Arming Safety Device External Stator Rotor
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Solution Overview
Problem
Existing arming and safety devices for pyrotechnic chains in the aeronautical field face issues with jamming due to brush motor oxidation and dynamic seal adhesion, leading to reliability and weight concerns, especially after long periods of inactivity.
Innovation Solution
The arming and safety device design relocates the stator outside the casing with the rotor inside, utilizing magnetic actuation to move the arming element between armed and disarmed positions, eliminating the need for dynamic seals and reducing the required driving force, electrical consumption, and eliminating the need for torque limiting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If brushed motors are used for actuation, then device complexity is reduced, but reliability deteriorates due to brush oxidation in vacuum environments
Solution Approach 1:
The invention replaces the brushed motor's mechanical contact system with an electromagnetic induction system. The stator generates a rotating magnetic field that induces current in the squirrel-cage rotor, eliminating brushes and commutators that oxidize in vacuum environments.
Solution Approach 2:
The invention changes the motor's operational parameters by using induction motor technology instead of brushed DC motors. This changes the actuation mechanism from mechanical contact to electromagnetic coupling, improving reliability in vacuum while maintaining actuation functionality.
2Reliability
If high driving force is applied to prevent jamming, then operational reliability is improved, but device mass and dimensions increase
Solution Approach 1:
The invention extracts the torque limiting device and associated mechanical components from the system. By eliminating dynamic seals and using magnetic coupling, the system achieves reliable operation without requiring excessive driving force, thereby reducing overall device mass.
Solution Approach 2:
The invention replaces mechanical force transmission through seals and gears with magnetic field coupling. This substitution eliminates the need for high driving forces to overcome friction and adhesion, allowing for a more compact and lighter device design.
3Reliability
If multiple components are added to increase driving force, then jamming prevention is improved, but device complexity increases
Solution Approach 1:
The invention extracts and eliminates torque limiting devices, dynamic seals, and associated mechanical components. The simplified motor design with external stator achieves reliable jamming prevention through magnetic coupling without requiring multiple additional parts.
Solution Approach 2:
The hermetic casing serves multiple functions: it contains the rotor, provides structural support, and acts as a magnetic flux path for the induction motor. This multi-functionality eliminates the need for separate torque limiting devices and sealing mechanisms, reducing overall device complexity.
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
This design enhances reliability, reduces weight and dimensions, prevents jamming due to oxidation or lack of lubrication, and maintains operational efficiency even after extended periods of inactivity, while maintaining simplicity and cost-effectiveness.
Implementation Method 1
At least one magnetic drive member of the rotor, contained in the housing, is magnetically actuated by the stator, through the housing, whereby the arming element is moved between its armed and disarmed positions.
Data Source
Figure 1~2
Figure 3~4A
Figure 4B
AI summary
An arming and safety device (10) for a pyrotechnic chain comprises a housing (20) having an inlet zone (21) for a pyrotechnic stream and an outlet zone (22) for the pyrotechnic stream, an arming element (30) housed in this housing (20), between the inlet (21) and outlet (22) zones, and adapted to move between a disarmed position in which it blocks the passage of the pyrotechnic stream and an armed position in which it allows the passage of the pyrotechnic stream, and an electric motor for driving the arming element (30). According to the invention, the stator (41) of the electric motor (40) is located outside the housing (20) and the rotor (42) is entirely contained inside the housing (20).