CVT Secondary Sheave Spring Guide Buckling Control
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Solution Overview
Problem
Conventional belt-type continuously variable transmissions (CVTs) experience significant vibration issues, particularly at high engine rpm, which affects the performance and stability of straddle-type vehicles.
Innovation Solution
The implementation of a secondary sheave mechanism with a compression coil spring and an outside spring guide that restricts buckling, allowing the compression coil spring to compress and decompress smoothly, reducing vibration and noise, and enhancing the stability of the CVT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a compression coil spring is used in the secondary sheave mechanism, then the belt groove width can be varied to control speed change ratio, but significant vibration and noise are generated especially at high engine rpm
Solution Approach 1:
A buffer member is introduced as an intermediary element between the compression coil spring and the secondary moving sheave member. This buffer member absorbs and dampens the vibrations generated by the compression coil spring during operation, particularly at high engine rpm, thereby reducing the harmful vibration and noise while preserving the speed change ratio control functionality
Solution Approach 2:
The invention converts the harmful vibration energy generated by the compression coil spring into beneficial damping through the buffer member. The buffer member is specifically designed to utilize the vibration energy to enhance the overall stability of the secondary sheave mechanism, transforming the harmful effect into a stabilizing force
2Adaptability or versatility
If the compression coil spring is allowed to compress and decompress freely, then the mechanism can adapt to speed changes, but buckling occurs causing increased vibration and instability
Solution Approach 1:
The buffer member serves as a mediator that prevents direct buckling of the compression coil spring. By positioning the buffer member between the spring and the moving sheave member, it provides structural support that maintains spring stability during compression and decompression cycles, enabling speed adaptation without buckling-induced instability
Solution Approach 2:
The buffer member provides beforehand cushioning support to the compression coil spring, preventing buckling before it can occur. This preventive measure ensures that the spring maintains its structural integrity throughout the compression and decompression process, allowing smooth speed transitions while maintaining mechanical stability
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 effectively minimizes vibration and noise caused by the compression coil spring, improving the performance and stability of the CVT, especially at high engine speeds, by preventing buckling and maintaining a compact design.
Implementation Method 1
Between the spring stopper 147 and the secondary moving sheave member 137b is disposed a compression coil spring 145. The compression coil spring 145 urges the secondary moving sheave member 137b in the direction in which the belt groove 137c decreases in width
Implementation Method 2
When the rotation speed of the primary sheave 136 (the rotation speed of the engine 113) increases, the centrifugal force generated at the roller weights 144 also increases. Therefore, the pressure of the roller weights 144 onto the primary moving sheave member 136b overcomes the urging force of the compression coil spring 145
Data Source
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AI summary
In order to reduce the vibration of a CVT while the engine runs at high rpm, the secondary sheave 37 of a CVT 14 includes a fixed sheave member 37a, a moving sheave member 37b, a compression coil spring 45, and an outside spring guide 49. The compression coil spring 45 urges the moving sheave member 37b toward the fixed sheave member 37a. The outside spring guide 49 prevents the compression coil spring 45 from buckling during compression.