JP5229105B2 - Flow measuring device - Google Patents

Description

  The present invention relates to a flow rate measuring apparatus that measures the flow rate of a fluid such as gas or water using ultrasonic waves.

  Conventionally, this type of ultrasonic flow measuring device has a configuration in which a measurement channel 52 for measuring a part of the fluid is installed in a main channel 51 through which the measurement fluid flows, as shown in FIG. It was.

  In this configuration, the flow rate divided in the measurement flow path 52 is measured, and the flow rate flowing in the main pipe flow path is obtained by calculation with a diversion ratio with the preset overall flow rate. There is a possibility that the flow of the entire pipe can be measured with a measurement system that is a measurement range (see, for example, Patent Document 1 and Patent Document 2).

JP 2004-251686 A JP 2005-140729 A

  However, in the conventional configuration, when the flow rate flowing into the measurement flow path 52 exceeds the upper limit that can be measured in the measurement flow path 52, measurement is impossible. There was a problem of being restricted.

  The present invention solves the above-described conventional problems, and enables reliable measurement over a wide range.

  In order to solve the above-described conventional problems, a flow rate measuring device according to the present invention includes a fluid channel, a measurement channel into which a part of the fluid flowing through the fluid channel flows, and a flow rate of the fluid flowing through the measurement channel. It is the structure which has a measurement means to measure, and a fluid diversion means which controls the fluid quantity which flows into a measurement flow path.

  Therefore, since the amount of fluid flowing into the measurement channel is variable, a wide range of measurements can be performed.

  The flow measuring device of the present invention can control the amount of so-called side flow flowing in the measurement flow path by the fluid diversion means, and can reliably measure even if the main flow flowing in the fluid flow path is a large flow rate. It becomes. Furthermore, because the flow splitting means can optimize the split ratio of the main flow and the secondary flow, it has the versatility that the design can be easily changed even if the pipe diameter of the fluid flow path in which the main flow flows is different with the same measurement flow path. It is something that can be done.

The longitudinal cross-sectional view of the flow measuring device which shows embodiment of this invention Cross-sectional side view of the same flow measurement device AA front sectional view of FIG. BB front sectional view of FIG. System configuration diagram of the same flow measurement device Explanatory drawing of measuring means part in the same flow measuring device Operation explanatory diagram of the flow rate measuring device Vertical sectional view showing a modification of the flow rate measuring device Action explanatory drawing in the modification of the same flow measuring device Vertical sectional view showing another modification of the flow rate measuring device AA front sectional view of FIG. Schematic configuration diagram of a conventional flow measurement device

The present invention includes a fluid flow channel, a measurement flow channel provided in the fluid flow channel, in which a part of the fluid flowing through the fluid flow channel is shunted, and a measurement unit that measures the flow rate of the fluid flowing through the measurement flow channel. And fluid diverting means for controlling the flow rate of the fluid flowing into the measurement channel with a baffle plate configured to be movable , and the measurement plate is provided on both the upstream side and the downstream side of the measurement channel. A certain distance from the flow path
It is possible to measure under a wide range of flow rates by controlling the amount of fluid diverted to the measurement flow path via the fluid diverting means.

  The fluid diverting means is preferably movable, and in addition, its configuration is set so as to obstruct the flow of the fluid.

  It is also conceivable to arrange the fluid diversion means on both the upstream side and the downstream side of the measurement channel so that both the normal flow and the reverse flow can be measured.

  If the measurement channel is placed concentrically inside the fluid channel via a support member, it will be easy to connect to the external piping, and it will be easy to support around the measurement channel. It becomes easier to ensure the mainstream objectability with respect to the secondary flow, and it becomes possible to stably ensure higher measurement accuracy.

  In addition, if the support member, the measurement channel, and the fluid channel are provided as separate members, even if the inner diameter of the fluid channel is changed, it can be dealt with only by changing the support member as long as it is larger than the measurement channel can be accommodated. Is.

  In this case, if a shielding plate that blocks at least the peripheral flow covering the projection surface in the direction of the fluid flow of the measurement flow path, excluding the measurement flow path opening in the measurement flow path, is provided. Since the fluid does not flow into any part other than the opening, there are no problems such as breakage due to the flow to the measurement channel, the reliability of the measurement device is improved, and the flow channel is affected regardless of the shape of the measurement channel. Contributes to ensuring stable measurement accuracy.

  Furthermore, if a rectifying member is placed between the fluid diversion means and the measurement flow path, stable measurement is possible even if there is a large amount of drift in the fluid flowing into the measurement flow path, and high-precision measurement is always possible. Become.

  By using the ultrasonic method as the measurement means, it is possible to perform high-accuracy measurement with a wider range capability, and because it enables measurement with a short sampling time, it can also be used for applications that require instantaneous measurement. It becomes possible. It is also possible to measure backflow.

  Embodiments of the present invention will be described below with reference to the drawings. The embodiments do not limit the present invention.

(Embodiment 1)
In FIG. 1 to FIG. 4, a measurement channel 3 is provided in a fluid channel 1 through which a fluid to be measured flows via a support member 2, and a part of the fluid is divided into the measurement channel 3. I have to.

  The fluid flow path 1 has a circular cross section, the measurement flow path 3 has a rectangular cross section, and is set so that the measurement flow path 3 is located at the center of the measurement flow path 3.

  Measuring means 4 is arranged in the measurement channel 3. This measuring means 4 has a pair of ultrasonic transmitters / receivers 5, 6 provided on the measurement channel 3 and on the opposite wall portion on the downstream side, so that the ultrasonic waves obliquely cross the fluid flowing through the measurement channel 3. It is.

  Fluid diverting means 7 and 8 are provided inside the fluid flow path 1 and at a predetermined distance from the downstream end opening above the measurement flow path 3.

  The fluid diverting means 7 and 8 are arranged on both the upstream side and the downstream side because not only the so-called forward flow in which the fluid flows through the fluid flow path 1 in the left-hand direction in FIG. In order to cope with this, the fluid flowing in the fluid flow path 1 is diverted by the fluid diversion means 7 or 8 and flows into the measurement flow path 3 as a diversion fluid.

  As shown in FIG. 5, the signal of the measuring means 4, that is, the ultrasonic propagation time signal between the ultrasonic transmitters / receivers 5 and 6, is input to the calculating means 9 described later, and the flow rate of the fluid flowing through the measurement flow path 3. Is calculated.

  The flow rate of the measurement flow path 3 corresponding to the diversion ratio is calculated from the obtained flow rate and the correction value registered in advance in the registration unit 10 and shown in the display unit 11. Is in charge.

  In this embodiment, the result is displayed on the display means. However, the measurement result may be output to a data logger as numerical data, or equipped with a wireless system or wired data transfer function. It is also possible to output at the location.

  The operation will be described below.

  First, the measuring means 4 will be described with reference to FIG.

  The measuring means 4 alternately transmits and receives ultrasonic waves between the ultrasonic transmitters and receivers 5 and 6, and measures the difference in the propagation time of ultrasonic waves in the forward direction and the reverse direction with respect to the flow of the fluid at regular intervals. It has the function of outputting as a propagation time difference signal. The calculation means 9 receives the propagation time difference signal and calculates the flow velocity and flow rate of the fluid to be measured.

  More specifically, in FIG. 6, L is the distance between the ultrasonic transceivers 5 and 6, T1 is the transmission time from the upstream, T2 is the transmission time from the downstream, C is the speed of sound, φ is the fluid velocity in the measurement channel 3 When the angle formed by the ultrasonic wave propagation direction with respect to the flow direction and the flow velocity are V, the flow velocity V is calculated by the following equation.

T1 = L / (C + Vcosφ) (1)
T2 = L / (C-Vcosφ) (2)
The speed of sound C is eliminated from the equation for subtracting the reciprocal of T2 from the reciprocal of T1, and V = (L / 2 cos φ) [(1 / T1) − (1 / T2)] (3)
Since φ and L are known, the flow velocity V can be calculated from the values of T1 and T2. Now, for example, considering measuring the flow rate of air, angle φ = 45 degrees, distance L = 35 mm, sound velocity C = 340 m / s
Assuming a flow velocity V = 8 m / s, T1 = 2.0 × 10 ⁻⁴ seconds and T2 = 2.1 × 10 ⁻⁴ seconds, and instantaneous measurement can be performed.

  The operation of the flow rate measuring apparatus configured as described above will be described below with reference to FIG.

  As shown in FIG. 7, the measurement fluid flowing into the fluid flow path 1 is divided by the fluid diverting means 7 into the substream B flowing through the measurement flow path 3 and the other main flow A.

  In the above-described measurement method using ultrasonic waves, when the flow velocity of the ultrasonic wave propagation portion is increased, there is a measurement limit due to the influence of flow disturbance.

  Although the measurement limit varies depending on the configuration of the measurement unit, in order to measure a larger flow rate, it is necessary to enlarge the measurement unit itself and review the device parts such as sensors, and prepare measurement means corresponding to the range of the measurement flow rate. Will have to do.

  In the diversion method according to the present embodiment, the side flow B flowing to the measurement flow path 3 is diverted from the main flow A by the baffle plate action of the fluid diversion means 7, and the flow of the side flow B is measured by the measurement means 4 according to the diversion ratio. Since it can be suppressed to the limit value or less, it is not necessary to review the specification of the measuring means 4 by changing the shunt ratio even if the specification of the measurement range as the measuring device is changed.

  In the above description, the upstream fluid diverting means 7 has been described. However, when the fluid flow is reversed, the downstream fluid diverting means 8 performs the same operation.

  Also, as shown in FIGS. 8 and 9, the baffle plates 7a and 8a are movably arranged in the fluid diverting means 7 and 8, so that the diversion ratio can be arbitrarily changed, and the flow rate can be measured with one measuring device. A wide range of measurements is possible by switching the range.

  The movement of the baffle plates 7a and 8a is achieved by transmitting the rotation of a motor (not shown) with a belt and changing their mounting angle, but the drive mechanism is not limited to this.

  As shown in FIGS. 2 and 4, the support member 2 that supports the measurement flow path 3 has a shape that is inscribed in the fluid flow path 1 and covers the front and rear of the measurement means 4, and thus serves as a flow shielding plate. Since there is no flow other than the opening of the path 3 (portion where the side flow B flows), there is no influence on the flow due to the shape of the measuring means 4, and the wires such as the ultrasonic transmitters / receivers 5 and 6 are in the flow. It is trying not to affect.

  Furthermore, the present invention can be applied to a case where the diameter of the fluid flow path 1 is different only by exchanging the support member 2, and the compatibility can be enhanced.

  In addition, by providing the fluid diverting means 7 and 8 having a baffle plate configuration, even if foreign matter flows into the fluid flow path 1, the rate of inflow into the measurement flow path 3 is reduced, and the life and reliability of the measuring means are improved. Improvements can be made.

  As shown in FIGS. 10 and 11, by inserting rectifying members 13 and 14 between the fluid diverting means 7 and 8 and the measurement flow path 3, the measurement flow path can be obtained even when the flowing-in flow is very disturbed. 3 can be suppressed, and accurate measurement is possible under any piping conditions.

  The rectifying members 13 and 14 are optimally porous bodies, for example, honeycomb-shaped porous bodies.

  As described above, according to the present invention, it is possible to perform reliable measurement even when the main flow through the fluid flow path is a large flow rate, and the diversion ratio between the main flow and the side flow can be optimized by the fluid diversion means. It is possible to provide a versatile flow rate measuring device that can easily change the design even if the measurement flow channel has a different diameter of the measurement flow channel.

DESCRIPTION OF SYMBOLS 1 Fluid flow path 3 Measurement flow path 4 Measuring means 5,6 Ultrasonic transmitter / receiver 2 Support member 7,8 Fluid diversion means 7a, 8b Baffle plate 13,14 Rectification member

Claims (5)

A fluid flow path;
A measurement flow path provided in the fluid flow path, in which a part of the fluid flowing through the fluid flow path is diverted;
Measuring means for measuring the flow velocity and / or flow rate of the fluid flowing through the measurement channel;
Fluid diversion means for controlling the flow rate of the fluid flowing into the measurement flow path with a baffle plate configured to be movable ;
A fluid flow measuring device in which the baffle plate is arranged at a predetermined distance from the measurement channel on both the upstream and downstream sides of the measurement channel . The fluid flow measuring device according to claim 1 , wherein the measurement flow path is concentrically arranged inside the fluid flow path via a support member. The flow rate measuring device according to claim 2, wherein the support member, the measurement channel, and the fluid channel are separate members. The fluid flow measuring device according to any one of claims 1 to 3 , wherein a rectifying member is disposed between the fluid diverting means and the measurement flow path. The fluid flow measuring device according to any one of claims 1 to 4 , wherein the measuring means uses an ultrasonic transceiver.

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