The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 23, 2002
Filed:
Aug. 04, 2000
Showa Corporation, , JP;
Abstract
In the back pressure groove structure of a variable displacement vane pump comprising a rotor rotatably contained in a pump housing and having a plurality of vane grooves arranged radially and equidistantly in a circumferential direction, a cam ring is arranged in the pump housing in a movable and displaceable manner, fitted into the pump housing to form a pump chamber with an outer peripheral portion of the rotor and applied with an urging force to provide a maximum volume of the pump chamber. A side plate is contained in the pump housing in a non-rotatable manner, slidably contacting with one sides of the rotor and the cam ring and having back pressure grooves communicating with the vane grooves. A cover plate closes an opening of the pump housing, slidably contacting with other sides of the rotor and the cam ring and having a back pressure groove communicating with the vane grooves, the back pressure grooves of the side plate communicate with a high pressure side and are divided back pressure grooves obtained by dividing an annular back pressure groove into a pump suction side groove and a pump discharge side groove. The back pressure groove of the cover plate is an annular back pressure groove or a C-shaped back pressure groove obtained by closing the annular back pressure groove at one of a pump suction side portion and a pump discharge side portion into which the annular back pressure groove is virtually partitioned.