JP2023062587A - wireless communication system - Google Patents

Abstract

To provide a wireless communication system that can be widely applied independently of an inner structure of a rotary machine while suppressing reduction in electric field intensity.SOLUTION: In a wireless communication system, a motor 50 comprises: a wireless sensor unit 5 provided in a metal housing 51; a first passive relay 60 provided between the interior and the exterior of the metal housing 51; and a second passive relay 80 provided in the metal housing 51 to relay an electric wave transmitted from the wireless sensor unit 5 to the first passive relay 60. A reception antenna 85 of the second passive relay 80 is configured by a conductor provided on an antenna substrate 84a. A transmission antenna 81 of the second passive relay 80 is a directional antenna configured by a conductor provided on an antenna substrate 84b and having a single directivity in a horizontal plane of the concerned antenna substrate 84b. A reception antenna 65 of the first passive relay 60 is arranged on an extension plane of the horizontal plane of the antenna substrate 84b.SELECTED DRAWING: Figure 12

Description

The present invention relates to wireless communication systems.

Wireless sensor bearings have been proposed that incorporate wireless sensor units that include various sensors such as vibration sensors, acceleration sensors, rotation sensors, temperature sensors, etc., and that output data acquired by the various sensors via wireless communication (see, for example, patent documents 1). As a technology for transmitting the data measured by the wireless sensor unit to the outside of a rotary machine to which such a bearing with a wireless sensor is applied, a non-powered repeater is installed to relay radio waves inside and outside the metal housing of the rotary machine. A communication system has been disclosed (eg, Patent Document 2).

JP 2018-66433 A WO2020/209206

In wireless communication systems using parasitic repeaters, it is necessary to suppress propagation loss of radio waves in order to maintain high field strength. In the prior art described above, the terminals of the parasitic repeater inserted through the metal housing of the rotating machine and the receiving antenna are connected with a coaxial cable, and the receiving antenna of the parasitic repeater faces the transmitting antenna of the wireless sensor unit. By using the near-field electromagnetic coupling between the transmitting antenna of the wireless sensor unit and the receiving antenna of the parasitic repeater, the effect of suppressing the propagation loss of the radio waves emitted from the wireless sensor unit is enhanced. ing. Alternatively, a second parasitic repeater that changes the transmission direction of radio waves and relays them is provided between a first parasitic repeater that relays radio waves inside and outside the metal housing of the rotating machine and the wireless sensor unit. The terminal part of the first parasitic repeater inserted through the metal housing of the machine and the receiving antenna are connected with a coaxial cable, and the receiving antenna of the first parasitic repeater is used for transmission of the second parasitic repeater. The second parasitic repeater is arranged opposite to the antenna and utilizes the near-field electromagnetic coupling effect generated between the transmitting antenna of the second parasitic repeater and the receiving antenna of the first parasitic repeater. It enhances the effect of suppressing the propagation loss of radio waves emitted from the repeater. When applying the wireless communication system of this aspect to a rotary machine such as a motor or a speed reducer, the routing of the coaxial cable inside the metal housing and the placement of the second parasitic repeater are It may be limited by multipath fading phenomena due to structures, reflections, etc.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wireless communication system capable of reducing the size of a rotating machine in the direction of its rotation axis while suppressing a decrease in electric field strength. .

In order to achieve the above object, a wireless communication system according to an aspect of the present invention provides a wireless sensor unit provided inside a metal housing, and a first sensor provided between the inside and the outside of the metal housing. 1 parasitic repeater; and a second parasitic repeater provided inside the metal housing for relaying radio waves transmitted from the wireless sensor unit to the first parasitic repeater. , the receiving antenna of the second parasitic repeater is composed of a conductor provided on a first substrate, and the transmitting antenna of the second parasitic repeater is provided on a second substrate different from the first substrate a directional antenna having unidirectionality in the horizontal plane of the second substrate, wherein the receiving antenna of the first parasitic repeater is an extension plane of the horizontal plane of the second substrate. placed above.

According to the above configuration, it is possible to obtain a wireless communication system that can be widely applied regardless of the internal structure of the rotating machine while suppressing a decrease in electric field strength.

As a preferred aspect of the wireless communication system, it is preferable that the transmission antenna of the second parasitic repeater is composed of a plurality of layers of conductors provided on the second substrate.

As a preferred aspect of the wireless communication system, the transmission antenna of the second parasitic repeater is preferably a log-periodic antenna.

As a preferred aspect of the wireless communication system, the transmitting antenna of the second parasitic repeater is preferably a Huygens source antenna.

As a desirable aspect of the wireless communication system, the transmission antenna of the wireless sensor is composed of a conductor provided on a substrate, and the first substrate is arranged substantially parallel to the substrate provided with the transmission antenna of the wireless sensor unit. preferably.

ADVANTAGE OF THE INVENTION According to this invention, the radio|wireless communications system which can make the rotation-axis direction size compact of a rotary machine is obtained, suppressing the fall of an electric field strength.

FIG. 1 is a perspective view of a bearing with wireless sensor. FIG. 2 is an exploded perspective view of the bearing with wireless sensor. FIG. 3 is a cross-sectional view of a portion of the wireless sensor-equipped bearing including a power generating portion and a convex portion. FIG. 4 is a cross-sectional view of a portion of the wireless sensor-equipped bearing including a power generating portion and a recess. FIG. 5 is a cross-sectional view of a portion of the bearing with wireless sensor including the sensor substrate. FIG. 6 is an explanatory diagram for explaining the relationship between the voltage of the electromotive force and the time in the bearing with wireless sensor. FIG. 7 is a plan view of the wireless sensor unit. FIG. 8 is a perspective view of the cover. FIG. 9 is a diagram showing an example of the internal configuration of a motor having a bearing with a wireless sensor. FIG. 10 is a diagram illustrating an application example of a wireless communication system according to a first comparative example. FIG. 11 is a diagram illustrating an application example of a wireless communication system according to a second comparative example. FIG. 12 is a diagram showing a specific example of a motor to which the wireless communication system according to the embodiment is applied. FIG. 13 is a diagram showing the structure of the antenna substrate on which the receiving antenna of the second parasitic repeater is provided. FIG. 14A is a diagram showing the structure of an antenna substrate on which a transmitting antenna of a second parasitic repeater is provided. FIG. 14B is a diagram showing conductors of the first layer of the antenna substrate on which the transmitting antenna of the second parasitic repeater is provided. FIG. 14C is a diagram showing conductors on the second layer of the antenna substrate on which the transmitting antenna of the second parasitic repeater is provided. FIG. 15 is a schematic structural diagram of a second parasitic repeater according to the embodiment. FIG. 16 is a diagram illustrating an application example of a wireless communication system according to a modification of the embodiment;

EMBODIMENT OF THE INVENTION Hereinafter, it demonstrates in detail, referring drawings for the form (henceforth embodiment) for implementing invention. In addition, the present invention is not limited by the following embodiments. In addition, components in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those that fall within a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be combined as appropriate.

First, a bearing with a wireless sensor will be described as an example to which the wireless sensor according to the present embodiment is applied.

FIG. 1 is a perspective view of a bearing with wireless sensor. FIG. 2 is an exploded perspective view of the bearing with wireless sensor. FIG. 3 is a cross-sectional view of a portion of the wireless sensor-equipped bearing including a power generating portion and a convex portion. FIG. 4 is a cross-sectional view of a portion of the wireless sensor-equipped bearing including a power generating portion and a recess. FIG. 5 is a cross-sectional view of a portion of the bearing with wireless sensor including the sensor substrate. The bearing 1 with wireless sensor shown in FIG. 1 has a wireless sensor unit 5, a tone ring 30, and a bearing main body 20, as shown in FIG.

As shown in FIGS. 3 to 5, the bearing body 20 is a rolling bearing having an outer ring 21, an inner ring 22, and rolling elements 23. As shown in FIGS. The outer ring 21 and the inner ring 22 relatively rotate around the rotation axis Ax (see FIG. 1). In the following description, the inner ring 22 is assumed to be a rotating ring.

The cover 10 has an annular top plate 12 and a cylindrical side plate 11 connected around the top plate 12 . The cover 10 is made of a magnetic material such as silicon steel plate, carbon steel (JIS SS400 or S45C), martensitic stainless (JIS SUS420) or ferritic stainless (JIS SUS430).

As shown in FIG. 2 , in the wireless sensor unit 5 , a plurality of power generation sections 3 and a substrate 40 are attached to one surface 12A of the top plate 12 . One surface 12A is a surface facing the bearing main body 20 . The board 40 has a power supply board 41 and a sensor board 42 .

For example, as shown in FIGS. 1 and 2 , the power generation unit 3 is fixed to the top plate 12 by fastening bolts 19</b>A made of a non-magnetic material such as brass to female screw holes drilled in the top plate 12 . Similarly, the power board 41 and the sensor board 42 are fixed to the top plate 12 by fastening bolts 19B made of a non-magnetic material such as brass to female screw holes drilled in the top plate 12 . As shown in FIG. 1 , the bolts 19A and 19B have lengths that do not protrude from the cover 10 when attached to the cover 10 .

The tone ring 30 is provided with convex portions 31 protruding radially outward and concave portions 32 concave radially inward from the convex portions 31 alternately arranged in the circumferential direction. The tone ring 30 has a cylindrical protrusion 33 protruding toward the bearing main body 20 on its inner peripheral side. The tone ring 30 is made of a magnetic material such as silicon steel plate, carbon steel (JIS standard SS400 or S45C), martensitic stainless steel (JIS standard SUS420) or ferritic stainless steel (JIS standard SUS430). .

The power generation section 3 has a permanent magnet 13 , a yoke 14 and a coil 15 . A permanent magnet 13 is fixed so as to be in contact with the top plate 12 . Yoke 14 is fixed so as to be in contact with permanent magnet 13 . The yoke 14 may be magnetically connected to the permanent magnet 13, and may not be directly connected. The yoke 14 is made of a magnetic material such as a silicon steel plate or NiFe alloy. It is desirable that the yoke 14 be made of a material having a magnetic permeability equal to or higher than that of the cover 10 so that the amount of magnetic flux inside the yoke 14 increases. If the yoke 14 is made of a silicon steel plate, the magnetic permeability will be high and the magnetic flux will easily pass through the yoke 14 .

The coil 15 is a so-called magnet wire in which a conducting wire is wound around the yoke 14 . The coils 15 of adjacent power generation units 3 are connected in series, and wires drawn out from the coils 15 of the plurality of power generation units 3 connected in series are connected to the power supply substrate 41 .

As shown in FIG. 3, one end of the side plate 11 is fitted into a groove 21A provided on the outer circumference of the outer ring 21 and fixed. The tubular projection 33 is fitted and fixed in a groove 22A provided on the inner circumference of the inner ring 22 . As a result, as shown in FIGS. 3 and 4, the inner peripheral end face of the yoke 14 and the inner peripheral end face of the top plate 12 are arranged at positions facing the convex portion 31 or the concave portion 32 of the tone ring 30 . Also, the cover 10 and the tone ring 30 can be easily attached to the bearing body 20 .

The magnetic field of the permanent magnet 13 causes the magnetic flux Mf to pass through the yoke 14 , the convex portion 31 or concave portion 32 of the tone ring 30 , and the top plate 12 of the cover 10 . Therefore, the permanent magnet 13, the yoke 14, the convex portion 31 or concave portion 32 of the tone ring 30, and the top plate 12 of the cover 10 form a magnetic circuit.

Further, as shown in FIG. 5, a magnetic body 311 exhibiting stronger magnetism than the tone ring 30 is attached to a part of the outer peripheral side end face 31IF of the projection 31 . For example, a concave portion corresponding to the shape and size of the magnetic body is provided on the outer peripheral side end surface 31IF of the convex portion 31 . The magnetic body 311 is fitted in this recess. The magnetic body 311 and the outer peripheral side end face 31IF around the magnetic body 311 are flush or substantially flush. The magnetic body 311 is, for example, a hard magnetic permanent magnet. In the tone ring 30, the magnetic body 311 is attached to only one location. The magnetic body 311 comes closest to the angle sensor 443 each time the inner ring 22 makes one relative rotation (360° rotation) with respect to the outer ring 21 . Angle sensor 443 includes, for example, a Hall element.

FIG. 6 is an explanatory diagram for explaining the relationship between the voltage of the electromotive force and the time in the bearing with wireless sensor. Here, the horizontal axis of FIG. 6 is the time T, and the vertical axis is the voltage Vi of the electromotive force. When the outer ring 21 is fixed and the inner ring 22 rotates, the tone ring 30 rotates together with the inner ring 22, and the tone ring 30 and the power generating section 3 rotate relative to each other. For the yoke 14, an air gap from the inner peripheral end surface to the outer peripheral end surface 31IF of the protrusion 31 shown in FIG. 3, an air gap from the inner peripheral end surface to the outer peripheral end surface 32IF of the recessed portion 32 shown in FIG. are alternately replaced.

In this manner, the distance between the yoke 14 of the power generating section 3 and the outer circumference of the tone ring 30 changes periodically due to the protrusions 31 and the recesses 32 on the outer circumference of the tone ring 30 . As a result, the density of the magnetic flux Mf generated in the power generation section 3 changes. When the yoke 14 with the permanent magnet 13 and the tone ring 30 are close to each other, the magnetic flux Mf passing through the permanent magnet 13, the yoke 14, and the tone ring 30 is large, and the yoke 14 and the tone ring 30 are separated. , the magnetic flux Mf passing through the permanent magnet 13, yoke 14, and tone ring 30 is reduced. A voltage change occurs in the coil 15 in which the magnet wire is wound around the yoke 14 according to the density change of the magnetic flux Mf.

That is, when the yoke 14 and the outer peripheral end surface 31IF of the protrusion 31 are closest to each other, the magnetic flux Mf shown in FIG. 3 increases, and the electromotive force voltage V1 shown in FIG. When the yoke 14 and the outer peripheral end surface 32IF of the recess 32 are farthest apart, the magnetic flux Mf shown in FIG.

FIG. 7 is a plan view of the wireless sensor unit. As shown in FIG. 7 , a power supply section 43 is mounted on the power supply board 41 . The power supply unit 43 converts the single-phase AC power supplied from the power generation unit 3 into a DC voltage and supplies the DC voltage to the sensor substrate 42 . A sensor 44 , a control section 45 having a communication circuit, and a transmission antenna 47 are mounted on the sensor substrate 42 . DC power from the power supply unit 43 is supplied to the sensor 44 and the control unit 45 . The sensor 44, the control unit 45, and the transmission antenna 47 may be composed of separate IC (Integrated Circuit) chips, or part or all of them may be composed of one IC chip. Also, the sensor 44 has, for example, an acceleration sensor 441 , a temperature sensor 442 and an angle sensor 443 . The sensor 44 may be one or two of the acceleration sensor 441, the temperature sensor 442, and the angle sensor 443 described above, or may be a sensor that measures other physical quantities.

FIG. 8 is a perspective view of the cover. As shown in FIG. 8, the cover 10 has a through hole 12H. As shown in FIG. 1, the through hole 12H is sealed with a non-magnetic lid 17 made of a non-magnetic material such as resin. As described above, the cover 10 has the transmitting antenna 47 on the bearing body 20 side. Here, since the cover 10 has magnetism, it has a function of shielding electromagnetic waves from the transmitting antenna 47 . Therefore, as shown in FIG. 7, the transmission antenna 47 is arranged so as to overlap the non-magnetic lid 17 in a plan view of the bearing body 20 viewed from the direction of the rotation axis Zr. That is, the non-magnetic lid 17 is provided on the portion of the cover 10 facing the transmitting antenna 47 . Therefore, the electromagnetic wave WV from the transmitting antenna 47 can reach the communication section 151 through the non-magnetic lid 17 .

Further, as shown in FIG. 8, one surface 12A of the top plate 12 is provided with a plurality of recesses 18 for arranging the power generation unit 3. As shown in FIG. For example, each of the multiple recesses 18 has a first recess 18A for arranging the coil 15 and a second recess 18B for arranging the permanent magnet 13 . When the one surface 12A is used as a reference surface, the first recess 18A is deeper than the second recess 18B.

The control unit 45 has a function of converting various data detected by the sensor 44 from analog data to digital data (for example, A/D conversion) and storing the data. The control unit 45 also has a function of transmitting stored digital data to the outside via the transmission antenna 47 . The control unit 45 operates using DC power supplied from the power supply unit 43 .

Digital data transmitted from the wireless sensor unit 5 is received by the communication section 151 of the host device 150 shown in FIG. Digital data received by the communication unit 151 is processed by the computer 152 . Thus, since the wireless sensor-equipped bearing 1 can wirelessly transmit digital data, it can be miniaturized.

As the wireless sensor according to the present embodiment, in addition to the wireless sensor-equipped bearing 1 described above, there is also a spacer-type wireless sensor module provided near the bearing. A wireless communication system using a wireless sensor such as the above-described bearing 1 with wireless sensor or wireless sensor module will be described below. The following description includes components that are substantially the same as those of the bearing 1 with wireless sensor and host device 150 described with reference to FIGS. 1 to 8 .

In this embodiment, a specific application example of a wireless communication system in a motor equipped with a bearing with a wireless sensor will be described. FIG. 9 is a diagram showing an example of the internal configuration of a motor having a bearing with a wireless sensor. In addition, the same code|symbol is attached|subjected to the same structure part as the structure mentioned above, and the overlapping description is abbreviate|omitted. Moreover, the rotating machine to which the wireless communication system according to the present embodiment is applied is not limited to a motor, and may be, for example, a reduction gear provided with a bearing with a wireless sensor.

The motor 50 has a metal housing 51, a rotor 52, a stator 53, and an output shaft 54 as a basic configuration.

The rotor 52 and output shaft 54 are rotatably held with respect to the metal housing 51 and stator 53 of the motor 50 . The wireless sensor-equipped bearing 1 is provided on the load side of the output shaft 54 to which the rotation control target 100 of the motor 50 is mechanically connected. In the present embodiment, the rotation controlled object 100 (hereinafter also referred to as “load”) of the motor 50 is, for example, a rotating machine such as a pump or a speed reducer.

The wireless sensor unit 5 is provided inside the bearing body 20 on the load side in the direction of the rotation axis Ax. A transmission antenna 47 of the wireless sensor unit 5 is composed of a conductor provided on the sensor substrate 42 . The transmitting antenna 47 is composed of, for example, any one of a pattern antenna, a microstrip patch antenna, and a chip antenna. The transmitting antenna 47 is arranged such that the intensity of the radio waves it radiates becomes maximum in the direction perpendicular to the sensor substrate 42 (the direction of the arrow in FIG. 9), and the maximum radiation direction of the radio waves is directed inward in the direction of the rotation axis Ax.

When applying the wireless communication system according to the embodiment to the motor 50 shown in FIG. A.

FIG. 10 is a diagram illustrating an application example of a wireless communication system according to a first comparative example. The same components as those in FIG. 9 are denoted by the same reference numerals, and overlapping descriptions are omitted.

In the motor 50 configured as shown in FIG. 9, the parasitic repeater 60 cannot be provided on the extension line of the radio wave radiation direction (inner side in the rotation axis Ax direction) of the transmission antenna 47 of the wireless sensor unit 5 . Therefore, in the example shown in FIG. 10 , the terminal portion 62 is inserted through a hole provided in the upper surface of the metal housing 51 of the parasitic repeater 60 . That is, the radiation direction of radio waves from the wireless sensor unit 5 is different from the drilling direction of the hole in the metal casing 51 through which the terminal portion 62 of the parasitic repeater 60 is inserted.

A transmission antenna 61 of the parasitic repeater 60 is provided outside the metal housing 51 . The transmitting antenna 61 can be composed of, for example, a dipole antenna, a monopole antenna, or the like.

The receiving antenna 65 of the parasitic repeater 60 is composed of a conductor provided on an antenna substrate 64 made of resin, for example, and provided inside the metal housing 51 . The receiving antenna 65 can be composed of, for example, a pattern antenna or a microstrip patch antenna, and the receiving sensitivity is maximized in the vertical direction of the antenna substrate 64 . In the first comparative example shown in FIG. 10 , the receiving antenna 65 of the parasitic repeater 60 is arranged at a position where the maximum sensitivity direction substantially coincides with the maximum radiation direction of the transmitting antenna 47 of the wireless sensor unit 5 .

The terminal portion 62 and the antenna substrate 64 are connected by a coaxial cable 63, for example. That is, the transmitting antenna 61 and the receiving antenna 65 are connected via the terminal portion 62 and the coaxial cable 63 . The connection between the antenna substrate 64 and the coaxial cable 63 is, for example, an SMA connector or U.S.A. They are connected by FL connectors. Coaxial cable 63 may be, for example, these SMA connectors or U.S.A. It is a coaxial cable with a diameter of about 1.37 mm, which is suitable for the FL connector.

As shown in FIG. 10 , the receiving antenna 65 of the parasitic repeater 60 is arranged facing the transmitting antenna 47 of the wireless sensor unit 5 . As a result, the maximum radiation direction of the transmitting antenna 47 of the wireless sensor unit 5 and the maximum sensitivity direction of the receiving antenna 65 of the parasitic repeater 60 substantially match.

Further, the reception antenna 65 of the parasitic repeater 60 is arranged at a position where the distance d from the transmission antenna 47 of the wireless sensor unit 5 is λ/2π or less, where λ is the wavelength of the fundamental wave of the radio wave. , the near-field electromagnetic coupling effect generated between the transmitting antenna 47 of the wireless sensor unit 5 and the receiving antenna 65 of the parasitic repeater 60 can be utilized.

FIG. 11 is a diagram illustrating an application example of a wireless communication system according to a second comparative example.

The first parasitic repeater 60 corresponds to the parasitic repeater 60 shown in FIG. In the example shown in FIG. 11, a second parasitic repeater 80 is provided inside the metal housing 51 .

The receiving antenna 85 of the second parasitic repeater 80 and the transmitting antenna 81 of the second parasitic repeater 80 are composed of conductors provided on an antenna substrate 84 made of resin, for example. In the second example of the comparative example shown in FIG. 11, the receiving antenna 85 and the transmitting antenna 81 are configured by pattern antennas or microstrip patch antennas, for example, and the receiving sensitivity is maximized in the vertical direction of the antenna substrate 84 . In the second parasitic repeater 80, the maximum sensitivity direction of the receiving antenna 85 substantially coincides with the maximum radiation direction of the transmission antenna 47 of the wireless sensor unit 5, and the maximum radiation direction of the transmission antenna 81 is the first parasitic repeater. It is arranged at a position that substantially coincides with the maximum sensitivity direction of the receiving antenna 65 of the repeater 60 . The receiving antenna 85 and the transmitting antenna 81 may be provided on different substrates, and the substrates may be connected to each other by coaxial cables.

As shown in FIG. 11 , the receiving antenna 85 of the second parasitic repeater 80 is arranged facing the transmitting antenna 47 of the wireless sensor unit 5 . As a result, the maximum radiation direction of the transmitting antenna 47 of the wireless sensor unit 5 and the maximum sensitivity direction of the receiving antenna 85 of the second parasitic repeater 80 substantially match.

Also, the transmitting antenna 81 of the second parasitic repeater 80 is arranged to face the receiving antenna 65 of the first parasitic repeater 60 . As a result, the maximum radiation direction of the transmitting antenna 81 of the second parasitic repeater 80 and the maximum sensitivity direction of the receiving antenna 65 of the first parasitic repeater 60 substantially match.

Further, the receiving antenna 85 of the second parasitic repeater 80 is placed at a position where the distance d1 from the transmitting antenna 47 of the wireless sensor unit 5 is λ/2π or less, so that the transmitting antenna 47 of the wireless sensor unit 5 and the receiving antenna 85 of the second parasitic repeater 80, the near-field electromagnetic coupling effect can be utilized.

Further, the distance d2 between the transmitting antenna 81 of the second parasitic repeater 80 and the receiving antenna 65 of the first parasitic repeater 60 is λ/2π, where λ is the wavelength of the fundamental wave of radio waves. By arranging in the following positions, the near-field electromagnetic coupling effect generated between the transmitting antenna 81 of the second parasitic repeater 80 and the receiving antenna 65 of the first parasitic repeater 60 can be utilized. can be done.

As described above, in the first example of the comparative example shown in FIG. 10 and the second example of the comparative example shown in FIG. In space A, the transmitting antenna 61 and the receiving antenna 65 of the first parasitic repeater 60 are connected via a terminal portion 62 and a coaxial cable 63 . In such a mode, the routing of the coaxial cable 63 and the arrangement of the second parasitic repeater 80 in the second example of the comparative example shown in FIG. For example, it is limited by ribs provided on the metal housing 51, windings of the rotor 52, magnets of the stator 53, etc.). In particular, in the second example of the comparative example shown in FIG. 11, the second parasitic repeater 80 has a substantially L-shaped structure, so that the size of the rotary machine in the direction of the rotation axis increases, and the wireless communication system becomes unusable. Applicable rotary machines are limited.

FIG. 12 is a diagram illustrating an application example of the wireless communication system according to the embodiment. 11 are assigned the same reference numerals, and overlapping descriptions are omitted. The wireless communication system according to the embodiment differs from the second comparative example shown in FIG. 11 in the aspect of the second parasitic repeater 80 .

In the configuration shown in FIG. 12, the receiving antenna 85 of the second parasitic repeater 80 is composed of, for example, a conductor provided on an antenna substrate 84a (first substrate) made of resin. ) with the maximum receiving sensitivity in the vertical direction.

FIG. 13 is a diagram showing the structure of the antenna substrate on which the receiving antenna of the second parasitic repeater is provided. An antenna substrate 84a (first substrate) on which the receiving antenna 85 of the second parasitic repeater 80 is provided is composed of, for example, a flexible printed circuit board (FPC) made of polyimide-based resin. In the example shown in FIG. 13, the receiving antenna 85 of the second parasitic repeater 80 is a spiral antenna made of a conductor provided on the antenna substrate 84a (first substrate). The feeding points 86a and 86b of the receiving antenna 85 of the second parasitic repeater 80 are, for example, SMA connectors and U.S.A. An FL connector is provided and connected to the transmission antenna 81 via a coaxial cable (not shown) or a transmission line 88 to be described later with reference to FIG.

The antenna substrate 84a (first substrate) provided with the receiving antenna 85 of the second parasitic repeater 80 is provided with the transmitting antenna 47 of the wireless sensor unit 5, as in the second example of the comparative example shown in FIG. It is arranged substantially parallel to and opposed to the substrate. As a result, the maximum radiation direction of the transmitting antenna 47 of the wireless sensor unit 5 (the direction indicated by the arrow b in FIG. 12) and the maximum sensitivity direction of the receiving antenna 85 of the second parasitic repeater 80 substantially match.

The receiving antenna 85 of the second parasitic repeater 80 is not limited to the spiral antenna shown in FIG. good.

In the configuration shown in FIG. 12, the transmitting antenna 81 of the second parasitic repeater 80 is composed of a conductor provided on an antenna substrate 84b (second substrate) composed of, for example, a high-frequency multilayer substrate. It is a directional antenna having unidirectionality in the horizontal plane of the substrate 84b (second substrate).

The receiving antenna 65 of the first parasitic repeater 60 is an extension plane of the horizontal plane of the antenna substrate 84b (second substrate) on which the transmitting antenna 81 of the second parasitic repeater 80 is provided (arrow a in FIG. the plane containing the direction). A specific aspect of the transmitting antenna 81 of the second parasitic repeater 80 will be described below.

FIG. 14A is a diagram showing the structure of an antenna substrate on which a transmitting antenna of a second parasitic repeater is provided. 14A is a view seen from the right side of FIG. 12, and the upper side of FIG. 12 corresponds to the left side. The antenna substrate 84b (second substrate) has at least two conductor layers. The transmitting antenna 81 of the second parasitic repeater 80 includes, for example, a first layer conductor 81a of an antenna substrate 84b (second substrate) indicated by a solid line in FIG. 14A, and an antenna substrate 84b (second substrate) indicated by a broken line in FIG. 2 substrate) second layer of conductors 81b. A first-layer conductor 81a of an antenna substrate 84b (second substrate) indicated by a solid line in FIG. 14A and a second-layer conductor 81b of an antenna substrate 84b (second substrate) indicated by a broken line in FIG. 14A are laminated. ing. FIG. 14B is a diagram showing conductors of the first layer of the antenna substrate on which the transmitting antenna of the second parasitic repeater is provided. FIG. 14C is a diagram showing conductors on the second layer of the antenna substrate on which the transmitting antenna of the second parasitic repeater is provided.

In the examples shown in FIGS. 14A, 14B, and 14C, the transmitting antenna 81 of the second parasitic repeater 80 is a log-periodic antenna (logarithmic periodic antenna).

The log-periodic antennas of the modes shown in FIGS. 14A, 14B, and 14C satisfy the following equations (1) and (2).

ln ₊₁ / _ln =xn ₊₁ / _xn (1)

α=tan ⁻¹ (l _n /x _n ) (2)

In the above formulas (1) and (2), n=1, 2, 3, 4 in the embodiments shown in FIGS. 14A, 14B, and 14C.

In the embodiments shown in FIGS. 14A, 14B, and 14C, the conductor constituting the transmitting antenna 81 of the second parasitic repeater 80 is, for example, 46 [mm] in the vertical direction shown in FIGS. It is a copper foil pattern of 18 [μm] provided on an antenna substrate 84b (second substrate) having a width of 18 [mm] and a thickness of 0.5 [mm]. As a communication standard used in the present disclosure, for example, a short-range wireless communication standard such as BLE (Bluetooth LE, Bluetooth Low Energy) in the 2.4 [GHz] band is exemplified. Therefore, it is possible to manufacture a small antenna suitable for use in the space A on the load side of the output shaft 54 in which the bearing 1 with wireless sensor inside the metal housing 51 is provided.

The antenna substrate 84b (second substrate) on which the transmitting antenna 81 of the second parasitic repeater 80 is provided is composed of, for example, a Teflon (registered trademark)-based rigid substrate. Thereby, the dielectric constant in the high frequency range can be suppressed. Further, the antenna substrate 84b (second substrate) may include an additive such as glass fiber or fused silica. As a result, thermal characteristics and electrical characteristics can be improved.

For example, an SMA connector or a U.S.C. An FL connector is provided and connected to the receiving antenna 85 with a coaxial cable.

The receiving antenna 65 of the first parasitic repeater 60 is composed of a conductor provided on an antenna substrate 64 made of resin, for example, as in the second example of the comparative example shown in FIG. This is the antenna with the maximum receiving sensitivity in the direction. The first parasitic repeater 60 is arranged at a position where the maximum sensitivity direction of the receiving antenna 65 substantially coincides with the maximum radiation direction of the transmitting antenna 81 of the second parasitic repeater 80 (the direction of arrow a in FIG. 12). be done.

The mode of the transmitting antenna 81 of the second parasitic repeater 80 is not limited to the modes shown in FIGS. 14A, 14B, and 14C. ) may be

P. Jin and R. W. Ziolkowski,“Metamaterial-Inspired, Electrically Small Huygens Sources,” in IEEE Antennas and Wireless Propagation Letters, vol. 9, pp. 501-505, May 2010.

In the above-described aspect, the antenna substrate 84a (first substrate) on which the receiving antenna 85 of the second parasitic repeater 80 is provided, and the antenna substrate 84b (first substrate) on which the transmitting antenna 81 of the second parasitic repeater 80 is provided. 2 substrates) are arranged close to each other substantially in parallel. As a result, the size of the second parasitic repeater 80 in the direction of the rotation axis Ax can be reduced compared to the configuration of the second example of the comparative example shown in FIG. can be expanded.

FIG. 15 is a schematic structural diagram of a second parasitic repeater according to the embodiment. In the example shown in FIG. 15, an antenna substrate 84a (first substrate) provided with the transmitting antenna 81 of the second parasitic repeater 80 and an antenna substrate 84b (having the receiving antenna 85 of the second parasitic repeater 80 provided) The second substrate) is fitted in a resin bracket 87 (resin member) so as to be substantially parallel to each other. It should be noted that the bracket 87 (resin member) may be of a mode that maintains the insulation of the conductors (copper foil patterns) of both the antenna substrate 84a (first substrate) and the antenna substrate 84b (second substrate). As a result, the antenna substrate 84a (first substrate) and the antenna substrate 84b (second substrate) are held in a state of being substantially parallel and close to each other.

The transmitting antenna 81 and the receiving antenna 85 are connected by a transmission line 88 provided on the bracket 87 . In the example shown in FIG. 15, the transmission line 88 may be, for example, a coaxial cable or a waveguide, as described above. Alternatively, the transmission line 88 may be configured such that a rod-shaped or plate-shaped conductor is embedded in the bracket 87 and the transmission antenna 81 and the reception antenna 85 are connected by the conductor. In this case, it is preferable that the conductor is formed in a gentle curve without providing a bent portion with an acute angle.

In the above-described configuration, so that the maximum radiation direction of the transmitting antenna 47 of the wireless sensor unit 5 and the maximum sensitivity direction of the receiving antenna 85 of the second parasitic repeater 80 match (in the direction of arrow b in FIG. 12), The antenna substrate 84a (first substrate) provided with the receiving antenna 85 of the second parasitic repeater 80 is arranged substantially parallel to the substrate provided with the transmitting antenna 47 of the wireless sensor unit 5, and the second parasitic repeater 80 By arranging the receiving antenna 85 of the repeater 80 at a position where the distance from the transmitting antenna 47 of the wireless sensor unit 5 is λ/2π or less, the transmitting antenna 47 of the wireless sensor unit 5 and the second parasitic repeater 80 It is possible to utilize the electromagnetic coupling effect of the near field generated between the receiving antenna 85 of the wireless sensor unit 5 and suppress the propagation loss of the radio waves radiated from the transmitting antenna 47 of the wireless sensor unit 5 .

Furthermore, the receiving antenna 65 of the first parasitic repeater 60 is, as shown in FIG. It is mounted on a plane (a plane including the direction of arrow a in FIG. 12). As described above, in the horizontal plane of the antenna substrate 84b (second substrate), the maximum radiation direction of the transmission antenna 81 of the second parasitic repeater 80 having unidirectionality (the direction of arrow a in FIG. 12). By arranging the receiving antenna 65 of the first parasitic repeater 60, the multipath fading phenomenon caused by the reflection in the metal housing 51 of the radio waves radiated from the transmitting antenna 81 of the second parasitic repeater 80 is suppressed. be done. As a result, the propagation loss of radio waves radiated from the transmitting antenna 81 of the second parasitic repeater 80 can be suppressed.

In the above-described configuration, the antenna substrate 84a (first substrate) provided with the receiving antenna 85 of the second parasitic repeater 80 (first substrate) and the antenna substrate 84b (second substrate) provided with the transmitting antenna 81 are arranged substantially parallel. By disposing, the second parasitic repeater 80 can be made more compact than the second example of the comparative example shown in FIG.

FIG. 16 is a diagram illustrating an application example of a wireless communication system according to a modification of the embodiment; FIG. 12 shows an example in which the first parasitic repeater 60 is provided on the extension of the radio wave radiation direction of the transmission antenna 81 of the second parasitic repeater 80. However, as shown in FIG. The first parasitic repeater 60 is placed at a position deviated from the extended plane (plane including the direction of arrow a) of the horizontal plane of the antenna substrate 84b (second substrate) on which the transmitting antenna 81 of the parasitic repeater 80 of No. 2 is provided. An insertion hole may be provided so that the transmitting antenna 61 and the receiving antenna 65 of the first parasitic repeater 60 are connected via the terminal portion 62 and the coaxial cable 63 .

With the configuration of the above-described embodiment, it is possible to obtain a wireless communication system that can be widely applied regardless of the internal structure of a rotating machine while suppressing a decrease in electric field intensity.

Note that the diagrams used above are conceptual diagrams for qualitatively explaining the present disclosure, and are not limited to these. In addition, although the above-described embodiment is an example of the preferred implementation of the present disclosure, it is not limited to this, and various modifications can be implemented without departing from the gist of the present disclosure.

1 Bearing with Wireless Sensor 5 Wireless Sensor Unit 10 Cover 20 Bearing Body 21 Outer Ring 22 Inner Ring 40 Substrate 41 Power Substrate 42 Sensor Substrate 43 Power Supply Part 44 Sensor 45 Control Part 47 Transmitting Antenna (Wireless Sensor Unit)
50 motor 51 metal housing 52 rotor 53 stator 54 output shaft 60 parasitic repeater (first parasitic repeater)
61 transmitting antenna (parasitic repeater, first parasitic repeater)
62 terminal portion 63 coaxial cable 64 antenna substrate 65 receiving antenna (parasitic repeater, first parasitic repeater)
80 second parasitic repeater 81 transmitting antenna (second parasitic repeater)
81a, 81b conductors 82a, 82b feed point 84a antenna substrate (first substrate)
84b Antenna substrate (second substrate)
85 receiving antenna (second parasitic repeater)
86a, 86b feeding point 87 bracket (resin member)
88 transmission path 100 rotation control object 150 host device 151 communication unit 152 computer 441 acceleration sensor 442 temperature sensor 443 angle sensor

Claims (6)

a wireless sensor unit provided inside a metal housing;
a first parasitic repeater provided between the inside and the outside of the metal housing;
a second parasitic repeater provided inside the metal housing for relaying radio waves transmitted from the wireless sensor unit to the first parasitic repeater;
with
the receiving antenna of the second parasitic repeater is composed of a conductor provided on the first substrate,
The transmitting antenna of the second parasitic repeater is a directional antenna that is composed of a conductor provided on a second substrate different from the first substrate and has unidirectionality in the horizontal plane of the second substrate. can be,
A wireless communication system, wherein a receiving antenna of the first parasitic repeater is arranged on an extension plane of a horizontal plane of the second substrate. 2. The wireless communication system according to claim 1, wherein the transmission antenna of said second parasitic repeater is composed of a plurality of layers of conductors provided on said second substrate. 3. The wireless communication system according to claim 2, wherein the transmitting antenna of said second parasitic repeater is a log-periodic antenna. The radio communication system according to claim 2, wherein the transmission antenna of the second parasitic repeater is a Huygens source antenna. The radio communication system according to any one of claims 1 to 4, wherein the first board and the second board are arranged in close proximity to each other in a substantially parallel manner. The transmitting antenna of the wireless sensor unit is composed of a conductor provided on a substrate,
The wireless communication system according to any one of claims 1 to 5, wherein the first board is arranged substantially parallel to a board provided with a transmitting antenna of the wireless sensor unit.

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