JPS60203858A - Semiconductor flow rate detector - Google Patents

Abstract

PURPOSE:To detect the two-dimensional direction of flow and its flow rate by arranging two semiconductor flow rate detecting elements for detecting the flow rate of fluid in an one-dimentional direction so that respective flow rate detecting directions are intersected at right angles and these elements are thermally insulated each other. CONSTITUTION:The semiconductor flow rate detecting elements 41, 42 are fitted on a thermally insulating carrier plate 7 so that respective flow rate detecting directions are intersected at right angles and these elements are thermally insulated. The outputs of both the elements 41, 42 are led into an arithmetic circuit 10. Since the outputs U1, U2 of respective elements 41, 42 become U1= Uf costheta and U2=Uf sintheta, the Uf and theta are found out from said formulas by the arithmetic circuit 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a semiconductor flow velocity detector capable of detecting the two-dimensional direction and flow velocity of a fluid such as air.

[Technical background of the invention and its problems]

Flow measurement is essential to daily life and industrial activities. - Karman vortex type and ultrasonic type are well-known methods for measuring dimensional flow, such as fluid flowing inside a pipe.In recent years, semiconductor flow velocity detectors have attracted attention due to their ease of mass production and miniaturization. has been done.

However, the two-dimensional flow direction detection and flow velocity measurement that are currently known are limited to mechanical methods such as those used for weather observation, which are small and spatially limited. There is very little that can be used in the limited areas.

[Purpose of the invention]

In view of the above points, an object of the present invention is to provide a semiconductor flow rate detector that is capable of detecting the two-dimensional direction and flow velocity of fluid flow using a semiconductor.

[Summary of the invention]

, the present invention uses two semiconductor flow velocity detection elements that perform -dimensional flow velocity detection, and arranges the detectors so that their flow velocity detection directions are perpendicular to each other and are thermally insulated from each other. Configure.

〔Effect of the invention〕

According to the present invention, the two-dimensional flow direction and flow velocity of the fluid can be determined by performing simple arithmetic processing on the outputs of the two detection elements.

Moreover, since a semiconductor detection element is used, the detector can be made small and inexpensive.

[Embodiments of the invention]

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

FIG. 1 shows a semiconductor flow velocity detection element 4 used in an embodiment of the present invention.
shows. The detection element 4 has a heat generating transistor 2 formed in the center of a semiconductor substrate 1, and temperature measuring transistors Ja and 3b formed at symmetrical positions sandwiching the heat generating transistor 2.

A one-dimensional flow velocity measuring circuit using such a flow velocity detection element 4 is constructed as shown in FIG. A differential circuit is constituted by the temperature measuring transistors 3m and 3b. Reference numeral 5 denotes a fluid temperature measuring transistor, and a differential amplifier 6 is provided to control the heat generating transistor 2 according to the output of the fluid temperature measuring transistor 5. For example, the temperature of the heat generating transistor 2 is always kept 30 degrees higher than the fluid temperature.

With such a configuration, the flow velocity of the fluid in the direction of the arrow shown by the solid line in FIG. 1 can be detected. That is, depending on the velocity of the fluid, the influence of the heat from the heat generating transistor 2 on the temperature measuring transistors 3m and 3b differs, and as the flow velocity increases, the effect between the collectors of the temperature measuring transistors Ja and Jb in FIG. This is because the differential output voltage v0 becomes large. FIG. 3 shows an example of this flow velocity characteristic.

By the way, if the output when the fluid flows at a velocity vf in the direction of the solid arrow in Fig. 1 is IJf, then the output U obtained when the fluid flows at an angle θ in the direction of the dashed arrow is U = U f °. It shows an angular dependence of ma+θ. This situation is shown in Figure 4. This means that of the fluid flow in the direction of the dashed arrow in FIG. 1, only the component in the direction of the solid arrow flows through the temperature measuring transistor Ja.
, 3b.

In the present invention, by utilizing such angular dependence of the -dimensional flow velocity detection element, two semiconductor flow velocity detection elements 41t'!, as shown in FIG. 5, are used. Basically, they are arranged so that their respective flow velocity detection directions are orthogonal to each other as shown by the solid arrows.

FIG. 6 shows a detector configuration according to a specific embodiment of the present invention.

Two semiconductor flow velocity detection elements 41.

4 are mounted closely on a thermally insulating carrier grate 7 so as not to thermally influence each other.

A flow velocity measuring circuit including this flow velocity detector is constructed as shown in FIG. Its basic configuration is the same as in Figure 2, but
The fluid temperature measuring transistor 5 is shared by two detection circuits. Each detection element 4. ,4. The output from the fluid is guided to an arithmetic circuit 10, and the direction and velocity of the fluid flow are determined through predetermined arithmetic processing.

Each element 4 shown by a broken line arrow in FIG. .

Assume that the fluid is flowing in the direction shown by the solid arrow with respect to the detection direction of 4. At this time, each detection element 41y4! Output U8. U, are respectively Ux=Ufoosθ U*=Ufgmθ. Subtracting Uf and θ from these equations, we get Uf=〆■y　1.By performing the above calculations using the arithmetic circuit 10, the flow velocity Uf and the direction θ of the fluid can be determined.

Note that the method of fixing the two semiconductor flow velocity detection elements is arbitrary as long as they do not affect each other thermally. For example, as shown in FIG.
It is also possible to embed and fix the detection elements 41.4.

Further, the semiconductor flow velocity detection element is not limited to the above-mentioned one,
For example, a diffused resistor may be used in the heat generating part, a thermocunol may be used in the temperature measuring element part, etc.

[Brief explanation of the drawing]

Fig. 1 shows an example of a semiconductor flow velocity detection element, Fig. 2 shows a flow velocity measurement circuit using this, Fig. 3 shows its output characteristics, and Fig. 4 shows the angular dependence of the output. FIG. 5 is a diagram showing the basic configuration of the flow velocity detector of the present invention,
FIG. 6 is a diagram showing the flow velocity detector configuration of one embodiment, FIG. 7 is a diagram showing a flow velocity and flow direction measurement circuit using this, and FIG. 8 is a diagram showing the flow velocity detector configuration of another embodiment. It is. 1... Semiconductor substrate, 2... Heat generating transistor, 3
a, 3b...Temperature measurement transistor, 4°41y
4! ...Semiconductor flow rate detection element, 5...Transistor for fluid temperature measurement, 6...Differential amplifier, 7゜8...Carrier plate, 9...thermal insulating material, 10...arithmetic circuit . Applicant's agent Patent attorney Takeshi Suzue Syllable 2 Figure 0 N No. 31

Claims (2)

[Claims] (1) Two semiconductor flow velocity detection elements that detect the flow velocity of a fluid in a one-dimensional direction are arranged so that their respective flow velocity detection directions are perpendicular to each other and are thermally insulated from each other. A semiconductor flow velocity detector featuring: (2) The semiconductor flow rate detection element according to claim 1, wherein the semiconductor flow rate detection element is formed by forming a heat generating part and two temperature measuring elements at symmetrical positions sandwiching the heat generating part on a semiconductor substrate. vessel.