Active Differential Clutch Separation for Torque Load Protection

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Solution Overview

Problem

Active differentials in motor vehicles experience high loads that reduce the lifespan of mechanical and electrical components due to large speed and torque differences between output shafts, leading to potential damage and reduced service life.

Innovation Solution

A separable clutch device in the active differential separates the distribution shaft from the planetary gear when predetermined limit values of speed or torque differences are exceeded, allowing for controlled torque distribution and reducing high loads on components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the active differential operates without a separable clutch device to maintain continuous torque distribution control, then the adaptability and torque distribution flexibility are improved, but the reliability and service life of components deteriorate due to excessive loads during high speed or torque difference conditions

Engineering Contradiction:
Improvetorque distribution flexibilityVSAvoidcomponent service life
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The clutch device is segmented into separable coupling and decoupling components that can disconnect the distribution shaft from the planetary gear when limit values are exceeded. This segmentation allows the system to switch between active torque distribution mode and passive differential mode, protecting components from excessive loads while maintaining adaptability during normal operation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The clutch device dynamically transitions between connected and disconnected states based on real-time monitoring of speed and torque differences. This dynamic adaptation allows the system to optimize between continuous torque distribution control during normal operation and component protection during extreme conditions, resolving the contradiction between adaptability and reliability

Inventive Principle:
Principle #15Dynamics

2Power

If the distribution shaft operates at high speeds to achieve large torque differences between output shafts, then the torque distribution capability is improved, but the mechanical stress and potential damage to the distribution motor increase

Engineering Contradiction:
Improvetorque distribution capabilityVSAvoiddistribution motor durability
Core Design Contradiction:
PowerVSStrength

Solution Approach 1:

The clutch device is designed with preliminary protective measures that detect approaching limit values of speed or torque differences and disconnect the distribution shaft from the planetary gear before excessive speeds are reached. This preliminary anti-action prevents mechanical stress and potential damage to the distribution motor while preserving the torque distribution capability during safe operating ranges

Inventive Principle:
Principle #9Preliminary anti-action

3Reliability

If the clutch device is designed to separate automatically when limit values are exceeded, then the reliability and component protection are improved, but the device complexity increases due to additional sensors and control mechanisms

Engineering Contradiction:
Improvecomponent protectionVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The clutch device is designed as a self-service system that automatically monitors operating parameters through integrated sensors and actuates separation when predetermined limit values are exceeded. This self-service capability provides reliable component protection without requiring complex external control systems, resolving the contradiction between reliability and device complexity

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3074260B1Active differential and motor vehicle
Publication Date: 2021.01.20 AUDI AG
  • EP3074260B1 patent drawingFigure 1~3

AI summary

An active differential for the controlled distribution of a drive torque generated by a drive motor to two output shafts includes a planetary gear train configured to couple the two drive shafts to a drive shaft of the drive motor, and a distributor motor including a distributor shaft. The distributor motor produces a torque, with a distribution of a drive torque to the two output shafts being dependent on the torque produced by the distributor motor. The distributor shaft and the planetary gear train are coupled by a coupling device which is configured to separate the distributor shaft from the planetary gear train when an operating parameter of the active differential exceeds a predetermined limit value. The operating parameter can hereby be an output torque difference between torques transmitted from the output shafts to the planetary gear train or a time derivative of the output torque difference.