WO2021171489A1

WO2021171489A1 - Screw compressor and freezer

Info

Publication number: WO2021171489A1
Application number: PCT/JP2020/008051
Authority: WO
Inventors: 伊藤　健
Original assignee: 三菱電機株式会社
Priority date: 2020-02-27
Filing date: 2020-02-27
Publication date: 2021-09-02
Also published as: EP4112940A4; EP4112940A1

Abstract

This screw compressor comprises: a cylindrical casing; a screw rotor disposed so as to rotate inside the casing; and a motor that is disposed inside the casing and that drives the screw rotor. In the casing, a motor frame in which the motor is accommodated has a cooling hole formed in a high temperature section of the motor frame where the temperature locally increases during operation, the cooling hole extending in a direction of the rotary axis of the screw rotor and allowing a refrigerant from the outside to pass through.

Description

Screw compressor and refrigeration equipment

The present disclosure relates to a screw compressor and a refrigerating apparatus equipped with a cooling technique for cooling a motor in a casing.

The screw compressor mainly includes a screw rotor, low-pressure side bearings and high-pressure side bearings that support the screw rotor, a motor that drives the screw rotor, and a casing that houses them. The motor can be placed on either the low-pressure side or the high-pressure side in the casing, but as the winding temperature of the motor stator rises, the tolerance of the compressor components to the heat-resistant temperature decreases, and reliability becomes lower. descend. Therefore, the motor is often arranged on the low pressure side for the purpose of promoting cooling of the motor. This is because when the motor is arranged on the low pressure side, the motor can be cooled by the low temperature and low pressure refrigerant gas sucked into the casing.

There is, for example, Patent Document 1 as a technique for cooling a motor with an intake gas in this way. In Patent Document 1, a collision member with which the flow of the refrigerant collides is provided in the casing, and the flow of the refrigerant is adjusted by colliding the refrigerant with the collision member to prevent a local temperature rise of the winding of the motor. ing.

JP-A-2018-178815

In Patent Document 1, the flow rate of the refrigerant is adjusted by using the collision member, but since the flow velocity of the refrigerant flowing into the casing changes according to the operating conditions, the flow rate of the refrigerant does not become the expected flow, and the motor is wound. It may not be possible to prevent the local temperature rise of the line. In this case, there is a problem that the operating range is limited.

The present disclosure has been made in view of the above problems, and provides a screw compressor and a freezing device capable of preventing a local temperature rise of a motor winding and expanding an operating range. The purpose.

The screw compressor according to the present disclosure includes a tubular casing, a screw rotor arranged to rotate in the casing, and a motor arranged in the casing to drive the screw rotor. Among the casings, the screw compressor includes a motor. In the motor frame, which is a part that accommodates the casing, a cooling hole through which an external refrigerant passes extends in the direction of the rotation axis of the screw rotor in a high temperature portion where the temperature rises locally during operation. ..

The refrigerating apparatus according to the present disclosure includes the above-mentioned screw compressor, a condenser, a main depressurizing device, and an evaporator, and from a refrigerant circuit in which a refrigerant circulates and a pipe between the condenser and the main depressurizing device. It is provided with a first pipe that is branched and connected to the inlet of the cooling hole of the screw compressor, and a cooling decompression device that is provided in the first pipe and depressurizes the refrigerant passing through the first pipe.

According to the present disclosure, since the cooling hole is provided in the high temperature part of the motor frame, the high temperature part can be centrally cooled by flowing the refrigerant from the outside through the cooling hole. Therefore, the high temperature portion and the motor can be stably cooled, and a local temperature rise can be prevented. As a result, the operating range can be expanded.

It is schematic cross-sectional view which shows an example of the screw compressor which concerns on Embodiment 1. FIG. FIG. 1 is a schematic cross-sectional view taken along the line AA of FIG. It is a schematic plan view which shows the screw rotor and a pair of gate rotors of the screw compressor which concerns on Embodiment 1. FIG. It is a figure which shows an example of the suction process of the compression chamber of the screw compressor of FIG. It is a figure which shows an example of the compression process of the compression chamber of the screw compressor of FIG. It is a figure which shows an example of the discharge process of the compression chamber of the screw compressor of FIG. It is a figure which shows the structure of the refrigerating apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the change of the evaporation temperature and the condensation temperature in one cycle operation of a refrigerating apparatus. It is a flowchart which shows the flow of control of the cooling pressure reducing device of the refrigerating sail device which concerns on Embodiment 1. FIG. It is a figure which shows the structure of the refrigerating apparatus which concerns on Embodiment 2.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each figure, the same or corresponding parts are designated by the same reference numerals, and the description thereof will be omitted or simplified as appropriate. In addition, the shape, size, arrangement, etc. of the configurations shown in each figure can be appropriately changed within the scope of the present disclosure.

Embodiment 1.
[Screw compressor 100]
FIG. 1 is a schematic cross-sectional view showing an example of the screw compressor according to the first embodiment. FIG. 2 is a schematic cross-sectional view taken along the line AA of FIG. FIG. 3 is a schematic plan view showing a screw rotor and a pair of gate rotors of the screw compressor according to the first embodiment.
As shown in FIGS. 1 and 2, the screw compressor 100 of the first embodiment includes a tubular casing 2, a screw rotor 3 housed in the casing 2, and a motor for rotationally driving the screw rotor 3. It is equipped with 4.

The motor 4 has a stator 4a fixed inscribed in the casing 2 and a motor rotor 4b arranged inside the stator 4a.

The motor 4 may be a constant speed machine having a constant rotation speed or an inverter type variable speed machine whose operating capacity can be adjusted by changing the rotation speed, but this specification assumes a variable speed machine. The rotation speed change is controlled by the control device 109 (see FIG. 7 described later).

The screw rotor 3 and the motor rotor 4b are arranged on the same axis, and both are fixed to the rotating shaft 5. The screw rotor 3 is connected to a motor rotor 4b fixed to the rotary shaft 5 and is rotationally driven.

Both ends of the rotating shaft 5 are rotatably supported by the main bearing 11 and the auxiliary bearing 13. The main bearing 11 is arranged in a main bearing housing (not shown) provided at the end of the screw rotor 3 on the discharge side (left side in FIG. 1). The auxiliary bearing 13 is provided at the end of the rotary shaft 5 on the suction side (right side in FIG. 1) of the screw rotor 3.

The screw rotor 3 is formed in a cylindrical shape, and a plurality of screw grooves 3a are spirally formed on the outer peripheral surface. Of the plurality of screw grooves 3a, as shown in FIG. 3, the space surrounded by the inner peripheral surface of the casing 2 and the pair of gate rotors 6 engaging and engaging with the screw grooves 3a forms a compression chamber 29. doing. The gate rotor 6 rotates with the rotation of the screw rotor 3.

The casing 2 includes a main casing 2a and a suction casing 2b. A screw rotor 3 and a motor 4 are housed in the main casing 2a. The suction casing 2b is formed with a suction port (not shown) for sucking the refrigerant from the external refrigerant circuit. Hereinafter, the refrigerant sucked into the casing 2 from the suction port is referred to as a suction refrigerant.

The inside of the casing 2 is separated by a partition wall (not shown) into a high pressure space (not shown) that is the discharge pressure and a low pressure space (not shown) that is the suction pressure. A discharge port 8 (see FIG. 3) that opens into a discharge chamber (not shown) is formed on the high-pressure space side of the casing 2. In the following, the portion of the main casing 2a to which the stator 4a of the motor 4 is fixed is referred to as a motor frame 2c.

The motor frame 2c is formed with a holding portion 21 for holding the stator 4a as shown in FIGS. 1 and 2. The holding portion 21 is a portion that protrudes from the inner peripheral surface of the motor frame 2c toward the stator 4a side and comes into contact with the outer peripheral surface of the motor 4 to hold the stator 4a. As shown in FIG. 2, the holding portions 21 are scattered in the circumferential direction, and the holding portions 21 are passages between the holding portions 21 through which the refrigerant sucked into the casing 2 passes.

The casing 2 has a high temperature portion 24 whose temperature rises locally during operation due to heat generated by the winding 4c of the motor 4 and lubricating oil or the like that flows into the casing 2 together with the refrigerant and accumulates in the lower part of the main casing 2a. Of the plurality of holding portions 21, the holding portion 21 located at the high temperature portion 24 is provided with a cooling hole 22 through which the refrigerant from the external refrigerant circuit passes. Hereinafter, the refrigerant flowing into the cooling hole 22 is referred to as a cooling refrigerant.

In this example, since the high temperature portion 24 is located below the rotating shaft 5, the cooling hole 22 is also provided below the rotating shaft 5. In this example, two cooling holes 22 are provided, but the number is arbitrary and may be one or three or more. The position of the high temperature portion 24 in the motor frame 2c varies depending on the shape of the flow path of the refrigerant in the casing 2, and if the cooling hole 22 is provided in the holding portion 21 located in the high temperature portion 24. good.

The cooling hole 22 is formed in the motor frame 2c so as to extend in the axial direction of the rotating shaft 5. Both ends of the cooling hole 22 are opened on the side surface of the main casing 2a, one opening is an inflow port 22a into which the cooling refrigerant flows in, and the other opening is an outflow port 22b in which the cooling refrigerant flows out. .. The first pipe 104 connected to the refrigerant circuit is connected to the inflow port 22a, and one end of the second pipe 106 is connected to the outflow port 22b. The other end of the second pipe 106 is connected to the opening on the outer surface side of the casing 2 of the injection hole 23 provided in the main casing 2a. The opening on the inner surface side of the casing 2 of the injection hole 23 communicates with the compression chamber 29.

[Compression operation]
Next, the operation of the screw compressor 100 according to the first embodiment will be described.
FIG. 4 is a diagram showing an example of a suction process of the compression chamber of the screw compressor of FIG. FIG. 5 is a diagram showing an example of a compression process of the compression chamber of the screw compressor of FIG. FIG. 6 is a diagram showing an example of a discharge process of the compression chamber of the screw compressor of FIG.

As shown in FIGS. 4 to 6, when the screw rotor 3 is rotated by the motor 4, the teeth 6a of the gate rotor 6 move relatively in the screw groove 3a. As a result, in the screw groove 3a, the suction step, the compression step, and the discharge step are regarded as one cycle, and this cycle is repeated. The portion surrounded by the dotted line in FIGS. 4 to 6 shows the casing 2, and the screw groove 3a surrounded by the casing 2 constitutes the compression chamber 29. Here, each process will be described by focusing on the compression chamber 29 shown by the hatching of dots in FIGS. 4 to 6.

The suction refrigerant sucked from the suction port (not shown) of the casing 2 passes around the motor 4 (see FIG. 1) and then flows into the screw groove 3a in the suction step. FIG. 4 shows the state of the compression chamber 29 immediately after the completion of the suction process, in other words, the compression start. Then, when the screw rotor 3 rotates in the direction of the solid arrow, the volume of the compression chamber 29 decreases as shown in FIG.

Subsequently, when the screw rotor 3 rotates, the compression chamber 29 communicates with the discharge port 8 as shown in FIG. As a result, the high-pressure refrigerant gas compressed in the compression chamber 29 is discharged to the outside from the discharge port 8.

[Cooling operation]
Next, the cooling operation in the screw compressor 100 will be described.
The cooling refrigerant from the refrigerant circuit passes through the cooling hole 22. That is, the cooling refrigerant flows from the first pipe 104 into the cooling hole 22 through the inflow port 22a and flows out from the outflow port 22b. Since the cooling hole 22 is provided in the high temperature portion 24 of the motor frame 2c, the high temperature portion 24 can be centrally cooled by flowing the cooling refrigerant through the cooling hole 22. By being able to concentrate and cool the high temperature portion 24, it is possible to suppress a local temperature rise of the motor 4. That is, since the high temperature portion 24 of the motor frame 2c is a portion having a higher temperature than the other portions due to the influence of the local temperature rise of the winding 4c of the motor 4, the temperature of the high temperature portion 24 should be lowered. Therefore, the local temperature rise of the winding 4c of the motor 4 can be suppressed. Further, since the cooling hole 22 is formed in the holding portion 21 so as to extend in the axial direction of the rotating shaft 5, the motor 4 can be cooled over the entire axial direction.

Here, when the operating conditions of the motor 4 change from a low rotation speed to a high rotation speed, the cooling refrigerant always flows through the cooling hole 22 provided in the high temperature section 24. That is, the high temperature portion 24 can be centrally cooled regardless of the rotation speed of the motor 4. Therefore, the high temperature portion 24 can be cooled stably as compared with the conventional technique of preventing the local temperature rise of the winding portion of the motor by adjusting the flow of the refrigerant by using the collision member. Therefore, it is not necessary to limit the operating range so that the temperature of the winding 4c of the motor 4 is equal to or lower than the heat resistant temperature, and the operating range can be expanded. Further, it is possible to suppress the deterioration of the motor efficiency due to the temperature rise of the motor 4, and it is also possible to reduce the size of the motor 4 by force.

The cooling refrigerant that has passed through the cooling hole 22 once flows out of the casing 2 from the outflow port 22b, passes through the second pipe 106, then enters the casing 2 again and flows into the compression chamber 29. That is, the cooling refrigerant flows into the compression chamber 29 in which the suction of the gas refrigerant is completed, instead of the screw groove 3a before the suction is completed. Therefore, it is possible to suppress the inconvenience that the cooling refrigerant hinders the suction of the intake refrigerant into the compression chamber 29, reduces the amount of refrigerant circulation, and deteriorates the performance. Here, the cooling refrigerant that has flowed out from the outlet 22b is once flowed out of the casing 2, then returned to the casing 2 and then flowed into the compression chamber 29, but passes through the casing 2. It may be allowed to flow into the compression chamber 29. In short, it suffices to provide a flow path for allowing the cooling refrigerant flowing out from the outflow port 22b to flow into the compression chamber 29.

Here, the cooling refrigerant may be a gas refrigerant or a two-phase refrigerant, or a liquid refrigerant, but a gas refrigerant or a two-phase refrigerant is preferable from the viewpoint of avoiding a decrease in operating capacity due to a decrease in the amount of refrigerant circulation. However, the cooling effect is higher when the cooling refrigerant is a liquid refrigerant. Therefore, the state of the cooling refrigerant may be appropriately selected from the balance between the cooling effect and the operating capacity.

[Refrigerant circuit]
Next, a refrigerating apparatus including the screw compressor 100 configured as described above will be described.
FIG. 7 is a diagram showing a configuration of a refrigerating apparatus according to the first embodiment. The refrigerating device 110 includes the above-mentioned screw compressor 100, a condenser 101, a main depressurizing device 102, and an evaporator 103, and these are connected in order by a refrigerant pipe to include a refrigerant circuit in which a refrigerant circulates. .. The refrigerating device 110 further includes a first pipe 104, a cooling decompression device 105, and a second pipe 106. The first pipe 104 is a pipe that branches from the pipe between the condenser 101 and the main decompression device 102 and is connected to the inflow port 22a of the casing 2 of the screw compressor 100. Since the second pipe 106 has been described above, the repeated description will be omitted.

The condenser 101 cools and condenses the refrigerant gas discharged from the screw compressor 100. The main decompression device 102 squeezes and expands the refrigerant liquid flowing out of the condenser 101. The pressure reducing device is composed of an electronic expansion valve, a capillary tube, a temperature expansion valve, or the like. The evaporator 103 evaporates the refrigerant flowing out of the main decompression device 102. The cooling decompression device 105 adjusts the flow rate of the refrigerant passing through the first pipe 104. The cooling pressure reducing device 105 is composed of an electronic expansion valve, a temperature expansion valve, or the like.

On the discharge side of the screw compressor 100, a discharge temperature sensor 107 that measures the temperature of the refrigerant discharged from the screw compressor 100 (hereinafter referred to as the discharge temperature) is provided. The discharge temperature measured by the discharge temperature sensor 107 is output to the control device 109 described later. Further, the screw compressor 100 is provided with a motor frame temperature sensor 108 that measures the temperature of the motor frame 2c (hereinafter referred to as the motor frame temperature), which is the installation location of the motor 4. The motor frame temperature measured by the motor frame temperature sensor 108 is output to the control device 109.

The refrigerating device 110 is further provided with a control device 109. The control device 109 controls the entire refrigerating device 110. Further, the control device 109 controls the opening degree of the cooling decompression device 105 based on the measured values of the discharge temperature sensor 107 and the motor frame temperature sensor 108. The control device 109 can be configured by hardware such as a circuit device that realizes the function, or can be configured by a computing device such as a microcomputer or a CPU and software executed on the arithmetic unit.

The refrigerant circulating in the refrigerant circuit is not limited to a specific refrigerant, but for example, a refrigerant having a low GWP may be selected in consideration of the impact on the environment and the like. The refrigerant having a low GWP is, for example, R32, R513A, HFO-1234yf, HFO-1234ze, or a mixed refrigerant containing at least one of them. The refrigerant applied to the screw compressor 100 may be a natural refrigerant such as carbon dioxide.

[Explanation of operation of refrigerant circuit]
The high-temperature and high-pressure refrigerant compressed by the screw compressor 100 dissipates heat while being condensed by the condenser 101. The refrigerant condensed in the condenser 101 is branched after passing through the condenser 101, and the mainstream refrigerant is decompressed and expanded by the main decompression device 102. The refrigerant expanded by the main decompression device 102 absorbs heat while evaporating by the evaporator 103. The refrigerant evaporated in the evaporator 103 is sucked into the screw compressor 100 and compressed again. With the above, one cycle is completed.

On the other hand, the cooling refrigerant, which is the remaining refrigerant branched after passing through the condenser 101, flows into the first pipe 104 when the cooling decompression device 105 is open, is decompressed by the cooling decompression device 105, and then is decompressed. It flows into the inflow port 22a of the screw compressor 100. The cooling refrigerant that has flowed into the inflow port 22a cools the high temperature section 24 in the process of passing through the cooling hole 22, and the cooling refrigerant that has cooled the high temperature section 24 passes through the second pipe 106 as described above, and then the compression chamber. It is injected into 29.

FIG. 8 is a diagram showing changes in the evaporation temperature and the condensation temperature during one cycle of operation of the refrigerating apparatus. In FIG. 8, the portion surrounded by the dotted line indicates the operating condition portion where the discharge temperature is high. As shown in FIG. 8, the discharge temperature tends to rise transiently under the condition that the condensation temperature is high in the operating range, and the refrigerant is injected into the compression chamber 29 in order to suppress the rise in the discharge temperature. This amount of refrigerant is controlled by the cooling decompression device 105. Hereinafter, the control of the cooling decompression device 105 will be described.

FIG. 9 is a flowchart showing a control flow of the cooling decompression device of the refrigerating sill device according to the first embodiment.
In the control device 109, the discharge temperature measured by the discharge temperature sensor 107 exceeds the preset set temperature corresponding to the preset discharge temperature, or the motor frame temperature measured by the motor frame temperature sensor 108 is preset. It is determined whether or not the set temperature corresponding to the determined motor frame temperature is exceeded (step S1). When the discharge temperature or the motor frame temperature exceeds the corresponding set temperature, the control device 109 controls the cooling decompression device 105 based on the temperature that exceeds the set temperature first, and passes through the cooling hole 22. The flow rate of the refrigerant to be used is adjusted (steps S2 to S5).

Specifically, when the discharge temperature exceeds the set temperature (step S2), the control device 109 controls the cooling decompression device 105 so that the discharge temperature drops (step S3). Specifically, the control device 109 increases the opening degree of the cooling decompression device 105. On the other hand, when the motor frame temperature exceeds the set temperature (step S4), the control device 109 controls the cooling decompression device 105 so that the motor frame temperature drops (step S5). Specifically, the control device 109 increases the opening degree of the cooling decompression device 105.

Further, when the discharge temperature measured by the discharge temperature sensor 107 is equal to or lower than the set temperature corresponding to the discharge temperature and the motor frame temperature is equal to or lower than the set temperature corresponding to the motor frame temperature, the control device 109 does not need to cool the motor 4. Therefore, the opening degree of the cooling decompression device 105 is closed (step S6).

Although an example of controlling the cooling decompression device 105 based on the discharge temperature has been described here, the cooling decompression device 105 may be controlled by using the discharge superheat degree obtained by subtracting the condensation temperature from the discharge temperature. good. In short, the cooling decompression device 105 may be controlled based on an index value according to the state of the refrigerant discharged from the screw compressor 100. Specifically, when the index value exceeds the set index value, the cooling decompression device 105 may be controlled so that the discharge temperature is lowered. When the cooling decompression device 105 is controlled by using the discharge superheat degree, if a temperature type expansion valve is used for the cooling decompression device 105, it can be configured at a lower cost than when an electronic expansion valve is used. This is because the temperature type expansion valve is a mechanical type in which the opening degree of the valve is mechanically adjusted according to the measured value measured by the temperature sensitive cylinder (not shown), so that an electron requiring a control board is required. This is because the number of parts can be reduced as compared with the expansion valve.

[effect]
The screw compressor 100 of the first embodiment has a tubular casing 2, a screw rotor 3 arranged to rotate in the casing 2, and a motor 4 arranged in the casing 2 to drive the screw rotor 3. And. In the motor frame 2c, which is a portion of the casing 2 that accommodates the motor 4, a cooling hole 22 through which a refrigerant from the outside passes passes through a high temperature portion 24 whose temperature locally rises during operation, and is a rotation shaft of the screw rotor 3. It is formed so as to extend in the direction. In this way, since the cooling hole 22 is provided in the high temperature portion 24 of the motor frame 2c, the high temperature portion 24 can be centrally cooled by flowing the cooling refrigerant from the outside through the cooling hole 22. Therefore, the high temperature portion 24 and the motor 4 can be stably cooled, and a local temperature rise can be prevented. As a result, the operating range can be expanded.

The screw compressor 100 of the first embodiment is formed so as to project inward from the inner peripheral surface of the motor frame 2c, and has a holding portion 21 that contacts the outer peripheral surface of the motor 4 to hold the motor 4. A cooling hole 22 is formed in 21. By forming the cooling hole 22 in the holding portion 21 in contact with the motor 4 in this way, the motor 4 can be efficiently cooled.

A plurality of cooling holes 22 are provided in the motor frame 2c. As a result, the motor 4 can be cooled more efficiently.

The refrigerating device 110 of the first embodiment includes the above-mentioned screw compressor 100, a condenser 101, a main decompression device 102, and an evaporator 103. Further, the refrigerating device 110 is a first unit that branches from the refrigerant circuit through which the refrigerant circulates and the piping between the condenser 101 and the main depressurizing device 102 and is connected to the inflow port 22a of the cooling hole 22 of the screw compressor 100. It is provided with a pipe 104 and a cooling decompression device 105 provided in the first pipe 104 to depressurize the refrigerant passing through the first pipe 104. As described above, by providing the screw compressor 100 described above, it is possible to obtain a refrigerating apparatus capable of expanding the operating range.

The refrigerating device 110 of the first embodiment includes a control device 109 that controls a cooling decompression device 105. The control device 109 controls the cooling decompression device 105 based on the index value regarding the state of the refrigerant discharged from the screw compressor 100, or the cooling decompression device based on the motor frame temperature which is the temperature of the motor frame 2c. Control device 105. As a result, the flow rate of the cooling refrigerant flowing into the cooling hole 22 can be adjusted, and the motor 4 can be appropriately cooled.

When the index value exceeds the preset index value set in advance, the control device 109 controls the cooling decompression device 105 so that the discharge temperature, which is the temperature of the refrigerant discharged from the screw compressor 100, is lowered, and the motor frame. When the temperature exceeds a preset set temperature, the cooling decompression device 105 is controlled so that the motor frame temperature is lowered. As a result, the flow rate of the cooling refrigerant flowing into the cooling hole 22 can be adjusted, and the motor 4 can be appropriately cooled.

The index value is the discharge temperature, which is the temperature of the refrigerant discharged from the screw compressor 100, or the discharge superheat degree obtained by subtracting the condensation temperature from the discharge temperature. As described above, the discharge temperature may be used or the discharge superheat degree may be used as the index value.

The refrigerating apparatus 110 of the first embodiment includes a flow path for allowing the cooling refrigerant flowing out from the outlet 22b of the cooling hole 22 to flow into the compression chamber 29. As a result, it is possible to suppress the inconvenience that the suction refrigerant is hindered from being sucked into the compression chamber 29 by the cooling refrigerant, the amount of refrigerant circulation is reduced, and the performance is deteriorated.

Embodiment 2.
Next, the second embodiment will be described. In the first embodiment, the configuration in which the refrigerant after passing through the cooling hole 22 flows into the compression chamber 29 is shown, but in the second embodiment, the refrigerant after passing through the cooling hole 22 is used in the control device 109. After cooling the inverter, it is configured to flow into the compression chamber 29. Hereinafter, the second embodiment will be described focusing on the differences from the first embodiment, and the configurations not described in the second embodiment are the same as those in the first embodiment.

FIG. 10 is a diagram showing a configuration of a refrigerating apparatus according to a second embodiment.
The refrigerating device 110 of the second embodiment further includes a cooler 121 for cooling the control device 109 in addition to the refrigerating device 110 of the first embodiment shown in FIG. The cooler 121 has a refrigerant pipe (not shown) through which the refrigerant passes. The cooler 121 is arranged in contact with the control device 109.

The control device 109 includes an inverter (not shown), and the inverter component, which is an electronic component constituting the inverter, generates heat. A cooler 121 is used to cool the heat. After cooling the motor 4 and passing through the cooling hole 22, the refrigerant flows through the cooler 121, and the heat transferred from the inverter component to the cooler 121 is transferred to the refrigerant, so that the control device 109 can be cooled. ..

According to the second embodiment, the same effect as that of the first embodiment can be obtained, and the following effects can be obtained. The second embodiment is provided with a cooler 121 which is arranged in contact with the control device 109 and through which the refrigerant passing through the cooling hole 22 passes, so that the inverter component of the control device 109 can be cooled. As a result, it is possible to reduce the capacity of an inverter component that generates a large amount of heat, such as an IGBT or a power module, and it is possible to reduce the size and cost of the inverter component.

The refrigerant circuit is not limited to the configuration shown in FIG. 10, and for example, a thermal efficiency mechanism may be further provided in the configuration shown in FIG. As a thermal efficiency mechanism, for example, there is an intercooler that exchanges heat between the refrigerant between the condenser 101 and the cooling decompression device 105 and the refrigerant between the cooling decompression device 105 and the inflow port 22a.

2 Casing, 2a Main Casing, 2b Suction Casing, 2c Motor Frame, 3 Screw Rotor, 3a Screw Groove, 4 Motor, 4a Stator, 4b Motor Rotor, 4c Winding, 5 Rotating Shaft, 6 Gate Rotor, 6a Teeth, 8 Discharge Port , 11 main bearing, 13 auxiliary bearing, 21 holding part, 22 cooling hole, 22a inlet, 22b outlet, 23 injection hole, 24 high temperature part, 29 compression chamber, 100 screw compressor, 101 condenser, 102 main decompression device , 103 Evaporator, 104 1st pipe, 105 Cooling compressor, 106 2nd pipe, 107 Discharge temperature sensor, 108 Motor frame temperature sensor, 109 Control device, 110 Refrigeration device, 121 Cooler.

Claims

With a tubular casing
With a screw rotor arranged to rotate in the casing,
A motor disposed in the casing and driving the screw rotor is provided.
In the motor frame, which is a portion of the casing that houses the motor, a cooling hole through which an external refrigerant passes extends in the rotation axis direction of the screw rotor in a high temperature portion where the temperature locally rises during operation. Screw compressor formed in.
1. The screw compressor described.
The screw compressor according to claim 1 or 2, wherein a plurality of the cooling holes are provided in the motor frame.
A refrigerant circuit comprising the screw compressor according to any one of claims 1 to 3, a condenser, a main decompression device, and an evaporator, and in which a refrigerant circulates.
A first pipe branched from the pipe between the condenser and the main decompressor and connected to the inlet of the cooling hole of the screw compressor.
A refrigerating device provided in the first pipe and provided with a cooling decompression device for depressurizing the refrigerant passing through the first pipe.
A control device for controlling the cooling decompression device is provided.
The control device is
The cooling decompression device is controlled based on an index value relating to the state of the refrigerant discharged from the screw compressor, or the cooling decompression device is controlled based on the motor frame temperature which is the temperature of the motor frame. The refrigerating apparatus according to claim 4.
When the index value exceeds a preset index value, the control device controls the cooling decompression device so that the discharge temperature, which is the temperature of the refrigerant discharged from the screw compressor, is lowered.
The refrigerating device according to claim 5, wherein when the motor frame temperature exceeds a preset set temperature, the cooling decompression device is controlled so that the motor frame temperature is lowered.
The refrigerating device according to claim 5 or 6, wherein the index value is a discharge temperature which is the temperature of the refrigerant discharged from the screw compressor, or a discharge superheat degree obtained by subtracting the condensation temperature from the discharge temperature.
The refrigerating apparatus according to any one of claims 5 to 7, further comprising a flow path for allowing the refrigerant flowing out from the outlet of the cooling hole to flow into the compression chamber of the refrigerant provided in the screw compressor.
The refrigerating device according to any one of claims 5 to 8, which is arranged in contact with the control device and includes a cooler through which the refrigerant passing through the cooling hole of the screw compressor passes.