Mass Flow Controller False Output Suppression

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Solution Overview

Problem

Mass flow controllers inaccurately output non-zero fluid flow rates due to pressure fluctuations when the control valve is completely closed, leading to user misunderstandings and maintenance challenges, as the external output part displays false information indicating fluid flow despite no actual flow.

Innovation Solution

The flow rate control device ensures the external output part displays zero as the external output flow rate value when the control valve is completely closed, regardless of the measured flow rate value, and outputs the measured flow rate value at a certain point or after a predetermined period if the time variation of the measured flow rate value exceeds a certain threshold, thereby distinguishing between true flow and false detections caused by pressure fluctuations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If the external output part displays the measured flow rate value from the flow rate sensor, then the flow rate information is provided to the outside, but false information is output when pressure fluctuations occur after the control valve is closed

Engineering Contradiction:

Improveflow rate information outputVSAvoidaccuracy of flow rate output

Core Design Contradiction:

Loss of informationVSReliability

Solution Approach 1:

A determination unit is introduced as an intermediary between the flow rate sensor and the external output part. This determination unit monitors pressure fluctuations and decides whether to output the measured flow rate value or suppress it, thereby preventing false information from being displayed while maintaining accurate flow rate information output when conditions are normal

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system uses feedback from pressure fluctuation detection to control the external output. When pressure fluctuations are detected after valve closure, the system feeds back this information to suppress the flow rate output, creating a closed-loop control that prevents false information from being displayed

Inventive Principle:

Principle #23Feedback

2Quantity of substance

If the control valve is completely closed to stop fluid flow, then no fluid passes through the valve, but the flow rate sensor may still output non-zero values due to pressure fluctuations

Engineering Contradiction:

Improvefluid flow through valveVSAvoidflow rate measurement accuracy

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The determination unit performs preliminary detection of pressure fluctuations before the flow rate value is output. By detecting pressure changes in advance and taking preventive action to suppress the output, the system prevents false flow rate measurements from being displayed while maintaining accurate measurements when conditions are normal

Inventive Principle:

Principle #9Preliminary anti-action

3Productivity

If the external output part displays non-zero flow rate values in closed state, then flow rate data is provided continuously, but user misunderstanding and maintenance difficulties occur

Engineering Contradiction:

Improvecontinuous data outputVSAvoiduser understanding and maintenance

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

Instead of continuously outputting flow rate data regardless of conditions, the system inverts the approach by suppressing output when abnormal conditions (pressure fluctuations in closed state) are detected. This ensures that only reliable, meaningful data is displayed, making it easier for users to understand system status and perform maintenance

Inventive Principle:

Principle #13The other way round (Inversion)

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 solution prevents false information about fluid flow from being output, enhancing the credibility of the mass flow controller and allowing for accurate maintenance decisions by clearly indicating zero flow when the control valve is closed and distinguishing between actual and false flow rate measurements.

Implementation Method 1

a flow rate sensor that measures a flow rate of a fluid flowing in a flow channel

Methodology Applied

Scientific EffectFluid flow detection:

Implementation Method 2

a control valve, and a valve control part that controls an opening degree of the control valve

Methodology Applied

Scientific EffectValve control: Valve

Implementation Method 3

an external output part that outputs an external output flow rate value based on the measured flow rate value

Methodology Applied

Scientific EffectSignal output:

Data Source

PatentUS9304030B2Flow rate control device

Publication Date: 2016.04.05 HORIBA STEC CO LTD

AI summary

A mass flow controller comprises a flow rate measuring part that measures a flow rate of a fluid flowing in a flow channel and outputs a measured flow rate value, a control valve, a valve control part that controls an opening degree of the control valve based on an entirely-close command to entirely close the control valve compulsorily or a set flow rate value set as a target value, and an external output part that outputs an external output flow rate value based on the measured flow rate value to the outside, and at a time when the valve control part receives the entirely close command or zero as the set flow rate value, the external output part outputs zero as the external output flow rate value, irrespective of the measured flow rate value.