CVT Pulley Ratio Control for Manual Shifting Response
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Solution Overview
Problem
Continuously variable transmission (CVT) vehicles experience driver dissatisfaction due to lack of responsiveness and a sense of incompatibility during shifting, as the pulley ratio changes unpredictably, affecting drivability and fuel efficiency.
Innovation Solution
A method where a controller senses the shift lever's position and fixes the pulley ratio in manual mode, re-adjusts set pulley ratios to maintain a consistent shifting feel, and controls the transmission to downshift on steep gradients, ensuring a uniform shifting experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the pulley ratio is continuously adjusted in CVT to improve fuel efficiency and power performance, then fuel efficiency and acceleration ability are improved, but the driver experiences stuffiness and boredom due to lack of response to engine RPM
Solution Approach 1:
The patent applies dynamics by enabling the CVT pulley ratio to change not only continuously based on driving conditions but also discretely in response to driver inputs (accelerator pedal operations). This dynamic adaptability allows the system to maintain fuel efficiency through continuous adjustment while providing driver engagement through responsive pulley ratio changes that reflect driver intent, effectively resolving the contradiction between fuel efficiency and driver engagement.
2Ease of operation
If manual shifting mode is implemented to improve driver engagement, then drivability is improved, but sudden pulley ratio changes occur causing driver incompatibility and discomfort
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal pulley ratio values for each manual shift position before actual shifting occurs. When manual shifting is selected, the controller references these pre-determined ratios and adjusts the pulley ratio smoothly to the target value, preventing sudden changes and ensuring comfortable transitions. This preliminary preparation of shift parameters resolves the contradiction between drivability and shift comfort.
Solution Approach 2:
The patent applies feedback by continuously monitoring the accelerator pedal position and using it as input for determining appropriate pulley ratio adjustments during manual shifting. The system provides feedback to the driver through smooth, predictable pulley ratio changes that respond to pedal input, creating a natural and comfortable shifting experience. This feedback mechanism ensures that pulley ratio changes align with driver intent, resolving the contradiction between drivability and shift comfort.
3Reliability
If the pulley ratio is fixed during manual shifting to prevent sudden changes, then shift comfort is improved, but the transmission cannot adapt to changing driving conditions
Solution Approach 1:
The patent applies dynamics by implementing a dual-mode pulley ratio control system that can operate in both fixed and adaptive modes. During manual shifting, the system maintains comfort by following predetermined ratio schedules, yet retains the ability to dynamically adjust ratios in response to accelerator pedal inputs and driving conditions. This dynamic flexibility allows the transmission to provide comfortable shifts while simultaneously adapting to changing driving conditions, resolving the contradiction between shift comfort and adaptability.
Data Source
AI summary
A method of controlling a pulley ratio of a continuously variable transmission vehicle, includes: sensing, by a controller, whether or not the position of a shift lever switches to a manual range, fixing, by the controller, a pulley ratio of a continuously variable transmission, when the position of the shift lever switches to the manual range, as a result of sensing, re-adjusting, by the controller, set pulley ratios of a plurality of manual shift positions based on the fixed pulley ratio of the continuously variable transmission, after the fixation, and controlling, by the controller, the continuously variable transmission at the re-adjusted pulley ratio of a target manual shift position, when manual shifting is required, after re-adjustment.