Differential Backup Input Mechanism for Wheel Slip Prevention

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Solution Overview

Problem

Conventional moveable power tools experience wheel slip when a single power source input fails, leading to ineffective movement transfer due to the inability of axles to rotate independently.

Innovation Solution

A differential mechanism with a main and auxiliary input end, allowing power input to an output component, ensuring continued rotation through engagement of the auxiliary input end when the main input fails, reducing slippage and enhancing stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single power source input is used for the differential, then the device complexity is reduced, but the reliability deteriorates when the power input fails causing wheel slip

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The power input mechanism is segmented into a main power input end and an auxiliary power input end. The main power input end includes a main input gear that meshes with the output gear, while the auxiliary power input end includes an auxiliary input gear that can also mesh with the output gear. This segmentation allows the system to have multiple independent power input paths, improving reliability without significantly increasing overall device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The auxiliary power input end is pre-configured and positioned to engage with the output gear before any failure occurs. When the main power input fails, the auxiliary input is already in position and can immediately take over without requiring additional activation steps or complex control systems.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a single power input path is used, then the device complexity is minimized, but the stability deteriorates when engagement failure occurs

Engineering Contradiction:
ImprovestabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The output gear serves multiple functions: it can be driven by both the main input gear and the auxiliary input gear. This multi-functionality allows the single output gear to receive power from either input source, providing stability through redundancy while maintaining relatively simple device architecture.

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

Solution Approach 2:

The output gear acts as an intermediary component between the two power input ends and the axles. It mediates the power transmission from either the main or auxiliary input to the axles, allowing seamless transition between power sources and ensuring stable operation even when one input path fails.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the main input end and output component engagement fails, then power transmission is interrupted, but adding an auxiliary input end increases device complexity

Engineering Contradiction:
Improvemovement transfer effectivenessVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The main power input end and auxiliary power input end are merged into a single integrated differential structure. Both input gears share the same output gear and are positioned to engage with the same meshing interface, allowing them to function as a unified system with redundant capability rather than separate independent systems.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The auxiliary power input end is designed to automatically engage and take over when the main power input fails. The system self-regulates the power transmission path without requiring external control or intervention, maintaining movement transfer effectiveness while keeping the control mechanism simple.

Inventive Principle:
Principle #25Self-service

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

Guarantees effective and stable movement transfer by maintaining axle rotation, even when primary input fails, thereby minimizing slippage and improving overall operational reliability.

Implementation Method 1

an elastic member is provided at the axial displacement gap, and, when the meshing of the output gear and the input mechanism fails, the output gear squeezes the elastic member so that the first transmission component engages with the second transmission component under an elastic force of the elastic member

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4589172A1Differential and moveable power tool having this differential
Publication Date: 2025.07.23 TECHTRONIC CORDLESS GP
  • EP4589172A1 patent drawingFigure 1A
  • EP4589172A1 patent drawingFigure 1B
  • EP4589172A1 patent drawingFigure 1C

AI summary

The present invention provides a differential and a moveable power tool that has this differential. The differential comprises an input mechanism, an output gear, a first transmission component and a second transmission component. The input mechanism comprises a main input end and an auxiliary input end. When meshing of the output gear and a main input mechanism fails, the first transmission component and the second transmission component engage, and the second transmission component in said engaged state drives the first transmission component to rotate in a predetermined direction, so that the auxiliary input end inputs movement to the output gear. The differential provided by the present invention can guarantee the effectiveness and stability of movement transfer, and reduces the occurrence of slippage.