JPH10213468A - Supersonic flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of power supply consumption in a battery drive system supersonic flowmeter. SOLUTION: Flow speed i.e., flow rate of supersonic wave is calculated in a calculating part 2a on the basis of a supersonic wave propagating time 101 measured by a flow speed measuring part 1a. The flow speed/flow rate data 201 outputted from the calculating part are supplied also to a control part 4a in addition to a display part 3a. A control signal 401 for transmission number of times performing the optimum setting of the measuring number of times for supersonic wave propagating time by a transmitting/receiving circuit 11a and a wave transmitter/receiver 12a, 12b on the basis of the flow speed/flow rate data 201 supplied in a control part 4a is supplied to a circuit 13 for controlling the transmitting number of times so that the optimum consumption of a power supply part 5 is ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flowmeter, and more particularly, to a gas flowed by being pumped through a sealed pipe.
Battery-driven ultrasonic flowmeter that measures the flow velocity of gas and liquid fluids such as water based on the transmission and reception of ultrasonic waves, and obtains the flow rate of the fluid based on the measured flow velocity, the cross-sectional area inside the tube, and the flow time. Belongs to.

[0002]

2. Description of the Related Art An ultrasonic flowmeter for measuring the flow rate of a fluid flowing through a pipe based on transmission and reception of ultrasonic waves has recently been frequently used in various application fields. FIG. 3 is a block diagram showing a configuration of a conventional ultrasonic flowmeter. The flow velocity measuring unit 1 for measuring the ultrasonic propagation time for a fluid, the flow velocity is obtained from the ultrasonic propagation time measured by the flow velocity measuring unit 1, and the flow velocity is calculated. , A calculation unit 2 for calculating the flow rate based on the sectional area inside the pipe and the flow time, a display unit 3 for displaying the flow velocity and flow rate data, which are the calculation results calculated by the calculation unit 2, in a predetermined display format, a predetermined control A control unit 4 that contains a program and controls the entire operation
And a power supply unit 5 using a battery for supplying power to each unit.

Next, the operation of the ultrasonic flowmeter shown in FIG. 3 will be described. The flow velocity measuring unit 1 that measures the ultrasonic propagation time in the fluid includes a pair of transducers 12 that are opposed to the fluid.
a, 12b and the transducers 12a,
A transmission / reception circuit that alternately sends ultrasonic pulses to 12b and repeatedly receives a transmission pulse sent to one of the transducers and receives the transmission pulse to the other transducer, and outputs a propagation time of the ultrasound to the fluid. The ultrasonic wave propagation time 101 is obtained and supplied to the calculation unit 2 as follows.

FIG. 4 is an explanatory diagram of the operation of the flow velocity measuring section 1 of FIG. A sealed diameter D through which the fluid is pumped and circulated
On the pipe wall of the pipe 1001 so that the center line C passes through the pipe axis A.
A pair of ultrasonic transducers 12a and 12b are disposed to face each other at an interval L. Now, if V is the flow velocity of the fluid in the direction of the tube axis A, and θ is the angle between the center line C and the tube axis A, D = L sin θ, and
Also, the velocity V _{L in} the center line direction of the flow velocity V = V cos θ.
Assuming that the propagation speed of the ultrasonic wave in the stationary fluid is V ₀ , the speed of the ultrasonic wave propagating from the transducer 12 b to the transducer 12 a is V ₀ + V cos θ, and the velocity of the ultrasound from the transducer 12 a to the transducer 12
The speed of the ultrasonic wave propagating in b is V ₀ −V cos θ. Therefore, when the ultrasonic wave propagation time which is sent towards the 12a from transducer 12b and t _1, the ultrasonic wave propagation time which is sent towards the 12b from transducer 12a and t _2, the following Equation 1, Equation 2 holds. Further, the following Expressions 3 and 4 are obtained from Expressions 1 and 2.

[0005]

(Equation 1)

[0006]

(Equation 2)

[0007]

(Equation 3)

[0008]

(Equation 4)

The flow velocity V to be obtained is 1 / t ₁ -1 / t ₂ =
Focusing on (2V cos θ) / L, it can be obtained as in the following Expression 5. The flow velocity V obtained in this manner is transmitted to the transducers 12a,
An average value obtained for a plurality of predetermined measurement points on the arrangement interval L of 12b is obtained, and this is referred to as a linear average flow velocity.

[0010]

(Equation 5)

The calculation unit 2 calculates the flow velocities V at a plurality of measurement points based on the data on the ultrasonic wave propagation time provided from the flow velocities measurement unit 1 based on the above-mentioned equations 1 to 5 to the transmitters / receivers 12a and 12b. Is obtained for each alternate transmission / reception of the ultrasonic pulse. The flow velocity (m
/ S) is converted to a cross-sectional average flow velocity in a cross section including the center line indicated by L in FIG. 4 and then multiplied by the cross-sectional area of the cross section to obtain a flow rate (m ³ / h, h is a unit time of measurement). )
Is required. The flow velocity / flow rate data 201 is displayed on the display unit 3 in a predetermined display format.

The control unit 4 controls the entire operation sequence by a built-in program, and measures the flow velocity and the flow rate every time the ultrasonic transducers 12a and 12b alternately transmit and receive ultrasonic pulses. The power supply unit 5 provides a power supply necessary for the operation of each unit. The ultrasonic wave propagation times t ₁ and t 1 in the flow velocity measuring unit 1
_For the measurement of ₂ , usually known sound speed correction by pressure data and temperature data for the fluid in the pipe is added,
Further, in order to improve measurement accuracy, there may be a case where two pairs of opposing transducers are symmetrically arranged.

[0013]

The above-mentioned conventional battery-driven ultrasonic flowmeter has the following problems. That is, in this type of conventional ultrasonic flow meter, measurement is performed at a constant measurement sampling interval set irrespective of the state of flow rate (flow velocity) to be measured. There is a problem that it is extremely low. For example, as shown in FIG. 6, if the measurement is performed at a constant measurement sampling interval of 5 times per second regardless of the flow velocity, and a single measurement consumes a power supply current of 500 μA (microampere), Consumes 2500 μA and therefore 9 A per hour
Is required unconditionally, and the operating efficiency of the power supply is
Irrespective of, it is suppressed to a low value.

An object of the present invention is to provide an ultrasonic flowmeter which can solve the above-mentioned problems and can significantly improve the operation efficiency of a battery power supply.

[0015]

The present invention has the following means in order to achieve the above object. That is, the ultrasonic flowmeter of the present invention uses a fluid that is pressure-fed inside the sealed pipe as a propagation medium, and shares a center line between the transducers disposed opposite to the pipe. In a battery-driven ultrasonic flowmeter that alternately transmits and receives ultrasonic pulses and measures the flow rate of the fluid, the number of transmissions of the ultrasonic pulse can be variably set in accordance with the flow rate of the fluid, There is provided a configuration including means for controlling the number of times of measurement of the flow rate of the fluid based on transmission and reception of the sound wave pulse in accordance with the flow rate of the fluid. Further, the ultrasonic flowmeter of the present invention has a configuration in which the fluid targets any one of a gas and a liquid.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a conventional ultrasonic flow meter of a battery drive type, a measurement sampling interval for measuring a flow rate is set to a fixed time irrespective of a flow rate.
For this reason, the operation efficiency of the drive battery of the conventional ultrasonic flowmeter has been suppressed to a low state determined at a constant measurement sampling interval. In the present invention, as shown in FIG. 1, the flow rate measuring unit 1a that measures the ultrasonic propagation time as a reference when obtaining the flow rate and thus the flow rate, the measurement sampling interval is variable according to the flow rate (flow rate). A transmission number control circuit 13 that makes the number of repetitions of the ultrasonic transmission pulse variable is provided so that the measurement sampling interval is controlled under the control of the control unit 4a based on the flow rate / flow rate data obtained by the calculation unit 2a. An embodiment of the invention is to adaptively control the flow rate (flow velocity).

[0017]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. The configuration of the embodiment shown in FIG. 1 is based on a flow velocity measuring unit 1 for obtaining an ultrasonic wave propagation time required for flow velocity measurement.
a, an arithmetic unit 2a for measuring the flow velocity and the flow rate based on the ultrasonic wave propagation time provided from the flow velocity measuring unit 1a, and a display unit 3a for displaying the flow velocity and the flow rate obtained by the arithmetic unit 2a in a predetermined display format. , A control program, and an arithmetic unit 2
a control unit 4a for controlling the entire operation sequence while controlling the number of transmissions of the ultrasonic pulse in the flow velocity measuring unit 1a and the measurement sampling interval based on the flow velocity and the flow rate data provided from a. And a power supply unit 5 for supplying.

Next, the operation of this embodiment will be described.
In the above-described configuration, components having the same reference numerals or the same reference numerals with the suffix a added thereto are all the same as the conventional configuration shown in FIG. 3 except for the content including the function of making the measurement sampling interval variable. Therefore, a detailed description of each operation regarding these same contents will be omitted. Flow velocity measuring unit 1a
The transmission frequency control circuit 13 is newly provided, thereby generating a transmission trigger 130 with a variable repetition interval, and determining the generation interval of the ultrasonic pulse by the transmission / reception circuit 11a, that is, the measurement sampling interval, between the power consumption and the flow rate measurement. Variable to ensure optimality.

The transmission number control circuit 13 is controlled by a transmission number control signal 401 provided from the control section 4a, and is capable of setting a transmission repetition number preset in accordance with the flow rate / flow rate of the fluid. 130 is transmitted to the transmission / reception circuit 11a. The control unit 4a transmits a transmission number control signal 401 for designating a desired number of transmissions based on the flow velocity / flow rate data 201 calculated by the arithmetic unit 2a based on the ultrasonic wave propagation time 101 provided from the flow velocity measuring unit 1a. 1
a.

FIG. 5 is a diagram showing an example of setting the number of times of measurement in the present embodiment. The flow rate (m / s) and the flow rate (m ³ /
Corresponding to h), the number of counts (times / s) is set in four stages of a, b, c and d, and the number of times of measurement is set to 5 (times / s) only when the flow velocity is 3 m / s or more. Indicates that In FIG. 5, the flow rate (m / s) is plotted on the horizontal axis as in FIG. 6, but the specific real number of the flow rate (m ³ / h) corresponding to these flow rates together with the flow rate is indicated by the display unit 3a and the control unit 4a. Respectively. The control unit 4a having received the flow rate / flow rate data 201 generates a transmission count control signal 401 for designating a measurement sampling interval corresponding to the provided flow rate or flow rate data, in this embodiment, the flow rate data under the control of a built-in program. Then, the data is transmitted to the transmission number control circuit 13.

FIG. 2 is a block diagram showing the configuration of the transmission number control circuit 13. The transmission number control circuit 13 shown in FIG.
In this embodiment, the transmission count table 131 stores the transmission count (pulse / s) for which the measurement count (count / s) is to be designated as shown in FIG. 5 corresponding to the flow rate in predetermined steps in this embodiment.
A transmission pulse control circuit 132 for transmitting a transmission pulse number control signal 1321 for performing transmission pulse number control based on the transmission number data 1301 read from the transmission number table 131; a reference clock generation circuit 133; The frequency of the reference clock 1331 sent from the generator 133 is divided,
A transmission trigger setting circuit 134 for outputting a transmission trigger 130 having a desired number of repetitions in accordance with the transmission pulse number control signal 1321.

Next, the operation of the transmission number control circuit 13 of FIG. 2 will be described. In accordance with the transmission number control signal 401 provided from the control unit 4a, transmission number data 1301 preset in accordance with the flow rate or the flow rate, in this embodiment, the flow rate is read from the transmission number table 131. The transmission trigger setting circuit 134 frequency-divides the reference clock provided from the reference clock generation circuit 133, further samples the frequency-divided clock with a time gate to generate a plurality of pulse trains of a desired repetition number, and A transmission trigger 130 is generated and output based on the The desired number of repetitions in this case is specified by the transmission pulse number control signal 1321.

In this way, the transmission trigger 130 in which the optimum number of repetitions corresponding to the flow velocity is set is obtained.
130 is provided to the transmission / reception circuit 11a, for example, measurement at the measurement sampling interval corresponding to the flow velocity as shown in FIG. 5 can be ensured, and extremely efficient battery operation becomes possible. For example, it is assumed that 500 μA is required for one measurement, and the number of measurements is 5 (times / s) when the flow velocity exceeds 3 (m / s) as shown in FIG. The current consumption in this case is 2500 μA / s, which is 9 A per hour. Further, when the flow velocity is 2 to 3 (m / s), the number of times of measurement is smaller than that in the case of 5 (times / s) from the viewpoint of maintaining the measurement accuracy in consideration of the time variation, and the number of times of measurement is 3 (times). / S) is sufficient, the current consumption in this case is 1500 μA / s and 5.
4A is enough.

When the flow rate is 1 to 2 (m / s) and the number of measurements is 2 (times / s) and the measurement accuracy is sufficient, the current consumption in this case is 1000 μA / s and 3 hours / hour. .6A
It is. When the flow rate is 0 to 1 (m / s) and the number of measurements is 0.5 (times / s), the current consumption in this case is 250 μA / s, which is 0.9 A per hour. Therefore, for example, the measurement sampling interval is set as shown in FIG.
Is 10%, the current consumption is (9A × 0.3) +
(5.4A × 0.3) + (3.6A × 0.3) + (0.
9A × 0.1) = 5.49 A, and the current consumption can be significantly reduced as compared with the case of FIG. 6 in which processing is performed with a fixed number of measurements regardless of the flow velocity.

[0025]

As described above, according to the present invention, in a battery-driven ultrasonic flowmeter, the power consumption efficiency is significantly improved by setting and operating a measurement sampling interval corresponding to a flow rate (flow rate). Has the effect of being able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ultrasonic flowmeter according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a transmission number control circuit of FIG. 1 in detail.

FIG. 3 is a block diagram showing a configuration of a conventional ultrasonic flowmeter.

FIG. 4 is an explanatory diagram of an operation of the flow velocity measuring unit 1a of FIG.

FIG. 5 is a diagram showing a setting example of the number of measurements of the ultrasonic flowmeter according to one embodiment of the present invention.

FIG. 6 is a diagram showing a setting example of the number of measurements of a conventional ultrasonic flowmeter.

[Explanation of symbols]

 1, 1a Flow velocity measuring unit 2, 2a arithmetic unit 3, 3a display unit 4, 4a control unit 5 power supply unit 11, 11a transmission / reception circuit 12a, 12b transmitter / receiver 13 transmission number control circuit 131 transmission number table 132 transmission pulse control circuit 133 Reference clock generation circuit 134 Transmission trigger setting circuit

Claims (2)

[Claims] An ultrasonic pulse is alternately transmitted between a plurality of transducers disposed opposite to the tube while sharing a center line by using a fluid flowing through the inside of the sealed tube under pressure as a propagation medium. In a battery-driven ultrasonic flowmeter that performs transmission and reception to measure the flow rate of the fluid, the number of transmissions of the ultrasonic pulse can be variably set in accordance with the flow rate of the fluid,
An ultrasonic flowmeter comprising means for controlling the number of times of measurement of the flow rate of the fluid based on the transmission and reception of the ultrasonic pulse in accordance with the flow rate of the fluid. 2. The ultrasonic flowmeter according to claim 1, wherein the fluid is one of a gas and a liquid.