Pressure Sensor Stepped Interface Prevents Resin Peeling
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Solution Overview
Problem
Existing pressure sensors for evaporated fuel leak detectors face challenges in ensuring airtightness due to potential peeling at the interface between the case and the sealing resin, which can compromise the detection accuracy and reliability.
Innovation Solution
The pressure sensor design includes a sensor unit with a pressure receiving portion, a case having a fluid flow path, and a sealing resin that covers the mold resin portion, with a stepped or inclined inner wall surface to prevent peeling and maintain airtightness, ensuring that only the interface between the case and the sealing resin is exposed externally.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing resin is used to seal the sensor unit in the case, then airtightness is improved, but peeling occurs at the interface between the case and sealing resin
Solution Approach 1:
The patent introduces a stepped surface that creates a multi-level interface structure. The first surface is positioned at a different height than the second surface, transforming a single-plane sealing interface into a multi-dimensional structure. This dimensional change prevents peeling by distributing stress across different levels and creating mechanical interlocking between the case, sealing resin, and sensor unit.
Solution Approach 2:
The sealing interface is divided into two distinct surfaces: a first surface for sealing between the case and sealing resin, and a second surface for sealing between the sensor unit and sealing resin. This segmentation separates the sealing functions into distinct zones, preventing peeling from propagating across the entire interface and maintaining localized sealing integrity.
2Ease of manufacture
If the sensor unit is exposed to external environment, then ease of installation is improved, but electromagnetic noise and heat sources affect detection accuracy
Solution Approach 1:
The sensor unit is nested within the case, creating a hierarchical structure where the case serves as a protective enclosure. The sealing resin fills the space between the sensor unit and case, providing both mechanical support and environmental isolation. This nesting arrangement shields the sensitive sensor unit from external electromagnetic noise and heat sources while maintaining a compact, easily installable configuration.
Solution Approach 2:
The sealing resin acts as an intermediary material between the sensor unit and the external environment. It provides electrical insulation to block electromagnetic noise, thermal isolation to reduce heat transfer, and mechanical coupling to secure the sensor unit in place. This intermediary layer protects the sensor unit from harmful external factors while maintaining functional integration.
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 effectively prevents peeling and maintains airtightness, enhancing the pressure detection accuracy and reliability of the evaporated fuel leak detector by isolating the sensor unit from external electromagnetic noise and heat sources.
Implementation Method 1
a pressure receiving portion (21) configured to detect a pressure of a fluid applied to a pressure receiving surface (210)
Implementation Method 2
a sealed cavity formed by the case (3) and the sealing resin (4) to house the sensor unit (2)
Data Source
AI summary
A pressure sensor for an evaporated fuel leak detector is used for checking a leak in a fuel tank and a canister. The pressure sensor includes a sensor unit, a case, and a sealing resin. The sensor unit has a pressure receiving portion, a plurality of conduction terminals, and a mold resin portion. The case is provided with a fluid flow path and a housing recess. The case has an annular inner wall surface that defines the housing recess and surrounds a side surface of the mold resin portion. The inner wall surface of the case is provided with a stepped surface that is parallel to the pressure receiving surface or is inclined by an internal angle of less than 90° with respect to the pressure receiving surface, in a cross section along a direction perpendicular to the pressure receiving surface.