SCROLL FLUID MACHINE

Abstract

Lubricant is satisfactorily supplied to a bearing that supports an eccentric bush. A scroll compressor (100) includes a fixed scroll (122) fixed to a housing (140), an orbiting scroll (124) that orbits with respect to the fixed scroll, and a conversion mechanism (300) that mutually converts a rotary motion of a drive shaft (166) and an orbiting motion of the orbiting scroll. The converting mechanism includes an eccentric shaft (260) that is provided on an end surface of the drive shaft and is eccentric with respect to the drive shaft, an eccentric bush (270) having a through hole (271) into which the eccentric shaft is fitted, and a bearing (280) that is press-fitted into a boss portion (250) formed on the orbiting scroll and supports an outer peripheral surface (272) of the eccentric bush. A lubricant supply passage (350) for supplying lubricant to the bearing is penetratingly formed in the eccentric bush. An outlet (356) of the lubricant supply passage is disposed on the outer peripheral surface of the eccentric bush (272).

Description

TECHNICAL FIELD

The present invention relates to a scroll fluid machine such as a scroll compressor and a scroll expander.

BACKGROUND ART

Patent Document 1 discloses a scroll compressor which is an example of a scroll fluid machine. In this scroll compressor, a drive shaft is connected to an orbiting scroll via a crank mechanism. The crank mechanism includes a boss portion formed on a back pressure chamber side end surface of a bottom plate of the orbiting scroll and an eccentric bush eccentrically attached to a crank pin disposed at an end portion of the drive shaft. The eccentric bush is rotatably supported by an inner peripheral surface of the boss portion via a bearing.

REFERENCE DOCUMENT LIST

Patent Document

• Patent Document 1: JP 2019-015188 A

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

Lubrication of the aforementioned bearing is achieved by dispersing lubricant in the back pressure chamber formed on the rear surface side of the orbiting scroll, and as a result, supply of the lubricant to the bearing may become insufficient.

Thus, it is an object of the present invention to satisfactorily supply lubricant to a bearing supporting an eccentric bush.

Means for Solving the Problem

According to an aspect of the present invention, a scroll fluid machine has, in a housing, a rotating main shaft that is rotatably provided, a fixed scroll fixed to the housing, an orbiting scroll that orbits with respect to the fixed scroll, and a conversion mechanism that mutually converts a rotary motion of the rotating main shaft and an orbiting motion of the orbiting scroll. The converting mechanism includes an eccentric shaft that is provided on an end surface of the rotating main shaft and is eccentric with respect to the rotating main shaft, an eccentric bush having a through hole into which the eccentric shaft is fitted, and a bearing that is press-fitted into a boss portion formed on the orbiting scroll and supports an outer peripheral surface of the eccentric bush.

A lubricant supply passage for supplying lubricant to the bearing is penetratingly formed in the eccentric bush. Here, an outlet of the lubricant supply passage is disposed on the outer peripheral surface of the eccentric bush.

Effects of the Invention

According to an aspect of the present invention, the outlet of the lubricant supply passage is disposed on the outer peripheral surface of the eccentric bush. As a result, lubricant can be supplied directly from the outlet of the lubricant supply passage to the bearing, and thus, the lubricant can be satisfactorily supplied to the bearing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of a scroll compressor according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating how gaseous refrigerant and lubricant flow in the first embodiment.

FIG. 3 is an enlarged cross-sectional view of a conversion mechanism according to the first embodiment.

FIG. 4 is a perspective view of an eccentric bush according to the first embodiment.

FIG. 5 is a sectional view of the eccentric bush according to the first embodiment.

FIG. 6 is an enlarged cross-sectional view of a conversion mechanism according to a second embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described referring to the accompanying drawings. Here, a case in which a scroll fluid machine according to the present invention is a scroll compressor is described. It is, however, apparent that the present invention is also applicable to a scroll expander.

FIG. 1 is a longitudinal cross-sectional view of a scroll compressor 100 according to a first embodiment of the present invention.

The scroll compressor 100 is incorporated, for example, in a refrigerant circuit of an air conditioner for a vehicle, and compresses and discharges gaseous refrigerant (fluid) drawn from a low-pressure side of the refrigerant circuit. The scroll compressor 100 includes a scroll unit 120, a housing 140 that internally includes a suction chamber H1 and a discharge chamber H2 for gaseous refrigerant, an electric motor 160 that drives the scroll unit 120, and an inverter 180 that drives and controls the electric motor 160. The scroll unit 120 may be driven, for example, by an engine output instead of by the electric motor 160. The inverter 180 may not be incorporated in the scroll compressor 100.

The scroll unit 120 includes a fixed scroll 122 and an orbiting scroll (movable scroll) 124 engaged with each other. The fixed scroll 122 includes a disk-shaped bottom plate 122A and an involute-shaped (spiral-shaped) wrap 122B erected on one surface of the bottom plate 122A. Like the fixed scroll 122, the orbiting scroll 124 includes a disk-shaped bottom plate 124A and an involute-shaped wrap 124B erected on one surface of the bottom plate 124A. Here, being disk-shaped is satisfied with being visually recognizable as being disk-shaped, and may have an outer surface including, for example, a convex portion, a concave portion, or a slit (regarding the shape, the same will be applied hereinafter).

The fixed scroll 122 and the orbiting scroll 124 are disposed such that the wraps 122B and 124B are engaged with each other. Specifically, the fixed scroll 122 and the orbiting scroll 124 are disposed such that the tip of the wrap 122B of the fixed scroll 122 is in contact with the one surface of the bottom plate 124A of the orbiting scroll 124, and the tip of the wrap 124B of the orbiting scroll 124 is in contact with the one surface of the bottom plate 122A of the fixed scroll 122. A tip seal (not shown) is attached to each of the tips of the wraps 122B and 124B.

Furthermore, the fixed scroll 122 and the orbiting scroll 124 are disposed such that the circumferential angles of the wraps 122B and 124B are offset from each other and the sidewalls of the wraps 122B and 124B are partially in contact with each other. As a result, a crescent-shaped sealed space functioning as a compression chamber H3 is formed between the wrap 122B of the fixed scroll 122 and the wrap 124B of the orbiting scroll 124.

The orbiting scroll 124 orbits with respect to the fixed scroll 122. The orbiting scroll 124 is disposed to be capable of revolving around an axis of the fixed scroll 122 via a conversion mechanism 300, which will be described later, in a state in which rotation of the orbiting scroll 124 is prevented. Thus, the scroll unit 120 moves the compression chamber H3 defined by the wrap 122B of the fixed scroll 122 and the wrap 124B of the orbiting scroll 124 toward the center while gradually reducing the volume of the compression chamber H3. As a result, the scroll unit 120 compresses the gaseous refrigerant drawn into the compression chamber H3 from the outer end portions of the wraps 122B and 124B.

The housing 140 has a front housing 142 for housing the electric motor 160 and the inverter 180, a center housing 144 for housing the scroll unit 120, a rear housing 146, and an inverter cover 148. The front housing 142, the center housing 144, the rear housing 146, and the inverter cover 148 are integrally fastened, for example, by at least one fastener (not shown) including a bolt and a washer, so as to constitute the housing 140 of the scroll compressor 100.

The front housing 142 has a cylindrical peripheral wall portion 142A and a thin plate-like partition wall portion 142B. The internal space of the front housing 142 is partitioned by the partition wall portion 142B into a space for housing the electric motor 160 and a space for housing the inverter 180. One end side of the peripheral wall portion 142A, i.e., an opening of the space for housing the inverter 180, is closed by the inverter cover 148. The other end side of the peripheral wall portion 142A, i.e., an opening of the space for housing the electric motor 160, is closed by the center housing 144. At a radially center portion of the partition wall portion 142B, a cylindrical support portion 142B1 protruding toward the other end side of the peripheral wall portion 142A is provided. The support portion 142B1 rotatably supports one end portion of a drive shaft 166, which will be described later. Here, the drive shaft 166 is an example of the “rotating main shaft” of the present invention, and it is rotatably provided in the housing 140.

Furthermore, the suction chamber H1 for gaseous refrigerant is defined by the peripheral wall portion 142A and the partition wall portion 142B of the front housing 142, and the center housing 144. Gaseous refrigerant is drawn from the low-pressure side of the refrigerant circuit into the suction chamber H1 via a suction port P1 formed on the peripheral wall portion 142A. The suction chamber H1 is adapted to allow the gaseous refrigerant to flow around the electric motor 160 and cool the electric motor 160. Spaces on one side and the other side of the electric motor 160 communicate with each other so as to form the single suction chamber H1. An appropriate amount of lubricant is stored in the suction chamber H1 in order to lubricate sliding portions of components including the rotationally driven drive shaft 166. Accordingly, in the suction chamber H1, the gaseous refrigerant flows in the form of a mixed fluid with lubricant.

The center housing 144 has a bottomed cylindrical shape having an opening on the side opposite to the side at which the front housing 142 is fastened and is adapted to house the scroll unit 120 therein. The center housing 144 has a cylindrical portion 144A and a bottom wall portion 144B provided at one end side of the cylindrical portion 144A. The scroll unit 120 is housed in a space defined by the cylindrical portion 144A and the bottom wall portion 144B. At the other end side of the cylindrical portion 144A, a fitting portion 144A1 to which the fixed scroll 122 is fitted is formed. Accordingly, the opening of the center housing 144 is closed by the fixed scroll 122. The bottom wall portion 144B is formed such that a radially center portion thereof bulges toward the electric motor 160. A through hole for receiving the other end portion of the drive shaft 166 penetrating therethrough is formed at a radially center portion of such a bulging portion 144B1 of the bottom wall portion 144B. Furthermore, a fitting portion for receiving a bearing 200 fitted therein is formed on the side, closer to the scroll unit 120, of the bulging portion 144B1. The bearing 200 rotatably supports the other end portion of the drive shaft 166.

A thin annular thrust plate 210 is disposed between the bottom wall portion 144B of the center housing 144 and the bottom plate 124A of the orbiting scroll 124. The bottom wall portion 144B receives, at an outer peripheral portion, a thrust force from the orbiting scroll 124 via the thrust plate 210. Seal members 220 are embedded in respective portions, in contact with the thrust plate 210, of the bottom wall portion 144B and the bottom plate 124A.

A back pressure chamber H4 is formed between an electric motor 160 side end surface of the bottom plate 124A and the bottom wall portion 144B, i.e., between an end surface, opposite to the fixed scroll 122, of the orbiting scroll 124 and the center housing 144. The center housing 144 is provided with a refrigerant introduction passage L1 formed so as to introduce the gaseous refrigerant from the suction chamber H1 to a space H5 near the outer end portions of the wraps 122B and 124B of the scroll unit 120. Since the refrigerant introduction passage L1 allows the space H5 and the suction chamber H1 to communicate with each other, the pressure in the space H5 is equal to the pressure (suction pressure Ps) in the suction chamber H1.

The rear housing 146 is fastened to a fitting portion 144A1 side end portion of the cylindrical portion 144A of the center housing 144 with at least one fastener. Accordingly, the fixed scroll 122 is fixed with its bottom plate 122A held between the fitting portion 144A1 and the rear housing 146. That is, the fixed scroll 122 is fixed to the housing 140. The rear housing 146, which has a bottomed cylindrical shape having an opening on the side fastened to the center housing 144, has a cylindrical portion 146A and a bottom wall portion 146B provided at the other end portion of the cylindrical portion 146A.

The discharge chamber H2 for gaseous refrigerant is defined by the cylindrical portion 146A and the bottom wall portion 146B of the rear housing 146, and the bottom plate 122A of the fixed scroll 122. A discharge passage (discharge hole) L2 for gaseous refrigerant is formed at a central portion of the bottom plate 122A. The discharge passage L2 is provided with a check valve 230 formed, for example, of a reed valve. The check valve 230 restricts the flow of the gaseous refrigerant from the discharge chamber H2 to the scroll unit 120. The gaseous refrigerant having been compressed in the compression chamber H3 of the scroll unit 120 is discharged to the discharge chamber H2 through the discharge passage L2 and via the check valve 230.

Although not illustrated in the drawings, an oil separator for separating lubricant from the gaseous refrigerant in the discharge chamber H2 is disposed in the rear housing 146. The gaseous refrigerant, from which lubricant has been separated by the oil separator, is discharged to the high-pressure side of the refrigeration circuit via a discharge port P2 formed on the bottom wall portion 146B of the rear housing 146. On the other hand, the lubricant separated by the oil separator is supplied to the back pressure chamber H4 through a back pressure supply passage L3, which is described later.

The electric motor 160 is, for example, a three-phase alternating current motor, and includes a rotor 162 and a stator core unit 164 disposed radially outward of the rotor 162. The stator core unit 164 of the electric motor 160 is supplied with an alternating current converted, for example, from a direct current from an in-vehicle battery (not shown) by the inverter 180.

The rotor 162 is rotatably supported radially inside the stator core unit 164 via the drive shaft 166 that is press-fitted into a shaft hole formed at a radially center of the rotor 162. The one end portion of the drive shaft 166 is rotatably supported on the support portion 142B1 of the front housing 142 via a sliding bearing 240. The other end portion of the drive shaft 166 penetrates the through hole formed in the center housing 144 and is rotatably supported on the bearing 200. When power is supplied from the inverter 180, a magnetic field is generated in the stator core unit 164, and a torque acts on the rotor 162 to rotationally drive the drive shaft 166. The other end portion of the drive shaft 166 is connected to the orbiting scroll 124 via the conversion mechanism 300.

The conversion mechanism 300 has a function to mutually convert a rotary motion of the rotating main shaft (drive shaft 166 in this embodiment) and an orbiting motion of the orbiting scroll 124. The conversion mechanism 300 will be described in detail later, referring to FIGS. 3 to 5. In the present embodiment, the orbiting scroll 124 is disposed to be capable of revolving around the axis of the fixed scroll 122 via the conversion mechanism 300, in a state in which rotation of the orbiting scroll 124 is prevented. In addition, a balance weight (counterweight) 290 that counteracts the centrifugal force of the orbiting scroll 124 is attached to the other end portion of the drive shaft 166.

FIG. 2 is a block diagram for illustrating flows of gaseous refrigerant and lubricant in the scroll compressor 100.

As illustrated in FIGS. 1 and 2, low-pressure, low-temperature gaseous refrigerant from the refrigerant circuit is introduced into the suction chamber H1 via the suction port P1, and then is introduced into the space H5 near the outer end portion of the scroll unit 120 through the refrigerant introduction passage L1. The gaseous refrigerant in the space H5 is taken into the compression chamber H3 of the scroll unit 120 and is compressed therein. After being compressed in the compression chamber H3, the gaseous refrigerant is discharged into the discharge chamber H2 through the discharge passage L2 and via the check valve 230, and is then discharged to the high-pressure side of the refrigeration circuit via the discharge port P2. In this way, the scroll unit 120 is configured to compress, in the compression chamber H3, the gaseous refrigerant flowing therein via the suction chamber H1 and discharge the compressed gaseous refrigerant via the discharge chamber H2.

Here, as illustrated in FIG. 1, the scroll compressor 100 further includes a back pressure control valve 400 for controlling a back pressure Pm in the back pressure chamber H4. The back pressure control valve 400, which is a mechanical (autonomous) pressure regulating valve, operates in accordance with a differential pressure between a discharge pressure Pd in the discharge chamber H2 and the back pressure Pm in the back pressure chamber H4 and thereby automatically adjusts the valve opening such that the back pressure Pm in the back pressure chamber H4 approaches a target back pressure Pc. At the bottom wall portion 146B of the rear housing 146, the back pressure control valve 400 is stored in a storage chamber 146C formed to extend from an outer peripheral surface of the bottom wall portion 146B in a direction orthogonal to the axis of the drive shaft 166 of the electric motor 160.

As illustrated in FIGS. 1 and 2, the scroll compressor 100 further includes a back pressure supply passage L3, a pressure release passage L4, and a suction pressure sensing passage L5, in addition to the refrigerant introduction passage L1 and the discharge passage L2.

The back pressure supply passage L3 is formed in the rear housing 146 and the center housing 144 such that the discharge chamber H2 and the back pressure chamber H4 communicate with each other. Here, the back pressure supply passage L3 in the rear housing 146 passes through the storage chamber 146C storing the back pressure control valve 400. The lubricant separated by the oil separator from the gaseous refrigerant in the discharge chamber H2 is introduced into the back pressure chamber H4 via the pressure control valve 400 and through the back pressure supply passage L3 to lubricate each sliding portion and to increase the back pressure Pm in the back pressure chamber H4.

The back pressure control valve 400 is disposed midway of the back pressure supply passage L3 so as to constitute a part of the back pressure supply passage L3. Accordingly, the lubricant separated from the gaseous refrigerant in the discharge chamber H2 is supplied to the back pressure chamber H4 after being appropriately decompressed by the back pressure control valve 400 while passing through the back pressure supply passage L3. That is, by adjusting the opening of the back pressure supply passage L3 connected to the inlet side (upstream side) of the back pressure chamber H4 using the back pressure control valve 400, the flow rate of the lubricant entering the back pressure chamber H4 is increased or decreased, and thus, the back pressure Pm is regulated.

The pressure release passage L4 is penetratingly formed in the drive shaft 166 in its axial direction so as to allow the back pressure chamber H4 and the suction chamber H1 to communicate with each other. An orifice OL is disposed midway of the pressure release passage L4, for example, at a suction chamber H1 side end portion of the drive shaft 166. Accordingly, the lubricant in the back pressure chamber H4 is returned to the suction chamber H1 while its flow rate is restricted by the orifice OL.

The suction pressure sensing passage L5 allows the space H5 near the outer end portion of the scroll unit 120 and the storage chamber 146C to communicate with each other, so as to sense the suction pressure Ps in the suction chamber H1 at the back pressure control valve 400. Specifically, the suction pressure sensing passage L5 is formed in the bottom plate 122A of the fixed scroll 122 and in the rear housing 146. Although here the suction pressure sensing passage L5 indirectly senses the suction pressure Ps in the suction chamber H1 via the space H5, it may directly sense the suction pressure Ps in the suction chamber H1.

Here, the back pressure chamber H4 (a mechanical chamber in which a revolving drive element such as the drive shaft 166 is provided) is formed on a back surface side of the orbiting scroll 124 (i.e., an end surface side, opposite to the fixed scroll 122, of the orbiting scroll 124). The back pressure chamber H4 generates the back pressure Pm that presses and biases the orbiting scroll 124 toward the fixed scroll 122. Thus, the orbiting scroll 124 is pressed toward the fixed scroll 122 by the back pressure Pm in the back pressure chamber H4. Assume here that the scroll unit 120 performs compression operation in a state in which the resultant force of the back pressure Pm acting on the end surface, facing the back pressure chamber H4, of the bottom plate 124A of the orbiting scroll 124 is considerably less than the compression reaction force acting on the end surface, facing the compression chamber H3, of the bottom plate 124A; that is, the scroll unit 120 performs compression operation with an insufficient back pressure. In such a case, a gap may be formed between the tip of the wrap 124B of the orbiting scroll 124 and the bottom plate 122A of the fixed scroll 122 and a gap may be formed between the bottom plate 124A of the orbiting scroll 124 and the tip of the wrap 122B of the fixed scroll 122. These gaps may reduce the volumetric efficiency of the compressor. In order to avoid insufficient back pressure, when the back pressure Pm is less than the target back pressure Pc, the back pressure control valve 400 increases the back pressure Pm closer to the target back pressure Pc.

On the other hand, if the resultant force of the back pressure Pm in the back pressure chamber H4 is excessively greater than the compression reaction force; that is, if the back pressure is excessive, the frictional force between the fixed scroll 122 and the orbiting scroll 124 excessively increases and thus reduces the machine efficiency of the compressor. In order to avoid excessive back pressure, when the back pressure Pm exceeds the target back pressure Pc, the back pressure control valve 400 reduces the back pressure Pm closer to the target back pressure Pc.

Next, the conversion mechanism 300 will be described in detail with reference to FIGS. 3 to 5 in addition to FIG. 1. FIG. 3 is an enlarged cross-sectional view of the conversion mechanism 300. FIG. 4 is a perspective view of an eccentric bush (eccentric bushing) 270. FIG. 5 is a sectional view of the eccentric bush 270.

The conversion mechanism 300 includes an eccentric shaft (crankpin) 260, the eccentric bush 270, and a bearing 280. The eccentric shaft 260 is provided on the other end surface of the drive shaft 166 and is eccentric (offset) with respect to the drive shaft 166. The eccentric bush 270 is in a cylindrical shape and has a through hole 271 into which the eccentric shaft 260 is fitted at a position eccentric from its central axis BS. Thus, the eccentric bush 270 is eccentrically attached to the eccentric shaft 260 via the through hole 271.

The bearing 280 is press-fitted into a cylindrical boss portion 250 formed to protrude on a back pressure chamber H4 side end surface of the bottom plate 124A of the orbiting scroll 124 and supports an outer peripheral surface 272 of the eccentric bush 270. In the present embodiment, a sliding bearing is used as the bearing 280. Thus, the eccentric bush 270 is rotatably supported by an inner peripheral surface of the boss portion 250 via the bearing 280. In this way, the orbiting scroll 124 is capable of revolving around the axis of the fixed scroll 122 via the conversion mechanism 300 in a state in which rotation of the orbiting scroll 124 is restricted.

A lubricant supply passage 350 for supplying lubricant to the bearing 280 is penetratingly formed in the eccentric bush 270. The lubricant supply passage 350 includes an axial flow passage 351 extending in an axial direction of the eccentric bush 270 and a radial flow passage 352 extending in a radial direction of the eccentric bush 270.

The axial flow passage 351 extends substantially in parallel to the central axis BS of the eccentric bush 270 and to a central axis RS of the drive shaft 166, and penetrates the eccentric bush 270. The radial flow page 352 branches from midway of the axial flow passage 351 and extends in the radial direction of the eccentric bush 270 to the outer peripheral surface 272 of the eccentric bush 270.

On an end surface of the eccentric bush 270, which is adjacent to the other end surface of the drive shaft 166, a concave portion 273 is formed extending in the radial direction of the eccentric bush 270. An opening on one end side of the axial flow passage 351 is positioned on a bottom surface of the concave portion 273. This opening can function as an inlet 355 of the lubricant supply passage 350. That is, the axial flow passage 351 has the inlet 355 of the lubricant supply passage 350.

An opening on one end of the radial flow passage 352, which is positioned on the outer peripheral surface 272 of the eccentric bush 270, can function as an outlet 356 of the lubricant supply passage 350. That is, the radial flow passage 352 has the outlet 356 of the lubricant supply passage 350. The outlet 356 of the lubricant supply passage 350 is facing an inner peripheral surface (support surface) 281 of the bearing 280. The outlet 356 of the lubricant supply passage 350 is preferably disposed so as to face an axial center portion of the inner peripheral surface 281 of the bearing 280.

As illustrated in FIG. 5, in the present embodiment, when the eccentric bush 270 is divided, by a first virtual plane PL1 including the central axis RS of the drive shaft 166, into a first region T1 and a second region T2, the first region T1 includes the central axis BS of the eccentric bush 270, the lubricant supply passage 350, and the though hole 271 positioned therein. The first virtual plane PL1 is a virtual plane perpendicular to a second virtual plane PL2 that includes both of the central axis RS of the drive shaft 166 and the central axis BS of the eccentric bush 270.

In the present embodiment, when a distance between the first virtual plane PL1 and the central axis BS of the eccentric bush 270 is defined as N1 and a distance between the first virtual plane PL1 and a central axis WS of the axial flow passage 351 is defined as N2, the relationship of N1<N2 is satisfied. That is, the central axis WS of the axial flow passage 351 is further away than the central axis BS of the eccentric bush 270 when viewed from the first virtual plane PL1. In addition, the lubricant supply passage 350 is further away than the central axis BS of the eccentric bush 270 when viewed from the first virtual plane PL1.

In the present embodiment, when a distance between the central axis RS of the drive shaft 166 and the central axis BS of the eccentric bush 270 is defined as N3 and a distance between the central axis RS of the drive shaft 166 and the central axis WS of the axial flow passage 351 is defined as N4, the relationship of N3<N4 is satisfied. That is, the central axis WS of the axial flow passage 351 is further away than the central axis BS of the eccentric bush 270 when viewed from the central axis RS of the drive shaft 166. In addition, the lubricant supply passage 350 is further away than the central axis BS of the eccentric bush 270 when viewed from the central axis RS of the drive shaft 166.

Here, supply of a lubricant to the bearing 280 will be described with reference to FIGS. 1 and 3 to 5.

A part of the lubricant in the back pressure chamber H4 flows through the concave portion 273 of the eccentric bush 270, and then flows into the axial flow passage 351 via the inlet 355. Due to the centrifugal force generated by the rotary motion of the drive shaft 166 around the central axis RS of the drive shaft 166, most of the lubricant in the axial flow passage 351 reaches to the radial flow passage 352, and then is supplied to the inner peripheral surface 281 of the bearing 280 via the outlet 356. The present embodiment employs the aforementioned configuration of the lubricant supply passage 350 so as to effectively provide an action of the centrifugal force.

According to the present embodiment, the scroll compressor 100 as an example of a scroll fluid machine has, in the housing 140, the drive shaft (rotating main shaft) 166 that is rotatably provided, the fixed scroll 122 fixed to the housing 140, the orbiting scroll 124 that orbits with respect to the fixed scroll 122, and the conversion mechanism 300 that mutually converts the rotary motion of the drive shaft (rotating main shaft) 166 and the orbiting motion of the orbiting scroll 124. The converting mechanism 300 includes the eccentric shaft 260 that is provided on the end surface of the drive shaft (rotating main shaft) 166 and is eccentric with respect to the drive shaft (rotating main shaft) 166, the eccentric bush 270 having the through hole 271 into which the eccentric shaft 260 is inter-fitted, and the bearing 280 that is press-fitted into the boss portion 250 formed on the orbiting scroll 124 and supports the outer peripheral surface 272 of the eccentric bush 270. The lubricant supply passage 350 for supplying the lubricant to the bearing 280 is penetratingly formed in the eccentric bush 270. The outlet 356 of the lubricant supply passage 350 is disposed on the outer peripheral surface 272 of the eccentric bush 270. This enables to supply the lubricant directly to the bearing 280 from the outlet 356 of the lubricant supply passage 350, and thus, the lubricant can be satisfactorily supplied to the bearing 280.

Furthermore, according to the present embodiment, the outlet 356 of the lubricant supply passage 350 is facing the inner peripheral surface 281 of the bearing 280. Thus, the lubricant can be satisfactorily supplied to the inner peripheral surface 281 of the bearing 280.

Furthermore, according to the present embodiment, the lubricant supply passage 350 includes the axial flow passage 351 extending in the axial direction of the eccentric bush 270 and the radial flow passage 352 extending in the radial direction of the eccentric bush 270. The axial flow passage 351 has the inlet 355 of the lubricant supply passage 350 and the radial flow passage 352 has the outlet 356 of the lubricant supply passage 350. Thus, the lubricant supply passage 350 can be formed easily.

Furthermore, according to the present embodiment, the lubricant supply passage 350 is further away than the central axis BS of the eccentric bush 270 when viewed from the central axis RS of the drive shaft (rotating main shaft) 166. Thus, the lubricant can be positively supplied to the bearing 280 by means of the centrifugal force generated by the rotational movement of the drive shaft 166.

Furthermore, according to the present embodiment, when the eccentric bush 270 is divided, by the first virtual plane PL1 including the central axis RS of the drive shaft (rotating main shaft) 166, into the first region T1 and the second region T2, the first region T1 includes the central axis BS of the eccentric bush 270, the lubricant supply passage 350, and the though hole 271 positioned therein. The lubricant supply passage 350 is further away than the central axis BS of the eccentric bush 270 when viewed from the first virtual plane PL1. Thus, the lubricant can be positively supplied to the bearing 280 by means of the centrifugal force generated by the rotary motion of the drive shaft 166.

Furthermore, according to the present embodiment, the scroll compressor 100 as an example of a scroll fluid machine further includes the back pressure chamber H4 that is formed on the back surface side of the orbiting scroll 124 and generates the back pressure that presses and biases the orbiting scroll 124 toward the fixed scroll 122. The outlet 355 of the lubricant supply passage 350 communicates with the back pressure chamber H4. Thus, the lubricant in the back pressure chamber H4 can be easily supplied to the bearing 280.

Furthermore, according to the present embodiment, the inlet 355 of the lubricant supply passage 350 is disposed at the concave portion 273 formed on the end surface of the eccentric bush 270. Thus, the lubricant from the back pressure chamber H4 can be easily guided to the lubricant supply passage 350.

Furthermore, according to the present embodiment, a sliding bearing is used as the bearing 280. Thus, the eccentric bush 270 can be rotatably supported with simple structure.

Next, a second embodiment of the present invention will be described referring to FIG. 6.

FIG. 6 is an enlarged cross-sectional view of the conversion mechanism 300 according to the second embodiment.

The following will describe differences from the first embodiment described above.

The eccentric bush 270 is integrally provided with a balance weight (counterweight) 290′. The balance weight 290′ is disposed at the opposite side of the through hole 271 with the central axis RS of the drive shaft 166 therebetween. Also in such an eccentric bush 270 that is integrally provided with the balance weight 290′, the lubricant supply passage 350 similar to the above is preferably provided.

Note that in the above described first and second embodiments, the balance weight 290, 290′ may be omitted.

Although the case in which the scroll fluid machine according to the present invention is a scroll compressor has been described in the above first and second embodiments, it is apparent that the present invention is also applicable to a scroll expander. When the present invention is applied to a scroll expander, the scroll expander may be configured, for example, to be incorporated in a refrigerant circuit of a Rankine cycle system for a vehicle to generate power by expanding refrigerant provided from the refrigerant circuit (recovering power from the refrigerant). In addition, when the present invention is applied to a scroll expander, the above described drive shaft 166 functions as an output shaft. That is, when the scroll fluid machine according to the present invention is a scroll compressor, the “rotating main shaft” of the present invention functions as a drive shaft, and when the scroll fluid machine according to the present invention is a scroll expander, the “rotating main shaft” of the present invention functions as an output shaft.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the embodiments described above, and further modification or other variations may be made based on the technical concept of the present invention.

REFERENCE SYMBOL LIST

• • 100 Scroll compressor (Scroll fluid machine)
  • 122 Fixed scroll
  • 124 Orbiting scroll
  • 140 Housing
  • 166 Drive shaft (Rotating main shaft)
  • 250 Boss portion
  • 260 Eccentric shaft
  • 270 Eccentric bush
  • 271 Through hole
  • 272 Outer peripheral surface
  • 273 Concave portion
  • 280 Bearing
  • 290, 290′ Balance weight
  • 281 Inner peripheral surface
  • 300 Conversion mechanism
  • 350 Lubricant supply passage
  • 351 Axial flow passage
  • 352 Radial flow passage
  • 355 Inlet
  • 356 Outlet
  • BS, RS, WS Central axis
  • H4 Back pressure chamber
  • PL1 First virtual plane
  • PL2 Second virtual plane
  • T1 First region
  • T2 Second region

Claims

1. A scroll fluid machine comprising, in a housing:

a rotating main shaft that is rotatably provided;

a fixed scroll fixed to the housing;

an orbiting scroll that orbits with respect to the fixed scroll; and

a conversion mechanism that mutually converts a rotary motion of the rotating main shaft and an orbiting motion of the orbiting scroll,

wherein the conversion mechanism includes: an eccentric shaft that is provided on an end surface of the rotating main shaft and is eccentric with respect to the rotating main shaft; an eccentric bush that has a though hole into which the eccentric shaft is fitted; and a bearing that is press-fitted into a boss portion formed on the orbiting scroll and supports an outer peripheral surface of the eccentric bush,

wherein a lubricant supply passage for supplying a lubricant to the bearing is penetratingly formed in the eccentric bush, and

wherein an outlet of the lubricant supply passage is disposed on the outer peripheral surface of the eccentric bush.

2. The scroll fluid machine according to claim 1, wherein the outlet of the lubricant supply passage faces an inner peripheral surface of the bearing.

3. The scroll fluid machine according to claim 1,

wherein the lubricant supply passage includes an axial flow passage extending in an axial direction of the eccentric bush and a radial flow passage extending in a radial direction of the eccentric bush,

wherein the axial flow passage has an inlet of the lubricant supply passage, and

wherein the radial flow passage has the outlet of the lubricant supply passage.

4. The scroll fluid machine according to claim 1, wherein the lubricant supply passage is further away than a central axis of the eccentric bush when viewed from a central axis of the rotating main shaft.

5. The scroll fluid machine according to claim 1, wherein, when the eccentric bush is divided, by a virtual plane including a central axis of the rotating main shaft, into a first region and a second region, the first region includes a central axis of the eccentric bush, the lubricant supply passage, and the through hole positioned therein.

6. The scroll fluid machine according to claim 5, wherein the lubricant supply passage is further away than the central axis of the eccentric bush when viewed from the virtual plane.

7. The scroll fluid machine according to claim 1, further comprising a back pressure chamber that is formed on a back surface side of the orbiting scroll and generates a back pressure that presses and biases the orbiting scroll toward the fixed scroll, wherein

an inlet of the lubricant supply passage communicates with the back pressure chamber.

8. The scroll fluid machine according to claim 1, wherein an inlet of the lubricant supply passage is disposed on a concave portion formed on an end surface of the eccentric bush.

9. The scroll fluid machine according to claim 1, wherein a sliding bearing is used as the bearing.