Swash-plate type compressor

A swash-plate type compressor, comprising:

• a housing;
• a drive shaft rotatably supported by said housing;
• at least one piston slidably fitted in a cylinder bore within said housing, said bore extending parallel to said drive shaft, said piston having at least one concave recess formed therein, the inner surface of said recess having the configuration of part of a sphere;
• a swash-plate disposed in said housing and secured to said drive shaft at a predetermined angle of slant thereto for rotation thereby, with a portion of a major surface of said swash-plate extending across at least a portion of said bore;
• at least one major surface of said swash-plate comprising an aluminum-silicon alloy having a silicon content in the range of 10% to 25% and a hardness of up to 42 on the Rockwell B scale;
• means for introducing a lubricating fluid to said major surface of said swash-plate;
• and
• at least one shoe made of hardened steel containing chromium and of a substantially semi-spherical shape having a convex substantially semispherical surface with at least a portion of said convex surface disposed within and in sliding contact with the concave recess of said piston,
• said shoe having a swash-plate engaging surface with a rounded chamfered annular generally frustoconical peripheral portion and a flat or slightly convex central portion in sliding contact with said major surface of said swash-plate,
• said central portion having a diameter in the range of 60% to 90% of the diameter of said swash-plate engaging surface,
• the angle of said frustoconical peripheral portion with respect to the plane of said central portion being no greater than 15 degrees, to positively provide lubricant over said entire swash-plate engaging surface and to maintain the swash-plate engaging surface substantially parallel to said major surface of said swash-plate;
• said central portion of said swash-plate engaging surface having a hardness of at least 50 on the Rockwell C scale;
• whereby rotation of the shaft causes the swash-plate to rotate so that the central portion of the swash-plate engaging surface of the shoe slides on said major surface of the swash-plate to cause said piston to reciprocate in said bore.