JP2000111043A - Gas safety apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure a flow rate by theoretically confirming a state of an unuse of a gas, measuring the flow rate of the gas unused state, setting the measured value to a zero point, and correcting a deviation from the zero point. SOLUTION: An operation signal is sent from a control circuit 4 to an ultrasonic sensor driving circuit 3 at a predetermined time interval to operate an ultrasonic sensor 1. Then, an instantaneous flow rate of the gas flowing through a channel 2 is measured, and an integrated gas used amount is measured based on data of the instantaneous flow rate. The lowest flow rate of the integrated used gas is recoded as a flow rate at the time of unusing the gas during a zero-point measuring period set by a zero-point correcting means 5 for a predetermined period. After the zero point measuring period, the recorded flow rate at the time of unusing the gas is set by the circuit 4 as a zero point of the flow rate to be measured by the sensor 1 so that the zero point correction of the gas safety apparatus can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures a gas flow rate and shuts off a gas passage when an abnormal flow rate is measured.
The present invention relates to a gas safety device for ensuring safety in using gas.

[0002]

2. Description of the Related Art In recent years, when a gas meter for measuring the amount of gas used has measured a large amount of flow or has been used for an unusually long time, it is determined that an abnormality has occurred and the gas passage is determined. The one with a built-in security device that shuts off and ensures safety is widely used.

[0003] In this type of flow rate measurement system for a gas safety device, a membrane-type meter that measures the flow rate from the volume that has passed through the meter within a predetermined time, and an ultrasonic sensor that operates at a predetermined time interval to measure the instantaneous flow rate. Meters for measuring are common.

A conventional gas safety device using an ultrasonic sensor will be described with reference to FIG. In the figure, when measuring a normal gas consumption, an operation signal is sent from the control circuit 4 to the ultrasonic sensor driving circuit 3 at a predetermined time interval, and the ultrasonic sensor 1 is operated to operate the gas flowing through the flow path 2. Measure the instantaneous flow rate. Then, the integrated gas usage is measured based on the instantaneous flow rate data returned from the ultrasonic sensor driving circuit 3. Further, the control circuit 4 determines whether or not the measured gas usage is abnormal, and when it is determined to be abnormal, sends an operation signal to the shut-off valve drive circuit 6 to close the shut-off valve 7 and stop the gas.

[0005]

However, in the flow rate measuring method using the ultrasonic sensor, there is a problem that the zero point shifts due to a temporal change of the ultrasonic sensor and the like, and the error of the flow rate measured value may gradually increase. there were.

[0006]

In order to solve the above-mentioned problems, in the present invention, a state where gas is not used is theoretically confirmed, a flow rate in a state where gas is not used is measured, and this measured value is set to a zero point. This corrects the deviation from the zero point. This enables accurate flow measurement.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the gas safety device according to the first means of the present invention, since there is usually a period in which gas is not used for several hours a day, it is necessary to record the minimum flow rate in a predetermined period. Thus, the flow measurement value when gas is not used can be accurately measured, and the zero point can be corrected by setting the minimum flow rate as data when gas is not used.

[0008] The gas safety device according to the second means of the present invention utilizes the fact that the pressure in the gas passage is generally higher when the gas is not used than when the gas is used due to the change in ambient temperature. Then, the maximum value of the pressure in the gas passage when using a gas having a flow rate equal to or higher than a predetermined flow rate is recorded. Zero point correction can be performed by setting the flow rate measured when the pressure is equal to or higher than the maximum value as data when gas is not used.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram showing a gas safety apparatus according to the first means of the present invention. The basic configuration is the same as that of the description of the conventional example, and the difference between the present embodiment and the conventional example is that zero point correcting means is added. In the zero point correcting means according to the first means of the present invention, a predetermined period is set as a zero point measuring period, and a minimum flow rate measured by the ultrasonic sensor 1 during this period is recorded as a flow rate when gas is not used. Then, by setting the flow rate when the gas is not used recorded after the zero point measurement period as the zero point of the flow rate measured by the ultrasonic sensor 1 in the control circuit 4, the zero point correction of the gas safety apparatus of the present invention becomes possible. .

(Embodiment 2) FIG. 2 is a structural view showing a gas safety apparatus according to the second means of the present invention. The basic configuration is the same as that of the conventional example. The difference between the present embodiment and the conventional example is that a pressure sensor for measuring the pressure in the gas passage and a zero point correcting means are added. In the zero point correcting means according to the second means of the present invention, first, the pressure in the gas passage is measured by the pressure sensor 8 during normal gas use, and the maximum value of the measured pressure is recorded. Next, when a pressure equal to or higher than the maximum value is measured during the zero point correction period, the flow rate in the flow path 2 is measured by the ultrasonic sensor 1, and the measured value is set as the zero point of the ultrasonic sensor 1 by the control circuit 4. By doing so, the zero point correction of the gas safety device of the present invention becomes possible. Further, the pressure in the gas passage after the measurement was measured again to confirm that the gas was not used during the measurement.

[0012]

As described above, according to the gas safety device according to the first means of the present invention, the flow rate when the gas is not used can be accurately measured, so that the zero point can be corrected, and the ultrasonic sensor can change over time. It is possible to measure the flow rate accurately without being affected by such factors.

According to the gas safety device of the second means of the present invention, in addition to the effect of the first means, there is no influence of gas pipe leakage, so that more accurate zero point correction can be performed. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a gas security device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a gas safety device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a conventional gas safety device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic sensor 2 Flow path 3 Ultrasonic sensor drive circuit 4 Control circuit 5 Zero correction means 6 Shutoff valve drive circuit 7 Shutoff valve 8 Pressure sensor

Claims (2)

[Claims] 1. A flow path for flowing a gas, an ultrasonic sensor for measuring a flow rate of the gas flowing through the flow path, an ultrasonic sensor driving circuit for driving the ultrasonic sensor, and recording a minimum flow rate for a predetermined period. In addition, zero point correction means for setting the minimum flow rate as data when gas is not used, a shutoff valve for shutting off a gas passage when an abnormality occurs, a shutoff valve driving circuit for operating the shutoff valve, and the shutoff valve And a control circuit for controlling the ultrasonic sensor. 2. A flow path for flowing a gas, an ultrasonic sensor for measuring a flow rate of the gas flowing through the flow path, an ultrasonic sensor driving circuit for driving the ultrasonic sensor, and a gas passage in the gas security device. Record the pressure sensor that measures the pressure and the maximum value of the pressure in the gas passage when using a gas with a flow rate equal to or higher than the predetermined flow rate. Zero point correction means for setting the flow rate measured when the pressure in the passage is equal to or higher than the maximum value as data when the gas is not used, a shutoff valve for shutting off the gas passage when an abnormality occurs, and for operating the shutoff valve And a control circuit for controlling the shut-off valve and the ultrasonic sensor.