JP7643932B2 - Flow Meter - Google Patents

Description

The present invention relates to a flow meter.

In recent years, there have been many instances of torrential rain, often referred to as "guerilla downpours," causing problems such as overflowing of urban stormwater drainage infrastructure. As a result, measures have been taken to reduce the amount of stormwater that flows into public sewer pipes by installing facilities in buildings that temporarily store stormwater, such as infiltration pits and stormwater storage tanks (hereinafter referred to as "temporary storage facilities").

In order to make effective use of these temporary storage facilities, it is necessary to install a flow meter in the pipeline into which storm water flows.
As a relatively simple and inexpensive flow meter, there is a known impeller type flow meter that is installed in a pipeline and utilizes the dynamic pressure of the fluid. However, the impeller can easily become entangled with foreign matter in rainwater, hindering the original function of the pipeline. In addition, because the impeller rotates continuously, there is also the problem that the bearings are easily worn out.

There are flow meters that can measure the flow rate without coming into contact with the fluid in the pipeline, such as non-contact ultrasonic flow meters, but they are not easy to install because they require a straight pipe section of a certain length (about 10 times the diameter), the pipe must be filled with water (liquid), and they are expensive.
Therefore, Patent Document 1 proposes a simple flow meter in which a wing that exerts lift when a fluid flows through it is installed inside a pipeline, and the force acting on a stay that holds the wing is detected by a load cell.

Japanese Patent Application Publication No. 9-26338

However, the flowmeter in Patent Document 1 also has a complex structure for holding the wings on the stay, and requires the placement of a straightening vane on the upstream side, so it is still difficult to say that it has a simple structure. In addition, the flowmeter in Patent Document 1 cannot measure the flow rate unless the pipe is full of water (liquid) or close to being full of water (liquid). For this reason, it is unsuitable as a flowmeter to be installed in a pipe where water flows in irregularly, such as rainwater, and where the flow rate fluctuates widely.

The present invention was made in consideration of the above circumstances, and aims to provide a flowmeter with a simple structure that is less likely to cause problems such as entanglement of foreign matter. Another aim is to provide a flowmeter that can measure the flow rate even in a pipeline where a fluid flows irregularly and where the flow rate fluctuates widely.

In order to achieve the above object, the present invention employs the following configuration.
[1] A flowmeter for measuring a flow rate of a fluid flowing through a pipeline laid substantially horizontally, comprising:
a sensor attached to the upper part of the pipeline to convert a load into an electric signal; an electric signal processing device that determines a flow rate from the electric signal obtained by the sensor; and a pressure receiving part that is connected at one end to the sensor and transmits the dynamic pressure of the fluid flowing in the pipeline to the sensor,
the pressure receiving portion has a weight portion and a flexible connecting wire connecting the weight portion to the sensor,
the weight portion is connected to the sensor by the connecting wire so as to be able to come into contact with a bottom surface of the pipeline, at least a portion of the weight portion that can come into contact with the bottom surface of the pipeline is a convex curved surface, and when subjected to dynamic pressure of a fluid flowing through the pipeline, the weight portion floats and attempts to move along with the flow of the fluid, thereby applying a moment load to the sensor through the connecting wire.
[2] The flow meter according to [1], wherein the weight portion is spherical.
[3] The flowmeter according to [1] or [2], wherein the fluid is water and the specific gravity of the weight portion is 7 to 9.
[4] The flow meter according to [3], wherein the fluid is rainwater.
[5] The flowmeter according to any one of [1] to [4], wherein the weight portion is made of stainless steel.
[6] The flow meter according to any one of [1] to [5], wherein the sensor has a conversion unit that converts a moment load applied through the connecting wire into a uniaxial load, and a load cell that converts the uniaxial load into an electrical signal.

The flowmeter of the present invention has a simple structure and is less susceptible to problems such as entanglement of foreign matter, and can measure flow rates even in pipelines where fluid flows irregularly and where the flow rate fluctuates widely.

1 is a schematic configuration diagram of a flow meter according to an embodiment of the present invention;

A flow meter according to an embodiment of the present invention will be described with reference to FIG.
The flowmeter 1 of this embodiment is a flowmeter that measures the flow rate of a fluid flowing through a pipeline 50 that is laid substantially horizontally, and is roughly composed of a sensor 10, an electric signal processing device 20, and a pressure receiving portion 30.

The pipeline 50 is laid substantially horizontally. Here, substantially horizontal means that the inner wall of the pipeline 50 is horizontal or close to horizontal, allowing the top surface 51 and the bottom surface 52 to be conceived as being at different vertical positions, to the extent that even if a fluid flows toward the bottom surface 52, the fluid does not reach the top surface 51. For example, an inclination to the extent that promotes the movement of the fluid in the pipeline 50 is permitted. Rather than being completely horizontal, it is preferable that the pipeline 50 has an inclination (water gradient) to the extent that promotes the movement of the fluid in the pipeline 50. The inclination of the pipeline 50 from the horizontal can be, for example, 2 to 3 degrees.
The cross-sectional shape of the pipe 50 is not particularly limited, and may be circular, rectangular, inverted trapezoidal, or the like.

The sensor 10 is composed of a mounting plate 11 fixed to the top surface 51 of the inner wall of the pipeline 50, a load cell 12 fixed to the underside of the mounting plate 11, and an L-shaped conversion part 13 with one end fixed to the mounting plate 11 by a hinge part 14. The conversion part 13 rotates clockwise around the hinge part 14 as the axis of rotation, so that the end opposite the end fixed to the hinge part 14 applies lateral pressure upward on the load cell 12.

In the present invention, the sensor 10 is attached above the pipeline 50. By attaching it above, it can be kept out of contact with the fluid at all times, making maintenance easy.
In this embodiment, the location where the sensor 10 is fixed is the highest part (top surface 51) of the inner wall of the pipeline 50, which is particularly preferable.

In this embodiment, an example is shown in which a load cell that converts a uniaxial load into an electrical signal (for example, a voltage) is used as the load cell 12.
There is no particular limitation on the type of load cell that converts the uniaxial load into an electrical signal, and it is possible to use a small compression type load cell, a spring type or piezoelectric type load cell, a magnetostrictive type load cell, a capacitance type load cell, a gyro type load cell, a strain gauge type load cell, etc. Among these, a small compression type load cell is preferred because it is easy to install inside the pipe.
The electrical signal processing device 20 is connected to the load cell 12 via a signal line 21, and receives the electrical signal obtained by the load cell 12.

The pressure receiving portion 30 is composed of a weight portion 31 and a flexible connecting wire 32 .
One end of the connecting wire 32 is attached to the weight portion 31 and the other end is attached to the conversion portion 13 of the sensor 10 , thereby connecting the weight portion 31 to the sensor 10 .
There is no particular limitation on the specific form of the connecting wire 32, as long as it has flexibility and strength to connect the weight portion 31 to the sensor 10 against the flow of the fluid. For example, it may be in the form of a string, a band, a chain, or the like. The material of the connecting wire 32 is preferably a material that is resistant to the fluid. When the fluid is water, for example, the connecting wire may be stainless steel (SUS), iron, or the like.

The connecting wire 32 is formed longer than the height from the bottom surface 52 to the top surface 51 of the inner surface of the pipeline 50. As a result, the weight portion 31 is connected to the sensor 10 by the connecting wire 32 so as to be able to contact the bottom surface 52 of the pipeline 50. Therefore, when there is no fluid or no fluid flow, the weight portion 31 sinks to the bottom surface 52 of the inner surface of the pipeline 50 and contacts the bottom surface 52, and when there is a fluid flow, the weight portion 31 floats and separates from the bottom surface 52 due to the dynamic pressure of the fluid, and is able to move along with the flow of the fluid within the range allowed by the restraint by the connecting wire 32.

In FIG. 1, the weight 31 is spherical, but it is sufficient that the portion that can come into contact with the bottom surface 52 is a convex curved surface. By making the portion that can come into contact with the bottom surface 52 a convex curved surface, friction with the bottom surface 52 is reduced, and the weight can be quickly lifted from a state where it is submerged on the bottom surface 52 (a state where it is in contact with the bottom surface 52) by the dynamic pressure of the fluid.

Examples of shapes in which the portion in contact with the bottom surface 52 is a convex curved surface include a spherical shape, a long spheroid shape, an oblate ellipsoid shape, a teardrop shape, etc. Among these, a spherical shape is preferable because it is easy to remove dirt that flows into the tube.
When weight portion 31 is spherical, the diameter is preferably 2 to 3 cm, but when the pipe diameter exceeds 100 mm, the diameter is preferably 3 cm or more. By setting the diameter of weight portion 31 to the lower limit of the preferred range or more, the dynamic pressure of the fluid can be sufficiently received. By setting the diameter of weight portion 31 to the upper limit of the preferred range or less, the weight portion 31 can be used even in a narrow pipe.

When the fluid is water, the specific gravity of the weight portion 31 is preferably 7 to 9, more preferably 7.5 to 8.5, and particularly preferably about 8. By having the specific gravity of the weight portion 31 at or above the lower limit of the preferred range, it can quickly sink toward the bottom surface 52 and return to a state of contact with the bottom surface 52 when the amount of water decreases. It can also avoid unstable movement due to water currents.

Since the specific gravity of weight portion 31 is equal to or less than the upper limit of the preferred range, it tends to float even when the flow rate is small, making it possible to measure the flow rate.
The material of the weight portion 31 is preferably a material that has an appropriate specific gravity and is resistant to the fluid. When the fluid is water, for example, stainless steel (SUS), iron, etc. can be used.

In the flowmeter 1 of this embodiment, when no fluid is present or flowing in the pipeline 50, the weight 31 is in contact with the bottom surface 52. At this time, the connecting wire 32 is in a loose state between the weight 31 and the sensor 10. In other words, the weight 31 does not apply tension to the connecting wire 32, and does not apply a moment load to the sensor 10 through the connecting wire 32.

At this time, the conversion section 13 of the sensor 10 hangs down below the hinge section 14, does not apply lateral pressure to the load cell 12, and the load cell 12 does not detect the load. In other words, the load cell 12 does not output an electrical signal corresponding to the dynamic pressure F along the flow direction to the electrical signal processing device 20, so the electrical signal processing device 20 can determine that the flow rate is zero.

On the other hand, when a fluid flows through the pipe 50, the weight 31 floats away from the bottom surface 52 due to the dynamic pressure F of the fluid, and moves along with the flow of the fluid within the range of the restraint by the connecting wire 32. Then, when the limit of the restraint by the connecting wire 32 is reached, a moment load is applied to the sensor 10 through the connecting wire 32.

Specifically, the limit of constraint by the connecting line 32 refers to the point at which the movement of the weight portion 31 causes the conversion portion 13 of the sensor 10 to rotate clockwise from the state where it hangs down below the hinge portion 14 and come into contact with the load cell 12.
Thereafter, weight portion 31 applies a tension corresponding to the dynamic pressure F to connecting wire 32, and applies a moment load about hinge portion 14 as an axis to sensor 10. The moment load applied to sensor 10 is converted into a uniaxial load by conversion portion 13 and applied to load cell 12. As a result, load cell 12 outputs an electrical signal corresponding to the dynamic pressure F to electrical signal processing device 20 via signal line 21.

The electrical signal processing device 20 determines the approximate flow rate based on the electrical signal input from the load cell 12 .
Specifically, the flow rate corresponding to the input electrical signal is obtained based on a calibration curve showing the relationship between the flow rate and the electrical signal input from the load cell 12. The calibration curve is created in advance based on the relationship between the voltage value and the flow rate when a fluid is allowed to flow at several known flow rates, and is stored in the electrical signal processing device 20.
Then, the flow rate thus obtained is integrated over the time period to be analyzed to obtain an approximate integrated flow rate.
If a water level gauge is installed in the pipe 50 in which the sensor 10 is installed, it is possible to obtain a more accurate flow rate.

The flowmeter 1 of this embodiment includes a sensor attached above the inside of a pipeline that converts the load into an electrical signal, an electrical signal processing device that determines the flow rate from the electrical signal obtained by the sensor, and a pressure receiving part that is connected at one end to the sensor and transmits the dynamic pressure of the fluid flowing in the pipeline to the sensor. When the pressure receiving part receives the dynamic pressure of the fluid flowing in the pipeline, it attempts to move along with the flow of the fluid, thereby applying a moment load to the sensor.

That is, a moment load corresponding to the flow rate is generated with a simple configuration, and the flow rate is obtained by detecting this moment load.
Therefore, it is possible to provide a flow meter with a simple structure that is less susceptible to problems such as entanglement of foreign matter.

If the pressure receiving part 30 is, for example, a rod-shaped or plate-shaped body that reaches from the sensor 10 side to near the bottom surface 52, a clearance is required between the pressure receiving part 30 and the bottom surface 52 in order for the pressure receiving part 30 to move along with the flow of the fluid when it receives the dynamic pressure of the fluid flowing through the pipeline 50. In that case, in the case of a minute flow rate, the dynamic pressure F of the fluid cannot be received by the pressure receiving part 30, and the flow rate cannot be measured.

The flowmeter 1 of this embodiment further includes a pressure-receiving portion 30 that is composed of a weight portion 31 and a connecting wire 32, and the weight portion 31 is connected to the sensor 10 by the connecting wire 32 so that it can come into contact with the bottom surface 52 of the pipeline 50. Therefore, even with a very small flow rate, the weight portion 31 of the pressure-receiving portion 30 can receive the dynamic pressure F of the fluid, allowing the flow rate to be measured.

In this embodiment, the portion of the weight portion 31 that can come into contact with the bottom surface 52 is made to be a convex curved surface. As a result, friction with the bottom surface 52 is reduced, and when subjected to the dynamic pressure of the fluid flowing through the pipeline 50, the sensor 10 quickly floats and moves along with the flow of the fluid, and a moment load can be applied to the sensor 10 through the connecting wire 32.

In this embodiment, the sensor 10 is composed of the conversion unit 13 that converts the moment load applied through the connecting wire 32 into a uniaxial load, and the load cell 12 that converts the uniaxial load into an electrical signal. Therefore, the sensor 10 can be composed of an inexpensive load cell.
The sensor of the present invention may be a sensor that directly converts the moment load into an electrical signal.

The fluid that is the subject of the flowmeter 1 of this embodiment is preferably a liquid. The liquid is not limited to water, and may be, for example, oil.
The flowmeter 1 of the present embodiment can be suitably used when the fluid is water, and in particular, rainwater.
In rainy weather, no rainwater flows through the pipes and the inside of the pipes is dry. In rainy weather, the amount of rainfall may be very small, but there may also be cases of extremely large flow rates, such as in the case of a sudden downpour.
The flowmeter 1 of this embodiment can also measure the flow rate in a pipeline with a large fluctuation in the flow rate.

REFERENCE SIGNS LIST 1 Flowmeter 10 Sensor 11 Mounting plate 12 Load cell 13 Conversion section 14 Hinge section 20 Electrical signal processing device 21 Signal line 30 Pressure receiving section 31 Weight section 32 Connecting line 50 Pipe line 51 Top surface 52 Bottom surface

Claims (6)

A flow meter for measuring a flow rate of a fluid flowing in a pipeline laid substantially horizontally, comprising:
a sensor attached to the upper part of the pipeline to convert a load into an electric signal; an electric signal processing device that determines a flow rate from the electric signal obtained by the sensor; and a pressure receiving part that is connected at one end to the sensor and transmits the dynamic pressure of the fluid flowing in the pipeline to the sensor,
the pressure receiving portion has a weight portion and a flexible connecting wire connecting the weight portion to the sensor,
the weight portion is connected to the sensor by the connecting wire so as to be able to come into contact with a bottom surface of the pipeline, at least a portion of the weight portion that can come into contact with the bottom surface of the pipeline is a convex curved surface, and when subjected to dynamic pressure of a fluid flowing through the pipeline, the weight portion floats and attempts to move along with the flow of the fluid, thereby applying a moment load to the sensor through the connecting wire. The flowmeter according to claim 1, wherein the weight portion is spherical. The flowmeter according to claim 1 or 2, wherein the fluid is water and the specific gravity of the weight is 7 to 9. The flow meter of claim 3, wherein the fluid is rainwater. The flowmeter according to any one of claims 1 to 4, wherein the weight portion is made of stainless steel. The flowmeter according to any one of claims 1 to 5, wherein the sensor has a conversion unit that converts the moment load applied through the connecting wire into a uniaxial load, and a load cell that converts the uniaxial load into an electrical signal.

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