JP2004138541A - Flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flowmeter capable of using measurement data measured before the previous time when a flow rate abnormality with a low occurrence frequency is measured. <P>SOLUTION: This flowmeter has a flow sensor 2 for measuring the flow rate of a fluid, a central processor 3 for calculating the flow rate and the integrated value of the flow rate based on the measurement result by the flow sensor 2 and detecting an abnormality of the measurement result or arithmetic result, and a nonvolatile memory 6 for storing abnormality information with the measurement result or arithmetic result. An error display is performed by a display means 10 based on the abnormality information stored in the nonvolatile memory 6. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a flow meter that measures a flow rate while monitoring an abnormality that occurs instantaneously.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a heat-sensitive flow sensor using a heater has been used to measure the flow rate of city gas, LP gas, or a special medical gas (see Patent Document 1 below). This flow sensor has a configuration in which a heater and a temperature sensor are arranged on the surface of a bridge portion having a bridge structure formed on a semiconductor substrate. Among these, the temperature sensor is a heater that moves along the direction of gas flow. Located on both sides.
[0003]
Therefore, according to this flow sensor, the amount of change is provided on both sides of the heater by utilizing the fact that the temperature distribution of heat generated by passing a current through the heater changes according to the flow rate and flow velocity of the gas. It can be detected by a temperature sensor. That is, the flow rate of the gas can be obtained from the output of the temperature sensor.
By the way, such a flow sensor has higher detection sensitivity of the flow rate and the flow velocity than the gas flow meter which detects the flow rate based on the output pulse generated by the rotation of the rotating body so far, and the reliability of the measurement result of the gas flow rate is high. Is also expensive.
[0004]
[Patent Document 1]
JP-A-11-258022 (page 3, FIG. 2)
[0005]
[Problems to be solved by the invention]
However, in the conventional gas flow rate detection method using a flow sensor, since the detection sensitivity is high as described above, in addition to a normal abnormal signal, even if instantaneous noise with a low frequency of occurrence is generated, these are not detected. There is a problem that the measurement is continued as it is, and the processing of the measurement of the erroneous gas flow rate and the integration of the measured value is continued, and the integration result or the like is greatly deviated.
[0006]
The present invention has been made to solve such a conventional problem, and when a flow rate abnormality having a low frequency of occurrence is measured, the measurement data measured before the previous time can be used as the current data for integration, and the flow rate can be reduced. It is an object of the present invention to obtain a flow meter that displays an error indicating that the fluid flow rate cannot be measured when the abnormality continues.
[0007]
[Means for Solving the Problems]
A flow meter according to claim 1 of the present invention calculates a flow rate and an integrated value of a flow rate based on a flow sensor that measures a flow rate of a fluid, and a measurement result by the flow sensor, and calculates the measurement result or the calculation result. A central processing unit that detects an abnormality of the non-volatile memory, a nonvolatile memory that stores the abnormality information together with the measurement result or the calculation result, and a display unit that displays an error based on the abnormality information stored in the nonvolatile memory. It is characterized by having.
[0008]
This allows the administrator or the like to quickly take measures to avoid storing the flow rate value including the abnormal information and the integrated value based on the error display by the display means. Further, by storing the abnormality information in the nonvolatile memory, even if the power supply voltage is reduced or cut off for some reason, maintenance can be performed reliably and quickly using the abnormality information.
[0009]
The flowmeter according to claim 2 of the present invention, wherein the central processing unit has a serial interface for transmitting the abnormality information to the outside together with the measurement result or the calculation result. It is total.
Thereby, the abnormality of the flow meter can be transmitted to the remote information management unit and the abnormality can be promptly detected at the information management unit, and the maintenance and management of the flow meter can be more appropriately performed.
[0010]
In the flow meter according to claim 3 of the present invention, when the abnormality is a momentary abnormality, the central processing unit extracts the information of the operation result stored in the non-volatile memory before the last time, and measures the flow rate. The flowmeter according to claim 1, wherein the flowmeter is used for integration.
As a result, the flow rate value can be integrated without generating a large error even after the detection of the abnormality information.
[0011]
The flow meter according to claim 4 of the present invention is characterized in that, when the abnormality is a continuous abnormality, the central processing unit causes the display unit to display an error indicating that the flow rate cannot be measured. A flow meter according to claim 1.
Thus, safety measures such as stopping the flow rate measurement operation by the flow meter can be promptly taken based on the error display.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a flow meter according to the present invention will be described in detail with reference to FIGS. FIG. 1 is a block diagram illustrating a flow meter according to the present invention, and FIG. 2 is a flowchart illustrating a flow measurement procedure according to the present invention. Although a gas flow meter is described here as an example, the present invention can be similarly applied to flow meters for other fluids.
As shown in FIG. 1, a flow sensor 2 as a flow rate measuring unit is attached to a pipe 1 of a gas as a fluid. The flow sensor 2 has a configuration in which a heater and a temperature sensor are arranged on the surface of a bridge portion having a bridge structure formed on a semiconductor substrate, and the temperature sensors are provided on both sides of the heater along the direction of gas flow. Are located.
[0013]
Therefore, according to this flow sensor, the amount of change is provided on both sides of the heater by utilizing the fact that the temperature distribution of heat generated by passing a current through the heater changes according to the flow rate and flow velocity of the gas. Each can be detected by a temperature sensor. Therefore, the gas flow rate can be calculated based on the output value (potential difference) of each temperature sensor.
[0014]
The CPU (Central Processing Unit) 3 multiplies, for example, the flow rate measured by the flow sensor 2 and the cross-sectional area of the gas flow as a fluid, that is, the cross-sectional area in the pipe through which the gas flows, and performs the flow of the gas. Ask for.
Further, the CPU 3 calculates an integrated value of the flow rate based on the measurement result of the flow rate by the flow sensor 2, and detects an abnormality in the measurement result or the calculation result.
[0015]
The abnormality of the measurement result or the calculation result is instantaneously generated by a low-frequency noise generated by a failure of the flow sensor 2 itself or a low-frequency noise generated by an abnormal operation of each part of the circuit processing the flow rate information. including.
The CPU 3 detects the abnormality in the arithmetic processing, stores the abnormality detection result in a memory, or attaches information of the abnormality to the flow rate information and outputs the result to the outside.
[0016]
A battery 4 is provided to supply power to each part of the peripheral circuit (block) including the CPU 3, and a set voltage detection circuit 5 for detecting a battery voltage is connected to the battery 4.
The set voltage detection circuit 5 sets the minimum set voltage for guaranteeing the normal flow rate measurement operation to 2.5 V when the battery voltage is, for example, 3 V, and sets the minimum set voltage to 2.5 V when the battery voltage falls below 2.5 V. Outputs a signal, which can be displayed on a display through the CPU 3.
[0017]
The CPU 3 is connected to a data memory 6 composed of an EEPROM (Electrically Erasable Programmable Read Only Memory), which is a non-volatile memory. The data memory 6 temporarily stores the measured gas flow rate and the integrated value of the gas flow rate. Functions to write and hold.
[0018]
Therefore, even when the power supply is stopped, the data once written is retained without being erased. The CPU 3 has a data memory 7 such as a static RAM (Static Random Access Memory) for writing and reading the flow rate and the integrated value of the flow rate during the measurement of the gas flow rate, and a program for executing the arithmetic processing. Is connected to a program memory 8 composed of a non-erasable ROM (Read Only Memory) storing the same.
[0019]
In addition, the data memory 7 stores abnormal information of noise generated in the flow sensor 2 and peripheral circuits detected by the CPU 3 during measurement of the gas flow rate. Further, the data memory 6 periodically stores the abnormal information of the noise so that it can be used as history data at the time of maintenance.
[0020]
Further, a reset circuit 9 and a display 10 are connected to the CPU 3. For example, when the operation of the flow meter is stopped, the battery is replaced, and a reset signal is input, the reset circuit 9 sets the gas flow value held in the data memory 6 or its integrated value as an initial value, The addition of the newly measured flow value can be started.
[0021]
The display 10 as a display means displays an instantaneous gas flow rate during the flow rate measurement or during the stop of the measurement, an integrated value of the gas flow rate, and further, for example, a liquid crystal display (LCD) to display the abnormal information. Are used.
The CPU 3 is connected to a host computer of an information management department such as an information management center via the serial interface 11, and can output the flow rate value, the integrated value, or the abnormality information.
[0022]
The CPU 3 calculates the gas flow rate and the integrated value thereof, displays a measurement result of the flow rate and abnormal information of the calculation result of the integrated value, a display process for displaying a warning due to a low battery voltage, and a reset signal. The controller controls and executes a process of restarting integration of fluid measurement values based on the input of the data, a process of writing and reading data to and from the data memory 6, a process of transmitting and receiving data to and from an external host computer, and the like.
DC power (driving power) is supplied from the battery 4 as a power source to the flow sensor 2, the CPU 3, the set voltage detection circuit 5, the data memories 6, 7, the program memory 8, the reset circuit 9, and the display 10. .
[0023]
Next, the operation of the flow meter having the above configuration will be described.
First, at the start of measurement by the flow meter, power is supplied from the battery 4 to the CPU 3 and each of the peripheral circuits, the reset circuit outputs a reset signal, and the CPU 3 is started. At this time, since the data memory 6 does not record data such as integrated data of gas flow values, the display unit 11 does not display the flow value or the integrated value of flow.
[0024]
Here, when gas, which is a fluid, flows through the pipe 1, the flow sensor 2 detects the amount of change in the temperature distribution of the heat of the heater according to the gas flow rate with the temperature sensor, and obtains the obtained gas flow rate and the flow rate in the pipe. The flow rate is measured with high accuracy based on the cross-sectional area.
Further, the CPU 3 integrates the measured flow rates, stores the integration result in the data memory 7, and simultaneously displays the flow rate value and the integrated value on the display 10.
[0025]
Further, the CPU 3 periodically saves the integrated value of the flow rate together with the integrated time in the data memory 6 as a non-volatile memory to prevent the integrated value from being lost due to a power failure such as a power failure.
The CPU 3 also detects abnormal information (abnormal flow data) such as instantaneous noise included in the flow rate and the integrated value of the flow rate, and stores the abnormal information and the frequency of occurrence of the abnormal information in the data memory 6. Remember.
[0026]
At this time, the CPU 3 continues to monitor the abnormality information during the flow rate measurement as shown in the flowchart of FIG. 2 (step S1), and determines whether there is an abnormality in the flow rate measured value or the calculated value (step S2). ).
If there is an abnormality, it is checked whether the abnormality has been repeated m times, for example, 5 times in the same error item (step S3). Instead of (abnormality information), the data measured last time is used, and the subsequent flow rate values are integrated based on the data. Then, since the integration result is written to the data memory 6, it is possible to prevent a large deviation from occurring in the integration result.
The abnormality information and the number of occurrences can be monitored on the display 10. In addition, by performing necessary maintenance at a stage where the number of abnormalities exceeds m times, it is possible to early avoid flow measurement when the flow meter continues to fail.
[0027]
On the other hand, if the abnormality has occurred more than m times and n times, for example, 10 times in a row with the same error item, an abnormal data signal is output and displayed on the display 10 (step S4).
The display method by the display 10 can be a system down display by lighting up the entire liquid crystal screen, a blinking lamp, or an audio output. Such a system down display is held in the data memory 6 (step S5), transmitted to the host computer of the external information management section through the interface 11, and reliably notified to the administrator through the host computer. You.
[0028]
As a result, an administrator who monitors the system display on the display 10 or the system down display on the information management section side notices these displays and notifications, and utilizes the flow sensor data while utilizing the history data in the data memory 6. 2 and the peripheral circuits can be quickly maintained. As a result, it is possible to avoid measurement and accumulation of the flow rate information while the abnormality has occurred.
[0029]
In the above-described embodiment, detection of abnormal information with a low frequency of occurrence such as noise has been described. However, detection of normal abnormal information that continuously occurs can be performed in a similar procedure. When the flowmeter is separately installed in a flow rate measuring section and a display section, the CPU 3, the data memories 6, 7 and the program memory 8 may be provided for each of the flow rate measuring section and the display section.
[0030]
【The invention's effect】
As described above, according to the flow meter of the present invention, the central processing unit calculates the flow rate and the integrated value of the flow rate based on the measurement result by the flow sensor, and detects the abnormality of the measurement result or the calculation result. The abnormality information is stored in a non-volatile memory together with the measurement result or the calculation result, and the calculation result and the abnormality information are displayed on a display means. In addition, it is possible to quickly take measures to avoid storing the flow value including the abnormality information and the integrated value thereof.
In addition, by storing the abnormality information in the nonvolatile memory, even if the power supply voltage is reduced or cut off for some reason, maintenance can be performed reliably and quickly using the abnormality information.
[0031]
Further, by providing the central processing unit with a serial interface for transmitting the abnormality information to the outside together with the measurement result or the computation result, the central processing unit transmits the abnormality of the flow meter to a remote information management unit, and The abnormality detection in the department can be promptly performed, and the maintenance and management of the flow meter can be more appropriately performed.
Further, when the abnormality is an instantaneous abnormality, the central processing unit extracts the information of the operation result stored in the nonvolatile memory before the last time and makes it available for the integration of the flow rate. Can be integrated without generating a large error even after the detection of.
[0032]
Further, when the abnormality is a continuous abnormality, the central processing unit causes the display means to display an error indicating that the flow rate cannot be measured, and based on the error display, stops the flow rate measurement operation by the flow meter. Safety measures can be taken promptly.
[Brief description of the drawings]
FIG. 1 is a block diagram showing one embodiment of a flow meter of the present invention.
FIG. 2 is a flowchart showing a flow measurement procedure according to the present invention.
[Explanation of symbols]
2 Flow sensor 3 CPU (Central processing unit)
6. Data memory (non-volatile memory)
10 Display (display means)

Claims (4)

A flow sensor that measures the flow rate of the fluid, a central processing unit that calculates a flow rate and an integrated value of the flow rate based on the measurement result by the flow sensor, and detects an abnormality in the measurement result or the calculation result; A flowmeter, comprising: a non-volatile memory that stores the abnormality information together with a result or a calculation result; and a display unit that displays an error based on the abnormality information stored in the non-volatile memory. The flowmeter according to claim 1, wherein the central processing unit has a serial interface that transmits the abnormality information to the outside together with the measurement result or the calculation result. The said central processing unit, when the said abnormality is an instantaneous abnormality, takes out the information of the operation result saved in the non-volatile memory before the last time, and uses it for integration of the flow rate. The flow meter according to 1. The flowmeter according to claim 1, wherein the central processing unit causes the display unit to display an error indicating that the flow rate cannot be measured when the abnormality is a continuing abnormality.

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