Switchable Ratchet Clutch Meshing Geometry for Stable One-Way Rotation

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Solution Overview

Problem

Stabilizing the behavior of a ratchet mechanism in a switchable ratchet type clutch device when the outer ring rotates freely with respect to the inner ring in the one-way torque transmission state is crucial for improving the durability of the clutch device.

Innovation Solution

The clutch device includes a first ring and a second ring, with first and second claw members oscillatable along a plane perpendicular to the axial direction. Biasing members are used to maintain contact between the claw members and the first ring, and a switching mechanism controls the state of the claw members between locked, one-way, and free states. The meshing portions on the first ring have inclined surfaces that stabilize the claw members during one-way torque transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the clutch device operates in one-way torque transmission state with conventional meshing portions, then torque transmission function is achieved, but the claw members exhibit violent movement and unstable behavior reducing durability

Engineering Contradiction:
ImprovedurabilityVSAvoidbehavior stability of claw members
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The meshing portions are designed with asymmetric surfaces where the first surface has a different inclination angle relative to the radial direction than the second surface. Specifically, the first surface is inclined at a first angle while the second surface is inclined at a second angle that is different from the first angle, creating asymmetric contact geometry that stabilizes claw member behavior during one-way torque transmission

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The invention changes the geometric parameters of the meshing portions by defining specific inclination angles for the first and second surfaces relative to the radial direction. By optimizing these angular parameters, the claw members maintain stable contact with the meshing portions during free rotation, preventing violent movement and improving durability

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If the outer ring rotates freely with respect to the inner ring in one-way state, then torque transmission in one direction is achieved, but the ratchet mechanism behavior becomes unstable

Engineering Contradiction:
Improvefree rotation capabilityVSAvoidratchet mechanism behavior
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The asymmetric design of meshing portions with different inclination angles for the first and second surfaces creates differential contact characteristics that stabilize claw member behavior specifically during free rotation in the one-way state, while maintaining the desired free rotation capability

Inventive Principle:
Principle #4Asymmetry

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 stabilizes the behavior of the claw members during one-way torque transmission, reducing violent movement and enhancing the durability of the clutch device.

Implementation Method 1

a plurality of first biasing members supported by the second ring, and biasing the plurality of first claw members such that the first end portion comes into contact with the first ring

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4382761B1Clutch device
Publication Date: 2025.05.14 NSK WARNER
  • EP4382761B1 patent drawingFigure 1
  • EP4382761B1 patent drawingFigure 2
  • EP4382761B1 patent drawingFigure 3

AI summary

A clutch device includes: a first ring; a second ring; a plurality of first claw members; a plurality of second claw members; a plurality of first biasing members; a plurality of second biasing members; and a switching mechanism. The first ring includes a plurality of meshing portions. Each of the plurality of meshing portions has a first surface, a second surface, and a third surface. The first surface faces the other side in a circumferential direction to come into contact with a first end portion in a locked state. The second surface faces one side in the circumferential direction to come into contact with a second end portion in the locked state. The third surface faces a second ring side between the first surface and the second surface, and is inclined to approach the second ring as the third surface approaches the first surface.