JP5649476B2 - Ultrasonic flow meter - Google Patents

Description

  The present invention relates to an ultrasonic flow meter, and more particularly to an ultrasonic flow meter capable of detecting noise.

  An ultrasonic flowmeter has a pair of ultrasonic transmitter / receiver units spaced upstream and downstream of the flow through which the fluid passes, and has the same ultrasonic forward propagation time as the fluid flow, The flow velocity is obtained from the propagation time of ultrasonic waves in the opposite direction to the flow, and the flow rate is obtained by multiplying the flow velocity by the cross-sectional area of the flow path.

  By the way, when filth such as oil mist adheres to the ultrasonic flow meter, the received wave is attenuated, and noise derived from the ultrasonic flow meter (hereinafter referred to as “casing noise”) may be generated. Are known. In addition, when a throttling mechanism such as a pressure reducing valve or a half-open valve is installed near the upstream or downstream of the ultrasonic flowmeter, an ultrasonic wave (hereinafter referred to as an ultrasonic wave different from the ultrasonic wave generated in the pipe for measuring the flow rate). , Referred to as “pipe noise”) and is superimposed on the received wave as noise.

  The ultrasonic flowmeter can determine the flow rate if the received wave can be detected even when noise is superimposed on the received wave or when the received wave is attenuated. However, if noise occurs at a position that coincides in time, the noise is superimposed on the received wave, and the flow rate is obtained based on the received wave on which the noise is superimposed, and an error may occur depending on the degree of noise. In addition, when noise that cannot be detected by the received wave is superimposed and the received wave is excessively attenuated / amplified, the propagation time of the ultrasonic wave cannot be measured (hereinafter referred to as “unmeasurable state”).

  In Patent Document 1, an ultrasonic propagation time at the time of normal measurement set in advance and an actually measured propagation time are compared, and if there is a difference of a predetermined magnitude or more, it is determined as an erroneous measurement. An ultrasonic flow meter is disclosed. Patent Document 2 discloses a flow rate measuring device that determines that noise is generated when a received wave is detected outside a sampling period in which the received wave is detected. Patent Document 3 discloses a device that stores the amplification factor amplified in order to detect the received wave, and analyzes the stored amplification factor, thereby narrowing down when the abnormality started to occur.

JP 2001-183195 A JP 2004-108831 A JP 2005-257445 A

  In the devices as disclosed in Patent Documents 1 and 2, there may be a case where detection is not possible even if noise occurs. In addition, even if noise is detected or measurement is disabled, the inside of the device cannot be immediately checked when the device is installed, and whether the cause of the noise is related to the housing or piping noise. Since it is unknown whether it is missing or decaying, it cannot be dealt with immediately.

  In the apparatus disclosed in Patent Document 3, since it is determined whether noise has occurred after a certain period of time has elapsed, it is not possible to determine the occurrence of noise when noise occurs.

  This invention is made | formed in view of the said subject, and makes it the subject which should be solved to provide the ultrasonic flowmeter which can detect the presence or absence of noise more accurately than the conventional noise detection.

The structural feature of the invention according to claim 1 for solving the above problem is that a pair of ultrasonic transducers arranged opposite to each other upstream and downstream of a passage through which a fluid passes are disposed, An ultrasonic flowmeter that obtains the flow rate from the arrival time of the ultrasonic wave,
A received wave detection unit that outputs a received wave detection signal when it is determined that a received wave received by the ultrasonic wave receiver has received the ultrasonic wave output from the ultrasonic wave transmitter. When,
A level detection unit having a noise detection level generating unit that generates a noise detection level and a level exceeding comparison unit that outputs a noise level exceeded signal when the received wave exceeds the noise detection level;
A noise detection time calculation unit for obtaining a noise detection time, using the time when the noise level exceeded signal is output as a start point or an end point;
A noise determination unit that outputs a noise generation signal when the noise detection time is out of a normal range; and
It is to have.

Further, the structural feature of the invention according to claim 2 is that in claim 1, when the output of the ultrasonic wave is performed a plurality of times,
The noise generation signal output by the noise determination unit is a case when the noise type determination time, which is the value of the noise detection time obtained in the previous measurement, and the value of the noise detection time are the same. A signal representing noise,
In other cases, the signal represents the pipe noise.

According to a third aspect of the present invention, the noise detection time according to the first or second aspect is a time from when the signal exceeding the noise level is output to when the received wave detection signal is output. And
It is determined that the noise detection time is longer than a set value when it is determined that the normal range is not satisfied.
The set value is assumed to be a time from when the ultrasonic wave output from the ultrasonic wave transmitter starts to be detected by the ultrasonic wave receiver to when the received wave detection signal is output. It is to be set in more than the time.

  Here, the time when detection is started by the ultrasonic wave receiver and the time when the reception wave detection signal is output differ depending on the detection method of the reception wave used.

According to a fourth aspect of the present invention, in the first or second aspect, the noise detection time is a time from when the noise level exceeded signal is output to when the received wave detection signal is output. And
It is determined that the noise detection time is out of the normal range when the noise detection time is equal to or shorter than the length of one period of the received wave or equal to or longer than the length of two periods.

According to a fifth aspect of the present invention, in the first or second aspect of the invention, the noise detection time outputs the noise level exceeded signal from the time when the ultrasonic transmitter outputs the ultrasonic wave. Is the time until
It is determined that the noise detection time is shorter than a set value when it is determined that the normal range is deviated.
The set value is set within a time that is assumed to be a time when the ultrasonic wave receiver starts to be detected after the ultrasonic wave is output from the ultrasonic wave transmitter.

Further, according to a sixth aspect of the present invention, in any one of the first to fifth aspects, the actual amplification factor of the received wave can be appropriately adjusted according to the amplitude of the received wave. An amplification unit;
Temperature measuring means for measuring the temperature of the fluid and outputting the measured temperature;
Pressure measuring means for measuring the pressure of the fluid and outputting the measured pressure;
The noise determination unit is configured when the difference between an appropriate theoretical amplification factor determined by a combination of the fluid type, the measurement temperature, and the measurement pressure is greater than or equal to a predetermined value, or the actual amplification factor. When a difference between the estimated temperature and estimated pressure of the fluid estimated from the above and the measured temperature and measured pressure is equal to or greater than a predetermined value, a noise generation signal is output.

In addition, the structural feature of the invention according to claim 7 for solving the above-described problem is that a set of ultrasonic transducers arranged opposite to the upstream and downstream of the passage through which the fluid passes are arranged, An ultrasonic flowmeter having an amplifying unit capable of appropriately adjusting the actual amplification factor of the received wave according to the amplitude of the received wave, and obtaining a flow rate from the arrival time of the ultrasonic wave between the ultrasonic transducers Because
A received wave detection unit that outputs a received wave detection signal when it is determined that a received wave received by the ultrasonic wave receiver has received the ultrasonic wave output from the ultrasonic wave transmitter. When,
Temperature measuring means for measuring the temperature of the fluid and outputting the measured temperature;
Pressure measuring means for measuring the pressure of the fluid and outputting the measured pressure;
The fluid estimated when the difference between an appropriate theoretical amplification factor determined by a combination of the fluid type, the measurement temperature, and the measurement pressure is greater than or equal to a predetermined value, or from the actual amplification factor A noise determination unit that outputs a noise generation signal when the difference between the estimated temperature and the estimated pressure and the measured temperature and the measured pressure is equal to or greater than a predetermined value;
It is to have.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, the theoretical amplification factor is stored in a database for each combination of the fluid type, the fluid temperature, and the fluid pressure. Has been
The database receives the temperature of the fluid from the temperature measuring unit and the pressure of the fluid from the pressure measuring unit, and outputs the stored theoretical amplification factor each time the ultrasonic wave is output. It is to be.

  In the invention according to claim 1, when the noise detection level generation unit generates the noise detection level and the received wave exceeds the noise detection level, the level excess comparison unit outputs a noise level excess signal. The noise determination unit outputs a noise generation signal when the noise detection time obtained based on the time when the noise level exceeded signal is output is out of the normal range.

  Although the magnitude of the received wave varies depending on the type, pressure, and temperature of the fluid, the wave shape (relative relationship between the waves, see FIG. 4) has the characteristic that it does not change. If it is known in advance, a normal range can be set because a time range in which a received wave is detected can be derived by a combination of pressure and temperature. Any method may be used to detect the received wave detection signal for calculating the arrival time of the ultrasonic wave. In the present application, “output a signal” may be any signal that can detect a signal such as an electric signal or an optical signal. Taking an electrical signal as an example, the change from a low voltage to a high voltage, a change from a high voltage to a low voltage, or what was being output is no longer output. However, if it can be detected, “output a signal”. According to the first aspect of the present invention, it is possible to accurately detect noise that could not be detected in the past by appropriately setting the noise detection level value and the normal range.

  In the invention according to claim 2, the noise determination unit compares the noise detection time with the noise type determination time to determine whether the generated noise is the housing noise related to the housing or the piping noise related to the piping. Can be determined. Here, the housing noise is noise derived from the ultrasonic flowmeter, the piping noise is noise not derived from the ultrasonic flowmeter, and the noise type determination time is the value of the previous noise detection time. . Piping noise derived from an ultrasonic flowmeter is noise generated when the ultrasonic wave output from the ultrasonic transmitter propagates through the housing (ultrasonic flowmeter), and is normally designed not to occur. It is designed to be excluded even if it occurs. However, noise is generated when the balance is lost due to adhesion of dirt. Case noise propagates in the case faster than anything, and once generated, propagates almost the same time every time. Therefore, on the premise of measuring the flow rate by performing ultrasonic output multiple times, the noise detection time value obtained in the previous measurement is stored as the noise type determination time, so that the next detected noise And the generation time of the noise generated one time before can be specified. Therefore, the noise generation signal is a signal representing the housing noise when the noise detection time is equal to the noise type determination time, and the other is a signal representing the piping noise. Note that being equal is not necessarily an equal sign and can have some width. According to the invention which concerns on Claim 2, the kind and cause of the noise which have generate | occur | produced can be specified.

  In the invention according to claim 3, the time for noise detection is the time from when the signal exceeding the noise level is output to when the received wave detection signal is output. Although the magnitude of the received wave changes depending on the type of fluid, pressure, and temperature, the wave shape (relative relationship between each wave, see FIG. 4) has the characteristic that it does not change. It can be assumed the time from the start of detection of the received wave until the reception wave detection signal is output. Therefore, by setting the normal range to be longer than the expected time, if noise is generated, the noise level will be output earlier than when the ultrasonic wave starts to be detected. Is longer than the set time. Therefore, the noise determination unit determines that noise is generated when the time for noise detection is longer than the set time. The normal range can be set in advance, or can be set based on a normal measurement value when the received wave can be detected normally. According to the invention of claim 3, noise can be detected even when the fluid used in the ultrasonic flowmeter is unknown by using the waveform characteristics of the received wave without considering the type of fluid. it can.

  In the invention which concerns on Claim 4, a normal range is set based on the period of a received wave. Since it has the characteristic that the shape of a received wave does not change as mentioned above, if the magnitude | size of a received wave is known, the length of one period of a received wave can be calculated | required. Therefore, when the noise detection time is equal to or shorter than the length of one cycle of the received wave or equal to or longer than the length of two cycles, it is determined that the normal range is out of range. According to the invention of claim 4, noise can be detected even when the fluid used in the ultrasonic flowmeter is unknown by using the waveform characteristics of the received wave without considering the type of fluid. it can.

  In the invention which concerns on Claim 5, the time for noise detection is the time from the time of outputting an ultrasonic wave to the time of receiving the signal exceeding a noise level. The time at which the ultrasonic wave begins to be detected can be derived based on the state (fluid temperature or pressure) obtained from the environment in which the type and flow rate of the fluid are measured. Therefore, by setting the normal range within a time shorter than the time when detection is started, that is, within the time expected to start detection, when noise is generated, it is earlier than when ultrasonic waves start being detected. Since a signal exceeding the noise level is output, the noise detection time is shorter than the set time. Therefore, the noise determination unit determines that noise is occurring when the noise detection time is shorter than the set time. According to the invention which concerns on Claim 4, when the fluid used with an ultrasonic flowmeter is known, a noise can be detected.

  In the invention which concerns on Claim 6, a noise determination part compares the appropriate theoretical amplification factor determined from the kind of fluid, temperature, and pressure, and the actual amplification factor which the amplification part actually adjusted the received wave. Thus, it is determined whether or not noise is generated. Alternatively, the presence or absence of noise is determined by comparing the temperature and pressure of the fluid estimated from the actual amplification factor with the temperature and pressure obtained by the measuring means. Here, the appropriate theoretical amplification factor is a rate for adjusting to a predetermined amplitude. The fact that the actual amplification factor is too different from the theoretical amplification factor, or that the fluid temperature and pressure estimated from the actual amplification factor actually differs greatly from the actually measured temperature and pressure. It can be said that there is a cause that the reception wave is attenuated. In order to calculate the theoretical amplification factor and to estimate the temperature and pressure of the fluid from the actual amplification factor, it is desirable to know the fluid to be used in advance. Therefore, according to the invention of claim 5, when the noise is superimposed at the same position in time and the magnitude of the received wave is apparently increased, or when the received wave is attenuated due to dirt, etc. In addition, even when the generation of noise cannot be detected based on the noise detection time, the noise can be detected.

  In the invention which concerns on Claim 7, a noise determination part compares the exact theoretical amplification factor determined from the kind of fluid, temperature, and pressure, and the actual amplification factor which the amplification part actually adjusted the received wave. Thus, it is determined whether or not noise is generated. Alternatively, the presence or absence of noise is determined by comparing the temperature and pressure of the fluid estimated from the actual amplification factor with the temperature and pressure obtained by the measuring means. The fact that the actual amplification factor is too different from the theoretical amplification factor, or that the fluid temperature and pressure estimated from the actual amplification factor actually differs greatly from the actually measured temperature and pressure. It can be said that there is a cause that the reception wave is attenuated. In order to calculate the theoretical amplification factor and to estimate the temperature and pressure of the fluid from the actual amplification factor, it is desirable to know the fluid to be used in advance. Therefore, when noise is superimposed at the same position in time and the magnitude of the received wave is apparently increased, or when the received wave is attenuated due to dirt or the like, the noise is detected based on the noise detection time. Even when it is impossible to detect occurrence of noise, noise can be detected.

In the invention according to claim 8, the theoretical amplification factor can be stored in the database for each combination of fluid type, temperature, and pressure. The database can output the theoretical amplification factor of the combination of the used fluid and the measured temperature and pressure to the noise determination unit.

It is a block diagram which shows the block diagram of the ultrasonic flowmeter 11 of this Embodiment 1. FIG. FIG. 3 is a block diagram illustrating configurations of a reception wave detection unit 3 and a level excess detection unit 4 that are used in the ultrasonic flowmeter 11 of the first embodiment. It is a timing chart for demonstrating the method the ultrasonic flowmeter 11 of this Embodiment 1 detects a received wave. It is a wave form diagram which shows an example of the received wave which the ultrasonic flowmeter 11 of this Embodiment 1 receives. It is the flowchart which showed an example of the flow which the ultrasonic flowmeter 11 of this Embodiment 1 detects generation | occurrence | production of noise. It is a timing chart which shows an example in which the ultrasonic flowmeter 11 of this Embodiment 1 detects noise. It is a timing chart which shows an example in which the ultrasonic flowmeter 11 of this Embodiment 1 detects noise. It is the flowchart which showed an example of the flow which the ultrasonic flowmeter of this Embodiment 2 detects generation | occurrence | production of noise. It is a timing chart which shows an example in which the ultrasonic flowmeter of this Embodiment 2 detects noise. It is a timing chart which shows an example in which the ultrasonic flowmeter of this Embodiment 2 detects noise. It is a block diagram which shows the block diagram of the ultrasonic flowmeter 13 of this Embodiment 3. FIG. It is the flowchart which showed an example of the flow which the ultrasonic flowmeter 13 of this Embodiment 3 detects generation | occurrence | production of noise. It is explanatory drawing which showed an example in which the ultrasonic flowmeter 13 of this Embodiment 3 detects noise.

  A representative embodiment of the present invention will be described with reference to FIGS. The ultrasonic flowmeter of the present invention is attached in the middle of a pipeline (not shown) through which gas or liquid flows.

(Embodiment 1)
As shown in FIG. 1, the ultrasonic flowmeter 11 of the first embodiment includes ultrasonic transducers 21 and 22, a received wave detection unit 3, a level excess detection unit 4, a noise determination unit 5, And a noise check counter (noise detection time calculation unit) 6. The ultrasonic flow meter 11 further includes a control unit 23, changeover switches S1 and S2, a transmitter / receiver drive unit 24, a counter 25, an amplification unit 26, a reference clock generation unit 27, and a noise generation notification unit 28. Have

  The ultrasonic transducers 21 and 22 are composed of a pair of ultrasonic transducers, and are disposed opposite to the upstream and downstream in the pipeline through which the fluid to be measured flows, one of which is upstream and the other is downstream. Located in. The ultrasonic transducers 21 and 22 can be operated on both the transmission side and the reception side, and the transmitter / receiver moving unit 24 or the reception wave detecting unit 3 (through the amplification unit 26) is switched via the changeover switches S1 and S2. Connected to transmit and receive ultrasonic waves in the fluid from upstream to downstream and from downstream to upstream. When the change-over switches S1 and S2 are in the state shown in FIG. 1, the ultrasonic transducers 21 and 22 are connected to the transducer drive unit 24 and operate as a transducer. The sonic transducer 22 is connected to the received wave detector 3 (via the amplifier 26) and operates as a receiver.

  For example, when the receiver 22 detects the ultrasonic wave output from the transmitter 21, the received wave detector 3 outputs a received wave detection signal. A method for outputting a reception wave signal (detection of a reception wave) will be described later.

  The control unit 23 switches transmission / reception of the ultrasonic transducers 21 and 22 at regular time intervals, and then outputs a start signal for each switching. Switching between transmission and reception is performed by switching the selector switches S1 and S2 with a transmission / reception switching signal from the control unit 23. When the reception wave detection signal from the reception wave detection unit 3 is input, the control unit 23 reads the measurement time measured by the counter 25 described later, and uses the measurement time in the opposite direction performed immediately before. The flow rate between the acoustic transducers is calculated, and the flow rate can be obtained from the calculated flow rate and the cross-sectional area of the pipe.

  When receiving the start signal output from the control unit 23, the transmitter / receiver driving unit 24 drives the ultrasonic transducer 21 (22) on the transmission side.

  The counter 25 measures the time from the start signal to the received wave detection signal. The control unit 23 reads the measured time. In this embodiment, the time is measured after the measurement time is reset by the start signal. The counter 25 measures time by counting the clocks from the reference clock generator 27.

  As shown in FIG. 2, the received wave detection unit 3 includes a reference level generation unit 31, a level selection unit 32, a comparison unit 33, and a zero cross detection unit 34.

  The reference level generation unit 31 outputs a plurality of reference levels of different voltages, for example, five reference levels Vthj1 to Vthj5 and inputs them to the level selection unit 32. For the five reference levels Vthj1 to Vthj5, for example, voltages are determined so as to be arranged exponentially (see FIG. 3). The level selection unit 32 selects a predetermined number, which is the smaller one of the plurality of reference levels output from the reference level generation unit 31, that is, three reference levels Vthj1 to Vthj3 in this embodiment, and outputs them to the comparison unit 33. The level selection unit 32 selects a predetermined number, for example, three reference levels from the smaller one for each transmission (every transmission) of the ultrasonic transducer on the transmission side, and outputs it to the comparison unit 33. The received wave is received by the receiver 22 (21), amplified by the amplifying unit 26, and then input to the comparison unit 33 and the zero cross detection unit 34 of the received wave detection unit 3. The received wave is sequentially compared with the selected reference levels Vthj1 to Vthj3 by the comparison unit 33.

  When the received wave (waveform) after amplification and the reference level are shown in FIG. 3, the second wave exceeds the minimum reference level Vthj1 at point a1, but does not exceed the two reference levels Vthj2 and Vthj3. The comparison unit 12 outputs to the zero cross detection unit 34 that a wave exceeding Vthj1 but not exceeding two Vthj2 and Vthj3 is detected at the point a1, and the zero cross detection unit 34 detects the zero cross point c1 of the second wave. Then, the zero cross point c1 is output to the level selection unit 32 as a zero cross detection signal. The comparison unit 33 outputs the point a1 to the level selection unit 32. Next, instead of the reference level Vthj1 beyond the second wave, the minimum reference level among the reference levels Vthj4 to Vthj5 that have not been selected so far is selected by the level selection unit 32 and output to the comparison unit 32. The

  Before the next wave is input to the comparison unit 33, a smaller predetermined number (three in this case) of reference levels Vthj2 to Vthj4 out of the remaining reference levels Vthj2 to Vthj5 excluding Vthj1 is input. Wait for the next wave. When any of the next waves immediately exceeds the reference levels Vthj2 to Vthj4, the comparison unit 33 outputs to the zero cross detection unit 34 that the wave has been detected. The zero-cross detection unit 34 detects a point c2 where the wave next zero-crosses, and outputs a received wave detection signal assuming that the wave is a zero-cross point.

  As illustrated in FIG. 2, the level excess detection unit 4 includes a noise detection level generation unit 41 and a level excess comparison unit 42. The noise detection level generation unit 41 generates a noise detection level Vthk smaller than the minimum level among the reference levels output by the reference level generation unit 31 of the received wave detection unit 3. The level excess comparison unit 42 outputs a noise level excess signal when the received wave exceeds the noise detection level.

  Returning to FIG. 1, when the noise confirmation counter 6 receives a noise level excess signal from the level excess detection unit 4, the noise detection time from when the noise level excess signal is output to when the received wave detection signal is output. (T1) is calculated. In calculating T1, when a signal exceeding the noise level is output and when a reception wave detection signal is output, it is reset when the start signal output from the control unit 23 is received, and the clock from the reference clock generation unit 27 is counted. Measure time. Then, the noise check counter 6 outputs the calculated T1 to the noise determination unit 5 described later.

  The noise determination unit 5 compares T1 input from the noise check counter 6 with the time range (Tx), and outputs a noise generation signal to the noise generation notification unit 28 when noise is generated. As shown in FIG. 4, Tx can be 1 × T0 <Tx <2 × T0 when one period of the received waveform is T0. That is, Tx is a value set with a magnitude corresponding to one to two periods of the received wave, and is a normal range in which the received wave detection signal is detected. One period of the received waveform can be calculated if the amplification factor is set so that the amplitude is always the same or if the magnitude of the received wave is known.

  As shown in FIG. 5, the noise determination unit 5 determines whether T1 input from the noise check counter 6 is equal to or less than Tx. When T1 is equal to or less than Tx, no noise is generated. Therefore, after determining that T1 is normal, T1 is recorded as a noise type determination time T10. T10 is the previous value of T1. When T1 is larger than Tx, noise is generated, and it is further determined whether T1 is equal to or not equal to T10. When T1 is equal to T10, it is assumed that the noise is noise related to the housing, and a noise generation signal is output. When T1 is not equal to T10, the noise is regarded as noise related to the piping, and a noise generation signal is output. Note that the equality in the comparison of T1 and T10 can have some width. In addition, a lower limit may be set in the comparison between T1 and Tx.

  The noise occurrence notifying means 28 that has received the noise generation signal as being either the case or the piping noise notifies the administrator of the occurrence of noise including the type of noise by character display, sound, blinking, etc. Notify and record the monitoring device. The distinction of the type of noise can be notified by the displayed characters, the manner of sound generation, the type of sound, the way the lamp blinks, and the like.

  The noise determination unit 5 outputs a determination end signal to the control unit 23 after determining that it is normal or that noise is occurring. The control unit 23 that has received the determination end signal transmits a new start signal after confirming the completion of the flow measurement operation.

  Next, an example in which the ultrasonic flow meter 11 according to the first embodiment detects noise will be described with reference to FIGS. 6 and 7. 6 and 7, the passage of time is shown from the left to the right in the figure. 6 and 7, the received wave is a waveform having a subsequent amplitude described as the first wave. Therefore, the amplitude generated before the received wave shown in FIGS. 6 and 7 is noise. The noise in FIG. 6 has an amplitude smaller than the reference level Vthj1, and the noise in FIG. 7 has an amplitude larger than the reference level Vthj1.

  In the ultrasonic flowmeter 11 of the first embodiment, the noise in FIG. 6 exceeds the noise detection level that is smaller than the reference level Vthj1 at the point n1, and therefore the level excess detection unit 4 outputs a noise level excess signal. In the received wave detector 3, the second wave of the received wave exceeds the reference level Vthj1 at the point a1, and further, the received wave detection signal is received at the zero cross point c2 after the fourth wave exceeds the reference levels Vthj2 to Vthj4 at once. Output. The noise check counter 6 calculates a noise detection time T1 from the point n1 to the point c2 where the received wave detection signal is output. In FIG. 6, T1 is clearly below Tx. Therefore, the noise determination unit 5 outputs a noise generation signal to the noise generation notification unit 28 assuming that noise is generated. Here, if T1 is equal to the noise type determination time T10 (previous T1), the noise is a noise related to the casing, and if T1 is not equal to T10, a noise generation signal is output that is a noise related to the pipe.

  In the ultrasonic flow meter 11 of the first embodiment, the noise in FIG. 7 exceeds the noise detection level that is further smaller than the reference level Vthj1 at the point n2, so that the level excess detection unit 4 outputs a noise level excess signal. In the received wave detection unit 3, after the wave different from the noise detection level exceeds the reference level Vthj1, the fourth wave of the received wave exceeds the reference levels Vthj2 to Vthj4 at a stroke, and the received wave is detected at the zero cross point c3. Output a signal. The noise check counter 6 calculates a noise detection time T1 from the point n2 to the point c3 where the received wave detection signal is output. In FIG. 7, T1 clearly exceeds the range of Tx. Therefore, the noise determination unit 5 outputs a noise generation signal to the noise generation notification unit 28 assuming that noise is generated. Here, if T1 is equal to T10, the noise is noise related to the casing, and if T1 is not equal to T10, the noise is output related to piping.

  According to the prior art, the noise shown in FIG. 6 cannot be detected regardless of the state in which the noise is generated. Then, when the noise increases as shown in FIG. 7, it is detected for the first time that the noise is generated. Moreover, even if the state where noise is generated as shown in FIG. 7 can be detected from the abnormal flow rate value, it cannot be detected whether the noise is related to the housing or the noise related to the piping.

  According to the ultrasonic flow meter 11 of the first embodiment, even when the fluid to be used is unknown, the received wave waveform (relative relationship between the waves) does not change, so that the accuracy is higher than in the past. Well, the presence or absence of noise can be detected. In particular, in the first embodiment, the noise detection level is set based on a reference level for detecting a received wave, and noise can be detected effectively.

  Further, since it is possible to determine whether the noise is noise related to the casing or noise related to the piping, the cause of the noise can be known without removing the installation of the ultrasonic flowmeter 11 itself. That is, it is possible not only to avoid a state in which measurement is impossible, but also to take immediate measures such as arranging procurement of replacement parts and the ultrasonic flowmeter itself without removing the device.

(Embodiment 2)
The ultrasonic flowmeter according to the second embodiment has basically the same configuration and operational effects as the ultrasonic flowmeter 11 according to the first embodiment. The ultrasonic flowmeter according to the second embodiment is different from the ultrasonic flowmeter 11 according to the first embodiment in noise detection time and time range. Below, it demonstrates focusing on a different structure and an effect.

  When the noise confirmation counter 6 receives the noise level excess signal from the level excess detection unit 4, the noise detection counter 6 outputs a noise signal from when the start signal is output from the control unit 23 to when the noise level excess signal is output from the level excess detection unit 4. The service time T2 is measured. Then, T2 is output to the noise determination unit 5.

  The noise determination unit 5 compares T2 input from the noise check counter 6 with the time range Ts. The time range Ts is from the time when the start signal is output and the ultrasonic wave is output from the transmitter 21 (22) to the time when the received wave starts to be detected by the receiver 22 (21) and thereafter. It is. The time when the received wave starts to be detected by the receiver 22 (21) is the maximum sound speed and the supersonic speed among the sound speeds of the working fluid that can be calculated in advance from the maximum temperature and the maximum flow velocity in the usage environment of the ultrasonic flowmeter. It can be calculated from the distance between the ultrasonic transducers 21 and 22 of the sonic flow meter. Therefore, Ts is a time slightly earlier than the shortest time to a time thereafter. That is, Ts is set between the ultrasonic transducers 21 and 22 at a time earlier than the shortest time that the ultrasonic wave propagates when there is no noise from when the start signal is output from the control unit 23. . Therefore, when a received wave is detected at a time earlier than a time earlier than the shortest time during which the ultrasonic wave is propagated, noise is generated.

  As shown in FIG. 8, the noise determination unit 5 compares T2 input from the noise check counter 6 with Ts. When T2 is within the range of Ts, that is, when T2 is greater than Ts, no noise is generated, so it is determined as normal. Thereafter, T2 is recorded as the noise type determination time T20. T20 is the previous value of T2. When T2 is shorter than Ts, that is, when T2 is equal to or less than Ts, noise is generated, and it is further determined whether T2 is equal to or not equal to T20. When T2 is equal to T20, it is assumed that the noise is noise related to the housing, and a noise generation signal is output. When T2 is not equal to T20, the noise is assumed to be noise related to the piping, and a noise generation signal is output. Note that the equality in the comparison between T2 and T20 can have some width.

  As in the first embodiment, the noise notification unit 28 notifies the occurrence of noise by some means when a noise generation signal is input.

  An example in which the ultrasonic flowmeter of the second embodiment detects noise will be described with reference to FIGS. 9 and 10. In FIGS. 9 and 10, the diagrams show the passage of time from left to right. 9 and 10, the received wave is a waveform having a subsequent amplitude described as the first wave. Therefore, the amplitude generated before the received wave shown in FIGS. 9 and 10 is noise. The noise in FIG. 9 has an amplitude smaller than the reference level Vthj1, and the noise in FIG. 10 has an amplitude larger than the reference level Vthj1.

  In the ultrasonic flowmeter of the second embodiment, the noise in FIG. 9 exceeds the noise detection level at the point n3, so the level excess detection unit 4 outputs a noise level excess signal. The noise check counter 6 measures a noise detection time T2 from when the control unit 23 outputs a start signal until the level excess detection unit 4 outputs a noise level excess signal, and outputs T2 to the noise determination unit 5. . In FIG. 9, T2 is clearly smaller than Ts. Therefore, after determining whether T2 is equal to or not equal to T20, the noise determination unit 5 outputs a noise generation signal that is noise related to the casing or piping related noise to the noise generation notification unit 28.

  Next, in the case of the ultrasonic flow meter of the second embodiment, as shown in FIG. 10, noise exceeds the noise detection level at the point n4, and the level excess detection unit 4 outputs a noise level excess signal. The noise check counter 6 measures a noise detection time T2 from when the control unit 23 outputs a start signal until the level excess detection unit 4 outputs a noise level excess signal, and outputs T2 to the noise determination unit 5. . In FIG. 9, T2 is clearly smaller than Ts. Therefore, after determining whether T2 is equal to or not equal to T20, the noise determination unit 5 outputs a noise generation signal to the noise generation notification unit 28 as to whether the noise is noise related to the casing or noise related to piping.

  According to the ultrasonic flowmeter of the second embodiment, when the fluid to be used is known, it is possible to detect the presence or absence of noise with higher accuracy than conventional based on the state obtained from the environment for measuring the flow rate. It is also possible to determine whether the noise is noise related to the housing or noise related to the piping. In other words, it is possible to avoid the inability to measure, and it is possible to take immediate measures such as arranging the procurement of replacement parts and the ultrasonic flowmeter itself without removing the installation.

(Embodiment 3)
As shown in FIG. 11, the ultrasonic flowmeter 13 of Embodiment 3 includes ultrasonic transducers 21 and 22, an amplifying unit 26, a received wave detecting unit 3, a pressure measuring unit 71, and a temperature measuring unit 72. The database 73 and the noise determination unit 7 are included. The ultrasonic flowmeter 11 further includes a control unit 23, changeover switches S <b> 1 and S <b> 2, a transmitter / receiver driving unit 24, a counter 25, a reference clock generation unit 27, and noise generation notification means 28. The ultrasonic flowmeter 13 of the third embodiment does not have the level excess detection unit 4 and the noise check counter 6 that the ultrasonic flowmeter 11 of the first embodiment and the ultrasonic flowmeter of the second embodiment have, but the same. The component basically works the same. The following description will focus on the different parts.

  The pressure measuring means 71 measures the pressure value of the fluid being used. The temperature measuring means 72 measures the temperature value of the fluid being used. The database 73 stores a plurality of amplification factors determined by combinations of pressure values and temperature values for each type of fluid used. For example, as shown in Table 1, the database 73 is amplification factors determined by temperature and pressure conditions when the amplification factor at atmospheric pressure at a temperature of 20 ° C. is 1. The database 73 receives the pressure value and temperature value measured by the pressure measuring means 71 and the temperature measuring means 72 every time the control unit 23 outputs a start signal, and the type of fluid used, the pressure value, and the temperature value. Is output to the noise determination unit 7.

  The noise determination unit 7 receives the reception wave detection signal from the reception wave detection unit 3, the actual amplification factor from the amplification unit 26, and the theoretical amplification factor from the database 73, and determines whether noise has occurred. Specifically, as shown in FIG. 12, the noise determination unit 7 first receives an actual gain and determines whether a received wave signal has been received. If no received wave signal has been received, a command to change the actual gain is output to the control unit 23. The control unit 23, to which the command for changing the actual amplification factor is input, outputs the start signal again.

  When the noise determination unit 7 receives the received wave signal, the noise determination unit 7 receives the theoretical amplification factor and compares the actual amplification factor with the theoretical amplification factor. When the actual amplification factor and the theoretical amplification factor are equal, no noise is generated, and nothing is output or no noise is output to the control unit 23. When the actual amplification factor and the theoretical amplification factor are not equal, a noise generation signal is output to the noise generation notification means 28. The noise occurrence notifying means 28 notifies the occurrence of noise by characters, sounds, flashing, and the like. The comparison between the actual amplification factor and the theoretical amplification factor has some width x in the absolute value of the difference between the actual amplification factor and the theoretical amplification factor (| actual amplification factor−theoretical amplification factor | ≦ x).

  An example in which the ultrasonic flow meter 13 according to the third embodiment detects noise will be described with reference to FIG. Each waveform divided by a broken line shown in FIG. 13 represents a received wave. A, B, C, and D described as the actual amplification factor and the theoretical amplification factor in the figure are values having a relationship of A <B <C <D. The state when the theoretical amplification factor output by the database 73 from the combination of the pressure value and the temperature value in the usage environment of the ultrasonic flowmeter 13 is A is state 1, and the state where the theoretical amplification factor B is B is state 2.

  First, in the leftmost received wave in the figure, the usage environment of the ultrasonic flowmeter 13 is in state 1, the theoretical amplification factor is A, and the noise determination unit 7 receives the received wave detection signal. Since the amplification unit 26 amplifies the received wave with A as an actual amplification factor, it is determined that no noise is generated. For the next received wave, the usage environment is state 2, the theoretical amplification factor is B, and the noise determination unit 7 has not received the received wave detection signal. Since the amplifying unit 26 amplifies the received wave with A as the actual amplification factor, a command for changing the actual amplification factor is output. For the third received wave, since the use environment is state 2 and the theoretical amplification factor is B, and the noise determination unit 7 has not received the reception wave detection signal, a command to change the actual amplification factor is output. For the fourth received wave, since the use environment is state 2 and the theoretical amplification factor is B, and the noise determination unit 7 has not received the received wave detection signal, a command to change the actual amplification factor is output. The fifth received wave is obtained by amplifying the fourth received wave with the actual gain of B and amplifying it with the actual gain of C. Therefore, the noise determination unit 7 can receive the received wave signal. However, since the theoretical amplification factor is B, the amplification factor is different from the actual amplification factor and is output when noise is generated. If the received wave detection signal is not detected even if the actual amplification factor is the maximum amplification factor D that is assumed depending on the fluid or environment of use, the measurement is disabled. In addition, since determination of an unmeasurable state can respond with a prior art, description in this specification is abbreviate | omitted.

  In the ultrasonic flowmeter, dirt such as oil mist adheres to the ultrasonic transducer, and the amount of adhesion increases, the received wave becomes small due to deterioration over time, and reception detection cannot be performed. However, the third received wave cannot be detected because the actual amplification factor is too large. In other words, when the actual gain is adjusted to a small value, the received wave is not attenuated due to noise. Therefore, by determining which of the actual gain is adjusted, the gain due to changes in temperature and pressure is determined. It is possible to detect the lack of tax collection.

  According to the ultrasonic flow meter 13 of the third embodiment, even when the generation of noise cannot be detected based on the noise detection time, the received wave is attenuated due to the attachment of filth to the ultrasonic transducer. Can be detected.

  The ultrasonic flowmeter 13 according to the third embodiment determines the presence or absence of noise by comparing the theoretical amplification factor and the actual amplification factor. However, the temperature and pressure of the fluid estimated from the actual amplification factor and the measuring means are determined. It can also be set as the structure which determines the presence or absence of noise by comparing the temperature and pressure which were obtained by this.

(Embodiment 4)
The ultrasonic flow meter of the fourth embodiment is a combination of the ultrasonic flow meter 11 of the first embodiment and the ultrasonic flow meter 13 of the third embodiment. By combining the ultrasonic flowmeter 11 of the first embodiment and the ultrasonic flowmeter 13 of the third embodiment, the generated noise is due to housing noise, piping noise, or dirt attached to the ultrasonic transducer. You can know what is the cause.

(Embodiment 5)
The ultrasonic flow meter of the fifth embodiment is a combination of the ultrasonic flow meter of the second embodiment and the ultrasonic flow meter 13 of the third embodiment. By combining the ultrasonic flow meter of the second embodiment and the ultrasonic flow meter 13 of the implementation object, the generated noise may be due to housing noise, piping noise, or dirt attached to the ultrasonic transducer. You can know what is the cause.

(Other embodiments)
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, an ultrasonic flow meter that combines the ultrasonic flow meter 11 of the first embodiment and the ultrasonic flow meter of the second embodiment is also conceivable. In that case, it is desirable that the fluid to be used is known, and since two types of noise determination are used, it can be assumed that noise is generated when it is determined that noise is generated on either side, It can also be assumed that noise is generated twice as long as both are determined to generate noise.

11, 13: Ultrasonic flow meter,
21 and 22: ultrasonic transducers, 23: control unit,
24: Transmission / reception wave drive unit, 25: Counter,
26: amplifying unit, 27: reference clock generating unit,
28: Noise generation notification means,
3: received wave detection unit, 31: reference level generation unit,
32: Level selection unit, 33: Comparison unit,
34: Zero-cross detection unit,
4: Over-level detection unit, 41: Noise detection level generation unit,
42: Level exceeding comparison part,
5: Noise determination unit,
6: Noise confirmation counter (noise calculation time calculation unit),
71: Pressure measuring means, 72: Temperature measuring means,
73: Database
S1, S2: changeover switches.

Claims (8)

An ultrasonic flowmeter that arranges a pair of ultrasonic transducers arranged oppositely upstream and downstream of a passage through which a fluid passes, and obtains a flow rate from the arrival time of the ultrasonic wave between them,
A received wave detection unit that outputs a received wave detection signal when it is determined that a received wave received by the ultrasonic wave receiver has received the ultrasonic wave output from the ultrasonic wave transmitter. When,
A level detection unit having a noise detection level generating unit that generates a noise detection level and a level exceeding comparison unit that outputs a noise level exceeded signal when the received wave exceeds the noise detection level;
A noise detection time calculation unit for obtaining a noise detection time, using the time when the noise level exceeded signal is output as a start point or an end point;
A noise determination unit that outputs a noise generation signal when the noise detection time is out of a normal range; and
An ultrasonic flowmeter characterized by comprising: When performing the ultrasonic output multiple times,
The noise generation signal output by the noise determination unit is a case when the noise type determination time, which is the value of the noise detection time obtained in the previous measurement, and the value of the noise detection time are the same. A signal representing noise,
The ultrasonic flowmeter according to claim 1, which is a signal representing piping noise in other cases. The noise detection time is the time from when the noise level exceeded signal is output to when the received wave detection signal is output,
It is determined that the noise detection time is longer than a set value when it is determined that the normal range is not satisfied.
The set value is assumed to be a time from when the ultrasonic wave output from the ultrasonic wave transmitter starts to be detected by the ultrasonic wave receiver to when the received wave detection signal is output. The ultrasonic flowmeter according to claim 1 or 2, wherein the ultrasonic flowmeter is set at a time longer than a predetermined time. The noise detection time is the time from when the noise level exceeded signal is output to when the received wave detection signal is output,
The super-judgment according to claim 1 or 2, wherein it is determined that the noise detection time is out of the normal range when the noise detection time is equal to or shorter than the length of one cycle of the received wave or equal to or longer than the length of two cycles. Sonic flow meter. The time for noise detection is a time from the time when the ultrasonic transmitter outputs the ultrasonic wave to the time when the noise level exceeded signal is output,
It is determined that the noise detection time is shorter than a set value when it is determined that the normal range is deviated.
The set value, the claim 1 or 2 is set within a time that is assumed from said when the ultrasonic waves output from the ultrasonic wave transmitter is when started to be detected by the ultrasonic receiver The ultrasonic flowmeter described in 1. An amplifying unit capable of appropriately adjusting the actual amplification factor of the received wave according to the amplitude of the received wave;
Temperature measuring means for measuring the temperature of the fluid and outputting the measured temperature;
Pressure measuring means for measuring the pressure of the fluid and outputting the measured pressure;
The noise determination unit is configured when the difference between an appropriate theoretical amplification factor determined by a combination of the fluid type, the measurement temperature, and the measurement pressure is greater than or equal to a predetermined value, or the actual amplification factor. 6. The noise generation signal is output according to claim 1, wherein a noise generation signal is output when a difference between the estimated temperature and the estimated pressure of the fluid estimated from the difference between the measured temperature and the measured pressure is a predetermined value or more. Ultrasonic flow meter. A set of ultrasonic transducers arranged opposite to the upstream and downstream of the passage through which the fluid passes can be arranged, and the actual gain of the received wave can be adjusted appropriately according to the amplitude of the received wave An ultrasonic flowmeter having an amplifying unit for obtaining a flow rate from an arrival time of ultrasonic waves between the ultrasonic transducers,
A received wave detection unit that outputs a received wave detection signal when it is determined that a received wave received by the ultrasonic wave receiver has received the ultrasonic wave output from the ultrasonic wave transmitter. When,
Temperature measuring means for measuring the temperature of the fluid and outputting the measured temperature;
Pressure measuring means for measuring the pressure of the fluid and outputting the measured pressure;
The fluid estimated when the difference between an appropriate theoretical amplification factor determined by a combination of the fluid type, the measurement temperature, and the measurement pressure is greater than or equal to a predetermined value or from the actual amplification factor A noise determination unit that outputs a noise generation signal when the difference between the estimated temperature and the estimated pressure and the measured temperature and the measured pressure is equal to or greater than a predetermined value;
An ultrasonic flowmeter characterized by comprising: The theoretical amplification factor is stored in a database for each combination of the fluid type, the fluid temperature, and the fluid pressure,
The database receives the temperature of the fluid from the temperature measuring means and the pressure of the fluid from the pressure measuring means each time the ultrasonic wave is output, and stores the theoretical amplification factor of the stored combination The ultrasonic flowmeter according to claim 6 or 7, which is output to a noise determination unit.

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