JP2003057083A - Flow rate interrupting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow rate interrupting device that can detect any abnormality of a microcomputer, and investigate its cause and take a measure even if an initial processing is performed in the microcomputer due to the abnormality of the microcomputer. SOLUTION: A microcomputer reset pulse oscillation circuit 16 outputs a reset signal accompanied with an abnormal signal outputted from a binarizing circuit 11 in the abnormal condition of a microcomputer 1, and the microcomputer 1 performs initial processing. In case when the microcomputer 1 can read a time-up signal outputted from a watchdog time-up pulse oscillation circuit 17 on the way of the initial processing, it is judged that resetting is done due to the abnormality of microcomputer, and an indication lamp 12 flickers to announce it to the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate shutoff device for monitoring the flow rate of a fluid and shutting off the flow path when the flow rate is abnormal.

[0002]

2. Description of the Related Art Here, a microcomputer gas meter will be described as an example of a conventional technique of a flow rate cutoff device. In a conventional microcomputer gas meter, a built-in microcomputer (hereinafter referred to as a well-known abbreviated microcomputer for simplification of description) constantly monitors a gas flow rate, and a gas flow rate abnormality (for example, a gas flow rate is a predetermined amount). In case of an emergency such as more than or less than a predetermined amount), the electromagnetic valve built in the microcomputer gas meter is opened / closed to shut off the gas supply to prevent a gas accident from occurring.

Such a microcomputer gas meter will be described with reference to the drawings. FIG. 5 is a circuit diagram showing an example of a conventional microcomputer gas meter. The conventional microcomputer gas meter includes a microcomputer 1, a flow rate sensor 2, a pressure sensor 3, a vibration sensor 4, an oscillator 5, a resistor 6, a capacitor 7, a discharging transistor 8, a charging resistor 9, a capacitor 10, and a binarization circuit 11. , Indicator light 12, shutoff valve driving transistor 1
3, a shutoff valve 14, and a one-shot pulse oscillation circuit 15.

In the conventional microcomputer gas meter, the microcomputer 1 monitors the gas usage state by signals from the flow rate sensor 2, the pressure sensor 3 and the seismic sensor 4, and the microcomputer 1 detects the abnormal usage state. The shutoff valve 14 is closed to stop the supply of fluid. An oscillator 5 is connected to the microcomputer 1 and is supplied with a clock frequency.

The microcomputer 1 of this microcomputer gas meter is
It has a so-called watchdog function for detecting abnormal operation. The watchdog function will be described. The following method is adopted as a method of realizing the watchdog function. In a state where the charging circuit including the charging resistor 9 and the capacitor 10 is operating normally, the command periodically issued from the refresh terminal of the microcomputer 1 is the resistor 6,
It is input to the base of the discharging transistor 8 via the capacitor 7. A charging circuit including a charging resistor 9 and a capacitor 10 is connected to the discharging transistor 8, and the charging circuit is charged and discharged according to the output from the discharging transistor 8. The resistor 6, the capacitor 7, and the discharging transistor 8 form a refresh circuit.

The charging circuit connected to the refresh circuit can set the charging time, and the charging resistor 9 and the capacitor 10 can be set.
The upper limit of the time constant determined by is determined with reference to the time when there is no problem in safety even if the microcomputer 1 is in a gas releasing state when the microcomputer 1 is abnormal, and it is necessary to be within 1 minute. On the other hand, the periodical command from the microcomputer 1 for periodically discharging the electric charge of the capacitor 10 is normally the resistance value of the charging resistor 9 and the electrostatic capacitance of the capacitor 10 from the condition that the potential of the capacitor 10 is hardly increased. Time constant 1 determined by capacity
It is set to a cycle of about / 100.

Therefore, in the prior art, the cycle of the command periodically issued from the refresh signal output terminal of the microcomputer 1 is, for example, 0.1 second, and the time constant determined by the charging resistor 9 and the capacitor 10 (of the charging circuit). The charging completion time) is usually set to about 10 seconds, which is sufficiently larger than the cycle of the command from the microcomputer 1. Therefore, the microcomputer 1 operates normally, and the discharging transistor 8 is periodically
In the state where the pulse signal for refresh is periodically issued (every 0.1 seconds) to the base of the capacitor, the capacitor 10 is immediately discharged before the completion of charging and the potential hardly rises, and the binarization circuit 11 does not output a significant signal (abnormal signal). ,

On the other hand, when an abnormality occurs in the operation of the microcomputer 1 and the discharge command is no longer output, the microcomputer 1 outputs a DC component. In this case, if the command from the refresh signal output terminal of the microcomputer 1 is in an abnormal state in which the direct current component of the potential level that keeps the discharging transistor 8 in the cutoff state continues to be output, the charging circuit is charged and the abnormality is detected. However, when an abnormal state in which the direct current component of the potential level that keeps the discharging transistor 8 in a conducting state is continuously output, the charging circuit is not charged and no abnormality is detected.

Therefore, by using the capacitor 7, the microcomputer 1
The DC component of the command issued from the refresh signal output terminal of is cut off. Therefore, the microcomputer 1
When the pulse signal is not output from, the discharging transistor 8 maintains the cutoff state, the electric charge of the capacitor 10 does not always discharge, and the potential rises, so that the abnormality can be surely detected.

Due to the abnormality of the microcomputer 1, the capacitor 10
When the electric charge in the
When the potential becomes higher than the set voltage value (ref) of the binarization circuit 11, the binarization circuit 11 outputs a significant signal (abnormal signal). The one-shot pulse oscillation circuit 15 receives a significant signal (abnormal signal) from the binarization circuit 11 and outputs a reset signal, which is a one-shot pulse signal, to the microcomputer 1.

This reset signal is input to the reset signal input terminal of the microcomputer 1. The microcomputer 1 detects a reset signal to initialize the operation abnormality by software, and at the same time, outputs a signal for shutting off the shutoff valve 14 to the shutoff valve driving transistor 13 to close the shutoff valve 14. In this case, the fact that there has been a reset is reported by blinking the indicator lamp 12 or the like. The watchdog function is like this.

Further, a microcomputer gas meter according to such an improvement of the prior art is disclosed in, for example, Japanese Patent Laid-Open No. 10-19628.
No. In the microcomputer gas meter disclosed in the application, when an abnormality of the microcomputer is detected, the shutoff valve is driven so as to be cyclically closed repeatedly to surely stop the gas supply.

In this microcomputer gas meter, since the shutoff valve is closed by hardware when the microcomputer itself is broken or when the clock circuit of the microcomputer is abnormally stopped, a higher fail-safe function of the system can be ensured, and the signal of the oscillation circuit can be secured. Thus, the shutoff valve is driven periodically, so that the shutoff valve is repeatedly closed even if the gas user manually returns the shutoff valve. Therefore, there is an excellent effect that the safety is secured and at the same time, the gas user can be notified that the microcomputer gas meter is abnormal.

Although the microcomputer gas meter described above is a general prior art, as another example, a timer circuit dedicated to a watchdog is provided inside the microcomputer instead of the above-mentioned charging circuit, and if this timer circuit overflows. There is also a method of using a microcomputer having a function of generating a reset signal. For example, a timer circuit measures time, and when a predetermined period has elapsed from the start of measurement, a reset signal is output to the microcomputer to reset the microcomputer. Also in this case, it is necessary to periodically refresh by software so that the timer circuit does not overflow.

Although the conventional microcomputer gas meter has been described above, in any case, a reset signal is generated by the microcomputer when the microcomputer malfunctions, and the microcomputer performs an initial process (initialization process) by software according to the reset signal. It is common to try to secure the fail-safe of the microcomputer gas meter by performing the above.

[0016]

In the prior art as described above, when the watchdog function operates and the microcomputer inputs the reset signal and performs the initial processing, the setting is registered in advance in the storage unit incorporated in the microcomputer. The existing data will be cleared and it will be in the initial state. Since the watchdog function is a function that detects an abnormal condition and operates, it notifies the gas consumer etc. at the time of operation and promptly investigate the cause.
It is desirable to take measures, but when the data is cleared and the microcomputer is in the initial state, the microcomputer cannot recognize that the watchdog function has operated, and there is a problem that prompt notification cannot be performed.

Further, the above-mentioned problem is not a problem peculiar to the microcomputer gas meter for gas, and for example, gas other than gas or liquid such as water or chemicals (hereinafter, these are collectively referred to as fluid). A device that detects the usage state of the device and shuts off the supply of the fluid at the time of abnormality has the same problem, and a solution has been desired.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to detect the presence of a microcomputer abnormality even when the initial processing of the microcomputer is performed due to the abnormality of the microcomputer so as to investigate and take action. It is to provide a flow rate cutoff device that enables the above.

[0019]

In order to solve the above problems, in the invention according to claim 1 of the present invention, at least a microcomputer, a sensor and a shutoff valve are provided, and a fluid such as gas or water is provided by a signal from the sensor. The microcomputer monitors the usage status, and if an abnormal usage status is detected, the microcomputer closes the shutoff valve to stop the fluid supply and improve the safety. An abnormality detecting means for outputting an abnormality signal, and a reset signal outputting means for outputting a reset signal which is a pulse signal of a predetermined output period in order to reset the microcomputer in response to the abnormality signal output by the abnormality detecting means, Time-up signal output means for receiving the abnormality signal output from the abnormality detection means and outputting a time-up signal that is a pulse signal in a predetermined output period; The output period of the time-up signal output from the time-up signal output means is longer than the output period of the reset signal output from the reset signal output means, and the microcomputer performs an initial process according to the reset signal. It is characterized by detecting a time-up signal and judging that there is a reset due to an abnormality in the microcomputer.

According to the present invention, the microcomputer reset signal is output by the watchdog function, and the watchdog function time-up signal output means is provided so that the watchdog function time-up signal is output for a time sufficiently longer than the microcomputer reset signal. It is set. When the microcomputer is reset by the watchdog function, the microcomputer receives the reset signal and performs initial processing, but the time-up signal of the watchdog function has a longer output period than the set signal. The flow rate cutoff device enables the microcomputer 1 to check the presence or absence of a time-up signal for the watchdog function after the initial processing to confirm that the microcomputer is reset by the watchdog function.

In the invention according to claim 2 of the present invention,
The flow rate cutoff device according to claim 1, further comprising an indicator light connected to the microcomputer, wherein the microcomputer controls the indicator light to blink when a time-up signal is detected during initial processing, thereby causing a microcomputer abnormality. It is characterized by notifying that there was a reset by.

In the invention according to claim 3 of the present invention,
The flow rate cutoff device according to claim 1 or 2, wherein the microcomputer has a built-in storage unit, and when a time-up signal is detected during initial processing of the microcomputer, the microcomputer stores data held in the storage unit. It is characterized in that the data in the storage unit is held if it is inspected and it is determined that the data is normal, and the data in the storage unit is cleared if it is determined that the data is abnormal.

Further, in the invention according to claim 4 of the present invention,
The flow rate cutoff device according to any one of claims 1 to 3, wherein the abnormality detection means includes a charging circuit that charges a capacitor and a refresh circuit that discharges the charge of the capacitor according to a command from a microcomputer. And a binarization circuit that outputs an abnormal signal when the potential of the capacitor rises above a certain value.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings, taking a microcomputer gas meter as an example. In the present embodiment, the flow rate cutoff device will be described assuming a microcomputer gas meter in particular for the sake of concreteness of the description, but the invention is not limited to the microcomputer gas meter, and for example, a fluid other than gas (a gas such as air, or It goes without saying that the present invention can also be applied to a flow rate cutoff device that cuts off liquid such as water and chemicals. FIG. 1 is a circuit diagram of a microcomputer gas meter according to an embodiment of the present invention, and FIG. 2 is a timing chart of signals output from each unit of the present embodiment.

In the present embodiment, as shown in FIG. 1, a microcomputer 1, a flow sensor 2, a pressure sensor 3, a vibration sensor 4, an oscillator 5, a resistor 6, a capacitor 7, a discharge transistor 8,
The charging resistor 9, the capacitor 10, the binarization circuit 11, the indicator lamp 12, the shutoff valve driving transistor 13, and the shutoff valve 14 are provided in the same manner as in the prior art, but the microcomputer reset pulse oscillation circuit 16, A watchdog time-up pulse oscillation circuit 17 and a reset switch 18 are provided. In FIG. 1, components having the same functions as those of the conventional technique are designated by the same reference numerals (1 to 14).

The difference from the prior art is that the time of the watchdog function is separate from the microcomputer reset pulse oscillation circuit 16 (which corresponds to the one-shot pulse oscillation circuit 15 in the prior art) that outputs the reset signal of the microcomputer 1 by the watchdog function. The watchdog time-up pulse oscillator circuit 17 that outputs an up signal is provided, and the output time of the time-up signal of the watchdog function is output longer than the output time of the reset signal. In the above, the microcomputer 1 can confirm that the watchdog function has worked.

In this embodiment, signals are output at the timing shown in FIG. In the timing chart shown in FIG. 2, the vertical axis represents voltage, the horizontal axis represents time, and four signals are simultaneously expressed in the vertical direction. (1) is the input voltage to the binarization circuit 11, that is, the potential of the capacitor 10, (2) is the output signal of the binarization circuit 11,
(3) is an output signal of the microcomputer reset pulse oscillation circuit 16, and (4) is an output signal of the watchdog time-up pulse oscillation circuit 17.

Next, the watchdog function according to this embodiment will be described. In FIG. 1, an abnormality detecting means for detecting an abnormality of the microcomputer 1 is the same as that of the conventional technique.
That is, the charging circuit including the charging resistor 9 and the capacitor 10, the refresh circuit including the resistor 6, the capacitor 7, and the discharging transistor 8 and the binarizing circuit 11 are combined.

When the microcomputer 1 is operating normally, a refresh signal is output from the microcomputer 1 at intervals of 0.1 seconds and is input to the discharging transistor 8 via the resistor 6 and the capacitor 7. The function and the like of the capacitor 7 are the same as those of the conventional technique, and the description thereof will be omitted. In this case, if the time constants of the charging resistor 9 and the capacitor 10 of the charging circuit are selected to be, for example, 10 seconds, the microcomputer 1 operates normally,
In the state where the discharging command is issued to the discharging transistor 8 in a cycle of 0.1 seconds, the potential of the capacitor 10 hardly rises and the binarization circuit 11 does not output a significant signal (abnormal signal).

When an abnormality occurs in the operation of the microcomputer 1, abnormality detection processing is executed. The microcomputer 1 runs away ((1 at time t ₁ in Figure 2)) and the input voltage of the charge of the capacitor 10 is no longer discharged to the binarizing circuit 11 begins to rise (time t ₁ in FIG. 2 ~t ₂ (see (1)), the potential is the set voltage value (re
At a timing exceeding f), the binarization circuit 11 outputs a significant signal (abnormal signal) (see (1) and (2) at time t ₂ in FIG. 2). This time point corresponds to 10 seconds after the microcomputer 1 runs out of control, as shown in (1) of FIG.

The significant signal (abnormal signal) output from the binarization circuit 11 is a microcomputer reset pulse oscillation circuit 16
And watchdog time-up pulse oscillation circuit 17
Are entered at the same time. When the binarization circuit 11 outputs a significant signal (abnormal signal), the microcomputer reset pulse oscillation circuit 16 and the watchdog time-up pulse oscillation circuit 17 simultaneously output a one-shot pulse signal (at time t ₂ in FIG. 2), (3)).

The pulse width at this time is a CR time constant of C ₁ × R _{1 in} the microcomputer reset pulse oscillation circuit 16 and C ₂ × in the watchdog time-up pulse oscillation circuit 17.
It is determined by the CR time constant of R ₂ . Since the reset signal of the microcomputer 1 is normally about 1 ms, the time constant of C ₁ × R ₁ of the microcomputer reset pulse oscillation circuit 16 is set to about 5 ms, and the C ₂ × R of the watchdog time-up pulse oscillation circuit 17 is set. ₂ is set to 10 times about 50 ms.

[0033] When the pulse signal from the microcomputer reset pulse oscillation circuit 16 demodulates the H level, the microcomputer 1 starts operation from the initial (see (3) at time t ₃ in FIG. 2). If the time-up signal input can be read within 45 ms during the initial processing, the abnormality can be detected. In the present embodiment, as shown in FIG. 2, the microcomputer 1 reads the time-up signal output from the watchdog time-up pulse oscillation circuit 17 at time t ₄ . In the present embodiment, the watchdog time-up pulse oscillation circuit 17
Is described as an L level signal. Since the microcomputer 1 outputs the refresh signal from the refresh signal output terminal 0.1 seconds after the start of the initial processing, the output of the binarization circuit 11 is cleared 0.1 seconds after the start of the initial processing (time t in FIG. 2). (See (2) in ₅ ).

Here, the reset switch 18 may be operated to reset the microcomputer 1 without depending on the watchdog function. Hereinafter, differences between the initial processing when the reset switch 18 is operated and the initial processing by the watchdog function will be described.

When the reset switch 18 is operated,
Reset signal is input to the icon reset input terminal
(Time t in FIG. 2₆(See (3)). In this case,
The watchdog time-up pulse oscillation circuit 17 has a signal
Is not transmitted, the watchdog time-up
Oscillator circuit 17 does not output a pulse (time t in FIG. 2). ₆
(See (4)). Therefore, the reset switch 1
After the operation of 8, the microcomputer 1 starts the initial processing (Fig.
Time t 2₇(Refer to (3)), time-up signal
Steady state signal is read when input is read
(Time t in FIG. 2 ₈(See (4)). In addition, this implementation
The morphological steady state is described as the H level. Above
The microcomputer 1 determines that the reset switch 1
Is it a reset when operating 8 or a watchdog
It is possible to determine whether the reset is due to a function.

In this embodiment, the microcomputer reset pulse oscillation circuit 16 and the watchdog time-up pulse oscillation circuit 17 which receive the H signal of the binarization circuit 11 and output a one-shot pulse are taken as an example. Although not shown, the circuit is not limited to such a circuit, and although not shown, a one-shot pulse signal is output upon receiving the L signal of the binarization circuit, or an edge of the binarization circuit signal is detected to generate a one-shot pulse. The microcomputer reset pulse oscillation circuit 16 and the watchdog time-up pulse oscillation circuit 17 that output may be used. These can be appropriately selected.

Next, the initial processing by the microcomputer 1 will be described. FIG. 3 is a flowchart of the initial processing executed by the microcomputer 1. In this initial processing, first, the port of the microcomputer 1 is set (step S11), then the pulsed time-up signal output from the watchdog time-up pulse oscillation circuit 17 is read (step S12), and the time-up signal is Low. It is detected whether or not it is a level (step S1)
3).

If the time-up signal is at low level, the indicator lamp 12 is driven to blink (step S1).
4). By performing such processing, it can be notified to the outside that the microcomputer 1 has been reset by the watchdog function. Although the example in which the notification by the indicator lamp 12 is adopted is given here, the notification can be similarly made by performing communication by a telephone line or wireless.

Next, another initial process by the microcomputer 1 will be described. FIG. 4 is a flowchart of another initial process executed by the microcomputer 1. In this example, in the initial processing, first, the port of the microcomputer 1 is set (step S21), and then the pulsed time-up signal output from the watchdog time-up pulse oscillation circuit 17 is read (step S2).
2) It is detected whether or not the time-up signal is at Low level (step S23).

If the time-up signal is at the low level, the RAM which is a storage unit built in the microcomputer 1
Check the RAM data registered in (step S2
4) Further, it is detected whether or not the RAM data is within the normal range (step S25). Then, if the time-up signal is at the low level and the RAM data is within the normal range, the RAM data is held and the normal operation is started (step S26). On the other hand, if the time-up signal is not at the Low level or the RAM data is not within the normal range, the RAM data is cleared and the initial state is entered (step S27). As a result, even if the watchdog function works, if the RAM is normal, the state before the watchdog function operation can be restored.

[0041]

According to the present invention, since the microcomputer has a function of recognizing whether the reset by the watchdog function is performed or not, the user is notified of the reset by the watchdog function. , Can prompt prompt response. When the RAM is normal, the state before the reset by the watchdog function is returned to, so that the original security function can be maintained even after the operation of the watchdog function.

In general, it is possible to provide a flow rate cutoff device capable of detecting the occurrence of a microcomputer abnormality and investigating the cause and coping with it, even when the initial processing of the microcomputer is performed due to the abnormality of the microcomputer.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a microcomputer gas meter according to an embodiment of the present invention.

FIG. 2 is a timing chart of signals output from each unit of the microcomputer gas meter according to the embodiment of the present invention.

FIG. 3 is a flowchart of an initial process executed by a microcomputer.

FIG. 4 is a flowchart of another initial process executed by the microcomputer.

FIG. 5 is a circuit diagram showing an example of a conventional microcomputer gas meter.

[Explanation of symbols]

1 Microcomputer 2 Flow sensor 3 Pressure sensor 4 Vibration sensor 5 Oscillator 6 Resistor 7, 10 Capacitor 8 Discharge transistor 9 Charging resistor 11 Binarization circuit 12 Indicator light 13 Shutoff valve drive transistor 14 Shutoff valve 15 One shot pulse oscillation Circuit 16 Microcomputer reset pulse oscillator circuit 17 Watchdog time-up pulse oscillator circuit 18 Reset switch

Claims (4)

[Claims] 1. A microcomputer comprising at least a microcomputer, a sensor, and a shutoff valve, wherein the microcomputer monitors the usage state of a fluid such as gas or water by a signal from the sensor, and when the abnormal usage state is detected, the microcomputer shuts off the shutoff valve. In a flow rate cutoff device that improves safety by closing and stopping the supply of fluid, an abnormality detection unit that detects an abnormality of a microcomputer and outputs an abnormality signal, and an abnormality signal output by the abnormality detection unit In order to reset the microcomputer, a reset signal output means for outputting a reset signal which is a pulse signal of a predetermined output period, and an abnormality signal output by the abnormality detection means are received and a time-up which is a pulse signal of a predetermined output period A time-up signal output means for outputting a signal, and outputting the time-up signal output from the time-up signal output means. The period is set to be longer than the output period of the reset signal output from the reset signal output means, and the microcomputer detects the time-up signal at the time of initial processing according to the reset signal and determines that there is a reset due to a microcomputer abnormality. Flow rate cutoff device. 2. The flow rate cutoff device according to claim 1, further comprising an indicator light connected to the microcomputer, wherein the microcomputer flashes the indicator light when a time-up signal is detected during initial processing. Control and
A flow rate cutoff device characterized by notifying that there was a reset due to a microcomputer abnormality. 3. The flow rate cutoff device according to claim 1, wherein the microcomputer has a built-in storage unit, and when a time-up signal is detected during initial processing of the microcomputer, the microcomputer stores the storage unit. The flow rate cutoff is characterized by inspecting the data held by and holding the data in the storage unit if the data is normal and clearing the data in the storage unit if the data is abnormal. apparatus. 4. The flow rate cutoff device according to claim 1, wherein the abnormality detecting means includes a charging circuit for charging a capacitor with an electric charge, and a command for the electric charge of the capacitor from a microcomputer. A flow rate cutoff device, comprising: a refresh circuit that discharges at 1, and a binarization circuit that outputs an abnormal signal when the potential of the capacitor rises above a certain value.