Dual-chamber pneumatically interconnected suspension: Modeling and theoretical analysis

Increasing concerns on the compromise between the vehicle ride comfort and roll stability call for the continuous developments of the vehicle suspension systems. This paper devotes a theoretical study in developing a dual-chamber pneumatically interconnected suspension (DCPIS) system to enhance the vehicle ride comfort while maintaining good anti-roll performance. A quarter car with the dual-chamber air suspension is modeled to study the vibration characteristics in terms of the vertical stiffness and the natural frequency of the suspension. Further, a novel DCPIS system of a vehicle is proposed. By assuming the displacement excitations are small from the equilibrium position, the vibration equations of the mechanical-pneumatic coupled system for a roll-plane 4-degree-of-freedom (4-DOF) half-car model with DCPIS are derived in frequency domain, which include the dynamic equations of the mechanical system, the linear differential equations of the dual-chamber air springs, and the pipes. Based on the system dynamic equations, both the vehicle free vibration modes and frequency response functions (FRFs) are compared between the half-car with the DCPIS and that with the standalone dual-chamber air suspension. The results show that the DCPIS can alleviate the vertical and roll vibration because it decreases the suspension stiffness and meanwhile increases the system damping ratio. The effects of the DCPIS system parameters on the vehicle bounce and roll vibration transmissibility properties are further investigated. In addition, the bounce and roll stiffness characteristics of the DCPIS are studied. It shows that its nonlinear bounce and roll stiffness behaviors have the advantages not only to alleviate shocks under extreme impact from the road obstacle and but also prevent rollovers in sharp steering maneuvers.