JP4779198B2 - Gas security device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas security device that measures a gas flow rate and shuts off a gas passage when an abnormal flow rate is measured to ensure safety in using the gas.
[0002]
[Prior art]
In recent years, if a gas meter that measures the amount of gas used has been measured for a large flow rate or if it has been used for a long period of time that is not normal, it is judged as abnormal and the gas passage is shut off. The one with a built-in security device to ensure the safety is widespread.
[0003]
In this type of gas safety device flow rate measurement method, a membrane meter that measures the flow rate from the volume that has passed through the meter within a predetermined time is generally used. A conventional gas security device will be described with reference to FIG. Normally, when gas is used, the gas flows into the membrane flow rate measuring unit 12 of the meter, and a signal is transmitted to the control circuit 6 every time a certain volume flows. Based on this signal, the integrated gas flow rate is calculated to determine whether the gas flow pattern is abnormal. If it is determined that the gas flow is abnormal, a cutoff signal is sent to the cutoff valve drive circuit 4 and the cutoff valve 3 is shut off. Stop the gas. Furthermore, as a safety function, when an earthquake of a predetermined seismic intensity or higher occurs, the seismic device 7 detects a shake and shuts off the shut-off valve 3, and a gas sensor abnormality is detected by the pressure sensor 5 to give a warning. It has a function of taking out or shutting off the shut-off valve 3.
[0004]
[Problems to be solved by the invention]
However, with a conventional gas safety device that uses a membrane-type measuring unit, when performing a leak check on a pipe at the time of installing the gas safety device or at the start of gas use, a pressure gauge for leak check is required, and it takes time to check for leaks. There was a problem that it took.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention, the flow rate of gas is measured by an electronic flow rate measurement unit, thereby making it possible to instantaneously measure a minute flow rate, and checking for pipe leakage by comparing with the flow rate when the gas passage is shut off. Can be realized with a gas security device.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
This onset Ming Gas Safety device, by measuring the flow rate of the gas, and electronic flow measurement unit that can measure the instantaneous flow rate, and determining the control circuit whether the use condition of the gas is normal, abnormal The electronic flow measurement device comprises a shutoff valve that shuts off gas when it occurs, and a pipe leak check means that checks the pipe leak by measuring the flow rate when the gas passage is shut off and opened when the gas safety device is installed. The unit is composed of two ultrasonic sensors capable of transmitting and receiving and a measurement channel having a predetermined cross-sectional area, and measures the instantaneous flow rate by measuring the propagation time of the ultrasonic wave between the two ultrasonic sensors , and the pipe leak check means comprises a measurement mode when the pipe leak check, a high-precision measurement mode with improved measurement accuracy by increasing the high to the resolution of the clock frequency for measuring the propagation time And by, but with improved leak check of the accuracy of the pipe.
[0007]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0008]
Example 1
FIG. 1 is a block diagram showing a gas security device according to a first embodiment corresponding to the first means of the present invention. The basic configuration is the same as that of the conventional example, and the difference between the conventional example and the present example is that the electronic flow measuring unit 1 is provided as a flow measuring unit, and the pipe leakage check means 8 is added to the control circuit. . The electronic flow measuring unit 1 is configured by a sensor driven by electricity, and the sensor is configured such that an electrical signal output changes when the flow velocity of the gas flowing in the gas safety device changes. The electronic flow rate measurement unit can measure the gas flow rate instantaneously by checking in advance the correlation between the change in the sensor signal and the flow velocity of the gas flowing in the gas safety device. And since the cross-sectional area of the gas passage is known, the instantaneous flow rate of the gas passing through the gas safety device can be measured.
[0009]
Utilizing the fact that the instantaneous flow rate can be measured by this electronic flow rate measuring unit, in this embodiment, a minute leak check of the gas pipe can be performed in a short time. As a procedure for a pipe leak check, first, a pipe leak check means 8 in the control circuit 6 is activated by giving an instruction for a pipe leak check from the outside to the gas safety device. And after receiving the instruction | indication of a piping leak check, the shut-off valve 3 is closed by the instruction | indication from the control circuit 6, and the instantaneous flow volume A is measured in the state. Next, the shut-off valve is opened, and the instantaneous flow rate B is measured in that state. Here, the pipe leak check means 8 compares the instantaneous flow rate A and the instantaneous flow rate B. If the two flow values are equal, it is determined that there is no pipe leak, and if the two flow values are different, it is determined that there is a pipe leak. Then, a display indicating that there is a pipe leak is output to the display unit 2 composed of liquid crystal. In this way, in this gas safety device, the presence or absence of leakage in the gas pipe can be confirmed in a short time.
[0010]
(Example 2)
FIG. 2 is a block diagram showing a gas security device of Example 2 corresponding to the second means of the present invention. The basic configuration is the same as in the description of the first embodiment of the present invention. In this embodiment, the electronic measurement unit includes two ultrasonic sensors 9 capable of transmitting and receiving and a measurement channel 10 having a predetermined cross-sectional area. An ultrasonic measurement unit is provided. The ultrasonic measurement unit sends a start signal to the ultrasonic transducer 9 installed in the measurement flow path 10 through which the fluid flows, the ultrasonic sensor drive circuit 11 that drives the ultrasonic transducer 9, and the ultrasonic sensor drive circuit 11. The control circuit 6 is configured to output and measure the time during which the ultrasonic wave propagates between the two ultrasonic sensors. In this embodiment, the two ultrasonic sensors are switched, the propagation times of the ultrasonic waves from the upstream to the downstream and the downstream to the upstream of the fluid to be measured are measured, and the velocity v is obtained from (Equation 1). (However, the propagation time from upstream to downstream is t1, and the propagation time from downstream to upstream is t2.)
[0011]
v = L / 2 ((1 / t1)-(1 / t2)) (Formula 3)
By utilizing the fact that this ultrasonic flow rate measurement unit can measure both the normal flow and the reverse flow, in this embodiment, it is possible to check micro leaks on both the upstream side and the downstream side of the gas safety device in a short time. The procedure for the pipe leak check is the same as that of the first embodiment of the present invention. However, if the instantaneous flow rate when the shut-off valve is closed is A and the instantaneous flow rate when the shut-off valve is opened is B, there is no pipe leakage when A = B, and when A> B, the upstream side of the gas safety device is In the case of pipe leak, A <B, the downstream side of the gas safety device is judged to be pipe leak. Further, as shown in FIG. 3, the pipe leak detection accuracy is further improved by adopting a high-accuracy measurement mode having a measurement interval shorter than that at the time of normal flow rate measurement at the time of pipe leak check.
[0012]
(Example 3)
FIG. 4 is a diagram showing a measurement flow of the gas safety device according to the third embodiment corresponding to the third means of the present invention.
[0013]
The sing-around method in ultrasonic measurement is a method that improves the resolution of measuring the flow velocity of the measurement fluid by repeating transmission and reception of ultrasonic waves in the same direction for the measurement fluid a predetermined number of times and measuring the total propagation time. is there. In this embodiment, the measurement accuracy at the time of pipe leakage check is improved by changing the number of times of sing-around (number of S times) between high-precision measurement and normal measurement. In FIG. 4, A> B, and in the case of high-precision measurement, the number of times of single-around can be set, and the resolution of the flow rate measurement becomes high. Therefore, the pipe leak can be confirmed more accurately by measuring in the high-accuracy measurement mode at the time of the pipe leak check.
[0014]
(Example 5)
FIG. 5 is a diagram showing the state of the time measurement clock of the gas safety device corresponding to the fourth means of the present invention. As shown in the figure, by increasing the clock frequency in the high-accuracy measurement mode, the measurement resolution of the time during which the ultrasonic wave propagates between the ultrasonic sensors is increased, and reception can be confirmed closer to the true reception timing of the ultrasonic wave. For this reason, pipe leak can be more accurately confirmed by measuring in the high-accuracy measurement mode at the time of pipe leak check.
[0015]
【The invention's effect】
According to the gas safety system of the present onset light as described above, since the minute flow rate can be confirmed in a short time, it confirmed piping leakage in a short time only in gas safety device, without increasing nor sing around count measurement times Since measurement accuracy can be improved, a high-accuracy measurement mode can be realized with less current consumption.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a gas safety device in Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a gas safety device in Embodiment 2 of the present invention. FIG. 3 is a configuration showing measurement timing of the gas safety device. FIG. 4 is a configuration diagram showing a measurement flow of a gas safety device according to Embodiment 3 of the present invention. FIG. 5 is a configuration diagram showing a state of a time measurement clock of the gas safety device according to Embodiment 4 of the present invention. Configuration diagram showing a conventional gas safety device [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electronic flow measurement part 2 Accumulated flow display part 3 Shut-off valve 4 Shut-off valve drive circuit 5 Pressure sensor 6 Control circuit 7 Shock absorber 8 Pipe leak check means 9 Ultrasonic sensor 10 Measurement flow path 11 Ultrasonic sensor drive circuit 12 Film Type flow measurement unit

Claims (1)

An electronic flow measurement unit that can measure the instantaneous flow rate by measuring the gas flow rate, a control circuit that determines whether the gas is in normal use, and a shut-off that shuts off the gas when an abnormality occurs Equipped with a valve and pipe leak check means to check the pipe leak by measuring the flow rate when the gas passage is shut off and opened when installing the gas safety device,
The electronic flow rate measuring unit is composed of two ultrasonic sensors capable of transmitting and receiving and a measurement channel having a predetermined cross-sectional area, and measures the propagation time of the ultrasonic wave between the two ultrasonic sensors to obtain an instantaneous flow rate. measured, the pipe leak check means, as the measurement mode when the pipe leak check, high precision measurement mode gas safety that example Bei a with improved measurement accuracy raised higher to resolution clock frequency for measuring the propagation time apparatus.