Characteristic analysis of a novel energy-harvesting hydraulically-interconnected suspension

The vehicle suspension system is not only used to consume the vibration energy transmitted from the ground to the vehicle body but also provides good handling stability for the vehicle. This can be a challenging tradeoff, especially for vehicles with a high center of gravity and heavy loads, such as trucks and SUVs. These vehicles are prone to large load deviations during emergency steering, causing the vehicle to roll over. The emergence of a hydraulically-interconnected suspension (HIS) could effectively maintain the vehicle body’s stability. As a unique hydropneumatic suspension, the HIS system has prominent nonlinear damping characteristics and can decouple the bounce motion and roll motion of the vehicle. This increases the vehicle’s roll stiffness without affecting the vertical rigidity of the vehicle, thereby substantially reducing the possibility of rollover accidents. This paper introduces a novel energy-harvesting hydraulically-interconnected suspension (EH-HIS), which has the dynamic characteristics of the HIS and can even harvest the vibration energy that is traditionally dissipated into heat using the oil shock absorbers. Working principles of bounce motion, roll motion, and pitch motion of the EH-HIS system have been analyzed. A mathematical model of the system was established based on the pressure drop principle and validated by a bench test. Damping characteristics and the energy harvesting capability are studied via simulations. Results show that the EH-HIS has considerable asymmetric and tunable damping characteristics that can meet the allowable range of most passenger vehicles. When the external resistance increases from 5 to 25 \mathrm\Omega , the corresponding equivalent damping coefficient decreases from 7558 to 3134 N·s·m⁻¹. The energy harvesting capability analysis shows that maximum energy harvesting power is achieved when the external resistance is equal to the internal resistance. Furthermore, the average harvesting power can reach 875.9 W under the excitation of 2 Hz (frequency) 30 mm (amplitude).