Prediction of Hub Load on Power Steering Pump Using Dynamic Simulation and Experimental Measurement

摘要

New trend in steering system such as EPS is coming up, but still hydraulic power steering system is more prevalent in today's vehicles. Power steering pump is a vital component of hydraulic power steering system. Failure of steering pump can lead to loss of power assistance. Prediction of hub load on pump shaft is an important design input for pump manufacturer. Higher hub loads than the actual designed load of pump bearing may lead to seizure of pump. Pump manufacturer has safe limits for hub load. Simulations can assist for optimization of belt layout and placement of accessories to reduce the hub load. Lower hub load can have direct effect on improvement of pump durability. This paper deals with dynamic simulation of belt drive system in MSC.ADAMS as well as vehicle level measurement of hub load on power steering pump. Hub load is measured with two different belt layout as well as in different maneuver related to cranking and high speed conditions at which the worst load cases are seen. At cranking, the highest torque load on a power steering pump typically occurs near idle RPM during a static steering situation, where maximum power steering assist is required. At cruising engine RPM, the vehicle is typically moving at reasonable speed and little power steering assist is required, thus lower operating pressure and a minimal torque load on the pump. The objective is to establish the methodology to predict the hub load and establish correlation between simulation and measurement.