JP2007058516A - Body structure for mass flow controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a body structure for a mass flow controller allowing improvement of measurement accuracy and mass flow control accuracy by suppressing transmission of stress distortion generated in screwing without depending on skill of an installation worker of fastening torque management or the like, and allowing weight reduction as a whole. <P>SOLUTION: A thick portion 2D except a surrounding portion 2B of peripheries of fluid conduits 10a-10d and fixing holding portions 2A of pressure gauges 3 of a rectangular parallelepiped body block 2 wherein the capacitance-type pressure gauges 3 are stored, disposed and fixed inside a plurality of recessed parts 5 and wherein a thick part is formed with the fluid conduits 10a-10d for applying fluid pressure to each the pressure gauge 3 are cut off and removed. A plurality of installation parts 12a-12c for screw fixing to a panel 11 or a main body box of the mass flow controller is formed correspondingly to the fixing holding portions 2A of the plurality of pressure gauges 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a body structure for a mass flow controller used for mass flow control of a fluid such as a reactive gas or a carrier gas supplied to a manufacturing process such as a semiconductor or a liquid crystal. Specifically, a pressure gauge for measuring a fluid flow rate is accommodated in each of a plurality of recesses formed in a rectangular parallelepiped body block, and each of these pressure gauges has a mounting flange formed around the opening end of the recess. The body block is fixed and held in an airtight and watertight state by fitting and tightening with a seal ring interposed therebetween, and fluid pressure is applied to the pressure receiving portion of each pressure gauge on the thick portion of the body block. Accordingly, the present invention relates to a body structure for a mass flow controller, in which a fluid flow path communicating with the recess is formed and the body block is fixed to a main body box or panel of the mass flow controller with screws.

  Some mass flow controllers employ means for measuring the fluid pressure at a plurality of points and calculating the actual fluid flow rate from the plurality of measured pressures in order to accurately control the mass flow rate of the fluid. As a mass flow controller body for realizing such means, conventionally, as shown in FIGS. 3 and 4, a plurality of recesses 21 are formed in a rectangular parallelepiped body block 20 called a bar, and these recesses are formed. A fluid pressure measurement fluid pressure measuring pressure gauge 25 is housed and fixed in an airtight and watertight state at 21, and fluid pressure is applied to the pressure receiving portion of each pressure gauge 25 on the thick portion of the body block 20. A flow path 22 was formed, and the body block 20 was configured to be fastened and fixed to a main body box or panel 23 of a mass flow controller via screws 24 such as bolts.

  However, when screwing and fixing the rectangular parallelepiped body block 20 to the main body box of the mass flow controller as described above, high accuracy is required for the flatness of the mutual contact surface between the body block 20 and the main body box of the mass flow controller. . If the flatness accuracy of any one of the contact surfaces is low, when the screws 24 are tightened strongly, at least one of the plurality of pressure gauges 25 is not only tilted, but a large stress is generated in the body block 20 to cause mechanical stress. Distortion, and as a result, the pressure measurement accuracy is liable to be adversely affected. When the body block 20 is screwed and fixed to the thin mass flow controller panel 23, the panel 23 itself is distorted and deformed by a large stress due to the strong tightening force of the screws 24, and the distortion is caused by a plurality of pressure gauges. 25, the original performance of the pressure gauge 25 is impaired and the pressure measurement accuracy, and hence the mass flow rate control accuracy of the fluid, tends to be adversely affected.

  Such adverse effects on measurement accuracy and mass flow control accuracy can be eliminated to some extent by improving the tightening torque management of screws by the installation operator, but depending on the installation operator's skill The measurement accuracy depends on the skill and tends to vary. This may cause the product (mass flow controller) yield to deteriorate, and is not unacceptably allowed as an actual problem.

  The present invention has been made in view of the above circumstances, and its purpose is not influenced by the skill of the mounting operator such as tightening torque management, and the stress strain generated at the time of screwing is generated in the housing fixing portion of the pressure gauge. An object of the present invention is to provide a body structure for a mass flow controller that can suppress the transmission and improve the measurement accuracy and the mass flow rate control accuracy and can also reduce the overall weight.

  In order to achieve the above object, the mass flow controller body structure according to the present invention has a fluid flow measurement pressure gauge accommodated in each of a plurality of recesses formed in a rectangular parallelepiped body block. The mounting flange portion is fixed and held in an airtight and watertight state in the body block by fitting and tightening a seal ring to a stepped portion formed around the opening end of the recess, and the wall thickness of the body block The fluid passage is connected to the recess so as to apply fluid pressure to the pressure receiving portion of each pressure gauge, and the body block is fixed to the body box or panel of the mass flow controller with screws. A body structure for a mass flow controller, wherein the plurality of pressures in the body block A main body box or panel of the mass flow controller corresponding to the fixed holding portions of a plurality of pressure gauges by cutting off and removing the remaining thick portion excluding the portion for housing and fixing and the surrounding portion of the outer periphery of the fluid flow path A plurality of attachment portions for fixing with screws are formed.

  The body structure for a mass flow controller of the present invention adopting the above-described characteristic configuration includes a mounting portion for fixing screws to the main body box or panel of the mass flow controller and a housing fixing portion for a plurality of pressure gauges. This occurs when the screws are fastened because the housing and fixing parts of the pressure gauge are not rigidly connected with high mechanical strength but are connected with a flexible structure with slits and cuts between them. It is possible to suppress the occurrence of distortion in each part due to the large stress to be transmitted and the transmission of the distortion to other parts. Therefore, advanced skills such as strict management of tightening torque are not required, and the body block can be attached to the body of the mass flow controller while maintaining the original performance of each pressure gauge, even for low-skill installation workers. By fixing with screws to the box or panel, the measurement accuracy, and thus the accuracy of controlling the mass flow rate of the fluid can be significantly improved. In addition, by removing the excess portion, the weight of the body can be reduced and the mass flow controller as a whole can be reduced in weight and cost can be reduced.

  In the body structure for a mass flow controller according to the present invention, as described in claim 2, the fluid flow rate or pressure is automatically set in parallel with the plurality of pressure gauges in the body block according to the pressure measured by the pressure gauges. A fluid control valve to be controlled may be attached. In this case, the mass flow rate or pressure control action of the fluid accompanying the control operation of the fluid control valve according to the pressure measured by the plurality of pressure gauges can be stably performed, and the performance improvement of the entire mass flow controller can be achieved.

  Further, in the body structure for a mass flow controller according to the present invention, in order to improve the measurement accuracy and reduce the weight as described above while maintaining sufficient fixing (attachment) strength of each part, As described in the item 3, it is preferable that the portion for accommodating and fixing and holding the plurality of pressure gauges, the surrounding portion of the outer periphery of the fluid flow path, and the plurality of attachment portions are formed so as to have a required strength. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing an example of a body structure for a mass flow controller according to the present invention, and FIG. 2 is a plan view thereof. This mass flow controller body 1 has a rectangular parallelepiped body block 2 made of a corrosion-resistant material such as stainless steel, and is arranged in parallel in the longitudinal direction (two in the drawing, but three or more). The capacitance type pressure gauge 3 for measuring the fluid flow rate and the valve 4 for automatically controlling the fluid flow rate or pressure are provided.

  Each of the capacitance type pressure gauges 3 is provided with a diaphragm 3B serving as a pressure receiving portion on one end opening side of the cylindrical case 3A, and an annular shape projecting outward on the other end side of the cylindrical case 3A. The flange portion 3C is integrally formed. These capacitance-type pressure gauges 3 are accommodated and disposed in a recess 5 formed in the body block 2 so that the diaphragm 3B is positioned on the bottom side, and the annular flange portion 3C and the open end of the recess 5 A seal ring 7 such as a metal gasket is interposed between the annular stepped portion 6 formed around it, and is fixed and held in an airtight and watertight state by the body block 2 via a pressing member 8 and a fastening bolt 9. ing. The automatic control valve 4 is fixed to the upper surface of the body block 2.

  Further, in the thick part of the body block 2, the capacitive pressure is applied so that the fluid pressure acts on the diaphragm 3 </ b> B of the upstream capacitive pressure gauge 3 of the two capacitive pressure gauges 3. The fluid introduction flow path 10a connected in communication with the recess 5 that accommodates the meter 3 and the fluid pressure after acting on the diaphragm 3B of the upstream capacitive pressure gauge 3 are transferred to the downstream capacitive pressure gauge 3. A fluid flow path 10b that connects the two recesses 5 that house the two capacitive pressure gauges 3 in order to act on the diaphragm 3B, and a fluid after acting on the diaphragm 3B of the downstream capacitive pressure gauge 3 A fluid flow path 10c for applying pressure to a diaphragm (which is well known and not shown) serving as a drive unit for an orifice opening / closing valve body in the automatic control valve 4, and the automatic control valve From 4 Fluid discharge passage 10d is formed.

  Of the body block 2, the outer periphery of the substantially cylindrical portion 2 </ b> A that surrounds the periphery of the concave portion 5 and the annular step portion 6 that accommodates and holds the two capacitance pressure gauges 3 and the fluid flow paths 10 a to 10 d. The remaining thick wall portion 2D (the portion surrounded by the dotted line in FIGS. 1 and 2) excluding the surrounding flow path wall portion 2B and the rectangular portion 2C in plan view that fixes the automatic control valve 4 is cut off and removed, and Three attachment portions 12a, 12b, and 12c for fixing screws to the main body box or panel 11 of the mass flow controller are respectively provided at the lower ends of the body blocks 2 corresponding to the two substantially cylindrical portions 2A and the rectangular portion 2C. Is formed.

  The mass flow controller body 1 configured as described above is fastened and fixed to the main body box or panel 11 of the mass flow controller via screws 13 at the three attachment portions 12a, 12b, and 12c formed in the body block 2. Further, the fluid introduction channel 10a and the fluid discharge channel 10d are used by being connected to a fluid channel in a main body box of the mass flow controller or a fluid pipe disposed under the panel 11 of the mass flow controller.

  And in the above usage modes, fluid pressures such as gas introduced into the fluid introduction flow path 10a are respectively measured by the two capacitance pressure gauges 3, and the substantial flow rate of the fluid is determined from these two measurement pressures. Based on the calculation, the automatic control valve 4 is controlled and automatically controlled so that the mass flow rate or pressure of the fluid becomes a set value.

  In the mass flow controller body 1 used in this way, it is an abbreviation that serves as a housing fixing part for fixing the screws 12 to the main body box or the panel 11 of the mass flow controller 12a, 12b, 12c and the two capacitance type pressure gauges 3. The cylindrical portions 2A and the two substantially cylindrical portions 2A are not mechanically rigidly connected with great strength, but have a flexible structure in which there are slits S and cuts C between them. Since they are connected, it is possible to suppress distortion of each part due to the large stress generated when the screws 13 are strongly tightened by the mounting parts 12a, 12b, and 12c, and to prevent the distortion from being transmitted to other parts. can do. Therefore, the body block 2 is strongly screwed to the main body box or panel 11 of the mass flow controller while maintaining the original performance of each pressure gauge 3 without requiring high skills such as strict management of the tightening torque. It is possible to remarkably improve the measurement accuracy as well as the control accuracy of the mass flow rate of the fluid.

  In addition, by cutting off and removing the extra thick portion of the body block 2 as much as possible, the weight of the body 1 can be reduced and the overall mass flow controller can be reduced in weight and cost can be reduced.

  In the above embodiment, the body block 2 is provided with the valve 4 for automatically controlling the fluid flow rate or pressure in parallel with the two capacitance type pressure gauges 3. It can be similarly applied to a so-called mass flow meter that is omitted.

  In the above embodiment, a capacitance type pressure gauge is used as a pressure gauge for fluid flow rate measurement, but any other type of pressure gauge may be used.

It is a longitudinal cross-sectional view which shows an example of the body structure for mass flow controllers which concerns on this invention. It is a top view of the body structure for mass flow controllers same as the above. It is a top view which shows the outline | summary of the body for conventional mass flow controllers. It is a side view which shows the outline | summary of the attachment state of the body for conventional mass flow controllers same as the above.

Explanation of symbols

1 Body for mass flow controller 2 Body block 2D Cut-off wall thickness part 3 Capacitance type pressure gauge 3B Diaphragm (pressure receiving part)
3C Flange part 4 Valve for automatic control 5 Recessed part 6 Step part 7 Seal ring 10a-10d Fluid flow path 11 Mass flow controller main body box or panel 12a-12c Mounting part

Claims (3)

A plurality of recesses formed in the rectangular parallelepiped-shaped body block are accommodated and arranged in a plurality of recesses, and each of these pressure gauges has a mounting flange portion around the opening end of the recess and a seal ring at a stepped portion. The body block is fixed and held in an airtight and watertight state by fitting and tightening with each other, and the thick portions of the body block are configured to apply fluid pressure to the pressure receiving portions of the pressure gauges. A body structure for a mass flow controller in which a fluid flow path connected to the recess is formed, and the body block is configured to be screwed and fixed to a body box or panel of the mass flow controller,
A portion of the body block that contains and holds the plurality of pressure gauges and a remaining thick portion excluding the surrounding portion of the outer periphery of the fluid flow path are cut off and removed, and the fixed holding parts of the plurality of pressure gauges are removed. Correspondingly, a plurality of attachment portions for fixing the mass flow controller to the main body box or panel are formed.   2. The mass flow controller according to claim 1, wherein a fluid control valve is attached to the body block in parallel with the plurality of pressure gauges to automatically control a fluid flow rate or a pressure according to a pressure measured by the pressure gauges. For body structure. 3. The mass flow controller according to claim 1, wherein the plurality of pressure gauges are housed and fixedly held, the surrounding portion of the outer periphery of the fluid flow path, and the plurality of attachment portions are each formed to have a required strength. For body structure.

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