Cam Clutch Switching Mechanism for Fast Response and Torque Capacity

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Solution Overview

Problem

Existing two-way clutches face issues with poor responsiveness due to time lost when switching rotation directions and limited torque capacity due to reliance on friction for power transmission.

Innovation Solution

A cam clutch with an operating mode switch mechanism that includes a cam orientation changing part axially movable independently of the inner and outer races, allowing for high responsiveness and secure torque capacity by tilting cams with engaging portions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sprags are tilted in the same direction as the rotation direction of the input-side rotary member, then the clutch can transmit rotary force, but responsiveness deteriorates due to time lost when rotation direction is switched

Engineering Contradiction:

Improverotary force transmissionVSAvoidswitching response time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The cam mechanism dynamically changes orientation based on rotation direction. The cam is tilted in the rotation direction of the inner race, and the operating mode switch mechanism changes the cam's engaged position on the cam surface, allowing the clutch to adaptively respond to direction changes without time loss.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The operating mode switch mechanism preliminarily positions the cam on the cam surface at the appropriate engaged position before direction switching occurs. This pre-positioning eliminates the time delay that would otherwise be required to tilt the cam during direction changes.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If plate spring members are used to allow power transmission in both directions, then bidirectional power transmission is achieved, but torque capacity decreases for the given size due to reliance on friction

Engineering Contradiction:

Improvebidirectional power transmissionVSAvoidtorque capacity

Core Design Contradiction:

Adaptability or versatilityVSForce

Solution Approach 1:

The invention replaces the friction-based plate spring mechanism with a cam-based mechanical system. The cam tilts in the rotation direction and engages with the operating mode switch mechanism, providing positive mechanical engagement instead of friction-based power transmission, thereby increasing torque capacity while maintaining bidirectional operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If the outer race is used as a rotating member, then operational flexibility is improved, but a complex mechanism is required to operate the operating mode switch mechanism from the fixed side

Engineering Contradiction:

Improveoperational flexibilityVSAvoidswitch mechanism complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Instead of operating the switch mechanism from the fixed side as in conventional designs, this invention allows operation from the rotating inner race side. The operating mode switch mechanism is engaged by the inner race through the cam interaction, inverting the conventional approach and simplifying the mechanism when the outer race is used as a rotating member.

Inventive Principle:

Principle #13The other way round (Inversion)

4Speed

If cams of a special shape are used to achieve high responsiveness, then switching speed is improved, but the clutch size increases in the axial direction

Engineering Contradiction:

Improveswitching speedVSAvoidaxial size

Core Design Contradiction:

SpeedVSLength of moving object

Solution Approach 1:

The invention optimizes the cam shape parameters to achieve high switching responsiveness. The cam has a specific profile that allows rapid engagement and disengagement when tilted, achieving fast switching without requiring excessive axial length. The biasing means also applies optimal force to facilitate quick cam repositioning.

Inventive Principle:

Principle #35Parameter changes

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 solution achieves high responsiveness in switching operating modes and secures a desired torque capacity without limitations from frictional forces, while allowing the outer race to be used as a rotating member without a complex structure and minimizing axial size increase.

Implementation Method 1

a biasing means radially biasing the plurality of cams

Methodology Applied

Scientific EffectElastic force: Elasticity

Implementation Method 2

Some or all of the plurality of cams include an engaging portion protruding from a side face toward the cam orientation changing part

Methodology Applied

Scientific EffectMechanical tilting: Mechanical Force

Data Source

PatentUS12253121B2Cam clutch

Publication Date: 2025.03.18 TSUBAKIMOTO CHAIN CO

AI summary

To provide a cam clutch that allows use of the outer race as a rotating member without requiring a complex structure, and that allows a size reduction in the axial direction. The cam clutch includes an operating mode switch mechanism (140) for switching between two or more of a free state that allows relative rotation in both directions, a one-way clutch mode that allows relative rotation in one of forward and reverse directions, and a locked state that prohibits relative rotation in both directions. The operating mode switch mechanism (140) includes a cam orientation changing part (141) axially movable independently of rotation of the inner race (110) and the outer race (120). A plurality of cams (131) include an engaging portion (136) protruding from a side face toward the cam orientation changing part (141).