Abstract: A method for detecting error-containing components of a piezo-injector in an internal combustion engine fuel-injection system is disclosed. The piezo-injector has a piezoelectric actuator and an injection needle driven thereby, and is configured for operation in a partial-stroke mode and a full-stroke mode. First, the internal combustion engine is brought to a defined operational point. Then, the time for the injector needle to strike its stop when said injector needle is opened, as well as the time for the injector needle to strike its needle seat again when said injector needle is closed, are measured. The measured times are compared to normal values determined at the test stand. Parameter(s) for the fuel-injection system are calculated, using different calculation models, and the results are stored. Finally, the calculated parameters of the different calculation models are compared to norm values determined at the test stand, and compared to one another.

Abstract: A method is disclosed for determining the force acting on the nozzle needle of a directly driven piezo injector, in which an electrical voltage is built on the piezo actuator which drives the nozzle needle by means of a charging process. After the charging process has ended, the voltage at the piezo actuator is measured again. A voltage gradient is determined from consecutive voltage values. Conclusions of the force acting on the nozzle needle are drawn from the voltage gradients.

Abstract: A method for detecting error-containing components of a piezo-injector in an internal combustion engine fuel-injection system is disclosed. The piezo-injector has a piezoelectric actuator and an injection needle driven thereby, and is configured for operation in a partial-stroke mode and a full-stroke mode. First, the internal combustion engine is brought to a defined operational point. Then, the time for the injector needle to strike its stop when said injector needle is opened, as well as the time for the injector needle to strike its needle seat again when said injector needle is closed, are measured. The measured times are compared to normal values determined at the test stand. Parameter(s) for the fuel-injection system are calculated, using different calculation models, and the results are stored. Finally, the calculated parameters of the different calculation models are compared to norm values determined at the test stand, and compared to one another.

Abstract: A method is disclosed for determining the force acting on the nozzle needle of a directly driven piezo injector, in which an electrical voltage is built on the piezo actuator which drives the nozzle needle by means of a charging process. After the charging process has ended, the voltage at the piezo actuator is measured again. A voltage gradient is determined from consecutive voltage values. Conclusions of the force acting on the nozzle needle are drawn from the voltage gradients.