JP2007032386A - Scroll type fluid machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scroll type fluid machine having a simple structure, maintaining a clearance between fixed and movable spiral walls as small as possible and capable of exhibiting intended working efficiency. <P>SOLUTION: This compressor as the scroll type fluid machine has a surrounding wall (24) surrounding a movable end plate (34) of a movable scroll (32). During turning of the movable scroll (32), an actual turning radius of the movable scroll (32) is determined by bringing the outer peripheral face of the movable end plate (34) into sliding contact with the inner peripheral face of the surrounding wall (24) via a lubrication layer (34a) or a smooth hardened layer (34b). The actual turning radius is set smaller than a reference turning radius making the clearance between the fixed and movable spiral walls become zero. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a scroll type fluid machine used as a compressor.

This type of scroll type fluid machine, that is, a scroll compressor, is widely used in home or vehicle air conditioners, and more recently, for supplying compressed gas such as hydrogen, oxygen or air to fuel cell electrodes. It is being used.
In a scroll compressor for a fuel cell, unlike a scroll compressor for a home or vehicle air conditioner, lubricating oil cannot be contained in the compressed gas. For this reason, this type of scroll compressor uses a bearing in which a lubricant is sealed in an internal bearing, and a technique for preventing leakage of the lubricant is adopted for this bearing (for example, Patent Document 1). ).
JP 2002-70764 A

In the case of the scroll compressor of Patent Document 1 described above, although the lubrication of the bearings inside thereof is maintained well, the sliding surfaces of the spiral wall in the fixed and movable scrolls cannot be lubricated. .
For this reason, the movable scroll wall of the movable scroll is not slidably contacted with the fixed scroll wall of the fixed scroll by the crank mechanism, and swivels with a clearance between the walls, thereby seizing the fixed and movable spiral wall. Is to be prevented.

  Since the above-described clearance between walls greatly affects the compression efficiency of the scroll compressor, it is desirable that the clearance be as small as possible. However, such a clearance between walls varies greatly depending on variations in machining accuracy of individual parts constituting the crank mechanism and assembly accuracy. If the clearance between the walls becomes excessive, the scroll compressor cannot achieve the desired compression efficiency. Conversely, if the clearance between the walls becomes too small, not only does the scroll wall of the fixed and movable scrolls wear out, In the worst case, it causes seizure of the spiral wall.

  An object of the present invention is to provide a scroll type fluid machine that can accurately maintain the clearance between the walls described above with a simple configuration.

  To achieve the above object, a scroll type fluid machine of the present invention includes a fixed scroll having a fixed spiral wall protruding from a fixed end plate, and a movable scroll protruding from a circular movable end plate and meshing with the fixed spiral wall. A movable scroll having a spiral wall, the reference turning radius of which is determined by turning with the sliding contact of the movable spiral wall with respect to the fixed spiral wall, and rotation of the movable scroll when receiving rotational power from the drive shaft. In addition to a driven crank mechanism for turning the movable scroll according to the reference turning radius with respect to the fixed scroll, a fixed enclosure surrounding the movable end plate of the movable scroll and having an inner peripheral surface concentric with the drive shaft The wall further includes a reference turning radius, an inner diameter of the inner peripheral surface of the surrounding wall, and an outer diameter of the outer peripheral surface of the movable end plate as D, d1, and d2, respectively. d2) / 2 Relationship is satisfied (claim 1).

  According to the scroll compressor described above, since the relationship of D> (d1-d2) / 2 is satisfied, the movable scroll is smaller than the reference turning radius D (d1-d2) / 2 with respect to the fixed scroll. Rotating while restrained by the actual turning radius. Therefore, during the orbiting motion, the movable scroll wall of the movable scroll does not slide against the fixed scroll wall of the fixed scroll, and the centrifugal force acting on the movable scroll is supported by the surrounding wall. In this case, the magnitude of the above-described clearance between the walls is determined by the difference between D and (d1−d2) / 2.

Preferably, the surrounding wall has a cylindrical shape integrated with the fixed scroll (Claim 2). In this case, the outer peripheral surface of the movable end plate is in sliding contact with the inner peripheral surface of the surrounding wall. Assembled.
Specifically, the driven crank mechanism is provided between a crank pin protruding from one end of the drive shaft, an eccentric bush attached to the crank pin, and the eccentric bush and the movable end plate of the movable scroll. The eccentric bush includes a bearing for supporting the movable scroll, and the crank pin is fitted in the eccentric bush with play (claim 3).

The play between the crankpin and the eccentric bush absorbs the dimensional error of each component in the crank mechanism and the assembly error of the crank mechanism and the movable scroll, and achieves the actual turning radius of the movable scroll.
Preferably, at least one of the inner peripheral surface of the surrounding wall defining the inner diameter d1 and the outer peripheral surface of the movable end plate defining the outer diameter d is a lubrication layer made of a solid lubricant and a smooth hardened layer obtained by surface treatment. (Claim 4). Such a lubricating layer or hardened layer facilitates the turning of the movable scroll.

  The scroll type fluid machine according to claims 1 and 3 has a simple configuration in which the outer peripheral surface of the movable end plate is slidably contacted with the inner peripheral surface of the surrounding wall, and the actual turning radius of the movable scroll is smaller than the reference turning radius. Therefore, the sliding contact of the movable spiral wall with the fixed spiral wall can be surely avoided during the orbiting movement of the movable scroll. In addition, since the inter-wall clearance is determined by the difference between the inner diameter of the inner peripheral surface of the surrounding wall and the outer diameter of the outer peripheral surface of the movable end plate, the inter-wall clearance can be kept as small as possible. As a result, the desired compression efficiency is achieved while reducing wear of the fixed and movable spiral walls and reliably preventing seizure of these spiral walls.

Further, since the centrifugal force acting on the movable scroll is supported by the surrounding wall during the turning motion, the movable scroll is not displaced in the axial direction of the drive shaft and no bending moment is generated on the drive shaft.
In the scroll type fluid machine according to the second aspect, since the surrounding wall is formed integrally with the fixed scroll, the actual turning radius of the movable scroll is determined simultaneously with the assembly of the movable scroll to the fixed scroll.

  The scroll compressor according to claim 4 can achieve smooth turning of the movable scroll and reduce wear of the surrounding wall and the movable end plate.

FIG. 1 shows an electrically driven scroll compressor, that is, an electric scroll compressor.
The compressor is roughly divided into a motor section 2 and a scroll section 4, and these sections 2 and 4 are partitioned by a partition wall 6.
The motor section 4 has a motor casing 8. The motor casing 8 has a cylindrical shape with an opening on the partition wall 6 side and is connected to the partition wall 6. The motor casing 8 accommodates an armature, and this armature has a drive shaft 10 at the center thereof. The drive shaft 10 extends from the partition wall 6 to the bottom wall of the motor casing 8, and is supported rotatably on both the partition wall 6 and the bottom wall via bearings 12.

A core 14 is attached to the drive shaft 10, and the core 14 is surrounded by a stator 16. The stator 16 is fixed to the inner peripheral surface of the motor casing 8 and has a stator coil 18. The drive shaft 10, the core 14, the stator 16 and the stator coil 18 constitute an armature, and the drive shaft 10 can rotate in one direction.
One end of the drive shaft 10 extends through the partition wall 6 into the scroll section 4. The scroll section 4 has a fixed scroll 20, and this fixed scroll 4 also serves as the casing of the scroll section 4.

  More specifically, the fixed scroll 20 includes a cylindrical scroll casing having an opening on the partition wall 6 side, like the motor casing 8, and the scroll casing has a fixed end plate 22 facing the partition wall 6, and the fixed end plate 22. And a cylindrical surrounding wall 24 extending from the outer peripheral edge toward the motor casing 8. The scroll casing is connected to the partition wall 6 by the surrounding wall 24, so that the partition wall 6 is sandwiched between the opening end of the surrounding wall 24 and the opening end of the motor casing 8 as is apparent from FIG. 1.

The inside of the scroll casing is kept airtight from the motor casing 8. Therefore, a shaft seal 26 is disposed between the partition wall 6 and the drive shaft 10, and this shaft seal 26 is positioned on one end side of the drive shaft 10 by the bearing 12.
Further, the fixed scroll 20 has a fixed spiral wall 28, which is formed integrally with the fixed end plate 22 and the surrounding wall 24, and projects from the fixed end plate 22 toward the partition wall 6. ing.

On the other hand, a movable scroll 32 is accommodated in the scroll casing, and the movable scroll 32 has a movable end plate 34 that is located on the partition wall 6 side and faces the fixed end plate 22. A movable spiral wall 36 projects from the movable end plate 34 toward the fixed end plate 22, and the movable spiral wall 36 and the fixed spiral wall 28 are arranged so as to mesh with each other.
Further, chip seals 28 a and 36 a are respectively attached to the fixed spiral wall 28 and the movable spiral wall 36, and these chip seals 28 a and 36 a are bottom sheets on the inner end surface of the movable end plate 34 and the inner end surface of the fixed end plate 22. It is in a contact state via (not shown).

  Further, a discharge hole 30 is formed through the center of the fixed end plate 22, and this discharge hole 30 is connected to a compressed working gas receiving device via a discharge valve (not shown). Although not shown in FIG. 1, a suction hole is formed through the outer peripheral portion of the fixed end plate 22, and this suction hole is connected to a working gas supply source outside the compressor through the suction pipe. An opening is formed in the surrounding wall 24 of the scroll casing, and a space between the surrounding wall 24 and the movable scroll 32 is formed as a suction chamber.

The movable scroll 32 is connected via a driven crank mechanism of the drive shaft 10, and the driven crank mechanism transmits the rotational power of the drive shaft 10 to the movable scroll 32 and turns the movable scroll 32.
More specifically, the driven crank mechanism has a crank pin 38 protruding from one end of the drive shaft 10, and an eccentric bush 40 is attached to the crank pin 38. The eccentric bush 40 has a pin hole for inserting the crank pin 38, and the inner diameter of this pin hole is slightly larger than the outer diameter of the crank pin 38. Therefore, the crank pin 38 is fitted in the pin hole of the eccentric bush 40 with some play.

As is apparent from FIG. 1, the eccentric bush 40 is fitted into the central recess of the movable end plate 34 via a bearing 42, and supports the movable end plate 34 rotatably.
On the other hand, the movable end plate 34 and the partition wall 6 are connected to each other via a plurality of rotation prevention couplings 44, and one of these rotation prevention couplings 44 is shown in FIG. The rotation prevention coupling 44 includes a disk 46 disposed between the outer peripheral portion of the movable end plate 34 and the partition wall 6, and one end of a pair of link pins 48 is inserted into the disk 46 with play, These ring pins 48 protrude from both end faces of the disk 46, respectively. These link pins 48 are rotatably supported by the movable end plate 34 and the partition wall 6 via bearings 50, respectively, and these bearings 50 separate the pair of link pins 48 from the axis of the disk 46 in the diametrically opposite direction. The bearing 50 on the partition wall 6 side also functions as a thrust bearing that receives the thrust force from the movable scroll 32.

The rotation prevention coupling may be a ball coupling using a ball instead of the link pin described above or an Oldham coupling using an Oldham coupling.
When the rotation of the drive shaft 10 is transmitted to the movable scroll 32 via the driven crank mechanism described above, the movable scroll 32 turns around the axis of the drive shaft 10, and at this time, the rotation of the movable scroll 32 is caused by the rotation prevention coupling. 44. That is, the movable scroll 32 performs a turning motion in a state where its rotation is prevented.

  The distance between the axes of the drive shaft 10 and the crank pin 38 (the distance between the axes of the link pins 48 in the rotation prevention coupling 44) is equal to the reference turning radius D of the movable scroll 32, and the movable scroll 32 turns at this reference turning radius D. When moving, the movable scroll wall 36 of the movable scroll 32 is in sliding contact with the fixed scroll wall 28 of the fixed scroll 20 to form a compression chamber with the fixed spiral wall 28, and the scroll section 4 sucks the working gas. A series of processes from discharge to compression to discharge is executed.

  More specifically, during the turning motion of the movable scroll 32, the compression chamber sucks the working gas from the suction chamber before it is formed on the outer peripheral portion of the fixed spiral wall 28, and thereafter, the center of the fixed spiral wall 28, that is, The volume of the compression chamber is reduced as it moves toward the discharge hole 30, and the working gas sucked in the compression chamber is compressed. When the compression chamber reaches the discharge hole 30, the compressed working gas overcomes the shutoff pressure of the discharge valve, opens the discharge valve, and high pressure working gas is discharged from the compression chamber.

As apparent from FIG. 1, the surrounding wall 24 of the fixed scroll 20 has a cylindrical inner peripheral surface 24 a surrounding the movable end plate 34 of the movable scroll 32, and the inner peripheral surface 24 a is concentric with the axis of the drive shaft 10. It is. In FIG. 1, the inner diameter of the inner peripheral surface 24a is indicated by d1.
On the other hand, the movable end plate 34 of the movable scroll 32 has a lubricating layer 34a formed on the outer peripheral surface thereof. The lubricating layer 34 a is formed from a solid lubricant and extends over the entire outer periphery of the movable end plate 34. The outer diameter of the lubricating layer 34a is indicated by d2 in FIG. 1, and this outer diameter d2 is slightly larger than the outer diameter of the outer peripheral surface of the movable end plate 34 itself.

Here, the difference Δd (= d1−d2) between the inner diameter d1 of the inner peripheral surface 24a and the outer diameter d2 of the lubricating layer 34a secures a space allowing the orbiting of the movable scroll 32, and the difference Δd is described above. The reference turning radius D has a relationship satisfying the following formula.
D> Δd / 2
Accordingly, since the difference Δd / 2 is smaller than the reference turning radius D, the outer peripheral surface of the movable end plate 34, that is, lubrication, as shown in FIGS. The outer peripheral surface of the layer 34a turns while slidingly contacting the inner peripheral surface 24a of the surrounding wall 24, and the actual turning radius of the movable scroll 32 is limited to Δd / 2 which is smaller than the reference turning radius.

That is, during the revolving motion of the movable scroll 32, the movable vortex wall 36 does not slidably contact the fixed vortex wall 28, and the compression chamber is in a state in which a clearance is secured between the fixed and movable vortex walls 28 and 36 as apparent from FIG. The size of the clearance between the walls here is D−Δd / 2.
Such a limit of the actual turning radius is allowed by the play in the driven crank mechanism and the rotation prevention coupling 44 described above, and these play are caused by the individual components constituting the driven crank mechanism and the rotation prevention coupling 44. Absorbs dimensional and assembly errors.

Therefore, the above-described clearance between the walls is the dimensional accuracy of the inner diameter d1 of the inner peripheral surface 24a of the surrounding wall 24, the outer diameter d2 of the outer peripheral surface of the lubricating layer 34a of the movable end plate 34, and the movable scroll with respect to the surrounding wall 24. Since it can be determined only by the assembly accuracy of 32, it is easy to set the clearance between the walls as small as possible.
As a result, even if the working gas does not contain lubricating oil, the scroll compressor can reliably prevent wear of the fixed and movable spiral walls 28 and 36 and seizure of these spiral walls 28 and 36. Compression efficiency can be achieved.

  Further, during the revolving motion of the movable scroll 32, the movable scroll 32 receives a centrifugal force as indicated by an arrow in FIG. 3, and this centrifugal force causes the movable end plate 34 of the movable scroll 32 to slidably contact through the lubricating layer 34a. It is canceled out by the reaction force from the surrounding wall 24. Therefore, the movable scroll 32 is not displaced in the axial direction of the drive shaft 10 and a bending moment is not generated in the drive shaft 10, and a smooth turning motion of the movable scroll 32 is achieved.

In this regard, when the reaction force from the surrounding wall 24 cannot be received, the reaction force against the centrifugal force is generated in the bearing 12 on the movable scroll 32 side, and thus the drive shaft 10 receives a large bending moment. Such a bending moment causes a swing in the orbiting movement of the movable scroll 32 and causes a fluctuation in the clearance between the walls.
Although the lubricating layer 34 a of the movable end plate 34 is not indispensable, the lubricating layer 34 a reduces the sliding resistance of the movable scroll 32. Therefore, not only the turning motion of the movable scroll 32 becomes smoother, but also the driving force required for the turning motion, that is, the load on the motor section 2 can be reduced.

The present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, in the case of the scroll compressor of the modification shown in FIG. 4, the outer peripheral surface of the movable end plate 34 is formed of a smooth hardened layer 34b obtained by surface treatment instead of the above-described lubricating layer 34a. The outer diameter of the hardened layer 34b is set to d2.
Further, the lubricating layer 34 a or the hardened layer 34 b can be provided not on the outer peripheral surface of the movable end plate 34 but on the inner peripheral surface 24 a of the surrounding wall 24. Further, the outer peripheral surface of the movable end plate 34 and the inner periphery of the surrounding wall 24 can be provided. The lubricant layer 34a or the hardened layer 34b may be provided on both surfaces 24a, and the outer peripheral surface of the movable end plate 34 and the inner peripheral surface 24a of the surrounding wall 24 may be provided between the lubricant layers 34a or between the hardened layers 34b, or the lubricant layer. You may make it slidably contact in the combination of 34a and the hardened layer 34b.

  The scroll type fluid machine of the present invention can be used not as a compressor but as an expander.

It is the longitudinal cross-sectional view which showed the scroll compressor of one Example as a scroll type fluid machine. FIG. 1 shows the surrounding wall and the movable end plate of FIG. 1, and (a) to (d) are diagrams sequentially illustrating how the movable end plate rotates in the surrounding wall. It is the figure which showed a mode that the centrifugal force which acts on a movable scroll is canceled by the reaction force from an surrounding wall during the turning motion of a movable scroll. It is the longitudinal cross-sectional view which showed the scroll compressor of the modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Drive shaft 20 Fixed scroll 22 Fixed end plate 24 Enclosure wall 28 Fixed spiral wall 32 Movable scroll 34 Movable end plate 34a Lubrication layer (outer peripheral surface)
34b Hardened layer (outer peripheral surface)
36 Movable spiral wall 38 Crank pin (driven crank mechanism)
40 Eccentric bush (driven crank mechanism)
42 Bearing (driven crank mechanism)
44 Anti-rotation coupling

Claims (4)

A fixed scroll having a fixed spiral wall projecting from a fixed end plate;
A movable spiral wall protruding from a circular movable end plate and meshing with the fixed spiral wall, the reference turning radius of which is determined by turning with the sliding contact of the movable spiral wall with respect to the fixed spiral wall Scroll and
In a scroll type fluid machine comprising a driven crank mechanism for rotating the movable scroll according to the reference turning radius with respect to the fixed scroll while preventing rotation of the movable scroll when receiving rotational power from a drive shaft ,
A stationary wall surrounding the movable end plate of the movable scroll and having an inner peripheral surface concentric with the drive shaft;
When the reference turning radius, the inner diameter of the inner peripheral surface of the surrounding wall, and the outer diameter of the outer peripheral surface of the movable end plate are represented by D, d1, and d2, respectively, the relationship of D> (d1-d2) / 2 is established. A scroll type fluid machine characterized by being satisfied.   The scroll type fluid machine according to claim 1, wherein the surrounding wall is formed integrally with the fixed scroll and has a cylindrical shape. The driven crank mechanism is
A crank pin protruding from one end of the drive shaft;
An eccentric bush attached to the crankpin;
A bearing provided between the eccentric bush and the movable end plate of the movable scroll, and supporting the movable scroll on the eccentric bush;
The scroll type fluid machine according to claim 2, wherein the crank pin is fitted in the eccentric bush with play.   At least one of the inner peripheral surface defining the inner diameter d1 and the outer peripheral surface defining the outer diameter d2 is formed of either a lubricating layer made of a solid lubricant or a smooth hardened layer obtained by surface treatment. The scroll type fluid machine according to any one of claims 1 to 3, wherein the scroll type fluid machine is provided.

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