JP2019039821A - Heat flow sensor - Google Patents

Abstract

To provide a heat flow sensor having a relatively simple configuration capable of achieving at low cost.SOLUTION: The heat flow sensor is for measuring the density of heat flux emitted from the surface of a measuring object 2. The heat flow sensor comprises: a thin film 3 which is formed of a material the thermal resistance of which is well-known, and which is placed on a measuring point on the surface of the measuring object 2; a first thermocouple 4 the junction of which is disposed on one surface of the thin film 3; and a second thermocouple 5 the junction of which is disposed at a position corresponding to the first thermocouple 4 on the other surface of the thin film 3. The density of heat flux is measured on the basis of a temperature difference between both surfaces of the thin film 3 from a difference between the electromotive force of the first thermocouple 4 and the electromotive force of the second thermocouple 5.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention relate to a heat flow sensor.

  As the heat flow sensor, one that measures the heat flow using the Seebeck effect is known (see, for example, Patent Document 1). In this heat flow sensor, a flexible wiring having a zigzag (meandering) thermoelectric cone pattern in which a first conductor pattern made of constantan and a second conductor pattern made of constantan and copper are alternately connected. The plate is formed by a two-stage etching method. And the heat flow sensor is formed by winding and bonding the flexible wiring board around a thermal resistor such as a resin film.

JP 2004-37097 A

The above-mentioned conventional heat flow sensor has a tendency to be relatively complicated and expensive because it requires a complicated conductor pattern.
In view of this, a heat flow sensor is provided that can be made inexpensively with a relatively simple configuration.

  The heat flow sensor according to the embodiment is for measuring the heat flux density emitted from the surface of the measurement object, and is made of a material having a known thermal resistance and is directed to the measurement location on the surface of the measurement object. And a first thermocouple in which a junction point is disposed on one surface of the thin film, and a second in which a junction point is disposed at a position corresponding to the first thermocouple on the other surface of the thin film. The measurement is performed based on obtaining the temperature difference between the two surfaces of the thin film from the difference between the electromotive force of the first thermocouple and the electromotive force of the second thermocouple.

The longitudinal cross-sectional view which shows 1st Embodiment and shows the mode at the time of use of a heat flow sensor roughly Plan view showing schematic configuration of heat flow sensor The figure which shows typically the connection state of a 1st thermocouple and a 2nd thermocouple. The top view which shows 2nd Embodiment and shows schematic structure of a heat flow sensor

(1) First Embodiment A first embodiment will be described with reference to FIGS. 1 and 2 schematically show a configuration of a heat flow sensor 1 according to the present embodiment. As shown in FIG. 1, the heat flow sensor 1 is assigned to a measurement location on the surface of the measurement object 2 (upper surface in the drawing) and is released from the measurement location of the measurement object 2. / M ² ), that is, for measuring the amount of heat per unit area flowing during a unit time. Here, the measurement object 2 is assumed to be a heat generating component such as a coil as a component of the transformer, for example.

  As shown in FIGS. 1 and 2, the heat flow sensor 1 according to the present embodiment includes a thin film 3 made of a material having a known thermal resistance and addressed to a measurement location on the surface of the measurement object 2, and one of the thin films 3. The first thermocouple 4 in which the junction point 4a is arranged on the surface (upper surface in the figure), and the junction point at a position corresponding to the first thermocouple 4 on the other surface (lower surface in the figure) of the thin film 3 And a second thermocouple 5 on which 5a is arranged.

In this case, the thin film 3 is made of a ceramic material, for example, a mica film obtained by forming laminated mica into a sheet shape, and is formed in a circular thin plate shape having a thickness dimension of about 0.1 to 1 mm, for example. The thin film 3 has a thermal resistance of R (m ² · K / W). The thermal resistance R (m ² · K / W) of the thin film 3 can be determined by the thickness dimension d (m) of the thin film 3 ÷ the thermal conductivity λ (W / m · K) of the thin film 3.

  As shown in FIG. 3, the first thermocouple 4 has, for example, the ends of a positive electrode metal wire 4b made of chromel (registered trademark) and a negative electrode metal wire 4c made of alumel (registered trademark). It is constituted by joining by brazing or the like, and the joining point 4a is attached to the central portion (point P1) of the upper surface of the thin film 3. Similarly, the second thermocouple 5 is also configured by, for example, joining the tip portions of a positive electrode metal wire 5b made of chromel and a negative electrode metal wire 5c made of alumel by brazing or the like. The junction 5a is attached to the center (point P2) of the lower surface of the thin film 3. Note that the point P1 on the upper surface and the point P2 on the lower surface of the thin film 3 overlap each other when viewed in the plane direction, but in FIG. 3, the point P1 and the point P2 are slightly shifted for convenience.

  At this time, in the present embodiment, the first thermocouple 4 and the second thermocouple 5 are connected in series in a direction in which the mutual electromotive force is canceled. Specifically, as shown in FIG. 3, the base end of the negative electrode metal wire 4c of the first thermocouple 4 and the base end of the negative electrode metal wire 5c of the second thermocouple 5 are electrically connected. It is connected to the. An electromotive force (voltage) signal ΔV generated between the base end of the positive electrode metal wire 4b of the first thermocouple 4 and the base end of the positive electrode metal wire 5b of the second thermocouple 5 is An output signal is input to a signal processing circuit (not shown). At this time, the difference (V1−V2) between the electromotive force V1 of the first thermocouple 4 and the electromotive force V2 of the second thermocouple 5 is output as the electromotive force signal ΔV.

  Next, the operation and effect of the heat flow sensor 1 configured as described above will be described. As shown in FIG. 1, the heat flow sensor 1 is assigned to a location where the heat flux density q on the surface of the measurement object 2 is measured. Based on the difference ΔV between the electromotive force V1 of the first thermocouple 4 and the electromotive force V2 of the second thermocouple 5, the heat flux density q is measured based on obtaining the temperature difference ΔQ on both surfaces of the thin film 3. Here, assuming that the temperature of the measurement point P1 on the upper surface side of the thin film 3 of the heat flow sensor 1 is Q1 (K) and the temperature of the measurement point P2 on the lower surface side of the thin film 3 is Q2 (K), the temperature difference by the heat flow sensor 1 Δθ (= Q1−Q2) can be obtained as follows.

That is, an electromotive force V1 corresponding to the temperature Q1 at the measurement point P1 on the upper surface of the thin film 3 is generated in the first thermocouple 4, and the measurement point P2 on the lower surface of the thin film 3 is generated in the second thermocouple 5. An electromotive force V2 corresponding to the temperature Q2 is generated. The difference ΔV between the electromotive force V1 and the electromotive force V2 is a value corresponding to the temperature difference Δθ between the measurement points P1 and P2 on both surfaces of the thin film 3. As the sensor output of the heat flow sensor 1, an electromotive force signal ΔV corresponding to the temperature difference Δθ between both surfaces of the thin film 3 is output, and the heat flux density q is easily converted from the voltage value ΔV. In this case, the heat flux density q (W / m ² ) is obtained by the temperature difference Δθ (K) ÷ the thermal resistance R (m ² · K / W) of the thin film 3.

  As described above, in this embodiment, since the thermocouples 4 and 5 are used as sensor outputs, the voltage signal ΔV corresponding to the temperature difference Δθ between both surfaces of the thin film 3 is output, and the heat flux density q can be easily obtained from the voltage value ΔV. Thus, so-called direct reading of the heat flux density q is also possible. And in this embodiment, since it is the structure which provides the two thermocouples 4 and 5 on both surfaces of the thin film 2, compared with what provides a meandering pattern with two types of metals on a resin film, It can be done inexpensively.

  In particular, in the present embodiment, the first thermocouple 4 and the second thermocouple 5 are connected in series in a direction in which the mutual electromotive force is canceled. Thereby, a voltage signal corresponding to the electromotive force difference ΔV between the first thermocouple 4 and the second thermocouple 5 can be obtained as a single output signal. Compared with the case where the signal of the first thermocouple 4 and the signal of the second thermocouple 5 are handled separately, highly accurate measurement can be performed while reducing errors.

  Furthermore, in the present embodiment, a mica film as a ceramic material is employed for the thin film 3. Here, as the material of the thin film 3, an electrical insulating sheet can be used, and preferable characteristics include high heat resistance, a certain degree of thermal resistance R (relatively low thermal conductivity λ), and due to temperature fluctuations. Less change in electrical characteristics is required. By adopting a mica film for the thin film 3, it is excellent in the required characteristics as described above, and is suitable for use in a high temperature region.

(2) Second Embodiment and Other Embodiments Next, a second embodiment will be described with reference to FIG. FIG. 4 schematically shows the configuration of the heat flow sensor 11 according to the second embodiment, and this heat flow sensor 11 is different from the heat flow sensor 1 of the first embodiment in the following points. . That is, the heat flow sensor 11 includes the first thermocouple 13 on one surface (front surface) of the thin film 12 addressed to the measurement location on the surface of the measurement object, and the other surface (back surface) of the thin film 12. A second thermocouple 14 is provided corresponding to the first thermocouple 13. At this time, a plurality of sets of the first thermocouple 13 and the second thermocouple 14 are provided on both surfaces of the thin film 12.

  The thin film 12 is made of an insulating material having a known thermal resistance, and is formed in a rectangular thin plate shape. In the present embodiment, a polymer film having high heat resistance is employed as the material of the thin film 12, and specifically, a polyimide film such as “Kapton (registered trademark)” manufactured by Toray DuPont Co., Ltd. is used. Further, the thickness d of the thin film 12 is 10 μm to several tens of μm. The first thermocouple 13 and the second thermocouple 14 are, for example, a combination of chromel and alumel, as in the first and second thermocouples 4 and 5 of the first embodiment, and these metals. Lines are joined at joints 13a and 14a.

  In the present embodiment, nine measurement points P11 to P19 are set on the surface side of the thin film 12 so as to be arranged in, for example, three rows both vertically and horizontally, and the nine first thermocouples 13 are connected to the respective junction points 13a. It is provided so as to be adhered to the measurement points P11 to P19. Similarly, nine second thermocouples 14 are provided so that each junction 13a is adhered to measurement points corresponding to these nine measurement points P11 to P19 on the back surface side of the thin film 12. Thus, nine sets of the first thermocouple 13 and the second thermocouple 14 are provided on both sides of the thin film 12.

  According to the second embodiment, the heat flow sensor 11 with high measurement accuracy can be obtained with a simple configuration and at a low cost, as in the first embodiment. A plurality of first thermocouples 13 and second thermocouples 14 are provided on both surfaces of the thin film 12, so that the heat flux density distribution in a wide region to which the thin film 12 of the measurement object is addressed can be obtained. It can be obtained. Furthermore, in this embodiment, by adopting a polyimide film having excellent heat resistance as the material of the thin film 12, even when the object to be measured is a curved surface using the flexibility of the polymer film, the thin film 12 follows the curved surface. The heat flux can be measured. Of course, the thin film 12 can be made inexpensively.

  In the first embodiment described above, a mica film is used as the ceramic material for the thin film 3, but a sheet-like molded product made of silicon nitride or the like can also be used. Even when the thin film is made of a polymer film, various materials having good heat resistance and stable electrical characteristics can be employed. As the thickness dimension of the thin film, a thickness of about several μm to 1 mm can be adopted. Furthermore, the material and the combination of the two types of metal wires constituting the thermocouple can be variously changed, for example, using constantan for the negative electrode metal wire.

  In addition, the heat flow sensor is not limited to the measurement of the heat flux of the components of the transformer, but can be applied to various measurement objects. The embodiment described above is presented as an example, and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  In the drawings, 1 and 11 are heat flow sensors, 2 is an object to be measured, 3 and 12 are thin films, 4 and 13 are first thermocouples, 5 and 14 are second thermocouples, 4a, 5a, 13a and 14a are Indicates the junction point.

Claims (5)

A heat flow sensor for measuring a heat flux density emitted from a surface of a measurement object,
A thin film made of a material having a known thermal resistance and addressed to a measurement location on the surface of the measurement object;
A first thermocouple having a junction disposed on one side of the thin film;
A second thermocouple having a junction point disposed at a position corresponding to the first thermocouple on the other surface of the thin film;
A heat flow sensor that performs measurement based on obtaining a temperature difference between both surfaces of the thin film from a difference between an electromotive force of the first thermocouple and an electromotive force of the second thermocouple.   The heat flow sensor according to claim 1, wherein the first thermocouple and the second thermocouple are connected in series in a direction in which mutual electromotive force is canceled.   The heat flow sensor according to claim 1 or 2, wherein a plurality of sets of the first thermocouple and the second thermocouple are provided on both surfaces of the thin film.   The heat flow sensor according to any one of claims 1 to 3, wherein the thin film is made of a ceramic material.   The heat flow sensor according to any one of claims 1 to 3, wherein the thin film is made of a polymer film.

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