Centrifugal Clutch Half-Clutch Buffering for Smoother Gear Shifts

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Centrifugal clutches in straddled vehicles experience gear-shift shocks and a decrease in connection capacity when transitioning between gear stages, particularly when using quick shift mechanisms.

Innovation Solution

A centrifugal clutch configuration with a half-clutch state is introduced, utilizing a manipulation force transmission member, a half-clutch manipulation force buffer spring, and a preload member to manage the transition between connected and disconnected states, reducing abrupt changes in speed and frictional engagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the centrifugal clutch transitions from non-connected state to connected state, then power transmission is established, but gear-shift shock occurs due to abrupt speed and driving force changes

Engineering Contradiction:
Improvepower transmission capabilityVSAvoidgear-shift shock
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a buffer spring mechanism that is pre-configured to absorb shock during clutch engagement. The buffer spring is positioned between the pressure member and the friction plates, and is designed to be compressed during the transition from non-connected to connected state, thereby cushioning the abrupt speed and driving force changes that cause gear-shift shock.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent employs a dynamic engagement mechanism where the clutch plates are gradually brought into contact through a controlled movement sequence. The pressure member moves progressively to engage the friction plates, allowing the system to transition dynamically from non-connected to connected state rather than through abrupt engagement, thus reducing shock.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If the centrifugal clutch is disconnected during gear shifting, then gear stage switching is facilitated, but connection capacity decreases

Engineering Contradiction:
Improvegear stage switchingVSAvoidconnection capacity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent implements a partial disengagement mechanism where the clutch is not fully disconnected but rather partially engaged during gear shifting. The pressure member is positioned to maintain light contact between friction plates, providing sufficient connection capacity while still allowing smooth gear stage switching. This partial action approach prevents complete disconnection and reconnection cycles.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent ensures continuous power transmission during gear shifting by maintaining a baseline level of clutch engagement. The buffer spring and pressure member are designed to preserve continuous contact between friction plates, eliminating complete disconnection and reconnection cycles, thereby maintaining connection capacity while facilitating smooth gear stage switching.

Inventive Principle:
Principle #20Continuity of useful action

3Productivity

If quick shift mechanism is used to facilitate gear switching, then disengagement and engagement speed is increased, but gear-shift shock is exacerbated

Engineering Contradiction:
Improvegear switching speedVSAvoidgear-shift shock
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent incorporates a buffer spring mechanism that is pre-configured to absorb the increased shock generated by rapid quick shift operations. The buffer spring is positioned to engage before the full impact of quick shift occurs, cushioning the abrupt changes in speed and driving force that result from high-speed disengagement and engagement.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent modifies the engagement parameters of the clutch system to accommodate quick shift operations. The buffer spring is designed with specific elastic properties and pre-compression levels that allow it to effectively cushion the high-speed engagement characteristic of quick shift mechanisms, thereby reducing gear-shift shock while maintaining high switching speed.

Inventive Principle:
Principle #35Parameter changes

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 effectively suppresses gear-shift shocks while maintaining connection capacity, ensuring smooth transitions and reducing wear-related fluctuations in gear-shift shocks over time.

Implementation Method 1

as the weight member moves outward along with rotation

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

a half-clutch manipulation force buffer spring interposed between the manipulation force transmission member and the pressing portion, the half-clutch manipulation force buffer spring being configured to be pushed by the manipulation force transmission member moving in the releasing direction, and elastically deform, to bias the pressing portion in the releasing direction

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 3

a first friction plate configured to rotate integrally with the clutch housing; a second friction plate configured to rotate integrally with an output section of the centrifugal clutch

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4656896A1Straddled vehicle
Publication Date: 2025.12.03 YAMAHA MOTOR CO LTD
  • EP4656896A1 patent drawingFigure 1(a)~1(b)
  • EP4656896A1 patent drawingFigure 2
  • EP4656896A1 patent drawingFigure 3(a)~3(b)

AI summary

To provide a centrifugal clutch and a straddled vehicle capable of reducing a gear-shift shock while suppressing a decrease in connection capacity in a connected state, a centrifugal clutch includes: first friction plates; second friction plates; a pressure member; a pressing portion; a cam portion; a clutch spring; a weight member; a manipulation force transmission member configured to receive a manipulation force to apply a half-clutch manipulation force to the pressing portion, the half-clutch manipulation force resisting a biasing force of the clutch spring; a half-clutch manipulation force buffer spring interposed between the manipulation force transmission member and the pressing portion, the half-clutch manipulation force buffer spring being configured to be pushed by the manipulation force transmission member moving in the releasing direction, and elastically deform, to bias the pressing portion in the releasing direction; and a preload member that is fixed to the manipulation force transmission member so as to create a state in which the half-clutch manipulation force buffer spring and the pressing portion are pinched between the preload member and the manipulation force transmission member while a preload is applied to the half-clutch manipulation force buffer spring.