Image Number 6 for United States Patent #7610902.
A fuel pump assembly has a bushing defining a pumping chamber, a plunger, a cam follower piece, and a compliance device for absorbing noise by increasing either or both of a hydraulic and/or a mechanical compliance of the fuel pump assembly. The compliance device may includes a spring washer or a press-fit spring. The pump bushing and/or plunger may include a cavity as the compliance device for increasing dead volume, the cavity being in fluid communication with the pumping chamber via an orifice. A deflectable or movable mechanism is positioned within a cavity for increasing dead volume, and a solenoid varies a diameter of the orifice. The moveable mechanism includes a poppet valve having a switching pressure related to engine speed. A vehicle includes an engine, transmission, fuel rail, and a fuel pump assembly configured with at least one compliance device for absorbing a hydraulic noise component.