JP3473591B2 - Flow measurement device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measuring device for measuring the flow rate of gas or the like by utilizing ultrasonic waves.

[0002]

2. Description of the Related Art A conventional flow measuring device of this type is shown in FIG.
Those shown in were common.

This device comprises an ultrasonic transducer 2 installed in a flow path 1 of a fluid, a switching means 4 for switching transmission and reception of a first ultrasonic transducer 2 and a second ultrasonic transducer 3, and a first ultrasonic transducer. Transmitting means 5 for driving the oscillator 2 and the second ultrasonic oscillator 3
Until inputting the amplifying means 6 for amplifying the signal received by the ultrasonic transducer on the receiving side, the delay means 14 for outputting a predetermined delay signal by the signal of the control means 12, and the delay output of the delay means 14. A signal cutoff unit 7 that cuts off the output signal of the amplification unit 6 and passes the output signal of the amplification unit 6 after input.
Then, as shown in FIG. 18, the received signal A that has passed through the signal blocking means 7 and is amplified by the amplifying means 6 is compared with the reference voltage, and the magnitude relationship is inverted, and the amplified signal is repeated at the first zero-cross point b. The comparing means 8 for outputting the zero-cross detection signal D to the means 9 and the repeating means 9 for counting the signal from the comparing means 8 for counting a preset number of times and for outputting the signal from the comparing means 8 to the control means 12. And a flow rate for calculating the flow rate in consideration of the size of the pipeline and the flow state in accordance with the time counted by the time counting means 10 and the time counting means 10 for counting the time counted a preset number of times by the repeating means 9. Calculation means 11 and flow rate calculation means 1
It is composed of a flow rate output calculated from 1, a transmission means 5 for receiving a signal from the repeating means 9, and a control means 12 for controlling the operation of the delay means 14.

In this device, the control means 12 controls the transmission means 5
The ultrasonic signal transmitted by the ultrasonic transducer 2
The signal propagates through the flow, is received by the second ultrasonic transducer 3, passes through the signal blocking means 7 whose blocking and passing is controlled by the delayed output from the delay means 14, and is processed by the amplifying means 6 and the comparing means 8. Then, it is input to the control means 12 through the repeating means 9. This operation is repeated n times set in advance, and the time interval is measured by the time measuring means 10.

Then, the first ultrasonic transducer 2 and the second ultrasonic transducer 3 are switched by the switching means 4 to perform the same operation, and the fluid to be measured is changed from upstream to downstream (this direction is a forward flow). ) And downstream to upstream (this direction is referred to as backflow), and the flow rate Q was obtained from (Equation 1) (effective distance in the flow direction between ultrasonic transducers was L, from upstream) The measurement time for n times downstream is t1, the measurement time for n times downstream to upstream is t2, the flow velocity of the fluid to be measured is v, the cross-sectional area of the flow path is S, the sensor angle is φ, and the flow rate is Q. ).

Q = S · v = S · L / 2 · cos φ ((1 / t1) − (1 / t2)) (Equation 1) (Actually, Equation 1 is multiplied by a coefficient according to the flow rate. Calculate the flow rate)

[0007]

However, as shown in FIG. 18, the above conventional flow rate measuring device switches the signal blocking means from the blocking state to the passing state at the timing a, and puts the ultrasonic transducer in the reception signal waiting state, and then the noise is generated. When the signal B is applied, the erroneous zero-cross detection signal C is output to the repeating means 9 by the comparing means 8 at the first zero-cross point c that exceeds the reference voltage, so that the time measured by the time measuring means 10 is the original ultrasonic signal. Different from the propagation time of, the flow rate calculation means 11 calculates an incorrect flow rate value. This is because the shorter the time from the switching to the reception signal waiting state until the arrival of the reception signal, the lower the probability of being affected by noise. Therefore, it is desirable to switch to the reception signal waiting state immediately before the reception signal.

However, the reception signal propagating in the flow of the flow channel changes its arrival timing depending on the flow rate of this flow channel, and the direction of change also changes depending on the driving direction of the vibrator. In order to cope with the case, a slight stabilization time is added based on the shortest arrival timing (received signal E in FIG. 18) when transmitting from the upstream side, and at the timing d in FIG. 18 so that the received signal waiting state does not become long. The delay means was set so that the received signal could pass through.

Therefore, when a flow rate other than the maximum flow rate value (for example, zero flow rate) when the ultrasonic wave is transmitted from the upstream side or when the ultrasonic wave is transmitted from the downstream side, the reception signal arrives after switching to the reception signal waiting state. However, there is a problem that the flow rate is erroneously measured when noise is applied. The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a flow rate measuring device that is less likely to be affected by noise due to noise.

[0010]

In order to solve the above-mentioned conventional problems, in the flow rate measuring device of the present invention, flow rate measurement is started, and during the repeated operation by the repeating means, the interruption control means interrupts the signal from the start of the repeating operation. The means is switched from the cutoff to the passage, and the reception signal waiting state is set to a time slightly shorter than the time interval based on the previous repeated operation interval. Generally, the individual operation intervals during repetitive operation are short times of several hundreds μs, and the change in the arrival timing of the reception signal due to the change in the flow rate of the fluid conduit and the change in the flow velocity due to the temperature during this period are extremely small, so When the cutoff control means controls the signal cutoff means, the reception signal cutoff state is switched to the standby state immediately before the arrival of the reception signal. As a result, the period of the reception signal standby state in which the flow rate measurement is affected by noise is shortened, and the probability of being influenced by noise is reduced, so that the flow rate measurement device is less affected by the flow rate measurement.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The flow in the first embodiment of the present invention
The quantity measuring device includes a first oscillator and a second oscillator provided in a fluid conduit for transmitting and receiving ultrasonic signals, a transmitting unit for driving the oscillator, a switching unit for switching between transmitting and receiving of the oscillator, and and repeating means for performing a plurality of times mutual ultrasonic transmission between transducer, signal for the flow rate calculation means for calculating a flow rate based on the accumulated time of the ultrasonic wave propagation, the passage and blocking of the received signal of the reception-side vibration Doko Blocking means, blocking control means for controlling the signal blocking means based on the repeating time interval of the repeating means, and reception signal passing through the signal blocking means
Signal is compared with the reference voltage and the magnitude relationship is reversed.
Repeat the above with the zero-cross point as the zero-cross detection signal
And comparing means for outputting to the means. This allows
During the repetitive operation by the repetitive means, the timing at which the signal interruption means switches from interruption to passage is slightly shorter than the repetitive time interval one time before, and is a period affected by noise until the arrival of the reception signal in the reception signal waiting state. Becomes shorter . In addition, the signal has been passed through the signal blocking means.
The received signal and the reference voltage are compared, and the magnitude relationship is reversed.
The next zero cross point is used as the zero cross detection signal.
Since it outputs it to the return means, it does not exceed the reference voltage.
It is possible to obtain a flow rate measuring device that is capable of removing scratches and the like and is less susceptible to noise.

In the second embodiment, repeated ultrasonic waves are used.
Interval storage means for storing the time interval or time interval difference is added.
In preparation for this, the cutoff control means stores in the interval storage means.
The signal interruption based on the time interval or the time interval difference
It controls the means. Thereby, the interval storage means
Past time interval record or past time interval difference stored in
Since the signal blocking means is controlled based on the set value based on actual results, in the first operation of the repetitive operation, it is switched to the reception signal waiting state at the timing according to the actual use state, and the period until the reception signal arrives is short. Therefore, the flow rate measuring device can be made less susceptible to noise.

In the third embodiment, the fluid pipe is provided.
First oscillator and second oscillator for transmitting and receiving a received ultrasonic signal
A child, a transmitting unit that drives the vibrator, and the vibrator.
Switching means for switching between transmission and reception, and mutual
Repeating means for transmitting ultrasonic waves multiple times,
A flow rate calculating means for calculating the flow rate based on the accumulated time,
Setting memory that stores the setting value for each transmission and reception direction of the oscillator
Means and the reception signal of the transducer on the receiving side
Signal shutoff means and the shutoff hand based on the storage means.
Disconnection control means for controlling the step. By this
The transmission and reception of the vibrator stored in the setting storage means.
With the setting value for each direction as the initial value
Since disconnection control is performed,
Even in this case, the period from the reception signal waiting state to the arrival of the reception signal is shortened, and the flow rate measuring device can be hardly affected by noise.

In the fourth embodiment, the fluid pipe is provided.
Oscillator and second oscillator for transmitting and receiving ultrasonic signals
And transmitting means for driving the vibrator, and transmitting the vibrator.
Switching means for switching the reception, repeating means for mutually transmitting ultrasonic waves between the transducers a plurality of times, flow rate calculating means for calculating the flow rate based on the cumulative time of ultrasonic wave propagation, and storing the time setting value. Signal blocking means for passing and blocking the reception signal of the receiving transducer, interval storage means for storing the minimum value or the maximum value of the repetition time interval of ultrasonic transmission,
The time setting value is updated based on the minimum value or the maximum value, and a cutoff control means for controlling the signal cutting means based on the updated time setting value and the repeating time interval of the repeating means is provided. There is. As a result, the signal interruption means is controlled based on the set value based on the minimum value or the maximum value of the repetition time interval of ultrasonic transmission stored in the interval storage means, so that it is actually used in the first operation of the repeated operation. The flow rate measuring device is switched to the reception signal waiting state at a timing according to the state, the period until the reception signal arrives is shortened, and the flow rate measuring device is less susceptible to noise.

[0015] In the fifth embodiment, further comprising an initial value storing means for the flow rate in the fluid conduit to store the repetition time interval of the ultrasonic transmission by repeating means when zero, the
The cutoff control means is a square
The last repeat time interval and flow rate
The signal blocker based on the repeating time interval at zero
Control the steps. With this , the reception signal waiting state is switched at a timing according to the transmission direction of the transducer, and particularly in the reverse direction, the period from the reception signal waiting state to the arrival of the reception signal is shortened, and the flow rate measuring device is less susceptible to noise. You can do it.

In the sixth embodiment, the ultrasonic wave transmission is repeated.
A representative value that stores the latest value of the return time interval as a representative value
The cutoff control means further comprises a storage means,
The signal cutoff means is controlled based on the above. This allows
Since the signal blocking means is controlled by setting the initial value to the set value based on the past time interval record for each transmission direction of the vibrator, especially in the first operation of the repetitive operation in the reverse direction, the timing corresponding to the actual use state. Is switched to the reception signal standby state, the period until the reception signal arrives is shortened,
The flow rate measuring device can be made less susceptible to noise.

In the seventh embodiment, the first oscillator
And repeated transmission of ultrasonic waves for each transmission and reception direction of the second transducer
Further, an average value storage means for storing the average value of the time interval is further provided.
The cutoff control means is based on the average value,
Control the breaking means. As a result, the signal blocking means is controlled with the set value based on the average value of the past time interval results as the initial value, so that in the first operation of the repetitive operation, the reception signal waiting is performed at a timing more suited to the actual use state. The flow rate measuring device is switched to the state, the period until the reception signal arrives is shortened, and the flow rate measuring device can be hardly affected by noise.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram of a flow rate measuring device according to a first embodiment of the present invention. In FIG. 1, a first ultrasonic transducer 2 that transmits ultrasonic waves and a second ultrasonic wave that receives ultrasonic waves are provided in the middle of the flow path 1.
The ultrasonic transducers 3 are arranged at an angle φ in the flow direction.
5 is a transmitting means to the first ultrasonic transducer 2, and 4 is a first
Switching means for switching between transmission and reception of the ultrasonic transducer 2 and the second ultrasonic transducer 3, 6 is amplification means for amplifying a signal received by the ultrasonic transducer on the receiving side, and 7 is an ultrasonic transducer on the receiving side. It is a signal blocking means for passing and blocking the received signal. The signal that has passed through the signal cut-off means 7 is compared with the reference voltage by the comparison means 8 and is output to the repeating means 9 as a zero-cross detection signal at the next zero-cross point at which the magnitude relation is reversed.

The repeating means 9 counts the reception of the zero-cross detection signal of the comparing means 8 and counts a preset number of times, and outputs the signal from the comparing means 8 to the control means 12. Numeral 10 is a first timing means for timing the time counting the number of times set in advance by the repeating means 9, and 11 is a function of considering the size of the pipeline and the state of the flow in accordance with the time counted by the first timing means 10. It is a flow rate calculation means 8 for calculating the flow rate. Reference numeral 13a is a second timing means for receiving a signal from the control means 12 and timing a preset time,
Reference numeral 13b is a third timing means for timing the time difference between the signals of the comparison means 8 and the second timing means 13a, and 13c is the time of the third clock means 13b receiving the signal of the second timing means 13a. It is a fourth timing means and a second timing means 1
3a, the 3rd timing means 13b, and the 4th timing means 13c constitute the interruption control means 13 for controlling the signal interruption means.
Reference numeral 12 is a control unit that receives signals from the flow rate calculation unit 11 and the repeating unit 9 and controls the operations of the transmission unit 5 and the cutoff control unit 13.

The operation and action of the flow rate measuring device configured as described above will be described below. First, the control means 1
When the flow rate measurement 2 starts, the transmitting means 5 is operated to transmit an ultrasonic wave signal from the ultrasonic transducer 2, and at the same time output a time counting start signal to the second time measuring means 13a. Second timing means 13a
Starts timing with a timing start signal and measures two preset times (constant times t0 and t1 in FIG. 2),
At the end of each timing (points A and B in FIG. 2), a timing start signal is output to the fourth timing means 13c and the third timing means 13b. The third timing means 13b measures the time Ct1 from the timing start signal (point B in FIG. 2) from the second timing means 13a until the signal from the comparison means 8 (point C in FIG. 2) is input, After the time measurement ends, the time measurement time Ct1 is transferred to the fourth time measurement means 13c. The fourth timing means 13c starts timing from the timing start signal (point A in FIG. 2) from the second timing means 13a and sets a preset time C.
When the time is measured for t0 (point D in FIG. 2), the signal is output to the signal cutoff means 7, the signal cutoff means 7 is switched from the cutoff state to the passing state, and the cutoff state is returned again after a predetermined time has elapsed.

On the other hand, the ultrasonic signal transmitted from the first ultrasonic transducer 2 propagates in the flow of the flow path 1, is received by the second ultrasonic transducer 3, is amplified by the amplifying means 6, and cuts off the signal. It is input to the means 7. When the signal blocking means 7 is switched from the blocking state to the passing state by the blocking control means 13 as described above, the received signal of the second ultrasonic transducer 3 amplified by the amplifying means 6 is input to the comparing means 8 and the reference voltage is applied. And is output to the repeating unit 9 as a zero-cross detection signal at the next zero-cross point at which the magnitude relation is reversed. The zero-cross detection signal is counted by the repeater 9 and then input to the controller 12.

Then, the control means 12 operates the transmitting means 5 again to transmit the ultrasonic wave signal from the ultrasonic vibrator 2 and at the same time, again outputs the time counting start signal to the second time counting means 13a. Therefore, in FIG. 2, C of the zero-cross detection signal of the comparison means 8
From the point, the second timing unit 13a again sets the constant time t0, t
2, the timing start signal is output to the fourth timing means 13c and the third timing means 13b at points A'and B'in FIG. The fourth timing means 13c is the third timing means 1
The time Ct1 transferred from 3b is measured, and the third time measuring means 13b measures the time Ct2 until the signal of the comparing means 8 (point C'in FIG. 2) is input.

That is, the fourth timing means 13c counts the time counted by the third timing means 13b of the immediately preceding operation.
This operation is repeated n times preset,
The time interval is measured by the time measuring means 10. And
The first ultrasonic transducer 2 and the second ultrasonic transducer 3 are switched by the switching means 4 to perform the above-mentioned operation, and the time at that time is measured by the time counting means 10. Then, the flow rate calculation means 11 calculates the flow rate value from these two time differences in consideration of the size of the flow path and the flow state. By operating as described above, the timing at which the signal blocking means 7 is switched from the blocking state to the passing state is the third time counting means 1 one time before the repeated operation.
3b is determined based on the time measured, and its value is shorter than the zero-cross detection signal of the comparison means 8 by the time difference (t1-t0) between the times t0 and t1 measured by the second time measurement means 13a.

That is, if the zero-crossing detection signal of the comparison means 8 is output at the same timing as the previous time (the output of the comparison means 8 indicated by the dotted line in FIG. 2), the signal cut-off means 6 is activated by the time t1-t0 before the output. Switch from blocking to passing. Although the timing of the zero-crossing detection signal of the comparing means 8 varies depending on the flow rate change of the fluid conduit and the flow velocity change due to temperature, the repetitive operation interval during the repetitive operation is usually a short time of several hundreds of μs, and therefore, during this period. Of the output of the comparison means 8 is small,
Since 2 is also small, the timing of the zero-cross detection signal hardly changes.

Here, if the time difference between the times t0 and t1 measured by the second timing means 13a is set to a value slightly larger than the maximum variation width of the output fluctuation t2 of the comparison means 8, the signal cutoff means must be provided before the arrival of the received signal. 6 is switched from the cutoff state to the passing state, and the period from the reception signal waiting state of the comparison means 8 to the arrival of the reception signal can be set to a short time, the period affected by noise is short, and the flow rate measurement is less susceptible to noise. It can be a device.

Further, such a flow rate measuring operation is usually executed at intervals of several seconds, and there is a possibility that the flow rate change and the temperature change during the non-measurement of the flow rate may be large. Therefore, the set value of the time t0 is set to a time slightly earlier than the timing (the maximum flow rate value of the flow path and the maximum use temperature) at which the output of the zero-crossing detection signal of the comparison means 8 becomes earliest, and the initial value of the fourth timing means 13c is set to zero. As a result, the signal blocking means 7 can be switched from the blocking state to the passing state before the arrival of the received signal under any conditions of the flow rate value and the temperature at the time of the first flow rate measurement of the repeated operation.

As described above, in the present embodiment, the timing at which the interruption control means 13 switches the signal interruption means 7 from the interruption state to the passing state is based on the time measured by the third timing means 13b one time before the repeated operation. Therefore, before the arrival of the received signal, the signal blocking means 7 always switches from the blocking state to the passing state, and the period from the received signal waiting state of the comparison means 8 to the arrival of the received signal is set to a short time. Therefore, it is possible to provide a flow rate measuring device that is not easily influenced by noise because the period affected by noise is short.

Second Embodiment FIG. 3 is a block diagram of a flow rate measuring device according to a second embodiment of the present invention. FIG. 4 is an operation explanatory view of the flow rate measuring device according to the second embodiment of the present invention, and shows how the received signal of the ultrasonic transducer on the receiving side fluctuates. In FIG. 3, the setting storage means 15 is a setting storage means for storing the setting value from the control means 12 and outputting it to the cutoff control means 13.
Is a cutoff control means for switching the signal cutoff means 6 between passage and cutoff of the reception signal of the transducer on the reception side based on the set value stored in the setting storage means 15. The operation and action of the flow rate measuring device configured as described above will be described below.

In FIG. 4, the waveform B is the first ultrasonic transducer 2
When transmitted by the second ultrasonic transducer 3 (hereinafter referred to as a positive direction) and when transmitted by the second ultrasonic transducer 3 and received by the first ultrasonic transducer 2 (hereinafter referred to as a reverse direction). Shows the received signal when the flow rate of the flow path is zero. Further, the waveform A shows the received signal in the forward direction at the maximum flow rate. Further, the waveform C shows the received signal in the reverse direction at the maximum flow rate. As described above, depending on the transmission direction of the transducer, the reception signals A to B in the forward direction fluctuate before the zero flow rate, and the reception signals in the reverse direction fluctuate, and the reception signals fluctuate after the zero flow rate.

Therefore, the control means 12 causes the setting storage means 15 to store a different set value for each transmission direction of the first ultrasonic transducer 2 and the second ultrasonic transducer 3 when performing the flow rate measurement, and performs the measurement operation. First, when the flow rate measurement is started, the control unit 12 operates the transmission unit 5 to transmit the ultrasonic signal from the first ultrasonic transducer 2 and output the time counting start signal to the cutoff control unit 13. Further, the control unit 12 sets the setting value corresponding to the reception signal A which is the shortest timing (timing at which the reception signal arrives earliest) in the forward direction in the setting storage unit 15 (the setting value corresponding to the setting time Tf in FIG. 4). Is output and stored. The cutoff control means 13 starts timekeeping in response to a timekeeping start signal from the control means 12, measures the time set by the setting storage means 15 (set time Tf in FIG. 4), and outputs it to the signal cutoff means 7 at the end of the timekeeping. The signal blocking means 7 switches from the blocking state to the passing state, and returns to the blocking state again after a predetermined time has elapsed.

On the other hand, the ultrasonic signal transmitted from the first ultrasonic transducer 2 propagates in the flow of the channel 1, is received by the second ultrasonic transducer 3, and is amplified by the amplifying means 6. Further, the amplified signal is input to the signal blocking means 7. When the signal cutoff means 7 is switched from the cutoff state to the passing state by the cutoff control means 13 as described above, the received signal of the second ultrasonic transducer 3 that has passed through the signal cutoff means 7 is input to the comparison means 8 and supplied with the reference voltage. And is output to the repeating unit 9 as a zero-cross detection signal at the next zero-cross point at which the magnitude relation is reversed. This zero-cross detection signal is counted by the repeating means 9 and then input to the control means 12.

Then, the control means 12 operates the transmitting means 5 again to transmit the ultrasonic wave signal from the ultrasonic vibrator 2 and at the same time output the time counting start signal to the interruption control means 13 again. This operation is repeated n times which is set in advance, and the time interval is measured by the time measuring means 10. And the first
The ultrasonic transducer 2 and the second ultrasonic transducer 3 are switched by the switching means 4, and the control means 12 causes the setting storage means 15 to set a value corresponding to the received signal B which is the shortest timing in the reverse direction (see FIG. 4). At, the set value corresponding to the set time Tr) is output and stored. Then, the above-described operation is performed, the time at that time is measured by the time measuring means 10, and the flow rate calculation means 11 determines the flow rate value from the difference between these two times in consideration of the size of the flow path and the flow state.

As described above, in the present embodiment, the timing at which the signal blocking means 7 is switched from the blocking state to the passing state is set to the proper timing in each of the forward direction and the reverse direction, so that the reception signal is always before the arrival. With signal blocking means 7
Is switched from the cutoff state to the passing state, and the period from the reception signal waiting state of the comparison means 8 to the arrival of the reception signal can be set to a short time both in the forward and reverse directions, and the period affected by noise is short, and the influence of noise is short. It is possible to make the flow rate measuring device hard to receive.

In this embodiment, the set values in the forward direction and the reverse direction are fixed values, but the known temperature of the fluid is calculated from the respective propagation times measured by the first timing means 10, and the set values are set accordingly. Needless to say, if the set value stored in the storage means 15 is changed in response to the temperature change, the temperature change of the fluid can be dealt with, which is even more effective.

(Third Embodiment) FIG. 5 is a block diagram of a flow rate measuring apparatus according to a third embodiment of the present invention. FIG. 6 is an operation explanatory diagram of the flow rate measuring device according to the third embodiment of the present invention.

In FIG. 5, reference numeral 17 denotes an interval storage means for storing the repetition time interval of ultrasonic transmission, which is different from the configuration of the first embodiment in that the interval storage means 17 is provided.

The operation and action of the flow rate measuring device constructed as above will be described below. When the flow rate is measured by the control means 12, the time measured by the third timing means 13b (time Ctmin and Ctma in FIG. 6).
x) is stored in the interval storage means 17. This time is the time of past measurement results and corresponds to the flow rate of the fluid in the flow rate measuring device of the present invention when it is actually used. As described in the first embodiment, the constant times t0 and t1 preset in the time cutoff unit 13a are determined by the timing at which the zero cross detection signal output becomes earliest based on the maximum flow rate value of the flow path and the maximum use temperature. There is.

However, due to reasons such as not being used in a large flow rate region and the temperature of the fluid not becoming high, the set value is not always the optimum set value depending on the actual use conditions. The output of the comparison means 8 is the output of the comparison means of FIG. 6 (zero-cross detection signal) depending on the flow rate and the temperature of the flow path 1 under actual use conditions.
The output timing fluctuates as indicated by the dotted line. Therefore, the time cutoff means 13a updates the time set value as follows based on the minimum value of the time measured by the third time measurement means 13b stored in the interval storage means 17 (time Ctmin in FIG. 6). It is changed as shown in the output b of the interruption control means.

Set value t1 '= t1 + Ctmin Set value t0' = t0 + Ctmin As described above, the time setting value of the time cutoff means 13a is based on the minimum value of the time measured by the third time measuring means 13b stored in the interval storage means 17. In the first time of the flow rate measurement repeating operation by updating, even at the output timing of the comparison means 8 having the earliest measurement result in the past, the timing at which the signal interruption means 6 switches from the interruption state to the passage state is the setup time (t1-t0). ) Minutes before you. As mentioned above,
In the present embodiment, the signal cutoff means 6 is controlled with the set value based on the past time interval results as the initial value, so that even in the first operation of the repetitive operation, the signal is cut off according to the actual use state under the use condition. It is possible to obtain a flow rate measuring device that is switched to the reception signal waiting state at the timing, and the period until the reception signal arrives is shortened, and is less susceptible to noise.

(Fourth Embodiment) FIG. 7 is a block diagram of a flow rate measuring apparatus according to a fourth embodiment of the present invention. FIG. 8 is an operation explanatory diagram of the flow rate measuring device according to the fourth embodiment of the present invention. In FIG. 7, 18 is the third timing means 13b.
Is the interval difference storage means for calculating and storing the difference in the repetition time interval of the ultrasonic transmission that is timed, and is different from the configuration of the first embodiment in that the interval difference storage means 18 is provided. The operation and action of the flow rate measuring device configured as described above will be described below. As described in the first embodiment, during the repeated operation, the time from the time measurement start signal from the second time measurement means 13a to the zero-cross detection signal of the comparison means 8 is measured by the third time measurement means 13b. The interval difference storage means 18 calculates each time interval difference measured by the third timing means 13b and stores the maximum value. When the flow rate measurement is started by the control means 12, the maximum value of the interval difference (Dmax in FIG. 8) previously stored in the interval difference storage means 18 of the second timing means 13a is the time setting values t0 and t1. When it is smaller than the time difference (t1-t0), the time setting value t1 is updated as follows.

T1 '= t0 + Dmax When the time setting value t0 and the updated time t1' are completed, the third time measuring means 13b, the fourth time measuring means 13c,
A time start signal is output to (point A, B in FIG. 8)
point). The third timing means 13b is the second timing means 13a.
The time Ctn 'from the timing start signal (point B in FIG. 8) to the input of the zero-cross detection signal (point C in FIG. 8) of the comparing means 8 is measured, and after the timing ends, the time Ctn' is calculated. Transfer to the fourth timing means 13c. Fourth
The time measuring means 13c measures the set time Ctn from the third time measuring means 13b before t1 is updated from the time measuring start signal (point A in FIG. 8) from the second time measuring means 13a and the time measurement ending point (in FIG. 8). At point D), the signal is output to the signal cutoff means 7, and the signal cutoff means 6 is switched from the cutoff state to the passing state, and after a predetermined time has passed, it is returned to the cutoff state.

When the comparison means 8 outputs the zero-crossing detection signal, the second timing means 13a restarts timing for a fixed time t0, t1 'by the timing start signal from the control means 12, and point A'in FIG. , B'point at 4th timing means 1
A clock start signal is output to 3c and the third clock means 13b. Then, the fourth timing means 13c counts the time Ctn 'transferred from the third timing means 13b, and outputs it to the signal interruption means 7 at the time measurement end point (point E in FIG. 8), and the signal interruption means 6 from the interruption state. Switch to the passing state.

The timing at which the signal blocking means 6 is switched from the blocking state to the passing state by operating as described above is determined based on the time difference measured by the third timing means 13b during the repeated operation, and its value is determined. The maximum value Dmax of the interval difference of the time Ctn, which is stored in the interval difference storage means 18 and is counted each time by the third timing means 13b, is earlier than the output of the comparison means 8. That is, if the output of the comparison means 8 is output at the same timing as the previous time, the time when the signal interruption means 6 switches from the interruption to the passing state is from point D to point E in FIG. 8, and only the time of Dmax from the zero cross detection signal. Before. The time setting values t0 and t1 of the second time measuring means 13a are set in consideration of the maximum flow rate of the flow path and the maximum operating temperature, and are output to the comparing means 8 in a normal state such as when the maximum flow rate is not flowing. On the other hand, the signal blocking means 7 has switched from the blocking state to the passing state sufficiently long before. On the other hand, the maximum value Dma of the interval difference stored in the interval difference storage means 18
By setting the time setting value t1 as described above based on x, it is possible to switch the signal cutoff means 7 from the cutoff state to the passing state at a timing suitable for actual use and without waste.

As described above, in the present embodiment, the time when the interruption control means 13 switches the signal interruption means 7 from the interruption state to the passing state is the third timing means 13b which is repeatedly operating.
By determining based on the maximum value of the time difference measured by, the signal blocking means 7 switches from the blocking state to the passing state before the arrival of the received signal and at a timing without waste according to actual use, and the amplifying means 7. Since the period from the reception signal waiting state of the comparing means 8 to the arrival of the reception signal can be set to a short time, the period affected by noise is short and the flow rate measuring device can be hardly influenced by noise.

(Fifth Embodiment) FIG. 9 is a block diagram of a flow rate measuring apparatus according to a fifth embodiment of the present invention.

FIG. 10 is a diagram for explaining the operation of the flow rate measuring device according to the fifth embodiment of the present invention.

In FIG. 9, reference numeral 19 denotes an initial value storage means for storing the time (the time Ctref in FIG. 10) measured by the third time measuring means 13b at the beginning of the repeated operation when the flow rate in the flow path 1 is zero. The difference from the configuration of the first embodiment is that an initial value storage means 19 is provided.

The operation and action of the flow rate measuring device configured as described above will be described below. The control means 12 operates the transmission means 5 in a state where the valve etc. (not shown) provided in the flow path 1 are shut off by the control means 12 and the flow rate is made zero, and the ultrasonic wave signal is transmitted from the ultrasonic transducer 2. Then, the second timing means 13a starts timing, measures a preset time (a fixed time t1 in FIG. 10), and at the end of timing (point B in FIG. 10), counts it to the third timing means 13b. Output the start signal. The third timing means 13b outputs a timing start signal (B in FIG. 10) from the second timing means 13a.
The time Ctref from the point) to the input of the zero-cross detection signal b (point D in FIG. 10) of the comparison means 8 is measured, and the initial value storage means 19 stores the time Ctref measured by the third timing means 13b.

Then, the valve is opened and the control means 12 starts the normal flow rate measurement. In the same manner as described in the first embodiment, during the repeated operation, the fourth time measuring means 13c measures the time measured by the third time measuring means 13b in the immediately preceding operation, and after the time measurement is completed, the signal interruption means 6 is passed from the interruption state. Switch to the state and return to the cutoff state again after the lapse of a predetermined time. Then, the time C measured by the third time measuring means 13b at the end of the repetitive operation in the positive direction.
The initial value storage means 1 is set to the time difference Td (= Ctref-Ctfe) between tfe and the time Ctref of the initial value storage means 19.
Time Tini (= Ctre
Let f + Td) be the initial value measured by the fourth timing means 13c in the reverse direction.

As a result, the timing at which the first signal blocking means of the repeated operation in the reverse direction switches from the blocking state to the passing state is the time Tini elapses after the fourth clocking means 13c starts timing in the reverse direction. Indicates a short time difference of several ms between the forward and reverse directions, and the change in the flow rate during this time is very small. Therefore, the zero-cross detection signal of the comparison means 8 during the measurement in the backward direction is the zero-cross signal c in FIG. , T1-to precede the zero-cross signal c.

As described above, the time measured by the third timekeeping means 13b at the end of the repeating operation in the positive direction and the initial value storing means 1
The time difference Td from the time of 9 is added to the time of the initial value storage means 19 to set the time as the initial value which the fourth time counting means 13c in the backward direction counts, so that the receiving signal waiting state of the comparison means 8 is reversed. It is possible to shorten the period until the reception signal arrives. As described above, in the present embodiment, the timing at which the signal blocking means 6 is switched from the blocking state to the passing state is set to the proper timing in each of the forward direction and the backward direction, so that the signal blocking is always performed before the reception signal arrives. The means 6 switches from the interruption to the passing state, and the comparison means 8
The period from the reception signal waiting state to the arrival of the reception signal can be set to a short time in both the forward direction and the reverse direction, and the period affected by noise is short and the flow rate measuring device can be hardly influenced by noise.

(Sixth Embodiment) FIG. 11 is a block diagram of a flow rate measuring apparatus according to a sixth embodiment of the present invention. FIG. 12 is an operation explanatory diagram of the flow rate measuring device according to the sixth embodiment of the present invention. In FIG. 11, reference numeral 20 denotes a representative value storage means for storing the latest value of the interval storage means 17 as a representative value for each transmission / reception direction of the vibrator. Representative value storage means 20
Is different from the configuration of the third embodiment. The operation and action of the flow rate measuring device configured as described above will be described below. The representative value storage means 20 stores the latest time measured by the third time measurement means 13b stored in the interval storage means 17 for each transmission / reception direction (the last time measured by the number of times set by the repeater 9). To do. Then, when the flow rate measurement is started, the control means 12 operates the transmitting means 5 to transmit the ultrasonic signal from the ultrasonic transducer 2 and at the same time output the timing start signal to the second timing means 13a. The second timing means 13a starts timing with a timing start signal, counts two preset times (constant times t0 and t1 in FIG. 12), and finishes timing of each (points A and B in FIG. 12). And the fourth timing means 13c and the third
The clocking start signal is output to each of the clocking means 13b.
The third timing means 13b measures the time Ct1 from the timing start signal (point B in FIG. 12) from the second timing means 13a to the input of the zero-cross detection signal (point C in FIG. 12) of the comparison means 8. .

The fourth timing means 13c is the second timing means 13
The time Ctl stored in the representative value storage means 20 is started from the timing start signal (point A in FIG. 12) from a.
The signal is output to the signal cut-off means 6 at the time when only ast is timed (point D in FIG. 12), the signal cut-off means 6 is switched from the cut-off state to the passing state, and after a predetermined time has passed, it is returned to the cut-off state again. On the other hand, the ultrasonic signal transmitted from the first ultrasonic vibrator 2 propagates in the flow of the flow path 1, is received by the second ultrasonic vibrator 3, is amplified by the amplifying means 6, and is transmitted to the signal blocking means 6. Is entered. When the signal cutoff means 6 is switched from the cutoff state to the passing state by the cutoff control means 13 as described above, the received signal of the second ultrasonic transducer 3 amplified by the amplification means 6 is input to the comparison means 8 and the reference voltage is applied. At the next zero-cross point where the magnitude relationship is reversed, a zero-cross detection signal (point C in FIG. 12) is output to the repeating means 9 and the above-mentioned third timing means 13b finishes the timing, and the timing time Ct1. Is transferred to the fourth timing means 13c.

The zero-cross detection signal is counted by the repeater 9 and then input to the controller 12. Then, the control means 12 causes the transmitting means 5 to operate again, and the ultrasonic transducer 2
The ultrasonic signal is further transmitted, and the time counting start signal is output again to the second time counting means 13a. This operation is repeated n times which is set in advance, and the time interval is measured by the time measuring means 10. Then, the first ultrasonic transducer 2 and the second ultrasonic transducer 3 are switched by the switching means 4, the above-mentioned operation is performed, and the time at that time is measured by the time counting means 10.

Then, the flow rate calculating means 11 determines the flow rate value from these two time differences in consideration of the size of the flow path and the flow state. By operating as described above, the time measurement time of the fourth time measurement means 13c at the beginning of the repetitive operation is the time measurement time of the last third time measurement means 13b at the time of flow rate measurement in the same direction of transmission and reception (forward direction or reverse direction). As a result, the timing at which the first signal blocking means 6 is switched from the blocking state to the passing state is the same as the last timing when measuring the flow rate in the same direction (forward or reverse direction) of transmission and reception. In other words, by using the previous time measurement time in the continuous flow rate measurement operation, the period from the reception signal waiting state of the comparison means 8 to the arrival of the reception signal can be set to an optimum and short time,
The period affected by noise is short and the flow rate measuring device is less susceptible to noise.

(Seventh Embodiment) FIG. 13 is a block diagram of a flow rate measuring apparatus according to a seventh embodiment of the present invention. FIG. 14 is an operation explanatory diagram of the flow rate measuring device according to the seventh embodiment of the present invention. In FIG. 13, reference numeral 21 denotes an average storage means for calculating and storing the average value of the interval storage means 17 for each transmission / reception direction of the vibrator. The difference from the configuration of the third embodiment is that an average storage means 21 is provided. The operation and action of the flow rate measuring device configured as described above will be described below. The average storage means 21 calculates and stores the average of the time measured by the third clock means 13b stored in the interval storage means 17 for each transmission / reception direction.

The flow rate measurement is started, and the first time measurement time of the fourth time measurement means 13c of the repeated operation is the time measurement time of the third time measurement means 13b at the time of flow rate measurement in the same direction (forward or reverse direction) of the previous transmission / reception. Average value (Ctav in FIG. 14
e) is used, so that the timing at which the first signal blocking means 6 is switched from the blocking state to the passing state is an average timing at the time of flow rate measurement in the same direction (forward direction or reverse direction) of the previous transmission and reception. .

That is, by using the average value of the time counts of the third timekeeping means 13b of the previous time in the continuous flow rate measuring operation, from the reception signal waiting state of the comparison means 8 to the arrival of the reception signal without being affected by the erroneous time measurement. The period can be set to an optimum and short time, the period affected by noise is short, and the flow rate measuring device can be hardly affected by noise.

(Embodiment 8) FIG. 15 is a block diagram of a flow rate measuring apparatus according to Embodiment 8 of the present invention. FIG. 16 is an operation explanatory diagram of the flow rate measuring device according to the eighth embodiment of the present invention. In FIG. 15, 13d is a fifth time measuring means for receiving a signal from the second time measuring means 13a and measuring a time measured by the third time measuring means 13b and a time shorter than the time measured by the third time measuring means 13b by a predetermined time. Yes, second timing means 13a, third timing means 13b, fifth timing means 13d
Constitutes a cutoff control means 13 for controlling the signal cutoff means.

A shutoff control means 1 is provided with a fifth timing means 13d.
The difference from the configuration of the first embodiment is that the amplifying means 6 is controlled by 3. The operation and action of the flow rate measuring device configured as described above will be described below. In addition, Example 1
The description of the same operation part as the above is omitted.

When the flow rate measurement is started, the second timing means 13a
Starts timing with a timing start signal from the control means 12,
Two preset times (constant time t in FIG. 16)
0, t1), and when the respective timing ends (see FIG. 16).
At point A and point B), a timing start signal is output to the fifth timing means 13d and the third timing means 13b. The third timing means 13b receives a time C from the timing start signal from the second timing means 13a (point B in FIG. 16) to the zero cross detection signal of the comparison means 8 (point C in FIG. 16).
Time t1 is measured, and after the time measurement is completed, the time count Ct1 is transferred to the fifth time measurement means 13d.

On the other hand, the fifth timing means 13d starts timing from the timing start signal (point A in FIG. 16) from the second timing means 13a and measures the time Ct0 (initial value is zero) set in advance. At a time point (point A in FIG. 16), the signal is output to the signal cutoff means 7, the signal cutoff means 7 is switched from the cutoff state to the passing state, and after a lapse of a predetermined time, it is returned to the cutoff state. Similarly, from the set time Ct0 to the fixed time Tc
When Ctamp is timed for a short time of nst, the amplification means 6
To the operating state. (When Ct0 is shorter than Tcnst, Ct0 and Ctamp are the same) Then, after a predetermined time has elapsed, the state is returned to the non-operation state. When the zero-crossing detection signal is detected by the comparison means 8 and input to the control means 12 through the repeating means 9, the control means 12 operates the transmitting means 5 again and transmits the ultrasonic signal from the ultrasonic transducer 2. The timing start signal is output again to the second timing means 13a.

Therefore, in FIG. 16, from the zero cross detection signal of the comparison means 8 at the point C, the second timing means 13a again
A'in FIG. 16 is started from the time measurement of the fixed time t0 and t1.
Fifth timing means 13d and third timing means 13b at points B and B
To the clock start signal. And the fifth timing means 13
d measures the time Ct1 transferred from the third time measuring means 13b, and the third time measuring means 13b measures the time Ct2 until the signal of the comparing means 8 (point C'in FIG. 2) is input, and the time measurement ends. After that, the measured time Ct2 is set to the fifth timing means 1
Transfer to 3d.

On the other hand, the fifth timing means 13d outputs a timing start signal from the second timing means 13a (point A'in FIG. 16).
When the time is measured for a preset time Ct1 (point E in FIG. 16), the signal is output to the signal cutoff means 7, the signal cutoff means 7 is switched from the cutoff state to the passing state, and a predetermined time elapses. , Return to the cutoff state again. Similarly, when the time Ctamp, which is shorter than the set time Ct1 by the constant time Tcnst, is counted, the amplifying means 6 is switched to the operating state. Then, after a lapse of a predetermined time, it is returned to the non-operating state.

That is, the fifth timing means 13d re-times the time counted by the third timing means 13b of the immediately preceding operation, and controls the amplifying means 6 and the signal cutoff means 7 based on this time.

As a result of the above operation, the timing at which the signal blocking means 6 is switched from the blocking state to the passing state is the second timing means 13a rather than the zero cross detection signal of the comparing means 8.
Is shorter than the time difference (t1−t0) between the time t0 and the time t1 measured by the amplifier.
However, if Tcnst is set to the operation stabilization time of the amplification means 6, the operation of the amplification means 6 becomes stable and the zero cross detection signal can be detected by the comparison means 8 immediately after, and the operation time of the amplification means 6 can be shortened and amplified. The current consumption of the means 6 can also be suppressed.

As described above, in the present embodiment, the cutoff control means 13 has the third clocking means 13b one time before the repeated operation.
By switching the state of the signal cutoff means 7 and the state of the amplification means 6 on the basis of the time measured by, the current consumption in the amplification means 6 is suppressed, and the signal cutoff means 6 is always operated before the arrival of the received signal. With a flow rate measuring device that is switched from the cutoff state to the passing state, the period from the reception signal waiting state of the comparison means 8 to the arrival of the reception signal can be set to a short time, the period affected by noise can be shortened, and the influence of noise can be reduced. You can do it.

Summarizing the effects of the above embodiments,
It becomes as follows.

[0070] shielding sectional control means 13 of the timing of the repetitive operation is switched signal cut-off means 6 from the cutoff to the passing state 1
By making the determination based on the time counted by the third time counting means 13b before the time, the signal cutoff means 6 must be switched from the cutoff state to the passing state before the arrival of the received signal, and the reception signal waiting of the comparison means 8 can be performed. you can configure in a short time period until arrival of the received signal from the state. In addition to this,
The received signal that has passed through the disconnection means is compared with the reference voltage, and the
Detects the next zero-cross point where the magnitude relationship is reversed
Since it is output to the repeating means as a signal, the reference voltage
It is possible to remove noises that do not exceed the range, and it is possible to reduce the influence of noises.

[0071] In addition, the time interval of the past track record or past time
The signal cut-off means 6 is controlled with the set value based on the actual result of the interval difference as the initial value, and even in the first operation of the repeated operation, it is switched to the reception signal waiting state at the timing corresponding to the actual use state under the use condition. As a result, the period until the reception signal arrives is shortened, and the effect of reducing the influence of noise is obtained.

[0072] Also, the signal timing of interrupting means 6 is switched from the cutoff to the passing state is the positive direction, by being set to a timing suitable respectively opposite directions, the signal interrupting means 6 is interrupted at reaching earlier always received signal From the reception signal waiting state of the comparison means 8 to the arrival of the reception signal can be set to a short time both in the forward and reverse directions, and the effect of noise is lessened.

[0073] Further, shielding sectional control unit 13 a signal blocking means 6
Is switched from the interruption state to the passing state at the minimum value of the time measured by the third time measuring means 13b during the repeated operation or
By determining based on the maximum value , the signal cutoff means 6 is switched from the cutoff state to the passing state before the arrival of the received signal and at a timing without waste according to actual use, and the amplification means 7 and the comparison means 8 receive the signal. Since the period from the signal waiting state to the arrival of the received signal can be set to a short time, there is an effect that it is less susceptible to noise.

[0074] Further, timing signal interrupting means 6 is switched from the cutoff to the passing state is the positive direction, by being set to a timing suitable respectively opposite directions, the signal blocking means 6 reaches earlier always received signal cutoff From the reception signal waiting state of the comparison means 8 to the arrival of the reception signal can be set to a short time both in the forward and reverse directions, and the effect of noise is lessened.

Further , as the time counting time of the fourth time measuring means 13c at the beginning of the repetitive operation, the time measuring time of the last third time measuring means 13b at the time of flow rate measurement in the same direction of transmission and reception (forward direction or reverse direction) is used, The timing when the signal blocking means 6 is switched from the blocking state to the passing state is the same as the last timing when measuring the flow rate in the same direction of transmission and reception (forward direction or reverse direction).
In the continuous flow rate measuring operation, the period from the reception signal waiting state of the comparison means 8 to the arrival of the reception signal can be set to an optimum and short time, and there is an effect that it is less susceptible to noise.

[0076] Further, by using the average value of the measured time of the last third timing means 13b in continuing the flow rate measurement operation, from the received signal waiting state of the comparison means 8 without being affected by the erroneous measurement of the received signal The time until arrival can be set to an optimum and short time, and there is an effect that it is less likely to be affected by noise.

[0077]

As described above, according to the present invention, the reference voltage
It is possible to remove noise that does not exceed
It has the effect of making it less susceptible.

[Brief description of drawings]

FIG. 1 is a block diagram of a flow rate measuring device according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the device.

FIG. 3 is a block diagram of a flow rate measuring device according to a second embodiment of the present invention.

FIG. 4 is a diagram explaining the operation of the device.

FIG. 5 is a block diagram of a flow rate measuring device according to a third embodiment of the present invention.

FIG. 6 is a diagram for explaining the operation of the device.

FIG. 7 is a block diagram of a flow rate measuring device according to a fourth embodiment of the present invention.

FIG. 8 is a diagram for explaining the operation of the device.

FIG. 9 is a block diagram of a flow rate measuring device according to a fifth embodiment of the present invention.

FIG. 10 is a diagram illustrating the operation of the device.

FIG. 11 is a block diagram of a flow rate measuring device according to a sixth embodiment of the present invention.

FIG. 12 is a view for explaining the operation of the same device.

FIG. 13 is a block diagram of a flow rate measuring device according to a seventh embodiment of the present invention.

FIG. 14 is a view for explaining the operation of the same device.

FIG. 15 is a block diagram of a flow rate measuring device according to an eighth embodiment of the present invention.

FIG. 16 is a view for explaining the operation of the same device.

FIG. 17 is a block diagram of a conventional flow rate measuring device.

FIG. 18 is a view for explaining the operation of the same device.

[Explanation of symbols]

1 flow path 2 First ultrasonic transducer 3 Second ultrasonic transducer 4 switching means 5 Transmission means 6 amplification means 7 Signal blocking means 8 comparison means 9 Repeating means 10 First timing means 11 Flow rate calculating means 12 Control means 13 Break-off control means

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-10-73464 (JP, A) JP-A-56-164918 (JP, A) JP-A-61-107178 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G01F 1/00-9/02

Claims (7)

(57) [Claims] 1. A first oscillator and a second oscillator provided in a fluid conduit for transmitting and receiving ultrasonic signals, transmitting means for driving the oscillator, switching means for switching transmission and reception of the oscillator, and Repeating means for performing mutual ultrasonic wave transmission between the transducers a plurality of times, flow rate calculating means for calculating the flow rate based on the accumulated time of ultrasonic wave propagation, and signal cutoff for passing and blocking the reception signal of the receiving side transducer Means, a cutoff control means for controlling the signal cutoff means based on a repeating time interval of the repeating means, and a reception signal passing through the signal cutoff means.
Signal is compared with the reference voltage and the magnitude relationship is reversed.
Repeat the above with the zero-cross point as the zero-cross detection signal
A flow rate measuring device comprising a comparing means for outputting to a means . 2. An ultrasonic wave repeating time interval or time interval
The shutoff control hand is further provided with an interval storage means for storing the difference.
The stage is a time interval or time stored in the interval storage means.
2. The signal cutoff means is controlled based on the difference in distance.
The flow rate measuring device described in . 3. A first oscillator and a second oscillator provided in a fluid conduit for transmitting and receiving ultrasonic signals, transmitting means for driving the oscillator, and switching means for switching transmission and reception of the oscillator, Repeating means for performing mutual ultrasonic wave transmission between the vibrators a plurality of times, flow rate calculating means for calculating a flow rate based on the cumulative time of ultrasonic wave propagation, and setting for storing a set value for each transmission / reception direction of the vibrator. A flow rate measuring device comprising: a storage unit, a signal blocking unit that passes and blocks a received signal of a receiving-side transducer, and a blocking control unit that controls the signal blocking unit based on the setting storage unit. 4. An ultrasonic signal is transmitted and received in a fluid line.
To drive the first and second oscillators and the oscillator.
Switching means for switching between transmission and reception of the vibrator
And the ultrasonic wave transmission between the transducers is repeated multiple times.
The flow rate is calculated based on the return means and the cumulative time of ultrasonic wave propagation.
The flow rate calculation means to be output and the time set value are stored and received.
Signal interceptor that passes and intercepts the received signal of the receiver oscillator
Step and the minimum or maximum of the repetition time interval of ultrasonic transmission
Interval storage means for storing a value and the minimum or maximum value
The time setting value is updated based on the updated
The time setting value and the repeating time interval of the repeating means
An interruption control means for controlling the signal interruption means based on
A flow rate measuring device equipped . 5. further comprising an initial value storing means for the flow rate in the fluid conduit to store the repetition time interval of the ultrasonic transmission by repeating means when zero, the interruption control means, reverse
End of the positive direction repeat operation
Repeat time interval and repeat time when flow rate is zero
The flow rate measuring device according to claim 1, wherein the signal blocking unit is controlled based on the interval . 6. The latest value of the repetition time interval of ultrasonic transmission for each transmitting / receiving direction of the first transducer and the second transducer is a representative value.
And a representative value storage means for storing
The flow rate measuring device according to claim 1, wherein the control unit controls the signal blocking unit based on the representative value . 7. An average value of repetition time intervals of ultrasonic transmission is stored for each transmission / reception direction of the first transducer and the second transducer .
Mean value storing means further comprising a that, the interruption control means the
Claim 1 for controlling the signal blocking means on the basis of the average value
Flow rate measurement apparatus according to.