Differential Assembly Jaw Clutch for Compact Locking Engagement

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Solution Overview

Problem

Existing vehicular differential assemblies with locking mechanisms are complex and require dedicated actuators, leading to increased component count and reduced reliability, especially when attempting to engage the locking mechanism while the vehicle is stationary due to wheel slip conditions.

Innovation Solution

A vehicular differential assembly featuring a frontal jaw clutch with a splined coupling between the planet gear cage and a sleeve element, allowing for a simpler and more compact design with reduced axial stroke requirements for locking, utilizing an actuator that can be commonly sourced and does not need to rotate with the housing, thereby reducing the number of components and improving reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a locking mechanism with multiple clutches and a dedicated actuator is used, then the differential can be locked to prevent wheel slip, but the device complexity and number of components increase significantly

Engineering Contradiction:
Improvedifferential locking reliabilityVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the actuator and the differential housing into a single integrated unit. The actuator is directly mounted on the housing and rotates with it, eliminating the need for separate mounting brackets, additional coupling components, and dedicated actuator designs. This integration reduces the total component count while maintaining the locking function through the clutch mechanism.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The actuator is designed to be a common, universally applicable component that can be mounted on the housing in a customary manner. Instead of requiring a dedicated actuator design, the invention uses a standard actuator that can serve multiple purposes and be integrated with the housing through conventional mounting methods, thereby reducing complexity and component specialization.

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

2Ease of operation

If the actuator is mounted on the outside of the housing to rigidly rotate with it, then the locking mechanism can be actuated, but the actuator requires a dedicated design instead of a common actuator

Engineering Contradiction:
Improvelocking mechanism actuationVSAvoidactuator compatibility
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The actuator is designed to be a common, universally applicable component that can be mounted on the housing in a customary manner. Instead of requiring a dedicated actuator design, the invention uses a standard actuator that can serve multiple purposes and be integrated with the housing through conventional mounting methods, thereby reducing complexity and component specialization.

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

3Reliability

If the clutch is designed to engage with significant force to lock the differential, then wheel slip is prevented, but the force on engaged parts increases requiring longer teeth and more material

Engineering Contradiction:
Improvedifferential locking effectivenessVSAvoidclutch tooth strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention transitions from a radial clutch design to a frontal jaw clutch design. This dimensional change in the clutch engagement geometry allows the locking force to be applied more efficiently through the jaw interface, reducing the bending moments and shear forces on the clutch teeth. As a result, shorter teeth with less material are required while maintaining or improving the locking effectiveness.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 enables efficient locking of the differential without the need for a stationary vehicle, reduces the force on engaged parts, allows for shorter teeth design, and simplifies the coupling process, resulting in a more reliable and compact differential assembly compared to prior art.

Implementation Method 1

a splined coupling between the planet gear cage and a sleeve element, which carries the first clutch portion and is coupled to the planet gear cage in an axially mobile and angularly fixed manner

Methodology Applied
Scientific EffectMechanical coupling: Mechanical Force

Data Source

PatentEP3851705A1Vehicular differential assembly
Publication Date: 2021.07.21 FPT IND SPA
  • EP3851705A1 patent drawingFigure 1
  • EP3851705A1 patent drawingFigure 2
  • EP3851705A1 patent drawingFigure 3

AI summary

A vehicular differential assembly (1) includes a planet gear cage (9) rotatable about an axis (B) and defining an internal cavity, a member (7) arranged inside the cavity in a rotatable manner around the axis (B), a first clutch portion (14) coupled to the planet gear cage (9) in an axially movable and angularly fixed manner, a second clutch portion (15) carried by the member (7) in a fixed position so as to engage with the first clutch portion (14), and an actuator (23) for moving the first clutch portion (14) along the axis (B) between a first position, in which the second clutch portion (15) is spaced from the first clutch portion (14), and a second position, in which the second clutch portion (15) is engaged with the first clutch portion (14).