US20200049010A1

US20200049010A1 - Scroll fluid machine

Info

Publication number: US20200049010A1
Application number: US16/342,947
Authority: US
Inventors: Yuuta Tanaka; Kodai ISHII; Jiro Iizuka; Kanetaka Miyazawa
Original assignee: Sanden Automotive Components Corp
Current assignee: Sanden Automotive Components Corp
Priority date: 2016-11-01
Filing date: 2017-10-10
Publication date: 2020-02-13
Also published as: CN109906315A; JP2018071480A; WO2018083964A1

Abstract

The scroll-type compressor comprises a fixed scroll 320 and an orbiting scroll which are engaged with each other, a front housing 220 for accommodating the fixed scroll 320 and the orbiting scroll, and a rear housing 240 joined to the open end of the front housing 220. The fixed scroll 320 has the base plate 322 fitted into the front housing 220, and the flange 326 held at a joint surface between the front housing 220 and the rear housing 240. Additionally, at least one of the flange 326 of the fixed scroll 320 and the front housing 220 forms therein a recessed portion 326A or 220E which permits the fixed scroll 320 to be displaced in an axial direction toward the orbiting scroll due to a pressure difference acting on opposite surfaces of the base plate 322 of the fixed scroll 320.

Description

TECHNICAL FIELD

The present invention relates to a scroll fluid machine that changes the capacity of a compression chamber defined by a fixed scroll and an orbiting scroll for compressing or expanding fluid.

BACKGROUND ART

An open scroll-type compressor, as disclosed in JP 2002-206491 A (Patent Document 1), is known as an example of a scroll fluid machine. The scroll-type compressor is provided with a fixed scroll and an orbiting scroll which are engaged with each other. In the scroll-type compressor, by causing the orbiting scroll to revolve around the axis of the fixed scroll, the capacity of a compression chamber defined by the fixed and orbiting scrolls increases and decreases to compress and discharge gaseous refrigerant.
Additionally, in the open scroll-type compressor, since a drive shaft which causes the orbiting scroll to revolve penetrates a housing, a seal such as a mechanical seal and a lip seal is provided to seal between the drive shaft and the housing. In this case, it is not possible to allow a high pressure to act on the sealed portion, and thus, unlike a closed scroll-type compressor, it is not possible to prevent the orbiting scroll from departing from the fixed scroll during a compression operation by causing a back pressure to act on the orbiting scroll to press the orbiting scroll against the fixed scroll. Accordingly, for each scroll-type compressor, an axial-direction clearance between the fixed and orbiting scrolls is measured, and for example, the thickness of the thrust plate that receives the thrust force of the orbiting scroll is changed to adjust the clearance.

REFERENCE DOCUMENT LIST

Patent Document

Patent Document 1: JP 2002-206491 A
However, in order to guarantee the reliability and functionality of the scroll-type compressor, the axial-direction clearance between the fixed and orbiting scrolls must be precisely adjusted, and for example, a thrust plate with a thickness which varies by 5 μm or 10 μm unit must be selected. In this case, not only is the management of the thrust plate burdensome, but also the produceability of the scroll-type compressor may be reduced.

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

Thus, an object of the present invention is to provide a scroll fluid machine which facilitates axial-direction clearance adjustment between the fixed and orbiting scrolls.

Means for Solving the Problem

Thus, the scroll fluid machine comprises: a fixed scroll and an orbiting scroll engaged with each other; a first housing for accommodating the fixed and orbiting scrolls, and a second housing joined to an open end of the first housing. The fixed scroll has a base plate fitted into the first housing, and a flange held at a joint surface between the first and second housings. Additionally, at least one of the flange of the fixed scroll and the first housing has a recessed portion forms therein which permits the fixed scroll to be displaced in an axial direction toward the orbiting scroll due to a pressure difference acting on the opposite surfaces of the base plate of the fixed scroll.

Effects of the Invention

According to the present invention, it is possible to facilitate the axial-direction clearance adjustment between the fixed and orbiting scrolls.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating an example of a scroll-type compressor.

FIG. 2 is a cross-sectional view illustrating an essential section describing an attempt to permit the fixed scroll to be displaced in an axial direction toward an orbiting scroll.

FIG. 3 is a cross-sectional view illustrating an essential section describing an attempt such that the fixed scroll can be easily displaced.

FIG. 4 illustrates a graph showing the relationship between the axial-direction clearance and the volumetric efficiency.

FIG. 5 illustrates a graph showing the relationship between the axial-direction clearance and the power consumption.

MODE FOR CARRYING OUT THE INVENTION

An embodiment for carrying out the present invention will be described in detail below with reference to attached drawings.
The scroll fluid machine can be used for a compressor or an expander. Here, the scroll-type compressor is described as an example.
FIG. 1 illustrates an example of a scroll-type compressor.
The scroll-type compressor 100 is incorporated in a refrigerant circuit of an air conditioning apparatus for a vehicle, for example, and compresses gaseous refrigerant (fluid) drawn from the low-pressure side of the refrigerant circuit to discharge the compressed gaseous refrigerant. The scroll-type compressor 100 includes a housing 200, a compression mechanism 300 for compressing low-pressure gaseous refrigerant, and a driving force transmission mechanism 400 for transmitting the driving force from the outside to the compression mechanism 300. Here, as the refrigerant, HFC refrigerants R32, R410A, and the like can be used, for example.
The housing 200 includes: a front housing 220 which accommodates a compression mechanism 300, and a driving force transmission mechanism 400 and a rear housing 240 which is joined to the open end of the front housing 220 to form a discharge chamber H1 of the gaseous refrigerant that is compressed by the compression mechanism 300. The front housing 220 and the rear housing 240 can be separated each other.
The outer peripheral surface of the front housing 220 is formed in the stepped cylindrical shape, the outside diameter of which is reduced in diameter in four stages as it departs from the joint surface between the front housing 220 and the rear housing 240. Here, the degree of the cylindrical shape can be the cylindrical shape that can be recognized visually, and the outer peripheral surface may have the reinforcing rib and the attaching boss, for example (as for the shape, the same applies hereafter). Additionally, the inner peripheral surface of the front housing 220 is formed in the stepped cylindrical shape, the outside diameter of which is reduced in diameter in four stages as it departs from the joint surface between the front housing 220 and the rear housing 240. Therefore, the front housing 220 is formed in the cylindrical shape which is reduced in diameter in four stages, in which the outer peripheral surface and the inner peripheral surface are similar in shape, and has substantially the same shell thickness as a whole. Furthermore, a suction port (not illustrated) for drawing the gaseous refrigerant from the low-pressure side of the refrigerant circuit into the outer periphery of the compression mechanism 300 is formed in the peripheral wall of the front housing 220.
In the following description, for ease of description, the inner peripheral surface of the stepped cylindrical shape of the front housing 220 will be referred to as the first inner peripheral surface 220A to the fourth inner peripheral surface 220D, from the large-diameter side to the smaller-diameter side. The front housing 220 is given as an example of the first housing.
The rear housing 240 has a hemispherical shape, in which the central portion of the rear housing 240 bulges outward as it departs from the joint surface between the rear housing 240 and the front housing 220. Therefore, the rear housing 240 forms the inner space having a predetermined capacity which functions as the discharge chamber H1. Additionally, the discharge port (not illustrated) for discharging the compressed refrigerant from the discharge chamber H1 to the high-pressure side of the refrigerant circuit is formed in the peripheral wall of the rear housing 240. The rear housing 240 is given as an example of the second housing.
The front housing 220 and the rear housing 240 are detachably fastened through a plurality of bolts 500 as the fasteners, for example, in a state in which the open end of the large-diameter side of the front housing 220 and open end of the rear housing 240 are joined together. Thus, at each of the spaced-apart positions on the outer peripheral surface of the front housing 220, there is formed a boss 222 which extends from the large-diameter side toward the smaller-diameter side along the axial direction, and into which the shaft portion of the bolt 500 is screwed. On the other hand, at each of the positions which are spaced apart on the outer peripheral surface of the rear housing 240 and correspond to the boss 222 of the front housing 220, there is formed a boss 242 that extends from the open end toward the bulging direction along the axial direction, and through which the shaft portion of the bolt 500 is penetrated. Therefore, in a state in which the front housing 220 and rear housing 240 are joined, the shaft portion of the bolt 500 is inserted from the outside of the rear housing 240 to the boss 242, and the shaft portion is screwed into the boss 222 of the front housing 220, so that the housing 200, in which the front housing 220 and the rear housing 240 are integrated, is configured.
The compression mechanism 300 is arranged in a space in the cylindrical shape which is defined by the first inner peripheral surface 220A of the front housing 220. The compression mechanism 300 specifically includes a fixed scroll 320 which is arranged to close the opening in the large-diameter side of the front housing 220, and an orbiting scroll 340 which is arranged between the fixed scroll 320 and the stepped portion of the first inner peripheral surface 220A and second inner peripheral surface 220B.
The fixed scroll 320 includes: a disc-shaped base plate 322 fitted into the open end of the first inner peripheral surface 220A of the front housing 220; an involute curved wrap (spiral-shaped wing) 324 extending from one surface of the base plate 322 toward the orbiting scroll 340, and a thin-plate circular flange 326 which extends from the outer peripheral surface of the base plate 322 toward the radial outside in the opening side of the first inner peripheral surface 220A, and which is held at the joint surface between the front housing 220 and the rear housing 240. The outer edge end of the flange 326 is formed in a shape conforming to the exterior shape of the open end of the large-diameter side of the front housing 220, and the through holes through which the shaft portions of the bolts 500 can be penetrated are formed in a plurality of predetermined places of the plate surface. Therefore, the fixed scroll 320 is held at the joint surface between the front housing 220 and the rear housing 240 through the flange 326 to close the opening in the large-diameter side of the front housing 220, and the fixed scroll 320 cooperates with the rear housing 240 to define the discharge chamber H1.
The orbiting scroll 340 has a disc-shaped base plate 342 arranged on the stepped portion side of the first inner peripheral surface 220A and the second inner peripheral surface 220B, and an involute curved wrap 344 extending from one surface of the base plate 342 towards the fixed scroll 320. The base plate 342 has an outer diameter smaller than that of the base plate 322 of the fixed scroll 320, and the other surface of the base plate 342 is in contact with the stepped portion of the first inner peripheral surface 220A and the second inner peripheral surface 220B through a thin-plate circular thrust plate 510 so as to transmit the thrust force to the stepped portion.
The fixed scroll 320 and the orbiting scroll 340 are engaged with each other such that the side walls of the wraps 324 and 344 are in partial contact with each other in a state in which the angles in the circumferential direction of the wraps 324 and 344 are shifted from each other. Here, the seal tip (not illustrated) for securing sealing with the base plate 342 of the orbiting scroll 340 is embedded in the tip portion of the wrap 324 of the fixed scroll 320. On the other hand, the seal tip (not illustrated) for securing sealing with the base plate 322 of the fixed scroll 320 is embedded in the tip portion of the wrap 344 of the orbiting scroll 340. Therefore, in the compression mechanism 300, a crescent-shaped enclosed space, that is, a compression chamber H2 for compressing the gaseous refrigerant, is defined between the fixed scroll 320 and the orbiting scroll 340.
At the central portion of the base plate 322 of the fixed scroll 320, there is formed a discharging hole 322A for discharging the gaseous refrigerant compressed by the compression chamber H2 to the discharge chamber H1. On the other surface of the base plate 322, a one-way valve 328 constituted by the reed valve, for example, is attached, which restricts the flow of the gaseous refrigerant from the discharge chamber H1 to the compression chamber H2 while permitting the flow of the gaseous refrigerant from the compression chamber H2 to the discharge chamber H1.
On the outer peripheral surface of the base plate 322 of the fixed scroll 320, a recessed groove 322B is formed over the entire length, and an O-ring 322C for securing sealing with the front housing 220 is fitted in the recessed groove 322B. Additionally, on the open-end surface of the rear housing 240, a recessed groove 240A is formed over the entire length, and the O-ring 240B for securing sealing with the front housing 220 is fitted in the recessed groove 240A.
The driving force transmission mechanism 400 includes a drive shaft 410, a crank 420, an eccentric bush 430, a balance weight 440, an electromagnetic clutch 450, and a pulley 460.
The drive shaft 410 is in the stepped shape having a smaller diameter portion 410A and a larger diameter portion 410B, and is rotatably accommodated in the front housing 220 such that the tip portion of the smaller diameter portion 410A protrudes from the smaller-diameter side end portion of the front housing 220. Specifically, the smaller diameter portion 410A and the larger diameter portion 410B of the drive shaft 410 are respectively rotatably supported with respect to the opening side end portion of the fourth inner peripheral surface 220D and the third inner peripheral surface 220C through a ball bearing 520 and a roller bearing 530. The smaller diameter portion 410A of the drive shaft 410, which is the portion positioned between the ball bearing 520 and the larger diameter portion 410B, is secured sealing with the fourth inner peripheral surface 220D of the front housing 220 by means of a sealing member 540 such as a mechanical seal and a lip seal.
On the end surface of the larger diameter portion 410B of the drive shaft 410, and in a position eccentric from the shaft center, there is formed the crank 420 of the cylindrical shape which protrudes from here towards the compression mechanism 300. To the outer peripheral surface of the crank 420, there is attached the eccentric bush 430 which has the cylindrical exterior shape and forms the fitting hole in an eccentric state into which the crank 420 is fitted relatively rotatably. The outer peripheral surface of the eccentric bush 430 is rotatably supported through the roller bearing 550 which is attached to the inner peripheral surface of an annular boss 342A which extends from the other surface of the base plate 342 of the orbiting scroll 340 to the smaller-diameter side of the front housing 220.
Additionally, on the end surface of the larger diameter portion 410B of the drive shaft 410, and in the position eccentric to the shaft center which is on the side opposite to the formed position of the crank 420, there is formed a circular hole 410C which extends toward inside the larger diameter portion 410B. A pin 430A of the cylindrical shape, which extends from the position eccentric to the shaft center toward the larger diameter portion 410B, is formed on the end surface of the eccentric bush 430 that comes face to face with the larger diameter portion 410B. The pin 430A of the eccentric bush 430 is fitted to revolve around the axis while being inscribed to the circular hole 410C of the drive shaft 410. Therefore, the orbiting scroll 340 revolves around the shaft center of the fixed scroll 320 in a state in which the rotation of the orbiting scroll 340 is restricted. Furthermore, in order to prevent vibrations caused by the revolution of the orbiting scroll 340 the balance weight 440, according to the weight of the orbiting scroll 340, is attached to the radial outside of the boss 342A of the orbiting scroll 340.
The tip portion of the drive shaft 410 is connected to the pulley 460 that is rotated by power from the outside through the electromagnetic clutch 450 which is idly attached to the outer peripheral surface of the smaller-diameter side of the front housing 220. Therefore, when the electromagnetic clutch 450 is operated, the pulley 460 and drive shaft 410 are connected, and the drive shaft 410 is rotated by the rotational force of the pulley 460. On the other hand, when the operation of the electromagnetic clutch 450 stops, the connection between the pulley 460 and the drive shaft 410 is released, and the rotation of the drive shaft 410 stops. In this way, the operation of the scroll-type compressor 100 can be controlled by appropriately controlling the electromagnetic clutch 450.
Next, actions of the scroll-type compressor 100 will be described.
When the drive shaft 410 is rotated by the power from the outside, the rotational force is transmitted to the orbiting scroll 340 through the crank 420 and the eccentric bush 430 to cause the orbiting scroll 340 to revolve around the shaft center of the fixed scroll 320. Here, since the pin 430A of the eccentric bush 430 is inscribed and fitted to the circular hole 410C of the drive shaft 410, the rotation of the orbiting scroll 340 is restricted. As a result, the capacity of the compression chamber H2 of the compression mechanism 300 increases and decreases, and the low-pressure gaseous refrigerant drawn into the inner space from the suction port of the front housing 220, while being compressed in the compression chamber H2, is introduced to the central portion. The gaseous refrigerant introduced to the central portion of the compression mechanism 300 is discharged into the discharge chamber H1 through the discharging hole 322A formed in the base plate 322 of the fixed scroll 320 and the one-way valve 328. The gaseous refrigerant discharged into the discharge chamber H1 is discharged into the high pressure side of the refrigerant circuit through the discharge port of the rear housing 240.
During the operation of the scroll-type compressor 100, the pressure in the discharge chamber H1 and the pressure in the compression chamber H2 are acting on the base plate 322 of the fixed scroll 320. The pressure in the compression chamber H2 changes according to the capacity, and thus, it can be easily understood that, by taking into consideration of the average pressure, the pressure in the discharge chamber H1 is higher than the average pressure in the compression chamber H2. In this case, the force toward the orbiting scroll 340 acts on the base plate 322 of the fixed scroll 320 due to the pressure difference between opposite surfaces of the base plate 322. Since the base plate 322 of the fixed scroll 320 has a certain thickness to ensure sufficient strength, its deformation amount is extremely small and is negligible. However, since the fixed scroll 320 is held at the joint surface between the front housing 220 and the rear housing 240 through the thin-plate shape flange 326, the flange 326 is elastically deformed by the force acting on the base plate 322, and an attempt for displacement toward the orbiting scroll 340 is made.
Here, since the flange 326 of the fixed scroll 320 is in full contact with the end surface of the large-diameter side of the front housing 220, flange 326 and front housing 220 interfere with each other, and the displacement toward the orbiting scroll 340 is prevented. Thus, as shown in FIG. 2, recessed portions 326A and 220E, which permit the fixed scroll 320 to be displaced in the axial direction toward the orbiting scroll 340 due to the pressure difference acting on the opposite surfaces of the base plate 322 of the fixed scroll 320, are formed in at least one of the flange 326 and the large-diameter side end surface of the front housing 220.
In the illustrated example, a thin-plate circular shim 560 for adjusting the axial-direction clearance between the fixed scroll 320 and the orbiting scroll 340 is attached between the front housing 220 and the flange 326 of the fixed scroll 320; however, this need not necessarily be attached. In this case, as with the conventional art, the axial-direction clearance between the fixed scroll 320 and the orbiting scroll 340 can be adjusted by appropriately selecting the thickness of the thrust plate 510.
When the fixed scroll 320 is attempted to be displaced in the axial direction toward the orbiting scroll 340, the recessed portion 326A formed in the flange 326 of the fixed scroll 320 is formed in the shape that avoids interference with the inner peripheral end portion of the large-diameter side of the front housing 220, specifically, is formed as the annular recessed groove facing the inner peripheral end portion of the open end of the large-diameter side of the front housing 220. The cross-sectional shape of the recessed groove can be determined, for example, when the fixed scroll 320 is displaced, by considering the position relationship with the inner peripheral end portion of the large-diameter side of the front housing 220. By doing so, the strength in the portion in which the recessed portion 326A is formed is reduced, and thus, the flange 326 of the fixed scroll 320 is elastically deformed from here, as the starting point. Additionally, the interference with the inner peripheral end portion of the large-diameter side of the front housing 220 is avoided by the recessed portion 326A, and the fixed scroll 320 can be easily displaced toward the orbiting scroll 340.
The recessed portion 220E formed in the large-diameter side end surface of the front housing 220, at the time the fixed scroll 320 is attempted to be displaced in the axial direction toward the orbiting scroll 340, is formed in the shape that avoids interference with the proximal end portion of the flange 326, specifically, formed as the annular recessed groove or the chamfer positioned in the inner peripheral end portion of the large-diameter side of the front housing 220. The shape of the recessed groove or the chamfer can be determined, for example, when the fixed scroll 320 is displaced, by considering the trajectory of the proximal end portion of the flange 326. By doing so, the interference with the flange 326 of the fixed scroll 320 is avoided by the recessed portion 220E, and the fixed scroll 320 can be easily displaced toward the orbiting scroll 340.
Therefore, the clearance can be easily adjusted by adjusting the axial-direction clearance between the fixed scroll 320 and the orbiting scroll 340 to a large extent, and by using the force acting on the base plate 322 of the fixed scroll 320 to displace the fixed scroll 320 toward the orbiting scroll 340. Here, the clearance is adjusted to a large extent; however, since the fixed scroll 320 is displaced toward the orbiting scroll 340, the orbiting scroll 340 is prevented from departing from the fixed scroll 320. Additionally, by adjusting the clearance to a large extent, the orbiting scroll 340 is not pressed against the fixed scroll 320 with the excessive force so that the power which causes the orbiting scroll 340 to revolve can also be reduced.
In order for the fixed scroll 320 to be further easily displaced toward the orbiting scroll 340, as illustrated in FIG. 3, at least a part of the tip portion side of the bolt 500 in the boss 222 of front housing 220 can be formed to be thin. By doing so, since the strength of the boss 222 is reduced, the boss 222 is deformed together with the bolt 500 as a result of the force acting on the base plate 322 of the fixed scroll 320, so that the displacement amount of the fixed scroll 320 can be increased. Therefore, the adjustment width of the axial-direction clearance between the fixed scroll 320 and the orbiting scroll 340 is increased, and for example, the adjustment interval of the thickness of the thrust plate 510 or the shim 560 can be increased.
In order to confirm the effect of the scroll-type compressor 100 according to the present embodiment, how the axial-direction clearance in the initial state relates to the volumetric efficiency and the power consumption is investigated. As a result, the relationship between the axial-direction clearance and the volumetric efficiency is as illustrated in FIG. 4. Referring to this relationship, it can be understood that, in the conventional art, the volumetric efficiency sharply decreases when the axial-direction clearance exceeds 40 μm, whereas in the present embodiment, the decrease in the volumetric efficiency is gradual up to the axial-direction clearance of 100 μm.
Additionally, the relationship between the axial-direction clearance and the power consumption is as illustrated in FIG. 5. Referring to this relationship, in can be understood that, in the conventional art, the power consumption decreases as the axial-direction clearance increases, whereas in the present embodiment, the axial-direction clearance is substantially constant in the range of 40-130 μm.
Therefore, it can be understood that, in the scroll-type compressor 100 according to the present embodiment, the substantially constant performance can be exhibited when the clearance in the initial state is 40-100 μm. Therefore, the adjustment range of the clearance in the initial state is larger than in the conventional art, and the axial-direction clearance adjustment between the fixed scroll 320 and the orbiting scroll 340 can be facilitated. Additionally, since the number of types of the thrust plate 510 or the shim 560 for adjusting the clearance can be reduced, the management can be facilitated.
The embodiment for implementing the present invention has been described; however, the present invention is not limited to this embodiment, and can be variously modified and altered based on the technical idea of the present invention, as an example is provided below.
The housing 200 of the scroll-type compressor 100 is not limited to the structure including the front housing 220 and the rear housing 240, and it can be the structure including the front housing, the center housing and the rear housing, for example. Additionally, the driving force transmission mechanism 400 is not limited to the above-described structure, but it can be a well-known structure.

REFERENCE SYMBOL LIST

100 Scroll-type compressor (scroll fluid machine)
200 Housing
220 Front housing (first housing)
220E Recessed portion
222 Boss
240 Rear housing (second housing)
320 Fixed scroll
322 Base plate
326 Flange
326A Recessed portion
340 Orbiting scroll
500 Bolt
560 Shim

Claims

1. A scroll fluid machine comprising:

a fixed scroll and an orbiting scroll engaged with each other;

a first housing for accommodating the fixed and orbiting scrolls, and

a second housing joined to an open end of the first housing;

wherein the fixed scroll has a base plate fitted into the first housing, and a flange held at a joint surface between the first and second housings, and

at least one of the flange of the fixed scroll and the first housing has a recessed portion formed therein which permits the fixed scroll to be displaced in an axial direction toward the orbiting scroll due to a pressure difference acting on opposite surfaces of the base plate of the fixed scroll.

2. The scroll fluid machine according to claim 1, wherein the recessed portion formed in the flange of the fixed scroll includes an annular recessed groove facing an inner peripheral end portion of the first housing.

3. The scroll fluid machine according to claim 1, wherein the recessed portion formed in the first housing includes an annular recessed groove or a chamfer positioned in the inner peripheral end portion of the first housing.

4. The scroll fluid machine according to claim 1, wherein a boss, into which a shaft portion of a bolt for fastening the first and second housings is screwed from the second housing side, is formed on an outer peripheral surface of the first housing, and

at least a part of the tip portion side of the bolt in the boss is formed to be thin.

5. The scroll fluid machine according to claim 1, wherein a shim for adjusting an axial-direction clearance between the fixed and orbiting scrolls is sandwiched between the first housing and the flange of the fixed scroll.

6. The scroll fluid machine according to claim 2, wherein the recessed portion formed in the first housing includes an annular recessed groove or a chamfer positioned in the inner peripheral end portion of the first housing.

7. The scroll fluid machine according to claim 2, wherein a boss, into which a shaft portion of a bolt for fastening the first and second housings is screwed from the second housing side, is formed on an outer peripheral surface of the first housing, and

8. The scroll fluid machine according to claim 3, wherein a boss, into which a shaft portion of a bolt for fastening the first and second housings is screwed from the second housing side, is formed on an outer peripheral surface of the first housing, and

9. The scroll fluid machine according to claim 2, wherein a shim for adjusting an axial-direction clearance between the fixed and orbiting scrolls is sandwiched between the first housing and the flange of the fixed scroll.

10. The scroll fluid machine according to claim 3, wherein a shim for adjusting an axial-direction clearance between the fixed and orbiting scrolls is sandwiched between the first housing and the flange of the fixed scroll.

11. The scroll fluid machine according to claim 4, wherein a shim for adjusting an axial-direction clearance between the fixed and orbiting scrolls is sandwiched between the first housing and the flange of the fixed scroll.