A conventional vehicle suspension system contains passive elements, namely a viscous damper and a spring. The damper converts vibration energy into heat energy-due to the viscous friction of fluid in the device, and is finally dissipated to the external environment. Other than damper configuration, the amount of energy dissipated largely depends on the road roughness, the vehicle velocity and the vehicle mass. Under common operating conditions, this energy may be considered insignificant. On the other hand, over rough urban roads, the energy may be higher and thus presents a potential to tap the energy. For this, a hybrid linear motor/generator may be adapted to replace existing damper in the vehicle suspension system. With an appropriate controller, the device may be alternated between damping and generating device to provide damping as well as extracting energy. The energy even small may help in improving the efficiency of vehicle, especially electric and hybrid vehicle systems. With such device, it is also possible to vary the damping in a nonlinear and adaptive manner to accommodate the conflicting requirement between high speed operation and control of resonance. This investigation examines the feasibility of a hybrid suspension damper namely, linear motor/generator in providing adequate damping for isolation of vibration while generate energy from relative motion between sprung and unsprung masses. The study utilizes a simplified quarter vehicle model with linear spring and the proposed damping/generating device to illustrate its performance. The performances are evaluated in terms of acceleration transmissibility, rattle space, power spectral density (PSD) of acceleration response, and Dynamic Load Coefficient (DLC) to quantity the resulting pavement loads.
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