Robert Boschgmbh

Ulrich Schoor

Klaus Dobler

Rudolf Heinz

Thomas Frey

Friedrich Boecking

Werner Grunwald

Bertram Sugg

Kai Sutter

Michael Jupe

A method for diagnosing a fuel injection device which includes a piezoelectric actuator, with which a valve element is actuated. The fuel injection device is connected to a diagnostic device which applies a defined voltage to the piezoelectric actuator. The charge introduced into the piezoelectric actuator, and from that a capacitance of the piezoelectric actuator, are ascertained by means of the diagnostic device.

Method for diagnosis in a fuel injection device comprising a piezoactuator

A piezoelectric actuator for actuating a mechanical component, having a multilayered structure of piezoelectric layers with inner electrodes disposed between them and contacting outer electrodes on alternating sides and the piezoelectric actuator has chamfered corners or edges. In the region of the corners or edges, on the sides of the piezoelectric actuator on which the inner electrodes with alternating polarities are routed to the respective outer electrodes, the inner electrodes have a contour that makes it possible to achieve a lower field intensity between the inner electrodes of alternating polarities in the structure of piezoelectric layers. This is achieved by virtue of the fact that on the side that does not contact the outer electrodes, the edge has an obtuse angle (&#x221d;) or is rounded.

Piezoelectric actuator

A piezoelectric actuator is proposed, for example for actuating a mechanical component, and has a multilayered structure of piezoelectric layers with inner electrodes interspersed between them. The inner electrodes contact the outer electrodes on alternating sides and the regions between the outer electrodes are provided with a suitable insulation. The insulation is a layer comprised of a band, for example an adhesive tape, which covers over a predetermined region between the outer electrodes. The adhesive tape is comprised of a precisely measured, prefabricated material and can be stuck, rolled, melted, vulcanized, or sintered in place in a bubble-free manner.

Piezoelectric actuator and a method for producing it

A conductor (5) which varies its resistance value under the influence of pressure is introduced into the combustion chamber of the engine. In one embodiment the conductor is a wire (5), a coil, a meander pattern or the like; preferably, one part (5a) of the wire arrangement is shielded from the pressure. The shielded (5a) and the unshielded (5b) parts of the wire arrangement then form the branches of a bridge circuit. The sensor is preferably disposed in the breathing room (11) of a spark plug or for a Diesel engine, combined with an electric conductor (21, 44) serving to provide pre-glowing in a glow plug. Combustion pressures are thus sensed for controlling and/or regulating injection systems and/or ignition systems without requiring additional bores.

Sensor

To sense pressure within the combustion chamber of an internal combustion engine (ICE), a plug element which already extends into the combustion chamber of the ICE, such as a sparkplug, or a glow plug, has a layer-like resistor applied to a ceramic insulator extending into the combustion chamber, for example, directly on the central insulator of a sparkplug or on the side of a ceramic glow plug bushing or plug element. If applied to a sparkplug then, preferably, the heater is shielded by metallic layers, separated from the metallic shielding layers by insulating layers, of which the top metallic layer preferably is platinum or a platinum-type metal to catalyze combustion of residues which, otherwise, might collect on the top layer and interfere with proper sensor operation. The layer-like sensor and conductive tracks may be of thick film construction; stamp-on printing with flexible printing stamps is suitable to apply the layer-like resistors.

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Stuttgart, Germany

Ulrich Schoor