Reliability Analysis for Automatic Transmission Based on AMESim

摘要

This paper presents a qualitative simulation method on reliability analysis, considering that hydraulic control system of automatic transmission (AT) has a complex structure and its failure modes are various, unpredictable and occur randomly. First, by using AMESim, simulation models of hydraulic control systems and planetary gear sets, which worked together in GM 4T65E transmission,are set up. Then failure states of adjustable-displacement oil pump return spring and the No.4 shuttle valve are simulated individually. To cause failure of the adjustable-displacement oil pump return spring, its coefficient of rigidity is set to an infinitesimally positive number. Comparing simulation results of the failed component state with those of normal state, it can be learned that the failed return spring causes the output oil pressure of supply pressure regulation and flow control subsystem to become lower than system requirements.Therefore, AT does not have normal working oil pressure.It causes the shifting actuator to slip. Furthermore,sufficient power can not be produced to enable car to pull away from the curb. Similarly, to cause failure of the No.4 shuttle valve, its coefficient of flow is set to naught.Comparing the simulation results, it can be learned that the failed shuttle valve causes loss of third-gear engagement with the selector in D (Drive) or O/D (Overdrive) position and the engine's braking function with the transmission in first gear (manual low gear).Finally, relationship between failed components and AT's problem is established. After analysis, it can be learned that dynamic simulation using AMESim not only remedies the defect in steady-state simulation, but also opens up an avenue to 'Failure Mode and Effect Analysis' of AT. This becomes the foundation for trouble-shooting overall AT system. The simulation example demonstrates the efficiency of the presented method.