Research on the Method of the Feasible Design Space and a novel Electro-Hydraulic Energy Regenerative Suspension

In order to recover the energy generated by the vehicle's body vibration during driving and enhance riding comfort, this paper proposes a novel electro-hydraulic energy regenerative suspension. The novel suspension converts the up-and-down movement of the shock absorber into rotation through a hydraulic motor. The bidirectional rotation of hydraulic motor is decoupled into a unidirectional rotation through one-way bearings. And the forward and reverse rotations of the motor are respectively transmitted to the magnetic powder brake and the generator. When the damper extends, the magnetic brake prevents the motor rotating, generating damping force, which is damping state. When the damper is compressed, the hydraulic motor drives the generator to rotate, generating electrical energy, which is energy regenerative state. The model of damping force is established. The correctness of the model is verified by comparing the force-displacement diagram with experimental diagram. And the feasibility of the new suspension is validated based on the force-displacement diagram. A novel design method for energy regenerative type suspension based on feasible design space is presented. First, the root mean square (RMS) values of the sprung mass acceleration, the dynamic deflection, and the energy regenerative power are taken as the coordinate axes of a three-dimensional space. Curves are plotted to illustrate the trends of these three evaluation indices as the damping and stiffness ratios of suspension change. Then, based on the curves in three-dimensional coordinate system, the damping and stiffness ratios for energy regenerative suspension are determined. Finally, a relational model is established between the damping/stiffness ratios and key structural parameters such as hydraulic cylinder piston area, motor displacement, and stiffness of shock-absorbing spring. The key structural parameters can be determined based on the selected damping and stiffness ratios. A prototype of the novel suspension is manufactured. A vibratory test demonstrates that the novel energy regenerative suspension not only reduces vibration of the sprung mass but also converts vibration energy into electrical energy. Compared with the passive suspension, the maximum change in the RMS of acceleration occurs at a 6 Hz, 2 mm sinusoidal excitation. The decrease amplitude is 34%. When the frequency of the road excitation is 10.5Hz and the amplitude is 1.5mm, the regenerative energy reaches its maximum value of 0.3152J. The work provides a valuable reference for the R&D of electro-hydraulic energy regenerative suspensions.