Abstract: A method for controlling the injection quantity of a piezoinjector of a fuel injection system, which comprises a nozzle needle displaceable by a piezoactuator. Based on the instantaneous injection quantity, a selection is made among various control methods. In a ballistic injector mode, a first control method is carried out, wherein both a needle closing point in time is equalized and a needle travel time is also equalized. In a full stroke injector mode, a second control method is carried out, wherein a needle closing point in time is equalized, but the needle travel time is not equalized.

Abstract: A method for determining a position of a lock element of an injection valve for an internal combustion engine includes moving the lock element in the direction of a locked position in a closing movement in order to lock the injection valve, subsequently measuring a closure time at which the lock element arrives in the locked position, determining a time difference between the closure time and a preceding starting time of the closing movement, and determining, based on the time difference, a position which the lock element has assumed at the starting time of the closing movement.

Abstract: A method for actuating a piezoelectric actuator and a piezo injector of a fuel injection system having a nozzle needle which can be moved between the closed position and an open position by the piezoelectric actuator are disclosed. Current is applied to the piezoelectric actuator from a source for the duration of a charging time as a function of a required quantity of fuel, in order to move the nozzle needle into its opened position for a time period which is dependent on the required quantity of fuel. The charging time is selected according to the following relationships: tcharge(p)=tnom,charge (p) for TI>tEP,p and tcharge (p, TI)?Ti for TI?tEP,p.

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 for determining the actual start of injection is performed by an actuating device for a piezo fuel injection valve and includes the following steps. First, a test injection is carried out with such a short actuation duration that a start of shut-off takes place at a time so early that the nozzle needle does not reach the open end position. Said time is predefined by the actuation and is therefore precisely known. Next, the closing time of the nozzle needle is then determined by measurement and evaluation of an electrical variable of the piezo direct drive. Once the closing time and the time of the start of shut-off are known, the actual start of injection is calculated back from the closing time via the start of shut-off. This permits an adequately precise determination of the actual injection quantity in almost every operating state of the internal combustion engine.

Abstract: A method is disclosed for detecting a nozzle chamber pressure in an injector that includes a closure element for opening and closing an injection opening, at least one actuator which directly actuates the closure element, and at least one sensor for measuring a state, which is dependent on the nozzle chamber pressure, of the closure element, wherein at least one measurement variable which is dependent on the state is detected by means of the sensor, and wherein a deviation of the measurement value from a predefined value is determined. An injection system for carrying out such method is also disclosed.

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 for actuating a piezoelectric actuator and a piezo injector of a fuel injection system having a nozzle needle which can be moved between the closed position and an open position by the piezoelectric actuator are disclosed. Current is applied to the piezoelectric actuator from a source for the duration of a charging time as a function of a required quantity of fuel, in order to move the nozzle needle into its opened position for a time period which is dependent on the required quantity of fuel. The charging time is selected according to the following relationships: tcharge(p)=tnom,charge (p) for TI>tEP,p and tcharge (p, TI)?Ti for TI?tEP,p.

Abstract: A method for controlling the injection quantity of a piezoinjector of a fuel injection system, which comprises a nozzle needle displaceable by a piezoactuator. Based on the instantaneous injection quantity, a selection is made among various control methods. In a ballistic injector mode, a first control method is carried out, wherein both a needle closing point in time is equalized and a needle travel time is also equalized. In a full stroke injector mode, a second control method is carried out, wherein a needle closing point in time is equalized, but the needle travel time is not equalized.

Abstract: A method for determining the actual start of injection is performed by an actuating device for a piezo fuel injection valve and includes the following steps. First, a test injection is carried out with such a short actuation duration that a start of shut-off takes place at a time so early that the nozzle needle does not reach the open end position. Said time is predefined by the actuation and is therefore precisely known. Next, the closing time of the nozzle needle is then determined by measurement and evaluation of an electrical variable of the piezo direct drive. Once the closing time and the time of the start of shut-off are known, the actual start of injection is calculated back from the closing time via the start of shut-off. This permits an adequately precise determination of the actual injection quantity in almost every operating state of the internal combustion engine.