Simulation And Analysis On Hydraulic Power Steering System Of Heavy Vehicle

With the development of the levels of social progress and the automotive industry, more and more large-tonnage heavy vehicles continue to be developed and widely used in various fields. Depending on the differences of the load, heavy vehicles can be divided into 3 axes,4 axes,5 axes,7 axes etc. With the increasing of the loaded weight of the heavy vehicle and the vehicle weight, automobile in turn has to overcome the increasing resistance of steering from the ground to the steering wheel in the process turning. If you rely solely on the driver's role in turning force on the steering wheel to the steering wheel steering resistance overcome distance and vehicle steering, consequentially, the driver is steering heavily. So in order to reduce the heavy feeling while driver is steering and make the car get better mobility, heavy vehicles should be added power steering devices to reach the aim of light rail transit to the driver, reduce labor intensity and improve the safety of cars.In order to enhance the pilot's actions and the mobility of cars, the most effective way is to install power steering device. Current power steering devices generally can be divided into hydraulic power steering, electrically controlled hydraulic power steering and electric power steering. Electric power steering is generally used by light cars and heavy vehicles for hydraulic power steering or electronically controlled hydraulic power steering. The research on this article is for 5-axle heavy vehicles: former 3-axis uses hydraulic power steering; latter 2-axis uses electro-hydraulic power steering. Hydraulic power steering is based on the traditional mechanical steering, adding the hydraulic control valves, hydraulic cylinders, hydraulic pumps, storage tanks and pipelines, and other hydraulic devices, to achieve the role of power steering.The paper mainly includes the following contents:1)The calculation of hydraulic power steering system for vehicle parameters, the establishment of vehicle steering wheel angle to the transfer function of wheel rotation, the dynamic characteristic analysis of it by using MATLAB/Simlink and the analysis of dynamic characteristics of key performance parameters.2) The performance analysis of hydraulic slide valve which is the important parts of hydraulic power steering system. The establishment of three dimensional solid model of hydraulic control valve, and the performance analysis on fluid dynamics simulation software FLUENT will provide pressure, speed, flow and fluid dynamics simulation of curve under different valve port opening spool valve to verify the performance of slide valve.3) In AMEsim and ADAMS software, hydraulic system and mechanical systems of the vehicle hydraulic power steering systems are established respectively. The modeling of the hydraulic system parts includes hydraulic control valves, hydraulic cylinders and hydraulic pumps and other hydraulic components; the modeling of the mechanical system parts includes chassis, axle, steering, thrust rod, steering suspension, tires and other mechanical model. And the vehicle model parameter is set on hydraulic systems and mechanical systems.4) The machine-liquid co-simulation on the establishment of the vehicle hydraulic power steering system. Through the setting of simulation parameters,vehicle standing still turning and speed respectively 15km/h steering simulation curve can be accurately obtained in two different types of conditions, such as the flow and pressure curves of the hydraulic slide valve port; the force and displacement curve of hydraulic cylinder; the corner curve of the wheel. According to compare the simulation data with calculated values, the correctness of the simulation model of the vehicle can be verified, and it will provide a basis for the future research.