JP2003121226A - Flow sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent heat of a heating element from being conducted to an ambient temperature detecting means by heat conduction to detect a temperature of a fluid precisely. SOLUTION: A flow passage 3 of the fluid 2 is formed of a base plate 4 and a flow passage forming member 6. An electric insulating film 9 is formed on a face in a side opposite to a flow passage 3 side of the base plate 4, and a flow velocity detecting means 8 comprising the heating element 20 and temperature sensors 21A, 21B, and the ambient temperature detecting means 22 are formed thereon. A heat sink 23 is arranged also. Since the heat sink 23 radiates the heat to an outside to be dispersed, when a temperature of the base plate 4 is elevated by the heat of the heating element 20, the heat of the heating element 20 is not conducted substantially to the ambient temperature detecting means 22 to prevent temperature rise in the ambient temperature detecting means 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow sensor used for measuring the flow velocity or flow rate of a fluid flowing in a flow channel, and more particularly to a thermal type flow sensor.

[0002]

2. Description of the Related Art Various thermal type flow sensors for measuring the flow velocity and flow rate of a fluid have been proposed in the past (eg:
JP-A-4-295724, JP-B-6-25684
Japanese Patent Laid-Open No. 8-146026, etc.). In this type of flow sensor, an element equipped with a flow velocity detecting means is usually installed in a pipe so as to be parallel to the flow of the fluid to be measured, and the spatial temperature of the fluid caused by the heat generated from a heating element (heater) is set. A bias in the temperature distribution is caused by the flow, and this is detected by a temperature sensor (indirect heating type), or a change in electric power or resistance due to the heat of the heating element being removed by the fluid is detected (self-heating type). By doing so, the flow velocity or flow rate is measured.

By the way, the conventional flow sensor was mainly used for non-corrosive gas, but recently, a sensor which can be used for liquid and corrosive gas has been developed. For example, as an example thereof, Japanese Patent Laid-Open No. 4-295 mentioned above.
A flow rate sensor disclosed in Japanese Patent No. 724 is known.

In this flow rate sensor, first and second regions are provided on a first surface of a silicon substrate, a heating element and a temperature sensor are provided in the first region, and an ambient temperature sensor is provided in a second region. In order to thermally insulate the first and second regions from each other, a third region made of oxidized porous silicon (insulating layer) is provided between the two regions, and the second surface of the silicon substrate is subjected to fluid flow. It is a side to accept. Further, a silicon cap is fixed to the first surface to increase the rigidity of the silicon substrate and protect the heating element, the temperature sensor and the ambient temperature sensor.

[0005]

However, since the conventional flow rate sensor described above has a structure in which the silicon substrate is directly exposed to the fluid to be measured, it cannot be exposed to corrosive gases or liquids used in semiconductor manufacturing equipment. There was a problem that could not be used. Further, as a measure for preventing heat conduction from the heating element to the ambient temperature sensor, the first region and the second region are thermally insulated from each other by the third region made of oxidized porous silicon. , Since the base itself is made of silicon and has high thermal conductivity, the heat of the heating element is transferred to the ambient temperature sensor through the lower side of the insulating layer, so the thermal effect of the heating element on the ambient temperature sensor is sufficiently prevented. However, as a result, the temperature of the ambient temperature sensor rises, and the temperature of the fluid cannot be measured accurately, resulting in low measurement accuracy. Further, since the step of placing the silicon base in the oxidation furnace and oxidizing the third region is required, the manufacturing of the silicon base is troublesome.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to prevent the heat of the heating element from being transmitted to the ambient temperature detecting means by heat conduction, so that the temperature of the fluid can be accurately measured. Another object of the present invention is to provide a flow sensor capable of detecting the flow rate and improving the flow rate detection accuracy.

[0007]

In order to achieve the above object, a first aspect of the present invention is directed to a thin plate-like substrate forming a part of a fluid passage, and a surface of the substrate opposite to the passage side. A flow velocity detecting means and an ambient temperature detecting means, and a heat sink projecting on a side opposite to the flow path of the substrate so as to partition a space between the flow velocity detecting means and the ambient temperature detecting means. Be prepared.

According to a second aspect of the present invention, there is provided a flow path forming member which constitutes a flow path of a fluid and has an opening in the middle of the flow path, and a thin plate-like substrate which closes the opening of the flow path forming member. A flow path of the substrate so as to partition a space between the flow speed detecting means and the ambient temperature detecting means provided on the surface of the substrate opposite to the flow path side, and the flow velocity detecting means and the ambient temperature detecting means. And a heat sink protruding from the opposite side.

A third invention is the same as the first or second invention, wherein the substrate is made of any one of stainless steel, sapphire and ceramics.

A fourth aspect of the invention is the same as the first or second aspect of the invention, in which the flow path forming member is formed of any one of stainless steel, sapphire, and ceramics.

In the first and second inventions, when the heating element of the flow velocity detecting means is heated, the heat is transferred to the substrate to raise the temperature of the substrate. If there is no heat sink between the heating element and the ambient temperature detecting means, the heat transferred to the substrate is transferred to the ambient temperature detecting means by heat conduction, so that the temperature of the ambient temperature detecting means is raised. If a heat sink is provided between the heating element and the ambient temperature detecting means, the heat transferred to the substrate is transferred to the heat sink by heat conduction, and the heat is radiated by the heat sink. Therefore, the temperature of the ambient temperature detecting means hardly changes, and the temperature of the fluid is accurately measured. The greater the heat capacity and heat dissipation effect of the heat sink, the less the thermal influence on the ambient temperature detecting means. Since the flow velocity detection means including the heating element is provided on the surface of the substrate opposite to the flow passage side, the fluid does not come into direct contact with the flow velocity detection means, and the corrosive gas or liquid of the corrosive gas or liquid is selected by selecting the material of the substrate. It can be used for measurement. Since the flow velocity detecting means is not exposed to the fluid, there is no possibility that dust will be accumulated, the resistance value will change due to the fluid, or it will change over time, and stable performance is maintained. Since the substrate is a thin plate, the fluid and the flow velocity detecting means are thermally short-circuited.

In the second aspect of the invention, the flow velocity or flow rate can be measured simply by incorporating the flow sensor in the flow channel.
Further, since the flow path can be formed with high accuracy in accordance with the measurement range or the like, it is suitable for a sensor for high accuracy or high flow rate.

In the third and fourth aspects of the invention, since the substrate and the flow path forming member are made of stainless steel, sapphire or ceramics, they are excellent in corrosion resistance and can be used for measuring corrosive gas or liquid.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments shown in the drawings. 1 (a), (b),
(C) is a front view, a sectional view and a rear view showing an embodiment of a flow sensor according to the present invention, and FIG. 2 is a front view of a sensor section. In these drawings, a flow sensor indicated by reference numeral 1 as a whole includes a substrate 4, a front surface, a back surface 4a, and a back surface of the substrate 4.
4b, which includes a plate 5 and a flow path forming member 6 which are joined to each other by welding, brazing, screws, etc., and a fluid to be measured (hereinafter referred to as fluid) 2 is formed by the back surface 4b of the substrate 4 and the flow path forming member 6. And constitutes a part of the flow path 3.

The substrate 4 is formed in the shape of an elongated rectangular thin plate, and the outer peripheral edge of the back surface 4b is joined to the surface of the flow path forming member 6. The material of the substrate 4 is preferably a material having a lower thermal conductivity than silicon and high heat resistance, corrosion resistance and rigidity. For this reason, in the present embodiment, a thin plate made of stainless steel having a plate thickness of about 50 to 150 μm is formed, and the central portion thereof is used as a sensor portion 4A having a diaphragm structure and is separated from the plate 5. Therefore, a through hole 7 is formed in the center of the plate 5 so as to correspond to the sensor portion 4A.

In this case, in FIG. 2, the sensor portion 4A having a diaphragm structure is shown as a circle, but it is preferable to form it into an ellipse which is long in the fluid flow direction as shown in FIG. The reason is that in the case of a circular shape, if the distance between the ambient temperature sensor 22 and the heat sink 23 is increased in order to improve the heat balance of the sensor, the diameter of the diaphragm is increased, the length of the heat sink 23 is increased, and the strength of the diaphragm is increased. On the other hand, when the fluid has an oval shape in the longitudinal direction, the diameter of the diaphragm in the minor axis direction does not increase even if the distance between the ambient temperature sensor 22 and the heat sink 23 is increased, and the length of the heat sink 23 increases. Is not long,
This is because the reduction in the strength of the diaphragm can be reduced as compared with the circular shape.

When the substrate 4 is made of stainless steel and its plate thickness is 50 μm or less, the strength is lowered, which is not preferable. Further, when it is 150 μm or more, the heat transfer efficiency in the thickness direction of the substrate 4, that is, the heat transfer efficiency between the fluid 2 and the flow velocity detecting means 8 described later decreases, and the heat transfer amount in the direction parallel to the surface of the substrate 4 ( (Heat loss) increases, which is not preferable.

An electric insulating film 9 is formed on the surface 4a of the substrate 4.
Are formed over the entire surface. In addition, the electric insulation film 9
The flow velocity detecting means 8 including the plurality of electrode pads 10 and the metal thin film 11 for wiring and the ambient temperature detecting means 22 are formed by a well-known thin film forming technique in the central portion of the surface corresponding to the sensor portion 4A. . For example, a material such as platinum is deposited on the surface of the electric insulating film 9 and formed into a predetermined pattern by etching, and the flow velocity detecting means 8 and the ambient temperature detecting means 22 are provided on the electrode pad 10 for the wiring metal thin film 1.
1 are electrically connected to each other.

As the electric insulating film 9, for example, thin silicon oxide (SiO 2) having a thickness of about several thousand angstroms is used.
₂ ) Film or silicon nitride film. The silicon oxide film is formed by, for example, sputtering, CVD, or applying a solvent mixed with silicon oxide and heating it to a predetermined temperature to form silicon oxide. The silicon nitride film is formed by sputtering or CVD.

The flow velocity detecting means 8 comprises one heating element (resistive heater) 20 and two temperature sensors 21A and 21B, and constitutes an indirectly heated flow velocity detecting means. Heating element 2
0 is located substantially in the center of the sensor unit 4A. The two temperature sensors 21A and 21B are formed so as to be respectively located on the upstream side and the downstream side in the flow direction of the fluid 2 with the heating element 20 interposed therebetween. The ambient temperature detecting means 22 is used for compensating for a change in ambient temperature, that is, when the temperature of the fluid 2 changes. The ambient temperature detecting means 22 is closer to the outer periphery of the sensor portion 4A and is further upstream than the upstream temperature sensor 21A. Is formed so as to be located at. The line width of the pattern of the heating element 20 is 1
The line width of the pattern of 0 to 50 μm, the temperature sensors 21A and 21B, and the ambient temperature detecting means 22 is preferably about 5 to 10 μm.

Further, on the surface 4a of the sensor portion 4A,
A heat sink 23 is provided so as to partition the space between the heating element 20 (strictly speaking, the temperature sensor 21A) and the ambient temperature detecting means 22. The heat sink 23 is formed in a flat plate shape (or a cylindrical shape) having an appropriate plate thickness with a metal having a good heat dissipation property, for example, and crosses the sensor portion 4A, and both end surfaces are fixed to the hole wall of the through hole 7. Has been done. Further, as the heat sink 23, one having a large heat capacity is preferable in order to enhance the heat radiation effect. In addition, it is preferable that a portion of the heat sink 23 that contacts the wiring metal thin film 11 is covered with an insulating film so as not to be electrically connected.

The plate 5 has the through hole 7 in the center thereof, and the printed wiring board 30 is closely fixed to the surface thereof. This printed circuit board 30 has the plate 5 at the center.
Has a hole 30a having substantially the same size as the through hole 7 of FIG. 1, a wiring pattern 31 is formed by printing on the front surface side, and a plurality of lead pins 32 electrically connected to the wiring pattern 31 are provided in a protruding manner. There is. On the wiring pattern 31, the electrode pad 10 of the flow velocity detecting means 8 is bonded to the bonding wire 3
An external lead wire (not shown) is connected to the lead pin 32.

As the material of the plate 5, a material having high thermal conductivity, heat resistance, and rigidity is preferable in order to serve as a structural material and a heat sink similarly to the flow path forming member 6, but the fluid 2 is preferable. Since they do not come into direct contact, they do not need much corrosion resistance.

The flow path forming member 6 is an elongated plate member 36.
And two cylinders 37A, 37B joined to both ends of the plate 36 on the back side in the longitudinal direction. However, the plate body 36 and the cylindrical bodies 37A and 37B may be integrally formed. The plate body 36 has two through holes 38A and 38B formed at both ends in the longitudinal direction and communicating with the cylindrical bodies 37A and 37B, respectively, and these through holes 38.
It has an oval recess 39 formed on the surface side so that A and 38B communicate with each other. The recess 39 has a width slightly smaller than the width of the substrate 4 and a depth of 0.5 to several meters.
At a distance of about m, a small space formed between the substrate 4 and the back surface 4b forms a part 3a of the flow path 3 of the fluid 2.

As the material of the flow path forming member 6, a material having a high heat conductivity, a high heat resistance, a high corrosion resistance and a high rigidity is preferable because it serves as a structural material and a heat sink. Further, in order to apply the flow sensor 1 to a corrosive fluid, it is preferable that all the portions that come into contact with the fluid 2 are made of the same material having corrosion resistance, and that the joining between the respective members does not use different materials for joining. It is preferable to carry out. Therefore, in the present embodiment, the plate 5 and the flow path forming member 6 are made of stainless steel (especially,
SUS316L). When the substrate 4, the plate 5 and the flow path forming member 6 are made of stainless steel in this way, they can be joined by using YAG laser welding or the like without using dissimilar metals. Further, stainless steel is relatively excellent in workability and is suitable as a sensor material. However, not only stainless steel but also a material having a high thermal conductivity such as sapphire or ceramics can be used because the heat transfer in the surface direction can be reduced by making the material thin accordingly. Note that the thermal conductivity of stainless steel, sapphire, and ceramics at 300 K depends on their compositions, but is 16.0, 46.0, and 36.0, respectively.
[W / m · K].

FIG. 3 is a diagram showing a constant temperature difference circuit of the flow sensor 1. In the figure, the heating element 20, the ambient temperature detecting means 22 and the three fixed resistors R1, R2 and R3 form a bridge circuit, and this and an operational amplifier (OP1) form a constant temperature difference circuit. OP1 receives the bridge circuit, the midpoint voltage of the resistor R1 and the heating element 20 as an inverting input, and the midpoint voltage of the resistors R2 and R3 as a non-inverting input. The output of OP1 is commonly connected to one ends of resistors R1 and R2. The resistances of the resistors R1, R2 and R3 are set so that the heat generating element 20 is always higher in temperature than the ambient temperature detecting means 22 by a constant temperature.

FIG. 4 is a diagram showing a sensor output circuit of the flow sensor 1. In the figure, two temperature sensors 21
A and 21B and two fixed resistors R4 and R5 form a bridge circuit, and OP2 forms a sensor output circuit.

In such a flow sensor 1, as shown in FIG.
When the fluid 2 is caused to flow in the direction of the arrow in FIG. 2 while the heating element 20 is heated to a certain higher temperature than the ambient temperature by energizing the bridge circuit of the constant temperature difference circuit shown in FIG.
Since the heat of the fluid A is taken away by the fluid 2 in proportion to its flow rate, the heating element 20 is also taken away of the heat and the resistance value is lowered. For this reason, the equilibrium state of the bridge circuit is lost, but since a voltage corresponding to the voltage generated between the inverting input and the non-inverting input of OP1 is applied to the bridge circuit, heat is generated so as to compensate for the heat taken by the fluid 2. The amount of heat generated by the body 20 increases. As a result, the resistance value of the heating element 20 increases, and the bridge circuit returns to the equilibrium state. Therefore, since a voltage according to the flow velocity is applied to the bridge circuit in the equilibrium state, among the voltages applied to the bridge circuit, the terminal voltage of the heating element 20 is output as a voltage output. Can be used.

When the fluid 2 takes away the heat of the heating element 20, a temperature difference occurs between the temperature sensor 21A located upstream of the heating element 20 and the temperature sensor 21B located downstream of the heating element 20, so that the sensor shown in FIG. The voltage difference or resistance value difference is detected by the output circuit, and the flow rate or flow rate can be measured based on the relationship between the flow rate or flow rate and the voltage difference or resistance value difference that have been calibrated in advance.

In the flow sensor 1 as described above, the flow velocity detecting means 8 and the ambient temperature detecting means 22 are provided on the surface of the substrate 4 made of a thin plate opposite to the surface in contact with the fluid 2, that is, the surface 4a. Since it is provided, the flow velocity detecting means 8, the electrode pad 10, the wiring metal thin film 11, and the ambient temperature detecting means 22.
Can be used for the measurement of corrosive gases and liquids used in semiconductor manufacturing equipment, etc. without directly contacting the fluid 2 and causing corrosion or deterioration, or dust adhesion. Therefore, the reliability and durability of the sensor can be improved.

Further, since the substrate 4 is made of stainless steel having a low thermal conductivity in the form of a thin plate, heat conduction in the direction parallel to the plane is small, and the thickness direction of the substrate 4, that is, the fluid 2 and the flow velocity. The heat conduction between the detection means 8 is good, and the responsiveness can be improved. Also, stainless steel has heat resistance,
It has excellent corrosion resistance, workability and rigidity, and is suitable as a sensor material.

Further, since the heat sink 23 is provided between the heat generating element 20 (strictly speaking, the upstream temperature sensor 21A) and the ambient temperature detecting means 22, the heat generating element 20 and the ambient temperature detecting means 22 are thermally coupled. Insulation can be performed and measurement accuracy can be improved. That is, when a heat sink is not used as shown in FIG. 5A, when the heating element 20 is heated, the temperature of the substrate 4 rises due to the heat, so the temperature of the ambient temperature detecting means 22 also rises due to heat conduction. This temperature rise causes a measurement error and the temperature of the fluid 2 cannot be accurately measured.

On the other hand, as shown in FIG.
If the heat sink 23 is provided between the ambient temperature detecting means 22 and the ambient temperature detecting means 22, even if the temperature of the substrate 4 rises due to the heating of the heating element 20, the heat is transmitted to the heat sink 23 and dissipated to the outside, so that the heat is dissipated. Heat sink 2
Almost no heat is transferred from 3 to the ambient temperature detecting means 22 side,
The temperature rise of the ambient temperature detecting means 22 is suppressed. Therefore, the ambient temperature detecting means 22 measures the temperature of the fluid 2 with high accuracy. In this case, if the heat capacity of the heat sink 23 is increased, the heat dissipation effect is also large, so that the heat conducted from the heating element 20 to the substrate 4 is effectively dissipated, and the thermal influence on the ambient temperature detecting means 22 is further enhanced. It can be reduced. In addition, 40 is an isotherm.

By the way, when an experiment was conducted with and without the heat sink 23, the heating element 2
When 0 is heated to a predetermined temperature, the temperature of the ambient temperature detecting means 22 rises by 5 ° C. when the heat sink 23 is not provided, whereas the temperature of the ambient temperature detecting means 22 almost rises when the heat sink 23 is provided. There wasn't.

FIGS. 6A, 6B and 6C are a front view, a sectional view and a rear view showing another embodiment of the present invention. In addition, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

In this embodiment, the pipe forming the flow path 3 of the fluid 2 is used as the flow path forming member 41, and the sensor mounting hole 42 is formed in the flow path forming member 41, and the sensor mounting hole 42 is provided with the header. Type flow sensor 43,
The back surface of the substrate 4 is brought into contact with the fluid 2.

The flow sensor 43 includes a cup-shaped case 45 with a collar, the substrate 4 covering the rear opening 46 of the case 45, a plurality of electrodes 50 incorporated in the case 45, and the like. The case 45 is fitted in the sensor mounting hole 42 of the flow path forming member 41 together with a sealing member such as an O-ring, and is fixed by a screw, an adhesive or the like. The back opening 46 is formed in an oval shape that is long in the flow direction of the fluid 2.

The substrate 4 is made of stainless steel in the form of a thin plate, and the flow velocity detecting means 8, the electrode pad 10, the wiring metal thin film 11, the ambient temperature detecting means 22 and the heat sink 23 shown in FIG. Are provided via an electric insulating film (not shown). It should be noted that the substrate 4 is not limited to a square and may have another shape such as an oval.

The case 45 is made of stainless steel, is attached to the sensor mounting hole 42 of the flow path forming member 41, and the flange 45a is joined to the outer peripheral surface of the flow path forming member 41 by YAG laser welding or the like. The back surface of the case 45 and the back surface of the substrate 4 form the same surface as the inner wall surface 41 a of the flow path forming member 41 and form a part of the flow path 3.

As the electrode 50, a metal frame 51 having a plurality of terminal pins 52 sealed with hermetic glass 53 is used, and one end of each terminal pin 52 is connected to the electrode pad 10 of the wiring metal thin film 11. Connected by brazing. Note that it is also possible to connect to the electrode pads 10 by using wire bonds without using such a metal frame 51.

The flow sensor 43 having such a structure
In the above, since the sensor mounting hole 42 is formed in the flow path forming member 41, the flow sensor 43 is fitted and fixed in the sensor mounting hole 42, and the back surface of the substrate 4 is brought into contact with the fluid 2, it is special. There is no need to use equipment, parts, etc.
Can be easily installed.

Further, since the heat sink 23 is provided, the thermal influence on the ambient temperature detecting means 22 can be prevented from being reduced and the measurement accuracy of the sensor can be improved as in the above-mentioned embodiment.

The present invention is not limited to the above-described embodiment, and various changes and modifications can be made. For example, in the above-described embodiment, the heating element 2
The spatial temperature distribution of the fluid 2 due to the heat generated from 0 is biased by the flow, and this is caused by the two temperature sensors 21A,
Although an example of using the indirectly heated sensor for detecting at 21B is shown, the invention is not limited to this, and a change in electric power or a change in resistance due to the heat of the heating element 20 being taken away by the fluid 2 is detected to determine the flow rate or flow velocity. A self-heating type sensor for detecting may be used. Further, although the two temperature sensors 21A and 21B are used, the number may be one. Further, the ambient temperature detecting means 2
Two of the two may be used and may be arranged to face each other in the flow direction of the fluid 2 or in the direction orthogonal to the flow direction.

[0044]

As described above, according to the flow sensor of the present invention, the heat transmitted from the flow velocity detecting means to the substrate is radiated by the heat sink.
It is possible to prevent the temperature of the ambient temperature detecting means from rising due to heat conduction, and improve the measurement accuracy of the sensor. Further, since it is only necessary to project the heat sink on the substrate, the structure is simple and it can be easily manufactured. Also,
Since the flow velocity detection means and the ambient temperature detection means do not come into direct contact with the fluid, it is possible to support the measurement of liquid and corrosive gas by selecting the material of the substrate, and to provide a sensor with high reliability and durability. You can

The material of the substrate is stainless steel,
Examples include sapphire and ceramics. Among them, stainless steel is a material that is extremely suitable in terms of corrosion resistance, workability, thermal conductivity, and rigidity, and sapphire is preferable when it is necessary to particularly improve corrosion resistance. Is. Further, the plate thickness of the substrate is preferably formed as thin as possible in order to improve the heat conduction between the fluid and the flow velocity detecting means and reduce the heat conduction in the lateral direction in the substrate. It is necessary to decide in consideration of external factors in manufacturing such as strength and handling. Therefore, in the case of stainless steel, about 50 to 150 μm is optimal.

[Brief description of drawings]

1A, 1B, and 1C are a front view, a cross-sectional view, and a rear view showing an embodiment of a flow sensor according to the present invention.

FIG. 2 is a front view of a sensor unit.

FIG. 3 is a diagram showing a constant temperature difference circuit of a flow sensor.

FIG. 4 is a diagram showing a sensor output circuit.

FIG. 5 is a diagram for explaining the effect of the present invention,
(A) is a figure when a heat sink is not provided, and (b) is a figure when a heat sink is provided.

FIG. 6 is a front view, a sectional view, and a rear view showing another embodiment of the present invention.

[Explanation of symbols]

1 ... Flow sensor, 2 ... Fluid, 3 ... Flow path, 4 ... Substrate, 4
A ... Sensor part, 5 ... Plate, 6 ... Flow path forming member, 8 ...
Flow velocity detecting means, 20 ... Heating element (heater), 21A, 21
B ... Temperature sensor, 22 ... Ambient temperature detecting means, 23 ... Heat sink, 41 ... Flow path forming member, 43 ... Flow sensor,
45 ... Case.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shouji Kamiten             2-12-19 Shibuya, Shibuya-ku, Tokyo Stock market             Takeyama (72) Inventor Taro Nakata             2-12-19 Shibuya, Shibuya-ku, Tokyo Stock market             Takeyama F-term (reference) 2F035 EA05 EA08

Claims (4)

[Claims] 1. A thin plate-shaped substrate forming a part of a fluid flow path, a flow velocity detecting means and an ambient temperature detecting means provided on a surface of the substrate opposite to the flow channel side, and the flow velocity detecting means. A flow sensor comprising: a heat sink projecting from a side surface of the substrate opposite to the flow path so as to partition a space between the means and the ambient temperature detecting means. 2. A flow path forming member that constitutes a flow path of a fluid and has an opening in the middle of the flow path, a thin plate-like substrate that closes the opening of the flow path forming member, and a substrate of this substrate. The flow passage detecting means and the ambient temperature detecting means provided on the surface opposite to the flow passage side, and the side surface opposite to the flow passage of the substrate so as to partition the space between the flow velocity detecting means and the ambient temperature detecting means. A flow sensor, comprising: a heat sink projecting from the. 3. The flow sensor according to claim 1, wherein the substrate is made of any one of stainless steel, sapphire, and ceramics. 4. The flow sensor according to claim 1, wherein the flow path forming member is formed of any one of stainless steel, sapphire, and ceramics.