JPS5819454Y2 - Open channel flow meter - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a flowmeter for an open channel, in which a positive displacement flowmeter is submerged in a part of an open channel (including a culvert).

The configuration of this type of open channel flow meter that has been used in the past is shown in Figures 1a and 1).

FIG. 1a is a perspective view, and FIG. 1b is a sectional view.

This flowmeter has a structure in which a partition plate 2 is provided in a water channel 1 and a positive displacement flowmeter, for example, an electromagnetic flowmeter 3 is provided in a through hole formed in the lower part of the partition plate 2.

4 is the fluid to be measured, and 5 indicates the direction of flow.

In the open channel flowmeter having such a configuration, a plurality of positive displacement flowmeters must be provided on the partition plate 2 because one positive displacement flowmeter does not have sufficient capacity for large flow rates.

・However, if a large number of positive displacement flowmeters are installed, the flowmeter becomes very expensive and the measurement accuracy decreases.

In addition, a dummy pipe was installed in the through hole of the partition plate 2 instead of a positive displacement flowmeter, and the overall flow rate was estimated from the indications of the basic positive displacement flowmeter, taking into account the flow velocity distribution of the waterway. There is.

According to this configuration, an expensive flowmeter can be avoided, but on the other hand, it is unavoidable that the measurement accuracy of the total flow rate is lowered.

In particular, when the shape of the waterway is complicated, the flow velocity distribution in the waterway becomes complicated, which may make it almost unusable.

On the other hand, positive displacement flowmeters are generally used in full water conditions.

Therefore, in the case of a small flow rate, as shown in Fig. 2, an excavated part 1a is provided with the bottom of the water channel 1 lowered by sandwiching the partition plate 2, and a positive displacement flow meter 3 is provided in this part, or a third
As shown in the figure, it is necessary to provide an auxiliary partition plate 6 on the downstream side of the partition plate 2 to fill the inside of the positive displacement flowmeter with water.

However, in these configurations, in the example of FIG.
In the example shown in FIG. 3, dirt and the like tend to accumulate between the partition plate 2 and the auxiliary partition plate 6, which has the disadvantage that measurement becomes impossible in some cases.

Therefore, the conventional method as shown in FIG. 1 has the drawback that accurate flow rate measurement is difficult to be expected for both large and small flow rates.

In order to eliminate these drawbacks of the conventional structure, the present invention changes the idea from the conventional one by constricting the side wall of the waterway, raising the bottom surface, and installing a positive displacement flowmeter in this part. , is characterized by being able to accurately measure both small and large flow rates.

The specific structure and operation of the present invention will be explained below with reference to the drawings.

FIG. 4 shows an embodiment of the flowmeter of the present invention.

FIG. 4a shows a frame 8 having a constriction part 8a and a convex part 8b inserted into the convex part 9 of the waterway, and a partition plate 7 which is the constricted part of this frame and is used to attach the positive displacement flowmeter 3 to the convex part. FIG. 2 is a front view of the open channel flow meter of the present invention, which is configured to include the following.

FIG. 4 is a sectional view showing the raised portion 9 on the bottom surface of the waterway and the raised portion 8b of the frame 8.

According to this configuration, the raised bottom surface 9 is provided in the middle of the waterway, and at the same time, the side surfaces are narrowed and the narrowing ratio is increased.
The configuration makes it difficult for dirt and the like to accumulate inside the positive displacement flowmeter 3, and at the same time, it becomes easy to fill the inside of the positive displacement flowmeter 3 with water even at a small flow rate.

Furthermore, even in the case of a large flow rate, the raised bottom surface 9 makes it difficult for dirt to accumulate inside the positive displacement flow meter 3, and at the same time, by arbitrarily selecting the restriction ratio of the flow path with the structure of the frame 8, the volume of one unit can be reduced. Using a type flow meter, it is possible to measure a wide range of flow rates and improve accuracy.

In the embodiment shown in FIG. 4, the frame 8 is provided in the water channel 1, but the part corresponding to the frame 8 may be made of concrete or the like at the same time as the water channel 1.
Also frame 8. Partition plate 7. The positive displacement flowmeters 3 may be manufactured separately and combined at the time of installation.

It goes without saying that various types of positive displacement flowmeters can be used within the scope of the above purpose, such as electromagnetic flowmeters, Karman vortex flowmeters, and ultrasonic flowmeters.

The configuration of the present invention has been described above, and its effects can be summarized as follows.

(1) Measurement is possible from small flow rates to large flow rates.

It is easy to change the aperture ratio of the constriction part of the waterway and change the size of the positive displacement flowmeter, and by taking advantage of the large rangeability of positive displacement flowmeters such as electromagnetic flowmeters, it is possible to expand the measurement flow range more than ever before. A large flow meter is obtained.

(2) Highly accurate flow rate measurement is possible.

According to the present invention, it is not necessary to use a plurality of flowmeters as in the conventional method, so that highly accurate flow rate measurement can be performed at low cost.

(3) The flowmeter is resistant to sediment accumulation.

Normally, sediment tends to accumulate in waterways, but according to the present invention, the bottom surface of the constricted part of the waterway is raised, making it possible to create a flowmeter that is resistant to sedimentation.

It is particularly effective when measuring small flow rates. (4) It is possible to shorten the construction period.

Since the above-mentioned flowmeter, which has been unitized in advance, can be set into an open channel, this part can be constructed as a normal waterway without requiring any special measures.

Therefore, there is an advantage that the construction period can be shortened and at the same time, it is possible to easily respond to changes in the user's specifications.

As described above, the open channel flowmeter of the present invention has various features not found in conventional flowmeters, and is extremely effective when used in the field of open channel flow rate measurement.

[Brief explanation of drawings]

Figure 1 is a basic configuration diagram of a conventional open channel flowmeter, Figures 2 and 3 are configuration diagrams of a conventional open channel flowmeter used to measure small flow rates, and Figure 4 is an open channel flowmeter using the present invention. FIG. 2 is a configuration diagram showing an example of a flowmeter for use in the first embodiment. 1... Waterway, 2, 7... Partition plate, 3.
...Positive flow meter, 4... Fluid to be measured, 5
...Flow direction, 6...Auxiliary partition plate,
8...Frame, 8a...Aperture part, 8
b... Protruding portion, 9... Raised bottom surface.

Claims (1)

[Scope of utility model registration request] In a flowmeter for an open channel in which a positive displacement flowmeter is installed by submerging it in a part of the open channel, a partition plate is provided at a portion where the side surface of the open channel is narrowed and the bottom surface thereof is raised to partition the channel, This open channel flowmeter is characterized by having a positive displacement flowmeter attached to a through hole formed at the bottom of the partition.