Electromechanically Actuated CVT Sheave Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mechanical continuously variable transmissions (CVTs) face challenges in providing precise and immediate control of gear ratios, leading to inefficiencies and complexity in manufacturing and maintenance, with existing systems often suffering from hysteresis effects and requiring complex adjustments.
Innovation Solution
An electromechanically actuated CVT system featuring a primary pulley with a fixed and mobile sheave, a cam system, and an actuation device driven by a motor and electronic controller, which adjusts the axial space between the sheaves based on engine speed and throttle position to control the transmission ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical CVT system uses springs, cams and centrifugal weights to generate clamping force, then the system can maintain force equilibrium, but the system suffers from hysteresis effects and slow response to load transitions
Solution Approach 1:
The patent replaces the mechanical spring-cam-weight system with an electromechanical actuator that uses electrical signals to control the mobile sheave position. This substitution eliminates the hysteresis effects inherent in mechanical springs and centrifugal weights, providing immediate and precise response to load transitions while maintaining reliable force equilibrium through electronic control.
Solution Approach 2:
The control system continuously monitors load conditions and automatically adjusts the actuator to maintain optimal clamping force. The system self-regulates the mobile sheave position based on real-time feedback, eliminating the need for manual adjustments and maintaining peak performance across varying operating conditions.
2Reliability
If a mechanical CVT system uses complex spring and cam mechanisms to control the mobile sheave, then the system can maintain torque transmission, but the system requires complex adjustments and tuning
Solution Approach 1:
The patent replaces complex mechanical adjustment mechanisms with an electromechanical actuator controlled by an electronic system. This eliminates the need for manual tuning of springs and cams, as the actuator can be precisely controlled through electrical signals to maintain optimal torque transmission across all operating conditions.
Solution Approach 2:
The system dynamically changes the clamping force parameter by adjusting the actuator position based on real-time operating conditions. This allows the CVT to adapt to varying torque requirements without requiring physical adjustments or tuning of mechanical components.
3Adaptability or versatility
If a mechanical CVT system uses centrifugal weights and springs to generate clamping force, then the system can automatically respond to speed changes, but the system has limited precision and immediate control
Solution Approach 1:
The patent replaces centrifugal weights and springs with an electromechanical actuator that receives electronic control signals. This substitution provides precise and immediate control of the mobile sheave position, enabling accurate ratio changes while maintaining automatic response to speed changes through electronic sensing and actuation.
Solution Approach 2:
The system incorporates feedback mechanisms that continuously monitor operating conditions and adjust the actuator position accordingly. This feedback loop ensures precise control of the transmission ratio while maintaining automatic adaptation to changing speed and load 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
This solution enables precise and immediate control of CVT ratios across its full operative range, reducing complexity and inertia, while maintaining stability and ease of maintenance.
Implementation Method 1
an actuation device having a drive motor and an electronic controller
Implementation Method 2
The cam system is rotatably connected to the mobile sheave and is adapted to provide an axial movement to the mobile sheave
Implementation Method 3
The torque supplied to the primary pulley by the engine is transmitted to the drive belt 106, then to the secondary pulley 104 by means of the friction between the conical surfaces of the sheaves and the sides of the drive belt 106
Data Source
AI summary
A pulley for a continuously variable transmission (CVT) and a method of controlling the pulley. The pulley has a main shaft, a fixed sheave, a mobile sheave and a cam system. The fixed sheave is fixedly mounted on the main shaft and has a fixed belt groove portion. The mobile sheave is movably mounted on the main shaft and has a mobile belt groove portion, the mobile sheave is mounted on the main shaft such that the fixed belt groove portion and the mobile belt groove portion form a riding path for a drive belt and is axially movable with respect to the main shaft such as to vary an effective diameter of the pulley by increasing or decreasing an axial space between the mobile sheave and the fixed sheave. The cam system is mounted at one end via a bearing fitted around the primary shaft to the mobile sheave. The cam system is adapted to provide an axial movement to the mobile sheave in order to increase or decrease the axial space between the mobile sheave and the fixed sheave.