Pressure Sensor Buffer Recess for Evaporated Fuel Leak Detection

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Solution Overview

Problem

Conventional pressure sensors for evaporated fuel leak detectors face challenges in maintaining accurate pressure detection due to the flow of sealing resin into the fluid flow path, which can affect the sensor's EMC performance and lead to damage from uneven fittings and high Young's modulus mold resins.

Innovation Solution

A pressure sensor design featuring a buffer recess and protruding cylinder portion at the housing recess's pressure receiving side, which prevents sealing resin from flowing into the fluid flow path and protects the mold resin portion, eliminating the need for concave-convex fitting structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sealing resin is filled in the housing recess to fix the sensor unit, then the sensor unit is securely fixed, but the sealing resin may flow into the fluid flow path and affect pressure detection

Engineering Contradiction:

Improvesensor unit fixationVSAvoidpressure detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The housing recess is segmented into two functional zones: a sensor unit accommodating region and a buffer recess. This segmentation allows the sealing resin to be contained in the buffer recess while preventing it from flowing into the fluid flow path, thus maintaining both secure fixation and accurate pressure detection

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The buffer recess acts as an intermediary structure between the sensor unit housing region and the fluid flow path. It serves as a barrier that intercepts any sealing resin that might otherwise flow into the fluid flow path, protecting the pressure detection function while allowing the sensor unit to be securely fixed

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If conventional housing recess design is used, then manufacturing is simple, but sealing resin may damage the mold resin portion due to uneven fittings and high Young's modulus

Engineering Contradiction:

Improvehousing recess structureVSAvoidmold resin portion integrity

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The buffer recess is designed to absorb and cushion the sealing resin before it can exert damaging forces on the mold resin portion. This beforehand cushioning prevents the high Young's modulus sealing resin from causing uneven fittings and damage to the mold resin portion, while maintaining manufacturing simplicity

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS11435259B2Pressure sensor for evaporated fuel leak detector

Publication Date: 2022.09.06 DENSO CORP

AI summary

A pressure sensor for an evaporated fuel leak detector is used for checking airtightness 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 has a fluid flow path and a housing recess. A buffer recess having an outer shape larger than the outer shape of a pressure receiving surface is formed at a pressure receiving side L1 of the bottom of the housing recess. Further, a protruding cylinder portion protruding into the buffer recess toward a back side L2 is formed at an outer edge of an opening end portion of the fluid flow path on the back side L2.