CVT Drive Force Control Device Torque Speed Ratio Adjustment
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Solution Overview
Problem
Conventional powertrain torque demand control methods for vehicles with continuously variable transmissions often result in drive force deviations and excessive sensitivity, leading to deteriorated drivability when correcting target rotation speeds without adjusting target torque.
Innovation Solution
A drive force control device that calculates and adjusts target transmission input rotation speed and torque based on accelerator pedal opening, using a programmable controller to manage speed ratios and output torque, ensuring similar response and followability to conventional engine torque demand control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the target rotation speed is corrected to be slightly higher when running load is large, then the drive force response improves, but the drive force deviates from the target drive force
Solution Approach 1:
The patent changes the calculation parameters by using the corrected target rotation speed (after increase) to calculate the target torque, rather than using the uncorrected rotation speed. This parameter change ensures that the torque calculation reflects the actual operating conditions, maintaining drive force accuracy while allowing rotation speed correction for improved response.
2Speed
If the target rotation speed is corrected to be slightly higher while maintaining target torque as is, then the drive force response improves, but the increase sensitivity becomes excessive
Solution Approach 1:
The patent implements feedback control by calculating the target torque based on the corrected target rotation speed and comparing it with the actual drive force. The controller adjusts the torque output to maintain the target drive force, preventing excessive sensitivity while preserving the improved response from rotation speed correction.
Solution Approach 2:
The patent dynamically adjusts the target torque parameter based on the corrected rotation speed and actual operating conditions. By changing the torque parameter in response to rotation speed correction, the system maintains balanced sensitivity and drivability while achieving improved response.
3Device complexity
If the target torque is calculated using the target rotation speed prior to correction, then the calculation is simpler, but the drive force deviates from the target drive force
Solution Approach 1:
The patent changes which parameter is used in the torque calculation - specifically using the corrected target rotation speed (after increase) instead of the uncorrected rotation speed. This simple parameter substitution maintains calculation simplicity while eliminating drive force deviation.
Data Source
AI summary
A drive force control device for a vehicle having a continuously variable transmission that varies an output rotation of a motive force source and transmits a rotation after variation to a drive wheel includes an accelerator pedal opening sensor that detects an accelerator opening of an accelerator pedal with which the vehicle is provided, and a programmable controller programmed to calculate a target drive force on the basis of the accelerator opening, calculate a target transmission input rotation speed on the basis of the target drive force, calculate a target transmission input torque on the basis of the target drive force, control a speed ratio of the continuously variable transmission to realize the target transmission input rotation speed, and control an output torque of the motive force source to realize the target transmission input torque.