A high-pressure pump includes: a low-pressure chamber, into which low-pressure fuel discharged from a low-pressure pump flows; a pressurizing chamber, which pressurizes the low-low-pressure fuel; and a leak chamber, into which leaked fuel from the pressurizing chamber flows. The leaked fuel of the leak chamber is suctioned into and is pressurized in the pressurizing chamber together with the low-pressure fuel of the low-pressure chamber, so that the leaked fuel is discharged to an outside of the high-pressure pump as high-pressure fuel. Furthermore, a suction check valve, which is placed between the low-pressure chamber and the leak chamber, limits backflow of the leaked fuel of the leak chamber to the low-pressure chamber when the high-pressure pump does not supply the high-pressure fuel.

Provided is a high pressure fuel pump including: a body formed in a side surface thereof with a discharge hole; a pressurizing device for generating a suction force for sucking fuel supplied from a fuel tank and a pressurizing force for pressurizing the fuel at a high pressure; a seal carrier coupled to a lower portion of the body and coupled with the pressurizing device; a flow control valve coupled to one side of the body, for controlling a supply flow rate and a discharge pressure of the fuel; and a pressure relief valve for relieving an abnormal high pressure by transferring a part of discharged fuel to a low pressure space formed in the lower portion of the body when the abnormal high pressure exceeding a preset pressure limit is generated in a fuel supply system for supplying the fuel discharged through the discharge hole to an injector.

A valve system includes a guide member having a passage, a seal member positioned relative to the passage, and a valve stem disposed within the guide member passage to move axially relative to the guide member and the seal member. The seal member has an inner circumferential surface defining a bore, an outer circumferential surface, and an intermediate seal portion therebetween. The intermediate seal portion includes a first axial end surface and a second axial end surface. The seal member further includes a ramp on at least one of the first axial end surface and the second axial end surface. The ramp is descending from the inner circumferential surface to one of the intermediate seal portion or the outer circumferential surface.

A high-pressure fuel pump includes a piston and a sealing device. The piston includes an end portion. The sealing device is disposed on the end portion, faces a drive of the fuel pump, and is configured to radially surround the piston. The piston is displaceable along a longitudinal axis relative to the sealing device. The sealing device includes a first and a second sealing portion which extend round in a radially internal manner. The first and the second sealing portions are each located at mutually spaced-apart axial end regions of the sealing device. The first and the second sealing portions are present on an injection-molded component which is subsequently processed in a cutting manner.

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 piston pump as a high-pressure fuel pump of a common rail system includes: a pump cylinder; a pump piston moveably mounted in a recess of the pump cylinder, the pump piston being moveable up and down in the recess; and a leakage groove arranged in the pump cylinder in a region of the recess, the leakage groove being coupled with a leakage line configured to discharge a fuel leakage. Between the pump cylinder and the pump piston a different size pairing clearance is formed in first and second portions of the pump cylinder.

A plunger is provided for reciprocating inside the barrel of a fuel pump. The plunger has a proximal end and a distal end. The proximal end of the plunger includes a cavity that defines a depressed volume within the plunger. A volume filler is disposed in the cavity, where the volume filler is constrained in the cavity by a retaining element.

A fuel pump includes a plunger which reciprocates within a bore of a housing. The plunger extends from a first end proximal to a pumping chamber to a second end distal from the pumping chamber and includes a sealing ring groove between the first end and the second end. The sealing ring groove extends from an upper shoulder proximal to the first end to a lower shoulder distal from the first end and are separated by a first distance. A sealing ring is located within the sealing ring groove and engages the bore in an interference fit. A diametric clearance greater than 12 microns and less than 30 microns is provided between the plunger and the bore such that the diametric clearance extends between the sealing ring groove and the first end for a second distance which is at least four times the first distance.

A fuel pump includes a plunger which reciprocates within a bore of a housing. The plunger extends from a first end proximal to a pumping chamber to a second end distal from the pumping chamber and includes a sealing ring groove between the first end and the second end. The sealing ring groove extends from an upper shoulder proximal to the first end to a lower shoulder distal from the first end and are separated by a first distance. A sealing ring is located within the sealing ring groove and engages the bore in an interference fit. A diametric clearance greater than 12 microns and less than 30 microns is provided between the plunger and the bore such that the diametric clearance extends between the sealing ring groove and the first end for a second distance which is at least four times the first distance.

A piston pump, in particular high-pressure fuel pump for an internal combustion engine, includes a pump housing, a pump piston and a conveying chamber defined at least by the pump piston and the pump housing. A seal for sealing the conveying chamber and a separate guide element for guiding the pump piston may be arranged between the pump piston and the pump housing. The seal is designed as a metal sleeve, and may have a radially outwardly projecting web.