JP3506040B2 - Gas security equipment - Google Patents

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 that secures 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 measures a large amount of flow, or when the gas meter has been used for an unusually long time, the gas passage is judged to be abnormal. Those that have a built-in security device that shuts off and secures safety are in widespread use.

In the flow rate measuring system of this type of gas safety device, a membrane type meter for measuring the flow rate from the volume passed through the meter within a predetermined time and an ultrasonic sensor at a predetermined time interval are operated to measure the instantaneous flow rate. A meter to measure is common.

A gas safety device using a conventional ultrasonic sensor will be described with reference to FIG. When measuring a normal gas usage amount, an operation signal is sent from the control circuit 4 to the ultrasonic sensor drive circuit 3 at a predetermined time interval to operate the ultrasonic sensor 1 and the instantaneous flow rate of the gas flowing in the flow path 2. To measure.
Then, the integrated gas usage is measured based on the instantaneous flow rate data returned from the ultrasonic sensor drive circuit 3. Also,
The control circuit 4 determines whether or not the measured amount of gas used is abnormal, and if it is determined to be abnormal, an operation signal is sent to the shutoff valve drive circuit 6 to close the shutoff valve 7 to stop the gas.

[0005]

However, in the flow rate measuring method using the ultrasonic sensor, there is a possibility that the zero point may shift due to the change with time of the ultrasonic sensor and the error in the flow rate measured value may gradually increase. there were.

[0006]

In order to solve the above problems, in the present invention, the shutoff valve of the gas passage is closed, the gas unused state is confirmed by the gas pressure, and the measured value at this time is set to the zero point. Correct the gap by that.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A gas safety device of the present invention drives a gas flow path for flowing a gas, an ultrasonic sensor for measuring a flow rate of the gas flowing through the flow path, and the ultrasonic sensor. Ultrasonic sensor drive circuit and provided in the flow path
A shut-off valve that shuts off the flow passage , a shut-off valve drive circuit that drives the shut-off valve, a pressure sensor that measures the pressure of the flow passage downstream of the shut-off valve, the shut-off valve, and the ultrasonic wave. A sensor and control means for controlling the pressure sensor ;
The output of the pressure sensor is constant after the shutoff valve is closed.
When the time is stable, adjust the zero point of the ultrasonic sensor.
It is provided with a zero-point correction means .

This makes it possible to correct the error in the flow rate measurement value of the ultrasonic sensor due to the change over time.

[0009]

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

(First Embodiment) FIG. 1 shows a first embodiment according to the present invention.
It is a block diagram which shows the gas security apparatus of FIG. The basic configuration is the same as the description of the conventional example, and the difference between the first embodiment and the conventional example is that a pressure sensor for measuring the pressure in the gas passage and a zero point correction means are added.

The shut-off valve drive circuit 6 receiving the signal from the control circuit 4 closes the shut-off valve 7. Then, the control circuit 4 monitors the gas pressure on the downstream side from the flow path 2 by the pressure sensor 8,
If the pressure is constant for a predetermined time, it is determined that there is no flow rate (see FIG. 2). Ultrasonic sensor 1 when no gas is used
By setting the zero point of the flow rate measured by the control circuit 4 as the zero point, the zero point correction of the gas safety device of the present invention becomes possible.

Of course, the zero point correction may be performed periodically, but it may be performed by learning control when the gas user does not use the gas frequently.

If the gas pressure on the downstream side suddenly drops during the zero point correction, gas pipe leakage or gas equipment may be used. In that case, the zero point correction may be interrupted. It may be a program.

[0014]

As described above, according to the gas safety apparatus of the present invention, since the flow rate when the gas is not used can be accurately measured, the zero point can be corrected, and the ultrasonic sensor is affected by the change over time. Without this, accurate flow rate measurement becomes possible.

[Brief description of drawings]

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

FIG. 2 is a characteristic diagram showing changes in gas pressure in the device.

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

[Explanation of symbols]

1 Ultrasonic sensor 2 channels 3 Ultrasonic sensor drive circuit 4 control circuit 5 Zero correction means 6 Shut-off valve drive circuit 7 Shut-off valve 8 Pressure sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-68451 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01F 1/00-9/02

Claims (3)

(57) [Claims] 1. A gas flow path for flowing a gas, and an ultrasonic sensor for measuring a flow rate of the gas flowing through the flow path,
An ultrasonic sensor drive circuit for driving the ultrasonic sensor,
A shutoff valve provided in the flow passage for shutting off the flow passage, a shutoff valve drive circuit for driving the shutoff valve, a pressure sensor for measuring a pressure of the flow passage downstream of the shutoff valve, A shutoff valve, control means for controlling the ultrasonic sensor and the pressure sensor, and zero point correction of the ultrasonic sensor when the output of the pressure sensor is stable for a certain period of time after the shutoff valve is closed. It includes a zero-point correction means, the periodically performs gas coercive zero point correction by the zero point correcting means
Security device. 2. A gas flow path for flowing gas, and the flow path
An ultrasonic sensor for measuring the flow rate of gas flowing through
An ultrasonic sensor drive circuit for driving the ultrasonic sensor,
A shutoff valve provided in the flow passage for shutting off the flow passage;
A shutoff valve drive circuit for driving the shutoff valve;
A pressure sensor that measures the pressure downstream of the shutoff valve
Controls the shutoff valve, the ultrasonic sensor and the pressure sensor
Control means to control the pressure after closing the shut-off valve.
If the output of the sensor is stable for a certain time, the ultrasonic wave
A zero point correction means for correcting the zero point of the sensor, The zero-point correction by the zero-point correction means is used less frequently.
A gas safety device to be used when there is no gas. 3. The value measured by the pressure sensor is suddenly lowered.
The method of claim 1 or 2, wherein the zero point correction is interrupted when it is lowered.
The gas safety device according to claim 2.