| Summary: | Renewable energy technologies, particularly in electric vehicles (EVs), have received significant attention in recent years. The wasted energy in a vehicle's shock absorber can be converted into an alternative energy source by regenerative shock absorbers. In this paper, a high-efficiency regenerative shock absorber considering twin ball screws transmissions is proposed for application in range-extended electric vehicles. The proposed regenerative shock absorber can convert vibrational kinetic energy, which is traditionally dissipated as heat in suspension systems, into electricity. The proposed system is divided into four modules: suspension vibration input module, transmission module, generator module and power storage module. Induced by road roughness, the irregular linear oscillations of the suspension are transmitted to the suspension vibration input module. The reciprocating vibrations are converted into unidirectional rotation of the generator by a pair of ball screws, gears, and two overrun clutches in the transmission module. The utilisation of different screw pitches leads to different damping coefficients for upward and downward progress, enabling the shock absorber to fully utilise elastic elements to improve vehicle comfort when compressed and quickly absorb vibrations when stretched. The electricity produced by the generator is stored in supercapacitors to charge the battery and extend the range of EVs. The mechanical properties of the full-scaled fabricated prototype were studied by utilising a mechanical testing and sensing fixture. An average power output of 3.701 W in 1Hz-3 mm sinusoidal vibration input and a peak efficiency of 51.1% and average efficiency of 36.4% were achieved in a bench tests. The range can be approximately extended by 1 mile per 100 miles when EV is driving on the road of class B with a speed of 60 km/h, demonstrating that the proposed high-efficiency regenerative shock absorber is beneficial for harvesting renewable energy, and practical and significant for extending the range of EVs.
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