Scroll type fluid compressor with thickened spiral elements

Claim 1

In a scroll type fluid compressor including a housing having a fluid inlet port and a fluid outlet port, a fixed scroll fixedly disposed relative to said housing and having a circular end plate from which a first spiral wrap extends axially into the interior of said housing, an orbiting scroll movably disposed for non-rotative orbital movement at a substantially constant orbital radius within the interior of said housing and having a circular end plate from which a second spiral wrap extends, said first and second wraps defined in part by inner and outer involute side wall surfaces and interfitting at an angular and radial offset to make a plurality of line contacts to define at least one pair of sealed off fluid pockets, drive means operatively connected to said orbiting scroll to effect the orbital motion of said orbiting scroll while preventing rotation of said orbiting scroll, thus causing the fluid pockets to diminish in volume due to the orbital motion of said orbiting scroll, the fluid pockets eventually merging to form a single high pressure pocket generally at the center of the scrolls and adjacent the fluid output port, the improvement wherein the involute curve which forms the outer side wall surface of each of said wraps starts from an arbitrary involute angle, the involute curve which forms the inner side wall surface of each of said wraps starts at an involute angle which is 180° greater than said arbitrary involute angle, and said starting points are interconnected by an inner end surface comprised of at least two arcuate surfaces to form a thicker inner end portion of said wrap, whereby the inner end portion of each wrap is strengthened and the innermost line contact defining the central high pressure pocket moves further inwardly toward the center of said wraps to minimize reexpansion of the compressed fluid back into the adjacent pair of fluid pockets.