Abstract: A fuel injection system has a low-pressure pump for withdrawing fuel from a tank and a high-pressure pump, which is supplied by the low-pressure pump and has camshaft-actuated pump elements. An on-off valve is connected on the inlet side to the pressure side of the low-pressure pump and on the outlet side, is connected on the one hand to a camshaft chamber of the high-pressure pump and on the other hand, is connected to the suction side of the low-pressure pump. At a first pressure threshold, a spring-loaded valve piston of the on-off valve opens a connection between the low-pressure pump and the camshaft chamber and at a relatively higher second pressure threshold, opens a connection between the pressure side and the suction side of the low-pressure pump. A throttle bore in the bottom of the valve piston serves to ventilate the low-pressure system.

Abstract: A common rail system having a regulated prefeed pump, which pumps a fuel flow from a fuel tank to a high-pressure pump. The fuel flow is split with the aid of a valve assembly into a lubricant flow and a high-pressure feed flow that is pumped into a high-pressure reservoir, and acted upon by high pressure. The prefeed pump has a substantially linear characteristic feed curve with a certain slope. To improve the regulating performance, the valve assembly for the lubricant flow includes a valve whose characteristic feed curve initially rises in a first portion (I) with the rpm of the prefeed pump with the same slope as the characteristic feed curve of the prefeed pump. Then in a second portion (II) rises substantially linearly, with a lesser slope than the characteristic feed curve of the prefeed pump, and in a third portion (III) finally drops again.

Abstract: A process and system for generating and delivering high-pressure fuel to a high-pressure storage chamber of a fuel injection system of an internal combustion engine. The system includes a low-pressure pump as a pre-feed pump by which fuel is supplied from a tank and is delivered to the intake side of a high-pressure pump and a part of the fuel delivered by the low-pressure pump is used to lubricate the high-pressure pump. In order to reduce the temperature level in the return and to increase the overall efficiency of the motor, the system is embodied so that the delivery quantity of the low-pressure pump or the delivery pressure on the delivery side of the low-pressure pump is controlled as a function of the currently required fuel quantity determined by sensors and a control device.