JPH0212019A - Flow rate measuring instrument - Google Patents

Abstract

PURPOSE:To reduce the length of a connecting line, to simplify the manufacturing process of the title instrument and to prevent thermal interference between a circuit element and heating element by providing a sensor substrate, heat radiating plate, and hybrid IC. CONSTITUTION:The heat generated from a transistor and reference resistance is absorbed by and radiated from heat radiating plates 11a and 11b. Since the parts of the plates 11a and 11b exposed in a fluid passage wall 1 are efficiently cooled by a fluid made to flow through the passage and the heat generated from the transistor and reference resistance is satisfactorily radiated. In addition, the heat generated from a hybrid IC 18 is also transmitted to the plates 11a and 11b through a connecting pin and taking-out electrode valve and radiated from the plates. In addition, since the transistor and reference resistance are provided on the same sensor substrate 3 together with a heating element and temperature compensating resistance, connecting line among them can be made shorter and wiring can be made easier and as a result, occurrence of noises can be reduced accordingly.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention measures the amount of heat dissipated with respect to the flow of fluid,
The present invention relates to a thermal flow rate measuring device that measures the flow rate of a fluid.

[Prior Art] Conventionally, such a thermal flow rate measuring device requires circuit elements such as a transistor and a reference resistor to control the power supplied to the heating element in order to measure the flow rate of the fluid. Because they generate a considerable amount of heat by themselves, they are usually placed at a considerable distance from the heat generating element to avoid thermal interference with the heat generating element.

Issue 11 to be Solved by the Invention] Therefore, in order to connect the circuit element to the heating element, a long connection line is required, resulting in a problem that wiring takes time and effort.

The present invention has been made to solve the above-mentioned problems, and aims to simplify the manufacturing process by shortening the connection line, and to prevent thermal interference between the circuit element and the heating element. .

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a heating element and a temperature measuring element are installed on the base, and a circuit element for controlling the power supplied to the heating element is also installed on the base. A heat sink is provided on the circuit element to prevent thermal influence from the circuit element to the heat generating element and to radiate heat generated from the circuit element.

"Function" The heat emitted from the circuit element is smoothly radiated by the heat radiator, and thermal interference to the heat generator is prevented.6 Therefore, even if the circuit element is provided on the same base 1 as the heat generator, the circuit The element does not affect the heating element in any way. As a result, the electrical connection line between the circuit element and the heating element can be shortened, wiring is easy, and the heating element and the circuit element can be mounted on the same substrate. Therefore, circuit elements can be assembled, fixed and connected in one step.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

FIG. 6 shows a cross-sectional view of the flow jlk measuring device 2 mounted and fixed on the fluid passage wall 1. The sensor substrate 3 of the flow rate measuring device 2 is a rectangular plate with a length and width of several centimeters, and is made of alumina ceramics or the like. Each part of this sensor board 3 consists of one flow passage wall 1
The end side to be inserted inside is inside, the opposite side is outside, and the third
In the figure, fl! II will be called the front side and the opposite side will be called the back side. A rectangular heat insulating hole 4 extending substantially parallel to the front side of the sensor board 3 is provided at a slightly inner corner f1111 of the inner front corner of the sensor board 3 . This heat insulating hole 4 is for insulating a heat generating element 6, a temperature compensation resistor 7, a transistor 8, and a reference resistor 9, which will be described later.

On the upper surface of this sensor substrate 3, a conductive pattern 5 made of platinum or the like, which is an electrically resistive material whose resistance value changes according to temperature changes, is formed by thick film printing via an insulating film or the like. This conductive pattern 5 has relatively low and high resistance parts by changing its width and material, and the low resistance part is the conductive part 5a, and the high resistance part is the resistive part 5b, 5C. becomes. Such conductive patterns 5 are formed in three rows of elongated ones on the lower surface of the sensor substrate 3, and the tips of the middle row and the tips of the back row are connected with the heating element 6 in between. is formed so as to surround the heat insulating hole 4. Further, the tips of the middle row and the tips of the front row are connected with a temperature compensation resistor 7 in between, and this temperature compensation resistor 7 is formed with multiple bends at a plurality of locations. The heating element 6 is the above-mentioned resistance section 5c, the temperature compensation resistor 7 is the above-mentioned resistance section 5b, and the other parts are the above-mentioned conductive section 5a, and the base ends of the three rows of conductive patterns 5. is the extraction electrode 10. The temperature compensation resistor 7 measures the temperature of the fluid, and the measured temperature and the heating element 6
The flow rate of the fluid can be determined from the supplied power value when controlling the temperature difference between the two and the two to be constant.

Further, five conductive patterns 5 are formed on the upper surface of the sensor substrate 3, three of which extend above the mounting position of the transistor 8, which will be described later, and the remaining two, which will be described later, It extends to the mounting position of the resistor 9, and a chip-type transistor 8 and a reference resistor 9 are soldered to each mounting position. Said 5
The base end portions of the two conductive patterns 5 also serve as extraction electrodes 10. These transistor 8 and reference resistor 9 control the power supplied to the heating element 6.

Rectangular heat sinks 11a and 11b are bonded to the −E surface and bottom surface of the sensor board 3 with an insulating flexible adhesive 12, and these heat sinks 11a and 11b are made of aluminum plates with good thermal conductivity. etc., the width is larger than the sensor substrate 3, the length is shorter than the sensor substrate 3, and the extraction electrode 10,
The heating element 6 and temperature compensation resistor 7 are exposed. Sensor board 3
The heat dissipation plate 1.1a on the upper surface is provided with a thick J-shaped storage hole 13, in which the 1st helangistor 8° reference resistor 9 is stored, and an insulating flexible adhesive is placed in the gap. Agent 1
2, the heat emitted from the transistor 8 and the reference resistor 9 is transferred to the heat sink 1. The heat is radiated by L a,llb, and the heating element 6 is no longer affected by the heat from the transistor 8 and the reference resistor 9. The insulating flexible adhesive 12 is also filled between the portions of the heat sinks 11a and itb that extend beyond the sensor substrate 3.

As shown in FIGS. 4 and 6, an annular rubber grommet 14 is attached around the sensor board 3 to which the heat sinks 11a and 11b are bonded, and inserted into the insertion hole 16 of the resin holder 15. It is inserted and fixed, and the sensor board 3 generates heat 6
, the tip portions of the temperature compensating resistor 7 and the heat sinks 11a and llb are exposed from the resin holder 15. l! !
The resin holder 15 has a cylindrical shape with the insertion hole 16 having a rectangular cross section formed in the center, and the base end of the resin holder 15 has an outwardly rectangular extending portion 1-7 in which the hybrid is inserted. I Ci 8 can be stored. This hybrid ICl3
As shown in FIG.
5 from above 0, 3 from below, connection [[1 terminal 21
is installed protrudingly. The base end of the sensor board 3 is inserted into the connection hole 19, and the connection terminals 21 of the high print ICl 3 are connected to the respective extraction electrodes 10 on both the upper and lower surfaces of the sensor board 3, as shown in FIG. be soldered. A saucer 22 is fitted and fixed into the extending portion 17 . The ()j finger holder 1.5 to which the sensor board 3, heat radiation V 11 a, 11 b, and hybrid ICl 3 are attached is inserted and fixed into the mounting hole 24 of the fluid passage wall 1 with the O-ring 23 in between. Ru.

The heat generated from the transistor 8 and the reference resistor 9 of the 'a quantity measuring device constructed as above is transmitted through the heat sink 1]a,llb
At this time, heat is absorbed and radiated by the heat sink 11.
In the portions a and llb exposed within the fluid passage wall 1,
It is efficiently cooled by the passing fluid, and heat dissipation from the transistors 1 to 8 and the reference resistor 9 is performed smoothly. In addition, the heat radiation plate 11.a, ll is connected to the heat radiation from the hybrid ICl3 through the connecting pin 20, the extraction "FJ!h pole 1°, etc.
The heat is transmitted to b and is dissipated.

Furthermore, since the transistor 8 and the reference resistor 9 are provided on the same sensor substrate 3 as the heating element 6 and the temperature compensation resistor 7, the connection line between them can be short, and wiring is easy! - Assembling the transistor 8 and the reference resistor 9 can be done in a single process of fixing and connecting by soldering.

Note that the fluid inside the fluid passage wall 1 is prevented from leaking to the outside of the fluid passage wall 1 due to the insulating flexible adhesive 12, the grommet 14, and the O-ring 23 between the sensor board 3 and the heat sinks 11a and Ilb. Therefore, the airtightness of the fluid passage wall 1 is maintained.

In this embodiment, the heat sinks 11a and ttb, which radiate heat from the transistor 8 and the reference resistor 9, are exposed in the fluid path, so the heat sinks 11a and llb are efficiently cooled by the a body, and the transistors 8 and Heat dissipation from the reference resistor 9 is performed smoothly. In addition to the transistor 8 and the reference resistor 9,
hybrid! (', 18 is also directly assembled 4f on the sensor board 3.

The connection line is correspondingly shorter, wiring is easier, and the hybrid ICl3 assembly 4-] fixing and connection can be performed in a single process of soldering.

The present invention is not limited to the above embodiments, and can be modified in various ways without departing from the gist of the present invention.
Materials a and 11b may be made of any material other than aluminum plates as long as they have good thermal conductivity, and the present invention can also be applied to hot wire anemometers, baka thermistor anemometers, boundary layer anemometers, etc. ).

[Effects of the Invention] As detailed above, according to the present invention, the heat emitted from the circuit elements is reduced by providing a cooling effect by the heat dissipation body, more preferably by exposing the heat dissipation body in the flow path. heat is radiated smoothly, thermal interference to the heating element is prevented, and even if the circuit element is provided on the same base as the heating element, the circuit element will not have any effect on the heating element. As a result, the electrical connection line between the circuit element and the heating element can be shortened, wiring can be simplified, and noise can be reduced accordingly. In addition, since the heating element and the circuit #1 element are provided on the same base -E, the circuit elements can be assembled, fixed and connected in one process, which reduces manufacturing costs.
It is also possible to reduce the size of the device.

[Brief explanation of the drawing]

1 to 7 show embodiments of the present invention.
3 to 3 are a plan view, a bottom view, and a side view of the sensor board 3 and the heat sinks 1la and llb, and FIG. 4 is a longitudinal cross-sectional view of the flow rate measuring device 2 attached to the fluid passage wall 1. , FIG. 5 is a diagram showing how the hybrid 1'C18 is attached to the sensor board 3, FIG. 6 is a sectional view taken along the line I-I in FIG. 4, and FIG. The assembly of the sensor board 3 and the extraction electrode 10 is a sectional view showing a connected state. 2...Flow rate measuring device, 3...Sensor board, 6...
Heating element, 7... Temperature compensation resistor, 8... Transistor, 9... Reference resistor, lla, llb... Heat sink, 1
2...11 rules for insulated flexible connections, 14...grommet,
15...1!1 Fat holder, 18...Hybrid I
C. Patent applicant: NGK Spark Plug Co., Ltd. Representative: Patent attorney Makoto Wakahara - Figure 1, Figure 1I, Figure 6, Figure 5, Figure 7

Claims (1)

[Claims] 1. A heating element and a temperature measuring element are arranged in a fluid passage, and the flow rate of the fluid is determined based on the relationship between the information from the heating element and the information from the temperature measuring element. In the flow rate measuring device, a base body on which the heating element and the temperature measuring body are installed, a circuit element provided on the base body and controlling power supplied to the heating element, and a circuit element provided for the circuit element and configured to A flow rate measuring device comprising: a heat radiator that prevents thermal influence from a circuit element to the heat generating element and radiates heat generated from the circuit element.