Study On Shift Process And Shift Quality Of 55-51SN Automatic Transmission

Caused by the characteristics of an internal combustion engine, there was something different between the out put speed and torque of the engine and what the vehicle required. A transmission is necessary to adjust the engine out puts as a media to meet the vehicles’ requirements in different driving condition even the aerocraft and ship also need a transmission. The main functions of a transmission are as following: Change the ratio according to the vehicle driving condition; Provide the neutral, reverse gear and parking function.Hydraulic Automatic transmission is one of the important drive train types matched on the contemporary passenger car. With the advance of the Auto society, traffic condition goes worse especially in the city, the global energy crisis and the rate of home users especially the female drivers is increasing rapidly. The most of drivers focus on the handling performance, durability, shift quality, fuel consumption, ride comfort etc. For hydraulic automatic transmission, the shift process is actually electrically controlled hydraulic system by friction unit(Clutch and brake) were separated and engaged. During the shift process, caused by the ratio step, separated and engaged schedule, engine torque or power response level etc. The state of the drive train changed before and after the shift action and jerk or shock will take place. Then the driver and passengers will feel uncomfortable with the friction unit hurts.At first, this paper analyzed the base structure of a traditional five speed automatic transmitson-55-51 SN, the shift processs and built the dynamic formula. Based on the simulation tool of CRUISE established the models and finished the simulation work of shift map setting.Secondly, analyzed the elements which influence the shift process and the shift quality.especially explained the influence in detail by the shift map, shift control technology, the power of inertial parts, the friction torque of clutch and the characteristic of the ATF. According to the application experience of the 55-51 SN transmission, explained the test processs and analyzed the result especially the caused reason.Thirdly, summed up the evolution method and set the main evolution targets.Finally, this paper concludes the related research fruit and insufficient,then point out the deeply study direction in the future.