Acceleration sensitive shock absorber

Abstract

A twin tube shock absorber has concentric inner and outer tubes connected to the wheel of a vehicle. A piston in the inner tube is connected to the chassis of the vehicle and divides the interior of the inner tube into upper and lower chambers. Fluid passes between these chambers and an annular reservoir between the tubes for absorbing shock in a conventional manner. An orifice is provided through the sidewall of the lower portion of the inner tube and is surrounded by a lower sleeve, which normally keeps the orifice closed. Upon upward acceleration of the tubes, the sleeve essentially remains fixed in space. The relative movement between the sleeve and tubes aligns a passage through the sleeve with the orifice and permits fluid to flow from the lower chamber below the piston to the annular reservoir. This provides a softer shock absorber when high upward acceleration is felt by the tubes of the shock absorber and a stiffer shock absorber during times when there is no large upward acceleration. A similar orifice and sleeve are provided at the upper end of the inner tube for permitting fluid to flow from the upper chamber into the reservoir during rapid downward acceleration of the tubes. The orifices are spaced apart from the ends of the inner tube so that when the piston passes an orifice, the characteristics of the shock may change from soft to stiff before the end of the stroke of the piston.