An outlet valve includes an outlet valve housing with an outlet valve bore including an outlet valve seating surface. The outlet valve also includes an outlet valve member which moves within the outlet valve bore second portion between a closed position and an open position. A surface of the outlet valve bore guides the outlet valve member during movement between the closed position and the open position. The surface of the outlet valve bore and the outlet valve seating surface are provided on a continuous piece of material of the outlet valve housing. An outlet valve spring biases the outlet valve member toward the closed position and a retainer is fixed to the outlet valve housing which grounds the outlet valve spring to the outlet valve housing.

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.

A high-pressure fuel pump includes a fuel chamber, a pressurizing chamber, a cylinder, a plunger, and a control valve. The control valve includes a valve seat having a valve hole, a valve member, a movable portion having a needle, a valve opening spring, a coil, and a projecting-side stopper. The needle is configured to project from the valve hole and thus separate the valve member from the valve seat. When the control valve is in an open-valve mode, the movable portion contacts the projecting-side stopper and the valve member is separate from the valve seat. The size of the clearance formed between the valve member and the valve seat when the control valve is in the open-valve mode is set such that the clearance functions as a passage restriction for causing pressure loss in the fuel flowing from the pressurizing chamber to the fuel chamber.

A high pressure fuel pump according to the present invention includes a cylinder which is fitted in a concave portion formed in a pump housing and which defines a compression chamber of the pump and a plunger which pressurizes, by sliding against the cylinder, the fluid in the compression chamber. The high pressure fuel pump is structured such that the fluid sucked into the compression chamber by reciprocating motion of the plunger is pressurized and is then discharged from the compression chamber.

The cylinder is formed of a cylindrical member which has a ceiling portion and in which the compression chamber is partitionedly formed. A fuel suction path formed in the pump housing reaches the compression chamber through the cylinder and a fuel discharge path formed in the pump housing is connected to the compression chamber through the cylinder. The cylinder is pressed, for sealed fixation, against the pump body by a fuel pressurizing force applied to the cylinder.

Neither holder nor caulking is used for cylinder fixation.

Various methods and systems are provided for health assessments of a fuel system. In one example, a fuel system includes a high-pressure fuel pump operable to increase fuel pressure from a first pressure to a second pressure, a common fuel rail fluidly coupling the high-pressure fuel pump to a plurality of fuel injectors each of which is operable to inject fuel to individual cylinders of an engine, a pressure sensor operable to detect a pressure of fuel at the common fuel rail, and a controller operable to diagnose a condition of the high-pressure fuel pump based on output from the pressure sensor.

An object of the present invention is to supply a high-pressure fuel supply pump capable of holding a spring holding member while reducing the height of the pump body.

A high-pressure fuel supply pump is provided with a pump body for forming a pressurizing chamber at an inner wall portion, and a flange portion for fixing the pump body to a high-pressure fuel supply pump mounting portion. The high-pressure fuel supply pump is provided with a cylinder and a spring holding member. The cylinder is inserted into a hole portion of the pump body from a lower side and in which the pressurizing chamber is formed further above an uppermost end surface. The spring holding member has an outer peripheral portion press-fitted and fixed to the pump body and a holding portion holding a spring portion for biasing the pump body between the outer peripheral portion and the inner peripheral portion. A spring-side lowest end portion of the holding surface of the spring holding member is disposed above the lowermost end portion of the flange portion.

The present application relates to a pump unit for a fuel injection system. The pump unit has a low pressure fuel supply line and a high pressure fuel outlet. A pumping chamber having a plunger is operable to perform a pumping cycle comprising a pumping stroke and a filling stroke. The pump unit also includes an inlet valve having an inlet valve member movable between an open position for permitting the supply of fuel to the pumping chamber from the low pressure fuel supply line and a closed position for inhibiting the supply of fuel from the pumping chamber to the low pressure supply line. An outlet valve is provided in the high pressure fuel outlet. The pump unit also includes a means for latching the inlet valve member in its open position. The present application also relates to a method of operating a pump unit.

Embodiments relate to a valve arrangement for a fuel injection system, including a valve disc that has a valve opening. A deformable valve sheet that is movable in a movement direction is provided to open and close the valve opening, and a valve shaft of a movement-activation arrangement, provided to activate the movement of the valve sheet, is secured to the valve sheet. The embodiments also relate to a high-pressure pump which includes the valve arrangement.

High pressure fuel pump includes a cylinder which is fitted in a concave portion formed in a pump housing and which defines a compression chamber of the pump and a plunger which pressurizes, by sliding against the cylinder, the fluid in the compression chamber. It is structured such that the fluid sucked into the compression chamber by reciprocating motion of the plunger is pressurized and is then discharged from the compression chamber. The cylinder is formed of a cylindrical member which has a ceiling portion and in which the compression chamber is partitionedly formed. A fuel suction path formed in the pump housing reaches the compression chamber through the cylinder and a fuel discharge path formed in the pump housing is connected to the compression chamber through the cylinder. The cylinder is pressed against the pump body by a fuel pressurizing force applied to the cylinder.

A valve device for controlling or metering a fluid includes a housing, a flow duct formed in the housing, and a valve body arranged in the flow duct. The valve body has a sealing section which, when the valve device is closed, rests on a sealing seat on the housing. The sealing section and sealing seat together form a sealing region. When the valve device is closed, a decay chamber is defined immediately upstream of the sealing region in the flow duct. The decay chamber is bounded by a baffle wall that is tilted with respect to the normal to the sealing region at an angle of at most 15 in the flow direction to 60 counter to the flow direction.