Scroll fluid machine having separable main body unit and motor unit

A scroll fluid machine includes a main body and a motor unit. The main body unit configured to compress a fluid. The motor unit configured to drive the main body unit. The main body unit and the motor unit are connected via the eccentric portion. The main body casing and the motor cover are fastened with a fastening member. The motor unit includes a main bearing that is fixed to an inside of the motor cover by a flange. The main bearing is configured to support the shaft and is located between the flange and an end bracket on an opposite side of the main body unit with respect to the flange.

TECHNICAL FIELD

The present invention relates to a scroll-type fluid machine and a maintenance method for the scroll-type fluid machine.

BACKGROUND ART

There are Patent Literatures 1 and 2 as the background art of the present invention. Patent Literature 1 describes “a rotating machine, in which an output side of a motor-type driving unit having a horizontal axis line is fixed to a first side of an attached plate in a support bracket in which the attached plate is provided to stand on a base plate, and an input side of a main body of a driven rotating machine is removably mounted on a second side of the attached plate, so that an output shaft of the motor-type driving unit can be connected to an input shaft of the main body of the driven rotating machine”.

Patent Literature 2 describes “a scroll-type fluid machine, comprising: a casing; a fixed scroll provided in the casing and including a spiral wrapping section provided to stand; a revolving scroll, in which a spiral wrapping section that overlaps with the wrapping section of the fixed scroll is provided stand on a surface of a panel, the revolving scroll revolved while forming a plurality of compression chambers in combination with the fixed scroll; a drive shaft that is rotatably provided in the casing and drives the revolving scroll; and a plurality of auxiliary crank mechanisms in a circumferential direction of the revolving scroll provided to revolve the revolving scroll while preventing autorotation of the revolving scroll, wherein the auxiliary crank mechanism includes a revolving-side bearing section provided on the revolving scroll side, a fixing-side bearing section provided on a fixing side, and an auxiliary crank shaft connected to the revolving-side bearing section and the fixing-side bearing section, at least one of the revolving-side bearing section and the fixing-side bearing section is housed in a boss piece, and the boss piece is connected to the revolving scroll or the fixing side via a support column in an axial direction”.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In the scroll-type fluid machine (rotating machine) of Patent Literature 1, an eccentric portion (an eccentric tube14) at a distal end of a shaft (an output shaft10) is kept attached to a main body unit (a driven rotating machine main body) side when, for example, a motor-type driving unit7is removed. For this reason, operation check cannot be performed only with a motor.

In the scroll-type fluid machine of Patent Literature 2, operation check can be performed only with a motor unit (a motor (driving source)15), for example, after the motor unit is removed; however, since a shaft (a main shaft15B) and a main shaft section9are separate units and connected by using a fastening member, the number of parts is large and labor is required at the time of disassembly. In addition, since the shaft and the main shaft section9are separate units, misalignment easily occurs. When misalignment occurs, a load applied to a main bearing is increased, which causes reduction in bearing life.

For example, there is a revolving bearing at a distal end of the eccentric portion of the shaft. The revolving bearing requires maintenance, such as supplying a lubricant, like grease. Since the eccentric portion is in a state of being attached to a compressor unit in both Patent Literature 1 and Patent Literature 2, the eccentric portion (the eccentric tube14) needs to be further removed after the motor-type driving unit7is removed in order to oil the revolving bearing. For this reason, in the configuration of Patent Literature 1, grease cannot be supplied to the revolving bearing only by removing the motor-type driving unit7from the main body unit (the driven rotating machine main body). Accordingly, maintenance, such as visual check of grease of the revolving bearing and supplying grease, cannot be performed easily.

In view of the above problems, an object of the present invention is to provide a scroll-type fluid machine and a maintenance method for the scroll-type fluid machine, in which separation, assembly, and maintenance of the compressor main body unit and the motor unit can be performed easily.

Solution to Problem

To solve the above problems, according to the present invention, there is provided a scroll-type fluid machine, including: a main body unit configured to compress a fluid; and a motor unit configured to drive the main body unit, wherein the main body unit includes a fixed scroll, a revolving scroll, a main body casing, and an autorotation preventing mechanism configured to be held by the revolving scroll and the main body casing and prevent autorotation of the revolving scroll, the motor unit includes a rotor, a stator configured to rotate the rotor, a shaft configured to rotate integrally with the rotor, a motor cover configured to house the rotor and the stator, and a main bearing configured to be fixed in the inside by the motor cover and support the shaft, an eccentric portion is included at a distal end of the shaft, the main body unit and the motor unit are connected via the eccentric portion, and the main body casing and the motor cover are fastened with a fastening member.

Further, according to another aspect of the present invention, there is provided a maintenance method for a scroll-type fluid machine, including: separating a main body unit configured to compress a fluid in a compression chamber between a fixed scroll and a revolving scroll and a motor unit configured to drive the main body unit by rotation of a shaft without disassembling the main body unit by removing an eccentric portion formed at a distal end of the shaft from the main body unit after removing a fastening member configured to fasten a main body casing attached to the fixed scroll and a motor cover provided on an outer side in a radial direction of the shaft.

Advantageous Effects of Invention

According to the present invention, a scroll-type fluid machine and a maintenance method for the scroll-type fluid machine, in which separation, assembly, and maintenance of a compressor unit and a motor unit can be performed easily.

DESCRIPTION OF EMBODIMENTS

First Embodiment

Hereinafter, detailed description will be made on a first embodiment of the present invention based on the accompanying diagram.FIG. 1shows an outline of a scroll-type fluid machine1in the present invention.FIG. 2shows a cross-sectional view of the scroll-type fluid machine1ofFIG. 1viewed from a side surface.FIGS. 3A and 3Bshow an example of a separated state of a main body unit19and a motor unit20.

The scroll-type fluid machine1in the present embodiment shown inFIG. 1may be a scroll-type compressor that compresses specific gas, such as air and nitrogen, or refrigerant, or a scroll-type vacuum pump.

As shown inFIGS. 3A and 3B, the scroll-type fluid machine1is configured with the main body unit19that compresses a fluid and the motor unit20that drives the main body unit19. As shown inFIG. 2, an internal structure of the main body unit19is configured with a fixed scroll2, a revolving scroll3arranged to face the fixed scroll2, and a main body casing14that covers the revolving scroll3from an outer side in a radial direction. In the fixed scroll2and the revolving scroll3, spiral wrapping sections2B and3B are formed on surfaces of panels2A and3A, respectively. The wrapping sections2B and3B of the fixed scroll2and the revolving scroll3overlap each other to constitute a compression chamber. The main body casing14has a tubular shape, and has both ends opened. The fixed scroll2is attached to an opening section on a one end side of the main body casing14, and the motor unit20is attached to an opening section22on the other end side. The revolving scroll3is driven by the motor unit20, and performs a revolving motion. The main body unit19compresses and discharges a fluid when the revolving motion of the revolving scroll3continuously contracts the compression chamber formed between the wrapping section2B of the fixed scroll2and the wrapping section3B of the revolving scroll3. The present embodiment exemplifies the scroll-type fluid machine1that has only one pair of the fixed scroll2and the revolving scroll3; however, the scroll-type fluid machine1may include the revolving scroll3that has the wrapping sections3B on both sides of the panel3A and the fixed scroll2on both sides of the revolving scroll3.

The revolving scroll3includes a boss section9A that houses a shaft6of the motor unit20on a back surface side (an opposite side of the surface on which the wrapping section3B is formed) of the panel3A. The boss section9A may be directly formed on the back surface of the panel3A of the revolving scroll3, or may be formed on a back surface (a surface on an opposite side of the revolving scroll3) of a boss plate9which is provided at a position away from the back surface of the panel3A as shown inFIG. 2.

The boss section9A provided on the back surface side of the revolving scroll3is provided with a revolving bearing10that supports a centrifugal force generated by a revolving motion of the revolving scroll3and a gas load that is generated by compressing air.

A plurality of autorotation preventing mechanisms for preventing autorotation of the revolving scroll3are provided between the main body casing14and the revolving scroll3. The autorotation preventing mechanism prevents autorotation of the revolving scroll3and supports a gas load in an axial direction applied from the revolving scroll3. The autorotation preventing mechanism has two eccentric shafts which are formed integrally in an axial direction, is held in a radial direction by a casing-side auxiliary crank bearing13, and is configured with an auxiliary crank shaft11that prevents autorotation of the revolving scroll3by performing a rotation motion by following the revolving scroll3, a revolving-side auxiliary crank bearing12that supports the auxiliary crank shaft11and is housed in the revolving scroll3, and a casing-side auxiliary crank bearing13housed in the main body casing14. The autorotation prevention mechanism may be configured by using, for example, a ball coupling mechanism, an Oldham coupling, or the like, in place of the auxiliary crank mechanism described so far.

The auxiliary crank shaft11is held by the main body casing14and the revolving scroll3with the revolving-side auxiliary crank bearing12and the casing-side auxiliary crank bearing13provided between them. For example, the auxiliary crank shaft11is fixed to the main body casing14with a bolt, and is fixed to the revolving scroll3by interference fitting with the revolving-side auxiliary crank bearing12provided between them. The auxiliary crank shaft11is loosely fitted to the revolving-side auxiliary crank bearing12(the casing-side auxiliary crank bearing13), and may be fixed to the revolving scroll3(the main body casing14) with a keep plate.

That is, the main body casing14and the revolving scroll3face each other in an axial direction (a longitudinal direction of the shaft6), and are held (fixed) in the axial direction with the autorotation preventing mechanism provided between them.

For this reason, when the shaft6is pulled out from the main body unit19in order to separate the main body unit19and the motor unit20, the revolving scroll3is not separated from the main body casing14. In this manner, the motor unit20can be separated without disassembling the main body unit19.

As shown inFIG. 2, the motor unit20includes a stator4and a rotor5that generate power, and the shaft6that is integrated with the rotor5by press fitting and the like and transmits power to the outside. When the stator4provides a turning force to the rotor5, the shaft6integral with the rotor5rotates. The shaft6has an eccentric portion6A. The eccentric portion6A is housed in the boss section9A provided on a back surface of the revolving scroll3in a manner removable only by being pulled in an axial direction when the main body unit19and the motor unit20are assembled (for example, the eccentric portion6A is attached to the boss section9A by loose fitting), and is removably attached to the main body unit. In this manner, the main body unit19and the motor unit20are connected with the eccentric portion6A provided between them. The eccentric portion6A of the shaft6performs an eccentric motion due to a rotation motion of the shaft6. For this reason, rotation of the shaft6causes the revolving scroll3connected to the eccentric portion6A to perform a revolving motion. The motor unit20also includes a motor cover21that contains the stator4and the rotor5. The motor cover21is configured with a motor casing17having a tubular shape that covers the stator4, the rotor5, and the shaft6from an outer side in a radial direction, a flange15provided in an opening section on the main body unit19side of the motor casing17, and an end bracket16provided in an opening section on an opposite side of the main body unit19.

The motor casing17is fixed to the stator4, and houses the rotor5and the shaft6. The shaft6is supported by a main bearing7and an anti-load bearing8. The main bearing7and the anti-load bearing8are arranged to be concentric, and the shaft6is prohibited from being inclined to an axis line of the main bearing7and the anti-load bearing8. In this manner, vibration generated by inclination of the shaft6is restrained when the scroll-type fluid machine1is operated.

In the present embodiment, the main bearing7is arranged in the motor cover21, that is, between the flange15and the end bracket16(on an opposite side of the main body unit19with respect to the flange15). The main bearing7is fixed in the motor cover21by the flange15. The flange15is fastened to the motor casing17. The flange15may be formed integrally with the motor casing17. The main body casing14and the motor cover21may be fastened in a manner that the flange15is sandwiched between the main body casing14and the motor casing17.

In the present embodiment, the main bearing7and at least part of the autorotation preventing mechanisms are arranged at positions in an axial direction (a longitudinal direction of the shaft6) that overlap each other when viewed from a radial direction. That is, an end surface on the main body unit19side of the main bearing7is arranged closer to the main body unit19side than an end surface on the motor unit20side of the autorotation preventing mechanisms (the casing-side auxiliary crank bearing13).

In particular, when the main body unit19and the motor unit20are formed as separate units and have a separable structure like in the present embodiment, size is easily increased in an axial direction. On the other hand, there is space on an inner side in a radial direction of the autorotation preventing mechanism of the main body unit19. The main bearing7is arranged in the space. In this manner, a dimension in an axial direction of the shaft6can be reduced, and a dimension in an axial direction of the entire scroll-type fluid machine1can be reduced.

For the revolving scroll3to perform a stable revolving motion at a proper position, the main bearing7and the autorotation preventing mechanism need to be connected (fixed). At this time, if positions in an axial direction of the main bearing7and the autorotation preventing mechanism are apart from each other, a large load (moment) is applied to a member that connects the main bearing7and the autorotation preventing mechanism during operation of the scroll-type fluid machine1. For this reason, a reinforcing member, such as a rib, needs to be made large, and reduction in size and weight cannot be achieved. On the other hand, when positions in an axial direction of the main bearing7and at least part of the autorotation preventing mechanisms overlap each other like in the present embodiment, reduction in size and weight of a member that connects the main bearing7and the autorotation preventing mechanism can be reduced, and reduction in size and weight of the entire scroll-type fluid machine1can be achieved.

If the main bearing7is provided on an outer side of the motor cover21in a state where an outer ring of the main bearing7is exposed, stability of the main bearing7needs to be secured when the main body unit19and the motor unit20are assembled so that the motor unit20is operated. Vibration during operation also needs to be restrained. For this reason, the main bearing7needs to be fitted to the main body unit19. On the other hand, in the present embodiment, the main bearing7is fixed to the inside of the motor cover21by the flange15. By the above configuration, the main bearing7does not need to be attached to or removed from the main body unit19when the main body unit19and the motor unit20are connected and separated. When the main body unit19and the motor unit20are separated, the main bearing7can be prevented from moving in an axial direction of the shaft6and becoming unstable. For this reason, by providing the main bearing7in the motor cover21, the main body unit19and the motor unit20can be easily connected and separated. When the shaft6is pulled out from the main body unit19in order to separate the main body unit19and the motor unit20, the main bearing7is never separated from the motor unit20. In this manner, the motor unit20can be separated from the main body unit19without disassembling the motor unit20. That is, assembly of the scroll-type fluid machine1and replacing work of the main body unit19and the motor unit20are facilitated. In addition, operation check using only the motor unit20and maintenance, such as, replacement of a part (including replacement of a motor that accompanies change of capacity of the motor) and supplying grease, become possible.

At this time, the flange15has a step shape, in which an inner side in a radial direction protrudes to the main body unit19side relative to an outer side in the radial direction. The main bearing7is fixed to an inner side in a radial direction of a surface on an opposite side of the main body unit19of the flange15(a section protruding to the main body unit19side). On the other hand, a fastening bearing surface24with respect to the main body unit19is on an outer side in a radial direction of the flange15(a section not protruding to the main body unit19side). That is, a position in an axial direction of at least part of the main bearing7is closer to a distal end of the eccentric portion6A than a position in an axial direction of the fastening bearing surface24with respect to the main body unit20formed on the flange15. In this manner, there can be achieved a configuration in which the main bearing7is fixed in the motor cover21by the flange15, and a position in an axial direction of at least part of the main bearing7overlaps with that of the autorotation preventing mechanism.

FIG. 7Ashows an enlarged view of the revolving bearing10according to the present embodiment. The eccentric portion6A of the shaft6is supported by the revolving bearing10with respect to the revolving scroll3. Power of the shaft6is transmitted to the revolving scroll3through the revolving bearing10. The revolving bearing10is configured with a revolving bearing inner ring10A having an annular shape fixed to the shaft6by press fitting and the like, a plurality of revolving bearing rollers10B provided in the boss section9A of the main body unit19, and a revolving bearing outer ring10C having an annular shape fixed to the boss section9A by press fitting and the like.

The revolving bearing roller10B is rotatably held between the revolving bearing inner ring10A and the revolving bearing outer ring10C. At the time of maintenance, a lubricant, such as grease, needs to be supplied to a plurality of the revolving bearing rollers10B separated to the main body unit19side (or the motor unit side). In the present embodiment, the revolving bearing inner ring10A is formed integrally with the eccentric portion6A of the shaft6so as to be a constituent of the motor unit20. The revolving bearing outer ring10C is formed integrally with the boss section9A so as to be a constituent of the main body unit19. In this manner, the main body unit19and the motor unit20can be easily separated at the revolving bearing inner ring10A and the revolving bearing roller10B, and reassembly can also be performed easily. By forming the shaft6and the eccentric portion6A integrally, the number of parts can be reduced, and labor of assembly and disassembly can be reduced. In addition, since the revolving bearing roller10B is exposed at the time of disassembly, maintenance, such as supplying grease to the revolving bearing roller10B, replacement of a part, and visual check, can be performed easily.

In the present embodiment, the revolving bearing roller10B is a constituent on the main body unit19side; however, as long as the structure is such that the revolving bearing roller10B is exposed when the main body unit19and the motor unit20are separated, for example, like a variation shown inFIG. 7B, the revolving bearing inner ring10A may be a constituent on the main body unit19side and the revolving bearing roller10B and the revolving bearing outer ring10C may be constituents on the motor unit20side. The boss section9A ofFIG. 7Bmay be integral with a balance weight23and a constituent on the motor unit20side.

As shown inFIGS. 3A and 3B, in the present embodiment, a fastening member that fastens the motor cover21and the main body casing14is removed and the main body unit19and the motor unit20are separated in order to perform maintenance. At this time, the eccentric portion6A of the shaft6is removed from the main body unit19(the boss section9A). At this time, the revolving bearing inner ring10A is removed integrally with the shaft6. On the other hand, the revolving bearing outer ring10C is on the main body unit19side even after the motor unit20is removed. The eccentric portion6A of the shaft6is attached to the boss section9A (the revolving bearing inner ring10A is attached to the revolving bearing roller10B) by loose fitting. For this reason, only by removing the fastening bolt18and pulling out the main body unit19in an axial direction, the main body unit19and the motor unit20can be separated. In this manner, each unit can be easily replaced with a new unit, and an output of the motor unit20can be easily changed. Since the motor unit20includes the main bearing7, operation and performance check can be performed only with the motor unit20after each unit is separated. In the main body unit19, the revolving bearing10(the revolving bearing roller10B) and the casing-side auxiliary crank bearing13are exposed on a back surface side, so that replacement of parts and maintenance, such as visual check and supplying a lubricant, like grease, can be performed easily.

After the maintenance is performed, the eccentric portion6A of the shaft6is inserted in the boss section9A of the main body unit19. By fastening the motor cover21and the main body casing14with a fastening member (for example, by inserting the fastening bolt18in a bolt insertion hole provided on the motor cover21and the main body casing14), the motor unit20is assembled with the main body unit19, and the scroll-type fluid machine1is assembled again.

By the above separation and assembly structure, the scroll-type fluid machine1can be easily assembled in an operable state after the main body unit19and the motor unit20are assembled separately.

Description will be made on a separation structure of the main body unit19and the motor unit20by usingFIGS. 3A, 3B, and 4.FIG. 4is a cross-sectional view in a side surface direction in a separated state.

At the time of maintenance of the main body unit19, maintenance of the revolving bearing10needs to be performed by supplying a lubricant, such as grease. In the prior art described in Patent Literature 1, the main body unit19and the motor unit20are separably connected in series, although the eccentric portion6A of the shaft6is kept attached to the main body unit19. To perform the maintenance of the revolving bearing10, work of disassembling the eccentric portion6A of the shaft6and also removing the eccentric portion of the shaft6is required after the main body unit19and the motor unit20are separated. For this reason, work processes other than separation of the main body unit19and the motor unit20are required, and the maintenance cannot be performed easily.

On the other hand, in the present embodiment, the eccentric portion6A of the shaft6is formed integrally with the shaft6, and is a constituent on the motor unit20side. Accordingly, the eccentric portion6A of the shaft6is removed from the main body unit19when the main body unit19and the motor unit20are separated. For this reason, visual check of grease and supply of grease to the revolving bearing10of the main body unit19can be performed without disassembling the main body unit19, and the maintenance is facilitated. The eccentric portion6A of the shaft6is formed integrally with the shaft6and is configured to be removed to the motor unit side integrally with the shaft6when the main body unit19and the motor unit20are separated. As long as the above configuration is used, for example, the eccentric portion6A and the shaft6may be configured to be fastened with a bolt, and the shaft6and the eccentric portion6A can be separated by removing the bolt.

An area of the opening section22on the motor unit20side of the main body casing14is larger than a projection area of the motor unit20(an area of a shadow created when parallel light is emitted to a section protruding to the main body unit19side from the flange15from an axial direction of the shaft6) between a distal end of the eccentric portion6A viewed from an axial direction of the shaft6and the flange15(a section protruding to the main body unit19side from the flange15). That is, a diameter ϕA of the opening section22of the main body casing14is made larger than a maximum diameter of the motor unit20between a distal end of the eccentric portion6A and the flange15(a section protruding to the main body unit19side from the flange15). In this manner, part of the motor unit20can be inserted in the inside of the main body casing14through the opening section22of the main body casing14and assembled or part of the motor unit20can be taken out from the inside of the main body casing without inclining the motor unit20when the main body unit19and the motor unit20are assembled or separated

When the balance weight23for keeping balance of the revolving scroll3is provided in a section protruding to the main body unit19side from the flange15of the shaft6, a projection area viewed from an axial direction between a distal end of the eccentric portion6A of the shaft6and the flange15of the motor unit20includes the balance weight23. A diameter of an opening section on the motor unit20side is larger than a larger one of a maximum diameter of the eccentric portion6A of the shaft6and a maximum diameter of the balance weight23.

FIG. 5shows a variation of the present embodiment. InFIG. 5, the balance weight23is arranged in the motor cover21, that is, a side away from the main body unit19farther than the flange15. In this case, the balance weight23does not need to pass through the opening section22of the main body casing14. For this reason, an area of the opening section22of the main body casing14only needs to be larger than a projection area viewed from an axial direction between a distal end of the eccentric portion6A and the flange of the motor unit20. That is, an area of the opening section22of the main body casing14may be smaller than a cross section viewed from an axial direction of the balance weight23. By arranging the balance weight23in the motor cover21, the opening section22of the main body casing14does not need to be made large even when the balance weight23is made large. Since the opening section22does not need to be made large, the main body casing14itself does not need to be formed large, and reduction in size and weight of the entire scroll-type fluid machine1can be achieved.

Second Embodiment

Description will be made on a second embodiment of the present invention by usingFIG. 6. Configurations which are the same as those in the first embodiment will be attached with the same reference signs and omitted from description. In the present embodiment, description will be made on a fastening position of the main body unit19and the motor unit20.

FIG. 6is a diagram of the main body unit19viewed from a back surface side. If the fastening position of the main body unit19and the motor unit20is on an inner side in a radial direction than an outer peripheral surface of the fixed scroll2, the fastening position is hidden behind the fixed scroll2and hard to observe. Fastening work and separation work are also interfered by the fixed scroll2. For this reason, maintenance work cannot be performed easily without removing the fixed scroll2. In the present embodiment, the fastening position of the main body unit19and the motor unit20(a position of the fastening bearing surface24) is placed on an outer side in a radial direction than the outer peripheral surface of the fixed scroll2on the basis of a center of the shaft6. In this manner, the fixed scroll2does not need to be removed when the main body unit19is separated, and the main body unit19and the motor unit20can be separated in a state where the fixed scroll is attached. In this manner, maintenance can be performed easily.

In addition, in the present embodiment, a distance ϕD from the center of the shaft6of the fastening position (the position of the fastening bearing surface24) is made larger than a distance ϕd from the center of the shaft6of the auxiliary crank bearing13. That is, the fastening position of the main body unit19and the motor unit20is provided on an outer side in a radial direction than positions of the autorotation preventing mechanisms (the auxiliary crank shaft11, the revolving-side auxiliary crank bearing12, and the casing-side auxiliary crank bearing13).

When the scroll-type fluid machine1is operated, the main body unit19, particularly a compression chamber formed between the fixed scroll2and the revolving scroll3generates much heat, so that the revolving scroll3is thermally expanded. When the revolving scroll3is thermally expanded, the auxiliary crank shaft11between the revolving scroll3and the main body casing is inclined, and a revolving radius of the revolving scroll3becomes large. At this time, there is possibility that the wrapping section2B of the fixed scroll2and the wrapping section3B of the revolving scroll3come into contact with each other, and reliability is lowered. On the other hand, if positions of the wrapping sections2B and3B are specified so that the wrapping sections2B and3B do not come into contact with each other in consideration of deformation caused by thermal expansion of the wrapping section2B of the fixed scroll2and the wrapping section3B of the revolving scroll3in advance, compression performance cannot be secured.

In view of the above, in the present embodiment, the fastening position of the main body unit19and the motor unit20is arranged on an outer side than the autorotation preventing mechanism. Thermal expansion of the revolving scroll3is transmitted to the main body casing14through the autorotation preventing mechanism; however, by fastening the main body casing14to the motor cover21with the fastening bolt18on an outer side in the radial direction than the autorotation preventing mechanism, deformation caused by thermal expansion of the main body casing14can be restrained. In this manner, a revolving radius of the revolving scroll3can be restrained from becoming large, and reliability and compression performance of the revolving scroll3can be secured.

All of the embodiments which have been described so far are merely an example of implementing the present invention. The present invention can be implemented by combining the first and second embodiments.

REFERENCE SIGNS LIST