Reverse Input Cutoff Clutch Structure for Easy Lock Release

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Solution Overview

Problem

The reverse input cutoff clutch described in JP 2007-232095A faces difficulties in releasing the state where the output member is prevented from rotating due to large meshing forces when rotational torque is reversely input, making it challenging to release the locked state.

Innovation Solution

A reverse input cutoff clutch design featuring a pair of engaging elements with specific geometric configurations, including input-side and output-side engaging portions, and a pressed member, where the engaging elements move radially to transmit or block torque, allowing easy release of the locked or half-locked state by controlling the force relationship between the input and output members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If rolling elements are meshed into a narrow-width portion of a wedge-shaped space to block reverse torque, then the output member is effectively prevented from rotating, but the locking state becomes difficult to release when large meshing forces are generated

Engineering Contradiction:
Improveblocking effectivenessVSAvoidrelease ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

A pressed member is introduced as an intermediary element between the rolling elements and the output member. The pressed member applies a pressing force to the rolling elements, enabling reliable blocking of reverse torque while providing a controlled mechanism for release. This mediator allows the system to achieve both strong locking and easy release by controlling the pressing force application.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The pressing force parameter applied to the rolling elements is made controllable and adjustable. By changing the magnitude of the pressing force, the system can transition between different operational states (locked, released). This parameter control enables the rolling elements to be firmly held during blocking while allowing easy release when the pressing force is reduced or removed.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the pressing force on rolling elements is increased to improve blocking reliability, then reverse torque blocking is enhanced, but the force required to release the locking state increases

Engineering Contradiction:
Improveblocking reliabilityVSAvoidrelease force
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The pressed member serves as a controllable intermediary that applies pressing force to the rolling elements. This intermediary mechanism allows the pressing force to be applied in a controlled manner, enabling reliable blocking while providing a straightforward method for release by simply controlling the pressing force magnitude. The pressed member decouples the blocking force requirement from the release force requirement.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables stable switching between locked, half-locked, and unlocked states, preventing the engaging elements from being stuck in the narrow portion, thus facilitating easy release of the output member's rotation prevention state.

Implementation Method 1

a pressed member that presses the engaging elements in a first direction toward the pressed member with a pressing force

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3981997B1Reverse input cutoff clutch
Publication Date: 2023.06.28 NSK LTD
  • EP3981997B1 patent drawingFigure 1
  • EP3981997B1 patent drawingFigure 2
  • EP3981997B1 patent drawingFigure 3

AI summary

Provided is a structure of a reverse input cutoff clutch capable of easily releasing the state in which the rotation of the output member is prevented or suppressed. The reverse input cutoff clutch comprises a pressed member 4 having a pressed surface 10, an input member 2 arranged coaxially with the pressed surface 10 and having an input-side engaging portion 7 arranged radially inside the pressed surface 10, an output member 3 arranged coaxially with the pressed surface 10 and having an output-side engaging portion 9 arranged more radially inside than the input-side engaging portion 7, and an engaging element 5 arranged radially inside the pressed surface 10 and having a pressing surface 11 facing the pressed surface 10, an input-side engaged portion 14 that engages with the input-side engaging portions 7, and an output-side engaged portion 15 that engages with the output-side engaging portion 9. The output-side engaged portion 15 is configured by a recessed portion, and the interior surface of the recessed portion has a pair of guided surfaces 19. The output-side engaging portion 9 has a pair of guide surfaces 17 facing the pair of guided surfaces 19.