A Shock Absorber Design with Position Sensitive Damper and its Performance Evaluation

Ride comfort and handling present conflicting requirements on damping properties of a suspension system. While ride comfort demands a softer damping, a higher damping force makes the ride handling better. Conventional dampers, being solely velocity dependent, are always a compromise between these two requirements. A damper can be made position sensitive, in addition to its velocity dependence, in order to obtain the best of both the worlds. A position-sensitive damper can have a softer damping force for low amplitude road excitations, as observed on highways and a higher damping force for higher amplitude road excitations, as observed in off-road conditions. Thus such a damper can be optimized not only for a good comfort, but for a good handling performance also. General designs for a position sensitive damper involve a bypass arrangement around the piston. This paper discusses an alternate arrangement for achieving position sensitive damping and its benefits. Prototypes of the same have been made and tested on a servo-hydraulic damper performance testing machine. Extensive analysis has been done to validate the position dependency. Further the prototypes have been tested on a vehicle. The findings are concluded in terms of an objective comparison between position sensitive damper and conventional damper.