CVT Shift Control Device Matching Driver Intent
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Solution Overview
Problem
When a vehicle equipped with a continuously variable transmission and a drive assist device switches to a power mode with stepped shift control, the gear ratio calculated by the transmission may not match the required gear ratio calculated by the drive assist device, leading to unintended acceleration and a feeling of wrongness for the driver.
Innovation Solution
A shift control device that can select between stepless and stepped shift control modes, using a selection operation accepting module, a drive assist device, and an indicator value acquisition module to ensure consistent shift control by comparing driver intentions with calculated values, executing shift control in either mode based on the difference between target and required gear ratios or speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If stepped shift control mode is selected in a vehicle equipped with drive assist device, then gear ratio is changed in stepped manner like automatic transmission, but the target gear ratio calculated by continuously variable transmission may not match the required gear ratio calculated by drive assist device, causing unintended acceleration and driver confusion
Solution Approach 1:
The control device acquires an indicator value reflecting driver's acceleration request (e.g., accelerator pedal position) and compares it with the required indicator value calculated from drive assist device's required driving force. Based on this feedback comparison, the system determines whether to execute stepped or stepless shift control, ensuring the selected mode matches driver's actual intention and preventing unintended acceleration
Solution Approach 2:
The system dynamically switches between stepped shift control mode and stepless shift control mode based on real-time comparison between actual indicator value and required indicator value. This dynamic adaptation allows the system to optimize shift control characteristics according to current driving conditions and driver intentions, resolving the contradiction between stepped control preference and acceleration accuracy
Data Source
AI summary
When a stepped shift control mode has been selected by a selection operation accepting unit and an acquired value of an indicator acquired by an indicator value acquisition module is greater than a required value of the indicator calculated from a required driving force calculated by a drive assist device, a shift control module executes shift control in the stepped shift control mode. If the acquired value is smaller than the required value, the shift control module executes shift control in the stepless shift control mode.