Adjustable End Stop Assembly for Linear Actuator Travel Limits

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Solution Overview

Problem

Existing mechanical linear actuators lack effective mechanisms for precisely limiting the travel of nut members to prevent damage and over-travel, particularly in applications like thrust reversers and power drive units where precise control is crucial.

Innovation Solution

A linear actuator system with a circumferentially and axially adjustable end stop assembly, featuring a screw member with splines and a nut member in threaded engagement, along with a ring member and threaded members that allow for adjustable positioning and orientation to prevent over-travel by engaging with the nut member.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a fixed end stop mechanism is used, then the structure is simple, but the positioning precision and adaptability are insufficient

Engineering Contradiction:
Improvepositioning precisionVSAvoidstructure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The end stop assembly is designed with adjustable components that allow dynamic repositioning along the screw member. The ring member can be circumferentially adjusted to different angular positions, and the threaded members enable axial repositioning, transforming a static fixed end stop into a dynamic adjustable one to achieve precise positioning while maintaining reasonable structural complexity

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system allows changing of geometric parameters including the angular position of the ring member around the screw member and the axial position through threaded member adjustment. This parameter variability enables precise control over end stop positioning without requiring a completely complex reconfigurable structure

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a separate mechanical end stop mechanism is added, then the travel limitation function is improved, but the device complexity increases

Engineering Contradiction:
Improvetravel limitation reliabilityVSAvoidmechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The end stop function is merged with the existing actuator components. The ring member integrates with the screw member through spline engagement, and the threaded members are incorporated into the flange assembly. This merging approach provides reliable travel limitation without adding a completely separate mechanical system

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The ring member serves multiple functions: it engages with the screw member splines to prevent over-rotation, provides a mounting structure for the threaded members, and acts as the circumferential adjustment mechanism. This multi-functionality achieves reliable travel limitation while minimizing additional mechanism complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If the end stop position is fixed, then the manufacturing is simple, but the adaptability to different applications is reduced

Engineering Contradiction:
Improveapplication adaptabilityVSAvoidmanufacturing simplicity
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The end stop assembly incorporates adjustable features allowing circumferential repositioning of the ring member and axial repositioning through threaded members. This dynamic adjustability provides application versatility without requiring completely different assemblies for different uses, while maintaining manufacturing simplicity through standardized components

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The end stop assembly is segmented into adjustable components (ring member, threaded members, flange) that can be independently positioned and configured. This segmentation allows adaptation to different applications through component repositioning rather than manufacturing different complete assemblies, balancing versatility with manufacturing simplicity

Inventive Principle:
Principle #1Segmentation

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 system provides precise control over the axial and circumferential positioning of the end stop, effectively preventing over-travel and ensuring reliable operation in applications like aircraft systems, enhancing safety and reducing the risk of damage.

Implementation Method 1

the threaded shaft is in threaded engagement with the threaded bore, and a plurality of threaded members in threaded engagement with the flange portion of the flange member

Methodology Applied
Scientific EffectThreaded engagement: Screw

Data Source

PatentEP3196509B1Linear actuator system with circumferentially and axially adjustable end stop assembly
Publication Date: 2021.10.13 THE BOEING CO
  • EP3196509B1 patent drawingFigure 1
  • EP3196509B1 patent drawingFigure 2
  • EP3196509B1 patent drawingFigure 3

AI summary

A linear actuator system including a screw member elongated along a longitudinal axis, the screw member including a threaded portion and an end portion, a nut member coaxially received over the screw member and in threaded engagement with the threaded portion of the screw member, a ring member received over the end portion of the screw member, a flange member connected to the end portion of the screw member, and a threaded member in threaded engagement with the flange member, the threaded member having a distal end protruding toward the ring member.