Thermal Flow Sensor Tilt Angle Correction

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Solution Overview

Problem

Thermal flow sensors installed at varying angles in a flow path suffer from inaccurate flow rate measurements due to convection heat effects, which affect the output values from thermopiles, leading to inconsistent and inaccurate flow rate calculations.

Innovation Solution

A flow rate measurement device comprising a heating unit, temperature sensing units, an angle calculation unit, and a storage unit that corrects flow rates based on tilt angles, using pre-stored correction values to account for convection heat, ensuring accurate measurements regardless of sensor orientation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If thermal flow sensors are installed at varying angles in a flow path, then the device can be installed in different orientations, but the measurement accuracy deteriorates due to convection heat effects affecting thermopile output values

Engineering Contradiction:
Improveinstallation angle flexibilityVSAvoidflow rate measurement accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system performs preliminary action by measuring the tilt angle of the thermal flow sensor before flow rate measurement, and pre-stores correction values corresponding to different tilt angles. This allows the system to compensate for convection effects in advance, ensuring accurate measurements regardless of installation angle.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the parameter being measured by detecting the tilt angle of the sensor and selecting appropriate correction values from stored data. By varying the correction parameter based on tilt angle, the system maintains measurement accuracy across different installation orientations.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If thermal flow sensors are installed without angle correction, then the installation process is simplified, but convection heat causes inaccurate flow rate measurements

Engineering Contradiction:
Improveinstallation simplicityVSAvoidflow rate measurement accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The thermal flow sensor system performs self-correction by automatically detecting its own tilt angle and applying appropriate correction values from stored data. This self-service mechanism eliminates the need for manual angle adjustment or complex installation procedures while maintaining high measurement accuracy.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system automatically adjusts the measurement parameter by applying tilt-angle-specific correction values, transforming the raw thermopile output into accurate flow rate measurements without requiring manual intervention for angle compensation.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If tilt angle detection and correction mechanisms are added to thermal flow sensors, then measurement accuracy improves, but device complexity increases

Engineering Contradiction:
Improveflow rate measurement accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system introduces a tilt angle detection unit as an intermediary component that measures sensor orientation and uses a correction value storage unit as a mediator to provide pre-calculated correction factors. This intermediary approach adds minimal complexity while significantly improving measurement accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The correction values for different tilt angles are pre-calculated and stored in the correction value storage unit, performing the complex compensation calculation in advance. This preliminary action eliminates the need for real-time complex computations, keeping the device complexity low while maintaining high accuracy.

Inventive Principle:
Principle #10Preliminary action

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 device provides highly accurate flow rate measurements by accounting for convection heat effects and sensor tilt, improving measurement precision and stability across different installation angles.

Implementation Method 1

a heating unit for heating a fluid

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

temperature sensing units that are provided flanking the heating unit in the direction of fluid flow, and that sense the temperature of the heated fluid

Methodology Applied
Scientific EffectTemperature sensing:

Implementation Method 3

When a fluid is heated by a heater, convection may occur in the vicinity of the heater, whereby heat is carried upward with respect to the horizontal plane

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3751240B1Flow rate measurement device and embedded gas meter
Publication Date: 2023.06.14 OMRON CORP
  • EP3751240B1 patent drawingFigure 1~2
  • EP3751240B1 patent drawingFigure 3~4
  • EP3751240B1 patent drawingFigure 5~6B

AI summary

The flow rate measurement device according to one aspect of the present invention comprises a heating unit for heating a fluid; temperature sensing units that are provided flanking the heating unit in the direction of fluid flow, and that sense the temperature of the heated fluid; a flow rate calculation unit that calculates the flow rate of the fluid on the basis of a sensing signals outputted from the temperature sensing units; angle calculation unit for calculating the tilt angle of the temperature sensing units with respect to a specific reference plane; a storage unit that stores the relation between the flow rate, the tilt angle, and a flow rate correction value; and a flow rate correction unit that corrects the flow rate by using the flow rate correction value stored in the storage unit.