JP2012194142A - Gas shut-off device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas shut-off device capable of correctly detecting inner pipe leakage even when gas supply pressure is varied.SOLUTION: The gas shut-off device includes: an ordinary period measurement part 14 for performing ordinary flow rate measurement; a flow rate operation part 15 for calculating a flow rate based on propagation time measured by the ordinary period measurement part 14; a no-flow-rate determination part 16 which when the flow rate calculated by the flow rate operation part 15 is a predetermined range or less, determines no flow rate; a short period measurement part 17 which when the no-flow-rate determination part 16 determines no flow rate, performs measurement of propagation time for several seconds to several hundred seconds at a frequency of once or more per day in a short propagation time measurement period of about 0.001 to 0.1 seconds shorter than the period of the ordinary period measurement part 14 and shorter than gas pressure supply variation; and a leakage determination part 18 which when the gas flow rate calculated by the flow rate operation part 15 is a predetermined value or more and is continued by the predetermined number of times or more, determines gas leakage based on the measurement result of the propagation time by the short period measurement part 17.

Description

  The present invention relates to a gas shut-off device that improves safety in use of gas and improves convenience in use of gas when using gas after a gas meter.

  When using gas appliances, in order to prevent accidents caused by forgetting to turn off gas or leaking gas, etc., the gas business operator managing the gas user's home and the gas supply path should notify the Systems that block supply paths are becoming widespread. As a conventional gas security device, based on the gas flow rate, etc., the gas supply is cut off when a large flow rate flows, or the gas flow is cut off when the gas flows for a long time at a minute flow rate. What shuts off when gas flows for a predetermined time is used.

  In a gas user's house or the like, a gas meter for measuring a gas flow rate is installed at an inlet portion of a gas supply path. Conventionally, as this type of gas meter, a membrane-type gas meter that integrates the amount of gas that flows at a predetermined flow rate is generally used, but recently, an instantaneous flow rate is obtained using an ultrasonic signal, and this instantaneous flow rate is calculated. There has also been proposed an ultrasonic gas meter that measures the flow rate of gas by integrating.

Japanese Patent No. 3490064

  However, in the conventional configuration, when a large-scale combustion device such as GHP is installed in the vicinity, and the gas supply pressure fluctuation is severe, the fluctuation flow rate is measured because the gas supply pressure fluctuation period is shorter than the flow measurement period. Therefore, if it is determined that the inner pipe leaks, or if the threshold value is changed to prevent erroneous determination due to fluctuations in the gas supply pressure, it may not be detected even if leakage actually occurs. In addition, when the measurement cycle is always shortened, there is a problem that battery consumption increases.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a gas shut-off device that can correctly detect an inner pipe leak even when there is a fluctuation in gas supply pressure.

  In order to solve the above-described conventional problems, a gas shutoff device according to the present invention includes a measurement flow path communicating with a gas supply pipe, and a pair of ultrasonic transceivers disposed on the upstream side and the downstream side of the measurement flow path. A propagation time measuring unit for measuring the propagation time of the ultrasonic wave between the pair of ultrasonic transceivers, and a normal period measurement for measuring the propagation time of the ultrasonic wave by the propagation time measuring unit for each first period A flow rate calculation unit that calculates a flow rate from the propagation time measured by the normal period measurement unit, a no flow rate determination unit that determines no flow rate from a calculation result of the flow rate calculation unit, and no flow rate in the no flow rate determination unit A short period measuring unit that measures the propagation time of ultrasonic waves at the propagation time measuring unit periodically and every second period shorter than the first period, and leakage of the gas supply pipe A leakage determination unit for detecting, the leakage determination unit , Which detects the leakage of the gas supply tube by using the propagation time measured in the short period measuring unit.

As a result, by measuring the flow rate with a period shorter than the gas supply pressure fluctuation, in the state where there is a periodic gas supply pressure fluctuation, it is averaged by measuring when the flow rate increases or decreases with the gas supply pressure Therefore, the gas flow rate can be measured accurately. In addition, since the flow rate is measured periodically with a short period only for a short time, it can be realized without increasing battery consumption.

  According to the gas shut-off device of the present invention, even if a gas supply pressure fluctuation due to GHP or the like occurs, it is possible to determine the leakage of the inner pipe, to ensure the safety in using the gas, and to improve the convenience in using the gas. Can be improved.

The block diagram which shows the structure of the gas interruption | blocking apparatus in Embodiment 1 of this invention. The block diagram which shows arrangement | positioning of the ultrasonic transmitter-receiver in the embodiment The figure which shows the relationship between the gas supply pressure fluctuation | variation in the same embodiment, and a measurement cycle The block diagram which shows the structure of the gas interruption | blocking apparatus in the 2nd Embodiment of this invention.

  A first invention includes a measurement channel communicating with a gas supply pipe, and a pair of ultrasonic transmitters / receivers disposed on the upstream side and the downstream side of the measurement channel, and an ultrasonic wave between the pair of ultrasonic transmitters / receivers. A propagation time measuring unit for measuring the propagation time of the sound wave, a normal period measuring unit for measuring the propagation time of the ultrasonic wave by the propagation time measuring unit for each first period, and the propagation measured by the normal period measuring unit When the flow rate calculation unit that calculates the flow rate from time, the no flow rate determination unit that determines no flow rate from the calculation result of the flow rate calculation unit, and the no flow rate determination unit determine that there is no flow rate, periodically and the first A short cycle measuring unit that measures the propagation time of the ultrasonic wave at the second cycle shorter than the cycle of the period, and a leakage determination unit that detects leakage of the gas supply pipe, and the leakage The determination unit calculates the propagation time measured by the short period measurement unit. The gas supply pipe leak is detected, and the flow rate is measured at a cycle shorter than the gas supply pressure variation, so that when the gas supply pressure varies, the flow rate increases in a state where there is a periodic gas supply pressure variation. Since it can be averaged by measuring even when it decreases, the gas flow rate can be measured accurately. Further, since the flow rate is measured at a short cycle for a predetermined time every predetermined time, it can be realized without increasing the consumption of the battery.

  In the second invention, in particular, the second period of the first invention is 1/10 or less of the first period.

  According to a third aspect of the present invention, in particular, in the first or second aspect, the gas for determining the presence or absence of fluctuations in the gas supply pressure from the difference between the minimum gas flow rate and the maximum gas flow rate obtained from the propagation time measured by the short period measurement unit. Supply pressure fluctuation presence / absence determination section, gas supply pressure fluctuation determination section that estimates a gas supply pressure fluctuation period based on the flow rate obtained from the propagation time measured by the short cycle measurement section, and determination by the gas supply pressure fluctuation determination section Since it has a measurement cycle changing unit that changes the first cycle so that it does not match the cycle, it can be measured in a state that does not match the cycle of the gas supply pressure by changing the cycle of the normal cycle measurement unit. In a state where there is a typical gas supply pressure fluctuation, the gas flow rate can be accurately measured because it can be averaged by measuring both when the flow rate increases and decreases with the gas supply pressure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a gas cutoff device according to Embodiment 1 of the present invention. In the present embodiment, a configuration example of a gas cutoff device using a gas meter installed in a gas user's house or the like will be described.

  The gas shut-off device 10 is installed at a predetermined position outdoors or indoors.

  Embodiments of the present invention will be described below with reference to the drawings. The gas cutoff device 10 includes a propagation time measurement unit 12, a timer unit 13, a normal cycle measurement unit 14, a flow rate calculation unit 15, a no flow rate determination unit 16, a short cycle measurement unit 17, and a leak determination unit disposed in the measurement flow path 30. 18, the control part 20, the cutoff valve 21, the cutoff valve drive part 22, and the battery 23 are comprised.

  As shown in FIG. 2, the propagation time measuring unit 12 includes a measurement channel 30 having a rectangular cross section that communicates with the measurement channel 30, and the upstream side of the opposite channel wall of the measurement channel 30. On the downstream side, a pair of ultrasonic transceivers 31 and 32 are arranged. These ultrasonic transmitters / receivers 31 and 32 are set so that the ultrasonic propagation path obliquely crosses the gas flow flowing through the measurement flow path 30, and the ultrasonic waves are alternately transmitted / received, so that the ultrasonic flow is sequentially transmitted and received. Propagation of ultrasonic waves in the opposite direction.

  The timer unit 13 counts the time of the ultrasonic signal propagation time measurement cycle. Usually, the time for measurement with a period of about 2 seconds is counted, and the fluctuation of the gas supply pressure due to the operation of GHP or the like is about 0.01 seconds to 0.1 seconds in order to eliminate the influence on about 10 Hz. The measurement cycle is counted.

  The normal period measuring unit 14 measures the propagation time using the propagation time measuring unit 12 at a propagation time measuring period of about 2 seconds counted by the timer unit 13.

  The flow rate calculation unit 15 calculates the flow rate of the gas flowing through the measurement flow path from the propagation time detected by the propagation time measurement unit 12 and the propagation time determined from the gas supply.

  The no flow rate determination unit 16 determines whether the flow rate obtained by the flow rate calculation unit 15 is equal to or less than a predetermined range.

  When the flow rate determining unit 16 determines that the flow rate is equal to or less than the predetermined range, the short cycle measuring unit 17 has a cycle shorter than the gas pressure supply fluctuation by 1/10 or less of the cycle counted by the timer unit 13. The propagation time is periodically measured for several seconds to several hundred seconds with a frequency of about once per day using the propagation time measuring unit 12 in a short propagation time measurement cycle of about 001 seconds to 0.1 seconds. The measurement time is set in consideration of battery consumption.

  Based on the result of measuring the propagation time by the short cycle measuring unit 17, the leakage determining unit 18 determines that the gas has leaked when the gas flow rate calculated by the flow rate calculating unit 15 is a predetermined value or more and continues for a predetermined number of times. Is.

  The control unit 20 stores flow rate information such as gas flow rate value information and integrated flow rate value information calculated by the flow rate calculation unit 15, and various types of information used in the gas shut-off device 10, and has a function of a security processing unit. It performs security processing such as operation control of each part of the gas shut-off device, communication, warning and gas shut-off. Here, the control unit 20 includes a processor and an operation program that constitute a microcomputer (microcomputer) and the like, and each function is realized by executing a predetermined operation program and performing corresponding processing in the processor.

  The shut-off valve 21 is connected in the path of the measurement flow path 30 and shuts off the gas supply by closing the measurement flow path 30 with a signal from the shut-off valve drive section 22 based on an instruction from the control section 20. is there.

  The battery 23 uses a lithium battery or the like as a power source for the gas cutoff device.

  Next, a flow rate measurement method in the propagation time measurement unit 12 will be described with reference to FIG. In FIG. 2, the distance between the ultrasonic transceivers 31, 32, that is, the measurement distance is L, the angle of the ultrasonic propagation path with respect to the gas flow is φ, the ultrasonic propagation time from the upstream to the downstream of the ultrasonic transceivers 31, 32 Is t1, the propagation time of ultrasonic waves from downstream to upstream is t2, and the speed of sound is C, the flow velocity V is obtained by the following equation.

V = L / 2 cos φ ((1 / t1) − (1 / t2)) (1)
The instantaneous flow rate of the gas flow is calculated from the flow velocity V and the cross-sectional area of the measurement channel 30.

  Next, the operation will be described with reference to FIG. FIG. 3 is a diagram showing the relationship between the flow rate waveform when the gas supply pressure fluctuation occurs due to the use of GHP or the like and the measurement cycle. As shown in the figure, the normal cycle measurement unit 14 counts by the timer unit 13. The propagation time measurement unit 12 is repeatedly used to measure the propagation time at the measurement period (first period) of about 2 seconds. Further, the short cycle measuring unit 17 described later measures the propagation time at a cycle (second cycle) that is equal to or less than 1/10 of the measurement cycle of the normal cycle measuring unit 14 and shorter than the cycle of the pressure fluctuation. .

  The flow rate calculation unit 15 converts the flow rate flowing through the measurement channel 30 from the propagation time detected by the propagation time measurement unit 12 and the propagation time determined from the gas supply.

  The flow rate determination unit 16 determines that there is no flow rate if the flow rate obtained by the flow rate calculation unit 15 is equal to or less than a predetermined range. If the flow rate determination unit 16 determines that there is no flow rate, the short cycle measurement unit 17 The propagation time is regularly measured at a frequency of about once a day with a short propagation time measurement cycle of about 0.001 seconds to 0.1 seconds, which is a cycle shorter than the gas pressure supply fluctuation counted at 13. Since the time T (for example, several seconds to several hundred seconds) or a predetermined number of times is performed, and the propagation time fluctuation due to the gas supply pressure fluctuation is averaged, the influence of the gas supply pressure fluctuation can be eliminated.

  Based on the result of measuring the propagation time by the short cycle measuring unit 17, the leakage determining unit 18 determines that the gas has leaked when the gas flow rate calculated by the flow rate calculating unit 15 continues for a predetermined number of times greater than or equal to a predetermined value.

  Note that the cycle of short-term measurement, the frequency of about once a day, the predetermined range of the flow rate, the number of times that it is determined that leakage is detected, and the like are set in advance in storage means such as a ROM, RAM, or EEPROM of the microcomputer.

  In the present embodiment, the configuration in which the pair of ultrasonic transmitters / receivers 31 and 32 are arranged on the upstream side and the downstream side of the channel wall facing the measurement channel 30 has been described as an example. It is also possible to correspond to a configuration in which an upstream ultrasonic transmitter / receiver 31 is installed at the inlet of the transmitter and a downstream ultrasonic transmitter / receiver 32 is installed at the outlet of the measurement flow channel.

  Also, the ultrasonic transmitter / receiver 31 on the upstream side and the ultrasonic transmitter / receiver 32 on the downstream side are installed on the same surface of the flow channel wall of the measurement flow channel, and the ultrasonic wave is transmitted / received via the reflective surface of the flow channel wall. It can also correspond to a configuration for transmitting and receiving ultrasonic signals of the ultrasonic transmitter 31 and the ultrasonic transmitter / receiver 32 on the downstream side.

(Embodiment 2)
FIG. 4 is a block diagram showing the configuration of the gas cutoff device according to Embodiment 2 of the present invention.

  Here, the gas supply pressure fluctuation presence / absence determination unit 40 determines the presence / absence of gas supply pressure fluctuation from the difference between the minimum gas flow rate and the maximum gas flow rate using the flow rate detected by the short cycle measurement unit 17.

  The gas supply pressure fluctuation determination unit 41 estimates the gas supply pressure fluctuation period based on the flow rate detected by the short period measurement unit 17.

  The measurement cycle changing unit 42 changes the supply cycle of the gas by changing the measurement cycle of the normal cycle measurement unit 14 by about 0.001 seconds to 0.1 seconds so as not to match the cycle determined by the gas supply pressure variation determination unit 41. This is to average the propagation time fluctuation due to.

  With the above configuration, the cycle of the normal cycle measurement unit can be changed, and measurement can be performed in a state that does not match the cycle of the gas supply pressure. Since it can be averaged by measuring both when and when it becomes less, the gas flow rate can be measured accurately.

  Since the present invention can accurately determine the detection of gas leakage without being affected by fluctuations in the supply pressure of the gas, it is possible to prevent gas use safety and misjudgment. Thereby, it is useful for the gas interruption | blocking apparatus which aims at the safety on use of gas, and improves the convenience on use of gas.

DESCRIPTION OF SYMBOLS 10 Gas cutoff device 12 Propagation time measurement part 13 Timer part 14 Normal period measurement part 15 Flow rate calculation part 16 No flow rate determination part 17 Short period measurement part 18 Leakage determination part 20 Control part 21 Shut-off valve 22 Shut-off valve drive part 23 Battery 30 Measurement Flow path 31, 32 Ultrasonic transceiver 40 Gas supply pressure fluctuation presence / absence determination unit 41 Gas supply pressure fluctuation determination unit 42 Measurement cycle change unit

Claims (3)

A measurement channel communicating with the gas supply pipe;
A pair of ultrasonic transmitters / receivers disposed on the upstream side and the downstream side of the measurement channel, a propagation time measuring unit for measuring the propagation time of ultrasonic waves between the pair of ultrasonic transmitters / receivers,
A normal period measurement unit that measures the propagation time of the ultrasonic wave in the propagation time measurement unit for each first period;
A flow rate calculation unit that calculates a flow rate from the propagation time measured by the normal period measurement unit;
No flow rate determination unit for determining the absence of flow rate from the calculation result of the flow rate calculation unit,
A short period measurement unit that measures the propagation time of the ultrasonic wave at the propagation time measurement unit periodically and every second period shorter than the first period when the flow rate determination unit determines that there is no flow rate; ,
A leakage determination unit for detecting leakage of the gas supply pipe,
The leak determination unit is a gas shut-off device that detects a leak of the gas supply pipe using the propagation time measured by the short period measurement unit. The gas cutoff device according to claim 1, wherein the second period is set to 1/10 or less of the first period. A gas supply pressure fluctuation presence / absence determining unit that determines the presence / absence of gas supply pressure fluctuation from the difference between the minimum gas flow rate and the maximum gas flow rate obtained from the propagation time measured by the short period measurement unit;
A gas supply pressure fluctuation determination unit that estimates a gas supply pressure fluctuation period based on the flow rate obtained from the propagation time measured by the short period measurement unit;
3. The gas cutoff device according to claim 1, further comprising a measurement cycle changing unit that changes the first cycle so as not to coincide with the cycle determined by the gas supply pressure fluctuation determining unit.

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