The present invention relates to a fuel pump for pumping fuel, comprising a piston (2) and a diaphragm seal element (3), which seals on an inner annular seal seat (4) and an outer annular seal seat (5), wherein the following equation is satisfied: (Ra.sup.2−ra.sup.2)/(ri+L).sup.2=ra/ri, where ri is the inner radius of the inner seal seat (4), ra is the inner radius of the outer seal seat (5), Ra is the outer diameter of the piston (2) and L is a difference between an outer radius (Ria) of the inner seal seat (4) and the inner radius (ri) of the inner seal seat (4). The invention further relates to a method for operating a fuel pump.

Provided is a high-pressure fuel pump that ensures oil tightness even at high fuel pressure and has a small and lightweight inexpensive discharge valve structure. Therefore, a high-pressure fuel pump according to the present invention includes: a discharge valve arranged on a discharge side of a pressurizing chamber; a discharge valve seat on which the discharge valve is seated; and a facing member configured independently as a separate member from the discharge valve seat and located on an opposite side of the discharge valve seat with the discharge valve interposed therebetween, in which a stroke direction regulating portion that regulates displacement of the discharge valve in a stroke direction is formed on a tapered surface of the facing member.

A high-pressure fuel pump includes a pump body, a plunger, a retainer, a spring that is configured to energize the plunger in a direction opposite to a direction of the pressurizing chamber, and a tappet covering the retainer from a side of an end portion of the retainer and the plunger. The retainer is provided with a projection portion protruding to a side of the tappet. The projection portion is separated from the tappet by a predetermined distance along an axial direction of the plunger.

A high-pressure pump has a metering valve and a valve stopper. The stopper has a regulation portion which an end surface of the valve is brought into contact with. An outer diameter of the regulation portion is equal to an outer diameter of the outer peripheral surface of the valve. A cylindrical sleeve is disposed around the regulation portion. When the end surface of the valve is in contact with the regulation portion, the sleeve covers a tapered surface of the valve.

A tappet assembly for use in translating force between a camshaft lobe and a fuel pump assembly via reciprocal movement within a tappet cylinder having a guide slot. The tappet assembly comprises a tappet body having inner and outer surface and defining a pair of apertures, and a follower assembly. The follower assembly has a shaft and a first bearing and a second bearing each supported on the shaft for engaging the camshaft lobe. A beam is further supported on the shaft between the first and second bearings and has a platform for engaging the fuel pump assembly. The shaft is disposed in the pair of apertures of the tappet body and the beam is arranged in the tappet body.

A pump body of a high pressure fuel pump defines a compression chamber in fluid communication with a first recess dug in a first outer face. A second recess is dug in a second outer face of the body. An inlet channel opens in a conduit extending between the first recess and the second recess.

A pump body of a high pressure fuel pump defines a compression chamber in fluid communication with a first recess dug in a first outer face. A second recess is dug in a second outer face of the body. An inlet channel opens in a conduit extending between the first recess and the second recess.

A method of adaptively predicting, during operation of a pump, a mass of fuel pumped by the pump during a pumping event to a fuel accumulator (“Q.sub.pump”) to control operation of the pump is provided, comprising: generating an adaptive model of operation of the pump, including estimating a start of pumping (“SOP”) position of a plunger of the pump, estimating Q.sub.pump, determining a converged value of the estimated SOP position, and determining a converged value of the estimated Q.sub.pump; using the adaptive model to predict Q.sub.pump by inputting to the model the converged value of the estimated SOP position, a measured pressure of fuel in the fuel accumulator and a measured temperature of fuel in the fuel accumulator; and controlling operation of the pump in response to the predicted Q.sub.pump.

A pump actuator for use between a cam and a pump is disclosed. The pump actuator comprises a pump actuator body having a structural enhancing feature. The pump actuator body comprises a pad defined between a plunger facing surface and an opposite roller facing surface. The plunger facing surface is recessed into the pump actuator body and offset from a radial end. The pump actuator body further includes a cylindrical wall defined between the radial end and the plunger facing surface. The structural enhancing feature is formed on the pad on the plunger facing surface. The structural enhancing feature increases load carrying capacity of the pump actuator body.

A high pressure fuel pump is provided with a pumping bore and a pressure relief valve only opening to enable a return flow from the outlet conduit back to the compression chamber when the pressure in the outlet conduit exceeds a predetermined threshold. The pressure relief valve is arranged in an elongated pressure relief valve chamber extending parallel and offset to the pumping bore.