Electronic Locking Differential with Direct State Detection

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Solution Overview

Problem

Existing electronic locking differentials in axle assemblies are susceptible to improvements in terms of operational efficiency and reliability, particularly in ensuring secure engagement of locking mechanisms.

Innovation Solution

The axle assembly incorporates a locking device with a first and second dog ring, a return spring, a thrust member, and an actuator, where the actuator moves the thrust member to engage the teeth of the dog rings, inhibiting relative rotation between the second side gear and the differential case, thereby enhancing locking stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an electromagnetic actuator is used to couple the side gear to the differential case, then the differential can operate in a fully locked condition, but the system becomes susceptible to reliability issues in ensuring secure engagement of the locking mechanism

Engineering Contradiction:
Improvesecure engagement of locking mechanismVSAvoidlocking mechanism structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A sensor detects the position of the plunger and generates a sensor position signal. When the plunger is in the retracted position, the sensor signal indicates that the locking dogs are engaged, providing feedback confirmation of the locked state to the control system.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

A plunger acts as an intermediary component between the electromagnetic actuator and the locking dogs. The plunger translates the electromagnetic actuator's motion into precise engagement of the locking dogs with the dogs in the side gear, ensuring reliable locking while simplifying the overall mechanism.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the actuator moves the plunger to push the thrust member and second dog toward the first dog, then the teeth and mating teeth engage to inhibit relative rotation, but the device complexity increases

Engineering Contradiction:
Improvelocking stabilityVSAvoidlocking device structure
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The plunger, thrust member, and second dog are fixedly coupled to one another, merging these components into a single integrated assembly. This reduces the number of separate parts and simplifies the locking device structure while maintaining stable locking through the engaged teeth of the dogs.

Inventive Principle:
Principle #5Merging (Combining)

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 configuration ensures robust locking of the differential assembly, preventing speed differentiation between axle shafts and improving operational reliability by ensuring secure engagement of the locking mechanism.

Implementation Method 1

The return spring biases at least one of the first and second dogs in a direction so that the teeth and the mating teeth are not engaged to one another

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

The actuator is operable in a returned position, which permits the return spring to maintain the teeth and the mating teeth in a de-coupled condition, and an extended position in which the actuator moves the plunger to push the thrust member and the second dog toward the first dog

Methodology Applied
Scientific EffectElectromagnetic actuator: Electromagnet

Data Source

PatentEP2111346B1Electronic locking differential with direct locking state detection system
Publication Date: 2014.10.22 AMERICAN AXLE & MANUFACTURING INC
  • EP2111346B1 patent drawingFigure 1
  • EP2111346B1 patent drawingFigure 2
  • EP2111346B1 patent drawingFigure 3

AI summary

An axle assembly with an electronic locking differential that employs a locking mechanism having components that are fixed to one another along an axis such that they co-translate with one another when the actuator that effects the locking and unlocking of the differential is operated. A method for assembling a differential is also provided.