JP3348255B2 - Heat removal atmosphere detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a humidity sensor having two sensor units for detecting a flow rate and a humidity by utilizing the fact that the inductance changes in accordance with, for example, the flow rate of a fluid or the amount of steam (heat removal). And a heat capture atmosphere detection device such as a flow sensor.

[0002]

2. Description of the Related Art FIG. 4 is a view showing the structure of a conventional heat-absorbing atmosphere detecting device and the structure of a heat-sensitive resistance element used in the heat-absorbing atmosphere detecting device. FIG. FIG. 3 is a diagram showing a bridge circuit used.

As shown in FIG. 4A, two thermosensitive resistance elements 21 and 22 having the same characteristics are fixed to different stems 26 via pins 24 as lead terminals by soldering or welding. I have. The stem 26 to which the thermal resistance element 21 is fixed is provided with a metal tube cap 2 having a vent hole.
5 is covered. On the other hand, the stem 26 to which the thermal resistance element 22 is fixed is covered with a cap 25 ′ of a metal tube at a very low temperature (about −40 ° C.).

As a result, the thermal resistance element 21 is exposed to the outside air, and the thermal resistance element 22 is sealed in a dry atmosphere.

[0005] As shown in FIG.
Reference numerals 1 and 22 each include a structure in which electrodes 31 are baked on the front and back surfaces of a bulk thermal resistor 32, and a lead wire 33 is attached to the electrodes 31.

As shown in FIG. 5, two heat-sensitive resistance elements 2
Datsunetsu Atmosphere detecting apparatus having a 1 and 22, the two heat-sensitive resistance elements 21 and 22 and R _HT, R _T, respectively, R _HT and R
A Wheatstone bridge circuit having _T different bridge sides is formed. Here, the temperature-resistance characteristics and the resistance values of the two thermosensitive resistance elements 21 and 22 are equal.

[0007] The operation of the conventional heat absorbing atmosphere detecting device will be described below.

The heat-sensitive resistance elements 21 and 22 are connected to lead wires 33.
When a voltage is applied to the device, heat is generated and the temperature becomes higher than the ambient temperature.
At this time, the temperature of the heat-sensitive resistance elements 21 and 22 is determined by the power contributing to the consumption of the heat and the heat dissipation of the heat. Therefore, heat conduction of the heat-sensitive resistance element 21 due to water vapor in the atmosphere acts to increase heat dissipation.

As a result, a temperature difference is generated between the heat-sensitive resistance elements 21 and 22 in accordance with the amount of water vapor (a little amount of moisture) or the flow rate of the fluid, and the difference in resistance generated in accordance with the temperature difference is fixed resistance R detected by the _third voltage across V _OUT, it is possible to detect the flow rate of the absolute humidity and the fluid in the atmosphere.

[0010]

In the conventional heat-absorbing atmosphere detecting device, during the application of a voltage, a change in temperature, or a change in humidity, the thermal resistance of the bulk thermosensitive resistors 21 and 22 until the entire temperature becomes uniform. It takes time to balance, and the thermal resistance element 2
The resistance values of 1 and 22 tend to be unstable. Therefore, the conventional heat absorbing atmosphere detecting device has a problem that it takes a long time until the bridge balance output is stabilized, and the response is poor.

Since the surface of the bulk thermal resistor easily changes with time, it is necessary to apply a coating to the surface of the bulk thermal resistor. Therefore, there is a problem that responsiveness is further deteriorated.

It is an object of the present invention to provide a heat removal atmosphere detecting device which solves such a problem, has excellent responsiveness, is small in change with time, and can always stably detect the heat removal amount with high accuracy.

[0013]

According to the present invention, there are provided first and second metal magnetic oxide films whose magnetic permeability varies greatly with temperature and have different magnetic permeability. A primary coil commonly meandering to the metal magnetic oxide film; a first and second secondary coil meandering independently of each other to the first and second metal magnetic oxide films; A sensor unit having heating means for heating one of the first and second metal magnetic oxide films to match the initial magnetic permeability of the metal magnetic oxide film and the second metal magnetic oxide film; Means for supplying an AC excitation voltage to the primary coil , and means for detecting a difference voltage between the output voltages of the first and second secondary coils , and Heat release atmosphere detection characterized by detection as voltage Location can be obtained.

Further, there is provided a heat absorbing atmosphere detecting device, wherein the first secondary coil and the second secondary coil are differentially connected.

Further, according to the present invention, the sensor section includes first and second sensor sections, the primary coil includes first and second primary coils, and the first sensor section includes first and second primary coils. Substrate, the first metal magnetic oxide film provided on the first substrate, the first primary conductor pattern formed as the first primary coil on the first substrate, A first secondary conductor pattern formed as the first secondary coil on a first substrate, and a second sensor unit is provided on the second substrate and the second substrate. The second metal magnetic oxide film, a second primary conductor pattern formed as the second primary coil on the second substrate, and the second secondary conductor pattern on the second substrate. A second secondary conductor pattern formed as a coil; and a heating means formed on the second substrate. Composed of a heater, said first primary conductor pattern and the second primary and the conductor pattern is characterized in that it is connected in series ablative thermal atmosphere detection device can be obtained.

Further, the first metal magnetic oxide film is provided on a surface of the first substrate, and the first primary conductor pattern and the first secondary conductor pattern are provided on a back surface of the substrate. The second metal magnetic oxide film and the heater are provided on the front surface of the second substrate, and the second primary conductor pattern and the second secondary conductor pattern are provided on the back surface of the substrate. Thus, there can be obtained a heat removal atmosphere detecting device.

Further, there is provided a heat-absorbing atmosphere detecting device, wherein the first and second primary conductor patterns and the first and second secondary conductor patterns are formed in a meandering or spiral shape. Can be

Further, there is provided an apparatus for detecting a heat absorbing atmosphere, wherein the first and second substrates are formed of different substrate portions of a common substrate.

According to the present invention, the first and second metal magnetic oxide films are Mn—Zn-based metal magnetic oxide films, and the heat absorbing atmosphere detecting device and the heat absorbing atmosphere detecting device are provided. Is obtained.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a diagram showing the structure of an atmosphere sensor for a heat removal atmosphere detecting apparatus according to the present invention.

As shown in FIGS. 1A and 1B, the thin film heater 11 is formed on the surface of the alumina substrate 13 and, specifically, is formed on the surface of the alumina substrate 13 by sputtering. Is formed, and a meandering thin film pattern is formed by an etching method.
It is obtained by heat treatment in a temperature range of ° C. Further, FIG.
As shown in (C), the primary conductor pattern 17 is located on the back surface of the alumina substrate 13 and directly below the thin film heater 11.
-1 and the secondary conductor pattern 16 are deposited, and a meandering pattern is formed by an etching method. Further, a Mn—Zn-based metal magnetic oxide 12 is printed on the thin film heater 11 in a thick film and then fired at 800 ° C. to obtain the sensor unit 14.

A thick magnetic metal oxide 12 ′ is printed on a region different from the region where the metal magnetic oxide 12 is printed and on the surface of the substrate 13, and then baked at 800 ° C. The primary conductor pattern 17-2 and the secondary conductor pattern 16 'are provided on the back surface in the same manner as the above-described method for producing the conductor pattern, and the sensor unit 15 is obtained.

The primary conductor patterns 17-1 and 17
-2 are connected at one end to each other and serve as primary coils, and the secondary conductor patterns 16, 16 'serve as secondary coils.

FIG. 2 is a diagram showing a differential detection circuit used in the heat removal atmosphere detecting device.

In FIG. 2, the primary conductor pattern 17-
₁ , 17-2 are the primary coil L ₁ and the primary coil L, respectively.
_2, and the secondary conductor patterns 16 and 16 'and each secondary coil L ₃ and L _4, the secondary coil L ₃ and the secondary coil L ₄ are are differentially connected as shown in FIG. 2, secondary the difference between the inductance value of the coil L ₃ and the secondary coil L ₄ and detectable.

According to the present invention, the heater 1
1 so that the heat is removed when exposed to the atmosphere due to the heat conduction effect of the heat generated by the heater 11, and the other sensor unit 15 is not provided with a heater so that the heat is not removed even when exposed to the atmosphere. The amount of heat removal is detected by using the temperature difference between the unit 14 and the sensor unit 15. Therefore,
Providing the heater 11 only in the sensor section 14 is a necessary condition for detecting the heat removal amount by using the heat removal atmosphere detecting device of the present invention.

At this time, if the material of the metal magnetic oxide 12 used for the sensor section 14 and the material of the metal magnetic oxide 12 ′ used for the sensor section 15 have the same Curie point, 3 is heated by the heater 11, and if the temperature after heating exceeds the Curie temperature of the metal magnetic oxide 12 according to the temperature characteristics of the initial magnetic permeability shown in FIG. I will. Therefore, it is no longer possible to determine an inductance value corresponding to a change in magnetic permeability due to a change in temperature, and this device is completely meaningless. Further, since the present invention detects the amount of heat removed from the atmosphere based on the difference between the inductance values of the sensor unit 14 and the sensor unit 15, the metal magnetic oxide 12 in the state after heating is detected.
It is necessary to make the initial magnetic permeability of the metal magnetic oxide 12 ′ uniform.

In view of the above, the metal magnetic oxide 12 used in the sensor unit 15 is used by the amount corresponding to the Curie temperature of the metal magnetic oxide 12 used in the sensor unit 14 which is previously generated by the heater 11 and rises in temperature. 'And a material whose initial magnetic permeability after heating matches the magnetic permeability at room temperature of the non-heated metal magnetic oxide 12'. You have to choose.

For example, when the heating temperature is 27 to 28 ° C., as shown in FIG. 3, the magnetic material made of the material having the initial magnetic permeability temperature characteristic of the curve A is the metal magnetic oxide 12 and the initial magnetic permeability temperature of the curve B is metal magnetic magnetic body made of a material having properties
And sex oxide 12 ', if selected in this way, to supply an AC excitation voltage to the primary coil L ₁ and L _2, when a voltage is applied to the heater 11, the metal in close contact with the heater 11 magnetic oxide 12 generates heat, and the temperature of the metal magnetic oxide 12 rises. Thus, the initial permeability is increased initial permeability, as shown in FIG. 3, the initial permeability of the metal magnetic oxide 12 and a metal magnetic oxide 12 'will be the same, the secondary coil L ₃ side inductance value of the secondary coil L ₄ side is the same. In this state, the differential voltage V _OUT is balanced.

Hereinafter, a method for measuring the amount of water vapor when the heat removal atmosphere detecting apparatus of the present invention is used as an absolute humidity sensor will be described in detail. Since the sensor unit 14 generates heat,
Heat conduction by the water vapor in the atmosphere acts to increase heat dissipation. Thus the ambient temperature of the sensor portion 14 is lowered, the initial permeability of the metal magnetic oxide 12 is also reduced, the inductance value of the secondary coil L ₃ side is also reduced accordingly. On the other hand, since the sensor unit 15 does not generate heat, heat conduction by the water vapor in the air does not act, and the temperature does not change due to the water vapor in the air. Therefore, at this time, the sensor section 15 becomes the ambient temperature and is used for temperature compensation.
₃ side and a difference occurs in the inductance value of the secondary coil L ₄ side, different induced electromotive voltage is generated in the secondary coil L ₃ and the secondary coil L _4. The difference is obtained as the voltage of the differential voltage V _OUT .

As described above, the amount of water vapor is determined by the differential voltage V _OUT
Voltage can be detected.

Although not shown, the primary coils L ₁ and L ₂ and the secondary coils L ₃ and L ₄ , the heater 11 and the metal magnetic oxides 12 and 12 ′ are placed on the same surface of the substrate 13. The same effect as described above can be obtained even if the film is formed by the same method as the forming method.

The heat removal atmosphere detecting apparatus of the present invention can be used not only as an absolute humidity sensor for detecting the amount of water vapor but also as a flow sensor for detecting the flow rate of a fluid.

That is, in the case of an absolute humidity sensor, the amount of water vapor is detected by measuring a change in inductance caused by a temperature change due to water vapor. On the other hand, in the case of a flow sensor, a temperature change corresponding to a change in the flow rate of a fluid is detected. The flow rate can be detected by measuring the accompanying change in inductance.

[0036]

According to the present invention, a primary and secondary coil is used as a thermal element, using a metal magnetic oxide film which is more responsive to temperature than the temperature characteristic of resistance of a conventional thermal element. Since a pair of sensor units including the above is used, the responsiveness to a change in the heat removal atmosphere can be improved. In addition, since the thick film of the metal magnetic oxide used in the sensor portion has little change over time and high durability, it is possible to obtain a durable atmosphere detection device and an atmosphere sensor for the deprivation atmosphere detection device with good durability. .

[Brief description of the drawings]

1A is a plan view showing a structure of an atmosphere sensor of the present invention, FIG. 1B is a cross-sectional view of the atmosphere sensor of FIG. 1A, and FIG. 1C is FIG. It is a bottom view of the atmosphere sensor of FIG.

FIG. 2 is a diagram showing a differential detection circuit used in the heat removal atmosphere detecting device of the present invention.

FIG. 3 is a diagram showing a temperature characteristic of an initial magnetic permeability of a magnetic material used in the heat removal atmosphere detecting device of the present invention.

FIG. 4A is a plan view showing a structure of a conventional atmosphere sensor, and FIG. 4B is a perspective view showing a structure of a heat-sensitive resistance element used in the atmosphere sensor of FIG.

FIG. 5 is a diagram showing a bridge circuit used in a conventional heat-absorbing atmosphere detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Thin film heater 12, 12 'Metal magnetic oxide 13 Alumina substrate 14, 15 Sensor part 16, 16' Secondary coil 17-1, 17-2 Primary coil 21, 22, Thermal resistance element 23 Vent hole 24 Pin terminal 25, 25 ′ Case 26, 26 ′ stem 31 electrode 32 bulk thermal resistor 33 lead wire

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 27/72-27/90 G01N 27/00-27/24 G01N 25/00-25/72 JICST file (JOIS)

Claims (7)

(57) [Claims] 1. The magnetic permeability changes greatly depending on the temperature, and first and second metal magnetic oxide films having different magnetic permeability are respectively meandered in common with the first and second metal magnetic oxide films. Primary coil, the first and second secondary coils meandering independently of each other in the first and second metal magnetic oxide films, the first metal magnetic oxide film and the second A sensor unit having heating means for heating one of the first and second metal magnetic oxide films in order to match the initial magnetic permeability of the metal magnetic oxide film, and supplying an AC excitation voltage to the primary coil And a means for detecting a difference voltage between output voltages of the first and second secondary coils, and detecting a heat removal amount of the atmosphere of the sensor unit as the difference voltage. Thermal atmosphere detector. 2. The heat removal atmosphere detecting device according to claim 1, wherein said first secondary coil and said second secondary coil are differentially connected. . 3. The heat removal atmosphere detecting device according to claim 1, wherein said sensor section comprises first and second sensor sections, said primary coil comprises first and second primary coils, Sensor part, a first substrate, the first metal magnetic oxide film provided on the first substrate, the first formed as the first primary coil on the first substrate A primary conductor pattern, a first secondary conductor pattern formed as the first secondary coil on the first substrate, the second sensor portion, the second substrate, the A second metal magnetic oxide film provided on a second substrate, a second primary conductor pattern formed as the second primary coil on the second substrate, A second secondary conductor pattern formed as the second secondary coil,
A heat sink formed on the second substrate as the heating means, wherein the first primary conductor pattern and the second primary conductor pattern are connected in series. Atmosphere detector. 4. The heat removal atmosphere detecting device according to claim 3, wherein said first metal magnetic oxide film is provided on a surface of said first substrate, and said first primary conductor pattern and said first metal oxide film are provided on said first substrate. A second conductor pattern is provided on a back surface of the substrate, the second metal magnetic oxide film and the heater are provided on a front surface of the second substrate, and the second primary conductor pattern and the second secondary conductor are provided. A heat-absorbing atmosphere detecting device, wherein a pattern is provided on a back surface of the substrate. 5. The heat removal atmosphere detecting device according to claim 3, wherein the first and second primary conductor patterns are provided.
A heat release atmosphere detecting device, wherein the first and second secondary conductor pattern are formed in a meandering or spiral shape. 6. The heat removal atmosphere detecting apparatus according to claim 3, wherein the first and second substrates are formed of different substrate portions of a common substrate. Heat capture atmosphere detector. 7. The heat-absorbing atmosphere detecting device according to claim 1, wherein the first and second metal magnetic oxide films are Mn—Zn-based metal magnetic oxide films. A heat removal atmosphere detection device characterized by the above-mentioned.