Tooth Profile Radial Angular Play for Roller Pinion Jamming

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Solution Overview

Problem

The deformation of aircraft landing gear and wheels causes significant variations in center distance between the wheel and roller pinion, leading to potential premature wear or jamming, which existing tooth profiles fail to accommodate effectively.

Innovation Solution

A method for generating a tooth profile with an interdental hollow profile that includes radial and angular deformations to allow for center distance variations, featuring a radial play to accommodate reduced center distances and angular play to prevent jamming, enabling smooth operation despite deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a standard tooth profile is used, then the wheel and pinion can operate at nominal center distance, but the rollers will jam or contact the bottom of the interdental hollow when center distance decreases due to deformation

Engineering Contradiction:
Improveoperation reliabilityVSAvoidroller movement smoothness
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The tooth profile parameters are modified by introducing radial play (modifying the bottom portion of the first profile to bring the bottom point closer to the center) and angular play (angularly displacing the first profile around the center). These parameter changes allow the interdental hollow to accommodate center distance variations while preventing roller jamming.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The tooth profile is designed with dynamic clearance characteristics - the radial play JR and angular play Jα allow the roller to move freely within the interdental hollow as center distance varies, transforming a static interference problem into a dynamic accommodation solution.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If the center distance is reduced due to deformation, then the wheel and pinion can accommodate deformation, but the rollers will come into contact with the bottom of the interdental hollow causing wear

Engineering Contradiction:
Improvecenter distance variation toleranceVSAvoidroller wear and blockage
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The radial play JR is designed in advance to provide a cushioning space that allows the roller to sink into the interdental hollow when center distance decreases, preventing direct contact with the bottom and avoiding wear and blockage before they occur.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The radial play JR acts as an intermediary space between the roller and the bottom of the interdental hollow, absorbing the harmful effect of center distance reduction and preventing the roller from directly contacting the interdental hollow bottom.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If a nominal interdental hollow profile is used, then the roller can engage without play at pitch diameter, but the roller will jam when angular displacement occurs due to center distance variation

Engineering Contradiction:
Improvetooth profile precisionVSAvoidoperation continuity
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The tooth profile is designed with asymmetric clearance characteristics - the angular play Jα creates an asymmetric angular displacement tolerance that allows the roller to maintain engagement without jamming even when center distance varies, while still achieving precise engagement at the pitch diameter.

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentEP3333454B1Method for generating a tooth profile of a wheel engaging with a roller pinion
Publication Date: 2020.05.13 SAFRAN LANDING SYSTEMS
  • EP3333454B1 patent drawingFigure 1~3
  • EP3333454B1 patent drawingFigure 4~5

AI summary

A method for generating an interdental groove profile (5) between two teeth (4) of a wheel (1) meshing with a roller pinion (2) (3) in a reference plane perpendicular to a central axis (X1) whose intersection with the reference plane defines a center (C), comprising the step of defining a nominal interdental groove with symmetrical first and second profiles such that the groove is adapted to allow the reception of a roller coming into contact without backlash with the active portions opposite the first and second profiles at a pitch diameter. The method of the invention comprises the steps of deforming the bottom portion (12) of the first profile so as to bring the bottom point closer to the center by an amount equal to a given radial clearance, and angularly displacing the first profile by a given half-angular clearance around the center to move it away from the radial axis.