JPH02153409A - Flow rate adjusting mechanism - Google Patents

Abstract

PURPOSE:To easily perform fine adjustment on the cross section of a passage in the diametral direction and to generate the laminar flow of liquid by comprising a flow rate adjusting member of a spring in which thin plates superposed in parallel are formed in coil shape. CONSTITUTION:The flow rate adjusting member 40 is comprised of the spring 46 with a uniform major diameter in which the thin plates are supposed in parallel with each other, and the passage in a radial direction can be changed by compression, and the cross section of the passage goes to zero when a gap is compressed so as to go to zero. The spring 46 is formed in a so-called coil shape flat spring. In such a way, it is possible to keep parallel relation between the thin plates, and to generate the laminar flow of the liquid that flows between the thin plates, and to accurately perform the measurement of a flow rate.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a flow rate adjustment mechanism that adjusts a fluid flow rate measurement range in, for example, a mass flow controller or the like.

Conventional technology and its challenges Conventionally, gas measurement and control have been performed using volumetric flowmeters, but recently, with the automation and computerization of manufacturing equipment, mass flow controllers that can be operated using electrical signals for both measurement and control have become widespread. It has come to be used.

In this case, the gas is divided into a sensor part and a bypass part,
The overall gas flow rate is detected by thermoelectrically detecting the flow rate in a portion of the sensor while keeping the flow rate ratio between the two constant. The bypass section has a flow m between the wall section provided in the middle of the flow path and the pressing member.
Ai adjustment member is provided to form a radial wave path, and the cross-sectional area of the radial flow path is changed to adjust the gas flow rate in a laminar flow state, which is different from the conventional flow rate adjustment member. In this case, a large number of annular thin plates arranged in a laminated manner was used, and the annular thin plates had grooves formed in the radial direction by photo-etching. However, forming grooves using this photoetching method is not only troublesome, but also increases or decreases the cross-sectional area of the radial flow path by increasing or decreasing the number of ring core thin plates. Taking them in and out for selection was an extremely troublesome task.

On the other hand, the fluid throttle valve described in JP-A No. 55-97569 adjusts the flow rate by expanding and contracting a coil spring provided in the flow path, but the coil spring is simply a coiled wire with a circular cross section. Since it is wound, the flow of the fluid does not become laminar but becomes turbulent, which poses a problem that it cannot be used for the purpose intended by the present invention.

In addition, the constant air flow device described in Japanese Utility Model Publication No. 48-5860 adjusts the flow rate by expanding and contracting a generally conical coil spring whose winding diameter differs in the length direction. Since the flow is different in the length direction, the flow does not become laminar, which is the same as the above, and has the same problems.

Therefore, it is an object of the present invention to provide a mechanism in which the radial cross-sectional area of the flow path can be easily finely adjusted and the fluid flow becomes laminar in the above-mentioned flow rate adjustment mechanism. .

Means and Function for Solving the Problems The present invention provides a flow regulating mechanism as described above, in which the flow regulating member is constituted by a coil-shaped spring formed of thin plates overlapping each other in parallel with the pressure member. It is characterized by:

The thin plate-shaped coil spring as described above can form a wave path in the radial direction, and as the pressing member is screwed in, the cross-sectional area of the flow path in the radial direction decreases according to the amount of screwing. The flow guided by the mutually overlapping thin plates not only allows fine changes in the cross-sectional area of the flow path in a laminar flow state, but also acts to prevent the screw from loosening due to the repulsive force of the spring.

Embodiments Hereinafter, a case where embodiments of the present invention are applied to a mass flow controller will be described based on the accompanying drawings. In addition,
The embodiments are merely illustrative and are not intended to be limited to dirt. "Fluid" naturally includes not only gases such as gases but also liquids.

In FIG.
The secondary flow path is intended to finely adjust the flow rate of fluid from the primary flow path to the secondary flow path.

Reference numeral 30 is what is most commonly referred to as a bypass nut in the technical field of mass 70 controllers, and corresponds to a "pressing member" in the claims, with a threaded portion 31 at one end and a columnar nut at the other end. A protruding portion 32 is formed, an intermediate cylindrical portion 33 has a slightly smaller diameter than the threaded portion 31, and a hole 35 is formed further in the radial direction from the central flow path 34. The fluid flowing from the left side of FIG. 1 passes from the center flow path 34 through the hole 35, through the annular flow path 36 on the outside of the columnar portion 33, and flows from the outside of the columnar protrusion 32 to the secondary flow path 20. (See also Figure 2).

Reference numeral 40 denotes a flow rate adjustment member that is interposed between the bypass nut 30, which is a pressing member, and a wall portion 20' provided in the middle of the flow path to form a radial flow path. Note that if the wall portion 20' is not provided due to the relationship between the diameters of the primary flow path and the secondary flow path, an annular portion may be provided in the flow path to serve as the wall portion.

FIGS. 2 and 3 show this flow adjustment member 40, which consists of a spring 46 with a negative outer diameter formed by coiling thin plates overlapping parallel to each other. The direction of the flow path can be changed minutely, and when the gap is compressed to zero, the cross-sectional area of the flow path also becomes zero.

Since this spring 46 is a so-called coiled temporary spring, the thin plates are parallel to each other, and the fluid flowing between them becomes a laminar flow, allowing accurate flow rate measurement.

Further, by caulking the tip of the columnar projection 32 of the bypass nut 30, the spring 46 can be held so that it does not fall off.

It goes without saying that the shape of the columnar projection 32 is not limited to the triangular prism shape shown in FIG. 4, but also includes various shapes such as the modified triangular prism 32 in FIG. 5 and the square prism 32# in FIG. 6.

In FIG. 1, since a screw 10' is cut on the primary flow path side, by inserting a screwdriver from the outside and rotating the bypass nut 30 forward, the coil spring 46 is compressed and the flow in the radial direction is The cross-sectional area of the path can be changed minutely. The flow path area set at one end can be maintained at a constant value over a long period of time because the nut does not loosen because an axial force is always applied due to the action of the spring.

Note that the portion designated by the reference numeral 50 in FIG. 1 is a part of the sensor of the mass flow controller, but since this is not the gist of the present invention, a description thereof will be omitted.

Effects of the Invention As explained above, the present invention provides a flow rate adjustment mechanism that is extremely simple and can minutely change the flow rate of fluid in a laminar flow state using parallel overlapping thin plates of a coil spring. It is suitable for use in mass flow controllers and the like.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; Fig. 1 is a sectional view of essential parts of a mass flow controller, Fig. 2 is a perspective view of a bypass nut to which the invention is applied, and Fig. 3 is a front view of a thin plate-shaped coil spring. 4 to 6 are side views showing different embodiments of the columnar protrusion. 0.20...Wave path 0'...Wall portion 0...Pushing member 0...Flow rate adjustment member 6...Thin coil spring Fig. 1 Fig. 3/ Fig. 4 Fig. 5 Fig. 6 Figure 2

Claims (3)

[Claims] (1) A flow rate adjustment member is interposed between a wall portion provided in the middle of the flow path and a pressing member to form a radial flow path, and the cross-sectional area of the radial flow path is changed to 1. A flow rate adjustment mechanism for adjusting a flow rate, wherein the flow rate adjustment member is comprised of a spring made of thin plates stacked parallel to each other and formed into a coil shape. (2) The flow rate adjustment mechanism according to claim 1, wherein the pressing member has a threaded portion and a cylindrical portion having a smaller diameter than the threaded portion. (3) Claim 2, characterized in that the pressing member further has a columnar protrusion on the opposite side of the threaded part.
Flow rate adjustment mechanism described in section.