ULTRASONIC DOPPLER VELOCITY SENSING WITHIN A HYDRAULIC ACTUATOR

摘要

A direct acting hydraulic damper comprising an internal, non-contact sensing means for the direct measurement of relative velocity between the piston and the cylinder of the damper. The damper comprising a cylinder forming a working chamber operable to store damping fluid. A piston is disposed within the cylinder defining an upper and lower portion of the working chamber. The damper further comprises a first transducer for emitting ultrasonic waves within the lower portion of the working chamber. The ultrasonic waves emitted by said first transducer are reflected by a base valve or end surface of the cylinder facing the transducers and are received by a second transducer. A frequency detection circuit determines the difference in frequency between the emitted and reflected ultrasonic waves and generates an output in response thereto. A computer then calculates the relative velocity of the piston with respect to the base valve or end surface, based on the Doppler principle. The velocity signal is then used for automatic control of suspension parameters according to predefined algorithm.