JP2014074367A - Screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw compressor free from excessive supply of a lubricant to a bearing.SOLUTION: A screw compressor in which a gas is compressed by screw rotors 9, 10 to supply a lubricant, has a rotor chamber 8 accommodating the screw rotors 9, 10, bearing spaces 31, 32 accommodating bearings 20, 22 supporting rotor shafts 17, 18 of the screw rotors 9, 10 and provided with bearing oil discharge flow channels 36, 37 for discharging the lubricant, pressure oil spaces 40, 41 respectively disposed between the rotor chamber 8 and the bearing spaces 30, 31 to supply the lubricant through an oil injection flow channel 39, intermediate spaces 43, 44 respectively disposed between the pressure oil spaces 40, 41 and the bearing spaces 30, 31, allowing the lubricant to leak out from the pressure oil spaces 40, 41, and communicated with the bearing spaces 30, 31, and an intermediate oil discharge flow channel 46 for communicating the intermediate spaces 43, 44 with a low pressure space having a pressure lower than a lubricant supply pressure to the pressure oil spaces 40, 41.

Description

  The present invention relates to a screw compressor.

  For example, as described in Patent Literatures 1 to 4, in a screw compressor device, the lubricating oil is separated by an oil separator from the gas discharged by the screw compressor, and the separated lubricating oil is cooled by an oil cooler. After that, there is a technology for supplying to the bearing portion and shaft seal portion of the screw compressor.

  In particular, as described in Patent Document 1, in order to prevent gas from leaking from the rotor chamber along the rotor shaft, lubricating oil for assisting the seal is supplied to the shaft seal portion between the rotor chamber and the bearing space. There are many cases. In this case, since the lubricating oil supplied for the shaft seal leaks from the shaft seal portion to the bearing side, the lubricating oil lubricates the bearing, and the lubricating oil that lubricated the bearing is discharged to the outside. .

  In general, the amount of oil required for the shaft seal is much larger than the amount of oil required for lubricating the bearing, and therefore the lubricant is supplied to the bearing more than necessary. For this reason, the bearing stirs the excessively supplied lubricating oil with the rotation of the rotor shaft and causes energy loss due to fluid resistance.

  Further, there is a case where a balance piston is provided between the bearing and the shaft seal portion, and the force by which the compressed gas presses the rotor shaft toward the suction side is canceled by the pressure of the lubricating oil. In this case as well, the bearing is lubricated by the lubricating oil leaked to the bearing side from the gap between the balance piston and the casing. Since it is more than the amount of oil required to lubricate, the lubricating oil is agitated, causing energy loss.

  In this way, if a mechanism for applying the lubricating oil pressure, such as a shaft seal or balance piston, is provided on the rotor shaft of the screw compressor, particularly on the discharge side where the pressure is high, excessive lubricating oil is supplied to the bearing. As a result, there has been a problem of causing a stirring loss in the bearing.

Japanese Patent Laid-Open No. 10-9179 Japanese Patent Laid-Open No. 10-159664 JP 2000-337282 A JP 2005-337242 A

  In view of the above problems, an object of the present invention is to provide a screw compressor in which excessive lubricating oil is not supplied to a bearing.

  In order to solve the above problems, a screw compressor according to the present invention is a screw compressor that compresses gas by a screw rotor and is supplied with lubricating oil, a rotor chamber that houses the screw rotor, and the screw rotor. A bearing space that accommodates a bearing that supports the rotor shaft and opens a bearing oil discharge passage for discharging the lubricating oil, and is provided between the rotor chamber and the bearing space, and through the oil supply passage. A pressure oil space to which the lubricating oil is supplied; an intermediate space that is provided between the pressure oil space and the bearing space, is capable of leaking the lubricating oil from the pressure oil space, and communicates with the bearing space; And an intermediate oil discharge passage for communicating the intermediate space with a low pressure space having a pressure lower than a supply pressure of the lubricating oil to the pressure oil space.

  According to this configuration, a part of the lubricating oil leaked from the pressure oil space to the intermediate space is discharged to the low pressure space through the intermediate oil discharge passage, so that the amount of lubricating oil flowing from the intermediate space into the bearing space is reduced. can do. For this reason, generation | occurrence | production of the power loss by a bearing stirring an excess lubricating oil can be suppressed.

  The screw compressor of the present invention may further include a flow rate limiting unit that limits a flow rate of the lubricating oil flowing from the intermediate space into the bearing space.

  According to this configuration, the amount of oil in the bearing space can be limited to an appropriate amount, so that power loss due to stirring of the lubricating oil can be minimized.

  Moreover, the screw compressor of this invention WHEREIN: The said flow volume restriction | limiting means may also contain the partition plate which divides between the said bearing space and the said intermediate space.

  According to this configuration, since the inflow of lubricating oil from the intermediate space to the bearing space can be restricted, oil drainage from the intermediate space through the intermediate oil drain passage is effectively promoted, and agitation loss in the bearing is reduced. it can.

  In the screw compressor of the present invention, the low-pressure space may be a confined space of the rotor chamber.

  According to this configuration, since the lubricating oil in the intermediate space is discharged to the confined space in the compression process, it is possible to prevent a reduction in the volumetric efficiency of the compressor.

  Moreover, the screw compressor of this invention WHEREIN: The said bearing oil drainage flow path may be connected to the confinement space of the said rotor chamber.

  According to this configuration, since the lubricating oil in the bearing space is discharged to the confined space in the compression process, it is possible to prevent a reduction in volumetric efficiency of the compressor.

  The screw compressor of the present invention may further include a reduced diameter portion that limits the flow rate of the lubricating oil between the intermediate space and the low pressure space.

  According to this configuration, the pressure in the intermediate space does not drop excessively, and oil supply to the bearing space can be ensured.

  As described above, according to the present invention, since the intermediate space for discharging the lubricating oil is provided between the bearing space and the pressure oil space, the amount of lubricating oil flowing into the bearing space is reduced, It is possible to prevent stirring loss.

It is a lineblock diagram of the screw compressor of one embodiment of the present invention. It is sectional drawing of the low stage discharge side of the screw compressor of FIG. It is sectional drawing by the side of the high stage discharge of the screw compressor of FIG. It is sectional drawing of the modification of the high stage discharge side of a screw compressor.

FIG. 1 shows a compression apparatus according to one embodiment of the present invention. The compression apparatus according to the present embodiment includes an oil-cooled screw compressor 1, an oil separator 2 that separates lubricating oil from the compressed gas discharged by the screw compressor 1, and a lubricant oil separated by the oil separator 2. And an oil cooler 3 for cooling the part.

  The screw compressor 1 is a two-stage compressor having a low-stage compression section 4 that compresses gas sucked from the outside and a high-stage compression section 5 that further compresses gas compressed by the low-stage compression section 4. A motor unit 6 that drives the stage compression unit 4 and the high stage compression unit 5 is integrated. The low-stage compression unit 4, the high-stage compression unit 5, and the motor unit 6 have a common casing 7 that is integrally connected.

  The low-stage compression unit 4 accommodates a pair of male and female screw rotors 9 and 10 in a rotor chamber 8 formed in the casing 7, and gas is supplied from the suction flow path 11 to the rotor chamber 8 by the rotation of the screw rotors 9 and 10. Is sucked in, compressed, and discharged to the connection flow path 12. The high-stage compression unit 5 is configured such that a pair of male and female screw rotors 14 and 15 are accommodated in a rotor chamber 13 formed in the casing 7, and gas is transferred from the connection flow path 12 to the rotor chamber 13 by the rotation of the screw rotors 14 and 15. Is sucked in and compressed, and discharged into the discharge passage 16.

  The rotor shafts 17 and 18 of the screw rotors 9 and 10 of the low-stage compression unit 4 are supported by bearings 19, 20 and 21, 22 respectively. Similarly, the rotor shafts 23 and 24 of the screw rotors 14 and 15 of the high-stage compression section 5 are supported by bearings 25, 26 and 27, 28, respectively.

  The rotor shaft 17 of the screw rotor 9 is integral with the rotor shaft of the motor unit 6, and is integrally connected to the rotor shaft 23 of the screw rotor 14 by a coupling 29.

  FIG. 2 shows in detail the structure related to holding and lubrication of the bearings 20 and 22 that support the rotor shafts 17 and 18 on the discharge side of the low-stage compression section 4. The casing 7 has a cylindrical inner wall into which the outer rings of the bearings 20 and 22 are fitted, and defines bearing spaces 30 and 31 for housing the bearings 20 and 22. In the bearing spaces 30 and 31, end portions on the rotor chamber 8 side are defined by partition plates 32 and 33, and opposite end portions are defined by end caps 34 and 35.

  Although the outer periphery of the partition plates 32 and 33 is in close contact with the casing 7, a gap through which the lubricating oil can pass is formed between the inner periphery and the rotor shaft 17. The rotor shaft 17 of the low-stage compression section 4 passes through the opening of the end cap 34, and the end of the coupling 29 on the low-stage compression section 4 side is also inserted into the opening of the end cap 34. The end caps 34 and 35 are formed with bearing oil drain passages 36 and 37 that allow the bearing spaces 30 and 31 to communicate with the connection passage 12.

  The casing 7 includes a wall portion 38 that defines an end surface on the discharge side of the rotor chamber 8, and the inner diameter of the wall portion 38 is a minimum level that allows rotation of the rotor shafts 17, 18 between the rotor shafts 17, 18. The size is such that a gap is formed. The wall portion 38 is formed with an oil supply passage 39 that opens toward the rotor shaft 17. Lubricating oil separated by the oil separator 2 is supplied to the oil supply passage 39 through the oil cooler 3 by the discharge pressure of the high-stage compression unit 5 via an external pipe (see FIG. 1). .

  Grooves are formed in the rotor shafts 17 and 18 to form pressure oil spaces 40 and 41 that receive the lubricating oil supplied from the oil supply passage 39. The pressure oil spaces 40 and 41 communicate with each other through a connection hole 42 provided in the wall portion 38. The lubricating oil supplied to the pressure oil spaces 40 and 41 forms a gap between the wall portion 38 and the rotor shafts 17 and 18 so that the compressed gas does not leak from the rotor chamber 8 along the rotor shafts 17 and 18. It functions as a shaft seal oil that seals with pressure and viscosity.

  The casing 7 forms intermediate spaces 43 and 44 by providing a gap between the wall 38 and the partition plates 32 and 33 and the rotor shafts 17 and 18. The intermediate spaces 43 and 44 communicate with each other through a connection hole 45 provided in the casing 7. Furthermore, an intermediate oil drain passage 46 that opens into the intermediate space 44 is formed in the casing 7. The intermediate oil drainage channel 46 communicates with a closed space (low pressure space) in the middle of compression of the low-stage compression unit 4 isolated by the screw rotors 9 and 10 in the rotor chamber 8 via an external pipe. It is connected to the path 47. The return channel 47 is provided with a reduced diameter portion 48 having a reduced diameter.

  In the configuration on the discharge side of the low-stage compression unit 4 described above, the lubricating oil supplied to the pressure oil spaces 40 and 41 leaks into the intermediate spaces 43 and 44 through the gap between the rotor shafts 17 and 18 and the casing 7. Can do. The intermediate spaces 43 and 44 communicate with the confined space of the low-stage compression unit 4 having a pressure lower than the supply pressure of the lubricating oil to the oil supply passage 39 via the intermediate oil discharge passage 46 and the return passage 47. Therefore, most of the lubricating oil leaked into the intermediate spaces 43 and 44 is discharged from the intermediate oil discharge passage 46.

  However, since the reduced diameter portion 48 is provided in the return flow path 47 to which the intermediate oil discharge flow path 46 is connected, the internal pressure of the intermediate spaces 43 and 44 is the internal pressure of the connection flow path 12 (low-stage compression section). 4), the pressure is only reduced to about the same level. Specifically, the reduced diameter portion 48 can restrict the flow rate flowing through the flow path between the intermediate space 44 and the low pressure space with respect to the flow rate of the lubricating oil flowing into the intermediate spaces 43, 44. The intermediate space 43 is filled with lubricating oil in the flow path between the space 44 and the reduced diameter portion 48 (in this embodiment, the flow path including the intermediate oil discharge flow path 46, the external piping, and the return flow path 47). , 44, the lubricating oil can be retained moderately. For this reason, a part of the lubricating oil leaked from the pressure oil spaces 40 and 41 to the intermediate spaces 43 and 44 passes through the gap between the rotor shafts 17 and 18 and the partition plates 32 and 33, and the bearing spaces 30 and 31. Flow into.

  Here, by adjusting the inner diameter of the partition plates 32 and 33, the size of the gap between the rotor shafts 17 and 18 and the partition plates 32 and 33 is adjusted, and the bearing space 30 from the intermediate spaces 43 and 44 is adjusted. , 31 functions as a flow rate restricting means for restricting the flow rate of the lubricating oil. Thereby, the amount of the lubricating oil staying in the bearing spaces 30 and 31 can be adjusted to the minimum necessary for the bearings 20 and 22. As a result, it is possible to prevent the occurrence of power loss due to the bearings 20 and 22 stirring the lubricating oil as the rotor shafts 17 and 18 rotate.

  Next, FIG. 3 shows in detail the structure related to holding and lubrication of the bearings 26 and 28 that support the rotor shafts 23 and 24 on the discharge side of the high-stage compression section 5. The casing 7 has a cylindrical inner wall into which the outer rings of the bearings 26 and 28 are fitted, and defines bearing spaces 49 and 50 for housing the bearings 26 and 28. In the bearing spaces 49 and 50, end portions on the rotor chamber 13 side are defined by partition plates 51 and 52, and opposite end portions are sealed by end caps 53 and 54. The outer periphery of the partition plates 51 and 52 is in close contact with the casing 7, but a gap through which lubricating oil can pass is formed between the inner periphery and the rotor shafts 23 and 24.

  In the casing 7, a bearing oil drain passage 55 that opens from the side is formed at the bottom of the bearing spaces 49 and 50 through openings provided in the end caps 53 and 54. The bearing oil discharge passage 55 is compressed by the high-stage compression section 5 isolated by the screw rotors 14 and 15 in the rotor chamber 13 through a communication passage 56 formed in the casing 7 so as to extend in the axial direction. It is connected to a return channel 57 that communicates with a confined space in the middle.

  The casing 7 includes a wall 58 that defines an end surface on the discharge side of the rotor chamber 8, and the inner diameter of the wall 58 is sized so as to form a minimum clearance between the rotor shafts 23 and 24. . The wall 58 is formed with an oil supply passage 59 that opens toward the rotor shaft 24. Lubricating oil is supplied to the oil supply passage 59 from the oil separator 2 via the oil cooler 3 by external discharge via the piping of the high stage compression section 5 (see FIG. 1).

  The rotor shaft 24 is formed with a groove that forms a pressure oil space 60 that receives the lubricating oil supplied from the oil supply passage 59. The casing 7 defines an intermediate space 61 around the rotor shaft 24 between the wall portion 58 and the partition plate 52. On the other hand, a balance piston 62 slidably fitted to the cylindrical inner wall of the casing 7 is fixed to the rotor shaft 23. The balance piston 62 divides the space between the casing 7 and the rotor shaft 23 into a pressure oil space 63 on the rotor chamber 13 side and an intermediate space 64 on the bearing 26 side. Further, the casing 7 includes a connection flow path 65 that connects the pressure oil space 60 around the rotor shaft 24 and the pressure oil space 63 around the rotor shaft 23, and an intermediate space 61 around the rotor shaft 24 and the rotor shaft. A connection hole 66 is formed to connect the intermediate space 64 around 23. The casing 7 is formed with an intermediate oil drain passage 67 that opens into the intermediate space 61. The intermediate oil drainage channel 67 is connected to the return channel 57 via an external pipe. That is, the intermediate spaces 61 and 64 communicate with a closed space (low pressure space) in the middle of compression of the high-stage compression unit 5 via the intermediate oil discharge passage 67 and the return passage 57.

  Lubricating oil supplied to the pressure oil spaces 60 and 63 is formed between the wall 58 and the rotor shafts 24 and 23 by the pressure and viscosity so that the compressed gas does not leak from the rotor chamber 13 along the rotor shafts 24 and 23. It functions as a shaft seal oil that seals the gaps between them. Further, the lubricating oil supplied to the pressure oil space 63 presses the balance piston 62 toward the bearing 23 (to the discharge side) by the pressure, and the gas compressed in the rotor chamber 13 causes the rotor shaft 23 to move. The force that pushes toward the suction side is offset.

  The lubricating oil supplied to the pressure oil space 60 leaks into the intermediate space 62 through the gap between the rotor shaft 24 and the casing 7. Further, the lubricating oil supplied to the pressure oil space 63 leaks into the intermediate space 64 through the gap between the balance piston 62 and the casing 7. Most of the lubricating oil leaked into the intermediate spaces 61 and 64 passes through the intermediate oil discharge passage 67 and the return passage 57, and the high-stage compression is lower than the lubricating oil supply pressure to the pressure oil spaces 60 and 63. The portion 5 is discharged into the confined space of the portion 5, but a part thereof flows into the bearing spaces 49 and 50 through the gap between the rotor shafts 23 and 24 and the partition plates 51 and 52.

  Also here, the partition plates 51 and 52 function as a flow restriction means for restricting the flow rate of the lubricating oil flowing from the intermediate spaces 61 and 64 into the bearing spaces 49 and 50. As a result, the amount of lubricating oil staying in the bearing spaces 49 and 50 is adjusted to the minimum necessary for the bearings 26 and 28, and the bearings 26 and 28 agitate the lubricating oil as the rotor shafts 23 and 24 rotate. The generation of power loss due to the operation can be prevented.

  Further, FIG. 4 shows a modification of FIG. In this modification, an orifice 68 is disposed in the communication channel 56. The orifice 68 restricts the flow rate of the lubricating oil discharged from the bearing spaces 49 and 50 through the communication flow path 56 and applies a back pressure to the bearing spaces 49 and 50, thereby causing the bearing spaces 49 and 50 to move from the intermediate spaces 61 and 64 to the bearing space. It functions as a second flow rate restricting means for further restricting the flow rate of the lubricating oil flowing into the 49, 50. The orifice 68 disposed in the communication flow path 56 can be designed so that it can be replaced relatively easily as compared with the partition plates 51 and 52 fitted to the rotor shafts 23 and 24. Therefore, the flow rate of the lubricating oil flowing into the bearing spaces 49 and 50 can be easily adjusted by the orifice 68.

  In the above embodiment, the low-pressure space in which the intermediate spaces 43, 44 and 61, 64 communicate with each other via the intermediate oil drain passages 46 and 67 is a confined space of the rotor chambers 8 and 13, You may make it connect with the other space which has a pressure lower than the supply pressure of lubricating oil. Similarly, the bearing oil discharge passages 36, 37 and 55 may communicate with other spaces having a pressure lower than the supply pressure of the lubricating oil. In addition, a reduced diameter portion 48 is provided in the return flow path 47 to appropriately retain the lubricating oil in the intermediate spaces 43 and 44, but the flow path between the intermediate space 44 and the reduced diameter portion 48 (this embodiment) In the embodiment, even if the intermediate oil drain passage 46, the external pipe and the return passage 47) are adjusted, the lubricant area is moderately retained in the intermediate spaces 43 and 44. Good. The bearing oil drain passage 55 is formed so as to open to the end caps 53 and 54, respectively, but the side surfaces of both the end caps 53 and 54 and between the end caps so as to allow the bearing spaces 49 and 50 to communicate with each other. A continuous flow passage may be formed in the casing 7 so as to open only to the lower end cap 54. Further, the orifice 68 may be disposed in the bearing oil drain passage 55 as long as a predetermined back pressure can be applied to the bearing spaces 49 and 50.

  The present invention is not limited to the two-stage screw compressor as in the above embodiment, and can be widely applied to all single-stage or multi-stage oil-cooled screw compressors. Moreover, the screw compressor and compression apparatus of this invention can be utilized as a component of a refrigerator or a heat pump.

DESCRIPTION OF SYMBOLS 1 ... Screw compressor 2 ... Oil separator 3 ... Oil cooler 4 ... Low stage compression part 5 ... High stage compression part 7 ... Casing 8 ... Rotor chamber 9,10 ... Screw rotor 12 ... Connection flow path 13 ... Rotor chamber 14, DESCRIPTION OF SYMBOLS 15 ... Screw rotor 17, 18 ... Rotor shaft 20, 22, 26, 28 ... Bearing 30, 31 ... Bearing space 32, 33 ... Partition plate (flow restriction means)
36, 37 ... Bearing oil drain passage 39 ... Oil supply passage 40, 41 ... Pressure oil space 43, 44 ... Intermediate space 46 ... Intermediate oil discharge passage 47 ... Return passage 48 ... Reduced diameter portion 49, 50 ... Bearing space 51, 52 ... Partition plate (flow rate limiting means)
55 ... Bearing oil drainage channel 56 ... Communication channel 57 ... Return channel 59 ... Lubrication channel 60,63 ... Pressure oil space 61,64 ... Intermediate space 62 ... Balance piston 67 ... Intermediate oil drainage channel 68 ... Orifice ( Flow restriction means)

Claims (6)

A screw compressor that compresses gas by a screw rotor and is supplied with lubricating oil,
A rotor chamber for housing the screw rotor;
A bearing space that accommodates a bearing that supports a rotor shaft of the screw rotor, and in which a bearing oil discharge passage for discharging the lubricating oil is opened;
A pressure oil space provided between the rotor chamber and the bearing space, to which the lubricating oil is supplied via an oil supply passage;
An intermediate space that is provided between the pressure oil space and the bearing space, is capable of leaking the lubricating oil from the pressure oil space, and communicates with the bearing space;
A screw compressor, comprising: an intermediate oil discharge passage that communicates the intermediate space with a low-pressure space having a pressure lower than a supply pressure of the lubricating oil to the pressure oil space.   The screw compressor according to claim 1, further comprising a flow restriction unit that restricts a flow rate of the lubricating oil flowing from the intermediate space into the bearing space.   The screw compressor according to claim 2, wherein the flow rate limiting means includes a partition plate that partitions the bearing space and the intermediate space.   The screw compressor according to any one of claims 1 to 3, wherein the low-pressure space is a confined space of the rotor chamber.   The screw compressor according to any one of claims 1 to 4, wherein the bearing oil drain passage communicates with a closed space of the rotor chamber.   The screw compressor according to any one of claims 1 to 5, further comprising a reduced diameter portion that restricts a flow rate of the lubricating oil between the intermediate space and the low pressure space.

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