Reverse Input Blocking Clutch With Elastic Gap Compensation

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Solution Overview

Problem

The reverse input blocking clutch experiences looseness in the output member due to gaps between the output-side engaging portion and the output-side engaged portion, leading to positional deviations and abnormal noise, especially when connected to screw shafts or used for adjusting stages or steering angles.

Innovation Solution

A reverse input blocking clutch design incorporating an elastic member that is elastically stretched between the output-side engaging portion and the engaging element, allowing for frictional engagement with the pressed surface to prevent looseness and ensure torque transmission, featuring a plate spring or coil spring configuration to maintain contact and reduce parts and installation space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If gaps are provided between the output-side engaging portion and the output-side engaged portion for assembly workability, then the ease of manufacture is improved, but the looseness of the output member increases causing positional deviations and abnormal noise

Engineering Contradiction:
Improveassembly workabilityVSAvoidlooseness suppression
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

An elastic member is introduced as an intermediary element between the output-side engaging portion and the engaging element. This elastic member fills the gap that exists for assembly workability while maintaining continuous contact and preventing looseness. The elastic member deforms elastically to accommodate the gap during assembly but maintains sufficient contact pressure to prevent abnormal noise and positional deviations during operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Power

If the engaging element is moved away from the pressed surface for torque transmission, then the power transmission is improved, but the frictional engagement with the pressed surface is reduced

Engineering Contradiction:
Improvetorque transmissionVSAvoidfrictional engagement force
Core Design Contradiction:
PowerVSForce

Solution Approach 1:

The engaging element is designed to dynamically adjust its position between the pressed surface and the output-side engaging portion based on the operating state. During torque transmission, the engaging element moves away from the pressed surface to engage with the output-side engaging portion. During reverse input blocking, the elastic member pushes the engaging element toward the pressed surface to maintain frictional engagement. This dynamic positioning resolves the contradiction between torque transmission and frictional engagement.

Inventive Principle:
Principle #15Dynamics

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 elastic member effectively suppresses looseness in the output member, preventing positional deviations and abnormal noise, while reducing manufacturing costs and part count, and enabling smooth switching between locked, semi-locked, and unlocked states.

Implementation Method 1

an elastic member that is elastically stretched between the output-side engaging portion and the engaging element

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the pressing surface is pressed against the pressed surface so as to frictionally engage the pressing surface with the pressed surface

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4006371B1Reverse input blocking clutch
Publication Date: 2023.06.14 NSK LTD
  • EP4006371B1 patent drawingFigure 1
  • EP4006371B1 patent drawingFigure 2
  • EP4006371B1 patent drawingFigure 3

AI summary

[Problem] To realize a reverse input blocking clutch capable of suppressing looseness of an output member. [Solution] The reverse input blocking clutch has a pressed member having a pressed surface 20 on the inner circumferential surface; an input member that has an input-side engaging portion 8 arranged on the inner side in the radial direction of the pressed surface 20, and is coaxially arranged with the pressed surface 20; an output member that has an output-side engaging portion 11 arranged further on the inner side in the radial direction than the input-side engaging portion 8 on the inner side in the radial direction of the pressed surface 20, and is coaxially arranged with the pressed surface 20; an engaging element 5 arranged on the inner side in the radial direction of the pressed surface 20 so as to be able to move in a first direction which is a far-near direction with respect to the pressed surface 20; and an elastic member 56 arranged at a position overlapping the output-side engaging portion 11 with respect to the first direction so as to be elastically stretched between the output-side engaging portion 11 and the engaging element 5.