Gimbal Joint Clearance Control With a Spherical Washer

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Solution Overview

Problem

Flexible metal bellow gimbal joints in high strain, high vibration, or temperature shift environments suffer from excessive manufacturing clearances leading to fatigue damage and reduced lifecycle, requiring costly and risky redesigns to address.

Innovation Solution

A spherical washer is introduced between the clevis and ring in the gimbal system, with a cylindrical and spherical side to reduce clearance and allow rotation, maintaining desired gap tolerances without destructive disassembly, and coated for lubrication to enhance performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If plain spherical ball bearings are used to reduce clearance, then manufacturing precision is improved, but device complexity and repair difficulty worsen due to destructive disassembly requirements

Engineering Contradiction:

Improveclearance reductionVSAvoiddestructive disassembly

Core Design Contradiction:

Manufacturing precisionVSEase of repair

Solution Approach 1:

A spherical washer is introduced as an intermediary component between the clevis and the bellows assembly. This washer acts as a mediator that reduces clearance without requiring the complex ball bearing installation process, avoiding destructive disassembly while achieving the desired precision improvement

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The spherical washer is a simple, inexpensive component that can be easily replaced if needed. Rather than installing complex ball bearings that require destructive disassembly for maintenance, the washer provides a cost-effective, easily replaceable solution that achieves clearance reduction without compromising repairability

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Manufacturing precision

If existing joints are redesigned to reduce clearance, then manufacturing precision is improved, but productivity worsens due to costly and time-consuming rework

Engineering Contradiction:

Improveclearance reductionVSAvoidredesign time

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The spherical washer is designed and prepared in advance as a standalone component. By pre-fabricating this simple clearance-reduction element, the system avoids time-consuming on-site redesign and rework of the entire joint assembly, thereby improving productivity while maintaining manufacturing precision

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The clearance reduction function is segmented from the main joint redesign effort. Instead of redesigning the entire gimbal joint assembly, the solution isolates the clearance issue to a specific location and addresses it with a dedicated spherical washer component, significantly reducing the scope and time of required work

Inventive Principle:

Principle #1Segmentation

3Ease of operation

If larger clearances are maintained for ease of assembly, then ease of operation is improved, but reliability worsens due to increased fatigue damage in high strain environments

Engineering Contradiction:

Improveassembly simplicityVSAvoidfatigue resistance

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The spherical washer provides localized clearance control at the critical interface between the clevis and bellows assembly. This allows the rest of the assembly to maintain generous clearances for ease of operation, while the specific local area experiences reduced clearance to prevent fatigue damage, thus resolving the contradiction between assembly simplicity and fatigue resistance

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 solution effectively reduces fatigue damage and extends operational life by maintaining desired gap tolerances within the gimbal system, allowing it to withstand high strain and temperature changes without the need for destructive rework, thus improving performance and reducing maintenance costs.

Implementation Method 1

The washer further includes a spherical side, wherein the spherical side has a shape that enables the clevis to rotate with respect to the ring about an axis extending centrally through the hole in the washer

Methodology Applied

Scientific EffectSpherical geometry enabling rotation:

Implementation Method 2

The washer includes a cylindrical side, wherein the cylindrical side is shaped to contact a side of a ring for a gimbal when the washer is located between a clevis for the gimbal and the ring for the gimbal

Methodology Applied

Scientific EffectCylindrical contact surface reducing clearance:

Implementation Method 3

coated for lubrication to enhance performance

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentUS11402041B2Gimbal clearances optimization system

Publication Date: 2022.08.02 THE BOEING CO

AI summary

An apparatus and method for the manufacture and maintenance of flexible joint gimbal systems. The apparatus and method reduce metal corrugated bellows gimbal joint fatigue damage due to loose fitting parts by implementing a spherical washer to reduce clearance in the flexible joint of the gimbal within desired tolerances.