Integrated Differential Planetary Gear Mechanism for Vehicle Weight Reduction

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Solution Overview

Problem

Existing driving force adjustment apparatuses for vehicles suffer from increased weight and complexity due to separate differential and planetary gear mechanisms, which worsen mountability and weight distribution.

Innovation Solution

A driving force adjustment apparatus that integrates a differential mechanism with a planetary gear mechanism, including four elements with two degrees of freedom, connected to the driving source, motor, and gear trains to distribute and adjust driving forces between the left and right wheels, reducing weight and size while enhancing mountability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a differential mechanism and planetary gear mechanism are arranged separately as in prior art, then the functions of driving force distribution and adjustment can be achieved, but the apparatus weight and size increase, worsening mountability

Engineering Contradiction:
Improvedriving force distribution and adjustment functionVSAvoidapparatus weight and size
Core Design Contradiction:
Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

The patent merges the differential mechanism and planetary gear mechanism into a single integrated transmission system. The differential mechanism's planet gears serve dual purposes: distributing driving force to left and right wheels while simultaneously acting as the planetary gear mechanism's working components for adjusting driving force distribution. This merging eliminates separate mechanisms, reducing apparatus weight and size while maintaining both driving force distribution and adjustment functions.

Inventive Principle:
Principle #5Merging (Combining)

2Adaptability or versatility

If two separate planetary gear mechanisms are used for driving force distribution adjustment, then the adjustment function is achieved, but the device complexity and weight increase

Engineering Contradiction:
Improvedriving force distribution adjustment capabilityVSAvoidmechanism complexity and component quantity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent makes the differential mechanism's planet gears serve multiple functions simultaneously. These planet gears function as both the differential mechanism's force distribution elements and the planetary gear mechanism's adjustment elements. This multi-functionality eliminates the need for separate mechanisms, reducing device complexity and component quantity while achieving both driving force distribution and adjustment capabilities.

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

3Reliability

If the motor rotation is restrained to improve traction performance, then traction is enhanced, but the motor cannot passively absorb rotational speed differences during vehicle turning

Engineering Contradiction:
Improvetraction performanceVSAvoidpassive motor rotation for absorbing speed difference
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent implements a dynamic control system that adjusts motor restraint based on driving conditions. The control unit monitors vehicle operation state and dynamically adjusts the motor's rotational freedom: allowing passive rotation during normal turning to absorb speed differences, and restraining rotation during low-traction conditions to enhance traction performance. This dynamic adjustment resolves the contradiction between traction enhancement and passive speed difference absorption.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3459773B1Driving force adjustment apparatus
Publication Date: 2020.04.29 MITSUBISHI MOTORS CORP
  • EP3459773B1 patent drawingFigure 1~2A
  • EP3459773B1 patent drawingFigure 2B~2C
  • EP3459773B1 patent drawingFigure 3~4

AI summary

A driving force adjustment apparatus comprises a driving source (1) that drives a left shaft (3) and a right shaft (4) of a vehicle, and a motor (2) that regulates driving forces that are to be distributed to the left shaft (3) and the right shaft (4). The driving force adjustment apparatus further comprises a left side gear train (A) that adjusts a reduction ratio of the left shaft (3); a right side gear train (B) that adjusts a reduction ratio of the right shaft (4); and a planetary gear mechanism (5) that comprises four elements and has two degrees of freedom, the four elements being connected each to one of the driving source (1), the motor (2), the left side gear train (A), and the right side gear train (B). This configuration integrates the differential mechanism for the left and right wheels (L,R) and the mechanism for adjusting the driving forces of the left and right wheels, aiming at enhancement in moutability and weight reduction.