JP5583365B2 - Ultrasonic gas meter and noise elimination method thereof - Google Patents

Description

  The present invention relates to an ultrasonic gas meter and a noise removal method thereof.

  Conventionally, 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 to measure the propagation time during which the ultrasonic signal propagates between the transducers, and the gas flow rate is intermittent based on the measured propagation time. Ask for.

JP 2008-51562 A

  Further, in an ultrasonic gas meter, the instrumental difference of the meter changes due to water intrusion. In such a case, since the flow rate value to be measured changes due to a change in the instrumental difference, the gas usage fee also changes, which is a problem in terms of fee. Here, intrusion of water may occur when a large amount of rainwater enters due to cracks in the piping and the water accumulates in the meter, and when the water accumulates in the piping, a gas with high humidity enters the ultrasonic gas meter. There are cases where water accumulates due to the condensation that is supplied.

  In particular, in the latter case, since water does not accumulate at a stretch, the state in which the instrumental difference has changed continues for a long time. For this reason, the problem on a charge tends to become remarkable. For these reasons, it is desired that condensation can be detected with high accuracy. Therefore, if a moisture sensor is provided to detect the ingress of water, not only the sensor cost is required, but also a sensor wiring seal structure is required, which further increases the cost.

  Therefore, it is desired that condensation can be accurately detected without providing a moisture sensor, but it is difficult to determine the condensation at present.

  The present invention has been made in order to solve such a conventional problem, and an object of the present invention is to provide an ultrasonic method capable of improving the determination accuracy of water intrusion due to condensation while suppressing cost. An object of the present invention is to provide a gas meter and a noise removal method thereof.

An ultrasonic gas meter according to the present invention includes a transmitting unit that intermittently transmits an ultrasonic signal in a gas flow path, a receiving unit that receives the ultrasonic signal, and a signal received by the receiving unit with a predetermined strength. Amplifying means for amplifying, a change factor specifying means for specifying a change factor that causes a change in the amplification degree by the amplifying means, and calculating the amplification factor for the change factor specified by the change factor specifying means as a noise component A noise component removing unit that removes the noise component from the amplification degree by the amplification unit; and a determination unit that determines the occurrence of condensation based on the corrected amplification degree from which the noise component has been removed by the noise component removing unit. Provided that the determination means causes condensation when the gas flow rate is zero and the correction gain does not change, and when the gas flow rate is not zero and the correction gain changes. Characterized in that to determine that.

According to this ultrasonic gas meter to identify the change factor resulting in a change in the amplification degree, and calculates the amplification factor of the identified change factor fraction as a noise component, to remove noise components from the amplification degree. For this reason, by removing the noise component of the amplification factor corresponding to the change factor, it is possible to accurately determine the dew condensation based on the corrected amplification factor after the removal. Accordingly, it is possible to improve the determination accuracy of water intrusion due to condensation while suppressing costs. Further, when the gas flow rate is zero and the correction amplification factor does not change, and when the gas flow rate is not zero and the correction amplification factor changes, it is determined that condensation has occurred. Here, when the gas flow rate to be measured is zero, the gas containing water vapor does not flow into the flow path, and water droplets do not adhere to the transmission means, the reception means, and their protective members. Therefore, the correction amplification degree does not change. On the other hand, when the measured gas flow rate is not zero, that is, when there is a certain flow rate, the gas containing water vapor flows into the flow path, and the water droplets adhering to the transmission means, the reception means, and their protective members increase. Accordingly, the correction amplification degree changes. Accordingly, it can be determined that condensation occurs in the above case.

  In the ultrasonic gas meter according to the present invention, it is preferable that the change factor specifying unit specifies the change factor as a mixed gas state when the amplification degree becomes stable after the fluctuation for a predetermined time.

  According to this ultrasonic gas meter, when the amplification level becomes stable after the fluctuation for a predetermined time, the change factor is specified as the mixed gas state. Here, in a mixed gas state in which gas and air are mixed, the propagation characteristics of ultrasonic waves are not stable, and the amplification becomes unstable. Therefore, there is a possibility of misjudging that it is condensation. However, the use of gas appliances causes the mixed gas to be discharged out of the gas meter, and the amplification level is stabilized. For this reason, the determination accuracy of dew condensation can be improved by specifying the change factor as the mixed gas state in the above case.

  In the ultrasonic gas meter of the present invention, it is preferable that the change factor specifying means specifies that the change factor is a temperature change when the ambient temperature has changed.

  According to this ultrasonic gas meter, when there is a change in the ambient temperature, the change factor is specified as a temperature change. Here, when the temperature changes, the gas expands and compresses, affecting the propagation characteristics of the ultrasonic wave and changing the amplification degree. For this reason, the determination accuracy of dew condensation can be improved by specifying the change factor as a change in the ambient temperature in the above case.

  In the ultrasonic gas meter of the present invention, it is preferable that the change factor specifying means specifies that the change factor is generation of a gas flow rate when a gas flow rate is generated.

  According to this ultrasonic gas meter, when a gas flow rate is generated, the change factor is specified as the gas flow rate. Here, when the flow velocity is increased, the propagation characteristics of ultrasonic waves are affected and the amplification degree is changed. For this reason, the determination accuracy of dew condensation can be improved by specifying the change factor as the gas flow rate in the above case.

  In the ultrasonic gas meter according to the present invention, the change factor specifying means may detect the change factor as dust when the amplification degree of the signal amplified to a predetermined intensity by the amplification means is different from the amplification degree at the same flow rate in the past. It is preferable to specify that it is an adhesion.

  According to this ultrasonic gas meter, when the amplification degree by the amplification means is different from the amplification degree at the same flow rate in the past, the change factor is specified as dust adhesion. Here, if dust adheres to and accumulates on the transmitting means and the receiving means and its protective member, the propagation characteristics of the ultrasonic waves are affected, and the amplification degree changes even if the flow velocity is the same. For this reason, the determination accuracy of dew condensation can be improved by specifying the change factor as dust adhesion in the above case.

  Further, in the ultrasonic gas meter according to the present invention, when the amplification degree of the signal amplified to a predetermined intensity by the amplification means has changed by a predetermined value or more within a specified time, a large amount of water has entered. It is preferable to judge that.

  According to this ultrasonic gas meter, it is determined that a large amount of water has entered when the degree of amplification changes by a predetermined value or more within a specified time. Here, when a large amount of water permeates, the water is accumulated in the flow path at once, and the change in the amplification degree tends to be relatively remarkable as compared with the case of dew condensation. Therefore, by determining that a large amount of water has entered in the above case, it is possible to determine not only dew condensation but also a large amount of water.

The noise removal method for an ultrasonic gas meter according to the present invention includes a transmission step of intermittently transmitting an ultrasonic signal in a gas flow path, a reception step of receiving the ultrasonic signal, and a reception step of receiving the ultrasonic signal. the signal amplification step of amplifying up to a predetermined strength, the said amplification degree in the amplification step and change factor specifying step of specifying a change factor resulting in a change amplification degree of the change factor component identified in the change factor specifying step Is generated as a noise component, and a noise component removing step of removing the noise component from the amplification degree in the amplification step, and the occurrence of condensation based on the corrected amplification degree from which the noise component has been removed in the noise component removal step A dew generation determination step for determining, wherein in the dew condensation generation determination step, the gas flow rate is zero, the correction amplification degree does not change, and the gas flow rate is zero. Wherein when the correction degree of amplification is changed in the absence, characterized in that it is determined that condensation has occurred.

According to the noise removing method of the ultrasonic gas meter to identify the change factor resulting in a change in the amplification degree, and calculates the amplification factor of the identified change factor fraction as a noise component, to remove noise components from the amplification degree. For this reason, by removing the noise component of the amplification factor corresponding to the change factor, it is possible to accurately determine the dew condensation based on the corrected amplification factor after the removal. Accordingly, it is possible to improve the determination accuracy of water intrusion due to condensation while suppressing costs. Further, when the gas flow rate is zero and the correction amplification factor does not change, and when the gas flow rate is not zero and the correction amplification factor changes, it is determined that condensation has occurred. Here, when the gas flow rate to be measured is zero, the gas containing water vapor does not flow into the flow path, and water droplets do not adhere to the transmission means, the reception means, and their protective members. Therefore, the correction amplification degree does not change. On the other hand, when the measured gas flow rate is not zero, that is, when there is a certain flow rate, the gas containing water vapor flows into the flow path, and the water droplets adhering to the transmission means, the reception means, and their protective members increase. Accordingly, the correction amplification degree changes. Accordingly, it can be determined that condensation occurs in the above case.

  According to the present invention, it is possible to improve the determination accuracy of water intrusion due to dew condensation while suppressing costs.

It is a lineblock diagram showing the ultrasonic gas meter concerning the embodiment of the present invention. FIG. 2 is a configuration diagram showing the inside of μCOM shown in FIG. 1. It is a flowchart which shows the noise removal method by the ultrasonic gas meter which concerns on this embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. FIG. 1 is a configuration diagram illustrating an ultrasonic gas meter according to an embodiment of the present invention. The ultrasonic gas meter 1 shown in FIG. 1 includes two acoustic transducers (disposed by a distance L in the gas flow path and opposed to each other so as to form an angle θ with respect to the gas flow direction Y). (Transmission means, reception means) TD1, TD2.

  The two acoustic transducers TD1, 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 both acoustic transducers TD1 and TD2.

  Each transducer TD1, TD2 is connected to a transmitter circuit 12 and a receiver circuit 13 via transducer interface (I / F) circuits 11a, 11b, respectively. The transmission circuit 12 intermittently transmits a signal for generating an ultrasonic signal by driving one of the transducers TD 1 and TD 2 under the control of the microcomputer (μCOM) 14.

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

  FIG. 2 is a block diagram showing the inside of the μCOM 14 shown in FIG. As shown in FIG. 2, the μCOM 14 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 programs for processes performed by the CPU 14a, and various types of CPU 14a. 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. These are connected to each other by a bus line 14d.

  The CPU 14a measures the gas flow rate based on the propagation times of the ultrasonic signals transmitted and received by the two transducers TD1 and TD2 at every sampling time, and instantaneously multiplies the measured gas flow rate by the cross-sectional area of the gas flow path. It has a measurement function that measures the flow rate. Furthermore, the CPU 14a according to the present embodiment has a determination function (determination means) for determining the occurrence of condensation in the flow path based on the amplification degree of the signal amplified to a predetermined strength by the amplifier 13a.

  Here, when water accumulates in the pipe, the following phenomenon occurs in the ultrasonic gas meter 1 depending on whether the gas is not supplied or the gas is supplied. First, when a gas containing water vapor is not supplied, the gas does not flow into the flow path, and water droplets do not adhere to the transducers TD1, TD and a protective member such as a mesh for protecting them. For this reason, the amplification degree by the amplifier 13a does not change. On the other hand, when a gas containing water vapor is supplied, water droplets adhere to the transducers TD1, TD and a protective member such as a mesh for protecting them, and the adhering water droplets gradually increase. For this reason, the amplification degree by the amplifier 13a tends to change.

  Therefore, the determination function can determine the occurrence of dew condensation by grasping the change characteristic of the amplification degree as described above. However, the amplification degree by the amplifier 13a varies not only due to the occurrence of condensation but also due to various factors. For this reason, even if it is attempted to determine the occurrence of condensation by the determination function, there is a possibility that an erroneous determination will occur due to a change in the amplification degree. Therefore, the CPU 14a according to the present embodiment includes a change factor specifying function (change factor specifying unit) and a noise component removing function (noise component removing unit).

  The change factor specifying function is a function for specifying a change factor (excluding the occurrence of condensation) that causes a change in the amplification degree. Here, for example, there are the following factors that cause a change in the degree of amplification. The first is a mixed gas state, the second is a temperature change, the third is a gas flow rate, and the fourth is dust adhesion.

  First, the first will be described. The mixed gas state is a state in which a mixed gas of gas and air is supplied into the ultrasonic gas meter 1. In the mixed gas state, the propagation characteristic of the ultrasonic signal becomes unstable and the amplification degree tends to fluctuate. For this reason, there is a possibility that it is erroneously determined that condensation has occurred.

  The second temperature change is a change in the environmental temperature at which the ultrasonic gas meter 1 is used. For example, when the environmental temperature in which the ultrasonic gas meter 1 is used changes from −30 ° C. to 60 ° C., the amplification degree changes by about “5”.

  The third gas flow rate is the flow rate of the gas supplied into the ultrasonic gas meter 1. When the gas flow rate increases, the propagation characteristics of the ultrasonic waves are affected and the amplification degree tends to change.

  The fourth dust adhesion means that dust and dirt adhere to the surfaces of the transducers TD1 and TD and their protective members. When dust adheres, the propagation characteristics of ultrasonic waves are affected and the amplification degree tends to change. Specifically, when dust adheres, the amplification degree gradually changes by 1 to 2 in one year.

  The change factor specifying function specifies these change factors as follows. First, the change factor specifying function determines that the change factor is a mixed gas state when the amplification degree becomes stable after a predetermined time (for example, 1-2 minutes). In the case of a mixed gas state, the amplification becomes unstable while the mixed gas is present in the ultrasonic gas meter 1, but when the gas appliance is used, the mixed gas is external to the ultrasonic gas meter 1. It tends to become stable after the discharge. Thereby, the ultrasonic gas meter 1 according to the present embodiment specifies the mixed gas state. The “stable state” is a concept including not only a state where the amplification degree does not change at all but also a case where the amplification degree changes within the second specified value.

  The change factor specifying function specifies that the change factor is a temperature change when the ambient temperature changes. At this time, the change factor specifying function receives, for example, a signal from a temperature sensor (not shown), and when there is a change in temperature calculated from the received signal, it determines that the temperature has changed and sets the change factor as a temperature. Judge that it is a change.

  As another method, since the degree of amplification changes due to a temperature change, it is determined that a change within a certain value (for example, ± 2) within a certain period (for example, 15 days) is a temperature change. The fixed value can be calculated from temperature fluctuation data within a fixed period (for example, 15 days).

  Further, the change factor specifying function determines that the change factor is the generation of the gas flow velocity when the gas flow velocity is generated. At this time, the change factor specifying function obtains the gas flow rate from the propagation time of the ultrasonic signals transmitted and received by the transducers TD1 and TD, and when the gas flow rate is generated, the change factor is the generation of the gas flow rate. to decide.

  The change factor specifying function specifies the change factor as dust adhesion when the amplification factor of the signal amplified to a predetermined strength by the amplifier 13a is different from the amplification factor at the same flow rate in the past. Prior to this identification, the change factor identification function stores the amplification degree together with the temperature obtained from the temperature sensor signal and the gas flow velocity obtained from the propagation time. The change factor specifying function compares the amplification factor at that time with the stored amplification factor when the condition of the same flow rate is satisfied after a certain period of time, and specifies the change factor as dust adhesion if different. .

  As described above, the change factor specifying function specifies a change factor without causing a change in the amplification degree. The noise component removal function calculates an amplification factor based on the change factor specified by the change factor specification function as a noise component, and removes the noise component from the amplification factor by the amplifier 13a.

  More specifically, when the change factor is a mixed gas state, it can be said that the change in the amplification degree is brought about by the mixed gas until the amplification degree reaches a stable state. Therefore, when it is determined that the change factor is the mixed gas state, the noise component removal function determines that the amplification factor up to the stable state is a noise component, and removes (cancels) the noise component. Then, the correction amplification degree is calculated by removing the noise component.

When the change factor is a temperature change, the noise component removal function calculates the amount of change in the amplification degree due to the temperature change, and determines the calculated change amount as the noise component. Then, the noise component removal function removes the noise component from the amplification degree by the amplifier 13a and obtains the correction amplification degree.
Further, the noise component removal function calculates the amount of change in the amplification degree due to the gas flow rate and non-dust adhesion similarly when the change factor is the gas flow rate and dust adhesion, and uses the calculated change amount as a noise component in the amplifier 13a. Remove from amplification by Thereby, the noise component removal function obtains the correction amplification degree.

  When the noise component removal function obtains the correction amplification degree, the determination function determines the occurrence of condensation based on the change characteristic of the correction amplification degree. As described above, when the gas containing water vapor is not supplied, the gas does not flow into the flow path, and water droplets do not adhere to the transducers TD1, TD and the protective member such as a mesh for protecting them. For this reason, the amplification degree by the amplifier 13a does not change. On the other hand, when a gas containing water vapor is supplied, water droplets adhere to the transducers TD1, TD and a protective member such as a mesh for protecting them, and the adhering water droplets gradually increase. For this reason, the amplification degree by the amplifier 13a tends to change. Therefore, the determination function determines that condensation has occurred when the gas flow rate is zero and the correction amplification factor does not change and when the gas flow rate is not zero and the correction amplification factor changes. This can reduce the possibility of misjudgment of the occurrence of condensation due to the mixed gas state, temperature change, gas flow rate, and dust adhesion.

  Furthermore, the determination function determines not only water intrusion due to condensation but also large amount of water intrusion. Here, if a large amount of water permeates, the water will be collected in the flow path at once, and the change in the amplification becomes relatively more remarkable than in the case of dew condensation. Therefore, the determination function determines that a large amount of water has infiltrated when the amplification degree changes by a predetermined value or more within a specified time. Thereby, the ultrasonic gas meter 1 according to the present embodiment can detect not only condensation but also a large amount of water intrusion.

  Next, a noise removal method using the ultrasonic gas meter 1 according to the present embodiment will be described. FIG. 3 is a flowchart showing a noise removal method by the ultrasonic gas meter 1 according to the present embodiment. First, the determination function of the CPU 14a determines whether or not the amplification degree has changed by a predetermined value or more within a specified time (S1).

  When it is determined that the amplification degree has changed by a predetermined value or more within the specified time (S1: YES), the determination function determines that a large amount of water has entered the flow path of the ultrasonic gas meter 1 (S2), and FIG. The process shown ends. Since a large amount of water has entered, the ultrasonic gas meter 1 performs a security process. That is, the ultrasonic gas meter 1 closes the shut-off valve 10 or notifies the management center that a large amount of water has entered.

  On the other hand, when it is determined that the amplification level has not changed by a predetermined value or more within the specified time (S1: NO), it is determined whether or not the amplification level has become stable after the fluctuation for a predetermined time (S3). When it is determined that a stable state has been reached after a predetermined time fluctuation (S3: YES), the noise component removal function determines that a change in the amplification degree due to the mixed gas state has occurred, and calculates the change as a noise component. (S4). Thereafter, the process proceeds to step S5.

  When it is determined that the stable state has not been reached after a predetermined time fluctuation (S3: NO), the change factor specifying function determines whether or not there has been a temperature change (S5). If it is determined that there is no temperature change (S5: NO), the process proceeds to step S7. If it is determined that there has been a temperature change (S5: YES), the noise component removal function calculates the amount of change in amplification due to the temperature change, that is, the noise component (S6), and the process proceeds to step S7.

  Thereafter, the change factor specifying function determines whether or not a gas flow rate is generated (S7). If it is determined that there is no gas flow rate (S7: NO), the process proceeds to step S9. If it is determined that there is a gas flow rate (S7: YES), the noise component removal function calculates the amount of change in the amplification factor due to the gas flow rate, that is, the noise component (S8), and the process proceeds to step S9.

  Next, it is determined whether the change factor specifying function is different from the amplification degree obtained at the same temperature and the same flow rate in the past (S9). If it is determined that it is not different from the amplification degree obtained at the same flow rate in the past (S9: NO), the process proceeds to step 11. When it is determined that the amplification degree is different from the amplification degree obtained at the same flow rate in the past (S9: YES), the noise component removal function calculates a change in amplification degree due to dust adhesion, that is, a noise component (S10), and the process is step S11. Migrate to

  In step S11, the noise component removal function removes the noise component calculated in steps S4, S6, S8, and S10 from the amplification degree by the amplifier 13a, and calculates a corrected amplification degree (S11). Then, the determination function determines whether or not the correction amplification factor changes when the gas flow rate is zero and the correction amplification factor does not change and the gas flow rate is not zero (S12).

  If it is determined that the correction amplification factor does not change when the gas flow rate is zero or the correction amplification factor does not change when the gas flow rate is not zero (S12: NO), the processing shown in FIG. 3 ends. If it is determined that the correction amplification factor is changed when the gas flow rate is zero and the correction amplification factor is not changed, and the gas flow rate is not zero (S12: YES), the determination function determines that condensation has occurred (S12: YES). S13). Thereafter, the process shown in FIG. 3 ends. Since a large amount of water has entered, the ultrasonic gas meter 1 may perform a security process. That is, the ultrasonic gas meter 1 closes the shut-off valve 10 or notifies the management center that a large amount of water has entered.

  Thus, according to the ultrasonic gas meter 1 and the noise removal method thereof according to the present embodiment, a change factor that causes a change in the amplification factor is specified, and the amplification factor based on the specified change factor is calculated as a noise component. Then, the noise component is removed from the amplification degree. For this reason, by removing the noise component of the amplification degree based on the change factor, it becomes possible to accurately determine the dew condensation based on the amplification degree after the removal. Accordingly, it is possible to improve the determination accuracy of water intrusion due to condensation while suppressing costs.

  Further, when the amplification degree becomes stable after changing for a predetermined time, the change factor is specified as the mixed gas state. Here, in a mixed gas state in which gas and air are mixed, the propagation characteristics of ultrasonic waves are not stable, and the amplification becomes unstable. Therefore, there is a possibility of misjudging that it is condensation. However, the use of gas appliances causes the mixed gas to be discharged out of the gas meter, and the amplification level is stabilized. For this reason, the determination accuracy of dew condensation can be improved by specifying the change factor as the mixed gas state in the above case.

  When the ambient temperature changes, the change factor is specified as a temperature change. Here, when the temperature changes, the gas expands and compresses, affecting the propagation characteristics of the ultrasonic wave and changing the amplification degree. For this reason, the determination accuracy of dew condensation can be improved by specifying the change factor as the change in the ambient temperature in the above case.

  When a gas flow rate is generated, the change factor is specified as the gas flow rate. Here, when the flow velocity is increased, the propagation characteristics of ultrasonic waves are affected and the amplification degree is changed. For this reason, the determination accuracy of dew condensation can be improved by specifying the change factor as the gas flow rate in the above case.

  When the amplification degree by the amplifier 13a is different from the amplification degree at the same flow rate in the past, the change factor is specified as dust adhesion. Here, if dust adheres to and accumulates on the transducers TD1 and TD2 and their protective members, the propagation characteristics of the ultrasonic waves are affected, and the amplification degree changes even at the same flow rate. For this reason, the determination accuracy of dew condensation can be improved by specifying the change factor as dust adhesion in the above case.

  Further, when the gas flow rate is zero and the correction amplification factor does not change, and when the gas flow rate is not zero and the correction amplification factor changes, it is determined that condensation has occurred. Here, when the measured gas flow rate is zero, the gas containing water vapor does not flow into the flow path, and water droplets do not adhere to the transducers TD1, TD2, their protective members, and the like. Therefore, the correction amplification degree does not change. On the other hand, when the measured gas flow rate is not zero, that is, when there is a certain flow rate, a gas containing water vapor flows into the flow path, and water droplets adhering to the transducers TD1, TD2, their protective members, and the like increase. Accordingly, the correction amplification degree changes. Accordingly, it can be determined that condensation occurs in the above case.

  Further, when the amplification degree changes by a predetermined value or more within the specified time, it is determined that a large amount of water has entered. Here, when a large amount of water permeates, the water is accumulated in the flow path at once, and the change in the amplification degree tends to be relatively remarkable as compared with the case of dew condensation. Therefore, by determining that a large amount of water has entered in the above case, it is possible to determine not only dew condensation but also a large amount of water.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above embodiment, and may be modified without departing from the gist of the present invention. For example, in the ultrasonic gas meter 1 according to the present embodiment, the corrected amplification factor is obtained by removing the noise component in the mixed gas state. However, the invention is not limited to this, and the corrected amplification factor is obtained in the mixed gas state. It may be determined that the condensation does not occur immediately without calculating and the process may be terminated.

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic gas meter 10 ... Gas cutoff valve 11a, 11b ... Transducer I / F circuit 12 ... Transmission circuit 13 ... Reception circuit 13a ... Amplifier (amplification means)
14 ... μCOM
14a ... CPU (determination means, change factor identification means, noise component removal means)
14b ... ROM
14b ... RAM
14b ... bus line 15 ... displays TD1, TD2 ... transducer (transmitting means, receiving means)

Claims (7)

Transmission means for intermittently transmitting ultrasonic signals in the gas flow path;
Receiving means for receiving the ultrasonic signal;
Amplifying means for amplifying the signal received by the receiving means to a predetermined strength;
Change factor specifying means for specifying a change factor that causes a change in the degree of amplification by the amplification means;
Calculating a degree of amplification of the change factor specified by the change factor specifying unit as a noise component, and a noise component removing unit for removing the noise component from the amplification by the amplification unit;
Determination means for determining the occurrence of condensation based on the correction amplification degree from which the noise component has been removed by the noise component removal means,
The determination means determines that condensation has occurred when the correction amplification factor changes when the gas flow rate is zero and the correction amplification factor does not change and when the gas flow rate is not zero.
An ultrasonic gas meter characterized by that. 2. The ultrasonic gas meter according to claim 1, wherein the change factor specifying unit specifies the change factor as a mixed gas state when the amplification level becomes stable after the fluctuation for a predetermined time. 2. The ultrasonic gas meter according to claim 1, wherein when the ambient temperature changes, the change factor specifying unit specifies the change factor as a temperature change. 2. The ultrasonic gas meter according to claim 1, wherein when the gas flow rate is generated, the change factor specifying unit specifies the change factor as generation of a gas flow rate. The change factor specifying means specifies the change factor as dust adhesion when the amplification degree of the signal amplified to a predetermined intensity by the amplification means is different from the amplification degree at the same flow rate in the past. The ultrasonic gas meter according to claim 1. The determining means is within a specified time, when the amplification degree of the amplified signal to a predetermined intensity by the amplifying means is changed more than a predetermined value, according to claim 1, characterized by determining that a large amount of water intrudes The ultrasonic gas meter according to 1. A transmission step of intermittently transmitting an ultrasonic signal in the gas flow path;
Receiving the ultrasonic signal; and
An amplification step of amplifying the signal received in the reception step to a predetermined strength;
A change factor specifying step for specifying a change factor that causes a change in the amplification degree in the amplification step ;
Calculating the amplification factor for the change factor specified in the change factor specifying step as a noise component, and removing the noise component from the amplification factor in the amplification step;
A dew generation determination step of determining the occurrence of dew condensation based on the corrected amplification degree from which the noise component has been removed in the noise component removal step,
In the dew generation determination step, it is determined that dew condensation has occurred when the correction amplification factor changes when the gas flow rate is zero and the correction amplification factor does not change and the gas flow rate is not zero.
A method for removing noise from an ultrasonic gas meter.

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