CN215762308U - Compressor and refrigerator provided with same - Google Patents

Abstract

The utility model provides a compressor and a refrigerator with the same. A compressor (1) for compressing a refrigerant gas in a refrigerator is provided with: an impeller (11); a rotating body (12) that can rotate integrally with the impeller (11); a rolling bearing (25) that rotatably supports the rotating body (12); a lubricant held in the rolling bearing (25); a bearing housing (35) that forms a bearing chamber (31) in which the rolling bearing (25) is disposed; a gas supply passage (51) which communicates with the bearing chamber (31) and supplies the refrigerant gas compressed by the compressor (1) into the bearing chamber (31); and a communication flow path (45) which communicates with a space outside the bearing chamber (31) and communicates with a region having a pressure lower than the pressure in the bearing chamber (31).

Description

Compressor and refrigerator provided with same

Technical Field

The present invention relates to a compressor used in a refrigerator, and more particularly to a lubricating structure for a bearing of the compressor.

Background

A compression type refrigerator used in a refrigerating and air-conditioning apparatus or the like is configured as a hermetic system in which a refrigerant is sealed. A compression refrigerator is generally configured by connecting an evaporator that takes heat from a fluid to be cooled and evaporates a refrigerant to exhibit a refrigeration effect, a compressor that compresses a refrigerant gas evaporated by the evaporator to generate a high-pressure refrigerant gas, and a condenser that cools and condenses the high-pressure refrigerant gas with a cooling fluid by refrigerant pipes.

The compressor is provided with: an impeller for compressing a refrigerant gas; and a bearing for supporting the rotating body to which the impeller is fixed. In order to suppress the hot sticking and wear of the bearing, the bearing is lubricated with oil. The oil is generally selected to be compatible with the refrigerant liquid. The compression refrigerator has a sealed structure as a whole, and oil leaking to the refrigerant flow path circulates in the refrigerator together with the refrigerant liquid in a state of being dissolved in the refrigerant liquid.

Patent document 1: japanese patent laid-open No. 2008-14577

However, in order to reuse the oil dissolved in the refrigerant liquid for lubrication of the bearings, a structure for separating the oil from the refrigerant liquid and supplying the separated oil to the bearings is required, and the structure of the entire refrigerator becomes complicated. Further, when the oil is mixed with the refrigerant liquid, the viscosity of the oil decreases, and the lubricating performance of the oil decreases. Further, the oil adheres to the heat exchanger of the evaporator, hindering heat transfer. Further, when the refrigerant liquid is vaporized, the oil becomes bubbles, and the liquid oil cannot be supplied to the bearings, and as a result, the lubrication of the bearings becomes insufficient.

SUMMERY OF THE UTILITY MODEL

Accordingly, the present invention provides a compressor having a structure in which a lubricant is not mixed with a refrigerant liquid, and a refrigerator having the compressor.

In one aspect, a compressor for compressing a refrigerant gas in a refrigerator includes: an impeller; a rotating body that is rotatable integrally with the impeller; a rolling bearing that rotatably supports the rotating body; a lubricant retained within the rolling bearing; a bearing housing forming a bearing chamber in which the rolling bearing is disposed; a gas supply passage communicating with the bearing chamber and configured to supply the refrigerant gas compressed by the compressor into the bearing chamber; and a communication flow path that communicates with a space outside the bearing chamber and communicates with a region of a pressure lower than the pressure in the bearing chamber.

The rolling bearing is disposed in a bearing chamber filled with compressed refrigerant gas (i.e., high-pressure refrigerant gas). Since the pressure in the bearing chamber is higher than the pressure in the space outside the bearing chamber, the refrigerant liquid present outside the bearing chamber cannot enter the bearing chamber and does not come into contact with the lubricant held by the rolling bearing. As a result, the lubricant does not mix with the refrigerant liquid, and the refrigerant liquid and the lubricant can perform their respective functions. Further, since an oil circulation line for supplying lubricating oil to the rolling bearing can be omitted, the structure can be significantly simplified. Further, since leakage of oil to the refrigerant side does not occur, a mechanism for separating oil from the refrigerant is not necessary.

In one aspect, the bearing device further includes a seal member that seals a gap between the bearing housing and the rotating body.

The seal can minimize leakage of refrigerant gas from the bearing chamber. As a result, the pressure difference between the inside and the outside of the bearing chamber becomes large, and the refrigerant liquid can be reliably prevented from entering the bearing chamber.

In one aspect, the compressor further includes a pressure equalizing passage that connects two spaces facing both sides of the rolling bearing, the two spaces being located in the bearing chamber.

The pressure equalizing passage can equalize the pressure of the refrigerant gas on both sides of the rolling bearing. Therefore, the lubricant can be prevented from being displaced or flowing out due to the pressure difference.

In one embodiment, the pressure equalizing passage is formed in the rotating body.

In one form, the pressure equalizing passage is formed in the bearing housing.

In one embodiment, the pressure equalizing passage is connected to the bearing housing.

In one aspect, the rolling bearing includes a plurality of rolling elements and lubricant retaining rings disposed on both sides of the plurality of rolling elements.

The lubricant retaining ring has a function of retaining lubricant inside the rolling bearing. Therefore, the lubricant retaining ring can not only maintain the performance of the rolling bearing, but also prevent the lubricant from mixing in the refrigerant liquid.

In one embodiment, the lubricant is a semi-fluid lubricant.

Unlike fluid oil, semi-fluid lubricant (e.g., grease) is difficult to flow out of the rolling bearing. Therefore, an oil circulation mechanism, which has been conventionally required, can be eliminated.

In one aspect, there is provided a refrigerator that circulates a refrigerant inside, the refrigerator including: an evaporator that evaporates a refrigerant liquid to generate a refrigerant gas; the compressor described above, which compresses the refrigerant gas; and a condenser that condenses the compressed refrigerant gas to generate the refrigerant liquid.

According to the present invention, a compressor in which a lubricant is not mixed with a refrigerant liquid is realized.

Drawings

Fig. 1 is a schematic diagram showing an embodiment of a refrigerator in which a refrigerant circulates.

Fig. 2 is an enlarged sectional view of the compressor shown in fig. 1.

Fig. 3 is an enlarged view of the first rolling bearing and the first bearing housing.

Fig. 4 is a sectional view taken along line a-a of fig. 3.

Fig. 5 is a diagram showing an embodiment of the first pressure equalizing passage.

Fig. 6 is a diagram showing an embodiment of the first pressure equalizing passage.

Fig. 7 is a diagram showing an embodiment of the first pressure equalizing passage.

Fig. 8 is a diagram showing an embodiment of the first pressure equalizing passage.

Fig. 9 is an enlarged view of the second rolling bearing and the second bearing housing.

Fig. 10 is a schematic diagram showing another embodiment of the refrigerator.

Fig. 11 is a modification of the embodiment shown in fig. 10.

Fig. 12 is a further modification of the embodiment shown in fig. 10.

Description of reference numerals: 1 … compressor; 2 … evaporator; 3 … condenser; 4A, 4B, 4C, 4E … refrigerant pipes; 11. 11A, 11B … impellers; 12 … a rotator; 13 … electric motor; 13a … motor rotor; 13B … motor stator; 13C … motor housing; 14 … impeller housing; 16 … guide vanes; 17 … compression chamber; 18 … refrigerant nozzle; 21. 22 … expansion valve; 25 … first rolling bearing; 26 … second rolling bearing; 31 … first bearing chamber; 32 … second bearing chamber; 35 … a first bearing housing; 36 … a second bearing housing; 40 … refrigerant liquid transport tube; 41 … refrigerant pump; 45 … refrigerant liquid return line; 51 … first gas supply flow path; 52 … second gas supply flow path; 61 … angular contact bearing; 61A … rotor; 61B … lubricant retaining ring; 65 … lubricant; 68A, 68B … seals; 70 … a first pressure equalization passage; 81 … angular contact bearing; 81a … rotor; 81B … lubricant retaining ring; 85 … a lubricant; 88 … seal member; 90 … a second pressure equalization passage; 95 … economizer; 97 … middle suction inlet; 99 … branch pipes.

Detailed Description

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

Fig. 1 is a schematic diagram showing an embodiment of a refrigerator in which a refrigerant circulates. The refrigerator of the present embodiment is a centrifugal refrigerator including a centrifugal compressor 1. As shown in fig. 1, the refrigerator includes: an evaporator 2 that evaporates a refrigerant liquid to generate a refrigerant gas; a compressor 1 for compressing a refrigerant gas; and a condenser 3 for condensing the compressed refrigerant gas to produce a refrigerant liquid. The suction port of the compressor 1 is connected to the evaporator 2 via a refrigerant pipe 4A. The discharge port of the compressor 1 is connected to the condenser 3 through a refrigerant pipe 4B. An expansion valve 21 is attached to a refrigerant pipe 4C extending from the condenser 3 to the evaporator 2. The expansion valve 21 is an actuator-driven flow rate control valve configured to be adjustable in opening degree, and is constituted by, for example, an electrically operated valve with a variable opening degree.

In the present embodiment, the compressor 1 is constituted by a single-stage centrifugal compressor. More specifically, the compressor 1 includes a single-stage impeller 11, a rotating body 12 rotatable integrally with the impeller 11, and a motor 13 for rotating the rotating body 12 and the impeller 11. In one embodiment, the rotating body 12 is a rotating shaft, and the impeller 11 is fixed to the rotating shaft. In another embodiment, the impeller 11 may be integrally formed with the rotor 12. The rotary body 12 is rotatably supported by bearings 25 and 26. The bearings 25 and 26 are disposed inside the motor 13. More specifically, the bearings 25 and 26 are disposed in bearing chambers 31 and 32 formed in the motor 13, respectively. In one embodiment, the compressor 1 may be a multistage centrifugal compressor including a multistage impeller.

A guide vane 16 for adjusting the suction flow rate of the refrigerant gas to the impeller 11 is disposed at the suction port of the compressor 1. The guide vanes 16 are located on the suction side of the impeller 11. The guide vanes 16 are arranged in a radial shape, and the opening degree of the guide vanes 16 is changed by rotating each guide vane 16 by a predetermined angle in synchronization with each other around the axis of the guide vane 16. The refrigerant gas sent from the evaporator 2 passes through the guide vanes 16 and is then pressurized by the rotating impeller 11. The refrigerant gas having been pressurized is sent to the condenser 3 through the refrigerant pipe 4B.

The evaporator 2 takes heat from a fluid to be cooled (for example, cold water) to evaporate the refrigerant liquid, thereby exerting a refrigeration effect. The compressor 1 compresses a refrigerant gas generated by the evaporator 2, and the condenser 3 cools and condenses the compressed refrigerant gas with a cooling fluid (e.g., cooling water), thereby generating a refrigerant liquid. The refrigerant liquid passes through the expansion valve 21 and is depressurized. The refrigerant liquid after pressure reduction is sent to the evaporator 2. In this way, the refrigerator is configured as a hermetic system in which the refrigerant is sealed.

The refrigerator further includes: a refrigerant liquid transport pipe 40 branched from the refrigerant pipe 4C; and a refrigerant pump 41 connected to the refrigerant liquid delivery pipe 40. The refrigerant liquid transport pipe 40 extends from the refrigerant pipe 4C to the motor 13 of the compressor 1 via the refrigerant pump 41. The refrigerant liquid delivery pipe 40 is connected to the refrigerant nozzle 18 disposed in the motor 13 of the compressor 1. The refrigerant nozzle 18 is disposed toward a component such as a motor stator of the electric motor 13.

Most of the refrigerant liquid flowing through the refrigerant pipe 4C is sent to the evaporator 2, but a part of the refrigerant liquid flowing through the refrigerant pipe 4C flows into the refrigerant liquid sending pipe 40 and is sent to the refrigerant nozzle 18 by the refrigerant pump 41. The refrigerant liquid is injected from the refrigerant nozzle 18 into the motor 13 to cool the inside of the motor 13. The interior of the electric motor 13 communicates with the interior of the evaporator 2 through a refrigerant liquid return pipe 45. More specifically, one end of the refrigerant liquid return pipe 45 is connected to the bottom of the electric motor 13, and the other end of the refrigerant liquid return pipe 45 is connected to the evaporator 2. The refrigerant liquid injected from the refrigerant nozzle 18 is collected in the motor 13 and returned to the evaporator 2 through the refrigerant liquid return pipe 45.

Fig. 2 is an enlarged sectional view of the compressor 1 shown in fig. 1. The compressor 1 includes: an impeller 11; an impeller housing 14 for housing the impeller 11; a rotary body 12 rotatable integrally with the impeller 11; a first rolling bearing 25 and a second rolling bearing 26 that rotatably support the rotating body 12; and a motor 13 for rotating the impeller 11 and the rotating body 12. A compression chamber 17 is formed in the impeller housing 14, and the impeller 11 is disposed in the compression chamber 17.

The motor 13 includes: a motor rotor 13A fixed to the rotating body 12, a motor stator 13B surrounding the motor rotor 13A, and a motor case 13C accommodating the motor rotor 13A and the motor stator 13B. The motor housing 13C is connected to the impeller housing 14. The refrigerant nozzle 18 is fixed to the motor case 13C and faces the motor stator 13B and the motor rotor 13A. The refrigerant liquid is injected from the refrigerant nozzle 18 to the motor stator 13B and the motor rotor 13A, and cools the motor stator 13B and the motor rotor 13A. The refrigerant liquid returns to the evaporator 2 through a refrigerant liquid return pipe 45 connected to the bottom of the motor case 13C.

The rotating body 12 is supported by a first rolling bearing 25 and a second rolling bearing 26 disposed on both sides of the motor rotor 13A. The first rolling bearing 25 is surrounded by a first bearing housing 35. More specifically, the first bearing housing 35 has a first bearing chamber 31 formed therein, and the first rolling bearing 25 is disposed in the first bearing chamber 31. The first bearing housing 35 is supported by the impeller housing 14. In the present embodiment, the first bearing housing 35 and the impeller casing 14 are formed as separate members, and the first bearing housing 35 is fixed to the impeller casing 14. In one embodiment, the first bearing housing 35 may also be integral with the impeller housing 14. In one embodiment, the first bearing housing 35 may be supported by the motor housing 13C. For example, the first bearing housing 35 may be fixed to the motor housing 13C or integrated with the motor housing 13C.

The first bearing housing 35 is not in contact with the rotating body 12, and a gap is formed between the first bearing housing 35 and the rotating body 12. The first bearing chamber 31 communicates with the compression chamber 17 in which the impeller 11 is disposed through the first gas supply passage 51. The first gas supply flow path 51 is formed in the inner side wall 14a of the impeller housing 14. Most of the refrigerant gas compressed by the rotating impeller 11 is sent to the condenser 3 through the refrigerant pipe 4B, while a part of the compressed refrigerant gas flows from the compression chamber 17 into the first bearing chamber 31 through the first gas supply passage 51, and the first bearing chamber 31 is filled with the refrigerant gas (high-pressure gas).

The first bearing housing 35 is disposed inside the motor housing 13C. The internal space of the motor housing 13C (i.e., the space outside the first bearing chamber 31) communicates with a region of lower pressure than the pressure inside the first bearing chamber 31. More specifically, the internal space of the motor housing 13C (i.e., the space outside the first bearing chamber 31) communicates with the evaporator 2 via the refrigerant liquid return pipe 45 (see fig. 1). Since the evaporator 2 communicates only with the suction side of the compressor 1, the pressure in the evaporator 2 is lower than the pressure in the first bearing chamber 31. Therefore, the internal space of the motor housing 13C (i.e., the space outside the first bearing chamber 31) is low pressure compared to the pressure inside the first bearing chamber 31. In the present embodiment, the communication flow path that communicates with the space outside the first bearing chamber 31 and communicates with a region of lower pressure than the pressure inside the first bearing chamber 31 is constituted by the refrigerant liquid return pipe 45.

According to the above configuration, the pressure of the refrigerant gas in the first bearing chamber 31 is higher than the pressure in the internal space of the motor housing 13C (i.e., the space outside the first bearing chamber 31). Therefore, the refrigerant liquid injected as the coolant from the refrigerant nozzle 18 does not enter the first bearing chamber 31 filled with the high-pressure refrigerant gas, and therefore does not contact the first rolling bearing 25.

The second rolling bearing 26 is surrounded by a second bearing housing 36. More specifically, the second bearing housing 36 forms the second bearing chamber 32 therein, and the second rolling bearing 26 is disposed in the second bearing chamber 32. The second bearing housing 36 is fixed to the motor housing 13C. The second bearing housing 36 may be integrated with the motor housing 13C.

The second bearing housing 36 is not in contact with the rotary body 12, and a gap is formed between the second bearing housing 36 and the rotary body 12. The second bearing chamber 32 communicates with the condenser 3 (see fig. 1) through the second gas supply passage 52. The condenser 3 communicates with a discharge port of the compressor 1 via a refrigerant pipe 4B (see fig. 1), and a refrigerant gas compressed by the compressor 1 is present inside the condenser 3. A part of the compressed refrigerant gas in the condenser 3 is sent to the second bearing chamber 32 through the second gas supply passage 52. The second bearing chamber 32 is filled with refrigerant gas (high-pressure gas).

In the present embodiment, the second gas supply flow path 52 extends from the condenser 3 to the second bearing housing 36, but in one embodiment, the second gas supply flow path 52 may extend from the refrigerant pipe 4B to the second bearing housing 36. In this case, a part of the compressed refrigerant gas flowing through the refrigerant pipe 4B is sent to the second bearing chamber 32 through the second gas supply passage 52.

The second bearing housing 36 is also disposed in the motor housing 13C, as in the first bearing housing 35. A refrigerant of a pressure lower than the pressure in the second bearing chamber 32 exists in the internal space of the motor housing 13C (i.e., the space outside the second bearing chamber 32).

With the above configuration, the pressure of the refrigerant gas in the second bearing chamber 32 is higher than the pressure in the internal space of the motor housing 13C (i.e., the space outside the second bearing chamber 32). Therefore, the refrigerant liquid injected as the coolant from the refrigerant nozzle 18 does not enter the second bearing chamber 32 filled with the high-pressure refrigerant gas and does not contact the second rolling bearing 26.

Fig. 3 is an enlarged view of the first rolling bearing 25 and the first bearing housing 35, and fig. 4 is a sectional view taken along line a-a of fig. 3. In the present embodiment, the first rolling bearing 25 includes two back surface combined angular contact bearings 61 arranged coaxially. The two angular contact bearings 61 are in contact with each other without forming a gap therebetween. Since there is no gap between the angular bearings 61, the high-pressure refrigerant gas does not enter between the angular bearings 61, and therefore, undesirable pressure fluctuations do not occur in the first bearing chamber 31. Further, the rear combination angular contact bearing 61 arranged coaxially has the following advantages.

1) Since the contact angle of the rotating body is inclined, a large axial load can be supported.

2) By managing the internal clearance, preload can be applied to improve the shaft rigidity.

In one embodiment, the first rolling bearing 25 may include only one angular contact bearing, or three or more angular contact bearings. In one embodiment, instead of the angular contact bearing, various rolling bearings such as a deep groove ball bearing may be provided.

Each angular contact bearing 61 holds a lubricant 65 inside thereof. The lubricant 65 is a semi-fluid lubricant (e.g., grease) having a higher viscosity than the lubricating oil. Unlike fluid oil, the semi-fluid lubricant (e.g., grease) 65 is difficult to flow out of the first rolling bearing 25. Therefore, an oil circulation mechanism, which has been conventionally required, can be eliminated.

Each angular contact bearing 61 includes a plurality of rolling elements 61A and lubricant retaining rings 61B arranged on both sides of the plurality of rolling elements 61A. The lubricant retaining ring 61B is retained by an outer ring (stationary ring) of each angular bearing 61, and is not in contact with an inner ring (rotating ring) of each angular bearing 61. The lubricant retaining ring 61B is formed of, for example, an annular metal plate or an annular resin plate. The lubricant retaining ring 61B has a function of leaving the lubricant 65 inside the first rolling bearing 25. Therefore, the lubricant retaining ring 61B can prevent the lubricant 65 from being mixed in the refrigerant liquid, while maintaining the performance of the first rolling bearing 25.

The compressor 1 includes seals 68A and 68B for sealing a gap between the first bearing housing 35 and the rotary body 12. In the present embodiment, the seals 68A and 68B are labyrinth seals as an example of non-contact seals. The seals 68A and 68B are disposed on both sides of the first rolling bearing 25. In one embodiment, only the motor rotor side seal 68B may be provided.

As shown in fig. 3, the refrigerant gas compressed by the compressor 1 flows into the first bearing chamber 31 through the seal 68A on the impeller side, and fills the first bearing chamber 31. The refrigerant gas flows little by little into the internal space of the motor housing 13C through the seal 68B on the motor rotor side. The seals 68A, 68B can minimize leakage of the refrigerant gas from the first bearing chamber 31. As a result, the pressure difference between the inside and the outside of the first bearing chamber 31 becomes large, and the refrigerant liquid can be reliably prevented from entering the first bearing chamber 31. The seals 68A and 68B may be contact seals from the viewpoint of minimizing leakage of the refrigerant gas from the first bearing chamber 31, but the contact seals are not suitable for high-speed operation.

The compressor 1 further includes a first pressure equalizing passage 70 that connects two spaces facing both sides of the first rolling bearing 25. The two spaces are located in the first bearing chamber 31. The first pressure equalizing passage 70 is formed in the rotating body 12. More specifically, a plurality of grooves extending in the axial direction are formed in the outer peripheral surface of the rotating body 12, and these grooves form the first pressure equalizing passage 70. As shown in fig. 4, the plurality of first pressure equalizing passages (grooves) 70 are distributed at equal intervals around the axial center of the rotating body 12. The number and arrangement of the first pressure equalizing passages 70 are not limited to those in the present embodiment. In one embodiment, only one first pressure equalizing passage (groove) 70 may be provided.

The axial length of the first pressure equalizing passage 70 is greater than the axial length of the first rolling bearing 25. Therefore, both ends of each first pressure equalizing passage 70 communicate with the two spaces in the first bearing chamber 31, respectively. In other words, the two spaces facing both sides of the first rolling bearing 25 communicate through the first pressure equalizing passage 70. The refrigerant gas compressed by the compressor 1 flows into the first bearing chamber 31 through the impeller-side seal 68A, flows through the first pressure equalizing passage 70, and fills the entire first bearing chamber 31. The first pressure equalizing passage 70 can equalize the pressure of the refrigerant gas on both sides of the first rolling bearing 25. Therefore, the lubricant 65 can be prevented from being displaced or flowing out due to the pressure difference of the refrigerant gas.

The first rolling bearing 25 is disposed in a first bearing chamber 31, and the first bearing chamber 31 is filled with compressed refrigerant gas (i.e., high-pressure refrigerant gas). The pressure in the first bearing chamber 31 is higher than the pressure in the space outside the first bearing chamber 31 (i.e., the internal space of the motor housing 13C). Therefore, the refrigerant liquid present outside the first bearing chamber 31 cannot enter the first bearing chamber 31, and therefore does not contact the lubricant 65 held by the first rolling bearing 25. As a result, the lubricant 65 is not mixed with the refrigerant liquid, and the refrigerant liquid and the lubricant 65 can perform their respective functions. Further, since the oil circulation line can be omitted, the structure can be greatly simplified. Further, since leakage of oil to the refrigerant side does not occur, a mechanism for separating oil from the refrigerant is not necessary.

As shown in fig. 5 and 6, the first pressure equalizing passage 70 may be a hole formed in the rotating body 12 as long as it communicates with two spaces facing both sides of the first rolling bearing 25. Further, the first pressure equalizing passage 70 may be formed in the first bearing housing 35. For example, as shown in fig. 7, the first pressure equalizing passage 70 may be a groove formed in the inner surface of the first bearing housing 35. Alternatively, although not shown, the first pressure equalizing passage 70 may be a hole formed in the first bearing housing 35. As shown in fig. 8, the first pressure equalizing passage 70 may be formed of a pipe having both ends connected to the first bearing housing 35.

Fig. 9 is an enlarged view of the second rolling bearing 26 and the second bearing housing 36. Since the configurations and effects not described in particular are the same as those of the embodiment described with reference to fig. 3 and 4, redundant description thereof will be omitted. In the present embodiment, the second rolling bearing 26 includes a back combination angular contact bearing 81 coaxially aligned. The two angular contact bearings 81 are in contact with each other without forming a gap therebetween. Since there is no gap between the angular bearings 81, the high-pressure refrigerant gas does not enter between the angular bearings 81, and undesired pressure fluctuations do not occur in the second bearing chamber 32. The advantageous effects of the two angular contact bearings 81 arranged coaxially are the same as those described in the angular contact bearing 61, and therefore, a repetitive description thereof will be omitted.

In one embodiment, the second rolling bearing 26 may also include only one angular contact bearing, or three or more angular contact bearings. In one embodiment, instead of the angular contact bearing, various rolling bearings such as a deep groove ball bearing may be provided.

Each angular contact bearing 81 holds a lubricant 85 inside thereof. The lubricant 85 is a semi-fluid lubricant (e.g., grease) and has a higher viscosity than the lubricating oil. Each angular contact bearing 81 includes a plurality of rolling elements 81A and lubricant retaining rings 81B disposed on both sides of the plurality of rolling elements 81A. The lubricant retaining ring 81B is retained by an outer ring (stationary ring) of each angular contact bearing 81 and is not in contact with an inner ring (rotating ring) of each angular contact bearing 81. The lubricant retaining ring 81B is formed of, for example, an annular metal plate or an annular resin plate. The lubricant retaining ring 81B has a function of retaining the lubricant 85 inside the second rolling bearing 26.

The compressor 1 includes a seal 88 for sealing a gap between the second bearing housing 36 and the rotary body 12. The seal 88 is a labyrinth seal as an example of a non-contact seal. In the present embodiment, the end of the rotary body 12 is located in the second bearing chamber 32, and therefore the seal 88 is provided only on the motor rotor side. The refrigerant gas compressed by the compressor 1 flows from the condenser 3 into the second bearing chamber 32 through the second gas supply flow path 52, and fills the second bearing chamber 32. The refrigerant gas flows out little by little into the internal space of the motor housing 13C through the seal 88 on the motor rotor side. The seal 88 can minimize leakage of refrigerant gas from the second bearing chamber 32. The seal 88 may also be a contact seal, but contact seals are not suitable for high speed operation.

The compressor 1 further includes a second pressure equalizing passage 90 that connects two spaces facing both sides of the second rolling bearing 26. The two spaces are located in the second bearing chamber 32. The second pressure equalizing passage 90 is formed in the rotary body 12. More specifically, a plurality of grooves extending in the axial direction are formed in the outer peripheral surface of the rotating body 12, and these grooves form the second pressure equalizing passage 90. The plurality of second pressure equalizing passages (grooves) 90 are distributed at equal intervals around the center of the rotary body 12. The number and arrangement of the second pressure equalizing passages 90 are not limited to those in the present embodiment. In one embodiment, only one second pressure equalizing passage (groove) 90 may be provided. The embodiments of the first pressure equalizing passage 70 described with reference to fig. 5 to 8 can also be applied to the second pressure equalizing passage 90.

The axial length of the second pressure equalizing passage 90 is greater than the axial length of the second rolling bearing 26. Therefore, both ends of each second pressure equalizing passage 90 communicate with the two spaces in the second bearing chamber 32. In other words, the two spaces facing both sides of the second rolling bearing 26 communicate through the second pressure equalizing passage 90. The refrigerant gas compressed by the compressor 1 flows into the second bearing chamber 32 through the second gas supply passage 52, flows through the second pressure equalizing passage 90, and fills the entire second bearing chamber 32. The second pressure equalizing passage 90 can equalize the pressure of the refrigerant gas on both sides of the second rolling bearing 26. Therefore, the lubricant 85 can be prevented from being displaced or flowing out due to the pressure difference of the refrigerant gas.

The second rolling bearing 26 is disposed in a second bearing chamber 32, and the second bearing chamber 32 is filled with compressed refrigerant gas (i.e., high-pressure refrigerant gas). The pressure in the second bearing chamber 32 is higher than the pressure in the space outside the second bearing chamber 32 (i.e., the internal space of the motor housing 13C). Therefore, the refrigerant liquid present outside the second bearing chamber 32 cannot enter the second bearing chamber 32 and does not contact the lubricant 85 retained in the second rolling bearing 26. As a result, the lubricant 85 is not mixed with the refrigerant liquid, and the refrigerant liquid and the lubricant 85 can perform their respective functions. Further, since the oil circulation line can be omitted, the structure can be greatly simplified. Further, since leakage of oil to the refrigerant side does not occur, a mechanism for separating oil from the refrigerant is not necessary.

Fig. 10 is a schematic diagram showing another embodiment of the refrigerator. The configuration of the present embodiment, which is not particularly described, is the same as the embodiment described with reference to fig. 1 to 9, and therefore, redundant description thereof is omitted. The refrigerator includes an economizer 95 disposed between the condenser 3 and the evaporator 2. The refrigerant pipe 4C includes an upstream side pipe 4Ca extending from the condenser 3 to the economizer 95, and a downstream side pipe 4Cb extending from the economizer 95 to the evaporator 2.

The economizer 95 is connected to the compressor 1 through a refrigerant pipe 4E. The economizer 95 is an intercooler disposed between the condenser 3 and the evaporator 2. An expansion valve 21 is attached to an upstream side pipe 4Ca extending from the condenser 3 to the economizer 95, and an expansion valve 22 is attached to a downstream side pipe 4Cb extending from the economizer 95 to the evaporator 2. The expansion valves 21 and 22 are actuator-driven flow rate control valves whose opening degrees are adjustable, and are constituted by, for example, electrically operated valves whose opening degrees are variable.

In the present embodiment, the compressor 1 is constituted by a multistage centrifugal compressor. More specifically, the compressor 1 is constituted by a two-stage centrifugal compressor, and includes a first-stage impeller 11A, a second-stage impeller 11B, and a motor 13 for rotating the impellers 11A, 11B. The guide vanes 16 are located on the suction side of the first-stage impeller 11A. The refrigerant gas sent from the evaporator 2 passes through the guide vanes 16, and then is sequentially pressurized by the rotating impellers 11A and 11B. The refrigerant gas having been pressurized is sent to the condenser 3 through the refrigerant pipe 4B.

The evaporator 2 takes heat from a fluid to be cooled (for example, cold water) to evaporate the refrigerant liquid, thereby exerting a refrigeration effect. The compressor 1 compresses a refrigerant gas generated by the evaporator 2, and the condenser 3 cools and condenses the compressed refrigerant gas with a cooling fluid (e.g., cooling water), thereby generating a refrigerant liquid. The refrigerant liquid is decompressed by the expansion valve 21. The refrigerant gas present in the refrigerant liquid after the pressure reduction is separated by the economizer 95, and is sent to an intermediate suction port 97 provided between the first-stage impeller 11A and the second-stage impeller 11B of the compressor 1. The refrigerant liquid having passed through the economizer 95 is decompressed by the expansion valve 22, and is further sent to the evaporator 2.

Fig. 11 is a modification of the embodiment shown in fig. 10. As shown in fig. 11, the branch pipe 99 branches from the refrigerant pipe 4E connecting the economizer 95 and the compressor 1, and extends to the second bearing chamber 32. The second bearing chamber 32 communicates with the economizer 95 via the refrigerant pipe 4E and the branch pipe 99. In the present embodiment, the gas supply passage for supplying the refrigerant gas compressed by the compressor 1 into the second bearing chamber 32 is constituted by a part of the refrigerant pipe 4E and the branch pipe 99. The refrigerant gas separated by the economizer 95 is sent into the second bearing chamber 32 through the refrigerant pipe 4E and the branch pipe 99. The second bearing chamber 32 is filled with refrigerant gas (high-pressure gas).

Fig. 12 is a further modification of the embodiment shown in fig. 10. As shown in fig. 12, one end of the refrigerant liquid return pipe 45 is connected to the bottom of the motor 13, and the other end of the refrigerant liquid return pipe 45 is connected to the economizer 95. The refrigerant liquid injected from the refrigerant nozzle 18 is collected in the motor 13 and returned to the economizer 95 through the refrigerant liquid return pipe 45. The internal space of the motor housing 13C (i.e., the space outside the first bearing chamber 31 and the second bearing chamber 32) communicates with the economizer 95 through the refrigerant liquid return pipe 45. The pressure in the economizer 95 is lower than the pressure in the first bearing chamber 31 and the second bearing chamber 32. Therefore, the pressure in the first and second bearing chambers 31 and 32 is higher than the internal space of the motor housing 13C (i.e., the space outside the first and second bearing chambers 31 and 32). In the present embodiment, the communication flow path that communicates with the space outside the first bearing chamber 31 and the second bearing chamber 32 and that communicates with the region of lower pressure than the pressure in the first bearing chamber 31 and the second bearing chamber 32 is constituted by the refrigerant liquid return pipe 45.

In the embodiment shown in fig. 10 to 12, the refrigerant liquid present outside the bearing chambers 31 and 32 does not enter the bearing chambers 31 and 32, and therefore does not come into contact with the lubricant held by the rolling bearings 25 and 26. As a result, the lubricant does not mix with the refrigerant liquid, and the refrigerant liquid and the lubricant can perform their respective functions. Further, since the oil circulation line can be omitted, the structure can be greatly simplified. Further, since leakage of oil to the refrigerant side does not occur, a mechanism for separating oil from the refrigerant is not necessary.

The above-described embodiments are described for the purpose of enabling those having ordinary skill in the art to which the present invention pertains to practice the present invention. Various modifications of the above-described embodiments will be apparent to those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the embodiments described above, but is to be accorded the widest scope based on the technical ideas defined by the claims.

Claims (12)

1. A compressor for compressing a refrigerant gas in a refrigerator, comprising:

an impeller;

a rotating body that is rotatable integrally with the impeller;

a rolling bearing that rotatably supports the rotating body;

a lubricant retained within the rolling bearing;

a bearing housing forming a bearing chamber in which the rolling bearing is disposed;

a gas supply passage communicating with the bearing chamber and configured to supply the refrigerant gas compressed by the compressor into the bearing chamber; and

and a communication flow path that communicates with a space outside the bearing chamber and communicates with a region having a pressure lower than a pressure in the bearing chamber.

2. The compressor of claim 1,

the bearing device further includes a seal member that seals a gap between the bearing housing and the rotating body.

3. Compressor according to claim 1 or 2,

the compressor further includes a pressure equalizing passage connecting two spaces facing both sides of the rolling bearing, the two spaces being located in the bearing chamber.

4. The compressor of claim 3,

the pressure equalizing passage is formed in the rotating body.

5. The compressor of claim 3,

the pressure equalizing passage is formed in the bearing housing.

6. The compressor of claim 3,

the pressure equalizing passage is connected to the bearing housing.

7. The compressor of any one of claims 1, 2, 4, 5, 6,

the rolling bearing includes a plurality of rolling elements and lubricant retaining rings disposed on both sides of the plurality of rolling elements.

8. The compressor of claim 3,

the rolling bearing includes a plurality of rolling elements and lubricant retaining rings disposed on both sides of the plurality of rolling elements.

9. The compressor of any one of claims 1, 2, 4, 5, 6,

the lubricant is a semi-fluid lubricant.

10. The compressor of claim 3,

the lubricant is a semi-fluid lubricant.

11. A refrigerator that circulates a refrigerant inside, comprising:

an evaporator that evaporates a refrigerant liquid to generate a refrigerant gas;

the compressor of any one of claims 1, 2, 4, 5, 6 compressing the refrigerant gas; and

a condenser that condenses the compressed refrigerant gas to generate the refrigerant liquid.

12. A refrigerator that circulates a refrigerant inside, comprising:

an evaporator that evaporates a refrigerant liquid to generate a refrigerant gas;

the compressor of claim 3, compressing said refrigerant gas; and

a condenser that condenses the compressed refrigerant gas to generate the refrigerant liquid.

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