A pump includes a reservoir configured to receive a fluid pressurized by a boost pump. The pump also includes at least one pumping mechanism configured to receive a first flow of fluid from the reservoir and direct the first flow of fluid into a discharge passage of the pump without pumping the first flow of fluid when priming the pump. The at least one pumping mechanism is disposed in the reservoir such that the fluid in the reservoir surrounds at least a portion of the at least one pumping mechanism. The discharge passage is configured to output the first flow of fluid from the pump. The pump further includes a bypass passage configured to communicate a second flow of fluid from the reservoir to the storage tank.

A high-pressure fuel supply pump includes a plunger, a valve member, a valve seat, a pressurizing chamber, and a fuel passage. The fuel passage includes a gap passage portion formed in a gap between the valve seat and the valve member. The fuel passage also includes a bent passage portion extending in a bent direction with respect to the gap passage portion, on the downstream side of the gap passage portion. The inner surface of the valve member, on a side thereof that faces the valve seat, has a convex shape in an area of the valve member that is between the bent passage portion and the gap passage portion.

A control device includes a plurality of sound reducing parts that is operated individually, when a predetermined condition for operation is met, at each of a plurality of timings when an operating sound is generated as a result of a movement of a valve body, in one open-and-close period, and that reduces the operating sound, at each of the plurality of the timings, by changing a period of energizing an electromagnetic part to an increase side relative to a normal time, an upper limit determination part that determines whether a required period of energizing the electromagnetic part in the one open-and-close period exceeds a predetermined upper limit value, when all the plurality of the sound reducing parts are operated, and a selectively operating part that selects and operates one or more of the plurality of the sound reducing parts to an extent that the required period of energizing does not exceed the upper limit value, when the upper limit determination part has determined that the required period of energizing exceeds the upper limit value.

A high pressure fuel supply pump includes: an electromagnetic suction valve that adjusts an amount of fuel sucked into a pressuring chamber; a discharge valve that discharges the fuel from the pressuring chamber; and a plunger that makes a reciprocating motion in the pressuring chamber. The electromagnetic suction valve includes an electromagnetic coil, a suction valve, and a movable portion that is able to close the suction valve by a magnetic force when the electromagnetic coil is energized. The movable portion includes an anchor that is driven to close the suction valve by the magnetic force and stops at a fixed member, and a rod that is driven with the anchor and is able to move even after the anchor stops. The electromagnetic suction valve includes a first and second springs that bias the suction valve in closed and open direction, respectively, and a third spring in the rod.

The error diagnosis device has: an input unit that receives detected values for pressure inside the common rail; a calculation unit that, if the detected values are less than a target common rail pressure, calculates the pressure differences and the fuel pump discharge amounts; and a determination unit that determines whether or not a set time has lapsed in a state in which the pressure differences are at least a first threshold value and less than a second threshold value and the discharge amounts are at least a third threshold value and less than a fourth threshold value. The determination unit determines that an error has occurred in the high-pressure pump if the set time has lapsed and determines that an error has occurred in the flowrate adjustment valve if the set time has not lapsed.

A discharge valve of a high-pressure pump is placed in a discharge passage and is openable to enable flow of fuel from a pressurizing chamber to a discharge outlet in response to a fuel pressure difference between the pressurizing chamber side and the discharge outlet side. A relief is placed in a relief passage. The relief passage communicates between a branching portion, which is located on a side of the discharge valve where the discharge outlet is placed in the discharge passage, and a return portion, which merges with a damper chamber. The relief valve is openable to enable flow of the fuel from the branching portion to the return portion in response to a fuel pressure difference between the branching portion side and the return portion side. A discharge passage orifice is placed between the discharge valve and the branching portion in the discharge passage and constricts a flow passage cross-sectional area of the discharge passage.

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.