Dynamic Characteristics And Road Test Analysis Of A Heavy Truck Fitted With Hydraulically Interconnected Suspension

Barycenter of a tri-axle heavy truck is high and the load on it is heavy, because of this, there is a serious tendency to roll when the truck is in high-speed steering or in emergency avoidance. For the above, proposing a new device-hydraulically interconnected suspension(HIS)-to reduce roll of trucks. The HIS system is a kind of hydro pneumatic suspension and all of the wheels are connected to each other, movement on one wheel will impact the other wheels.An anti-roll HIS system is implemented in a tri-axle truck to increase its roll stiffness, thereby improving its anti-roll performance. The dynamic modeling of the truck with the HIS system consists of mechanical and hydraulic sub-systems coupled through mechanical-fluid boundary conditions. The vehicle mechanical sub-system is modeled by a nine degree-of-freedom mass-spring-damping system to represent the vibrations of a full-car model with six wheels. Hydraulic impedance method is employed to establish the relationship of hydraulic force and wheel’s displacement. Modal analysis is performed to compare the natural frequencies of the truck with and without the HIS system. The results show that the anti-roll hydraulically interconnected suspension can significantly improving vehicle roll resistance when does not affect other modes of the car.An automatic oiling-exhaust gas system and a durability test bench are designed for HIS system. A series of infield tests have been done include internal leakage test, pressure test and fatigue test. Stiffness-frequency test has been done based on durability test bench, the test results showed that there is a significant relationship between working frequency of HIS and its stiffness.A series of road test are carried out, including snaking test and right angle bend test, the test results of roll angles indicate that the HIS system is very e ffective on anti-roll stability, and it has a good performance at v ehicle ride comfort as well as handling stability.A torsion-eliminating Hydraulically Interconnected Suspension(THIS) is proposed to reduce the undesired articulation(warp) stiffness of a car. Car models are built in frequency domain and time domain. The research methods in frequency domain is the same as which in anti-roll HIS system research, hydraulic impedance method is also employed here, the research result in frequency domain shows that a car fitted with THIS has a bigger bounce stiffness. The time domain model is built with Simulink, in time domain simulation, give specific incentives to wheels to verify the results in frequency domain and find the dynamic characteristic of THIS.