CVT Movable Sheave Position Sensing via Cam-Rotation Conversion

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Solution Overview

Problem

Existing continuously variable transmissions (CVTs) with non-contact position detecting sensors for movable sheaves have complex structures, which can be improved for simplicity and accuracy in detecting the position of the movable sheave.

Innovation Solution

An electronically controlled CVT with a position detecting mechanism using a rotational shaft and a rotation sensor to detect the position of the movable sheave based on the rotational angle, incorporating a cam to convert linear motion into rotational motion and utilizing a torsion spring for enhanced assembly and accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a non-contact position detecting sensor based on magnetic field is used to detect the axial position of the movable sheave, then the position detection function is achieved, but the structure becomes complicated

Engineering Contradiction:
Improveposition detection accuracyVSAvoidsensor structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the magnetic field-based non-contact sensor with a mechanical position detecting sensor that detects position through direct mechanical contact or proximity sensing. This substitution simplifies the overall structure while maintaining position detection functionality, eliminating the need for complex magnetic field sensing components.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention uses a simplified sensing mechanism that copies the essential function of detecting axial position without replicating the complex magnetic field generation and detection system. The position detecting sensor achieves the same measurement objective through a more straightforward mechanical or electrical sensing approach.

Inventive Principle:
Principle #26Copying

2Measurement precision

If the position detecting mechanism is placed in a close position to the rotational shaft, then the detection accuracy is enhanced, but the assembly complexity increases

Engineering Contradiction:
Improveposition detection accuracyVSAvoidassembly complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent integrates the position detecting sensor directly into the movable sheave assembly or the rotational shaft structure, merging multiple functions into a single integrated component. This reduces the number of separate parts and simplifies assembly while maintaining close proximity for accurate detection.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The rotational shaft or supporting structure is designed to serve multiple functions: supporting the movable sheave, enabling its axial movement, and housing or mounting the position detecting sensor. This multi-functionality reduces the need for additional dedicated components and simplifies the overall assembly.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution allows for a simpler and cost-effective configuration with improved accuracy in detecting the position of the movable sheave, reducing the number of components and enhancing assembly ease.

Implementation Method 1

The shaft may include a cam converting a linear motion of the movable sheave in the axial direction into a rotational motion of the shaft

Methodology Applied
Scientific EffectCam mechanism: Cam

Implementation Method 2

a rotation sensor detecting a rotational angle of the shaft. The position detecting mechanism detects a position of the movable sheave based on the rotational angle of the shaft detected by the rotation sensor

Methodology Applied
Scientific EffectRotation sensing:

Implementation Method 3

The position detecting mechanism may further include an urging member urging the shaft to one side of a rotational direction of the shaft

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4632248A1Continuously variable transmission and straddled vehicle including same
Publication Date: 2025.10.15 YAMAHA MOTOR CO LTD
  • EP4632248A1 patent drawingFigure 1
  • EP4632248A1 patent drawingFigure 2
  • EP4632248A1 patent drawingFigure 3

AI summary

The present continuously variable transmission (15) includes a rotational shaft (22), a movable sheave (57), and a position detecting mechanism (100); the movable sheave (57) being supported by the rotational shaft (22) to be movable in the axial direction of the rotational shaft (22); the position detecting mechanism (100) including a shaft (104), rotated in conjunction with the movement of the movable sheave (57), and a rotation sensor (102) detecting the rotational angle of the shaft (104); the position detecting mechanism (100) detecting the position of the movable sheave (57) based on the rotational angle of the shaft (104) detected by the rotation sensor (102).