JP4418261B2 - Gain history device - Google Patents

Description

  The present invention relates to a gain history device.

  Currently, an ultrasonic gas meter using an ultrasonic flow velocity sensor has been proposed (for example, Patent Document 1). In the ultrasonic gas meter described above, an ultrasonic flow sensor is constituted by two acoustic transducers composed of, for example, piezoelectric transducers that operate at an ultrasonic frequency that are arranged at a predetermined distance in the gas flow path.

  Then, the ultrasonic signal generated by one transducer is received by the other transducer, the propagation time during which the ultrasonic signal is propagated between the transducers is measured, and the gas flow rate is intermittently determined based on the measured propagation time. The passage flow rate is obtained by multiplying the flow rate by the sectional area of the gas flow path and the intermittent time. Furthermore, an electronic gas meter can be configured by displaying the integrated flow rate obtained by integrating the passing flow rate.

  Incidentally, in recent years, in addition to the function of measuring the flow rate passing through the gas flow path described above, an electronic gas meter has a measurement abnormality in which the flow rate cannot be measured accurately due to a failure of the ultrasonic flow rate sensor or the like. Some of them have a function of detecting. With this function, the reliability of the electronic gas meter can be improved.

  As the above-described measurement abnormality detection, there is one using a gain adjustment function. The gain adjustment function is to accurately measure the propagation time of the ultrasonic signal described above, so that the gain of the amplifier that amplifies the transmitted or received ultrasonic signal is stabilized so that the level of the received ultrasonic signal is constant. To adjust. Specifically, as shown in FIG. 3, for example, the time from the transmission of the ultrasonic signal of the third pulse until the reception level of the ultrasonic signal becomes 0 immediately after exceeding the threshold A is measured as the propagation time. In this case, the gain is adjusted so that the reception level exceeds the threshold A only when the ultrasonic signal transmitted at the third pulse is received.

Even if the gain of the amplifier is maximized using this gain adjustment function, a measurement abnormality is detected when an ultrasonic signal exceeding the threshold A cannot be received. However, the conventional electronic gas meter has only a function for detecting a measurement abnormality, and what state the gain adjustment was in when the measurement abnormality occurred, and how the gain changed over time. It was not left as data. For this reason, it is impossible to analyze a change in gain that is very important with respect to measurement accuracy over time, and it has not been possible to narrow down specifically to which part an abnormality has occurred.
Japanese Patent Publication No.7-119638

  Therefore, the present invention pays attention to the above-mentioned problems, and by storing the gain history, it becomes possible to analyze the gain history and to narrow down the location where the abnormality has occurred based on the analysis result. It is an object of the present invention to provide a gain history device capable of

The invention according to claim 1 is a transmitting means for intermittently transmitting an ultrasonic signal in a gas flow path, a receiving means for receiving the ultrasonic signal, and the transmitting means transmits or has been received by the receiving means. An amplifying means for amplifying the ultrasonic signal and a gain adjusting means for adjusting the gain of the amplifying means are provided, and a propagation time from when the transmitting means transmits the ultrasonic signal to when the receiving means receives is obtained. Based on the obtained propagation time, when the abnormality of the flow velocity measuring device provided in the flow velocity measuring device for measuring the gas flow velocity occurs, adjustment is performed by the gain adjusting means to narrow down the abnormality occurrence point. The gain history apparatus is characterized by recording a gain adjustment history.

  According to the first aspect of the invention, the adjustment history of the gain adjusted by the gain adjusting means is recorded. Accordingly, it is possible to record a gain adjustment history that is important in the measurement control of the flow velocity measuring device.

  The invention according to claim 2 is the gain history apparatus according to claim 1, further comprising history data storage means for storing the adjustment history data of the gain, and a gain maximum value for each fixed period is used as the adjustment history data. The gain history apparatus stores the history data in the history data storage means.

  According to the invention described in claim 2, paying attention to the fact that an accurate gain analysis can be performed if the maximum value for each fixed period is analyzed, history data storage is performed using the maximum value for each fixed period as adjustment history data. Can be stored in the means.

  The invention according to claim 3 is the gain history device according to claim 2, wherein a plurality of flow velocity sections are provided, and in the fixed period, a gain maximum value for each flow velocity section is used as the adjustment history data as the history data. The gain history apparatus is characterized in that it is stored in a storage means.

  According to the invention of claim 3, paying attention to the fact that the gain varies depending on the flow velocity of the gas flowing in the gas flow path, the maximum gain value for each flow velocity section is adjusted in a certain period. The history data can be stored in the history data storage means.

  The invention according to claim 4 is the gain history device according to claim 2 or 3, wherein the maximum gain value storing means for storing the maximum gain value, the maximum gain value stored in the maximum gain value storing means, An update means for comparing the current gain of the amplifying means and, if the current gain value is greater than the maximum gain value, updating the maximum gain value to the current gain value, The gain history apparatus is characterized in that the maximum gain value stored in the maximum gain storage means is stored in the history data storage means as adjustment history data every time a certain period of time elapses.

  According to the fourth aspect of the present invention, the maximum gain value is stored in the maximum gain value storage means. The updating means compares the current gain value of the amplifying means with the gain maximum value stored in the gain maximum value storage means, and if the current gain value is greater than the gain maximum value, the gain maximum value is Update to the current gain value. Then, every time a certain period of time elapses, the maximum gain value stored in the maximum gain storage means is stored in the history data storage means as adjustment history data. Therefore, since the gain maximum value stored in the gain maximum value storage unit is updated by the updating unit, the maximum gain value can be used as history data without storing all the gains during a certain period.

  The invention according to claim 5 is the gain history device according to claim 1, further comprising history data means for storing the history data of the gain, and an average value of gains for a certain period is used as the adjustment history data. The gain history device is characterized in that it is stored in a data storage means.

  According to the invention described in claim 5, paying attention to the fact that an accurate gain analysis can be performed by analyzing the average value for each fixed period, the history data is stored using the average value for each fixed period as the adjustment history data. Can be stored in the means.

  The invention according to claim 6 is the gain history device according to claim 5, wherein a plurality of flow velocity sections are provided, and an average value of gains for each flow velocity section in the fixed period is used as the history data as the history data. The gain history apparatus is characterized in that it is stored in a storage means.

  According to the sixth aspect of the invention, paying attention to the fact that the gain fluctuates depending on the flow velocity of the gas flowing in the gas flow path, the gain average value for each flow velocity section in the fixed period is adjusted history. The data can be stored in the history data storage means.

  As described above, according to the first aspect of the present invention, the gain adjustment history important in the measurement control of the flow velocity measuring device can be recorded, so that the recorded adjustment history can be analyzed. In addition, it is possible to obtain a gain history device that can narrow down the location where an abnormality has occurred based on the analysis result.

  According to the second aspect of the present invention, since the maximum value for each fixed period can be stored as the adjustment history data in the history data storage means, it is possible to accurately store the gain without storing all the gains as the adjustment history data. Gain analysis can be performed, and a gain history device with a small memory capacity and reduced cost can be obtained.

  According to the third aspect of the present invention, since the gain maximum value for each flow velocity section can be stored in the history data storage means as the adjustment history data in a certain period, further accurate gain analysis can be performed. A gain history device that can be performed can be obtained.

  According to the fourth aspect of the present invention, since the maximum gain value stored in the maximum gain value storage unit is updated by the updating unit, the maximum gain value is recorded in the history without storing all the gains during a certain period. Since it can be used as data, a gain history device with a small memory capacity and reduced costs can be obtained.

  According to the fifth aspect of the present invention, since the average value for each fixed period can be stored as adjustment history data in the history data storage means, it is possible to accurately store all gains without storing them as adjustment history data. Gain analysis can be performed, and a gain history device with a small memory capacity and reduced cost can be obtained.

  According to the sixth aspect of the present invention, since the gain average value for each flow velocity section can be stored in the history data storage means as the adjustment history data in a certain period, a more accurate gain analysis can be performed. A gain history device that can be performed can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an electronic gas meter incorporating the gain history device of the present invention. The illustrated electronic gas meter is configured as an ultrasonic type, and is arranged so as to be opposed to each other so as to be separated by a distance L in the gas flow path and at an angle θ with respect to the gas flow direction Y. There are two acoustic transducers TD1 and TD2.

  The two acoustic transducers TD1 and TD2 are composed of, for example, piezoelectric vibrators that operate at an ultrasonic frequency. The gas flow path is provided with a gas shut-off valve 10 that shuts off the gas flow path by closing the valve upstream of the two acoustic transducers TD1 and TD2.

  Each transducer TD1 and TD2 is connected to a transmission circuit 12 and a reception circuit 13 via transducer interface (I / F) circuits 11a and 11b, respectively. The transmission circuit 12 transmits a signal for generating an ultrasonic signal by driving one of the transducers TD1 and TD2 in the form of a pulse burst under the control of the microcomputer (μCOM) 14, and an oscillation circuit (see FIG. (Not shown).

  The receiving circuit 13 incorporates an amplifier 13a (= amplifying means) that inputs signals from the other transducers TD1 and TD2 that have received the ultrasonic signals that have passed through the gas flow path and amplifies the ultrasonic signals. The gain of the amplifier 13 a can be adjusted by the μCOM 14. Further, a display 15 is connected to the μCOM 14.

  As shown in FIG. 2, the μCOM 14 described above includes a central processing unit (CPU) 14a that performs various processes according to a program, a ROM 14b that is a read-only memory that stores a program for processing performed by the CPU 14a, and the like. A RAM 14c, which is a readable / writable memory having a work area used in the processing process, a data storage area for storing various data, and the like are incorporated, and these are connected to each other by a bus line 14d.

  Next, the operation of the electronic gas meter having the above-described configuration will be described. The above-described CPU 14a uses the two transducers TD1 and TD2 to measure the gas flow rate at each sampling time, and performs the instantaneous flow rate measurement process of measuring the instantaneous flow rate by multiplying the measured gas flow rate by the cross-sectional area of the gas flow path. . Details of the instantaneous flow rate measurement process will be described below.

  First, the CPU 14a outputs a trigger signal to the transmission circuit 12 to generate a pulse burst signal, supplies the pulse burst signal to one of the transducers TD1 and TD2, and causes this one transducer to generate an ultrasonic signal. In addition, the receiving circuit 13 receives a signal from the other transducer that receives the ultrasonic signal transmitted from one transducer, and captures a signal generated by the receiving circuit 13 in response thereto. As is clear from the above, the transmission circuit 12 corresponds to the transmission means in the claims, and the reception circuit 13 corresponds to the reception means in the claims.

  Thereafter, the CPU 14a performs control to turn back the same operation again by reversing the transducer for generating the ultrasonic signal and the transducer for receiving the ultrasonic signal. Then, the CPU 14a uses the propagation time timer formed in the RAM 14c to output a trigger signal to the transmission circuit 12 to generate an ultrasonic signal of one transducer, and then receives the ultrasonic signal of the other transducer. Propagation times T1 and T2 until a signal that occurs is received through the receiving circuit 13 are measured.

Assuming that the speed of sound is c and the flow velocity of the gas flow is v, the propagation speed of the ultrasonic signal from the transducer TD1 to the transducer TD2 is (c + v cos θ), and the propagation speed of the ultrasonic signal from the transducer TD2 to the transducer TD1 is (c− vcos θ). Accordingly, if the distance between the transducers TD1 and TD2 is L, the time T1 when the ultrasonic signal from the transducer TD1 travels in the same direction Y as the gas flow and reaches the transducer TD2, and the ultrasonic signal from the transducer TD2 is the gas flow. The time T2 that travels in the opposite direction to reach the transducer TD2 is
T1 = L / (c + vcos θ) (1)
T2 = L / (c−v cos θ) (2)
It becomes.

From equations (1) and (2), v = (L / 2 cos θ) · (1 / T1-1 / T2)
= (L / 2cos θ) · {(T2−T1) / (T2 · T1)} (3)
Thus, when L is known, the flow velocity v can be obtained by measuring T1 and T2.

T2 · T1 = L ² / {(c + vcos θ) · (c−vcos θ)}
= L ² / (c ² −v ² cos ² θ)
Since the flow velocity v is an extremely small numerical value compared with the sound velocity c, v ^{2 in} the equation can be negligibly small compared with c ² cos ² θ, and T2 · T1 = L ² / c ² can be obtained. . And the above equation (3) finally becomes
v = {(T2-T1) · c ² } / 2L cos θ
= (T2-T1). (C ² ). (1 / 2L cos θ)
Can be rewritten. Here, when Td = (T2−T1),
v = Td · k (4)
Where k = c ² / 2L cos θ
It becomes.

  That is, the gas flow velocity v is obtained by multiplying the difference Td in the propagation time of the ultrasonic signal by the constant k. The instantaneous flow rate can be obtained by multiplying the gas flow velocity v by the cross-sectional area of the gas flow path. The CPU 14a further multiplies the obtained instantaneous flow rate by the sampling time to obtain a flow rate measurement process for obtaining the gas passage flow rate, an integration process for integrating the obtained passage flow rate, and a display for displaying the accumulated passage flow rate on the display 15. Process.

  In addition, every time the above-described flow rate measurement process is performed, the CPU 14a functions as a gain adjustment unit, and performs a gain adjustment process of the amplifier 13a and a measurement abnormality detection process that detects that a measurement abnormality has occurred. Next, details of the gain adjustment processing and measurement abnormality detection processing will be described below with reference to FIG. As shown in the figure, when a pulsed ultrasonic signal is output from the transmitting side, the peak is gradually increased on the receiving side and received. At this time, for example, the time from the transmission of the ultrasonic signal of the third pulse until the reception level of the ultrasonic sensor becomes 0 immediately after exceeding the threshold A is measured as the ultrasonic signal propagation times T1 and T2.

  Therefore, in order to accurately measure the flow velocity, it is necessary to adjust the gain of the received ultrasonic signal so that the reception level exceeds the threshold A only when the ultrasonic signal transmitted at the third pulse is received. Specifically, the gain of the amplifier 13a is adjusted so that the peak P after the reception level becomes 0 immediately after the reception level exceeds the threshold A falls within the predetermined range B. Utilizing this gain adjustment function, the CPU 14a detects a measurement abnormality when an ultrasonic signal exceeding the threshold A cannot be received even when the gain of the amplifier 13a is maximized.

  Further, the CPU 14a performs history processing for recording the gain history of the amplifier 13a adjusted by the gain adjustment processing in parallel with the above-described instantaneous flow rate measurement processing, gain adjustment processing, and measurement abnormality detection processing. This history processing will be described with reference to the flowchart of FIG. 4 for explaining the processing procedure of the CPU 14a.

  First, the CPU 14a starts operation by turning on a power supply (not shown), and starts a one-month timer formed in the RAM 14c in the first step S1 (step S1). Next, the current gain Gn of the amplifier 13a is acquired (step S2), and the acquired current gain Gn is the gain maximum value stored in the gain maximum value area (= gain maximum value storage means) formed in the RAM 14c. It is determined whether or not it is greater than Gmax (step S3).

  When Gn> Gmax (Y in step S3), the CPU 14a functions as an updating unit, updates the gain maximum value Gmax to the current gain Gn (step S4), and then proceeds to step S5. On the other hand, if Gn ≦ Gmax (N in step S3), the CPU 14a immediately proceeds to step S5 without updating the maximum gain value Gmax. In step S5, the CPU 14a determines whether or not the one-month timer has exceeded one month (step S5).

  If it has not exceeded one month (N in step S5), the CPU 14a returns to step S2 again. On the other hand, if it exceeds 1 month (Y in step S5), the CPU 14a uses the gain maximum value Gmax stored in the gain maximum value area as history data, and the history data area (= After being stored in the history data storage means (step S6), the maximum gain Gmax is reset to 0 (step S7), and the process returns to step S1.

  Through the above history processing, the maximum gain value for each month is sequentially stored as history data in the history data area. Thereby, when a measurement abnormality or the like occurs, the gain history can be analyzed. By the way, although the process up to the abnormality is various, the abnormality does not basically occur at first, and then suddenly or gradually becomes strange. It is possible to narrow down where an abnormality has occurred by grasping from the history data of gain whether it suddenly went wrong or gradually became strange.

  For example, factors that occur suddenly include noise, mixing of other gases, amplifier 13a, μCOM 14a, receiving circuit 13, ultrasonic transducers TD1 and TD2, and the like. On the other hand, factors that gradually become strange include, for example, corrosion in the gas channel, reduced sensitivity due to intrusion of dust and drain into the gas channel, and decreased sensitivity due to deterioration over time of the acoustic transducers TD1 and TD2. Can be considered. As described above, the cause of the abnormality can be narrowed down by analyzing the history data of the gain and grasping whether it has suddenly become abnormal or gradually becomes abnormal.

  Further, according to the electronic gas meter described above, when the current gain Gn is greater than the maximum gain value Gmax, the maximum gain value Gmax is updated to the current gain Gn. Thus, since the maximum gain value Gmax is updated, the maximum gain value for one month can be obtained without storing all of the gain history for one month, and the memory capacity can be reduced, resulting in cost reduction. Can be achieved.

  In the above-described embodiment, the maximum gain value for one month is used as history data. However, for example, every time the gain is adjusted, it is possible to leave all the gains as history data. However, a large-capacity memory is required to leave all gains as history data. Further, in order to narrow down the cause of occurrence of abnormality, it is not necessary to analyze from history data of all gains, and it is sufficient to analyze the maximum gain value for a certain period (one month in this embodiment).

  In the above-described embodiment, the maximum gain value for each month is used as the history data. However, for example, paying attention to the fact that the gain value varies somewhat depending on the gas flow velocity flowing in the gas flow path, a plurality of flow velocity segments are provided, and the maximum gain value for each flow velocity segment in one month is used as the history data. It is also possible to do. If such history data is analyzed, a more accurate gain analysis can be performed. In this case, the RAM 14c is provided with a gain maximum value area for each flow velocity section, and the gain maximum value stored in the gain maximum value area corresponding to the current flow velocity is compared with the current gain. Update if the current gain is large.

  In the above-described embodiment, the maximum gain value is used as history data. However, for example, it is also possible to use an average gain value for one month as history data. Furthermore, it is also conceivable to use the gain average value for each flow velocity category during one month as history data.

  Further, in the above-described embodiment, the gain history of the amplifier 13a that amplifies the received ultrasonic signal is left. However, when gain adjustment is performed for an amplifier that amplifies an ultrasonic signal to be transmitted, it is conceivable to leave the gain history.

It is a figure which shows one Embodiment of the electronic gas meter incorporating the gain history apparatus of this invention. It is a block diagram which shows the detail of (micro | micron | mu) 14 which comprises the electronic gas meter of FIG. It is a time chart for demonstrating the gain adjustment process and measurement abnormality detection process which CPU14a of FIG. 2 performs. It is a flowchart which shows the process sequence in the log | history process of CPU14a which comprises the electronic gas meter of FIG.

Explanation of symbols

12 Transmission circuit (transmission means)
13 Receiving circuit (receiving means)
13a Amplifier (amplifying means)
14a CPU (gain adjustment means, update means)
14c RAM (history data storage means, gain maximum value storage means)

Claims (6)

Transmitting means for intermittently transmitting an ultrasonic signal in the gas flow path, receiving means for receiving the ultrasonic signal, and amplifying means for amplifying the ultrasonic signal transmitted by the receiving means or received by the receiving means And a gain adjusting means for adjusting the gain of the amplifying means, a propagation time from when the transmitting means transmits an ultrasonic signal until reception by the receiving means is obtained, and based on the obtained propagation time The adjustment history of the gain adjusted by the gain adjusting means is recorded in order to narrow down the location of the abnormality when the abnormality of the flow velocity measuring device provided in the flow velocity measuring device for measuring the gas flow velocity occurs. A gain history device. The gain history device according to claim 1,
A history data storage means for storing the gain adjustment history data;
A gain history apparatus, wherein a maximum gain value for each predetermined period is stored in the history data storage means as the adjustment history data. The gain history device according to claim 2,
A gain history apparatus characterized in that a plurality of flow velocity sections are provided and a maximum gain value for each flow velocity section is stored in the history data storage means as the adjustment history data in the predetermined period. The gain history device according to claim 2 or 3,
A gain maximum value storing means for storing a gain maximum value;
The gain maximum value stored in the gain maximum value storage means is compared with the current gain of the amplifying means.If the current gain value is larger than the gain maximum value, the gain maximum value is Updating means for updating to the current gain value,
A gain history apparatus that stores the maximum gain value stored in the maximum gain storage means as adjustment history data in the history data storage means every time the fixed period elapses. The gain history device according to claim 1,
A history data means for storing the history data of the gain,
An average gain value for each fixed period is stored in the history data storage means as adjustment history data. The gain history device according to claim 5,
A gain history apparatus, comprising: a plurality of flow velocity sections, wherein an average value of gains for each flow velocity section is stored in the history data storage means as the history data during the predetermined period.

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