Landing Actuator Control Rod Sealing With a Replaceable Guide Piece

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Solution Overview

Problem

Aircraft landing gear actuators face high maintenance costs and wear due to the expensive and deteriorating sealing around the control rod between the hydraulic enclosure and the external zone, requiring a cost-effective solution for sealing and maintenance.

Innovation Solution

The solution involves relocating the friction surfaces subject to wear to an inexpensive, removable guide part rather than the expensive hydraulic part, allowing for easy maintenance and replacement of the guide piece and sealing means, thereby minimizing the cost of manufacturing and maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sealing is implemented around the control rod in the hydraulic enclosure, then dynamic sealing function is achieved, but manufacturing cost increases and maintenance becomes difficult

Engineering Contradiction:
Improvedynamic sealing functionVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The guide piece is separated into a distinct, removable component from the hydraulic enclosure. This segmentation allows the sealing function to be isolated in the guide piece, enabling independent maintenance and replacement without affecting the expensive hydraulic enclosure, thereby reducing manufacturing costs while maintaining reliable sealing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sealing function is extracted from the hydraulic enclosure and relocated to the guide piece. This extraction allows the sealing means to be positioned in a separate, easily replaceable component, reducing the manufacturing cost of the overall assembly while maintaining the dynamic sealing function.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If sealing is implemented around the control rod in the hydraulic enclosure, then dynamic sealing function is achieved, but maintenance cost increases due to wear

Engineering Contradiction:
Improvedynamic sealing functionVSAvoidmaintenance cost
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

By segmenting the guide piece as a separate, removable component, the sealing means are isolated in a low-cost part that can be independently maintained. This reduces maintenance costs by allowing replacement of only the worn guide piece and sealing means rather than the entire hydraulic enclosure assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The guide piece is designed as an inexpensive, replaceable component that absorbs wear and can be easily replaced when the sealing means deteriorate. This disposable approach to the guide piece significantly reduces maintenance costs compared to protecting the expensive hydraulic enclosure.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Strength

If friction surfaces are positioned on the hydraulic part, then structural integrity is maintained, but manufacturing cost increases and scrap is generated

Engineering Contradiction:
Improvestructural integrityVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The friction surfaces are segmented into the separate guide piece, allowing the hydraulic enclosure to maintain its structural integrity without expensive machined friction zones. The guide piece, being a separate component, can be manufactured more economically with the necessary friction surfaces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The friction surfaces are extracted from the hydraulic enclosure and relocated to the guide piece. This extraction preserves the structural integrity of the expensive hydraulic part while positioning machined friction zones on the low-cost guide piece, reducing manufacturing costs and scrap.

Inventive Principle:
Principle #2Taking out (Extraction)

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

This approach reduces the risk of damaging the hydraulic part during maintenance, lowers costs, and extends the life of the undercarriage by allowing for reliable and cost-effective dynamic sealing and detection of the hydraulic piston's sliding position.

Implementation Method 1

sealing means (6) are disposed around and against the control rod (5) to prevent the passage of fluid along the rod (5) between the first and second zones (2, 4)

Methodology Applied
Scientific EffectSealing:

Implementation Method 2

The first zone (2) is intended to receive a fluid at high hydraulic pressure and the second zone (4) is intended to receive a fluid at lower hydraulic pressure

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP3051149B1Aircraft landing actuator including a control system comprising a control rod
Publication Date: 2021.06.02 SAFRAN LANDING SYSTEMS
  • EP3051149B1 patent drawingFigure 1~2
  • EP3051149B1 patent drawingFigure 3~5

AI summary

A control system (1) comprising a control rod (5) extending between: - a first zone (2) located within a hydraulic enclosure delimited by an enclosure wall (3); and - a second zone (4) located outside said hydraulic enclosure; the control system (1) further comprising sealing means (6) arranged around and against this control rod (5) to prevent the passage of fluid between the first and second zones (2, 4). The system includes a guide piece (7) removably assembled to the enclosure wall (3), the sealing means (6) being assembled inside the guide piece (7) so as to allow relative movement of the rod (5) with respect to the guide piece (7) while maintaining a seal between said first and second zones (2, 4).