1. Field of the Invention
This invention relates to a full stroke position-setting mechanism for a variable capacity wobble plate compressor, and more particularly to a full stroke position-setting mechanism for a variable capacity wobble plate compressor which is capable of suppressing elastic deformation of a shaft of the compressor when the compressor is under the full stroke condition (maximum delivery quantity condition).
2. Description of the Prior Art
FIG. 8 shows in cross-section a variable capacity wobble plate compressor equipped with a conventional full stroke position-setting mechanism, which is proposed e.g. by Japanese Provisional Utility Model Publication (Kokai) No. 5-83378. FIG. 9 is an enlarged cross-section of the full stroke position-setting mechanism appearing in FIG. 8.
As shown in FIG. 8, the variable capacity wobble plate compressor equipped with the conventional full stroke position-setting mechanism is comprised of a shaft 5, a thrust flange 240 rigidly mounted thereon, a drive hub 241 rotatively mounted on the shaft 5 via a hinge ball 9, a link arm 42 connecting between one radial end of the drive hub 241 and one radial end of the thrust flange 240, and a wobble plate 10 mounted on the drive hub 241 and driven for wobbling motion by the rotation of the drive hub 241. The wobbling motion of the wobble plate 10 converts the rotation of the drive hub 241 into reciprocating motion of a piston 7 which is connected to the wobble plate 10 by a rod 11.
In the variable capacity wobble plate compressor, as pressure within the crankcase 8 decreases, the inclination angle of the wobble plate 10 increases, so that as shown in FIG. 9, an abutment portion 241c of the drive hub 241 abuts on a drive hub-receiving surface 240c formed on the periphery of a boss 240b of the thrust flange 240, whereby the compressor is placed into the full stroke condition (the maximum delivery quantity condition).
On the other hand, as the pressure within the crankcase 8 increases, the inclination angle of the wobble plate 20 decreases, and the abutment portion 241c of the drive hub 241 becomes away from the drive hub-receiving surface 240c on the periphery of the boss 240b of the thrust flange 240, whereby the compressor is placed into the minimum stroke condition (minimum delivery quantity condition).
However, since the drive hub-receiving surface 240 is in parallel with the axis of the shaft 5, if the compressor suddenly enters the maximum delivery quantity condition, a large load acts on the shaft 5 to cause elastic deformation of the shaft 5, which can shift points of the center of gravity of rotors of the compressor, such as the thrust flange 240 and the drive hub 241, causing vibrations and noise. In addition, although another full stroke position-setting mechanism has been proposed e.g. by Japanese Provisional Utility Model Publication (Kokai) No. 6-4376 in which the drive hub-receiving surface 240c is inclined relative to the axis of the shaft 5, this mechanism cannot prevent occurrence of vibrations and noise, either.
Further, intermittent occurrences of compression reaction forces cause vibrations of the drive hub 241 (five vibrations per one rotation in the case of a five-cylinder type compressor), which can cause fretting, i.e. the phenomenon of exfoliation of surfaces of associated members. This phenomenon is liable to occur between the thrust flange 240, the link arm 42, and the drive hub 241, as well as between the shaft 5, the hinge ball 9, and the drive hub 241. This brings about abnormal wear, noise, and finally, locking of the compressor.