In this paper, a physical mechanism of semi-active on-off damper is proposed to achieve the proposed variation in damping values without control devices. The performance is tested experimentally. The variable damping is achieved by the modulation of fluid flow orifices based on a control strategy which uses the relative displacement and velocity across the suspension system.
The damper was tested under steady state and found that its experimental performance agrees well with theoretical values wide over the operating frequency range. When a conventional on-off damper is adapted to a single degree-of-freedom suspension system, it makes poorer performances than that of utilizing passive damper in the region of the operating frequency is less then its natural frequency. To improve the performance of on-off damper in low frequency region, a pressure limited on-off damper, is suggested. It is designed that it works like a conventional damper in low frequency region but its function is changed automatically into an on-of type semi-active damper when the input frequency is raised to above its natural requency. Computer simulation shows that the shock and vibration isolation characteristics of the pressure limited on-off damper is superior to those of the passive damper over the whole frequency range. A Pressure limited on-off damper is prepared and its performance was tested and compared with the simulation results.
