JP4184989B2 - Fluid measuring device and gas meter - Google Patents

Description

  The present invention relates to a fluid measurement device and a gas meter, and more specifically, a fluid measurement device that amplifies a signal corresponding to the flow of fluid output from a flow sensor by an amplifying unit and measures the flow rate of the fluid based on the signal, And it is related with the gas meter provided with a fluid measuring device.

  An ultrasonic fluid measuring device that measures the flow rate of a fluid such as a gas operates with two acoustic transducers, for example, piezoelectric transducers that operate at an ultrasonic frequency that is disposed at a certain distance in the gas flow path. And alternately performing the operation of causing the other transducer to receive the ultrasonic signal generated by one transducer and measuring the time during which the ultrasonic signal propagates between the transducers in the gas flow direction and the opposite direction. Based on the two measured propagation times, the flow velocity of the gas flowing in the gas flow path is obtained intermittently, and the instantaneous flow rate is obtained by multiplying the flow velocity by the cross-sectional area of the gas flow path.

  The gas meter then calculates the passing flow rate by multiplying the instantaneous flow rate obtained by the fluid measuring device by an intermittent measurement time, that is, the sampling period, and further displays the integrated flow rate obtained by integrating the passing flow rate on the display unit. Yes.

In addition, a fluid measuring device is disclosed that can detect measurement errors and failures due to changes in characteristics of ultrasonic transducers by self-diagnosis (Patent Document 1). This fluid measuring device self-diagnoses a decrease in measurement accuracy due to changes in the characteristics of two ultrasonic transducers over time, temperature changes in the characteristics, or impedance changes due to corrosion of the terminals connecting the ultrasonic transducers and wiring. This diagnosis has prevented a decrease in measurement accuracy.
Japanese Patent Laid-Open No. 2003-329502

  The fluid measuring apparatus has conventionally prevented a decrease in measurement accuracy by self-diagnosis, but there is still a problem that the measurement accuracy decreases after a number of years. When examining the fluid measurement device that caused this problem, the received ultrasonic signal was amplified with an amplifier, the propagation time from transmission to reception was measured based on the waveform, and the flow velocity was calculated from the result. It was found to be a fluid measuring device that calculates the flow rate.

  In the case of such a fluid measurement device, the point to capture waveform reception is determined, but if the waveform is not stable due to deterioration of the performance of the amplifier over time, it will deviate from the point that it should originally capture, and as a result The calculation of a different flow velocity caused a decrease in measurement accuracy. Therefore, it is conceivable to stop the measurement when the amplifier is deteriorated. However, in this case, problems such as the inability of the consumer to use gas occur, and this cannot be realized.

  Therefore, in view of the above-described problems, an object of the present invention is to provide a fluid measuring device and a gas meter that can prevent a decrease in measurement accuracy.

The fluid measurement device made claims 1, wherein the present invention for solving the above problems, as shown in the basic diagram of Fig. 1, a flow rate sensor 5 for outputting a signal corresponding to the flow of fluid, the flow rate sensor A fluid measuring device comprising: amplifying means 5a for amplifying the signal output from 5 at an arbitrarily determined gain level; and a flow rate measuring means P1 for measuring the flow rate of the fluid based on the signal amplified by the amplifying means 5a. The gain level detecting means P2 for detecting the gain level of the amplifying means 5a corresponding to the flow rate measured by the fluid measuring means P1, the flow rate measured by the flow rate measuring means P1 and the gain level corresponding to the flow rate. History information generating means P3 for generating history information indicating the gain level detected by the detecting means P2, and history information generated by the history information generating means P3 are stored in time series. History information storage means 9b, deterioration detection means P4 for detecting deterioration of the predetermined gain level based on history information having the same flow rate stored in the history information storage means 9b, and the deterioration Alarm information generating means P5 for generating alarm information for alarming deterioration of the amplifying means 5a detected by the detecting means P4, and alarm information output means for outputting the alarm information generated by the alarm information generating means P5 for the alarm And P6.

According to the fluid measuring device of the present invention described in claim 1, when the gain level of the amplifying means 5a corresponding to the flow rate measured by the fluid measuring means P1 is detected by the gain level detecting means P2, these flow rates are determined. History information indicating the gain level is generated by the history information generation means P3 and stored in the history information storage means 9b in time series. And when deterioration of a predetermined gain level is detected by the deterioration detection means P4 based on history information having the same flow rate stored in the history information storage means 9b, it is generated by the alarm information generation means P5. The alarm information is output by the alarm information output means P6 to a display device, a communication device, an alarm device or the like for alarm.

In order to solve the above problems, a gas meter according to claim 2 according to the present invention comprises the fluid measuring device according to claim 1 as shown in the basic configuration diagram of FIG . 1 , and the gas measured by the fluid measuring device. It is a gas meter which measures the usage-amount of the said gas based on the flow volume of this, Comprising: The alarm means 4 which alerts based on the alarm information which the alarm information output means P6 of the said fluid measuring device output is provided, It is characterized by the above-mentioned.

According to the gas meter of the present invention described in claim 2 above, when alarm information is output by the alarm information output means P6 in response to detection of deterioration of the amplifying means, the amplifying means 5a is deteriorated based on the alarm information. For example, the alarm means 4 performs an alarm by displaying on a gas meter display device, reporting to a gas company, or the like.

As described above, according to the fluid measuring device of the present invention described in claim 1 , the flow rate and the gain level corresponding to the flow rate are stored as history information, and the gain level is determined based on the history information having the same flow rate. Since the deterioration is monitored and alarm information is output when the deterioration is detected, the deterioration of the amplifying means can be recognized by referring the alarm information to the fluid supply side. Even if the gain level changes with the flow rate such that the gain level is low when the flow rate is small, deterioration is determined based on the history of the gain level corresponding to the same flow rate. It is possible to accurately grasp the secular change of the gain level of the means. Therefore, since the fluid supply side can confirm in advance a decrease in measurement accuracy due to the influence of deterioration of the amplification means, it is possible to take early measures such as replacement of the amplification means, level adjustment, etc. A decrease can be prevented. In addition, for the consumer, the occurrence of a long period of fluid interruption due to a decrease in measurement accuracy is avoided.

As described above, according to the gas meter of the present invention described in claim 2, when the deterioration of the amplification means is detected by the fluid measuring device, an alarm is given. Deterioration can be recognized quickly. Therefore, the gas company can confirm in advance the decrease in measurement accuracy due to the effect of deterioration of the amplification means, so it is possible to take early measures such as replacement of the amplification means, level adjustment, etc. Therefore, it is possible to measure the exact amount of gas used. In addition, for the consumer, it is possible to avoid the occurrence of a long-term gas interruption period due to a decrease in measurement accuracy.

Hereinafter, according to the present invention, for example a gas, the best mode when incorporated in a gas meter the fluid measurement apparatus used in measurement of a fluid such as water, will be described with reference to the drawings in FIGS. 2-5.

Here, FIG. 2 is a block diagram showing an example of a schematic configuration of the gas meter of the present invention, and FIG. 3 is an explanation showing the configuration of the sensor circuit unit and the ultrasonic transducer shown in FIG. 2 and the operation of the ultrasonic transducer. FIG . 4 is a flowchart showing an example of gain history generation processing executed by the CPU of FIG. 2, and FIG. 5 is a flowchart showing an example of gain monitoring processing executed by the CPU of FIG.

Extracting the propagation time of the ultrasonic wave in a predetermined time between ultrasonic transducers (transmitter / receivers) provided in the gas flow path through which the gas is transmitted or received, and the extracted propagation time As shown in FIG. 2, a gas meter to which a fluid measuring device that measures the flow rate of gas is applied is a microprocessor (MPU) 1, an operation unit 2, a display unit 3, an alarm unit 4, an ultrasonic flow sensor. 5, seismic sensor 6, communication unit 7, electromagnetic shut-off valve 8, memory 9, and battery B such as a lithium battery.

  The operation unit 2, display unit 3, alarm unit 4, ultrasonic flow sensor 5, seismic sensor 6, communication unit 7, and memory 9 basically include the MPU 1 and the components 2, 3 connected thereto. 4, 6, 7 and 9 are connected to the MPU 1 via an interface unit (not shown) having a voltage conversion function. The electromagnetic shut-off valve 8 is connected to the MPU 1 via the shut-off valve drive unit 81.

  As is well known, the MPU 1 includes a CPU 1a, a ROM 1b, and a RAM 1c. The CPU 1a performs basic control, flow rate measurement and pressure detection, battery voltage check, battery remaining capacity monitoring, installation environment determination according to the present invention described later, and the like according to a control program stored in the ROM 1b. The ROM 1b stores in advance various programs such as a basic control program, a control program for detecting flow rate measurement, calculating an integrated flow rate, and a program for monitoring the installation environment. The RAM 1c basically functions as a work area for temporarily storing variables and data generated during the process performed by the CPU 1a.

  The operation unit 2 includes a switch group for inputting a command to start or end the gas meter, stop an abnormality alarm, or change the display of the display unit 3. These commands are input to the MPU 1 by manually operating the operation unit 2.

  The display unit 3 receives a command from the MPU 1 via the interface unit 11 and displays various abnormality alarms such as integrated flow rate display, seismic sensitivity, gas leakage, and battery voltage drop in response to the command. As this display part 3, well-known LED etc. are assumed, for example. When a plurality of LEDs are used as the display unit 3, different types of alarms can be displayed by changing the combination of LED displays.

  The alarm unit 4 corresponding to the alarm means in the claims is configured to have an alarm buzzer, etc., and receives various data such as alarm information from the MPU 1 via the interface unit 11, and responds to this. A warning sound is emitted. In addition, about an alarm, it can be set as various different embodiments by the specification of a gas meter, such as the combination of the display of the alarm screen by the display part 3, and the alarm sound which the alarm part 4 emits.

  The ultrasonic flow sensor 5 corresponding to the flow sensor in the claims is composed of a pair of ultrasonic vibrators disposed in the gas flow path. The ultrasonic flow sensor 5 is connected to the MPU 1 through the sensor circuit unit 51. The MPU 1 calculates the flow velocity and flow rate of the gas passing through the gas flow path based on the ultrasonic signal propagation time between the pair of ultrasonic transducers of the ultrasonic flow sensor 5. This will be described later with reference to FIG.

  Note that the flow sensor is not limited to the ultrasonic flow sensor 5, and other various sensors such as a flow sensor can also be used. In the present invention, the signal of the flow sensor is amplified by the amplification means. This is effective for a configuration in which the MPU 1 and the like are input.

  The seismic sensor 6 includes a known seismic element that generates an on / off signal in response to a shake caused by an earthquake or the like and supplies the signal to the MPU 1 via the interface unit 11. For example, the MPU 1 determines the degree of shaking from the number of on / off signals received within a predetermined time, and performs abnormal processing such as valve closing control of the shut-off valve when the shaking is large.

  The communication unit 7 has a function of making a predetermined telegram call using a public line such as a telephone line. The communication unit 7 is also connected to an NCU (network control unit) 71 for controlling communication with the management center of the gas sales company through a public line such as a telephone line.

  The electromagnetic shut-off valve 8 includes a valve drive solenoid coil and is connected to a shut-off valve drive unit 81 which is a drive circuit for the solenoid coil. The shut-off valve drive unit 81 is instructed by the MPU 1 to generate a solenoid coil drive signal using the lithium battery B as a power supply source, and supplies this to the electromagnetic shut-off valve 8. In response to this, the electromagnetic shut-off valve 8 is opened or closed to shut off the gas flow path.

  The memory 9 is capable of holding various stored data even when the power supply from the battery B is cut off, and is an electrically erasable / rewritable read-only memory having various storage areas necessary for processing operations of the CPU 1a. The memory (EEPROM) is connected to the MPU 1 in a readable / writable manner. The memory 9 stores various counters necessary for measuring the amount of gas used, identification information for identifying the gas meter 10, and the like.

  The battery B serves as a power supply source for the gas meter. The battery B is frequently used for this type of gas meter because it can be used for a long time and has high versatility. On the other hand, the battery B becomes inactive at low temperatures, and the battery voltage decreases despite the remaining battery level. Sometimes.

  The gas meter having such a configuration is applied to, for example, an LPG supply facility. In this case, the gas meter is interposed in a pipe connecting a pressure regulator that regulates the high-pressure gas stored in the LPG container and a gas combustor to which the regulated gas is supplied.

  The gas meter usually detects the flow rate of the gas passing through the gas flow path using the ultrasonic flow rate sensor 5, integrates the flow rate, and displays it on the display unit 3. Further, when the gas meter detects abnormal shaking by the seismic sensor 6, the gas meter displays the fact on the display unit 3 and closes the electromagnetic shut-off valve 8. Further, at the same time, the gas meter transmits a message indicating an abnormal state to a management center such as a gas sales company or a gas company through the communication unit 7, the NCU 71, and a public line such as a telephone line. Furthermore, this gas meter periodically checks the battery voltage, and when the battery voltage drops, a message to that effect is displayed on the display unit 3.

  Next, the configuration of the ultrasonic flow sensor 5 and the sensor circuit unit 51 shown in FIG. 2 and the principle of temperature detection using the ultrasonic flow sensor 5 will be described with reference to FIG.

  As shown in FIG. 3, the sensor circuit unit 51 includes a transmission circuit 511, a reception circuit 512, a switching circuit 513, an amplifier 514, a peak hold circuit 515, and a gain monitoring unit 516. The switching circuit 513 is instructed by the MPU 1 to alternately connect the ultrasonic transducers 5 a and 5 b as the ultrasonic flow rate sensor 5 shown in FIG. 2 to the transmission circuit 511 and the reception circuit 512.

  An amplifier 514 is connected to the receiving circuit 512, a peak hold circuit 515 is connected to the amplifier 514, and MPU 1 is connected to the peak hold circuit 515. Then, the receiving circuit 512 amplifies the output signal by the amplifier 514, and the MPU 1 captures the peak hold value from the peak hold circuit 515 into the RAM 1c or the like.

  The amplifier 514 is configured to be able to set the gain level in a stepwise range, for example, in the range of 0 to 128, and amplifies the signal at the gain level instructed from the MPU 1. As an example of the gain level setting means, an arbitrary value is taken into the gas meter from the outside by a message, and the value is set in the amplifier 514.

  For example, the peak hold circuit 515 detects the peak hold value of the digital signal converted by the A / D converter, and outputs the detected peak hold value to the MPU 1. The gain monitoring unit 516 also checks the gain level of the amplifier 514 and outputs gain level data corresponding to the gain level in response to a request from the MPU 1.

  Regarding the operation in the sensor circuit unit 51, when the ultrasonic transducer 5a is connected to the transmission circuit 511, the ultrasonic signal is transmitted from the ultrasonic transducer 5a to the ultrasonic transducer 5b. This ultrasonic signal propagates through the gas to be measured and is received by the ultrasonic transducer 5 b connected to the receiving circuit 512. The ultrasonic transducer 5b that receives the ultrasonic signal generates a signal corresponding to the ultrasonic signal, and supplies the signal to the MPU 1 via the receiving circuit 512, the amplifier 514, and the peak hold circuit 515. On the other hand, when the ultrasonic transducer 5b is connected to the transmission circuit 511, ultrasonic signals are transmitted and received in the opposite direction to the above. The MPU 1 can calculate the flow velocity and flow rate of the gas to be measured based on the propagation time of the ultrasonic signals in both directions.

In other words, it is assumed that the pair of ultrasonic transducers 5a and 5b is disposed opposite to the gas flow path 52 with an angle of θ. Here, in the figure, the average flow velocity of the gas to be measured flowing in the direction indicated by the arrow is V, the distance between the ultrasonic transducers 5a and 5b is L, the line connecting the ultrasonic transducers 5a and 5b and the gas flow path 52. Assuming that the angle formed by the central axis is θ, and the uplink and downlink propagation times of the ultrasonic signal are tu and td, respectively,
As the average flow velocity V is already known,
V = L / 2COS (1 / td-1 / tu). ... (Formula 1)
And if Q is the flow rate, S is the passage area, and K is the correction count,
Q = KSV (Formula 2)
As a result, the flow rate Q of the fluid passing through the gas flow path 52 is calculated.

  The ROM 1b stores various programs such as the programs indicating the arithmetic expressions of (Expression 1) and (Expression 2) described above. The RAM 1c has a storage area for storing various data such as the number of samplings, energization time, and remaining battery level. The total number of sampling times for which the propagation times between the ultrasonic transducers are extracted is stored in the number of sampling times.

Next, the best mode of the above configuration will be described below. In this case, the ROM 1b includes a program indicating the arithmetic expressions of (Expression 1) and (Expression 2) described above, and the CPU 1a as a flow rate measuring means, a gain level detecting means, a history information generating means, a deterioration detecting means, Various programs for causing the CPU 1a to function as alarm information generation means and alarm information output means are stored.

  Further, the memory 9 stores a history information storage area in which history information indicating the measured flow rate and a gain level corresponding to the flow rate is stored in time series, and a maximum gain level in which a maximum gain level within a predetermined sampling time is stored. It has various areas such as a gain level storage area. Therefore, in the second best mode, the memory 9 functions as history information storage means described in the claims.

Next, an example of the processing outline of the gain history generation processing executed by the CPU 1a of the gas meter having the above-described configuration will be described below with reference to the flowchart of FIG .

When the gain history generation process shown in FIG. 4 is executed in response to the activation of the CPU 1a, a timer that times out when a predetermined sampling time elapses is started in step S31, and then the sampling process is executed in step S32. When the process ends, the process proceeds to step S33.

  In the sampling process, as described above, the sensor circuit 51 is controlled so that the ultrasonic transducer 5b is connected to the transmission circuit 511, and the transmission circuit 511 is energized, so that the ultrasonic signal is in the gas to be measured. And is received by the ultrasonic transducer 5b connected to the receiving circuit 512. The ultrasonic transducer 5b that receives the ultrasonic signal generates a signal corresponding to the ultrasonic signal, which is amplified by the amplifier 514 via the receiving circuit 512, and the peak hold value is the peak hold circuit 515. Is detected, and the peak hold value is taken into the MPU 1 so that the upward propagation time is measured by the CPU 1a. This process is performed a plurality of times, and the uplink propagation times are stored in the RAM 1c. Thereafter, the sensor circuit unit 51 is controlled so that the ultrasonic transducer 5a is connected to the transmission circuit 511, and a plurality of downlink propagation times are measured in the same manner as described above, and these downlink propagation times are measured. Is also stored in the RAM 1c.

  In step S33, the average of the uplink and downlink propagation times sampled at the current sampling time is calculated as the uplink and downlink propagation times tu and td and stored in the RAM 1c. Then, in step S34, the propagation time tu and the RAM 1c A flow velocity (instantaneous flow rate) is calculated based on td and the arithmetic expression of (Equation 1), and then in step S35, a flow rate is calculated based on the calculated flow velocity and the calculation equation of (Equation 2). This flow rate is stored in the RAM 1c, and then the process proceeds to step S36. Therefore, a series of processing of steps S32 to S35 corresponds to the flow rate measuring means in the claims.

  In step S36 (gain level detection means), the gain level data is taken into the RAM 1c from the gain monitoring unit 516, whereby the gain level of the amplifier 514 is detected in the RAM 1c. Thereafter, the calculated flow rate is determined in advance in step S37. It is determined whether or not the specified flow rate is reached. If it is determined that the flow rate is not the prescribed flow rate (N in S37), the process proceeds to step S40. On the other hand, if it is determined that the flow rate is the prescribed flow rate (Y in S37), the process proceeds to step S38.

  In step S38, it is determined whether or not the gain level of the RAM 1c is larger than the maximum gain level of the memory 9. If it is determined that the gain level is not greater than the maximum gain level (N in S38), the process proceeds to step S40. On the other hand, if it is determined that the gain level is greater than the maximum gain level (Y in S38), the process proceeds to step S39.

  In step S39, the maximum gain level is updated by setting the gain level of the RAM 1c to the maximum gain level of the memory 9, and then in step S40, it is determined whether or not the timer has timed out. When it is determined that the timeout has not occurred (N in S40), the process returns to step S32, and a series of processes is repeated. On the other hand, if it is determined that a timeout has occurred (Y in S40), the process proceeds to step 41.

  In step S41 (history information generating means), history information indicating the specified flow rate and the maximum gain level of the memory 9 corresponding to the specified flow rate is generated in the RAM 1c. In step S42, the history information is stored in the history information storage area of the memory 9. The history information is registered by being added and stored in series, and the maximum gain level of the memory 9 is reset in step S43, and then the process proceeds to step S44.

  In step S44, it is determined whether an end request has been received. If it is determined that an end request has not been received (N in S44), the process returns to step S31, and a series of processing is repeated. On the other hand, if it is determined that an end request has been received (Y in S44), the process ends.

Next, an example of a process overview of the gain monitoring process executed by the CPU 1a of the gas meter having the above-described configuration will be described below with reference to the flowchart of FIG . The gain monitoring process is executed with the gain history generation process described above.

When the gain monitoring process shown in FIG. 5 is executed in response to the activation of the CPU 1a, it is determined in step S51 whether or not history information is registered in the history information storage area of the memory 9. If it is determined that it is not registered (N in S51), the determination process is repeated to wait for the registration of history information. On the other hand, if it is determined that it is registered (Y in S51), the process proceeds to step S52.

  In step S52, it is determined whether a predetermined change in the gain level is detected based on the gain level ratio between the history information registered this time and the previous history information. For example, it is determined whether or not the gain level ratio is larger than a determination value (such as 1.05). If it is determined that a change in gain level has not been detected (N in S52), the process proceeds to step S55. On the other hand, if it is determined that a change in gain level has been detected (Y in S52), the process proceeds to step S53.

  In step S53, the gain abnormality counter in the RAM 1c is updated by being incremented. Thereafter, in step S54, it is determined whether or not the gain abnormality counter is larger than a predetermined deterioration determination value. If it is determined that the value is not larger than the deterioration determination value (N in S54), the history information registered this time is set as the previous history information in step S55, and then the process returns to step S51 to repeat a series of processes.

  If it is determined in step S54 that the value is larger than the deterioration determination value, that is, it is determined that the amplifier 514 is deteriorated (Y in S54), alarm information for alarming the deterioration of the amplifier 514 is generated in the RAM 1c in step S56. In step S57 (alarm information output means), the generated alarm information is output to the display unit 3 and the alarm unit 4, so that an alarm screen for alarming the deterioration of the amplifier 514 is displayed on the display unit 3. Then, an alarm using an alarm sound, voice, or the like is given by the alarm unit 4, and then the process ends.

  As is clear from the above description, the series of processing in steps S52 to S54 corresponds to the deterioration detecting means in the claims. Therefore, the CPU 1a functions as a flow rate measurement unit, a gain level detection unit, a history information generation unit, a deterioration detection unit, an alarm information generation unit, and an alarm information output unit described in the claims.

Next, an example of the operation (action) of the gas meter described above in the best mode according to the present invention will be described below.

  When the gas meter is activated, the up and down propagation times are measured several times for each sampling time, and the average is the propagation times tu and td at the sampling time, and the flow velocity and flow rate are calculated based on the propagation times tu and td. Is done. Then, the gain level of the amplifier 514 when the flow velocity and the flow rate are calculated is detected, and history information indicating the gain level and the corresponding flow rate is generated and stored in the history information storage area of the memory 9.

  Then, it is determined whether or not the gain level has changed by comparing the gain levels of the current history information and the previous history information. When the gain level is changed, the gain abnormality counter is updated. When the gain level is larger than the value of the gain abnormality counter, alarm information is generated and output. An alarm is given by the alarm unit 4 or the like.

  As described above, the gas meter stores in the memory 9 history information indicating a flow rate and a gain level corresponding to the flow rate, and monitors deterioration of the gain level based on history information having the same flow rate, and detects the deterioration. Since the alarm information is output to the power supply, the deterioration of the amplifier (amplifying unit) 514 can be recognized by referring the alarm information to a gas company or the like. Further, the gain level changes depending on the flow rate such that the gain level is low when the flow rate is small. However, since the deterioration is determined based on the history of the gain level corresponding to the same flow rate, the gain of the amplifier 514 Accurately capture changes over time in levels.

  Furthermore, when the history information is compared and the gain level is increased, it can be determined that the sensitivity of the ultrasonic wave has deteriorated. It is possible to make a gas company or the like recognize that there is a possibility of a decrease in measurement accuracy by judging and warning that it tends to be worse.

  Accordingly, since the gas business operator can confirm in advance the decrease in measurement accuracy due to the deterioration of the amplifier (amplifying means) 514, it is possible to perform early measures such as replacement of the amplifier 514 and level adjustment. It is possible to prevent a decrease in measurement accuracy. In addition, for the consumer, it is possible to avoid the occurrence of a long-term gas interruption period due to a decrease in measurement accuracy.

In the above-described best mode , the case where the deterioration of the amplifier 514 is detected based on the previous and current history information corresponding to a predetermined flow rate has been described. However, the present invention is not limited to this. Various embodiments can be made, such as detecting deterioration by analyzing a change amount and a change pattern of the gain level based on a plurality of past history information and current history information.

It is a figure which shows the basic composition of the fluid measuring device and gas meter which concern on this invention. It is a block diagram which shows an example of schematic structure of the gas meter of this invention. It is explanatory drawing which shows the effect | action of the structure of the sensor circuit part shown in FIG. 2, an ultrasonic transducer | vibrator, and an ultrasonic transducer | vibrator. It is a flowchart which shows an example of the gain log | history production | generation process which CPU of FIG. 2 performs. It is a flowchart which shows an example of the gain monitoring process which CPU of FIG. 2 performs.

Explanation of symbols

4 Alarm means (alarm unit)
5 Flow rate sensor (Ultrasonic flow rate sensor)
5a Amplification means (amplifier)
P1 Flow rate measuring means (CPU)
P2 Gain level detection means (CPU)
P3 History information generation means (CPU)
P4 Deterioration detection means (CPU)
P5 Alarm information generation means (CPU)
P6 Alarm information output means (CPU)

Claims (2)

A flow sensor for outputting a signal corresponding to the flow of the fluid; an amplifying means for amplifying the signal output from the flow sensor at an arbitrarily determined gain level; and a flow rate of the fluid based on the signal amplified by the amplifying means. In a fluid measurement device comprising a flow rate measuring means for measuring
A gain level detecting means for detecting a gain level of the amplifying means corresponding to the flow rate measured by the fluid measuring means;
History information generating means for generating history information indicating the flow rate measured by the flow rate measuring means and the gain level detected by the gain level detecting means corresponding to the flow rate;
History information storage means for storing history information generated by the history information generation means in time series;
Deterioration detecting means for detecting deterioration of the predetermined gain level based on history information having the same flow rate stored in the history information storage means;
Alarm information generating means for generating alarm information for alarming deterioration of the amplification means detected by the deterioration detection means;
Alarm information output means for outputting the alarm information generated by the alarm information generation means for the alarm;
A fluid measuring device comprising: A gas meter comprising the fluid measuring device according to claim 1 , wherein the gas meter measures a usage amount of the gas based on a flow rate of the gas measured by the fluid measuring device,
A gas meter comprising alarm means for performing an alarm based on alarm information output by the alarm information output means of the fluid measuring device.

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