JP2535089Y2 - Laminar flow element - Google Patents

Description

[Detailed description of the invention]

[0001]

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

[0002]

2. Description of the Related Art As the laminar flow element, as shown in FIG. 3A, a plurality of thin tubes 31 are inserted into an outer tube 32, or as shown in FIG. (For example, Japanese Patent Publication No. 1-4
No. 0300) and a thin plate 36 having a through hole 35 at the center and a plurality of communication passages 37 in the radial direction for communicating the through hole 35 and the outer periphery of the thin plate 36 as shown in FIG. Are stacked 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,
No. 50-2968). Note that FIG.
Reference numerals 38 and 39 in (C) denote positioning holes when the thin plates 34 and 36 are overlapped, respectively.

[0003]

However, in the laminar flow element shown in FIG. 3A, in addition to the thin tube 31 which is the original fluid flow path, the space between the thin tubes 31 and the thin tube 31 are not included. There is also a fluid contact surface in the gap (not shown) between
Further, in the laminar flow elements shown in FIGS. 3B and 3C, in addition to the through holes 33 and 35 which are the original fluid flow paths,
The gaps (not shown) between the laminated thin plates 34, 36 and the thin plates 34, 36 also had a fluid contact surface, and the fluid easily stayed in these gaps. If there is a gap in which the fluid tends to stay as described above, there is an inconvenience that when a fluid is switched from one fluid to a fluid having a different chemical property (when switching between different fluids), it takes a considerably long time to replace the fluid.

The present invention has been made in consideration of the above-mentioned matters, and the purpose thereof is to provide not only a good laminar flow characteristic as a laminar flow element but also a replacement at the time of switching different kinds of fluids. It is to provide a laminar flow element having good characteristics.

[0005]

In order to achieve the above object, a laminar flow element according to the present invention comprises a plurality of through-holes formed independently of each other in a plane of a plate-like body orthogonal to a direction in which a fluid flows. In each, a thin tube of a length necessary to form a laminar flow is inserted, so that no gap is formed between the through-hole, and on each of the upstream and downstream sides of the plate-like body,
The tube is fastened so that the opening position is different.

[0006]

In the above-mentioned laminar flow element, elements having different opening positions of the thin tubes and different projecting lengths from the plate surface are present on both the upstream side and the downstream side of the plate.
Therefore, on the upstream side of the plate-like body, the fluid in the portion close to the surface of the plate-like body is conveyed to the downstream side in such a manner as to be sucked into the narrow tube projecting closer to the plate-like body. Further, on the downstream side of the plate-like body, the fluid in the portion near the plate-like body surface is carried to the downstream side together with the fluid that has passed through the narrow tube projecting closer to the plate-like body. As a result, the fluid is located upstream and downstream of the plate, respectively.
It does not stay and flows while forming a laminar flow.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

First, FIG. 2 shows a main 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 denotes a flow meter block, which has a fluid inlet 2 and a fluid conducting port. A laminar flow element S, which will be described later, is provided in the bypass channel 4 between the outlet 3. Reference numeral 5 denotes 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, respectively. Around the outer periphery of 8, two sensor coils 9 connected to a bridge circuit (not shown) are wound around at an appropriate interval.

Next, a configuration example of the laminar flow element S will be described with reference to FIG. 1. Reference numeral 10 denotes a plate-like body made of a metal having excellent chemical resistance and corrosion resistance such as stainless steel. Is formed in a disk having a thickness of about 1 mm. This plate
In 10, a plurality of through holes 11 are formed independently of each other and perpendicular to both surfaces without any deviation.

Reference numeral 12 denotes a through hole, which is inserted into each of the through holes 11.
The thin tubes are fixed so as to be parallel to each other by, for example, brazing so that no gap is formed between the tubes. It is preferable that the thin tube 12 has a length necessary for forming a laminar flow (for example, at least 20 mm). In this embodiment, a stainless steel tube having an inner diameter of 0.1 mm and a length of 25 mm is used. Used.

The thin tube 12 is provided on the plate 10 as follows. That is, on the upstream side (left side in the figure) of the plate-like body 10, the projecting length from the upstream side surface is long, and the opening position is far from the upstream-side surface. A small tube (hereinafter referred to as 12A) having a short projecting length from the side surface and an opening position close to the downstream surface, and a short projecting length from the upstream surface on the upstream side and an opening position A thin tube (hereinafter, indicated by reference numeral 12B) close to the surface (therefore, on the downstream side of the plate-shaped body 10, the projection length from the downstream surface is long and the opening position is far from the downstream surface) is not biased. Are provided in a mixed state. The mixing ratio of the thin tubes 12A and 12B is arbitrary.

In the laminar flow element S configured as described above, the opening positions of the thin tubes 12 (12A, 12B) are different on the upstream side and the downstream side of the plate-like body 10, respectively, and the projecting length from the surface is different. But different ones are mixed. Therefore, on the upstream side of the plate-like body 10, the fluid in the portion close to the surface of the plate-like body 10 is a thin tube 12 protruding closer to the surface.
B is carried to the downstream side as if sucked. Also,
On the downstream side of the plate-like body 10, the fluid near the surface of the plate-like body 10 is a thin tube protruding closer to the surface.
It is carried downstream with the fluid that has passed through 12A. As a result, the fluid does not stay on each of the upstream side and the downstream side of the plate-shaped body 10 and flows while forming a laminar flow.

Therefore, in a laminar flow meter in which the above-described laminar flow element S is incorporated so that the surface thereof is orthogonal to the direction in which the fluid flows, there is no fluid stagnation in the bypass flow path 4. The replacement speed when switching between different fluids is increased. Further, even if particles or impurities are mixed in the fluid, the fluid is immediately discharged.

The length of the thin tube 12 is not always required to be uniform, and may be set to at least a length capable of forming a laminar flow.

[0015]

[Effects of the Invention] As described above, according to the present invention,
A laminar flow element having good laminar flow characteristics and capable of promptly replacing a fluid when switching between different types of fluids is obtained. In addition, its manufacture is easy, and a high-performance laminar flow element can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a laminar flow element according to the present invention.

FIG. 2 is a longitudinal sectional view showing a main part of a laminar flow meter incorporating the laminar flow element.

FIGS. 3A, 3B, and 3C are diagrams showing a conventional laminar flow element, respectively.

[Explanation of symbols]

 S: laminar flow element, 10: plate, 11: through hole, 12: thin tube.

Claims (1)

(57) [Scope of request for utility model registration] 1. A thin tube having a length necessary for forming a laminar flow is inserted into each of a plurality of through-holes formed independently of each other in a plane of a plate-shaped body orthogonal to a direction in which a fluid flows, and A laminar flow element wherein a narrow tube is fastened so that no gap is formed between the hole and the upstream side and the downstream side of the plate-like body so that the opening positions of the thin tubes are different.