Field Device Housing With Conductive Core and Plastic Shell
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Solution Overview
Problem
Existing field devices for process automation face challenges in balancing mechanical robustness and corrosion protection, with metal housings being costly and requiring complex coatings, while plastic housings lack mechanical stability and offer inferior EMC protection, leading to increased development efforts.
Innovation Solution
A field device with a conductive metal housing core surrounded by a non-conductive plastic shell, utilizing injection molding or other connections for assembly, which provides cost-effective manufacturing and universal industrial sector compatibility, along with effective EMC shielding and corrosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal housings are used for field devices, then mechanical robustness is improved, but manufacturing cost increases due to complex coatings and corrosion protection measures
Solution Approach 1:
The housing combines a metal core (providing mechanical robustness and EMC shielding) with a plastic outer shell (providing corrosion protection). This composite structure allows each material to contribute its advantageous properties while mitigating their individual disadvantages, eliminating the need for expensive coatings on metal housings.
Solution Approach 2:
The housing is divided into two distinct parts: an inner metal core and an outer plastic shell. This segmentation allows independent optimization of each component - the metal core for mechanical strength and EMC protection, and the plastic shell for corrosion resistance - simplifying manufacturing compared to coated metal housings.
2Ease of manufacture
If plastic housings are used for field devices, then manufacturing cost and corrosion protection are improved, but mechanical robustness and EMC protection deteriorate
Solution Approach 1:
By combining plastic and metal in a composite housing structure, the invention retains the cost-effectiveness and corrosion resistance of plastic while adding the mechanical robustness and EMC shielding properties of metal through the internal core structure.
Solution Approach 2:
The metal core is nested within the plastic shell, creating a layered structure where the inner metal component provides structural support and electromagnetic shielding, while the outer plastic layer provides environmental protection and cost-effective manufacturing.
3Object-affected harmful factors
If thin metal layers are applied to plastic housings for EMC protection, then EMC shielding is improved, but mechanical stability remains insufficient and manufacturing cost increases
Solution Approach 1:
Instead of applying thin metal coatings to plastic, the invention uses a substantial metal core structure that inherently provides both mechanical stability and effective EMC shielding. The metal core's thickness and continuity ensure robust electromagnetic protection without relying on thin layers.
Solution Approach 2:
The invention extracts the EMC protection function from a surface coating approach and implements it through a volumetric metal core structure. This extraction allows the metal component to provide both structural support and electromagnetic shielding as integrated functions rather than separate layers.
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 enables cost-effective production of field devices with enhanced mechanical robustness and corrosion resistance, while ensuring universal applicability and improved EMC protection through the use of a conductive housing core and non-conductive shell, reducing the need for complex coatings and thin metal layers.
Implementation Method 1
a housing for EMC shielding, which encloses an interior space
Implementation Method 2
the housing shell surrounding the housing core on all sides is applied to the housing core by an injection molding process
Data Source
Figure 1
AI summary
The invention relates to a field device (1) for use in process automation, said field device having a housing (22) with EMC protection. The housing contains a conductive housing core (3) which is surrounded on all sides by a non-conductive housing casing (2) in a force-fitting or form-fitting manner. At least one printed circuit board (15) is placed on an electrically conductive region (14) of the housing core (3) and is connected thereto, and the printed circuit board divides the interior of the housing into at least two chambers (12, 13) with different degrees of EMC protection. The printed circuit board (15) contains a through-bore (20) by means of which at least one first and second electronic circuit (10, 19) arranged in a mutually spaced manner in different respective chambers (12, 13) are contacted together. The electrically conductive housing core (3) is tied to ground potential by means of ground contacts (6, 16) which are arranged on the inside or the outside of the housing, and the ground potential electrically contacts the circuits (10, 19) by means of housing core (3) regions (9), which are led into the interior through the housing casing (2), using spring contacts (11). Transitions (7) into a sensor or cover unit (17, 18) are provided in the housing in the form of screw contacts and/or sliding contacts such that the contacts are electrically connected to the housing core (3), and seals (8) protect the transitions (7) from environmental influences.