Explosion-Proof Antenna Fitting With Shielded Capacitive Blocking
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Solution Overview
Problem
Existing explosion-proof fittings for antennas in hazardous areas are inflexible, requiring costly and time-consuming replacement of the entire antenna and sealing compound, and are not suitable for accommodating flexible printed circuits, as the sealing compound can alter passive filtering properties and complicate assembly.
Innovation Solution
An explosion-proof fitting with a central assembly that includes a capacitive blocking circuit and a shielding casing, where the capacitive blocking circuit is directly connected to the antenna and radio attachments, and a sealing compound fills the space between the shielding casing and housing, maintaining passive filtering properties and allowing easy antenna replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the antenna is completely buried in sealing compound, then explosion-proof sealing is improved, but antenna replacement flexibility deteriorates
Solution Approach 1:
The invention divides the antenna system into separable components: the antenna element and the sealing compound are no longer completely integrated. The antenna can be detached from the sealing compound without replacing the entire assembly, allowing maintenance and replacement while preserving the sealing structure.
Solution Approach 2:
The antenna is extracted from the sealing compound, eliminating the need for complete burial. This allows the antenna to be removed and replaced independently while the sealing compound remains in place, resolving the contradiction between sealing integrity and replacement flexibility.
2Reliability
If sealing compound contacts capacitive blocking circuit, then sealing protection is improved, but passive filtering properties deteriorate
Solution Approach 1:
A support structure acts as an intermediary between the sealing compound and the capacitive blocking circuit. This intermediary prevents direct contact between the sealing compound and the circuit components, preserving the passive filtering properties while maintaining sealing protection through the support structure's isolation function.
3Reliability
If flexible printed circuit is fastened with complicated contrivances, then connection reliability is improved, but assembly complexity deteriorates
Solution Approach 1:
The support structure provides self-service functionality by integrating attachment means that automatically secure the flexible printed circuit during assembly. The circuit board with attached circuit elements is held in position by the support structure's inherent design, eliminating the need for separate complicated fastening operations.
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 flexible and cost-effective antenna replacement while maintaining signal shielding and sealing properties, minimizing signal loss and simplifying assembly by keeping the capacitive blocking circuit's filtering properties intact and using a shielding casing for efficient insulation and grounding.
Implementation Method 1
the sealing compound, generally resin, can cause an alteration of the passive filtering properties when it comes into contact with the capacitive blocking circuit
Implementation Method 2
the use is known of a capacitive blocking circuit inside the explosion-proof box (i.e., the safe area) for providing an inherent safety barrier
Data Source
Figure 1
Figure 2
Figure 2a
AI summary
An explosion-proof fitting (10) for connecting an antenna (12) in hazardous areas comprises: - a housing (30) defining a cavity (36) between a first (32) and a second (34) end; - an antenna attachment (48) at said first end (32) and a radio attachment (45) at said second end (34); - a central assembly (6), accommodated in the cavity (36) . The central assembly (6) comprises a capacitive blocking circuit (44) connected to the antenna attachment (48) and the radio attachment (45), and a shielding casing (5), about the capacitive blocking circuit (44), which remains at least partially spaced apart therefrom and from the housing (30). Between the shielding casing (5) and the housing (3) there is a sealing compound (50). A central assembly (6) for an explosion-proof fitting (10), and an explosion-proof box (14) comprising an explosion-proof fitting (10) according to the present invention.