Multi-Material Solenoid Plunger for Reliable Differential Locking

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Solution Overview

Problem

Existing vehicle differential locking mechanisms fail to reliably engage and disengage the locking mechanism due to misalignment or failure to couple properly, leading to inconsistent torque application across wheels with different traction conditions.

Innovation Solution

A drive member, or plunger, formed from multiple materials, including a magnetically responsive material and a non-responsive material, is designed to move axially in response to a magnetic field, ensuring reliable actuation by coupling the plunger and lock member together to prevent relative movement and facilitate proper engagement with the differential gears.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a plunger is made from a single magnetic material, then it responds well to magnetic fields, but it allows relative axial movement between parts leading to unreliable locking mechanism engagement

Engineering Contradiction:
Improvereliable actuation of locking mechanismVSAvoidsingle-material construction
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The plunger is constructed from multiple materials: a magnetically responsive material (such as steel) and a non-magnetic material (such as plastic or polymer). This composite construction allows the plunger to respond to magnetic fields while the non-magnetic material provides structural support and prevents relative axial movement between the plunger and lock member, thereby ensuring reliable engagement of the locking mechanism.

Inventive Principle:
Principle #40Composite materials

2Reliability

If the plunger and lock member are not properly coupled, then the structure is simpler, but relative axial movement occurs causing misalignment and failure to engage

Engineering Contradiction:
Improveproper engagement of locking mechanismVSAvoidcoupling structure between plunger and lock member
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The plunger and lock member are merged into a single integrated component where the non-magnetic material of the plunger directly contacts and couples with the lock member. This merging eliminates relative axial movement between the two parts and ensures proper alignment and engagement of the locking mechanism without requiring additional coupling structures.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If a press-fit construction is used for the plunger, then assembly is simplified, but misalignment occurs leading to inconsistent torque application

Engineering Contradiction:
Improveassembly processVSAvoidalignment of plunger components
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The use of a non-magnetic material (such as plastic or polymer) in the plunger construction provides inherent alignment features and tolerance compensation that maintain precise alignment between plunger components during press-fit assembly. This composite construction allows for easier assembly while maintaining manufacturing precision and consistent torque application.

Inventive Principle:
Principle #40Composite materials

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 ensures consistent and reliable locking and unlocking of the differential, improving torque distribution across wheels by preventing relative axial movement between the plunger and lock member, enhancing vehicle performance on varying traction surfaces.

Implementation Method 1

A drive member, or plunger, formed from multiple materials, including a magnetically responsive material and a non-responsive material, is designed to move axially in response to a magnetic field

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

a first body formed at least partially from a first material that is magnetically responsive

Methodology Applied
Scientific EffectMagnetic response: Magnetism

Data Source

PatentEP3615847B1Multiple material solenoid actuator plunger
Publication Date: 2024.04.10 GKN AUTOMOTIVE LTD
  • EP3615847B1 patent drawingFigure 1~2
  • EP3615847B1 patent drawingFigure 3~9
  • EP3615847B1 patent drawingFigure 4~5

AI summary

In at least some implementations, a system for a vehicle differential that has multiple gears may include a coil, a drive member movable in response to a magnetic field generated by application of electricity to the coil and a lock member driven by the drive member to selectively engage a gear of the differential. The drive member is movable between a first position and a second position, has an axis and includes a first body formed at least partially from a first material that is magnetically responsive and a second body formed at least partially from a second material. The first body and second body are coupled together and overlapped in two opposing axial directions to limit or prevent relative axial movement between the first body and the second body.