ECU Case Sealing Groove Design for Waterproofing
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Solution Overview
Problem
Existing electronic control units face issues with inconsistent sealing due to size variations and warpage of resin case materials, leading to incomplete bonding and frequent waterproof failures, which are exacerbated by the reliance on waterproof sealing compounds.
Innovation Solution
The electronic control unit design features two case members with a rail-shaped convex portion fitting into a groove-shaped concave portion, including a narrow bottom surface side and wider aperture surface side concave portions linked by an inclined step, ensuring the adhesive compound remains in place and enhancing bonding, thereby ensuring a consistent waterproof seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a waterproof sealing compound is used to bond case members, then bonding strength is improved, but sealing reliability deteriorates due to size variation and warpage of resin members
Solution Approach 1:
The groove-shaped concave portion is designed with variable depth: deeper at the aperture surface side and shallower at the bottom surface side. This parameter change allows the adhesive to be retained in the deeper region while accommodating size variations and warpage of resin members, maintaining both bonding strength and sealing reliability
Solution Approach 2:
The groove-shaped concave portion acts as an intermediary structure that mediates between the bonding requirement (adhesive retention) and the sealing requirement (consistent contact). By providing a depth gradient, it allows the adhesive to remain in place while accommodating dimensional variations of the resin members
2Ease of manufacture
If resin members are used for case materials, then ease of manufacture is improved, but manufacturing precision deteriorates due to contraction and warpage
Solution Approach 1:
The groove depth is varied from shallow at the bottom surface to deep at the aperture surface. This parameter change accommodates the size variations and warpage inherent in resin molding, allowing the case members to be easily manufactured while maintaining assembly precision
Solution Approach 2:
The groove structure is designed in advance to accommodate future size variations. The depth gradient provides a cushioning effect that absorbs dimensional changes occurring during resin molding, preventing defects before they occur
3Strength
If adhesive is applied between case members, then bonding capability is improved, but adhesive retention deteriorates due to size variation
Solution Approach 1:
The groove depth is changed from shallow at the bottom to deep at the aperture surface. This ensures that the adhesive is retained in the deeper region where it can effectively bond the case members, while the overall groove structure accommodates size variations that would otherwise cause adhesive loss
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
This configuration ensures a reliable waterproof capability and reduces production costs by minimizing faulty ratios, even with size variations in case members, and maintains a consistent sealing characteristic across different conditions.
Implementation Method 1
both case members are bonded and assembled by an adhesive between the rail-shaped convex portion of the first case member and the groove-shaped concave portion of the second case member
Data Source
AI summary
An electronic control unit is configured in such a way that the groove-shaped concave portion of the second case member includes a first concave portion, in which a groove width at a bottom surface side is narrow, and a second concave portion, in which a groove width at an aperture surface side is wide, and the first concave portion and the second concave portion are linked by an inclined step portion in such a way that a groove width at the step portion is increased in a direction from the bottom surface side to the aperture surface side, and moreover, a tip of the rail-shaped convex portion of the first case member is fitted into the first concave portion at the bottom surface side of the second case member.