JP2008121479A - Hermetic screw compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a hermetic screw compressor capable of entirely preventing flowing out of high temperature oil supplied to a low pressure side bearing to low pressure side (motor side), and is easy in maintenance. <P>SOLUTION: The hermetic screw compressor is equipped with a male rotor 16, a female rotor 17 engaging with the male rotor, a motor 4 connected with a low pressure side shaft part 27 of the male rotor, low pressure side bearings 9, 10, supporting the low pressure side shaft part of each of the rotors, respectively, high pressure side bearings supporting high pressure side shaft part of each of the rotors, respectively, and casings 1, 2, 3 to accommodate them. A contact type sealing arrangement 24 sealing the shaft part between the low pressure side bearing of the low pressure side bearing part of the male rotor and the motor is arranged, the contact type sealing arrangement is built in within a cover 25 detachable in the axial direction with respect to the casing, and is attached to the casing through the cover. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hermetic screw compressor used for an air conditioner or a refrigerator.

  The hermetic screw compressor includes a screw rotor, a low-pressure side bearing that supports the screw rotor, a high-pressure side bearing, an electric motor that drives the screw rotor, and a casing that houses them. The electric motor can be arranged on either the low pressure side or the high pressure side, but if arranged on the low pressure side, the electric motor that generates heat with the low-temperature and low-pressure refrigerant gas can be cooled, and thus the electric motor is often arranged on the low pressure side.

  Further, it is necessary to supply oil in order to lubricate the bearing, and in a screw compressor, it is common to supply oil using a differential pressure between the low pressure side and the high pressure side. In the differential pressure lubrication, high temperature and high pressure oil in the discharge gas atmosphere is supplied to the bearing that supports the screw rotor, so that the oil that lubricated the low pressure side bearing among the bearings is an electric motor arranged on the low pressure side. Since the oil flows out, the insulating material of the motor is overheated with oil and deteriorates. Furthermore, since the high-temperature oil that has flowed out is mixed with low-temperature and low-pressure refrigerant gas and sucked into the tooth groove portion of the screw rotor, the low-temperature refrigerant gas is overheated with oil and the compression function is reduced. It was.

  For this reason, Patent Document 1 discloses that a non-contact seal structure is employed between the electric motor and the low-pressure side bearing for the purpose of preventing oil outflow from the low-pressure side bearing to the low-pressure side (motor side).

Japanese Laid-Open Patent Publication No. 2-275086 (FIG. 5)

  In the above-mentioned patent document, a non-contact type seal structure is adopted, but the non-contact type seal is sealed only by the viscous frictional resistance and bending resistance of the fluid, so that the sealing performance is inferior and the oil spills. It was found that a sufficient effect cannot be expected to prevent this.

  In order to reduce the oil spill, the use of contact-type sealing means was considered. However, as the compressor operation time elapses, the seal part or the counterpart shaft part wears, so that maintenance is necessary. It was difficult to adopt a shape seal.

  An object of the present invention is to obtain a hermetic screw compressor that can sufficiently prevent the high temperature oil supplied to the low pressure side bearing from flowing out to the low pressure side (motor side) and is easy to maintain. .

  In order to achieve the above object, the first feature of the present invention is that a screw rotor having a tooth profile portion, a low pressure side shaft portion and a high pressure side shaft portion, an electric motor connected to the low pressure side shaft portion of the screw rotor, In a hermetic screw compressor comprising a low-pressure side bearing that supports a low-pressure side shaft portion, a high-pressure side bearing that supports the high-pressure side shaft portion, and a casing that hermetically houses them, the low-pressure side of the low-pressure side shaft portion A contact-type sealing device that seals the shaft portion between the bearing and the electric motor is disposed. The contact-type sealing device is built in a cover that can be attached to and detached from the casing, and is attached to the casing via the cover. There is in being.

  Here, it is more preferable that a sleeve having a hardness higher than that of the low-pressure side shaft portion is fitted into a portion of the low-pressure side shaft portion that slides with the contact-type sealing device.

  The screw rotor may include at least a pair of a male rotor and a female rotor that mesh with each other. Alternatively, the screw rotor may be composed of a screw rotor and a gate rotor that mesh with each other.

  The second feature of the present invention is that a screw rotor having a screw-shaped tooth profile and a rotor shaft integrally formed therewith, an electric motor connected to the rotor shaft and rotationally driving the screw rotor, and the rotor shaft In a hermetic screw compressor including a low-pressure side bearing that supports a suction side, a high-pressure side bearing that supports a discharge side of the rotor shaft, and a casing that houses these, a space between the low-pressure side bearing and the motor A contact-type sealing device provided to seal the rotor shaft of the motor, and a bearing retainer for holding the low-pressure side bearing in the axial direction with respect to the casing. The contact-type sealing device is provided on the bearing retainer. It has a built-in configuration and is attached to the casing via the bearing retainer.

  Here, it is more preferable that a sleeve having a higher hardness than the rotor shaft is fitted into a portion of the rotor shaft that slides with the contact-type sealing device.

  According to a third aspect of the present invention, a male rotor, a female rotor meshing with the male rotor, an electric motor connected to the low-pressure side shaft portion of the male rotor, and the low-pressure side shaft portion of each rotor are supported. In a hermetic screw compressor including a low-pressure side bearing, a high-pressure side bearing that supports a high-pressure side shaft portion of each of the rotors, and a casing that houses them, the low-pressure side bearing of the low-pressure side shaft portion of the male rotor A contact-type sealing device that seals the shaft between the motor and the electric motor is disposed, and the contact-type sealing device is built in a cover that can be attached to and detached from the casing in the axial direction, and is attached to the casing via the cover. Further, a sleeve having a higher hardness than that of the low-pressure side shaft portion is fitted into a portion of the low-pressure side shaft portion that slides with the contact-type sealing device.

  Here, the low-pressure side shaft portion and the high-pressure side shaft portion may be integrated with each rotor, and the low-pressure side shaft portion of the male rotor may be directly connected to the motor and driven.

  The contact-type sealing device may be composed of an oil seal or a mechanical seal.

  According to the present invention, the contact-type sealing device that seals the shaft portion between the low-pressure side bearing of the low-pressure side shaft portion and the electric motor is disposed, and this contact-type sealing device is built in the cover that can be attached to and detached from the casing. Since it is configured to be attached to the casing via the cover, a high-performance and highly reliable hermetic screw compressor that prevents high-temperature and high-pressure oil from flowing out to the low-pressure side and has excellent maintainability. Can be obtained.

In order to prevent oil leakage from the low-pressure side bearing to the low-pressure side (motor side), if a contact-type seal device is used between the motor and the low-pressure side bearing, the sealing performance can be greatly improved. Since the seal portion or the counterpart shaft portion wears over time, maintenance is required. According to the present invention, a contact-type sealing device is arranged inside a screw compressor, and a high-performance and highly reliable hermetic screw compressor having easy maintenance and easy maintenance is obtained.
Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a sectional view of a hermetic screw compressor according to an embodiment of the present invention. In the following description, an example in which the present invention is implemented in a hermetic twin screw compressor will be described. The present invention can be similarly applied to a single screw type.

  The hermetic screw compressor includes a motor casing 1, a main casing 2, and a discharge casing 3 that are connected to each other in a sealing relationship. The motor casing 1 houses a drive motor 4 for driving the compression mechanism. The main casing 2 is formed with cylindrical bores 5 and 6 and suction ports 7 and 8 for introducing refrigerant gas into the cylindrical bores 5 and 6. In the cylindrical bores 5 and 6, a male rotor 16 and a female rotor 17 rotatably supported by roller bearings 9, 10, 11, 12, 13 and ball bearings 14 and 15 are meshed with each other and stored. The shaft 16 is directly connected to the drive motor 4 on the low pressure side. The main casing 2 is integrally formed with an oil separator 18 and an oil sump 19 for storing lubricating oil.

  The discharge casing 3 that houses the roller bearings 11 and 13 and the ball bearings 14 and 15 is formed with a refrigerant gas discharge passage (not shown) that communicates with an oil separator 18 that is integrated with the main casing 2. The discharge casing 3 is fixed to the main casing 2 by means such as bolts. A shield plate 22 is attached to one end of the discharge casing 3 to close the bearing chambers 20 and 21 that house the roller bearings 11 and 13 and the ball bearings 14 and 15.

  An oil supply passage is formed in the main casing 2 and the discharge casing 3, and the oil sump 19 configured in the main casing 2 is communicated with each bearing portion.

Next, the flow of refrigerant gas and oil will be described.
The low-temperature and low-pressure refrigerant gas sucked from the suction port 29 provided in the motor casing 1 is a gas passage provided between the drive motor 4 and the motor casing 1 after foreign matter is collected by the strainer 30; And the motor 4 for a drive is cooled through the air gap between the stator 4a and the motor rotor 4b. The cooled refrigerant gas is sucked into the compression chamber formed by the meshing tooth surfaces of the male and female screw rotors and the main casing 2 from the suction ports 7 and 8 formed in the main casing 2. Thereafter, the male rotor 16 connected to the driving motor 4 is rotated and sealed with the meshing tooth surfaces of the male and female screw rotors and the compression chamber formed by the main casing 2, and gradually compressed by the reduction of the compression chamber, It becomes high-temperature and high-pressure refrigerant gas, passes through a discharge passage (not shown) formed in the discharge casing 3, and is discharged into an oil separator 18 configured integrally with the main casing 2. Of the compression reaction force acting on the male and female screw rotors during compression, the radial load is supported by the roller bearings 9, 10, 11, 12, and 13, and the thrust load is supported by the ball bearings 14 and 15. Oil for lubrication and cooling of these bearings is supplied from an oil sump 19 provided at a high pressure portion in the main casing 2 through an oil passage communicating with each bearing portion, and is supplied by differential pressure, and separated with compressed refrigerant gas. It is discharged into the container 18. The oil contained in the compressed refrigerant gas is separated by the oil separator 18 and stored in an oil sump 19 configured integrally with the main casing 2. After oil separation, the compressed refrigerant gas is discharged from a discharge port provided in the main casing 2.

  FIG. 2 is a partially enlarged view of the vicinity of the low-pressure side bearings 9, 10, 12 shown in FIG. The oil supplied from the oil sump 19 provided in the high pressure portion lubricates the roller bearings 11 and 13 and the ball bearings 14 and 15 disposed on the high pressure side through the oil passage 23a. On the other hand, a portion of the oil that has passed through the oil passage 23b is supplied to the roller bearing 12 that is disposed on the low pressure side and supports the female rotor 17, and the remaining oil passes through the oil passages 23c and 23d to reach the low pressure side. The roller bearings 9 and 10 that are arranged and support the male rotor 16 are lubricated.

  Conventionally, the oil after lubricating the bearing has been discharged toward the drive motor 4 disposed on the low pressure side, but the oil is supplied from the oil sump 19 provided in the high pressure portion using the differential pressure. The high temperature and high pressure oil is in a state of high temperature and high pressure, so that the high temperature and high pressure oil overheats and degrades the insulating material of the drive motor 4, and further, the low temperature and low pressure refrigerant gas sucked from the suction port is overheated by this oil. Since the volume expands and the refrigerant circulation rate decreases, the compression function is reduced.

  In this embodiment, the contact seal 24 is disposed between the low-pressure roller bearings 9 and 10 and the drive motor 4. Here, an oil seal is employed as the contact seal 24. Further, the contact seal 24 is built in the bearing cover 25, and the bearing cover 25 is attached to the main casing 2. As a result, high-temperature and high-pressure oil can be prevented from flowing out to the low-pressure side, and the insulating material of the drive motor 4 and the low-temperature and low-pressure refrigerant gas are not overheated by the oil, thereby obtaining high performance and reliability. It becomes possible. The oil after lubrication passes through the oil passage 23e and flows into the compression chamber. Further, since the contact-type seal 24 is built in the removable bearing cover 25, even if the seal portion of the contact-type seal 24 is worn with the passage of the compressor operating time, the contact cover 25 can be removed by removing the bearing cover 25. The shape seal 24 can be easily maintained.

FIG. 3 is a diagram illustrating the second embodiment and corresponds to FIG.
In this embodiment, the sleeve 26 is fitted into the low pressure side shaft portion 27 of the male rotor 16. When an oil seal is used for the contact-type seal 24, rubber or plastic is used for the material of the seal part, and steel or cast iron is used for the material of the mating shaft, so the seal part will wear with the passage of compressor operating time. Is normal. However, when foreign matter such as iron powder is caught in the seal portion, the counterpart shaft may be worn. In this case, it is necessary to replace the male rotor 16 at the time of maintenance, and the maintenance cost becomes high. In this embodiment, since the sleeve 26 is fitted into the low pressure side shaft portion 27 and the hardness of the sleeve 26 is higher than that of the low pressure side shaft portion 27, the sleeve 26 is not easily worn, and even if the sleeve 26 is worn. Since it is only necessary to replace the sleeve 26, the maintainability is improved and the maintenance cost can be reduced.

FIG. 4 is a diagram illustrating the third embodiment and corresponds to FIG.
In this embodiment, the contact type seal is constituted by a mechanical seal 28. The mechanical seal 28 has a more complicated structure than the oil seal, but it can obtain a higher sealing performance and can greatly reduce the possibility of high temperature and high pressure oil flowing out to the low pressure side. A highly reliable hermetic screw compressor can be obtained.

1 is a longitudinal sectional view of a hermetic screw compressor showing an embodiment of the present invention. The partial expanded sectional view of the low pressure side bearing vicinity shown in FIG. FIG. 5 is a diagram illustrating a second embodiment of the present invention and corresponding to FIG. 2. FIG. 6 is a diagram illustrating a third embodiment of the present invention and corresponding to FIG. 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Motor casing, 2 ... Main casing, 3 ... Discharge casing, 4 ... Drive motor, 4a ... Stator, 4b ... Motor rotor, 5, 6 ... Cylindrical bore, 7, 8 ... Suction port, 9, 10, 11, DESCRIPTION OF SYMBOLS 12, 13 ... Roller bearing, 14, 15 ... Ball bearing, 16 ... Male rotor, 17 ... Female rotor, 18 ... Oil separator, 19 ... Oil sump, 20, 21 ... Bearing chamber, 22 ... Shield plate, 23a, 23b , 23c, 23d, 23e ... oil passage, 24 ... contact seal, 25 ... bearing cover, 26 ... sleeve, 27 ... low pressure side shaft, 28 ... mechanical seal, 29 ... suction port, 30 ... strainer.

Claims (10)

A screw rotor having a tooth profile portion, a low pressure side shaft portion, and a high pressure side shaft portion, an electric motor connected to the low pressure side shaft portion of the screw rotor, a low pressure side bearing supporting the low pressure side shaft portion, and the high pressure side shaft In a hermetic screw compressor provided with a high-pressure side bearing and a casing for hermetically storing them when supporting the part,
A contact-type seal device that seals a shaft portion between the low-pressure side bearing of the low-pressure side shaft portion and the electric motor is disposed, and the contact-type seal device is built in a cover that can be attached to and detached from the casing. A hermetic screw compressor, which is attached to the casing via a screw.   2. The hermetic screw compressor according to claim 1, wherein a sleeve having a hardness higher than that of the low-pressure side shaft portion is fitted into a portion of the low-pressure side shaft portion that slides with the contact-type sealing device.   2. The hermetic screw compressor according to claim 1, wherein the screw rotor includes at least a pair of a male rotor and a female rotor that mesh with each other.   2. The hermetic screw compressor according to claim 1, wherein the screw rotor includes a screw rotor and a gate rotor that mesh with each other. A screw rotor having a screw-like tooth profile portion and a rotor shaft integrally formed therewith, an electric motor connected to the rotor shaft to rotationally drive the screw rotor, and a low-pressure side bearing supporting the suction side of the rotor shaft; In a hermetic screw compressor comprising a high-pressure side bearing that supports the discharge side of the rotor shaft, and a casing that stores these bearings,
A contact-type sealing device provided to seal a rotor shaft between the low-pressure side bearing and the electric motor;
A bearing retainer for holding the low-pressure side bearing in the axial direction with respect to the casing;
The contact-type sealing device is configured to be incorporated in the bearing retainer, and is attached to the casing via the bearing retainer.   6. The hermetic screw compressor according to claim 5, wherein a sleeve having a hardness higher than that of the rotor shaft is fitted into a portion of the rotor shaft that slides with the contact type sealing device. A male rotor, a female rotor meshing with the male rotor, an electric motor connected to the low pressure side shaft portion of the male rotor, a low pressure side bearing supporting the low pressure side shaft portion of each rotor, and In a hermetic screw compressor including a high-pressure side bearing that supports each of the high-pressure side shaft portions, and a casing that stores them.
A contact-type sealing device that seals the shaft portion between the low-pressure side bearing of the low-pressure side shaft portion of the male rotor and the electric motor is disposed, and this contact-type sealing device is a cover that can be attached to and detached from the casing in the axial direction. The sleeve is attached to the casing via the cover, and a sleeve having a higher hardness than the low-pressure side shaft portion is fitted into a portion that slides with the contact-type sealing device of the low-pressure side shaft portion. A hermetic screw compressor characterized by that.   8. The hermetic seal according to claim 7, wherein the low-pressure side shaft portion and the high-pressure side shaft portion are integrally formed with each rotor, and the low-pressure side shaft portion of the male rotor is directly connected to the motor and driven. Shape screw compressor.   9. The hermetic screw compressor according to claim 1, wherein the contact-type sealing device is an oil seal.   9. The hermetic screw compressor according to claim 1, wherein the contact-type sealing device is a mechanical seal.

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