CVT Variator Control for Road Disturbance Protection
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Solution Overview
Problem
Existing continuously variable transmission (CVT) systems lack effective control mechanisms to adapt to changes in vehicle operational states, such as road disturbances, wheel traction loss, and deceleration events, which can lead to damage or inefficiency.
Innovation Solution
A control system with sensors and a controller that monitors vehicle states and adjusts the variator speed ratio by overclamping the belt in response to detected events, such as road disturbances, wheel traction loss, or deceleration, to maintain optimal operation and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CVT operates without control mechanisms to adapt to changes in vehicle operational states, then the device complexity is reduced, but the reliability deteriorates due to potential damage from road disturbances, wheel traction loss, and deceleration events
Solution Approach 1:
The control system is pre-programmed with compensation strategies for various critical events (road disturbances, wheel traction loss, deceleration). When an event is detected via sensors, the controller immediately executes the predetermined compensation action by adjusting the variator speed ratio, eliminating the need for complex real-time decision algorithms while ensuring reliable protection
Solution Approach 2:
Sensors continuously monitor vehicle operational states (acceleration, wheel speed, brake pedal position) and provide feedback to the controller. This feedback loop enables the system to detect critical events and automatically adjust the CVT variator speed ratio accordingly, improving reliability without requiring overly complex device architecture
2Reliability
If the variator speed ratio is adjusted in response to detected events, then the reliability is improved by preventing damage, but the loss of time increases due to the compensation adjustment process
Solution Approach 1:
Compensation strategies are pre-calculated and stored in the controller for various critical events. When an event occurs, the controller simply retrieves and executes the predetermined speed ratio adjustment, minimizing the time required for compensation while ensuring reliable CVT protection
Solution Approach 2:
The control system rapidly executes the compensation adjustment by directly commanding the variator assembly to transition to the predetermined protective speed ratio, minimizing the duration of exposure to damaging conditions and reducing time loss while maintaining reliability
3Adaptability or versatility
If the control system monitors multiple vehicle operation states, then the adaptability is improved to detect various critical events, but the device complexity increases due to additional sensors and control logic
Solution Approach 1:
The control system uses a multi-functional approach where existing vehicle sensors (acceleration sensors, wheel speed sensors, brake pedal position sensors) serve multiple purposes - monitoring both normal operation and detecting critical events. This universal use of sensors improves adaptability without proportionally increasing device complexity
Solution Approach 2:
The control system leverages data already being collected by the vehicle's existing sensor network for other control functions. By repurposing this existing data for critical event detection and compensation, the system achieves high adaptability while avoiding the need for dedicated additional sensors and complex control logic
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 control system effectively adjusts the CVT speed ratio to mitigate damage and maintain efficiency during critical vehicle events, similar to downshifting in a step gear transmission, thereby protecting the CVT from stress and ensuring optimal performance.
Implementation Method 1
The endless rotatable drive element rides within a variable-width gap defined by conical pulley faces
Implementation Method 2
A clamping force may be applied to the variator pulleys via one or more pulley actuators. The clamping force effectively squeezes the pulley halves together
Implementation Method 3
A clamping force may be applied to the variator pulleys via one or more pulley actuators. The clamping force effectively squeezes the pulley halves together to change the width of the gap between pulley faces
Data Source
AI summary
A continuously variable transmission (CVT) for a vehicle includes an input member, an output member and a variator assembly including a first pulley rotatably coupled to the input member and a second pulley rotatably coupled to the output. The first and second pulleys are rotatably coupled by a flexible continuous rotatable device. A control system is provided including an instruction set executable to determine an initial variator speed ratio of the variator assembly and detect an event causing a change in an operational state of the vehicle. The control system determines a compensation strategy to adjust the variator speed ratio in response to the change in the operational state of the vehicle and generates an adjusted variator speed ratio based upon the compensation strategy. The control system transmits the adjusted variator speed ratio to the variator assembly.