JP3458460B2 - 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 using ultrasonic waves.

[0002]

2. Description of the Related Art A conventional flow rate measuring device of this type is shown in FIG.
As shown in, for example, Japanese Patent Laid-Open No. 4-328424, ultrasonic transducers 2 and 3 are provided in a part of the fluid conduit 1 so as to face each other in the flow direction, and ultrasonic waves are transmitted from the transducer 1 in the flow direction. The velocity of the fluid was obtained from the difference between the time required to reach the oscillator 2 and the time required to generate the ultrasonic wave against the flow from the oscillator 2 and reach the oscillator 1, and determined the velocity of the fluid according to the cross-sectional area of passage. The flow rate was calculated by multiplying the correction factor.

[0003]

However, in the above-mentioned conventional flow rate measuring device, when the flow velocity is small with respect to the sonic velocity (340 m / sec for gas), for example, the time difference becomes extremely small when the flow velocity is 0.1 m / sec or less. Measurement accuracy cannot be increased. For this reason, it may be possible to reduce the diameter of the flow path or increase the distance between the vibrators, but it was difficult to put into practical use in terms of the size of the vibrator, the increase in generated power, and the pressure loss.

The present invention is intended to solve the above problems and has an object to measure a low flow rate with high accuracy.

[0005]

In order to achieve the above object, the flow rate measuring device of the present invention has the following configuration.

A movable body whose fluid opening changes according to the flow velocity, movable body position detecting means for detecting the position of the movable body, a first vibrator provided on the movable body, and the first vibration. A second oscillator that sends and receives a signal to and from a child, a timer that calculates a signal based on a signal transmission time difference between the two oscillators, and a flow rate is obtained from the signals of the movable body position detector and the timer. And a flow rate calculating means.

Further, a movable body in which the opening of the fluid changes according to the flow velocity, a temperature detecting means for detecting the temperature of the fluid, a first vibrator provided on the movable body, the first vibrator and a signal A second vibrator for transmitting and receiving the signal, and a clocking means for calculating a signal based on a mutual signal transmission time difference between the two vibrators,
The movable body position detecting means for obtaining the position of the movable body from the average value of the mutual signal transmission time between the oscillators and the signal of the temperature detecting means, and the flow rate from the signals of the movable body position detecting means and the clocking means. It is provided with a flow rate calculating means for obtaining.

[0008] a first transducer and second transducer opening of the fluid is respectively provided with a movable member that changes, upstream and downstream of the previous SL movable member in response to flow rate, the cross between the transducers Time measuring means for calculating a signal based on a signal transmission time difference,
A movable body position detecting means for obtaining a displacement amount of the movable body from an average value of mutual signal transmission times between the vibrators; and a flow rate calculating means for obtaining a flow rate from signals of the movable body position detecting means and the time measuring means. Be prepared.

A movable body whose fluid opening changes according to the flow velocity, a movable body position detecting means for detecting the position of the movable body, a first vibrator and a second oscillator provided on the movable body.
A vibrator, a timer for calculating a signal based on a signal transmission time difference between the two vibrators, a flow rate calculator for obtaining a flow rate from the movable body position detector, and the signal from the timer. Is.

Further, a movable body in which the opening of the fluid changes according to the flow velocity, a movable body position detecting means for detecting the position of the movable body, a first oscillator and a second oscillator for generating ultrasonic waves in the flow path. A vibrator, a timer for calculating a signal based on a signal transmission time difference between the two vibrators, a flow rate calculator for obtaining a flow rate from the movable body position detector, and the signal from the timer. Is.

The movable body is automatically moved by the pressure difference of the fluid or moved by an electric driving means, and holds its position during the operation of the vibrator.

Further, the movable body moves in a stepwise manner to a preset position.

[0013]

According to the present invention, the flow passage area is varied by the movable body, the flow velocity of the flow passage is calculated from the difference of the transmission time with respect to the flow of ultrasonic waves, and the flow rate is obtained from the position of the movable body and the flow velocity. Is.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a movable body 5 is rotatably attached in the middle of a fluid conduit 4, and the movable body 5 is provided with movable body position detecting means 6 such as an angle detector for detecting the position thereof. . A vibrator 7 for generating or receiving ultrasonic waves is fixed to the movable body 5, and a vibrator 8 facing the vibrator 7 is attached to the conduit 4. The ultrasonic wave generated from the vibrator 7 is received by the vibrator 8, and the ultrasonic wave transmitted from the vibrator 8 is received by the vibrator 7. Switching between oscillation and reception is performed by the switching means 9. That is, the ultrasonic wave generation means 11 is generated by the control signal of the controller 10.
Then, an ultrasonic wave is generated from the vibrator 8, the ultrasonic wave is received by the vibrator 7, and the time required to reach the controller 10 via the reception amplification means 12 is measured by the time measuring means 13.
After that, the transmission and reception of the vibrators 7 and 8 are reversely connected by the switching means, this time ultrasonic waves are transmitted from the vibrator 7 to the vibrator 8, the arrival time is obtained in the same manner as described above, and the flow rate calculation means 14 Calculate the flow rate value with.

When the sound in the stationary fluid is c and the velocity of the fluid flow is v, the propagation velocity of the ultrasonic wave in the forward direction of the flow is (c
+ V), and the propagation velocity in the opposite direction is (cv). Assuming that the distance between the transducers 7 and 8 is L and the angle formed by the ultrasonic wave propagation axis and the central axis of the conduit is φ, the times t1 and t2 at which the ultrasonic waves reach the forward direction and the reverse direction, respectively, are t1 = L / (c + vCOSφ) (1) t2 = L / (c-vCOSφ) (2), and from equations (1) and (2), v = L / 2COSφ (1 / t1-1 / t2) (3) If L and φ are known, the flow velocity v can be obtained by measuring t1 and t2.

From this flow velocity, the flow rate Q becomes Q = KSv (4), where S is the passage area and K is the correction count.

These t1 and t2 are obtained by the time measuring means 13, and the flow rate calculating means 14 calculates the flow rate in consideration of the flow passage cross-sectional area of the pipe 4 and the flow velocity distribution in the pipe. When the flow velocity is small, time t
Since the difference between 1 and t2 is very small, transmission and reception are repeated a plurality of times to perform signal processing with the integrated value.

Next, the operation will be described. When the flow velocity is low, the movable body 5 is located at the bottom of the figure due to its own weight, so that the fluid passage area is small as shown in FIG. As described above, the flow velocity is measured by measuring the transmission time of the ultrasonic wave from the transducer 7 to the transducer 8 and the transmission time from the transducer 8 to the transducer 7, obtaining the difference between the transmission times, and detecting the movable body position. The position of the movable body 5 is detected by the means 6 and L, φ and S are calculated, and the flow rate is calculated by the flow rate calculation means 14 by the equation (4). When the flow velocity increases, the movable body 5 moves upward due to the force of the flow as shown by the broken line 5 ', and the flow passage area increases.
The position of the movable body 5 at this time is detected by the movable body position detecting means 6, and L, φ and S in the moved state are obtained and the flow rate is calculated.

The movable body position detecting means 6 does not necessarily need to be provided with any special detecting means such as the angle detector shown in FIG. 2, but as shown in the second embodiment of the present invention in FIG. It is also possible by calculation. That is, equation (1) and equation (2)
When the average value of t1 and t2 is calculated from the formula, it becomes (t1 + t2) / 2 = L (c−vCOSφ) (5). Since c >> vCOSφ, L can be calculated, and the relation of φ to L is calculated in advance. The flow velocity can be calculated if this is done. In an environment where the temperature of the fluid changes significantly, as shown in FIG.
The accuracy can be further improved by providing a position at which the flow is not disturbed in the middle of the pipeline to correct the sound velocity.

FIG. 4 shows a third embodiment of the present invention in which fixed oscillators 7 and 8 are provided upstream and downstream of a movable body 5 having movable body position detecting means (not shown). 5, the passage area of the flow passage is changed according to the flow velocity, and the flow velocity at the passage portion is measured by ultrasonic waves as described above. In this case, since the distance between the vibrators 7 and 8 is constant, the sound velocity can be calculated from the average value of the transmission time by the equation (5), and the temperature of the fluid can be obtained from the sound velocity, so that the temperature correction becomes easy. Since the flow path area changes with the movement of the movable body 5, it is necessary to change the area term of the equation (4), but the flow velocity distribution also changes, so that the correction count also depends on the movement of the movable body 5. It is desirable to change.

FIGS. 5 and 6 show a fourth embodiment of the present invention, in which a sliding body 16 is mounted on a movable body 5 having a movable body position detecting means 6 with an upper end point 16a as a fulcrum.
The vibrators 7 and 8 are fixed on the sliding body 16. The fluid passes around the sliding body 16 as shown in FIG. 6, and when the movable body 5 moves in accordance with the flow velocity, the upper end point 16a of the sliding body 16a.
Moves along with it, and the lower end point 16b slides on the conduit 4 so that the area of the flow path changes. In this case as well, the oscillator 7,
Although the distance of 8 does not change, the area of the flow path and the flow velocity distribution change, so it is necessary to correct it.

In addition to the force of the fluid, the movable body 5 is guaranteed to operate more reliably if it is driven by the electric drive means 17 as shown in FIG. This electric drive means, like a step motor, whose position can be easily identified does not require any special movable body position detection means.

If the position of the movable body 5 changes during the operation of the vibrators 7 and 8, the calculation of the time measuring means will not be performed correctly.
It is better to hold that position. Therefore, it can be held by the electric driving means 17 as described above, or the attraction force can be utilized by using a magnet for the position detecting means. As shown in FIG. 8, if several magnets 18 are provided circumferentially, the position of the movable body 5 also changes digitally.

[0024]

As is apparent from the above description, the following effects can be obtained by the flow rate measuring device of the present invention.

(1) A movable body whose fluid opening changes according to the flow velocity, movable body position detection means for detecting the position of the movable body, a first vibrator provided on the movable body, and A second oscillator that transmits and receives a signal to and from the first oscillator, a clocking unit that calculates a signal based on a signal transmission time difference between the two oscillators, and a signal from the movable body position detecting unit and the clocking unit. Since it was equipped with a flow rate calculation means for obtaining the flow rate,
When the flow rate is small, the opening is small and the flow velocity is relatively large, so the flow rate detection accuracy is improved.When the flow rate is large, the opening is large and the flow velocity is not relatively large, and a large measurement range can be obtained. The maximum pressure loss is small. Further, since the flow rate is calculated according to the signal from the movable body position detecting means, the accurate flow rate can be measured without being affected by the operation accuracy of the movable body.

(2) Movable body whose fluid opening changes according to the flow velocity, temperature detecting means for detecting the temperature of the fluid, a first vibrator provided on the movable body, and the first vibrator. A second oscillator for transmitting and receiving a signal, a time measuring means for calculating a signal based on a mutual signal transmission time difference between the two oscillators, an average value of mutual signal transmission times between the oscillators, and the temperature detection. Since the movable body position detecting means for obtaining the position of the movable body from the signal of the means, and the flow rate calculating means for obtaining the flow rate from the signal of the movable body position detecting means and the timing means are provided, the distance between the transducers changes. However, since the distance is automatically calculated by the calculation of the ultrasonic wave transmission time, a special device for measuring the distance is not required, and the device can be constructed inexpensively and in a small size.

[0027] (3) a first transducer and second transducer opening of the fluid is respectively provided with a movable member that changes, upstream and downstream of the previous SL movable member in response to flow rate, between the transducers A clocking means for calculating a signal based on a mutual signal transmission time difference, a movable body position detecting means for obtaining a displacement amount of the movable body from an average value of mutual signal transmission times between the vibrators, and the movable body position detecting means. And the flow rate calculating means for obtaining the flow rate from the signal of the time measuring means, the opening is small for a small flow rate and the flow velocity is relatively large to improve the flow rate detection accuracy. Since the portion does not become large and the flow velocity does not become relatively large, a large measurement range can be obtained and the maximum pressure loss is small. Further, since the flow rate is calculated according to the signal of the movable body position detecting means, the accurate flow rate can be measured without being influenced by the operation accuracy of the movable body, and the position of the vibrator is fixed, so that the reliability is high.

(4) Movable body in which the opening of the fluid changes according to the flow velocity, movable body position detecting means for detecting the position of the movable body, first oscillator and second oscillator provided on the movable body. Since the vibrator is provided with a time measuring means for calculating a signal based on a mutual signal transmission time difference between the two vibrators, a flow rate calculating means for calculating a flow rate from the movable body position detecting means and the signal of the time measuring means. When the flow rate is small, the opening becomes smaller and the flow velocity becomes relatively high, improving the flow rate detection accuracy.
When the flow rate is large, the opening becomes large and the flow velocity does not become relatively large, so that a large measurement range can be obtained and the maximum pressure loss is small. Further, since the flow rate is calculated in accordance with the signal of the movable body position detecting means, the operation accuracy of the movable body is not affected, and since the transducer moves in accordance with the opening, ultrasonic waves can be operated throughout the opening. Accurate flow rate can be measured.

(5) Movable body whose fluid opening changes according to flow velocity, movable body position detecting means for detecting the position of the movable body, first oscillator for generating ultrasonic waves in the flow path, and A second oscillator; a timer for calculating a signal based on a signal transmission time difference between the two oscillators; and a flow rate calculator for obtaining a flow rate from the movable body position detector and the signal from the timer. Therefore, when the flow rate is small, the opening is small and the flow velocity is relatively large, so the flow rate detection accuracy is improved.When the flow rate is large, the opening is not large and the flow velocity is not relatively large. The maximum pressure loss can be small. Further, since the flow rate is calculated according to the signal from the movable body position detecting means, accurate measurement can be performed without being affected by the operation accuracy of the movable body.

(6) Since the movable body automatically moves according to the pressure difference of the fluid, it can be manufactured at low cost.

(7) Since the movable body is moved by the electric drive means, the operation can be ensured.

(8) Since the position of the movable body is held during the operation of the vibrator, the measurement error can be reduced.

(9) Since the movable body moves stepwise to a preset position, position detection can be performed digitally, and the arithmetic processing can be speeded up.

[Brief description of drawings]

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

FIG. 2 is a side view of a movable body of the device.

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

FIG. 4 is a partial configuration diagram of a flow rate measuring device according to a third embodiment of the present invention.

FIG. 5 is a partial configuration diagram of a flow rate measuring device according to a fourth embodiment of the present invention.

FIG. 6 is a side view of a movable body of the device.

FIG. 7 is a side view of a movable body according to a fifth embodiment of the present invention.

FIG. 8 is a configuration diagram of a movable body position detecting means according to a sixth embodiment of the present invention.

FIG. 9 is a block diagram of a conventional flow rate measuring device.

[Explanation of symbols]

5 movable body 6 Movable body position detection means 7 First transducer 8 Second oscillator 13 Timekeeping means 14 Flow rate calculation means 15 Temperature detection means 16 Electric drive means

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Fujieda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-53-95667 (JP, A) 72519 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01F 1/00-9/02

Claims (9)

(57) [Claims] 1. A movable body in which an opening of a fluid changes according to a flow velocity, movable body position detecting means for detecting a position of the movable body, a first vibrator provided on the movable body, and the first vibrator. A second oscillator that sends and receives a signal to and from one oscillator, a timer that calculates a signal based on a signal transmission time difference between the two oscillators, and a flow rate based on the signals of the movable body position detector and the timer. A flow rate measuring device comprising: 2. A movable body in which an opening of a fluid changes according to a flow velocity, a temperature detecting means for detecting a temperature of the fluid, a first vibrator provided on the movable body, and the first vibrator. A second oscillator that transmits and receives a signal, a time measuring unit that calculates a signal based on a mutual signal transmission time difference between the two oscillators, an average value of mutual signal transmission times between the oscillators, and the temperature detection unit. A flow rate measuring device comprising a movable body position detecting means for obtaining the position of the movable body from the signal, and a flow rate calculating means for obtaining a flow rate from the signal of the movable body position detecting means and the time measuring means. A movable body opening of the fluid is changed in accordance with claim 3] flow rate, the first oscillator and the second oscillator respectively provided upstream and downstream of the previous SL movable member, mutual between the transducers And a movable body position detecting means for obtaining a displacement amount of the movable body from an average value of mutual signal transmission times between the vibrators, and a movable body position detecting means. A flow rate measuring device comprising a flow rate calculating means for obtaining a flow rate from a signal of the time measuring means. 4. A movable body in which an opening of a fluid changes according to a flow velocity, a movable body position detecting means for detecting a position of the movable body, a first vibrator and a second vibration provided in the movable body. Flow rate measurement including a child, a time measuring means for calculating a signal based on a signal transmission time difference between the two vibrators, a flow rate calculating means for obtaining a flow rate from the movable body position detecting means and the signal of the time measuring means. apparatus. 5. A movable body in which an opening of a fluid changes in accordance with a flow velocity, a movable body position detecting means for detecting a position of the movable body, a first oscillator and an oscillator for generating ultrasonic waves in a flow path. Two oscillators, a timer for calculating a signal based on a signal transmission time difference between the two oscillators, a movable body position detector, and a flow rate calculator for obtaining a flow rate from the signals of the timer. Flow rate measuring device. 6. The flow rate measuring device according to claim 5, wherein the movable body is automatically opened and closed by a pressure difference of the fluid. 7. The flow rate measuring device according to claim 5, wherein the movable body is moved by an electric drive means. 8. The flow rate measuring device according to claim 5, wherein the movable body holds its position during operation of the vibrator. 9. The flow rate measuring device according to claim 5, wherein the movable body moves stepwise to a preset position.