The Dynamic Parameter Analysis Of Vehicle With Limited Slip Differential

Limited Slip Differential (LSD) is a new high-technique for improving the performance of vehicle. It gets more and more extensive application in the international car product. At our country, research and develop work about it also begins to arouse more notice, and doesn't achieve suitable self-exploitation product in market. This paper has set up a hydraulic LSD model for computing torque transmitted with the help of key scientific research item from national economy-trade committee.We have completed some research tests and believable of design-compute and theory model. Meanwhile nine-freedom whole vehicle model for analyzing vehicle's controllability and stability is set up. At last, by way of computer simulation and comparison analysis using of the vehicle models with different differentials brought out upward, we have validated the improving of vehicle controllability and stability because of LSD and practicability of the vehicle model set up. Main contents as follows:First, the paper educes calculation equations for shearing torque transmitted by LSD from the research theory. Afterwards, the paper analyzes all kinds of factors that influence the characteristic of transferring torque of LSD and gets the calculation model for computing the shear torque of LSD, with inclusion of all factors that have effect on the characteristic. This model describes that the difference of rotate speed of two axle of LSD and the working temperature of it is the main outside factors influencing the shear torque of LSD.Second, we complete that how the characteristics of limited torque outputted change if circumstance changed. On the other hand, with a view to analyze the controllability and stability by virtue of the method of system simulation, by analyzing the vehicle in dynamics during its turning, this paper has analyzed the controllability and stability of rear-driving vehicle with LSD. This model may be used to analyze the effect of limited torque on vehicle's controllability and stability. And then the paper establishes a simulation model for computer based on the mathematic model explained upward. And then, the vehicle's controllability stability has been analyzed by using of computer simulation.With the comparison of vehicle with LSD and vehicle with ordinary differential, the paper finds the obvious improving of limited torque on vehicle's controllability and stability, and the feasibility of math model brought out. The effects on vehicle's controllability stability of LSD mainly consist in the decrease of yaw velocity, slide acceleration, and vehicle roll angle, and the increase of under-steer and steering force etc. These results indicate that the stability and security of the vehicle when turning is effectively improved, and in some degree the vehicle's ride comfortability is improved too. Meanwhile it just brings a little effect on fuel-economic in accepting degree. But the slip torque just brings a little bad effect on fuel economy. On the other hand, the effects on vehicle's instantaneous characteristic LSD consist in ahead of peak time, decrease of excess and steady state. These changes proves that LSD increases vehicle's rigidity when driving and decrease its damp. But the slip torque is a little bad for steering force.The research developed in this paper will urge people to the research of this new technique. This research will improve the matching degree between the LSD and vehicle's controllability and stability in the design of LSD. Therefore, this research will accelerate the coming forth of the suitable domestic LSD product. In addition, the attempt of this paper in analyzing the vehicle's dynamics by virtue of computer simulation will supply some help for other researchers on the application of Simulink technique in vehicle field.