Robert Boschgmbh

Alfred Kizler

Gunter Schirmer

Klaus Dobler

Christian Zrenner

A voltage source for measurement of pressure fluctuations in internal combustion engine cylinders by current detected between the electrodes of the sparkplug after the spark has died down, is derived from the ignition voltage. A capacitor can be charged to a voltage of a few hundred volts for this purpose in various ways, and either a positive or a negative measurement voltage can be provided with respect to ground across a measuring resistor for further processing. Very few additional components are required. It is possible to provide a voltage that is continuously available for the convenience of timing the measurement and for the capability of making the measurement and all of the cylinders of the engine.

Voltage source for ion current measurement in an internal combustion

An apparatus serving to detect pressure fluctuations in the combustion chamber of an internal combustion engine, including an ionic current sensor, which is exposed to the gases in the combustion chamber and comprises a first electrode and a second electrode, between which a measurement voltage is applied and between which a connecting channel extends from the open combustion chamber into a dead space. In this manner, ionic currents may be detected which are caused by fluctuating pressures in the combustion chamber, particularly when there is engine knocking. Particularly when the geometry of the dead space is adapted to the frequency of the pressure fluctuations which are to be measured, these pressure fluctuations can be detected independently of other, slower pressure variations in the form of a pulsating current which is large when the ion-carrying gas enters the dead space and small when this gas, by now strongly deionized, exits the dead space.

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Stuttgart, Germany

Alfred Kizler