Resin Push Ring Axial Bearing Constraint

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Solution Overview

Problem

Conventional direct drive motors face challenges in suppressing axial movement of bearings, requiring complex support structures and multiple bolts, which complicates automation and increases size, while existing solutions struggle to accurately detect rotational states and position outputs.

Innovation Solution

A direct drive motor design featuring a bearing with an inner and outer ring, a push ring made of polymeric resin material to absorb dimensional tolerances, and a single incremental resolver for accurate rotational state detection, along with a simplified support structure using a flange portion and retaining ring to prevent axial movement, and adhesive sealing members to enhance rigidity and alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If C-type retaining rings are used to fix the bearing in the axial direction, then the bearing can be fixed with a simple structure, but complete suppression of axial movement is difficult due to machining errors and dimensional tolerances

Engineering Contradiction:
Improvebearing support structureVSAvoidaxial position precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

A resin layer is introduced as an intermediary substance between the bearing outer ring and the housing. This resin layer fills gaps caused by dimensional tolerances and machining errors, acting as a mediator that ensures complete axial position suppression without requiring extremely precise machining of the housing groove or retaining ring.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If the first housing and second housing are divided into two parts at bearing portions and fastened with bolts, then axial movement of the bearing is suppressed, but the structure becomes complex and automation becomes difficult

Engineering Contradiction:
Improveaxial position precisionVSAvoidhousing structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention extracts the bearing support function from the complex divided housing structure and concentrates it into a single integrated housing with an axial groove. The retaining ring and resin layer are used to provide the necessary axial positioning, eliminating the need for multiple bolts and divided housings while maintaining the same level of axial position precision.

Inventive Principle:
Principle #2Taking out (Extraction)

3Strength

If multiple bolts are used to fasten divided housings, then the bearing is firmly supported, but the motor size increases and automation becomes difficult

Engineering Contradiction:
Improvebearing support strengthVSAvoidmotor size
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

The invention merges the bearing support function with the housing structure itself by forming an axial groove directly in the housing. The retaining ring and resin layer work together as a unified axial positioning mechanism, eliminating the need for multiple separate bolts and reducing the overall motor size while maintaining firm bearing support.

Inventive Principle:
Principle #5Merging (Combining)

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 prevents axial movement of the bearing, reduces motor size, and enhances positional accuracy, enabling more efficient automation and precise rotational control while maintaining structural integrity and reducing the footprint of the motor.

Implementation Method 1

a push ring formed of a polymeric resin material... absorbs width dimensional tolerance of the bearing and the retaining ring in the axial direction

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3135935B1Bearing device, conveyance device, inspection device and machine tool
Publication Date: 2020.01.29 NSK LTD
  • EP3135935B1 patent drawingFigure 1
  • EP3135935B1 patent drawingFigure 2
  • EP3135935B1 patent drawingFigure 3

AI summary

To provide a bearing device that can suppress movement of a bearing in an axial direction with a simple configuration, and a conveying device, an inspection device, and a machine tool that use the bearing device. A bearing 11 including an inner ring 21 and an outer ring 23 arranged to face each other with a rolling element 25 interposed therebetween, and a housing 7 including a housing inner 3 supported by the inner ring 21 and a rotor flange 5 supported by the outer ring 23 are included. The rotor flange 5 includes a flange portion 51 extending toward one end surface 23a side in an axial direction of the outer ring 23, and a C-type retaining ring 53 arranged at the other end surface 23b side in the axial direction of the outer ring 23. A push ring 55 formed of a resin material is provided in a gap between the flange portion 51 and the one end surface 23a in the axial direction.