Aircraft Bistable Switch Using Leaf Spring Buckling

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Solution Overview

Problem

Bistable switches in aircraft control systems often experience mechanical wear, leading to the creation of additional stable equilibrium positions, which reduces reliability by introducing an intermediate stable position that can interfere with the intended two-position control mechanism.

Innovation Solution

A bistable switch design incorporating a leaf spring in a buckling state, mechanically connected to a frame and control means, which adopts distinct stable buckling positions for each control position, and includes detection means to emit an electrical signal, preventing the formation of intermediate equilibrium positions and enhancing reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional mechanical connections (rollers, tabs, springs) are used in bistable switches, then the switch can achieve two stable equilibrium positions, but mechanical wear creates additional stable equilibrium positions that reduce reliability

Engineering Contradiction:

Improveswitching reliabilityVSAvoidmechanical connection complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical connections (rollers, tabs, pivoting elements) with a leaf spring-based buckling mechanism. The leaf spring utilizes elastic deformation and buckling instability to achieve bistability without sliding or pivoting contacts, thereby eliminating wear-related failures and intermediate stable positions caused by mechanical friction and deformation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental operating parameter from mechanical friction-based equilibrium to elastic buckling-based equilibrium. By utilizing the nonlinear elastic behavior and buckling transitions of the leaf spring, the system achieves two distinct stable states defined by buckling positions rather than friction-based contact positions, eliminating the problem of wear-induced intermediate states.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If multiple mechanical components are used to achieve bistability, then the switch can maintain two stable positions, but the size and mass of the switch increase

Engineering Contradiction:

Improvecontrol precisionVSAvoidswitch mass

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent merges multiple traditional mechanical components (rollers, springs, tabs, pivoting elements) into a single integrated leaf spring structure. The leaf spring simultaneously provides the bistable mechanism, the control lever connection, and the detection trigger, significantly reducing the number of parts, overall size, and mass while maintaining reliable two-position control.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The leaf spring serves multiple functions: it acts as the control lever extension, provides the bistable mechanism through buckling, and triggers the detection means. This multi-functionality eliminates the need for separate components for each function, reducing overall switch mass and complexity while maintaining precise control.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of operation

If traditional rollers and springs are used, then the switch can provide two stable positions, but mechanical wear generates intermediate stable equilibrium positions

Engineering Contradiction:

Improveswitching feedbackVSAvoidcontrol reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces friction-based mechanical connections with an elastic buckling mechanism. The leaf spring provides clear, distinct stable positions through buckling transitions that produce audible snapping feedback, eliminating the ambiguous intermediate positions caused by wear and friction in traditional roller-and-spring mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 ensures reliable switching by eliminating intermediate equilibrium positions, improving user feedback through a snapping sound, and reducing the switch's size and mass, while maintaining precision and repeatability.

Implementation Method 1

a leaf spring (52) which is mechanically connected to the frame (26) and to the control means (34), the leaf spring (52) being arranged in a buckling state and being configured to adopt a first stable buckling position when the control means (34) is in the first control position and to adopt a second stable buckling position when the control means (34) is in the second control position

Methodology Applied

Scientific EffectBuckling:

Data Source

PatentUS20240145191A1Bistable switch intended to be fitted in an aircraft

Publication Date: 2024.05.02 SAFRAN ELECTRONICS & DEFENSE (FR)

AI summary

This bistable switch (24) is intended to be fitted in an aircraft and comprises a frame (26) and a control means (34, 94) which is intended to be operated by a user, the control means (34, 94) being movable relative to the frame (26) between a first control position and a second control position. This switch (24) comprises a leaf spring (52) which is mechanically connected to the frame (26) and to the control means (34, 94), the leaf spring (52) being arranged in a buckling state and being configured to switch between the two control positions in each of its two stable buckling positions, respectively.