JP2001108499A - Ultrasonic liquid flow rate detection sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic liquid flow rate detection sensor that can be installed without cutting existing piping, and at the same time, can make a span larger, and can easily carry out the alignment between ultrasonic vibrations. SOLUTION: In the ultrasonic liquid flow rate detection sensor that is arranged opposite to the front and back or piping being formed of a fluororesin, transmits and receives an ultrasonic wave, and detects the flow rate of fluid flowing inside the piping according to the time difference, a rectangular parallelepiped-shaped recessed part 23b with a quadrilateral-shape section is formed in the longitudinal direction of a back surface, at the same time, an engagement part 23c projection in an outer direction is provided at a part other than the recessed part, a sensor holder 23 with a gear-lock part consisting of the recessed part with the same shape as the engagement part is provided, and a shoe 21 is fitted to one part of the recessed part with the quadrilateral- shaped section of a sensor holder, a where the shoe 21 is formed by the same fluorine plastic as the piping, and forms a part in contact with the piping on the same curved surface as the outer periphery of the piping.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clamp-on type ultrasonic liquid flow rate detecting sensor which is attached to the outside of a fluororesin pipe through which a fluid to be measured flows and detects a flow rate.

[0002]

2. Description of the Related Art A method of measuring a fluid flowing in a pipe by ultrasonic waves is such that ultrasonic liquid flow rate detection sensors are disposed on the upstream and downstream sides of a pipe so as to be opposed to each other and transmit and receive ultrasonic pulses. In this method, the flow rate is measured by detecting the flow rate based on the difference in arrival time.

Conventionally, in the case of this system, a material such as acrylic or epoxy has been used for a shoe of an ultrasonic liquid flow detecting sensor which is in contact with a pipe, and the shoe is made of PFA resin used in a semiconductor cleaning device or the like. When attached to a small diameter pipe, due to the difference in the material of the shoe and the pipe, the PF
Since the sound wave entering the A resin pipe is refracted in a direction orthogonal to the pipe, the distance (span) between the sensors cannot be made large, and the measurement accuracy cannot be improved.

Conventionally, the ultrasonic liquid flow rate detection sensor is fixed to a pipe by using a wire band or the like. In this case, however, there is an advantage that it can be applied to any pipe diameter. However, there is a problem that the alignment must be performed each time. In the ultrasonic flowmeter, the position of the sensor is important, and if the positioning is not performed accurately, the accuracy of measurement is greatly affected.

Therefore, when a small flow rate is measured by ultrasonic waves as in the field of cleaning a semiconductor substrate, a dedicated flow rate measuring device as shown in FIG. 8 is used instead of the clamp-on type.
In this measuring device, the flow path 81 of the detecting section 80 is formed in a U-shape. The liquid flowing from the inlet 81a is bent by 90 degrees, passes through the measuring pipe 81b, is bent again by 90 degrees, and is bent again by 90 degrees.
1c. Measuring tube 81b
Ultrasonic transducers 82 for transmitting and receiving ultrasonic waves
Is mounted, and the flow rate is obtained from the pipe size and the like based on the detection signal from the ultrasonic transducer 82.

[0006]

However, when this flow rate measuring device is used, an existing pipe must be cut and a detection unit must be connected, and there is a possibility that impurities may be mixed in the pipe, and this measuring pipe may be used. Has a 'U'-shape, so it is easy for liquid to accumulate in the corners, accumulating impurities,
An aqueous solution may be precipitated, which is problematic.

An object of the present invention is to provide an ultrasonic liquid flow rate detection sensor which can be installed without cutting existing pipes, can have a large span, and can be easily positioned between ultrasonic transducers. It is in.

[0008]

Means for Solving the Problems In order to solve the above problems, the present invention employs the following means. The ultrasonic liquid flow rate detection sensor according to claim 1 is disposed opposite to the front and back of a pipe formed of a fluororesin, transmits and receives ultrasonic waves, and detects a flow rate of a fluid flowing inside the pipe from a time difference between the ultrasonic waves. An ultrasonic liquid flow rate detection sensor, wherein the shoe of the ultrasonic liquid flow rate detection sensor that contacts the pipe is formed of the same fluororesin as the pipe, and the portion that contacts the pipe has the same curved surface as the outer circumference of the pipe. It is characterized by being formed.

According to a second aspect of the present invention, there is provided an ultrasonic liquid flow rate detection sensor which is disposed opposite to the front and back of a pipe formed of a fluororesin, transmits and receives ultrasonic waves, and detects a flow rate of a fluid flowing into the pipe based on a time difference. An ultrasonic liquid flow rate detection sensor for detecting a rectangular parallelepiped, a concave portion having a rectangular cross section in the longitudinal direction of the back surface thereof, and having an engaging portion projecting outward in a portion other than the concave portion, A sensor holder having a locking portion composed of a recess having the same shape as the engagement portion,
A shoe formed of the same fluororesin as the pipe and having a portion in contact with the pipe formed on the same curved surface as the outer circumference of the pipe is fitted and inserted into a part of the square-shaped concave portion of the sensor holder. And

According to a third aspect of the present invention, there is provided an ultrasonic liquid flow rate detection sensor according to the first or second aspect, wherein the surface on which the ultrasonic vibrator of the shoe is attached is set at 50 to 58 degrees with respect to the pipe surface. It is characterized by doing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of an ultrasonic liquid flow detection sensor according to the present invention will be described below with reference to the drawings. FIGS. 1A and 1B are diagrams for explaining in principle the state in which the ultrasonic liquid flow rate detection sensor 10 is clamped on a pipe 50. FIG. 1A is a side view and FIG. 1B is a front view. However,
In (b), the lower sensor 10 is omitted. As shown in the figure, the pipe 50 has a uniform diameter and is made of a chemical-resistant fluororesin (PFA) for transporting a semiconductor-related cleaning liquid. Shoe 1 of ultrasonic liquid flow rate detection sensor 10 clamped on pipe 50
1 is made of the same fluororesin (PTFE) as the pipe 50, and a portion 11a that comes into contact with the pipe 50 is formed on the same curved surface as the outer periphery of the pipe 50, that is, a curved surface having the same curvature as the outer surface of the pipe 50. ing. Therefore, the shoe 11 comes into close contact with the outer surface of the pipe 50. Also, shoe 11
The ultrasonic vibrator 12 is attached to the side surface 11b, and the side surface 11b has an inclination angle θ with respect to the outer surface of the pipe 50.

As described above, since the shoes 11 made of the same material (PTFE) are used for the fluororesin (PFA) -based piping 50, good ultrasonic wave reception can be obtained in measuring the flow rate. This is because the acoustic characteristics of the shoe 11 and the pipe 50 are close to or identical to each other, so that there is almost no reflection of ultrasonic waves between the shoe 11 and the pipe 50, and the pipe 5 is efficiently connected.
This is because the ultrasonic wave is incident on the liquid within 0. further,
Since the speed of sound propagating in the fluororesin is relatively slow at about 1300 m / S, if the object to be measured is specified to have a higher propagation speed than the fluororesin such as water or aqueous solution, the sound wave path propagating through the middle point of the pipe 50 Is the shortest time, and the zero gloss point of S1 used for the flow rate measurement is not disturbed by the received wave propagating through another path. For this reason, by multiplying by an appropriate correction coefficient, more accurate flow rate measurement becomes possible.

At this time, the incident angle of the ultrasonic wave is Snel
Based on the law of l, refraction occurs so as to be more acute with respect to the center axis of the pipe, so that the interval between the transmission and reception sensors 10 can be increased. This leads to more accurate flow measurement.

As an example, the material of the shoe 11 is PTF
E, the material of the pipe 50 was PFA, water was poured into the pipe 50, and the relationship between the inclination angle θ of the side surface 11b of the shoe 11 and the receiving sensitivity of the ultrasonic transducer was tested. The results shown in FIG. 2 were obtained. Was. A stable wave receiving sensitivity can be obtained when the inclination angle θ of the surface of the shoe 11 to which the ultrasonic transducer 12 is attached is in the range of 50 ° to 58 °. It was found that when the inclination angle was less than 50 °, the span between the ultrasonic liquid flow rate detection sensors 10 could not be obtained, and when the inclination angle was more than 58 °, the sensitivity sharply decreased. The diameter of the pipe 50 is 6.35 mm. In addition, since the portion 11a of the shoe 11 that comes into contact with the pipe 50 is formed on the same curved surface as the outer circumference of the pipe 50, high-accuracy flow rate measurement can be performed by improving the receiving sensitivity and the S / N ratio due to the close contact. .

Next, a second embodiment will be described.
This ultrasonic liquid flow detection sensor includes a sensor holder 23 shown in FIG. 3 and a shoe 21 to which an ultrasonic vibrator 22 shown in FIG. 4 is attached. 3A is a perspective view of the sensor holder 23 as viewed from the bottom, FIG. 3B is a perspective view of the sensor holder 23 as viewed from above, FIG.
(B) is a sectional view taken along line BB of (a), (c) is a front view, and (a) is viewed from the direction of arrow C. The sensor holder 23 is made of plastic such as vinyl chloride, and has a substantially rectangular parallelepiped shape. The sensor holder 23 is provided with a slightly recessed groove 23a over both longitudinal ends of the center of the back surface. A recess 23b having a rectangular cross section is formed in the groove 23a. Also, at the raised portions on both sides of the groove 23a on the back surface and the sensor holder 2
A pair of columnar engaging portions 23c is provided in the vicinity of the end of the third.

An engaging portion formed of a concave portion having the same shape as the engaging portion 23c is provided at a raised portion on both sides of the groove 23a on the back surface, and near the middle between the center portion and the end portion of the sensor holder 23. 23d are formed. In addition, this locking part 23d penetrates through the front and back of the sensor holder 23. Further, the sensor holder 23 has a circular through hole 23e in the center.
Is provided at the end with a circular through-hole 23f having a thread groove formed therein, and four rectangular holes 23g penetrating between the side surface and the upper surface.

Next, the shoe 21 fitted into the sensor holder 23 will be described. The shoe 21 is made of a fluororesin, and as shown in FIG. 4, is made up of a trapezoidal main portion 21a in a side view and a flat plate-like sub-portion 21b extending horizontally from the main portion 21a. One side surface 21c in the longitudinal direction of the main portion 21a is formed vertically, and the other side surface 21d has an inclination angle θ of 58 ° with respect to the bottom surface,
The ultrasonic vibrator 22 is bonded and attached thereto.
Further, as shown in FIG. 4C, the bottom surface 21e of the main portion 21a is formed in a curved surface, and has a curved surface having substantially the same curvature as the curved surface of the outer surface of the pipe through which the liquid to be measured passes. . Further, a screw hole 21f is provided on the upper surface of the main part 21a, and the screw hole 21f is formed by inserting a screw from a through hole 23e of the sensor holder 23 when the shoe 21 is fitted into the sensor holder 23. The shoe 21 is screwed into the screw hole 21f to fix the shoe 21 to the sensor holder 23.

FIGS. 5A and 5B show the ultrasonic liquid flow rate detection sensor 20 with the shoe 21 fitted in the sensor holder 23. FIG. 5A is an exploded view and FIG. 5B is a view showing a completed state. The shoe 21 is inserted into the recess 23 b of the sensor holder 23 and fixed with the screw 24. At this time, the sub part 21 b of the shoe 21 is supported on both sides by a part of the groove 23 a of the sensor holder 23. Also, the ultrasonic transducer 22
Is connected to the hole 23f of the sensor holder 23.
Is drawn out to the outside through the center of the cap 26 closing the cap.

Next, the ultrasonic liquid flow rate detection sensor 20
How to use will be described. As shown in FIG. 6, the pair of ultrasonic liquid flow rate detection sensors 20 are turned upside down with the right and left reversed, and the engagement portions 23 of the respective
c into the engaging portion 23d on the other side. The pipe 50 is sandwiched from both sides by the bottom surface 21 e of the shoe 21 of the sensor 20 on both sides. As described above, the positioning of the ultrasonic liquid flow rate detection sensor 20 disposed opposite to the upstream side and the downstream side can be easily performed with one touch.

Subsequently, as shown in FIG. 7, the band 30 is tightened through a hole 23g formed in the sensor holder 23 so that the two sensors 20 do not come off. The band 30 may be used for bundling a large number of wires. If the band 30 can be locked and unlocked, it can be removed at the end of the flow rate measurement, which is more convenient.

As described above, the attachment of the sensor 20 to the pipe 50 can be performed very easily, the attachment accuracy is improved, and the shape of the sensor holder 23 is the same on both the upstream side and the downstream side. Since the structure is such that the sensor holder 23 is mounted facing each other, only one type of mold is required to form the sensor holder 23, and the cost can be reduced.

[0022]

As described above, since the ultrasonic liquid flow rate detection sensor according to the present invention is of the clamp-on type, the flow rate detection work is easier than the conventional semiconductor cleaning liquid quantity detection sensor which cuts and attaches the existing pipe. Along with
Since the same fluororesin as the pipe is used for the shoe, the span can be made large from the relationship of reflection and refraction of the sound wave, and the flow rate measurement with high accuracy can be performed.

Further, the work time can be shortened because the attachment to the pipe is easy and the alignment is easy. Further, since the upstream and downstream sensor holders can be made from one type of mold, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a first view of an ultrasonic liquid flow detection sensor according to the present invention.
FIGS. 2A and 2B are diagrams in which the embodiment of FIG. 1 is attached to a pipe, where FIG.

FIG. 2 is a diagram showing the relationship between the angle of the ultrasonic transducer mounting surface of the shoe and the wave receiving sensitivity.

3A and 3B show a sensor holder, wherein FIG. 3A is a perspective view seen from a bottom surface, and FIG. 3A is a perspective view seen from a top surface.

FIG. 4 shows the shape of the shoe, (a) is a plan view, (b)
3A is a cross-sectional view taken along line BB of FIG. 3A, and FIG. 3C is a right side view.

FIG. 5 is an exploded view of the shoe and the sensor holder, and (b) is an assembled view.

FIG. 6 is a diagram for explaining a state in which the ultrasonic liquid flow rate detection sensor according to the second embodiment shown in FIG. 5 is attached to a pipe.

FIG. 7 is a diagram in which an ultrasonic liquid flow rate detection sensor is attached to a pipe and fastened with a band.

FIG. 8 is a diagram illustrating an operation principle of a conventionally used detector for measuring a flow rate of a semiconductor cleaning liquid.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ultrasonic liquid flow detection sensor 11 Shoe 11a Portion which contacts pipe 12 Ultrasonic vibrator 20 Ultrasonic liquid flow detection sensor 21 Shoe 22 Ultrasonic vibrator 23 Sensor holder 23b Depression 23c Engagement part 23d Lock part 50 Pipe

Claims (3)

[Claims] An ultrasonic liquid flow rate detection sensor disposed opposite to the front and back of a pipe formed of a fluororesin, transmitting and receiving ultrasonic waves, and detecting a flow rate of a fluid flowing inside the pipe from a time difference between the ultrasonic waves. The shoe of the ultrasonic liquid flow detection sensor contacting the pipe is formed of the same fluororesin as the pipe,
An ultrasonic liquid flow rate detection sensor, wherein a portion in contact with a pipe is formed on the same curved surface as an outer circumference of the pipe. 2. An ultrasonic liquid flow rate detection sensor disposed opposite to the front and back of a pipe formed of a fluororesin, transmitting and receiving ultrasonic waves and detecting a flow rate of a fluid flowing inside the pipe from a time difference between the ultrasonic waves. A rectangular parallelepiped-shaped recess having a rectangular cross section in the longitudinal direction of the back surface, and having an engaging portion projecting outward in a portion other than the recess, and a recess having the same shape as the engaging portion. A shoe provided with a sensor holder having a stop portion, the sensor holder being formed of the same fluororesin as the pipe in a part of the concave portion having the rectangular cross section, and having a portion in contact with the pipe formed on the same curved surface as the outer circumference of the pipe. The ultrasonic liquid flow rate detection sensor, wherein is inserted. 3. The ultrasonic liquid flow rate detection sensor according to claim 1, wherein the surface of the shoe on which the ultrasonic vibrator is attached has an angle of 50 ° to 58 ° with respect to a piping surface.