Series Piston Pressure Switch for Munition Fuze Safety
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Solution Overview
Problem
Current commercial products lack a reliable, ultra-high pressure latching pressure switch for ammunition fuze safety systems, particularly for 120 mm un-spun tank munitions, as existing solutions like temperature and spin-based methods are not easily implementable and insufficient for robust secondary safety requirements.
Innovation Solution
A pressure switch design featuring a series piston actuator activated by mounting gas pressure during launch, with multiple sealing features and a simple, robust construction to ensure reliable electrical contact and prevent unintended initiation of the fuze, utilizing a 5,000 psi pressure threshold and materials like stainless steel and Ultem for durability and insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure switch is added to provide second environment safety for ammunition fuzing systems, then reliability is improved, but device complexity increases
Solution Approach 1:
The pressure switch assembly is integrated into the fuze body structure, combining the safety switching function with the existing fuze mechanism. The piston actuator, electrical contacts, and sealing elements are housed within the fuze body, eliminating the need for separate external components and reducing overall system complexity while maintaining the required second environment safety functionality.
Solution Approach 2:
The pressure switch assembly serves multiple functions: it acts as a second environmental safety mechanism, provides electrical circuit completion for fuze initiation, and responds to launch pressure conditions. By designing a single component that fulfills these multiple roles, the patent avoids adding separate dedicated devices for each function, thereby improving reliability without proportionally increasing complexity.
2Reliability
If multiple sealing features are implemented to protect against leaking gas pressure, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs flexible sealing elements including an O-ring seal and a flexible membrane that can deform to accommodate pressure differentials and assembly tolerances. These flexible sealing components provide reliable gas pressure containment while being manufactured using standard sealing techniques and materials, avoiding complex multi-step sealing processes or specialized manufacturing procedures.
Solution Approach 2:
The pressure switch assembly utilizes composite construction with a stainless steel body providing structural strength and pressure containment, combined with Ultem® material for the piston actuator and electrical components providing insulation and electrical properties. This composite material approach achieves reliable sealing and structural integrity while leveraging the manufacturing capabilities of each material type, simplifying production compared to requiring single-material solutions with complex processing.
3Reliability
If a series piston actuator is used to require pressure threshold for actuation, then safety is improved, but device complexity increases
Solution Approach 1:
The piston actuator is designed to automatically respond to pressure conditions without requiring external control systems or additional actuation mechanisms. When launch pressure exceeds the predetermined threshold, the piston automatically moves to complete the electrical circuit, and when pressure drops, it automatically returns to the open position. This self-actuating mechanism provides safe pressure-threshold-based control while maintaining mechanical simplicity, avoiding complex electronic controls or multiple moving parts.
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 pressure switch effectively prevents unintentional initiation of the fuze by requiring a reliable pressure threshold and maintaining a solid electrical contact throughout the ballistic event, ensuring enhanced safety and reliability for high-caliber munitions by sealing against gun gases and maintaining functionality up to 100,000 psi.
Implementation Method 1
The piston actuator of the pressure switch is in series with the fuze and the propulsion means such that if the munition never sees a pressure environment (propulsion), the pressure switch is never closed to complete the electrical circuit
Implementation Method 2
employing multiple sealing methods to protect the switch against leaking gas pressure into the munition, after the switch has first been actuated
Data Source
AI summary
A pressure switch is provided to arm a munition's fuze mechanism upon launch. The switch operation is based upon extreme gas pressures experienced during launch of the munition. The switch includes a piston contained in a housing. The piston translates due to launch pressures. The piston translation then causes a copper puck component to contact nearby electrical stab pins, to close a circuit. The closed circuit is then used to electrically arm the fuze mechanism.