Patent ID: 7008174

Claim:
A fuel pump for a motor vehicle, the fuel pump pressurizing fuel for delivery to an engine, the fuel pump comprising: a housing; a motor situated in the housing and driving a shaft, the shaft defining a central axis; a single sided impeller connected to the shaft for rotation and for axial translation relative to shaft, the impeller having opposed axially facing surfaces including a body-side surface and a cover-side surface, the cover-side surface defining an impeller flow channel extending circumferentially around the impeller, the impeller further including a plurality of vanes positioned at least partially within the impeller flow channel, the impeller defining a flow passageway extending through the impeller; a cover attached to the housing, the cover having a cover surface defining a cover flow channel extending circumferentially around the cover and receiving fuel from an inlet formed in the cover, the cover flow channel at least partially aligned with the impeller flow channel, the cover flow channel having an inlet end receiving lower pressure fuel and an outlet end providing higher pressure fuel, the outlet end extending radially inwardly for fluid communication with the flow passageway of the impeller; a body defined inside the housing, the body defining an impeller chamber having a body surface, the impeller chamber sized to receive the impeller, the body further defining an outlet passageway positioned to fluidically connect to the flow passageway of the impeller to receive higher pressure fuel for delivery to the engine; and the impeller being subjected to a cover-side force from fuel in the cover flow channel and the impeller flow channel, and subjected to a body-side force from fuel in the outlet passageway, the outlet passageway being at least partially exposed to the body-side surface of the impeller, the area of the impeller exposed to higher pressure fuel in the outlet passageway being sized to provide a body-side force approximately equal to the cover-side force.