Cageless Full-Complement Bearing for Compact High-Load Gearboxes

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Solution Overview

Problem

Existing full-complement anti-friction bearings struggle to efficiently support high radial loads while maintaining compactness and ease of manufacturing, especially for compact planetary gearboxes with diameters less than 100 mm, and lack effective lubrication solutions.

Innovation Solution

A full-complement, cageless anti-friction bearing design featuring six rolling elements with an outer diameter matching the inner bearing body, an inner bore diameter slightly larger than three times the outer diameter, and a lubricant reservoir in the inner bearing body to reduce friction and enhance load distribution, using materials like metal or ceramic with diamond-like carbon coatings for improved wear resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a large number of rolling elements with small outer diameter are used, then the bearing can support high radial loads, but the bearing becomes complex and difficult to manufacture

Engineering Contradiction:

Improveradial load capacityVSAvoidbearing structure complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the cage component from the bearing structure. By removing the cage that normally holds and guides the rolling elements, the design simplifies the overall structure while maintaining the full-complement arrangement of rolling elements for high radial load capacity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using a cage to hold the rolling elements in place, the invention inverts the approach by allowing the rolling elements to be directly contained within the outer bearing body with optimized geometry. The inner bearing body diameter is specifically designed to create natural spacing for exactly six rolling elements, eliminating the need for external cage structures.

Inventive Principle:

Principle #13The other way round (Inversion)

2Volume of moving object

If the bearing is designed to be compact, then it is suitable for small planetary gearboxes, but manufacturing precision becomes more difficult to achieve

Engineering Contradiction:

Improvebearing sizeVSAvoiddimensional tolerance requirement

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The invention merges the functions of the cage and the outer bearing body by integrating the rolling element containment directly into the outer bearing body geometry. This consolidation eliminates separate components and reduces the overall bearing size while simplifying manufacturing to two main parts (inner and outer bearing bodies) that can be precision-cast or machined as single pieces.

Inventive Principle:

Principle #5Merging (Combining)

3Volume of moving object

If rolling elements are arranged closely together, then the bearing is compact, but friction increases between rolling elements

Engineering Contradiction:

Improvebearing compactnessVSAvoidfriction between rolling elements

Core Design Contradiction:

Volume of moving objectVSObject-generated harmful factors

Solution Approach 1:

The invention applies local quality by creating specific geometric features on the inner bearing body surface, including circumferential grooves that serve as lubricant reservoirs. These localized lubrication zones are positioned at critical areas where rolling elements contact the inner bearing body, providing targeted friction reduction without requiring the rolling elements to be spaced farther apart.

Inventive Principle:

Principle #3Local quality

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 design effectively supports high radial loads, maintains compactness, and ensures efficient operation by minimizing play between rolling elements and optimizing lubrication, making it suitable for compact planetary gearboxes with improved manufacturing simplicity and longevity.

Implementation Method 1

a lubricant reservoir in the inner bearing body to reduce friction

Methodology Applied

Scientific EffectLubrication: Lubrication

Implementation Method 2

using materials like metal or ceramic with diamond-like carbon coatings for improved wear resistance

Methodology Applied

Scientific EffectDiamond-like carbon coating: Diamond-like Carbon

Data Source

PatentUS11118624B2Cageless full-complement anti-friction bearing and planetary gearbox having such an anti-friction bearing

Publication Date: 2021.09.14 MAXON MOTOR AG

AI summary

A full-complement anti-friction bearing is disclosed which includes a plurality of rolling elements, an inner bearing body in the form of a shaft or an axle with a cylindrical outer diameter, and an outer bearing body arranged concentrically with the latter and having an inner bore. In an exemplary embodiment, all rolling elements have the same outer diameter and are arranged between the inner bearing body and the outer bearing body in such a way that the rolling elements roll on the outer diameter of the inner bearing body and on the inner bore of the outer bearing body, the outer bearing body being thus rotatably supported relative to the inner bearing body. In addition, the full-complement anti-friction bearing is configured without a cage.