CVT Supporting Structure With Impregnated Bush for Easier Assembly

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Solution Overview

Problem

Conventional continuously variable transmission supporting structures face challenges in manufacturability and assemblability due to the need for processing the outer peripheral surface of annular members and the requirement of grease filling in grease grooves.

Innovation Solution

The implementation of a shaft member with a diameter expansion member and an impregnated bush, where the shaft diameter is increased by the diameter expansion member, and the impregnated bush is placed between the diameter expansion member and the bearing, reducing sliding resistance without additional processing, thereby improving manufacturability and assemblability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a grease groove is formed on the outer peripheral surface of the annular member to reduce sliding resistance, then the sliding resistance between the bearing and annular member is reduced, but the manufacturability of the supporting structure is reduced

Engineering Contradiction:

Improvesliding resistanceVSAvoidmanufacturability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent introduces an impregnated bush as an intermediary component between the bearing and the shaft. The impregnated bush is a pre-manufactured component that already contains grease in its porous structure, eliminating the need to form grease grooves on the annular member. This mediator transfers the lubrication function from a processed surface feature to a separate lubricated component, resolving the contradiction between reducing sliding resistance and maintaining manufacturability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the state of grease from being placed in grooves on a processed surface to being impregnated within the porous structure of a bush component. This parameter change in how grease is contained and delivered eliminates the need for complex surface processing while maintaining effective lubrication, thus improving manufacturability without sacrificing sliding resistance reduction

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a grease groove is formed on the outer peripheral surface of the annular member, then sliding resistance is reduced, but the assemblability of the supporting structure is reduced

Engineering Contradiction:

Improvesliding resistanceVSAvoidassemblability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The impregnated bush is prepared in advance with grease already impregnated into its porous structure during manufacturing. This preliminary action of pre-lubricating the component eliminates the need for grease filling operations during assembly, thereby improving assemblability while still achieving the goal of reducing sliding resistance through proper lubrication

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If the first bearing directly supports the tip portion of the shaft member, then the supporting structure is simpler, but the surface pressure resistance is insufficient

Engineering Contradiction:

Improvesupporting structure complexityVSAvoidsurface pressure resistance

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

The patent applies local quality by introducing a diameter expansion member at the specific location where the shaft tip is supported. This expansion member locally increases the shaft diameter only at the bearing support location, improving surface pressure resistance where needed without changing the overall shaft design or adding complexity to the entire supporting structure. The impregnated bush further enhances this local area with lubrication properties

Inventive Principle:

Principle #3Local quality

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 configuration enhances the manufacturability and assemblability of the supporting structure by reducing sliding resistance and eliminating the need for surface processing, while maintaining stable support for the shaft.

Implementation Method 1

the impregnated bush is disposed between the diameter expansion member and the first bearing. With this configuration, the sliding resistance between the first bearing and the diameter expansion member can be reduced

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentEP4628750A1Continuously variable transmission and straddled vehicle including continuously variable transmission

Publication Date: 2025.10.08 YAMAHA MOTOR CO LTD

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AI summary

There is disclosed a continuously variable transmission (15) , which can improve a manufacturability of a supporting structure and an assemblability of the supporting structure, is provided; continuously variable transmission (15) of a straddled vehicle 1 including a primary pulley (41), a secondary pulley (42), a belt (43), a case (48) and a supporting structure (100). the supporting structure (100) being provided between case (48) and at least one of primary pulley (41) and secondary pulley (42); supporting structure (100) including a shaft member (46), a diameter expansion member (101), a first bearing (95) and an impregnated bush (102); the diameter expansion member (101) being disposed on an outer peripheral surface of a tip portion (46b) of shaft member (46); first bearing (95) being mounted to case (48); first bearing 95 being disposed at an interval from the diameter expansion member (101) in a radial direction; impregnated bush (102) being disposed between diameter expansion member (101) and first bearing (95) in the radial direction.