Patent ID: 8313318

Claim:
A compressor comprising: a housing defining a suction pressure region and a discharge pressure region; a first scroll member supported within said housing for axial displacement relative to said second scroll member and including a first end plate, a first spiral wrap extending from a first side of said first end plate, a first chamber located on a second side of said first end plate having first and second passages in communication therewith, and a first aperture extending through said first end plate and in communication with said first chamber; a second scroll member supported within said housing and including a second end plate having a second spiral wrap extending therefrom and meshingly engaged with said first spiral wrap to form a series of compression pockets, said first aperture being in communication with one of said compression pockets to provide communication between said compression pocket and said first chamber; and a piston located within said first chamber and axially displaceable between first and second positions, said piston isolating said first passage from communication with said second passage when in the first and second positions, said piston preventing communication between said first aperture and said first passage when in the first position, and said piston providing communication between said first aperture and said first passage when in the second position.