wireless communication system

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: A motor 50 applied with a wireless communication system performs wireless communication between the interior and the exterior of a metal housing 51 configured by engaging a first housing 51a and a second housing 51b with each other. The motor comprises: a wireless sensor unit 5 attached to the first housing; a first passive relay 60 attached to the second housing and provided between the interior and the exterior of the metal housing; and a second passive relay 80 attached to the first housing to relay an electric wave transmitted from the wireless sensor unit to the first passive relay. A reception antenna 85 of the second passive relay is configured by a conductor provided on an antenna substrate 84a. A transmission antenna 81 of the second passive relay 80 is configured by a conductor provided on an antenna substrate 84b. The antenna substrate 84a and antenna substrate 84b are arranged substantially in parallel with each other and adjacent to each other.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to wireless communication systems. [Background technology]

[0002] A bearing with a wireless sensor has been proposed that incorporates a wireless sensor unit containing various sensors such as a vibration sensor, acceleration sensor, rotation sensor, and temperature sensor, and outputs data acquired by the various sensors via wireless communication (for example, Patent Document 1).In a rotating machine to which such a bearing with a wireless sensor is applied, a wireless communication system that includes a non-powered repeater that relays radio waves between the inside and outside of the metal casing of the rotating machine has been disclosed as a technology for sending data measured by the wireless sensor unit to the outside (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-66433 [Patent Document 2] International Publication No. 2020 / 209206 Summary of the Invention [Problem to be solved by the invention]

[0004] In a wireless communication system using a parasitic repeater, it is necessary to suppress the propagation loss of radio waves in order to maintain a high electric field strength. In the above-mentioned conventional technology, the terminal part of the parasitic repeater inserted into the metal housing of the rotating machine is connected to the receiving antenna with a coaxial cable, and the receiving antenna of the parasitic repeater is positioned opposite the transmitting antenna of the wireless sensor unit, and the electromagnetic coupling effect of the near field generated between the transmitting antenna of the wireless sensor unit and the receiving antenna of the parasitic repeater is used to enhance the suppression effect of the propagation loss of the radio waves emitted from the wireless sensor unit. Alternatively, a second parasitic repeater that changes the transmission direction of the radio waves and repeats them between a first parasitic repeater that relays radio waves inside and outside the metal casing of the rotating machine and a wireless sensor unit is provided, and a terminal portion of the first parasitic repeater inserted into the metal casing of the rotating machine and a receiving antenna are connected by a coaxial cable, and the receiving antenna of the first parasitic repeater is arranged opposite the transmitting antenna of the second parasitic repeater, and the effect of suppressing the propagation loss of the radio waves radiated from the second parasitic repeater is enhanced by utilizing the electromagnetic coupling effect of the near field generated between the transmitting antenna of the second parasitic repeater and the receiving antenna of the first parasitic repeater. When a wireless communication system of this type is applied to a rotating machine such as a motor or a reducer, the routing of the coaxial cable inside the metal casing and the placement of the second parasitic repeater may be restricted by the internal structure of the metal casing, multipath fading due to reflections, etc.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide 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 strength. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a wireless communication system according to one embodiment of the present invention is a wireless communication system that performs wireless communication between the inside and outside of a metal housing in which a first housing and a second housing are fitted together, and includes: a wireless sensor unit attached to the first housing; a first parasitic repeater attached to the second housing and arranged between the inside and outside of the metal housing; and a second parasitic repeater attached to the first housing and relaying radio waves transmitted from the wireless sensor unit to the first parasitic repeater, wherein the receiving antenna of the second parasitic repeater is formed by a conductor provided on a first board, and the transmitting antenna of the second parasitic repeater is formed by a conductor provided on a second board different from the first board, the first board and the second board are arranged in close proximity and approximately parallel to each other, and the receiving antenna of the first parasitic repeater is arranged on a plane extended from the horizontal plane of the second board when the first housing and the second housing are fitted together.

[0007] According to the above configuration, a wireless communication system can be obtained that can be widely applied regardless of the internal structure of a rotating machine while suppressing a decrease in electric field strength.

[0008] In a preferred embodiment of the wireless communication system, the wireless communication system further comprises a resin member that holds the first substrate and the second substrate substantially parallel to each other.

[0009] As a desirable aspect of the wireless communication system, the transmitting antenna of the wireless sensor is preferably constructed of a conductor provided on a substrate, and the first substrate is preferably arranged approximately parallel to the substrate on which the transmitting antenna of the wireless sensor unit is provided.

[0010] As a desirable aspect of the wireless communication system, it is preferable that the receiving antenna of the first parasitic repeater and the transmitting antenna of the first parasitic repeater are integrated and attached to the second housing.

[0011] As a desirable aspect of the wireless communication system, the receiving antenna of the first parasitic repeater is preferably connected to the transmitting antenna of the first parasitic repeater by a coaxial cable and attached to the second housing. [Effects of the Invention]

[0012] According to the present invention, a wireless communication system can be obtained that can be widely applied regardless of the internal structure of a rotating machine while suppressing a decrease in electric field strength. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of a bearing with a wireless sensor. [Figure 2] FIG. 2 is an exploded perspective view of the bearing with a wireless sensor. [Figure 3] FIG. 3 is a cross-sectional view of a portion of the bearing with a wireless sensor, including the power generating portion and the protruding portion. [Figure 4] FIG. 4 is a cross-sectional view of a portion of the bearing with a wireless sensor, including the power generating section and the recessed section. [Figure 5] FIG. 5 is a cross-sectional view of a portion of a bearing with a wireless sensor, including a sensor substrate. [Figure 6] FIG. 6 is an explanatory diagram for explaining the relationship between the voltage of the electromotive force and time in a bearing with a wireless sensor. [Figure 7] FIG. 7 is a plan view of the wireless sensor unit. [Figure 8] FIG. 8 is a perspective view of the cover. [Figure 9] FIG. 9 is a diagram showing an example of the internal configuration of a motor equipped with a bearing with a wireless sensor. [Figure 10] FIG. 10 is a diagram illustrating an application example of a wireless communication system according to a first example of a comparative example. [Figure 11] FIG. 11 is a diagram illustrating an application example of a wireless communication system according to a second example of the comparative example. [Figure 12]FIG. 12 is a diagram showing a specific example of a motor to which the wireless communication system according to the embodiment is applied. [Figure 13] FIG. 13 is a schematic structural diagram of a second passive repeater according to the embodiment. [Figure 14] FIG. 14 is a structural diagram showing a specific example of the first unit and the second unit that constitute the motor shown in FIG. [Figure 15] FIG. 15 is a diagram illustrating an application example of a wireless communication system according to a first modified example of the embodiment. [Figure 16] FIG. 16 is a diagram illustrating an application example of a wireless communication system according to a second modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments. Furthermore, the components in the following embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the following embodiments can be combined as appropriate.

[0015] First, a bearing with a wireless sensor will be described as an example to which the wireless sensor according to this embodiment is applied.

[0016] FIG. 1 is a perspective view of a bearing with a wireless sensor. FIG. 2 is an exploded perspective view of a bearing with a wireless sensor. FIG. 3 is a cross-sectional view of a portion of the bearing with a wireless sensor that includes a power generating section and a convex section. FIG. 4 is a cross-sectional view of a portion of the bearing with a wireless sensor that includes a power generating section and a concave section. FIG. 5 is a cross-sectional view of a portion of the bearing with a wireless sensor that includes a sensor board. The bearing with a wireless sensor 1 shown in FIG. 1 has a wireless sensor unit 5, a tone ring 30, and a bearing body (first bearing) 20, as shown in FIG. 2.

[0017] 3 to 5, the bearing body (first bearing) 20 is a rolling bearing having an outer ring 21, an inner ring 22, and rolling elements 23. The outer ring 21 and the inner ring 22 rotate relatively around a rotation axis Ax (see FIG. 1). In the following description, the inner ring 22 will be described as the rotating ring, but as long as the inner ring 22 and the outer ring 21 rotate relatively, it does not matter which one is rotating.

[0018] The cover 10 has an annular top plate 12 and a cylindrical side plate 11 connected to the periphery of the top plate 12. The cover 10 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).

[0019] 2, in the wireless sensor unit 5, a plurality of power generation units 3 and a substrate 40 are attached to one surface 12A of the top plate 12. The one surface 12A is the surface facing the bearing body (first bearing) 20. The substrate 40 has a power supply substrate 41 and a sensor substrate 42.

[0020] 1 and 2, for example, bolts 19A made of a non-magnetic material such as brass are fastened to female threaded holes in the top plate 12, thereby fixing the power generation unit 3 to the top plate 12. Similarly, bolts 19B made of a non-magnetic material such as brass are fastened to female threaded holes in the top plate 12, thereby fixing the power supply board 41 and the sensor board 42 to the top plate 12. As shown in FIG. 1, bolts 19A and 19B have a length such that they do not protrude from the cover 10 when attached to the cover 10.

[0021] The tone ring 30 has convex portions 31 that protrude outward and concave portions 32 that are recessed inward from the convex portions 31, arranged alternately in the circumferential direction. The tone ring 30 has cylindrical protrusions 33 on its inner periphery that protrude toward the bearing body (first bearing) 20. 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).

[0022] The power generation unit 3 has a permanent magnet 13, a yoke 14, and a coil 15. The permanent magnet 13 is fixed so as to be in contact with the top plate 12. The yoke 14 is fixed so as to be in contact with the permanent magnet 13. The yoke 14 only needs to be magnetically connected to the permanent magnet 13, and does not have to be directly connected. The yoke 14 is made of a magnetic material such as a silicon steel plate or a NiFe alloy. It is desirable that the yoke 14 be made of a material with magnetic permeability equal to or higher than that of the material of the cover 10, so as to increase the amount of magnetic flux inside the yoke 14. If the yoke 14 is made of a silicon steel plate, the magnetic permeability will be high, making it easier for magnetic flux to pass through the yoke 14.

[0023] The coils 15 are so-called magnet wires 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 wiring drawn from the coils 15 of the plurality of series-connected power generation units 3 is connected to the power supply board 41.

[0024] As shown in Fig. 3, one end of the side plate 11 is fitted into and fixed to a groove 21A provided on the outer periphery of the outer ring 21. The cylindrical protrusion 33 is fitted into and fixed to a groove 22A provided on the inner periphery of the inner ring 22. As a result, as shown in Figs. 3 and 4, the inner circumferential end faces of the yoke 14 and the top plate 12 are positioned to face the protrusions 31 or recesses 32 of the tone ring 30. The cover 10 and the tone ring 30 can then be easily attached to the bearing body (first bearing) 20.

[0025] The magnetic field of permanent magnet 13 causes magnetic flux Mf to pass through yoke 14, protrusion 31 or recess 32 of tone ring 30, and top plate 12 of cover 10. Therefore, permanent magnet 13, yoke 14, protrusion 31 or recess 32 of tone ring 30, and top plate 12 of cover 10 form a magnetic circuit.

[0026] As shown in FIG. 5 , a magnetic body 311 exhibiting stronger magnetism than the tone ring 30 is attached to a portion of the outer peripheral end face 31IF of the protrusion 31. For example, a recess corresponding to the shape and size of the magnetic body is provided in the outer peripheral end face 31IF of the protrusion 31. The magnetic body 311 is fitted into this recess. The magnetic body 311 and the outer peripheral end face 31IF around the magnetic body 311 are flush or nearly flush with each other. The magnetic body 311 is, for example, a hard magnetic permanent magnet. The magnetic body 311 is attached to only one location on the tone ring 30. With each rotation (360° rotation) of the inner ring 22 relative to the outer ring 21, the magnetic body 311 comes closest to the angle sensor 443. The angle sensor 443 includes, for example, a Hall element.

[0027] FIG. 6 is an explanatory diagram illustrating the relationship between the voltage of the electromotive force and time in a bearing with a wireless sensor. The horizontal axis in FIG. 6 represents time T, and the vertical axis represents the voltage Vi of the electromotive force. As the outer ring 21 is fixed and the inner ring 22 rotates, the tone ring 30 rotates along with the inner ring 22, causing the tone ring 30 and the power generator 3 to rotate relative to each other. For the yoke 14, the air gap from the inner peripheral end face to the outer peripheral end face 31IF of the protrusion 31 shown in FIG. 3 alternates with the air gap from the inner peripheral end face to the outer peripheral end face 32IF of the recess 32 shown in FIG. 4.

[0028] In this way, the convex portions 31 and concave portions 32 on the outer periphery of the tone ring 30 cause the distance between the yoke 14 of the power generation unit 3 and the outer periphery of the tone ring 30 to periodically change. This causes a change in the density of the magnetic flux Mf generated in the power generation unit 3. When the yoke 14, which includes the permanent magnet 13, and the tone ring 30 are close to each other, the magnetic flux Mf passing through the permanent magnet 13, yoke 14, and tone ring 30 is large; when the yoke 14 and the tone ring 30 are farther apart, the magnetic flux Mf passing through the permanent magnet 13, yoke 14, and tone ring 30 is small. This change in the density of the magnetic flux Mf generates a voltage change in the coil 15, which is made of magnet wire wound around the yoke 14.

[0029] 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 becomes larger, and the electromotive force voltage V1 shown in Fig. 6 is supplied to the power supply board 41. When the yoke 14 and the outer peripheral end surface 32IF of the recess 32 are farthest from each other, the magnetic flux Mf shown in Fig. 4 becomes smaller, and the electromotive force voltage V2 shown in Fig. 6 is supplied to the power supply board 41.

[0030] FIG. 7 is a plan view of the wireless sensor unit. As shown in FIG. 7, a power supply unit 43 is mounted on a power supply board 41. The power supply unit 43 converts single-phase AC power supplied from the power generation unit 3 into DC voltage and supplies it to a sensor board 42. A sensor 44, a control unit 45 having a communication circuit, and a transmitting antenna 47 are mounted on the sensor board 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 transmitting antenna 47 may be configured on separate IC (Integrated Circuit) chips, or some or all of them may be configured on a single IC chip. The sensor 44 includes, for example, an acceleration sensor 441, a temperature sensor 442, and an angle sensor 443. The sensor 44 may be any 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.

[0031] FIG. 8 is a perspective view of the cover. As shown in FIG. 8, a through-hole 12H is formed in the cover 10. 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 is provided with a transmitting antenna 47 on the bearing body (first bearing) 20 side. Here, the cover 10 is magnetic, and therefore has the effect of shielding electromagnetic waves from the transmitting antenna 47. For this reason, as shown in FIG. 7, the transmitting antenna 47 is arranged to overlap the non-magnetic lid 17 in a plan view seen from the direction of the rotation axis Zr of the bearing body (first bearing) 20 (the direction of the rotation axis Ax in FIG. 1). In other words, the non-magnetic lid 17 is provided on a portion of the cover 10 facing the transmitting antenna 47. For this reason, the electromagnetic waves WV of the transmitting antenna 47 are radiated in the direction of the rotation axis Zr (Ax) of the bearing body (first bearing) 20 via the non-magnetic lid 17 and can reach the communication unit 151.

[0032] 8, one surface 12A of the top plate 12 is provided with a plurality of recesses 18 for arranging the power generation unit 3. For example, each of the plurality of 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 taken as the reference plane, the first recess 18A is deeper than the second recess 18B.

[0033] 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 the stored digital data to the outside via a transmission antenna 47. The control unit 45 operates using DC power supplied from the power supply unit 43.

[0034] The digital data transmitted from the wireless sensor unit 5 is received by the communication unit 151 of the higher-level device 150 shown in Figure 1. The digital data received by the communication unit 151 is processed by the computer 152. In this way, the bearing with wireless sensor 1 can transmit digital data wirelessly, which allows for miniaturization.

[0035] In addition to the above-described wireless sensor bearing 1, the wireless sensor according to this embodiment also includes a spacer-type wireless sensor module that is installed near the bearing. Below, a wireless communication system using a wireless sensor such as the above-described wireless sensor bearing 1 or wireless sensor module will be described. Note that the following description includes components that are substantially the same as the configuration of the wireless sensor bearing 1 and host device 150 described in Figures 1 to 8.

[0036] In this embodiment, a specific example of application of the wireless communication system to a motor equipped with a bearing equipped with a wireless sensor will be described. Fig. 9 is a diagram showing an example of the internal configuration of a motor equipped with a bearing equipped with a wireless sensor. Note that components that are the same as those in the configuration described above are given the same reference numerals, and duplicated explanations will be omitted. Furthermore, the rotating machine to which the wireless communication system according to this embodiment is applied is not limited to a motor, and may be, for example, a reducer equipped with a bearing equipped with a wireless sensor.

[0037] The motor 50 basically comprises a metal housing 51, a rotor 52, a stator 53, and an output shaft 54.

[0038] The rotor 52 and the output shaft 54 ​​are rotatably held relative to the metal casing 51 and the stator 53 of the motor 50. The bearing with wireless sensor 1 is provided on the load side of the output shaft 54 ​​to which a rotation-controlled object 100 of the motor 50 is mechanically connected. In this embodiment, the rotation-controlled object 100 of the motor 50 (hereinafter also referred to as the "load") is a rotating machine such as a pump or a reducer.

[0039] The wireless sensor unit 5 is provided on the inside in the direction of the rotation axis Ax of the load-side bearing body (first bearing) 20. The transmitting antenna 47 of the wireless sensor unit 5 is made up of a conductor provided on the sensor substrate 42. The transmitting antenna 47 is made up of, for example, any one of a pattern antenna, a microstrip patch antenna, and a chip antenna.

[0040] As described above, the wireless sensor unit 5 of the present disclosure is configured to be covered by the cover 10 provided on the bearing body (first bearing) 20. The cover 10 is formed of a magnetic material, and radio waves transmitted from the transmitting antenna 47 of the wireless sensor unit 5 are radiated in the direction of the rotation axis Ax of the bearing body (first bearing) 20 via the non-magnetic lid 17 that seals the through-hole 12H provided in the cover 10. When the bearing with wireless sensor 1 is applied to the motor 50 configured as shown in FIG. 9, the transmitting antenna 47 of the wireless sensor unit 5 is positioned so that the maximum radiation direction of the radio waves faces inward in the direction of the rotation axis Ax. Therefore, the strength of the radio waves radiated from the transmitting antenna 47 of the wireless sensor unit 5 is greatest in the direction perpendicular to the sensor board 42. Therefore, when the bearing with wireless sensor 1 is applied to the motor 50 configured as shown in FIG. 9, a system is required to extract the radio waves transmitted from the transmitting antenna 47 of the wireless sensor unit 5 to the outside of the metal housing 51.

[0041] Hereinafter, a wireless communication system capable of extracting radio waves transmitted from the transmitting antenna 47 of the wireless sensor unit 5 to the outside of the metal housing 51 will be described.

[0042] Fig. 10 is a diagram showing an application example of a wireless communication system according to a first example of a comparative example. The same components as those in Fig. 9 are given the same reference numerals, and duplicated explanations will be omitted. In the first example of a comparative example shown in Fig. 10, the wireless communication system includes a wireless sensor unit 5 and a non-powered repeater 60.

[0043] Each element that makes up the non-powered repeater 60 is provided in the first space A on the load side of the output shaft 54 ​​where the bearing with wireless sensor 1 is provided, but the internal space of a motor is generally narrow and placement is restricted by the structure inside the metal casing.

[0044] 10, the terminal portion 62 of the parasitic repeater 60 is inserted into a hole provided on the top surface of the metal housing 51. In other words, the radiation direction of the radio waves from the wireless sensor unit 5 is different from the drilling direction of the hole in the metal housing 51 through which the terminal portion 62 of the parasitic repeater 60 is inserted.

[0045] The transmitting antenna 61 of the parasitic repeater 60 is provided outside the metal housing 51. The transmitting antenna 61 can be configured, for example, as a dipole antenna or a monopole antenna.

[0046] The receiving antenna 65 of the parasitic repeater 60 is configured, for example, by a conductor provided on a resin antenna substrate 64, and is provided inside the metal housing 51. The receiving antenna 65 can be configured, for example, by a pattern antenna or a microstrip patch antenna, and has maximum receiving sensitivity in the vertical direction of the antenna substrate 64. In a first example of the 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.

[0047] The terminal portion 62 and the antenna substrate 64 are connected by, for example, a coaxial cable 63. That is, the transmitting antenna 61 and the receiving antenna 65 are connected via the terminal portion 62 and the coaxial cable 63. The antenna substrate 64 and the coaxial cable 63 are connected by, for example, an SMA connector or a U.FL connector. The coaxial cable 63 is, for example, a coaxial cable with a diameter of about 1.37 mm that is compatible with these SMA connectors and U.FL connectors.

[0048] 10, the receiving antenna 65 of the parasitic repeater 60 is disposed opposite 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 are approximately aligned.

[0049] Furthermore, when the wavelength of the fundamental wave of the radio wave is λ, the receiving antenna 65 of the parasitic repeater 60 can be arranged at a position where the distance d from the transmitting antenna 47 of the wireless sensor unit 5 is λ / 2π or less, thereby making it possible to utilize the electromagnetic coupling effect of the near field occurring between the transmitting antenna 47 of the wireless sensor unit 5 and the receiving antenna 65 of the parasitic repeater 60. However, the opposing arrangement of the receiving antenna 65 and the transmitting antenna 47 increases the size in the direction of the rotation axis Ax.

[0050] 11 is a diagram illustrating an application example of a wireless communication system according to a second example of the comparative example. In the second example of the comparative example shown in FIG. 11, the wireless communication system includes a wireless sensor unit 5, a first parasitic repeater 60, and a second parasitic repeater 80.

[0051] The first parasitic repeater 60 corresponds to the parasitic repeater 60 shown in Fig. 10. In the example shown in Fig. 11, a second parasitic repeater 80 is provided inside a metal housing 51. This second parasitic repeater 80 is configured to change the radiation direction of the radio waves radiated from the transmitting antenna 47 of the wireless sensor unit 5 and transmit the radio waves to the first parasitic repeater 60.

[0052] The receiving antenna 85 of the second parasitic repeater 80 and the transmitting antenna 81 of the second parasitic repeater 80 are configured with conductors provided on an antenna substrate 84 made of, for example, resin. In a second example of the comparative example shown in FIG. 11 , the receiving antenna 85 and the transmitting antenna 81 are configured with, for example, a pattern antenna or a microstrip patch antenna, and the receiving sensitivity is maximized in the vertical direction of the antenna substrate 84. The second parasitic repeater 80 is disposed at a position where the maximum sensitivity direction of the receiving antenna 85 substantially coincides with the maximum radiation direction of the transmitting antenna 47 of the wireless sensor unit 5, and the maximum radiation direction of the transmitting antenna 81 substantially coincides with the maximum sensitivity direction of the receiving antenna 65 of the first parasitic repeater 60. The receiving antenna 85 and the transmitting antenna 81 may be provided on separate substrates, and the substrates may be connected to each other by coaxial cables.

[0053] 11, the receiving antenna 85 of the second parasitic repeater 80 is disposed opposite 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 are approximately aligned.

[0054] Furthermore, the transmitting antenna 81 of the second parasitic repeater 80 is disposed opposite 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 are approximately aligned.

[0055] In addition, by positioning the receiving antenna 85 of the second unpowered repeater 80 at a position where the distance d1 from the transmitting antenna 47 of the wireless sensor unit 5 is λ / 2π or less, it is possible to utilize the near-field electromagnetic coupling effect that occurs between the transmitting antenna 47 of the wireless sensor unit 5 and the receiving antenna 85 of the second unpowered repeater 80.

[0056] Furthermore, by positioning the transmitting antenna 81 of the second unpowered repeater 80 and the receiving antenna 65 of the first unpowered repeater 60 at a position where the distance d2 between them is λ / 2π or less, where λ is the wavelength of the fundamental wave of the radio wave, it is possible to utilize the electromagnetic coupling effect of the near field that occurs between the transmitting antenna 81 of the second unpowered repeater 80 and the receiving antenna 65 of the first unpowered repeater 60.

[0057] As described above, in the first comparative example shown in FIG. 10 and the second comparative example shown in FIG. 11, in the first space A on the load side of the output shaft 54 ​​where the wireless sensor-equipped bearing 1 is provided inside the metal housing 51, the transmitting antenna 61 and the receiving antenna 65 of the parasitic repeater (first parasitic repeater) 60 are connected via the terminal part 62 and the coaxial cable 63. In such an embodiment, the routing of the coaxial cable 63 and the arrangement of the second parasitic repeater 80 in the second comparative example shown in FIG. 11 are limited by the structures of the metal housing 51, the rotor 52, and the stator 53 (for example, ribs provided on the metal housing 51, windings of the stator 53, or magnets of the rotor 52). In particular, in the second comparative example shown in FIG. 11, the second parasitic repeater 80 has a substantially L-shaped structure, which limits the rotating machines to which the wireless communication system can be applied. Furthermore, since the receiving antenna 65 of the parasitic repeater (first parasitic repeater) 60 and the second parasitic repeater 80 must be assembled inside the narrow metal housing 51 (first space A), the assembly workability of the motor 50 may be deteriorated.

[0058] Hereinafter, a wireless communication system according to an embodiment will be described, which enables an expanded range of application and improved assembly workability by reducing the size in the direction of the rotation axis Ax.

[0059] Fig. 12 is a diagram showing a specific example of a motor to which the wireless communication system according to the embodiment is applied. Note that the same components as those in Fig. 11 are given the same reference numerals and redundant explanations will be omitted.

[0060] 12, a metal housing 51 of a motor 50 (rotating machine) is composed of a first housing 51a and a second housing 51b. The wireless communication system according to the embodiment differs from the second example of the comparative example shown in FIG. 11 in the configuration of a second parasitic repeater 80.

[0061] 12, the receiving antenna 85 of the second parasitic repeater 80 is configured with a conductor provided on an antenna substrate 84a (first substrate) made of, for example, a resin. The receiving antenna 85 of the second parasitic repeater 80 is exemplified by, for example, a spiral antenna, a patch antenna, a microstrip line antenna, etc. The receiving antenna 85 of the second parasitic repeater 80 is not limited to a spiral antenna, a patch antenna, or a microstrip line antenna, and is preferably an antenna whose receiving sensitivity is maximized in the vertical direction of the antenna substrate 84a (first substrate).

[0062] 12, the transmitting antenna 81 of the second parasitic repeater 80 is configured with a conductor provided on an antenna substrate 84b (second substrate) configured with, for example, a Teflon (registered trademark) rigid substrate. The transmitting antenna 81 of the second parasitic repeater 80 is exemplified by, for example, a patch antenna or a microstrip line antenna. The transmitting antenna 81 of the second parasitic repeater 80 is not limited to a patch antenna or a microstrip line antenna, and is preferably an omnidirectional antenna within the horizontal plane of the antenna substrate 84b (second substrate).

[0063] 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 (second substrate) on which the transmitting antenna 81 of the second parasitic repeater 80 is provided are arranged in close proximity to each other and substantially parallel to each other. This makes it possible to reduce the size of the second parasitic repeater 80 in the direction of the rotation axis Ax compared to the configuration of the second example of the comparative example shown in Fig. 11, thereby expanding the application range of the wireless communication system according to the present disclosure.

[0064] Fig. 13 is a schematic structural diagram of a second parasitic repeater according to an embodiment. In the example shown in Fig. 13, an antenna substrate 84a (first substrate) on which a transmitting antenna 81 of a second parasitic repeater 80 is provided and an antenna substrate 84b (second substrate) on which a receiving antenna 85 of the second parasitic repeater 80 is provided are fitted into a resin bracket 87 (resin member) so as to be approximately parallel to each other. Note that the bracket 87 (resin member) may be configured in any manner as long as it maintains insulation between the conductors (copper foil patterns) of both the antenna substrate 84a (first substrate) and the antenna substrate 84b (second substrate). This allows the antenna substrate 84a (first substrate) and the antenna substrate 84b (second substrate) to be held in a state in which they are arranged closely to each other and approximately parallel to each other.

[0065] The transmitting antenna 81 and the receiving antenna 85 are connected by a transmission line 88 provided on a bracket 87. In the example shown in Fig. 13, the transmission line 88 may be, for example, a coaxial cable or a waveguide. Alternatively, the transmission line 88 may be formed by embedding a rod-shaped or plate-shaped conductor in the bracket 87, and the transmitting antenna 81 and the receiving antenna 85 are connected by this conductor. In this case, it is preferable that the conductor is formed in a gentle curve without any sharp bends.

[0066] Fig. 14 is a structural diagram showing a specific example of the first unit and second unit constituting the motor shown in Fig. 12. As shown in Fig. 14, the motor 50 in the embodiment shown in Fig. 12 is composed of a first unit 50a and a second unit 50b.

[0067] The first unit 50a incorporates a wireless sensor-equipped bearing 1 with an output shaft 54 ​​inserted into a first housing 51a. The second passive repeater 80 is attached to the first housing 51a via a bearing pressing member 55 made of resin, for example.

[0068] The antenna board 84a (first board) on which the receiving antenna 85 of the second parasitic repeater 80 is provided is arranged approximately parallel to the board on which the transmitting antenna 47 of the wireless sensor unit 5 is provided, separated by a resin non-magnetic cover 17, 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 coincide (direction indicated by arrow b in Figure 12), and the receiving antenna 85 of the second parasitic repeater 80 is arranged in a position where the distance from the transmitting antenna 47 of the wireless sensor unit 5 is λ / 2π or less.This makes it possible to utilize the electromagnetic coupling effect of the near field that occurs between the transmitting antenna 47 of the wireless sensor unit 5 and the receiving antenna 85 of the second parasitic repeater 80, and to suppress the propagation loss of the radio waves emitted from the transmitting antenna 47 of the wireless sensor unit 5.

[0069] In the second unit 50b, a bearing body (second bearing) 20a is attached along a shaft hole 54a provided in the second housing 51b. The first parasitic repeater 60 is inserted through a hole provided in the second housing 51b.

[0070] The motor 50 is configured by inserting the end of the output shaft 54 ​​incorporated in the first housing 51a into the shaft hole 54a, and fitting the first housing 51a and the second housing 51b together in the direction of the rotation axis Ax.

[0071] In the above-described configuration, the receiving antenna 65 of the first parasitic repeater 60 is attached on an extension plane (plane including the direction of arrow a in FIG. 12) of the horizontal plane of the antenna board 84b (second board) on which the transmitting antenna 81 of the second parasitic repeater 80 is provided, when the first housing 51a and the second housing 51b are fitted together, as shown in FIG. 12. As described above, by making the transmitting antenna 81 of the second parasitic repeater 80 an omnidirectional antenna within the horizontal plane of the antenna board 84b (second board) and arranging the receiving antenna 65 of the first parasitic repeater 60 on an extension plane (plane including the direction of arrow a in FIG. 12) of the horizontal plane of the antenna board 84b (second board), the multipath fading phenomenon caused by reflection of radio waves radiated from the transmitting antenna 81 of the second parasitic repeater 80 within the metal housing 51 is suppressed. This makes it possible to suppress the propagation loss of the radio waves radiated from the transmitting antenna 81 of the second parasitic repeater 80.

[0072] Furthermore, in the above-described configuration, by arranging the antenna board 84a (first board) on which the receiving antenna 85 of the second parasitic repeater 80 is provided and the antenna board 84b (second board) on which the transmitting antenna 81 is provided approximately parallel to each other, the second parasitic repeater 80 can be made more compact than the second example of the comparative example shown in Figure 11.

[0073] Furthermore, in the above-described configuration, the first parasitic repeater 60 has the receiving antenna 65 and the transmitting antenna 61 integrated via the terminal portion 62, and the first housing 51a and the second housing 51b are fitted together in a state where the receiving antenna 65 and the transmitting antenna 61 are inserted into a hole provided in the second housing 51b, thereby forming the motor 50. With this configuration, the assembly workability can be improved compared to the first example of the comparative example shown in Fig. 10 and the second example of the comparative example shown in Fig. 11. In addition, the wiring work of the coaxial cable 63 is also unnecessary.

[0074] (Variation) FIG. 15 is a diagram illustrating an application example of a wireless communication system according to a first modified example of the embodiment. Figure 12 shows an example in which a first parasitic repeater 60 in which a receiving antenna 65 and a transmitting antenna 61 are integrated via a terminal portion 62 is provided on an extension plane (plane including the direction of arrow a) of the horizontal plane of the antenna board 84b (second board) on which the transmitting antenna 81 of the second parasitic repeater 80 is provided.However, as shown in Figure 15, a hole for inserting the first parasitic repeater 60 may be provided at a position off the extension plane (plane including the direction of arrow a) of the horizontal plane of the antenna board 84b (second board) on which the transmitting antenna 81 of the second parasitic repeater 80 is provided, and the transmitting antenna 61 and receiving antenna 65 of the first parasitic repeater 60 are connected via the terminal portion 62 and a coaxial cable 63, and the antenna board 64 on which the receiving antenna 65 of the first parasitic repeater 60 is provided may be attached to the second housing 51b via, for example, a resin antenna mounting member 56.

[0075] Fig. 16 is a diagram illustrating an application example of a wireless communication system according to a second modified example of the embodiment, in which the first space A on the load side is seen through from the direction of the rotation axis Ax.

[0076] As shown in Figures 15 and 16, when the first housing 51a and the second housing 51b are fitted together, the receiving antenna 65 of the first parasitic repeater 60 only needs to be attached on an extension plane (a plane including the direction of arrow a) of the horizontal plane of the antenna board 84b (second board) on which the transmitting antenna 81 of the second parasitic repeater 80 is provided, and is not limited by the position of the insertion hole through which the transmitting antenna 61 of the first parasitic repeater 60 is inserted or the circumferential position of the receiving antenna 65 of the first parasitic repeater 60.

[0077] 15 and 16, the first housing 51a and the second housing 51b are fitted together in a state in which the antenna board 64 provided with the receiving antenna 65 of the first parasitic repeater 60 is attached to the second housing 51b via the antenna mounting member 56, thereby forming the motor 50. With this configuration, as with the wireless communication systems according to the embodiments shown in FIGS. 12 to 14, assembly workability can be improved compared to the first comparative example shown in FIG. 10 and the second comparative example shown in FIG. 11. In both FIGS. 10 and 11, the antenna board 64 and the receiving antenna 65 are present on the insertion path of the rotor 52, so the assembly method shown in FIG. 14 cannot be used. Therefore, the rotor 52 must be inserted from the right, which requires some ingenuity in the manner of connection with the rotationally controlled object 100.

[0078] The configurations of the above-described embodiment and modified examples provide 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 strength.

[0079] In this disclosure, an embodiment has been described in which a wireless communication system is provided in the first space A on the load side of the output shaft 54 ​​on which the bearing with wireless sensor 1 is provided inside the metal housing 51. However, an embodiment may also be such that the bearing body (bearing 20a) in the second space B is a bearing with a wireless sensor and a wireless communication system is provided in the second space B, or a embodiment may be such that a wireless communication system is provided in each of the first space A and the second space B.

[0080] Furthermore, the figures used above are conceptual diagrams for qualitatively explaining the present disclosure, and are not intended to be limiting. Furthermore, while the above-described embodiment is an example of a preferred implementation of the present disclosure, the present disclosure is not limited thereto, and various modifications can be made without departing from the spirit of the present disclosure. [Explanation of symbols]

[0081] 1. Bearings with wireless sensors 5 Wireless Sensor Unit 10 Cover 17 Non-magnetic lid 20 Bearing body (first bearing) 20a Bearing body (second bearing) 21 outer ring 22 Inner Circle 40 boards 41 Power supply board 42 Sensor board 43 Power supply section 44 sensors 45 Control Unit 47 Transmitting antenna (wireless sensor unit) 50 Motor (rotating machine) 50a Unit 1 50b 2nd unit 51 Metal Case 51a 1st cabinet 51b Second cabinet 52 rotor 53 Stator 54 Output shaft 54a Shaft hole 55 Bearing holder 56 Antenna mounting member 60 Unpowered Repeater (First Unpowered Repeater) 61 Transmitting antenna (parallel repeater, first parallax repeater) 62 Terminal section 63 Coaxial Cable 64 Antenna board 65 Receiving antenna (parasitic repeater, first parasitic repeater) 80 Second unpowered repeater 81 Transmitting antenna (second non-powered repeater) 84a, 84b Antenna board 85 Receiving antenna (second non-powered repeater) 87 Bracket (resin part) 88 Transmission Line 100 Rotation control target 150 Upper device 151 Communications Department 152 Computer 441 Acceleration Sensor 442 Temperature Sensor 443 Angle Sensor A 1st space B 2nd space Ax rotation axis

Claims

1. A wireless communication system for wirelessly communicating between the inside and outside of a metal housing of a rotary machine, the rotary machine comprising: a shaft; a metal housing in which a first housing and a second housing are fitted together; and a bearing that holds the shaft rotatably relative to the metal housing, a wireless sensor unit attached to the first housing, the wireless sensor unit detecting the state of the bearing with a sensor and transmitting data via a transmitting antenna; a first parasitic repeater attached to the second housing and provided between the inside and the outside of the metal housing; a second passive repeater attached to the first housing and configured to relay radio waves transmitted from the wireless sensor unit to the first passive repeater; Equipped with the receiving antenna of the second parasitic repeater is an antenna formed of a conductor provided on a first substrate, and having a maximum receiving sensitivity in a direction perpendicular to the first substrate; a transmitting antenna of the second parasitic repeater is a directional antenna formed of a conductor provided on a second substrate different from the first substrate, and having unidirectionality in a direction parallel to the second substrate; the maximum radiation direction of the radio waves emitted from the transmitting antenna of the wireless sensor unit is parallel to the rotation axis of the shaft; a receiving antenna of the second parasitic repeater is arranged in a maximum radiation direction of radio waves radiated from a transmitting antenna of the wireless sensor unit; the first substrate and the second substrate are disposed on a plane perpendicular to the rotation axis of the shaft, and are disposed in close proximity to each other and substantially parallel to each other at overlapping positions when viewed from a direction parallel to the rotation axis of the shaft; the maximum radiation direction of the radio wave radiated from the transmitting antenna of the second parasitic repeater is directed in a direction perpendicular to the rotation axis of the shaft; The receiving antenna of the first parasitic repeater is arranged in a maximum radiation direction of radio waves radiated from the transmitting antenna of the second parasitic repeater when the first housing and the second housing are fitted together. Wireless communication system.

2. a resin member that holds the first substrate and the second substrate substantially parallel to each other; 10. The wireless communication system of claim 1.

3. a transmitting antenna of the wireless sensor unit is formed by a conductor provided on a substrate; The first substrate is disposed substantially parallel to a substrate on which a transmitting antenna of the wireless sensor unit is provided.

3. The wireless communication system according to claim 1 or 2.

4. The receiving antenna of the first parasitic repeater and the transmitting antenna of the second parasitic repeater are integrated and attached to the second housing.

4. A wireless communication system according to claim 1.

5. The receiving antenna of the first parasitic repeater is connected to the transmitting antenna of the first parasitic repeater by a coaxial cable and is attached to the second housing.

4. A wireless communication system according to claim 1.

Images