Continental Automotive Gmbh

Christian Bauer

Janos Radeczky

Janos Kerekgyarto

A method and a device for determining the minimum hydraulic injection interval of a piezo-servo injector are described. The closing time of the nozzle needle of the injector is determined on the basis of the characteristic pressure profile in the control spring chamber of the injector. By incrementally reducing the injection interval of a subsequent injection by successively advancing the timing of the start of actuation of a subsequent injection and continuing to observe the pressure profile in the control spring chamber, the smallest injection interval is obtained from the last iteration step in which closing of the nozzle needle of the preceding injection could still be detected in the characteristic pressure profile. Particularly precise determination of the minimum injection interval is possible with this method.

Method and device for determining the minimum hydraulic injection interval of a piezo-servo injector

A method is provided for determining the fuel temperature in the high-pressure zone of a fuel injection system of a motor vehicle. The fuel injection system has at least one injector operated by a servo valve which is actuated by means of a piezo actuator. After an injection process has been carried out, the piezo actuator is discharged after the injection has ended in such a way that the servo valve can close, but a non-positive connection remains between the piezo actuator and the servo valve. This condition of reduced charge is maintained. The pressure oscillation of the actuator voltage resulting from this is recorded and from this the hydraulic natural frequency of the enclosed high-pressure volume of fuel is deduced. The prevailing fuel temperature can be determined from the natural frequency.

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Treffelstein, Germany

Christian Bauer