Electro-Pneumatic Cable Cutter Assembly Without Squib Hazards
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Solution Overview
Problem
Existing cable cutters for aircraft hoists, particularly those using electric squib initiators, face regulatory issues due to explosive materials, are single-shot devices with no built-in test features, and are susceptible to inadvertent firing under mechanical stress.
Innovation Solution
A cable cutter assembly for aircraft hoists utilizing an electro-pneumatic design with a solenoid valve and pressurized fluid system, which allows for repeated operation, built-in test features, and eliminates the need for explosive materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electric squib-based cable cutter is used, then the cable can be cut quickly and reliably, but the device contains explosive materials that create regulatory issues and safety concerns
Solution Approach 1:
The patent replaces the chemical/explosive mechanism (squib) with an electro-pneumatic system consisting of an electric motor, compressor, and controlled gas discharge mechanism. This substitution eliminates explosive materials while maintaining the rapid cable-cutting capability through controlled pneumatic actuation of the cutting blade.
Solution Approach 2:
The patent employs a pneumatic system where a compressor generates pressurized gas that is stored and then rapidly discharged to drive the cutting blade. This pneumatic mechanism provides the necessary force for cable cutting without using explosives, resolving the contradiction between reliable cutting and explosive material hazards.
2Productivity
If a squib-based cable cutter is used, then the cable can be cut in a single shot, but the device has no built-in test features and cannot be rehearsed or maintained
Solution Approach 1:
The patent transitions from a static, single-use squib system to a dynamic, reusable electro-pneumatic system. The motor-driven compressor and controllable gas discharge mechanism allow the system to be activated, tested, deactivated, and rehearsed multiple times, enabling built-in test capabilities and maintenance while maintaining rapid cutting performance.
Solution Approach 2:
The electro-pneumatic system incorporates self-testing capabilities through its controllable architecture. The motor and compressor can be activated independently of the cutting operation, allowing the system to perform self-diagnostics and rehearsals, ensuring operational readiness without requiring external testing equipment or procedures.
3Force
If a squib-based cable cutter is used, then the cutting force is generated instantly, but the device is susceptible to inadvertent firing due to mechanical abuse
Solution Approach 1:
The patent implements a preliminary action sequence where the electric motor first activates the compressor to generate and store pressurized gas before the cutting operation. This staged approach, combined with electronic control, provides multiple safety checkpoints that prevent inadvertent firing while ensuring that when cutting is intended, the full cutting force is delivered reliably.
Solution Approach 2:
The electro-pneumatic system incorporates feedback control through its motor and compressor control circuitry. Sensors monitor the system state (gas pressure, motor operation, blade position) and provide feedback to the control system, which can prevent activation under abnormal conditions or mechanical abuse, thereby eliminating inadvertent firing while maintaining reliable cutting force generation.
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 electro-pneumatic cable cutter assembly provides reliable and safe operation, reduces maintenance requirements, and avoids regulatory issues associated with explosive materials, while enabling efficient cutting of cables during rescue operations.
Implementation Method 1
the solenoid valve includes a coil and a magnetically movable armature
Implementation Method 2
A second pressurized gas cavity is fluidly interconnected with the first pressurized gas cavity by the second fluid passage. The actuator assembly may include at least one outlet port... move the cutter in a cable cutting direction
Data Source
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AI summary
A cable cutter assembly (200) for an aircraft (102) hoist is disclosed, and includes an actuator assembly (210) (e.g., at least one pressurized fluid cavity (248), a first outlet port (228), and a solenoid (240) that includes a coil (270) and an armature (290)). The armature (290) is movable between closed and open positions relative to the first outlet port (e.g., via an actuation force), with the armature (290) engaging the first outlet port (228) for the closed position (e.g., a valve seal (304) incorporated by the armature) and being spaced from the first outlet port (228) for the open position. A cutter (326) body (322) includes a cutter body (322) cavity (324) that is fluidly connected with the first outlet port (228). A cutter (326) is movably disposed within the cutter body cavity (324). Disposing the armature (290) in the open position (e.g., via energizing the coil) fluidly connects the pressurized fluid cavity (248) with the cutter body cavity (324) to move the cutter (326) in a cable (106, 360) cutting direction.