Investigation on the Dynamic Behavior of a Solenoid Hydraulic Valve for Automotive Semi-Active Suspensions Coupling 3D and 1D Modeling,

The aim of this paper is to investigate the influence of the internal fluid flow characteristics of a special hydraulic solenoid valve, developed by hlins Racing AB, on its overall dynamic behavior. This valve is a two stage hydraulic pressure control valve and is typically mounted on each shock absorber of an on-road vehicle, allowing the implementation of semi-active suspension functionality. This technology is referred as CES (Continuously Controlled Electronic Suspension). The CES valve allows continuously controlling the vehicle shock absorbers damping characteristic by proportionally adjusting the metering geometry offered to its damping element, i.e. hydraulic oil. The electronic valve actuation and control, obtained through an electromagnetic solenoid, is based on the input from several vehicle dynamics sensors, such as accelerometers, gyroscopes and other displacement sensors. The CES valve's unconventional design significantly influences the fluid flow, making the use of numerical modeling essential to discover its physical behavior and to support further product development. In this paper, a CFD (Computational Fluid Dynamics) analysis on the main and pilot stages of the hydraulic valve is discussed. This 3D numerical analysis is used to extract critical physical variables, affecting the valve behavior, such as flow coefficients and pressure distributions on the moving elements, i.e. flow forces. This information is coupled with a detailed lumped parameter model of the hydraulic valve, which solves for the valve moving element dynamics considering the action of the main external forces. Moreover, the 1D model allows predicting the valve critical pressure/flow characteristics. It is shown how the coupling of 3D modeling results with the CES valve 1D model strongly improves the whole valve dynamics numerical predictions over traditional methods for considering the effect of fluid inertia and discharge in lumped parameter simulations. Comparisons with measurement both on single regions of the CES hydraulic valve and on the entire valve are discussed in order to validate the various phases of numerical modeling.