CVT Gear Ratio Control Learning for Smooth Power-Off Upshifts
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Solution Overview
Problem
Existing CVT systems lack a gear ratio control learning process, leading to delayed or rapid gear shifting and potential shocks during pulley gear shifting due to the driving state of the vehicle or wear and deterioration of the pulley and belt contact surface, which does not effectively reflect the driver's intention.
Innovation Solution
An apparatus and method for learning CVT gear ratio control, including an Acceleration Position Sensor, gear ratio detector, timer, and controller, which detect changes in the accelerator pedal and pulley gear ratio, and adjust the gear shifting time to achieve a target gear ratio, preventing rapid changes and ensuring smooth transitions by adjusting the slope of the gear ratio control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gear ratio control learning is not performed, then the system structure remains simple, but gear shifting becomes delayed or rapid causing shocks and not reflecting driver's intention
Solution Approach 1:
The system performs gear ratio control learning in advance by storing the relationship between accelerator pedal positions and gear ratios in a map table. This preliminary action allows the control unit to directly retrieve appropriate gear ratios during power-off up-shift events without complex real-time calculations, ensuring smooth gear shifting while maintaining relatively simple control logic.
Solution Approach 2:
The system implements feedback by comparing the current gear ratio with the target gear ratio retrieved from the map table, and adjusts the gear ratio control accordingly. The control unit continuously monitors gear ratio changes and modifies control pressure to achieve the target gear ratio, ensuring the actual gear shifting matches the driver's intention while maintaining system simplicity through iterative adjustment.
2Adaptability or versatility
If gear ratio control learning is performed, then driver's intention is reflected accurately, but the control process becomes more complex
Solution Approach 1:
The system pre-establishes the relationship between accelerator pedal positions and gear ratios through map table storage during normal operation. This preliminary action captures driver's typical operating patterns and intentions, allowing the system to adapt to driver preferences without requiring complex real-time learning algorithms during actual gear shifting events.
Solution Approach 2:
The system performs self-learning by automatically storing and updating the map table data based on actual gear shifting events and driver operations. The control unit autonomously adjusts the stored gear ratio information based on observed driver behavior and gear shifting outcomes, enabling the system to adapt to driver's intention without external intervention or complex additional sensors.
3Speed
If target gear ratio is changed rapidly, then gear shifting speed increases, but shocks occur during gear shifting
Solution Approach 1:
The system applies beforehand cushioning by implementing a gradual gear ratio change approach. Instead of immediately jumping to the target gear ratio, the control unit adjusts the gear ratio in controlled increments, reducing the rate of change. This cushioning effect prevents sudden shocks during gear shifting while still achieving the target gear ratio efficiently, balancing speed and comfort.
Solution Approach 2:
The system employs dynamic control by continuously adjusting the gear ratio based on real-time feedback from the gear ratio detector and control pressure sensor. The control unit modifies the gear ratio change rate dynamically during the shifting process, accelerating when appropriate and decelerating to prevent shocks, thereby optimizing both shifting speed and smoothness adaptively.
Data Source
AI summary
An apparatus for learning gear ratio control of a CVT (Continuously Variable Transmission) may include: an APS (Acceleration Position Sensor) configured to detect a change of an accelerator pedal in a CVT vehicle; a gear ratio detector configured to detect a pulley gear ratio of the CVT; a timer configured to measure the time during which gear ratio control learning is performed during power-off up-shift of the CVT; and a controller configured to receive the values detected through the APS, the gear ratio detector and the timer, and control the CVT to shift gears at a target gear ratio learned through the gear ratio control learning, during the power-off up-shift by coasting.