Modeling and simulation of a shift hydraulic system for a stepped automatic transmission
- Sarawoot Watechagit amd Krishnaswamy Srinivasan
- SAE Technical Paper, No:2003-0l-03l4, March 2003
It is well-known that the shift hydraulic system plays a major role in the operation of the stepped automatic transmission. The main functions of the shift hydraulic system are to generate and maintain desired fluid pressures for transmission operation, as well as to initiate gear shifts and control shift quality. Generally, the widely used hydraulic control system in automatic transmissions is a pulse width modulation (PWM) type. It consists of a solenoid valve and a reducing type second stage valve, the so called pressure control valve (PCV), to control the oncoming and off-going clutches. This paper presents a simulation model of the shift control system based on the AMESim software. A simulation analysis is conducted to study the working principle and performance of the pressure control valve, and is validated against experimental data. The effects of such parameters as spring stiffness, spool diameter and under lap are analyzed and optimized based on genetic algorithms. The results confirm that simulation analysis and structure parameter optimization with AMESim are instructive to the designing of the pressure control valve of shift hydraulic system.