Casing Waterproof Sealing via Clearance Buffer and Tray
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Solution Overview
Problem
Existing casing designs for electronic control units face challenges in achieving reliable waterproof sealing, particularly when dimensional variations occur, leading to compromised waterproof performance and increased outer shape dimensions due to the need for larger seal material storage areas.
Innovation Solution
A casing design featuring a hermetically sealing portion with a predetermined outer clearance that ensures a secure seal, even with dimensional variations, using an outer circumferential groove and protruding portion configuration, along with a tray portion and seal material management to prevent overflow and maintain a compact form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clearance between the seal groove and protruding portion is reduced to zero to improve sealing, then waterproof performance improves, but dimensional variations cause assembly failures and reliability decreases
Solution Approach 1:
The patent applies beforehand cushioning by intentionally designing a non-zero clearance (A) between the seal groove and protruding portion that accommodates dimensional variations. This clearance acts as a buffer that prevents assembly failures while maintaining reliable sealing, even when manufacturing tolerances cause variations in the dimensions of the case and cover components.
2Reliability
If the outer shape dimension is increased to provide larger storing portions for seal material, then sealing reliability improves, but the compact form factor is compromised
Solution Approach 1:
The patent applies local quality by concentrating the seal material storage function in the localized clearance region (A) between the seal groove and protruding portion, rather than increasing the overall outer dimensions. This allows sufficient seal material to be stored locally at the sealing interface while maintaining a compact overall form factor of the casing.
3Strength
If the fit clearance is tapered to be wide at bottom and narrow at opening to improve adhesive spread, then adhesion force increases, but positional displacement and capillary phenomenon increase
Solution Approach 1:
The patent applies parameter changes by optimizing the fit clearance dimensions (outer clearance A and inner clearance C) to specific ranges that balance adhesive spread and positional control. Rather than using a tapered configuration, the patent maintains controlled clearances that allow sufficient adhesive application while preventing excessive capillary action and positional displacement during assembly.
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 enhanced waterproof sealing performance, reduces the need for precise assembly accuracy, and maintains a compact casing design by ensuring the seal material does not overflow, thus enhancing the casing's waterproof integrity and aesthetic appeal.
Implementation Method 1
By inclining the side surfaces of the protruding portion 31 inwardly with respect to the internal surface of the groove portion 22 from top to bottom of the groove portion 22, even in a case where a highly viscous adhesive 30 is used as the seal material, it becomes possible to insert the protruding portion 31 into the groove portion 22 by pressing the adhesive 30 with the side surfaces of the protruding portion 31. Hence, a pressure applied to the adhesive 30 can be increased and the adhesive 30 can be spread sufficiently across the side surfaces of the protruding portion 31. Accordingly, because wettability of the adhesive 30 on the side surfaces of the protruding portion 31 is enhanced, an adhesion force is increased.
Implementation Method 2
Heat generated in the heating components is transmitted to the case by contact heat transfer via a heat-transfer material.
Data Source
AI summary
An outer circumferential groove filled with a seal material and an opposing surface portion are provided to a fit portion of a case. A tray portion opposing the opposing surface portion and an outer circumferential protruding portion entering the outer circumferential groove are provided to the fit portion of a cover. Master dimensions are set so that an outer clearance A0 between the outer circumferential groove and the outer circumferential protruding portion is always larger than an inner clearance C0 between the former and the latter when center positions of the cover and the case coincide with each other.