CVT Acceleration Control via Target Pulley Speed Convergence
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Solution Overview
Problem
CVT-mounted vehicles experience non-linear acceleration due to sudden changes in pulley ratio during transitions from kick-down to linear sections, leading to rapid acceleration changes, which affect the smoothness of the driving experience.
Innovation Solution
A CVT acceleration control method that uses sensors to detect accelerator position, vehicle speed, and pulley rotation speeds, with a controller adjusting the pulley ratio to converge the driving pulley rotation speed to a target speed, preventing sudden changes by setting a gentle target speed change based on sensor inputs and predetermined conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If AT simulation control is implemented with rapid target Np changes during transition from KD to linear section, then dynamic driving characteristic is provided, but non-linear acceleration and smoothness degradation occur
Solution Approach 1:
The control method dynamically adjusts the target Np calculation based on the current operating section (KD or linear) and vehicle speed. In the linear section, a different target Np calculation formula is used compared to the KD section, allowing the system to adapt its control characteristics to the current operating conditions while maintaining smooth acceleration transitions.
Solution Approach 2:
The invention changes the control parameters (target Np calculation method) based on the operating section. By switching between different target Np calculation approaches depending on whether the vehicle is in KD or linear section, the system achieves both dynamic driving characteristics and acceleration smoothness without sudden non-linear changes.
2Speed
If rapid pulley ratio changes are used to follow target Np during linear section transition, then acceleration response is improved, but non-linear acceleration occurs
Solution Approach 1:
The control method performs preliminary action by calculating and setting the target Np in advance based on the predicted operating section and vehicle speed. This allows the pulley ratio to follow a pre-planned smooth trajectory rather than reacting to sudden changes, maintaining both acceleration response and linearity.
Solution Approach 2:
The system continuously monitors the current vehicle speed and operating section to provide feedback for target Np calculation. This feedback mechanism ensures that the pulley ratio changes are continuously adjusted to follow the target Np smoothly, preventing non-linear acceleration while maintaining responsive acceleration performance.
3Power
If target Np is rapidly increased during KD to linear section transition, then driving performance is enhanced, but current Np overshoots target Np causing non-linear acceleration
Solution Approach 1:
The control method dynamically adjusts the target Np based on the operating section and vehicle speed, preventing overly aggressive target increases that would cause overshoot. The system adapts the target Np growth rate to match the actual acceleration capabilities, maintaining both driving performance and speed control precision.
Solution Approach 2:
Instead of applying full aggressive acceleration demand, the system uses partial action by moderating the target Np increase rate during transitions. This prevents the current Np from overshooting the target while still providing sufficient acceleration performance for dynamic driving characteristics.
Data Source
AI summary
A CVT acceleration control method applied to a CVT-mounted vehicle including an accelerator position sensor, a vehicle speed sensor, a driving pulley rotation sensor and a driven pulley rotation sensor that is configured to detect a rotation speed of a driven pulley and to output a corresponding signal, a CVT operation portion and a controller, the CVT acceleration control method, may include determining, by the controller, whether a current vehicle driving state satisfies a predetermined starting control condition, monitoring, by the controller, a current driving pulley rotation speed change, determining, by the controller, whether the current vehicle driving state satisfies a predetermined trigger condition, setting, by the controller, a target driving pulley rotation speed change, and controlling, by the controller, the operation of the CVT operation portion such that the current driving pulley rotation speed change converges to the target driving pulley rotation speed change.