Wobble plate type variable displacement compressor

1. A wobble plate type variable displacement compressor having pistons inserted reciprocally into cylinder bores, a swash plate rotated together with a rotational main shaft and supported changeably in angle relative to said main shaft, a wobble plate which is connected to said pistons, in which a rotational movement of said swash plate is converted into a wobble movement of said wobble plate, and which transmits said wobble movement to said pistons to reciprocate said pistons, and a rotation preventing mechanism of said wobble plate, characterized in that

said rotation preventing mechanism of said wobble plate comprises

(a) an inner ring provided in a housing movably in an axial direction while being prevented from rotation relative to the housing, the inner ring having a plurality of guide grooves for guiding a plurality of balls provided for force transmission, the inner ring being configured to move in the axial direction on the main shaft,

(b) an outer ring having a plurality of guide grooves for guiding said balls at positions opposing respective guide grooves of said inner ring, and connected to said wobble plate on an outer circumference of said outer ring and supported wobblingly together with said wobble plate,

(c) the plurality of balls being held by said guide grooves formed in said inner ring and said outer ring and performing force transmission by being held between said guide grooves which oppose each other, and

(d) a sleeve functioning as a wobble central member of said wobble movement of said wobble plate, provided on said rotational main shaft to rotate relatively thereto and to move in an axial direction and engaged with said inner ring movably in an axial direction together with said inner ring, and said outer ring is supported wobblingly on said sleeve, and

a structure for connecting said outer ring and said wobble plate is formed by providing a plurality of concave portions arranged in a circumferential direction on one member, plastically deforming the other member partially at locations corresponding to said concave portions so as to fit into said concave portions, and fixing both members to each other in an axial direction and in a rotational direction by means of said plastic deformation,

said main shaft is rotatably supported within the housing, the housing having the cylinder bores at a rear end and an inboard support for the main shaft at a front end,

wherein said guide grooves opposing each other of said inner ring and said outer ring of said wobble plate rotation preventing mechanism are formed at a relative angle of 30 to 60 degrees relative to a center axis of said rotational main shaft, and guide grooves opposing each other for forming a single ball guide are disposed so as to be symmetric relative to a plane perpendicular to said main shaft and passing through a wobble center of said wobble plate at a condition where a relative angle between an axis of said inner ring and an axis of said outer ring is zero.

2. The wobble plate type variable displacement compressor according to claim 1 , wherein two ball guides adjacent to each other among a plurality of ball guides of said wobble plate rotation preventing mechanism are a pair of ball guides disposed in parallel to each other.

3. The wobble plate type variable displacement compressor according to claim 2 , wherein said pair of ball guides disposed in parallel to each other are disposed symmetrically relative to a plane including a center axis of said rotational main shaft.

4. The wobble plate type variable displacement compressor according to claim 2 , wherein a guide groove forming one ball guide of said pair of ball guides, which are disposed in parallel to each other, is disposed so that its axis is positioned on a plane including a center axis of said rotational main shaft.

5. The wobble plate type variable displacement compressor according to claim 1 , wherein two ball guides disposed on both sides of said rotational main shaft approximately symmetrically relative to said rotational main shaft among a plurality of ball guides of said wobble plate rotation preventing mechanism are a pair of ball guides disposed in parallel to each other.

6. The wobble plate type variable displacement compressor according to claim 5 , wherein said pair of ball guides, which are disposed in parallel to each other, are disposed so that axes of guide grooves forming said pair of ball guides are positioned on a plane including a center axis of said rotational main shaft.

7. The wobble plate type variable displacement compressor according to claim 1 , wherein an inner diameter side of the inner ring has a spherical surface and an outer diameter side of the sleeve has a spherical surface, and the inner ring and the sleeve are mutually supported by engaging the spherical surface of the inner diameter side of the inner ring with the spherical surface of the outer diameter side of the sleeve so that there is a clearance between the spherical surfaces.