JP2020139835A - Laminar flow element and laminar flow meter - Google Patents

Abstract

To further accurately measure temperature of fluid passing through with good responsiveness, and to reduce the occurrence of a flow rate measurement error.SOLUTION: A thin film temperature sensor 5 is disposed at a position overlapping a groove (flow path) 2B of a laminar flow plate 1B on a bottom surface 3A of a laminar flow plate 1A. The thin film temperature sensor 5 is covered with an insulating protective film 6. A portion of the insulating protective film 6 facing the groove 2B of the laminar flow plate 1B has a uniform thickness and a flat surface.SELECTED DRAWING: Figure 2

Description

The present invention relates to a laminar flow element and a laminar flow meter using the laminar flow element.

Conventionally, a laminar flow meter has been used as one of the flow meters for measuring the flow rate of a fluid flowing through a flow path. This laminar flow meter is equipped with a laminar flow element that makes the flowing fluid flow laminar, that is, the flow line of the fluid is always parallel to the pipe axis, and the upstream side and the downstream side of this laminar flow element. The flow rate of the fluid flowing through the flow path is measured from the difference in the pressure of the fluid on the side (see, for example, Patent Document 1).

The laminar flow meter is a flow meter that utilizes the phenomenon that when a fluid flows in a laminar flow state in a flow path, the pressure drop due to the movement of the fluid is proportional to the volumetric flow rate according to Hagen-Poiseuille's law. In this laminar flow meter, the relationship between the mass flow rate and the differential pressure is expressed by the following equation.
Qm = ΔP ・ K ・ (ρ / (μ ・ L)) ・ ・ ・ ・ (1)
However, Qm: mass flow rate, ΔP: difference in fluid pressure between the upstream side and downstream side of the laminar flow element (differential pressure), K: proportionality constant, ρ: fluid density, μ: fluid viscosity coefficient (fluid viscosity) ), L: Flow path length.

In this equation (1), the density ρ of the fluid and the viscosity μ of the fluid depend on the temperature. Therefore, it is necessary to measure the temperature of the laminar flow element and correct the fluid density ρ and the fluid viscosity μ. In order to perform such correction with high accuracy, it is necessary to measure the temperature of the fluid passing through the laminar flow element as accurately as possible.

Japanese Unexamined Patent Publication No. 2017-191090 Japanese Unexamined Patent Publication No. 2004-77327

However, in the conventional laminar flow meter, the temperature of the fluid flowing into the laminar flow element is detected, or the temperature of the body of the laminar flow element is detected (see, for example, Patent Document 2). .), It is hard to say that the temperature of the fluid passing through the laminar flow element is measured correctly.

In particular, at the temperature of the body of the laminar flow element, the layer is affected by the delay in thermal response due to the heat capacity of the body of the laminar flow element and the influence of heat transfer from other parts attached to the body of the laminar flow element. An error occurs in the measured temperature of the fluid passing through the flow element, and the generated flow rate measurement error becomes large.

The present invention has been made to solve such a problem, and an object of the present invention is to measure the temperature of a passing fluid more accurately and responsively to reduce the occurrence of flow rate measurement error. It is an object of the present invention to provide a laminar flow element and a laminar flow meter capable of the above.

In order to achieve such an object, the laminar flow element according to the present invention passes through a plurality of laminar flow plates, which are laminated to form a laminar flow with the flowing fluid flowing as a laminar flow, and the laminar flow plate. The plurality of laminar flow plates (1) are provided with a first laminar flow plate (1A) having a groove (2A) formed in the first surface (4A) and provided with a temperature sensor for measuring the temperature of the fluid. , A first surface that is overlapped with a second surface (3A) opposite to the first surface of the first laminar flow plate and faces the second surface of the first laminar flow plate. The temperature sensor includes the second laminar flow plate (1B) in which the groove (2B) is formed in (4B), and the temperature sensor is the first of the second surface (3A) of the first laminar flow plate. It is a thin film temperature sensor (5) provided at a position overlapping the groove (2B) formed on the first surface (4B) of the laminar flow plate of 2.

In the present invention, a thin film temperature sensor is provided at a position overlapping the groove of the second laminar flow plate on the surface opposite to the surface on which the groove of the first laminar flow plate is formed. This makes it possible to measure the temperature of the passing fluid more accurately and responsively without affecting the flow of the passing fluid in the present invention.

Further, the laminar flow meter (200) according to the present invention acquires the difference in pressure between the laminar flow element (100) according to the present invention and the upstream side and the downstream side of the laminar flow element as a differential pressure. The layer is based on the configured differential pressure acquisition unit (15), the differential pressure acquired by the differential pressure acquisition unit, and the temperature detected by the temperature sensor (5) provided in the laminar flow element. It is characterized by including a flow rate calculation unit (18) configured to obtain the flow rate of the fluid flowing through the flow element.

In the above description, as an example, the components on the drawing corresponding to the components of the invention are indicated by reference numerals in parentheses.

As described above, according to the present invention, the temperature sensor of the thin film is placed at a position overlapping the groove of the second laminar flow plate on the surface opposite to the surface on which the groove of the first laminar flow plate is formed. Since it is provided, it is possible to measure the temperature of the passing fluid more accurately and responsively without affecting the flow of the passing fluid, and it is possible to reduce the occurrence of flow rate measurement error. become.

FIG. 1 is a diagram showing a main part of a laminar flow device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a laminated state of laminar flow plates located at the center of the laminar flow element. FIG. 3 is a plan view showing the installation state of the thin film temperature sensor and the lead portion on the bottom surface of the laminar flow plate. FIG. 4 is a plan view showing a state in which an insulating protective film is applied on the thin film temperature sensor and the lead portion. FIG. 5 is a diagram showing an example in which three thin film temperature sensors are provided along the flow direction of the fluid. FIG. 6 is a block diagram showing a main part of the wireless temperature sensor. FIG. 7 is a diagram showing a configuration of a main part of a laminar flow type flow meter using the laminar flow element according to the present invention. FIG. 8 is a diagram showing an example in which a differential pressure sensor is provided in place of the pressure sensor on the upstream side and the pressure sensor on the downstream side.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a main part of a laminar flow element 100 according to an embodiment of the present invention. In this figure, for explanation, only the laminar flow element 100 is shown as a cross-sectional view along the flow direction of the fluid.

The laminar flow element 100 includes a plurality of metal laminar flow plates 1 in which grooves 2 are formed as flow paths for the flow of passing fluid as a laminar flow, and these laminar flow plates 1 are laminated so as to sandwich the grooves 2. Has been done. In FIG. 1, reference numeral 10 denotes a main flow path, and a laminar flow element 100 is provided in the middle of the main flow path 10.

FIG. 2 shows a laminated state of the laminar flow plate 1A and the laminar flow plate 1B located at the center of the laminar flow element 100. FIG. 2 is a cross-sectional view seen from the flow direction of the fluid passing through the laminar flow element 100. A groove 2A is formed in the laminar flow plate 1A as a flow path for the flow of the passing fluid as a laminar flow, and a groove 2B is formed in the laminar flow plate 1B as a flow path for the flow of the passing fluid as a laminar flow. Is formed. The laminar flow plate 1A corresponds to the first laminar flow plate in the present invention, and the laminar flow plate 1B corresponds to the second laminar flow plate.

The laminar flow plate 1A has a surface opposite to the surface 4 (4A) on which the groove 2A is formed as a bottom surface 3 (3A), and is formed on the surface 4 (4B) on which the groove 2B of the laminar flow plate 1B is formed. It is superposed. Hereinafter, the surface 4 on which the groove 2 is formed is referred to as the “upper surface” of the laminar flow plate 1. The upper surface 4A of the laminar flow plate 1A corresponds to the first surface of the first laminar flow plate in the present invention, and the bottom surface 3A of the laminar flow plate 1A corresponds to the second surface of the first laminar flow plate. The upper surface 4B of the laminar flow plate 1B corresponds to the first surface of the second laminar flow plate.

On the bottom surface 3A of the laminar flow plate 1A, a temperature sensor (hereinafter, referred to as "thin film temperature sensor") 5 made of a thin film resistance such as platinum is provided at a position overlapping the groove 2B formed in the laminar flow plate 1B. Has been done. In the present embodiment, the thin film temperature sensor 5 is provided so as to face the center position of the groove 2B, that is, to be located at the center of the groove 2B in the longitudinal direction and the width direction. The thin film temperature sensor 5 is covered with an insulating protective film (hereinafter, referred to as “insulating protective film”) 6 made of polyimide or the like. The insulating protective film 6 is formed on the entire surface of the bottom surface 3A of the laminar flow plate 1A.

The procedure for installing the thin film temperature sensor 5 on the bottom surface 3A of the laminar flow plate 1A will be described. First, as shown in FIG. 3, a thin film temperature sensor 5 and a lead portion 7 connected to the thin film temperature sensor 5 are installed on the bottom surface 3A of the laminar flow plate 1A. After that, as shown in FIG. 4, the insulating protective film 6 is thickly applied to the entire surface of the bottom surface 3A of the laminar flow plate 1A. At this time, the insulating protective film 6 on the thin film temperature sensor 5 and the lead portion 7 is thicker than the other portions, but the thickened portion is removed by cutting to make the thickness of the insulating protective film 6 uniform. Further, a signal connected to the lead portion 7 by wire bonding or filling with a metal material after ensuring insulation from the laminar flow plate 1A in the through hole 8 formed at a position away from the groove 2A of the laminar flow plate 1A. Make the take-out wiring 9.

In the laminar flow element 100, the bottom surface 3 of each laminar flow plate 1 is thin, has a small heat capacity, and easily exchanges heat. Further, the thickness of the portion of the laminar flow plate 1B of the insulating protective film 6 facing the groove 2B is made uniform and has a flat surface. As a result, the temperature of the fluid passing through the groove 2B can be measured more accurately and responsively without affecting the flow of the fluid passing through the groove 2B.

In the laminar flow element 100 shown in FIG. 1, the thin film temperature sensor 5 is provided so as to face the center position of the groove 2B of the laminar flow plate 1B, but a plurality of thin film temperature sensors 5 are provided along the groove 2B. You may do so.

When the fluid passes through the groove 2B, a pressure drop occurs, and the temperature changes with the pressure drop. Therefore, a temperature distribution can be formed in the flow direction of the fluid. When this temperature distribution becomes a problem, a plurality of thin film temperature sensors 5 are provided along the groove 2B, and for example, the average value of the temperatures detected by the plurality of thin film temperature sensors 5 is used as the temperature measurement value.

FIG. 5 shows an example in which three thin film temperature sensors 5 are provided along the groove 2B. In this laminar flow element 100', a thin film temperature sensor 5-1 is provided on the upstream side, a thin film temperature sensor 5-3 is provided on the downstream side, and the thin film temperature sensor 5 is provided between the thin film temperature sensors 5-1 and 5-3. -2 is provided.

Further, in the laminar flow element 100 shown in FIG. 1, the thin film temperature sensor 5 is provided on the bottom surface 3A of the laminar flow plate 1A located at the center of the laminar flow element 100, but the temperature of the fluid flowing through the groove 2 is measured. As long as it can be detected, the thin film temperature sensor 5 may be provided on the bottom surface 3 of another laminar flow plate 1.

Further, the thin film temperature sensor 5 may be a thin film IC, and the thin film IC may be provided with wireless power supply and transmission / reception functions. That is, the temperature sensor of the thin film provided on the bottom surface 3A of the laminar flow plate 1A is a wireless temperature sensor 5'(see FIG. 6) that operates by receiving a wireless power supply from the outside, and the temperature detected by the temperature detection unit 51 is measured. The wireless communication circuit unit 52 may transmit to the outside through the antenna 53, or a command from the outside may be received by the wireless communication circuit unit 52 through the antenna 53. In the wireless temperature sensor 5', the electric power from the outside supplied through the antenna 53 is received by the power receiving unit 54 and supplied to the wireless communication circuit unit 52 and the temperature detecting unit 51.

[Laminar flow meter]
FIG. 7 shows the configuration of a main part of the laminar flow meter 200 using the laminar flow element according to the present invention. In the laminar flow type flow meter 200, a pressure sensor 11 for detecting the pressure of the fluid on the upstream side of the laminar flow element 100 as the upstream pressure P1 is provided on the upstream side of the laminar flow element 100. A pressure sensor 12 is provided on the downstream side of the laminar flow element 100 to detect the pressure of the fluid on the downstream side as the downstream pressure P2.

Further, in the laminar flow type flow meter 200, the laminar flow element is composed of the upstream pressure P1 of the laminar flow element 100 detected by the pressure sensor 11 and the downstream pressure P2 of the laminar flow element 100 detected by the pressure sensor 12. A flow rate calculation unit 14 for calculating the mass flow rate Qm of the fluid flowing through 100 is provided.

The flow rate calculation unit 14 is realized by hardware including a processor and a storage device and a program that realizes various functions in cooperation with these hardware, and is realized by a differential pressure measuring unit 15, a density correction unit 16, and a viscosity correction unit. A 17 and a mass flow rate calculation unit 18 are provided.

In the flow rate calculation unit 14, the differential pressure measuring unit 15 receives the upstream pressure P1 of the laminar flow element 100 from the pressure sensor 11 and the downstream pressure P2 of the laminar flow element 100 from the pressure sensor 12 as inputs, and the upstream side thereof. The difference between the pressure P1 and the downstream pressure P2 is obtained as the differential pressure ΔP.

The density correction unit 16 receives the temperature T of the fluid passing through the laminar flow element 100 detected by the thin film temperature sensor 5 as an input, and the fluid flowing through the laminar flow element 100 based on the temperature T of the fluid passing through the laminar flow element 100. Correct the density ρ of. The viscosity correction unit 17 receives the temperature T of the fluid passing through the laminar flow element 100 detected by the thin film temperature sensor 5 as an input, and the fluid flowing through the laminar flow element 100 based on the temperature T of the fluid passing through the laminar flow element 100. Correct the viscosity μ of.

The mass flow rate calculation unit 18 inputs the differential pressure ΔP from the differential pressure measuring unit 15, the corrected density ρ from the density correction unit 16, and the corrected viscosity μ from the viscosity correction unit 17, and the above-mentioned (1). ), The mass flow rate Qm of the fluid flowing through the laminar flow element 100 is calculated.

As a result, the temperature of the fluid passing through the laminar flow element 100 can be measured more accurately and responsively, the density of the fluid and the viscosity of the fluid can be accurately corrected, and the occurrence of flow rate measurement error can be reduced. Will be.

In this laminar flow meter 200, the difference between the upstream pressure P1 detected by the pressure sensor 11 and the downstream pressure P2 detected by the pressure sensor 12 is obtained by the differential pressure measuring unit 15 as the differential pressure ΔP. However, as shown in FIG. 8, a differential pressure sensor 19 for detecting the difference in pressure between the fluids on the upstream side and the downstream side of the laminar flow element 100 as a differential pressure ΔP is provided, and the differential pressure ΔP detected by the differential pressure sensor 19 is provided. May be sent to the mass flow rate calculation unit 18. In FIG. 8, in order to distinguish from the laminar flow meter 200 shown in FIG. 7, the laminar flow meter is shown as 200'and the flow rate calculation unit is shown as 14'.

[Extension of Embodiment]
Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the structure and details of the present invention within the scope of the technical idea of the present invention.

1 ... Laminar flow plate, 2 ... Groove, 3 ... Bottom surface, 4 ... Top surface, 5 ... Thin film temperature sensor, 6 ... Insulation protective film, 7 ... Lead part, 8 ... Through hole, 9 ... Signal extraction wiring, 11, 12 ... pressure sensor, 14, 14'... flow rate calculation unit, 15 ... differential pressure measurement unit, 16 ... density correction unit, 17 ... viscosity correction unit, 18 ... mass flow rate calculation unit, 19 ... differential pressure sensor, 5'... wireless temperature Sensor, 51 ... Temperature detection unit, 52 ... Wireless communication circuit unit, 53 ... Antenna, 54 ... Power receiving unit, 100, 100'... Laminar flow element, 200, 200' ... Laminar flow type flow meter.

Claims (9)

It is provided with a plurality of laminar flow plates that are laminated to form a flow path that uses the flow of the passing fluid as a laminar flow, and a temperature sensor that measures the temperature of the fluid that passes through the flow path.
The plurality of laminar flow plates
A first laminar flow plate with a groove formed on the first surface,
A groove is formed on the first surface of the first laminar flow plate which is overlapped with the second surface opposite to the first surface of the first laminar flow plate and faces the second surface of the first laminar flow plate. Including the second laminar flow plate
The temperature sensor
A thin film temperature sensor provided at a position overlapping the groove formed on the first surface of the second laminar flow plate on the second surface of the first laminar flow plate. A characteristic laminar flow element. In the laminar flow device according to claim 1,
The temperature sensor
A laminar flow element characterized in that the second surface of the first laminar flow plate is covered with an insulating protective film. In the laminar flow device according to claim 2.
The protective film is
A laminar flow element characterized in that the thickness of a portion of the second laminar flow plate facing the groove formed on the first surface is uniform. In the laminar flow device according to any one of claims 1 to 3.
The first laminar flow plate is
A through hole is provided at a position away from the groove formed on the first surface of the first laminar flow plate.
A laminar flow element characterized in that a signal from the temperature sensor is taken out through the through hole. In the laminar flow device according to any one of claims 1 to 3.
The temperature sensor
A laminar flow device including a wireless communication circuit unit configured to transmit the detected temperature wirelessly. In the laminar flow device according to any one of claims 1 to 5.
The temperature sensor
A laminar flow element characterized in that it is arranged in the middle in the longitudinal direction of the groove formed on the first surface of the second laminar flow plate. In the laminar flow device according to any one of claims 1 to 5.
The temperature sensor
A laminar flow element characterized in that a plurality of laminar flow elements are provided along the groove formed on the first surface of the second laminar flow plate. The laminar flow element according to any one of claims 1 to 7, wherein the flowing fluid flows as a laminar flow.
A differential pressure acquisition unit configured to acquire the difference in pressure between the upstream side and the downstream side of the laminar flow element as a differential pressure,
A flow rate configured to obtain the flow rate of the fluid flowing through the laminar flow element based on the differential pressure acquired by the differential pressure acquisition unit and the temperature detected by the temperature sensor provided in the laminar flow element. A laminar flow meter characterized by having a calculation unit. In the laminar flow meter according to claim 8,
A density correction unit configured to correct the density of the fluid based on the temperature detected by the temperature sensor provided in the laminar flow element.
Further provided with a viscosity correction unit configured to correct the viscosity of the fluid based on the temperature detected by the temperature sensor provided in the laminar flow element.
The flow rate calculation unit
It is configured to obtain the mass flow rate of the fluid flowing through the laminar flow element from the differential pressure acquired by the differential pressure acquisition unit, the density corrected by the density correction unit, and the viscosity corrected by the viscosity correction unit. A laminar flow meter characterized by its presence.

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