JP2015042847A - Screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw compressor of high efficiency and high reliability by cooling an oil supplied to a bearing and a compression operation chamber with a simple structure.SOLUTION: A screw compressor includes a screw rotor composed of a tooth portion and a shaft portion, a motor mounted on the shaft portion of the screw rotor, a motor casing 1 accommodating the motor and provided with a refrigerant flow channel and a suction port 5, a bearing for supporting the screw rotor, a main casing 2 having a suction port opened to the screw rotor, a discharge casing 3 having a discharge port, an oil separator 4 for discharging a discharge gas, and an oil reservoir disposed at a lower portion of the separator. An oil flow channel is formed inside of the motor casing in a state that the motor casing 1 and a stator are positioned within an inscribed range. The oil in the oil reservoir is supplied to the oil flow channel, and then the oil is supplied to the bearing.

Description

  The present invention relates to a screw compressor used in a refrigeration apparatus such as an air conditioner or a refrigerator.

  When a screw compressor is used as a conventional screw compressor in a refrigerating apparatus such as an air conditioner or a refrigerator, the liquid refrigerant circulating in the refrigeration cycle is bypassed, and heat exchange is performed between the liquid refrigerant and oil circulating in the compressor. However, there are some which cool oil (for example, refer to patent documents 1).

  The refrigeration apparatus described in Patent Document 1 includes a refrigerant circulation cycle in which a screw compressor, an oil separator, a condenser, a decompression device, and an evaporator are connected via a refrigerant pipe, and an oil cooler from the oil separator. , An oil supply passage leading to the bearing portion in the compressor, the screw rotor, and a refrigerant branch passage that bypasses the liquid refrigerant partially from the refrigerant pipe at the outlet of the decompression device and reaches the screw rotor via the expansion valve and the cooling rod . In the oil cooler, the high-temperature oil from the oil separator and the cold refrigerant bypassed from the branch flow path are heat-exchanged to cool the high-temperature oil, and the cooled oil is guided to the screw rotor and the bearing portion.

Japanese Patent Laid-Open No. 3-79959

  In the screw compressor of Patent Document 1, high-temperature oil from the oil separator and liquid refrigerant bypassed from the refrigerant pipe at the outlet of the decompression device are led to an oil cooler provided separately for heat exchange. However, when the liquid refrigerant is bypassed in order to cool the high-temperature oil, an expansion valve that depressurizes the liquid refrigerant and a heat exchanger that houses the cooling pipe are required, and the cycle configuration becomes complicated. Furthermore, since heat exchange is performed with a refrigerant having a low temperature, there is a possibility of performance degradation due to oil supercooling.

  An object of the present invention is to provide a highly efficient and highly reliable screw compressor by cooling oil supplied to a bearing and a compression working chamber with a simple structure.

  The screw compressor of the present invention includes a screw rotor that compresses a refrigerant, a motor that drives the screw rotor, a bearing that supports the screw rotor, a screw rotor, a motor, a casing that houses the bearing, and a discharge from the screw rotor. An oil separator that separates the refrigerant into refrigerant gas and oil, and a heat exchanger that is formed integrally with the casing, and the oil separated by the oil separator passes through an oil passage in the heat exchanger. Supplied to the bearing.

  ADVANTAGE OF THE INVENTION According to this invention, the oil supplied to a bearing or a compression working chamber can be cooled with a simple structure, and a highly efficient and highly reliable screw compressor can be provided.

Diagram showing the appearance of screw compressor Longitudinal sectional view in FIG. Cross section in FIG. III-III arrow cross-sectional view in FIG. Oil system diagram showing oil flow A figure corresponding to FIG. 3 of the modified example IV-IV arrow cross-sectional view in FIG.

  The screw compressor of this embodiment includes a screw rotor that compresses a refrigerant, a motor that drives the screw rotor, a bearing that supports the screw rotor, a screw rotor, a motor, a casing that houses the bearing, and a screw rotor. An oil separator that separates the discharged refrigerant into refrigerant gas and oil, and a heat exchanger that is formed integrally with the casing, and the oil separated by the oil separator passes through an oil passage in the heat exchanger And supplied to the bearing. Since the oil separated by the oil separator is supplied to the bearing via the oil flow path in the heat exchanger formed in the casing, the oil supplied to the bearing and the compression working chamber can be cooled with a simple structure. A highly efficient and reliable screw compressor can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the appearance of a screw compressor. FIG. 2 is a longitudinal sectional view in FIG. FIG. 3 is a cross-sectional view in FIG. 4 is a cross-sectional view taken along the line III-III in FIG. FIG. 5 is an oil system diagram showing the flow of oil. FIG. 6 shows a modification of the present embodiment and corresponds to FIG. 7 is a cross-sectional view taken along the line IV-IV in FIG.

  1 to 5, the screw compressor includes a compressor main body 70, motors (electric motors) 7 and 8 that drive the compressor main body 70, and a motor casing 1 that houses the motors 7 and 8. The motor casing 1 has a refrigerant flow path 11 formed outside the motors 7 and 8, and gas flows into the refrigerant flow path 11 from the suction port 5 through the strainer 30 and the suction chamber (low pressure chamber) 10. .

  The refrigerant gas compressed by the compressor main body 70 flows into the discharge chamber (high pressure chamber) 13 formed in the discharge casing 3 through the discharge port 14. The discharge chamber 13 is connected to the oil separator 4 formed integrally with the compressor body 70. The refrigerant gas flowing into the oil separator 4 from the discharge chamber 13 separates the refrigerant gas compressed by the compressor body 70 and the oil. The separated gas is supplied from the discharge port 6 of the compressor body 70 to the outside (for example, a condenser constituting a refrigeration cycle). On the other hand, the separated oil is stored in an oil sump 10 provided at the lower part of the oil separator, and bearings 20 and 21 provided in the main casing 2 and bearings 22, 23 and 24 provided in the discharge casing 3. , 25. The oil supplied to the bearings 20 and 21 disposed in the main casing 2 lubricates the bearings 20 and 21 and is discharged to the suction port 12 formed in the main casing. The oil supplied to the bearings 22, 23, 24, and 25 disposed in the discharge casing 3 is discharged into a compression working chamber formed by the male rotor 9A and the female rotor 9B.

  The motors 7 and 8 house the rotor 8 attached to the suction side shaft portion of the male rotor 9A, the stator 7 disposed on the outer peripheral side of the rotor 8, and the rotor 8 and the stator 7. A motor casing 1.

  The compressor main body 70 includes a male rotor 9A and a female rotor 9B that rotate while being parallel to each other with their rotation axes parallel to each other, a main casing 2 that houses the teeth of the male rotor 9A and the female rotor 9B, and a rotor shaft of the main casing 2 And a discharge casing 3 connected to the direction discharge side (right side in FIG. 2).

  A motor casing 1 is connected to the suction side (left side in FIG. 2) of the main casing 2 in the rotor axial direction, and a refrigerant flow path 11 from the suction chamber 10 to the main casing 2 is formed inside the motor casing 1. The

  The suction side shaft portion of the male rotor 9 </ b> A is supported by a roller bearing 20 disposed in the main casing 2, and the discharge side shaft portion is supported by a roller bearing 22 and a ball bearing 24 disposed in the discharge casing 3. Similarly, the suction side shaft portion of the female rotor 9B is supported by a roller bearing 21 disposed in the main casing 2, and the discharge side shaft portion is supported by a roller bearing 23 and a ball bearing 25 disposed in the discharge casing 3. The Further, the suction side shaft portion of the male rotor 9 </ b> A is directly connected to the rotation shafts of the motors 7 and 8. The male rotor 9A is rotated by driving the motors 7 and 8, and the female rotor 9B is rotated while meshing with the male rotor 9A.

  The main casing 2 has cylindrical bores 15 and 16 that house the teeth of the male rotor 9A and the female rotor 9B. Compression working chambers are formed in the tooth grooves of the male rotor 9A and the female rotor 9B. The main casing 2 is formed with a suction port 12 that communicates the inside of the motor casing 1 with the compression working chamber of the intake stroke. The main casing 2 is formed with a discharge port 14 on the male rotor 9A side and a discharge port on the female rotor 9B side which are located on the outer side in the rotor radial direction (upper side in FIG. 2) with respect to the compression working chamber of the exhaust stroke.

  The discharge casing 3 is in contact with the end surface of the main casing 2 and covers the openings of the bores 15 and 16, the discharge port on the male rotor 9A side and the discharge port on the female rotor 9B side formed on the discharge side end surface. And a discharge chamber 13 through which compressed gas from the compression working chamber is discharged through the discharge port 14.

  In such a screw compressor, the refrigerant gas flows into the suction chamber 10 from the suction port 5 and passes through the refrigerant flow path 11 of the motor casing 1 (while cooling the rotor 8 and the stator 7). Flows into the second suction port 12. Along with the rotation of the male rotor 9A and the female rotor 9B, the volume of the compression working chamber is reduced while moving in the rotor axial direction, and the refrigerant gas is compressed. The refrigerant gas compressed in the compressor working chamber flows into the oil separator 4 through the discharge port 14 and the discharge chamber 13, is separated from the oil by the oil separator 4, and then is supplied to the outside from the discharge port 6. The

  Here, the heat exchanger 41 is integrally formed in the motor casing 1 of the screw compressor of the present embodiment. The heat exchanger 41 is disposed in the motor casing 1 radially outside the contact position between the motor casing 1 and the motor stator 7 (position where the motor casing 1 supports the motor stator 7) (that is, the motor casing 1 and the motor The refrigerant flow path 11 is not located between the stator 7). A plurality of fins 40 are formed on the outer surface of the heat exchanger 41.

  An oil passage 52 is formed inside the heat exchanger 41, and oil pipes 50 and 51 are connected to the oil passage 52. The oil pipe 50 is connected to the oil sump 10 via the cover 31 and supplies oil from the oil sump 10 to the heat exchanger 41. The oil pipe 51 is connected to an oil passage 70 formed in the main casing 2, and the oil cooled by the heat exchanger 41 is discharged to the suction port 12 after lubricating the bearings 21 and 20. The oil pipe 51 is also connected to an oil passage 71 formed in the discharge casing 3, and after lubricating the bearings 22, 23, 24, 25, the tooth grooves and the bores 15 of the male rotor 9 </ b> A and the female rotor 9 </ b> B. , 16 are discharged into a compression working chamber.

  The screw compressor configured as described above operates as follows. That is, the hot oil in the oil sump 10 flows into the heat exchanger 41 provided integrally with the motor casing 1. The oil that has flowed into the heat exchanger 41 flows through the oil flow path 52 into the heat exchanger 41. In this process, heat exchange is performed between the oil flow path 52 of the heat exchanger 41 formed in the motor casing 1 and the external air (that is, the oil flowing through the oil flow path 52 and the external air between the motor casing 1 and the external air). It also functions as a heat exchanger for exchanging heat.) In particular, in this embodiment, a plurality of radiating fins are formed integrally with the motor casing on the outer surface of the heat exchanger 41, and heat dissipation is promoted through the radiating fins. Since the surface area in contact with the outside air can be increased, the oil can be cooled efficiently. Thus, when the oil temperature is higher than the air temperature, the oil temperature decreases due to heat exchange, and the intake oil temperature decreases due to heat exchange between the cooled oil and the refrigerant gas. Since the density increases, the refrigerant circulation rate increases and the performance improves.

  Furthermore, power is reduced by supplying cooled oil to the compression working chamber. Further, since the thermal deformation of the screw rotors 9A and 9B is reduced, leakage from the gap between the meshing portions of the male rotor 9A and the female rotor 9B is reduced. And since the viscosity of oil increases, the leak from the clearance gap between compression working chambers can be reduced. These effects improve the performance of the screw compressor.

  In addition, when the oil temperature is lower than the air temperature, the oil temperature rises due to heat exchange with the air, so the viscosity of the oil is reduced and the oil stirring loss inside the bearing is reduced. improves.

  Here, the position of the heat exchanger 41 is formed in the motor casing 1 radially outside the position where the motor casing 1 and the motor stator 7 are in contact (the refrigerant flow between the motor casing 1 and the motor stator 7). Since the path 11 is not located), the distance between the oil flow path 52 and the refrigerant flow path 11 in the heat exchanger 41 can be increased. Therefore, overheating of the refrigerant gas flowing through the refrigerant flow path 11 due to the heat of the oil flowing through the oil flow path 52 can be suppressed.

  Here, the surface area of the flow path 52 in the heat exchanger 41 can be increased by branching the oil flow path 52 provided in the heat exchanger 41 into a plurality of (multipath), and the flow path 52 Therefore, the heat exchanger 41 can be downsized.

  In addition, in the present Example, although the heat exchanger 41 was arrange | positioned in the motor casing 1 of the radial direction outer side of the contact position of the motor casing 1 and the motor stator 7, it is not restricted to this. That is, for example, as shown in FIGS. 6 and 7, a heat insulating material 60 may be disposed between the refrigerant flow path 11 provided in the motor casing 1 and the oil flow path 52 inside the motor casing 1. By disposing the heat insulating material 60 between the refrigerant flow path 11 and the oil flow path 52 inside the motor casing 1, the heat of the oil flow path 52 is blocked by the heat insulating material 60, and the gas flowing through the refrigerant flow path 11 is converted into gas. It becomes difficult to transfer heat.

1: Motor casing 2: Main casing 3: Discharge casing 4: Oil separator 5: Suction port 6: Discharge port 31: Cover 40: Fin 41: Heat exchanger 50: Oil piping 51: Oil piping 70: Compressor body

Claims (5)

A screw rotor for compressing the refrigerant;
A motor for driving the screw rotor;
A bearing for supporting the screw rotor;
A casing for housing the screw rotor, the motor, and the bearing;
An oil separator that separates refrigerant discharged from the screw rotor into refrigerant gas and oil;
A heat exchanger formed integrally with the casing;
With
A screw compressor in which oil separated by the oil separator is supplied to the bearing via an oil flow path in the heat exchanger. In Claim 1, the motor is supported by the casing, and a refrigerant flow path that guides the refrigerant sucked into the casing to the screw rotor is formed between the casing and the motor.
A screw compressor in which the heat exchanger is formed on a radially outer side of a position where the casing supports the motor. In Claim 1, the motor is supported by the casing, and a refrigerant flow path that guides the refrigerant sucked into the casing to the screw rotor is formed between the casing and the motor.
The heat exchanger is formed radially outside the refrigerant flow path;
A screw compressor in which a heat insulating material is disposed between the refrigerant channel and the oil channel.   4. The screw compressor according to claim 1, wherein the oil flow path is branched into a plurality of parts.   The screw compressor according to any one of claims 1 to 4, comprising a radiation fin integrally formed on a surface of the heat exchanger.