Electronic Limited Slip Differential Clutch Torque Limiting

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Solution Overview

Problem

Existing drive slip control systems can cause instability and loss of traction in vehicles by transferring excessive torque to high friction coefficient wheels, leading to unwanted oversteer or understeer when these wheels begin to slip, as the systems fail to effectively limit torque and manage wheel slip.

Innovation Solution

A method that processes clutch torque and wheel speed data to determine an electronic limited slip differential clutch torque limit, reducing it by a predetermined ratio when high friction coefficient wheel slip is detected, using a processing system that includes sensors and an electronic control unit to adjust torque distribution dynamically.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If braking intervention is applied to the low μ wheel to control drive slip, then traction on the low μ wheel is improved, but torque transfer to the high μ wheel causes it to slip, resulting in loss of vehicle stability and lateral stability

Engineering Contradiction:
Improvetraction control effectivenessVSAvoidvehicle stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The system continuously monitors wheel slip conditions and dynamically adjusts clutch torque limits based on real-time feedback from wheel speed sensors and slip calculations. When high μ wheel slip is detected, the system reduces the clutch torque limit by a predetermined ratio, creating a closed-loop control that prevents stability loss while maintaining traction control effectiveness

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system changes the clutch torque parameter dynamically by reducing it to a predetermined ratio when high μ wheel slip is detected. This parameter modification prevents excessive torque transfer to the high μ wheel, thereby avoiding slip-induced instability while maintaining adequate traction control

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If the electronic limited slip differential clutch torque limit is reduced when high μ wheel slip is detected, then vehicle stability is maintained, but torque biasing capability to the high μ wheel is limited

Engineering Contradiction:
Improvevehicle stabilityVSAvoidtorque biasing capability
Core Design Contradiction:
Stability of the object's compositionVSPower

Solution Approach 1:

The clutch torque limit is made dynamic rather than static, allowing the system to adapt torque biasing capability based on real-time wheel slip conditions. The torque limit adjusts automatically - reducing when high μ wheel slip occurs and potentially restoring when slip ceases - thereby maintaining vehicle stability while preserving torque biasing capability when conditions permit

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3922500B1A method for limiting clutch torque to reduce high friction coefficient wheel slip
Publication Date: 2023.03.15 EATON INTELLIGENT POWER LTD
  • EP3922500B1 patent drawingFigure 1
  • EP3922500B1 patent drawingFigure 2A
  • EP3922500B1 patent drawingFigure 2B

AI summary

A method for limiting the amount of torque biased to a high µ wheel of a vehicle comprises processing clutch torque data to determine an electronic limited slip differential clutch torque limit, processing wheel speed data to generate µ slip data, comparing the generated µ slip data to threshold µ slip data. When the generated µ slip data is greater than the threshold µ slip data, the method comprises reducing the electronic limited slip differential clutch torque limit by a predetermined ratio.