Seat Track Fitting Shear Pin Engagement Mechanism
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Solution Overview
Problem
Existing passenger seat track fitting assemblies lack sufficient load-carrying capacity and strength to securely attach seats to vehicle tracks, leading to potential misalignment or dislodgment during crashes or turbulence, which can pose safety risks to occupants.
Innovation Solution
A track fitting assembly with a main body, pre-loaded stud assembly, and shear plunger assembly, featuring a plunger, shear pin, and button, which can be configured into engaged and disengaged positions to securely attach the seat to the track, utilizing a cam mechanism and spring forces to ensure stability and easy disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional track fitting assemblies with studs and bolts are used, then the assembly is simple in structure and easy to install, but the load-carrying capacity and strength are insufficient to prevent seat dislodgment during crashes or turbulence
Solution Approach 1:
The track fitting assembly is divided into multiple functional components: a main body, a shear plunger assembly (with plunger, spring, and shear pin), and a button assembly. This segmentation allows each component to perform a specific function - the shear pin provides shear strength, the spring provides resilient force, and the button provides manual actuation capability - collectively achieving high load-carrying capacity while maintaining manageable complexity through functional specialization
Solution Approach 2:
The shear pin is pre-installed in a broken or weakened state within the main body, and the plunger is pre-loaded by the spring into a positioned state. This preliminary preparation allows the assembly to be quickly engaged with the track by simply inserting the button, eliminating the need for complex fastening operations during installation while ensuring the structure is ready to withstand crash loads immediately upon engagement
2Reliability
If the track fitting assembly uses a secure locking mechanism to prevent seat rattle, then the seat stability is improved, but the ease of disengagement for seat adjustment becomes difficult
Solution Approach 1:
The button assembly is designed to be manually actuated by the user to disengage the shear pin from the track, providing self-service capability for seat adjustment. The spring automatically re-loads the plunger into the positioned state after disengagement, preparing the assembly for re-engagement without requiring additional tools or complex operations, thus maintaining ease of operation while ensuring secure locking during normal use
Solution Approach 2:
The shear pin is designed to transition between two dynamic states: engaged with the track providing secure locking, and disengaged allowing seat movement. The button assembly provides the mechanical advantage to overcome the spring force and shear the pin from its engaged position, enabling easy disengagement when needed while maintaining reliability during normal operation
3Force
If the shear pin is designed to extend through the opening for secure engagement, then the load transfer capability is improved, but the risk of accidental disengagement or interference with surrounding components increases
Solution Approach 1:
The shear pin is nested within the main body in its stored position, protected by the recess and surrounded by the button assembly. When engaged, the pin extends through the opening but remains guided and constrained by the main body geometry. This nesting approach protects the shear pin from accidental damage or interference with surrounding components while maintaining full load transfer capability when engaged
Solution Approach 2:
The button assembly acts as an intermediary mechanism between the user and the shear pin. Instead of directly manipulating the shear pin, the user actuates the button, which transmits force through the plunger and spring system to reliably shear the pin from its engaged position. This intermediary mechanism prevents accidental disengagement while ensuring controlled, intentional release when needed
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 provides enhanced load-carrying capacity and stability to prevent seat rattle and ensure the seat remains securely attached during normal conditions and extreme events, such as crashes, thereby enhancing passenger safety.
Implementation Method 1
at least one shear plunger assembly comprising a shear pin, a plunger-spring, and a button
Implementation Method 2
The shear plunger assembly may be configured to have a disengaged position, wherein the button is extended from the main body and the shear pin is positioned within the main body, and an engaged position, wherein the button is positioned substantially flush with the main body, the recess is positioned substantially flush with the disengagement recess, and the shear pin is extended from the main body and within the at least one opening
Data Source
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AI summary
Described are track fitting assemblies (10) having a main body (12) with at least one plunger aperture (90), at least one button aperture (102) intersecting the at least one plunger aperture (90), and at least one disengagement recess (150), at least one shear plunger (16) assembly having a plunger (74), a shear pin (82), a plunger-spring (80), and a button (76) comprising a recess (146), and a track (120) with a pair of lips (124) having at least one opening (132). The shear plunger assembly (16) is configured to have a disengaged position, wherein the button is extended from the main body and the shear pin (82) is positioned within the main body, and an engaged position, wherein the button (76) is positioned substantially flush with the main body, the recess (148) of the button (76) is positioned substantially flush with the disengagement recess (180) of the main body (12), and the shear pin (82) is extended from the main body (12) and within the at least one opening (132).