Switch Casing Sealing Edge Structure for High IP Protection
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Solution Overview
Problem
Conventional switch casings made of plastic materials are not suitable for humid environments due to deformation issues with screw-fixing lids, leading to reduced sealing effectiveness and low IP protection against dust and liquids, especially in thin designs.
Innovation Solution
A casing design with a raised sealing edge along the entire perimeter of the lid, housing a gasket in a groove, and hinged anchoring to reduce deformation and enhance sealing, allowing for higher IP protection ratings like IP69K.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If screw-fixing lids are used to close the casing opening, then the lid can be securely fixed, but the lid deforms and sealing effectiveness is reduced
Solution Approach 1:
A gasket is introduced as an intermediary element between the lid and the casing body. The gasket compensates for deformation caused by screw fixing, maintaining sealing effectiveness while allowing secure mechanical attachment of the lid to the casing.
Solution Approach 2:
The sealing approach is changed from direct rigid contact to flexible compression sealing. The gasket material deforms under compression to create a seal, accommodating dimensional variations and deformation while maintaining sealing pressure.
2Volume of moving object
If thin casings are used to reduce transversal dimensions, then the switch size is reduced, but the casing becomes less robust and sealing is compromised
Solution Approach 1:
A flexible gasket is used to provide sealing in thin casing designs. The gasket's flexibility allows it to maintain effective sealing contact even when the casing thickness is reduced, compensating for the reduced structural rigidity of thin-walled casings.
Solution Approach 2:
The sealing solution moves from relying on casing thickness (one dimension) to using a dedicated sealing element in the radial direction. The gasket provides sealing functionality independent of the casing wall thickness, enabling thin casing designs to achieve high IP protection ratings.
3Ease of manufacture
If plastic materials are used for the casing, then cost is reduced, but resistance to humid environments and water is insufficient
Solution Approach 1:
The casing system becomes a composite structure combining plastic casing material with elastomeric gasket material. This composite approach maintains the cost advantages of plastic while adding the humidity and water resistance properties of elastomers through the gasket sealing system.
Solution Approach 2:
The gasket acts as an intermediary barrier between the plastic casing interior and the external humid/watery environment. It provides the necessary environmental resistance that plastic alone cannot achieve, while allowing the cost-effective plastic material to be used for the main casing structure.
4Strength
If the lid is fixed with screws at the edge, then secure attachment is achieved, but the lid deforms and IP protection degree is reduced
Solution Approach 1:
The gasket serves as a mediator between the rigid lid/casing structure and the sealing requirement. It absorbs the deformation caused by screw fixation while maintaining continuous sealing contact, preserving IP protection despite the mechanical stress of screw attachment.
Solution Approach 2:
The sealing mechanism changes from rigid geometric fit to elastic compression. The gasket material's elastic properties allow it to maintain sealing pressure and contact even when the lid deforms under screw loading, keeping dust and liquid ingress paths blocked.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A casing for switches for industrial machine or plant control comprises a containment shell (2) having at least one opening (4) made on its front face (5) for accessing thereinside and having an outer perimeter edge (8), a lid (6) anchored in a movable manner to the front face (5) and having a perimeter edge (7) adapted to at least partially overlap the outer perimeter edge (8). The lid (6) has on its inner face a groove (9) which extends along the whole perimeter edge (7) thereof, internally thereto and which has a gasket (10). The front face (5) has a raised sealing edge (11) which extends internally to the outer perimeter edge (8) and along the whole longitudinal extension of said outer perimeter edge (8), said raised sealing edge (11) having a profile corresponding to that of said groove (9).