基于 MPS 方法液力变矩器低温启动搅油力矩研究

The viscosity of vehicle transmission lubricating oil increases in low temperature environment, and its fluidity becomes poor, which increases the starting torque of transmission system. The torque converter is an important part of the vehicle transmission system. The churning torque during the starting process of the torque converter at low temperature is still unclear. The method based on moving particle semi-implicit(MPS) is used to study the variation of churning torque of torque converter with rotational speed at different operating temperature and different oil level. The feasibility of the numerical calculations is validated by the churning torque test bench built. The rheological properties of 5W-40 oil at low temperatures are tested using a rheometer. The transient variation of the churning torque in the torque converter under different starting modes at low temperature, as well as the distribution of lubricating oil and flow field characteristics, are analyzed. A device for reducing the churning torque during low temperature start-up is proposed. The research results indicate that the 5W-40 oil is a non-Newtonian fluid at low temperature. When the speed of the torque converter is 284 r/min, the churning torque at -43 ℃ is 2.5 times that at -20 ℃. Compared with linear start-up, segmented start-up has less energy loss. The proposed device can effectively reduce the churning torque during low temperature start-up of the torque converter, and the higher the speed, the more significant the effect. A numerical calculation method is provided for the calculation of the churning torque in the torque converter, along with theoretical support for designing a reduction in the churning torque during low temperature start-up in vehicle transmission systems.