CVT Control Using Accelerometer for Traction Loss Speed
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Solution Overview
Problem
Continuously variable transmissions (CVTs) face challenges in accurately detecting vehicle speed during loss of traction events, leading to underperformance or overexertion, as traditional monitoring methods may provide inaccurate information during such conditions.
Innovation Solution
A control system comprising a controller, accelerometer, and sensors that monitor vehicle acceleration and wheel speed to compute an adjusted vehicle speed, generating a variator speed ratio and transmitting it to the CVT, using numerical integration and maintaining a constant grade acceleration signal to maintain optimal CVT operation during traction control events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional wheel speed sensors are used to detect vehicle speed, then the detection method is simple, but the detection accuracy deteriorates during loss of traction events
Solution Approach 1:
The patent introduces an accelerometer as an intermediary device to measure vehicle acceleration independently of wheel speed. This mediator provides a reference measurement that is not affected by wheel slip, allowing the system to calculate corrected vehicle speed by integrating acceleration data and comparing it with wheel speed sensor data during traction control events.
Solution Approach 2:
The patent replaces the purely mechanical wheel speed detection method with a hybrid system that uses an accelerometer to measure linear acceleration. This substitution allows the system to derive vehicle speed through numerical integration of acceleration data, providing accurate speed measurement even when wheel speed sensors fail during loss of traction.
2Reliability
If the CVT operates during traction control events using traditional speed detection, then the system continues to function, but performance deteriorates due to inaccurate speed information
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors both wheel speed sensor data and accelerometer data. During traction control events, the system uses the accelerometer-derived acceleration information to correct the vehicle speed calculation, providing accurate feedback to the CVT control algorithm and enabling reliable operation with optimal performance.
Solution Approach 2:
The patent changes the parameter used for speed detection from direct wheel speed measurement to integrated acceleration measurement during traction control events. By numerically integrating the accelerometer signal and comparing it with wheel speed data, the system adapts the speed detection parameter to maintain accuracy under varying traction conditions.
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
The system effectively adjusts the CVT speed ratio in real-time, ensuring optimal performance and preventing damage during traction control events by accurately detecting changes in vehicle operational states and maintaining the adjusted speed ratio until the event ceases.
Implementation Method 1
A control system having a controller, an accelerometer and one or more sensors in communication with the controller to detect a change in an operational state of the vehicle
Data Source
AI summary
A system and method for controlling a vehicle having a continuously variable transmission (CVT) comprises a control system having at least one controller, an accelerometer and one or more sensors in communication with the at least one controller to monitor and detect a change in an operational state of the vehicle. The control system determines a vehicle acceleration rate with the accelerometer in response to the change in the operational state of the vehicle. An adjusted vehicle speed is computed based, at least in part, on the vehicle acceleration rate. A variator speed ratio is generated based upon the adjusted vehicle speed and transmitted to the variator assembly of the CVT.