Pressure Sensor Sealing Resin Thermal Stress Shielding

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Solution Overview

Problem

Existing pressure sensors for evaporated fuel leak detectors are susceptible to errors due to thermal stress and electromagnetic noise, which affect the accuracy of pressure detection.

Innovation Solution

A pressure sensor design featuring a sensor unit with a mold resin portion and a sealing resin filled in a housing recess, where the sealing resin covers the mold resin portion and has a uniform thickness, preventing electromagnetic noise and heat from reaching the sensor unit and reducing thermal stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the sensor unit is exposed to the outside environment, then ease of assembly is improved, but the sensor unit becomes susceptible to electromagnetic noise and heat from surrounding components

Engineering Contradiction:

Improveease of assemblyVSAvoidelectromagnetic noise and heat

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent uses a sealing resin to create a flexible sealing structure that covers the sensor unit. This resin layer acts as a protective barrier that blocks electromagnetic noise and heat from reaching the sensor unit while maintaining a compact integrated structure. The sealing resin fills the housing recess and conforms to the sensor unit's contours, providing effective shielding without requiring complex rigid enclosures.

Inventive Principle:

Principle #30Flexible shells and thin films

2Adaptability or versatility

If the sealing resin thickness is varied, then adaptability to different sensor units is improved, but thermal stress distribution becomes non-uniform affecting pressure detection accuracy

Engineering Contradiction:

Improveadaptability to sensor unitsVSAvoidpressure detection accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent employs a housing recess with specific geometric features including an inclined surface and a vertical surface that work together to control the sealing resin thickness. The inclined surface gradually transitions to the vertical surface, creating a controlled thickness profile that ensures uniform thermal stress distribution across the sensor unit while maintaining adaptability to different sensor geometries. This local geometric quality control ensures consistent thermal stress characteristics.

Inventive Principle:

Principle #3Local quality

3Device complexity

If the housing recess has a simple geometry, then manufacturing complexity is reduced, but the sealing resin cannot provide uniform thermal stress distribution

Engineering Contradiction:

Improvehousing recess geometryVSAvoidpressure detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The housing recess is segmented into distinct functional surfaces: an inclined surface that guides the sealing resin and a vertical surface that defines the final resin thickness. This segmentation allows each surface to perform its specific function in controlling resin distribution and thermal stress uniformity. The inclined surface facilitates gradual resin filling while the vertical surface ensures consistent thickness, achieving uniform thermal stress distribution without requiring complex three-dimensional geometries.

Inventive Principle:

Principle #1Segmentation

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 design enhances the accuracy of pressure detection by minimizing errors caused by thermal stress and electromagnetic interference, improving the overall performance of the pressure sensor.

Implementation Method 1

the sealing resin filled in the housing recess covers a surface of the mold resin portion arranged in the housing recess... it is difficult for electromagnetic noises or heat generated from the motor of the pressure reducing pump and the solenoid noise of the solenoid valve arranged around the pressure sensor of the decompression leak check module, to reach to the sensor unit from the back side of the sensor unit

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 2

when the pressure sensor is heated, the thermal stress applied from the sealing resin to the pressure receiving portion of the sensor unit becomes more uniform. Therefore, the pressure detection of the pressure receiving portion is less affected by the thermal stress

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS11493402B2Pressure sensor for evaporated fuel leak detector

Publication Date: 2022.11.08 DENSO CORP

AI summary

A pressure sensor for an evaporated fuel leak detector 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 has a fluid flow path and a housing recess. Each remaining inner wall surface of the housing recess except for an inner wall surface on the conduction terminal side is provided with an inclined surface and a vertical surface, in a cross section along an axial direction perpendicular to a pressure receiving surface of the sensor unit. The inclined surface is inclined inward as toward a pressure receiving side. The vertical surface extends from the end of the inclined surface on the pressure receiving side to define a filling gap in which the sealing resin is filled between the side surface of the mold resin portion and the vertical surface.