JPH0518799A - Laminar flow element and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a laminar flow element provided with a desirable laminar flow characteristic and finished into mirror like surface so as to be prevented from the adhesion and holdup of impurity by laminating plural polished thin plates in the closely attached state in the orthogonal direction to the flow direction of a fluid, and forming a passage among them. CONSTITUTION:Rectangular polished thin plates 10, 11 of equal size are laminated plural times in the closely attached state in the orthogonal direction to the flow direction of a fluid, and a passage 16 is formed among them. Between a first thin plate 13 and a second thin plate 14 respectively without elongated holes 12, the thin plate 10 with an elongated hole 12 formed therein is held by the thin plate 11 without an elongated hole 12, and these thin plates 10, 11 are laminated plural times by brazing. All the thin plates 10, 11, 13, 14 are then cut in such a way as to transverse both end part inner sides of the elongated holes to obtain a laminar flow element S. The clean and high performance laminar flow element prevented from attracting impurity can be obtained since the surface of the thin plates can be polished into mirror like surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminar flow element used in a laminar flow meter for measuring the flow rate of a fluid such as gas and a method for manufacturing the same.

As the laminar flow element, as shown in FIG. 7A, a plurality of thin tubes 31 are inserted into an outer tube 32, or as shown in FIG. A stack of many thin plates 34 having holes 33 (for example, Japanese Patent Publication No. 1-403
No. 00) or as shown in FIG. 1C, a thin plate 36 having a through hole 35 in the center and a plurality of communicating passages 37 communicating the through hole 35 and the outer periphery of the thin plate 36 in the radial direction. A plurality of layers are laminated so that the fluid flows from the outer periphery of the thin plate 36 through the communication passage 37 to the through hole 35 at the center (for example, Japanese Patent Laid-Open No.
-2968). 7 (B) and (C)
Reference numerals 38 and 39 in the reference numerals indicate alignment holes when the thin plates 34 and 36 are overlapped with each other.

[0003]

However, in the laminar flow device shown in FIG. 7A, since a large number of thin tubes 31 are used, the inner and outer surfaces of the thin tubes 31 are polished to a mirror surface state. However, it is difficult to clean particles because impurities and particles contained in the fluid easily adhere to the thin tube 31. Further, in the laminar flow element shown in each of FIGS. 3B and 3C, since a large number of thin plates 34 and 36 are laminated in the fluid flowing direction, the thin plates 34 and 36 and the thin plates 34 and 36 are formed.
A large number of fluid retention parts are formed in the gaps between them (not shown), and as a result, particles and impurities contained in the fluid tend to accumulate, making cleaning difficult.

The present invention has been made in consideration of the above-mentioned matters, and an object of the present invention is not only to have good laminar flow characteristics as a laminar flow element but also to easily perform mirror finishing. It is an object of the present invention to provide a clean laminar flow element in which impurities and the like do not adhere and do not stay, and a manufacturing method thereof.

[0005]

In order to achieve the above object, a laminar flow element according to the present invention comprises a plurality of polished thin plates laminated in a state in which they are in close contact with each other in a direction orthogonal to a direction in which a fluid flows. It is characterized in that a flow path through which a fluid flows is formed therebetween.

One of the methods for manufacturing a laminar flow element according to the present invention is to form a plurality of thin plates having long holes between a first thin plate and a second thin plate having no long holes. A thin plate having no holes is sandwiched, and in that state, all the thin plates are cut so as to traverse the inside of both ends of the elongated hole, and a flow path is provided between the first thin plate and the second thin plate. Is formed.

Another method of manufacturing a laminar flow element according to the present invention is one in which a plurality of thin plates having notches are formed between a first thin plate having no notches and a second thin plate. , Sandwiching a thin plate having no cutout formed therebetween, and cutting all thin plates so as to cross the closed portion of the cutout in this state,
A feature is that a flow path is formed between the thin plate and the second thin plate.

[0008]

In the laminar flow element having the above-mentioned structure, since all the surfaces contacting with the fluid can be polished so as to be mirror-finished, impurities are hardly adsorbed. Further, since the fluid does not stay, even if impurities or the like are mixed in the fluid, they are quickly discharged to the outside of the laminar flow element together with the fluid. Therefore, a clean laminar flow element can be obtained.

In any of the methods for producing a laminar flow element, since the surface of the thin plate can be polished to be a mirror surface, a clean laminar flow element that does not adsorb impurities and the like can be obtained. Can be easily manufactured.

[0010]

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

First, FIG. 2 shows an essential part of a laminar flow type flow meter incorporating a laminar flow element S according to the present invention. In this figure, reference numeral 1 is a flow meter block, and its fluid inlet 2 and fluid conduit. As shown in FIG. 1, the bypass flow path 4 between the outlet 3 and the outlet 3 is provided between a plurality of polished thin plates 10 and 11 which are stacked in close contact with each other in a direction orthogonal to the direction of fluid flow. The laminar flow element S (the detailed structure and manufacturing method thereof will be described later) in which the flow path 16 through which the fluid flows is formed is provided. Reference numeral 5 is a measurement flow path provided in parallel with the bypass flow path 4, and is provided so as to connect between the openings 6 and 7 opened on the upstream side and the downstream side of the laminar flow element S, and a horizontal portion thereof. Two sensor coils 9, which are connected to a bridge circuit (not shown) and are constituent elements thereof, are wound around the outer periphery of 8 at appropriate intervals.

Next, the structure of the laminar flow element S and the manufacturing method thereof will be described with reference to FIGS. In FIG. 3 (A), reference numerals 10 and 11 are rectangular thin plates made of metal such as stainless steel having excellent chemical resistance and corrosion resistance and having the same size. For example, 40 mm (length) × 10 mm (width)
X 0.2 mm (thickness), one thin plate 10
A long hole 12 having a size of 30 mm (length) × 5 mm (width) is formed therein by, for example, etching. Then, a plurality of such thin plates 10 and 11 are alternately stacked as shown in FIG. 9A, and adjacent thin plates 10 and 11 are fixed by brazing, for example. In this case, it is desirable that the surfaces of the thin plates 10 and 11 be sufficiently polished and mirror-finished before they are superposed. Further, at the beginning and the end of the stacking, the thin plates 11 without the long holes are placed. Hereinafter, the thin plates at the upper and lower ends are respectively referred to as the first thin plate 1
3, called the second thin plate 14.

Next, in a state where the thin plates 10 and 11 are overlapped with each other by brazing, as shown in FIG. 1B, the thin plates 10 and 11 are crossed in the laminating direction slightly inside from both ends of the long hole 12,
Cut all sheets 10 and 11. 15 shows one cutting position. By this cutting, a space with both ends opened is formed in the thin plate 10, and this serves as the flow path 16. That is, a plurality of flow paths 16 are formed between the laminated thin plates 10 and 11. In this case, the flow path 16 is preferably cut so as to have a length necessary for forming a laminar flow (for example, at least 20 mm). Then, as shown in FIG. 4, a pair of holding members 17 is provided on one end side of the laminated thin plates 10 and 11 in the longitudinal direction to form the laminar flow element S.

The laminar flow element S manufactured as described above
Is provided in the bypass flow path 4 of the laminar flow meter so that the laminating direction of the thin plates 10 and 11 is orthogonal to the fluid flow direction. In the laminar flow element S having such a configuration, the flow path 16
Since the length is set to be equal to or longer than the length required to form the laminar flow, desired laminar flow characteristics can be obtained. Then, since the surfaces of the thin plates 10 and 11 can be sufficiently polished in advance or surface modification treatment can be performed, the flow path 16 in contact with the fluid is provided.
The inside can be finished to a desired mirror surface state. Therefore,
Even if impurities or the like are mixed in the fluid, they are less likely to adhere to the flow path 16.

The present invention is not limited to the above embodiment, but as shown in FIG. 5, the thin plate 10 may be provided with a plurality of elongated holes 12.

In each of the above-described embodiments, the thin plate 10
Although the long hole 12 is provided in the thin plate 10, as shown in FIG. 6, the thin plate 10 is provided with a plurality of notches 18, and the thin plate 10 and the thin plate 11 not having the notches are alternately superposed. All thin plates 10 so as to traverse the closed portion 19 of the cutout portion 18 in the state,
11 may be disconnected. In this embodiment, it goes without saying that the thin plate 10 may be provided with only one cutout portion 18.

The fluid flow rate in the laminar flow element S according to the present invention is defined by the ratio of the number of laminated thin plates 10 and 12 between the first thin plate 13 and the second thin plate 14 and the total number of laminated layers. It can be arbitrarily set by changing it. Also, the first
Between the thin plate 13 and the second thin plate 14, it is not always necessary to alternately stack the thin plates 10 having the long holes 12 or the notches 18 and the thin plates 11 having no long holes formed therein.
May be continuously laminated. In this case, the channel 16 becomes larger accordingly.

Further, it is needless to say that the numerical values of the above respective parts are merely examples and are not limited to these.

[0019]

As described above, in the laminar flow device according to the present invention, since all the surfaces in contact with the fluid can be polished to be mirror-finished, impurities are not adsorbed. Also, since no fluid retention occurs,
Even if impurities and the like are mixed in the fluid, they are quickly discharged to the outside of the laminar flow element together with the fluid. Therefore, a clean laminar flow element having a desired flow rate characteristic can be obtained.

In the method for manufacturing a laminar flow element according to the present invention, since the surface of the thin plate can be polished to be a mirror surface, a clean laminar flow element that does not adsorb impurities and the like. Can be easily manufactured, and a high-performance laminar flow element can be obtained at low cost.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a laminar flow element according to the present invention in an assembled state.

FIG. 2 is a vertical cross-sectional view showing an essential part of a laminar flow meter incorporating the laminar flow element.

3A and 3B are diagrams showing an example of a method for manufacturing a laminar flow device.

FIG. 4 is an exploded perspective view of a laminar flow element.

FIG. 5 is an exploded perspective view showing another example of a thin plate having long holes formed therein.

FIG. 6 is an exploded perspective view showing an example of a thin plate having a cutout portion.

7 (A), (B), and (C) are diagrams showing a conventional laminar flow element, respectively.

[Explanation of symbols]

S ... Laminar flow element, 10, 11 ... Thin plate, 12 ... Long hole, 13 ... First thin plate, 14 ... Second thin plate, 16 ... Flow path, 18 ... Notch portion, 19 ... Closure portion.

Claims (3)

[Claims] 1. A laminar flow device characterized in that a fluid flow path is formed between a plurality of polished thin plates laminated in a state in which they are in close contact with each other in a direction orthogonal to the direction in which the fluid flows. 2. A plurality of thin plates having long holes are sandwiched between a first thin plate and a second thin plate having no long holes, and the thin plates having no long holes are sandwiched between them. Cut all the thin plates so that they cross the inside of both ends of the long hole,
A method for manufacturing a laminar flow element, characterized in that a flow path is formed between the thin plate and the second thin plate. 3. A plurality of thin plates each having a notch formed between a first thin plate and a second thin plate not having a notch, and a state in which the thin plates not having the notch are sandwiched therebetween. 2. A method for manufacturing a laminar flow element, characterized in that all the thin plates are cut so as to cross the closed portion of the cutout portion, and a flow path is formed between the first thin plate and the second thin plate.