CVT Belt Slippage Detection with Gear Ratio Derivative Thresholds
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Solution Overview
Problem
Existing belt-slippage diagnostic systems for continuously-variable transmissions struggle to accurately distinguish belt slippage from abrupt gear ratio changes caused by shift operations or road inputs, leading to incorrect diagnoses.
Innovation Solution
A belt-slippage diagnostic apparatus that uses a combination of first- and second-order derivatives of the gear ratio, heat quantity, continuation time, and hydraulic pressure analysis to determine slippage occurrence, including a slippage determination portion, heat-quantity determination portion, continuation-time determination portion, and responsiveness-defect determination portion to accurately diagnose belt slippage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If slippage is determined based on gear ratio change alone, then slippage detection is simple, but false detection occurs during abrupt shift operations or road surface inputs
Solution Approach 1:
The patent changes the parameter used for slippage detection from simple gear ratio to the derivative of gear ratio. By using the rate of change of gear ratio instead of the gear ratio itself, the system can distinguish between normal operational changes and actual slippage events, thereby improving detection accuracy while maintaining operational simplicity.
2Measurement precision
If multiple parameters (first-order derivative, second-order derivative, heat quantity, continuation time) are used for slippage determination, then slippage detection accuracy is improved, but system complexity increases
Solution Approach 1:
The patent segments the slippage detection process into multiple independent evaluation criteria: first-order derivative threshold, second-order derivative threshold, heat quantity threshold, and continuation time threshold. Each criterion is evaluated separately and contributes to the overall slippage determination, allowing the system to achieve high accuracy while maintaining modular complexity that can be implemented step-by-step.
Solution Approach 2:
The system uses feedback from multiple sensors (gear ratio sensor, temperature sensor, time measurement) to continuously monitor transmission conditions. The slippage determination portion integrates feedback from all these sources, comparing actual values against predetermined thresholds to make accurate slippage decisions, thereby improving measurement precision through multi-source feedback integration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise identification of belt slippage, differentiation between micro and macro slippages, and inference of slippage causes, improving the accuracy and reliability of durability assessment and hydraulic control in continuously-variable transmissions.
Implementation Method 1
a belt-type continuously-variable transmission including a primary pulley, a secondary pulley and a belt looped over the primary and secondary pulleys
Implementation Method 2
a heat-quantity determination portion configured, when the occurrence of the slippage of the belt is determined by the slippage determination portion, to determine whether a heat quantity, which is a quantity of heat generated by the slippage of the belt
Data Source
AI summary
A belt-slippage diagnostic apparatus for a continuously-variable transmission that includes a primary pulley, a secondary pulley and a belt looped over the primary and secondary pulleys. The belt-slippage diagnostic apparatus includes a slippage determination portion configured to determine occurrence of slippage of the belt on at least one of the primary and secondary pulleys, when a first-order derivative of a gear ratio, which is a ratio of a rotational speed of the primary pulley to a rotational speed of the secondary pulley, is not smaller than a first threshold value and a second-order derivative of the gear ratio is not smaller than a second threshold value.