JP6981042B2 - Wireless temperature sensor - Google Patents

Description

The present invention relates to a radio temperature sensor that detects the temperature of a conductor.

The device described in Patent Document 1 is known as a device for measuring the temperature of a conductor. In the apparatus described in Patent Document 1, one end of an optical fiber, which is a temperature detector, is connected to a metal to be measured for temperature, and the other end of the optical fiber is connected to a temperature calculation unit.

Japanese Unexamined Patent Publication No. 2008-45971

When it is necessary to wire-connect the conductor to be measured for temperature (hereinafter referred to as the conductor to be measured) and the processing circuit for performing temperature calculation processing by an optical fiber or an electric wire, the work of temperature measurement is troublesome.

When the conductor to be measured moves, if it is necessary to make a wired connection, the connection work may be more troublesome. In addition, when the conductor to be measured is in a high temperature environment in which a processing circuit for performing temperature calculation processing cannot be arranged, the wired connection between the conductor to be measured and the processing circuit becomes a particularly troublesome work.

Therefore, it is conceivable to wirelessly connect the wireless temperature sensor attached to the conductor to be measured and the processing circuit that performs the temperature calculation process, and transmit a signal indicating the temperature detected by the wireless temperature sensor from the antenna.

In order to operate this antenna, the radio temperature sensor needs a ground having a size corresponding to the frequency. The larger the wireless temperature sensor including the ground, the larger the heat capacity of the wireless temperature sensor, so that a difference is likely to occur between the temperature of the wireless temperature sensor and the temperature of the conductor to be measured. As a result, the difference between the temperature detected by the wireless temperature sensor and the temperature of the conductor to be measured, that is, the temperature measurement error may increase.

The present invention has been made based on this circumstance, and an object of the present invention is to provide a wireless temperature sensor having a small temperature measurement error.

The above object is achieved by a combination of the features described in the independent claims, and the subclaims provide for further advantageous embodiments of the invention. The reference numerals in parentheses described in the claims indicate, as one embodiment, the correspondence with the specific means described in the embodiments described later, and do not limit the technical scope of the present invention. ..

The first radio temperature sensor and the second radio temperature sensor for achieving the above object are attached to the measurement target conductor (2), which is the target conductor for measuring the temperature, and detect the temperature of the measurement target conductor. A wireless temperature sensor that wirelessly transmits a signal indicating the detected temperature.
A temperature detection element (12) that detects the temperature, and
An antenna (11, 511) that transmits a signal indicating the temperature detected by the temperature detection element, and
With grounds (13, 213, 313)
The gland is exposed so as to be in contact with the conductor to be measured on the surface attached to the conductor to be measured.

In the wireless temperature sensor of the present invention, the ground is exposed on the surface attached to the conductor to be measured, and the ground comes into contact with the conductor to be measured at the time of temperature measurement, so that the conductor to be measured functions as a ground. Therefore, since the ground provided by the wireless temperature sensor can be reduced, the wireless temperature sensor can be miniaturized. As the wireless temperature sensor becomes smaller, the heat capacity of the wireless temperature sensor becomes smaller.

Therefore, even when the temperature of the conductor to be measured changes, the temperature of the temperature detecting element tends to change accordingly, so that the temperature difference between the temperature detecting element and the conductor to be measured becomes small. Therefore, the temperature measurement error becomes small.

Further, the first wireless temperature sensor, Ri-free linear temperature sensor der you measure the temperature of the measurement target conductor shaped hole on a surface wireless temperature sensor is mounted (21) is formed,
The gland has a convex portion (213c) that fits into the hole of the conductor to be measured and is in contact with a part of the conductor to be measured.

By doing so, in addition to making it difficult for the position of the wireless temperature sensor to shift during temperature measurement, the certainty of electrical contact between the ground and the conductor to be measured is also improved.

In the second wireless temperature sensor, the temperature detection element comprises exposed surfaces (12a, 12b) in contact with air.
The second radio temperature sensor includes a cover (315, 415, 515) facing the exposed surface of the temperature detection element.
The first radio temperature sensor also preferably comprises the exposed surface and cover.

By providing a cover facing the exposed surface, the temperature detected by the temperature detection element is less affected by the air around the sensor, and as a result, the temperature detected by the temperature detection element and the actual temperature of the conductor to be measured are set. The difference becomes smaller.

In the second radio temperature sensor, the cover (315) is made of a conductor and is in contact with the ground.
The cover of the first radio temperature sensor is also preferably made of a conductor and is in contact with the ground.

In this way , the cover also functions as a ground, so that the size of the ground can be made smaller. Therefore, the wireless temperature sensor can be further miniaturized.

Preferably, the antenna is made of a material that has a lower thermal conductivity than the ground.

In this way, the heat of the antenna is less likely to be transferred to the temperature detecting element as compared with the case where the antenna is made of a material having the same thermal conductivity as the ground. Therefore, it is possible to prevent the temperature detected by the temperature detecting element from being affected by the temperature of the antenna.

In the first radio temperature sensor, preferably the antenna (511) is housed in a cover.

By doing so, it is possible to prevent the antenna temperature from fluctuating due to the influence of the atmospheric temperature. As a result, the temperature detected by the temperature detecting element is also less affected by the ambient temperature, so that the difference between the temperature detected by the temperature detecting element and the actual temperature of the conductor to be measured can be further reduced.

It is an external perspective view of the radio temperature sensor 10 of 1st Embodiment. FIG. 2 is a sectional view taken along line II-II of FIG. It is sectional drawing of the radio temperature sensor 210 of 2nd Embodiment. FIG. 3 is an external perspective view of the wireless temperature sensor 310 of the third embodiment. It is sectional drawing of the radio temperature sensor 410 of 4th Embodiment. It is sectional drawing of the radio temperature sensor 510 of 5th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of the radio temperature sensor 10 according to the first embodiment of the present invention. In FIG. 1, the wireless temperature sensor 10 is placed on the upper surface of the conductor 2 to be measured. The conductor 2 to be measured can be various substances as long as it is a conductor. The conductor 2 to be measured is made of metal, for example. In the following, it will be described that the conductor 2 to be measured is a radiator made of aluminum and moves in a furnace at about 600 degrees for aluminum brazing. The inside of the furnace is in a state where hot air is blown in order to bring the brazed member to a desired temperature.

The wireless temperature sensor 10 has a configuration in which an antenna 11, a SAW device 12 which is a temperature detection element, and a ground 13 are fixed to a fixed plate 14. The SAW device 12 and the antenna 11 are fixed to one surface of the fixing plate 14, and the ground 13 is provided on the other surface of the fixing plate 14. In the following, the surface of the fixing plate 14 on the side where the SAW device 12 and the antenna 11 are fixed is the upper surface, and the surface on the side where the ground 13 is provided is the lower surface.

The antenna 11 transmits and receives radio waves having a predetermined frequency. The frequency is 920 MHz here. Further, the antenna 11 of this embodiment is a monopole antenna. In the case of a monopole antenna that transmits and receives a wavelength of a radio wave of 920 MHz, the antenna length is about 8 cm, assuming that the antenna length is 4 / λ. Note that radio waves having a frequency other than the 920 MHz band, such as 2.4 GHz, may be used.

A radio wave is transmitted to the radio temperature sensor 10 from a transmitter / receiver installed outside the furnace, and the antenna 11 receives the radio wave. The antenna 11 is made of a conductor, for example, aluminum or stainless steel.

FIG. 2 is a sectional view taken along line II-II of FIG. As shown in FIG. 2, the base end of the antenna 11 is connected to the wiring 15 provided on the fixing plate 14. One end of the wiring 15 is connected to the SAW device 12. That is, the antenna 11 is connected to the SAW device 12 via the wiring 15.

The SAW device 12 has a known configuration in which a comb-shaped electrode is formed on a piezoelectric substrate, and a radio wave received by the antenna 11 is converted into a surface acoustic wave by the comb-shaped electrode. When the reflected wave of this surface acoustic wave is transmitted to the comb-shaped electrode, the surface acoustic wave is converted into an electric signal. This electric signal is transmitted to the antenna 11 and radiated as a radio wave from the antenna 11. The radio wave radiated from the antenna 11 is received by a transceiver installed outside the furnace. The transmitter / receiver is connected to the processing circuit.

The processing circuit measures the time difference between transmitting the radio wave to the radio temperature sensor 10 and receiving the radio wave from the radio temperature sensor 10. Since this time difference changes depending on the temperature of the SAW device 12, the temperature of the SAW device 12 can be calculated from this time difference.

Strictly speaking, this temperature is the temperature of the SAW device 12. However, if the wireless temperature sensor 10 is placed on the measurement target conductor 2 and the temperature does not change for a certain period of time, the temperature of the SAW device 12 and the temperature of the measurement target conductor 2 become the same. Become. Therefore, the temperature of the SAW device 12, that is, the temperature detected by the wireless temperature sensor 10 is defined as the temperature of the conductor 2 to be measured.

The ground 13 is formed on the lower surface of the fixing plate 14. An example of the material of the ground 13 is copper. The ground 13 includes an upper convex portion 13a extending in the thickness direction of the fixed plate 14, and the tip of the upper convex portion 13a is exposed on the upper surface of the fixed plate 14. The tip of the upper convex portion 13a is connected to the SAW device 12.

In the present embodiment, the wireless temperature sensor 10 is placed on the upper surface of the conductor 2 to be measured. In this state, the lower surface 13b of the ground 13 becomes a mounting surface to be attached to the conductor 2 to be measured in the wireless temperature sensor 10. Since the entire lower surface 13b of the ground 13 is a mounting surface, the lower surface 13b of the ground 13 is exposed to this mounting surface.

When the wireless temperature sensor 10 is placed on the upper surface of the conductor 2 to be measured, the lower surface 13b of the ground 13 comes into contact with the upper surface of the conductor 2 to be measured. In FIG. 1, for convenience of illustration, the shape of the conductor 2 to be measured is shown as a rectangular parallelepiped, so that the upper surface of the conductor 2 to be measured is a flat surface. However, when the conductor 2 to be measured is a radiator, the upper surface is a space except for the portion where the end face of the fin exists. Therefore, only a part of the ground 13 is in electrical contact with the conductor 2 to be measured. Like the radiator, the shape of the conductor 2 to be measured may be a shape that allows a part of the ground 13 to come into contact with the conductor 2.

The fixing plate 14 is made of ceramic because it needs to be an insulator and a material that does not deform in the furnace. The fixing plate 14 of the first embodiment has a circular planar shape.

Since the ground 13 is in electrical contact with the conductor 2 to be measured, the conductor 2 to be measured also functions as a ground. If the antenna 11 is to be operated with sufficient performance only by the ground 13, the size of the ground 13 needs ^{to be the size of π (4 / λ) 2} , that is, about 200 cm ^2. However, in the present embodiment, since the conductor 2 to be measured also functions as a ground, the size of the ground 13 ^{can be 2 cm 2} or less.

[Summary of the first embodiment]
In the state where the wireless temperature sensor 10 of the first embodiment is placed on the measurement target conductor 2, the lower surface 13b of the ground 13 comes into contact with the measurement target conductor 2, so that the measurement target conductor 2 also functions as a ground.

Therefore, if the antenna 11 is to be operated with sufficient performance only by the ground 13, the size of the ground 13 can be reduced ^{to 2 cm 2 or less, where the size of the ground 13 needs to be about 200 cm 2.} If the ground 13 becomes smaller, the wireless temperature sensor 10 can be made smaller. Then, as the wireless temperature sensor 10 becomes smaller, the heat capacity of the wireless temperature sensor 10 becomes smaller.

Therefore, even when the temperature of the conductor 2 to be measured changes, the temperature of the SAW device 12 tends to change accordingly, so that the temperature difference between the SAW device 12 and the conductor 2 to be measured becomes small. Therefore, the temperature measurement error becomes small.

<Second Embodiment>
Next, the second embodiment will be described. In the following description of the second embodiment, the element having the same number as the code used so far is the same as the element having the same code in the previous embodiments, unless otherwise specified. Further, when only a part of the configuration is described, the embodiment described above can be applied to the other parts of the configuration.

FIG. 3 shows a cross-sectional view of the radio temperature sensor 210 of the second embodiment. The appearance of the wireless temperature sensor 210 when mounted on the conductor 2 to be measured is the same as that in FIG. The cross-sectional view shown in FIG. 3 is a cross-sectional view obtained by cutting the radio temperature sensor 210 in the same cross section as in FIG.

The portion of the wireless temperature sensor 210 of the second embodiment different from that of the wireless temperature sensor 10 of the first embodiment is the shape of the ground 213. The ground 213 includes an upper convex portion 213a, a lower convex portion 213b, and a flat plate portion 213c. The flat plate portion 213c is a flat plate-shaped portion joined to the lower surface of the fixed plate 14. The upper convex portion 213a has the same shape as the upper convex portion 13a of the first embodiment. The downward convex portion 213b is a portion protruding from the flat plate portion 213c. The upper convex portion 213a, the lower convex portion 213b, and the flat plate portion 213c may be configured as separate members as long as they are electrically connected to each other, or may be made of different materials from each other when they are used as separate members. ..

The number of downward convex portions 213b is not particularly limited. Although FIG. 3 shows two downward convex portions 213b, the number of downward convex portions 213b may be one or three or more.

The upper surface of the conductor 2 to be measured is a surface on which the wireless temperature sensor 210 is attached, and a hole 21 is formed on the upper surface thereof. The hole 21 means a space between fins when the conductor 2 to be measured is a radiator. It should be noted that the radiator has a large number of spaces because it is divided into fins. That is, the radiator has a large number of holes 21. However, for convenience of illustration, only the number corresponding to the downward convex portion 213b of the ground 213 is shown as the hole portion 21 of the conductor 2 to be measured. Of course, the conductor 2 to be measured may actually have a number of holes 21 corresponding to the downward convex portions 213b of the ground 213.

The lower convex portion 213b of the ground 213 is fitted in the hole portion 21 of the conductor 2 to be measured. Further, in this state, the downward convex portion 213b is in contact with the wall surface of the hole portion 21. That is, the downward convex portion 213b is in contact with the member of the conductor 2 to be measured.

In the radio temperature sensor 210 of the second embodiment, the ground 213 includes a downward convex portion 213b, and the downward convex portion 213b fits into the hole portion 21 of the conductor 2 to be measured. Therefore, even if the wireless temperature sensor 210 may move if the wireless temperature sensor 210 is simply placed on the conductor 2 to be measured, such as when hot air is blowing in the furnace, the wireless temperature sensor 210 may move. Can be suppressed from moving.

Further, since the lower convex portion 213b of the ground 213 is in contact with the wall surface of the hole portion 21, the certainty of the electrical contact between the ground 213 and the conductor 2 to be measured is also improved.

<Third Embodiment>
FIG. 4 shows the radio temperature sensor 310 of the third embodiment. The wireless temperature sensor 310 includes the same antenna 11 and SAW device 12 as in the first embodiment. The plane shape of the ground 313 is a quadrangular shape unlike the ground 13 of the first embodiment. The fixed plate 314 also has a rectangular parallelepiped shape, which is different in shape from the fixed plate 14 of the first embodiment.

The ground 313 and the fixing plate 314 have the same materials and functions as the ground 13 and the fixing plate 14 of the first embodiment except that the shapes are different. The upper surface 12a and the side surface 12b of the SAW device 12 are exposed exposed surfaces and are in contact with air.

The radio temperature sensor 310 of the third embodiment includes a cover 315. The cover 315 is made of conductor metal. The material of the cover 315 can be, for example, the same material as the antenna 11.

The cover 315 includes a roof portion 315a and a pair of leg portions 315b. The roof portion 315a has a rectangular plate-like shape, and leg portions 315b are connected to both ends in the longitudinal direction. The longitudinal direction of the roof portion 315a is the y-axis direction of FIG.

The leg portion 315b also has a rectangular plate shape and extends in the direction perpendicular to the roof portion 315a. The end of the leg portion 315b on the side opposite to the side connected to the roof portion 315a is inserted into the measurement target conductor 2 and electrically contacts the measurement target conductor 2.

In the third embodiment, the length of the roof portion 315a and the leg portion 315b in the x-axis direction is slightly shorter than the length of the SAW device 12 in the x-axis direction.

The roof portion 315a faces the upper surface 12a of the SAW device 12 in a non-contact state. Further, the leg portion 315b faces the side surface 12b of the SAW device 12 in a non-contact state.

Since the radio temperature sensor 310 of the third embodiment includes the cover 315, the hot air in the furnace is blocked by the cover 315 and is unlikely to directly hit the SAW device 12. As a result, it is possible to prevent the temperature detected by the SAW device 12 from being affected by the temperature of the air in the furnace and deviating from the temperature of the conductor 2 to be measured. Therefore, the difference between the temperature detected by the SAW device 12 and the actual temperature of the conductor 2 to be measured becomes small.

In addition, since the cover 315 is made of a conductor metal, it has good thermal conductivity. Therefore, the temperature of the cover 315 tends to be the same as that of the conductor 2 to be measured. Since the cover 315 faces the upper surface 12a and the two side surfaces 12b of the SAW device 12, the heat of the conductor 2 to be measured is easily transferred to the SAW device 12 through the cover 315. Also in this respect, the difference between the temperature detected by the SAW device 12 and the actual temperature of the conductor 2 to be measured becomes small.

Further, since the cover 315 is made of a conductor and is inserted into the measurement target conductor 2 and is in electrical contact with the measurement target conductor 2, the cover 315 also functions as a ground together with the measurement target conductor 2. Therefore, the ground 313 can be made smaller. This also reduces the difference between the temperature detected by the SAW device 12 and the actual temperature of the conductor 2 to be measured.

<Fourth Embodiment>
FIG. 5 shows the radio temperature sensor 410 of the fourth embodiment. The wireless temperature sensor 410 has a configuration in which a cover 415 is added to the wireless temperature sensor 10 of the first embodiment. The cover 415 has a shape that covers all the upper surface 12a and the four side surfaces 12b of the SAW device 12.

The cover 415 of the fourth embodiment is intended to prevent the temperature detected by the SAW device 12 from being affected by the ambient air temperature. Therefore, it is preferable to use a material having a low thermal conductivity. For example, it is preferably made of a material having a lower thermal conductivity than the antenna 11 and the ground 13. The cover 415 is made of, for example, ceramic.

Further, the cover 415 is placed on the upper surface of the fixing plate 14 in order to prevent the temperature detected by the SAW device 12 from being affected by the ambient air temperature, and forms a closed space together with the fixing plate 14. do. The SAW device 12 is housed in this space. Even in this state, the heat from the conductor 2 to be measured is transferred to the SAW device 12 via the ground 13.

In the fourth embodiment, the cover 415 made of a material having a low thermal conductivity covers all the exposed surfaces 12a and 12b of the SAW device 12. As a result, the temperature detected by the SAW device 12 is less likely to be affected by the ambient air temperature. Therefore, even in the fourth embodiment, the difference between the temperature detected by the SAW device 12 and the actual temperature of the conductor 2 to be measured becomes small.

<Fifth Embodiment>
FIG. 6 shows the radio temperature sensor 510 of the fifth embodiment. The radio temperature sensor 510 includes a patch antenna 511 instead of the antenna 11 of the first embodiment. It also includes a cover 515.

The operating frequency of the patch antenna 511 is the same as that of the antenna 11 of the first embodiment. The end of the patch antenna 511 is connected to the wiring 15. If the patch antenna 511 has the same operating frequency, it is easy to shorten the antenna length as compared with the monopole antenna.

The cover 515 is placed on the upper surface of the fixing plate 14 and forms a closed space together with the fixing plate 14. The SAW device 12 is housed in this space. Therefore, the cover 515 covers all the upper surface 12a and the four side surfaces 12b of the SAW device 12. The patch antenna 511 is also housed in the cover 515. The patch antenna 511 is arranged so as to be in contact with the inner surface of the cover 515 and to face the SAW device 12.

Like the cover 415 of the fourth embodiment, the cover 515 is preferably made of a material having a low thermal conductivity. For example, it is preferably made of a material having a lower thermal conductivity than the antenna 11 and the ground 13. The cover 515 is made of, for example, ceramic.

Also in the fifth embodiment, the upper surface 12a and the side surface 12b, which are the exposed surfaces of the SAW device 12, are all covered by the cover 515 made of a material having a low thermal conductivity. Therefore, the same effect as that of the fourth embodiment can be obtained.

In addition, in the fifth embodiment, the patch antenna 511 is also housed in the cover 515. Therefore, it is possible to prevent the temperature of the patch antenna 511 from fluctuating due to the influence of the atmospheric temperature. As a result, the temperature detected by the SAW device 12 located near the patch antenna 511 is also less affected by the ambient temperature. Therefore, the difference between the temperature detected by the SAW device 12 and the actual temperature of the conductor 2 to be measured can be made smaller.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the following modifications are also included in the technical scope of the present invention. Various changes can be made within the range that does not deviate.

<Modification 1>
The material of the antennas 11 and 511 may be a material having a lower thermal conductivity than the grounds 13, 213 and 313. In this way, the heat of the antennas 11 and 511 is less likely to be transferred to the SAW device 12 as compared with the case where the antennas 11 and 511 are made of a material having the same thermal conductivity as the grounds 13, 213 and 313. Therefore, it is suppressed that the temperature detected by the SAW device 12 is affected by the temperature of the antennas 11 and 511.

<Modification 2>
In the fifth embodiment, an antenna other than the Apache antenna, such as a monopole antenna, may be used instead of the patch antenna 511.

<Modification 3>
In the fifth embodiment, the patch antenna 511 may be arranged on the upper surface of the fixing plate 14.

<Modification example 4>
The cover 315, which is conductive and is connected to the measurement target conductor 2 provided in the third embodiment, may be capable of accommodating the antenna 11. In order to do so, the size of the cover 315 may be increased, or in addition to this, the antenna 11 may be a bent antenna or a patch antenna. good.

2: Conductor to be measured 10: Radio temperature sensor 11: Antenna 12: SAW device 12a: Top surface 12b: Side surface 13: Ground 13a: Top convex part 13b: Bottom surface 14: Fixed plate 15: Wiring 21: Hole part 210: Radio temperature sensor 213: Ground 213a: Upper convex part 213b: Lower convex part 213c: Flat plate part 310: Radio temperature sensor 313: Ground 314: Fixed plate 315: Cover 315: Cover 315a: Roof part 315b: Leg part 410: Wireless temperature sensor 415: Cover 510: Wireless temperature sensor 511: Patch antenna 515: Cover

Claims (6)

A wireless temperature sensor attached to a measurement target conductor (2), which is a measurement target conductor, detects the temperature of the measurement target conductor, and wirelessly transmits a signal indicating the detected temperature.
A temperature detection element (12) that detects the temperature, and
An antenna (11, 511) that transmits a signal indicating the temperature detected by the temperature detection element, and
With grounds (13, 213, 313)
The gland is exposed on the surface attached to the conductor to be measured so as to be in contact with the conductor to be measured .
It is a wireless temperature sensor that measures the temperature of the conductor to be measured in a shape in which a hole (21) is formed in a surface to which the wireless temperature sensor is attached.
The ground is a radio temperature sensor having a convex portion (213b) that fits into a hole of the conductor to be measured and is in contact with a part of the conductor to be measured. The temperature detecting element includes exposed surfaces (12a, 12b) that come into contact with air.
The wireless temperature sensor according to claim 1, wherein the wireless temperature sensor includes a cover (315, 415, 515) facing the exposed surface of the temperature detection element. The wireless temperature sensor according to claim 2 , wherein the cover (315) is made of a conductor and is in contact with the ground. A wireless temperature sensor attached to a measurement target conductor (2), which is a measurement target conductor, detects the temperature of the measurement target conductor, and wirelessly transmits a signal indicating the detected temperature.
A temperature detection element (12) that detects the temperature, and
An antenna (11, 511) that transmits a signal indicating the temperature detected by the temperature detection element, and
With grounds (13, 213, 313)
The gland is exposed on the surface attached to the conductor to be measured so as to be in contact with the conductor to be measured .
The temperature detecting element includes exposed surfaces (12a, 12b) that come into contact with air.
The wireless temperature sensor includes a cover (315) facing the exposed surface of the temperature detection element.
The cover is a radio temperature sensor made of a conductor and in contact with the ground. The radio temperature sensor according to any one of claims 1 to 4, wherein the antenna is made of a material having a thermal conductivity lower than that of the ground. The wireless temperature sensor according to claim 2 , wherein the antenna (511) is housed in the cover.

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