Electronic hybrid limiter (EHL) for pump displacement

The paper reports upon numerical simulation tests carried out on a variable displacement axial piston pump equipped with multiple automatic controls. The swashplate control circuit includes two classical hydraulic stages with two tandem three way valves (the pressure compensator and the flow limiter) and a servovalve with digital control circuit acting as a hybrid torque or/and speed limiter. The dynamic response of the system is evaluated for both separate and combined control functions. The effect of changes in the digital control circuit is discussed with reference to the system response to various load demands with special emphasis devoted to the benefits induced by the use of fuzzy control logic.