Planetary Gear Housing Laser Welding Overlap

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Solution Overview

Problem

Existing transmission housings with integrated internal teeth have unused space due to the necessary overlapping area for laser welding, limiting the compactness and functionality, especially in small transmissions where high transmission ratios are required.

Innovation Solution

A gear housing with a hollow-cylindrical body featuring a first internal toothing and a bearing flange with a second internal toothing in the overlapping area, allowing for laser transmission welding and enabling the integration of an additional planetary gear, thus achieving compact dimensions and high functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If an overlap area is provided for laser transmission welding between the bearing flange and housing body, then the manufacturing process is simple and cost-effective, but unused spaces are created that reduce compactness

Engineering Contradiction:
Improvemanufacturing process simplicityVSAvoidgearbox housing compactness
Core Design Contradiction:
Ease of manufactureVSVolume of moving object

Solution Approach 1:

The patent merges the overlap area (originally unused space for welding) with a functional second internal toothing. The bearing flange is designed with this second toothing that engages with the first toothing on the housing body, transforming the wasted overlap space into a useful gear engagement zone that provides additional planetary gear support while maintaining the laser welding connection.

Inventive Principle:
Principle #5Merging (Combining)

2Adaptability or versatility

If two internal toothed sections are integrated into the housing body, then gear functionality is enhanced, but the housing body must be axially open on both sides increasing complexity

Engineering Contradiction:
Improvegear functionalityVSAvoidhousing structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the housing structure into two separate components: the housing body with the first internal toothing and the bearing flange with the second internal toothing. This segmentation allows the second toothing to be formed on the bearing flange (which can be axially open on one side only) rather than requiring the entire housing body to be open on both sides, thus reducing structural complexity while maintaining dual gear functionality.

Inventive Principle:
Principle #1Segmentation

3Volume of moving object

If compact dimensions are achieved in small gearboxes, then space is optimized, but the ability to achieve high transmission ratios is limited

Engineering Contradiction:
Improvegearbox housing dimensionsVSAvoidtransmission ratio capability
Core Design Contradiction:
Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent implements a nested gear configuration where the second internal toothing on the bearing flange engages with the first internal toothing on the housing body, creating a compact dual-stage planetary gear system. This nested arrangement allows two gear stages to be integrated within the same radial space, achieving high transmission ratios without increasing the overall gearbox dimensions.

Inventive Principle:
Principle #7Nested doll (Nesting)

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

This design allows for a high level of functionality with compact dimensions, simplifies assembly, increases stability, and reduces manufacturing costs by using fewer components and optimizing the use of internal space, while also accommodating different gear reductions and thermal expansion through adjustable tooth geometries.

Implementation Method 1

A laser beam is directed onto this overlap area, causing the material of the bearing flange to melt and bond with the housing body

Methodology Applied
Scientific EffectLaser transmission welding: Laser Beam Welding

Implementation Method 2

causing the material of the bearing flange to melt and bond with the housing body

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP3495695B1Planet carrier for a planetary gear
Publication Date: 2020.10.21 BUHLER MOTOR GMBH
  • EP3495695B1 patent drawingFigure 1~2
  • EP3495695B1 patent drawingFigure 3

AI summary

The invention relates to a gearbox housing for a planetary gearbox with a hollow cylindrical housing body (10) having a first internal toothing (11) and a bearing flange (20) that engages coaxially, at least partially, in the housing body (10) to form a contact area (30), wherein the housing body (10) and the bearing flange (20) are metallurgically joined in the contact area (30) by laser transmission welding. The invention is characterized in that the bearing flange (20) has a second internal toothing (21) in the contact area (30). Furthermore, the invention relates to a planetary gearbox and a motor-gearbox combination with such a gearbox housing, as well as a manufacturing method.