Overrunning Clutch Drag Assembly for Reverse Motor Lockout

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Solution Overview

Problem

Conventional clutches are unable to operate in all required modes, particularly failing to allow an electric motor to drive wheels in one direction, enable the wheels to overrun the motor in that direction, freewheel relative to the motor in a reverse direction, and prevent reverse rotation of the motor.

Innovation Solution

A clutch assembly with torque transmission members and a drag assembly that engages and disengages based on rotational direction, using a cage to retain the torque transmission members and a rotatable member with a fixed member to limit rotation in the opposite direction, allowing the input member to drive the output member in one direction, enable overrunning, and prevent reverse rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional clutch designs are used, then the structure is simple, but the clutch cannot operate in all required modes (drive in one direction, overrun in that direction, freewheel in reverse, prevent reverse rotation)

Engineering Contradiction:

Improveoperating modesVSAvoidclutch structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The clutch is divided into two independent assemblies: a clutch assembly with torque transmission members for bidirectional torque transfer, and a drag assembly with a rotatable member and fixed member for unidirectional rotation control. This segmentation allows each assembly to specialize in specific functions, achieving four operating modes without requiring a completely complex integrated design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The clutch assembly and drag assembly work together as a unified system to provide multiple operating modes: driving in first direction, overrun in first direction, freewheeling in second direction, and preventing reverse rotation. The drag assembly's rotatable member coupled to the cage provides universal control over the input member's rotation in both directions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If torque transmission members are used to enable bidirectional torque transfer, then the clutch can drive in one direction and overrun in that direction, but the input member cannot be prevented from rotating in the reverse direction

Engineering Contradiction:

Improvetorque transfer controlVSAvoidrotation direction control

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The drag assembly is merged with the clutch assembly by coupling the rotatable member to the cage, which rotates with the input member. This combination allows the fixed member to prevent reverse rotation of the input member while the torque transmission members continue to enable reliable bidirectional torque transfer during driving and overrun conditions.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If the drag assembly limits rotation of the rotatable member in the second direction, then the input member is prevented from rotating in reverse, but this may affect the freewheeling capability of the output member

Engineering Contradiction:

Improvereverse rotation preventionVSAvoidfreewheeling

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The drag control is applied locally to the input member through the rotatable member and fixed member interaction, while the output member maintains its independent freewheeling capability. The torque transmission members allow the output member to freewheel in the second direction by disengaging from the input member, while the drag assembly simultaneously prevents reverse rotation of the input member.

Inventive Principle:

Principle #3Local quality

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 a combination of operating modes where the input member drives the output member in one direction, allows overrunning and freewheeling in the reverse direction, and prevents rotation of the input member in the reverse direction, enhancing the functionality of clutches in applications like electric scooters.

Implementation Method 1

The rotatable member rotates in the first rotational direction about the second axis relative to the fixed member, but rotation of the rotatable member in a second rotational direction, opposite the first rotational direction, about the second axis relative to the fixed member is limited

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12044276B2Disproportional drag actuation of an overrunning clutch

Publication Date: 2024.07.23 WARNER ELECTRIC TECHNOLOGY LLC

AI summary

A clutch includes a clutch assembly having radially spaced input and output members, torque transmission members therebetween, and a cage retaining the torque transmission members. Rotation of the input member relative to the output member in a first direction engages the clutch assembly while rotation of the output member relative to the input member in the first direction disengages the clutch assembly. The clutch further includes a drag assembly including a rotatable member coupled to the cage of the clutch assembly and a fixed member. The rotatable member rotates in the first direction relative to the fixed member, but rotation of the rotatable member in a second direction relative to the fixed member is limited thereby limiting rotation of the input member of the clutch assembly in the second direction.