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:
Jan. 03, 1995
Filed:
Jun. 21, 1993
Brian J Christopher, Clio, MI (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A fuel pump-suited for a Demand System motor vehicle fuel injection system includes a lower pressure vapor separating pump stage, a roller vane positive displacement high pressure pump stage, and a variable speed electric motor for driving an impeller in the vapor separating stage and a rotor in the roller vane stage. The roller vane stage has a bleed orifice therein located on an inlet side plate of the roller vane stage to intercept succeeding ones of a plurality of vane pockets on the rotor between a downstream end of a discharge port of the roller vane stage and an upstream end of an inlet port of the roller vane stage when the vane pockets are isolated from both ports. The bleed orifice is in flow communication with a fuel tank of the vehicle and functions to relieve the pressure of fuel trapped in the roller pockets upstream of the inlet port and to recirculate an increasing fraction of the discharge of the roller vane stage back to the fuel tank which fraction as the speed of the electric motor decreases to a minimum.