Modeling and Experiments of a Hydraulic Electromagnetic Energy-Harvesting Shock Absorber

Hydraulic electromagnetic energy-harvesting shock absorbers (HESAs) have been proposed recently, with the purpose to mitigate the vibration of vehicle suspensions and also recover the vibration energy traditionally dissipated by oil dampers. This paper designs an HESA prototype for heavy vehicles and creates a dynamic modeling to study its characteristics. The model shows that the HESA's output force can be decomposed into the electric damping force, friction damping force, the inertia force, and the accumulator force. Based on the modeling, the counteracting effect between the accumulator force and the inertia force is explained, and the influences of the parameters are analyzed. Simulations are conducted to investigate the effects of the high-pressure accumulator and the inertia on the regenerative voltage. Experiments are also carried out to study the characteristics of vibration damping and energy harvesting. Results show that the damping coefficient of the proposed HESA ranges from 32 to 91 kNs/m, which covers most of the damping range of 25–50 kNs/m for typical heavy-duty trucks and 15–80 kNs/m for railway freight vehicles. The average regenerative power reaches 220 W and the corresponding hydraulic efficiency reaches 30%, at a vibration input of 3 Hz frequency and 7 mm amplitude. Moreover, the influences of different hydraulic components on the hydraulic efficiency are also experimentally studied in order to guide the future design of HESAs.