Pressure Sensor Sealing Adhesive Waterproofing
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Solution Overview
Problem
Conventional pressure sensors for fluid pressure detection, such as refrigerant pressure sensors, face issues with waterproofness and airtightness due to the expansion and contraction of O-ring or packing materials under heat shock and freezing/thawing, leading to water ingress and malfunction.
Innovation Solution
The use of a sealing adhesive without an atmosphere-side O-ring or packing, where the adhesive is filled in one direction to improve workability and ensure waterproofness and airtightness, with features like a straight or narrowed portion at the opening of the protective cover and a swaging spacer for enhanced sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If O-ring or packing materials are used to ensure waterproofness and airtightness, then sealing performance is improved, but reliability deteriorates due to expansion and contraction under heat shock and freezing/thawing conditions
Solution Approach 1:
The invention removes the O-ring or packing from the sealing structure and replaces it with a sealing adhesive. The sealing adhesive is applied to the mating surface of the case, eliminating the need for elastomeric sealing components that are susceptible to thermal expansion and contraction. This extraction of the problematic O-ring component directly resolves the contradiction by maintaining sealing reliability without dimensional instability.
Solution Approach 2:
The invention changes the material parameter from elastomeric O-ring/packing to adhesive material. The sealing adhesive maintains its sealing properties across a wide temperature range without the expansion and contraction behavior characteristic of elastomeric materials. This parameter change in material selection resolves the contradiction between maintaining waterproofness/airtightness and avoiding dimensional instability under thermal cycling.
2Reliability
If multiple adhesives are used to fill openings in different orientations, then airtightness is maintained, but ease of manufacture deteriorates due to complex application processes
Solution Approach 1:
The invention merges the sealing function into a single adhesive application step by applying sealing adhesive to the mating surface of the case. This consolidates what would otherwise require multiple adhesive applications in different orientations into one unified sealing operation. The merging of sealing functions resolves the contradiction by maintaining airtightness while dramatically improving ease of manufacture.
Solution Approach 2:
The sealing adhesive performs multiple functions simultaneously: it provides waterproofing, airtightness, and structural bonding in a single application. This universal sealing approach eliminates the need for specialized adhesive applications for different orientations, resolving the contradiction between maintaining reliability and improving manufacturability.
Data Source
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AI summary
The present invention aims to provide a pressure sensor (100) capable of improving waterproofness and airtightness by using a sealing adhesive (136) without the use of an atmosphere-side O-ring or packing and improving workability by filling the sealing adhesive (136) in one direction. In the pressure sensor (100), a protective cover is formed by any combination of a joint (111), a lower cover (112), a pressure detection unit (120), and a case portion (135). The protective cover includes a side wall forming an outer periphery and a bottom on the pressure chamber side of the side wall. An opening (135A) on a side of the protective cover opposite to the bottom is filled with the sealing adhesive (136) to maintain waterproofness and airtightness of a signal transmission unit (130).