JP2008008706A - Ultrasonic flowmeter equipped with diaphragm pressure sensor, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flowmeter equipped with a diaphragm pressure sensor suitable to be installed in an ultrasonic propagation passage of the ultrasonic flowmeter, having corrosion resistance by using a fluororesin, and its manufacturing method. <P>SOLUTION: In this ultrasonic flowmeter equipped with the diaphragm pressure sensor 42 for measuring the pressure of chemical solution supplied into a chemical solution supply pipe 51 made of a fluororesin, a flow rate of the chemical solution is measured by an ultrasonic oscillation/reception parts 52A, 52B provided on both ends of the ultrasonic propagation passage 51A constituting a part of the chemical solution supply pipe under control of the pressure measured by the sensor 42. The diaphragm pressure sensor includes a diaphragm 43 formed by scraping thinly a part of a pipe wall of the chemical solution supply pipe constituting the ultrasonic propagation passage in order to form a pressure sensitive part in contact with the chemical solution, a reinforcing member 44 formed for the diaphragm, and a pressure/electricity conversion element formed for the reinforcing member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic flowmeter equipped with a diaphragm pressure sensor and a method for manufacturing the same, and in particular, a chemical solution that is attached to a chemical solution supply pipe made of fluororesin, for example, used in a semiconductor manufacturing apparatus, and supplied to the chemical solution supply pipe. The present invention relates to an ultrasonic flowmeter equipped with a diaphragm pressure sensor and a method for manufacturing the same.

FIG. 1 shows the principle of a flow meter that measures a flow rate by flowing a fluid through a cylindrical fluororesin tube.
The ultrasonic flowmeter 10 is formed by piezoelectric elements PZT in order to measure the flow velocity of the fluid flowing in the chemical liquid supply pipe 11 at both ends of the ultrasonic wave propagation channel 11A constituting a part of the chemical liquid supply pipe 11. It has an ultrasonic oscillation / reception unit 12A and an ultrasonic oscillation / reception unit 12B. Assuming that the fluid passes from one end IN to the other end OUT of the chemical solution supply pipe 11, the ultrasonic vibration oscillated from the ultrasonic oscillation / reception unit 12A propagates through the fluid in the ultrasonic propagation channel 11A and becomes super. The ultrasonic vibration that reaches the sound wave oscillating / receiving unit 12B and simultaneously oscillated from the ultrasonic wave oscillating / receiving unit 12B reaches the ultrasonic wave propagation channel 11A against the flow. The interval between the ultrasonic wave propagation channel 11A and the ultrasonic wave oscillating / receiving unit 12B is L, and the time for the ultrasonic wave to reach the ultrasonic wave oscillating / receiving unit 12B from the ultrasonic wave propagation channel 11A is TD. When TU is the time required to reach the ultrasonic wave oscillating / receiving unit 12A from the ultrasonic wave propagation channel 11B, TD and TU are given by the following equations.

Where C is the speed of sound of the fluid.
Therefore, the flow velocity V is given by the following equation.

Thus, when the flow velocity of the fluid flowing in the chemical solution supply pipe 11 is obtained, the flow rate per unit time is measured if the diameter of the chemical solution supply pipe 11 is determined in advance.

  FIG. 2 shows a specific ultrasonic flow meter 20 using the ultrasonic flow meter 10 shown in FIG. 1, and the ultrasonic flow meter 20 has a constant fluid flow particularly in a semiconductor manufacturing apparatus. It is suitable for measuring the flow rate of a chemical solution related to semiconductor manufacturing that is required to be stably discharged or dropped.

The ultrasonic flow meter 20 includes a pressure sensor 21, a pressure controller 22, a pressure control valve 23, a flow measurement controller 24, and a flow control valve 25.
The chemical liquid flowing in from the input terminal IN is detected by the pressure sensor 21, and the detected pressure is controlled through the pressure regulator 22 and the pressure regulating valve 23 so as to have an arbitrary pressure value set in advance. . By this pressure adjustment, the ultrasonic flowmeter 10 can measure a stable flow rate of the chemical solution with a small pulsation pressure. The flow rate of the chemical solution measured by the ultrasonic flow meter 10 is controlled to be an arbitrary flow rate value set in advance via the flow rate measurement controller 24 and the flow rate control valve 25.

  When such an ultrasonic flow metering device is used in, for example, a semiconductor manufacturing apparatus, a structure without pressure loss or liquid pool in the piping system is required for chemicals involved in semiconductor manufacturing, and the piping system can be used at the same time. A structure that is as short as possible and that is compact and free from contamination is required. Further, in order to accurately measure the flow rate, measurement under a constant pressure with little pressure fluctuation is required.

  In such a conventional ultrasonic flow meter, a pressure sensor made of fluororesin, for example, PFA (registered trademark: Tetrafluoroehylene Perflouroalkoxy vinyl ether copolymer) is usually used as a pressure sensor.

  FIG. 3 shows the structure of a typical PFA diaphragm pressure sensor 30 for detecting the liquid pressure in the chemical liquid supply pipe. Such a pressure sensor includes a ceramic diaphragm 31 in which a circular fluororesin diaphragm is further reinforced with a ceramic plate as a pressure sensing unit, and a strain resistance element is attached to the ceramic plate as a Wheatstone bridge circuit, and an applied pressure is applied. The distortion of the fluororesin diaphragm due to (in the direction of the arrow) is transmitted to the ceramic diaphragm 31, and this distortion is converted into an electric signal as a resistance value change of the strain resistance element functioning as a pressure / electric conversion element, thereby detecting the pressure. It is configured. Specifically, the pressure sensing unit includes a liquid reservoir 33 between the pressure (chemical solution) inlet 32 and the ceramic diaphragm 31 so as to increase the area of the diaphragm and efficiently detect the distortion.

  Such a PFA diaphragm pressure sensor has no structural problem in measuring fluid pressure, but in order to efficiently and accurately measure pressure and flow rate in an ultrasonic flow meter. When a pressure sensor is installed in the ultrasonic wave propagation channel of the ultrasonic flow meter, the ultrasonic wave passing through is irregularly reflected particularly in a structure having irregularities such as a liquid reservoir, and accurate measurement cannot be expected.

  An object of the present invention is to provide a diaphragm that has excellent corrosion resistance against strongly acidic and strongly alkaline liquids by using a fluororesin, and is suitable for installation in an ultrasonic wave propagation channel of an ultrasonic flowmeter. An ultrasonic flow meter including a pressure sensor and a method for manufacturing the ultrasonic flow meter are provided.

  In the present invention, the ultrasonic flowmeter includes a diaphragm pressure sensor that measures the pressure of the chemical liquid supplied to the chemical liquid supply pipe made of fluororesin, and supplies the chemical liquid under the control of the pressure measured by the diaphragm pressure sensor. The flow rate of the chemical solution is measured by ultrasonic wave oscillating / receiving units provided at both ends of the ultrasonic wave propagation channel constituting a part of the pipe. Diaphragm pressure sensor is formed with respect to the diaphragm formed by thinly cutting a part of the pipe wall of the chemical solution supply pipe constituting the ultrasonic wave propagation path to form a pressure sensing part in contact with the chemical solution And a pressure / electrical conversion element formed on the reinforcing member.

  Further, in the present invention, a diaphragm pressure sensor for measuring the pressure of the chemical liquid supplied to the chemical liquid supply pipe made of fluororesin is provided, and a part of the chemical liquid supply pipe is controlled under the control of the pressure measured by the diaphragm pressure sensor. The method of manufacturing an ultrasonic flowmeter equipped with a diaphragm pressure sensor that measures the flow rate of a chemical solution by ultrasonic oscillation / reception units provided at both ends of an ultrasonic propagation channel that constitutes the pressure sensing unit in contact with the chemical solution Forming a diaphragm by thinly cutting a part of the wall of the chemical solution supply pipe constituting the ultrasonic wave propagation path, forming a reinforcing member on the diaphragm, and Forming a pressure / electrical conversion element. A diaphragm pressure sensor is constituted by the diaphragm, the reinforcing member, and the pressure / electrical conversion element.

  According to the present invention, a liquid pool is generated in a part of an ultrasonic wave propagation channel of an ultrasonic flowmeter made of a fluororesin such as PFA without interfering with a flow path of a supplied chemical solution. Instead, it incorporates a diaphragm pressure sensor and has an integrated structure with the ultrasonic wave propagation channel. Thereby, since it is not necessary to attach a pressure sensor outside the ultrasonic flowmeter, the piping space of the ultrasonic flowmeter can be reduced.

  Further, according to the present invention, since the pressure sensor has an integrated structure with the ultrasonic wave propagation channel, pressure pulsation in the ultrasonic wave propagation channel can be suppressed as much as possible, so that accurate pressure measurement can be performed.

  Further, according to the present invention, since the pressure sensor has an integrated structure with the ultrasonic wave propagation channel, propagation of the ultrasonic signal is not hindered, so that accurate flow rate measurement can be performed.

  FIG. 4 shows a diaphragm pressure sensor incorporated as an integrated structure in an ultrasonic wave propagation flow path constituting a part of a fluororesin chemical supply pipe 41 in an ultrasonic flowmeter manufactured of a fluororesin such as PFA. 42 is shown. 4A is a partial cross-sectional view of the chemical liquid supply pipe 41 in which the diaphragm pressure sensor 42 is incorporated, and FIG. 4B is a partial side view of the chemical liquid supply pipe 41 in which the diaphragm pressure sensor 42 is incorporated.

  As shown in FIGS. 4A and 4B, in order to form the pressure sensing part of the diaphragm pressure sensor 42, a part of the tube wall in the central part of the fluororesin chemical liquid supply pipe 41 which is an ultrasonic wave propagation channel is formed. Thinly, the diaphragm 43 is obtained. For example, a ceramic plate 44 is provided on the diaphragm 43 functioning as a pressure sensing unit, and a strain resistance element is attached to the ceramic plate 44 as a Wheatstone bridge circuit (not shown) to reinforce the chemical solution supply pipe 41. The pressure applied by the chemical solution flowing through is transmitted to the ceramic plate 44 via the distortion of the diaphragm 43. The distortion of the ceramic plate 44 is converted into an electric signal as a change in the resistance value of the strain resistance element, whereby the pressure is detected. The diaphragm 43 formed by thinly cutting a part of the pipe wall of the chemical liquid supply pipe 41 is guaranteed sufficient mechanical strength against the pressure of the chemical liquid flowing through the chemical liquid supply pipe 41 together with the ceramic plate 44.

  In order to form the diaphragm 43 of the chemical liquid contact part as an integrated structure in the ultrasonic wave propagation channel of the chemical liquid supply pipe 41, that is, a part of the tube wall at the center of the ultrasonic wave propagation channel of the chemical liquid supply pipe 41 is formed. In order to form a diaphragm 43 that is thinly cut and smooth, a hole 45 for planar processing of the diaphragm 43 is cut in advance at a position facing the cross-sectional direction in the attachment portion of the pressure sensor 42 of the chemical solution supply pipe 41. A processing tool is inserted from 45, and a portion functioning as the diaphragm 43 is thinly cut. After a predetermined thickness is obtained by this processing, the holes 45 are welded by a welding machine, and the leakage of the chemical solution is completely filled in the contents.

FIG. 5 shows an ultrasonic flow meter 50 with a diaphragm pressure sensor 42 according to the present invention.
The ultrasonic flowmeter 50 is formed by piezoelectric elements PZT at both ends of an ultrasonic wave propagation channel 51 </ b> A constituting a part of the chemical liquid supply pipe 51 in order to measure the flow velocity of the fluid flowing in the chemical liquid supply pipe 11. An ultrasonic oscillation / reception unit 52A and an ultrasonic oscillation / reception unit 52B are provided. Assuming that the fluid passes from one end IN to the other end OUT of the chemical solution supply pipe 51, the ultrasonic vibration oscillated from the ultrasonic oscillation / reception unit 52A propagates the fluid in the ultrasonic propagation channel 51A and becomes super. The ultrasonic vibration that has reached the sound wave oscillating / receiving unit 52B and simultaneously oscillated from the ultrasonic wave oscillating / receiving unit 52B reaches the ultrasonic wave propagation channel 51A against the flow. Thereby, as described with reference to FIG. 1, the flow velocity of the fluid flowing in the chemical solution supply pipe 51 is obtained, and the flow rate per unit time is measured. The pressure sensor 42 shown in FIGS. 4A and 4B is housed in a protective unit case 53.

  FIG. 6 shows a specific ultrasonic flow metering device 60 that uses the ultrasonic flowmeter 50 shown in FIG. 5, and the ultrasonic flow metering device 60 is used to maintain a constant fluid, particularly in a semiconductor manufacturing device. It is suitable for measuring the flow rate of a chemical solution related to semiconductor manufacturing that is required to be stably discharged or dropped.

The ultrasonic flow meter 60 includes a pressure sensor 42 (FIGS. 4 and 5), a pressure controller 62, a pressure control valve 63, a flow measurement controller 64, and a flow control valve 65.
The chemical liquid flowing in from the input terminal IN is detected by the pressure sensor 42, and the detected pressure is controlled to be an arbitrary preset pressure value via the pressure regulator 62 and the pressure regulating valve 63. . By this pressure adjustment, the ultrasonic flowmeter 50 can measure a stable flow rate of the chemical solution with a smaller pulsation pressure than the conventional apparatus. The flow rate of the chemical solution measured by the ultrasonic flow meter 50 is controlled to be an arbitrary flow rate value set in advance via the flow rate measurement controller 64 and the flow rate control valve 65.

The principle of a flowmeter that measures the flow rate by flowing a fluid through a tubular fluororesin tube will be described. 2 shows a specific ultrasonic flow metering device using the ultrasonic flow meter shown in FIG. The structure of the conventional typical PFA diaphragm pressure sensor which detects the hydraulic pressure in a chemical | medical solution supply piping is shown. 4A is a partial cross-sectional view of a chemical liquid supply pipe in which a diaphragm pressure sensor according to the present invention is incorporated, and FIG. 4B is a partial side view of the chemical liquid supply pipe in which a diaphragm pressure sensor according to the present invention is incorporated. FIG. 5 shows an ultrasonic flowmeter equipped with the diaphragm pressure sensor shown in FIG. FIG. 6 shows a specific ultrasonic flow metering device using the ultrasonic flow meter shown in FIG.

Explanation of symbols

10, 50 Ultrasonic flow meter 11, 41, 51 Chemical solution supply pipe 11A, 51A Ultrasonic propagation channel 12A, 12B, 52A, 52B Ultrasonic oscillation / reception unit and ultrasonic oscillation / reception unit 20, 60 Ultrasonic flow metering Apparatus 22, 62 Pressure controller 23, 63 Pressure control valve 24, 64 Flow rate measurement controller 25, 65 Flow control valve 30, 42 Diaphragm pressure sensor 31 Ceramic diaphragm 32 Pressure (chemical solution) inlet 33 Liquid reservoir 43 Diaphragm 44 Ceramic plate 45 Hole 53 Unit case

Claims (3)

A diaphragm pressure sensor that measures the pressure of the chemical solution supplied to the fluororesin chemical solution supply pipe, and is an ultrathin that forms part of the chemical solution supply pipe under the control of the pressure measured by the diaphragm pressure sensor. In the ultrasonic flowmeter equipped with a diaphragm pressure sensor for measuring the flow rate of the chemical solution by ultrasonic wave oscillating / receiving units provided at both ends of the sound wave propagation channel, the diaphragm pressure sensor includes:
In order to form a pressure sensing part in contact with the chemical solution, a diaphragm formed by thinly cutting a part of a tube wall of the chemical solution supply pipe constituting the ultrasonic wave propagation channel;
A reinforcing member formed for the diaphragm;
A pressure / electrical conversion element formed on the supply member;
An ultrasonic flowmeter equipped with a diaphragm pressure sensor. A diaphragm pressure sensor that measures the pressure of the chemical solution supplied to the fluororesin chemical solution supply pipe, and is an ultrathin that forms part of the chemical solution supply pipe under the control of the pressure measured by the diaphragm pressure sensor. In the method of manufacturing an ultrasonic flowmeter equipped with a diaphragm pressure sensor, the flow rate of the chemical solution is measured by ultrasonic oscillation / reception units provided at both ends of the sound wave propagation channel.
In order to form a pressure sensing part in contact with the chemical solution, a step of forming a diaphragm by thinly cutting a part of a tube wall of the chemical solution supply pipe constituting the ultrasonic wave propagation channel;
Forming a reinforcing member for the diaphragm;
Forming a pressure / electrical conversion element on the reinforcing member;
And a diaphragm pressure sensor is constituted by the diaphragm, the reinforcing member, and the pressure / electrical conversion element. A method of manufacturing an ultrasonic flowmeter equipped with a diaphragm pressure sensor. The process of forming the diaphragm
Cutting a hole in the opposite position of the diaphragm in the cross-sectional direction of the chemical solution supply pipe;
In order to form the diaphragm, a step of inserting a working bite from the hole, and thinly cutting a part of the wall of the chemical solution supply pipe to a predetermined thickness;
Filling the voids after the predetermined thickness is obtained;
The manufacturing method of Claim 1 characterized by the above-mentioned.

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