CVT Control Using Fast Fourier Transform for Macro-Slip Reduction
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Solution Overview
Problem
Existing continuously variable transmission (CVT) systems face challenges in efficiently controlling torque transfer due to macro-slip conditions caused by improper clamping pressures, leading to reduced efficiency and potential damage to components.
Innovation Solution
A powertrain assembly with a controller that uses fast Fourier transforms to analyze signals from input and output sensors, adjusting clamping pressures based on amplitude and phase differences to optimize torque transfer and prevent macro-slip, thereby enhancing efficiency and component longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clamping pressures are increased to prevent macro-slip, then torque transfer reliability improves, but energy losses increase and component stress increases
Solution Approach 1:
The system dynamically adjusts clamping pressures in real-time based on actual operating conditions and detected macro-slip patterns. Instead of maintaining constantly high clamping pressures, the controller modulates pressures to match actual torque transfer needs, preventing macro-slip only when necessary and reducing pressures when conditions allow, thereby improving reliability while minimizing energy losses.
Solution Approach 2:
The system uses sensors to detect macro-slip conditions and feeds this information back to the controller, which then adjusts clamping pressures accordingly. This closed-loop feedback mechanism ensures clamping pressures are optimized based on actual performance, applying pressure only when macro-slip is detected or anticipated, thus improving torque transfer reliability without unnecessary energy expenditure.
2Reliability
If clamping pressures are increased to prevent macro-slip, then torque transfer reliability improves, but component stress and potential damage increase
Solution Approach 1:
The system dynamically adjusts clamping pressures based on real-time detection of macro-slip conditions rather than maintaining constantly high pressures. This dynamic adjustment prevents component stress and damage by applying high pressures only when and where macro-slip occurs, rather than uniformly across all operating conditions, thus improving reliability while protecting components.
Solution Approach 2:
The system applies different clamping pressures to different pulleys based on their specific operating conditions and detected macro-slip patterns. Instead of uniformly high pressures across the entire transmission system, the controller selectively increases pressure only at the pulley experiencing macro-slip, improving torque transfer reliability at the problem location while minimizing stress on other healthy components.
3Measurement precision
If fast Fourier transform analysis is implemented, then control precision improves, but device complexity increases
Solution Approach 1:
The system replaces complex mechanical sensing and adjustment mechanisms with electronic signal processing using fast Fourier transform analysis. Instead of mechanical devices to detect and respond to macro-slip conditions, the system uses digital signal processing of sensor data to identify macro-slip patterns and trigger electronic control responses, improving measurement precision while managing complexity through software-based solutions.
Data Source
AI summary
A powertrain assembly includes a continuously variable transmission having a variator, an input member, an output member and a torque converter clutch. An input sensor configured to receive a signal from the input member. An output sensor is configured to receive a signal from the output member. The assembly includes a controller having a processor and tangible, non-transitory memory on which is recorded instructions for executing a method of controlling the continuously variable transmission. If the torque converter clutch is locked, the controller is programmed to obtain respective readings at predefined time intervals which are collected for the respective signals from the input sensor and the output sensor, until a predefined time window is reached. First and second fast Fourier transforms are obtained of the respective signals. The continuously variable transmission is controlled based at least partially on the first and second fast Fourier transforms.