Patent ID: 7131822

Claim:
A swash plate compressor, comprising: a housing; a rotatable main shaft extending in the housing; a swash plate mounted on the shaft and rotatable together with the shaft; and a compressor unit adapted to carry out a suction process and a compression process for a working fluid as the swash plate rotates, wherein the compressor unit comprises: a plurality of pistons arranged adjacent to one another in the rotating direction of the swash plate and adapted to reciprocate in an axial direction of the shaft as the swash plate rotates; and a plurality of cylinder bores, wherein each of the cylinder bores is configured to receive a corresponding one of the pistons and to guide the corresponding one of the pistons in reciprocation, and each said cylinder bore has a cross-section formed of any closed curve other than a circle, wherein the closed curve comprises a plurality of curve elements and a plurality of straight elements, and each of the straight elements connects each two adjacent curve elements, wherein each of the pistons comprises: a piston body having an inner end disposed within the cylinder bore; a piston head mounted on the inner end of the piston body; and a piston ring mounted on the piston body, wherein the piston head and the piston ring have a cross-sectional shape which conforms to the cross-section of the cylinder bore, such that only the piston head and the piston ring slidably contact the cylinder bore when the piston is fitted in the cylinder bore, wherein the piston head and the piston ring each comprise: a metallic ring portion surrounding the outer periphery of the piston body; and a seal ring surrounding an outer periphery of the ring portion, the seal ring being formed of a synthetic resin and being elastically deformable.