Research on fill phase control strategy of shifting clutch

In a clutch-to-clutch shift of automatic transmission, smoothness of shift requires not only good timing coordination between the oncoming clutch and the off-going clutch, but also proper pressure control of the engagement of the oncoming clutch. However, before the oncoming clutch pressure starts to increase, the initial cavity has to be filled first. The fill time and stability of the fill phase are very important for shifting clutch control. In order to improve the ride performance of the automatic transmission vehicles, a new fill phase control strategy is present according to the response analysis of the clutch pressure electro-hydraulic cushioning valve and analysis of the fill process of shifting clutch. Finally, the designed strategy is validated by a real bench test. The results demonstrated that the strategy can effectively decrease the fill time and decrease the clutch pressure shock.