JPH04295768A - Fluid detector - Google Patents

Abstract

PURPOSE:To improve the fluid detection sensitivity and responsibeness of a detection element by the use of small power consumption, eliminate the influence of fluid turbulence received by the detection element and contrive the improvement of a characteristic in the direction of fluid flow. CONSTITUTION:A specified space is provided on part of a board 21, a diaphragm part 23 is formed and two fluid detection elements 11, 12 forming a fluid detection part 2 are provided by integrating a heat generation part and a resistance bulb part in the diaphragm part 23. The directions of respective maximum detection sensitivities are crossed to provide the fluid detection elements 11, 12 on the curvature faces of a pair of fluid guide plates 5, 6 whose opposed faces are curvature faces. The fluid detection element is provided on the fluid guide plate, the other fluid detection element on the other fluid guide plate respectively or the two fluid detection elements 11, 12 are provided on at least the fluid guide plate in a condition in which they are paired.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a fluid detection device that simultaneously detects the velocity and direction of fluid flow.

Conventionally, as this type of device, FIGS. 12 and 13
As shown in FIG. 2, a pair of fluid guide plates 5 and 6 are configured using a spacer 7 so as to be parallel to each other, and a mounting base 33 to which a fluid detection element 11 is bonded is installed between them.
and hold them with a support tube 4 (Delft University of Technology, Netherlands, B.W. van Oudhuisden, J.H. Air flow meter” sensor and actuator, A21-A23
1990, pp. 420-424, B. W. Va
n Oudheusdenand J. H. Hui
jsing, Delft University
of Technology, Netherla
nds:”An Electronic Wind
Meter Based on a Si
liconFlow Sensor”,Sensor
s and Actuators. A21-A23
(1990) 420-424). The fluid detection element 11 is
A diffused resistor 45 for a heater, a temperature measuring transistor 46 for measuring the average temperature of this element, and thermopiles 44a, 44b, 44c and 44d for detecting a temperature difference due to flow are mounted on a substrate 21 (here, a silicon substrate) of about 6 mm square. Figure 14
It is arranged as shown in . This fluid detection element 11 is bonded to a ceramic mounting base 33, and this mounting base is installed between the fluid guide plates 5 and 6 so that the surface on which the element 11 is not provided, that is, the back surface thereof, is exposed to the fluid.

The operation of this fluid detection device is as follows: When power is applied to the heater diffusion resistor 45 using the temperature measuring transistor 46 so that the average temperature of the element becomes a certain high temperature, the heat generated there is transferred to the mounting base 33 through the base 21. Covers surfaces exposed to fluid. Here, when the fluid is flowing, the upstream side of the flow of the mounting base 33 is cooled and the downstream side is slightly warmed. This phenomenon occurs in the temperature measuring thermopile through the mounting base 33 and the base 21, and an electromotive force is generated between the thermopile on the upstream side of the flow and the thermopile on the downstream side of the flow. In addition, in FIG. 14, the direction in which the temperature measuring thermopile 44a, the heater resistor 25, and the temperature measuring thermopile 44b are arranged in the fluid detection element is referred to as direction A, and the flow direction of the fluid is referred to as direction B. Temperature measuring thermopile 44c,
Assuming that the direction in which the heater resistor 45 and the temperature measuring thermopile 44d are arranged is direction C, the angle between direction A and direction B is θ, and the size of the mainstream of the fluid is V,
From the difference x in the electromotive force between temperature measuring thermopiles 44a and 24b of this detector, f (
y)=V·sinθ is detected.

[0004] This conventional device has an elevation angle φ in the flow direction B.
When the angle is about 15 degrees or more, turbulence 40 occurs from the ends of the fluid guide plates 5 and 6, which reaches the detection section and affects the sensor output. Since the magnitude of this turbulence 40 is affected by the velocity of the mainstream fluid, temperature, etc., there is a drawback that the reproducibility of detection is poor. For this reason, it has been difficult to stably detect the velocity and direction of the fluid. Also,
Due to the operating mechanism of the element, although it can detect relatively fast flowing fluid, it is not sensitive to minute movements. That is, the sensitivity of fluid detection is low and the responsiveness is low. Moreover, it has the disadvantage of high power consumption for operation.

[0005]

Problems to be solved by the present invention In addition to improving the sensitivity and responsiveness of the detection element and reducing power consumption, the problems to be solved by the present invention are to eliminate the influence of fluid turbulence on the detection element, and to improve the sensitivity and response of the detection element. This is an improvement in the reproducibility of the characteristics with respect to the direction of flow.

[0006]

[Means for Solving the Problems] The fluid detection device of the present invention includes a diaphragm portion formed by providing a predetermined space in a part of a substrate, and a heat generating portion and a temperature measuring resistor portion integrated in this diaphragm portion. Two fluid detection elements forming a fluid detection section are installed on the curved surfaces of a pair of fluid guide plates whose opposing surfaces are curved so that the directions of their maximum detection sensitivities intersect with each other. The detection elements may be arranged such that one fluid detection element is arranged on one fluid guide plate and the other fluid detection element is arranged on the other fluid guide plate, or two fluid detection elements are arranged in a pair and at least one of them is arranged. This is installed on the fluid guide plate.

[0007]

[Operation] The fluid detection device according to the present invention guides the fluid to the fluid detection element without disturbing the flow by a guide plate having a curved surface, thereby eliminating the influence of turbulence and improving the reproducibility of the characteristics in the flow direction of the fluid. The fluid detection section accurately detects the flow velocity and direction of the fluid with high sensitivity and quick response, and operates with low power consumption.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 2, and 3 show an embodiment of a fluid detection device 1 according to the present invention, and this fluid detection device is composed of a detection section 2 and a control section 3.

The configuration of the fluid detection section 2 will now be explained. In FIG. 1, FIG. 2, or FIG. 3, one end of the support tube 4 is fixed to the control unit 3, and a pair of fluid guide plates 5, 6 are provided at the other end, that is, the free end. The first fluid guide plate 5 is fixed to the support tube 4, and in front of the first fluid guide plate there are a plurality of spacers 7, 7 whose thickness and number are determined so as not to disturb the flow. The second fluid guide plate 6 is fixed. As a result, the pair of fluid guide plates are fixed in parallel with each other with a predetermined distance therebetween. The opposing surfaces of both fluid guide plates are formed with chevron-shaped curved surfaces 8 and 9 that approach each other as they move from their respective peripheries toward the center. This constitutes the fluid detection section 2. Note that the curved surfaces 8 and 9 of the fluid guide plates 5 and 6 can be formed into a spherical surface, an aspherical curved surface, or a conical shape as required. Further, the curvature of this curved surface does not need to be the same, and can be adjusted as appropriate. Note that it is desirable that the curved surface be made as smooth as possible. Then, one of the pair of fluid guide plates 5 or 6, for example, the first fluid guide plate 5
A pair of fluid detection elements 11 and 12 are installed on the curved surface 8 facing the other fluid guide plate 6 .

Next, the configuration of fluid detection elements 11 and 12 used in this fluid detection device 1 will be explained. Note that the fluid detection elements 11 and 12 have the same configuration. That is, in FIG. 4, the substrate 21 is made of, for example, single crystal silicon and is about 1.7 mm square and about 0.7 mm thick, and a cavity 22 is formed in the center of the substrate 21. A diaphragm part 23 is formed above the cavity 22, which is separated from the substrate 21 by a space and is thermally insulated from the substrate 21 as a result. On the surface of this diaphragm portion 23 is a thin film heater element 24 and a thin film temperature sensing resistance element 2 sandwiching it.
5 and 26 are arranged. Further, on the surface of the substrate 21 where the void portion 22 is not formed, a thin film temperature measuring resistance element 27 and a bonding pad 28 for taking out electrical wiring are formed.

[0011] The manufacturing method of this element is, for example, by using an ordinary thin film forming technique on the substrate 21 to form an insulating film layer such as silicon oxide or silicon nitride, and a resistor film layer such as platinum, nickel, or nickel-iron alloy. A resistor film layer is formed into a predetermined resistor pattern by photolithography, an insulating film layer such as silicon oxide or silicon nitride is formed as a protective film, and then a resistor film layer for etching is formed on the insulating film layer. Open slit 29. When this is subjected to anisotropic etching using, for example, a potassium hydroxide solution, a void 22 is formed through the slit 29, and the heater element 24 and the temperature sensing resistor element 25 are separated from the substrate 21 by the void 22.
, 26 are formed into a diaphragm portion 23 that is thermally insulated. This constitutes the fluid detection element 11 or 12.

Further, FIG. 5 shows a V-V cross section of the fluid detection element 11 or 12 shown in FIG. Note that in FIG. 5, reference numeral 30 indicates the heater element 24 formed on the substrate 21.
This is a protective film for protecting devices such as. The diaphragm section 23, including the protective film 30, is formed to have a thickness of about 1 micron, for example, and loss due to heat conduction from the end is extremely small, realizing thermal insulation of the fluid detection section.

Further, FIG. 6 shows the temperature distribution of the heater element and the temperature-measuring resistance element in FIG. Here, when the heater element 24 is controlled to a certain higher temperature th (for example, 60° C.: ambient temperature reference) than the ambient temperature using the temperature-measuring resistance element 27 at the ambient temperature, the temperature-measuring resistance elements 25, 26 The temperatures t1 and t2 become almost equal as shown in FIG. At this time, for example, the temperature measuring resistance element 25 and the heater element 2 shown in FIG.
4 and the direction in which the temperature-measuring resistance element 26 is disposed, that is, in the direction of arrow A, the temperature-measuring resistance element 25 on the upstream side is cooled and its temperature decreases by Δt1. On the other hand, the temperature of the temperature-measuring resistance element 26 on the downstream side increases by Δt2. As a result, a temperature difference occurs between the temperature-measuring resistance element 25 on the upstream side and the temperature-measuring resistance element 26 on the downstream side. Thereby, by incorporating the temperature measuring resistance elements 25 and 26 into a Wheatstone bridge circuit and converting the temperature difference into voltage, a voltage corresponding to the flow rate of the fluid can be obtained, thereby making it possible to detect the flow rate of the fluid. Assuming that the angle between direction A and direction B is θ and the size of the main flow of fluid is V, this fluid detection element detects V·cos θ. Therefore, the direction in which the temperature-measuring resistance element 25, heater element 24, and temperature-measuring resistance element 26 are arranged, that is, the direction of arrow A, is the direction in which the detection sensitivity of the fluid detection elements 11 and 12 is maximized, and in this specification, , this is the direction of maximum detection sensitivity of the fluid detection element. In addition,
The fluid detection element 11 or 12 is characterized by having a very thin, thermally insulated diaphragm-shaped detection part, so that it has high sensitivity, fast response speed, and operates with very low power consumption.

Fluid detection element 1 constructed in this way
FIG.
It is installed near the top of the chevron-shaped curved surface 8 or 9 of the fluid guide plate 5 or 6 as shown in FIG. At this time, care must be taken to avoid creating a step between the end of the mounting base 33 and the curved surface 8. In addition, the two fluid detection elements 11 and 12 are as shown in FIG.
The temperature-measuring resistance element 25, the heater element 24, and the temperature-measuring resistance element 26 are arranged so that their arrangement directions, that is, the directions of maximum detection sensitivity, intersect with each other. In this figure, they intersect at an angle of approximately 90 degrees.

Now, the direction of the maximum detection sensitivity of the fluid detection element 11 is defined as direction A, the direction in which the detection section of the fluid detection element 12 is arranged is defined as direction C, the angle formed by direction A and direction C is defined as ψ,
When the direction of fluid flow is direction B, direction A and direction B
Let θ be the angle between the
From the output x of the Wheatstone bridge including the temperature measuring elements 25 and 26 of the fluid detection element 11, f(x)=V・co
sθ is detected, and the temperature measuring element 2 of the fluid detection element 12
Wheatstone bridge output y to f including 5, 26
(y)=V·cos(θ−ψ) is detected. From this, V and θ can be determined using the following calculation formula.

[0016]

[Math 1]

[0017]

[Math 2] Note that when ψ=90°, the above equation is simplified as

001
8]

[Math 3]

[0019]

[Math 4]

By configuring the fluid detection unit 2 in this way, the fluid guide plate does not generate flow turbulence 40 until the elevation angle φ in the fluid flow direction B is 15 degrees or more and about 30 degrees. The magnitude V and direction θ of the velocity of the fluid can be detected with good reproducibility without affecting the angular characteristics of the detection element 11 or 12. Furthermore, the structure of the fluid detection section also serves to prevent damage to the fluid detection element due to contact from the outside.

The control unit 3 includes a control circuit for the heater element 24 of the fluid detection element, and temperature measuring resistance elements 25 and 26.
Contains a Wheatstone bridge circuit, its amplifier circuit, and output circuit. The output from the control section can be connected to a display, calculation, and control device such as a personal computer 41 or an FA controller.

The fluid detection device 1 according to the present invention is used, for example, as shown in FIG. 8, in a paint booth 43 of an automobile 42 for the purpose of detecting the magnitude of the flow velocity and the wind direction in the main stream (flow from top to bottom). Ru. In this application, the magnitude of the velocity of the mainstream is 30 to 40 cm/sec, the resolution of the wind direction to be detected is about 2 degrees, and a highly sensitive fluid detection device is required.

9 to 11 show other embodiments of the present invention. In FIGS. 9 and 10, fluid detection elements 11 are provided on curved surfaces 8 and 9 of a pair of fluid guide plates 5 and 6, respectively. and 12 will be installed. More specifically, a mounting base 33 or 34 made of ceramic, for example, on which the fluid detection element 11 or 12 shown in FIG. Install it near the top of the chevron-shaped curved surface 8 or 9 of 6. At this time, care is taken to avoid creating a step between the end of the mounting base 33 and the curved surface 8 and between the end of the mounting base 34 and the curved surface 9.

In this embodiment, the fluid detection element 11 or 12 is installed so as to protrude from the mounting base 33 or 34 into the fluid by the thickness of the fluid detection element 11 or 12. Normally, this protruding structure is considered to have an adverse effect on detection characteristics, but according to a comparative experiment between a protruding structure and a non-protruding structure conducted by the present inventor, it was found that a fluid detection element is included in the fluid detection section 2 of the present invention. When 11 or 12 was installed in this way, the detection characteristics were not adversely affected, and the protruding structure had favorable characteristics such as higher sensitivity and less adhesion of dust and the like to the detection part. Furthermore, the protruding structure is easier to manufacture and has good reproducibility of characteristics between manufactured products.

The mounting bases 33 and 34 have electrical wiring connected from the front surface to the back surface thereof. The lead wire 35 coming out from the back surface is guided to the control section 3 through the support tube 4 as shown in FIG. Further, as shown in FIGS. 9 and 10, the spacer 7 is constituted by a hollow pipe, and the second fluid guide plate 6
The lead wire 36 coming out from the side passes through the hollow part of the spacer 7, enters the support tube 4, and is guided to the control section 3. As shown in FIG. 11, the first fluid detection element 11 and the second fluid detection element 12 are arranged in directions A and C of their respective maximum detection sensitivities.
They are arranged so that they cross each other.

[0026]

As explained above, the fluid detection device of the present invention has high sensitivity and high sensitivity because the fluid detection element has a minute diaphragm portion that is thermally insulated from its substrate.
It features high-speed response and low power consumption. In addition, the pair of fluid guide plates serve as mounting surfaces for the fluid detection element, and also eliminate the influence of turbulent components in the space above them, allowing the fluid to flow to the fluid detection element without disturbing the flow over a wide range of elevation angles φ. It not only guides the flow and enables stable detection, but also protects the fluid detection element from the outside.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a detection section of a fluid detection device according to a first invention.

FIG. 2 is a sectional view of a detection section of the fluid detection device in the first invention.

FIG. 3 is a configuration diagram showing a fluid detection device according to the present invention, partially in cross section.

FIG. 4 is a perspective view of a fluid detection element used in the fluid detection device according to the present invention.

5 is a sectional view taken along line V-V in FIG. 4 and viewed in the direction of the arrow.

6 is an operation explanatory diagram showing temperature distribution of a heater element and a temperature measuring resistance element of the fluid detection element shown in FIG. 5; FIG.

7 is a plan view showing the arrangement of a pair of fluid detection elements in the fluid detection section shown in FIG. 2. FIG.

FIG. 8 is a configuration diagram of the fluid detection device according to the present invention used in an automobile painting line.

FIG. 9 is an external perspective view showing another embodiment of the detection section of the fluid detection device according to the present invention.

10 is a sectional view of the detection section shown in FIG. 9. FIG.

11 is a front view showing the arrangement of fluid detection elements in the fluid detection section shown in FIGS. 19 and 10. FIG.

FIG. 12 is an external perspective view of a detection section of a conventional fluid detection device.

FIG. 13 is a sectional view of the detection section of the fluid detection device shown in FIG. 12.

14 is a plan view of a fluid detection element used in the fluid detection section shown in FIGS. 12 and 13. FIG. In the drawings, the same reference numerals indicate the same or corresponding parts.

[Explanation of symbols]

1 Fluid detection device 2 Fluid detection section 3 Control section 4 Support tube 5 Fluid guide plate 6 Fluid guide plate 7 Spacer 8 Curved surface 9 Curved surface 11 Fluid detection element 12 Fluid detection element 21 Substrate 22 Cavity 23 Diaphragm 24 Heater element 25 Temperature measurement Resistance element 26 Temperature-measuring resistance element 27 Temperature-measuring resistance element 28 Bonding pad 29 Slit 30 Protective film 31 Bonding wire 33 Mounting base 34 Mounting base 35 Lead wire 36 Lead wire 41 Computer 42 Car 43 Paint booth A Maximum of the first detection element Direction of detection sensitivity B Fluid flow direction

Claims (2)

[Claims] Claim 1: A fluid detection element is constructed by forming a thin diaphragm part with a predetermined space in the negative part of the substrate, and providing a heat generating part and a temperature measuring resistor part in this diaphragm part. On the other hand, a pair of fluid guide plates are arranged to face each other with a predetermined interval, and in at least one of the fluid guide plates, the surface facing the other guide plate is 1. A fluid detection device comprising: a curved surface protruding toward a guide plate; and a pair of the fluid detection elements are disposed on the curved surface so that their respective detection directions intersect with each other. 2. A fluid detection element is constructed by providing a predetermined space in a part of the substrate to form a thin diaphragm part, and providing a heat generating part and a temperature measuring resistance part in this diaphragm part. On the other hand, a pair of fluid guide plates are arranged to face each other with a predetermined interval, and the surface of the fluid guide plate facing the other guide plate is a curved surface that protrudes toward the other guide plate. A fluid detection device characterized in that the fluid detection elements are disposed on each curved surface so that their respective detection directions intersect with each other.