JP3558430B2 - Gas meter with battery voltage monitoring device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gas meter with a battery voltage monitoring device capable of preventing accidents caused by city gas, propane gas, and the like.
[0002]
[Prior art]
When supplying city gas, propane gas, or the like to consumers through piping, a gas meter is provided for each customer. This gas meter measures and displays the flow rate of the gas used, and has a built-in control unit consisting of a microcomputer on the built-in electrical board. Using various sensors, the gas flow path is used when a gas leak or earthquake occurs. And has a function of shutting off a gas flow path by a shut-off electromagnetic valve inserted into the gas passage.
[0003]
A control device for controlling such a gas meter is supplied with power from a battery mounted on the same electrical board so that it can operate normally even in the event of a power failure. This battery is also used as a power source for driving the shut-off valve. Therefore, a decrease in the output voltage of the battery causes a situation where the shut-off valve cannot be closed or the microcomputer as the control device cannot be normally operated.
[0004]
Microcomputer chips, on the other hand, have very high impedances themselves and low power consumption. Also, the power supply voltage at which the operation is guaranteed is relatively low at about 1.2-1.3 volts. Can work.
[0005]
On the other hand, in order to drive the shut-off valve, it is necessary to supply a current to a solenoid coil in the shut-off valve to generate a predetermined power. Usually, a self-holding type shut-off valve that closes with an instantaneous current to avoid power consumption and consumes no electric power for opening and closing the valve is used as the shut-off valve. Nevertheless, when the valve is closed, it is necessary to supply a drive current, and a certain voltage value needs to be supplied from the battery to generate a predetermined magnetic force.
[0006]
Therefore, in the conventional gas meter, a circuit for checking the output voltage value of the battery is provided separately from the microcomputer chip. FIG. 9 shows a schematic block diagram of the circuit. A battery 21 for supplying a power supply voltage to a microcomputer 20 as a control device is connected. Further, a shutoff valve 22 is inserted in the middle of the gas flow path, and is closed by a valve drive unit 23 by a current supplied from the battery 21. Then, the conventional battery voltage check circuit 6 is provided on the same electrical circuit board, and the switch 61 is closed by the voltage check command signal O1 supplied once every 25 hours from the microcomputer 20, so that the voltage check circuit 6 operates. Then, the result is supplied to the microcomputer 20 as a voltage check result signal I1.
[0007]
As described above, since the microcomputer 20 can operate even when the power supply voltage supplied from the battery is relatively low, when the microcomputer 20 receives the check voltage decrease signal I1 indicating that the battery voltage has decreased from the voltage check circuit 6, By shutting off the switch 231 by outputting the shutoff command signal O2, the shutoff valve 22 is closed before safety cannot be ensured.
[0008]
[Problems to be solved by the invention]
When checking the output voltage of a battery, it is necessary to consider a voltage value when the output of the battery is opened and a voltage value when a circuit having a predetermined low impedance value is energized. In particular, in order to drive the shutoff valve 22, it is necessary to supply a large current to a solenoid circuit having a relatively low impedance. In general, in a battery, the internal resistance of the internal electrode portion tends to increase due to aging, and in such a case, the voltage value during energization is considerably lower than the voltage during opening. This is because a large current during energization causes a voltage drop due to the internal resistance of the battery.
[0009]
Therefore, in order to check whether or not the output voltage of the battery is equal to or higher than the value required to drive the shut-off valve, the conventional voltage check circuit 6 uses a pseudo resistor having the same impedance as the solenoid circuit of the shut-off valve. The output voltage is checked while the pseudo resistor is connected to the battery. Therefore, operating the voltage check circuit 6 consumes a large amount of power. For this reason, the output voltage of the battery is checked once every 25 hours as described above.
[0010]
FIG. 10 shows an operation flowchart of such a voltage check. When 25 hours have passed since the previous measurement (step 50), a current is applied to the pseudo resistor in the voltage check circuit (step 51), and after the power is supplied, the voltage value of the battery is measured (step 52), and the battery voltage is, for example, 1.36. If the voltage is equal to or less than the volt (step 53), the microcomputer 20 outputs the cutoff command signal O2 (step 54). In addition, even when the voltage value at the time of energization is as low as 1.36 volts, the open circuit voltage is, for example, 2.7 volts, which is a value sufficient for operating the microcomputer 20.
[0011]
However, a decrease in the battery voltage is caused not only by a gradual progression such as aging of the battery, but also by a large current caused by water entering the gas meter, causing a short circuit, or rarely by the microcomputer 20 running away. It is also conceivable that the amount rapidly decreases, for example, when is consumed. In such a case, the voltage check once every 25 hours may not be able to detect in a timely manner that the battery voltage has become lower than the voltage required for driving the shutoff valve. For this reason, it is conceivable that the shut-off valve cannot be closed even if a voltage value at which the microcomputer 20 can operate is obtained.
[0012]
Furthermore, when the operation of the microcomputer 20 itself becomes impossible due to a decrease in the voltage of the battery, the instruction signal for closing the shutoff valve can no longer be issued, and the safety control is not performed with the shutoff valve open. It is possible that this will cause a situation.
[0013]
Therefore, an object of the present invention is to provide a gas meter with a voltage monitoring device that can constantly monitor the voltage value of a battery.
[0014]
Another object of the present invention is to provide a gas meter with a voltage monitoring device that has a high internal impedance and can constantly monitor the battery voltage without consuming power.
[0015]
A further object of the present invention is to provide a gas meter with a voltage monitoring device capable of closing a gas shut-off valve independently of a microcomputer when detecting that the battery voltage has dropped.
[0016]
It is a further object of the present invention to provide a gas meter in which reuse is prohibited after detecting a drop in battery voltage and closing a gas shutoff valve.
[0017]
[Means for Solving the Problems]
The object of the present invention is, according to the first invention,
When detecting an abnormal state, a control device that performs drive control to close a shutoff valve provided in the gas flow path,
A battery connected to the control device and the shut-off valve to supply voltage to them;
Connected to the battery and the shut-off valve, has an internal impedance sufficiently higher than the internal impedance of the shut-off valve, constantly monitors the output voltage of the battery, and adjusts the output voltage of the battery to the minimum voltage required to drive the shut-off valve. A voltage monitoring device that supplies a forced shut-off signal to the shut-off valve to close the shut-off valve when the value drops to near the value,
It has pseudo-impedance means similar to the shut-off valve, and checks the output voltage of the battery in a state where power is supplied from the battery to the pseudo-impedance means every time a predetermined time elapses, and the voltage decreases to a predetermined value. A voltage check circuit that supplies a check voltage drop signal to the control device when
The control device is provided by providing a gas meter which supplies a shutoff command signal for closing the shutoff valve to the shutoff valve in response to the check voltage drop signal from the voltage check circuit. .
[0018]
By providing the voltage monitoring device having such a configuration, the battery voltage can be constantly monitored, and when the battery voltage suddenly drops for some reason, the drop in the voltage at that time can be detected. If the voltage drops rapidly, a relatively large current is flowing, so even if the voltage monitoring device has a high impedance, it is possible to substantially monitor the voltage value including the internal resistance of the battery. It becomes possible. In addition, since the battery has a high impedance, a large amount of battery power is not consumed even when the battery is constantly connected. Further, since a voltage check circuit having a relatively low internal impedance is provided, it is possible to appropriately detect a case where the battery voltage value gradually decreases. In addition, since the battery is merely energized to the pseudo impedance means every time a predetermined time has elapsed, the battery power is not consumed.
[0019]
The object of the present invention is, according to the second invention, in the first invention,
The control device has a memory for storing a history of abnormal conditions, in response to a monitoring voltage drop signal supplied from the voltage monitoring device when the output voltage of the battery drops to near the minimum voltage value, This is achieved by providing a gas meter characterized by storing a history of a decrease in battery voltage in a memory and then prohibiting the return of the shutoff valve.
[0020]
With this configuration, even if the shut-off valve is directly shut off from the voltage monitoring device, the control device is notified of the history of the shut-off due to the decrease in the battery voltage, so that the subsequent return of the shut-off valve can be prohibited. Here, prohibiting the return of the shut-off valve means that in the case of a type of shut-off valve in which the control device shuts off only in the shut-off direction and the return is performed manually, a shut-off command signal that the control device shuts off again when the shut-off valve is manually reset. Means to supply. Further, in the case of a shutoff valve of a type in which the bidirectional drive of shutoff and return is performed by a control device, it means that a return command signal is not supplied when a return command is issued.
[0021]
The object of the present invention is, according to the third invention, in the second invention,
Further, the control device is provided by providing a gas meter which stores the history of the battery voltage drop in the memory in response to the check voltage drop signal from the voltage check circuit.
[0022]
According to a fourth aspect, the object of the present invention is the above-mentioned second or third aspect,
The control device stores a history of another abnormal state different from the decrease in the battery voltage in the memory, and supplies the shutoff command signal to the shutoff valve in response to the detection of the another abnormal state, This is attained by providing a gas meter characterized in that the return of the shutoff valve is prohibited while the other abnormal state is not resolved.
[0023]
Here, prohibiting the return of the shutoff valve has the same meaning as described above.
[0024]
According to a fifth aspect of the present invention, the object of the present invention is any one of the first to fourth aspects,
The voltage monitoring device includes a reference voltage generation circuit connected to the battery for generating a predetermined constant voltage, a comparison voltage generation circuit connected to the battery for dividing the output voltage to a predetermined ratio, and a reference voltage and a comparison voltage. , And an output circuit that outputs the forced cutoff signal in response to the output of the comparison circuit that is output when the output voltage of the battery drops near the minimum voltage value. This is achieved by providing a gas meter.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0026]
[Outline of gas meter]
FIG. 1 is a schematic external view of a gas meter. A part of the meter upper case 9 has been removed for explanation. The gas meter main body 1 has a gas supply pipe connected to an inlet side base 2 and an outlet side 3, and a pair of diaphragms for measuring the amount of gas passing through both bases 2, 3 are built in the measuring unit 4. The pair of diaphragms reciprocate according to the gas flow, and the number of times is accumulated and displayed on the counter 7. The above is the general gas flow measurement function.
[0027]
In such a gas meter, in addition to the function of measuring the gas flow rate, reciprocating motion due to the gas flow rate and its change is transmitted to the permanent magnet, and the motion is detected by a reed switch or the like, and the reciprocating motion is detected from a range of normal use conditions set in advance. It has a function to monitor whether it has deviated. Then, when an abnormal state is detected, the shutoff solenoid valve 22 provided in the meter upper case 9 is shut off. Such a series of controls is performed by a control device 20 including a microcomputer and the like mounted on the electrical board 8 in the upper case 9. The battery 21 is also mounted on the electrical board 8. 7 is a counter for displaying the measured result, 28 is a return button of the shut-off valve 22, and 29 is a seismic sensor.
[0028]
As described above, a recent gas meter incorporates a shut-off valve, a microcomputer, and the like in addition to a mechanism necessary for measurement, and has a function of safety control as well as measurement of a gas flow rate.
[0029]
FIG. 2 is a schematic diagram of a gas meter system. A gas supply pipe is connected to the gas meter main body 1 via a cock 5. The gas flow flowing to the measuring section 4 in the gas meter is converted into reciprocating motion of a permanent magnet or the like as described above, detected by a reed switch or the like in the flow rate measuring device 12, and a pulse signal corresponding to the reciprocating motion is transmitted from the microcomputer. To the control device 20. Therefore, the control device 20 can know the current gas flow rate value from the number of pulses per unit time.
[0030]
Normal use conditions are set in the control device 20 in advance. For example, an instantaneous maximum flow rate or a maximum duration without a temporal change in the gas flow rate. When such a gas flow exceeding the instantaneous maximum flow rate or the maximum duration is detected, the control device 20 shuts off the gas by giving a shutoff command signal to the valve drive circuit 23 of the shutoff valve 22. Then, the history is stored in a memory in the control device 20, and the cause of the interruption is displayed on the display unit 11 including a light emitting diode or the like. Further, the control device 20 receives an abnormal signal from the sensor 14 that detects an abnormality other than the gas flow such as detecting an earthquake, and similarly gives a shut-off command signal to the shut-off valve 20 to shut off the gas, and stores it in the memory. And display.
[0031]
The microcomputer 20, the drive circuit 23 of the shut-off valve, and the like, together with the battery 21 for supplying the power supply voltage thereto, are commonly mounted in common on the electrical board 8 in the upper case 9 of the gas meter main body 1.
[0032]
FIG. 3 is a schematic circuit diagram of the control device and its periphery, and FIG. 4 is a schematic sectional view of the shut-off valve 22. In FIG. 3, a battery 21 supplies a power supply voltage Vcc to a control device 20 including a microcomputer and other peripheral circuits. The flow measuring device 12 is provided with a reed switch 121 for detecting the reciprocating motion transmitted to the permanent magnet 13 from the pair of diaphragms described above. The driver transistor 122 is driven by a pulse signal from the reed switch. At 20, a pulse input I3 of the gas flow is input. Reference numeral 124 denotes a filter circuit for eliminating chattering of the reed switch 121.
[0033]
In the sensor 14, for example, a sensing signal when the seismic sensor 29 detects an earthquake is received at an input terminal 141, and the drive transistor 142 is driven to input the earthquake sensing input I 4 to the control device 20. 143 is a filter circuit similarly.
[0034]
By monitoring the above-mentioned pulse input I3 of the gas flow, it is possible to check whether the gas flow has deviated from the normal use condition. If an abnormality is detected by the control device 20, the shut-off command signal O2 is output. Thus, the shut-off valve 22 is closed. Also, when the earthquake detection input I4 is received, the cutoff command signal O2 is output in the same manner.
[0035]
The outline of the shutoff valve 22 will be described with reference to FIG. The shutoff valve 22 is provided at the inlet-side base 2 in the upper case 9 of the gas meter main body. It is normally in an open state, and the valve body 222 is separated from the valve seat 221. This is because the movable iron core 223 overcomes the detaching spring 225 and is attracted to the permanent magnet 226 when no current is flowing through the solenoid coil 224. When the shut-off valve 22 is closed, a one-shot current flows through the solenoid coil 224 to generate a reverse magnetic field. The iron core 223 separates from the permanent magnet 226, and the valve body 222 contacts the valve seat 221 by the repulsive force of the spring 225. Upon contact, the shutoff valve will be closed.
[0036]
As described above, the shut-off valve 22 is a self-holding shut-off valve that closes with an instantaneous current and consumes no electric power for closing and holding the valve open in order to avoid power consumption.
[0037]
Returning to FIG. 3 again, the control device 20 that has detected the abnormality outputs the shutoff command signal O2, and the drive transistor 231 causes the one-shot current to flow from the power supply Vcc to the solenoid coil 224 to shut off the valve. Therefore, in order to close the shutoff valve 22, it is necessary to supply a certain amount of current to the coil 224 having a relatively low internal impedance, and for this purpose, a certain amount of power supply voltage is required. Further, control device 20 stores a history according to the type of abnormality in an internal memory.
[0038]
Returning to FIG. 4 again, after the shut-off valve 22 is closed by detecting an earthquake or exceeding the maximum instantaneous flow rate as described above, the cap 281 is removed and the return button 28 is pressed, whereby the valve seat 221 is pressed. The shut-off valve 22 can be returned by depressing the valve body 222 that is in contact with the iron core 223 to attract the iron core 223 to the permanent magnet 226.
[0039]
Such manual return of the shut-off valve 22 is detected by the back electromotive force of the solenoid coil L2 generated as the movable iron core 223 moves, and notifies the drive transistor 232 of the return of the shut-off valve as shown in FIG. The input I2 is input to the control device 20.
[0040]
In this way, when the control device 20 manually detects that the shut-off valve 22 has returned, the control device 20 checks again whether there is the same abnormality according to the history of the abnormality stored in the built-in memory. Move to When an abnormality such as gas leakage is detected, it is determined that the abnormal state has not been removed, and the shutoff command signal O2 is output again to shut off.
[0041]
[Monitoring of battery voltage drop]
Due to the problem of reliability, each circuit device of the electric board in the gas meter uses the battery 21 mounted on the board as a power source. Therefore, the battery 21 first needs a sufficient and sufficient voltage value to normally operate the control device 20 including a microcomputer, and secondly, a necessary and sufficient voltage value to close the shutoff valve 22. is necessary. The voltage required and sufficient to close the shut-off valve 22 is about 1.5 volts when energized and about 2.7 volts when open, whereas the internal impedance of the control device 20 is very low. And a voltage value close to open is about 1.2-1.3 volts.
[0042]
The conventional gas meter is provided with the voltage check circuit 6 for checking the voltage of the battery once every 25 hours as described with reference to FIG. The detailed operation is as described above.
[0043]
However, if the check is performed once every 25 hours, if the voltage of the battery 21 suddenly drops for some reason, it cannot be detected and the shut-off valve 22 cannot be closed. is there. Therefore, in the present embodiment, as shown in FIG. 3, a voltage monitoring device 24 that constantly monitors the output voltage Vcc of the battery 21 is provided independently of the microcomputer 20. When it is detected that the voltage of the battery 21 has dropped to a predetermined value, a forced shut-off signal O6 is supplied to the drive circuit 23 of the shut-off valve 22 and a monitoring voltage drop signal O7 is sent to the check voltage drop signal of the control device 20. Supply to the port of I1.
[0044]
Here, the voltage check circuit 6 that checks the voltage of the battery at a constant frequency has a relatively low pseudo impedance Z6 similar to the internal impedance of the shut-off valve 22. In this way, when the voltage of the battery gradually decreases, the voltage of the battery 21 can be measured while connecting to the battery 21 at a constant frequency and flowing a large current.
[0045]
On the other hand, the voltage monitoring device 24 that constantly monitors the internal impedance Z26 is set sufficiently higher than the internal impedance of the shut-off valve 22. By doing so, even if the voltage monitoring device 24 is always connected to the battery 21, the power consumption of the battery 21 is small. Therefore, the voltage monitoring device 24 constantly monitors the voltage close to the open voltage of the battery 21. In addition, when the voltage of the battery 21 drops rapidly, a large current flows, so that the voltage of the battery 21 can be monitored substantially under the influence of the internal resistance of the battery 21.
[0046]
Further, the voltage monitoring device 24 monitors whether or not the battery 21 maintains a voltage sufficient to obtain a one-shot current sufficient for closing the shut-off valve 22. Therefore, an optimal threshold value corresponding to the threshold value is set as the reference voltage.
[0047]
If the shut-off valve 22 is closed due to a drop in the voltage of the battery 21, the return of the gas meter again must be permanently prohibited. Therefore, upon receiving the check voltage drop signal I1 from the conventional voltage check circuit 6, the control device 20 stores the history in the built-in memory, and forcibly shuts off again when the shut-off valve 22 is opened to return. In order to perform this, a shutoff command signal O2 is issued.
[0048]
Similarly, when the voltage monitoring device 24 according to the present invention detects the voltage drop of the battery 21 and closes the shutoff valve 22 by the forced shutoff signal O6, the voltage monitoring device 24 notifies the control device 20 by the monitoring voltage drop signal O6. ing. As a result, the control device 20 similarly stores the history in the built-in memory, and when the shut-off valve is manually reset again, the shut-off valve is shut down again by issuing the shut-off command signal O2.
[0049]
That is, since the voltage value required to drive the shut-off valve 22 is higher than the voltage value required to operate the microcomputer 20, even if the monitoring voltage drop signal O7 is output by the voltage monitoring device 24, the microcomputer is still 20 may be operating normally, and the permanent inhibition function of the return of the gas meter as described above is utilized.
[0050]
FIG. 5 is a circuit example of the voltage monitoring device 24 that monitors the voltage drop of the battery. In this circuit example, the output voltage Vcc of the battery 21 is divided by the resistors R1 and R2 to generate the comparison voltage Vb, while the reference voltage Vref is generated by the resistor R3 and the Zener diode Z1. These resistors R1, R2, R3, and Z1 are designed so that the comparison voltage Vb becomes lower than the reference voltage Vref when the output voltage Vcc of the battery 21 drops to near the minimum voltage required to drive the shut-off valve 22. ing. The comparison voltage Vb and the reference voltage Vref are input to the comparison circuit 241, and the output of the comparison circuit 241 is connected to the outputs O6 and O7 via the low-pass filter 242.
[0051]
The comparison circuit 241 is configured by, for example, a circuit indicated by an arrow in FIG. A pair of transistors 243 and 244, an output transistor 245, and resistors R5-R8 are provided, and a reference voltage Vref and a comparison voltage Vb are input to the gates of the pair of transistors, respectively. Normally, since the output voltage Vcc of the battery 21 is sufficiently high and the comparison voltage Vb is higher than the reference voltage Vref, the transistor 244 is turned on, the output transistor 245 is turned off, and the output is at a high level. As a result, the drive transistor 231 of the shut-off valve 22 is off, and the shut-off valve 22 is kept open. On the other hand, when the output voltage of the battery 21 decreases and falls below the level designed in advance, the comparison voltage Vb becomes lower than the reference voltage Vref, the transistor 244 turns off, the output transistor 245 turns on, and the output goes low. As a result, the base of the drive transistor 231 of the shutoff valve 22 becomes low level, and when it is turned on, a one-shot current is supplied to the solenoid coil.
[0052]
Note that it is desirable to connect a circuit that outputs a low-level pulse with a constant width to the output 246 of the comparison circuit 241 in order to allow a one-shot current to flow.
[0053]
The low-pass filter 242 is composed of a normal CR circuit. As shown in FIG. 3, the output of the battery 21 is also supplied to the microcomputer 20 via the equivalent low-pass filter circuit 211. For example, when a relatively large current flows, for example, when the shut-off valve 22 is driven as a result of sensing an earthquake, the battery voltage often drops for a short time and then recovers to the original voltage. It is provided to ensure the normal operation of the microcomputer 20 in that case. Therefore, the voltage monitoring device 24 is also provided with the low-pass filter 242 to prevent the shut-off command signal O6 for shutting off the shut-off valve 22 and the monitoring voltage drop signal O7 from being output in the same phenomenon.
[0054]
The voltage monitoring device 24 as described above is designed to have a relatively high internal impedance. In particular, it is considerably higher than the internal impedance when the shut-off valve 22 is driven. As a result, even if the voltage monitoring device 24 is constantly connected to the battery 21 and the voltage is monitored, the power consumed by the voltage monitoring device 24 itself is an extremely low value, and the voltage itself may cause a voltage drop of the battery 21. It will not be.
[0055]
[Operation in control device]
FIG. 6 is a schematic block diagram of the control device 20 including a microcomputer. The control device 20 may be a general-purpose microcomputer or a customized microcomputer. The internal structure includes an arithmetic unit 201, a ROM 203 in which a control program is stored, a RAM 202 in which a program area is used as a work area or an environment in which a gas meter is installed, and an interface for transmitting and receiving signals to and from the outside. The units 204 and the like are connected through a common bus 205. The interface unit 204 has an analog / digital conversion circuit and the like.
[0056]
The RAM 202 stores, for example, the number of the gas meter, the maximum instantaneous flow rate, the maximum duration, the integrated value of the measured gas flow rate, the leak detection threshold value, the valve shutoff information, the telephone number, the ID number of the gas meter, and the like. The maximum instantaneous flow rate, the maximum duration, the leak detection threshold, and the like are used to detect an abnormality in the gas flow. Further, the valve shutoff information is history and valve shutoff information as a cause when the shutoff valve is closed upon detecting various abnormalities. Therefore, when an earthquake is detected or when it is detected that the maximum instantaneous flow rate has been exceeded, even if the shut-off valve is manually reset afterwards, the history of the shut-off valve is permitted by checking its history. A decision can be made.
[0057]
The arithmetic unit 201 executes the program according to the control program stored in the ROM 203. The operation flow will be described with reference to the flowchart in FIG.
[0058]
Steps 30, 34, and 37 in FIG. 7 are portions for checking an abnormal state. Although these steps are parallel programs that progress simultaneously in FIG. 7, they may be executed by a sequential program. In steps 34 and 37, a decrease in the battery voltage is observed, whereas in step 30, an abnormality for another reason is detected. In steps 30-32, for example, when the gas flow instantaneously exceeds the maximum instantaneous flow rate, the shutoff command signal O2 is output from the control device 20 and the shutoff valve 22 is closed. At the same time, the history and the information of shutting off the valve are written in the RAM 202 of the internal memory.
[0059]
Also, in steps 33-36, every time 25 hours elapse, the control device 20 outputs the voltage check command signal O1 to operate the voltage check circuit 6. Then, it is checked whether or not the battery voltage (power supply state) at that time has dropped to a predetermined voltage. If the battery voltage has dropped, the valve is shut off and the history is written to the memory.
[0060]
On the other hand, the voltage monitoring device 24 constantly monitors the output voltage of the battery as in step 37, and when the output voltage drops to a predetermined threshold value, gives the forced shutoff signal O6 to the shutoff valve 22 without going through the control device 20 to shut off. I do. Then, the monitoring voltage lowering signal O7 is supplied to the control device 20, and the history and the information indicating the interruption are written into the memory in the control device 20 (steps 37 and 36).
[0061]
When the shutoff valve 22 is closed, the cause is displayed on the display unit 11 of the gas meter by the control device 20. Therefore, the user of the gas meter checks the abnormal state according to the information, and if there is no problem, manually opens the shut-off valve 22 and returns it.
[0062]
When the shut-off valve 22 is returned, the control device 20 recognizes the back electromotive force generated accordingly (step 38), and the control device 20 determines whether or not the shut-down has been performed due to the prohibition of the restart. (Step 39). This can be determined by reading the area of the RAM 202. For example, when the battery voltage drops, the gas meter is permanently prohibited from being reused. In this case, the control device 20 issues the shutoff command signal O2 again, and the shutoff valve is closed again (step S1). 41). On the other hand, in the case of earthquake detection or exceeding the maximum instantaneous flow rate, it is possible to reuse as long as the cause disappears. For example, a diagnosis program from the control device 20 is executed to determine whether the operation is normal (step 40). If there is no problem, the operation state is normal.
[0063]
In addition, when the shut-off valve 22 is shut down again even if the reset operation is performed 2-3 times, it is usually determined that the reset is impossible, and no further reset operation is performed.
[0064]
As described above, when the shut-off valve is closed, the control device 20 performs an operation as to whether or not the manual return of the shut-off valve is permitted according to the contents of the closed history. In the case of the voltage check circuit 6 which operates once every 25 hours according to a command from the conventional control device 20, a cut-off command has been issued by the control device 20. However, in the case of the voltage monitoring device 24 which constantly monitors the voltage of the battery, the control device 20 forcibly shuts off regardless of whether or not the control device 20 operates normally. Can not. Therefore, when the voltage monitoring device 24 performs the forcible shutoff, the voltage monitoring device 24 notifies the control device 20 of the fact and uses the re-return prohibition function of the control device 20.
[0065]
Although the case where the shutoff valve 22 is driven by the control device 20 in only one direction has been described above, the present invention can be applied to a case where the shutoff valve 22 is driven by the control device 20 in both directions. That is, this is a case where the shutoff valve 22 is driven bidirectionally by the control device 20 giving the shutoff command signal and the return command signal. Such a bidirectional shutoff valve is still a self-holding type that does not consume power in the open state and the closed state.
[0066]
FIG. 8 is an operation flowchart when a bidirectional shutoff valve is used. What is different from the case of FIG. That is, when a bidirectional shutoff valve is used, the shutoff valve is reset by the control device 20 giving a reset command signal. Therefore, the control unit 20 waits until receiving the return command (step 42). When the return command is received, the history stored in the RAM 202 in the control device 20 is checked in the same manner as described above, and it is determined whether or not the history is the restart prohibition history. When restart is prohibited, the shut-off valve is not restored. If the restart is not prohibited, a check is performed to determine whether the gas flow and the like are in a normal operation state. If the operation is normal (step 40), the shut-off valve is reset by a reset command signal from the control device 20. become.
[0067]
【The invention's effect】
According to the present invention, the output voltage of the battery that supplies power to the control device and the shut-off valve of the gas meter is constantly monitored, and when the voltage drops to near the minimum voltage necessary for driving the shut-off valve, the shut-off valve is forcibly closed by itself. The voltage monitoring device ensures that even if the battery voltage drops sharply, it can reliably detect the voltage, and shut down the most important safety measures before a microcomputer or other control device cannot operate normally. Valve shutoff can be performed.
[0068]
Further, since the voltage monitoring device is designed to have a relatively high internal impedance, even if the voltage monitoring device is constantly connected to monitor the output voltage of the battery, power consumption of the battery does not occur.
[0069]
In addition, when the voltage monitoring device forcibly shuts down itself, the voltage monitoring device notifies the control device 20 of that fact at the same time, so that the meter re-inhibition function of the control device 20 can be effectively used thereafter.
[Brief description of the drawings]
FIG. 1 is an external view of a gas meter.
FIG. 2 is a schematic diagram of a gas meter system.
FIG. 3 is a schematic circuit diagram of a control device according to the embodiment of the present invention.
FIG. 4 is a schematic view of a shut-off valve.
FIG. 5 is a circuit diagram of the voltage monitoring device according to the embodiment of the present invention.
FIG. 6 is a schematic block diagram of a control device.
FIG. 7 is an operation flowchart (1) of the embodiment of the present invention.
FIG. 8 is an operation flowchart (2) of the embodiment of the present invention.
FIG. 9 is a diagram showing a conventional technique.
FIG. 10 is a flowchart of a conventional voltage check.
[Explanation of symbols]
1 Gas meter body
6 Voltage check circuit
20 Control device
21 Battery
22 Shutoff valve
23 Drive section of shut-off valve
24 Voltage monitoring device
241 comparison circuit
242 Low-pass filter
O2 cutoff command signal
O6 Force cutoff signal
O7 Monitor voltage drop signal
I1 Check voltage drop signal
I2 Shut-off valve return signal
Vcc Battery output voltage (power supply voltage)
Vb Comparison voltage
Vref reference voltage

Claims (7)

When detecting an abnormal state, a control device that performs drive control to close a shutoff valve provided in the gas flow path,
A battery connected to the control device and the shut-off valve to supply voltage to them;
Connected to the battery and the shut-off valve, has an internal impedance sufficiently higher than the internal impedance of the shut-off valve, constantly monitors the output voltage of the battery, and adjusts the output voltage of the battery to the minimum voltage required to drive the shut-off valve. A voltage monitoring device that supplies a forced shut-off signal to the shut-off valve to close the shut-off valve when the value drops to near the value,
It has pseudo-impedance means similar to the shut-off valve, and checks the output voltage of the battery in a state where power is supplied from the battery to the pseudo-impedance means every time a predetermined time elapses, and the voltage decreases to a predetermined value. A voltage check circuit that supplies a check voltage drop signal to the control device when
The gas meter, wherein the control device supplies a shutoff command signal for closing the shutoff valve to the shutoff valve in response to the check voltage drop signal from the voltage check circuit. In claim 1,
The control device has a memory for storing a history of abnormal conditions, and in response to a monitoring voltage drop signal supplied when the output voltage of the battery drops from the voltage monitoring device to near the minimum voltage value, A gas meter wherein a history of a decrease in battery voltage is stored in a memory, and thereafter the return of the shutoff valve is prohibited. In claim 2,
Furthermore, the control device stores the history of the battery voltage drop in the memory in response to the check voltage drop signal from the voltage check circuit. In claim 2 or 3,
The control device stores a history of another abnormal state different from the decrease in the battery voltage in the memory, and supplies the shut-off command signal to the shut-off valve in response to the detection of the another abnormal state. A gas meter, wherein the return of the shutoff valve is prohibited while the other abnormal state is not resolved. In any one of claims 1 to 4,
The voltage monitoring device includes a reference voltage generation circuit connected to the battery and generating a predetermined constant voltage, a comparison voltage generation circuit connected to the battery and dividing the output voltage to a predetermined ratio, and a reference voltage and a comparison voltage. And an output circuit that outputs the forced cutoff signal in response to the output of the comparison circuit that is output when the output voltage of the battery drops to near the minimum voltage value. And a gas meter. When detecting an abnormal state, a control device that performs drive control to close a shutoff valve provided in the gas flow path,
A battery connected to the control device and the shut-off valve to supply voltage to them;
Connected to the battery and the shut-off valve, has an internal impedance sufficiently higher than the internal impedance of the shut-off valve, constantly monitors the output voltage of the battery, and adjusts the output voltage of the battery to the minimum voltage required to drive the shut-off valve. A voltage monitoring device for supplying a forced shutoff signal to the shutoff valve to close the shutoff valve when the value drops to a value near the value. In claim 6,
The control device has a memory for storing a history of abnormal conditions, and in response to a monitoring voltage drop signal supplied when the output voltage of the battery drops from the voltage monitoring device to near the minimum voltage value, A gas meter wherein a history of a decrease in battery voltage is stored in a memory, and thereafter the return of the shutoff valve is prohibited.

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