Differential Lock Timing Buffers for Wheel Slip Control

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Solution Overview

Problem

Existing methods of controlling differential locks in vehicles fail to accurately detect wheel slip and synchronize axle shafts for effective traction, leading to unnecessary engagement or disengagement, which affects vehicle drivability and component wear.

Innovation Solution

A method that uses pre-activation and differential lock engagement buffers based on wheel and vehicle speed to delay and synchronize the actuation of the differential lock, ensuring accurate detection and engagement only when necessary, thereby improving traction and reducing wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the differential lock is actuated immediately when wheel slip is detected, then traction is improved, but unnecessary engagement occurs leading to increased component wear and reduced drivability

Engineering Contradiction:
ImprovetractionVSAvoidcomponent wear
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The system performs preliminary monitoring of wheel slip conditions and calculates required buffer time before actuating the differential lock. This preliminary action allows the system to prepare for engagement only when conditions are favorable, preventing unnecessary wear while maintaining traction when needed.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The buffer time for differential lock actuation is dynamically adjusted based on real-time vehicle operating conditions including acceleration, wheel speed, and slip duration. This dynamic adjustment ensures engagement occurs at optimal moments, reducing unnecessary wear while maintaining effective traction control.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the differential lock is actuated immediately when wheel slip is detected, then traction is improved, but drivability is reduced due to frequent engagement and disengagement

Engineering Contradiction:
ImprovetractionVSAvoiddrivability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system monitors wheel slip conditions and calculates buffer time in advance before actuating the differential lock. This preliminary monitoring and calculation prevents premature engagement, reducing frequent on/off cycling that degrades drivability while maintaining effective traction when truly needed.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The actuation timing is dynamically optimized by adjusting buffer time based on acceleration and wheel speed conditions. This dynamic approach smooths engagement timing, reducing drivability issues caused by abrupt or unnecessary lock activation while maintaining traction effectiveness.

Inventive Principle:
Principle #15Dynamics

3Object-generated harmful factors

If the differential lock engagement buffer is increased to reduce unnecessary engagement, then component wear is reduced, but the response time for effective traction control increases

Engineering Contradiction:
Improvecomponent wearVSAvoidresponse time
Core Design Contradiction:
Object-generated harmful factorsVSLoss of time

Solution Approach 1:

The engagement buffer time is dynamically adjusted based on real-time conditions including acceleration and wheel speed. This dynamic adjustment optimizes the balance between reducing unnecessary wear and maintaining adequate response time for effective traction control, as the buffer is longer when conditions warrant caution and shorter when rapid response is needed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the buffer time parameter based on operating conditions such as acceleration and wheel speed. This parameter adjustment allows the system to minimize component wear by avoiding unnecessary engagement while maintaining adequate response time when genuine wheel slip requires correction.

Inventive Principle:
Principle #35Parameter changes

4Measurement precision

If wheel slip detection threshold is lowered to improve detection accuracy, then false positives increase leading to unnecessary differential lock actuation

Engineering Contradiction:
Improvewheel slip detection accuracyVSAvoidfalse positive rate
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary monitoring of wheel slip conditions over a calculated buffer period before actuating the differential lock. This preliminary monitoring filters out transient or false slip signals while maintaining detection sensitivity, reducing false positives without compromising detection accuracy for genuine wheel slip conditions.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from continuous monitoring of wheel speed and acceleration to validate detected wheel slip conditions before actuation. This feedback mechanism distinguishes between genuine wheel slip requiring correction and false positives, maintaining detection accuracy while reducing unnecessary engagement.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4342708B1Method of controlling a differential lock
Publication Date: 2025.09.03 ARVINMERITOR TECHNOLOGY LLC
  • EP4342708B1 patent drawingFigure 1
  • EP4342708B1 patent drawingFigure 2
  • EP4342708B1 patent drawingFigure 3

AI summary

A method of controlling a differential lock. The differential lock is actuated to lock a differential assembly when wheel slip of a first wheel assembly is detected and a duration of the wheel slip exceeds a pre-activation buffer. The pre-activation buffer is based on acceleration of the first wheel assembly and vehicle speed.