JP2007298188A - Refrigeration equipment - Google Patents

Abstract

In a refrigeration apparatus including a low-stage compressor and a high-stage compressor and capable of a two-stage compression refrigeration cycle operation, energy saving is improved when a cooling operation is started.
A high-stage compressor (41) is started at the start of a cooling operation. As a result, the single-stage compression refrigeration cycle operation is performed in the refrigerant circuit (20). When the temperature in the refrigerator becomes equal to or lower than a predetermined temperature by the single-stage compression refrigeration cycle operation, the low-stage compressor (101) is started. As a result, in the refrigerant circuit (20), a two-stage compression refrigeration cycle is performed, and the interior is cooled to a lower temperature.
[Selection] Figure 6

Description

  The present invention relates to a refrigeration apparatus including a refrigerant circuit having a low stage compressor and a high stage compressor, and particularly relates to energy saving measures at the start of cooling operation of the refrigeration apparatus.

  2. Description of the Related Art Conventionally, refrigeration apparatuses that cool the interior of a refrigerator or a freezer that stores food or the like have been widely used for business use or home use.

  For example, Patent Document 1 discloses a refrigeration apparatus that cools the inside of a freezer of a convenience store. A low stage compressor, a high stage compressor, an expansion valve, a heat source side exchanger, and a use side heat exchanger are connected to the refrigerant circuit of the refrigeration apparatus. The heat source side heat exchanger is disposed outside the room, and the use side heat exchanger is installed in the freezer.

  In the cooling operation in which the interior is cooled by the use side heat exchanger, a two-stage compression refrigeration cycle is performed in the refrigerant circuit. Specifically, in this cooling operation, the high stage compressor and the low stage compressor are in operation. The refrigerant compressed by the high stage compressor flows through the heat source side heat exchanger. In the heat source side heat exchanger, the refrigerant dissipates heat to the outdoor air and condenses. The condensed refrigerant is reduced in pressure when passing through the expansion valve and flows through the use side heat exchanger. In the use side heat exchanger, the refrigerant absorbs heat from the internal air and evaporates. As a result, the inside of the freezer is cooled. The refrigerant after evaporation is compressed by a low stage compressor and then further compressed by a high stage compressor.

As described above, in the refrigeration apparatus disclosed in Patent Document 1, the refrigerant is compressed in two stages by the low-stage compressor and the high-stage compressor, so that the refrigerant is compressed by a single compressor (so-called simple unit). Compared with the stage compression refrigeration cycle operation), the height difference of the refrigeration cycle is increased. As a result, in this refrigeration apparatus, the evaporation temperature of the refrigerant flowing through the use side heat exchanger can be lowered, and the interior of the refrigerator can be cooled to an extremely low temperature.
JP 2002-228297 A

  By the way, immediately before starting the cooling operation with the refrigeration apparatus as described above, for example, immediately after the stored item is carried into the warehouse, the interior temperature may be a relatively high temperature (for example, 10 ° C.). is there. On the other hand, in the above-described two-stage compression refrigeration cycle operation, the refrigerant is evaporated at a relatively low temperature (for example, −30 ° C.) to cool the inside of the cabinet, so to speak, a refrigeration cycle suitable for cooling in the cabinet in a low temperature region. It is. Therefore, if the two-stage compression refrigeration cycle operation is performed by operating both the low-stage compressor and the high-stage compressor from the condition that the internal temperature is high in this way, the power of the two compressors is required. Nevertheless, the interior cannot be cooled efficiently. Therefore, this type of refrigeration apparatus has a problem that it causes an increase in COP (coefficient of performance) from the start of the cooling operation in the warehouse until the interior is sufficiently cooled.

  The present invention has been made in view of such points, and an object of the present invention is to provide a refrigeration apparatus that includes a low-stage compressor and a high-stage compressor and is capable of two-stage compression refrigeration cycle operation. It is to improve energy saving.

  1st invention is equipped with the refrigerant circuit (20) to which the low stage compressor (101) and the high stage compressor (41) were connected, and performs the refrigerating cycle in the said refrigerant circuit (20), and cools the inside of a store | warehouse | chamber A refrigeration system is assumed. The refrigerant circuit (20) of the refrigeration apparatus includes a single-stage compression refrigeration cycle operation that operates one of the low-stage compressor (101) and the high-stage compressor (41), a low-stage compressor (101), It is configured to be capable of two-stage compression refrigeration cycle operation that operates both the high-stage compressor (41), and when starting the cooling in the warehouse, only one of the compressors (41, 101) is activated and the refrigerant When the single-stage compression refrigeration cycle operation is performed in the circuit (20), and the index indicating the temperature in the refrigerator drops to a predetermined value after the start of the single-stage compression refrigeration cycle operation, the other compressor (101, 41) also It is characterized by comprising start control means (201) for starting and performing a two-stage compression refrigeration cycle operation in the refrigerant circuit (20).

  In the first invention, the refrigeration cycle is performed in the refrigerant circuit (20) to which the low stage compressor (101) and the high stage compressor (41) are connected. As a result, the refrigerant evaporates in the warehouse and the air in the warehouse is cooled. Further, the refrigeration apparatus is provided with an activation control means (201). The start control means (201) controls the start of the low-stage compressor (101) and the high-stage compressor (41) during the period from the start of cooling the inside of the storage with the refrigeration apparatus until the inside of the storage is sufficiently cooled. Do.

  Specifically, in the refrigeration apparatus of the present invention, when starting the cooling of the interior, the start-up control means (201) has only one of the low-stage compressor (101) and the high-stage compressor (41). Start and leave the other compressor stopped. As a result, in the refrigerant circuit (20), the refrigerant is compressed by only one compressor, and the single-stage compression refrigeration cycle operation is performed. As described above, in the refrigeration apparatus of the present invention, only one of the compressors is operated at the start of the cooling operation, so that the power of the compressor can be reduced as compared with the case where both the compressors (41, 101) are operated. . On the other hand, immediately after starting the cooling of the interior, the interior temperature is relatively high. For this reason, even in the single-stage compression refrigeration cycle operation in which the refrigerant evaporation temperature is relatively high, the internal temperature becomes sufficiently low.

  On the other hand, in the single-stage compression refrigeration cycle operation where the evaporation temperature is relatively high, the internal temperature cannot be lowered to a desired low temperature region. For this reason, the start control means (201) of the present invention starts the compressor that has been in the stopped state when it is cooled to a certain extent and the index indicating the temperature in the store has decreased to a predetermined value. As a result, in the refrigerant circuit (20), the refrigerant is compressed by both the compressors (41, 101), and the two-stage compression refrigeration cycle operation is performed. When the two-stage compression refrigeration cycle operation is performed, the evaporation temperature of the refrigerant also decreases, so that the internal temperature can be further decreased to a desired temperature.

  The second invention is characterized in that, in the first invention, the start control means (201) starts only the high stage compressor (41) in the single stage compression refrigeration cycle operation.

  In the refrigeration apparatus of the second invention, when the cooling operation is started, only the high stage compressor (41) is activated and the low stage compressor (101) remains in the stopped state. For this reason, in a refrigerant circuit (20), a refrigerant | coolant is compressed only by a high stage compressor (41), and single stage compression refrigeration cycle operation | movement is performed. As a result, the internal temperature gradually decreases.

  When the index indicating the temperature in the refrigerator is lowered to a predetermined value by the single-stage compression refrigeration cycle operation, the low-stage compressor (101) is started. For this reason, in the refrigerant circuit (20), the refrigerant compressed by the low stage compressor (101) is further compressed by the high stage compressor (41), and the two-stage compression refrigeration cycle operation is performed. As a result, the internal temperature is cooled to a lower temperature.

  According to a third invention, in the second invention, the refrigerant circuit (20) is connected to the low-stage compressor (101, 121) and the interior of the heat source side circuit (40) to which the high-stage compressor (41) is connected. A plurality of use side circuits (50, 60) to which cooling heat exchangers (83, 93) for cooling are respectively connected in parallel, and the start-up control means (201) is a single-stage compression refrigeration. Whether or not to start each low-stage compressor (101, 121) after the start of the cycle operation is determined based on the cooling heat exchanger (83, 83) of the use side circuit (50, 60) provided with the low-stage compressor (101, 121). It is performed based on the index which shows the temperature in the warehouse cooled in 93).

  In the refrigeration apparatus of the third invention, a plurality of use side circuits (50, 60) are connected in parallel to the heat source side circuit (40) to constitute the refrigerant circuit (20), while each use side circuit ( 50, 60) are provided with cooling heat exchangers (83, 93) and low-stage compressors (101, 121), respectively. That is, the refrigeration apparatus of the present invention constitutes a so-called multi-type refrigeration apparatus.

  When the inside of each warehouse is started to be cooled by the refrigeration apparatus of the present invention, only the high stage compressor (41) is activated and the low stage compressors (101, 121) remain in a stopped state. As a result, in the refrigerant circuit (20), the refrigerant compressed by the high-stage compressor (41) is diverted from the heat source side circuit (40) to each use side circuit (50, 60), and the refrigerant after diversion is used for each use. It is sent to the cooling heat exchanger (83, 93) of the side circuit (50, 60). In each use side circuit (50, 60), the refrigerant evaporates and the inside of the cabinet is cooled. The refrigerant evaporated in each cooling heat exchanger (83, 93) joins in the heat source side circuit (40) and is compressed again in the high stage compressor (41). As described above, in the refrigeration apparatus of the present invention, the single-stage compression refrigeration cycle operation is performed in each of the usage-side circuits (50, 60) when starting the cooling of each warehouse. As a result, the interior of each compartment is cooled at the same time, and the temperature in each compartment is gradually lowered.

  After the start of this single-stage compression refrigeration cycle operation, the start control means (201) individually determines for each user circuit (50, 60) whether the index indicating the temperature in each compartment has dropped to a predetermined value, It is determined whether or not to start each low-stage compressor (101, 121). Specifically, when the index indicating the temperature in the refrigerator cooled by, for example, the first cooling heat exchanger (83) is lowered to a predetermined value by the above-described single-stage compression refrigeration cycle operation, the activation control means (201) Then, the first low-stage compressor (101) corresponding to the first cooling heat exchanger (83) is started. As a result, a two-stage compression refrigeration cycle operation is performed in the first usage side circuit (50) provided with the first cooling heat exchanger (83). For this reason, the refrigerant | coolant evaporation temperature which flows through a 1st cooling heat exchanger (83) falls, and the temperature in this store | warehouse | chamber further falls. Similarly, when the index indicating the temperature in the refrigerator cooled by, for example, the second cooling heat exchanger (93) is lowered to a predetermined value by the single-stage compression refrigeration cycle operation, the start control means (201) The second low stage compressor (121) corresponding to the cooling heat exchanger (93) is started. As a result, in the second usage side circuit (60) provided with the second cooling heat exchanger (93), the two-stage compression refrigeration cycle operation is performed. For this reason, the refrigerant | coolant evaporation temperature which flows through a 2nd cooling heat exchanger (93) falls, and the temperature in this store | warehouse | chamber further falls.

  According to a fourth invention, in any one of the first to third inventions, the activation control means (201) includes an internal air temperature, a refrigerant evaporation temperature, and a refrigerant evaporation pressure as an index indicating the internal temperature. At least one is used.

  In the fourth invention, as an index for determining whether or not the internal temperature has been cooled to a predetermined temperature by the single-stage compression refrigeration cycle operation, at least one of the internal air temperature, the refrigerant evaporation temperature, and the refrigerant evaporation pressure is used. Two indicators are used. That is, the activation control means (201) performs a transition determination from the single-stage compression refrigeration cycle operation to the two-stage compression refrigeration cycle operation based on these indices.

  According to the present invention, the single-stage compression refrigeration cycle operation is performed at the start of the cooling operation for cooling the interior of the refrigerator. For this reason, at the start of the cooling operation, the power of the compressor can be reduced, and it is possible to cool down to a certain temperature inside the warehouse that was at a relatively high temperature. Therefore, in the refrigeration apparatus of the present invention, it is possible to improve the energy saving performance when starting the cooling operation.

  Further, in the present invention, the two-stage compression refrigeration cycle operation is performed when the inside temperature is cooled to a certain temperature by the single-stage compression refrigeration cycle operation. That is, in the present invention, the two-stage compression refrigeration cycle operation is performed only when the internal temperature reaches a low temperature region suitable for the two-stage compression refrigeration cycle. Therefore, according to the refrigeration apparatus of the present invention, it is possible to reliably cool the interior to a desired temperature while ensuring energy saving at the start of the cooling operation.

  In the second invention, at the start of the cooling operation, only the high-stage compressor (41) is first operated to perform the single-stage compression refrigeration cycle operation, and then it is determined that the internal temperature has cooled to some extent. The low-stage compressor (101) is operated to perform the two-stage compression refrigeration cycle operation. For this reason, in the single-stage compression refrigeration cycle operation, the power of the compressor can be reduced by the amount of stopping the low-stage compressor (101).

  In the third invention, in the so-called multi-type refrigeration apparatus, the single stage compression refrigeration cycle operation is performed by operating the high stage compressor (41) of the heat source side circuit (40) at the start of the cooling operation. For this reason, according to the present invention, in the single-stage compression refrigeration cycle operation, it is possible to cool a plurality of interiors simultaneously while reducing the power of each low-stage compressor (101, 121).

  Further, in the present invention, after the single-stage compression refrigeration cycle operation, it is individually evaluated whether each chamber is cooled to a certain extent, and the use side circuit (50, 60) that has been determined to have cooled to a certain extent has been reduced. The stage compressors (101, 121) are started as appropriate. Therefore, according to the present invention, the two-stage compression refrigeration cycle operation corresponding to the degree of cooling in each warehouse can be performed individually in each use side circuit (50, 60). As a result, it is possible to reliably cool the interiors of the respective use side circuits (50, 60) to the desired temperatures while ensuring energy saving at the start of the cooling operation.

  In the fourth aspect of the invention, it is determined whether or not the inside has been cooled by the single-stage compression refrigeration cycle operation while viewing the inside air temperature, the refrigerant evaporation temperature, and the refrigerant evaporation pressure. For this reason, according to the present invention, it is possible to reliably perform the transition determination from the single-stage compression refrigeration cycle operation to the two-stage compression refrigeration cycle operation, and to ensure the energy saving and reliability of the refrigeration apparatus. Can do.

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

  The refrigeration apparatus (10) of this embodiment is installed in a convenience store or the like to cool a plurality of freezers.

  As shown in FIG. 1, the refrigeration apparatus (10) includes an outdoor unit (11), a first refrigeration showcase (12), a second refrigeration showcase (13), a first booster unit (14), and a second booster. Unit (15) is provided. The outdoor unit (11) is installed outdoors. On the other hand, the remaining units (12, 13, 14, 15) are all installed in a store such as a convenience store.

  The outdoor unit (11) has an outdoor circuit (40), the first refrigeration showcase (12) has a first refrigeration circuit (80), and the second refrigeration showcase (13) has a second refrigeration circuit (90). However, the first booster unit (14) is provided with a first booster circuit (100), and the second booster unit (15) is provided with a second booster circuit (120). In the refrigeration apparatus (10), a refrigerant circuit (20) that performs a vapor compression refrigeration cycle is configured by connecting these circuits (40, 80, 90, 100, 120) with pipes.

  The first refrigeration circuit (80) and the first booster circuit (100) are connected to each other in series to constitute a first usage side circuit (50). The second refrigeration circuit (90) and the second booster circuit (120) are connected to each other in series to constitute a second usage side circuit (60). The first usage side circuit (50) and the second usage side circuit (60) are respectively connected in parallel to the outdoor circuit (40).

  A first closing valve (21) and a second closing valve (22) are provided at the end of the outdoor circuit (40), and a third closing valve (23) is provided at the end of the first booster circuit (100). A fourth closing valve (24) is provided at each end of the booster circuit (120). One end of a liquid communication pipe (31) is connected to the first closing valve (21). The other end of the liquid communication pipe (31) is branched into two, one of which is connected to the end of the first refrigeration circuit (80) and the other is connected to the end of the second refrigeration circuit (90). Has been. One end of a gas communication pipe (32) is connected to the second closing valve (22). The other end of the gas communication pipe (32) is branched into two, one of which is connected to the third closing valve (23) and the other is connected to the fourth closing valve (24).

<Outdoor unit>
The outdoor circuit (40) of the outdoor unit (11) includes a high stage compressor (41), an outdoor heat exchanger (42), a receiver (43), a supercooling heat exchanger (44), a first outdoor expansion valve ( 45), a second outdoor expansion valve (46), and a four-way switching valve (47) are provided.

  The high-stage compressor (41) is a fully-enclosed and high-pressure dome-type scroll compressor, and constitutes a variable capacity compressor. That is, electric power is supplied to the high stage compressor (41) via the inverter. The capacity of the high stage compressor (41) can be changed by changing the rotation speed of the compressor motor by changing the output frequency of the inverter.

  One end of a first suction pipe (61) is connected to the suction side of the high stage compressor (41). The other end of the first suction pipe (61) is connected to the four-way switching valve (47). A first discharge pipe (62) is connected to the discharge side of the high stage compressor (41). The other end of the first discharge pipe (62) is connected to the four-way switching valve (47).

  The outdoor heat exchanger (42) is a cross fin type fin-and-tube heat exchanger, and constitutes a heat source side heat exchanger. An outdoor fan (48) is provided in the vicinity of the outdoor heat exchanger (42). In the outdoor heat exchanger (42), heat is exchanged between the outdoor air blown by the outdoor fan (48) and the refrigerant. One end of the outdoor heat exchanger (42) is connected to the four-way switching valve (47) via the fifth closing valve (25). The other end of the outdoor heat exchanger (42) is connected to the top of the receiver (43) via the first liquid pipe (71).

  The supercooling heat exchanger (44) includes a high-pressure channel (44a) and a low-pressure channel (44b), and exchanges heat between the refrigerants flowing through the channels (44a, 44b). The supercooling heat exchanger (44) is constituted by, for example, a plate heat exchanger.

  The inflow end of the high-pressure channel (44a) is connected to the bottom of the receiver (43). The outflow end of the high-pressure channel (44a) is connected to the first closing valve (21) via the second liquid pipe (72). On the other hand, the inflow end of the low-pressure channel (44b) is connected to the middle of the second liquid pipe (72) via the first branch pipe (73). The outflow end of the low-pressure channel (44b) is connected to the middle of the first suction pipe (61).

  One end of the second branch pipe (74) is connected to the second liquid pipe (72) between the connection portion of the first branch pipe (73) and the first closing valve (21). The other end of the second branch pipe (74) is connected between the outdoor heat exchanger (42) and the receiver (43) in the first liquid pipe (71).

  The first branch pipe (73) is provided with the first outdoor expansion valve (45). The first outdoor expansion valve (45) is an electronic expansion valve whose opening degree can be adjusted. One end of the third branch pipe (75) is connected to the first branch pipe (73) on the upstream side of the first outdoor expansion valve (45). The other end of the third branch pipe (75) is connected between the connection portion of the second branch pipe (74) in the first liquid pipe (71) and the outdoor heat exchanger (42). The third branch pipe (75) is provided with the second outdoor expansion valve (46). The second outdoor expansion valve (46) is an electronic expansion valve whose opening degree can be adjusted, and constitutes a heat source side expansion valve.

  The four-way switching valve (47) has a first port as the first discharge pipe (62), a second port as the first suction pipe (61), and a third port as the outdoor heat exchanger (42). In addition, the fourth port is connected to the second closing valve (22), respectively. The four-way switching valve (47) is in a first state (state indicated by a solid line in FIG. 1) 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. The first port and the fourth port can communicate with each other, and the second port and the third port can communicate with each other. The second state can be switched to the second state (shown by a broken line in FIG. 1).

  Various sensors and pressure switches are also provided in the outdoor circuit (40). Specifically, the first suction pipe (61) is provided with a first suction temperature sensor (151) and a first suction pressure sensor (152). The first discharge pipe (62) is provided with a first high pressure switch (153), a first discharge temperature sensor (154), and a first discharge pressure sensor (155). An outdoor temperature sensor (156) is provided in the vicinity of the outdoor fan (48). The second liquid pipe (72) is provided with a liquid temperature sensor (157).

  The outdoor circuit (40) is also provided with a plurality of check valves that allow the refrigerant to flow in one direction but prohibit the refrigerant from flowing in the opposite direction. Specifically, the first discharge pipe (62) has a check valve (CV-1), the first liquid pipe (71) has a check valve (CV-2), and the second liquid pipe (72). A check valve (CV-3) is provided in the second branch pipe (74), and a check valve (CV-4) is provided in the second branch pipe (74). These check valves (CV-1, CV-2, CV-3, CV-4) only allow refrigerant to flow in the direction of the arrow attached to the symbol indicating the check valve in FIG. It is configured.

<Frozen showcase>
In the first refrigeration circuit (80) of the first refrigeration showcase (12), in order from the liquid side end to the gas side end, the first drain pan heater (81), the first indoor expansion valve (82), and A first cooling heat exchanger (83) is provided.

  The said 1st drain pan heater (81) is comprised with the refrigerant | coolant piping arrange | positioned along the bottom face of the drain pan of the 1st cooling heat exchanger (83). The first drain pan heater (81) melts frost and ice blocks collected in the drain pan of the first cooling heat exchanger (83).

  The first indoor expansion valve (82) is an electronic expansion valve whose opening degree can be adjusted, and constitutes a use side expansion valve. The first cooling heat exchanger (83) is a cross fin type fin-and-tube heat exchanger, and constitutes a use side heat exchanger. A first internal fan (84) is provided in the vicinity of the first cooling heat exchanger (83). In the first cooling heat exchanger (83), heat is exchanged between the internal air blown by the first internal fan (84) and the refrigerant.

  The first refrigeration circuit (80) is provided with three temperature sensors. Specifically, the heat transfer tube of the first cooling heat exchanger (83) is provided with a first evaporation temperature sensor (161) for detecting the evaporation temperature of the refrigerant. Near the gas side end of the first refrigeration circuit (80), a first outlet temperature sensor (162) is provided for detecting the temperature of the refrigerant flowing out of the cooling heat exchanger (83). A first internal temperature sensor (163) for detecting the internal temperature is provided in the vicinity of the first internal fan (84).

  The second refrigeration circuit (90) of the second refrigeration showcase (13) has the same configuration as the first refrigeration circuit (80). That is, the second refrigeration circuit (90) includes a second drain pan heater (91), a second indoor expansion valve (92), and a second cooling heat exchanger (93), as in the first refrigeration circuit (80). A second internal fan (94) is provided. In addition, the second refrigeration circuit (90) includes a second evaporation temperature sensor (164), a second outlet temperature sensor (165), and a second internal temperature sensor (in the same manner as the first refrigeration circuit (80)). 166).

<Booster unit>
The first booster circuit (100) of the first booster unit (14) is connected to the gas side end of the first refrigeration circuit (80) via the first booster communication pipe (33). The first booster circuit (100) is provided with a first low-stage compressor (101).

  The first low-stage compressor (101) is a fully-enclosed and high-pressure dome-type scroll compressor, and constitutes a variable capacity compressor. Electric power is supplied to the first low-stage compressor (101) via an inverter. The capacity of the first low-stage compressor (101) can be changed by changing the rotation speed of the compressor motor by changing the output frequency of the inverter.

  One end of a second suction pipe (111) is connected to the suction side of the first low-stage compressor (101). The other end of the second suction pipe (111) is connected to the first booster communication pipe (33). The second suction pipe (111) is connected to a first liquid injection pipe (34) branched from the middle of the liquid communication pipe (31). The first liquid injection pipe (34) is provided with a first electric valve (102) whose opening degree can be adjusted. One end of a second discharge pipe (112) is connected to the discharge side of the first low-stage compressor (101). The other end of the second discharge pipe (112) is connected to the third closing valve (23).

  The first booster circuit (100) is also provided with a first oil discharge pipe (113) and a first bypass pipe (114).

  The first oil discharge pipe (113) has one end connected to the oil discharge port of the first low-stage compressor (101) and the other end connected to the second discharge pipe (112). The first oil discharge pipe (113) is provided with a solenoid valve (SV-1). The solenoid valve (SV-1) is opened when the refrigeration oil in the first low stage compressor (101) becomes excessive. As a result, the refrigeration oil flows into the outdoor circuit (40) through the first oil discharge pipe (117), and is supplied into the high stage compressor (41).

  The first bypass pipe (114) has one end connected to the second suction pipe (111) and the other end connected to the second discharge pipe (112). That is, the first bypass pipe (114) constitutes a bypass means that connects the suction side and the discharge side of the first low-stage compressor (101). The first bypass pipe (114) is provided with a solenoid valve (SV-2). Details of the opening / closing operation of the solenoid valve (SV-2) will be described later.

  The second suction pipe (111) is provided with a second suction temperature sensor (167) and a second suction pressure sensor (168). The second discharge pipe (112) is provided with a second high pressure switch (169), a second discharge temperature sensor (170), and a second discharge pressure sensor (171). In the first booster circuit (100), the second discharge pipe (112) is provided with a check valve (CV-5), and the first oil discharge pipe (113) is provided with a check valve (CV-6). ing.

  The second booster circuit (120) of the second booster unit (15) is connected to the gas side end of the second refrigeration circuit (90) via the second booster communication pipe (35). The second booster circuit (120) has the same configuration as the first booster circuit (100).

  That is, the second booster circuit (120) includes a second low-stage compressor (121), a third suction pipe (131), a third discharge pipe (132), a second liquid injection pipe (36), and a second oil. A discharge pipe (133) and a second bypass pipe (134) are provided. The second liquid injection pipe (36) is provided with a second motor operated valve (122), the second oil discharge pipe (133) is provided with a solenoid valve (SV-3), and the second bypass pipe (134) is provided with Has a solenoid valve (SV-4).

  The third suction pipe (131) is provided with a third suction temperature sensor (172) and a third suction pressure sensor (173). The third discharge pipe (132) is provided with a third high pressure switch (174), a third discharge temperature sensor (175), and a third discharge pressure sensor (176). In the second booster circuit (120), a check valve (CV-7) is provided in the third discharge pipe (132), and a check valve (CV-8) is provided in the second oil discharge pipe (133). ing.

<Configuration of controller>
The refrigeration apparatus (10) according to the present invention includes a controller (200). This controller (200) can mutually transmit between each sensor and each control device connected to the refrigerant circuit (20). Specifically, the controller (200) is configured to be able to receive detection signals from the sensors of the refrigerant circuit (20). The controller (200) includes compressors (41, 101, 121), expansion valves (45, 46, 82, 92), motor valves (102, 122), solenoid valves (SV-) connected to the refrigerant circuit (20). 1, SV-2,...) Can be controlled.

  Further, as a feature of the present invention, the controller (200) is provided with start control means (201) for performing start control of each compressor (41, 101, 121) at the start of the cooling operation for cooling the inside of the refrigerator with the refrigeration apparatus (10). It has been. Details of the control operation of the activation control means (201) will be described later.

-Driving action-
Below, the operation | movement operation | movement of the freezing apparatus (10) which concerns on this embodiment is demonstrated. The refrigeration system (10) can perform a cooling operation for cooling the interior of each refrigeration showcase (12, 13) and a defrost operation for melting frost attached to each cooling heat exchanger (83, 93). It has become.

<Cooling operation>
In the cooling operation of the refrigeration apparatus (10), the four-way switching valve (47) is set to the first state. Further, the second outdoor expansion valve (46) is fully closed, while the opening degree of the first outdoor expansion valve (45) is adjusted as appropriate. In the first refrigeration circuit (80), the opening degree of the first indoor expansion valve (82) is appropriately adjusted. In the second refrigeration circuit (90), the opening degree of the second indoor expansion valve (92) is appropriately adjusted.

  In this cooling operation, the refrigerant circuit (20) can be switched between a single-stage compression refrigeration cycle operation and a two-stage compression refrigeration cycle operation.

<< Single-stage compression refrigeration cycle operation >>
In the single-stage compression refrigeration cycle operation shown in FIG. 2, the high-stage compressor (41) is in an operating state, and the low-stage second and third variable capacity compressors (101, 121) are in a stopped state. In the first booster circuit (100), the solenoid valve (SV-2) is opened, and in the second booster circuit (120), the solenoid valve (SV-4) is opened.

  The refrigerant discharged from the high stage compressor (41) passes through the four-way switching valve (47) from the first discharge pipe (62) and flows through the outdoor heat exchanger (42). In the outdoor heat exchanger (42), the refrigerant dissipates heat to the outdoor air and condenses.

  The refrigerant condensed in the outdoor heat exchanger (42) is supplied to the second liquid pipe via the first liquid pipe (71), the receiver (43), and the high-pressure channel (44a) of the supercooling heat exchanger (44). Flows into (72). Part of the refrigerant flowing through the second liquid pipe (72) is diverted to the first branch pipe (73), and the rest is diverted to the liquid communication pipe (31).

  The refrigerant that has flowed out of the first branch pipe (73) passes through the first outdoor expansion valve (45) and is decompressed, and then flows through the low-pressure channel (44b) of the supercooling heat exchanger (44). In the supercooling heat exchanger (44), the high-pressure refrigerant flowing through the high-pressure channel (44a) and the low-pressure refrigerant flowing through the low-pressure channel (44b) exchange heat. As a result, the heat of the refrigerant flowing through the high-pressure channel (44a) is taken as the heat of evaporation of the refrigerant flowing through the low-pressure channel (44b). That is, in the supercooling heat exchanger (44), the refrigerant flowing through the high pressure side flow path (44a) is supercooled. The refrigerant evaporated in the low pressure side flow path (44b) of the supercooling heat exchanger (44) flows into the first suction pipe (61). On the other hand, the refrigerant that has flowed into the liquid communication pipe (31) is divided into the first refrigeration circuit (80) and the second refrigeration circuit (90).

  The refrigerant flowing into the first refrigeration circuit (80) flows through the first drain pan heater (81). The refrigerant flowing through the first drain pan heater (81) is cooled by releasing heat to frost and ice blocks collected in the drain pan. The refrigerant flowing out of the first drain pan heater (81) passes through the first cooling heat exchanger (83) after passing through the first indoor expansion valve (82) and being decompressed. In the first cooling heat exchanger (83), the refrigerant absorbs heat from the internal air and evaporates. As a result, the internal air of the first refrigeration showcase (12) is cooled.

  The refrigerant evaporated in the first cooling heat exchanger (83) flows into the first booster circuit (100) through the first booster communication pipe (33). This refrigerant flows into the gas communication pipe (32) via the first bypass pipe (114). That is, the refrigerant that has flowed into the first booster circuit (100) during the single-stage compression refrigeration cycle operation is sent to the outdoor circuit (40), bypassing the stopped first low-stage compressor (101).

  On the other hand, the refrigerant flowing into the second refrigeration circuit (90) flows through the second drain pan heater (91). The refrigerant flowing through the second drain pan heater (91) dissipates heat to the frost and ice blocks collected in the drain pan and is cooled. The refrigerant that has flowed out of the second drain pan heater (91) passes through the second cooling heat exchanger (93) after passing through the second indoor expansion valve (92) and being decompressed. In the second cooling heat exchanger (93), the refrigerant absorbs heat from the internal air and evaporates. As a result, the internal air of the second refrigeration showcase (13) is cooled.

  The refrigerant evaporated in the second cooling heat exchanger (93) flows into the second booster circuit (120) through the second booster communication pipe (35). This refrigerant flows into the gas communication pipe (32) via the second bypass pipe (134). That is, the refrigerant that has flowed into the second booster circuit (120) during the single-stage compression refrigeration cycle operation is sent to the outdoor circuit (40), bypassing the stopped second low-stage compressor (121).

  The refrigerant that merges in the gas communication pipe (32) and is sent to the outdoor circuit (40) passes through the four-way switching valve (47) and flows through the first suction pipe (61). This refrigerant is mixed with the refrigerant evaporated in the above-described supercooling heat exchanger (44) and sucked into the high stage compressor (41). The refrigerant is compressed to a high pressure by the high stage compressor (41) and then discharged from the first discharge pipe (62) again.

<< Two-stage compression refrigeration cycle operation >>
In the two-stage compression refrigeration cycle operation shown in FIG. 3, the high stage compressor (41) on the high stage side is in the operating state, and the first low stage compressor (101) and the second low stage on the low stage side are in operation. At least one or both of the compressors (121) are in operation. Hereinafter, the operation of the two-stage compression refrigeration cycle when the first low-stage compressor (101) and the second low-stage compressor (121) are operated together with the high-stage compressor (41) will be described.

  In this two-stage compression refrigeration cycle operation, the high-stage compressor (41) and the first and second low-stage compressors (101, 121) are in operation. In the first booster circuit (100), the solenoid valve (SV-2) is closed, and in the second booster circuit (120), the solenoid valve (SV-4) is closed.

  The refrigerant discharged from the high-stage compressor (41) flows through the same path as that of the single-stage compression refrigeration cycle described above, flows out from the outdoor circuit (40) to the liquid communication pipe (31), and then enters the first refrigeration circuit ( 80) and the second refrigeration circuit (90).

  The refrigerant flowing into the first refrigeration circuit (80) flows through the first drain pan heater (81) and is depressurized by the first indoor expansion valve (82), and then flows through the first cooling heat exchanger (83). In the first cooling heat exchanger (83), the refrigerant absorbs heat from the internal air and evaporates. As a result, the interior of the first frozen showcase (12) is cooled.

  The refrigerant evaporated in the first cooling heat exchanger (83) flows into the first booster circuit (100) through the first booster communication pipe (33). This refrigerant is sucked into the first low-stage compressor (101) via the second suction pipe (111) and compressed. The refrigerant compressed by the first low stage compressor (101) flows into the gas communication pipe (32) via the second discharge pipe (112).

  The refrigerant flowing into the second refrigeration circuit (90) flows through the second cooling heat exchanger (93) after flowing through the second drain pan heater (91) and decompressed by the second indoor expansion valve (92). In the second cooling heat exchanger (93), the refrigerant absorbs heat from the internal air and evaporates. As a result, the interior of the second refrigerated showcase (13) is cooled.

  The refrigerant evaporated in the second cooling heat exchanger (93) flows into the second booster circuit (120) through the second booster communication pipe (35). This refrigerant is sucked into the second low-stage compressor (121) via the third suction pipe (131) and compressed. The refrigerant compressed by the second low stage compressor (121) flows into the gas communication pipe (32) via the third discharge pipe (132).

  The refrigerant that has joined the gas communication pipe (32) and sent to the outdoor circuit (40) passes through the four-way switching valve (47) and flows through the first suction pipe (61), and the high-stage compressor (41). Is further compressed.

  As described above, in the two-stage compression refrigeration cycle operation, the refrigerant compressed by the low-stage compressor (101, 121) is further compressed by the high-stage compressor (41). For this reason, in the two-stage compression refrigeration cycle, the pressure difference of the refrigerant increases, and the pressure of the refrigerant evaporated in each cooling heat exchanger (83, 93) decreases. Therefore, in the two-stage compression refrigeration cycle, the refrigerant evaporation temperature in the cooling heat exchanger (83, 93) is lower than in the above-described single-stage compression refrigeration cycle, and the interior can be cooled to a lower temperature. it can.

<Defrost operation>
In the defrosting operation of the refrigeration apparatus (10), the first cooling heat exchanger (83) and the second cooling heat exchanger (93) are defrosted simultaneously.

  As shown in FIG. 4, in the outdoor circuit (40) during the defrost operation, the four-way selector valve (47) is set to the second state. Moreover, while the 1st outdoor expansion valve (45) will be in a fully closed state, the opening degree of a 2nd outdoor expansion valve (46) is adjusted suitably. In the first refrigeration circuit (80), the first indoor expansion valve (82) is fully opened. In the second refrigeration circuit (90), the second indoor expansion valve (92) is fully opened. In the first booster circuit (100), the solenoid valve (SV-2) is set to an open state. In the second booster circuit (120), the solenoid valve (SV-4) is set to an open state.

  In the defrost operation, the high stage compressor (41) is in the operating state, while the second and third variable capacity compressors (101, 121) are in the stopped state. As a result, in the refrigerant circuit (20), the outdoor heat exchanger (42) serves as an evaporator, and each cooling heat exchanger (83, 93) serves as a condenser, so-called reverse cycle defrosting is performed.

  The refrigerant discharged from the high stage compressor (41) passes through the four-way switching valve (47) and flows into the gas communication pipe (32). The refrigerant flowing into the gas communication pipe (32) is divided into the first booster circuit (100) and the second booster circuit (120).

  The refrigerant flowing into the first booster circuit (100) flows through the first bypass pipe (114) to the first booster communication pipe (33). That is, the refrigerant flowing into the first booster circuit (100) bypasses the stopped first low-stage compressor (101) and is sent to the first refrigeration circuit (80).

  The refrigerant that has flowed into the first refrigeration circuit (80) flows through the first cooling heat exchanger (83). In the first cooling heat exchanger (83), the frost on the surface is heated and melted from the inside, while the refrigerant is condensed by taking heat of fusion to the frost. The refrigerant condensed in the first cooling heat exchanger (83) passes through the first indoor expansion valve (82) in the fully opened state, then flows through the first drain pan heater (81), and flows into the liquid communication pipe (31). . In this case also, the heat of the refrigerant flowing through the first drain pan heater (81) is used for melting the frost and ice blocks collected in the drain pan.

  The refrigerant flowing into the second booster circuit (120) flows to the second booster communication pipe (35) via the second bypass pipe (134). That is, the refrigerant flowing into the second booster circuit (120) bypasses the stopped second low-stage compressor (121) and is sent to the second refrigeration circuit (90).

  The refrigerant flowing into the second refrigeration circuit (90) flows through the second cooling heat exchanger (93). In the second cooling heat exchanger (93), the frost on the surface is heated and melted from the inside, while the refrigerant is condensed by taking heat of fusion to the frost. The refrigerant condensed in the second cooling heat exchanger (93) passes through the fully opened second indoor expansion valve (92), then flows through the second drain pan heater (91), and flows into the liquid communication pipe (31). . Also in this case, the heat of the refrigerant flowing through the second drain pan heater (91) is used for melting frost and ice blocks collected in the drain pan.

  The refrigerant merged in the liquid communication pipe (31) sequentially passes through the second branch pipe (74), the receiver (43), and the high-pressure channel (44a) of the supercooling heat exchanger (44). The refrigerant further passes through the first branch pipe (73) and the third branch pipe (75), and is decompressed by the second outdoor expansion valve (46), and then flows through the outdoor heat exchanger (42). In the outdoor heat exchanger (42), the refrigerant absorbs heat from the outdoor air and evaporates. The refrigerant evaporated in the outdoor heat exchanger (42) passes through the four-way switching valve (47), flows through the first suction pipe (61), and is then sucked into the high stage compressor (41).

<Startup control operation>
Next, the control operation by the start control means (201) when starting the cooling operation in the refrigeration apparatus according to the present embodiment will be described.

  When the cooling operation described above is started, the temperature in the refrigerator is relatively high (for example, 10 ° C.) immediately after the stored items are brought into the refrigerator of each freezer showcase (12, 13). Sometimes. On the other hand, in the above-described two-stage compression refrigeration cycle operation, the refrigerant is evaporated at a relatively low temperature (for example, −30 ° C.) to cool the inside of the cabinet, so to speak, a refrigeration cycle suitable for cooling in the cabinet in a low temperature region. It is. Therefore, when the two-stage compression refrigeration cycle operation is performed by operating both the low-stage compressor and the high-stage compressor under the condition that the internal temperature is high in this way, the power of two or more compressors is required. Despite this, the inside of the cabinet may not be cooled sufficiently. Therefore, in the refrigeration apparatus (10) according to the present invention, the start control means (201) is provided so that the interior can be efficiently cooled even when the cooling operation is started from a state where the interior is at a relatively high temperature. The start-up control of the compressors (41, 101, 121) is performed.

  For example, if the cooling operation is started by the refrigeration apparatus (1) immediately after the stored items are brought into the freezer showcases (12, 13), the activation control means (201) is increased in step S1 of FIG. Start only the stage compressor (41). As a result, in the refrigerant circuit (20), the above-described single-stage compression refrigeration cycle operation shown in FIG. 2 is performed, and the interior of each refrigeration showcase (12, 13) is cooled.

  Next, the start control means (201) performs the start control operation from step S2 to step S7 for each of the first low stage compressor (101) and the second low stage compressor (121). Hereinafter, the activation control operation for the first low-stage compressor (101) will be described in detail.

  In step S2, it is determined whether or not the first low-stage compressor (101) satisfies the preparation conditions. The precondition is that the first low stage compressor (101) is not in an abnormal state, the second high pressure switch (169) is not operating, the overcurrent relay of the first low stage compressor (101) ( For example, whether the overcurrent relay is not operating or the guard timer of the first low-stage compressor (101) is up. And when these preparation conditions are satisfy | filled by step S2, it transfers to step S3.

  In step S3, a determination is made regarding the set temperature (target temperature) in the first refrigeration showcase (12) chamber set in the controller (200). Here, when this set temperature is higher than a predetermined temperature T1 (for example, −10 ° C.), for example, the interior can be sufficiently cooled to the set temperature only by the single-stage compression refrigeration cycle operation. The low stage compressor (101) remains stopped. On the other hand, when the set temperature is equal to or lower than T1, in the single-stage compression refrigeration cycle operation, the interior cannot be cooled to the set temperature, and in this case, the process proceeds to step S4.

  In step S4, the elapsed time from the start of the single-stage compression refrigeration cycle operation to the present is determined. Here, when this elapsed time has not passed a predetermined time t1 (for example, 1 minute), the first low-stage compressor (101) remains stopped, and when this elapsed time becomes t1 or more, the process proceeds to step S5. Transition.

  In step S5, when the elapsed time exceeds a predetermined time t2 (for example, 60 minutes), the start control means (201) forcibly starts the first low-stage compressor (101). On the other hand, if the elapsed time does not exceed t2, the process proceeds to step S6.

  In step S <b> 6, it is determined whether or not the temperature of the first refrigeration showcase (12) has been cooled to a certain temperature by the single-stage compression refrigeration cycle operation. In this determination, the internal temperature, the refrigerant evaporation temperature, and the refrigerant evaporation pressure are used as indices indicating the internal temperature. Specifically, the activation control means (201) is configured to detect, in the first usage side circuit (50), the internal temperature of the first freezer showcase (12) detected by the first internal temperature sensor (163), the first internal circuit (50), Each of the refrigerant evaporation temperature detected by the evaporation temperature sensor (161) and the refrigerant evaporation pressure detected by the second suction pressure sensor (168) are determined. Here, the internal temperature is a predetermined temperature T3 (for example, −10 ° C.) or lower, the refrigerant evaporation temperature is a predetermined temperature T4 (for example −20 ° C.) or lower, or the refrigerant evaporation pressure is a predetermined pressure. When the pressure is equal to or lower than P1 (saturation pressure corresponding to −20 ° C.), it is determined that the interior is cooled to some extent, and the process proceeds to step S7.

  In step S7, the start control means (201) starts the first low-stage compressor (101) and opens the solenoid valve (SV-2) of the first bypass pipe (114). As a result, as shown in FIG. 6, the two-stage compression refrigeration cycle operation is performed only by the first use side circuit (50), and the internal temperature of the first refrigeration showcase (12) is cooled to a lower temperature. .

  The start control means (201) performs the start control operation from step S2 to step S7 for the second low stage compressor (121) in parallel with the start control operation of the first low stage compressor (101) as described above. I do. That is, at this time, in step S6, the second refrigeration showcase detected by the second inside temperature sensor (166) to determine whether or not the inside of the second refrigeration showcase (13) has been cooled to a certain temperature. This is performed using the internal temperature of (13), the refrigerant evaporation temperature detected by the second evaporation temperature sensor (164), and the refrigerant evaporation pressure detected by the third suction pressure sensor (173). That is, the start control means (201) individually determines whether to start each low-stage compressor (101, 121) based on the index indicating the temperature in each store. When the condition of step S6 is satisfied for the second usage side circuit (60), the activation control means (201) activates the second low-stage compressor (121) and the second bypass pipe (134). Open the solenoid valve (SV-4). As a result, as shown in FIG. 3, a two-stage compression refrigeration cycle operation is performed in the second usage side circuit (60), and the interior of the second refrigeration showcase (13) is cooled to a lower temperature.

  In the above description, after starting the single-stage compression refrigeration cycle operation, the first low-stage compressor (101) is started first, and then the second low-stage compressor (121) is started. However, when the interior of the second refrigerated showcase (13) is cooled to a predetermined temperature before the first refrigerated showcase (12), the second lower stage than the first low stage compressor (101). The compressor (121) is started first, and the two-stage compression refrigeration cycle operation is performed in the second usage side circuit (60).

-Effect of the embodiment-
In the above embodiment, only the high stage compressor (41) is operated at the start of the cooling operation for cooling the inside of the refrigerator, and the single stage compression refrigeration cycle operation is performed. Therefore, at the start of the cooling operation, the interior of each warehouse can be cooled at the same time while reducing the power of the compressor by the amount that each low-stage compressor (101, 121) is stopped. On the other hand, since the internal temperature is relatively high at the start of the cooling operation, the operation is a single-stage compression refrigeration cycle operation in which the refrigerant evaporation temperature of each cooling heat exchanger (83, 93) is relatively high. However, the temperature in the storage can be lowered sufficiently. Therefore, according to the embodiment, it is possible to improve the energy saving performance at the time of starting the cooling operation.

  Further, in the above-described embodiment, it is individually determined whether or not the temperature in each cabinet has been cooled to a certain degree during the single-stage compression refrigeration cycle operation, and the low-side circuit (50, 60) that is determined to have cooled to a certain degree The stage compressors (101, 121) are started as appropriate. That is, in the above embodiment, the two-stage compression refrigeration cycle operation is performed for the first time when the temperature in each compartment reaches a low temperature region suitable for the two-stage compression refrigeration cycle. Therefore, according to the above embodiment, the interior of each refrigerated showcase (12, 13) can be reliably cooled to the set temperature while ensuring energy saving at the start of the cooling operation.

  Further, in the above-described embodiment, when the set temperature is higher than the predetermined temperature T1 in step S3 during the single-stage compression refrigeration cycle operation, the start of each low-stage compressor (101, 121) is prohibited. That is, in the above embodiment, the two-stage compression refrigeration cycle operation is not performed when the set temperature is originally set to a high temperature and the interior can be sufficiently maintained at the set temperature even in the single-stage compression refrigeration cycle operation. . For this reason, according to the said embodiment, the unnecessary driving | operation of each low stage compressor (101,121) can be avoided, and the energy-saving property of a freezing apparatus can be improved.

  In the above embodiment, the low-stage compressor (101, 121) is forcibly activated when a predetermined time t2 or more has elapsed since the start of the single-stage compression refrigeration cycle operation in step S5. For this reason, according to the above embodiment, even if there is a sensor misjudgment or the like in step S6 and the temperature inside the storage is actually cooled to a certain extent, the process does not proceed to step S7. The compressor (101, 121) can be reliably started to perform the two-stage compression refrigeration cycle operation. Therefore, the temperature in each cabinet can be reliably cooled to the set temperature, and the reliability of this refrigeration apparatus can be ensured.

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

  The refrigeration apparatus (10) of the above embodiment is a so-called multi-type refrigeration apparatus in which a plurality of use side circuits (50, 60) are connected in parallel to the heat source side circuit (40). Control means (201) is applied. However, for example, as shown in FIG. 7, the activation control means (201) of the present invention is applied to a so-called pair-type refrigeration apparatus in which one utilization side circuit is connected to the heat source side circuit (40). It may be.

  That is, also for the pair-type refrigeration apparatus (10) shown in FIG. 7, the high-stage compressor (41) is activated at the start of the cooling operation in the warehouse to perform the single-stage compression refrigeration cycle operation, and the refrigeration showcase (12 When the index indicating the internal temperature of () decreases to a predetermined value, the low-stage compressor (101) may be activated to perform the two-stage compression refrigeration cycle operation. Further, in the refrigeration apparatus (10) of FIG. 7, at the start of the cooling operation, the low-stage compressor (101) is started first to perform the single-stage compression refrigeration cycle operation, and then the temperature in the refrigerator is at a certain level. When it becomes low, the high-stage compressor (41) can be started to perform the two-stage compression refrigeration cycle operation. In any of these startup controls, as in the above-described embodiment, the energy saving performance at the start of the cooling operation can be improved.

  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 energy saving measures for a refrigeration apparatus including a refrigerant circuit having a low-stage compressor and a high-stage compressor.

It is a piping system diagram of the refrigerant circuit of the refrigerating device concerning an embodiment. It is a piping system figure which attached | subjected the flow of the refrigerant | coolant at the time of single stage compression refrigeration cycle operation | movement. It is a piping system figure which attached | subjected the flow of the refrigerant | coolant at the time of a two-stage compression refrigerating cycle operation | movement. It is the piping system figure which showed the flow of the refrigerant | coolant at the time of a defrost operation. It is a flowchart about the starting control of the compressor by a starting control means. It is the piping system figure which showed the flow of the refrigerant | coolant at the time of performing a two-stage compression refrigeration cycle operation | movement with one utilization side circuit. It is a piping system diagram of the refrigerant circuit of the refrigerating device concerning other embodiments.

Explanation of symbols

10 Refrigeration equipment
20 Refrigerant circuit
40 Heat source side circuit
41 High stage compressor
50 First use side circuit
60 Second user circuit
83 First cooling heat exchanger
93 Second cooling heat exchanger
101 1st low stage compressor
121 Second low stage compressor
201 Start control means

Claims (4)

A refrigeration apparatus comprising a refrigerant circuit (20) to which a low stage compressor (101) and a high stage compressor (41) are connected, and performing a refrigeration cycle in the refrigerant circuit (20) to cool the interior of the refrigerator,
The refrigerant circuit (20) includes a single-stage compression refrigeration cycle operation that operates one of a low-stage compressor (101) and a high-stage compressor (41), and a low-stage compressor (101) and a high-stage compressor (41). ) And the two-stage compression refrigeration cycle operation that operates both,
When cooling the inside of the refrigerator, only one of the compressors (41, 101) is started and the refrigerant circuit (20) performs the single-stage compression refrigeration cycle operation. After the single-stage compression refrigeration cycle operation is started, When the index indicating the temperature of the refrigerant falls to a predetermined value, the other compressor (101, 41) is also activated, and the activation control means (201) for performing the two-stage compression refrigeration cycle operation in the refrigerant circuit (20) is provided. A refrigeration apparatus characterized by comprising: In claim 1,
The start control means (201) starts only the high stage compressor (41) in the single stage compression refrigeration cycle operation. In claim 2,
The refrigerant circuit (20) includes a low-stage compressor (101, 121) and a cooling heat exchanger (83, 93) for cooling the interior of the heat source side circuit (40) to which the high-stage compressor (41) is connected. Is configured by connecting a plurality of usage circuits (50, 60) connected to each other in parallel,
The activation control means (201) determines whether to activate each low-stage compressor (101, 121) after the start of the single-stage compression refrigeration cycle operation, and uses side circuit provided with the low-stage compressor (101, 121) A refrigeration apparatus characterized in that the refrigeration apparatus is based on an index indicating the temperature in the refrigerator cooled by the cooling heat exchanger (83, 93) of (50, 60). In any one of Claims 1 thru | or 3,
The start-up control means (201) uses at least one of the internal air temperature, the refrigerant evaporation temperature, and the refrigerant evaporation pressure as an index indicating the internal temperature.

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