JPH0150420B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas cutoff device for preventing gas explosions that may occur due to various causes. The above-mentioned causes are, for example, abnormal outflow of gas due to disconnection of the rubber hose that connects the gas pipe and gas appliance, cracks in the rubber hose, etc. This is an abnormal outflow of raw gas, and also an abnormal outflow of raw gas after a misfire occurs due to a crack in a gas pipe caused by an earthquake or a gas appliance falling over. Explosions can be prevented by detecting these factors before they lead to a gas explosion and blocking the gas flow using a blocking means provided in the gas flow path.

As this type of gas cutoff device, one having the configuration shown in FIG. 4 can be considered. In the figure, 1 is a flow rate sensor attached to a gas meter 5 to detect the flow rate of gas. This sensor includes, for example, a combination of a magnet provided in a diaphragm in a gas meter or a part of a link mechanism that transmits the reciprocating motion of the diaphragm to a meter indicator, and a reed switch that detects the position of this magnet. One reciprocation of the diaphragm turns the reed switch on and off once. Diaphragm 1
Since the round trip flow rate is fixed as q, by measuring the time from the first turn on of the reed switch to the next turn on, it is possible to know the current flow rate of gas per unit time. . Alternatively, it is a sensor that detects an external abnormality that is not directly related to the gas flow itself, such as a seismic sensor that turns an attached switch on and off when it detects an earthquake, or a seismic sensor that outputs a predetermined signal when it detects raw gas above a certain concentration. There are gas sensors etc. that output. 3'' is a control unit that receives signals from the flow rate sensor 1 and the abnormality sensor 2 and processes these signals according to a predetermined processing procedure.For example, if the flow rate detected by the flow rate sensor 1 is constant If the flow continues at this value for more than a predetermined time, it means that the equipment corresponding to that flow rate has been used for much longer than the normal usage time, and such a condition should be considered as an indication of some kind of abnormality. , outputs a cutoff signal.Also, abnormality sensor 2
When a seismic sensor is used as a seismic sensor, the number of times the attached switch is turned on and off within a predetermined period of time is counted, and if the counted value is greater than or equal to a predetermined value, a cutoff signal is also output. This process distinguishes between seismic waves and malfunctions occurring in the seismic sensor, and is applied to respond only to seismic waves. The processing described above is a part of the processing procedure, which also includes a processing procedure for detecting an abnormal condition that, if left untreated, could lead to a gas explosion. Reference numeral 4 denotes a cutoff means that cuts off the gas flow when a cutoff signal is output from the control unit 3''.The cutoff means 4 includes, for example, a manual return type one-shot solenoid valve that combines a magnet and an electromagnetic coil. 5 is a gas meter, and gas is supplied to the gas meter 5 as Gi, and after passing through the gas meter 5, it is supplied as G to the consumer.

The control section of the gas cutoff device described above will now be explained in more detail with reference to FIG. 3B is an interface circuit between the signal from the flow rate sensor 1 and a counter 3C, which will be described later, and a typical example thereof is a chattering removal circuit. In other words, when the flow rate sensor 1 is constructed from a combination of a magnet and a reed switch as described above, the reed switch has chattering, and if this is input directly to the counter 3C, accurate on/off cannot be prompted.
Chattering needs to be removed. 3C is a counter, which is an interface circuit 3B for every fixed time t.
The flow rate pulses from the microcomputer 3i are counted and the counted value N is outputted to a microcomputer 3i, which will be described later.
Therefore, the counter 3C outputs the count value N to the microcomputer 3i at fixed time intervals t, and then
It is set by the microcomputer 3i and starts counting again. 3D is an interface circuit between the abnormality sensor 2 and the microcomputer 3i.
For example, if the abnormality sensor 2 is a vibration sensor that combines a microswitch and a ball, it is a microswitch chattering removal circuit. 3E is a clock pulse generator for the microcomputer 3i, and when the clock generator is built in the microcomputer 3i, it is composed of, for example, a crystal oscillator and other passive circuit components. 3i is a microcomputer that receives signals from counter 3C and interface circuit 3D, and stores its ROM in advance.
These signals are processed according to processing procedures stored in the section. Further, the time t is generated by counting the clock pulses from the clock pulse generator 3E. For example, the current gas flow rate Q _P is
It is recognized by dividing the count value N of the counter 3C by the time t, and whether or not the flow rate Q _P exceeds a predetermined time T _P is determined by the integration of the clock pulses from the clock pulse generator 3E since the flow rate Q _P starts flowing. Determination is made by comparison with the value. If a certain time
If more than T _P has passed, microcomputer 3
i outputs a cutoff signal to the cutoff means 4.
Further, the signal from the abnormality sensor 2 is transmitted for a predetermined time T ₂
To determine whether or not the clock has been turned on and off a predetermined number of times R or more within the specified period, count the on-off circuit R' and determine the elapsed time t _R from the first turn on by counting the _clock pulses _. The determination is made by comparing ' and R. 3G is a battery that serves as a power source for the control unit 3''.Although it is possible to obtain DC power from a commercial power source, a battery is used from the standpoint of safety and ease of installation.

The disadvantage of such a device is that flow rate pulses and abnormal sensor inputs are input irregularly, so the control unit 3''
must be in an operating state at all times, and therefore the battery 3G is likely to run out. In order to maintain operation for a predetermined period of time, the capacity of the battery must be increased, or the battery must be replaced after a short period of time.

The present invention solves the problems of the above-mentioned device, and while exhibiting the same functions as the above-mentioned device,
To provide a gas cutoff device which can lengthen the continuous operation time when the same battery is used and can lengthen the battery replacement period since the discharge of the battery is significantly reduced.

FIG. 1 is a block diagram of one embodiment of the present invention. 3 is a control unit related to the present invention. 3A is
An oscillator that oscillates at a constant frequency, whose output is
It is input to the standby return port iRQφ of the microcomputer 3F, which will be described later. The output of the counter 3C is input to the input port iφ of the microcomputer 3F, and the output of the interface circuit 3D is input to the second standby return port iRQ1 of the microcomputer 3F. 3F is a microcomputer as a judgment unit, which has a built-in ROM which is a storage unit for storing processing procedures, cut-off conditions, etc., and has a standby mode. It is possible to enter standby mode (ie, by instructions of a program stored in its RM portion). What is standby mode here?
This is a mode in which the main parts of the computer (CPU, RM, etc.) of the microcomputer 3F are stopped. During standby, the power supply current can be reduced to about one-third to several tenths of that during normal operation. Once the standby mode has been entered, returning to the original operating state is generally done by inputting an external signal to a specific port of the microcomputer 3F. This port is called the standby return port.
In this example, two standby return ports iRQφ,
Has 1.

Next, the operation of the above configuration will be explained using the timing chart for explaining the operation shown in FIG.

The oscillation frequency of the oscillator 3A is selected to be higher than the maximum value fsmax of the signal frequency from the flow rate sensor 1, and the flow rate measurement error caused by the asynchronous signals of the oscillator 3A and the flow rate sensor 1 is kept below the allowable value. It is set to be. In FIG. 2, A is the output of the oscillator 3A, B is the output of the interface circuit 3B, and the signal from the flow rate sensor 1 is pulsed. At time t1, an oscillation pulse from the oscillator 3A is input to the microcomputer 3F. As shown in FIG. 2D, the microcomputer 3F enters the normal operation mode RUN in response to this signal and reads the contents of the counter 3C. If the content of the counter is “φ”, at time t2 in software,
Enters standby mode STB. At time t3, the flow rate pulse is input to counter 3C, and counter 3
The content of C becomes "1". At time t4, oscillator 3
The oscillation pulse from A causes the microcomputer 3F to return to normal operation mode RUN, and then
The CPU operates and checks the contents of counter 3C.
Since the content is "1", the soft timer with that content starts operating and starts counting oscillation pulses from the oscillator 3A. If the oscillation frequency of the oscillator 3A is 10 Hz and the measurement time t is 60 seconds, it is sufficient to count 600 oscillation pulses. That is, inside the microcomputer 3F, processing is performed to initialize a soft timer and start a counting operation. After this, at t5, the required processing is completed again, and the process returns to standby mode STB. Thereafter, the same operation is repeated, and at time t6, when the 600th oscillation pulse after time t4 is input to the microcomputer 3F, the microcomputer 3F
is in the normal operation mode RUN, and the internal soft timer has reached 60 seconds, so the counter 3
Read the content “N” of C, and calculate the allowable duration Tmax for the flow rate “N” with this “N” as the flow rate.
It is derived from the table area of the ROM part and set in the second soft timer. Also, since the measurement has been completed, the microcomputer 3F
Reset C and prepare for the next measurement. After completing the above processing, the microcomputer 3F enters the standby mode STB again and waits for the next standby return signal (oscillation pulse or signal from the interface circuit 3D). When the oscillation pulse is input at time t7, the microcomputer 3F enters the normal operation mode, counts down the second soft timer, checks whether the content is "φ", and if it is "φ". , a cutoff signal is output as the duration time Tmax has exceeded. If it is not "φ", read the contents of the counter 3C. If the content is "φ", end the process without doing anything,
If it is "1", the first soft timer for flow rate measurement is started, the process is ended, and the process returns to standby mode STB. If, during standby, the input from the abnormality sensor 2 is input via the interface circuit 3D at time t8 as shown in FIG. Continue and monitor.
Assuming that the cutoff condition is two or more on/off cycles within 1 sec, in the case of FIG. 2, there are two on/off cycles within 0.3 sec, so the microcomputer 3F outputs a cutoff signal. Assuming that the current driving condition for the cutoff means 4 is continuous driving for 0.2 seconds, the microcomputer 3F changes the cutoff output to the second cutoff output from time t9 when the first oscillation pulse is input after determining that the cutoff condition is satisfied until two oscillation pulses arrive. Outputs as shown in figure 2 and returns to standby mode after this output.
Return to STB. Now, let tcy be the execution time of one instruction of the microcomputer 3F determined by the clock pulse generator 3E, and let tcy be the average number of instructions executed each time an oscillation pulse is input, then the average processing time t _P
becomes tcy×. If the period of the oscillation pulse (0.1 sec in the above example) is T, the average current consumption _DD of the microcomputer 3F is: _DD = I _DS (ID) + I _DR・DI _DS : When the microcomputer 3F is on standby Current I _DR : Current during normal operation of the microcomputer 3F D: tcy×M/-/T Now, if tcy×<T, then D<1, and generally I _DS < I _DR , so _DD < I _DR . . In commonly available microcomputers, tcy is several tens of microseconds,
With the processing described above, t _P =tcy× will never exceed T in several hundred steps at most. In the above explanation, the input state from the abnormality sensor 2 is, for example, turned on and off twice or more within 1 sec, but it is also assumed that the on time and off time are predetermined times t _ON and t _OFF.
By applying the above restrictions, the ability to discriminate between noise and true abnormal signals can be improved. If t _ON , t _OFF < (oscillation pulse period), oscillator 3
By using a soft timer that counts the number of clock pulses from the clock pulse generator 3E, which has a much higher frequency than the oscillation pulse frequency from A, it is possible to create a timer that is shorter than the period of the oscillation pulses, so it is possible to monitor the on-off time. .

In this embodiment, an abnormality signal is input to the standby return port of a microcomputer with a standby function, so when there is no abnormality signal, the microcomputer only needs to process each oscillation pulse of the flow rate sensor output, and can operate normally at all times. Compared to devices that monitor the presence or absence of abnormal signals, the current consumption of the microcomputer can be significantly reduced. Further, since the microcomputer is returned to the normal operation mode upon generation of the abnormal signal, the signal can be continuously monitored from then on, and the same functions as a device normally operating can be obtained.

FIG. 3 is another embodiment of the present invention in which a microcomputer having only one standby return port is used. Microcomputer 3
F′ has the only standby return port iRQ and also has a built-in event counter. This counter operates even in standby mode STB, and the output of the interface circuit 3B is input to the input port Tci of this counter. The oscillation pulse of the oscillator 3A output is input to the input port iφ of the microcomputer 3F'.
It is also input to one of the R gates 3H. The output of the interface circuit 3D is the input port i1 of the microcomputer 3F.
It is also input to the other R gate 3H. The output of the R gate 3H is input to the standby return port iRQ of the microcomputer 3F'.

With the above configuration, each time an oscillation pulse is output from the oscillator 3A, the standby return port iRQ of the microcomputer 3F' is output via the R gate 3H.
, the microcomputer 3F' returns from the standby mode STB to the normal operation mode RUN each time. In addition, the output from the abnormality sensor 2 is sent to the microcomputer 3 via the interface circuit 3D and from the R gate 3H.
Since the signal is input to F', the microcomputer 3F' can return from standby mode to normal operation mode each time. As described above, the processing contents within the microcomputer 3F' are different depending on whether the recovery is caused by a signal from the oscillator 3A or the case where the recovery is caused by a signal from the abnormality sensor 2. Therefore, the microcomputer 3F' recognizes the cause of return to standby by checking the signal input states of the input ports iφ, i1. The microcomputer 3F' therefore determines which process should be performed and performs the appropriate process. After that, it will go back to standby mode and wait for the next return signal.

In this embodiment, even if a microcomputer with only one standby return port is used,
The same reduction in current consumption as in the example of FIG. 1 can be achieved by simply adding a simple circuit (R gate 3H in this case).

As described in detail above, the present invention allows the determination unit to return from standby mode to normal operation mode in response to an abnormality signal from an abnormality sensor, and each time the determination unit performs a predetermined process, and after the process is completed, the determination unit enters standby mode by software. mode and waits for the next standby return signal. With this configuration, the following effects can be obtained. First, the average current consumption of the determination section can be reduced compared to when it is always operated in the normal operation mode. Therefore, the life of the battery as a power source can be extended. Second, despite this configuration, it is possible to always perform the same functions as in the normal operation mode. Thirdly, as a determination section, even if the operation of the clock pulse generator 3E is stopped in the standby mode, the microcomputer can be returned from the standby mode to the normal operation mode by inputting the above-mentioned return signal. By stopping the operation of the clock pulse generator in this mode, the current consumption in standby mode can be further reduced. Fourth, since the battery can be made relatively smaller and smaller in capacity, the entire device can be made lighter and smaller.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a gas cutoff device according to one embodiment of the present invention, Fig. 2 is a timing chart for explaining the operation of the block diagram of Fig. 1, and Fig. 3 is a gas cutoff device according to another embodiment of the present invention. 4 is a block diagram of the gas cutoff device, and FIG. 5 is a block diagram of an example of the control section of the gas cutoff device. 1...Flow rate sensor, 2...Abnormality sensor, 3...
Control unit, 3A...Oscillator, 3F, 3F'...Example of determination unit with standby mode and storage unit, 4
...blocking means.

Claims (1)

[Claims] 1 An abnormality sensor that detects external abnormalities such as earthquakes and raw gas, and a signal from the abnormality sensor as input,
A control unit that processes this input signal according to a predetermined processing procedure, determines whether the gas can be shut off, and outputs a shut-off signal when the shut-off is determined, and a shut-off unit that shuts off the gas in response to the shut-off signal from the control unit. and a battery as a power source of the device, the control unit includes a determination unit having a standby mode and a port capable of returning from the standby mode to a normal operation mode in response to an external input signal, and a storage unit that stores the processing procedure. The output of the abnormality sensor is input to the standby return port of the determination unit, and the determination unit processes the signal from the abnormality sensor according to a processing procedure from the storage unit to determine whether or not to shut off. A gas cutoff device that makes a determination and switches from a normal operation mode to a standby mode after the processing.