CVT Gear Ratio Control for Driver-Intent Re-Acceleration
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Solution Overview
Problem
Existing sailing stop control systems fail to accurately match vehicle acceleration performance with the driver's intention, often resulting in excessive acceleration or difficulty in speed control after cancellation, leading to an uncomfortable driving experience.
Innovation Solution
A vehicle control method that estimates the driver's acceleration intention using a map-based approach, adjusts the gear ratio of the continuously variable transmission, and strategically engages the forward clutch to match the driver's input, preventing shock and enhancing acceleration response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the continuously variable transmission is downshifted to generate vehicle propulsion for re-acceleration when sailing stop control is cancelled, then the acceleration performance is improved, but the acceleration becomes excessive when the driver does not intend to accelerate, making speed control difficult
Solution Approach 1:
The patent applies dynamics by making the gear ratio adjustable based on detected driving conditions and driver acceleration intention. The control device dynamically selects between a first gear ratio (for acceleration) and a second gear ratio (for speed control) based on real-time detection of the accelerator pedal state and other driving parameters, allowing the transmission to adapt its characteristics to match driver intent rather than using a fixed downshift strategy
Solution Approach 2:
The patent changes the gear ratio parameter of the continuously variable transmission based on detected driving conditions. When acceleration intention is detected, the system selects a first gear ratio that provides higher propulsion, while when speed control is needed, it selects a second gear ratio that provides more moderate acceleration, thus using parameter changes to resolve the contradiction between acceleration performance and speed control
2Loss of time
If the engagement element is engaged immediately after downshifting to quickly generate vehicle propulsion, then the response time is reduced, but the acceleration performance may not match the driver's acceleration intention
Solution Approach 1:
The patent implements feedback by continuously monitoring the accelerator pedal operation amount and other driving parameters to detect driver acceleration intention. The control device uses this feedback information to determine whether to select the first or second gear ratio, and to control the timing of engagement element engagement, ensuring that the acceleration response matches driver intent while maintaining quick response time
Solution Approach 2:
The patent applies preliminary action by detecting acceleration intention before the engagement element is engaged. The control device analyzes accelerator pedal operation and other parameters in advance to determine driver intent, then pre-selects the appropriate gear ratio and timing for engagement element engagement, ensuring that the acceleration response is both quick and accurately matched to driver intention
Data Source
AI summary
Provided is a vehicle control method in which a controller executes sailing stop control in which, if the conditions for stopping a drive source are satisfied during travel, the drive source is stopped and a coupling element provided in a power transmission path between the drive source and a continuously variable transmission is released for coasting. If the conditions for stopping the drive source are not satisfied, the controller restarts the drive source and estimates the driver's intention to accelerate, and if the driver has an intention to accelerate, the gear ratio of the continuously variable transmission is increased to a higher value than when there is no intention to accelerate, and the coupling element is coupled.