Intake Air Humidity Sensor Thermal Management

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Solution Overview

Problem

Existing measurement devices for intake air in internal combustion engines face challenges in accurately measuring humidity due to temperature differences between the humidity sensor and the intake air, and they also generate pressure losses due to the shape of the assembly supporting the humidity sensor.

Innovation Solution

A measurement device with a bypass housing and a heat discharge portion thermally bonded to the humidity detection element, where the humidity sensor is positioned to be close to the intake air temperature and the heat discharge portion is designed to efficiently dissipate heat, reducing temperature differences and minimizing pressure losses by optimizing the shape of the protrusions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the humidity sensor is integrated into the housing that protrudes toward the inner periphery of the intake duct, then the device structure is simplified and manufacturing is easier, but heat from the engine is transmitted to the humidity sensor through the housing, increasing the sensor temperature and reducing measurement accuracy

Engineering Contradiction:

Improvedevice structureVSAvoidhumidity detection accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The housing is divided into an upstream housing and a downstream housing that are separated by a predetermined distance, preventing direct heat transmission from the engine to the humidity sensor while maintaining structural integration

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A heat-resistant member is positioned between the humidity sensor and the upstream housing to block heat transmission from the engine to the sensor, allowing the sensor to operate at intake air temperature

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the assembly supporting the humidity sensor is separated from the housing and protrudes toward the inner periphery of the intake duct, then heat transmission from the housing to the humidity sensor is prevented, but a pressure loss is generated due to the rectangular cross-section of the assembly

Engineering Contradiction:

Improvetemperature control of humidity sensorVSAvoidpressure loss

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The assembly supporting the humidity sensor is designed with a streamlined shape that gradually increases in cross-sectional area from upstream to downstream, reducing flow separation and pressure loss compared to a rectangular cross-section

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If the cover includes two openings arranged along the flowing direction of the intake air, then foreign matter is prevented from entering the cover and the humidity sensor is protected, but the pressure loss cannot be efficiently suppressed

Engineering Contradiction:

Improveprotection of humidity sensorVSAvoidpressure loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The cover is designed with a streamlined shape that gradually increases in cross-sectional area from upstream to downstream, reducing flow separation and pressure loss while maintaining protection of the humidity sensor

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 improves the accuracy of humidity detection by aligning the humidity sensor's temperature with the intake air temperature and reduces pressure losses, ensuring precise measurements while minimizing heat-related malfunctions.

Implementation Method 1

a heat discharge portion being directly in contact with the intake air and being thermally bonded to the humidity detection element

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the heat discharge portion is designed to efficiently dissipate heat, reducing temperature differences

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS10444175B2Measurement device

Publication Date: 2019.10.15 DENSO CORP

AI summary

A measurement device includes a bypass housing placed at a position in the intake duct that introduces an intake air to an internal combustion engine and defining a passage through which a part of the intake air flowing through an interior of the intake duct passes, a flowing amount sensor measuring a flowing amount of the intake air passing through the interior of the bypass housing, a humidity detection element measuring a humidity of the intake air passing through a position in the vicinity of the bypass housing, and a heat discharge portion being directly in contact with the intake air and being thermally bonded to the humidity detection element.