Integrated Distributor Gear Joint for Transfer Case Alignment

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Solution Overview

Problem

Conventional transfer cases in vehicles with all-wheel drive systems face challenges in arranging the cardan shaft to the front axle with minimal inclination and optimal proximity to the longitudinal axis, due to geometric constraints and the need for universal joints with limited deflection angles, which complicates the use of a common floor assembly for both rear-wheel and all-wheel drive variants.

Innovation Solution

Integrating a joint partially into the output gear of the transfer case, allowing for a longer cardan shaft and minimizing its inclination angle, with the outer part of the joint coupled form-fittingly to the output gear and the inner part slidably coupled via splines or a plunging joint, enabling the cardan shaft to extend laterally past the transmission with a controlled helix angle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a universal joint is arranged at both ends of the cardan shaft with a conventional transfer case, then the cardan shaft can accommodate deflection angles, but the deflection angles are very limited and the joints must be arranged in a Z-arrangement

Engineering Contradiction:
Improvecardan shaft deflection capabilityVSAvoidjoint arrangement complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The joint is integrated directly into the output gear of the transfer case, merging the joint function with the gear function. This eliminates the need for separate universal joints at both ends of the cardan shaft, reducing structural complexity while maintaining deflection capability through the integrated joint design

Inventive Principle:
Principle #5Merging (Combining)

2Length of moving object

If the cardan shaft is arranged with a larger inclination angle to accommodate geometric boundary conditions, then the transfer case can be positioned closer to the front axle, but the inclination angle increases beyond optimal limits

Engineering Contradiction:
Improvedistance between transfer case and front axleVSAvoidcardan shaft inclination angle
Core Design Contradiction:
Length of moving objectVSShape

Solution Approach 1:

The integrated joint design changes the geometric parameters of the cardan shaft arrangement, enabling a more favorable inclination angle while maintaining the required distance between the transfer case and front axle. The joint's integration into the output gear allows for optimized shaft positioning that reduces the inclination angle to between 5° and 15°

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If the cardan shaft is arranged parallel to the longitudinal axis of the vehicle, then the same floor assembly can be used for both rear-wheel and all-wheel drive variants, but geometric boundary conditions prevent optimal parallel arrangement

Engineering Contradiction:
Improvefloor assembly compatibilityVSAvoidcardan shaft alignment
Core Design Contradiction:
Adaptability or versatilityVSShape

Solution Approach 1:

The integrated joint in the output gear enables the cardan shaft to be arranged with minimal inclination angle, making the floor assembly compatible with both rear-wheel and all-wheel drive variants. The design achieves universal applicability by allowing the shaft to extend laterally past the transmission at a controlled helix angle, accommodating different drive configurations with the same floor assembly

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

Data Source

PatentEP2277732B1Gear, in particular distributer gear
Publication Date: 2011.10.19 BAYERISCHE MOTOREN WERKE AG
  • EP2277732B1 patent drawingFigure 1
  • EP2277732B1 patent drawingFigure 2
  • EP2277732B1 patent drawingFigure 3~5

AI summary

The gear i.e. distributor gear (1) has a driven gear wheel (8) connected with an articulated shaft (18) by a universal joint (13) partially integrated into the wheel. An outer ring (12) of the joint is arranged between two carrier elements (9, 11) of the wheel. The outer ring is inserted into the wheel in a circumferential direction. An end (17) of the shaft is shiftably arranged in an inner ring (14) of the joint by a longitudinal tooth (16). The inner ring is pivotably arranged with respect to the outer ring. The wheel is supported in housings (23a, 23b) by two ball bearings (21, 22).