WO2007074807A1

WO2007074807A1 - Screw-type fluid machine

Info

Publication number: WO2007074807A1
Application number: PCT/JP2006/325864
Authority: WO
Inventors: Shinya Yamamoto; Ryosuke Koshizaka; Kentaro Ishihara; Masahiro Inagaki; Yuya Izawa
Original assignee: Kabushiki Kaisha Toyota Jidoshokki
Priority date: 2005-12-26
Filing date: 2006-12-26
Publication date: 2007-07-05
Also published as: US20100233006A1; JP2007170341A; EP1967734A1

Abstract

A vacuum pump has rotating shafts individually connected to a pair of screw-like rotors and also has a pair of shaft holding bodies extending in the housing. The shaft holding bodies support the rotating shafts by base bearing sections and end bearing sections. Each pair of the base bearing section and the end bearing section is fixed in the axial direction relative to a corresponding rotating shaft and shaft holding body. Lubricant oil is contained in a oil containing space in a gear case attached to the housing. A cooling water path in which cooling water for cooling the lubricant oil flows is formed in the gear case. An electromagnetic valve controls the flow rate of the cooling water in the cooling water path. A temperature sensor is provided in the oil containing space and measures the temperature of the lubricant oil. According to the temperature measured by the temperature sensor, a control device controls the magnetic valve in order that the temperature of the lubricant oil in the oil containing space is maintained constant. Application of an axial load on the bearing sections is suppressed even if the bearing sections are fixed in the axial direction to the rotating shafts and the shaft holding bodies.

Description

Specification

Screw fluid machine

Technical field

[0001] The present invention relates to a screw type fluid machine such as a vacuum pump used in a semiconductor manufacturing process, for example.

Background art

[0002] As a screw-type fluid machine, for example, a screw-type vacuum pump described in Patent Document 1 is known. The screw-type vacuum pump of Patent Document 1 includes a pair of screw-shaped rotors that are adjacent to each other and are adjacent to each other in a casing. Each rotor is provided with a rotating shaft, and each rotating shaft is supported by a casing as a shaft holder via an upper bearing and a lower bearing.

[0003] Synchronous gears are respectively fixed to both rotary shafts, and these synchronous gears are meshed with each other. A lubricating oil passage extending in the axial direction is formed inside each rotary shaft, and the lubricating oil passage functions as a centrifugal pump. The lubricating oil passage has an inlet opening at the lower end of the rotating shaft and an outlet opening at the peripheral surface of the rotating shaft above the upper bearing. There is a heat exchanger near the entrance of the lubricant passage. Lubricating oil is stored in the casing, and the lower end of the rotating shaft is immersed in the stored lubricating oil. Further, a cooling water pipe is provided in the casing, and heat exchange is performed between the cooling water and the lubricating oil in the heat exchange.

[0004] When the vacuum pump is driven, the centrifugal pump is stored in the casing and sucks up the lubricating oil. When the lubricating oil is sucked up by the centrifugal pump, it is cooled by heat exchange by heat exchange. The sucked-up lubricating oil exits from the outlet of the lubricating oil passage, flows down to the upper bearing, and cools the upper bearing. Thereafter, the lubricating oil flows down from the upper bearing along the rotating shaft and is stored again in the casing. Due to the flow of the lubricating oil, the upper and lower bearings and the rotating shaft are cooled. When the rotating shaft thermally expands due to sliding or the like, an axial load is applied to the bearing that supports the rotating shaft with respect to the casing. However, by cooling the bearing and rotating shaft with lubricating oil, such thermal expansion is suppressed and the bearing is loaded. Force is suppressed.

[0005] However, if the lubricating oil is simply cooled using heat exchange, the temperature of the lubricating oil cannot be finely adjusted according to the operating condition of the vacuum pump. Therefore, in practice, the thermal expansion of the rotating shaft cannot be sufficiently suppressed, and the axial load applied to the bearing cannot be sufficiently suppressed.

[0006] If the bearing is provided between the casing and the rotary shaft so that the axial displacement of the rotary shaft relative to the casing is allowed, the axial direction of the bearing due to the thermal expansion of the rotary shaft It is possible to prevent the load from being applied. However, in the case of adopting such a configuration, if the horizontal axis of the rotating shaft does not suppress vertical vibration, vibration and noise are likely to occur.

Patent Document 1: Japanese Patent Laid-Open No. 4-314991

Disclosure of the invention

[0007] An object of the present invention is to provide a screw capable of suppressing an axial load force from being applied to a bearing portion even when the bearing portion is axially fixed to a rotating shaft and a shaft holder. It is to provide a fluid machine.

[0008] In order to achieve the above object, a screw-type fluid machine according to an aspect of the present invention includes a housing, a pair of screw-like rotors housed in the housing and mated with each other, and the two rotors. A pair of rotating shafts connected so as to be coaxial with each other, and a pair of cylindrical shaft holders extending in the housing. Each rotating shaft has an end protruding from the housing. Each shaft holder has a first end and a second end, and has a through-hole through which one of the rotating shafts is inserted. First bearing portions are respectively attached to the through holes at the first end portions. Second bearing portions are respectively attached to the through holes at the second end portions. Each pair of the first and second bearing portions supports the corresponding rotation shaft so as to be rotatable with respect to the shaft holder. Each pair of the first and second bearing portions is fixed in the axial direction with respect to the corresponding rotating shaft and the shaft holder. Synchronous gears are provided at the end portions of the two rotating shafts that project the housing force. A gear case houses the synchronous gear, and the gear case defines an oil storage space in which lubricating oil can be stored. The cooling unit cools the lubricating oil using a cooling fluid. The flow rate changing unit controls the flow rate of the cooling fluid. A temperature sensor is provided in the oil storage space, Detect the temperature of the lubricating oil. The control unit controls the flow rate changing unit according to the temperature detected by the temperature sensor so that the temperature of the lubricating oil in the oil storage space is maintained constant.

Brief Description of Drawings

FIG. 1 is a longitudinal sectional view of a vacuum pump according to an embodiment of the present invention.

2 is a cross-sectional view of the vacuum pump of FIG. 1 along the line AA.

FIG. 3 is an enlarged view of a main part showing a base side bearing portion and an end side bearing portion in the vacuum pump of FIG.

4 is a cross-sectional view of the vacuum pump shown in FIG. 1, taken along line BB.

FIG. 5 is an enlarged cross-sectional view of an oil supply pump portion in the vacuum pump of FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. As shown in FIG. 1, the screw-type fluid machine according to the present embodiment is a vertical-type screw-type vacuum pump (hereinafter simply referred to as “vacuum pump”) 10 used for semiconductor manufacturing. . The vacuum pump 10 includes a housing 14 including an upper housing member 11, a rotor housing member 12, and a lower housing member 13, and the housing 14 forms an outer shell of the vacuum pump 10.

Specifically, the upper housing member 11 is joined to the upper end of the rotor housing member 12, and the lower housing member 13 is joined to the lower end of the rotor housing member 12. The upper housing member 11 is formed with a suction port 15 for sucking a compressive fluid so as to communicate with the inside of the housing 14. The lower housing member 13 is provided with a discharge port 16 for discharging a compressive fluid so as to communicate with the inside of the housing 14. The lower housing member 13 includes an extending portion 13a extending sideways, and a drive motor 17 as a driving source is installed on the extending portion 13a. Further, the lower housing member 13 is joined with a gear case 18 that covers the lower housing member 13 including the extending portion 13a downward.

As shown in FIG. 2, a screw-like male rotor 21 and a screw-like female rotor 31 are housed in the housing 14, and both the rotors 21, 31 and the housing 14 are accommodated. Thus, a working chamber is formed. The male rotor 21 has an insertion hole 22 extending from the discharge port 16 toward the suction port 15 and a connecting hole 23 having a smaller diameter than the insertion hole 22 and extending upward from the upper end of the insertion hole 22. Yes. A rotation shaft 25 that passes through the lower housing member 13 is fitted into the connection hole 23. The male rotor 21 and the rotating shaft 25 are connected to each other using a stop plate 26 and a connecting bolt 27. For this reason, the male rotor 21 rotates integrally with the rotating shaft 25. Similarly, the female rotor 31 shown in FIG. 2 also has an insertion hole 32 and a connection hole 33, and is connected to the rotary shaft 35 using a stop plate 36 and a connection bolt 37. Each rotor 21, 31 is coaxial with the corresponding rotary shaft 25, 35.

[0013] The lower housing member 13 has a pair of cylindrical shaft holders 28 and 38 that extend upwardly, and the base portions of both shaft holders 28 and 38 are connected to each other as shown in FIG. It has been In this embodiment, the shaft holders 28 and 38 are fixed to the lower housing member 13 by fixing bolts 41. The shaft holder 28 is inserted into the insertion hole 22 of the male rotor 21, and a slight gap is formed between the outer peripheral surface of the shaft holder 28 and the inner peripheral surface of the insertion hole 22. The shaft holder 38 is inserted into the insertion hole 32 of the female rotor 31, and a slight gap is also formed between the outer peripheral surface of the shaft holder 38 and the inner peripheral surface of the insertion hole 32.

A through hole 29 penetrating in the axial direction is formed at the center of the shaft holder 28, and a rotating shaft 25 for the male rotor 21 is passed through the through hole 29. Between the rotary shaft 25 and the shaft holder 28, a pair of upper and lower bearing portions 42 and 43 made of rolling bearings are provided. The bearing portions 42 and 43 are disposed at the upper and lower portions of the shaft holder 28. In this embodiment, the upper bearing portion 42 is an end-side bearing portion or a second bearing portion, and the lower rolling bearing 43 is a base-side bearing portion or a first bearing portion. The upper end portion (second end portion) of the shaft holder 28 is provided with an upper diameter-enlarged hole 29 a having a diameter larger than the diameter of the through hole 29 following the through hole 29. The end side bearing portion 42 is disposed in the upper diameter-expanded hole 29a. A portion of the rotary shaft 25 between the end side bearing 42 and the base side bearing 43 has a diameter slightly larger than the diameter of the upper and lower end portions of the rotary shaft 25. As shown in FIG. 3, the portion of the rotating shaft 25 whose diameter changes forms an end portion side step portion 25a and a base portion side step portion 25b.

As shown in FIGS. 1 and 2, a seal member 30 is interposed between the rotary shaft 25 and the shaft holder 28 at a position above the end side bearing portion 42. Lower end of shaft holder 28 (first The lower end diameter hole 29 b having a diameter larger than the diameter of the through hole 29 is provided at the end) following the through hole 29. The base side bearing portion 43 is disposed in the lower diameter enlarged hole 29b.

These bearing portions 42 and 43 are provided to rotatably support the rotary shaft 25 with respect to the shaft holder 28. In this embodiment, each of the end side bearing portion 42 and the base portion side bearing portion 43 has a configuration in which two single-row rolling bearings are arranged side by side.

[0017] The end-side bearing portion 42 will be described in more detail. The end-side bearing portion 42 is configured by a combined force of two angular ball bearings 42a and 42b. As shown in FIG. 3, the two bearings 42a and 42b are arranged in the upper diameter-expanded hole 29a in a state where they are combined on the back surface. The outer rings of both the bearings 42a and 42b are press-fitted into the upper diameter expansion hole 29a and are fixed to the shaft holder 28. The inner rings of both bearings 42a and 42b are press-fitted into the rotary shaft 25.

[0018] The inner ring of the angular ball bearing 42b is abutted against the end side step portion 25a of the rotary shaft 25, and the inner ring of the angular ball bearing 42a is angular by a nut 49a screwed into the rotary shaft 25. It is pressed against the inner ring of the ball bearing 42b. As a result, the rolling elements of the anguilla ball bearings 42a and 42b are in a state where there is no gap between the inner and outer rings in both the axial direction and the radial direction.

On the other hand, as shown in FIG. 3, the base-side bearing portion 43 is also disposed in the lower diameter enlarged hole 29b in a state where the angiular ball bearings 43a and 43b are combined on the back surface. The outer rings of both bearings 43a and 43b are press-fitted into the lower diameter expansion hole 29b and fixed to the shaft holder 28. The inner ring of the angular ball bearing 43a is abutted against the base side step portion 25b of the rotary shaft 25, and the inner ring of the angular bearing 43b is inserted into the inner ring of the angular ball bearing 43a by a nut 49b screwed into the rotary shaft 25. It is pressed against. Therefore, the rolling elements of the anguilla ball bearings 43a and 43b are in a state of no gap with the inner and outer rings in both the axial direction and the radial direction.

[0020] Since each of the end-side bearing portion 42 and the base-side bearing portion 43 is configured by the back combination of two angular ball bearings, the rotary shaft 25 is axially and radially relative to the shaft holder 28. It does not move in the direction. That is, the end-side bearing portion 42 and the base-side bearing portion 43 are fixed in the axial direction by the nuts 49a and 49b and the both step portions 25a and 25b. These anguilla ball bearings 42 a, 42 b, 43 a, 43 b ensure a slight gap between the outer peripheral surface of the rotating shaft 25 and the inner peripheral surface of the through hole 29 of the shaft holding body 28. This gap forms a lubricating oil recovery path 48 (hereinafter simply referred to as oil recovery path 48). The oil recovery path 48 is a path for passing the lubricating oil 62 toward the gear case 18 where the lubricating oil 62 as a cooling medium is brought into contact with the rotating shaft 25 and the shaft holding member 28 as cooling targets.

On the other hand, a long pipe 44 extending along the axis of the rotary shaft 25 is formed in the rotary shaft 25, and the long pipe 44 has a lower end force of the rotary shaft 25 and an end side bearing portion 42. It reaches to the lower side. The rotary shaft 25 is also formed with a short pipe 45 extending in the radial direction of the rotary shaft 25 below the end side bearing portion 42. The upper end of the long pipe 44 is located below the end side bearing part 42 and is connected to the short pipe 45. The short pipe 45 opens at the peripheral surface of the rotary shaft 25 so as to communicate with the oil recovery path 48 at a position below the end side bearing portion 42. The long pipe 44 and the short pipe 45 constitute an oil supply path 46 that supplies the lubricating oil 62 to the oil recovery path 48. The oil supply passage 46 and the oil recovery passage 48 constitute an oil circulation passage.

[0023] So far, the force described for each element of the shaft holder 28, the rotary shaft 25, the bearings 42, 43, etc. on the male rotor 21 side. Each element on the female rotor 31 side is equivalent to each element on the male rotor 21 side. The structure is basically the same. That is, as shown in FIG. 2, the rotating shaft 35 is inserted through the through hole 39 of the shaft holder 38. The shaft holder 38 is provided with an upper diameter-expanded hole 39a and a lower diameter-expanded hole 39b, similar to the shaft holder 28. An end-side bearing portion 52 and a base-side bearing portion 53 are disposed in the upper diameter-expanded hole 39a and the lower diameter-expanded hole 39b, respectively. The bearing portions 52, 53 are connected to the rotary shaft 35 and the shaft holder 38. Arranged between.

[0024] Similar to the end portion side bearing portion 42 of the male rotor 21, the end portion side bearing portion 52 is configured by a rear combination of two anguillar ball bearings 52a and 52b, and is pressed downward by a nut 59a. Further, a sealing member 40 is disposed above the end side bearing portion 52. The base side bearing portion 53 is constituted by a rear combination of two anguilla ball bearings 53a and 53b, and is pressed upward by a nut 59b, like the base side bearing portion 43 of the male rotor 21.

In addition, an oil supply path 56 composed of a long pipe 54 and a short pipe 55 is formed on the rotating shaft 35 on the female rotor 31 side. Further, the gap forming the oil recovery path 58 is connected to the rotary shaft 35 and the shaft. It is formed between the holding body 38. Incidentally, the shaft diameters of the rotary shafts 25 and 35 are the same, and the end side bearings 42 and 52 and the base side bearings 43 and 53 use the same specification angular bearings.

[0026] Here, the male rotor 21 will be described in detail. As shown in FIG. 4, the male rotor 21 includes five teeth 24, and these teeth 24 are arranged at equal intervals in the circumferential direction of the male rotor 21. The teeth 24 extend in a spiral shape from the upper end to the lower end of the male rotor 21. Then, as shown in FIG. 2, the teeth 24 are formed such that the lead angle decreases as the force moves from the upper end to the lower end.

On the other hand, as shown in FIG. 4, the tooth grooves 34 in the female rotor 31 are formed so as to correspond to the teeth 24 of the male rotor 21, and the number of tooth grooves 34 is six. . That is, since the number of teeth 24 of the male rotor 21 is smaller than the number of tooth grooves 34 of the female rotor 31, when both the rotors 21 and 31 rotate synchronously, the rotational speed of the male rotor 21 is The rotation speed becomes higher than the rotation speed, and the rotation speed of the female rotor 31 becomes lower than the rotation speed of the male rotor 21. Such screw type rotors 21 and 31 are referred to as a gradual change type.

As shown in FIGS. 1 and 2, the rotating shaft 25 of the male rotor 21 extends so as to penetrate the lower housing member 13, and the lower end of the rotating shaft 25 is located in the gear case 18. . A synchronous gear 47 is attached to a portion of the rotary shaft 25 located in the gear case 18. On the other hand, the rotating shaft 35 of the female rotor 31 also extends so as to penetrate the lower housing member 13, and the lower end of the rotating shaft 35 is located in the gear case 18. A synchronous gear 57 is attached to a part of the rotating shaft 35 located in the gear case 18. Both synchronous gears 47 and 57 are meshed with each other.

As shown in FIG. 1, the synchronous gear 47 on the male rotor 21 side is meshed with an intermediate gear 50 provided in the gear case 18. The intermediate gear 50 is meshed with the drive gear 20 provided on the drive shaft 19 of the drive motor 17 in the gear case 18. An oil storage chamber 61 that forms an oil storage space is formed in the lower portion of the gear case 18, and the lubricating oil 62 is stored in the oil storage chamber 61.

[0030] A cylindrical protrusion 63 is formed in a portion of the bottom plate portion 18a of the gear case 18 facing the lower end of the rotating shaft 25. As shown in FIG. 5, the protrusion 63 has a bottomed round hole 63a. Defined. In the round hole 63a, a trochoid oil supply pump 70 is disposed as an oil supply unit. The oil supply pump 70 has an outer rotor 72 made of an internal gear and an inner rotor 71 made of an external gear, and the inner one-portion 71 is arranged inside the outer rotor 72. The outer peripheral surface of the outer rotor 72 is fitted to the inner peripheral surface of the round hole 63a in a rotatable state. The lower end of the rotating shaft 25 is fitted and fixed in the through hole 71a of the inner rotor 71.

The inner rotor 71 is eccentric with respect to the outer rotor 72. When the inner rotor 71 rotates, the outer rotor 72 rotates accordingly. The upper end opening of the cylindrical protrusion 63 is closed by the upper cover 73, and the upper cover 73 covers the inner rotor 71 and the outer rotor ₇₂ . The oil supply pump 70 has an oil suction part 75 and an oil discharge part 76. The oil suction part 75 communicates with the oil storage chamber 61. The oil discharge section 76 communicates with the oil supply path 46 of the rotary shaft 25 through a guide path 77 formed on the bottom surface of the round hole 63a.

[0032] As the rotary shaft 25 rotates, the lubricating oil 62 stored in the oil storage chamber 61 is sucked into the oil pump 70, specifically, the space between the rotors 71 and 72, through the oil suction portion 75. It is. Lubricating oil is conveyed through the space between the rotors 71 and 72 to the oil discharge section 76, and is supplied from the oil discharge section 76 to the oil supply path 46 through the guide path 77.

On the other hand, as shown in FIG. 2, a cylindrical protrusion 64 is formed at the bottom plate portion 18 a of the gear case 18 facing the lower end of the rotating shaft 35. The protrusion 64 defines a bottomed round hole 64a. A trochoid oil supply pump 80 as an oil supply device is disposed in the round hole 64a. Although the detailed configuration of the oil pump 80 is not shown, it is equivalent to the oil pump 70 described above. That is, the oil supply pump 80 has an inner rotor 81 and an outer rotor 82. The outer peripheral surface of the outer rotor 82 is fitted to the inner peripheral surface of the round hole 64a in a rotatable state, and the inner rotor 81 is connected to the rotary shaft 35. The inner rotor 81 and the outer rotor 82 are covered with an upper cover 83. Although not shown, the oil supply pump 80 has an oil suction portion that communicates with the oil storage chamber 61 and an oil discharge portion that communicates with the oil supply passage 56 through the guide passage 87. When the inner rotor 81 rotates together with the rotating shaft 35, the outer rotor 82 rotates accordingly, and the lubricating oil in the oil storage chamber 61 is rotated. 62 is supplied to the oil supply path 56 through the oil suction section, the space between the rotors 81 and 82, the oil discharge section, and the guide path 87.

Incidentally, the vacuum pump 10 according to this embodiment has a configuration for cooling the lubricating oil 62 stored in the gear case 18. That is, the bottom plate portion 18a of the gear case 18 is formed with a plurality of cooling passages 88 through which cooling water as a cooling fluid passes. The cooling water passage 88 extends so as to pass through the bottom plate portion 18a, and the cooling oil passes through the cooling water passage 88, whereby the lubricating oil 62 stored in the gear case 18 is cooled. The cooling water passage 88 functions as a cooling unit that cools the lubricating oil 62 using the cooling fluid.

As shown in FIG. 1, the upstream portion of the cooling water passage 88 is connected to an upstream piping 89 having a solenoid valve 91 as a flow rate changing portion, and the downstream portion of the cooling water passage 88 is a downstream piping. Connected to 90. The solenoid valve 91 is controlled to open and close the upstream pipe 89 by a control device 92 as a control unit. The control device 92 is connected to a temperature sensor 93 that directly measures the temperature of the lubricating oil 62 in the gear case 18. The temperature sensor 93 is disposed in the gear case 18, that is, in the oil storage chamber 61. The control device 92 controls the electromagnetic valve 91 based on a detection signal from a temperature sensor 93 that maintains the temperature of the lubricating oil 62 in the gear case 18 constant.

Next, the operation of the vacuum pump 10 according to this embodiment will be described. When the drive motor 17 is rotated, the rotation of the drive motor 17 is transmitted to the synchronous gear 47 of the male port motor 21 through the drive gear 20 and the intermediate gear 50. Then, both synchronous gears 47 and 57 rotate synchronously, and the rotors 21 and 31 together with the rotating shafts 25 and 35 rotate. When both the rotors 21 and 31 rotate while the teeth 24 of the male rotor 21 and the tooth grooves 34 of the female rotor 31 are in contact with each other, the compressive fluid is sucked into the working chamber from the suction port 15. The compressive fluid sucked into the working chamber is transported toward the discharge port 16 while being compressed by both the rotors 21, 31, and discharged from the discharge port 16. When the suction port 15 is connected to a closed space such as a room or a container, these closed spaces can be evacuated.

[0037] When the vacuum pump 10 is in an operating state, the rotary shafts 25 and 35 are rotated at high speeds in opposite directions. The oil supply pumps 70 and 80 provided at the ends of the rotary shafts 25 and 35 suck the lubricating oil 62 stored in the oil storage chamber 61 from the respective oil suction portions, and each oil Discharge from the discharge part. The discharged lubricating oil 62 flows into the lower ends of the long pipes 44 and 54 of the rotary shafts 25 and 35 through the planned passages 77 and 87 connected to the respective oil discharge portions, and passes through the short pipes 45 and 55, respectively. As a result, it reaches the lower side of the end side bearing portions 42 and 52.

[0038] When the lubricating oil 62 that has reached the lower side of the end side bearing portions 42, 52 passes through the oil recovery passages 48, 58 and is directed downward, the rotating shafts 25, 35 and the shaft holders 28, 38 are Cooling. The temperature difference between the rotary shafts 25 and 35 and the shaft holders 28 and 38 is suppressed by cooling off the rotary shafts 25 and 35 and the shaft holders 28 and 38. The lubricating oil 62 is recovered in the oil storage chamber 61 in the gear case 18 after cooling the rotary shafts 25 and 35 and the shaft holders 28 and 38. The lubricating oil 62 is again transferred from the oil storage chamber 61 to the oil supply pumps 70 and 80, and the same operation as described above is repeated. The lubricating oil 62 also lubricates the synchronous gears 47 and 57 by passing through the synchronous gears 47 and 57 while being collected in the oil storage chamber 61.

Further, the lubricating oil 62 stored in the gear case 18 is cooled by the cooling water passing through the cooling water passage 88. That is, in this embodiment, the lubricating oil 62 is cooled using the cooling water so that the temperature of the lubricating oil 62 provided for cooling by the operation of the oil supply pumps 70 and 80 is kept constant. Specifically, the control device 92 monitors the temperature of the lubricating oil 62 through the temperature sensor 93 and controls the electromagnetic valve 91 so that the temperature of the lubricating oil 62 is maintained at a preset cooling temperature. The control device 92 opens and closes the electromagnetic valve 91 according to the temperature of the lubricating oil 62 detected by the temperature sensor 93 to adjust the flow of the cooling water in the cooling water passage 88. In other words, when the temperature of the lubricating oil 62 is likely to rise, the control device 92 opens the solenoid valve 91 and passes the cooling water through the cooling water passage 88 to prevent the temperature of the lubricating oil 62 in the gear case 18 from rising. To do. In addition, when the temperature of the lubricating oil 62 is likely to be low, the control device 92 closes the solenoid valve 91 so that the cooling water does not pass through the cooling water passage 88 and cools the lubricating oil 62 with the cooling water. Do not do it. In this case, the heat of the lubricating oil 62 collected in the oil storage chamber 61 prevents the temperature of the lubricating oil 62 stored in the oil storage chamber 61 from decreasing.

[0040] By passing the lubricating oil 62 maintained at a constant temperature through the oil recovery passages 48, 58, the temperature difference between the rotary shafts 25, 35 and the shaft holders 28, 38 is suitably suppressed, and the rotary shaft 25 The thermal expansion of 35 is suppressed. As a result, the thermal expansion of the rotary shafts 25 and 35 is preferably suppressed from applying an axial load to the bearings 42a, 42b, 43a, 43b, 52a, 52b, 53a and 53b. The vacuum pump 10 according to this embodiment has the following advantages.

(1) Based on the detection result of the temperature of the lubricating oil 62 by the temperature sensor 93, the control device 92 controls the solenoid valve 91. Thereby, the flow rate of the cooling water is adjusted so that the lubricating oil 62 stored in the oil storage chamber 61 is maintained at a constant temperature. By passing the lubricating oil 62 maintained at a constant temperature through the oil recovery passages 48 and 58, the rotary shafts 25 and 35 and the shaft holders 28 and 38 can be cooled. As a result, it is possible to suppress the occurrence of a temperature difference between the rotating shaft 25 and the shaft holder 28 and the occurrence of a temperature difference between the rotating shaft 35 and the shaft holder 38.

(2) Anguilla ball bearings 42a, 42b, 43a, 43b, 52a, 52b, 53a, 53b are fixed to the rotary shafts 25, 35 and the shaft holders 28, 38 so as not to move in the axial direction. However, in this embodiment, the occurrence of a temperature difference between the rotary shafts 25 and 35 and the shaft holders 28 and 38 is suppressed, so that the axial directions of the rotary shafts 25 and 35 relative to the shaft holders 28 and 38 are reduced. The thermal expansion force that causes the displacement to S is suppressed. Therefore, it is possible to suitably suppress the axial load force S from being applied to the bearings 42a, 42b, 43a, 43b, 52a, 52b, 53a, 53b.

(3) Each bearing 42a, 42b, 43a, 43b, 52a, 52b, 53a, 53b can be restrained from applying a load force S, thus improving the reliability of each bearing and the power consumption of the vacuum pump 10. Can also be reduced.

(4) Since it is possible to suppress the load force S from being applied to each bearing 42a, 42b, 43a, 43b, 52a, 52b, 53a, 53b, the end side bearing portions 42, 52 and the base side bearing portion 43, The degree of freedom of arrangement of the bearing portions 43 and 53 with respect to the rotary shafts 25 and 35 is improved, for example, the distance between them can be set large.

(5) Since the bearings 42a, 42b, 43a, 43b, 52a, 52b, 53a, 53b are fixed to the rotary shafts 25, 35 and the shaft holders 28, 38, the horizontal and vertical runout of the rotary shafts 25, 35 The vibration and noise in the vacuum pump 10 can be suppressed regardless of the rotational speed of the rotary shafts 25 and 35.

(6) Since the lubricating oil 62 is supplied to the oil recovery passages 48 and 58 below the end side bearing portions 42 and 52, the lubricating oil 62 supplied to the oil recovery passages 48 and 58 is Due to the influence of sliding heat of the side bearings 42 and 52, the temperature control of the lubricating oil 62 in the oil recovery passages 48 and 58 becomes easy.

(7) In the middle of the recovery of the lubricating oil 62 to the oil storage chamber 61, the synchronous oil 47, 57 Therefore, the synchronization gears 47 and 57 can be lubricated.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications such as the following can be made within the scope of the gist of the invention.

Oil pumps 70 and 80 may be gear pumps instead of trochoid pumps.

[0043] The lead angle of the teeth of the male rotor and the female rotor tooth groove may be constant! /.

In the above embodiment, each bearing portion may be configured by a force front combination or a parallel combination formed by a back combination of two angular ball bearings. Further, each bearing portion is not limited to an angular ball bearing, and may be constituted by a general deep groove type rolling bearing. Further, the number of rolling bearings is not particularly limited, and each bearing portion may be constituted by three or more rolling bearings. In addition, the back combination of an anguilla ball bearing is preferred to prevent the side shaft of the rotating shaft from swinging against the shaft holder.

[0044] Instead of the open / close switching type electromagnetic valve 91, a thermostat may be used, or a flow rate control valve whose opening degree can be adjusted by proportional control may be used.

The short pipes 45 and 55 may be provided on the upper side of the end side bearing portions 42 and 52, and the lubricating oil may be supplied from the upper side of the end side bearing portions 42 and 52. In this case, the lubricating oil is affected by the sliding heat of the end side bearing portions 42 and 52, but if the lubricating oil is cooled in consideration of the influence of the sliding heat, the effect almost the same as that of the above embodiment is obtained. Obtainable.

[0045] The shaft holder 28 on the male rotor side 21 and the shaft holder 38 on the female rotor 31 side may be completely separate from each other. In this case, both shaft holders 28 and 38 can be easily manufactured and the vacuum pump can be assembled.

[0046] The screw type fluid machine of the present invention is not limited to the screw type vacuum pump, but may be applied to a screw type compressor.

Claims

The scope of the claims

[1] a housing;

A pair of screw-shaped rotors housed in the housing and mated with each other; and a pair of rotating shafts connected to the two rotors so as to be coaxial with each other, each rotating shaft protruding from the housing force Having an end,

A pair of cylindrical shaft holders extending in the housing, each shaft holder having a first end and a second end, and having a through-hole through which one of the rotating shafts is inserted. To do

A first bearing portion mounted in the through hole at the first end portion; and a second bearing portion mounted in the through hole at the second end portion, the first and second bearings. Each pair of parts rotatably supports the corresponding rotating shaft with respect to the shaft holder, and each pair of the first and second bearing parts supports the corresponding rotating shaft and the shaft holder. Fixed in the axial direction,

A synchronous gear provided at each of the ends of the two rotating shafts protruding from the housing force;

A gear case in which the synchronous gear is housed, the gear case defining an oil storage space in which lubricating oil can be stored;

A cooling unit that cools the lubricating oil using a cooling fluid;

A flow rate changing unit for controlling the flow rate of the cooling fluid;

A temperature sensor that is provided in the oil storage space and detects the temperature of the lubricating oil; and a temperature detected by the temperature sensor so that the temperature of the lubricating oil in the oil storage space is maintained constant. And a control unit for controlling the flow rate changing unit according to

A screw type fluid machine comprising:

[2] The screw type fluid machine according to [1], wherein each of the first and second bearing portions is configured by a combination of at least two rolling bearings.

[3] The screw type fluid machine according to claim 2, wherein the rolling bearing includes an anguilla ball bearing.

[4] The cooling section extends in the gear case so as to allow the cooling fluid to pass therethrough. The screw type fluid machine according to any one of claims 1 to 3, comprising a cooling water passage.

[5] Any one of claims 1 to 4, further comprising oil supply units respectively driven by the rotary shaft to cool the shaft holder and the rotary shaft using the lubricating oil in the oil storage space. The screw type fluid machine according to one item.

[6] A gap is provided between the inner peripheral surface of each shaft holder and the corresponding outer peripheral surface of the rotary shaft, and the rotary shaft has an inlet opening at the end of the rotary shaft. An oil supply passage having an outlet communicating with the gap is formed, and the oil supply portion is a pump provided at the end portion of each rotating shaft, and the pump corresponds to lubricating oil in the oil storage space. The screw-type fluid machine according to claim 5, wherein the screw-type fluid machine is supplied to an inlet of an oil supply passage of the rotary shaft.