8挡自动变速器换挡控制策略

Gear Shift Strategy for a New 8-speed Automatic Transmission

为了实现8挡自动变速器工程化应用,通过建立液力自动变速器的简化动力学模型,分析影响换挡品质的关键控制因素。针对4种基本换挡类型,确立了换挡离合器及发动机控制的理想曲线。基于PI滑差控制和发动机协同控制理论,提出了快速充油、扭矩相及惯性相3个阶段的控制策略。搭建台架与整车试验测试环境,在极限状态下的试验结果表明,所提出的换挡控制策略正确、可行,具有工程化应用价值。

In order to achieve engineering application for a new 8-speed automatic transmission, a simplified dynamic model for hydraulic automatic transmission was built and key control parameters that affect shift quality were analyzed. For the four basic shift types, the ideal curves of shift clutch and engine control were set up. Based on torque estimation method, PI slip control algorithm and engine coordinated control theory, the control model and transmission controller were developed for three shift phases which included rapid-fill phase, torque phase and speed phase. In rapid-fill phase the command pressure at oncoming clutch was set as the kiss point at which point the oncoming clutch just transmits torque , in torque phase the torque change rate at off going clutch was controlled as similar as oncoming clutch based on torque estimation, in speed phase the engine torque reduction control was added to reduce the shift jerk. An environment of the rig and vehicle tests was built and the testing results obtained in extreme conditions can verify the accuracy and feasibility of this shift control strategy. The peak jerk during shift process was reduced significantly and the smooth gearshift was obtained. The strategy has high value for engineering application.