Aircraft Control Lever Sealing Assembly for Low-Friction Dirt Exclusion
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Solution Overview
Problem
Aircraft control lever assemblies face challenges in preventing the ingress of detritus and dirt due to the mechanical or electrical connections between the control lever and the housing, which can lead to reliability issues and reduced operational lifespan.
Innovation Solution
A control lever assembly design featuring a housing with an outer and inner cover member that slidably covers the rim of the aperture, creating a chicane configuration with a constant gap to prevent contact and minimize friction, ensuring a sealing surface that overlaps the arced surface of the housing without direct contact, thereby restricting the entry of foreign objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If closing bellows are employed to seal between the moveable control lever and housing, then ingress of detritus and dirt is restricted, but friction and hysteresis increase due to contact between the bellows and the control lever movement
Solution Approach 1:
The patent extracts the sealing function from the moving bellows and relocates it to a stationary sealing arrangement. The seal is positioned at the aperture in the housing where the control lever passes through, rather than on the moving control lever itself. This allows the sealing surface to remain stationary while the control lever moves freely, eliminating friction and hysteresis caused by moving seals.
Solution Approach 2:
The patent introduces a stationary sealing member as an intermediary element between the control lever and the housing aperture. This sealing member remains fixed in the housing while the control lever moves through the aperture, providing continuous sealing without requiring the seal itself to move. The intermediary seal thus prevents direct contact between moving and sealing surfaces.
2Ease of operation
If the control lever is moved to control the aircraft, then the control function is achieved, but detritus and dirt can ingress through the aperture between the control lever and housing
Solution Approach 1:
The patent addresses the sealing problem by transitioning from a radial sealing approach to an axial sealing approach. Instead of sealing radially against the moving control lever, the seal is positioned axially at the aperture in the housing. The sealing surface extends axially along the aperture, creating an overlap that prevents detritus ingress while allowing unrestricted radial movement of the control lever.
Solution Approach 2:
The patent segments the sealing function from the control lever movement function. The housing aperture provides the movement path for the control lever, while a separate stationary sealing member provides the sealing function. This segmentation allows the control lever to move freely for control operations while the separate seal prevents detritus ingress through the aperture.
3Reliability
If a sealing arrangement is provided to prevent detritus ingress, then reliability is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent merges the sealing function with the existing housing structure. The sealing member is integrated into the housing aperture rather than being a separate component attached to the moving control lever. This integration reduces the number of moving parts and simplifies the overall device complexity while maintaining reliable sealing to prevent detritus ingress.
Solution Approach 2:
The stationary sealing arrangement in the housing aperture provides self-service sealing without requiring additional moving components or complex mechanisms. The seal automatically maintains its sealing function throughout the range of motion of the control lever, providing reliable protection against detritus ingress without increasing device complexity.
Data Source
AI summary
A control lever assembly for controlling an aircraft system. The lever includes: a housing having an outer side and an aperture defined by a rim; and a control lever extending through the aperture and movable in the aperture; the control lever having an outer cover member arranged to slide over the outer side of the housing and cover the rim throughout the range of movement of the control lever.