Patent ID: 8070461

Claim:
A closing element for a valve assembly of a compressor unloader, the compressor including a casing and a compression chamber defined within the casing, the unloader including a housing defining a fixed volume chamber, and the valve assembly having a base disposed generally between the compression and unloader chambers, a passage extending through the base and fluidly connecting the two chambers, a seat defined about a section of the passage, and a stem bore defined within the base and having a control chamber section and a central axis, the valve closing element comprising: a generally cylindrical main body moveably disposed at least partially within the stem bore so as to be displaceable generally along the bore axis, the main body having a sealing end surface, the sealing surface being disposeable against the valve seating surface so as to substantially obstruct the valve passage, and an opposing control end surface disposed within the bore control chamber section; and a sealing member disposed generally about the main body and located generally between the sealing and control surfaces, the sealing member being configured to substantially prevent fluid flow between the control chamber section and the valve passage through the stem bore, at least one of the cylindrical main body and the sealing member being configured such that the main body is generally radially moveable with respect to the bore axis to at least generally align the main body sealing surface with the valve seat.