Vehicle Drive Force Control Device for Sport Mode Torque Coordination
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Solution Overview
Problem
Conventional powertrain torque demand control methods independently control the internal combustion engine and automatic transmission, leading to deviations in final vehicle drive force when attempting to achieve a target drive force, particularly in sport modes.
Innovation Solution
A drive force control device with sensors for accelerator pedal opening and vehicle speed, and a programmable controller that computes and corrects target drive force and input torque to the automatic transmission, allowing for integrated control of speed ratio and engine torque to maintain target drive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the shift map is simply switched to sport mode in PTD control, then the speed ratio increases for better acceleration response, but the final vehicle drive force deviates from the target drive force
Solution Approach 1:
The controller continuously monitors the actual vehicle drive force and compares it with the target drive force. Based on this feedback, the controller adjusts the engine torque output to compensate for deviations caused by sport mode shift map switching, ensuring the actual drive force matches the target while maintaining the enhanced speed ratio characteristics
Solution Approach 2:
The system dynamically changes the engine torque parameter in response to sport mode activation. When sport mode is selected, the controller modifies the engine torque output parameter to work in conjunction with the altered speed ratio, maintaining the integral relationship between engine torque and transmission speed ratio that defines PTD control
2Speed
If the accelerator pedal opening is increased to improve acceleration response, then the target drive force increases, but the integral control relationship between engine torque and transmission speed ratio becomes difficult to maintain
Solution Approach 1:
The controller merges the sport mode shift control function with the PTD integral control function into a unified control system. This integration allows simultaneous management of speed ratio selection and engine torque adjustment, maintaining the coordinated relationship between these parameters even during rapid acceleration in sport mode
Data Source
AI summary
A target drive force is computed according to an accelerator pedal opening. A target input rotation speed lower limit basic value to an automatic transmission is computed based on a vehicle speed and a shift range of the automatic transmission. A target drive force lower limit correction value is computed based on the target input rotation speed lower limit basic value. The target drive force is corrected based on the target drive force lower limit correction value. A target input torque of the automatic transmission is computed based on the target drive force after correction. An input torque to the automatic transmission is controlled to the target input torque. By this control, an arbitrary drive force characteristic can be obtained in a PTD control.