Humidity Sensor Waterdrop Adherence Detection via Second-Order Differential

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Solution Overview

Problem

Humidity measurement devices in internal combustion engines face challenges in accurately determining the presence of waterdrops on humidity sensors, leading to reduced measurement accuracy and responsiveness due to the sensors' inability to differentiate between actual humidity changes and waterdrop adherence.

Innovation Solution

The implementation of a second-order differential calculation method to analyze humidity signals, allowing for precise determination of waterdrop adherence by identifying steep changes in humidity signal rates, thereby distinguishing between actual humidity changes and waterdrop occurrences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional humidity sensor is used to detect humidity, then the sensor can measure humidity levels, but waterdrops may adhere to the sensor surface causing measurement errors and reduced accuracy

Engineering Contradiction:

Improvehumidity measurement accuracyVSAvoidwaterdrop adhesion

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a hydrophobic coating as an intermediary layer between the humidity sensor surface and waterdrops in the intake air. This coating acts as a mediator that prevents waterdrops from adhering to the sensor surface while allowing the sensor to continue measuring humidity accurately through the coating layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful effect of waterdrop adhesion into a beneficial detection mechanism. By analyzing the electrical signal characteristics (impedance changes, capacitance variations) when waterdrops do adhere to the sensor, the system can detect waterdrop presence and distinguish it from actual humidity changes, thereby maintaining measurement accuracy.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Productivity

If the humidity sensor operates continuously in the intake air flow, then it can provide real-time humidity data, but it cannot differentiate between actual humidity changes and waterdrop adherence

Engineering Contradiction:

Improvereal-time measurement capabilityVSAvoidsignal differentiation capability

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The patent implements a feedback mechanism that continuously monitors the electrical signal characteristics of the humidity sensor. By analyzing changes in impedance, capacitance, or other electrical properties in real-time, the system can distinguish between signals caused by actual humidity changes and those caused by waterdrop adhesion, maintaining information integrity while providing continuous measurement.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent utilizes changes in electrical parameters (impedance, capacitance, conductance) of the sensor as waterdrops adhere to its surface. By monitoring these parameter changes alongside humidity readings, the system can differentiate between true humidity variations and waterdrop interference, preserving the ability to provide accurate real-time data.

Inventive Principle:

Principle #35Parameter changes

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 approach enhances the accuracy and responsiveness of waterdrop detection, enabling timely and precise identification of waterdrop adherence and elimination, thus improving the overall performance of humidity measurement in internal combustion engines.

Implementation Method 1

a humidity detection part to detect a humidity of the intake air

Methodology Applied

Scientific EffectHumidity sensing: Hygrometer

Implementation Method 2

a second-order calculation part to calculate a second-order differential value by performing a second-order differentiation by time on the humidity signal

Methodology Applied

Scientific EffectDifferential calculation:

Implementation Method 3

an adherence determination part to determine whether waterdrops adhere to a surface of a sensor element which is for detecting the humidity

Methodology Applied

Scientific EffectWaterdrop adhesion detection:

Data Source

PatentUS11143643B2Humidity measurement device, control device for internal combustion engine, and abnormality detection device

Publication Date: 2021.10.12 DENSO CORP

AI summary

A humidity measurement device is configured to measure a humidity of a gas. The humidity measurement device includes: a second-order calculation part to calculate a second-order differential value by performing second-order differentiation by time on a humidity signal output from a humidity detection part; and an adherence determination part to determine whether a liquid has adhered to the humidity detection part based on the second-order differential value obtained by the second-order calculation part.