Tapered Roller Bearing Cage Structure for High Moment Rigidity

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Solution Overview

Problem

Conventional tapered roller bearings face limitations in achieving high moment rigidity and long life while maintaining a compact size, with issues related to roller retention, contact angle, and lubrication failure due to insufficient cage strength and flange design.

Innovation Solution

A tapered roller bearing design featuring a resin cage with specific geometric features such as varying pocket widths, a large flange with a recessed portion, and an optimized contact angle of 45°, which enhances roller retention, moment rigidity, and lubrication by preventing cage damage and maintaining a compact structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the contact angle is increased to 35° or more to improve moment rigidity, then moment rigidity is improved, but roller retention becomes insufficient due to the inner ring not having a smaller flange

Engineering Contradiction:
Improvemoment rigidityVSAvoidroller retention
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The cage acts as an intermediary structure that provides roller retention through protrusions on its opening edges, replacing the need for a smaller flange on the inner ring. This allows the contact angle to be increased to 35° or more for improved moment rigidity while maintaining reliable roller retention through the cage's integrated protrusions.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If angular ball bearings are used to meet requirements of higher moment rigidity and longer life, then moment rigidity and life are improved, but bearing size becomes so large that it cannot maintain or reduce the bearing size

Engineering Contradiction:
Improvemoment rigidityVSAvoidbearing size
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

The invention changes the contact angle parameter to 35° or more, which optimizes the load distribution and moment rigidity characteristics of the tapered roller bearing. This parameter change allows the bearing to achieve high moment rigidity and long life while maintaining a compact size, avoiding the need for larger angular ball bearings.

Inventive Principle:
Principle #35Parameter changes

3Strength

If a large flange with an inclined surface is provided on the inner ring to support tapered rollers, then roller support is improved, but the inclined surface may surface-contact with the cage and damage the cage due to insufficient strength

Engineering Contradiction:
Improveroller supportVSAvoidcage strength
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The cage with protrusions on its opening edges serves as an intermediary retention structure that prevents rollers from falling out without requiring a smaller flange on the inner ring. This eliminates the need for an inclined surface on the large flange that would otherwise contact and potentially damage the cage, thereby protecting cage integrity while maintaining roller support.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3690266B1Tapered roller bearing
Publication Date: 2023.04.05 NSK LTD
  • EP3690266B1 patent drawingFigure 1A~1B
  • EP3690266B1 patent drawingFigure 2A~2B
  • EP3690266B1 patent drawingFigure 3A~3B

AI summary

A tapered roller bearing (1) includes an outer ring (2) having an outer ring raceway surface (2a) on the inner peripheral surface thereof, an inner ring (3) having an inner ring raceway surface (3a) on the outer peripheral surface thereof, and a plurality of tapered rollers (4) arranged in a rollable manner between the outer ring raceway surface and the inner ring raceway surface. A large flange (3b) is formed on an end portion of the inner ring on a large-diameter side of the inner ring, and the inner ring raceway surface continuously extends to the end face (3c) of the inner ring on a small-diameter side of the inner ring. The contact angle (α) is 37°30' to 50°. In this manner, the tapered roller bearing having high moment rigidity and long life can be provided.