JP2015215116A - Gas shut-off device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas shut-off device capable of suppressing erroneous determination of internal pipe leakage.SOLUTION: A gas shut-off device includes: section calculation means 8 for calculating a section average flow rate by accumulating a flow rate for predetermined time, and for acquiring a maximum flow rate and a minimum flow rate during the time; and flow rate presence/absence determination means 9 for determining presence/absence of a gas flow rate from the flow rate from the section calculation means 8. When a difference between maximum and minimum of the section average flow rate and the section average flow rate Qt is within a determination allowable range, the flow rate presence/absence determination means 9 calculates the average flow rate by holding the difference between maximum and minimum of the section average flow rate in an ascending order for N-pieces, and determines that there is no flow rate in the case where the average flow rate calculated by a certain number of times is within an average determination flow rate, and also, determines that there is a flow rate in the case where the calculated average flow rate is larger than the average determination flow rate.

Description

  The present invention relates to a gas shut-off device that detects the presence or absence of internal pipe leakage.

  Conventionally, by using an average value for the number of determinations of the section average flow rate by the section calculation means, it is possible to stably determine that there is no flow even under pulsation, and pulsation due to the use of a gas engine, heat pump, air conditioner, etc. A gas shut-off device is disclosed that prevents an erroneous determination that an inner pipe leakage warning is generated even in an environment in which there is no actual leakage even in an environment in which a leak occurs (for example, patents) Reference 1).

  Further, when the flow rate based on the flow rate signal from the flow rate sensor is greater than a predetermined determination value and is greater than the predetermined determination value for a predetermined time or more, it is determined that there is an inner pipe leak, and the shut-off valve is Drive to shut off the gas flow path. Since the flow sensor is located on the downstream side of the shut-off valve, when the gas flow is shut off by the shut-off valve, the flow rate flowing into the flow sensor becomes zero. At this time, if the inner pipe leaks, the gas remaining in the blocked inner pipe leaks and the gas pressure decreases. On the other hand, when the gas pressure does not decrease, the flow rate flowing into the flow rate sensor is zero, so that the zero flow rate value of the flow rate sensor can be determined. In this case, if the flow rate value based on the flow rate signal from the flow rate sensor does not become zero, it is determined that there is an abnormality in the flow rate sensor. For this reason, since the abnormality by the secular change etc. of a flow sensor can be judged, the gas meter which can improve the misjudgment of an inner pipe leak is disclosed (for example, patent document 2).

JP 2010-216724 A JP 2004-219259 A

  However, in the conventional gas shut-off device disclosed in Patent Document 1 and the gas meter disclosed in Patent Document 2, there is no gas leakage in the gas pipe, and the gas pipe capacity (particularly in an unused state in which no gas flows in the gas pipe) In large-capacity piping for business use, etc., gas flow (forward flow or reverse flow) occurs over a long period of time due to temperature change (rise / decrease), etc. (hereinafter referred to as breathing motion), and internal pipe leakage There was a problem that a warning may occur.

  This invention solves the said conventional subject, and it aims at providing the gas interruption | blocking apparatus which can suppress the misjudgment of an inner pipe | tube leak.

  In order to solve the above-described conventional problems, a gas shut-off device according to the present invention is connected to a gas supply pipe and measures flow rate measuring means for measuring a gas flow rate at regular time intervals, and calculation means for obtaining a flow rate value by the flow rate measuring means. The interval calculation means for calculating the average flow rate during the predetermined time period by accumulating the flow rate value calculated by the calculation means for a predetermined time, and the number of times each data of the interval calculation means is set in advance. N in the ascending order of the absolute value of the maximum and minimum difference, and a flow rate presence / absence determining means for calculating the average of the N average flow rates to determine the presence or absence of the gas flow rate. When the section average flow rate is within the allowable judgment range and the average flow rate is within the average determination flow rate, it is determined that there is no flow rate. It is intended.

  By using the gas shut-off device of the present invention, it is possible to determine only by the N section average flow rate in the vicinity of the average during the inner tube leakage determination period. It is possible to reduce the occurrence of a leakage warning.

The block diagram of the gas meter in Embodiment 1 of this invention. The schematic block diagram of the ultrasonic flow measurement means. The characteristic view which shows the change of the gas flow rate. The figure which shows the determination threshold value of the same area average flow volume. The flowchart which shows the operation | movement procedure of the same flow amount presence determination. The flowchart which shows the operation | movement procedure of the flow volume presence determination in Embodiment 2 of this invention. The table | surface about the holding | maintenance operation | movement of the total flow volume in Embodiment 2 of this invention. The figure shown about the holding | maintenance operation | movement of the total flow in Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiment.

  According to a first aspect of the present invention, there is provided a flow rate measuring unit that is connected to a gas supply pipe and measures a gas flow rate at regular time intervals, a calculation unit that obtains a flow rate value by the flow rate measurement unit, and a flow rate value calculated by the calculation unit. The interval calculation means for calculating the average flow rate during the predetermined time and calculating the maximum flow rate and the minimum flow rate between them, and holding the N pieces of data of the interval calculation means in ascending order of the maximum / minimum difference absolute value in a preset number of times. A flow rate presence / absence determining unit that calculates an average from the N average flow rates to determine the presence / absence of a gas flow rate, and the flow rate presence / absence determination unit includes an average flow rate within a section average flow rate within an average determination flow rate Is within the average judgment flow rate, it is judged that there is no flow rate, and when the calculated average flow rate is other than the average judgment flow rate, it is judged that there is a flow rate.

  According to a second aspect of the present invention, N average flow rates are calculated as N average flow rates in N intervals after the maximum / minimum difference maximum value has appeared within a preset number of times of data of the interval calculation means. A flow rate presence / absence determination unit that determines the presence or absence of a gas flow rate, and the flow rate presence / absence determination unit determines that there is no flow rate when the section average flow rate is within the determination allowable range and the average flow rate is within the average determination flow rate, If the calculated average flow rate is other than the average determination flow rate, it is determined that there is a flow rate, and the reduction of the data holding area in claim 1 is realized.

(Embodiment 1)
A gas meter will be described as a gas cutoff device in the first embodiment of the present invention. FIG. 1 is a block diagram of a gas meter according to a first embodiment of the present invention.

  In FIG. 1, a gas meter 1 is provided in the middle of a gas supply pipe a, and one or more gas appliances (not shown) installed in customer premises are connected to the downstream side of the gas supply pipe a. Yes.

  In FIG. 1, the gas meter 1 includes an interruption means 2, a flow rate measurement means 3, a display 4, a seismometer 5, a calculation means 6, a section calculation means 8, a flow rate presence / absence determination means 9, and a control means 10. The A flow rate measuring means 3 is provided on the downstream side of the shut-off device 2.

  The flow rate measuring means 3 is connected in the path of the gas supply pipe a and, as will be described later, obtains a propagation time difference caused by the gas flow in the gas supply pipe a by using an ultrasonic signal, and detects an instantaneous gas flow rate. Is.

  The calculation means 6 calculates the gas flow rate (flow rate value) by integrating the instantaneous flow rates based on the instantaneous flow rates detected by the flow rate measurement means 3. The flow rate measurement means 3 and the calculation means 6 realize the function of the flow rate measurement unit.

  The interval calculation means 8 accumulates the flow rate value calculated by the calculation means 6 for a predetermined time to calculate the interval average flow rate.

  The flow rate presence / absence determination means 9 holds N pieces in ascending order from the maximum flow rate, the minimum flow rate, and the average flow rate Qt of the section average flow rate by the section calculation means 8 every predetermined time, and whether or not there is a flow rate for determining inner pipe leakage Judgment processing is performed.

  In addition to controlling the operation of each part in the gas meter 1, the control means 10 performs a flow rate determination result by the flow rate determination means 9, a warning due to the inner pipe leakage confirmation, a safety process such as gas shutoff, and the like.

  Here, the control means 10, the calculation means 6, the section calculation means 8, and the flow rate presence / absence determination means 9 are constituted by a processor and an operation program constituting a microcomputer (microcomputer) and the like, and the processor executes a predetermined operation program. Each function is realized by performing corresponding processing.

  The flow rate measurement means 3 in the first embodiment uses ultrasonic measurement means. However, as a measurement method, other flow measurement methods may be used in a short cycle such as a fluidic method. Other methods capable of continuous measurement may be used.

  The display 4 is composed of an LED, a liquid crystal display, and the like, and displays a gas flow rate, an operating state of the gas appliance, a warning, and the like. The seismoscope 5 detects vibration such as an earthquake and outputs a detection signal to the control means 10. The shut-off means 2 is connected to the path of the gas supply pipe a, and shuts off the gas supply by closing the gas supply pipe a based on an instruction from the control means 10. The pressure sensor 12 is connected to the gas meter 1 and measures the pressure in the path of the gas supply pipe a. The pressure determination unit 13 is a unit that periodically determines the pressure value measured by the pressure sensor 12.

  The operations of the flow rate measuring means 3 and the calculating means 6 will be described in detail below. FIG. 2 is a schematic configuration diagram of the flow rate measuring means 3.

  The flow rate measuring means 3 has a measurement flow path 30 having a rectangular cross section communicating with the gas supply pipe a, and a pair of ultrasonic waves is provided on the upstream side and the downstream side of the flow path walls facing each other. 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. Ultrasonic waves are propagated in the opposite direction.

  At this time, the distance between the ultrasonic transmitters / receivers 31 and 32, that is, the measurement distance is L, the angle of the ultrasonic propagation path with respect to the gas flow is φ, and the ultrasonic wave from the ultrasonic transmitter / receiver 31 to the ultrasonic transmitter / receiver 32 downstream thereof. Assuming that the sound wave propagation time is t1, the ultrasonic wave propagation time from the ultrasonic wave transmitter / receiver 32 to the ultrasonic wave transmitter / receiver 31 upstream thereof is t2, and the sound velocity is C, the flow velocity V is obtained by the following equation.

V = L / 2 cos ((1/1/1)-(1 / t2))
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. The time interval for measuring the instantaneous flow rate can be set within a range where ultrasonic waves can be transmitted and received.

  In general, since the start time and the time during which the gas flow rate changes due to control differ depending on the gas appliance to be used, reducing the measurement time interval is advantageous in order to instantaneously discriminate the appliance. However, as the measurement time interval is shortened, battery consumption increases in a gas meter or the like driven by the battery. Further, when the measurement time interval is a two-digit order interval equivalent to the membrane type used in the conventional gas meter, it becomes difficult to judge by looking at the difference in flow rate change.

  In this embodiment, when the gas appliance is not used, the periodic instantaneous flow rate is measured at intervals of 2 seconds and the difference value is taken to determine the activation of the gas appliance. Note that the measurement time interval can be further shortened. For example, after starting the gas appliance, control such as shortening the measurement time interval may be performed in order to increase measurement accuracy.

  Next, the operation of the flow rate presence / absence determining means 9 will be described in detail below. FIG. 3 is a characteristic diagram showing a change in gas flow rate during pulsation, and FIG. 4 is a diagram showing an allowable determination range of the section average flow rate Qt.

  FIG. 3 shows an instantaneous flow rate value of the gas measured by the flow rate measuring means 3. If the instantaneous flow rate is stable near zero when the gas appliance is not in use, it is easy to determine that there is no flow rate, and if the instantaneous flow rate is stable at a minute flow rate, it is also easy to detect inner pipe leakage. .

  However, if there is a flow rate due to the effects of breathing, etc., it cannot be determined that there is no flow rate. There was a problem.

  When gas flow is generated due to breathing action, the pressure fluctuation is large, so when making a judgment of no flow rate, if the pressure value in the gas pipe is within the predetermined range, the section average for the predetermined time The maximum value (maximum flow rate) Qtmax, the minimum value (minimum flow rate) Qtmin and the average value (average flow rate) of the flow rate Qt are obtained and used for the determination of the degree of stability.

  FIG. 4 shows threshold values for determining the degree of stability of the section average flow rate Qt. Assuming that the average determination flow rate is Qh (L / h), a range from −Qh to Qh is a determination threshold (determination allowable range). If the section average flow rate Qt is outside the range of -Qh to Qh, it is determined that there is a flow rate. FIG. 4 shows the first determination count of the section average flow rate Qt that falls within the range of −Qh to Qh, which is the determination threshold. If the average flow rate of the section average flow rate Qt for the first determination count is out of the allowable determination range, it is determined that there is a flow rate.

  FIG. 5 is a flowchart showing an operation procedure of the flow rate presence / absence determination 9 in the present embodiment. The flow rate presence / absence determining means 9 stores a program for executing the control flow from step S1 to step S15 shown in FIG.

  In step S1, the section average flow rate Qt from the section calculation means 8, the maximum value Qtmax and the minimum value Qtmin in the section are updated.

  In step S2, it is determined whether or not the difference between the maximum flow rate Qtmax and the minimum flow rate Qtmin from the section calculation means 8 is less than the allowable range width, and if it is less than the allowable range width, the process proceeds to step S3. In step S3, it is determined whether or not the section average flow rate Qt from the section calculation means 8 is within the determination allowable range, and if it is within the determination allowable range, the process proceeds to step S7.

  In step S3, if the section average flow rate Qt is not within the determination range tolerance, it is determined that there is a flow rate, the process proceeds to step S4, the inner pipe leakage determination timer is increased, and in step S5, the inner pipe leakage determination timer is set. It is determined whether or not the predetermined value has been reached. When the predetermined value is reached, the process proceeds to step S6, where it is determined that the inner pipe leaks.

  In step S3, if the section average flow rate Qt from the section calculation means 8 is within the determination allowable range, in step S7, the absolute value of the difference between the maximum flow rate Qtmax and the minimum flow rate Qtmin (maximum minimum in a preset period). The section average flow value Qt is arranged in ascending order of the absolute value of the difference), the section average flow value Qt is held together with the absolute values of the maximum and minimum differences, and it is determined whether or not the number of holding exceeds N. Proceed to In S8, the value held in the (N + 1) th (the largest value among the absolute values of the maximum and minimum differences held and the section average flow rate Qt corresponding to the absolute value of the maximum and minimum differences) is deleted. To do.

  In step S9, the continuous number counter is increased. In step S10, it is determined whether or not the continuous number counter has reached the continuous determination number. If it has been reached, the continuous number counter is cleared in step S11, and the N sections held in step S7 in step S12. The average flow rate of the average flow rate Qt is calculated (if it is not N, the average of the number of section average flow rates Qt held at that time may be calculated, or the average flow rate of the section average flow rate Qt may be zero. In step S13, the held absolute value of the N maximum and minimum differences and the N section average flow rates Qt are cleared.

  In step S14, it is determined whether or not the absolute value of the average flow rate of the N section average flow rates Qt calculated in step S12 is within the average determination flow rate. If it is within the average determination flow rate, the flow proceeds to step S15 as no flow rate. In step S15, the inner pipe leakage determination timer is cleared. In step S14, if the absolute value of the average flow rate of the section average flow rate Qt is not within the average determination flow rate, the process proceeds to step S4.

  As described above, the flow rate presence / absence determination means 9 accumulates the section average flow rate when the section average flow rate Qt is within the determination allowable range, calculates the average flow rate, and when the calculated average flow rate is within the average determination flow rate. It is determined that there is no flow rate, and when the calculated average flow rate is other than the average determination flow rate, it is determined that there is a flow rate.

  As described above, in the present embodiment, by averaging the N section average flow rates Qt in ascending order of the absolute values of the maximum and minimum differences, the average is obtained even when the breathing motion is occurring. Since the flow rate is determined based on the near N section average flow rates Qt, it is possible to stably determine that there is no flow rate, and to prevent an erroneous warning of inner pipe leakage.

(Embodiment 2)
A gas shut-off device according to the second embodiment of the present invention will be described using a gas meter. FIG. 6 is a flowchart showing an operation procedure for determining whether or not there is a flow rate in the present embodiment.

  In the flowchart shown in FIG. 6, in step S21, the section average flow rate Qt from the section calculating means 8, the maximum value Qtmax and the minimum value Qtmin in the section are updated.

In step S22, it is determined whether or not the difference between the maximum flow rate Qtmax and the minimum flow rate Qtmin from the section calculation means 8 is less than the allowable range width, and if it is less than the allowable range width, the process proceeds to step S23. In step S23, it is determined whether or not the section average flow rate Qt from the section calculation means 8 is within the determination allowable range, and if it is within the determination allowable range, the process proceeds to step S27.
If the section average flow rate Qt is not within the determination range in step S23, it is determined that there is a flow rate, the process proceeds to step S24, the inner pipe leakage determination timer is increased, and in step S25, the leakage determination timer is set to a predetermined value. When the predetermined value is reached, the process proceeds to step S26 to determine the inner pipe leakage.

  In step S27, if the absolute value of the difference between the maximum flow rate Qtmax and the minimum flow rate Qtmin (Qt maximum / minimum difference) obtained by the section average flow rate is equal to or less than the Qt maximum / minimum difference maximum value (initial value: allowable maximum value), step S28 is performed. If not, the process proceeds to step S37.

  In step S28, the absolute value of the difference (Qt maximum / minimum difference) between the maximum flow rate Qtmax and the minimum flow rate Qtmin obtained by the section average flow rate is compared with the Qt maximum / minimum difference / maximum difference candidate value, and the absolute value of the Qt maximum / minimum difference is determined. If it is larger than the Qt maximum / minimum difference maximum value candidate value, the Qt maximum / minimum difference / maximum value candidate value is updated in step S29, and the maximum value candidate counter and the total flow rate candidate are cleared.

  In step S30, Qt is added to the total flow rate candidate. If the maximum value or the counter is less than N in step S31, the maximum value counter is increased in step S32, and Qt is added to the total flow rate in step S33. Proceed to S37.

  If the absolute value of the Qt maximum / minimum difference is less than or equal to the Qt maximum / minimum difference / maximum candidate value in step S28, the maximum value candidate counter is counted in step S34, and if the maximum value candidate counter is not N or more in step S35, step S30 is performed. Go ahead. If there are N or more maximum value candidate counters in step S35, the process proceeds to step S36, the Qt maximum / minimum difference maximum value is updated with the Qt maximum / minimum difference maximum value candidate value, the maximum value candidate counter is set to N, and the total flow rate value Is updated to the value of the total flow rate candidate, and the Qt maximum / minimum difference maximum value candidate value is cleared.

  In step S37, the continuous number counter is increased.

  In step S38, it is determined whether or not the continuous number counter has reached the continuous determination number. When the continuous number counter reaches the continuous determination number, the continuous number counter is cleared in step S39, and the section average flow rate Qt is determined in step S40. The average flow rate of the maximum N section average flow rates Qt is calculated from the total flow rate obtained by adding (if the number is not N, the average of the number of section average flow rates Qt held at that time may be calculated, In step S41, the Qt maximum / minimum difference maximum value is set as an allowable range value, the Qt maximum / minimum difference maximum value candidate value, the maximum value candidate counter, the maximum value counter, and the total flow rate are set. To clear.

  In step S42, it is determined whether or not the absolute value of the average flow rate calculated in step S40 is within the average determination flow rate. If it is within the average determination flow rate, the flow rate is determined to be absent, and in step S43, the inner pipe leakage determination timer is cleared.

  FIG. 7 shows a table for determining the total flow rate. When the predetermined number of times starts, the total flow rate is obtained by adding from the N segment average flow rates. When the N segment average flow rates are added, the N average flow rate calculation target is obtained as the total flow rate. Further, the Qt maximum / minimum difference maximum value candidate value is set to the initial value 0, and the maximum / minimum difference value when the predetermined number of times starts is set as the maximum / minimum difference / maximum candidate. For example, if the maximum / minimum difference equal to or greater than the maximum / minimum difference / maximum value candidate value of Qt (11), which is the 11th time, does not appear, the maximum value candidate counter continues to increase. When N maximum value candidate counters are added, the value of the total flow rate is replaced and N average flow rates are calculated.

  FIG. 8 shows a diagram illustrating the operation for maintaining the total flow rate. The value of the total flow rate candidate added by the determination of the Qt maximum / minimum difference maximum value candidate value becomes a candidate every time it is updated, because the one with the maximum / minimum difference smaller than the current value becomes a candidate. The section average flow rate can be the total flow rate.

  As described above, in the present embodiment, it is possible to determine that there is no flow rate stably even when breathing motion is occurring, based on the section average value considering the value of the maximum / minimum difference. Since the warning can be prevented and it is not necessary to hold the maximum / minimum value difference of the section average flow rate for N and the section average flow rate Qt, the data holding area of the first embodiment can be reduced. .

  As described above, since the gas shutoff device according to the present invention can determine the leak of the inner pipe even in an environment where pulsation or breathing motion occurs, the gas shutoff device according to the present invention is also applicable to a method for detecting leakage of water or gas. Applicable.

DESCRIPTION OF SYMBOLS 1 Gas meter 2 Blocking means 3 Flow rate measuring means 4 Display (display part)
DESCRIPTION OF SYMBOLS 5 Seismic device 6 Calculation means 8 Section calculation means 9 Flow existence determination means 10 Control means 12 Pressure sensor 13 Pressure determination means

Claims (2)

A flow rate measuring means connected to the gas supply pipe for measuring the gas flow rate at regular time intervals, a calculation means for obtaining a flow rate value by the flow rate measurement means, and a section for accumulating the flow rate value calculated by the calculation means for a predetermined time An interval calculation means for calculating an average flow rate and obtaining a maximum flow rate and a minimum flow rate therebetween,
A flow rate presence / absence determining means for determining the presence or absence of a gas flow rate capable of holding N pieces of data of the interval calculation means in ascending order of absolute values of the maximum and minimum differences in a preset number of times; With
The flow rate presence / absence determination means determines that there is no flow rate when the section average flow rate is within the allowable determination range and the N average flow rates obtained by the flow rate presence / absence determination means are within the average determination flow rate, and the calculated average flow rate is A gas shut-off device that determines that there is a flow rate other than the average determination flow rate. The maximum value of the absolute value of the maximum / minimum difference can be updated during the preset number of times of the data of the section calculation means, and N total flow rates below the maximum value of the absolute value of the maximum / minimum difference are calculated and set in advance. The gas shut-off device according to claim 1, further comprising a flow rate presence / absence determining means for determining the presence or absence of a gas flow rate capable of calculating the N average flow rates at the number of times.