JPS6232369B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel cutoff control device using a microcomputer powered by a battery.

Conventionally, there have not been many fuel cutoff control devices that use batteries as a power source. In addition, many common devices that use batteries as a power source, if the battery voltage drops,
For example, as seen in devices that already have a display, such as watches and calculators, it is only when the user becomes aware of an abnormal condition such as an increase in time error or the inability to perform calculations that the battery loses its original function. It is becoming clear that the In this way, there are many products that do not guarantee operation when the voltage drops.

The function of the fuel cutoff control device is to install it at the entrance of the gas supply line, such as the one found in each home,
The system automatically shuts off the supply path if it is determined that there is an abnormality based on the flow rate, such as during continuous gas outflow, and such equipment must maintain monitoring operation all year round. In addition, this type of device is installed far away (outdoors), and daily users cannot frequently check the presence or absence of batteries when using fuel.
Furthermore, the installation environment is subject to conditions such as a wide temperature range. Therefore, it is necessary to detect battery voltage drop with high precision and to reliably notify this information.

The present invention aims to expand the power supply voltage range by performing a high-precision voltage check that is not dependent on the ambient temperature in a device with a battery voltage check function added, thereby making it possible to monitor the device all year round. The purpose is

In order to achieve the above object, the present invention includes a reference voltage generation circuit, a temperature correction circuit that performs temperature correction of this generated voltage, and a power supply voltage comparison circuit that compares the output voltage of this temperature correction circuit with the voltage of a battery power source. ,
The basic configuration includes a main control section that drives the reference voltage generation circuit, the temperature correction circuit, and the power supply voltage comparison circuit at predetermined intervals, and with this configuration, the battery voltage can be made dependent on the ambient temperature. Without,
It can be checked intermittently.

An embodiment of the present invention will be described below with reference to FIG.

In the figure, 1 is a power supply unit consisting of a battery, 2 is a clock generation unit that generates a clock that is a reference for time counting, 3 is a sensor input unit that inputs a fuel flow signal, and 4 is a light emitting unit that displays a plurality of different states. A display section consisting of a diode (LED) and a liquid crystal display for displaying the cause of an abnormality, 5 a shutoff section consisting of a self-holding solenoid valve that shuts off the fuel supply path, 6 a main control section consisting of a microcomputer, and 7 a control section from a diode. A temperature correction circuit 9 having a temperature sensing element that corrects the voltage from the reference voltage generation circuit, and a voltage comparator that compares the output voltage of the temperature correction circuit and the voltage of the power supply section 1. This is a voltage detection section consisting of a power supply voltage comparison circuit 10.

Next, the operation of the above configuration will be explained.

First, when the power supply section 1 is turned on, the entire control device becomes operational. The main control section 6 consists of a microcomputer, which inputs the flow rate signal from the sensor input section 3 and the clock signal from the clock generation section 2, and measures the fuel flow rate per unit time from the number of flow rate signals at arbitrary time intervals. do. The microcomputer has registered in advance flow rate data that serves as a reference for shutting off or displaying an alarm, and compares the measurement results with the flow rate data. The registered flow rate is, for example, data on the maximum flow rate that must not be exceeded under normal usage conditions as specified by the gas meter in each home in the gas supply route (this value is exceeded only when the gas valve is opened). ), or if the elapsed time at the same flow rate exceeds the time specified by that flow rate, flow rate data can be used to determine that the appliance was forgotten to be turned off and shut off. . As a result of the comparison, if the measured flow rate and time exceed the above data, display data is output to the display section 4, and a cutoff output is also performed to the cutoff section 5. It also has a repeat timer that counts the clock signal from the clock generator 2 and operates the voltage detector 7 periodically (for example, every 24 hours). A signal from section 7 is input to check the presence or absence of battery voltage, and at the same time an alarm is displayed on display section 4. A diode in the reference voltage generating circuit 8, which constitutes a part of the voltage detecting section 7, generates a relatively low voltage (approximately 0.6 to 0.7 V) having a negative temperature coefficient. Therefore, it is possible to detect a battery voltage of about 1.5 to 2V. Further, a temperature correction circuit 9 having a temperature sensing element having a positive temperature coefficient for temperature correcting this reference voltage corrects the reference voltage having a negative temperature coefficient of the diode. It is possible to generate a judgment voltage that is not affected even if the voltage varies over a wide range. Furthermore, battery consumption can be detected by the power supply voltage comparison circuit 10 that compares this determination voltage with the battery voltage. Therefore, the reference voltage for determining battery exhaustion can be set to a value close to the minimum operating voltage of other circuit sections, and the power supply voltage that can be used can be expanded.

Figure 2 is based on the block diagram in Figure 1.
This is a specific example. The same numbers as in FIG. 1 indicate the same contents. Reference numeral 11 denotes a crystal oscillator whose frequency is divided by a counter 12 to generate, for example, a clock pulse with a period of 0.1 seconds at the _I1 input terminal of the main controller 6. Reference numeral 21 is a reed switch for measuring the flow rate of fuel, which is installed close to a meter such that a magnet moves back and forth depending on the gas flow rate.
Transistor 22 is responsive to operation of reed switch 21. Therefore, the main control unit 6 calculates the fuel flow rate per unit time at any given time based on the number of pulses coming into the input terminal of _I2 and the time counted by the clock pulses coming into the input terminal of _I1 . can be measured. 13 to 15 are light emitting diodes (LEDs) connected to each other by transistors.
16, 17, and 18 currents,
These are controlled by output terminals O ₁ , O ₂ , O ₃ of the main control section 6. 19 is a transistor for driving the self-holding electromagnetic valve 20, and the main control unit 6
is controlled by the output terminal O ₄ of. Transistors 24 and 25 are connected to the O ₅ terminal of the main control section 6 and are periodically driven to supply power to the voltage detection section 7 . 25 is a diode and generates a reference voltage V _D. The temperature correction circuit includes a voltage comparator 26, a temperature-sensitive resistance element 27 having a positive temperature coefficient, a resistor 28 connected in series with the temperature-sensitive resistance element, and a judgment voltage V _S and a power supply voltage comparison circuit 10. The reference voltage generating circuit 8 corrects the temperature-dependent voltage V _D of the reference voltage generating circuit 8 to generate a temperature-independent voltage V _S .
The power supply voltage comparison circuit 10 includes a voltage comparator 31 that compares the judgment voltage V _S with the voltage at the connection point of the resistors 29 and 30 that supply the power supply voltage, and transmits the battery voltage judgment result to the input terminal I ₃ of the main control unit 6. Outputs the signal. The voltage V _O at the connection point of the output terminal of the voltage comparator 26 is controlled so that V _E applied to the input terminal of the voltage comparator 26 of the temperature correction circuit 9 is always equal to the reference voltage V _D . For example, if V _D changes from 0.6 V to 0.7 V due to a decrease in ambient temperature, V _O shifts to the high side (resistor 28 is R ₁ and temperature sensitive resistance element 27 is R ₂ ) V _S ×R V _O is adjusted so that ₁ /R ₁ +R ₂ = 0.7V, but at this time the temperature sensitive resistance element 27 having a positive temperature coefficient is under the same temperature condition as the diode 25,
This resistance is decreasing, and the determination voltage V _S does not change.

In this way, it is possible to reduce power consumption by intermittently operating the voltage detection section by the main control section 6, and it is also possible to check the battery voltage without depending on the low voltage temperature. , it becomes possible to set the value of the determination voltage close to the minimum operating voltage of other circuit sections, and it is possible to expand the usable voltage range.

As described above, the fuel cutoff control device of the present invention provides the following effects. By adding a diode reference voltage generation circuit and a temperature compensation circuit to the voltage detection section, which operates intermittently by the main control section with a timer function, it is possible to save power and achieve high precision that is independent of temperature. It becomes possible to check the battery voltage and enable year-round monitoring operation of the device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a fuel cutoff control device according to an embodiment of the present invention, and FIG. 2 is a specific circuit diagram of FIG. 1. 1...Power supply section, 3...Sensor input section, 5...
Shutoff unit, 6... Main control unit, 7... Voltage detection unit, 8
...Reference voltage generation circuit, 9 ...Temperature correction circuit, 1
0...Power supply voltage comparison circuit.

Claims (1)

[Claims] 1. A power supply section consisting of a battery, a sensor input section that inputs a fuel flow rate signal, a cutoff section that cuts off a fuel supply path, a reference voltage generation circuit consisting of a diode, and temperature-correcting the voltage from the reference voltage generation circuit. A voltage detection unit including a temperature correction circuit and a power supply voltage comparison circuit that compares the output voltage of the temperature correction circuit and the voltage of the power supply unit, and flow rate data that serve as a criterion for driving at least the cutoff unit are registered in advance. It has an output terminal for driving each of the data storage section, the cutoff section, and the voltage detection section, the sensor input section, and an input terminal for inputting signals from the voltage detection section. A fuel cutoff control device comprising a main control section that drives the main control section and determines an input signal from a voltage detection section.