JPH08210631A - Sensor input and output device for gas safety apparatus - Google Patents

Abstract

PURPOSE: To reduce a current consumption and to simultaneously stabilize the voltage of a supply power source for a long period by supplying power to meet the timing of detecting a pressure by a control circuit and so controlling as to increase the number of times of pressure detections by a threshold value discriminator. CONSTITUTION: A sensor input and output device holds the power source voltage of a pressure sensor 1 and a threshold value discriminator 3 supplied with power from a constant-voltage circuit 6 by the voltage stabilizing operation of the circuit 6 and the reference voltage of an A-D converter 2 constant to eliminate the influence of the voltage change of a battery by using for a long period and the voltage change at the time of loading of operating a shut-off valve. A control circuit 5 switches a power source switching circuit 4 to meet the timing for inputting a pressure value, intermittently operates the sensor 1, the discriminator 3 and the converter 2 to reduce the current consumption per time mean. The circuit 5 measures by the discriminator 3 having low current consumption in the case of monitoring the specific pressure such as high or lower voltage of high measuring frequency, and reduces the current consumption by decreasing the measuring frequency by the converter 2 having much current consumption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor input / output device for a gas security device used in a gas supply path.

[0002]

2. Description of the Related Art In recent years, for the purpose of safely using city gas or LP gas, when the amount of fuel gas (hereinafter referred to as gas) used is measured and the amount of use increases abnormally,
2. Description of the Related Art Gas meters with a safety device that cut off a gas passage are becoming widespread when it is detected that the gas meter is being used for a long time, which is far from the normal use state.

In this type of gas meter with a safety device, a detection signal of the gas flow rate is taken into a control circuit, processed by an internal microcomputer to monitor the gas flow rate, and if there is an abnormality, a shutoff signal is output to shut off the shutoff valve. Close. The gas meter with safety device is equipped with a long-term reliable power supply battery such as a lithium battery, supplies the circuit current and the drive current of the shutoff valve, and has the characteristic that no battery replacement is required during the installation and use period of the gas meter with safety device Have

[0004]

However, in the conventional structure, safety is maintained in safety only in the portion related to the flow rate of the gas to be detected, and abnormal combustion of the gas appliance due to fluctuations in the gas supply pressure. With regard to problems such as disappearance and disappearance, safety is ensured by interlocking with an external sensor such as a gas leak detector, and the gas supply pressure is not directly detected to shut off the gas passage. Some safety devices were equipped with a mechanical pressure switch that had a simple contact output, but this was only for detecting the pressure drop due to the opening of the gas passage. It wasn't about controlling security devices.

In recent years, however, semiconductor pressure sensors have become relatively inexpensive and easy to use, and general-purpose ICs for peripheral circuits such as A / D conversion circuits have been marketed, and semiconductor pressure sensors are used for A / D converters. It became possible to digitize the signal in the above and control it by processing it with a microcomputer, and it became possible to detect the gas pressure linearly and use it for the safety of the gas passage.

However, the power source of the safety device is a battery such as a lithium battery, and the pressure sensor and the current consumption of the A / D conversion are reduced in order to make it possible to replace the battery during the installation period of the safety device. In order to improve the accuracy of pressure detection and pressure detection, there are many issues to be solved regarding battery power sources, such as the need for long-term stability of the voltage of the power supply to the pressure sensor and A / D converter. It had been.

In order to solve the above problems, the present invention is a gas that reduces the current consumption of a pressure sensor and an A / D converter, at the same time stabilizes the voltage of a power supply for a long time, and rationalizes input / output control. It is intended to provide a sensor input / output device for a security device.

[0008]

In order to solve the above-mentioned problems, the means of the sensor input / output device of the gas safety device of the present invention comprises a pressure sensor for measuring the pressure in the gas passage and an analog output voltage of the pressure sensor. A / D conversion circuit for converting quantity to digital signal, threshold judgment circuit for judging only certain threshold value of pressure measurement value, pressure sensor, threshold judgment circuit, and reference of A / D conversion circuit A constant voltage circuit for converting the voltage supplied to the voltage input to a constant voltage, one of which is a battery, the pressure sensor, the threshold value determination circuit and the A
The power supply switching circuit that opens and closes the power supply to the reference voltage input of the A / D conversion circuit, and the other one that opens and closes the power supply from the battery to the A / D conversion circuit, and the power supply switching as one operation of control. Control the circuit switching timing, and
And a control circuit for controlling the / D conversion circuit and the threshold value judgment circuit.

[0009]

With the above structure, the sensor input / output device of the gas safety device of the present invention has the function of stabilizing the voltage of the constant voltage circuit.
The pressure sensor to which power is supplied from here, the power supply voltage of the threshold value judgment circuit and the reference voltage of the A / D conversion circuit are kept constant, fluctuations in battery voltage due to long-term use, and load such as shutoff valve operation Eliminate the effects of voltage fluctuations over time.

The control circuit performs the switch operation of the power source switching circuit in accordance with the timing of input processing of the pressure value,
The pressure sensor, threshold value discrimination circuit, and A / D conversion circuit are operated intermittently to enable reduction of current consumption per time average.

Further, the control circuit monitors the specific pressure such as the lowest pressure which is frequently measured by the threshold value discriminating circuit which consumes less current, and the A / D conversion circuit which consumes more current consumes the measuring cycle. It is made longer to reduce the measurement frequency to reduce the current consumption per time average.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an input / output device of a gas safety device according to the present invention will be described below with reference to the drawings.

In FIG. 1, the flow rate signal detected by the flow rate sensor 9 provided inside the gas meter body 10 is input from the input terminal P6 of the control circuit 5 and processed by the control circuit 5, and as a result, an abnormal current is confirmed. If so, a shutoff signal is output from the output terminal P7, the valve drive circuit 7 drives the shutoff valve 8, and the gas passages A and B are shut off.

The pressure sensor 1 installed in a part of the gas passage (in this embodiment, installed at the gas passage inlet A portion, but not limited to this) converts the pressure change in the gas passage into a voltage value and outputs it. To do. The voltage value of the output voltage of the pressure sensor 1 is measured by the threshold value determination circuit 3 or the A / D conversion circuit 2, and the result of the threshold value determination is the control circuit 5 as an “H” or “L” signal. Is input to the input terminal P1 of
The D-converted pressure measurement value is input to the input terminal P2 as a digital signal. When the pressure information is processed by the control circuit 5 and an abnormality is confirmed in the pressure fluctuation, a shutoff signal is output from the output terminal P7, the valve drive circuit 7 drives the shutoff valve 8, and the gas passages A and B are shut off. To be done.

In order to measure the gas pressure with high accuracy, the power supply voltage supplied to the pressure sensor 1, the threshold value judgment circuit 3, and the reference voltage input of the A / D conversion circuit 2 is constant. Therefore, the constant voltage circuit 6 is provided so that the constant voltage is supplied to each circuit.

The control circuit 5 causes the pressure sensor 1, the threshold value judgment circuit 3 and the A / D conversion circuit 2 to perform an intermittent operation in order to reduce current consumption. High measurement frequency (one example: every second)
The monitoring of a specific pressure such as the minimum pressure is performed by the threshold value determination circuit 3 that consumes less current, and the A / D conversion circuit 2 that consumes more current consumes a longer measurement cycle and a lower measurement frequency (one example:
Every 15 minutes) The current consumption per time average is reduced.
For this reason, two switches, SW1 and SW2, are provided inside the power supply switching circuit 4 and are controlled by different output terminals P4 and P5 of the control circuit 5 to open and close the power supply at different cycles.

The voltage on the output side (OUT) of the constant voltage circuit 6 is set as low as possible in the power supply voltage range in which the pressure sensor 1 operates, and the voltage between the input and output (IN-OU) is set.
The potential difference of T) is earned so that the constant voltage operation can be obtained up to a place where the voltage drop of the battery 11 is lower. A / D
Although the power source of the conversion circuit 2 is not a constant voltage, the A / D conversion operation is determined by the reference voltage, and this voltage is stabilized by the output voltage of the constant voltage circuit 6, so it is not affected by the battery voltage. The current consumption in the reference voltage input unit is small, and it may be connected to the power supply on the SW1 side, which is frequently opened and closed.

[0018]

As is apparent from the above description, in the sensor input / output device of the gas safety device of the present invention, the control circuit supplies power at the timing of pressure detection, and the pressure in the threshold determination circuit is supplied. Since the control is performed so as to increase the number of times of detection, 1) it is possible to suppress the consumption of the power supply battery to a low level and also to expect stable and highly accurate pressure measurement even when the battery voltage fluctuates.

2) The power supply of the A / D conversion circuit is common to the microcomputer, and no special level shifter is required for exchanging signals between the A / D conversion circuit and the microcomputer.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a sensor input / output device of a gas safety device according to an embodiment of the present invention.

[Explanation of symbols]

 1 Pressure sensor 2 A / D conversion circuit 3 Threshold value discrimination circuit 4 Power supply switching circuit 5 Control circuit 6 Constant voltage circuit

Claims (1)

[Claims] 1. A pressure sensor for measuring a pressure in a gas passage, an A / D conversion circuit for converting an output voltage of the pressure sensor from an analog amount into a digital signal, and a threshold value in a measurement range of the pressure sensor. A threshold value determination circuit for determining only the pressure sensor, the threshold value determination circuit,
And a constant voltage circuit for converting the voltage supplied to the reference voltage input of the A / D conversion circuit to a constant voltage, and at least two or more systems of switches, one of which is a battery to the pressure sensor,
The power supply to the reference voltage input of the threshold judgment circuit and the A / D conversion circuit is opened and closed.
A power supply switching circuit that opens and closes the power supply to the conversion circuit, and performs overall control of the security device, and controls the switching timing of the power supply switching circuit as one operation of control,
A sensor input / output device of a gas safety device, comprising: a control circuit that processes main signals of the A / D conversion circuit and the threshold value determination circuit to perform a control operation as a safety device.