Scroll type compressor with wrap portions of different axial heights

In a scroll type 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 an operative interior area of said housing, an orbiting scroll having a circular end plate from which a second spiral wrap extends axially, said first and second spiral wraps 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 within said operative interior area, a driving mechanism operatively connected to said orbiting scroll to effect orbital motion of said orbiting scroll so that the volume of the fluid pockets changes during the orbital motion of said orbiting scroll, the improvement comprising:

• a transition portion on the spiral wrap of one of said scrolls, said transition portion defining an inner wrap portion extending from said transition portion toward the inner end of the spiral wrap and an outer wrap portion extending from said transition portion toward the outer end of the spiral wrap, said outer wrap portion having a greater axial height than said inner wrap portion;
• and
• a stepped portion on the end plate of the other of said scrolls in registry with said transition portion during at least a portion of the relative orbital movement of said scrolls, said stepped portion defining an inner end plate portion extending from said stepped portion toward the center of the end plate and an outer end plate portion extending from said stepped portion toward the periphery of the end plate, said outer end plate portion being deeper than said inner end plate portion to accommodate said outer wrap portion therein.