Waterproof Switch Support Member with Variable Gap
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Solution Overview
Problem
Existing waterproof structures for in-vehicle switch devices, such as engine start switches, face challenges in preventing water droplet infiltration due to capillary phenomena, which can lead to corrosion of electronic components and increased manufacturing costs and complexity.
Innovation Solution
A waterproof structure featuring a cylindrical case with a support member that has a wider gap at one end portion, weakening the suction force for water droplets and incorporating protrusions for additional support, effectively preventing water infiltration while maintaining a simple and cost-effective design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a uniform small gap is maintained between the support member and case inner surface, then structural stability is improved, but water droplet infiltration increases due to capillary phenomenon
Solution Approach 1:
The support member features a non-uniform gap structure where the gap width varies along its length. Specifically, the gap is smaller at portions away from the substrate and larger at the portion near the substrate, creating different local properties to simultaneously ensure structural stability and prevent water infiltration
2Object-affected harmful factors
If temperature inside the case is increased to match outside temperature, then water droplet infiltration is suppressed, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention replaces the thermal control system (heating mechanism) with a purely mechanical/structural solution. By designing the support member with variable gap widths, the capillary suction force is reduced without requiring any active temperature control, thereby eliminating the need for additional parts and reducing manufacturing complexity
3Volume of moving object
If a uniform small gap is maintained between the support member and case inner surface, then compact design is improved, but electronic component reliability decreases due to corrosion
Solution Approach 1:
The support member implements spatially varying gap widths where the gap is smaller at distal portions (maintaining compactness) and larger at the portion near the substrate (preventing water infiltration and corrosion). This local differentiation allows both compact design and component reliability to be achieved simultaneously
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 effectively prevents water droplet movement towards the substrate, thereby protecting electronic components from corrosion and ensuring the reliability and affordability of the switch device.
Implementation Method 1
when water droplets adhere to the back side of the switch device due to dew condensation or the like, there is a concern that the water droplets infiltrate into the case through a gap between the inner surface of the case and the outer surface of the support member due to capillary phenomenon
Data Source
AI summary
An engine start switch includes a substrate on which electronic components are mounted, a case which is formed in a cylindrical shape by a peripheral wall portion surrounding the substrate and of which at least one end portion is opened, and a support member that supports the substrate in the case and extends toward the open end of the case from one end portion thereof supporting the substrate. The support member includes an outer surface that faces an inner surface of the peripheral wall portion with a gap interposed therebetween, and a gap at the one end portion of the support member is wider than a gap at other portions excluding at least the one end of the support member.