KR102126815B1 - Refrigeration apparatus - Google Patents

Abstract

An object of the present invention is to prevent the ignition of the motor by preventing liquefaction of the working fluid in the motor in a refrigeration apparatus including a two-stage compressor in which a motor is disposed at an intermediate stage.
The refrigeration apparatus 1 includes a two-stage screw compressor 10, a suction check valve 5b provided on the upstream side of the two-stage screw compressor 10, and a discharge check valve provided on the downstream side of the two-stage screw compressor 10. The valve 5a, the condenser 30 provided on the downstream side of the discharge check valve 5a, the evaporator 50 provided on the upstream side of the suction check valve 5b, and the condenser 30 in the flow of refrigerant And the expansion valve 40 provided between the evaporator 50, the pump down valve 5c provided between the condenser and the evaporator, the portion between the suction check valve 5b and the evaporator 50, and the middle end portion. It is provided with a bypass pipe 4 that is fluidly connected, and a bypass valve 4a provided in the bypass pipe 4.

Description

Refrigeration unit {REFRIGERATION APPARATUS}

The present invention relates to a refrigeration device.

Patent Document 1 discloses a refrigeration apparatus including a two-stage compressor. In this two-stage compressor, a motor is arranged so that a motor chamber (internal space of the motor) is fluidly connected to an intermediate flow path (connection space) between the first compressor body and the second compressor body in the flow of the working fluid. . In a two-stage compressor, since the working fluid is compressed in two stages, the pressure in the intermediate flow path and the motor chamber is at an intermediate pressure equal to or greater than the intake pressure and less than the discharge pressure.

Japanese Patent Publication No. 2011-99345

In the two-stage compressor, since the intermediate pressure is maintained even when the operation is stopped, the working fluid may be liquefied in the motor chamber due to a decrease in the outside temperature. When the working fluid is liquefied in the motor chamber, internal parts such as windings of the motor are immersed in the liquid, and electrical insulation is deteriorated, and there is a fear that the motor may be burned.

An object of the present invention is to prevent deterioration and burnout of electrical insulation of a motor by preventing liquefaction of a working fluid in a motor chamber in a refrigeration system including a two-stage compressor.

The present invention is arranged such that the motor chamber is fluidly connected to an intermediate flow path between the first compressor body and the second compressor body in the flow of the first compressor body, the second compressor body, and the working fluid, and the first stage A two-stage compressor having a compressor body and a motor for driving the second-stage compressor body, a suction check valve provided on the upstream side of the two-stage compressor, and an upstream side of the suction check valve in the flow of the working fluid. There is provided a refrigeration device including a bypass passage for fluidly connecting a first passage, a second passage including the intermediate passage and the motor chamber, and a bypass valve provided in the bypass passage.

According to this configuration, since the pressure of the second flow path can be balanced with the pressure of the first flow path through the bypass pipe by opening the bypass valve, the pressure (intermediate pressure) of the second flow path can be lowered if necessary. have. In addition, since the suction check valve is provided on the upstream side of the two-stage compressor, it is possible to depressurize the inside of the first flow passage upstream of the suction check valve by performing a pump down operation before opening the bypass valve. On the other hand, the first flow path can be made negative. Therefore, the pressure in the second flow path can be lowered by opening the bypass valve after the pump down operation. Therefore, it is possible to suppress the liquefaction of the working fluid in the motor room even when the ambient temperature decreases. Thereby, internal parts, such as a winding of a motor, are immersed in a liquid, electrical insulation deteriorates, and it can suppress that a motor burns out.

The refrigeration apparatus includes: a discharge check valve provided on the downstream side of the two-stage compressor, a condenser provided on the downstream side of the discharge check valve, a liquid storage part fluidly connected to the condenser, and upstream of the suction check valve An evaporator provided on the side, an expansion valve provided between the condenser and the evaporator in the flow of the working fluid, a pump down valve provided between the condenser and the evaporator in the flow of the working fluid, and the suction check valve The first pressure sensor detects the pressure of the working fluid between the two-stage compressors, and when the two-stage compressor is stopped, closes the pump down valve and drives the two-stage compressor to store the working fluid in the liquid. A control device that stops the pump down operation and opens the bypass valve may be further provided when the pump down operation collected in the unit is performed and the pressure value detected by the first pressure sensor becomes equal to or less than a predetermined value.

According to this configuration, when the two-stage compressor is stopped, the pump down operation is performed by the control device. By performing the pump-down operation, the working fluid is recovered in the liquid storage section, and the pressure in the first flow path can be reduced. At this time, the pressure in the second flow path is maintained as high as described above immediately after the pump down operation. Therefore, by opening the bypass valve after the pump-down operation, the working fluid in the second flow path can be turned to the depressurized first flow path through the bypass pipe. Here, the predetermined value that becomes the threshold value of the pressure value detected by the first pressure sensor is a pressure value sufficient to sufficiently discharge the working fluid in the second flow path into the first flow path, and is preferably substantially vacuum. It is a pressure value that can be judged.

The refrigeration apparatus includes a discharge check valve provided on the downstream side of the two-stage compressor, a condenser provided on the downstream side of the discharge check valve, a liquid storage part fluidly connected to the condenser, and an upstream side of the suction check valve Evaporator provided in the, the expansion valve provided between the condenser and the evaporator in the flow of the working fluid, a second pressure sensor for detecting the pressure of the working fluid between the evaporator and the suction check valve, the two-stage When the compressor is stopped, a control device that opens the bypass valve may be further provided if the pressure value measured by the second pressure sensor is equal to or less than a predetermined value.

According to this configuration, when the two-stage compressor is stopped, it can be determined by the second pressure sensor whether the first flow path is negatively and sufficiently necessary relative to the second flow path. Therefore, when the first flow path is negatively and sufficiently necessary to the second flow path, the pressure in the second flow path can be lowered only by opening the bypass valve.

The refrigeration apparatus includes: a discharge check valve provided on the downstream side of the two-stage compressor, a condenser provided on the downstream side of the discharge check valve, a liquid storage part fluidly connected to the condenser, and upstream of the suction check valve An evaporator provided on the side, an expansion valve provided between the condenser and the evaporator in the flow of the working fluid, a pump down valve provided between the condenser and the evaporator in the flow of the working fluid, and the suction check valve A first pressure sensor for detecting the pressure of the working fluid between the two-stage compressors, a second pressure sensor for detecting the pressure of the working fluid between the evaporator and the suction check valve, and the two-stage compressor stopped At this time, it is determined whether the pressure is measured by the second pressure sensor, and the pump down valve is closed, and if the pressure value measured by the second pressure sensor is equal to or less than the predetermined value, the bypass valve is turned on. When the pressure value measured by the second pressure sensor is opened and is greater than the predetermined value, a pump down operation is performed to collect the working fluid to the liquid storage unit by driving the two-stage compressor, and detected by the first pressure sensor. When the pressure value becomes equal to or less than the predetermined value, a control device for stopping the pump down operation and opening the bypass valve may be further provided.

According to this configuration, when the two-stage compressor is stopped, it is determined by the second pressure sensor whether the first flow path is sufficiently negatively necessary with respect to the second flow path, and the first flow path is necessary and sufficient for the second flow path. In the case of negative pressure, the pressure in the second flow path can be reduced to a pressure at which the refrigerant does not liquefy in the motor chamber even if the outside temperature decreases by simply opening the bypass valve. In addition, when the first flow path is not sufficiently negatively pressured relative to the second flow path, the pump is operated to make the first flow path negatively sufficient to the second flow path, and then the bypass valve is opened to open the second flow path. Can be reduced to a desired pressure.

The motor chamber may be fluidly connected to the intermediate flow path from one end side of the motor in the direction of the rotation axis of the motor, and the bypass pipe may be fluidly connected to the motor chamber on the other end side of the motor.

According to this configuration, it is possible to positively lower the pressure of the portion distant from the portion fluidly connected to the intermediate flow path in the motor chamber through the bypass pipe. In the motor chamber, since the working fluid tends to stay in a part distant from the part fluidly connected to the intermediate flow path, it is possible to further prevent liquefaction of the working fluid by actively lowering the pressure of the working fluid in the part.

According to the present invention, in a refrigeration apparatus including a two-stage compressor, since the working fluid in the second flow path can be turned to the first flow path through the bypass pipe, liquefaction of the working fluid in the motor room can be prevented. , It can prevent deterioration and burnout of the electrical insulation of the motor.

1 is a schematic configuration diagram of a refrigerating device according to an embodiment of the present invention.
Figure 2 is an enlarged view of the two-stage screw compressor of Figure 1;
3 is a control block diagram of the control device of FIG. 1;
4 is a flow chart showing control of the control device of FIG. 3;

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

1 is a schematic configuration diagram of a refrigerating device 1 according to an embodiment. The refrigeration unit 1 includes a two-stage screw compressor (two-stage compressor) 10, an oil separator 20, a condenser 30, a refrigerant tank 31, an expansion valve 40, and an evaporator 50 ). In the refrigeration apparatus 1, these are fluidly connected by piping 2a to 2e, and a circulation path of the refrigerant as a working fluid is constituted. In particular, the inlet check valve 5b is provided in the pipe 2e, and thereafter, the flow path on the upstream side of the intake check valve 5b of the pipe 2e is also referred to as a first flow path C1.

FIG. 2 is an enlarged view of the two-stage screw compressor 10 of FIG. 1. The two-stage screw compressor 10 compresses the refrigerant. The refrigerant may be, for example, ammonia or freon.

The two-stage screw compressor 10 further compresses and discharges the refrigerant compressed by the first stage compressor body 11 and the first stage compressor body 11 to intake and compress the refrigerant from the intake port 11a. A second stage compressor body 12 and a motor 13 driving them are provided.

The first compressor body 11 and the second compressor body 12 can rotate a pair of female screw rotors 11b and 12b in the rotor chambers 11A and 12A defined by the common casing 14 shared. I accept it. In this embodiment, the common casing 14 has a suction port portion 14a, a central portion 14b, and a discharge port portion 14c. In Fig. 2, only the male rotor is shown. The screw rotors 11b and 12b have rotor shafts 11c and 12c, respectively. The rotor shafts 11c and 12c are supported by bearings 15a to 15d, respectively. Further, the rotor shafts 11c and 12c are mechanically connected to the output shaft 13a of the motor 13 via gears 16, respectively. In the present embodiment, the two-stage screw compressor 10 is described as an example of the two-stage compressor, but the type of the compressor is not limited to this, and other types of two-stage compressors such as scroll type may be used.

The common casing 14 has an intake port 11a for suctioning refrigerant into the rotor chamber 11A of the first stage compressor body 11 as an intake port of the two-stage screw compressor 10, and a discharge port of the two-stage screw compressor 10 As described above, a discharge port 12a for discharging the refrigerant from the rotor chamber 12A of the second stage compressor body 12 is formed. The refrigerant discharged from the first stage compressor body 11 is sucked into the second stage compressor body 12 through an intermediate flow path which is a connection space 14A defined by the common casing 14 and the motor casing 17. have. That is, the connection space 14A is not only a flow path (middle flow path) of a fluid connecting the discharge port of the first stage compressor body 11 and the suction port of the second stage compressor body 12, but also accommodates the gear 16. It is also a space. Thereafter, the flow path from the discharge of the first compressor body 11 to the suction of the second compressor body 12, including this connection space 14A and the motor chamber 13A described later, is also referred to as the second flow path C2. do.

Further, in the common casing 14, oiling ports 14d, 14e (see FIG. 1) for supplying oil for lubrication and cooling to the bearings 15a, 15d are formed.

In the present embodiment, the first stage compressor body 11 and the second stage compressor body 12 are provided to be positioned relatively up and down, and are arranged so that the directions of suction and discharge of each other are opposite directions. In particular, in the present embodiment, the first compressor main body 11 in which the size of the screw rotor 11b is relatively large is disposed on the upper side, in other words, the second stage compressor in which the size of the screw rotor 12b is relatively small. The main body 12 is arranged on the lower side. In general, a structure in which the first compressor main body 11 and the second compressor main body 12 are horizontally arranged may be employed, or other arrangements may be adopted, other than the structure to be vertically disposed.

The motor 13 is disposed adjacent to the first compressor body 11 and the second compressor body 12. The motor 13 is inside the motor casing 17 so as to surround the rotor 13b and the rotor 13b provided on the output shaft 13a in the motor chamber 13A, which is an inner space of the motor casing 17. The stator 13c fixed to is accommodated. The output shaft 13a is supported by bearings 15e and 15f on both sides of the rotor 13b.

On one end side of the motor casing 17 in the rotational axis direction of the motor 13, communication paths 17a, 17b for connecting the connection space 14A sealed by the motor casing 17 and the motor chamber 13A are formed. It is done. Thereby, the fluid, such as a refrigerant and the oil mentioned later, can flow back and forth between the connection space 14A and the motor chamber 13A via the communication paths 17a and 17b.

Further, on the other end side of the motor casing 17, a bypass hole 17c to which a bypass pipe 4 to be described later is connected is formed. The bypass hole 17c is formed in the motor casing 17 on the opposite side to the connection space 14A. Specifically, the bypass hole 17c is formed on the top of the short wall of the motor casing 17. In addition, the motor casing 17 is formed with an oil supply port 17d for supplying oil for lubrication and cooling to the bearing 15e on the opposite side to the connection space 14A.

As shown in FIG. 1, the oil separator 20 is fluidly connected to the discharge port 12a of the two-stage screw compressor 10 through the pipe 2a. The oil separator 20 separates and collects oil from the refrigerant discharged from the outlet 12a of the two-stage screw compressor 10. The oil separator 20 includes a filter 21 and an oil tank 22. The filter 21 separates oil from the refrigerant. The oil separated from the refrigerant by the filter 21 is stored in the oil tank 22. The oil tank 22 is fluidly connected to the oil supply ports 14d, 14e, and 17d through the pipes 3a to 3c, and the oil stored in the oil tank 22 is the pipes 3a to 3c and the oil supply port It is sent to bearings 15a, 15d, 15e via (14d, 14e, 17d). Moreover, the oil provided for cooling and lubrication by the bearings 15a and 15d flows into the rotor chambers 11A and 12A, and also contributes to cooling, lubrication and sealing of the screw rotors 11b and 12b. Further, although not shown, the oil stored in the oil tank 22 is directly supplied to the screw rotors 11b and 12b as well as the bearings 15a, 15d and 15e. Accordingly, the oil is flowing in a circulation mode in which it is discharged together with the refrigerant from the outlet 12a of the two-stage screw compressor 10, sent to the oil tank 22, and supplied to the two-stage screw compressor 10 again.

The condenser 30 is fluidly connected through the oil separator 20 and the pipe 2b, and the refrigerant separating oil from the oil separator 20 is transferred from the oil separator to the condenser 30 through the pipe 2b. Is supplied. In the condenser 30, the refrigerant is cooled and condensed. The condenser 30 is provided with a refrigerant tank 31, and the liquid refrigerant condensed in the condenser 30 is stored in the refrigerant tank 31. In addition, the discharge check valve 5a is provided in the pipe 2b to prevent the refrigerant from flowing backward.

The expansion valve 40 is fluidly connected to the condenser 30 and the refrigerant tank 31 through a pipe 2c, and the refrigerant passing through the condenser 30 and the refrigerant tank 31 connects the pipe 2c. Is supplied to the expansion valve 40. The expansion valve 40 has a function of depressurizing the high-pressure refrigerant. In addition, a pump down valve 5c is provided in the pipe 2c. The pump down valve 5c is an electromagnetic valve, and is open in the normal operation state, and is closed by the control device 60 when a predetermined condition described later is satisfied.

The evaporator 50 is fluidly connected through the expansion valve 40 and the pipe 2d, and the refrigerant decompressed by the expansion valve 40 is supplied to the evaporator 50 through the pipe 2d. The evaporator 50 is a portion that heats a refrigerant and evaporates it. The evaporator 50 is also fluidly connected to the intake port 11a of the two-stage screw compressor 10 through the pipe 2e, and the refrigerant evaporated from the evaporator 50 is two-stage through the pipe 2e. It is supplied to the intake port 11a of the screw compressor 10. In addition, as described above, a suction check valve 5b is provided in the pipe 2e to prevent the refrigerant from flowing backward.

A pressure sensor (first pressure sensor) 6a for detecting the pressure of the refrigerant flowing through the portion is provided on the downstream portion of the suction check valve 5b in the pipe 2e. In addition, a pressure sensor (second pressure sensor) 6b for detecting the pressure of the refrigerant flowing through the portion is provided in the portion upstream of the suction check valve 5b in the pipe 2e. In addition, the portion on the upstream side of the suction check valve 5b in the pipe 2e is fluidly connected to the bypass hole 17c by the bypass pipe 4. The bypass pipe 4 is provided with a bypass valve 4a that allows or blocks the flow of fluid in the bypass pipe 4. The bypass valve 4a is an electromagnetic valve, and is closed in the normal operation state, and is opened by the control device 60 when a predetermined condition described later is satisfied.

3 shows a control block diagram of the control device 60 of FIG. 1. The control device 60 is constructed by hardware including a storage device such as a central processing unit (CPU), random access memory (RAM), and read only memory (ROM), and software mounted thereon. The control device 60 controls each component of the refrigeration device 1, but in particular receives signals from the motor 13 and signals relating to the pressure values from the pressure sensors 6a, 6b. Based on the signal, driving of the motor 13 and opening and closing of the pump down valve 5c and the bypass valve 4a are controlled.

The control device 60 includes a pump down control unit 61, a first determination unit 62, a second determination unit 63, and a bypass valve control unit 64.

The pump down control unit 61 receives the stop signal from the motor 13, closes the pump down valve 5c according to the flow chart in FIG. 4 to be described later, and drives the motor 13 at a predetermined rotational speed to operate the pump down. This is the part that runs. Here, the pump down operation is an operation in which the refrigerant is recovered in the refrigerant tank 31 and the pressure in the intake portion of the two-stage screw compressor 10 is reduced.

The 1st determination part 62 is a part which receives the pressure value P1 detected by the pressure sensor 6a, and determines whether it is equal to or less than a predetermined value Pth (P1≤Pth). Here, the predetermined value Pth is a pressure value that can sufficiently discharge the pressure of the second flow path C2 through the bypass pipe 4 to the first flow path C1, and is preferably determined to be substantially vacuum. It is a pressure value that can be performed, and may be, for example, 0.04 MPa.

The 2nd determination part 63 is a part which receives the pressure value P2 detected by the pressure sensor 6b, and determines whether it is equal to or less than a predetermined value Pth (P2≤Pth).

The bypass valve control unit 64 is a portion that opens the bypass valve 4a according to the determination results of the first determination unit 62 and the second determination unit 63.

4 is a flow chart showing control of the control device 60 of FIG. 3. When the control device 60 receives the stop signal from the motor 13, the control of FIG. 4 starts (step S1). At this time, the pump down valve 5c is opened, and the bypass valve 4a is closed because it is immediately after the normal operation state is finished. First, the pump down valve 5c is closed by the pump down control unit 61 (step S2). Next, it is determined whether or not the pressure value P2 detected by the pressure sensor 6b or the predetermined value Pth or less (P2≤Pth) by the second determination unit 63 (step S3). When the pressure value is not P2 or the predetermined value Pth or less, the motor 13 is driven by the pump down control unit 61 to perform the pump down operation (step S4). By performing the pump down operation, the refrigerant is recovered in the refrigerant tank 31 and the pressure in the first flow path C1 can be reduced. At this time, the pressure in the second flow path C2 is maintained high immediately after the pump down operation. Next, it is determined whether the pressure value P1 detected by the pressure sensor 6a by the first determination unit 62 is equal to or less than the predetermined value Pth (P1≤Pth) (step S5), and the pressure value P1 is equal to or less than the predetermined value Pth It waits until it becomes (step S5). Then, when it reaches the predetermined value Pth or less, the pump down operation is ended (step S6), and the bypass valve 4a is opened by the bypass valve control unit 64 (step S7). Thereby, the motor chamber 13A and the piping 2e communicate with the bypass piping 4, and the pressure in the motor chamber 13A decreases. In the process of step S3, when the pressure value P2 or the predetermined value Pth or less is performed, the process of steps S4 to S6 is omitted, and step S7 is executed. Then, after completing these processes, the main control is ended (step S8).

According to the freezing apparatus 1 of this embodiment, the following advantages are provided.

(1) Since the pressure of the second flow path C2 can be balanced with the pressure of the first flow path C1 through the bypass pipe 4 by opening the bypass valve 4a, the second flow path is required. The pressure of (C2) can be reduced. In addition, since the suction check valve 5b is provided on the upstream side of the two-stage screw compressor 10, by performing a pump down operation before opening the bypass valve 4a, the upstream side of the suction check valve 5b is provided. The pressure in the first flow path C1 can be reduced, and the first flow path C1 can be made negative with respect to the second flow path C2. Therefore, the pressure in the second flow path C2 can be lowered by opening the bypass valve 4a after the pump down operation. Therefore, it is possible to suppress the refrigerant from being liquefied in the motor chamber 13A even when the ambient temperature decreases. Thereby, it is possible to suppress that the internal parts such as the windings of the motor 13 are immersed in the liquid, the electrical insulation deteriorates, and the motor 13 burns out.

(2) When the two-stage screw compressor 10 is stopped, it is judged by the second pressure sensor 6b whether the first flow path C1 is negatively and sufficiently necessary for the second flow path C2. When the 1st flow path C1 is negatively and sufficiently necessary for the second flow path C2, the motor chamber 13A even if the pressure of the second flow path C2 decreases the outside temperature by simply opening the bypass valve 4a. In the refrigerant can be reduced to a pressure that does not liquefy. In addition, when the first flow path C1 is not sufficiently negatively needed for the second flow path C2, by performing the pump-down operation, the first flow path C1 has a sufficient negative pressure required for the second flow path C2. After allowing, the bypass valve 4a can be opened to lower the second flow path C2 to a desired pressure.

(3) In the motor chamber 13A, the pressure away from the communication paths 17a, 17b can be actively reduced through the bypass pipe 4. In the motor chamber 13A, since the refrigerant tends to stay in a portion far from the communication paths 17a and 17b, the liquefaction of the refrigerant can be further prevented by actively lowering the pressure of the refrigerant in the portion.

In the above, specific embodiments of the present invention and modifications thereof have been described, but the present invention is not limited to the above embodiments, and can be implemented by variously changing within the scope of the present invention.

For example, in the control flow of Fig. 4, the valve closing process in step S2 and the determination process in step S3 do not necessarily have to be executed in this order. That is, the valve closing process may be performed after the determination processing. Note that the determination processing in step S3 may be omitted, and in this case, the processing in steps S4 to S7 is executed after the valve closing processing in step S2. In addition, for example, in the above-described embodiment, the bypass hole 17c connecting the bypass pipe 4 is provided on the opposite side to the communication paths 17a and 17b in the direction of the rotation axis of the motor 13, but the second If it is a part connected to the flow path C2, another part may be provided.

1: Refrigeration unit
2a to 2e: piping
3a to 3c: Piping
4: Bypass piping
4a: bypass valve
5a: discharge check valve
5b: suction check valve
5c: Pump down valve
6a: Pressure sensor (first pressure sensor)
6b: pressure sensor (second pressure sensor)
10: two-stage screw compressor (two-stage compressor)
11: First stage compressor body
11A: Rotor room
11a: Intake vent
11b: screw rotor
11c: rotor shaft
12: 2nd stage compressor body
12A: Rotor room
12a: outlet
12b: screw rotor
12c: Rotor shaft
13: motor
13A: Motor room
13a: output shaft
13b: rotor
13c: stator
14: common casing
14A: connection space (middle flow path)
14a: inlet part
14b: central part
14c: discharge port
14d, 14e: Refueling port
15a to 15f: bearing
16: gear
17: motor casing
17a, 17b: communication path
17c: bypass hole
17d: Refueling port
20: oil separator
21: filter
22: oil tank
30: condenser
31: refrigerant tank
40: expansion valve
50: evaporator
60: control device
61: pump down control
62: first judgment unit
63: second judgment unit
64: bypass valve control
C1: 1st Euro
C2: Second Euro

Claims (5)

In the flow of the first compressor body, the second compressor body, and the working fluid, a motor chamber is arranged to be fluidly connected to an intermediate flow path between the first compressor body and the second compressor body, and the first compressor body and the A two-stage compressor having a motor that drives the second-stage compressor body,
And a suction check valve provided on the upstream side of the two-stage compressor,
A bypass pipe for fluidly connecting a first flow path upstream of the suction check valve in the flow of the working fluid, and a second flow path including the intermediate flow path and the motor chamber,
A bypass valve provided in the bypass pipe,
A control device that opens the bypass valve when the two-stage compressor is stopped and the first flow path is negative pressure than the second flow path
Refrigerating device comprising a. In the flow of the first compressor body, the second compressor body, and the working fluid, a motor chamber is arranged to be fluidly connected to an intermediate flow path between the first compressor body and the second compressor body, and the first compressor body and the A two-stage compressor having a motor that drives the second-stage compressor body,
And a suction check valve provided on the upstream side of the two-stage compressor,
A bypass pipe for fluidly connecting a first flow path upstream of the suction check valve in the flow of the working fluid, and a second flow path including the intermediate flow path and the motor chamber,
A bypass valve provided in the bypass pipe,
The discharge check valve provided on the downstream side of the two-stage compressor,
A condenser provided on the downstream side of the discharge check valve,
A liquid storage part fluidly connected to the condenser;
Evaporator provided on the upstream side of the suction check valve,
An expansion valve provided between the condenser and the evaporator in the flow of the working fluid,
A pump down valve provided between the condenser and the evaporator in the flow of the working fluid,
A first pressure sensor for detecting the pressure of the working fluid between the suction check valve and the two-stage compressor,
When the two-stage compressor is stopped, the pump down operation is performed to collect the working fluid to the liquid storage unit by closing the pump down valve and driving the two-stage compressor, and the pressure value detected by the first pressure sensor is The control device which stops the pump down operation and opens the bypass valve when it reaches a predetermined value or less
Refrigerating device comprising a. In the flow of the first compressor body, the second compressor body, and the working fluid, a motor chamber is arranged to be fluidly connected to an intermediate flow path between the first compressor body and the second compressor body, and the first compressor body and the A two-stage compressor having a motor that drives the second-stage compressor body,
And a suction check valve provided on the upstream side of the two-stage compressor,
A bypass pipe for fluidly connecting a first flow path upstream of the suction check valve in the flow of the working fluid, and a second flow path including the intermediate flow path and the motor chamber,
A bypass valve provided in the bypass pipe,
The discharge check valve provided on the downstream side of the two-stage compressor,
A condenser provided on the downstream side of the discharge check valve,
A liquid storage part fluidly connected to the condenser;
Evaporator provided on the upstream side of the suction check valve,
An expansion valve provided between the condenser and the evaporator in the flow of the working fluid,
A second pressure sensor for detecting the pressure of the working fluid between the evaporator and the suction check valve;
Control device for opening the bypass valve when the pressure value measured by the second pressure sensor is less than or equal to a predetermined value when the two-stage compressor is stopped
Refrigerating device comprising a. In the flow of the first compressor body, the second compressor body, and the working fluid, a motor chamber is arranged to be fluidly connected to an intermediate flow path between the first compressor body and the second compressor body, and the first compressor body and the A two-stage compressor having a motor that drives the second-stage compressor body,
And a suction check valve provided on the upstream side of the two-stage compressor,
A bypass pipe for fluidly connecting a first flow path upstream of the suction check valve in the flow of the working fluid, and a second flow path including the intermediate flow path and the motor chamber,
A bypass valve provided in the bypass pipe,
The discharge check valve provided on the downstream side of the two-stage compressor,
A condenser provided on the downstream side of the discharge check valve,
A liquid storage part fluidly connected to the condenser;
Evaporator provided on the upstream side of the suction check valve,
An expansion valve provided between the condenser and the evaporator in the flow of the working fluid,
A pump down valve provided between the condenser and the evaporator in the flow of the working fluid,
A first pressure sensor for detecting the pressure of the working fluid between the suction check valve and the two-stage compressor,
A second pressure sensor for detecting the pressure of the working fluid between the evaporator and the suction check valve;
When the two-stage compressor is stopped, it is determined whether the pressure value measured by the second pressure sensor is large or small and the pump down valve is closed, and the pressure value measured by the second pressure sensor is the predetermined value. Hereinafter, if the pressure value measured by the second pressure sensor is greater than the predetermined value by opening the bypass valve, a pump down operation is performed to collect the working fluid to the liquid storage unit by driving the two-stage compressor, and A control device for stopping the pump down operation and opening the bypass valve when the pressure value detected by the first pressure sensor falls below the predetermined value.
Refrigerating device comprising a. The motor chamber according to any one of claims 1 to 4, wherein the motor chamber is fluidly connected to the intermediate flow path on one side of the motor in the direction of the rotation axis of the motor,
The bypass pipe is a refrigeration apparatus, which is fluidly connected to the motor chamber on the other end side of the motor.

Images