Scroll fluid machine having projections on a wrap peripheral surface

A scroll fluid machine comprising:

• a first scroll member having a wrap portion projecting axially from a end plate, said wrap portion being wound spirally from a radially inner side toward a radially outer side of said end plate;
• and
• a second scroll member provided facing said first scroll member, said second scroll member having a wrap portion projecting axially from an end plate, said wrap portion being wound spirally from a radially inner side toward a radially outer side of said end plate so as to overlap the wrap portion of said first scroll member to define a plurality compression chambers;
• wherein at least one of said scroll members has on a peripheral surface of the wrap portion thereof a plurality of axially extending projections at spacings in a spiral direction of said wrap portion, said projections each having a transverse sectional configuration defined by a top of the projection and slopes connecting the top to said peripheral surface, each of said slopes having a concave surface at a portion thereof that is contiguous to said peripheral surface,
• wherein said first scroll member is a driven member and said second scroll member is a fixed one and said projections satisfy the following condition:
• S1<S2
• where S1 is a gap defined on the inner side of the wrap portion of the first scroll member between the top of each of the projections and the associated peripheral surface of the wrap portion when the projections approach the associated peripheral surface, and S2 is a gap defined on the outerside of the wrap portion of the first scroll member between the top of each of the projections and the associated peripheral surface of the wrap portion when the projections approach the associated peripheral surface.

A scroll fluid machine comprising:

• a first scroll member having a wrap portion projecting axially from an end plate, said wrap portion being wound spirally from a radially inner side toward a radially outer side of said end plate;
• and
• a second scroll member provided facing said first scroll member, said second scroll member having a wrap portion projecting axially from an end plate, said wrap portion being wound spirally from a radially inner side toward a radially outer side of said end plate so as to overlap the wrap portion of said first scroll member to define a plurality of compression chambers;
• wherein at least one of said scroll members has on a peripheral surface of the wrap portion thereof a plurality of axially extending projections at spacings in a spiral direction of said wrap portion, said projections each having a transverse sectional configuration defined by a top of the projection and slopes connecting the top to said peripheral surface, each of said slopes having a concave surface at a portion thereof that is contiguous to said peripheral surface, and
• wherein said projections are formed only on a limited axial part of the wrap portion away from said end plate, with the surfaces of the tops of the projections being flush with the remaining peripheral surface of the wrap portion having no projections.