pipe (21), a second port as the fourth port of the second four-way switching valve (32), and a third port as heat source heat. A fourth port is connected to the first gas side shut-off valve (113) on one end side of the exchanger (15). In the second four-way selector valve (32), the first port is branched to the first branch pipe (22) branched from the discharge junction pipe (21), and the second port is the branch end of the third suction pipe (57c). In addition, the fourth port is connected to the second port of the first four-way switching valve (31) described above, while the third port is closed. In the third four-way selector valve (33), the first port is connected to the second branch pipe (120) branched from the discharge junction pipe (21), and the second port is connected to the second suction pipe (57b) described above. Three ports are connected to the branch end of the third suction pipe (57c), and the fourth port is connected to the branch end of the first suction pipe (57a).

  The first, second and third four-way switching valves (31, 32, 33) are in a first state in which the first port and the third port communicate with each other and the second port and the fourth port communicate with each other. (A state indicated by a solid line in FIG. 1) and a second state (a state indicated by a broken line in FIG. 1) in which the first port and the fourth port communicate with each other and the second port and the third port communicate with each other. It has become.

  The heat source heat exchanger (15) is a cross fin type fin-and-tube heat exchanger. A blower fan (23) is provided in the vicinity of the heat source heat exchanger (15). In this heat source heat exchanger (15), heat is exchanged between the refrigerant flowing in the heat source heat exchanger (15) and the outdoor air blown by the blower fan (23).

  The other end of the heat source heat exchanger (15) is connected to the top of the receiver (16) via the first pipe (24). The first pipe (24) is provided with a check valve (CV), and the check valve (CV9) allows only the flow of refrigerant from the heat source heat exchanger (15) to the receiver (16). It is attached in the direction to be.

  The receiver (16) can temporarily store the high-pressure refrigerant condensed in the heat source heat exchanger (15) when the first four-way switching valve (31) is in the first state. One end of a gas vent pipe (48) having a solenoid valve (SV4) is connected to the top of the receiver (16). The other end of the gas vent pipe (48) is connected in the middle of a second injection pipe (30d) of an injection circuit (30) described later.

  One end of a second pipe (high pressure line) (25) is connected to the bottom of the receiver (16). The other end of the second pipe (25) branches, one is connected to the first liquid side shut-off valve (111) via a check valve (CV10), and the other is a subcooling heat exchanger (described later) 17) is connected to the second liquid side shut-off valve (112) via the high pressure side flow path (17a). The check valve (CV10) is attached in such a direction as to allow only the flow of refrigerant from the receiver (16) toward the first liquid side stop valve (111).

  A third pipe (26) and a fourth pipe (27) are provided that bypass the receiver (16) and connect the first pipe (24) and the second pipe (25). One end of the third pipe (26) is connected between the receiver (16) and the check valve (CV9) in the first pipe (24), and the other end is a check in the second pipe (25). It is connected to the valve (CV10) and the first liquid side closing valve (111). One end of the fourth pipe (27) is connected between the heat source heat exchanger (15) and the check valve (CV9) in the first pipe (24), and the other end is connected to the second pipe ( It is connected between the supercooling heat exchanger (17) in 25) and the second liquid side shut-off valve (112).

  The third pipe (26) is provided with a check valve (CV11), which is attached in a direction allowing only the refrigerant flow from the second pipe (25) to the first pipe (24). Yes. The fourth pipe (27) is provided with a heat source expansion valve (66).

  The supercooling heat exchanger (17) has a high-pressure side channel (17a) and a decompression-side channel (17b), and flows through the high-pressure side channel (17a) and the decompression-side channel (17b). The refrigerant is configured to exchange heat. As described above, the high-pressure channel (17a) communicates with the second pipe (25). On the other hand, the decompression side flow path (17b) is connected to an injection circuit (30) described later.

  The injection circuit (30) includes a first injection pipe (branch pipe) (30e), a second injection pipe (30d), and first, second, and third branch injection pipes (30a, 30b, 30c). Yes. The first injection pipe (30e) branches from the second pipe (25) and is connected to the inflow end of the pressure reducing side channel (17b). The first injection pipe (30e) is provided with a supercooling pressure reducing valve (pressure reducing means) (67). The supercooling pressure reducing valve (67) is an electric expansion valve having a variable opening.

  One end of the second injection pipe (30d) is connected to the outflow end of the decompression side flow path (17b), and the other end of the second injection pipe (30d) is connected to the first, second, and third branch injection pipes ( Branches to 30a, 30b, 30c). The first, second, and third branch injection pipes (30a, 30b, 30c) are connected to the intermediate ports of the compressors (14a, 14b, 14c), respectively. The first, second, and third branch injection pipes (30a, 30b, 30c) have a first on-off valve (5), a second on-off valve (flow rate adjusting means) (6, 7), respectively. And check valves (CV4, CV5, CV6) are provided.

  The oil return circuit (40) includes first, second, and third oil separators (oil separators) (37a, 37b, 37c), an oil return main pipe (branch pipe) (42), and first, second, And a third oil return branch pipe (oil return pipe) (43a, 43b, 43c). The first, second and third oil separators (37a, 37b, 37c) are for separating the refrigeration oil from the high-pressure refrigerant of the compressors (14a, 14b, 14c), and the discharge pipes described above. (56a, 56b, 56c) and provided upstream of each check valve (CV1, CV2, CV3).

  One end of the oil return main pipe (42) is connected in the middle of the second injection pipe (30d), and the other end branches to the first, second and third oil return branch pipes (43a, 43b, 43c). ing. The first, second, and third oil return branch pipes (43a, 43b, 43c) are connected to the oil outlets of the first, second, and third oil separators (37a, 37b, 37c), respectively. . The oil return branch pipes (43a, 43b, 43c) have check valves (CV12, CV13, CV14) in order from the first, second, and third oil separators (37a, 37b, 37c). ) And capillary tubes (41a, 41b, 41c). The check valves (CV12, CV13, CV14) are attached in such a direction as to allow only the flow of refrigerating machine oil from the oil return branch pipes (43a, 43b, 43c) to the oil return main pipe (42). Yes.

  The heat source circuit (11) is provided with various sensors and pressure switches. Specifically, each discharge pipe (56a, 56b, 56c) is provided with a discharge pipe temperature sensor (48a, 48b, 48c) and a high pressure switch (39a, 39b, 39c). The discharge pipe temperature sensor (48a, 48b, 48c) detects the temperature of the discharge pipe (56a, 56b, 56c), and the high-pressure switch (39a, 39b, 39c) detects the discharge pressure and detects abnormally high pressure. The refrigeration system (1) is urgently stopped. The first and third suction pipes (57a, 57c) are provided with suction pipe temperature sensors (20a, 20b), respectively. The suction pipe temperature sensors (20a, 20b) detect the temperatures of the first and third suction pipes (57a, 57c).

  At the junction of each discharge pipe (56a, 56b, 56c) (that is, the inflow end of the discharge junction pipe (21)), the discharge pressure of the compression mechanism (14) composed of each compressor (14a, 14b, 14c) is supplied. A discharge pressure sensor (18) is provided as pressure detecting means for detecting. The first suction pipe (57a) is provided with a first suction pressure sensor (19a) for detecting the suction pressure of the compressor (14a) connected to the first utilization system circuit (4a). Yes. The third suction pipe (57c) is provided with a second suction pressure sensor (19b) for detecting the suction pressure of the compressor (14b, 14c) set in the second utilization system circuit (4b). Yes.

  In addition, an outside air temperature sensor (45) for detecting the outside air temperature is provided in the vicinity of the blower fan (23). A first liquid temperature sensor (72) is provided downstream of the supercooling heat exchanger (17) in the second pipe (25). A second liquid temperature sensor (74) is provided downstream of the supercooling pressure reducing valve (67) in the first injection pipe (30e). Each liquid temperature sensor (72, 74) detects the temperature of the liquid refrigerant.

  Further, an operating ammeter (operating current detecting means) (46) electrically connected to the compressors (14a, 14b, 14c) is provided. This operating ammeter (46) measures the operating current of the compression mechanism (14) during driving.

<Air conditioning unit>
The air conditioning circuit (52) of the air conditioning unit (50) is provided with an indoor heat exchanger (second use side heat exchanger) (54) and an indoor expansion valve (53). The indoor heat exchanger (54) is a cross-fin type fin-and-tube heat exchanger. An indoor fan (55) is provided in the vicinity of the indoor heat exchanger (54). In the indoor heat exchanger (54), heat is exchanged between the refrigerant flowing through the indoor heat exchanger (54) and the indoor air blown by the indoor fan (55). The indoor expansion valve (53) is an electric expansion valve whose opening degree can be adjusted.

  In the air conditioning circuit (52), the first refrigerant temperature sensor (122) is connected to the indoor heat exchanger (54) in the pipe between the first gas side communication pipe (3a) and the indoor heat exchanger (54). A second refrigerant temperature sensor (121) is provided in each heat transfer tube. An indoor temperature sensor (123) for detecting the temperature of the air in the store is provided in the vicinity of the indoor heat exchanger (54).

<Refrigerated unit>
The refrigerating circuit (61a) of the refrigerating unit (60a) is provided with a refrigerating heat exchanger (first use side heat exchanger) (64a) and a refrigerating expansion valve (63a). The refrigeration heat exchanger (64a) is a cross-fin type fin-and-tube heat exchanger. A refrigeration fan (65a) is provided in the vicinity of the refrigeration heat exchanger (64a). In the refrigeration heat exchanger (64a), heat is exchanged between the refrigerant flowing through the refrigeration heat exchanger (64a) and the internal air blown by the refrigeration fan (65a).

  In the refrigeration circuit (61a), an outlet refrigerant temperature sensor (125) is provided on the outlet side of the refrigeration heat exchanger (64a). The refrigeration expansion valve (63a) is a temperature-sensitive expansion valve whose opening degree is adjusted according to the temperature detected by the outlet refrigerant temperature sensor (125). Further, in the vicinity of the refrigeration heat exchanger (64a), an internal temperature sensor (124) for detecting the temperature of the internal air in the refrigeration unit (60a) is provided.

<Refrigeration unit>
The refrigeration circuit (61b) of the refrigeration unit (60b) includes a refrigeration expansion valve (63b), a refrigeration heat exchanger (first use side heat exchanger) (64b), and a booster compressor (86). ing. The refrigeration heat exchanger (64b) is a cross-fin type fin-and-tube heat exchanger. A freezing fan (65b) is provided in the vicinity of the freezing heat exchanger (64b). In the refrigeration heat exchanger (64b), heat is exchanged between the refrigerant flowing through the refrigeration heat exchanger (64b) and the internal air blown by the refrigeration fan (65b).

  In the refrigeration circuit (61b), an outlet refrigerant temperature sensor (126) is provided on the outlet side of the refrigeration heat exchanger (64b). The refrigeration expansion valve (63b) is a temperature-sensitive expansion valve whose opening degree is adjusted according to the temperature detected by the outlet refrigerant temperature sensor (126). Further, in the vicinity of the freezing heat exchanger (64b), an internal temperature sensor (127) for detecting the temperature of the air in the freezer is provided.

  The booster compressor (86) is a high-pressure dome type scroll compressor, and constitutes a variable capacity compressor similar to the first compressor (14a). The discharge pipe (78) of the booster compressor (86) is connected to the second gas side communication pipe (3b), and the suction pipe (81) of the booster compressor (86) is connected to the refrigeration heat exchanger (64b). ing. The discharge pipe (78) is provided with an oil separator (87), a high pressure switch (88), and a check valve (CV15) in this order from the booster compressor (86) side. The suction pipe (81) is provided with a suction pressure sensor (89) for detecting the suction pressure of the booster compressor (86). An oil return pipe (92) for returning the refrigeration oil separated from the refrigerant to the suction side of the booster compressor (86) is connected to the oil separator (87). The oil return pipe (92) is provided with a capillary tube (91).

  The refrigeration circuit (61b) is provided with a bypass pipe (95) that connects the suction pipe (81) and the discharge pipe (78). The bypass pipe (95) is provided with a check valve (CV16). The bypass pipe (95) is configured such that the refrigerant flowing through the suction pipe (81) bypasses the booster compressor (86) and flows to the discharge pipe (78) when the booster compressor (86) fails. Yes.

<controller>
The controller (100) has the detection values of the sensors (18,19a, 19b, 48a, 48b, 48c, ...), the high pressure switch (39a, 39b, 39c), and the operating ammeter (46). Entered. Based on these detected values, the controller (100) controls the drive of each compressor (14a, 14b, 14c) and each fan (23, 55, 65a, 65b), and various valves (5-7, 31 to 33, 53,...), The operation of the refrigeration system (1) is controlled while adjusting the opening degree and adjusting the operation frequency of the inverter.

  The controller (100) constitutes a control means for opening and closing the second and third on-off valves (6, 7). Specifically, the controller (100) includes a first determination unit (first overload determination unit) (101) and a second determination unit (second overload determination unit) (102). These determination units (101, 102) determine whether or not the compression mechanism (14) is in an overload operation state.

  The discharge pressure sensor (18) is electrically connected to the first determination unit (101) through a signal line, and the detection value of the discharge pressure sensor (18) is transmitted through the signal line to the first determination unit. (101). The first determination unit (101) determines that the compression mechanism (14) is in an overload operation state if the detection value input from the discharge pressure sensor (18) is equal to or greater than a predetermined value. It is configured.

  On the other hand, the operating ammeter (46) is electrically connected to the second determination unit (102) via a signal line, and the detected value of the operating ammeter (46) is transmitted via the signal line to the second determination unit (102). The determination unit (102) is configured to be input. The second determination unit (102) is configured to determine that the compression mechanism (14) is in an overload operation state if the detection value is greater than or equal to the detection value input from the operation ammeter (46). ing.

  When at least one of the determination units (101, 102) determines that the compression mechanism (14) is in an overload operation state, the controller (100) indicates that the third four-way switching valve (33) is the second one. If it is in a state, the second and third on-off valves (6, 7) are closed. If the third four-way selector valve (33) is in the first state, the third on-off valve (7) is closed.

-Driving action-
Next, the operation of the refrigeration apparatus (1) will be described. In this refrigeration system (1), the refrigerator is cooled by the refrigeration unit (60a), the refrigerator is cooled by the air conditioning unit (50) while the refrigerator is cooled by the refrigeration unit (60b), and the refrigeration unit (60a) The air conditioner unit (50) heats the room while the refrigerator is cooled and the freezer is cooled by the refrigeration unit (60b). First, the operation of the cooling / cooling operation will be described.

  In this cooling / cooling operation, the second compressor (14b) is used in the first usage system circuit (4a) for refrigeration and freezing, and the second compressor (14b) is used in the second usage system for air conditioning. Switching to the second mode used for the circuit (4b) is possible.

  In the cooling operation of the first mode, all the four-way switching valves (31, 32, 33) are set to the first state. Further, the heat source expansion valve (66) is set to a fully closed state. Furthermore, the opening degrees of the indoor expansion valve (53), the refrigeration expansion valve (63a), and the freezing expansion valve (63b) are adjusted as appropriate. Each fan (23, 55, 65a, 65b), the three compressors (14a, 14b, 14c), and the booster compressor (86) are in operation.

  The high-pressure refrigerant compressed by the first, second, and third compressors (14a, 14b, 14c) is discharged through the discharge pipes (56a, 56b, 56c), and the oil separators (37a, 37b). 37c). In each oil separator (37a, 37b, 37c), the refrigeration oil is separated from the high-pressure refrigerant. The separated refrigerating machine oil is once stored in each oil separator (37a, 37b, 37c), and then passed through each oil return branch pipe (43a, 43b, 43c) and the oil return main pipe (42). It flows into the injection pipe (30d). The refrigerating machine oil that has flowed into the second injection pipe (30d) is divided and after passing through the branch injection pipes (30a, 30b, 30c), the compressors (14a, 14b, 14c) is inhaled.

  On the other hand, the high-pressure refrigerant from which the refrigerating machine oil has been separated flows out of the oil separators (37a, 37b, 37c), and then joins in the discharge junction pipe (21). The high-pressure refrigerant joined in the discharge junction pipe (21) flows into the heat source heat exchanger (15) through the first and second four-way switching valves (31, 32). In the heat source heat exchanger (15), the high-pressure refrigerant condenses by exchanging heat with outdoor air. The condensed refrigerant flows into the receiver (16) through the first pipe (24). The high-pressure refrigerant that has flowed into the receiver (16) is temporarily stored in the receiver (16) and then flows out of the receiver (16). The high-pressure refrigerant that has flowed out of the receiver (16) flows into the second pipe (25) and is divided. One of the high-pressure refrigerant flows into the first liquid side shut-off valve (111) and the other is the supercooling heat exchanger (17 ). The high-pressure refrigerant that has flowed toward the first liquid side closing valve (111) passes through the first liquid side closing valve (111) and then flows into the first liquid side communication pipe (2a).

  On the other hand, the high-pressure refrigerant flowing toward the supercooling heat exchanger (17) is further divided after passing through the high-pressure side flow path (17a) of the supercooling heat exchanger (17). It flows to the second liquid side closing valve (112), and the other flows to the first injection pipe (30e). The high-pressure refrigerant that has flowed toward the second liquid-side closing valve (112) passes through the second liquid-side closing valve (112) and then flows into the second liquid-side connecting pipe (2b).

  The high-pressure refrigerant that has flowed toward the first injection pipe (30e) is reduced to a predetermined pressure by the supercooling pressure reducing valve (67) to become an intermediate pressure refrigerant, and then the supercooling heat exchanger (17). Flows into the decompression side flow path (17b). In the supercooling heat exchanger (17), the intermediate-pressure refrigerant exchanges heat with the high-pressure refrigerant flowing through the high-pressure channel (17a). As a result, the high-pressure refrigerant is cooled to increase the degree of supercooling, while the intermediate-pressure refrigerant is heated to become a gas refrigerant. The gas refrigerant flows out of the supercooling heat exchanger (17) and then splits into the first, second, and third branch injection pipes (30a, 30b, 30c) via the second injection pipe (30d). . The intermediate pressure refrigerant flowing into each branch injection pipe (30a, 30b, 30c) passes through each on-off valve (5, 6, 7) and then compressed at the intermediate pressure position in each compressor (14a, 14b, 14c). It is injected into the room.

  Here, when the compression mechanism (14) enters an overload operation state due to an increase in outside air temperature or the like, the third open / close valve (7) is closed by the controller (100). Thereby, the intermediate pressure refrigerant is not injected into the third compressor (14c). Then, the amount of high-pressure refrigerant discharged from the third compressor (14c) is reduced by the amount that the intermediate-pressure refrigerant is not injected. As a result, the overload operation state of the compression mechanism (14) is avoided.

  The high-pressure refrigerant that has flowed into the first liquid side connecting pipe (2a) passes through the first liquid side connecting pipe (2a) and flows into the air conditioning circuit (52). The high-pressure refrigerant that has flowed into the second liquid side connection pipe (2b) is divided by the second liquid side connection pipe (2b) and flows into the refrigeration circuit (61a) and the refrigeration circuit (61b).

  The high-pressure refrigerant flowing into the air conditioning circuit (52) is depressurized by the indoor expansion valve (53) and then flows to the indoor heat exchanger (54). In the indoor heat exchanger (54), the refrigerant absorbs heat from the room air and evaporates. As a result, the indoor air is cooled and the store is cooled. The refrigerant evaporated in the indoor heat exchanger (54) passes through the first gas side communication pipe (3a), the first four-way switching valve (31), and the second four-way switching valve (32) in this order, 3 is sucked into the third compressor (14c) from the suction pipe (57c).

  The high-pressure refrigerant flowing into the refrigeration circuit (61a) is depressurized by the refrigeration expansion valve (63a) and then flows to the refrigeration heat exchanger (64a). In the refrigeration heat exchanger (64a), the refrigerant absorbs heat from the internal air and evaporates. As a result, the refrigerator is cooled, and for example, the internal temperature is maintained at 5 ° C. The refrigerant evaporated in the refrigeration heat exchanger (64a) flows to the second gas side communication pipe (3b).

  The high-pressure refrigerant flowing into the refrigeration circuit (61b) is depressurized by the refrigeration expansion valve (63b), and then flows to the refrigeration heat exchanger (64b). In the refrigeration heat exchanger (64b), the refrigerant absorbs heat from the internal air and evaporates. As a result, the inside of the freezer is cooled and, for example, the inside temperature is maintained at −10 ° C. The refrigerant evaporated in the refrigeration heat exchanger (64b) is compressed by the booster compressor (86), then flows into the second gas side communication pipe (3b), and merges with the refrigerant from the refrigeration circuit (61a). . The merged refrigerant flows into the first suction pipe (57a), a part of the refrigerant is sucked into the first compressor (14a), and the rest is passed through the second suction pipe (57b) to the second compressor (14b). Inhaled.

  The refrigerant sucked into each compressor (14a, 14b, 14c) is intermediate pressure refrigerant injected from each intermediate port while being compressed in the compression chamber of each compressor (14a, 14b, 14c). Are further compressed to become high-pressure refrigerant and discharged again from the compressors (14a, 14b, 14c). As the refrigerant circulates in this way, the first mode cooling / cooling operation is performed.

  The cooling and cooling operation in the second mode is the same except that the third four-way switching valve (33) is switched to the second state in the first mode. In the second mode cooling / cooling operation, the refrigerant evaporated in the indoor heat exchanger (54) flows from the first gas side communication pipe (3a) to the first four-way switching valve (31) and the second four-way switching valve. It flows to the third suction pipe (57c) via (32). Part of the refrigerant flowing into the third suction pipe (57c) is sucked into the third compressor (14c), and the rest passes through the third four-way switching valve (33) and passes through the second suction pipe (57b). 2 Sucked into the compressor (14b).

  Further, when only the first four-way switching valve (31) is switched to the second state from the cooling / cooling operation state, the heating / cooling operation can be performed. In this case, when the heat source expansion valve (66) is fully closed, the first heating / cooling operation is performed. When the opening adjustment is performed as necessary without fully closing the heat source expansion valve (66), the second heating / cooling operation is performed. It becomes heating and cooling operation.

  Further, the first four-way switching valve (31) and the second four-way switching valve (32) are switched to the second state, and the opening adjustment is performed as necessary without fully closing the heat source expansion valve (66). If it does, it will become the 3rd heating cooling operation.

  In the first heating / cooling operation, the indoor heat exchanger (54) provided in the air conditioning circuit (52) serves as a condenser, and is provided in the refrigeration heat exchanger (64b) and the refrigeration circuit (61a). The refrigerated heat exchanger (53b) serves as an evaporator. In this operation, heating in the store and cooling of the refrigerator and the freezer can be performed simultaneously without using the heat source heat exchanger (15).

  In the second heating / cooling operation, the indoor heat exchanger (54) serves as a condenser, and the heat source heat exchanger (15), the refrigeration heat exchanger (53b), and the refrigeration heat exchanger (64b) serve as an evaporator. Become. In this operation, unlike the first heating / cooling operation, heating in the store and cooling of the refrigerator and the freezer can be performed simultaneously while using the heat source heat exchanger (15) as an evaporator.

  In the third heating / cooling operation, the indoor heat exchanger (54) and the heat source heat exchanger (15) serve as a condenser, and the refrigeration heat exchanger (64b) and the refrigeration heat exchanger (53b) evaporate. It becomes a vessel. In this operation, heating in the store and cooling of the refrigerator and freezer can be performed simultaneously while using the heat source heat exchanger (15) as a condenser.

-Effect of the embodiment-
In this embodiment, when the controller (100) determines that the compression mechanism (14) is in an overload operation state, the compressor (14b, 14c) connected to the second utilization system circuit (4b) The corresponding on-off valve (6, 7) can be closed to prevent the intermediate pressure refrigerant from being injected into the compressor (14b, 14c). Thereby, the discharge amount of the refrigerant in the compression mechanism (14) can be reduced without reducing the operating capacity of the first compressor (14a) connected to the first utilization system circuit (4a). An overload operation state of the compression mechanism (14) can be avoided.

  Further, according to the present embodiment, it is possible to determine whether or not the compression mechanism (14) is in an overload operation state based on the discharge pressure and the operating current value of the compression mechanism (14). Thereby, the overload operation state of the compression mechanism (14) can be more reliably determined, and the overload operation state can be avoided.

  Further, according to the present embodiment, by providing the supercooling heat exchanger (17), the refrigerant depressurized by the supercooling pressure reducing valve (29) is converted into a high-pressure refrigerant flowing through the refrigerant circuit (4). After heat exchange, it can be injected into each compression chamber. Thereby, compared with the case where the said supercooling heat exchanger (17) is not provided, it can inject into several compressors (14a, 14b, 14c), improving the COP of a freezing apparatus (1).

  According to the present embodiment, the refrigeration oil separated from the refrigerant discharged by the oil separator (37a, 37b, 37c) is passed through the injection circuit (40) in each compressor (14a, 14b, 14c). It can be returned to the compression chamber at the intermediate pressure position.

<< Other Embodiments >>
About the said embodiment, it is good also as the following structures.

  In this embodiment, in order to avoid the overload operation state of the compression mechanism (14), the on-off valve (5, 6) is used as a flow rate control means for adjusting the injection amount of the intermediate pressure refrigerant in each compressor (14b, 14c). 7) is used, but the present invention is not limited to this. For example, a flow control valve may be used. In this case, the valve opening degree of the flow rate adjusting valve may be adjusted so that the discharge pressure or the operating current value of the compression mechanism (14) is smaller than the predetermined value.

  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 including a refrigerant circuit in which a plurality of compressors and a plurality of usage-side heat exchangers are connected to perform a refrigeration cycle.

It is a refrigerant circuit figure of the refrigerating device concerning the embodiment of the present invention.

Explanation of symbols

1 Refrigeration equipment
4 Refrigerant circuit
4a First use system circuit
4b Second utilization system circuit
5,6,7 1st, 2nd, 3rd on-off valve (flow rate adjusting means)
10 Heat source unit (heat source side unit)
14a First compressor (variable capacity compressor)
14b, 14c Second and third compressors (fixed capacity compressors)
17 Supercooling heat exchanger
18 Discharge pressure sensor (pressure detection means)
30 Injection circuit
37a, 37b, 37c 1st, 2nd, 3rd oil separator
40 Oil return circuit
46 Operating ammeter (Operating current detection means)
50 Air conditioning unit (second usage side unit)
53 Indoor expansion valve
54 Indoor heat exchanger (second-use-side heat exchanger)
60a Refrigeration unit (first user side unit)
60b Refrigeration unit (first user side unit)
63a Refrigeration expansion valve
63b Refrigeration expansion valve
64a Heat exchanger for refrigeration (first use side heat exchanger)
64b Refrigeration heat exchanger (first use side heat exchanger)
67 Pressure reducing valve for supercooling (pressure reducing means)
100 controller (control means)

Claims (6)

A compression mechanism (14) composed of a variable capacity compressor (14a) and a fixed capacity compressor (14b, 14c), and a heat source side heat exchanger (15) connected to the discharge side of the compression mechanism (14) A heat source side unit (10) having, a first usage side unit (60a, 60b) having a first usage side heat exchanger (64a, 64b), and a second usage having a second usage side heat exchanger (54). Side unit (50),
A first usage side unit (60a, 60b) and a second usage side unit (50) are connected to the heat source side unit (10), and the first capacity side compressor (14a) is connected to the first side. 1 use side heat exchangers (64a, 64b) are connected, and the second use side heat exchanger (54) is connected to the suction side of the fixed capacity compressors (14b, 14c) so that the vapor compression refrigeration A refrigeration system comprising a refrigerant circuit (4) for performing a cycle,
The branch pipe (30e) branched from the high-pressure line (25) through which the refrigerant that passed through the heat source side heat exchanger (15) of the refrigerant circuit (4) flows, and the pressure reducing means (67) provided in the branch pipe (30e) An injection circuit (30) for connecting the branch pipe (30e) and the intermediate port of the fixed capacity compressor (14b, 14c),
A flow rate adjusting means (6, 7) provided between the pressure reducing means (67) in the injection circuit (30) and an intermediate port of the fixed capacity compressor (14b, 14c);
A refrigeration apparatus comprising: control means (100) for reducing the opening degree of the flow rate adjusting means (6, 7) when the compression mechanism (14) is determined to be in an overload operation state. In claim 1,
The flow rate adjusting means (6, 7) is composed of an openable / closable open / close valve (6, 7).
The refrigeration apparatus, wherein the control means (100) is configured to close the on-off valve (6, 7) when it is determined that the compression mechanism (14) is in an overload operation state. In claim 1 or 2,
The control means (100) has pressure detection means (18) for detecting the discharge pressure of the compression mechanism (14), and when the detected value of the pressure detection means (18) becomes a predetermined value or more, the compression mechanism ( A refrigeration apparatus comprising a first overload determination unit (101) that determines that 14) is in an overload operation state. In any one of Claims 1-3,
The control means (100) includes a second overload determination unit (102) that determines whether or not the compression mechanism (14) is in an overload operation state.
The second overload determination unit (102) has operating current detection means (46) for detecting an operating current value of the compression mechanism (14), and the detected value of the operating current detection means (46) is a predetermined value. When it becomes above, it is comprised so that it may determine with the said compression mechanism (14) being in an overload operation state, The freezing apparatus characterized by the above-mentioned. In any one of Claims 1-4,
A supercooling heat exchanger (17) having a decompression side passage (17b) through which the refrigerant decompressed by the decompression means (67) flows and a high pressure side passage (17a) through which the high-pressure refrigerant in the refrigerant circuit (4) flows. With
The decompression side flow path (17b) is connected to the branch pipe (30e) of the injection circuit (30), and the high pressure side flow path (17a) is connected to the high pressure line (25) of the refrigerant circuit (4). A refrigeration apparatus characterized by comprising: In any one of claims 1 to 5,
Oil separators (37a, 37b) provided in the discharge pipes (56a, 56b, 56c) of the compressors (14a, 14b, 14c) to separate the refrigeration oil from the refrigerant discharged from the compressors (14a, 14b, 14c) 37c) and an oil return pipe (43a, 43b, 43c) connected to the oil separator (37a, 37b, 37c), one end side of which is connected to the oil return pipe (43a, 43b, 43c) The other end is connected to the branch pipe (42) branched from the injection circuit (30), and the refrigeration oil is returned from the oil return pipe (43a, 43b, 43c) to each compressor (14a, 14b, 14c). A refrigeration apparatus comprising an oil return circuit (40).

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