CVT Sheave Hardness Differential for Wear Management
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Solution Overview
Problem
Conventional belt type continuously variable transmissions face challenges in simultaneously preventing wear of the V-belt and the sheaves, with resin block belts reducing sheave wear but increasing belt wear, and chrome plating sheaves exacerbating belt wear.
Innovation Solution
A belt type continuously variable transmission design featuring a primary sheave with a chrome-plated aluminum body and a secondary sheave made of stainless steel, where the surface hardness of the secondary sheave is lower than the primary sheave, and the secondary sheave is not plated with chrome, along with spiral grooves for wear powder retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the V-belt is made of rubber, then the V-belt is likely to wear to reduce durability, but using a resin block belt reduces sheave wear while increasing belt wear
Solution Approach 1:
The invention changes the material parameter of the V-belt from rubber to resin, and adjusts the surface hardness parameter of the sheaves by applying chrome plating to the primary sheave while leaving the secondary sheave unplated. This creates a differential hardness relationship where the primary sheave (chrome-plated) is harder than the resin belt, and the secondary sheave (unplated) is softer than the resin belt, thereby distributing wear differently across components.
Solution Approach 2:
The invention applies different surface treatments to different parts of the system: the primary sheave receives chrome plating to create a hard, wear-resistant surface, while the secondary sheave remains unplated with a softer surface. This local differentiation of surface properties allows the system to simultaneously protect against belt wear at the primary sheave and reduce belt wear at the secondary sheave through controlled material hardness variations.
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 design effectively prevents wear of both the V-belt and sheaves by managing contact pressures and surface hardness, ensuring compatibility and longevity of components.
Implementation Method 1
at least a surface of a contact part of the sheave body of the primary sheave contacting with the V-belt is coated with a plating material having a hardness higher than a hardness of its sheave body
Implementation Method 2
a surface hardness of a contact part of sheave halves of the secondary sheave contacting with the V-belt is lower than a surface hardness of a contact part of the primary sheave contacting with the V-belt
Data Source
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AI summary
The present invention relates to a belt type continuously variable transmission comprising a primary sheave to which a driving force from an engine is transmitted, a secondary sheave, and a V-belt wound around the primary sheave and the secondary sheave, the V-belt having a contact part contacting with the primary sheave and the secondary sheave, and at least a portion of the contact part being made of resin, wherein a surface hardness of a contact part of the secondary sheave contacting with the V-belt is lower than a surface hardness of a contact part of the primary sheave contacting with the V-belt.