JP2000298046A - Measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure items such as flowrate by suppressing the generation of Karman vortex of fluid around a measuring tube. SOLUTION: A flow measuring part 1 is separated with a partition wall 10 into an inflow chamber 11 and an outflow chamber 12 and a measuring tube 13 is provided in a state of penetrating the partition wall 10 in the flow measuring part 1. Around the measuring tube 13 of the inflow chamber 11, a straightener plate 14 for suppressing the generation of Karman vortex of fluid is provided. By this, the fluid flown into the inflow chamber 11 is arranged by the straightener 14 placed around the measuring tube 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device for measuring desired measurement items such as flow rates of gas and other fluids.

[0002]

2. Description of the Related Art Expected measurement items of gas and other fluids,
For example, when obtaining the flow rate of a fluid, first, the flow rate of the fluid is continuously or periodically measured, and the flow rate of the fluid is calculated based on the measured flow rate. As one method of measuring the flow rate of such a fluid, a method using ultrasonic waves is known.

The principle of such a method using ultrasonic waves will be described below with reference to a conventional apparatus shown in FIG. In FIG. 6, reference numeral (21) denotes a measuring pipe through which a fluid such as a gas flows. Ultrasonic transducers (2) and (3) are arranged in the measurement pipe (21) at a predetermined distance on the upstream side and the downstream side in the flow direction.

The ultrasonic vibrators (2) and (3) are driven by a driving pulse from a pulse generating circuit (4) to vibrate, generate and transmit ultrasonic waves, and receive transmitted ultrasonic waves. The received wave when the ultrasonic vibrators (2) and (3) vibrate is output as an electric signal from the amplifier circuit (5).

[0005] The propagation time until the ultrasonic wave transmitted from the upstream ultrasonic oscillator (2) in the forward direction with respect to the flow is received by the downstream ultrasonic oscillator (3); The difference between the ultrasonic wave transmitted from the downstream ultrasonic oscillator (3) in the opposite direction to the flow and the propagation time until the ultrasonic wave is received by the upstream ultrasonic oscillator (2) is related to the flow velocity. Therefore, in the arithmetic circuit (7), the flow velocity is measured based on the propagation time difference, and the flow rate is obtained based on the flow velocity. FIG.
In the above, (6) is a switching circuit for switching the connection between each of the ultrasonic transducers (2) and (3) and the pulse generating circuit (4) and the amplifier circuit (5). After connecting the ultrasonic transducer (2), the ultrasonic transducer (3) on the downstream side and the amplifier circuit (5) and measuring the propagation time from the upstream side to the downstream side, the switching circuit (6) The operation is switched so that the pulse generating circuit (4) is connected to the downstream ultrasonic oscillator (3), and the upstream ultrasonic oscillator (2) is connected to the amplifier circuit (5). It measures the propagation time to the side.

[0006] As a flow rate measuring apparatus utilizing the above-described ultrasonic waves, a flow rate measuring apparatus as shown in FIG. 7 has been proposed. In this flow rate measuring device, the inside of a flow rate measuring section (1) is partitioned into an inflow chamber (11) and an outflow chamber (12) by a partition wall (10), and the inflow chamber (11) is separated.
The inflow pipe (8) and the outflow pipe (9) are connected to the outflow chamber (12). A measuring pipe (13) is provided in the partition wall (10) so as to penetrate the partition wall (10), and the inflow chamber (11) and the outflow chamber (12) are communicated. .

The fluid flowing through the inflow pipe (8) flows into the inflow chamber (11) in a direction intersecting with the length direction of the measurement pipe (13), as indicated by a white arrow in FIG. The flow force in the inflow chamber (11) is reduced. Then, the fluid in the inflow chamber (11) whose flow momentum has been alleviated flows into the opening (11) of the measurement pipe (13) on the inflow chamber (11) side.
d), from the opening (11d) to the measuring tube (13)
Flows into. The fluid flowing into the measuring pipe (13) flows through the measuring pipe (13) from the inflow chamber (11) side to the outflow chamber (12) side, and the opening of the measuring pipe (13) on the outflow chamber (12) side. After flowing out of the part (11e) to the outflow chamber (12), it flows out to the outflow pipe (9) as it is.

The ultrasonic vibrators (2) and (3) are provided on the inner surfaces on both sides in the length direction of the flow rate measuring section (1), and the flow velocity of the fluid flowing through the measuring pipe (13) is provided. To
The measurement is performed by the method using the above-described ultrasonic wave, and the flow rate is obtained based on the flow velocity.

[0009]

However, as described above, if the fluid flows into the inflow chamber (11) in a direction intersecting with the length direction of the measuring pipe (13), the flow of the fluid is increased. Although relaxed, a so-called Karman vortex (P) was often generated around the measurement tube (13). For this reason, the flow of the fluid in the inflow chamber (11) is disturbed by the Karman vortex (P), and the flow rate of the fluid flowing into the measurement pipe (13) becomes unstable, so that the fluid flows in the measurement pipe (13). There was a problem that the flow rate of the fluid could not be determined accurately. And the problem concerning this structure is not only in the case of the flow rate measurement using the above-described ultrasonic waves, but also in the case of the flow rate measurement using other methods, or when measuring only the flow velocity,
This also occurs when measuring the temperature of the fluid and other measurement items.

The present invention has been made in view of the above-mentioned technical background, and can suppress the occurrence of Karman vortices of a fluid around a measurement pipe, and can therefore perform measurement of a measurement item such as a flow rate with high accuracy. It is an object of the present invention to provide a measurement device that can be performed well.

[0011]

According to the present invention, a fluid inflow chamber, one end of which faces the inflow chamber, and the other end of which faces the outside of the inflow chamber, and flows in the lengthwise direction into the inflow chamber. A measuring pipe arranged in a state intersecting with the inflow direction of the fluid to flow into the inflow chamber in a direction intersecting with the length direction of the measuring pipe, and then flowing out through the measuring pipe. A fluid measuring device configured to perform measurement on an expected measurement item while passing through the measurement tube, wherein a Karman vortex of the inflow fluid is generated around the measurement tube in the inflow chamber. A rectifying plate for suppression is provided.

According to this, the fluid that has flowed into the inflow chamber in a direction intersecting with the length direction of the measurement pipe is rectified by the rectifying plate provided around the measurement pipe. Generation of Karman vortices in the fluid is suppressed.

In the present invention, the term "intersection" means not only when the inflow direction of the fluid flowing into the inflow chamber and the length direction of the measurement tube intersect, but also in the inflow direction of the fluid flowing into the inflow chamber. And the length direction of the measuring tube is in a torsional relationship.

[0014]

1 and 2 are views showing a state in which a measuring device according to the present invention is applied to a flow measuring device using ultrasonic waves.

In FIG. 1, (1) is a flow rate measuring section for measuring a flow rate of a fluid, and an inflow pipe (8) through which the fluid flows.
And an outflow pipe (9) through which the fluid flows out is defined by the partition wall (1).
0). (2) and (3) are ultrasonic vibrators for transmitting and receiving ultrasonic waves. The ultrasonic vibrator transmits and receives ultrasonic waves.
They are provided so as to face each other. (4) is a pulse generation circuit that generates pulses for driving the ultrasonic transducers (2) and (3), and (5) is an amplifier that outputs a received wave received by the ultrasonic transducers (2) and (3). A circuit, (6) a switching circuit for switching the connection between the ultrasonic transducers (2) and (3) and the pulse generation circuit (4) and the amplification circuit (5), and (7) a fluid for the fluid based on the propagation time difference of the ultrasonic waves. An arithmetic circuit for determining the flow velocity and further the flow rate. In FIG. 1, the same parts as those shown in FIG. 7 are denoted by the same reference numerals.

The flow rate measuring section (1) is located at a position slightly closer to the ultrasonic vibrator (3) than the center in the longitudinal direction.
A partition wall (10) is provided over the entire cross section, and the left space where the ultrasonic vibrator (2) is provided serves as the inflow chamber (11), while the ultrasonic vibrator (3) is provided. The space on the right side is an outflow chamber (12). And the inflow chamber (11) of the flow rate measuring section (1)
An inflow pipe (8) is vertically connected to the upper wall at a position near the partition wall (10). For this reason,
The fluid flowing in the inflow pipe (8) is measured by the flow rate measuring unit (1).
Flows into the inflow chamber (11) from a direction perpendicular to the length direction of
The flow force is reduced in the inflow chamber (11). In addition, the upper wall of the flow measuring unit (1) on the side of the outflow chamber (12) has an outflow pipe (9) at the center of the outflow chamber (12).
Are connected vertically. For this reason, the fluid in the outflow chamber (12) flows upward through the outflow pipe (9) perpendicularly to the length direction of the flow rate measurement unit (1).

The central portion of the flow measuring section (1) has a longitudinal direction coinciding with the longitudinal direction of the flow measuring section (1) and a central portion of the partition wall (10). A measurement pipe (13) having a penetrating mode is provided, and the measurement pipe (1) is provided.
The inflow chamber (11) and the outflow chamber (12) are communicated by 3). As a result, the fluid stored in the inflow chamber (11) flows into the measurement pipe (13) from the opening (13d) of the measurement pipe (13) on the inflow chamber (11) side, and directly flows into the measurement pipe (13). The gas flows from the inflow chamber (11) to the outflow chamber (12), and flows out of the measurement tube (13) through the opening (13e) on the outflow chamber (12) side to the outflow chamber (12). At this time, the flow rate of the fluid flowing in the measurement pipe (13) is measured by a method using an ultrasonic wave, which will be described later, and the flow rate is determined based on the flow rate.

Both ends (13a) and (13b) of the measuring tube (13) in the longitudinal direction are formed in a horn shape having a circular cross section whose diameter increases toward the front end portion. Fluid smoothly flows into the measurement pipe (13), and the fluid in the measurement pipe (13) smoothly flows into the inflow chamber (1).
It flows out in 1). In addition, measurement pipe (1
The intermediate portion (13c) of 3) extends from the center portion to both end portions (13c).
a) It is formed on the inner surface whose diameter gradually decreases toward (13b), and most of the ultrasonic waves transmitted from the ultrasonic transducers (2) and (3) are reflected on the inner surface of the intermediate portion (13c). , And are received by the opposed ultrasonic transducers (3) and (2).

Also, the inflow chamber (11) of the flow rate measuring section (1).
In the center position in the width direction (the thickness direction of the paper surface of FIG. 1), there is a region where the measurement tube (13) exists, and a region between the ultrasonic transducer (2) and the measurement tube (13). The flow straightening plates (14) and (14) are connected to the measuring tube (1) over the entire vertical cross section except
3) It is provided vertically and vertically. The rectifying plate (14) rectifies the flow of fluid flowing from the inflow pipe (8) into the inflow chamber (11). More specifically, the fluid flowing through the inflow pipe (8) flows into the inflow chamber at the connection between the inflow pipe (8) and the flow measurement section (1) while being divided on both sides in the width direction of the flow measurement section (1). (11). After flowing along the side surface of the current plate (14) above the measurement tube (13), the outer peripheral surface of the measurement tube (13), and the side surface of the current plate below the measurement tube (13), respectively. The opening (1) of the measuring pipe (13) on the inflow chamber (11) side along the side surface of the straightening plate (14) as it is.
Since the fluid flows smoothly up to 3d), the generation of Karman vortex of the fluid around the measuring pipe (13) can be suppressed.

Next, a flow measurement method using the flow measurement device shown in FIG. 1 will be described.

First, when a fluid is supplied to the inflow pipe (8),
The fluid that has flowed through the inflow pipe (8) is connected to the inflow pipe (8) and the flow measurement section (1) by the flow measurement section (1).
Flows into the inflow chamber (11) while being divided on both sides in the width direction. Then, separately, the side surface of the rectifying plate (14) above the measuring tube (13), the outer peripheral surface of the measuring tube (13), and the side surface of the rectifying plate (14) below the measuring tube (13) are sequentially arranged. After flowing, the current plate (1) below the measuring tube (13)
It flows to the opening (13d) of the measuring tube (13) along 4). At this time, the flow of the fluid flowing into the inflow chamber (11) is reduced in the inflow chamber (11), and the flow of the fluid is reduced by the flow straightening plate (14) provided around the measurement pipe (13). By suppressing the generation of Karman vortices, it is possible to flow smoothly in the inflow chamber (11).

The inflow chamber (11) of the measuring pipe (13)
The fluid that has reached the opening (13d) on the side of the
3d) flows into the measurement pipe (13), flows through the measurement pipe (13) from the inflow chamber (11) side to the outflow chamber (12) side, and flows from the measurement pipe (13) to the outflow chamber (12) side. Opening (1
After flowing out of the outflow chamber (12) from 3e), it flows out to the outflow pipe (9).

In this state, when a pulse for driving the ultrasonic vibrator (2) is output from the pulse generating circuit in order to measure the flow rate of the fluid flowing in the measuring tube (13), the ultrasonic vibrator ( Ultrasonic waves corresponding to the vibration of 2) are transmitted. Most of the ultrasonic waves are received as they are by the ultrasonic transducer (3) facing the same, or after being reflected by the inner surface of the intermediate portion (13c) of the measuring tube (13), the ultrasonic waves on the outflow side are returned. Received by the vibrator (3).

Next, when the connection is switched by the switching circuit and the ultrasonic wave is transmitted from the ultrasonic vibrator (3), most of the ultrasonic wave is transmitted in the same manner as described above.
Is received.

The ultrasonic wave transmitted from the ultrasonic vibrator (2) on the inflow chamber (11) side in the forward direction by the arithmetic circuit (7) is transmitted to the supersonic wave on the outflow chamber (12) side. The propagation time until the ultrasonic wave is received by the ultrasonic oscillator (3) and the ultrasonic wave transmitted in the opposite direction to the flow from the ultrasonic oscillator (3) on the outflow chamber (12) side are transmitted to the inflow chamber (11). The flow velocity of the fluid flowing through the measurement pipe (13) is derived from the difference from the propagation time until reception by the ultrasonic transducer (2) on the side, and the flow rate in the measurement pipe (13) is further determined based on the flow velocity. Find the flow rate of the flowing fluid.

In the above embodiment, the current plate (1
4) The entire vertical cross-section of the inflow chamber (11) at the center in the width direction except for the region where the measurement tube (13) exists and the region between the ultrasonic transducer (2) and the measurement tube (13). However, the present invention is not limited to this, and the straightening plate (15) may be provided only below (or above) the measuring tube (13) as shown in FIG. Alternatively, the current plate may be provided in a part of the length of the measuring tube (13) in the longitudinal direction, for example, a current plate (16) may be provided at an intermediate portion of the measuring tube (13) as shown in FIG. Board (17) to partition wall (10)
To the opening (13d) of the measuring tube (13). In short, so that the generation of Karman vortex of the fluid around the measurement tube (13) can be suppressed,
The current plate may be provided at a predetermined location around the measurement tube (13).

Also, by connecting the inflow pipe (8) vertically to the flow rate measuring section (1), the fluid can flow into the inflow chamber (11) from a direction perpendicular to the measurement pipe (13). However, it is not always necessary to use a right angle.
3) Inflow the fluid in a direction intersecting the length direction with the inflow chamber (11)
Anything can be used as long as it can be flowed into.

The end (13b) of the measuring tube (13) faces the outflow chamber (12).
The end (13b) of 3) may be directly connected to the outflow pipe (9).

In addition to the flow rate measurement using the ultrasonic wave, the flow rate measurement may be performed using another method. Further, not only the flow rate but also other measurement items may be measured.

[0030]

The flow rate measuring device according to the present invention is characterized in that a rectifying plate for suppressing the generation of Karman vortex of the inflowing fluid is provided around the measurement pipe in the inflow chamber. Fluid flowing into the inflow chamber in a direction intersecting with the length direction of the pipe is rectified by a rectifying plate provided around the measurement pipe, thereby suppressing generation of Karman vortex of the fluid around the measurement pipe. . Therefore, the fluid in the inflow chamber smoothly flows into the measurement pipe without being disturbed by the Karman vortex, so that it is possible to accurately measure the measurement items such as the flow rate of the fluid.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a flow measurement device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the flow measurement device of FIG.

FIG. 3 is a schematic configuration diagram showing a flow rate measuring device in which a current plate is provided below a measuring pipe.

FIG. 4 is a schematic configuration diagram showing a flow rate measuring device in which a current plate is provided at an intermediate portion of a measuring pipe.

FIG. 5 is a schematic configuration diagram showing a flow rate measuring device in which a flow straightening plate is provided at a portion extending from a partition wall to an opening of a measuring pipe.

FIG. 6 is a schematic configuration diagram for explaining an ultrasonic flow velocity measuring method.

FIG. 7 is a schematic configuration diagram showing a conventional flow measurement device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Flow measurement part 2, 3 ... Ultrasonic vibrator 8 ... Inflow pipe 9 ... Outflow pipe 10 ... Partition wall 11 ... Inflow chamber 12 ... Outflow chamber 13 ...・ Measurement tube 14 ・ ・ ・ Rectifier plate

Claims (1)

[Claims] A fluid inflow chamber having one end facing the inflow chamber and the other end facing the outside of the inflow chamber;
A measuring pipe arranged in a state intersecting the length direction with respect to the inflow direction of the fluid flowing into the inflow chamber, after flowing into the inflow chamber in a direction intersecting with the length direction of the measurement pipe, A fluid measuring device configured to measure a desired measurement item while passing through the measurement tube, for a fluid flowing out of the measurement tube, and around the measurement tube in the inflow chamber. A flow rectifying plate for suppressing generation of Karman vortices in the inflow fluid.