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 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.

Various embodiments include methods for operating a high-pressure pump comprising: driving a piston arranged in a compression chamber with a motor shaft; during movement of the piston toward the top dead center, closing the inlet valve so the fluid is then delivered by the piston through an outlet valve; applying a coil current to an electromagnet used to close the inlet valve during and/or after overshooting the top dead center; detecting a start time at which the coil current, on account of starting of an opening movement of the inlet valve, fulfills a predetermined change criterion; labelling a dead center rotation position of the motor shaft at which the piston is at the top dead center based at least in part on the ascertained start time; and adjusting operation of the pump based on the identified dead center rotation position.

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 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.

An improved high-pressure fuel pump for a gasoline direct injection system is provided. The fuel pump includes a pump body defining a low-pressure side, a high-pressure side, and a pumping chamber therebetween. The pump body also defines a central bore and a drain port extending from the central bore to the low-pressure side. A slip-fit sleeve is clamped within the central bore, the slip-fit sleeve including upper and lower guide ribs. A plunger is moveable within the sleeve for compressing fuel within the pumping chamber. The plunger and the sleeve define a first diametral clearance, and the guide ribs and the central bore define a second diametral clearance. Fuel diverting around the upper guide rib during pumping operations can recirculate through the drain port to the low-pressure side. To accommodate thermal expansion of the sleeve, the second diametral clearance is at least 75% of the first diametral clearance.

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.

Methods and systems for operating an engine that includes two fuel pumps are described. In one example, a first fuel pump may be activated or remain activated in response to an engine shutdown request so that a second fuel pump may be cooled before the first fuel pump is deactivated in response to the engine shutdown request.

A high-pressure fuel pump for a fuel injection system of an internal combustion engine is disclosed. The fuel pump includes a pump housing and a pump cover which is mounted on the pump housing and which, together with the pump housing, delimits a low-pressure chamber. A recess is formed in the pump housing, in which recess a pressure-limiting valve is located. The recess is fluidically connected to the low-pressure chamber via a channel. The channel has the same or a larger cross-section at its end facing the low-pressure chamber than at its end facing the recess.

An injector apparatus (310) for injecting fluid under pressure into an associated chamber (332) is provided. The injector apparatus (310) includes a first piston (314) defining a first working area facing an associated chamber (332), a high pressure piston (318) defining a high pressure working area facing a high pressure chamber (319), and a control piston (317) defining a control piston working area facing a control chamber (315). The first piston (314) is moveable with a body of the injector apparatus (310) to compress fluid in the high pressure chamber (319) using the high pressure piston (318), while movement of the first piston (314) is selectively controllable by controlling the fluid in the control chamber (315). The first working area is larger than the control piston working area and the control piston (317) working area is larger than the high pressure working area.