Patent ID: 7641456

Claim:
A scroll compressor comprising: a first scroll member having a base and a generally spiral wrap extending from its base, and a second scroll member having a base and a generally spiral wrap extending from its base; an electric motor for driving a shaft to cause said second scroll member to orbit relative to said first scroll member; a back pressure chamber defined behind a base of one of said first and second scroll members, said back pressure chamber receiving a tapped refrigerant from a compression chambers, said back pressure chamber biasing said first and second scroll members together, and a start-up cavity formed in said back pressure chamber to increase a volume of said back pressure chamber and reduce a starting load on said electric motor, said back pressure chamber is defined by at least one seal receiving within a seal cavity, wherein said seal cavity extends for a first depth away from said base of said one of said first and second scroll members, and said start-up cavity extends from said base for a second depth, with said second depth being greater than said first depth; and said start-up cavity contains more than 50% of a volume of said back pressure chamber.