Parameter Design Of Roll Resistant Specific Hydraulically Interconnected Suspension And Simulation Analysis

The suspension system is an indispensable part of the vehicle, and has important effects on handling stability and ride comfort. However, many aspects of vehicle performance have contradictory requirement for suspension system, such as the tradeoff between handling stability and ride comfort. Hydraulically interconnected suspension can achieve good handling and ride comfort by decoupling bounce and roll modes though its specific connection.In this paper a mathematical model of roll resistant specific Hydraulically Interconnected Suspension is set up and the force generated by actuator is divided into stiffness force and damping force, which are used to study stiffness property and stiffness property respectively. Thus stiffness of bounce, roll, pitch and warp modes are studied through the model. Meanwhile how the parameters of main components influence the stiffness property is analyzed:(1)the nominal capacity and precharge pressure of accumulator proportional to the stiffness of each modes;(2)reducing the volume of accumulator air chamber of equilibrium leads to larger nonlinear stiffness;(3)although there are four independent variables of the geometry size of actuators, they influence the stiffness through a weighted sum,while the weight numbers are calculated based on the parameters about the positions where the actuators are installed, but nothing on their allocation. The expressions of weight numbers vary for different modes.Aiming at a sport utility vehicle(SUV), a set of parameters of HIS system are designed. Considering the features of vehicle suspension mechanism, roll stiffness is chosen as the main design reference. The single-wheel bounce stiffness is regarded as the additional spring stiffness provided by HIS system. Combining the influence of main component and design principles of actuator and accumulator, the parameters of HIS system and springs are determined. Finally, the principle of selecting pipes is discussed, which is based on the damping property of shock absorber and the influence of inside diameter of pipeline.To study the performance of vehicle with an HIS system, a series of simulation experiments are conducted. These simulation experiments include handling stability, ride comfort and tire road holding analysis. The key findings include the following:(1)the HIS system offers enough roll stiffness for improving handling stability, so it can be a good substitute for anti-roll bars. However, the roll stiffness is limited by the compression ratios of diaphragm accumulator with weak nonlinearity, and it has potential adverse effects on understeering;(2)in aspect of ride comfort, HIS system improves the ride comfort on bounce and pitch modes, while it makes the ride comfort on roll mode worse than that of the vehicle with anti-roll bar with the same stiffness;(3)HIS system provides significant improvements in performance of tire road holding and reducing the torsional load of the body, but the improvements seem unapparent when vehicle running on well road.