JPH09264771A - Small-sized ultrasonic flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To markedly reduce the windless area in a measuring pipe to enhance measuring accuracy by forming the corner parts in the measuring pipe into a recessed curve shape. SOLUTION: The corner parts 5 of a measuring pipe 1 in the axial direction thereof is formed into a circular arc shape in the cross-section of the measuring pipe 1. Therefore, the windless area in the measuring pipe 1 is markedly reduced and, therefore, the cross-sectional area allowing a fluid to flow becomes almost same to the physical cross-sectional area of the measuring pipe 1 and, by multiplying the product of the fluid and the cross-sectional area by a slight correction factor, a flow rate can be accurately measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact ultrasonic flowmeter for measuring the flow rate of a fluid from the sectional area of the measurement tube and the flow velocity of the fluid flowing in the measurement tube.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2 (1), a compact ultrasonic flowmeter of this type has a structure in which an ultrasonic oscillator 2 provided on the outer peripheral surface of a measuring tube 1'provides an inside of the measuring tube 1 '. The ultrasonic wave emitted obliquely along the acoustic propagation path 4 and reflected by the inner wall of the measuring tube is received by the sensor 3 provided on the outer peripheral surface of the measuring tube 1 ', and after the ultrasonic wave is transmitted, the sensor The flow velocity of the fluid flowing in the measuring pipe 1'is determined from the time until it is received at 3, and the flow rate of the fluid is measured by the product of this velocity and the cross-sectional area of the internal space of the measuring pipe 1 '.

[0003]

SUMMARY OF THE INVENTION In the above-mentioned conventional small-sized ultrasonic flowmeter, the measuring tube has a ridge portion parallel to its axial direction.
As shown in FIG. 2 (2), since it has an edge shape,
As shown in Fig. 2 (3) (enlarged view of C part in Fig. 2 (2)), a large windless region 6 is generated in the kuma, and the cross section in which the fluid is flowing is reduced. There was a drawback that it caused an error.

An object of the present invention is to provide a compact ultrasonic flowmeter which can measure the flow rate with high accuracy because the wind-free area inside the measuring tube is extremely small.

[0005]

In order to achieve the above object, the miniature ultrasonic flowmeter of the present invention is characterized in that the measuring tube has a kuma parallel to its axial direction when viewed in a cross section of the measuring tube. It is formed in a concave curved shape.

By forming a concave curve in the measuring tube, the windless region is remarkably reduced, and as a result, the flow rate can be accurately measured.

[0007]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 (1) is a sectional view of a compact ultrasonic flowmeter according to an embodiment of the present invention, and FIG. 1 (2) is A- of FIG. 1 (1).
FIG. 3 is a sectional view taken along line A ′. 1, the same reference numerals as those in FIG. 2 indicate the same constituent elements.

In the miniature ultrasonic flowmeter of the present embodiment, when the cross-section 5 of the measuring tube 1 which is parallel to the axial direction of the measuring tube 1 is seen in the cross section of the measuring tube 1, as shown in FIG. It is formed in an arc shape.

Therefore, the windless region in the measuring pipe 1 is significantly reduced, and therefore the cross-sectional area in which the fluid flows becomes almost the same as the physical cross-sectional area of the measuring pipe 1, and the product of the flow velocity and the cross-sectional area is slightly corrected. By multiplying by, the flow rate can be measured accurately.

[0011]

As described above, according to the present invention, when the cross section of the measuring tube, which is parallel to the axial direction of the measuring tube, is formed into a concave curved shape, the wind-free area is reduced. There is an effect that the flow rate is significantly reduced and the flow rate measurement accuracy is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view (FIG. 1 (1)) of a compact ultrasonic flowmeter according to an embodiment of the present invention and a cross-sectional view taken along the line AA ′ of FIG. 1 (1) (FIG. 1 (2)). .

FIG. 2 is a cross-sectional view of a conventional example of a compact ultrasonic flowmeter (see FIG.
(1)) and a sectional view taken along the line BB ′ of FIG.
(2)) and an enlarged view of part C of FIG. 2 (2) (FIG. 2 (3))
It is.

[Explanation of symbols]

 1, 1'Measurement tube 2 Ultrasonic transmitter 3 Sensor 4 Sound wave propagation path 5 Kumabe 6 Windless area

Claims (2)

[Claims] 1. A small ultrasonic flowmeter for measuring a flow rate of a fluid from a cross-sectional area of the measurement tube and a flow velocity of the fluid flowing in the measurement tube, wherein a knuckle portion of the measurement tube parallel to its axial direction is provided. A small ultrasonic flowmeter, characterized in that it is formed in a concave curved shape when seen in a cross section of the measuring tube. 2. The curved shape is an arc shape.
The small ultrasonic flowmeter described.