JP2010276533A - Flow rate measuring instrument and fluid pressure measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To radically solve problems owing to the existence of a conduit section by removing the conduit section itself. <P>SOLUTION: This flow rate measuring instrument is provided with a restriction mechanism 3 in the middle of a pipe 1 to measure the flow rate of a fluid based on pressures measured by pressure sensors 2 provided on the upstream side and on the downstream side, respectively. The measuring instrument is provided with a thin-walled portion 11a with its exterior side recessed at a required part of the outer wall 11 of the pipe 1. Projected/depressed parts 6 are formed on the upstream and down stream sides of the restriction mechanism 3, with the projected/depressed parts 6 projected/depressed owing to elastic deformation of the thin-walled portion 11a caused by pressure fluctuation of the fluid, while pressure-sensitive surfaces of the pressure sensors 2 are put into contact with outer surfaces of the projected/depressed parts 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a flow rate measuring device for measuring a flow rate of fluid by measuring a fluid pressure on a upstream side and a downstream side of a throttle mechanism provided between piping members by using a pressure sensor, and more particularly to manufacturing a semiconductor. The present invention relates to an apparatus that is preferably used by being installed in a line for sending various chemicals, cleaning liquids, various gas fluids, etc. to an apparatus, an FPD manufacturing apparatus, a solar cell manufacturing apparatus, and the like.

  In a conventional flow measurement device using this type of pressure sensor (hereinafter also referred to as a differential pressure type flow meter), as shown in Patent Document 1, pressure is applied to the pressure sensor from a main pipe through which a fluid to be measured flows. A conduit for guiding is provided. As shown in Patent Document 1, this conduit portion is branched from the main piping, and is formed of, for example, a small hole or a thin tube. Japanese Patent Application Laid-Open No. H10-228667 discloses a pressure sensor using a quartz disk. In this document, the quartz disk is configured so that the pressure acts perpendicularly to the face plate part, and a conduit part is formed from the main pipe to the quartz disk, although it is a short distance.

JP 2004-226144 A JP2002-54959

  However, for example, in the case of a highly viscous liquid, the conduit portion may be clogged. Further, even if the fluid has a low viscosity, deposits are generated in the conduit portion, or the deposits are peeled off and flow downstream to cause contamination. This contamination has a great adverse effect in semiconductor processes and the like. Furthermore, in general, in the case of a differential pressure type flow meter, as is clear from Bernoulli's theorem, the measurement accuracy at a low flow rate deteriorates.

  Of course, in addition to the differential pressure type flow meter, there are, for example, an ultrasonic type flow meter and an electromagnetic flow meter. However, in the ultrasonic flowmeter, due to the structure, it is affected by bubbles due to the provision of narrow tubes, bends, orifices, etc., or because the connecting pipe diameter and the pipe diameter of the sensor part are different, stagnant contamination occurs. For viscous fluids, there is a problem that the flow velocity distribution causes measurement errors, and for an electromagnetic flow meter, there is a problem that the fluid needs to be electrically conductive or the sensor structure in a thin tube is difficult.

In view of this, the present invention eliminates the conduit portion itself by using a configuration in which the pressure of the fluid can be measured through the wall of the piping member, and drastically solves the problems caused by the presence of the conduit portion. This is the main intended issue.
In addition, the present invention has a secondary feature in that the pressure can be measured without difficulty even when the piping member is a thin tube by improving the arrangement of the quartz plate, and the measurement accuracy at a low flow rate can be improved. It was made a difficult problem.

  That is, the flow measurement device according to the present invention includes a piping member through which a fluid to be measured for flow flows, a throttle mechanism provided between the piping members, and an upstream side and a downstream side of the throttle mechanism. And a pair of pressure sensors for measuring the pressure of the fluid, and the flow rate of the fluid is measured based on the pressure measured by each pressure sensor, and the outer surface side is recessed at a required portion of the outer wall of the piping member. A thin portion is provided, and projecting and projecting portions that project and retract by elastic deformation of the thin portion due to pressure fluctuation of the fluid are formed on the upstream side and the downstream side of the throttle mechanism, and pressure is applied to the outer surface of the projecting portion. The pressure-sensitive surface of the sensor is in contact.

  In such a case, the conduit part for guiding the pressure to the pressure sensor is completely unnecessary, and the projecting / recessing part for transmitting the pressure is formed by a thin part in which the outside of the outer wall of the piping member is recessed. Therefore, the unevenness on the inner surface of the piping member can be completely eliminated, so that the retention of fluid can be prevented. Furthermore, generation of bubbles, pressure loss, contamination, and the like due to the stagnation of the fluid can be prevented. In addition, since the pressure sensor can be disposed outside the piping member, it can be easily attached and detached, the convenience of maintenance can be improved, and the size can be reduced.

  In the case of a pressure sensor using a crystal plate (piezoelectric element), as shown in Patent Document 2, generally, the face plate portion of the crystal plate is arranged so as to be perpendicular to the pressure direction. This is made vertical, i.e., the edge of the quartz plate is used as a pressure-sensitive surface, and the quartz plate is arranged in a posture substantially perpendicular to the surface of the protruding and recessed portion, and the pressing force from the protruding and recessed portion is If it is configured to act on the edge, even if the piping member is a thin tube, pressure can be measured without difficulty, and the resolution in a low flow rate region can be improved.

  More specifically, it is preferable that the pressure sensor is attached to the piping member so that the face plate portion of the crystal plate is parallel to the fluid flow direction. This is because the pressure receiving area is increased and the pressure transmission efficiency can be improved.

  As a specific aspect in which the protruding and recessed portion can be formed by simple processing, a bottomed groove is provided around the outer wall of the piping member, and the bottom of the bottomed groove functions as the protruding and recessed portion. Can be mentioned.

  Further, in order to suitably hold the crystal plate with a simple configuration in such a configuration, an outer shell body that is tightly fixed around the bottomed groove and the piping members before and after the bottomed groove is provided. It is preferable that a through-hole extending from the surface to the bottomed groove is formed and the quartz plate is accommodated and held in the through-hole.

  As another specific aspect of the protruding and recessed portion, an annular bottomed groove that opens outward is provided on the outer wall of the piping member, and the thin-walled portion is formed at the bottom of the bottomed groove. The thing which makes the outer wall part enclosed by the bottom groove function as the said protrusion part can be mentioned. If this is the case, the part where the pressure-sensitive surface is in contact with the protruding part will be a thick part similar to other outer walls, so the deflection of the protruding part due to the pressure-sensitive surface and the damage of the protruding part at the contact part will be Can be avoided.

  As a preferable aspect that can be easily manufactured and the structure can be integrated, the piping member is made of resin or metal, and the throttle mechanism is the same material as the piping member and is continuously provided integrally. Can do. This is because a throttle mechanism can be easily formed by deforming part of the piping member by pressing or applying heat.

  The present invention can also be applied as a fluid pressure measuring device by omitting the throttle mechanism. With such a configuration, it is possible to measure the pressure while maintaining a contamination-free state.

  According to the present invention configured as described above, the conduit portion for guiding the pressure to the pressure sensor is not necessary, and the projecting and recessed portion for transmitting the pressure is formed by a thin portion in which the outside of the outer wall of the piping member is recessed. Therefore, the unevenness of the inner surface of the piping member can be eliminated, so that the retention of fluid can be prevented. Furthermore, it is possible to prevent the occurrence of contamination due to the retention of the fluid. In addition, since the pressure sensor can be arranged outside the piping member, it can be easily attached and detached, and maintainability and the like can be improved.

The longitudinal cross-sectional view which shows the internal structure of the flow volume measuring apparatus which concerns on 1st Embodiment of this invention. The whole perspective view of the flow measuring device in the embodiment. The front view which shows the inside of the pressure sensor of the flow volume measuring apparatus in the embodiment. The top view which shows the piping member and throttle mechanism in the embodiment. The elements on larger scale which show the protrusion part in the same embodiment. AA sectional view taken on the line in FIG. The graph which shows the flow volume characteristic of the pressure sensor in the embodiment. The longitudinal cross-sectional view which shows the internal structure of the flow volume measuring apparatus in 2nd Embodiment of this invention. FIG. 9 is an end view taken along line AA in FIG. 8.

  An embodiment of the present invention will be described below with reference to the drawings.

<First Embodiment>
As shown schematically in FIG. 1 and FIG. 2, the flow rate measuring device 100 according to the present embodiment is disposed between a piping member 1 through which a fluid to be measured for flow flows and the piping member 1. The throttle mechanism 3 provided, a pair of pressure sensors 2 provided on the upstream side and the downstream side of the throttle mechanism 3 for measuring the pressure of the fluid, and the pressures measured by the pressure sensors 2 and the measured pressures Is a so-called differential pressure type apparatus including an information processing means 5 for calculating the flow rate of the fluid based on the above.

  Specifically, as shown in FIG. 1 and the like, the piping member 1 is a resin (for example, PFA) tube having a circular cross section, the inner diameter thereof is equal, and the thickness of the outer wall 11 is also described later. Except for the thin-walled portion 11a.

  As shown in FIGS. 1 and 4, the throttle mechanism 3 is a tube-shaped member using the same material as the piping member 1. Specifically, the center portion has a minimum inner diameter, and this center The inner diameter is gradually increased from the part to form a shape that reaches both ends smoothly. The inner diameters of both end portions are matched with the inner diameter of the piping member 1, and both end portions are integrally and continuously connected to the end portions of the upstream and downstream piping members 1.

  As shown in FIGS. 7 and 8, the pressure sensor 2 includes a crystal plate 21 and a crystal plate 21 supported by the casing 22, and an oscillation frequency is generated by an external pressure acting on the crystal plate 21. Therefore, the oscillation signal of the quartz plate 21 is output as a pressure signal.

  Explaining each part, the housing 22 has a substantially oval shape in plan view. In the present embodiment, the housing 22 is shared by the two pressure sensors 2. Of course, the housing 22 may be separated. The casing 22 is provided with a storage chamber 22c that is surrounded by a bottom wall 22a and a side peripheral wall 22b that stands up from the bottom wall 22a and is open on one side. Is placed inside.

  As shown in FIG. 3 in particular, the quartz plate 21 has, for example, an equal-thick disc shape having an orientation flat portion (hereinafter also referred to as an orientation flat portion 21a), and electrode plates 23 are attached to the front and back surfaces, respectively. It is. Then, the orientation flat portion 21a is fixed to a holding base 25 attached to the bottom wall 22a of the housing chamber 22c, and the quartz plate 21 rises from the bottom wall 22a, and the tip pressure-sensitive surface 21b (orientation flat) of the quartz plate 21 is fixed. The part 21a is opposed to the opening P (shown in FIG. 1) of the storage chamber 22c.

  The quartz plate 21 is also supported at its side edges by a pair of elastic supports 24 with slits that are erected from the bottom wall 22a. The elastic support 24 is made of a conductive material such as a metal, and is configured to hold a crystal plate 21 and an electrode plate 23 together by a vertically extending slit (not shown) and to also function as a lead wire. . With such a configuration, when the tip which is a pressure-sensitive surface is pressed, the quartz plate 21 is transmitted in the vertical direction (contour direction) as it is, and is compressed and deformed to bend. It is set not to move in the horizontal direction.

  However, in this embodiment, as shown in FIGS. 1 and 4 to 6, a bottomed groove 4 having an annular shape that opens outwardly on the outer wall 11 of the piping member 1 on the upstream side and the downstream side of the throttle mechanism 3. Are provided. The bottomed groove 4 has an oval shape extending in the longitudinal direction of the piping member 1. Naturally, the thickness of the outer wall 11 at the bottom of the bottomed groove 4 is larger than the thickness of the other outer walls 11. Become thin. However, since the thin portion 11a is more easily elastically deformed than the other outer walls 11, the region surrounded by the bottomed groove 4 protrudes and decreases in pressure due to the elastic deformation of the thin portion 11a. It will function as the sunk portion 6 that sometimes immerses. And it is comprised so that the pressure sensitive surface of the said pressure sensor 2, ie, the front-end | tip pressure sensitive surface of the quartz plate 21, may contact the surface of this protrusion part 6. FIG.

More specifically, as shown in FIG. 1, the pressure-sensitive surface of the crystal plate 21 is fixed to the outer surface of the protrusion 6 by passing the piping member 1 and the throttle mechanism 3 through the housing 22 and fixing them. The pressure sensor 2 can detect the pressure of the fluid via the protrusions 6. At this time, the face plate portion of the crystal plate 21 is parallel to the fluid flow direction, that is, the longitudinal direction of the piping member 1, and the tip of the side peripheral wall 22 b in the accommodation chamber 22 c is the piping member 1 around the protruding portion 6. In close contact with the outer wall 11, the accommodation chamber 22 c becomes an airtight space. It is preferable from the viewpoints of life, measurement accuracy, etc., to fill the accommodating chamber 22c, which has become an airtight space, with an inert gas such as dried nitrogen gas.
Reference numeral 8 in FIG. 1 denotes a screw feed mechanism for adjusting the initial value (offset) of the pressing force with respect to the projecting portion 6 of the crystal plate 21 by moving the holding base 25 forward and backward.

The information processing means 5 is an electric circuit including a CPU, a memory, a counter, and the like. The information processing means 5 receives an oscillation signal from the pressure sensor 2, measures its frequency with a counter, and calculates a pressure from the frequency. . In the pressure sensor 2 of the present embodiment, the correlation between the pressure and the frequency is a linear function as shown in Table 1 and FIG. 7, and the reproducibility is very good. Therefore, the pressure can be accurately calculated from the frequency. it can. Here, the approximate expression representing the linear function is y = 6.650x + 8.589. That is, the measurement frequency can be handled as pressure.

Thus, the procedure by which the information processing means 5 calculates the flow rate will be described. When the frequencies of the oscillation signals of the pressure sensors 2 are f _u (upstream side) and f _d (downstream side), respectively, The measurement pressure P _u and the measurement pressure P _d on the downstream side are respectively P _u = a · f _u + b
P _d = a · f _d + b
It can be expressed as. Here, a and b are constants determined in advance by experiments or the like.
Therefore, the differential pressure ΔP is expressed as follows: ΔP = P _u −P _d = a · (fu−fd) = a · Δf

By the way, since the square value of the flow rate Q is proportional to ΔP,
Q = c · √ (ΔP) = k√ (Δf)
It becomes. Here, c is a constant determined in advance by experiment or the like, and k is a multiplication value of a and c.

  Therefore, the information processing means 5 calculates the flow rate Q by multiplying the square root of the frequency difference Δf by a coefficient k determined by experiments.

  The instrumental difference of each pressure sensor 2 is corrected by a counter in the information processing means 5.

<Second Embodiment>
As schematically shown in FIG. 8 as a whole, the flow measuring device 100A according to this embodiment includes an upstream side and a downstream side piping member 1A through which a fluid to be subjected to flow rate measurement flows, and the piping member 1A. 3A, a pair of pressure sensors 2A provided on each piping member 1A for measuring the pressure of the fluid, and receiving pressures measured by the pressure sensors 2A and based on the measured pressures. It is a so-called differential pressure type equipped with information processing means 5A for calculating the flow rate of the fluid.

  Each part will be described in detail. As shown in FIG. 8, the piping member 1A is, for example, a resin (for example, PFA) tube having a circular cross section, the inner diameter thereof is equal, and the outer wall 11A has a thickness except for a thin portion 11aA described later. It is structured equally.

  As shown in FIG. 8, the restricting mechanism 3A has a block shape, more specifically, a rectangular parallelepiped shape, and a flow path 31A having a restricting function is passed through the inside. And the edge part of each said piping member 1A is inserted in the both ends of this aperture mechanism 3A, and it is comprised so that the piping member 1A and the said flow path 31A may be connected in series. The flow path 3A has a shape in which the central portion has a minimum inner diameter, the inner diameter gradually increases from the central portion, and reaches both ends smoothly. The flow path 31A is configured to be smoothly continuous with the upstream and downstream piping members 1A.

  As shown in FIGS. 8 and 9, the pressure sensor 2A includes a quartz plate 21A and a support 22A that supports the quartz plate 21A, and the oscillation frequency is increased by an external pressure acting on the quartz plate 21A. Since it changes, it is the type which outputs the oscillation signal of the crystal plate 21A as a pressure signal.

  The support body 22A includes a side edge support portion 22aA that supports the left and right side edge portions of the crystal plate 21A, and a base end support portion 22bA that supports the base end portion of the crystal plate 21A, and this base end support portion 22bA. Further, an electric circuit board PA for taking out an electric signal from the crystal plate 21A is attached.

  Since the crystal plate 21A is the same as that of the first embodiment, description thereof is omitted here.

  In this embodiment, as shown in FIGS. 8 and 9, bottomed grooves 4 </ b> A that circulate in the circumferential direction are provided in the piping member outer wall 11 </ b> A on the upstream side and the downstream side of the throttle mechanism 3 </ b> A, respectively. The bottomed groove 4A has a constant width that goes around the piping member 1A. As a matter of course, the thickness of the outer wall 11A at the bottom of the bottomed groove 4A is thinner than the thickness of the other outer wall 11A. . However, since the thin portion 11aA is more easily elastically deformed than the other outer wall 11A, in this embodiment, a partial region of the thin portion 11aA protrudes when the pressure of the fluid increases and immerses when the pressure decreases. It is comprised so that it may function as the protrusion part 6A. Then, the pressure sensitive surface of the pressure sensor 2A, that is, the tip pressure sensitive surface of the crystal plate 21A is brought into contact with the surface of the protruding portion 6A via a spacer 8A described later.

  More specifically, as shown in FIGS. 8 and 9, an outer shell body 7A having a block shape is tightly fixed around the bottomed groove 4A and the piping member 1A before and after the bottomed groove 4A, and the outer shell body 7A is fixed. A rectangular through hole 7aA extending from the surface of the groove to a part of the bottomed groove 4A is formed, and the pressure sensor 2A including the crystal plate 21A and the spacer 8A are accommodated and held in the through hole 7aA.

  More specifically, the outer shell body 7A has a cross-sectional contour shape equal to that of the throttle mechanism 3A, and the outer shell body 7A and the throttle mechanism 3A are continuously elongated. It is comprised so that it may make. The outer shell body 7A can be divided vertically into two along the longitudinal direction, and the periphery of the piping member 1A can be covered by combining the divided halves 71A and 72A.

  The spacer 8A has a block body shape whose bottom surface is curved in accordance with the curvature of the bottomed groove 4A, and is a protruding portion that is a part of the bottomed groove 4A exposed by the through hole 7aA. The through hole 7aA is fitted so as to be in contact with the outer surface of 6A. Further, the spacer 8A is disposed in the through hole 7aA so as to be movable only in the vertical direction in accordance with the projecting and retracting operation of the projecting and recessed portion 6A.

  The pressure sensor 2A can detect the pressure of the fluid via the projecting part 6A and the spacer 8A by arranging the pressure-sensitive surface of the quartz plate 21A so as to contact the outer surface of the spacer 8A. ing. As in the first embodiment, the crystal plate 21A is arranged so that its face plate portion is parallel to the fluid flow direction, that is, the longitudinal direction of the piping member 1A.

  Since the structure of the information processing means 5A and the flow rate calculation method by the information processing means 5A are the same as those in the first embodiment, description thereof is omitted here.

The present invention is not limited to the above embodiment.
For example, the pressure sensor is not necessarily required upstream and downstream of the throttle mechanism. For example, when the upstream or downstream pressure is known, for example, connected to a vacuum or a constant pressure source, There is no need for a pressure sensor on the pressure side, or a through-hole or a projecting portion for holding the pressure sensor.

  Moreover, you may comprise the fluid pressure measuring device which measures the pressure of the fluid which flows through the inside using a piping member and a single pressure sensor, without providing a throttle mechanism. Thus, the present invention can also be applied as a fluid pressure measuring device capable of measuring pressure while maintaining a contamination-free state.

  Furthermore, although it is the pressure sensor 2 in 1st Embodiment, the opening of the storage chamber 22c may be sealed beforehand with a thin film member, for example, and the storage chamber 22c may be made into airtight space beforehand. That is, a part of the wall forming the storage chamber 22c is made of a thin film member such as a deformable metal, the surface of the thin film member is set as a pressure-sensitive surface, and the crystal plate 21 is placed in the airtight space in the airtight space. You may arrange | position so that it may contact | connect the inner surface of the said thin film member with the attitude | position substantially perpendicular | vertical to a pressure-sensitive surface. In this way, the pressure sensor 2 alone can be assembled in advance. In this case, the surface of the thin film member and the surface of the protrusion 6 may be attached.

  Further, for example, the protruding portion may be configured such that a certain region of the outer wall of the piping member is a thin portion 11a, and the thin portion itself functions as a protruding portion.

  Further, the pressure sensor is not limited to a quartz plate, and a pressure sensor using a piezoelectric element or another type may be used.

  In addition, it is needless to say that the present invention may be combined with some or all of the above-described embodiments and modified embodiments as appropriate, and various modifications are possible without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100, 100A ... Flow volume measuring apparatus 1, 1A ... Piping member 11, 11A ... Outer wall 11a, 11aA ... Thin part 2, 2A ... Pressure sensor 21, 21A ... Quartz plate 3, 3A: Drawing mechanism 4, 4A ... Bottomed groove 6, 6A ... Projection 7A ... Outer shell

Claims (7)

A pipe member through which a fluid whose flow rate is to be measured flows, a throttle mechanism provided between the pipe members, and a pair of pressure sensors provided on the upstream side and the downstream side of the throttle mechanism to measure the pressure of the fluid. A flow rate measuring device for measuring a flow rate of the fluid based on a pressure measured by each pressure sensor,
The pipe member is provided with a thin portion having a concave outer surface at a position where the pressure sensor is disposed, and a projecting portion that projects in a radial direction due to elastic deformation of the thin portion due to pressure fluctuation of the fluid is formed. A flow rate measuring device, wherein the pressure sensitive surface of the pressure sensor is brought into contact with the outer surface of the part. The pressure sensor detects the pressure acting on the pressure-sensitive surface by changing the oscillation frequency of the crystal plate while using the edge of the crystal plate as a pressure-sensitive surface,
The flow rate measuring device according to claim 1, wherein the quartz plate is arranged in a posture substantially perpendicular to the surface of the projecting portion, and a pressing force from the projecting portion acts on an edge of the crystal plate. .   The flow rate measuring device according to claim 1 or 2, wherein the pressure sensor is attached to a piping member so that a face plate portion of the crystal plate is parallel to a fluid flow direction.   The flow rate measuring device according to claim 1, 2 or 3, wherein a bottomed groove that circulates is provided on an outer wall of the piping member, and a bottom portion of the bottomed groove functions as the protruding and recessed portion.   An outer shell body that is tightly fixed around the bottomed groove and the pipe members before and after the bottomed groove is formed, and a through hole that extends from the surface of the outer shell body to the bottomed groove is formed, and the quartz crystal is formed in the through hole. The flow rate measuring device according to claim 4, wherein the plate is accommodated and held.   The flow rate measuring device according to claim 1, 2, 3, 4, or 5, wherein the throttle mechanism is integrally and continuously provided with the same material as the piping member. A fluid pressure measuring device comprising a piping member through which a fluid whose flow is to be measured flows, and a pressure sensor for measuring the pressure of the fluid,
The pipe member is provided with a thin-walled portion whose outer surface side is recessed at a required portion of the outer wall to form a projecting and projecting portion that projects by elastic deformation of the thin-walled portion due to pressure fluctuations of the fluid, A fluid pressure measuring device, wherein a pressure sensitive surface of the pressure sensor is in contact with the fluid pressure sensor.