JP2005304154A - Rectenna and bearing device fitted with rectenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small rectenna where the drop of reception efficiency is little, and a bearing device fitted with a rectenna mounting this rectenna. <P>SOLUTION: This rectenna 1 has a reception means which reduce waves and a rectifying means 3 which rectifies the power received with this reception means. As the above reception means, a dipole antenna 2 with a turned-up or bent tip is used. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rectenna that is a device that wirelessly receives power and converts it into DC power, and a rectenna-equipped bearing device that includes the rectenna.

Some wheel bearing devices are equipped with a rotation sensor for controlling an anti-lock brake device (ABS). As such a wheel bearing device with a sensor, a wheel rotation number signal as a sensor output is wirelessly transmitted, and a power source for the sensor unit and the sensor signal transmission unit is a generator mounted on the bearing, a radio wave from the vehicle body, electromagnetic coupling A power supply harness from the vehicle body to the sensor unit is omitted (for example, Patent Document 1).
Furthermore, a wheel bearing device is also attempted which is equipped with a wireless sensor system that supplies power to a plurality of sensor units by wireless power feeding and wirelessly transmits and receives sensor detection signals of each sensor unit. This is advantageous in that it eliminates the need for power supply lines and signal lines to the bearings and reduces the number of assembly steps, and since power is secured by wireless power feeding, wheel rotation detection at zero speed can be detected. This is possible and effective for improving the performance of anti-lock brake devices.

In a wireless sensor system using wireless power feeding, a rectenna that is a power receiving element having a receiving means and a rectifying means is provided. This rectenna receives radio waves such as microwaves for power transmission, converts the received high-frequency power into DC power, and supplies power to the sensor unit. Conventionally, a dipole antenna or the like has been used as a rectenna antenna.
JP 2001-151090 A

  The dipole antenna has high reception efficiency when the antenna size is ½ of the wavelength λ of the received radio wave. However, when the rectenna is attached to the bearing, the antenna size cannot be increased due to the installation space. For this reason, the reception efficiency is lowered, and the power reception efficiency is lowered by the rectenna. In addition, when a rectenna is used for the sensor-equipped wheel bearing device as described above, the rectenna is attached to a bearing or a tire suspension part, so that radio waves are easily affected by surrounding metal parts. Rectenna's power reception efficiency was decreasing.

  An object of the present invention is to provide a rectenna that is small and has little reduction in reception efficiency, and a rectenna-equipped bearing device in which the rectenna is mounted.

The rectenna according to the present invention is a rectenna having a receiving means for receiving radio waves and a rectifying means for rectifying the power received by the receiving means. As the receiving means, a dipole antenna having a shape in which the tip is folded or bent is used. It is used. The receiving means receives radio waves such as microwaves.
According to this configuration, since the dipole antenna serving as the receiving means has a folded or bent tip, the entire length of the antenna can be secured even if the size is reduced. Therefore, the rectenna can be made small and the power reception efficiency is hardly lowered.

  The dipole antenna may be formed on a dielectric substrate. When a dipole antenna is formed on a dielectric substrate, the effect of shortening the wavelength of the dielectric is added, thereby further promoting the reduction in size and the suppression of the decrease in power reception efficiency.

Further, a reflector may be provided at a position spaced a predetermined distance from the antenna surface on which the dipole antenna and the rectifying means are formed.
When the reflection plate is provided, the reception radio wave is reflected by the reflection plate so that the radio wave can be concentrated on the dipole antenna, and the power reception efficiency can be increased accordingly. In addition, when a reflector is provided, the rectenna can be made even less susceptible to the influence of surrounding metal parts and has a higher reception efficiency.

When a reflector is provided, a dielectric may be interposed between the antenna surface on which the dipole antenna and the rectifying means are formed and the reflector.
Since the dielectric is interposed between the antenna surface and the reflector, the rectenna can be further reduced in size without reducing the reception efficiency due to the wavelength shortening effect of the dielectric.

The wireless sensor system of the present invention includes the rectenna of the above-described invention and a sensor that is fed with the rectenna.
By adopting the rectenna that is small and highly efficient as described above in the wireless sensor system, the entire wireless sensor system can be reduced in size, and power can be efficiently supplied to the sensor.

A rectenna-equipped bearing device according to the present invention is characterized in that the rectenna having any one of the above-described configurations of the present invention is mounted on a bearing.
By providing a rectenna on the bearing, wireless power can be supplied from the periphery of the bearing to the sensor, and the wiring system is simplified. The sensor may be provided in the bearing or may be provided in the vicinity of the bearing as a separate body from the bearing. By providing the bearing with a rectenna, it is not necessary to install the rectenna in the bearing-use device independently, and the number of assembly steps can be reduced. In such a bearing device with a rectenna, by adopting the rectenna which is small and highly efficient according to the present invention, even if there is little margin space around the bearing installation place, the rectenna can be provided. The degree of design freedom can be increased.

A wheel bearing device with a rectenna according to the present invention is provided between an outer member having a double-row raceway surface on an inner periphery, an inner member having a raceway surface facing the raceway surface, and the raceway surfaces of both rows. A wheel bearing device having a rolling element and rotatably supporting a wheel with respect to a vehicle body, comprising a sensor for detecting a detection target and a rectenna for supplying power to the sensor. A rectenna having any one of the above-described configurations of the invention is used.
By providing the wheel bearing device with a rotation sensor and other sensors, the wheel bearing device can be made intelligent, and the function can be improved while limiting the increase in the number of assembly steps of the automobile. By supplying power to the sensor with the rectenna, the power supply harness from the vehicle body to the sensor can be omitted. In automobiles, the space around the wheel bearing device is small due to its small size and light weight, and it is difficult to obtain a spare space for installing the rectenna etc., but by adopting the rectenna of the present invention, its small size and high The advantage that efficiency can be achieved is effectively exhibited, and the wheel bearing device with the sensor and the rectenna can be obtained by effectively using the limited peripheral space.

Since the rectenna of the present invention uses a dipole antenna having a folded or bent tip as the receiving means, it can be miniaturized and a reduction in reception efficiency can be reduced.
Since the wireless sensor system of the present invention includes the rectenna of the present invention and the sensor that is fed by this rectenna, the wireless sensor system can be miniaturized and the wireless power supply to the sensor can be efficiently performed. .
Since the rectenna-equipped bearing device of the present invention is equipped with the rectenna of the present invention, the rectenna can be easily attached to the bearing, the number of assembling steps can be reduced, and the degree of design freedom can be increased.
Since the wheel bearing device with rectenna of the present invention includes the sensor and the rectenna of the present invention, it can be installed in a limited installation space while achieving intelligence by the sensor and simplification of the wiring system by the rectenna. In addition, the efficiency of power reception can be improved.

  A first embodiment of the present invention will be described with reference to FIGS. The rectenna 1 of this embodiment is an element for power reception when power is wirelessly fed by radio waves such as microwaves, and is an integrated antenna 2 and rectifier circuit 3 shown in the block diagram of FIG. It is. The antenna 2 is receiving means for receiving radio waves, and the rectifying circuit 3 is rectifying means for rectifying high-frequency power received by the antenna 2 and converting it to DC power. As shown in the circuit diagram of FIG. 3, the rectifier circuit 3 includes a rectifier diode 4, a coil 5, and a capacitor 6. As the diode 4, a shot barrier diode (SBD) is used as generally used. As the antenna 2, a dipole antenna is used.

1A to 1C are perspective views of the rectenna 1 as viewed from the front surface side, the side surface side, and the back surface side. The dipole antenna 2 as a receiving means is formed on the outer surface of the substrate 7 by printing or plating the pattern shape of copper or silver. The substrate 7 is made of a dielectric material. The pair of antenna patterns 2a, 2a constituting the dipole antenna 2 is formed in a shape in which the tip 2aa is folded from the front surface 7a to the back surface 7b of the substrate 7. Each antenna pattern 2a, 2a has a shape in which the end surface side is bent at the end of the substrate surface 7a and is further bent from the end surface to the substrate back surface, and the tip 2aa is positioned on the substrate back surface 7b. In this example, the antenna patterns 2a and 2a are bent along the cross-sectional shape of the substrate 7, but may be bent back into a U shape.
The pair of antenna patterns 2a and 2a are arranged so as to face each other at the center in the central longitudinal direction of the substrate surface 7a serving as the antenna surface. A rectifier circuit 3 connected to both antenna patterns 2a and 2a is arranged at the center, and an output wiring 8 is drawn from the rectifier circuit 3.

  By connecting the wiring 8 of the rectenna 1 to an element such as a sensor or a wireless tag or an electric device (not shown), power is supplied from the rectenna 1 to the element or the electric device. That is, the high frequency power received by the antenna 2 is rectified by the rectifier circuit 3 and converted to DC power, and the DC power is supplied from the wiring 8 to the elements and electrical equipment.

  According to the rectenna 1 having this configuration, since the dipole antenna 2 having a folded shape with the tip bent is used as the receiving means, the rectenna 1 can be reduced in size while securing a predetermined antenna size, and the power reception efficiency can be reduced. Can be reduced. Further, since the dipole antenna 2 is formed on the outer surface of the substrate 7 made of a dielectric material, the effect of shortening the wavelength of the dielectric material is added, thereby further promoting the miniaturization and the suppression of the decrease in power reception efficiency.

  Another embodiment of the present invention is shown in FIG. The rectenna 1 of this embodiment is the first embodiment shown in FIGS. 1 to 3 as shown in FIGS. 4 (A) to 4 (C) as perspective views seen from the front surface side, side surface side, and back surface side. In the embodiment, a reflector 9 is provided at a predetermined distance from the antenna surface which is the surface 7a of the substrate 7 on which the dipole antenna 2 and the rectifier circuit 3 are formed, and between the substrate 7 and the reflector 9 The dielectrics 10 are integrated with each other. The distance from the antenna surface (substrate surface 7a) to the position of the reflector 9 is a distance that can increase the reception efficiency of the rectenna 1. Other configurations are the same as those in the first embodiment.

  In the rectenna 1 of this embodiment, since the reflecting plate 9 is provided at a position spaced apart from the antenna surface (substrate surface 7a), the received radio waves are reflected by the reflecting plate 9 and concentrated on the dipole antenna 2. Power reception efficiency can be increased accordingly. Further, since the reflector 9 is positioned on the back side of the antenna 2, when the rectenna 1 is attached to a metal part such as a bearing, the influence of radio wave reflection from the metal part can be reduced. Further, by interposing the dielectric 10 between the antenna surface (substrate surface 7a) and the reflecting plate 9, the distance between the substrate 7 and the reflecting plate 9 for improving the power reception efficiency is shortened by the wavelength shortening effect of the dielectric 10. The rectenna 1 can be reduced in size accordingly.

  In each of the rectennas 1 of the above embodiments, the dipole antenna 2 has a folded shape in which the tip 2aa of the antenna pattern 2a extends to the back surface of the substrate 7. However, depending on the shape of the substrate 7, the dipole antenna 2 2aa may be a bent shape that is a position up to the end face of the base 7.

  FIG. 5 shows an embodiment of a wireless sensor system using the rectenna 1 having any of the above configurations. This wireless sensor system includes sensor units 11A and 11B attached to various devices and mechanical parts such as bearings, and a sensor receiver 12 that wirelessly supplies power and transmits and receives signals between the sensor units 11A and 11B. Is done. A plurality (two in this case) of sensor units 11A and 11B are provided. Each sensor unit 11A, 11B includes a sensor 13 that detects a detection target such as temperature and rotation, a signal transmission unit 14 that wirelessly transmits a detection signal detected by the sensor 13 to the sensor receiver 12, a rectenna 1, And a power supply circuit 15. The rectenna 1 is means for receiving high-frequency power wirelessly transmitted from the sensor receiver 12 and converting it into DC power. The power supply circuit 15 is means for supplying electric power to the sensor 13 and the signal transmission unit 14 using DC power extracted from the rectenna 1 as a power source. The power supply circuit 15 may include a capacitor or a secondary battery and a charging circuit thereof, and may store the surplus power supplied from the rectenna 1 therein. The sensor 13 may detect acceleration, vibration, torque, load, bearing preload, etc. in addition to temperature and rotation.

  The sensor receiver 12 includes a signal communication unit 16 that performs wireless communication with the signal transmission unit 14 of the sensor units 11A and 11B, and a power transmission unit 17 that wirelessly transmits power to the rectenna 1 of the sensor units 11A and 11B. . The signal communication unit 16 and the power transmission unit 17 may be an integrated unit provided in an integrated housing, circuit board, element, or the like, or may be separate. Further, there may be a plurality of signal communication units 16 and power transmission units 17.

According to the wireless sensor system having this configuration, high-frequency power is wirelessly transmitted from the power transmission unit 17 of the sensor receiver 12 to the rectennas 1 of the sensor units 11A and 11B provided in separate mechanical components. Is converted into DC power by each rectenna 1 and supplied as power from the power supply circuit 15 to each sensor 13 and the signal transmitter 14. In each sensor unit 11 </ b> A, 11 </ b> B, the detection signal detected by the sensor 13 is wirelessly transmitted by the signal transmission unit 14, and the detection signal is received by the signal communication unit 16 of the sensor receiver 12.
As shown in FIGS. 1 to 4, the rectenna 1 used for each of the sensor units 11A and 11B can be downsized and suppresses a decrease in power reception efficiency. While being able to reduce in size, the electric power supply to the sensor 13 and the signal transmission part 14 of sensor unit 11A, 11B can be performed efficiently.

  FIG. 6 shows an embodiment in which the above-described wireless sensor system is applied to a bearing device. One bearing device 21A is a rolling bearing including an inner ring 22 and an outer ring 23 having raceway surfaces 22a and 23a, respectively, and a rolling element 24 that fits between the raceway surfaces 22a and 23a. A sensor unit 11C having two types of sensors 13A and 13B to be detected is mounted. The sensors 13A and 13B are, for example, a temperature sensor, a vibration sensor, a load sensor, a torque sensor, a preload sensor, or the like. By installing these sensors and detecting the state of the bearing, it can be used for bearing failure diagnosis and factory line monitoring. The bearing device 21A is formed of a deep groove ball bearing, and the inner ring 22 fitted to the shaft 29A is a rotation side race and the outer ring 23 is a fixed side race. The rolling element 24 is held by a holder 25. One end of the annular space between the inner and outer rings 22 and 23 is sealed with a seal 26. In addition to the sensors 13A and 13B, the sensor unit 11C includes a rectenna 1, a power supply circuit, and a signal transmission unit (both not shown).

  The other bearing device 21B is also a deep groove ball bearing having the same structure as the above-described bearing device 21A, and is equipped with a sensor unit 11D having a rotation sensor 13C for detecting the number of rotations of the inner ring 22 fitted to the shaft 29B. is there. Since the configuration of each part excluding the sensor unit 11D is the same as that of the above-described bearing device 21A, the same reference numerals are given to the respective constituent members as in the case of the bearing device 21A, and description thereof is omitted here.

The rotation sensor 13 </ b> C includes an annular pulsar ring 30 mounted on the outer diameter surface of the inner ring 22, and a magnetic field sensor 31 that faces the pulsar ring 30 from the outer diameter side. The pulsar ring 30 has a periodic magnetic change in the circumferential direction, such as a magnet magnetized in multiple poles or a magnetic ring formed with gear-like irregularities in the circumferential direction. The magnetic field sensor 31 detects a periodic magnetic change in the circumferential direction of the pulsar ring 30, detects the relative rotation of the inner ring 22 and the outer ring 23, and outputs a rotation signal. This rotation signal is an incremental pulse train signal. In addition to the magnetic field sensor 31, the sensor unit 11D includes a rectenna 1, a power supply circuit, and a signal transmission unit (both not shown).
The magnetic field sensor 31 is preferably composed of a magnetoresistive sensor (MR sensor). This is because the magnetoresistive sensor can reduce power consumption by increasing the resistance value, which is advantageous for wireless power feeding. In addition to the magnetoresistive sensor, an active magnetic field sensor such as a Hall sensor, a fluxgate type magnetic field sensor, or an MI sensor can be used as the magnetic field sensor 31.

In addition, two magnetic field sensors 31 are arranged at positions where the phase is 90 ° apart from the period of the magnetic change in the circumferential direction of the pulsar ring 30 to detect rotation signals whose phases are different by about 90 °. good. Thus, by detecting the two rotation signals, the rotation direction of the shaft 29B can be detected.
The sensor unit 11D is attached to the outer ring 23 side of the bearing end opposite to the attachment portion of the seal 26 so as to face the pulsar ring 30 in the radial direction.

  Both the sensor units 11C and 11D and one sensor signal receiver 12 constitute a wireless sensor system. The sensor signal receiver 12 includes a signal communication unit 16 that wirelessly communicates with the sensor units 11C and 11D, and a power transmission unit 17 that wirelessly transmits power to the rectenna 1 of the sensor units 11C and 11D. This is the same as the case of the wireless sensor system.

  According to the wireless sensor system having this configuration, the electric power wirelessly transmitted from the sensor signal device 12 is received by the rectenna 1 of the sensor units 11C and 11D mounted on the bearing devices 21A and 21B, so that the sensors 13A and 13B, the magnetic field Electric power is supplied to the sensor 31 and the signal transmission unit (not shown), and the sensor and the signal transmission unit become operable. The detection signals detected by these sensors are wirelessly transmitted from the signal transmission units of the sensor units 11C and 11D and received by the communication signal unit 16 of the sensor signal device 12.

  In this wireless sensor system, since the rectenna 1 shown in FIGS. 1 to 4 is used, the rectenna 1 can be easily attached to the bearing devices 21A and 21B, the number of assembling steps can be reduced, and the degree of design freedom can be increased. it can.

  FIG. 7 shows an embodiment in which the wireless sensor system of FIG. 5 is applied to a wheel bearing device. In the wheel bearing device 41, the outer member 42 is fixed to the vehicle body via a knuckle (not shown). The inner member 43 is a rotating member, and includes a hub ring 47 and an outer ring 55a of a constant velocity universal joint 55 that is inserted into and fixed to the inner surface of the hub ring 47. The shaft portion 56 that integrally extends from the constant velocity universal joint outer ring 55a is formed by a large-diameter portion 56a and a small-diameter portion 56b on the base end side, and the small-diameter portion 56b is fixed by spline fitting to the inner-diameter surface of the hub wheel 47. ing.

  The outer member 42 has double-row raceway surfaces 45 a and 45 b on the inner circumference, and raceway surfaces 46 a and 46 b facing the raceway surfaces 45 a and 45 b are provided on the outer circumference of the inner member 43. That is, the raceway surfaces 46a and 46b of each row of the double row raceway surfaces 46a and 46b are formed on the hub wheel 47 and the constant velocity universal joint outer ring 55a of the inner member 43, respectively. The double row rolling elements 44 are interposed between the raceway surfaces 45a and 46a and between the raceway surfaces 45b and 46b. The inward member 43 has a wheel mounting flange 43 a, and the wheel is mounted to the wheel mounting flange 43 a with a bolt 51. The rolling elements 44 are held by a holder 48 for each row. The outer member 42, the inner member 43, the rolling elements 44, and the cage 48 constitute a rolling bearing, and the outer member 42 and the inner member 43 serve as raceways. The axial end of the annular space between the outer member 42 and the inner member 43 is sealed with seals 49 and 50.

  The rotation sensor 52 is a sensor that detects the rotation of the inner member 43, and includes a pulsar ring 53 and a magnetic field sensor 54 that faces the pulsar ring 53. The structure of the pulsar ring 53 and the magnetic field sensor 54 is the same as that of the rotation sensor 13C in FIG. The magnetic field sensor 54 is integrated with the sensor unit bearing interior 61A by being molded in the sensor unit bearing interior 61A that is fixed so as to penetrate the outer member 42 in the radial direction. Another sensor 62 for detecting information other than rotation in the bearing is also molded in the sensor unit bearing interior 61A. The sensor 62 is, for example, a temperature sensor, a vibration sensor, a load sensor, a preload sensor, or the like.

  On the outer periphery of the outer member 42, there is a signal transmission unit (not shown) for wirelessly transmitting a detection signal of the magnetic field sensor 54, a rectenna and a power supply circuit (none of which are shown). 61B is provided, and the sensor unit bearing inner 61A and the sensor unit bearing outer 61B are integrated to form a sensor unit 61. The wireless sensor system is configured by the sensor unit 61 and the external sensor receiver 12 as in the wireless sensor system of FIG. The sensor receiver 12 is attached to the vehicle body side, and a signal received by the sensor receiver 12 is sent as a sensor signal to the ECU of the vehicle body, and used for various controls and abnormality monitoring.

  According to the wheel bearing device of this configuration, the power wirelessly transmitted from the sensor receiver 12 is received by the rectenna shown in FIGS. 1 to 3 and supplied as the power source for the sensors 52 and 62. Further, the sensor unit 61 having the rectenna and the sensors 52 and 62 can be downsized, and the sensor unit 61 can be easily mounted with a small installation space. Thereby, the assembly man-hour of the wheel bearing device can be reduced, and the degree of freedom in design can be increased.

  In this embodiment, the rotation of the wheel is detected by the rotation sensor 52 including the pulsar ring 53 and the magnetic field sensor 54, and the power is supplied to the rotation sensor 52 wirelessly. The wheel rotation can be detected, and the performance of automobile control such as an anti-lock brake system and traction control can be improved. Furthermore, as described in the embodiment of FIG. 6, for example, if the rotation direction of the wheel is also detected by providing two magnetic field sensors 54 of the rotation sensor 52, the detection signal of the rotation sensor 52 is used as a hill hold control or the like. Can also be used. In addition to the rotation sensor 52, another sensor 62 is provided, so that it is possible to detect information other than rotation, such as the load and temperature in the bearing, and it is possible to make the bearing intelligent. It can be used for various vehicle controls.

(A)-(C) are each perspective views seen from the surface side of the rectenna concerning this 1st Embodiment of this invention, a side surface side, and a back surface side. It is a block diagram which shows schematic structure of the same rectenna. It is a circuit diagram of the same rectenna. (A)-(C) are each perspective views seen from the surface side, side surface side, and back surface side of the rectenna concerning other embodiment of this invention. It is a block diagram which shows schematic structure of the wireless sensor system using the rectenna of this invention. It is explanatory drawing which shows schematic structure of the bearing apparatus provided with the same wireless sensor system. It is sectional drawing of the wheel bearing apparatus provided with the same wireless sensor system.

Explanation of symbols

1 ... Rectenna 2 ... antenna (reception means)
3. Rectifier circuit (rectifier means)
7 ... Substrate 7a ... Substrate surface (antenna surface)
DESCRIPTION OF SYMBOLS 9 ... Reflector 10 ... Dielectric 13, 13A, 13B, 62 ... Sensor 13C, 52 ... Rotation sensor 21A, 21B ... Bearing apparatus 41 ... Wheel bearing apparatus

Claims (7)

  In a rectenna having a receiving means for receiving radio waves and a rectifying means for rectifying the power received by the receiving means, a dipole antenna having a folded or bent tip is used as the receiving means. Rectena to do.   The rectenna according to claim 1, wherein the dipole antenna is formed on a dielectric substrate.   3. The rectenna according to claim 1 or 2, wherein a reflector is provided at a position spaced a predetermined distance from an antenna surface on which the dipole antenna and the rectifying means are formed.   4. The rectenna according to claim 3, wherein a dielectric is interposed between the antenna surface on which the dipole antenna and rectifying means are formed and the reflector.   The wireless sensor system provided with the rectenna of any one of Claim 1 thru | or 4, and the sensor electrically fed by this rectenna.   A bearing device with a rectenna, wherein the rectenna according to any one of claims 1 to 4 is mounted on a bearing.   An outer member having a double-row raceway surface on the inner periphery, an inner member having a raceway surface facing the raceway surface, and a rolling element interposed between the raceway surfaces of both rows, and a wheel with respect to the vehicle body A bearing device for a wheel that rotatably supports the vehicle, comprising: a sensor that detects a detection target; and a rectenna that feeds power to the sensor; and the rectenna according to any one of claims 1 to 4. A rectenna-equipped wheel bearing device using the rectenna described in 1.

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