Abstract: A method for operating a fuel injection system with pressure reduction, and a fuel injection system that includes a fuel injection valve with a servo valve are provided. The method for operating a fuel injection system includes performing a desired pressure reduction in the pressure accumulator using at least one fuel injection valve of the fuel injection system. This is achieved by opening a servo valve in the fuel injection valve, which is opened, during a pressure reduction phase, just wide enough that the actual closing element remains closed and as a result no fuel injection process takes place.

Abstract: A method for operating a fuel injection system includes detecting the pressure prevailing in a pressure accumulator using a fuel injection valve piezo actuator that includes, in addition to the active piezo region used to actuate the closing element, a passive piezo region that acts as a pressure sensor. Using this pressure sensor, the closing element force acting on the passive piezo region, and therefore the pressure prevailing in the pressure accumulator, can be determined.

Abstract: A method for operating a fuel injection system includes detecting the pressure prevailing in a pressure accumulator using a fuel injection valve piezo actuator that includes, in addition to the active piezo region used to actuate the closing element, a passive piezo region that acts as a pressure sensor. Using this pressure sensor, the closing element force acting on the passive piezo region, and therefore the pressure prevailing in the pressure accumulator, can be determined.

Abstract: A method for operating a fuel injection system with pressure reduction, and a fuel injection system that includes a fuel injection valve with a servo valve are provided. The method for operating a fuel injection system includes performing a desired pressure reduction in the pressure accumulator using at least one fuel injection valve of the fuel injection system. This is achieved by opening a servo valve in the fuel injection valve, which is opened, during a pressure reduction phase, just wide enough that the actual closing element remains closed and as a result no fuel injection process takes place.

Abstract: A method for operating a fuel injection system of an internal combustion engine uses a piezo actuator that includes, in addition to the active piezo region used to actuate the servo valve, a passive piezo region that acts as a force sensor. A force measurement is performed using this force sensor during the injection phase or in the injection pause, and a correction variable for controlling the piezo actuator is determined from the deviation between the actual force progression and a target progression, in order to regulate the injection process in this manner. A fuel injection system configured to perform such a method is also disclosed.

Abstract: A fuel pump assembly for use in an engine comprising a pumping plunger which is reciprocable, in use, under the influence of an associated drive arrangement so as to cause pressurisation of fuel within a pumping chamber. The drive arrangement includes a shoe and a roller which is cooperable with a driven cam so as to impart reciprocal movement to the shoe as the cam is driven, in use. The roller has a first surface area region having a first surface roughness and a second surface area region having a second surface roughness higher than the first surface roughness and in that static friction between the roller and the cam is larger than static friction between the roller and the shoe.

Abstract: The energy conversion during a combustion process is computed from the body sound signal of the internal combustion engine according to a theoretical model, and from it the amount of fuel delivered is derived. If the computed amount of fuel differs from the predetermined amount of fuel, a malfunction of the fuel injection system is recognized.