| Match between ISD suspension with variable interance and vehicle is always a new topic of vehicle dynamic system. According to the similarity principle of electrical and mechanical analogy, in this paper, dynamic matching problem of ISD suspension and vehicle was equated to the impedance matching problem in mechanical network. The match mechanism between ISD suspension and vehicle was mainly studied based on the ISD suspension structure of InerterSpring-Damper in parallel. The semi-control ISD suspension whose inertance is variable was proposed and the control theory, the design method and performance test technology have been mastered. The paper introduced inerter to the rear suspension of a mature car and the ISD suspension of Inerter-Spring-Damper in parallel was designed and its performances were verified by bench test. The research is to provide theory and method support for engineering application of ISD suspension.Firstly, on account of the impedance mismatching between vehicle and traditional suspension, the ISD suspension structure of Inerter-Spring-Damper in parallel was proposed in this paper. Based on the proposed model, the impedance matching problem was summarized as a class of single linear network containing source maximum power transmission problem. The matching mechanism between vehicle and suspension was obtained by using maximum power transmission theory and it was also verified right and valid by traditional dynamic models.Secondly, the quarter passive ISD suspension model of Inerter-Spring-Damper in parallel was built and simulated, however, the results show that it will not improve the suspension performances in the vehicle vibration frequency range, even the performances are deteriorated. In order to solve this problem, the semi-control ISD suspension with variable inertance based on the structure of Inerter-Spring-Damper in parallel was put forward. Meanwhile, the paper designed the LQG controller for the semi-control ISD suspension by integrating all three suspension performance indexes. Under the random excitation, at the speed of 20m/s, the vehicle body acceleration RMS value was reduced by 9.49%,the suspension work space RMS value was reduced by 35.04% and the dynamic tire load RMS value was reduced by 0.38%.From the comparative analysis of the semi-control ISD suspension in time domain and frequency domain, its excellent performances were demonstrated in simulation.Lastly, a fluid inerter was developed and this paper deduced its inertance expression formula. Also, the mechanical property and the impact of nonlinear factors were analyzed and the property test on numerical control electro-hydraulic servo system proved the simulated model right. On this basis, a three level adjustable fluid inerter was designed to applied in suspension system in parallel beside the traditional. The designed semi-control ISD suspension was lay out in suspension single channel test bench, three motivation models: sinusoidal input, sine sweep and random input were set for the performance bench test. In the random input running test, at the speed of 30,40,50km/h, the vehicle body acceleration RMS values were reduced by 4.61%,3.78%,3.76%, the suspension work space RMS values were reduced by 7.63%,3.89%,5.01%. Test results conform to theoretical research, and prove that semi-control ISD suspension with variable inertance can improve vehicle comprehensive performances, meet the requirements of ride comfort and handle stability.The research work in this paper reveals the matching mechanism between vehicle and suspension and provides a new analysis method in suspension dynamic study. The design method of fluid inerter lays the reliable foundation for ISD suspension system industrial application. The designed semi-control ISD suspension with variable inertance opens up a new road for improving suspension performances and technological innovation. |
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