WO2020080064A1

WO2020080064A1 - Refrigeration apparatus

Info

Publication number: WO2020080064A1
Application number: PCT/JP2019/038210
Authority: WO
Inventors: 昇壷井; 哲也垣内; 勝之鈴木; 英次神吉; 田中　啓介
Original assignee: 株式会社神戸製鋼所
Priority date: 2018-10-18
Filing date: 2019-09-27
Publication date: 2020-04-23
Also published as: JP2020063884A; JP6971951B2

Abstract

This refrigeration apparatus 1 is provided with a compressor 10 for compressing a refrigerant that is for a refrigeration cycle, a motor 20 that is accommodated in a motor chamber 12a defined by a motor casing 12 of the compressor 10 and drives the compressor 10, a pressure measurement unit 70 for measuring the pressure in the motor chamber 12a, a temperature detection unit 60 for measuring a temperature associated with the temperature state of the motor 20, a heating unit 50 for heating the motor chamber 12a, and a control device 40 for controlling the motor 20 and the heating unit 50. The control device 40 calculates a saturation temperature Ts of the refrigerant under the pressure measured by the pressure measurement unit 70, causes the heating unit 50 to heat the motor chamber 12a if a representative temperature T detected by the temperature detection unit 60 is no greater than the saturation temperature Ts when the compressor 10 is to be started, and enables starting of the compressor 10 if the representative temperature T exceeds the saturation temperature Ts.

Description

Refrigeration equipment

The present invention relates to a refrigeration system.

In the hermetically sealed electric motor of Patent Document 1, the stator winding wound with the ammonia resistant insulated conductor is arranged in the axial space in the motor frame in a gas phase portion that is not immersed in the liquid phase of the ammonia refrigerant. There is. In addition, the fully sealed electric motor has a liquid reservoir, and the refrigerant liquid accumulated in the liquid reservoir is discharged to the outside of the motor frame.

Japanese Utility Model Publication No. 6-17354

However, in the fully sealed electric motor of Patent Document 1, the refrigerant in the vapor phase part may be liquefied, and the liquefied refrigerant may adhere to the stator winding. Since the liquefied refrigerant has electrical conductivity, starting the motor with the liquefied refrigerant attached to the stator winding may cause the motor to burn out.

The present invention has an object to prevent burnout of a motor in a refrigeration system by preventing the liquefied refrigerant from starting the motor in a state of adhering to the motor.

One aspect of the present invention includes a compressor that compresses a refrigerant for a refrigeration cycle, a motor that is housed in a motor chamber defined by a motor casing of the compressor, and drives the compressor, and an inside of the motor chamber. A pressure measuring unit for measuring the pressure of the motor, a temperature detecting unit for measuring a temperature related to the temperature state of the motor, a heating unit for heating the motor chamber, and a control device for controlling the motor and the heating unit. The control device calculates the saturation temperature of the refrigerant at the pressure measured by the pressure measurement unit, and when the compressor is started, the representative temperature detected by the temperature detection unit is the saturation temperature. In the following cases, there is provided a refrigeration apparatus that heats the motor chamber by the heating unit and enables the compressor to be started when the representative temperature exceeds the saturation temperature.

According to this configuration, when the temperature of the motor is equal to or lower than the saturation temperature of the refrigerant in the motor chamber when the compressor is started, the controller heats the motor chamber by the heating unit and relates to the temperature state of the motor. When the temperature to be exceeded exceeds the saturation temperature of the refrigerant in the motor chamber, the compressor can be started. As a result, when the compressor is started, since the liquefied refrigerant does not exist in the motor chamber, it is possible to prevent the compressor from being started in a state where the liquefied refrigerant is attached to the motor, and it is possible to suppress burnout of the motor.

Further, the temperature detection unit may measure a temperature of a stator coil of the motor and a temperature of the motor chamber, and the control device controls the stator coil of the motor detected by the temperature detection unit. The magnitude relationship between the temperature and the temperature of the motor chamber may be determined, and the lower temperature of the temperature of the stator coil and the temperature of the motor chamber may be set as the representative temperature.

The temperature detection unit may measure the temperature of the motor casing, and the control device determines the temperature of the stator coil of the motor or the temperature of the motor chamber from the temperature of the motor casing detected by the temperature detection unit. The temperature may be estimated, or the temperature of the stator coil of the motor or the estimated value of the temperature of the motor chamber may be set as the representative temperature.

With this configuration, a temperature sensor that measures the temperature of the motor casing can be mounted outside the motor chamber, so there is no need to install equipment such as airtight terminals. Therefore, the configuration required for the temperature detection unit of the refrigeration system can be reduced and the configuration of the refrigeration system can be simplified, so that the manufacturing cost of the refrigeration system can be reduced.

The heating unit may be a heater attached to the motor casing of the motor chamber.

The compressor may include a motor casing jacket configured to surround an outer surface of the motor casing, and the heating unit may control the temperature of the motor casing jacket and a temperature higher than a temperature of the motor chamber. A heating circuit for supplying the medium to the motor casing jacket may be included.

In the refrigeration cycle, a suction check valve provided upstream of the compressor is fluidly connected to the first flow path upstream of the suction check valve in the refrigeration cycle and the motor chamber. A bypass pipe and a bypass valve provided in the bypass pipe may be provided.

Further, it is preferable that the control device opens the bypass valve when the representative temperature is equal to or lower than the saturation temperature and the pressure in the first flow path is lower than the pressure in the motor chamber.

With this configuration, by opening the bypass valve, the pressure in the motor chamber can be balanced with the pressure in the first flow path through the bypass pipe. As a result, the motor chamber can be depressurized, and the saturation temperature of the refrigerant in the motor chamber can be lowered, so that burnout of the motor can be efficiently suppressed.

According to the present invention, motor burnout can be suppressed.

1 is a schematic configuration diagram of a refrigeration apparatus according to a first embodiment of the present invention. FIG. 3 is an enlarged view of the compressor according to the first embodiment. 3 is a flowchart showing control of the control device according to the first embodiment. The enlarged view of the compressor which concerns on 2nd Embodiment. The enlarged view of the compressor which concerns on 3rd Embodiment. The schematic block diagram of the refrigerating device concerning a 3rd embodiment. The schematic block diagram of the refrigerating device concerning a 4th embodiment. The enlarged view of the compressor which concerns on 4th Embodiment.

(First embodiment)
Referring to FIG. 1, the refrigeration apparatus 1 according to the present embodiment includes a compressor 10, a motor 20 that drives the compressor 10, an oil separator 30, a condenser 31, a refrigerant tank 32, and an expansion valve 33. An evaporator 34 and a control device 40 are provided. In the refrigeration system 1, the compressor 10, the oil separator 30, the condenser 31, the refrigerant tank 32, the expansion valve 33, and the evaporator 34 are fluidly connected by the pipes 2a to 2e. Thereby, in the refrigeration system 1, a circulation flow path of the refrigeration cycle including the compressor 10, the oil separator 30, the condenser 31, the refrigerant tank 32, the expansion valve 33, and the evaporator 34 is configured. .

The compressor 10 compresses a refrigerant. The refrigerant for the refrigeration cycle of the present embodiment is a natural refrigerant such as ammonia or an artificial refrigerant such as CFCs, and is a refrigerant that has electric conductivity when in a liquid state.

The compressor 10 of this embodiment is a two-stage screw compressor. Referring to FIG. 2, the compressor 10 includes a compressor casing 11, a motor casing 12, a first stage compressor body 13 housed in the compressor casing 11, and a second stage compressor housed in the compressor casing 11. A compressor body 14 is provided. The compressor casing 11 and the motor casing 12 are integrally connected in a sealed manner. In other words, the compressor 10 of this embodiment is a semi-hermetic type compressor.

The compressor casing 11 has a rotor chamber 11a for accommodating a pair of screw rotors 13a described later of the first-stage compressor body 13 and a pair of screw rotors 14a described later for the second-stage compressor body 14. Of the rotor chamber 11b. Further, the compressor casing 11 has an intake port 11c as an intake port of the compressor 10 for sucking the refrigerant into the rotor chamber 11a for the first stage compressor body 13, and a second stage as an outlet port of the compressor 10. A discharge port 11d for discharging the refrigerant from the rotor chamber 11b for the compressor body 14 is formed.

The motor casing 12 defines a motor chamber 12a for housing the motor 20. Further, the motor casing 12 defines the connection space 15 together with the compressor casing 11. The motor casing 12 is formed with

communication passages

12b and 12c that communicate the motor chamber 12a and the connection space 15. As a result, the refrigerant can move back and forth between the connection space 15 and the motor chamber 12a through the

communication passages

12b and 12c. An electric heater 50 (heating unit) for heating the motor chamber 12a is provided on the outer surface of the motor casing 12. The electric heater 50 is provided at least at the bottom of the motor casing 12 so that at least the lower part of the motor chamber 12a can be heated.

As described above, the first-stage compressor body 13 includes a pair of male and female screw rotors 13a housed in the rotor chamber 11a of the compressor casing 11. Note that FIG. 2 shows only the male rotor of the pair of male and female screw rotors 13a. The screw rotor 13a has a rotor shaft 13b, and both ends of the rotor shaft 13b are rotatably supported by

bearings

11e and 11f provided in the compressor casing 11. The end of the rotor shaft 13b of the screw rotor 13a on the side of the connection space 15 is mechanically connected to a gear 16a arranged in the connection space 15.

The second-stage compressor body 14 includes a pair of male and female screw rotors 14a housed in the rotor chamber 11b of the compressor casing 11, as described above. Note that FIG. 2 shows only the male rotor of the pair of female and male screw rotors 14a. The screw rotor 14a has a rotor shaft 14b, and both ends of the rotor shaft 14b are rotatably supported by

bearings

11g and 11h provided in the compressor casing 11. The end of the rotor shaft 14b of the screw rotor 14a on the side of the connection space 15 is mechanically connected to a gear 16b arranged in the connection space 15.

In the present embodiment, the first-stage compressor body 13 and the second-stage compressor body 14 are provided so as to be positioned relatively up and down, and the suction and discharge directions are opposite to each other. There is. Particularly, in the present embodiment, the first-stage compressor body 13 in which the size of the screw rotor 13a is relatively large is arranged on the upper side, in other words, the size of the screw rotor 14a in the second-stage compression body is relatively small. The machine body 14 is arranged on the lower side. Alternatively, instead of the vertically arranged structure, a structure in which the first-stage compressor body 13 and the second-stage compressor body 14 are horizontally arranged may be adopted, or other arrangements may be adopted. Good.

The motor 20 of this embodiment is an inner rotor type motor and is housed in the motor chamber 12 a of the motor casing 12. The motor 20 includes an output shaft 21, a rotor 22 connected to the output shaft 21, and a stator 23 arranged so as to surround the rotor 22. A stator coil 23a is wound around the stator 23. The output shaft 21 is rotatably supported by

bearings

12d and 12e provided on the motor casing 12 on both sides of the rotor 22. The end of the output shaft 21 on the side of the connection space 15 is mechanically connected to the

gears

16a and 16b. That is, the output shaft 21 includes the rotor shaft 13b of the screw rotor 13a of the first-stage compressor body 13 and the rotor shaft of the screw rotor 14a of the second-stage compressor body 14 via the gear 16c that meshes with the

gears

16a and 16b. Mechanically connected to 14b.

Further, referring also to FIG. 1, the refrigeration system 1 includes a temperature detection unit 60 that detects a temperature associated with a temperature state of the motor 20, and a pressure measurement unit 70 that detects a pressure P inside the motor chamber 12a. . Specifically, as shown in FIG. 2, the temperature detection unit 60 of the present embodiment is provided on the surface of the stator coil 23a, and measures the temperature T1 of the stator coil 23a of the motor 20, and a temperature sensor 61. The temperature sensor 62 is provided in the motor chamber 12a and measures the temperature T2 of the motor chamber 12a. The pressure measuring unit 70 is provided in the motor chamber 12a and includes a pressure sensor 71 that measures the pressure P in the motor chamber 12a.

The pressure sensor 71 of the present embodiment is provided so as to detect the pressure of a space far from the connection space 15 in the space formed on both sides of the motor 20 in the motor chamber 12a. Further, the temperature sensor 61 of the present embodiment is provided so as to detect the temperature of one of the stator coils 23 a formed at both ends of the motor 20 that is farther from the connection space 15. Further, the temperature sensor 62 of the present embodiment is provided so as to detect the temperature of a space far from the connection space 15 among the spaces formed on both sides of the motor 20 in the motor chamber 12a. Specifically, the temperature sensor 62 is provided so as to detect the temperature of the lower portion of the space (in the vicinity of the bottom of the motor casing 12). That is, the pressure sensor 71, the temperature sensor 61, and the temperature sensor 62 of the present embodiment are provided on the side opposite to the load side with respect to the motor 20, which is structurally likely to collect refrigerant.

When the first-stage compressor body 13 is driven by the motor 20, the first-stage compressor body 13 sucks the refrigerant from the intake port 11c, compresses it, and discharges it into the connection space 15. When driven by the motor 20, the second-stage compressor body 14 further compresses the refrigerant compressed by the first-stage compressor body 13 and discharged into the connection space 15, and discharges it to the discharge port 11d. In other words, the refrigerant discharged from the first-stage compressor body 13 is sucked into the second-stage compressor body 14 via the connection space 15 defined by the compressor casing 11 and the motor casing 12. That is, the connection space 15 is a fluid flow path (intermediate flow path) that connects the discharge port of the first-stage compressor body 13 and the intake port of the second-stage compressor body 14.

As shown in FIG. 1, the oil separator 30 is fluidly connected to the discharge port 11d of the compressor 10 through the pipe 2a. The oil separator 30 separates and collects oil from the mixed fluid of the refrigerant and the oil discharged from the discharge port 11d of the compressor 10. The oil separator 30 includes a filter 30a and an oil tank 30b. The filter 30a collects the oil accompanying the flow of the vapor-phase refrigerant and separates it from the refrigerant. The separated oil is stored in the oil tank 30b. That is, the oil is collected in the oil tank 30b. The oil stored in the oil tank 30b is supplied to the compressor 10 via an oil passage (not shown).

The condenser 31 is fluidly connected to the oil separator 30 through the pipe 2b, and the gas-phase refrigerant obtained by separating the oil in the oil separator 30 is supplied from the oil separator 30 to the condenser 31 through the pipe 2b. In the condenser 31, the refrigerant is cooled and condensed. The condenser 31 is provided with a refrigerant tank 32, and the liquid-phase refrigerant condensed in the condenser 31 is stored in the refrigerant tank 32. A discharge check valve 3a is interposed in the pipe 2b so that the refrigerant does not flow backward.

The expansion valve 33 is fluidly connected to the condenser 31 and the refrigerant tank 32 through the pipe 2c, and the refrigerant passing through the condenser 31 and the refrigerant tank 32 is supplied to the expansion valve 33 through the pipe 2c. The expansion valve 33 has a function of reducing the pressure of the high-pressure refrigerant.

The evaporator 34 is fluidly connected to the expansion valve 33 through the pipe 2d, and the refrigerant decompressed by the expansion valve 33 is supplied to the evaporator 34 through the pipe 2d. The evaporator 34 is a part that heats and evaporates the refrigerant. The evaporator 34 is fluidly connected to the intake port 11c of the compressor 10 through the pipe 2e, and the vapor-phase refrigerant evaporated in the evaporator 34 is supplied to the intake port 11c of the compressor 10 through the pipe 2e. It A suction check valve 3b is interposed in the pipe 2e so that the refrigerant does not flow backward.

The control device 40 is constructed by hardware including a storage device such as a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory), and software installed therein. The control device 40 of the present embodiment responds to the signal from the temperature detection unit 60 corresponding to the temperature related to the temperature state of the motor 20 and the pressure of the motor chamber 12a (shown in FIG. 2) from the pressure measurement unit 70. The activation of the motor 20 and the operation of the electric heater 50 are controlled based on the signal.

The control of the control device 40 according to the present embodiment will be described below with reference to FIG. When the control device 40 receives the activation signal of the compressor 10, the control device 40 starts the control of FIG. 3 (step S1).

First, the control device 40 sets the representative temperature T based on the signals from the temperature sensors 61 and 62 (step S2). Specifically, the control device 40 of the present embodiment determines the magnitude relationship between the temperature T1 of the stator coil 23a measured by the temperature sensor 61 and the temperature T2 of the motor chamber 12a measured by the temperature sensor 62. , The smaller temperature is set as the representative temperature T.

Next, the control device 40 calculates the saturation temperature Ts of the refrigerant at the pressure P detected by the pressure sensor 71 (step S3). The saturation temperature Ts is obtained from the ph diagram (Mollier diagram) of the refrigerant.

After that, the control device 40 determines whether or not the representative temperature T exceeds the saturation temperature Ts (T> Ts) (step S4).

In the process of step S4, when the representative temperature T is equal to or lower than the saturation temperature Ts, the control device 40 controls the electric heater 50 so that the electric heater 50 heats the motor chamber 12a (step S5). After that, in the process of step S4, the processes of steps S2 to S5 are repeated until it is determined that the representative temperature T exceeds the saturation temperature Ts.

When it is determined in the process of step S4 that the representative temperature T exceeds the saturation temperature Ts, the control device 40 starts the compressor 10 (step S6). Then, after completing the process of step S6, the control device 40 ends the present control (step S7).

According to the refrigeration system 1 of the present embodiment, the control device 40 causes the electric heater 50 to drive the motor when the representative temperature T is equal to or lower than the saturation temperature Ts of the refrigerant in the motor chamber 12a when the compressor 10 is started. The electric heater 50 is controlled to heat the chamber 12a. Further, the control device 40 starts the compressor 10 when both the temperature T1 of the stator coil 23a of the motor 20 and the temperature T2 of the motor chamber 12a exceed the saturation temperature Ts of the refrigerant in the motor chamber 12a. As a result, when the compressor 10 is started, since the liquefied refrigerant does not exist in the motor chamber 12a, it is possible to prevent the compressor 10 from being started in a state where the liquefied refrigerant is attached to the stator coil 23a of the motor 20. Therefore, the burnout of the motor 20 can be suppressed.

The process of step S2 and the process of step S3 may be performed at the same time. The process of step S3 may be executed before the process of step S2.

Further, the temperature detection unit 60 may not include the temperature sensor 62 that measures the temperature of the motor chamber 12a. In this case, the controller 40 sets the temperature T1 of the stator coil 23a of the motor 20 measured by the temperature sensor 61 as the representative temperature T in the process of step S2 (shown in FIG. 3).

(Second embodiment)
Referring to FIG. 4, the temperature detection unit 60 of the present embodiment includes a temperature sensor 63 that measures the temperature T3 of the motor casing 12 instead of the temperature sensors 61 and 62 (shown in FIG. 2). That is, the temperature detection unit 60 of the present embodiment measures the temperature T3 of the motor casing 12 instead of measuring the temperature T1 of the stator coil 23a of the motor 20 and the temperature T2 of the motor chamber 12a (shown in FIG. 2). .

The temperature sensor 63 of this embodiment is provided so as to detect the temperature of a portion of the motor casing 12 that is located on the opposite side of the connection space 15 (opposite load side of the motor) with the motor 20 interposed therebetween. Specifically, the temperature sensor 63 is provided so as to detect the temperature of the bottom portion of the motor casing 12 located on the side opposite to the load with respect to the motor that structurally tends to accumulate refrigerant.

In the present embodiment, the control flow of the control device 40 is the same as that of the first embodiment except for the process of step S2, and FIG. 3 is cited. In the process of step S2, the control device 40 of the present embodiment estimates the temperature of the stator coil 23a of the motor 20 from the temperature T3 of the motor casing 12 measured by the temperature sensor 63, and uses the estimated value as the representative temperature T. Set as. The temperature of the motor chamber 12a may be estimated from the temperature T3 of the motor casing 12 measured by the temperature sensor 63, and the estimated value may be set as the representative temperature T.

According to the present embodiment, since the temperature sensor 63 that measures the temperature T3 of the motor casing 12 can be attached to the outside of the motor chamber 12a, it is not necessary to provide a device such as an airtight terminal. Therefore, the configuration required for the temperature detection unit 60 of the refrigeration system 1 can be reduced and the configuration of the refrigeration system 1 can be simplified, so that the manufacturing cost of the refrigeration system 1 can be reduced.

(Third Embodiment)
Referring to FIG. 5, a motor casing jacket 80 is provided on the outer surface of the motor casing 12 of the present embodiment so as to surround the motor casing 12. A temperature control medium (eg, water) is supplied to the motor casing jacket 80 so as to heat or cool the motor chamber 12a. The motor casing jacket 80 is formed with an inlet 80a through which the temperature control medium flows in and an outlet 80b through which the temperature control medium flows out. In the present embodiment, the motor casing jacket 80 and a heating circuit described later form a heating unit.

Referring to FIG. 6, the refrigeration system 1 includes a cooling device (cooling tower) 81 for cooling the temperature control medium (water in this embodiment) supplied to the motor casing jacket 80. The motor casing jacket 80 and the cooling device 81 are fluidly connected via the

pipes

4a and 4b. As a result, the refrigeration system 1 of this embodiment is provided with a cooling circuit having the motor casing jacket 80 and the cooling device 81. In the cooling circuit, the temperature control medium is circulated by a pump (not shown), and the temperature control medium cooled by the cooling device 81 is supplied to the motor casing jacket 80.

The pipe 4a fluidly connects the outlet 80b of the motor casing jacket 80 and the cooling device 81. The pipe 4a is provided with an opening / closing valve 5a that allows or blocks the flow of the temperature control medium in the pipe 4a. The opening / closing valve 5a is an electromagnetic valve, and the opening / closing control is performed by the control device 40.

The pipe 4b fluidly connects the inlet 80a of the motor casing jacket 80 and the cooling device 81. The pipe 4b is provided with an opening / closing valve 5b that allows or blocks the flow of the temperature control medium in the pipe 4b. The opening / closing valve 5b is an electromagnetic valve, and the opening / closing control is performed by the control device 40.

The controller 40 cools the motor 20 by opening the on-off

valves

5a and 5b and supplying the temperature control medium cooled by the cooling device 81 to the motor casing jacket 80 during the normal operation of the refrigeration system 1. .

Further, the refrigeration system 1 of this embodiment includes a heat exchanger 82 for heating the temperature control medium supplied to the motor casing jacket 80. The motor casing jacket 80 and the heat exchanger 82 are fluidly connected to each other via the pipes 4a to 4d. As a result, the refrigeration apparatus 1 of this embodiment is provided with a heating circuit including the motor casing jacket 80 and the heat exchanger 82. In the heating circuit, the temperature control medium is circulated by a pump (not shown), and the temperature control medium heated by the heat exchanger 82 is supplied to the motor casing jacket 80. As described above, in the present embodiment, the motor casing jacket 80 and the heating circuit form a heating unit.

The heat exchanger 82 causes heat exchange between an external heat source (not shown) such as a heat source boiler and a temperature control medium flowing through the heating circuit. By this. The heat exchanger 82 supplies a temperature control medium (high temperature water in the present embodiment) having a temperature higher than the saturation temperature Ts of the refrigerant in the motor chamber 12a to the motor casing jacket 80 so that the temperature control medium flows in the heating circuit. To heat.

The pipe 4c is branched from the pipe 4a at a branch portion 4e on the upstream side of the opening / closing valve 5a of the pipe 4a, and fluidly connects the pipe 4a and the heat exchanger 82. The pipe 4c is provided with an opening / closing valve 5c that allows or blocks the flow of the temperature control medium in the pipe 4c. The opening / closing valve 5c is an electromagnetic valve, and the opening / closing control is performed by the control device 40.

The pipe 4d joins the pipe 4b at a joining portion 4f on the downstream side of the on-off valve 5b of the pipe 4b, and fluidly connects the pipe 4b and the heat exchanger 82. The pipe 4d is provided with an opening / closing valve 5d that allows or blocks the flow of the temperature control medium in the pipe 4d. The opening / closing valve 5d is an electromagnetic valve, and the opening / closing control is performed by the control device 40.

The control device 40 of the embodiment includes a signal from the temperature detection unit 60 that corresponds to the temperature related to the temperature state of the motor 20, and a signal from the pressure measurement unit 70 that corresponds to the pressure of the motor chamber 12a (shown in FIG. 5). The start of the motor 20 and the operation of the on-off valves 5a to 5d are controlled based on the above.

In the present embodiment, the control flow of the control device 40 is the same as that of the first embodiment except for the process of step S5, and FIG. 3 is cited. In the present embodiment, in the process of step S5, the control device 40 controls the operation of the open / close valves 5a to 5d so as to open the open /

close valves

5c and 5d and close the open /

close valves

5a and 5b. The control device 40 also activates a pump (not shown) to circulate the temperature control medium in the heating circuit. As a result, the temperature control medium (high-temperature water) having a temperature exceeding the saturation temperature Ts of the refrigerant in the motor chamber 12a is supplied to the motor casing jacket 80 via the heating circuit, and the motor chamber 12a is heated.

In the present embodiment, instead of providing the on-off

valves

5a and 5c, a three-way valve may be provided on the branch portion 4e. Similarly, instead of providing the on-off

valves

5b and 5d, a three-way valve may be provided on the merging portion 4f.

(Fourth Embodiment)
Referring to FIG. 7, the refrigerating apparatus 1 of the present embodiment fluidly connects the portion (first flow path C1) on the upstream side of the suction check valve 3b in the pipe 2e and the motor chamber 12a (shown in FIG. 8). A bypass pipe 6 connected to the. The bypass pipe 6 is provided with a bypass valve 7 that allows or blocks the flow of the refrigerant in the bypass pipe 6. The bypass valve 7 is a solenoid valve and is closed in the normal operation state of the refrigeration system 1.

Referring to FIG. 8, the motor casing 12 of the present embodiment has a bypass hole 12f connected to the bypass pipe 6 (shown in FIG. 7). Thus, referring also to FIG. 7, the motor chamber 12a and the first flow path C1 are fluidly connected by the bypass pipe 6. Specifically, the bypass hole 12f is provided in the motor casing 12 on the opposite side of the connection space 15 with the motor 20 interposed therebetween. That is, the bypass hole 12f is provided on the side opposite to the load of the motor 20 of the motor casing 12.

A pressure sensor 90 for detecting the pressure P1 of the refrigerant flowing through the first flow path C1 is provided in the first flow path C1 in the pipe 2e of the present embodiment.

The control device 40 of the present embodiment corresponds to the signal from the temperature detection unit 60 corresponding to the temperature related to the temperature state of the motor 20 and the pressure of the motor chamber 12a (shown in FIG. 8) from the pressure measurement unit 70. The activation of the motor 20, the operation of the electric heater 50, and the operation of the bypass valve 7 are controlled based on the signal.

In the present embodiment, the control flow of the control device 40 is the same as that of the first embodiment except for the process of step S5, and FIG. 3 is cited. In the process of step S5, when the electric heater 50 heats the motor chamber 12a, the control device 40 of the present embodiment determines that the pressure P1 of the first flow passage measured by the pressure sensor 90 is higher than the pressure P of the motor chamber 12a. If low, the bypass valve 7 is opened. That is, in the present embodiment, the bypass valve 7 is opened when the representative temperature T is equal to or lower than the saturation temperature Ts and the pressure P1 in the first passage is lower than the pressure P in the motor chamber 12a. The bypass valve 7 can be closed before the motor 20 is started by the control device 40.

According to this configuration, by opening the bypass valve 7, the pressure P in the motor chamber 12a can be balanced with the pressure P1 in the first flow path through the bypass pipe 6. As a result, the pressure in the motor chamber 12a can be reduced, so that the saturation temperature Ts of the refrigerant in the motor chamber 12a can be lowered. Therefore, the heating of the motor chamber 12a by the electric heater 50 and the decompression of the motor chamber 12a by the bypass pipe 6 are used together, whereby the burnout of the motor 20 can be efficiently suppressed.

Although specific embodiments of the present invention and modifications thereof have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention.

For example, the compressor 10 is not limited to a screw type compressor, and may be another type of compressor such as a reciprocating type or a centrifugal type.

Further, the compressor 10 is not limited to the two-stage compressor, and may be a one-stage compressor.

Further, the compressor 10 is not limited to a semi-hermetic type compressor, and may be a totally hermetic type compressor as long as the refrigerant can exist in the motor casing. That is, the compressor casing 11 and the motor casing 12 may be integrally formed.

1 Refrigerator 2a to 2e Piping 3a Discharge check valve 3b Suction check valve 4a to 4d Piping

4e Branching section

4f Merging section 5a to 5d Open / close valve 6 Bypass piping 7 Bypass valve 10 Compressor 11 Compressor casing

11a Rotor chamber

11b Rotor Chamber

11c Intake port

11d Discharge port 11e-11h Bearing 12 Motor casing

12a Motor chamber

12b,

12c Communication passage

12d, 12e Bearing 13 1st stage compressor body 13a Screw rotor 14 2nd stage compressor body 15

Connection space

16a, 16b, 16c Gear 20 Motor 21 Output shaft 22 Rotor 23 Stator 23a Stator coil 30 Oil separator 31 Condenser 32 Refrigerant tank 33 Expansion valve 34 Evaporator 40 Controller 50 Electric heater (heating unit)
60 Temperature Detector 61, 62, 63 Temperature Sensor 70 Pressure Measuring Unit 71 Pressure Sensor 80 Motor Casing Jacket 81 Cooling Device 82 Heat Exchanger 90 Pressure Sensor

Claims

A compressor for compressing the refrigerant for the refrigeration cycle,
A motor that is housed in a motor chamber defined by the motor casing of the compressor and that drives the compressor;
A pressure measuring unit for measuring the pressure inside the motor chamber,
A temperature detection unit that measures a temperature related to the temperature state of the motor,
A heating unit for heating the motor chamber,
A control device for controlling the motor and the heating unit,
The control device is
Calculate the saturation temperature of the refrigerant at the pressure measured by the pressure measurement unit,
When starting the compressor, if the representative temperature detected by the temperature detection unit is less than or equal to the saturation temperature, heat the motor chamber by the heating unit,
A refrigeration apparatus that enables the compressor to be started when the representative temperature exceeds the saturation temperature.
The temperature detector measures the temperature of the stator coil of the motor and the temperature of the motor chamber,
The control device is
Judging the magnitude relationship between the temperature of the stator coil and the temperature of the motor chamber detected by the temperature detector,
The refrigerating apparatus according to claim 1, wherein a lower one of the temperature of the stator coil and the temperature of the motor chamber is set as the representative temperature.
The temperature detector measures the temperature of the motor casing,
The control device is
Estimating the temperature of the stator coil of the motor or the temperature of the motor chamber from the temperature of the motor casing detected by the temperature detection unit,
The refrigeration apparatus according to claim 1, wherein an estimated value of the temperature of the stator coil of the motor or the temperature of the motor chamber is set as the representative temperature.
The refrigeration system according to any one of claims 1 to 3, wherein the heating unit is a heater attached to the motor casing.
The compressor includes a motor casing jacket configured to surround an outer surface of the motor casing,
4. The heating unit according to claim 1, wherein the heating unit includes the motor casing jacket and a heating circuit that supplies a temperature control medium having a temperature higher than the temperature of the motor chamber to the motor casing jacket. The refrigeration system described.
A suction check valve provided on the upstream side of the compressor in the refrigeration cycle,
A bypass pipe that fluidly connects the first flow path upstream of the suction check valve and the motor chamber in the refrigeration cycle;
The refrigeration apparatus according to any one of claims 1 to 3, further comprising: a bypass valve provided in the bypass pipe.
The refrigeration apparatus according to claim 6, wherein the control device opens the bypass valve when the representative temperature is equal to or lower than the saturation temperature and the pressure in the first flow path is lower than the pressure in the motor chamber.