Frangible Connector Hoist System for Crash Cable Payout
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Solution Overview
Problem
Existing hoist systems for spare tire carriers in vehicles face issues such as heavy and expensive larger cables, complex secondary cable connections, and limited cable extension due to internal component fractures, which can lead to cable breakage during vehicle crashes.
Innovation Solution
A cable hoist system with a housing, drive cable, and a drive mechanism featuring a first gear assembly with frangible connectors that break under excessive force, allowing the gear to move relative to the control plate and enabling the drive cable to unspool, reducing tension and preventing breakage during crashes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a larger cable is used to increase the minimum breaking strength, then the cable strength is improved, but the weight and cost increase
Solution Approach 1:
The cable system is segmented into a primary cable for normal operation and a secondary cable/tether for crash protection. The primary cable can be lighter since it doesn't need to withstand crash forces alone, while the secondary cable provides the necessary strength backup during crashes, distributing the strength requirement across multiple components rather than requiring one heavy cable to handle all scenarios.
Solution Approach 2:
The system changes the operational parameters of the cable by introducing a controlled failure mode through the frangible connector. During normal operation, the primary cable carries full load; during crashes, the frangible connector fails at a predetermined force, transferring the load to the secondary cable. This parameter change allows the primary cable to be optimized for weight while the secondary cable provides the necessary strength threshold.
2Reliability
If a secondary cable/tether is used to catch the spare tire if the main cable breaks, then the reliability is improved, but the device complexity and cost increase
Solution Approach 1:
The secondary cable/tether is integrated with the primary cable system through the frangible connector, creating a unified cable assembly where both cables work together. The secondary cable is positioned to automatically engage when the frangible connector fails, merging the functions of primary lifting and crash protection into a single integrated system rather than separate independent systems.
Solution Approach 2:
The frangible connector acts as an intermediary component between the primary and secondary cables. It normally connects the primary cable to the reel mechanism but is designed to fail at a predetermined force, at which point it mediates the transition of load from the primary cable to the secondary cable, enabling automatic switching without complex control systems.
3Length of moving object
If frangible connectors are used to allow cable displacement, then the cable extension capability is improved, but the cable breaking risk increases
Solution Approach 1:
The frangible connector is designed with predetermined failure characteristics that cushion the transition during crash events. By failing at a controlled, predetermined force rather than allowing the primary cable to stretch excessively or break suddenly, the frangible connector provides a cushioning effect that protects the primary cable from breaking while still allowing the necessary cable extension to occur through the secondary cable engagement.
Solution Approach 2:
The frangible connector is designed as a disposable component that is intended to fail under crash conditions. Rather than designing the primary cable or other critical components to withstand crash forces indefinitely, the system uses a low-cost, replaceable frangible connector that sacrifices itself to protect more critical components, allowing cable extension while preventing catastrophic failure of the primary cable.
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 allows for safer and more reliable cable payout during crashes while maintaining connection to the spare tire, reducing weight and complexity compared to prior art, and eliminating the need for secondary cables.
Implementation Method 1
the at least two frangible connectors break to allow the first gear to move relative to the control plate member such that the second gear and the reel assembly can rotate to allow for pay out of the drive cable
Data Source
AI summary
A cable hoist system for a spare tire carrier in a vehicle includes a housing; a drive cable; a reel assembly; and a drive mechanism. A first gear assembly of the drive mechanism includes a control plate member connected to a first gear using at least two frangible connectors. The at least two frangible connectors connecting the control plate member and the first gear provides a frangible connection in the first gear assembly such that, when the first gear assembly is subject to a force exceeding a predetermined value caused by momentum of a spare tire applied through the reel assembly and a second gear of a second gear assembly, the at least two frangible connectors break to allow the first gear to move relative to the control plate member such that the second gear and the reel assembly can rotate to allow for pay out of the drive cable.