JP3124390B2 - Gas meter with automatic shut-off function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a gas meter having an automatic shut-off function capable of shutting off a gas when an abnormality occurs.

[0002]

2. Description of the Related Art Gas leak accidents have the danger of affecting not only property damage but also serious accidents involving human lives. In recent years, gas meters with an automatic shut-off function have been adopted.

A gas meter with an automatic shut-off function of this type will be described below with reference to FIG. Meter casing 1
Includes a seismic sensor 2, a pressure sensor 3, a shutoff valve 4, a shutoff valve return device 5, a flow sensor 6, a one-chip microcomputer 7, a battery 8, an alarm display device 9, and a control unit 10.
Is incorporated. In the gas meter with the automatic shut-off function having such a configuration, the one-chip microcomputer 7 of the control unit 10 has a function of operating the shut-off valve 4 to shut off the gas when the input data is judged to be abnormal. The one-chip microcomputer 7 usually incorporates programs for processing the following six abnormalities.

(1) The gas is shut off by judging an abnormal gas flow rate.

[0005] (2) The gas is shut off by judging abnormal use of the gas equipment for a long time.

(3) Gas is shut off at the time of a large earthquake by a signal from the seismic sensor.

(4) The gas is shut off when an abnormal decrease in the gas supply pressure is detected.

(5) Gas is shut off by an external signal from a gas leak alarm, an incomplete combustion alarm, or the like.

(6) An alarm is output when there is a suspicion of leakage from indoor piping using a function of measuring a gas flow rate.

[0010] These six basic functions are operated by a program of the one-chip microcomputer 7.

In the meantime, particularly with respect to the above item (6), a conventional detection algorithm for early detection of a small gas leak generated due to aging of indoor piping, etc., requires no gas within one day at midnight or the like. It is assumed that there is a certain period of unused time. Therefore, if the flow rate pulse signal output from the flow rate sensor 6 is not detected for a certain time (for example, one hour) or more, it means that no gas was used in that time zone, and at the same time,
It can be determined that there is no gas leakage from the indoor piping after the gas meter. However, if there is no time period during which no gas flows at all, it cannot be determined whether any gas appliance has been used or whether there is a gas leak. Therefore, for example, only when there is no time period of a certain period during which gas does not flow at all for a long period of one month, it is determined that there is a possibility of gas leakage in the indoor piping, and an alarm is output. It has become.

[0012]

As described above, the conventional gas meter with an automatic shut-off function is based on the premise that there is a certain time period during the day when no gas is used. If no gas exists, it cannot be determined whether the gas appliance has been used or a gas leak has occurred.

In particular, recently, a centralized system for supplying hot water from a single heat source unit to home heating, a fully automatic bath, a kitchen, a washroom, and the like has begun to spread, and customers using such a system have become widespread. In this case, since the ignition and extinguishing of the gas are repeated finely by an automatic device, the time period during which the flow of gas is completely stopped within a day is extremely short. Therefore, it is practically impossible to continuously secure a time period in which no gas is used for a certain period of time.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a gas meter with an automatic shut-off function capable of quickly outputting an accurate gas leak alarm.

[0015]

In order to achieve the above-mentioned object, the presence or absence of a leak is determined based on the state of formation of a flow rate pulse signal formed as the gas is consumed. The present invention provides a gas meter with an automatic shut-off function having a function of shutting off, when the pulse interval of the flow rate pulse signal is smaller than a set interval, a leak determination interrupting means for interrupting the determination of the presence or absence of a leak; And a leakage determination unit that determines that leakage has occurred when the integrated time during which the flow rate pulse signal is not formed in a state where the flow pulse signal is not formed does not reach the set time.

[0016]

In the gas meter with the automatic shut-off function according to the present invention, when the pulse interval of the flow rate pulse signal formed with the consumption of gas is smaller than the set interval, it is determined that the gas appliance is in use and whether there is a leak. Is interrupted, and when the accumulated time during which the flow rate pulse signal is not formed in a state where the interruption is not performed does not reach the set time, it is determined that the gas is leaking. Even if no gas is present, it is possible to detect small gas leaks caused by aging of indoor piping at an early stage.

[0017]

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

FIG. 1 is a block diagram showing a configuration in one embodiment of the present invention. In the figure, 10 is a control unit, 11 is a reed switch that detects the rotational movement obtained by the meter weighing means 17 in a magnetically non-contact manner and outputs it as a contact open / close signal, and 12 is a contact open / close of the reed switch 11. A flow pulse input circuit for converting a signal into an electric pulse signal; 13, a waveform shaping circuit for synchronizing a flow pulse signal output from the flow pulse input circuit 12 with an internal clock signal of the control unit; A flow pulse period discriminating circuit that outputs a pipe leakage check flow pulse to the microcomputer 16 only when the pulse interval of the pulse is longer than a predetermined value. Reference numeral 15 denotes a pulse interval of the output pulse of the waveform shaping circuit 13 which is smaller than a predetermined value. A pipe leak check mask signal to the microcomputer 16 is output only when the Leakage checking mask signal generating circuit, 16 is a microcomputer. Reference numeral 17 denotes meter metering means, 18 denotes a gas leak alarm input circuit for outputting a signal from an external gas leak alarm or the like to the microcomputer 16, and 19 outputs a signal from the vibration sensor 2 to the microcomputer 16. 20 is a pressure sensor input circuit for outputting a signal from the pressure sensor 3 to the microcomputer 16, 21 is a shutoff valve driving circuit for driving the shutoff valve 4, and 22 is a voltage of the lithium battery 8. A voltage drop judging circuit for detecting a drop, 23 is an LED for displaying a gas shutoff event, and 24 is a test switch for testing the shutoff function.

The flow pulse period discriminating circuit 14 and the pipe leak check mask signal generating circuit 15 constitute a leak judging means, and the microcomputer 16 constitutes a leak judging means.

Next, the operation of the above-structured apparatus will be described with reference to FIGS. The flow pulse input circuit 12 converts the mechanical opening / closing of the contact of the reed switch 11 into an electric signal, and outputs the electric signal to the waveform shaping circuit 13 and the microcomputer 16 as a flow pulse signal.
The waveform shaping circuit 13 inputs the flow rate pulse signal and shapes it into a pulse synchronized with the internal clock signal of the control unit 10, and converts the shaped flow rate pulse signal (shown in FIG. Output to The flow rate pulse period discriminating circuit 14 checks whether the pulse interval of the shaped flow rate pulse signal (hereinafter, simply referred to as a flow rate pulse signal when not particularly disturbing) is larger than a predetermined value. A flow pulse for pipe leak check (shown in FIG. 3B) is output to the microcomputer 16. If the pulse interval of the flow rate pulse signal is not larger than a predetermined value based on the signal from the flow rate pulse period discriminating circuit 14, the pipe leak check mask signal generation circuit 15 performs pipe leakage while the pulse continues. The check mask signal (shown at c in FIG. 3) is supplied to the microcomputer 1
Output to 6. FIG. 3D shows the timing of the pipe leak check. The period in which “interrupted” is written is regarded as the period in which the gas appliance is in use and gas is flowing, and the microcomputer 16 determines Interrupt the leak check. The period indicated by hatching is a period during which the microcomputer 16 performs a pipe leak check. The microcomputer 16 accumulates data for the period excluding the check suspension period, and checks only the period in which it is determined that the gas appliance is not used. If the time during which the flow rate pulse signal could not be detected exceeds the predetermined time, it is determined that there is no gas leakage from the pipe.

Next, referring to FIG. 4 showing a circuit of an embodiment of the waveform shaping circuit 13, the flow rate pulse period discriminating circuit 14, and the pipe leak check mask signal generating circuit 15, FIG.
The operation will be described with reference to the timing chart of FIG. The flow rate pulse signal output from the flow rate pulse input circuit 12 is input to the D terminal of the D-FF circuit 131 of the waveform shaping circuit 13, and similarly, at the rise of the internal clock CLK input to the CK terminal, the D-FF circuit 131 Q
The terminal output (signal A in FIGS. 4 and 5) becomes hi, and the next D-FF circuit 13 is output at the falling edge of the same internal clock CLK.
2 Q バ ー terminal output (signal B in FIGS. 4 and 5) is low
w, the AND circuit 133 outputs the internal clock C
A flow pulse signal (signal C in FIGS. 4 and 5) shaped into the same width at the same timing as LK is output. The flow rate pulse signal C is output from the flow rate pulse period determination circuit 14
-Input to the CK terminal of the 2-bit binary counter 151 of the FF circuit 141 and the pipe leakage check mask signal generation circuit 15. Therefore, the flow pulse signal C
At the rise of the Q terminal output signal D of the D-FF circuit 141 and Q _{1 of the} 2-bit binary counter 151.
The terminal output becomes hi. Since the signal D is input to the AND circuit 142 together with the internal clock CLK, the signal D
Becomes high, the internal clock CLK is output to the AND circuit 142.
And output to the CK terminal of the n-bit binary counter 144.

When the pulse interval (clock cycle) of the internal clock CLK is _tck , the flow rate pulse signal C
Is larger than t ₁ given by t ₁ = (2 ⁿ⁻¹ −1) · t _ck (1), the output of the Q _n terminal of the n-bit binary counter 144 becomes hi after the lapse of t _1. , A signal E (FIG. 6) is output from the AND circuit 145. The signal E is a 2-bit binary counter 151 of the pipe leakage check mask signal generation circuit 15.
Of the flow pulse signal C
If the pulse interval is greater than t _1, 2-bit binary it counter 151 to be reset by the signal E, Q ₂ output of 2 bits is entered following the flow pulse signal C binary I counter 151 is a hi No.
Therefore, the pipe leakage check mask signal generation circuit 15
Is not set, the output signal at the Q terminal remains low, and the pipe leakage check mask signal F
Is not output. In addition, since the output signal of the Q-bar terminal of the D-FF circuit 152 remains high, the signal E becomes A
The signal is output to the microcomputer 16 as a flow rate pulse G for pipe leakage check through the ND circuit 143.

Next, the pulse interval of the flow rate pulse signal C is t
If not greater than _{1, the} flow rate pulse signal C input to the CLR terminal of the n-bit binary counter 144
Resets before the time t ₁ elapses,
Since the signal E is not output, the flow pulse G for pipe leakage check is not output to the microcomputer 16. When the flow pulse signal C stops coming, the signal E (of FIG. 6) is output by the n-bit binary counter 144 after a lapse of t ₁ from the output of the last flow pulse signal C.
Is output. On the other hand, no signal is outputted E Since the pulse interval of the flow pulse signal C is not greater than t _1, 2-bit binary I counter 151 of the piping leakage check mask signal generating circuit 15 is not reset. The 2-bit binary counter 151 counts up with the flow pulse signal C, and at the rising edge of the second pulse of the flow pulse signal C (FIG. 6), the 2-bit binary counter 1
51 Q ₂ 'terminals become hi (in FIG. 6), D-FF
The circuit 152 is set, and the pipe leakage check mask signal F is output to the microcomputer 16. When the flow pulse signal C stops coming, the signal E (FIG. 6) is output by the n-bit binary counter 144 after the elapse of the time t ₁ from the output of the last flow pulse signal C (FIG. 6), and 2 bits are output. The binary counter 151 is reset. Subsequently, at the falling of the signal E, the D-FF circuit 152 is reset, and the pipe leakage check mask signal F
Becomes low (FIG. 6). While the pipe leak check mask signal F is high, the AND circuit 143 blocks the pipe leak check flow pulse G.

Therefore, according to the configuration of the above-described embodiment, the flow rate pulse signal having a pulse interval not larger than the period t ₁ determined by the internal clock period and the number of bits n of the n-bit binary counter 144 is deleted. , while the pulse interval outputs only high flow pulse signals than t ₁ to the microcomputer 16 as a pipe leak check flow pulses G, the pulse interval is detected the flow pulse signal not greater than t _1, a piping Since the leak check mask signal F is output to the microcomputer 16, the microcomputer 16 interrupts the pipe leak check during this time and turns off the pipe leak check mask signal F.
By restarting the time accumulation and the leak check again from the point of time, it is also possible to effectively check for gas leaks in domestic pipes where a large heat source unit is operating. In other words, if there is a flow rate equal to or higher than the reference value based on a certain gas flow rate, it is determined that a large heat source unit is used, and the leak check is temporarily suspended, and from the time when the flow rate becomes lower than the reference value By restarting the time accumulation and the leak check, it is possible to detect a gas leak in a home pipe in which a large heat source device is operating without error and quickly.

[0025]

As described above, according to the present invention, when the pulse interval of the flow rate pulse signal formed as the gas is consumed is smaller than the set interval, it is determined that the gas appliance is in use and whether or not there is a leak. Suspended, when the accumulated time during which the flow rate pulse signal is not formed in a state where the interruption is not performed does not reach the set time, it is determined that there is a leak. Even if it does not exist, it is possible to early detect a minute gas leak generated due to aging of the indoor piping or the like, so that an accurate gas leak alarm can be quickly output.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a main part.

FIG. 3 is a timing chart showing the overall operation.

FIG. 4 is a circuit diagram of one embodiment of the present invention.

FIG. 5 is a timing chart showing the operation of the circuit diagram.

FIG. 6 is a timing chart showing the operation of the circuit diagram.

FIG. 7 is a block diagram of a conventional device.

[Explanation of symbols]

 12 Flow rate pulse input circuit 13 Waveform shaping circuit 14 Flow rate pulse period discriminating circuit 15 Piping leak check mask signal generating circuit 16 Microcomputer 131, 132, 141, 152 D-FF circuit 133, 142, 143, 145 AND circuit 134, 153 NOT Circuit 144 n-bit binary counter 151 2-bit binary counter

Claims (1)

(57) [Claims] 1. A gas meter with an automatic shut-off function having a function of judging the presence or absence of a leak based on the state of formation of a flow rate pulse signal formed as the gas is consumed, and shutting off the gas flow when it is judged that a leak has occurred. In the above, when the pulse interval of the flow rate pulse signal is smaller than a set interval, a leak determination interrupting means for interrupting the determination of the presence or absence of a leak is formed, and the flow rate pulse signal in a state where the leak determination interrupting means is not interrupted is formed. A leak judging means for judging a leak when the accumulated time not performed does not reach a set time, wherein the gas meter has an automatic shut-off function.