Bolt Head Lock Plate Assembly for Vibration-Resistant Mounting

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Solution Overview

Problem

Existing mount assemblies for gas turbine engines fail to effectively prevent or limit the loosening of mounting bolts due to vibrations during operation, necessitating an improved solution for fastener rotation prevention.

Innovation Solution

A mount assembly featuring a second bolt with a multi-point head and a second lock plate, where the lock plate has a multi-point aperture and a circumferential slot that aligns with the bolt head, allowing the fastener to compress the lock plate and prevent rotation, combined with a lock bolt and nut configuration to enhance static friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional mounting bolts are used without additional locking mechanisms, then the device complexity is low, but the reliability of fastener retention under vibration is insufficient

Engineering Contradiction:
Improvefastener retentionVSAvoidmounting assembly structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A lock plate is introduced as an intermediary component between the mounting bolt and the engine case. The lock plate features a multi-point aperture that receives the bolt head and a circumferential slot that engages with a corresponding feature on the engine case, preventing bolt rotation and loosening while maintaining a relatively simple overall structure

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The locking function is segmented from the bolt itself and implemented through a separate lock plate component. This allows the bolt to maintain its primary fastening function while the lock plate provides the anti-loosening function through its multi-point aperture and circumferential slot geometry

Inventive Principle:
Principle #1Segmentation

2Reliability

If a lock plate with circumferential slot is used to prevent bolt rotation, then the reliability of fastener retention improves, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvebolt anti-looseningVSAvoidmulti-point aperture alignment
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The multi-point aperture is designed with an asymmetric geometry featuring N distinct points arranged circumferentially, where N is an odd number. This asymmetric design provides multiple discrete engagement positions that are tolerant to manufacturing variations, as the circumferential slot can engage with any of the N points while still preventing rotation

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The design allows flexibility in the number of points (N) and the angular spacing between them, enabling optimization of the engagement geometry to balance manufacturing precision requirements with locking effectiveness. The circumferential slot width and depth can also be adjusted to accommodate reasonable manufacturing tolerances

Inventive Principle:
Principle #35Parameter changes

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 prevents or limits the rotation of fasteners, ensuring secure mounting and reducing the likelihood of bolt loosening, even under operational vibrations, thereby enhancing the stability and reliability of the assembly.

Implementation Method 1

The fastener may compress the lock plate towards the body to prevent rotation of the lock plate

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3657032B1Mount assembly with bolt head lock plate(s)
Publication Date: 2023.04.19 RTX CORP
  • EP3657032B1 patent drawingFigure 1
  • EP3657032B1 patent drawingFigure 2
  • EP3657032B1 patent drawingFigure 3

AI summary

A bolt lock plate includes a plate (32A) configured with a multi-point aperture (110A) and a slot (112A). The multi-point aperture (110A) has an axial centerline (114A) and a cross-sectional geometry with a quantity N of points (116) arranged about the axial centerline (114A). The slot (112A) extends circumferentially about the axial centerline (114A) a quantity M of degrees within the plate (32A) and between opposing ends (118, 120) of the slot (112A). The quantity M is at least substantially equal to three-hundred and sixty divided by a product of the quantity N and a constant C. The constant C is equal to one or two.