Shoe for use in swash plate type compressor and method of forming the same

A swash plate type compressor comprising:

• a housing;
• a drive shaft rotatably supported by the housing;
• a swash plate operatively connected to the drive shaft;
• a piston accommodated in the housing, the piston being operatively connected to the swash plate;
• and
• a pair of shoes interposed between the swash plate and the piston, each of the shoes including:
• a spherical engaging surface for engaging with the piston;
• and
• a plane engaging surface being a substantially plane, the plane engaging surface engaging with the swash plate, the plane engaging surface comprising:
• a substantially planar sliding surface formed near a center of the plane engaging surface, the sliding surface sliding over a surface of the swash plate;
• a substantially radially extending peripheral surface formed near a periphery of the plane engaging surface, the peripheral surface being formed at a distance from the extended sliding surface away from the surface of the swash plate so as to form an inwardly-directed step in the plane engaging surface, the peripheral surface being connected to the spherical engaging surface at its outer periphery;
• and
• a connecting surface connecting the sliding surface to the peripheral surface.

A method of forming a shoe that is interposed between a swash plate and a piston in a swash plate type compressor, the shoe including a spherical engaging surface and a plane engaging surface that is substantially a plane, the plane engaging surface having a substantially planar sliding surface that is formed near a center of the plane engaging surface and has a predetermined outer diameter, a substantially radially extending peripheral surface that is formed near a periphery of the plane engaging surface and is formed at a distance from the extended sliding surface so as to form an inwardly-directed step in the plane engaging surface, and a connecting surface that connects the sliding surface to the peripheral surface, the method comprising the steps of:

• preparing a blank piece having a predetermined outer diameter that is smaller than that of the planar sliding surface;
• preparing a pair of dies including a first die for molding the spherical engaging surface and a second die for molding the plane engaging surface;
• setting the blank piece in the pair of the dies;
• and
• closing the pair of the dies for forging the shoe.

A shoe in a swash plate type compressor including a swash plate and a piston, the shoe being interposed between the swash plate and the piston, the shoe comprising:

• a spherical engaging surface for engaging with the piston;
• and
• a plane engaging surface being substantially a plane, the plane engaging surface engaging with the swash plate, the plane engaging surface comprising:
• a substantially planar sliding surface formed near a center of the plane engaging surface, the sliding surface sliding over a surface of the swash plate;
• a peripheral surface formed near a periphery of the plane engaging surface, the peripheral surface being formed at a distance from the extended sliding surface away from the surface of the swash plate so as to form an inwardly-directed step in the plane engaging surface, the peripheral surface being substantially parallel with the sliding surface such that the peripheral surface is oriented at an angle, with respect to the extended sliding surface of the shoe, of from about 0 degree to about 10 degrees;
• and
• a connecting surface connecting the sliding surface to the peripheral surface.

A set of dies for molding a shoe that is interposed between a swash plate and a piston in a swash plate type compressor, the shoe including a spherical engaging surface for engaging with the piston and a plane engaging surface for engaging with the swash plate, the plane engaging surface having a substantially planar sliding surface that is formed near a center of the plane engaging surface, a substantially radially extending peripheral surface that is formed near a periphery of the plane engaging surface and is formed at a distance from the extended sliding surface so as to form an inwardly-directed step in the plane engaging surface and a connecting surface that connects the sliding surface to the peripheral surface, the set of dies comprising:

• a first die having a spherical molding surface for molding the spherical engaging surface;
• and
• a second die having a plane molding surface for molding the plane engaging surface, the plane molding surface including:
• a first molding surface formed near a center of the plane molding surface for molding the sliding surface;
• a second molding surface formed near a periphery of the plane molding surface for molding the peripheral surface;
• and
• a third molding surface connecting the first molding surface to the second molding surface for molding the connecting surface.