Clutch Cam Assembly With Split Clearances for Stable Torque Transfer

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Solution Overview

Problem

Existing clutch devices face instability in torque transmission due to low fitting accuracy between the pressure member and the clutch member, leading to tilting of cam surfaces and insufficient thrust force.

Innovation Solution

A clutch device design that includes a center clutch with a cylindrical pressure clutch slide portion and a lifter plate, where the clearance between the second center clutch slide portion and the pressure clutch slide portion is greater than the clearance between the first center clutch slide portion and the lifter plate slide portion, allowing for improved close contactability and stabilization of torque transmission through assist and slipper cam surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the pressure member and clutch member are fitted together with tight clearances to improve precision, then manufacturing precision is improved, but fitting accuracy deteriorates due to cumulative errors and tilting

Engineering Contradiction:
Improveclearance controlVSAvoidfitting accuracy
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The clutch assembly is divided into multiple independent sliding pairs: the pressure member slides on the cylindrical portion of the clutch member, while the lifter plate slides on the clutch member at a different location. This segmentation allows each sliding pair to independently accommodate clearance variations without cumulative errors affecting the entire assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lifter plate acts as an intermediary element between the pressure member and the clutch member. By providing a separate sliding interface, it mediates the clearance relationships and prevents direct transmission of clearance errors from the pressure member to the cam surface contact point.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If the pressure member is tightly fitted to the clutch member to reduce clearance, then manufacturing precision is improved, but the cam surfaces tilt and close contactability deteriorates

Engineering Contradiction:
Improveclearance controlVSAvoidclose contactability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The sliding function is segmented into two independent locations: one at the pressure member-clutch member interface and another at the lifter plate-clutch member interface. This segmentation ensures that clearance variations at one location do not directly cause tilting at the cam surface contact location.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The solution moves from a single-dimensional clearance control (pressure member to clutch member) to a two-dimensional clearance distribution system (pressure member to clutch member, and lifter plate to clutch member). This dimensional expansion allows independent optimization of each interface.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Device complexity

If the pressure member slides directly on the clutch member to transmit force, then device complexity is reduced, but torque transmission stability deteriorates due to tilting

Engineering Contradiction:
Improvestructure simplicityVSAvoidtorque transmission stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The lifter plate serves as an intermediary component that transmits axial force from the pressure member to the clutch member while providing a separate sliding interface. This intermediary structure stabilizes torque transmission by preventing direct tilting between the pressure member and clutch member cam surfaces.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The lifter plate performs multiple functions: it transmits axial force, provides a sliding interface to accommodate clearance variations, and stabilizes the cam surface contact. This multi-functionality maintains torque transmission stability without significantly increasing device complexity.

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

This configuration enhances the close contactability between cam surfaces, stabilizes torque transmission, and allows for effective cooling of the clutch plates, ensuring reliable and efficient power transfer between the drive shaft and the driven shaft.

Implementation Method 1

three cam surfaces formed at the pressure member move over three cam surfaces formed at the clutch member in a state in which the pressure member has slid in each of a rotation direction and an axial direction relative to the clutch member

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3767121B1Clutch device
Publication Date: 2023.01.11 FCC KK
  • EP3767121B1 patent drawingFigure 1
  • EP3767121B1 patent drawingFigure 2
  • EP3767121B1 patent drawingFigure 3~4

AI summary

Provided is a clutch device configured so that close contactability between a cam surface of a center clutch and a cam surface of a pressure clutch can be improved and torque transmission can be stabilized accordingly. The clutch device (100) includes a center clutch (105) and a pressure clutch (112). The center clutch (105) includes center-side cam portions (107), a pressure clutch slide portion (106), and a lifter plate slide portion (110). The pressure clutch (112) includes pressure-side cam portions (114), a lifter plate (116), and a second center clutch slide portion (113). The lifter plate (116) includes first center clutch slide portions (120). A clearance (C2) between the second center clutch slide portion (113) and the pressure clutch slide portion (106) is set greater than a clearance (C1) between the first center clutch slide portion (120) and the lifter plate slide portion (110).