JP3470881B2 - Micro flow sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microflow sensor which enables accurate measurement of a wide range of flow rate from a small flow rate to a large flow rate.

Specifically, 1: 1000 to 1: 1000
We propose a micro flow sensor that satisfies the rangeability of 00.

[0003]

2. Description of the Related Art A conventionally known microflow sensor is manufactured by a semiconductor process based on Si (silicon) and, as shown in FIG. 5, is used as a microheater 32 and a temperature sensor on a diaphragm 31. Thermopile (hereinafter referred to as anti-thermopile)
33 (33a, 33b) are arranged.

The temperature sensor is not limited to the thermopile, but a temperature measuring resistor, a thermistor, a pyroelectric body, etc. may be used.

In this microflow sensor, the microheater 32 is heated in the flow of the fluid (gas or the like) to be measured, and the temperature output of one thermopile 33a arranged upstream of the microheater 32 and the microheater 32.
The principle of measuring the flow velocity and the flow rate based on the difference with the temperature output of the other thermopile 33b arranged on the downstream side of is adopted.

Further, in recent years, miniaturization of gas meters has progressed, and attempts have been made to measure a wide range of flow rates from a small flow rate to a large flow rate with a single microflow sensor.

[0007]

However, in such a conventional micro flow sensor, even if an attempt is made to measure a wide range of flow rate from a small flow rate to a large flow rate, if the flow rate of the fluid to be measured is large, it is output at the time of measurement. However, there is a problem that the measurement is impossible in reality because the saturation occurs.

More specifically, when the air flow of the fluid to be measured remains at a small flow rate, the amount of heat transfer from the air stream to be measured is small, so the anti-thermopile 33 (33) is used.
The temperature of the hot junction of a, 33b) is low, and the temperature difference with the fluid to be measured is large. Therefore, the amount of heat transfer from the measurement target fluid is proportional to the flow velocity (flow rate) of the measurement target fluid, and an accurate output can be obtained.

On the other hand, when the flow rate of the fluid to be measured becomes large, the amount of heat transfer from the fluid to be measured is large, and therefore the temperature of the hot junction of the thermopile 33 (33a, 33b) becomes high. , The temperature difference with the fluid to be measured becomes extremely small. Therefore, the output is saturated, the amount of heat transfer from the fluid to be measured is not proportional to the flow velocity (flow rate) of the fluid to be measured, and accurate output cannot be obtained.

The present invention focuses on the above-mentioned conventional drawbacks and solves the problems. An object of the present invention is to provide a microflow sensor capable of accurately measuring a wide range of flow rate from a small flow rate to a large flow rate. To provide.

[0011]

A microflow sensor according to the present invention described in claim 1 is symmetrically arranged on each of an upstream side and a downstream side of a microheater arranged in an air flow of a fluid to be measured. that comprises two at least two pairs vs. temperature sensor comprising a temperature sensor, Ri Na by placing each pair temperature sensors so that different respective distances from the micro heater for each set, said at least two sets of pairs Temperature sensor
However, the closer to the temperature sensor the micro-heater is, the more
The above-mentioned meter can be used rather than the temperature sensor remote from the micro heater.
Temperature sensing for each of the above temperature sensors against the amount of heat from the fluid to be measured
It is characterized in that it is composed of a temperature sensor having a high temperature rise sensitivity .

According to the microflow sensor of the present invention described in claim 1, the temperature sensor close to the microheater measures a small flow rate, and the temperature sensor far from the microheater measures a large flow rate. It is possible to accurately measure a wide range of flow rate from a small flow rate to a large flow rate.

More specifically, the temperature sensor farther from the micro heater reaches the temperature sensor while the fluid to be measured is cooled by the diffusion of the fluid, so that it is difficult to measure a small flow rate. On the other hand, the temperature sensor close to the micro-heater has a large temperature rise in the temperature sensor temperature sensing part,
It exceeds the temperature sensitivity range of the temperature sensor, making it difficult to measure a large flow rate.

However, by arranging both of the above two sets of temperature sensors, it becomes possible to measure from a small flow rate to a large flow rate in a manner that complements each other.

[0015]

Further, according to the micro-flow sensor of the present invention as set forth in claim 1, and a temperature rise difference between the temperature sensor temperature sensing unit according to a distance difference between the micro-heater, each pair temperature sensors for heat from the measurement object fluid The synergistic effect with the temperature rise sensitivity difference of the temperature sensing part enables a wider range of flow rate measurement.

According to a second aspect of the present invention, in the microflow sensor, two temperature sensors are symmetrically arranged on the upstream side and the downstream side of the microheater arranged in the air flow of the fluid to be measured. comprising at least two pairs vs. temperature sensor consisting, that the temperature rise speed of the temperature sensing portion of said each pair temperature sensors for heat from the measurement object fluid is formed at each different pair temperature sensors for each set Characterize.

According to the second aspect of the microflow sensor of the present invention, the temperature rise sensitivity difference of each temperature sensor temperature sensing portion with respect to the amount of heat from the fluid to be measured is utilized to obtain a high heat temperature rise sensitivity. Since the temperature sensor measures the small flow rate and the temperature sensor having low thermal temperature rise sensitivity measures the large flow rate, the wide range flow rate from the small flow rate to the large flow rate can be accurately measured.

More specifically, even if the amount of heat transferred from the fluid to be measured warmed by the micro heater is the same, if the temperature sensitivity of the temperature sensor is high, the temperature of the temperature sensor temperature sensing section is relatively low and the temperature is above. The temperature of the fluid to be measured is close to the temperature of the fluid to be measured, and the output is saturated without becoming a temperature higher than the temperature of the fluid to be measured. Since the amount of heat transfer has a monotonically increasing relationship with the flow rate of the fluid to be measured, a temperature sensor that has a low sensitivity to rise in temperature increases the flow rate at which the output saturates, and a larger flow rate can be measured. become. On the other hand, when the heat temperature rise sensitivity is high, the sensor sensitivity is generated even with a small amount of heat transfer, so that a smaller flow rate can be measured.

Therefore, by arranging both of the above-mentioned two sets of temperature sensors, it becomes possible to measure from a small flow rate to a large flow rate in a manner complementary to each other.

The micro-flow sensor of the present invention described in claim 3 is the micro-flow sensor according to claim 2, wherein the at least two sets of pairs temperature sensor, the heat capacity of each pair temperature sensor temperature sensing unit are each different It is characterized in that it is formed in.

According to the third aspect of the microflow sensor of the present invention, for the same amount of heat transfer, if the heat capacity is large, the heat temperature rise sensitivity becomes small, and the temperature rise in the temperature sensing part becomes slow. When the heat capacity is small, the heat temperature rise sensitivity is high, and the temperature rise of the temperature sensor temperature sensitive portion is sharp.

A microflow sensor according to a fourth aspect of the present invention is the microflow sensor according to the second or third aspect, wherein the at least two pairs of temperature sensors have respective temperature sensor temperature sensing parts and sensor bases. It is characterized in that they are formed so as to have different thermal resistances.

According to the microflow sensor of the fourth aspect of the present invention, if the thermal resistance between the temperature sensor temperature sensing portion and the sensor base is small for the same amount of heat transfer, heat is immediately transferred to the sensor base. However, since the sensor base immediately radiates heat to the housing to which the microflow sensor is attached, the heat temperature rise sensitivity becomes small, and the temperature rise in the temperature sensor temperature sensing portion becomes slow.

On the other hand, if the thermal resistance between the temperature sensor temperature sensing portion and the sensor base is large for the same amount of heat transfer, heat is not readily transferred to the sensor base and the sensor base is immediately attached with the microflow sensor. Since the heat is not radiated to the housing, the heat temperature sensitivity is high and the temperature rise of the temperature sensor temperature sensing portion is sharp.

A microflow sensor according to a fifth aspect of the present invention is the microflow sensor according to any one of the second to fourth aspects, wherein the at least two pairs of temperature sensors have different wiring patterns for each pair. It is characterized by being formed by.

According to the microflow sensor of the fifth aspect of the present invention, at least two pairs of temperature sensors are formed in different wiring patterns for each group, and as a result, each pair of temperature sensors of each group is heated. The distance between the sensor and the micro heater is different, or the temperature rise sensitivity of the temperature sensing part of each temperature sensor with respect to the amount of heat from the fluid to be measured is different. Since it is possible to measure each area by subdividing a wide area from a large flow rate to, it is possible to accurately measure a wide area flow rate from a small flow rate to a large flow rate.

In each of the microflow sensors described in claims 1 to 5 , when the same temperature sensor of each set is made of the same material, they are simultaneously formed and arranged during the manufacturing process. Therefore, it is possible to efficiently manufacture the device without requiring additional steps.

A microflow sensor according to a sixth aspect of the present invention is the microflow sensor according to any one of the first to fifth aspects, wherein the at least two pairs of temperature sensors are made of different materials. It is characterized by consisting of things.

According to the microflow sensor of the present invention described in claim 6 , at least two pairs of temperature sensors are made of different materials for each pair, and as a result,
The distance from the micro heater of each pair of temperature sensors of each set is made different, or the temperature rise sensitivity of the temperature sensing part of each pair of temperature sensors to the amount of heat from the fluid to be measured is made different, and The temperature sensor can accurately measure a wide range of flow rate from a small flow rate to a large flow rate.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to the accompanying drawings. Here, in FIG.
FIG. 1A is a schematic plan view showing a first embodiment of a microflow sensor of the present invention, and FIG. 1B is a schematic side view of FIG. 1A.

The microflow sensor shown in FIG. 1 includes a diaphragm 11, a microheater 12 arranged in the air flow of a fluid to be measured (gas or the like), and a flow direction of the fluid to be measured. In X, two pairs of paired thermopiles 13 (13a, 1) are symmetrically arranged on the upstream side and the downstream side of the microheater 12, respectively.
3b) and 14 (14a, 14b), and each pair of thermopiles is arranged so that the distance from the microheater 12 is different. Incidentally, here, each pair of thermopiles 13 (13a, 13b), 1
4 (14a, 14b) are made of the same material, and can be formed and arranged at the same time during the manufacturing process, so that an additional process is not required and efficient manufacturing is possible. Has become.

Generally, a thermopile is a temperature sensor having a hot junction group serving as a temperature sensing section and a cold junction group serving as a reference temperature sensing section, and the temperature difference between the cold junction reference temperature and the temperature sensing section temperature is the output voltage. It is a sensor.

The thermopile 13a used in this embodiment,
The cold junction groups 13b, 14a, 14b are arranged in the thick portions 11a, 11a serving as the sensor base made of Si,
Since the base body is arranged in good thermal contact with the housing to which the sensor is attached, the temperature is the temperature of the fluid to be measured.

On the other hand, the hot junction group is arranged on the diaphragm 11 made of an oxide film having a good heat insulating property, and is proportional to the difference between the temperature of the fluid to be measured heated by the micro heater 12 and the temperature of the hot junction group. The amount of heat moves to the hot junction, warms the hot junction group, and the temperature difference between the hot junction group and the cold junction group becomes the output of the thermopiles 13 and 14.

The thermopile 13a used in this embodiment,
13b, 14a, and 14b are S to which boron ions are added.
It was made of i wiring and Al wiring.

In this embodiment, the thermopile 13a, 1
3b, 14a, and 14b are used on the upstream side and the downstream side of the microheater 12, and the pair of thermopiles 13 and 14 symmetrically arranged with the microheater 12 sandwiched therebetween are used. Since the output difference of the thermopile output has a monotonically increasing relationship with the flow rate of the fluid to be measured, the flow rate is measured.

The micro-heater 12 arranged at the substantial center of the diaphragm 11 is usually driven by a rectangular pulse voltage or current of about 10 to 20 milliseconds. It may be driven by using a feedback circuit so that the temperature becomes constant.

The thermopile 13 close to the micro heater 12 is used for measuring a small flow rate because a temperature difference between the upstream side and the downstream side is likely to appear even if the flow rate is small.

On the other hand, the thermopile 14 far from the micro-heater 12 is unlikely to show a temperature difference unless the flow rate becomes large to a certain extent, but the temperature difference tends to change with a large flow rate change, and is used for the measurement of the flow rate. To be

As long as the distance relationship between the microheater 12 and the thermopiles 13 and 14 does not change, FIG.
As shown in a schematic plan view in (a) and a sectional view taken along line AA of FIG. 2 (a) in FIG. 2 (b), the micro heater 12 and the thermopiles 13, 14 are arranged with respect to the outer shape of the base 11. There is no problem if a change occurs.

FIG. 3 shows the flow rate measurement characteristics obtained by this embodiment. As is clear from FIG. 3, the microflow sensor of the present invention can avoid saturation of the flow rate measurement output at a large flow rate as compared with the conventional microflow sensor having a pair of thermopiles, and from a small flow rate to a large flow rate. The flow rate up to the flow rate can be measured.

Next, a second embodiment of the present invention will be described with reference to the accompanying drawings. Here, in FIG. 4, (a) is a schematic plan view showing an example of the microflow sensor of the second embodiment of the present invention, and (b) is BB of FIG. 4 (a).
It is a line sectional view.

The microflow sensor shown in FIG. 4 has a diaphragm 11, a microheater 12 disposed substantially at the center of the diaphragm 11 in the air flow of the fluid to be measured, and an upstream of the microheater 12 in the air flow direction of the fluid to be measured. And a pair of paired thermopiles 15 and 16 symmetrically arranged on the downstream side and the downstream side, respectively,
The hot junction of the thermopile 15 is arranged at the same airflow position as the center of the microheater 12 in the fluid flow to be measured, and the thermopile 16 is arranged on both sides of the airflow above the microheater 12 respectively.

The thermopile 15a used in this embodiment,
All of 15b, 16a, and 16b are made of Si wiring and Al wiring to which boron ions are added, and they can be manufactured at the same time during the manufacturing process, so that additional steps are not required and the efficiency is improved. It can be manufactured well.

The thermopile 15a used in this embodiment,
The cold junction groups 15b, 16a, 16b are arranged in a thick portion serving as a sensor base body made of Si.
Since 1a is arranged in good thermal contact with the housing to which the sensor is attached, the temperature of the fluid to be measured is 1a.

On the other hand, the thermopiles 15a, 15b, 16
The hot junction groups a and 16b are arranged on the diaphragm 11 made of an oxide film having a good heat insulating property, and the micro heater 12
The amount of heat proportional to the difference between the temperature of the fluid to be measured and the temperature of the hot junction group moved to the hot junction moves to warm the hot junction group,
The temperature difference between the hot junction group and the cold junction group becomes the output of the thermopiles 15 and 16.

In the present embodiment, the distance between the hot junction group and the cold junction group of the thermopile 15 and the thermopile 16 is different, and this distance is the heat when the heat of the hot junction is conducted to the housing. Since the resistance is proportional to the resistance, the thermal resistance of the temperature sensing part of the thermopile 15 to the housing is larger than that of the temperature sensing part of the thermopile 16.

The thermosensitive portion of the thermopile 15 has a large thermal resistance with respect to the housing, and the temperature rises even with a small amount of heat at a small flow rate, so the sensitivity of small flow rate measurement is good, but the temperature easily rises. When a large amount of heat is generated at a large flow rate, the temperature-sensing section approaches the temperature of the heated measurement target fluid, and the measured output at a large flow rate is saturated.

On the other hand, the temperature-sensitive part of the thermopile 16 has a small thermal resistance with the housing, so it does not easily approach the temperature of the fluid to be measured, and the measured output of a large flow rate is difficult to saturate.
Since the temperature of the temperature sensing part does not rise easily, it is difficult to measure at a small flow rate.

By providing a mechanism for automatically or manually switching the above two sets of thermopile outputs to a small flow rate and a large flow rate, one microflow sensor can accurately measure a wide range of flow rate from a small flow rate to a large flow rate. It became possible to do it.

In the second embodiment described above, a method of changing the thermal resistance with the wiring length has been described as a method of forming different thermal temperature rise sensitivities between the two pairs of temperature sensors.
It is also possible to change the thermal resistance by changing the wiring thickness or the wiring material, or to change the heat capacity of the temperature sensing section by changing the volume or material of the temperature sensing section. For example, in the embodiment shown in FIG. 4, measures are taken to change the wiring thickness of the thermopiles 15 and 16.

In the first and second embodiments described above, each pair of temperature sensors is paired with a thermopile 13, 14, 1 as a pair of temperature sensors.
Although the embodiment adopting Nos. 5 and 16 has been described, the present invention is not limited to this embodiment, and each of the temperature sensors of each set adopts other embodiments such as a temperature measuring resistor, a thermistor, and a pyroelectric body. It is also possible.

[0054]

According to the microflow sensor of the present invention described in claim 1, two microflow sensors symmetrically arranged on the upstream side and the downstream side of the microheater arranged in the air flow of the fluid to be measured. comprising at least two pairs vs. temperature sensor comprising a temperature sensor, varies the distance from the micro-heater of the above each pair temperature sensors for each set are each the at least
Two pairs of temperature sensors are used for temperature control close to the above micro heater.
Temperature sensor, the temperature
Sensor to the amount of heat from the fluid to be measured
Temperature sensor with high sensitivity to temperature rise in each temperature sensor
It is characterized by being composed of .

According to the microflow sensor of the present invention described in claim 1, the temperature sensor close to the microheater measures a small flow rate, and the temperature sensor far from the microheater measures a large flow rate. It is possible to accurately measure a wide range of flow rate from a small flow rate to a large flow rate.

More specifically, the temperature sensor farther away from the microheater reaches the temperature sensor while the fluid to be measured is cooled by the diffusion of the fluid, so it is difficult to measure a small flow rate. On the other hand, the temperature sensor close to the micro-heater has a large temperature rise in the temperature sensor temperature sensing part,
It exceeds the temperature sensitivity range of the temperature sensor, making it difficult to measure a large flow rate.

However, by arranging both of the above-mentioned two sets of temperature sensors, it becomes possible to measure from a small flow rate to a large flow rate in a manner that complements each other.

[0058]

Further, according to the micro-flow sensor of the present invention as set forth in claim 1, and a temperature rise difference between the temperature sensor temperature sensing unit according to a distance difference between the micro-heater, each pair temperature sensors for heat from the measurement object fluid The synergistic effect with the temperature rise sensitivity difference of the temperature sensing part enables a wider range of flow rate measurement.

According to a second aspect of the present invention, there are provided two temperature sensors which are symmetrically arranged on the upstream side and the downstream side of the micro heater arranged in the air flow of the fluid to be measured. comprising at least two pairs vs. temperature sensor consisting, that the temperature rise speed of the temperature sensing portion of said each pair temperature sensors for heat from the measurement object fluid is formed at each different pair temperature sensors for each set Characterize.

According to the second aspect of the microflow sensor of the present invention, the temperature sensor having a high thermal temperature increase sensitivity measures a small flow rate, and the temperature sensor having a low thermal temperature increase sensitivity measures a large flow rate. By performing each, it is possible to accurately measure a wide range of flow rate from a small flow rate to a large flow rate.

More specifically, even if the amount of heat transferred from the fluid to be measured warmed by the micro heater is the same, if the heat temperature rise sensitivity is high, the temperature of the temperature sensor temperature sensing section is set to a relatively low flow rate. The temperature of the fluid to be measured is close to the temperature of the fluid to be measured, and the output is saturated without becoming a temperature higher than the temperature of the fluid to be measured. Since the amount of heat transfer has a monotonically increasing relationship with the flow rate of the fluid to be measured, a temperature sensor that has a low sensitivity to rise in temperature increases the flow rate at which the output saturates, and a larger flow rate can be measured. become. On the other hand, when the heat temperature rise sensitivity is high, the sensor sensitivity is generated even with a small amount of heat transfer, so that a smaller flow rate can be measured.

Therefore, by disposing both of the above-mentioned two sets of temperature sensors, it becomes possible to measure from a small flow rate to a large flow rate in a manner that complements each other.

[0064] Micro-flow sensor of the present invention described in claim 3 is the micro-flow sensor according to claim 2, wherein the at least two sets of pairs temperature sensor, the heat capacity of each pair temperature sensor temperature sensing unit are each different It is characterized in that it is formed in.

According to the third aspect of the microflow sensor of the present invention, for the same heat transfer amount, if the heat capacity is large, the heat temperature rise sensitivity becomes small, and the temperature rise in the temperature sensor temperature sensing portion becomes slow. When the heat capacity is small, the heat temperature rise sensitivity is high, and the temperature rise of the temperature sensor temperature sensitive portion is sharp.

Therefore, a large flow rate is measured by a temperature sensor having a small temperature rise in the temperature sensor temperature sensitive part and a temperature rise in the temperature sensor temperature sensing part is slow, and a large temperature rise in the temperature sensor temperature sensing part causes a sharp temperature rise in the temperature sensor. By measuring a small flow rate with a sensor, it is possible to accurately measure a wide range of flow rate from a small flow rate to a large flow rate.

A microflow sensor according to a fourth aspect of the present invention is the microflow sensor according to any one of the second to third aspects, wherein the at least two pairs of temperature sensors are temperature sensitive sensors. It is characterized in that the portions and the sensor base are formed so as to have different thermal resistances.

According to the microflow sensor of the fourth aspect of the present invention, if the thermal resistance between the temperature sensor temperature sensing portion and the sensor base is small for the same amount of heat transfer, heat is immediately transferred to the sensor base. However, since the sensor base immediately radiates heat to the housing to which the microflow sensor is attached, the heat temperature rise sensitivity becomes small, and the temperature rise in the temperature sensor temperature sensing portion becomes slow.

On the other hand, if the thermal resistance between the temperature sensor temperature sensing portion and the sensor base is large for the same amount of heat transfer, heat is not readily conducted to the sensor base, and the microflow sensor is immediately attached to the sensor base. Since the heat is not radiated to the housing, the heat temperature sensitivity is high and the temperature rise of the temperature sensor temperature sensing portion is sharp.

Therefore, a large flow rate is measured by the temperature sensor for which the temperature rise in the temperature sensor temperature sensing portion is low and the temperature rise in the temperature sensor temperature sensing portion is large, and the temperature sensor temperature sensing portion senses a sharp temperature rise. By measuring a small flow rate with a sensor, it is possible to accurately measure a wide range of flow rate from a small flow rate to a large flow rate.

A microflow sensor according to a fifth aspect of the present invention is the microflow sensor according to any one of the second to fourth aspects, wherein the at least two pairs of temperature sensors have different wiring patterns for each pair. It is characterized by being formed by.

According to the microflow sensor of the fifth aspect of the present invention, at least two pairs of temperature sensors are formed with different wiring patterns for each group, and as a result, each pair of temperature sensors of each group is heated. The distance between the sensor and the micro heater is different, or the temperature rise sensitivity of the temperature sensing part of each temperature sensor with respect to the amount of heat from the fluid to be measured is different. Since it is possible to measure each area by subdividing a wide area from a large flow rate to, it is possible to accurately measure a wide area flow rate from a small flow rate to a large flow rate.

In each of the above-mentioned microflow sensors according to the first to fifth aspects, when the temperature sensors of each set are made of the same material, they are formed and arranged at the same time during the manufacturing process. Therefore, it is possible to efficiently manufacture the device without requiring additional steps.

A microflow sensor according to a sixth aspect of the present invention is the microflow sensor according to any one of the first to fifth aspects, wherein the at least two pairs of temperature sensors are made of different materials. It is characterized by consisting of things.

According to the microflow sensor of the present invention as defined in claim 6 , at least two pairs of temperature sensors are made of different materials for each pair, and as a result,
The distance from the micro heater of each pair of temperature sensors of each set is made different, or the temperature rise sensitivity of the temperature sensing part of each pair of temperature sensors to the amount of heat from the fluid to be measured is made different, and The temperature sensor can accurately measure a wide range of flow rate from a small flow rate to a large flow rate.

[Brief description of drawings]

1A is a schematic plan view showing an example of a microflow sensor according to a first embodiment of the present invention, and FIG. 1B is a schematic side view of FIG. 1A.

FIG. 2A is a schematic plan view showing another example of the microflow sensor according to the first embodiment of the present invention, and FIG.
FIG. 3 is a sectional view taken along the line AA of FIG.

FIG. 3 is a graph showing a comparison between the output result of the conventional microflow sensor and the output result of the microflow sensor of the present invention.

4A is a schematic plan view showing an example of a microflow sensor according to a second embodiment of the present invention, and FIG. 4B is a sectional view taken along line BB of FIG. 4A.

FIG. 5 is a schematic plan view showing a conventional microflow sensor.

[Explanation of symbols]

11 diaphragm 12 Micro heater 13,14,15,16 vs. thermopile

Claims (6)

(57) [Claims] 1. At least two pairs of temperature sensors each comprising two temperature sensors symmetrically arranged on each of an upstream side and a downstream side of a micro-heater arranged in an air flow of a fluid to be measured are provided. Do not arrange each pair of temperature sensors so that the distance from the micro heater is different for each group.
Ri, said at least two sets of pairs temperature sensor, the Maikurohi
The closer to the temperature sensor the temperature sensor is,
Heat from the fluid to be measured, rather than a remote temperature sensor
The temperature rise sensitivity of each temperature sensor's temperature sensing part with respect to the amount
A microflow sensor characterized by being composed of a high temperature sensor. 2. At least two pairs of temperature sensors, each of which has two temperature sensors symmetrically arranged on the upstream side and the downstream side of the micro-heater arranged in the air flow of the fluid to be measured, are provided. micro flow sensor temperature rise sensitivity of the temperature sensing portion of each pair temperature sensors for heat from the measurement object fluid, characterized in that it is formed at each different pair temperature sensors for each set. 3. The at least two pairs of temperature sensors include:
3. The micro flow sensor according to claim 2, wherein the temperature sensors have different heat capacities from each other. 4. The at least two pairs of temperature sensors include:
Micro flow sensor according to claim 2 or 3, wherein the comprising the thermal resistance between each pair temperature sensor temperature sensing unit and the sensor substrate is different from each other so formed. 5. The at least two pairs of temperature sensors include:
Micro flow sensor according to claim 2-4, characterized in that it is formed by different wiring patterns for each set. 6. The at least two pairs of temperature sensors include:
Micro flow sensor according to any one of claims 1 to 5, characterized in that it consists of different materials for each set.