JP2008096109A - Electronic gas meter and flow rate variation determination method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic gas meter capable of avoiding the occurrence of gas supply cutoff though a gas consumption apparatus functions normally, even when the speed of the flow rate variation of gas of the gas consumption apparatus is extremely low. <P>SOLUTION: The electronic gas meter 10 stores instantaneous flow rate Qi, and the maximum value and minimum value of the instantaneous flow rate. The latest instantaneous flow rate Qi is compared in magnitude with the maximum value and minimum value. When the flow rate exceeds the maximum value or minimum value, the maximum value or minimum value is updated to the latest instantaneous flow rate Qi. The difference ΔQ between the stored maximum value and minimum value is calculated. When it exceeds a predetermined flow rate variation threshold dQ, it is determined as presence of the flow rate variation, and the stored maximum value and minimum value are updated to the latest instantaneous flow rate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic gas meter and a flow rate change determination method, and in particular, when a state in which a change in gas flow rate does not exceed a predetermined flow rate change threshold value continues for a certain period of time, the gas supply is cut off from the viewpoint of ensuring safety. The present invention relates to an electronic gas meter having at least a function to perform the above and a flow rate change determination method using the electronic gas meter.

  An electronic gas meter with a safety function that shuts off the gas flow path when it is determined that an abnormality such as gas leakage has occurred when the flow rate of the gas flowing through the gas flow path is substantially constant for a predetermined time. It has been known. More specifically, this type of electronic gas meter is provided with a correspondence table showing correspondence between gas consumption classification (flow rate) and safety duration (interruption time), and the time limit for safe continuous use The safety is ensured by setting it long in the region where the consumption is small and short in the region where the consumption is large. A gas flow rate that exceeds a predetermined flow rate change threshold value (for example, 51.82 L / h) within a time limit for safe continuous use set in accordance with the current gas flow rate (gas consumption amount). When a change occurs, the control means determines that the user has consciously changed the operating conditions of the gas consuming device, resets the timer, and restarts the safety duration (interruption time) from 0 The gas supply is prevented from being cut off even though the gas consuming device is functioning normally.

  When the target gas consuming device is a gas stove, a gas water heater, or a bathtub, a sudden and large change in gas flow occurs during use of the device due to changes in combustion conditions intentionally made by the user. Therefore, a gas flow rate change that exceeds the flow rate change threshold value is likely to occur within a certain amount of time. Therefore, the safety mechanism described above functions properly, and when the gas consuming device is used properly for a long time, the gas meter side has a safety duration ( There is no inconvenience that the gas flow path is shut off when it is determined that the shut-off time has been exceeded.

  By the way, in recent years, in gas consuming equipment where the rate of change in gas consumption flow rate is slow, such as gas fan heaters and distributed power plants represented by fuel cell systems, the actual flow rate has changed, Since the flow rate change speed (flow rate change amount per unit time) is moderate, if a conventional mechanical or electronic gas meter with a supply abnormality detection function is used as it is, a predetermined flow rate change threshold will be exceeded. A gas leak occurs when a predetermined time limit for continued use of safety has elapsed even though the gas consuming equipment is functioning normally without recognizing that the gas flow rate has changed. It is possible that it is determined that an abnormality such as the above has occurred and the gas flow path is blocked. For example, a gas fan heater is a device that is often used for a long time, and although the safety is ensured and it is not necessary to shut it off, the gas meter shuts off after a certain time after using the gas fan heater as described above. There is a problem that the convenience of the person using the gas fan heater is significantly impaired.

  In addition, when a power generation system is installed in a power demand area such as a home or a store by adopting a distributed power plant method, the power generation system can be changed in order to operate the power generation system efficiently. In some cases, the vehicle is operated while being appropriately controlled according to the conditions. In particular, when the power generation system is a fuel cell system, when the load followability of the fuel cell system is not good or when the load itself is moderate, operation may be performed with a slow change in consumption flow rate. . However, when the power generation system installed in the power demand area is operated for a long time in this way, the supply abnormality detection function configured in the conventional gas meter, for example, the safety duration over detection function, has a slow gas consumption flow rate. It is possible that the change cannot be correctly detected as a change in flow rate, and the continuous gas consumption in the power generation system may be erroneously detected as an abnormal gas usage state. When the safety duration over detection function works, an alarm is generated each time, or the shutoff valve inside the gas meter is driven to automatically shut off the gas supply. This causes an increase in operation cost due to an inappropriate alarm response, and a deterioration in efficiency and function of the fuel cell system due to improper shutoff while the fuel cell is being driven. This is a problem to be improved in order to improve the safety performance.

  In order to eliminate the inconvenience, Patent Document 1 or Patent Document 2 states that the gas combustion amount continuously varies over a preset time on the gas consuming device side disposed downstream of the electronic gas meter. A technique is disclosed that includes gas combustion amount forced change means for forcibly changing the gas combustion amount in the gas combustion section when it is detected that the change has not been exceeded. By providing this means in the gas consuming device, the control means of the electronic gas meter allows the gas exceeding the predetermined flow rate change threshold within a predetermined time limit corresponding to the current gas flow rate (gas consumption amount). Therefore, it is possible to prevent the gas supply from being cut off even though the gas consuming device is functioning normally.

  On the other hand, in an electronic gas meter, for the purpose of detecting the total flow rate over and the individual maximum flow rate over, there is a technique for determining whether or not there is an instantaneous steep gas flow rate change flowing in the meter. 4 etc. There, the flow rate measured by the flow rate measurement unit is stored at regular time intervals, and the latest n (n is an integer) number average is calculated therefrom, and the latest n times average flow rate and the immediately preceding ( n-1 times), or the difference between the latest n-time average flow rate and the n-th previous n-time average flow rate to a predetermined flow rate change threshold, and based on the comparison result, The presence or absence of a change in gas flow rate is determined.

Japanese Patent No. 3532757 JP 2004-258767 A JP-A-8-327415 JP 2005-241405 A

  By adopting the technology described in Patent Document 1 or Patent Document 2, in a gas consuming device such as a gas fan heater or a fuel cell where the rate of change of the gas consumption flow rate is slow, the device functions normally. Nevertheless, it is possible to prevent the gas supply from being interrupted. However, all of the techniques described in Patent Document 1 and Patent Document 2 are provided with a means for forcibly changing the amount of gas combustion on the gas consuming device side, and an equipment load that is not originally required on the gas consuming device side. Can be said to impose. Further, when a forced flow rate change of a specific pattern is caused in the gas consuming device by the gas combustion amount forced change means, the conventional electronic gas meter cannot recognize the specific pattern.

  The present invention has been made in view of the above circumstances, and does not impose a special equipment burden on the gas consuming equipment side, and the gas supply shut-off despite the above-described gas consuming equipment functioning normally. An object of the present invention is to provide an electronic gas meter capable of avoiding occurrence of the above. Another object of the present invention is to provide an electronic gas meter capable of recognizing a specific pattern when a means for causing a forced change in the amount of gas combustion in a specific pattern is provided on the gas consuming device side.

  An electronic gas meter according to the present invention includes an instantaneous flow rate measuring unit that measures an instantaneous flow rate of a gas flowing through a gas flow path, a first storage unit that stores an instantaneous flow rate measured by the instantaneous flow rate measuring unit, and a specific instantaneous flow rate. Second storage means for storing the value as a max value and a min value, and reading the instantaneous flow rate stored in the first and second storage means to compare the magnitude of the latest instantaneous flow rate with the max value and the min value If the latest instantaneous flow rate is larger than the max value, the max value of the second storage means is updated with the latest instantaneous flow rate. If the latest instantaneous flow rate is smaller than the min value, the second storage means is updated. The first calculation means for updating the min value with the latest instantaneous flow rate, the difference between the max value and the min value stored in the second storage means, and the difference value is compared with a predetermined flow rate change threshold value. 1st ratio to Stored in the second storage means when the flow rate change determination means determines that there is a flow rate change. And a second calculating means for updating the maximum value and the min value to the latest instantaneous flow rate.

  In the electronic gas meter according to the present invention, the max value and the min value of the instantaneous flow rate measured over time are stored, and compared with the max value and the min value stored in the latest instantaneous flow rate. If the latest instantaneous flow rate is larger than the stored max value, the max value is updated with the latest instantaneous flow rate. If the latest instantaneous flow rate is smaller than the stored min value, the min value is updated with the latest instantaneous flow rate. Therefore, the maximum value and the min value of the gas consumption amount are always stored in the second storage means without being affected by the length of the operation time of the gas consuming device. That is, even in the case of a gas consuming device in which the gas flow rate changes slowly and slightly over a long time, the max value and the min value of the gas consumption during that time are stored in the second storage means.

  The electronic gas meter calculates the difference between the max value and the min value stored in the second storage means, and compares the difference value with a predetermined flow rate change threshold value (for example, 51.82 L / h). When the difference value exceeds the predetermined flow rate change threshold, the flow rate change determination means determines that “there is a change in flow rate”, and the max value and the min value stored in the second storage means are updated to the latest value. Update to instantaneous flow rate. For this reason, for example, the speed of change of the gas consumption flow rate per unit time during normal operation is slow due to the operating characteristics of gas consuming equipment such as fuel cells, and the flow rate change between adjacent measurement points, that is, the latest Even if the flow rate change that exceeds the predetermined flow rate change threshold does not occur between the flow rate at the measurement point and the flow rate at the immediately preceding measurement point, the flow rate change determination means exceeds the flow rate change threshold value. Therefore, it can be reliably detected that the flow rate has changed, and it can be determined that the flow rate has changed. A flow rate change exceeding the flow rate change threshold may occur only once, and it may be determined that “there is a flow rate change”. In order to avoid the influence of a temporary irregular flow rate change, the flow rate change When the flow rate change exceeding the threshold value occurs continuously a plurality of times (for example, 3 times), it may be determined that “there is a flow rate change” for the first time.

  When the flow rate change determining means determines that there is a change in flow rate, the gas consuming device functions normally by taking measures such as not shutting off the gas supply even after the initially set safety duration has elapsed. However, it is possible to avoid the inconvenience that the gas supply is cut off despite the fact that the gas is supplied.

  The electronic gas meter according to the present invention may further comprise means for determining whether a difference value exceeding the predetermined flow rate change threshold value is a difference value generated in an increasing direction or a difference value generated in a decreasing direction.

  The electronic gas meter of this form is for forcibly causing a specific change in gas combustion amount in a specific pattern when no change in gas consumption exceeding a threshold value within a predetermined time occurs on the gas consuming device side. This is particularly effective when the gas combustion amount forced change means is provided on the gas consuming equipment side. That is, the electronic gas meter can determine the specific pattern, that is, whether the forced change of the gas combustion amount is caused in the increasing direction or whether the forced change of the gas combustion amount is caused in the decreasing direction. When a plurality of gas consuming devices are connected downstream of the electronic gas meter, when a gas combustion amount forced change means for causing a forced change in the gas combustion amount in the increasing direction or the decreasing direction is provided in only one of them, The electronic gas meter can selectively recognize that a flow rate change exceeding the flow rate change threshold has occurred in the gas consuming device.

  The electronic gas meter further includes second comparison means for calculating a temporal change amount of the difference value and comparing the temporal change amount with a temporal change amount threshold value of a predetermined flow rate, The flow rate change determination means may determine the presence or absence of a change in the gas flow rate based on a comparison result by the first comparison means and the second comparison means.

  When multiple gas consuming devices are connected downstream of an electronic gas meter, each gas consuming device usually has a unique gas consumption pattern. Different in gas consuming equipment. Therefore, even in the electronic gas meter of the above aspect, by providing the second comparison means, a gas consuming device in which a flow rate change exceeding a flow rate change threshold value is selectively selected from a plurality of gas consuming devices. Can be recognized.

  In a preferred aspect of the electronic gas meter according to the present invention, the electronic gas meter further includes safety duration setting means for setting a safety duration corresponding to the gas flow rate, and the safety duration setting means includes the flow rate change determination means. When it is determined that the flow rate has changed, the safety duration corresponding to the latest instantaneous flow rate is reset and the timer is reset.

  When the above electronic gas meter determines that the flow rate has changed, the safety duration corresponding to the latest instantaneous flow rate at that time is reset, and a new time measurement starts from the point of determination. It is possible to ensure a safe duration according to the actual driving situation. When the latest instantaneous flow rate is greater than the stored max value, the safe duration corresponding to the latest instantaneous flow rate is the safe duration corresponding to the max value updated to that value. Yes, when the latest instantaneous flow rate is smaller than the stored min value, it is the safety duration corresponding to the min value updated to that value. Further, as the safety duration corresponding to the instantaneous flow rate, the safety duration corresponding to the flow rate difference between the max value and the min value when the flow rate change determination unit determines that there is a flow rate change is reset and the timer is reset. You may do it.

  In a preferred aspect of the electronic gas meter according to the present invention, the gas instantaneous flow rate measuring means includes an n-time average flow rate calculation unit for calculating an average of n (n is an integer) times at the time of n consecutive measurements, and each measurement point. Is the n-time average flow rate calculated by the n-time average flow rate calculation unit. As described above, by adopting the n-time average flow rate as the flow rate at each measurement point, it is possible to eliminate the influence of a temporary rapid flow rate change. Note that the integrated flow rate can be used n times instead of the average flow rate n times.

  The present invention also stores an instantaneous flow rate measuring step for measuring an instantaneous flow rate of gas flowing through a gas flow path, and an instantaneous flow rate measured in the instantaneous flow rate measuring step as a flow rate change determination method using the electronic gas meter. A first storage step; a second storage step for storing the specific instantaneous flow rate as a max value and a min value; and reading the instantaneous flow rate stored in the first and second storage steps to obtain the latest instantaneous flow rate and the max value. If the latest instantaneous flow rate is larger than the max value, the max value in the second storage step is updated with the latest instantaneous flow rate, and the latest instantaneous flow rate is compared with the min value. If it is smaller, the first calculation step for updating the min value in the second storage step with the latest instantaneous flow rate, and the difference between the max value and the min value stored in the second storage step A comparison step for calculating the difference value and a predetermined flow rate change threshold value, a flow rate change determination step for determining the presence or absence of a change in the flow rate of the gas based on the comparison result of the comparison step, and the flow rate change An electronic gas meter characterized in that it includes at least a second calculation step for updating the maximum value and the min value stored in the second storage step to the latest instantaneous flow rate when the determination step determines that there is a change in the flow rate. A flow rate change determination method is also disclosed.

  By using the electronic gas meter according to the present invention, the gas supply is interrupted even though the gas consuming device is functioning normally without giving a special equipment burden to the gas consuming device. Can surely be avoided.

  In a preferred aspect of the electronic gas meter according to the present invention, when a means for causing a forced change in the amount of gas combustion in a specific pattern is provided on the gas consuming device side, a flow rate that exceeds a flow rate change threshold value among a plurality of gas consuming devices. It is possible to selectively recognize a specific gas consuming device in which a change has occurred and reliably avoid a situation in which the gas supply is interrupted even though the gas consuming device functions normally. .

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an electronic gas meter according to the present invention, FIG. 2 is a block diagram showing its control means, and FIGS. 3 and 4 conceptually explain the judgment principle of the flow rate judgment method of the electronic gas meter according to the present invention. It is a figure for doing. 5 to 10 are flow charts for explaining several modes of the processing procedure of the electronic gas meter according to the present invention.

  As shown in the block diagram of FIG. 1, the electronic gas meter 10 includes a flow rate sensor 11 used for measuring the flow rate of the gas G flowing in the pipe H inside the metal housing 1, and the gas G A pressure sensor 12 for detecting the pressure of the battery, a clock 13 used for measuring time, a storage means (memory) 14 for storing various information, a lithium battery 15 for supplying power to the entire meter, and the entire meter And a shutoff valve 17 for switching the supply state of the gas G to the downstream side of the gas meter 10. A display panel 18 for displaying various information is attached to the casing 1 of the gas meter 10.

  The flow velocity sensor 11 is an ultrasonic flow velocity sensor (refer to Japanese Patent Application Laid-Open No. 2004-212288, for example) that measures the flow velocity of the gas G using, for example, a conventionally known ultrasonic wave. Is output as a measurement signal S1. The pressure sensor 12 is, for example, a piezoelectric film sensor that generates a voltage corresponding to a distortion generated according to a conventionally known pressure. The pressure sensor 12 detects the pressure of the gas G flowing through the pipe H and applies pressure to the control unit 16. The signal S2 is output. The clock 13 is configured to include a crystal oscillator, and a clock signal S3 is output to the control means 16 using the operating characteristics of the crystal oscillator.

  The memory 14 stores various data required by the control means 16, and is composed of, for example, a RAM. Specifically, the first storage unit 14a includes first and second storage units 14a and 14b. The first storage unit 14a includes an instantaneous flow rate Qi of the gas G calculated by the control unit 16 and a plurality of measurement units at certain time intervals. The n times average flow rate Qni at the point is stored. The 2nd memory | storage means 14b memorize | stores the specific instantaneous flow rate mentioned later as a max value and a min value. Further, the memory 14 stores a flow rate change threshold value dQ, a flow rate change threshold value DQ, a gas flow rate classification (flow rate) U, and a safety duration (cutoff time) T, which are basic values for determining that there is a flow rate change. Is also stored.

  The control means 16 is constituted by, for example, a CPU or the like, and “instantaneous flow rate measurement means”, “(first and second) calculation means”, “(first and second) comparison means” according to the present invention. ”,“ Flow rate change determining means ”,“ safety duration setting means ”and the like. Each will be described below with reference to FIG.

(1) Flow rate calculation function (instantaneous flow rate measuring means 21)
The instantaneous flow rate measuring means 21 measures the time based on the clock signal S3 output from the clock 13, and the flow rate of the gas G at every predetermined measurement time interval s based on the measurement signal S1 output from the flow rate sensor 11. V is calculated, and the instantaneous flow rate Qi of the gas G is calculated by multiplying the flow velocity V of the gas G by the cross-sectional area A of the pipe H. Further, the n-time average flow rate calculation means 22 calculates the n-time average flow rate Qni from n consecutive times of the instantaneous flow rate Qi. The calculation result is sent to the memory 14.

(2) Calculation function (first calculation means 23a, second calculation means 23b)
The first calculation unit 23a reads the latest instantaneous flow rate Qi stored in the first storage unit 14a and the max value and the min value of the instantaneous flow rate Qi stored in the second storage unit 14b to obtain the latest Comparison between the instantaneous flow rate Qi and the max and min values is compared. If the latest instantaneous flow rate Qi is larger than the max value, the max value of the second storage means 14b is updated with the latest instantaneous flow rate Qi. If the latest instantaneous flow rate Qi is smaller than the min value, the second storage means is updated. The min value of 14b is updated with the latest instantaneous flow rate Qi.

  The second calculating unit 23b updates the max value and the min value stored in the second storage unit 14b to the latest instantaneous flow rate Qi when the flow rate change determining unit 25 described later determines that there is a flow rate change.

(3) Comparison function (first comparison means 24a, second comparison means 24b)
The first comparison unit 24a calculates a difference ΔQ (max−min) between the max value and the min value stored in the second storage unit, and compares the difference value ΔQ with a predetermined flow rate change threshold value dQ. To do.

  The second comparison means 24b calculates the temporal change amount ΔQ / Δt of the difference value ΔQ (max-min) and compares the temporal change amount with the temporal change amount threshold value DQ of a predetermined flow rate. To do. This second comparison function can be omitted.

(4) Flow rate change determination function (flow rate change determination means 25)
The presence or absence of a change in the gas flow rate is determined based on the comparison result by the comparison means 24. If the absolute value of the obtained difference value ΔQ is greater than or equal to a predetermined flow rate change threshold value dQ, it is determined that there is a flow rate change, and if smaller than the predetermined flow rate change threshold value dQ, Judge that there is no flow rate change. The determination result is sent to the safety duration setting means 26.

(5) Continuous use time setting function (safety duration setting means 26)
The safety duration Tq corresponding to the current gas flow rate Qi is taken from the correspondence table Ta between the gas flow rate classification (flow rate) U and the safety duration (cutoff time) T stored in the memory 14, and set as the safety duration Tq. . When the safety continuation time Tq elapses, a cutoff signal S4 is output to the cutoff valve 17. When the flow rate change determination means 25 determines that there is a change in flow rate, the safe duration Tp corresponding to the instantaneous flow rate Qi at the measurement point P at the time of determination is read from the correspondence table Ta and reset as a new continuous use time Tp. . At the same time, the timer is reset to 0, and a cutoff signal S4 is output to the cutoff valve 17 when a new continuous use time Tp has elapsed.

  The determination principle of the flow rate change determination method for an electronic gas meter according to the present invention will be conceptually described with reference to FIGS. Here, the continuous use time setting function described above is not used. 3 and 4, the vertical axis represents the flow rate, and the horizontal axis represents time. Now, it is assumed that instantaneous flow rate measurement at each measurement point is performed while the operation of the gas consuming equipment is continued, and the flow rate Q1 at the point P1 in FIG. 3A is stored in the second storage unit 14b as a min value. Further, it is assumed that a preset flow rate change threshold value for determining whether or not there is a flow rate change is dQ.

  Measurement points move over time. In this example, the flow rate change is in an increasing direction, and the flow rate Qn at each measurement point Pn is updated as a maximum value. In FIG. 3a, the flow rate Q2 at the measurement point P2 is a maximum value, and at this time, the difference value ΔQ (Q2−Q1) is smaller than dQ, and the above-described determination that there is a change in the flow rate is not established. Further, time elapses to FIG. 3b, and the difference value ΔQ (Q3−Q1) = dQ is obtained at the flow rate Q3 (Qmax) at the measurement point P3. At that time, the determination that the flow rate has changed is established, and the max value and the min value stored in the second storage unit 14b are updated by the flow rate Q3 (that is, the latest instantaneous flow rate) at the measurement point P3.

  Thus, when the change per unit time of the gas flow rate is very small, as shown in FIG. 3c, the flow rate change amount calculated from the difference value Qx of the flow rate values at the adjacent measurement points Pn and Pn + 1 is as follows. Even if it cannot be determined that there is a change in the flow rate appropriately because the change threshold value dQ is not exceeded, the predetermined flow rate change threshold value is exceeded by taking a long measurement time as shown in FIGS. 3a to 3b. In this case, as in the flow rate change determination method according to the present invention, by sequentially updating the max value and the min value as described above, it is possible to accurately determine that the flow rate has changed at an appropriate timing. become able to.

  FIG. 4 is another diagram conceptually illustrating the determination principle of the flow rate change determination method of the electronic gas meter according to the present invention. In this case, the flow rate slowly increases and then decreases. The flow rate Q1 at the point P1 in FIG. 4a is stored in the second storage means 14b as a min value. The measurement point moves with time and the max value is updated. At the flow rate Q2 at the measurement point P2 in FIG. 4A, the difference value ΔQ (Q2−Q1) is smaller than dQ, and the above-described determination that the flow rate has changed. Does not hold. Further, the update in the increasing direction proceeds, and as shown in FIG. 4b, the flow rate Q3 at the measurement point P3 becomes the maximum value, but the difference value ΔQ (Q3-Q1) is still smaller than dQ, and there is a change in flow rate. Does not hold.

  Thereafter, the flow rate changes in a decreasing direction, but the measured value is between the stored max value and min value, and neither is updated (FIG. 4c). 4d, the flow rate Q4 at the measurement point P4 is equal to the stored flow rate Q1 (min value), and at the measurement point P5 in FIG. 4e, the flow rate Q5 is lower than the flow rate Q1. Thereby, the min value is updated to Q5. However, at the stage of FIG. 4e, the difference value ΔQ (Q3-Q5) is still smaller than dQ, and the determination that there is a change in the flow rate is not established. Further, the flow rate changes in the decreasing direction, and the difference value ΔQ (Q3−Q6) is equal to dQ for the first time at the measurement point P6 in FIG. At that time, both the max value and the min value stored in the second storage unit 14b are updated to Q6.

  In the present invention, the instantaneous flow rate at each measurement point may be an instantaneous flow rate actually measured at the measurement point, and the above-described patent document using the n-time average flow rate calculation means 22 shown in FIG. 3 or Patent Document 4 may be used to calculate the average flow rate n times and use it. It may be a moving average value. As a result, it is possible to eliminate the influence of a temporary sudden change in flow rate.

  Next, the first aspect of the processing procedure of the electronic gas meter according to the present invention will be described more specifically with reference to the flowchart (0) of FIG. Here, the “continuous use time setting function” described above is used.

  In S010, i is an integer variable value, which is a measurement point at regular intervals s (for example, every 2 seconds). q is the instantaneous flow rate measurement value, and Q (i) is the instantaneous flow rate measurement value at the measurement point i. Tq is an initial value of the safety continuation time corresponding to the gas flow rate, and Tqx is a set value when Tq used in the determination of S090 is a variable (setting changeable).

  In S020, the instantaneous flow rate measuring unit 21 measures the instantaneous flow rate Q (i) at the measurement point i, the first storage unit 14a stores it, and the second storage unit 23b stores the maximum value and the min value of the instantaneous flow rate. Remember as. The clock 13 starts measuring time T.

  In S030, the instantaneous flow rate measuring means 21 measures the instantaneous flow rate Q (i + 1) at the next measurement point i + 1.

  In S040, the first calculation unit 23a reads the instantaneous flow rate Q (i + 1) at the measurement point i + 1 and the max value stored in the second storage unit 14b from the first storage unit 14a, and Q (i + 1)> Compare if max. In the case of yes, it transfers to S042, updates the max value of the 2nd memory | storage means 14b to Q (i + 1), and moves to S060. If no, in S050, it is compared whether min> Q (i + 1). In the case of yes, it transfers to S042, updates the min value of the 2nd memory | storage means 14b to Q (i + 1), and moves to S060.

  In S060, the first comparison unit 24a calculates a difference value ΔQ that is a maximum value−min value, and sets a predetermined flow rate change threshold value dQ (for example, 51.82 L / h) that is set in advance. Compare if it exceeds. If it exceeds, that is, yes, in S110, the flow rate change determination means 25 determines that “there is a change in flow rate”. The measurement point is updated (S120), and the process returns to S020.

  In the case of no in S050 and in the case of no in S060, that is, when neither the max value nor the min value is updated, and when the flow rate change amount (difference value ΔQ) does not exceed the threshold value dQ, S070 , The measurement point is updated, and the time T is updated in S080. In S090, it is determined whether or not the time T has exceeded a preset Tq (safety duration). If not (no), the process returns to S030, and when the time has elapsed (yes), in S100, When the safety confirmation time is exceeded, the control device 16 drives the shut-off valve 17 to the closed state.

  In the flowchart (0), the setting of Tq (safety duration) can be selectively changed. Which Tq is selected and set may be appropriately determined in consideration of the consumption characteristics of the gas consuming device. For example, although not shown in particular, when (a) Tq corresponding to the q (gas flow rate) of the max value is set, “Tq update (Tq corresponding to max)” is set as S043 after S042. (B) When Tq corresponding to q (gas flow rate) of the difference value ΔQ, which is max value−min value, is set, immediately before S060, “Tq update (to max-min)” is set as S059. (C) In the case of setting Tq corresponding to q (gas flow rate) of the min value, S053 is followed by “Tq update (corresponding to min)”. The step of “Tq is set)” is added.

  The flow chart (1) in FIG. 6 shows that “there is a change in flow rate” when the difference value ΔQ, which is the maximum value−min value, exceeds the predetermined flow rate change threshold value dQ continuously twice or more. The determination is established. According to this aspect, it becomes possible to ignore an irregular flow rate change that occurs temporarily, and the determination of “there is a flow rate change” is further ensured. Here, k is added as a variable in S010 to indicate the number of times that the difference value ΔQ exceeds the predetermined flow rate change threshold value dQ. kq is a preset number of times (for example, k = 3). In the flow diagram (1), steps having the same contents as those in the flow diagram (0) are denoted by the same reference numerals, and description thereof is omitted.

  If yes in S060, the variable k is updated (S062), and it is determined in S064 whether k has become kq. When yes, that is, when k has reached the preset value kp, k is cleared (S066), and the determination “There is a change in flow rate” is established (S110). In S060, if no, k is cleared (S068), and the process proceeds to S070. If no in S064, that is, if k does not reach the preset value kp, the process proceeds to S070. Subsequent steps proceed in the same manner as in the flowchart (0).

  The flow chart (2) in FIG. 7 adds not only the amount of the difference value ΔQ but also the change direction of the flow rate by adding information tmin and tmax indicating the temporal order to the flow rate values of max and min. It is possible to determine whether the direction is a direction or a decreasing direction. In this aspect, the gas combustion amount for forcibly causing the gas combustion amount forced change of a specific pattern when the gas consumption amount change exceeding the threshold value within a predetermined time does not occur on the gas consuming device side. This is particularly effective when the forced change means is provided on the gas consuming device side. Also in the flow diagram (2), steps having the same contents as the steps in the flow diagram (0) are denoted by the same reference numerals, and description thereof is omitted.

  In the flow diagram (2), the time tmax is stored together with the max value in S042. Also in S052, the time tmin is stored together with the min value. When the flow rate change amount (difference value ΔQ) exceeds the threshold value dQ in S060, that is, in the case of yes, Δt (tmax−tmin) is calculated in S061, and in S063, whether the value Δt is positive or negative. Is judged. If it is positive, that is, yes, a determination of “change in flow rate” is established (S112), and if it is negative, that is, if no, a determination that “the flow rate phenomenon is changed” is satisfied (S114). In either case, the process proceeds to the next S120, and the same procedure as in the flowchart (0) proceeds.

  The flow diagram (3) of FIG. 8 is further added to the mode of the flow diagram (2), by adding information on the time when the max and min were most recently updated to the flow values of max and min, respectively. In addition to the difference value between max and min, the temporal change amount of the change amount is calculated, and the change in flow rate is determined using the temporal change amount. Similarly to the flow diagram (2) in FIG. 7, this mode is also forcing a specific pattern of gas combustion amount when a change in gas consumption exceeding a threshold value within a predetermined time does not occur on the gas consuming device side. This is particularly effective when a gas combustion amount forced change means for forcibly causing a change is provided on the gas consuming device side. In the flow diagram (3), steps having the same contents as the steps in the flow diagram (2) are denoted by the same reference numerals, and description thereof is omitted.

  Also in the flow chart (3), the time tmax is stored together with the max value in S042. Also in S052, the time tmin is stored together with the min value. If the flow rate change amount (difference value ΔQ) exceeds the threshold value dQ in S060, that is, if yes, the second comparison unit 24b calculates Δt (| tmax−tmin |) together with ΔQ in S065. In S067, the temporal change amount (ΔQ / ΔT) of the difference value is compared with the temporal change amount threshold value DQ of a predetermined flow rate. If ΔQ / ΔT> DQ (yes), the determination of “there is a change in flow rate” is established in S110, and if ΔQ / ΔT <DQ (no), the process proceeds to S070. In either case, the same procedure as in the flowchart (2) proceeds thereafter.

  Although not shown, the determination in S067 may be DQ1 <ΔQ / ΔT <DQ2. Here, DQ1 and DQ2 are the upper and lower values and the lower limit value of the temporal change amount threshold value DQ of a predetermined flow rate, and only when there is ΔQ / ΔT between them, the determination of “flow rate change” is made. Like that. By setting in this way, the device that causes a specific flow rate change is selected more accurately and the timer is cleared more accurately (i.e., valve shutoff occurs even though the device is operating normally). Can be prevented).

  Take the difference between the time when the instantaneous flow rate entered the specific range (Q1 ± A) (for example, max value) and the specific range (Q2 ± A) (for example, min value), and use that as a criterion for determining the change in flow rate You can also. By adopting this mode, it is possible to more accurately select only devices that cause a specific flow rate change and clear the timer. The flowchart (3-1) in FIG. 9 introduces the idea in the flowchart 3 shown in FIG. In the flow diagram (3-1), steps having the same contents as the steps in the flow diagram (3) are denoted by the same reference numerals and description thereof is omitted.

  In the flow diagram (3-1), it is determined in S040 whether Q (i + 1) is within a specific range (Q1 ± A). In the case of yes, it progresses to S042. If no, it is determined in S050 whether Q (i + 1) is within a specific range (Q2 ± A). If yes, the process proceeds to S052, and if no, the process proceeds to S070. In the flow chart (3-1) of FIG. 9, the second comparison unit 24b is shown to make the determination of DQ1 <ΔQ / ΔT <DQ2 in S067, but simply determines that ΔQ / ΔT> DQ. It may be.

  Combining the flow diagram (2) and the flow diagram (3), a specific slope amount of a specific sign (increase direction or decrease direction) instead of an absolute value (absolute value of slope) of the temporal change amount of the difference value. It is also possible to capture only the flow rate change and select only the gas consuming device that makes such a change to clear the timer. This is shown in the flowchart (3-2) in FIG. In the flow diagram (3-2), S065, S067, and S110 in the flow diagram (3) are employed instead of S112 in the flow diagram (2). However, in this case, “ΔQ ← (max−min)” in S065 is “| ΔQ ← (max−min) |”, and ““ Change in flow rate ”determination is established” in S110 is “There is a change in flow rate”. The determination is satisfied.

  Similarly, in the flowchart (3-2), S065, S067, and S110 in the flowchart (3) are employed instead of S114 in the flowchart (2). However, in this case, “ΔQ ← (max−min)” in S065 is “| ΔQ ← (max−min) |”, and “Some changes in flow rate” is established in S110 is “There is a decrease in flow rate”. It becomes “determination establishment”.

  Although not shown, if the timer counted from the previous “flow rate change” determination exceeds the safe duration for the maximum flow rate, for example, there is a risk of gas leakage, and the shutoff valve is closed in the same manner as a conventional gas meter. Alternatively, the above-described function of the electronic gas meter according to the present invention and the security function of the conventional gas meter can be run by OR. What is necessary is just to select the optimal method according to the kind and use environment of gas consumption apparatus.

The block diagram which shows an electronic gas meter. The block diagram which shows a control means. The figure which illustrates notionally the judgment principle of the flow rate change judgment method of the electronic gas meter by this invention. FIG. 5 is still another view for conceptually explaining the determination principle of the flow rate change determination method for an electronic gas meter according to the present invention. Flow chart (0) for demonstrating the process sequence of an electronic gas meter. Flow chart (1) for demonstrating the other process sequence of an electronic gas meter. Flow chart (2) for demonstrating the further process sequence of an electronic gas meter. The flowchart (3) for demonstrating the further another process sequence of an electronic gas meter. The flowchart (3-1) for demonstrating the further another process sequence of an electronic gas meter. The flowchart (3-2) for demonstrating the further another process sequence of an electronic gas meter.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Electronic gas meter, 11 ... Flow rate sensor, 12 ... Pressure sensor, 13 ... Clock, 14 ... Memory | storage means (memory), 16 ... Control means, 17 ... Shut-off valve, 21 ... Flow measurement means, 22 ... N times average flow rate Calculation means, 23 ... Calculation means, 24 ... Comparison means, 25 ... Flow rate change determination means, 26 ... Continuous use time setting means, Q ... Instantaneous flow rate, P ... Measurement point, dQ ... Flow rate change for determining that there is a change in flow rate Threshold value, ΔQ ... difference value, Ta ... gas flow rate classification and safety duration (interruption time) correspondence table

Claims (7)

Instantaneous flow rate measuring means for measuring the instantaneous flow rate of the gas flowing through the gas flow path;
First storage means for storing an instantaneous flow rate measured by the instantaneous flow rate measurement means;
Second storage means for storing a specific instantaneous flow rate as a max value and a min value;
The instantaneous flow rate stored in the first and second storage means is read out, and the latest instantaneous flow rate is compared with the maximum value and the min value, and the maximum instantaneous flow rate is greater than the max value. First calculating means for updating the max value of the second storage means with the latest instantaneous flow rate, and updating the min value of the second storage means with the latest instantaneous flow rate if the latest instantaneous flow rate is smaller than the min value. ,
First comparison means for calculating a difference between the max value and the min value stored in the second storage means and comparing the difference value with a predetermined flow rate change threshold value;
A flow rate change determination means for determining the presence or absence of a change in the flow rate of the gas based on a comparison result by the first comparison means;
Second calculation means for updating the max value and the min value stored in the second storage means to the latest instantaneous flow rate when the flow rate change determination means determines that there is a flow rate change;
An electronic gas meter comprising:   The electronic system according to claim 1, further comprising means for determining whether a difference value exceeding the predetermined flow rate change threshold value is a difference value generated in an increasing direction or a difference value generated in a decreasing direction. Gas meter.   The flow rate change determination means further comprises second comparison means for calculating a temporal change amount of the difference value and comparing the temporal change amount with a temporal change amount threshold value of a predetermined flow rate. 3. The electronic gas meter according to claim 1, wherein presence or absence of a change in the flow rate of the gas is determined based on a comparison result by the comparison unit and the second comparison unit.   4. The electronic gas meter according to claim 1, further comprising safety duration setting means for setting a safety duration corresponding to a gas flow rate, wherein the safety duration setting means is configured to determine the flow rate change. An electronic gas meter characterized in that when the means determines that there is a flow rate change, the safety duration corresponding to the latest instantaneous flow rate is reset and the timer is reset.   The safety duration setting means resets the safety duration corresponding to the difference flow between the max value and the min value when the flow rate change determination means determines that there is a flow change as the safety duration corresponding to the instantaneous flow rate. The electronic gas meter according to claim 4, wherein the timer is reset.   The gas instantaneous flow rate measuring means includes an n-time average flow rate calculation unit for calculating an average of n (n is an integer) times at the time of n consecutive measurements, and a flow rate at each measurement point is an n-time average flow rate. An electronic gas meter according to any one of claims 1 to 5, wherein An instantaneous flow rate measuring step for measuring the instantaneous flow rate of the gas flowing through the gas flow path;
A first storage step for storing the instantaneous flow rate measured in the instantaneous flow rate measurement step;
A second storage step for storing a specific instantaneous flow rate as a max value and a min value;
The instantaneous flow rate stored in the first and second storage steps is read and the latest instantaneous flow rate is compared with the maximum value and the min value. If the latest instantaneous flow rate is greater than the max value, the first flow rate is calculated. A first calculation step in which the max value in the second storage step is updated with the latest instantaneous flow rate, and if the latest instantaneous flow rate is smaller than the min value, the min value in the second storage step is updated with the latest instantaneous flow rate; ,
A comparison step of calculating a difference between the max value and the min value stored in the second storage step and comparing the difference value with a predetermined flow rate change threshold value;
A flow rate change determination step for determining the presence or absence of a change in the flow rate of the gas based on the comparison result of the comparison step;
A second calculation step of updating the max value and the min value stored in the second storage step to the latest instantaneous flow rate when the flow rate change determination step determines that there is a flow rate change;
The flow rate change judgment method of the electronic gas meter characterized by including at least.

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