Methods and systems are provided for cooling a high pressure fuel pump. One method includes, when a spill valve is in a pass-through state, circulating fuel from a compression chamber of the high pressure fuel pump to a step room of the high pressure fuel pump. The fuel circulation through the step room may provide for a reduction in fuel temperature in the step room, and thus, the high pressure fuel pump.

A pump unit includes a pump housing having a low-pressure inlet and a high-pressure outlet. A working medium is fed via the low-pressure inlet to a working chamber formed in the pump housing. The working medium is discharged from the working chamber via the high-pressure outlet. The pump unit also includes a pump piston channel formed in the pump housing and having a longitudinal axis. The pump unit has a first pump piston arranged movably along the longitudinal axis in the pump piston channel and coupled hydraulically to the working chamber. The pump unit also has a second pump piston arranged movably along the longitudinal axis in the pump piston channel and coupled hydraulically via a compensation volume to the first pump piston, wherein the compensation volume is coupled hydraulically to a compensation unit configured to adapt the compensation volume based on a pressure in the working chamber.

A fuel system is disclosed for use with an engine. The fuel system may have a common rail, a first type of fuel injector fluidly connected to the common rail, and a second type of fuel injector fluidly connected to the common rail. The second type of fuel injector may include a pumping portion having a bore formed therein, and a plunger reciprocatingly disposed in the bore. The second type of fuel injector may also include an accumulator portion fluidly connected to the common rail and configured to receive fuel pushed from the bore of the pumping portion by the plunger, a nozzle portion, and a valve portion fluidly connecting the pumping, nozzle, and accumulator portions.

A fuel system is disclosed for use with an engine, including a fuel injector assembly fluidly coupled with a low-pressure fuel conduit, an accumulator, and a cap within an opening in the accumulator. The fuel injector assembly may be structured to draw in low-pressure fuel, pressurize the fuel, and store the pressurized fuel in the accumulator for injection to a combustion chamber. The cap has a pressure sensor and a pressure relief valve therein, and drains fuel leaked past fluid seals between the cap and each of the pressure sensor, the pressure relief valve, and the accumulator by way of a common drain line.

When a plunger of a high pressure pump is rising, a high pressure pump controller closes a regulator valve by energizing a solenoid of an electromagnetic actuator of the high pressure pump to discharge fuel into a delivery pipe. Further, this fuel discharge energization is stopped before the plunger reaches top dead center at a pump TDC timing. Further, a fuel pressure of the delivery pipe is detected at the pump TDC timing, and based on that detected value, a time Td from the pump TDC timing until a valve opening timing of the regulator valve is estimated. Once the estimated time Td elapses from the pump TDC timing, the solenoid is reenergized to removed a movement speed of a movable portion in a direction that pushes the regulator valve in an opening direction.

In a high pressure pump in a system for fuel injection in a combustion engine, determining whether a predetermined partial load operating condition prevails in the combustion engine, at which one single of several pump elements (10) in the high pressure pump is capable of alone delivering a fuel pressure requested in an accumulator tank (6), according to a first reference value, and to achieve a reproducible increase of the fuel pressure to a second reference value. If applicable, the high pressure pump's pump elements are controlled so that one single pump element alone delivers the fuel pressure in the accumulator tank according to the first reference value, whereupon this reference value is changed to the second reference value, and the actual development of the pressure in the accumulator tank as a function of time is determined, and compared with stored values of similar developments for the determination of information regarding the pump element's performance ability.

Methods and systems are provided for cooling a high pressure fuel pump. One method includes, when a spill valve is in a pass-through state, circulating fuel from a compression chamber of the high pressure fuel pump to a step room of the high pressure fuel pump. The fuel circulation through the step room may provide for a reduction in fuel temperature in the step room, and thus, the high pressure fuel pump.

A fuel pump for conveying fuel includes a conveying unit having a cylinder, a plunger received in the cylinder, a pump spring received in the cylinder, an inner sleeve connected to the plunger, an outer sleeve in contact with the pump spring and in contact with a roller of a cam mechanism, and a locking bolt configured to detachably connect the inner and outer sleeves.

Provided is a fuel pump comprising: a pump body; a plunger reciprocatably displaceable with respect to the pump body; and a plurality of valve elements inclusive of a suction valve to allow the fuel to be sucked into the fuel pressurizing chamber and a discharge valve to allow the fuel to be discharged out of the fuel pressurizing chamber, in which the pump body comprises a tubular valve retention member to retain the plurality of valve elements, a cylinder member to slidably retain the plunger, and an outer shell member having an inner wall surface facing an outer surface of the valve retention member, the inner wall surface and the outer surface of the valve retention member collectively forming a suction gallery chamber.

Methods and systems are provided for cooling a high pressure fuel pump. One method includes, when a spill valve is in a pass-through state, circulating fuel from a compression chamber of the high pressure fuel pump to a step room of the high pressure fuel pump. The fuel circulation through the step room may provide for a reduction in fuel temperature in the step room, and thus, the high pressure fuel pump.