Switchable Ratcheting Clutch with Bidirectional Tipping Pawls

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Solution Overview

Problem

Known ratcheting clutches require separate ratcheting elements for each circumferential direction, increasing size, complexity, and cost, and are limited to providing ratcheting function in only one direction.

Innovation Solution

A switchable ratcheting clutch design that uses the same sets of pawls and resilient elements to enable rotation in three modes: a free-wheel mode and two one-way modes by adjusting the position of a cage and resilient elements to engage pawls with the outer race in different circumferential directions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate ratcheting elements are used for each circumferential direction, then bidirectional ratcheting function is achieved, but device complexity and parts count increase

Engineering Contradiction:

Improvebidirectional ratcheting functionVSAvoidparts count

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The pawl is designed with dual functionality to provide ratcheting in both circumferential directions. By incorporating two protrusions on the pawl that can engage with the outer race in opposite directions, a single pawl component replaces what would traditionally require two separate pawls, thereby achieving bidirectional ratcheting while reducing parts count

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The resilient element is made movable relative to the cage, allowing it to dynamically switch between engaging the first protrusion and the second protrusion of the pawl. This dynamic repositioning enables the same pawl to function in different ratcheting directions based on the resilient element's position, achieving versatility without increasing permanent parts

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If separate ratcheting elements are used for each circumferential direction, then bidirectional ratcheting function is achieved, but manufacturing cost increases

Engineering Contradiction:

Improvebidirectional ratcheting functionVSAvoidproduction cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Multiple ratcheting functions are merged into a single pawl component. Instead of manufacturing separate pawls for each direction, the invention combines both ratcheting directions into one pawl with two protrusions, reducing the total number of parts that need to be manufactured, inventoried, and assembled, thereby lowering production costs

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If separate ratcheting elements are used for each circumferential direction, then bidirectional ratcheting function is achieved, but clutch size increases

Engineering Contradiction:

Improvebidirectional ratcheting functionVSAvoidclutch size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The resilient element serves multiple functions by being repositionable along the pawl. The same resilient element engages different protrusions on the pawl to control ratcheting in opposite directions, eliminating the need for additional resilient elements and reducing the overall volume required for bidirectional functionality

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 design reduces parts count, complexity, and production costs while enabling bidirectional ratcheting functionality using the same components, thus overcoming the limitations of existing clutches.

Implementation Method 1

a resilient element fixed to the cage and in contact with the pawl... the resilient element urges the pawl into contact with the outer race

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

the cage is arranged to be circumferentially displaced, by an actuator, to slide the resilient element along the pawl

Methodology Applied

Scientific EffectMechanical displacement: Displacement

Data Source

PatentUS11187284B2Switchable ratcheting clutch with tipping pawls

Publication Date: 2021.11.30 SCHAEFFLER TECHNOLOGIES AG & CO KG

AI summary

A clutch including: an inner race forming a pocket; an outer race located radially outward of the inner race; a pawl including a portion disposed in the pocket; a cage rotatable by an actuator to a circumferential position with respect to the pawl; and a resilient element fixed to the cage and in contact with the pawl. The inner or outer race is supported for rotation about an axis of rotation. In a first one-way mode: the cage is in the circumferential position; the inner race is relatively rotatable, with respect to the outer race, only in a first circumferential direction; and the resilient element urges the pawl into contact with the outer race. In a second one-way mode: the inner race is relatively rotatable, with respect to the outer race, only in a second circumferential direction; and the resilient element urges the pawl into contact with the outer race.