Power-on downshift control for clutch-to-clutch automatic transmission

Power-on downshift is an effective way for the vehicle to achieve rapid acceleration and overtake. To achieve smooth power-on downshift, not only the clutch hydraulic pressure should be accurately controlled, but also the engine torque should be properly controlled. Based on the DEUTZ BF4M 1013 turbo-charged electronic unit pump diesel engine and the Allison S2000 clutch-to-clutch automatic transmission, an integrated powertrain control strategy for the power-on downshift process is proposed. First of all, the dynamics model of the downshift process is derived using the Lagrange method. Then the method for controlling the oncoming clutch and the offgoing clutch is obtained, and the coordinated engine control based on the turbine speed is proposed. The experimental study is carried out on the test bench. The experimental results show that the shift time is less than 1 s, and the shift jerk of the power-on downshift process is smaller than 10 m/s³. The proposed integrated powertrain control strategy for the power-on downshift process can be used for the practical engineering application.