JP2019056336A - Scroll type fluid machine - Google Patents

Abstract

To provide a scroll type fluid machine which enables a fluid including a lubrication oil to be supplied to the lip seal side regardless of a position of a counter weight.SOLUTION: A second supply passage 63 which supplies a fluid from the counter weight 40 side to the lip seal 59 side and a second return passage 64 which returns the fluid from the lip seal 59 side to the counter weight 40 side are formed at a press-fit part of a front housing 4 into which a main bearing 14 formed by a slide bearing, which rotatably supports a driving shaft 8 located between a counter weight 40 and a lip seal 59, is press-fitted. Further, a third supply passage 65 which introduces the fluid from the scroll unit 6 side to an inlet of the second supply passage 63 is formed at a crank chamber 53 of the front housing 4 in which the counter weight 40 is rotatably housed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a scroll type fluid machine that compresses or expands fluid by changing the volume of a compression chamber partitioned by a fixed scroll and a turning scroll.

  As an example of the scroll type fluid machine, as described in Japanese Patent Application Laid-Open No. 2004-300974 (Patent Document 1), a scroll type compressor having a fixed scroll and a turning scroll engaged with each other is known. In the scroll compressor, the orbiting scroll revolves around the axis of the fixed scroll by the drive unit including the drive shaft, thereby changing the volume of the compression chamber partitioned by the fixed scroll and the orbiting scroll, Compress and discharge.

  One end portion of the drive shaft extends through the housing containing the fixed scroll and the orbiting scroll, and is rotatably supported by the housing via a rolling bearing such as a roller bearing. The other end portion of the drive shaft is rotatably supported with respect to the housing via a rolling bearing such as a roller bearing or a needle bearing. In this case, a lip seal is disposed between the outer peripheral surface of the one end portion of the drive shaft and the inner peripheral surface of the housing to prevent the gaseous refrigerant containing the lubricating oil from leaking to the outside.

JP 2004-3000974 A

  By the way, in a scroll compressor, for example, for the purpose of improving high-speed performance, impact resistance, and quietness, it is considered to use a sliding bearing instead of a rolling bearing that supports the other end of the drive shaft. ing. However, if a sliding bearing is used instead of the rolling bearing, the gas refrigerant containing the lubricating oil is difficult to flow in the axial direction through the sliding bearing, so that there is a risk that the lip seal located downstream thereof will be insufficiently lubricated. there were.

  For this reason, it is conceivable to form a supply passage for supplying the gaseous refrigerant to the lip seal side and a return passage for returning the gaseous refrigerant supplied to the lip seal side in the press-fitting portion of the casing into which the slide bearing is pressed. . However, depending on the position of the counterweight for reducing the vibration generated by the revolving orbiting motion of the orbiting scroll, the inlet of the supply passage is blocked, making it difficult for the gas refrigerant to flow.

  Therefore, an object of the present invention is to provide a scroll type fluid machine that can supply a fluid containing lubricating oil to the lip seal side regardless of the position of the counterweight.

  For this reason, it has a scroll unit that compresses or expands a fluid, a drive shaft that transmits a rotational drive force to the scroll unit, and a housing that rotatably accommodates the drive shaft, and the drive shaft passes through the housing. The scroll type fluid machine that reduces the vibration by the counterweight that rotates integrally with the drive shaft while the seal is sealed by the lip seal is a sliding bearing that freely supports the drive shaft located between the counterweight and the lip seal. It has. In addition, a first fluid supply passage for supplying fluid from the counterweight side to the lip seal side and a first fluid return passage from the lip seal side to the counterweight side to the press-fitting portion of the housing into which the slide bearing is press-fitted And a fluid introduction passage for introducing fluid from the scroll unit side to the inlet of the first fluid supply passage is formed in the crank chamber of the housing in which the counterweight is rotatably accommodated. .

  According to the present invention, gas refrigerant containing lubricating oil can be supplied to the lip seal side regardless of the position of the counterweight.

It is sectional drawing which shows an example of a scroll type compressor. It is a top view which shows an example of the arrangement structure of a counterweight. It is a perspective view which shows the principal part of the housing in which the main bearing was press-fitted. It is a perspective view which shows the principal part of the housing which removed the main bearing. It is a perspective view which shows the external shape of a front housing. It is the fragmentary sectional view which expanded the principal part of the scroll compressor.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.
As the scroll type fluid machine, either a compressor or an expander can be used. Here, a scroll type compressor will be described as an example.

FIG. 1 shows an example of a scroll compressor 1 attached to an engine room of a vehicle.
The scroll compressor 1 is incorporated in a refrigerant circuit of a vehicle air conditioner, for example, and compresses and discharges a gaseous refrigerant (fluid) sucked from the low pressure side of the refrigerant circuit. Lubricating oil is sealed inside the scroll compressor 1, and the lubricating oil lubricates the bearing and the sliding portion and seals the sliding surface.

  The scroll compressor 1 includes a rear housing 2 and a front housing 4 constituting a housing, and a scroll unit 6 is accommodated in the front housing 4. The rear housing 2, the flange portion 29 of the fixed scroll 24 constituting the scroll unit 6, and the front housing 4 are fastened and joined by a plurality of bolts 5.

  In the inner space of the front housing 4, the drive shaft 8 is disposed so as to extend in the longitudinal direction (axial direction) of the front housing 4. The drive shaft 8 has a large-diameter shaft portion 10 located on the scroll unit 6 side, a small-diameter shaft portion 12 that is located at the end opposite to the scroll unit 6 and protrudes outside through the front housing 4; have. The large-diameter shaft portion 10 of the drive shaft 8 is rotatably supported by the front housing 4 via a main bearing 14, and the small-diameter shaft portion 12 is rotatably supported by the front housing 4 via a ball bearing 16. Yes. Therefore, the drive shaft 8 is supported to be freely rotatable with respect to the front housing 4.

  Here, the main bearing 14 is constituted by an oil-impregnated sliding bearing made of a porous sintered metal. The main bearing 14 has a cylindrical shape, and an outer peripheral surface thereof is press-fitted into a press-fit portion of the front housing 4, and the large-diameter shaft portion 10 of the drive shaft 8 is rotatably supported by the inner peripheral surface. . A clearance (radial clearance) between the main bearing 14 and the drive shaft 8 is set to a minimum.

  A lip seal 59 is attached to the through portion 4A of the front housing 4 through which the small diameter shaft portion 12 of the drive shaft 8 passes. The front end portion of the lip seal 59 is slidably pressed against the outer peripheral surface of the drive shaft 8, and gas refrigerant containing lubricating oil is prevented from leaking outside through the through portion 4 </ b> A.

  Further, a drive pulley 20 having a built-in electromagnetic clutch 18 is attached to the protruding end of the small diameter shaft portion 12. The drive pulley 20 is rotatably supported by the front housing 4 via a bearing 22. The rotation of the drive pulley 20 can be transmitted to the drive shaft 8 via the electromagnetic clutch 18. Therefore, when the electromagnetic clutch 18 is connected when the engine is driven, the drive shaft 8 rotates integrally with the drive pulley 20.

  The scroll unit 6 includes a fixed scroll 24 in which a flange portion 29 is sandwiched between the rear housing 2 and the front housing 4, and a turning scroll 26 assembled so as to mesh with the fixed scroll 24. . The fixed scroll 24 includes a disk-shaped substrate 25 and a spiral-shaped wrap 27 erected on one surface of the substrate 25. On the peripheral surface of the substrate 25, there are formed an inlay portion 28 that is inserted into the inner peripheral surface of the front housing 4 and mated, and a flange portion 29 that protrudes outward from the rear housing 2 side of the inlay portion 28. Yes.

  In the fixed scroll 24, the inlay portion 28 of the substrate 25 is inserted and engaged with the front housing 4, and in this state, the flange portion 29 comes into contact with the opening end portion of the front housing 4. In FIG. 1, a member denoted by reference numeral 37 is an O-ring that seals between the spigot portion 28 and the front housing 4.

  The orbiting scroll 26 includes a disk-shaped substrate 30 and a spiral-shaped wrap 33 that is erected on one surface of the substrate 30 and meshes with the wrap 27 of the fixed scroll 24. When the wrap 27 of the fixed scroll 24 and the wrap 33 of the orbiting scroll 26 are engaged with each other, the tip of the wrap 33 comes into slidable contact with one surface of the substrate 25 of the fixed scroll 24, and the tip of the wrap 27 is The orbiting scroll 26 abuts on one surface of the substrate 30 so as to freely slide.

  The orbiting scroll 26 revolves around the axis of the fixed scroll 24 by being rotationally driven by the drive shaft 8. When the orbiting scroll 26 revolves, the wrap 27 of the fixed scroll 24 and the wrap 33 of the orbiting scroll 26 are engaged with each other, and a compression chamber 35 for compressing a gaseous refrigerant containing lubricating oil is formed therein. The At this time, the volume of the compression chamber 35 increases or decreases with the revolution orbiting motion of the orbiting scroll 26 relative to the fixed scroll 24.

  In order to revolve the orbiting scroll 26, the boss 32 projecting from the other surface of the substrate 30 of the orbiting scroll 26 and the large-diameter shaft portion 10 of the drive shaft 8 include a crank pin 34, an eccentric bush 36 and a needle bearing 38. Are interconnected via Further, as shown in FIG. 2, a counterweight 40 having a substantially semicircular shape in plan view is attached to the eccentric bush 36. The counterweight 40 rotates integrally with the eccentric bush 36 and cancels and reduces vibrations generated by the orbiting scroll 26 revolving around the axis of the fixed scroll 24. For this reason, the front housing 4 is formed with a cylindrical crank chamber 53 for accommodating and rotating the counterweight 40. Here, the drive shaft 8 having the large-diameter shaft portion 10 and the small-diameter shaft portion 12, and the drive portion 15 that drives the orbiting scroll 26 by the crank pin 34, the eccentric bush 36, and the counterweight 40 that rotate together with the drive shaft 8 are provided. It is configured.

  An annular support surface 31 that supports the thrust force of the scroll unit 6 is formed inside the front housing 4. An annular thrust plate 42 is supported on the support surface 31. The thrust plate 42 is disposed between the other surface of the substrate 30 of the orbiting scroll 26 and the support surface 31 of the front housing 4, and supports the orbiting scroll 26 so as to be capable of revolving orbiting. That is, the support surface 31 and the thrust plate 42 of the front housing 4 serve as a thrust support portion that supports the orbiting scroll 26 so as to be capable of revolving orbiting.

  A discharge chamber 44 is formed between the fixed scroll 24 and the end wall 43 of the rear housing 2. A discharge hole 45 that allows the compression chamber 35 and the discharge chamber 44 to communicate with each other is formed in the substrate 25 of the fixed scroll 24. A discharge valve 46 that opens and closes the discharge hole 45 is disposed in the discharge chamber 44. In addition, a discharge port 51 that opens to the discharge chamber 44 is formed in the rear housing 2.

  In FIG. 1, a member denoted by reference numeral 61 is an attachment portion formed on the outer surface of the front housing 4, and a member denoted by reference numeral 62 is an attachment formed on the outer surface of the end wall 43 of the rear housing 2. Part. The scroll compressor 1 is attached to a predetermined location (attachment location) of the engine room with bolts through these attachment portions 61 and 62.

  A low-pressure gas is placed on the peripheral wall of the front housing 4 on the scroll unit 6 side of the drive shaft 8 so as to straddle the thrust plate 42 and the substrate 30 at a position facing the outer periphery of the substrate 30 of the thrust plate 42 and the orbiting scroll 26. A suction port 49 for introducing the refrigerant is formed. The center line C1 of the suction port 49 is offset from the thrust plate 42 toward the scroll unit 6 by a predetermined distance. For this reason, the flow path cross-sectional area of the suction port 49 is larger on the scroll unit 6 side indicated by reference numeral 49A than on the drive unit 15 side indicated by reference numeral 49B across the thrust plate 42.

  When a cylindrical slide bearing is used as the main bearing 14 that rotatably supports the large-diameter shaft portion 10 of the drive shaft 8 positioned between the counterweight 40 and the lip seal 59, lubrication sucked from the suction port 49 is performed. The flow rate at which the gaseous refrigerant containing oil is supplied to the lip seal 59 through the main bearing 14 is reduced. Therefore, as will be described below, a supply passage that supplies the lip seal 59 with the gaseous refrigerant containing the lubricating oil sucked from the suction port 49 and the gaseous refrigerant containing the lubricating oil supplied to the lip seal 59 are sucked. By providing a return passage returning to the port 49 side, lubrication of the lip seal 59 is ensured.

3 and 4 show an example of the supply passage and the return passage.
A first supply passage 47 extending in the radial direction from the outer peripheral end of the support surface 31 toward the inner peripheral end is formed at a predetermined position on the support surface 31 of the front housing 4 facing the suction port 49. Further, a predetermined portion of the support surface 31 of the front housing 4 opposite to the first supply passage 47 across the axis of the drive shaft 8 extends in a radial direction from the outer peripheral end toward the inner peripheral end. A first return passage 48 is formed. Accordingly, the first supply passage 47 supplies the crank chamber 53 with the gaseous refrigerant containing the lubricating oil sucked from the suction port 49 formed in the peripheral wall of the front housing 4. The first return passage 48 returns the gaseous refrigerant containing the lubricating oil from the crank chamber 53 to the suction port 49 side. Here, the first supply passage 47 and the first return passage 48 are examples of the second fluid supply passage and the second fluid return passage, respectively.

  The first supply passage 47 is formed of a concave groove that gradually increases in depth and gradually decreases in width from the outer peripheral end to the inner peripheral end of the support surface 31. Further, the first return passage 48 is constituted by a concave groove having substantially the same width whose depth gradually increases from the outer peripheral end of the support surface 31 toward the inner peripheral end. That is, the first supply passage 47 and the first return passage 48 have a large inlet side of the gas refrigerant containing the lubricating oil, and therefore the gas refrigerant can flow smoothly.

  In the stroke in which the scroll unit 6 sucks, compresses and discharges the gaseous refrigerant, there is a portion where the thrust force acting on the thrust plate 42 and the support surface 31 from the orbiting scroll 26 is maximized. Therefore, it is desirable that the first supply passage 47 and the first return passage 48 be formed so as to avoid a portion where the thrust force is maximum.

  A second supply passage 63 and a second return passage 64 that extend along the axial direction of the main bearing 14 are formed at predetermined positions of the press-fitting portion of the front housing 4 into which the main bearing 14 is press-fitted. Here, the first supply passage 47 and the second supply passage 63 are formed on the same straight line passing through the axis of the drive shaft 8 when viewed from the direction perpendicular to the cross section of the drive shaft 8. Similarly to the first supply passage 47 and the second supply passage 63, the first return passage 48 and the second return passage 64 have a drive shaft as viewed from the direction perpendicular to the cross section of the drive shaft 8. It is formed on the same straight line passing through the eight axes. Therefore, the second supply passage 63 supplies a gaseous refrigerant containing lubricating oil from the counterweight 40 side to the lip seal 59 side. The second return passage 64 returns the gaseous refrigerant containing the lubricating oil from the lip seal 59 side to the counterweight 40 side. Here, the second supply passage 63 and the second return passage 64 are examples of the first fluid supply passage and the first fluid return passage, respectively.

  The second supply passage 63 and the second return passage 64 are constituted by concave grooves having substantially the same width, the depth of which gradually decreases from the scroll unit 6 side toward the lip seal 59 side. This is because the front housing 4 has a large diameter on the scroll unit 6 side and a small diameter on the through portion 4A side, and the outer peripheral surface of the press-fitted portion into which the main bearing 14 is press-fitted has a conical shape. In order to adapt to the shape. As shown in FIG. 5, the outer peripheral surface of the front housing 4 positioned radially outward of the second supply passage 63 and the second return passage 64 is along the axial direction (longitudinal direction) of the front housing 4. A reinforcing rib 66 extending in a protruding manner is formed. By forming the reinforcing rib 66 on the outer peripheral surface of the front housing 4, it is possible to avoid the thickness of the outer wall of the portion where the second supply passage 63 and the second return passage 64 are located from being reduced. Strength can be secured.

  Note that the second supply passage 63 and the second return passage 64 are similar to the first supply passage 47 and the first return passage 48 in the stroke in which the scroll unit 6 sucks, compresses and discharges the gaseous refrigerant. It is desirable to avoid the location where the thrust force acting on the thrust plate 42 and the support surface 31 from the orbiting scroll 26 is maximized.

  By the way, when the counterweight 40 that rotates integrally with the eccentric bush 36 is positioned on the suction port 49 side as shown in FIG. 2, the inlet of the second supply passage 63 is closed by the counterweight 40, and the gas refrigerant is It becomes difficult to flow from the first supply passage 47 to the second supply passage 63. For this reason, the flow rate of the gaseous refrigerant supplied to the lip seal 59 is temporarily reduced, and during that time, the lip seal 59 tends to be insufficiently lubricated. When the counterweight 40 further rotates and moves away from the suction port 49 side, the inlet of the second supply passage 63 is opened and the circulation of the gaseous refrigerant is resumed.

  Therefore, a third supply passage 65 extending along the axial direction of the front housing 4 is formed at a predetermined location on the inner peripheral surface of the crank chamber 53. The third supply passage 65 is formed of a concave groove having substantially the same width, and communicates the outlet of the first supply passage 47 and the inlet of the second supply passage 63, and the second supply passage 63 from the scroll unit 6 side. Introduce gaseous refrigerant to the inlet. In this way, regardless of the position of the counterweight 40 with respect to the front housing 4, the first supply passage 47 and the second supply passage 63 communicate with each other so that gaseous refrigerant can be constantly supplied to the lip seal 59 side. it can. Here, the third supply passage 65 is an example of the fluid introduction passage.

Next, the operation of the scroll compressor 1 will be described.
When the electromagnetic clutch 18 is operated in a state where the rotational driving force of an engine (not shown) is transmitted to the driving pulley 20, the driving shaft 8 rotates integrally with the driving pulley 20. When the drive shaft 8 rotates, the rotational driving force is transmitted to the orbiting scroll 26 of the scroll unit 6 via the crank pin 34, the eccentric bush 36 and the needle bearing 38, and the shaft of the fixed scroll 24 does not rotate. Revolves around the mind. When the orbiting scroll 26 revolves, the gaseous refrigerant containing the lubricating oil is sucked into the inside from the suction port 49 of the front housing 4. The gas refrigerant sucked from the suction port 49 is divided into the scroll unit 6 side and the drive unit 15 side because of the thrust plate 42. At this time, as described above, the flow path cross-sectional area of the suction port 49 is larger on the scroll unit 6 side (49A) than the drive unit 15 side (49B) across the thrust plate 42. The amount of the gas refrigerant that is diverted to the flow increases more than the gas refrigerant that is diverted to the drive unit 15 side.

  Then, the gas refrigerant branched to the scroll unit 6 side is sucked into the compression chamber 35 located radially outward of the scroll unit 6 (suction stroke). As the orbiting scroll 26 revolves around the axis of the fixed scroll 24, the volume of the compression chamber 35 gradually decreases toward the center, and the gaseous refrigerant sucked into the compression chamber 35 is compressed (compression). Process). The compressed high-pressure gaseous refrigerant is discharged from the scroll compressor 1 from the compression chamber 35 through the discharge hole 45, the discharge valve 46, the discharge chamber 44 and the discharge port 51.

  On the other hand, the gaseous refrigerant branched to the drive unit 15 side flows into the first supply passage 47 and passes through the first supply passage 47 to the crank chamber 53 as shown by the broken arrow in FIG. Supplied. At this time, if the counterweight 40 is at a position away from the suction port 49, the gas refrigerant supplied to the crank chamber 53 is slid by sliding parts such as the crank pin 34 and the eccentric bush 36 by the lubricating oil contained therein. Lubricate.

  A part of the gaseous refrigerant supplied to the crank chamber 53 flows into a third supply passage 65 formed on the inner peripheral surface of the crank chamber 53 as shown in FIG. At this time, since the third supply passage 65 is formed on the inner peripheral surface of the crank chamber, the gaseous refrigerant that has passed through the first supply passage 47 can be always allowed to flow regardless of the position of the counterweight 40. it can. If the counterweight 40 is positioned on the suction port 49 side, the gaseous refrigerant supplied to the crank chamber 53 via the first supply passage 47 is preferentially supplied to the third supply passage 65 and the second supply passage 65. The supply passage 63 is supplied to the lip chamber. For this reason, when the counterweight 40 is located on the suction port 49 side, the lubricating ability of the lip seal 59 can be improved.

  The gaseous refrigerant that has flowed into the third supply passage 65 passes through the inside thereof and is supplied to the main bearing 14 side. The gas refrigerant supplied to the main bearing 14 side flows into the second supply passage 63 and passes through the second supply passage 63 as shown by the broken arrow in FIG. It is supplied into the front housing 4 (lip chamber) located between them. The gaseous refrigerant supplied to the lip chamber lubricates the sliding portion of the lip seal 59 with the lubricating oil contained therein, and then returns to the crank chamber 53 via the second return passage 64. Further, the lubricating oil contained in the gas refrigerant passing through the second supply passage 63 and the second return passage 64 and the gas refrigerant passing around the main bearing 14 is absorbed from the surface by the main bearing 14 including the oil-impregnated sliding bearing. Therefore, the sliding portion of the large-diameter shaft portion 10 of the drive shaft 8 is also lubricated.

  The gaseous refrigerant returned to the crank chamber 53 flows into the first return passage 48, passes through the inside thereof, and is returned to the scroll unit 6 side, that is, the suction port 49 side. The gaseous refrigerant returned to the scroll unit 6 side is sucked into the compression chamber 35 located radially outward of the scroll unit 6, and is compressed and discharged through the suction stroke and the compression stroke as described above.

  Depending on the position of the counterweight 40, the inlet of the first return passage 48 is blocked by the counterweight 40, so a third return passage may be further formed on the inner peripheral surface of the crank chamber 53. . In this case, the third return passage is formed by a concave groove having substantially the same width extending along the axial direction of the crank chamber 53, and communicates the outlet of the first return passage 48 and the inlet of the second return passage 64. . In this way, the gas refrigerant supplied to the lip chamber can always flow to the suction port 49 side regardless of the position of the counterweight 40, and the pressure in the lip chamber does not increase excessively. The influence on the supply of the gaseous refrigerant supplied to the lip chamber via the one supply passage 47, the second supply passage 63, and the third supply passage 65 can be reduced.

  About the said embodiment, a new modification can be produced by combining the technical idea demonstrated there arbitrarily, or rearranging the one part. Therefore, it should be understood that the present invention is not limited to the contents described in the above embodiment, and includes technical ideas that can be easily conceived by those skilled in the art.

1 Scroll type compressor (Scroll type fluid machine)
2 Rear housing 4 Front housing 4A Through part 6 Scroll unit 8 Drive shaft 14 Main bearing (sliding bearing)
31 Support surface 40 Counterweight 47 First supply passage (second fluid supply passage)
48 First return passage (second fluid return passage)
49 Suction port 53 Crank chamber 59 Lip seal 63 Second supply passage (first fluid supply passage)
64 Second return passage (first fluid return passage)
65 Third supply passage (fluid introduction passage)

Claims (5)

A scroll unit that compresses or expands a fluid; a drive shaft that transmits a rotational drive force to the scroll unit; and a housing that rotatably accommodates the drive shaft, and the drive shaft passes through the housing. In a scroll type fluid machine that seals a part with a lip seal and reduces vibration by a counterweight that rotates integrally with the drive shaft,
A sliding bearing that rotatably supports the drive shaft positioned between the counterweight and the lip seal;
A first fluid supply passage for supplying fluid from the counterweight side to the lip seal side and a fluid from the lip seal side to the counterweight side into the press-fit portion of the housing into which the slide bearing is press-fitted. A first fluid return passage is formed,
A fluid introduction passage for introducing fluid from the scroll unit side to the inlet of the first fluid supply passage is formed in the crank chamber of the housing in which the counterweight is rotatably accommodated.
Scroll type fluid machine. The fluid introduction passage is composed of a concave groove formed in an inner peripheral wall of the crank chamber.
The scroll type fluid machine according to claim 1. A second fluid supply passage for supplying fluid sucked from a suction port formed in a peripheral wall of the housing to the crank chamber on a support surface of the housing that supports a thrust force of the scroll unit; and the crank chamber And a second fluid return passage for returning fluid from the suction port side to the suction port side,
The scroll type fluid machine according to claim 1 or 2. The second fluid supply passage and the second fluid return passage are formed on opposite sides of the axis of the drive shaft;
The scroll type fluid machine according to claim 3. The first fluid supply passage, the second fluid supply passage, and the fluid introduction passage are formed on the same straight line that passes through the axis of the drive shaft when viewed from the direction perpendicular to the cross section of the drive shaft. The
The scroll type fluid machine according to claim 3 or 4.