Locking Differential Cam Assembly Axial Disengagement

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Solution Overview

Problem

Existing locking differentials are mechanically complex, costly, and generate noise and vibration due to the interaction between cam teeth and driven teeth during speed differentials between axle half shafts.

Innovation Solution

A locking differential mechanism with a pair of side gears, a central driver, and a cam assembly featuring opposed annular faces with drive teeth, and clutch members with driven teeth, where the cam assembly moves clutch members axially to disengage from the central driver when speed differentials occur, reducing internal wear and noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the driven teeth on the clutch member are designed to remain in meshing engagement with the drive teeth on the central driver, then torque transmission is maintained, but noise and vibration are generated during speed differentials due to interaction with cam teeth

Engineering Contradiction:
Improvetorque transmissionVSAvoidnoise and vibration
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the camming action from the driven teeth of the clutch member, dedicating those teeth solely to meshing engagement with the drive teeth for torque transmission. The camming function is instead performed by separate cam surfaces on the cam member that act on the clutch member body, not on the driven teeth. This separation eliminates the harmful interaction between cam teeth and driven teeth that causes noise and vibration during speed differentials.

Inventive Principle:
Principle #2Taking out (Extraction)

2Adaptability or versatility

If a traditional locking differential mechanism with cam members and clutch members is used, then speed differentials are accommodated, but the device becomes mechanically complex and costly to manufacture

Engineering Contradiction:
Improvespeed differential accommodationVSAvoidmechanical complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the cam member and clutch member into a single integrated component. The clutch member includes both the driven teeth for torque transmission and cam surfaces for speed differential accommodation. This integration eliminates the need for separate cam members and clutch members, reducing the number of parts and simplifying the overall mechanism while maintaining the ability to accommodate speed differentials.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated clutch member performs multiple functions: it transmits torque through its driven teeth that mesh with the drive teeth, and it accommodates speed differentials through its cam surfaces that interact with the cam member. This multi-functional design reduces the number of components needed and simplifies the mechanism while maintaining adaptability to different operating conditions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of operation

If the cam teeth and driven teeth interact during speed differentials, then the clutch can disengage from the central driver, but internal wear increases and operational smoothness decreases

Engineering Contradiction:
Improveclutch disengagementVSAvoidinternal wear
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent extracts the camming action from the driven teeth, dedicating them solely to torque transmission through meshing engagement. The cam surfaces are provided separately on the clutch member body, not on the driven teeth. This separation ensures that the driven teeth remain in continuous meshing engagement with the drive teeth, eliminating wear from disengagement and re-engagement while maintaining smooth operation during speed differentials.

Inventive Principle:
Principle #2Taking out (Extraction)

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 results in a mechanically efficient, cost-effective locking differential with reduced noise and vibration, allowing axle half shafts to rotate at different speeds without re-engaging unnecessarily, thus preventing damage and improving operational smoothness.

Implementation Method 1

a cam assembly having a pair of opposed cam members. Each of the cam members is mounted for rotation with a corresponding one of the pair of side gears and is disposed in abutting contact with a corresponding one of the pair of clutch members. Each of the pair of opposed cam members includes a plurality of camming teeth extending toward the corresponding teeth on the opposed cam member.

Methodology Applied
Scientific EffectCamming action: Cam

Data Source

PatentEP2425154B1Locking differential
Publication Date: 2016.05.25 EATON CORP
  • EP2425154B1 patent drawingFigure 1
  • EP2425154B1 patent drawingFigure 2
  • EP2425154B1 patent drawingFigure 3

AI summary

A locking differential mechanism (12) for supplying torque from a driveshaft to a pair of aligned output shafts (26, 28) including a pair of side gears (34, 36), a central driver (52), and a pair of clutch members (62, 64) operatively coupled for rotation with the corresponding one of the pair of side gears (34, 36). A cam assembly (78) includes a pair of cam members (80, 82). Each of the pair of cam members (80, 82) includes a plurality of camming teeth (88, 90) extending toward the corresponding teeth on the opposed cam member. Each of the cam members (80, 82) is movable from a first position where the cam teeth (88, 90) are disposed in meshing relationship with respect to each other when the pair of side gears (34, 36), are rotating at substantially the same speed and a second position spaced axially from the first position along the associated side gear (34, 36) so as to move an associated clutch member (62, 64) from its first position to its second position out of driven relationship with the central driver (52) in response to a difference in rotational speed of the associated pair of side gears (34, 36).