A high-pressure fuel pipe is a pipe disposed between an injector and a high-pressure fuel pump, the high-pressure fuel pump is provided on a downstream side of a low-pressure fuel pump, an engine is a single cylinder or a two-cylinder, the high-pressure fuel pump is a plunger type that performs pressurization once or twice per rotation in synchronization with a camshaft of the engine, and a volume of the high-pressure fuel pipe is k×Q/ΔP/1000×n or less, where k is a volume modulus of fuel, Q is a maximum discharge amount of the fuel in one reciprocation of the high-pressure fuel pump, ΔP is a difference between a target fuel pressure boosted by the high-pressure fuel pump and a feed fuel pressure boosted by the low-pressure fuel pump, and n is the number of times of boosting in one rotation of the high-pressure fuel pump.

A damper spring structure of a high-pressure fuel pump includes: a housing of the high-pressure fuel pump in which a flow path for fuel is formed; a lid coupled to the housing and having an accommodation space between the housing and the lid; a damper spring installed in the accommodation space between the housing and the lid; and a damper installed in the damper spring so as to be supported by the damper spring, in which the damper spring is seated and supported on the lid and the housing in the accommodation space by contact points, and the lid is supported at a plurality of contact points.

A damper spring structure of a high-pressure fuel pump includes: a housing of the high-pressure fuel pump in which a flow path for fuel is formed; a lid coupled to the housing and having an accommodation space between the housing and the lid; a damper spring installed in the accommodation space between the housing and the lid; and a damper installed in the damper spring so as to be supported by the damper spring, in which the damper spring is seated and supported on the lid and the housing in the accommodation space by contact points, and the lid is supported at a plurality of contact points.

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 fuel pump includes a pump housing with a pumping chamber an inlet valve bore. An inlet valve selectively provides and prevents fluid communication between an inlet of the fuel pump and the pumping chamber. The inlet valve includes an inner housing received within the inlet valve bore such that an outer periphery of the inner housing is sealed to an inner periphery of the inlet valve bore. An outer housing circumferentially surrounds the inner housing. An annular chamber is defined radially between the inner housing and the outer housing and axially between the outer housing and the pump housing. A sealing ring is located within the annular chamber such that the sealing ring is compressed axially against the pump housing and the outer housing.

A pumping element comprises a first flow chamber; a second flow chamber in fluid connection with the first flow chamber, the second flow chamber including a shoulder; a check valve including a first insert and a second insert, the first insert being movable between a first position wherein the first insert forms a seal that inhibits fluid flow between the first and second flow chambers and a second position wherein the first insert permits fluid flow between the first and second flow chambers, the second insert being inserted into the second flow chamber to an extent limited by the shoulder; and a spring having a first end engaging the first insert and a second end engaging the second insert; wherein the first insert moves from the first position to the second position against a biasing force of the spring in response to pressurized fluid in the first flow chamber.

A pumping element comprises a first flow chamber; a second flow chamber in fluid connection with the first flow chamber, the second flow chamber including a shoulder; a check valve including a first insert and a second insert, the first insert being movable between a first position wherein the first insert forms a seal that inhibits fluid flow between the first and second flow chambers and a second position wherein the first insert permits fluid flow between the first and second flow chambers, the second insert being inserted into the second flow chamber to an extent limited by the shoulder; and a spring having a first end engaging the first insert and a second end engaging the second insert; wherein the first insert moves from the first position to the second position against a biasing force of the spring in response to pressurized fluid in the first flow chamber.

A fuel injection pump includes: a tappet configured to reciprocate by rotation of a cam; a cylinder that supports the tappet to reciprocate; and a plunger configured to reciprocate with the tappet. The tappet includes: a tappet body supported by the cylinder to reciprocate; a pin supported on both sides in an axial direction of the pin by the tappet body; a roller rotatably fitted to an outer peripheral side of the pin; a washer disposed between at least one end surface of the roller in the axial direction and an inner peripheral surface of the tappet body. The washer has at least one protrusion to be in contact with a stopper of the tappet body in either of two rotational directions.

A fuel pump for a direct injection system and having: a main body; a pumping chamber; a piston, which is mounted in a sliding manner on the inside of the pumping chamber; an intake duct, which ends in the pumping chamber; an intake valve, which is arranged along the intake duct; and a flow rate adjustment device provided with a control rod which is coupled to the intake valve and with an electromagnetic actuator which is configured to axially move the control rod. The flow rate adjustment device has a containing element, which houses the electromagnetic actuator, has an open end facing the intake valve, and ends with a “U”-shaped rim which has an outer ring which is arranged around the containing element at a given distance from a cylindrical wall of the containing element. An annular weld (22) is obtained between the main body and the outer ring of the “U”-shaped rim.

An actuator includes a housing, a first chamber inside the housing, a cylinder within the housing, and a second chamber within the housing. The cylinder fluidically isolates the first chamber from the second chamber. The actuator also includes a rod connected to the cylinder and extending through the second chamber and the housing. A shell is spaced apart from the housing and defines a fluid gap between the shell and the housing. The shell includes a shell inlet fluidically connected to the fluid gap and a shell outlet fluidically connected to the fluid gap.