Various embodiments may include a method for operating a piezo-actuator in a piezo-operated injector for a fuel injection system comprising: producing a measuring pulse at a position at which the usable signal which is to be measured is expected; then producing a reference pulse which corresponds to the measuring pulse, in the same cycle; subtracting a first actuator voltage measured during the reference pulse from a second actuator voltage measured during the measuring pulse; using a resulting voltage signal difference to calculate a force sensed by the piezo-actuator; and using the force sensed to correct an injection amount for the injector.

Various embodiments include a method for operating an internal combustion engine with a fuel injection system including a piezo actuator comprising: stopping the discharge phase of the actuator during an injection cycle; measuring a voltage profile at the actuator; comparing a feedback signal at the actuator with a setpoint value; varying the discharge time of the actuator in successive injection cycles until the feedback signal corresponds to the setpoint value; defining a servo valve closing time as a defined offset with respect to the optimized discharge time; and using the defined servo valve closing time to set an injection quantity of fuel for future injection cycles.

A multi-layer piezoelectric element includes: a stacked body in which piezoelectric layers and internal electrode layers are laminated; a conductor layer disposed on a side face of the stacked body; a conductive joining material layer disposed on a surface of the conductor layer; and an external electrode joined to the conductor layer via the conductive joining material layer, the conductive joining material layer comprising solder and a conductive adhesive, the solder constituting an end of the conductive joining material layer which end confronts an end of the external electrode to be connected to an external circuit. There is provided a multi-layer piezoelectric element which suppresses separation of an end on an input/output side of the external electrode and is driven stably for a long period of time, an injection device and a fuel injection system which are provided with the multi-layer piezoelectric element.

Method for operating an injector, comprising the steps of generating (S201) a digital injection profile by combining trapezoidal individual injection operations which are matched to a prespecified target injection profile (200); and generating (S202) an electrical actuating signal for the injector on the basis of the generated digital injection profile and the actuating parameters of the injector.

An actuating-type gas guiding device includes a main body and a piezoelectric actuator. The piezoelectric actuator is disposed in the main body. The piezoelectric actuator includes a suspension plate, an outer frame, at least one bracket and a piezoelectric element. The suspension plate has a first surface and a second surface. The suspension plate is permitted to undergo a bending vibration. The outer frame is arranged around the suspension plate. The at least one bracket is connected between the suspension plate and the outer frame for elastically supporting the suspension plate. The piezoelectric element is attached on the first surface of the suspension plate. In response to a voltage applied to the piezoelectric element, the suspension plate is driven to undergo the bending vibration in a reciprocating manner. Consequently, gas is guided to flow in the main body along a non-scattered linear direction.

A fuel injection control device has a valve opening control portion which opens a control valve by electrically charging a piezoelectric element, and a valve closing portion which closes the control valve. The valve opening control portion includes a first rising control portion, a pause control portion and a second control portion. The first rising control portion increases a charge amount of the piezoelectric element during a first rising period. The pause control portion pauses an increase in the charge amount of the piezoelectric element during a pause period after the first rising period. The second rising control portion increases the charging amount of the piezoelectric elements again during a second rising period after the pause period. The pause period includes a period of immediately before the control valve is opened.

The present disclosure describes an injector for an internal combustion engine which includes an injector housing, a piezo-actuator control unit having a first set of terminals, a connecting plug on a head of the injector housing, the connecting plug having a second set of terminals, and an electrical connection between the control unit and the connecting plug within the injector housing. The electrical connection comprises a contact element with conductor tracks integrated into an insulating body. The conductor tracks are connected to the terminals of the control unit and of the connecting plug. A first end of the insulating body abuts the control unit or the connecting plug and a second end is spaced from the connecting plug or the control unit. The contact element includes an elastic device by means of which the insulating body is braced against the component it abuts.

A system and method for fast control of the timing of combustion in an internal combustion engine, comprising actuating a fast-acting fuel-additive supply valve to meter a variable amount of fuel additive into a fuel stream, thereby forming an additive-enhanced fuel with an additive concentration that can be dynamically adjusted as fast as each engine cycle; injecting the additive-enhanced fuel directly or indirectly into a combustion chamber or into an intake port; and combusting the additive-enhanced fuel.

A method for controlling a piezoelectric actuator of a fuel injector of an internal combustion engine of a vehicle, the actuator acting on valve elements to open or close the injector, respectively enabling or stopping the injection of fuel into a combustion chamber of the engine, includes the steps of: applying to the actuator a first nominal electric charge required to open the injector in accordance with the torque requested and the engine speed, to open the valve elements for fuel injection, instructing the closure of the injector to stop the fuel injection, by applying an electric discharge to the actuator to close the valve elements, the method applied from an on-board engine control unit during operation, and including applying to the actuator between these 2 steps at least one second electric charge to polarize the actuator during an opening phase of the injector and during fuel injection.

An injector includes an actuator arranged in an actuator space, a piston guide having a bore hole, and a piston arranged in the bore hole. The piston has a first end face facing the actuator and delimiting a first space in and/or on the bore hole, and a second end face lying opposite the first space and delimiting an adjoining second space in and/or on the bore hole. The piston is arranged between the first and second spaces, and a gap extends around the circumference of the piston between the piston and the bore hole. The piston includes a first material and the piston guide includes a second material, the first and second materials having different thermal expansion properties such that when the piston guide and/or piston are heated, the gap width of the gap decreases to limit fuel leakage between the first space and second spaces.