Examination of Commercial Vehicle Clutch Servo’s Internal Hydropneumatic Control

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Dr. Sütő Zoltán
Department of Automation and Applied Informatics

Knorr-Bremse is a dominant participant in the field of railway and heavy commercial vehicle air brake systems. In commercial vehicle industry beside brakes it also develops different clutch servos, a group of which exists for 40 years by now, and excludes any electronics. The control is purely mechanical with the support of hydraulic and pneumatic media. Today’s production trends require a fully comprehensive knowledge of products with the purpose of economically more efficient production and lower cost supply while the lifespan is not affected.

Due to the capabilities of control an idea of a possible oscillation has occurred. This can offer critical information during the design of frictional parts. The deeper examination of this phenomenon required the measurement of control piston displacement. During the research of different measurement methods and their realizations a photo reflective encoder based measurement system seemed to be able to fulfill most requirements. Conventional solutions failed due to the well optimized geometrical design, the high pressure hydraulic and pneumatic media or because of the expenses.

With the realized measurement system the theoretical background of control methodology could be verified and also the effects of parameters during the oscillation could be examined. The collective effect of different parameters can expand the movement to six times longer with the attendance of several changes in the direction. The project also includes the validation of a simulation model which is based on the same problem. As it was suggested, the simulation could not produce an accurate solution for the movement of control piston although the appearance of events in the time domain seems reliable.


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