JPH082576Y2 - Extra-fine channel laminar flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an improvement of a laminar flow meter used in all industrial fields that handle fluids. A laminar flow type flow meter that uses the viscous resistance of the fluid is used for flow rate measurement and control, but the flow rate is reduced by a new matrix (laminar flow element) that enables ultrafine laminar flow channels.
By improving the pressure characteristics and improving the application method, we provide a convenient measurement / detection device in a wider field.

[Prior Art] A laminar flow meter (laminar
Flow meters) have been widely used. The laminar flow meter measures the flow rate approximately as a proportional function of the pressure difference from the relationship between the flow rate and the pressure difference along the tube axis when the flow is completely laminar in a smooth pipe channel. The matrix (laminar flow element), which is a set of such smooth flow passages, is the main factor that determines the performance of the laminar flow meter.

As a matrix (laminar flow element), (a) a bundle of circular tubes filled with gaps, (b) a thick plate with many holes, (c) a grid of thin plates (D) Wavy pressed thin plate and flat thin plate are overlaid,
There are spiral wound ones, and (e) thin sheets forming hexagonal channels. Of these, (d) is relatively easy to manufacture and is considered to be the most practical.

However, in the conventional type (d), that is, in the case where a thin plate pressed in a wave shape and a flat thin plate are stacked and spirally wound, the laminar flow, which is the main factor that determines the performance of the laminar flow meter, An element with a plate thickness of 25μ or more was used for structural reasons, and the hydraulic equivalent diameter of the flow path was 0.3mm or more. Generally, the linear relationship between the differential pressure and the flow rate, which is a characteristic of a laminar flow meter, is Re number 15
It is known that a value of 0 or less is good. The maximum flow velocity range was about 8 m / s for air at normal temperature and pressure.

Further, the differential pressure is also measured by a differential pressure sensor or a manometer using a conduit from the outer wall of the entire flow path pipe.

[Problems to be solved by the invention] With this type of conventional matrix, the differential pressure is 70 mmH ₂ O.
In the above, the deviation from the linear characteristic of differential pressure-flow rate becomes large, and the accuracy and response of pressure measurement deteriorate in the range where the pressure sensor or differential pressure measurement is 10 mmH ₂ O or less, and
The cost of the device is difficult, and for this reason, there is a need for a pressure sensor having a pressure difference of about 200 mmH ₂ O with appropriate accuracy and responsiveness that does not cause excessive cost.

In addition, it was necessary to improve the responsiveness and downsize the entire flow meter device including the pressure sensor in terms of utilization.

In order to meet these needs, one issue is to reduce the equivalent diameter of each laminar flow passage tube in order to increase the maximum average flow velocity in the matrix and keep the Re number at about 150 or less. Met. Furthermore, it is necessary not to reduce the effective flow channel area ratio of the matrix.

It was also an issue to arrange the differential pressure sensor in the flow path using a small one and to be able to directly measure the pressure in the flow path without drawing out a pressure conduit or the like to the outside. .

The present invention has been made in view of the above circumstances, the differential pressure is about 200 ~ 300 mmH ₂ O accuracy of the pressure sensor, good responsiveness, and the device can be downsized, matrix It is possible to reduce the equivalent diameter of the individual laminar flow passage pipes in the above, without reducing the effective flow passage cross-sectional area ratio, and in addition, directly in the flow passage without drawing out a pressure conduit etc. to the outside. It is an object of the present invention to provide an ultrafine channel laminar flow meter capable of measuring pressure.

[Means for Solving the Problem] To this end, the ultrafine channel laminar flow meter of the present invention is a thin plate having a thickness of 25 μm or less and a width of 12 mm or less and a corrugated plate with a pitch of 0.45 mm or less. It is characterized by stacking flat thin plates to form a spiral multi-layer structure, and arranging a matrix configured so that the hydraulic equivalent diameter of each channel cross section is 0.2 mm or less inside the outer tube that constitutes the channel. I am trying.

[Operation] Place the laminar flow element inside the outer tube,
The fluid to be measured flowing in the outer tube is passed through the laminar flow element. The volumetric flow rate is determined as a proportional function of the pressure difference across the laminar flow element.

[Embodiment] Hereinafter, the details of the present invention will be described with reference to the drawings illustrating an embodiment.

The embodiment shown in FIG. 1 is a part 1'of a cross section of a laminar flow element 1 of the present invention, which is a corrugated thin plate 11 having a thickness t ₁ and a width l ₁ and a flat thin plate 12 which are formed in a wave shape. (Thickness t ₂ , width l ₂
mm) and are wound in a spiral shape.

For example, stainless steel is used as the material forming the corrugated thin plate 11, and the thickness t ₁ = 25 μm or less, particularly 10 to 20 μm, and the width
l ₁ = 15 mm or less, particularly 5 to 12 mm is preferable.

As the material for forming the flat thin plate 12, for example, stainless steel is used, and the thickness t ₂ = 25 μm or less, particularly 10 to 20 μm.
m, width l ₂ = 15 mm or less, particularly 5 to 12 mm.

The actual flow path length can be selected depending on the pressure level, but when the differential pressure is 300 mmH ₂ O or less in the normal operating range, it is about 12
mm or less is suitable, and the thickness of the matrix, that is, the plate width of the constituent element is 12 mm or less.

Further, a member having rigidity in the flow direction (axial direction) is provided in the core so as to prevent displacement and movement in the flow direction of each layer of the matrix formed of multiple layers, so that the matrix can be held.

It is desirable that the corrugated sheet 11 is formed by roll forming in which a pair of rolls having fine tooth shapes is passed. The tooth pitch is preferably 0.5 mm or less, particularly 0.45 mm (about 0.15 module) or less. The hydraulic equivalent diameter dm of each flow path cross section of the laminar flow element 1 is dm = 4 (A / S) A: Flow path cross sectional area of the laminar flow element 1 S: Flow path cross section of the laminar flow element 1 Is the perimeter of It is preferable that dm ≦ 0.25 mm, especially dm ≦ 0.2 mm. It is also desired to keep the effective flow channel area ratio at 50% or more.

The laminar flow element thus constructed constitutes the laminar flow meter 20 as follows. That is, the second
The figure shows the measurement principle of the laminar flow meter 20 using the laminar flow element of the present invention.
The laminar flow element 1 which is formed by spirally winding the center rod 2 is held. The fluid 13 to be measured flows in the outer tube 4 and flows into the laminar flow element 1
Static pressure P ₁ · P ₂ before and after the flow element 1
The differential pressure ΔP is measured by the manometer 3 or another differential pressure gauge.

In FIG. 4, as another embodiment of the present invention, a pressure sensor 5 is built-in, and an in-line type is constructed so that the differential pressure can be directly measured in the pipe, and the axis of the laminar flow element 1 is further constructed. The structure which prevented the deviation of the direction is shown. That is, inside the outer tube 4 of the flow path, the laminar flow element 1 is formed around the core 6 having a cylindrical side surface as a center, and a laminar flow element 1 is formed in a thin plate shape to prevent axial movement of the element. A plurality of holding members 7 and 8 are radially provided to the core 6, respectively, and fixed to the outer tube 4 via the outer peripheral portion of the flow element 1. Inside the core 6 through a seal packing 10 a pressure sensor 5, is fixed to the core 6 by screws or the like, upstream static pressure P ₁ is a pressure sensor 5 via a hole 9 for introducing the upstream static pressure P ₁ Try to join one. The downstream static pressure P ₂ passes through a plurality of holes 62 provided in the core cover 61 and the pressure sensor 5
To the other pressure end 53 of.

The electric output of the pressure sensor 5 is from the substrate 55 to the lead wire 54.
It is taken out to the outside through a plurality of (a plurality), a compensation circuit 56 including a temperature sensor, a lead wire 57 through a hole provided in a core cover 61, and an airtight terminal 41 provided in an outer tube. The electric output including the differential pressure and temperature compensation is led to the indicator 32 having a calculation circuit via the lead wire 58 outside the outer tube 4, and displays the flow rate calculated by the differential pressure and temperature.

[Experimental Example] The flow rate was measured using the laminar flow meter 20 shown in FIGS. 1 and 2.

Fluid to be measured: Air Thickness of corrugated sheet 11 t ₁ ＝ 20μm Width l ₁ ＝ 10mm Thickness of flat sheet 12 t ₂ ＝ 20μm Width l ₂ ＝ 10mm Pitch of tooth profile P ₁ ≒ 0.35mm Pitch in radial direction Pd ≒ (including thin plate thickness) 0.15
mm dm = 0.16 mm At this time, the relationship between the differential pressure and the flow rate is as shown in the example of Fig. 3, and the linearity is greatly improved compared to the case of the conventional laminar flow element.

[Effects of the Invention] As is apparent from the above-described embodiments, the laminar flow meter having the ultrafine flow passage according to the present invention has an equivalent diameter dm of the flow passage of about 12 mm or less in the flow passage length l (matrix plate width). 0.2 mm
The flow rate and the pressure difference can be
As illustrated in the figure, it was possible to improve the linearity over a wider range of flow rate and differential pressure than the characteristics of the conventional matrix. Then, it is possible to increase the flow velocity at the same Re number, and it is possible to reduce the size for the same flow rate capacity. In addition, a pressure sensor is built in, and it is not necessary to draw out the fluid introduction pipe for measuring the differential pressure to the outside, enabling in-line measurement.

Further, since the flow path length can be shortened and the pressure sensor can directly measure the differential pressure before and after the matrix, the dynamic characteristics can be improved in the measurement of the changing flow rate including the pulsating flow.

[Brief description of drawings]

FIG. 1 is a sectional partial explanatory view of a laminar flow element according to an embodiment of the present invention, and FIG. 2 is a vertical sectional explanatory view of an ultrafine channel laminar flow meter according to an embodiment of the present invention. FIG. 4 is a graph showing the relationship between flow rate and pressure difference, FIG. 4 is an ultrafine flow path laminar flow meter according to another embodiment of the present invention, and FIG. 5 is a sectional view taken along line VV in FIG. is there. 1 ... Laminar flow element, 2 ... Center rod, 3
…… Manometer, 4 …… Outer tube, 5 …… Pressure sensor, 6
…… Core, 7,8 …… Holding member, 9 …… Hole, 10 …… Seal packing, 11 …… Corrugated sheet, 12 …… Flat sheet, 13 …… Fluid, 20 …… Laminar flow meter , 53 …… pressure end, 55 …… substrate,
54 …… lead wire, 56 …… compensation circuit, 57,58 …… lead wire, t ₁ , t ₂ …… thickness, l ₁ , l ₂ …… width, P ₁ …… upstream static pressure,
P ₂ ...... Downstream static pressure

Claims (3)

[Scope of utility model registration request] 1. A hydrodynamic equivalent diameter of each flow path cross section is formed by stacking a corrugated plate having a pitch of 0.45 mm or less and a flat thin plate formed by molding a thin plate having a thickness of 25 μm or less and a width of 12 mm or less, in a spiral shape. 0.
Ultrafine flow channel laminar flow meter with a matrix configured to be 2 mm or less arranged in the outer tube that constitutes the flow channel 2. In the laminar flow meter, a core having a built-in pressure sensor is arranged in a central portion thereof, and a pressure difference of a fluid generated before and after a matrix can be detected in a flow passage at a high response speed. Item 1. Ultrafine flow channel laminar flow meter 3. In the laminar flow meter, a thin plate member having a small flow resistance and an axial rigidity is arranged around an outer periphery of a central core so as to radially hold a matrix,
An ultrafine flow channel laminar flow meter according to claim 2, wherein the matrix is arranged so as to prevent a positional change in the flow direction.