CVT Variator Gross Slip Detection via Multi-Parameter Thresholds
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Solution Overview
Problem
CVT variator systems experience false gross slip errors due to hydraulic pressure latency and system parameter uncertainties, leading to unnecessary clamping events and reduced fuel economy.
Innovation Solution
A method for CVT variator gross slip detection that determines differences in commanded and real variator speed ratios, checks variator rate of change and torque capacity ratios, and performs remedial actions such as setting fault codes and adjusting clamping to mitigate false triggers, using sensors like Hall Effect sensors to monitor pulley speeds and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional gross slip detection methods are used in CVT variator systems, then gross slip conditions can be detected, but false gross slip errors are triggered due to hydraulic pressure latency and system parameter uncertainties, leading to unnecessary clamping events
Solution Approach 1:
The patent implements a feedback-based detection system that continuously monitors variator speed ratio differences and compares them against dynamically updated reference values. The system uses feedback from speed sensors and hydraulic pressure sensors to adjust detection thresholds and differentiate between actual gross slip conditions and transient variations caused by hydraulic latency, thereby reducing false errors while maintaining reliable detection
Solution Approach 2:
The patent changes detection parameters by introducing multiple threshold levels (first threshold for speed ratio difference, second threshold for hydraulic pressure rate of change) and transitioning between different detection modes based on operating conditions. This parameter-based approach allows the system to adapt detection sensitivity to current variator operating states, reducing false triggers while maintaining detection accuracy
2Reliability
If unnecessary clamping events are triggered due to false gross slip errors, then variator clamping force is increased, but fuel economy is reduced
Solution Approach 1:
The patent performs preliminary detection and analysis of speed ratio differences and hydraulic pressure changes before triggering clamping events. By evaluating multiple parameters (speed ratio difference, rate of change, hydraulic pressure) in advance and comparing them against thresholds, the system prevents premature or unnecessary clamping actions, thereby avoiding unnecessary energy consumption and improving fuel economy
Solution Approach 2:
The patent introduces hydraulic pressure monitoring as an intermediary parameter that mediates between speed ratio detection and clamping actuation. By incorporating hydraulic pressure rate of change as a intermediate verification step, the system filters out false gross slip signals and only triggers clamping when both speed ratio and hydraulic pressure parameters confirm actual slip conditions, reducing unnecessary energy loss
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
Effectively reduces false gross slip errors, preventing unnecessary clamping and improving fuel economy by accurately detecting and addressing variator slip conditions.
Implementation Method 1
using sensors like Hall Effect sensors to monitor pulley speeds and pressures
Data Source
AI summary
A continuously variable transmission (CVT) and a method is provided for CVT variator gross slip detection includes determining if a difference between a commanded variator speed ratio and a real variator speed ratio is greater than a predetermined variator speed ratio threshold, and then determining if a variator rate of change ratio is outside of predetermined variator rate of change ratio limits. Further, the method includes determining if a real torque capacity ratio is greater than a predetermined torque capacity ratio threshold, and performing at least one remedial action when the variator rate of change ratio is outside of predetermined variator rate of change ratio limits, and the real torque capacity ratio is greater than the predetermined torque capacity ratio threshold when the difference between the commanded variator speed ratio and the real variator speed ratio is greater than the predetermined variator speed ratio threshold.