Pyrotechnic Circuit Interrupter Spacers for Temperature-Stable Isolation
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Solution Overview
Problem
Existing pyrotechnic circuit interrupters exhibit degraded electrical isolating power at varying temperatures, particularly at high temperatures, due to insufficient separation force and inconsistent conductor severing mechanisms.
Innovation Solution
Incorporation of spacers between the shear piston and conductor to uniformly distribute and enhance the separation force by controlling the movement of the shear piston, utilizing deformable pins or spacers that break or deform at specific overpressures to ensure consistent conductor severing across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shear piston directly contacts the conductor without spacers, then the separation process is simpler, but the acceleration of the shear piston is too low at the start of movement resulting in degraded electrical isolating power
Solution Approach 1:
The patent introduces spacers as intermediary elements between the shear piston and the conductor. These spacers are designed to break or deform at a specific overpressure threshold, serving as a mediator that delays the shear piston's movement until sufficient gas pressure is generated. This ensures the shear piston achieves higher acceleration and maintains reliable electrical isolation, while the spacers themselves are sacrificial components that are consumed during operation.
2Reliability
If the shear piston moves immediately upon explosive charge activation, then the response time is faster, but the separation force is insufficient leading to degraded electrical isolating power at high temperatures
Solution Approach 1:
The spacers are pre-installed in a position that blocks the shear piston's movement path. When the explosive charge activates, the spacers break or deform first, creating the necessary clearance and allowing the shear piston to move. This preliminary action of the spacers ensures that the shear piston only moves after sufficient gas pressure has built up, providing both the necessary delay for pressure buildup and the subsequent high-speed movement for reliable conductor severing.
3Reliability
If spacers are added between the shear piston and conductor, then the temperature-independent separation power is improved, but the device complexity increases
Solution Approach 1:
The spacers are designed as disposable, sacrificial components that are intentionally consumed during the circuit interrupter's operation. They are made from materials that break or deform at predictable overpressure thresholds, and once they have served their purpose of delaying the shear piston's movement, they are destroyed in the process. This approach allows the addition of complexity in the form of spacers while keeping the overall system cost-effective and manufacturable.
4Temperature
If the spacers have high resistance to break, then they provide sufficient delay for overpressure buildup, but they may prevent the shear piston from achieving sufficient movement speed
Solution Approach 1:
The spacers are designed with specific geometric parameters and material properties that define their break or deform at a predetermined overpressure threshold. By carefully selecting the spacer dimensions, material strength, and configuration, the design ensures that the spacers provide sufficient delay for pressure buildup but then fail in a controlled manner that allows the shear piston to achieve the necessary acceleration and movement speed for reliable conductor severing across different temperature conditions.
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 a pyrotechnic circuit interrupter with improved temperature-independent separation power, ensuring reliable conductor severing and arc extinction, even under thermal stress.
Implementation Method 1
an explosive charge for driving the shear piston
Implementation Method 2
the spacers are broken or pushed to the side, so that from the beginning of the movement a higher overpressure acts on the shear piston
Data Source
AI summary
The invention relates to a pyrotechnic current breaker (1) for severing a conductor (9), having a housing (2) which is equipped with a cutting piston (8) and an ignition unit (16) for driving the cutting piston (8). The conductor (9) passes through the housing (2), and when the igniter (18) is triggered, the cutting piston (8) severs a printed circuit board (12) from the conductor (9). According to the invention, at least one spacer (20), preferably three spacers (20), are provided between the cutting piston (8) and the conductor (9), said spacers having the shape of pins and lying on a circle (19), the center of which lies on the central axis (24) of the cutting piston (8). If the side of the spacers facing the printed circuit board (12) is angled such that the region (21) of each spacer (20) adjoining the central axis (24) has a shorter distance to the printed circuit board (12) than the region (23) facing away from the central axis (24), the spacers (20) are pushed towards the central axis (24) when the igniter is triggered such that the spacers can be received in a recess (22). Furthermore, the region (21) adjoining the central axis (24) is easily deformable such that changes in the distance between the cutting piston (8) and the conductor (9) due to temperature fluctuations are compensated for.