JP2004326158A - Sensor device for tire mounting, and sensor-mounted tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor device for mounting a tire and a sensor-mounted tire which can reduce the deterioration of communication quality caused by a multipath of an electromagnetic wave. <P>SOLUTION: The sensor device 20 which is mounted on the tire 10, detects air pressure inside the tire and transmits a detection result to outside the tire 10 by the electromagnetic wave is provided with an antenna having directivity whose level ratio (front to back ratio:F/B) between a maximum point of a main beam and a maximum point in a range on a rear side is larger than "1". The sensor device 20 is fixed to a rim 15 so that a radiation direction of the electromagnetic wave becomes a circumferential direction of the tire 10. Since the sensor device for tire mounting is provided with the antenna having directivity whose front to back ratio is larger than "1", the direction 30 of the electromagnetic wave radiated from the antenna becomes a specified direction. Thus, a reception direction of the electromagnetic wave on a reception side can be specified, and reception probability can be improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tire-mounted sensor device and a sensor-mounted tire, and more particularly to a tire-mounted sensor device and a sensor-mounted tire that can reduce deterioration of communication quality due to multipath of electromagnetic waves.
[0002]
[Prior art]
Conventionally, when trying to identify or obtain information on physical quantities such as tire internal pressure, temperature, rotation speed, etc., when receiving electrical oscillation energy from a position distant from a specific tire, it was embedded in that tire A technique of transmitting a signal from a transponder (sensor device) is known.
[0003]
The transponder is composed of an integrated circuit and an outer shell for protecting the integrated circuit, and has various shapes such as a small coin shape or a cylindrical shape.
[0004]
An example of this kind of technology is disclosed in Japanese Utility Model Laid-Open No. 2-123404. In this technique, the embedding position of the transponder in the tire is set at the central portion of the carcass ply winding-up end level or on the carcass ply outer surface of the buttress portion. The first and second electrodes formed by the two wires drawn from the transponder are used as an antenna.
[0005]
As another example, Japanese Unexamined Utility Model Publication No. Hei 7-13505 discloses a pneumatic tire equipped with a transponder. This is an improvement on the technique described above. In this pneumatic tire, a pocket for storing a transponder is provided in a raised portion provided on the inner peripheral surface of the bead portion of the toroidal tire.
[0006]
As a result, the raising and lowering portion having the transponder storage pocket is provided in the bead portion, which deviates from the portion constituting the tire and has little movement during running on the inner peripheral surface of the tire, has no adverse effect on the tire and has no adverse effect on the tire. The transponder can be freely moved in and out of the vehicle, so that the stored transponder can be inspected freely or replaced when necessary. This transponder uses a coil wound in a cylindrical shape as an antenna.
[0007]
[Patent Document 1]
JP-A-2-123404 [Patent Document 2]
Japanese Utility Model Publication No. Hei 7-13505
[Problems to be solved by the invention]
However, since the wire antenna and the coil antenna as described above are omnidirectional and have a front-to-back ratio (F / B) of about 1, in a tire mounting sensor device having such an antenna, the sensor device has The radiated electromagnetic waves are scattered on a metal wall of a tire house, a road surface, or the like, and multipaths are caused, thereby causing a decrease in the reception probability on the receiving side. That is, a signal due to an electromagnetic wave radiated from the tire mounting sensor device cannot be accurately received on the receiving side due to the occurrence of multipath.
[0009]
In view of the above problems, an object of the present invention is to provide a tire mounting sensor device and a sensor mounting tire capable of reducing deterioration of communication quality due to multipath of electromagnetic waves and the like.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a tire mounting sensor device mounted on a tire, having a sensor for detecting a physical quantity inside the tire, and transmitting a detection result by the sensor to the outside of the tire by electromagnetic waves. The present invention proposes a tire mounting sensor device including an antenna having a directivity in which a level ratio (front-to-back ratio: F / B) between a maximum point of a main beam and a maximum point in a range on a rear side thereof is larger than 1.
[0011]
Since the tire mounting sensor device of the present invention includes the antenna having the directivity whose front-to-back ratio is greater than 1, the direction of the electromagnetic wave radiated from the antenna is in a specific direction, so that the reception of the electromagnetic wave on the receiving side is performed. Since the direction can be specified, the reception probability can be improved.
[0012]
Further, the present invention, in the tire mounting sensor device of the above configuration, including an insulating circuit board mounted with electronic components, the antenna has a plurality of elements arranged in parallel with the circuit board, The present invention proposes a tire mounting sensor device in which the antenna is covered by an insulating member.
[0013]
In the tire mounting sensor device of the present invention, since the plurality of elements of the antenna are arranged in parallel with the circuit board, the height from the circuit board to the top of the antenna can be set low. The overall shape can be reduced in size.
[0014]
Further, according to the present invention, in the tire mounting sensor device having the above-described configuration, the antenna is mounted on the circuit board such that the directionality of the electromagnetic wave radiated from the antenna is parallel to the circuit board. A sensor device for mounting a tire is proposed.
[0015]
In the tire mounting sensor device according to the present invention, the direction of the directivity of the electromagnetic wave radiated from the antenna is parallel to the circuit board, so that the circuit board is less susceptible to electrical influences.
[0016]
Further, according to the present invention, in the tire mounting sensor device having the above-described configuration, the antenna is provided with a radiator arranged on one semicircle on a circumference in a virtual plane and a reflector arranged on the other semicircle on the other side. Wherein the radiator comprises a loop-shaped first element having both ends arranged at predetermined intervals in a direction perpendicular to the virtual plane and folded in a U-shape; And a power supply unit provided at both ends of the first element and the first element with respect to the power supply unit, and both ends are disposed at predetermined intervals in a direction perpendicular to the virtual plane and U The reflector comprises a loop-shaped second element folded back into a U-shape, and the reflector is folded back into a U-shape with both ends arranged at predetermined intervals in a direction perpendicular to the virtual plane. Loop-shaped third element And connecting portions provided at both ends of the third element, and symmetrically disposed with the third element with respect to the connecting portion, and at predetermined intervals in a direction perpendicular to the virtual plane. The power supply unit includes a fourth element having both ends disposed and folded in a U-shape, wherein the power supply unit connects first and second ends of the first element and the second element so as to cross each other. 2 inductor, and a third inductor electromagnetically coupled with the first and second inductors and having both ends connected to a feeder line, wherein the connection portion is provided at both ends of the third element and both ends of the fourth element. A sensor device for mounting a tire, comprising fourth and fifth inductors connected to cross each other, is proposed.
[0017]
In the tire mounting sensor device of the present invention, a radiator is configured by the first element and the second element, and a reflector is configured by the third element and the fourth element. Directivity occurs in the extending linear direction, and F / B becomes 1 or more.
[0018]
Further, the present invention proposes the tire mounting sensor device having the above configuration, wherein the sensor includes a pressure sensor for detecting an air pressure in the tire.
[0019]
In the tire mounting sensor device of the present invention, the air pressure in the tire is detected by the pressure sensor, and the detection result is transmitted by electromagnetic waves via the antenna.
[0020]
The present invention also provides a sensor-equipped tire having a sensor for detecting a physical quantity inside the tire, and a sensor device for transmitting a detection result by the sensor to the outside of the tire by electromagnetic waves, wherein the sensor device includes a main beam. An antenna having a directivity having a level ratio (front-to-back ratio: F / B) between the maximum point and the maximum point in the range on the rear side thereof is greater than 1, and the direction of the antenna is centered on the rotation axis of the tire. A sensor mounting tire in which the antenna is arranged so as to be in a circumferential direction of a circle to be formed is proposed.
[0021]
According to the sensor-equipped tire of the present invention, since the sensor device having the antenna having the directivity whose front-rear ratio is greater than 1 is provided, the electromagnetic wave radiated from the antenna is scattered on the metal wall or the road surface of the tire house. Even if multipath occurs, the direction of the electromagnetic wave radiated from the antenna can be specified, and the receiving direction of the electromagnetic wave with the maximum electric field strength can be specified on the receiving side, thereby improving the reception probability. Further, the present invention proposes a sensor-mounted tire on which the above-described tire-mounted sensor device is mounted.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a partially cutaway perspective view showing a sensor mounting tire according to one embodiment of the present invention, FIG. 2 is an external perspective view showing a sensor device according to one embodiment of the present invention, and FIG. 3 is a side view of the sensor device. In the figure, reference numeral 10 denotes a sensor-equipped tire (hereinafter simply referred to as a tire), which is a well-known tubeless radial tire. 11 is a carcass, 12A and 12B are belts, 13 is an undertread, 14 is a cap tread, 15 is a rim, and 20 is a sensor device fixed to the rim 15.
[0024]
In this radial structure, the carcass 11 has a carcass cord which is arranged at substantially 90 degrees with respect to the circumferential direction, is made of one or two layers of carcass, and has a belt having a cord angle of about 20 to 30 degrees thereon. 12A and 12B are arranged such that the codes cross each other.
[0025]
Further, an undertread 13 and a cap tread 14 are arranged on the belts 12A and 12B in the order described.
[0026]
Here, the rubberized cord layer disposed between the cap tread 14 and the carcass 11 is called a belt in the case of a radial tire, and is called a breaker in the case of a bias tire. That is, in the bias structure, the carcass is arranged at 35 to 45 degrees with respect to the circumferential direction, a plurality of layers of carcass are overlapped so that the cords cross each other, and a breaker for protecting the carcass is arranged thereon. You.
As shown in FIGS. 2 and 3, the sensor device 20 is provided on a circuit board 21 having an insulating property, a sensor device main body 22 and an antenna 23 provided on the circuit board 21, and provided on the back side of the circuit board 21. And a battery 24. Although not shown, the outer periphery of the sensor device 20 is molded with an electrically insulating resin.
[0027]
The sensor device main body 22 is composed of a well-known integrated circuit (IC) and includes a pressure sensor for detecting ambient air pressure, and a transmission circuit for transmitting the detection result as digital data by electromagnetic waves having a frequency of 315 MHz. Is connected to an antenna 22.
[0028]
The antenna 23 is generally called a loop antenna, and includes a radiator 231 and a reflector 232 whose resonance frequency is set to 315 MHz, and a circle supporting the radiator 231 and the reflector 232. A columnar boom 23a is fixed to the circuit board 21 by a columnar support member 23b. The boom 23a is arranged so as to be parallel to the surface of the circuit board 21. Thereby, the direction of the directivity of the electromagnetic wave radiated from the antenna is parallel to the circuit board 21, so that the circuit board 21 is hardly affected by the electromagnetic wave radiation.
[0029]
The radiator 231 is disposed so as to be curved in one semicircular portion on the circumference of a virtual plane parallel to the surface of the circuit board 21, and both ends are spaced apart at predetermined intervals in a direction perpendicular to the virtual plane. A loop-shaped first element 231a that is arranged and folded back into a U-shape, a power supply portion 233 provided at both ends of the first element 231a, and the first element 231a is arranged symmetrically with respect to the power supply portion 233. And a loop-shaped second element 231b whose both ends are arranged at predetermined intervals in a direction perpendicular to the virtual plane and which is folded back into a U-shape.
[0030]
The reflector 232 is disposed in a curved manner in the other semicircular portion on the circumference, and both ends are disposed at predetermined intervals in a direction perpendicular to the virtual plane, and the reflector 232 is folded back into a U-shape. Loop-shaped third element 232a, connecting portions 234 provided at both ends of the third element 232a, and the third element 232a are arranged symmetrically with respect to the connecting portion 234 and perpendicular to the virtual plane. And a fourth element 232b whose both ends are arranged at predetermined intervals in the direction and are folded back into a U-shape.
[0031]
In addition, as shown in FIG. 4, the power supply unit 233 includes a first inductor 233a and a second inductor 233b that connect both ends of the first element 231a and both ends of the second element 231b so as to intersect with each other. A third inductor 233c that is electromagnetically coupled to the two inductors 233a and 233b and has both ends connected to the transmission circuit via a feeder line.
[0032]
The connection portion 234 includes a fourth inductor 234a and a fifth inductor 234b that connect both ends of the third element 232a and both ends of the fourth element 232b so as to cross each other.
[0033]
Further, both ends of the radiator 231 and both ends of the reflector 232 are disposed so as to face each other with a predetermined space therebetween via insulating members 235 and 236. As a result, a capacitive coupling by the capacitances C1 and C2 occurs between the end of the radiator 231 and the end of the reflector 232 that face each other.
[0034]
In the sensor device 20 of the present embodiment, as shown in FIGS. 5 and 6, directivity is generated in a direction from the reflector 232 to the radiator 231, that is, in a linear direction extending from the connection portion 234 to the power supply portion 233, and 30 dB. The above front-to-back ratio (F / B) and a sensitivity of about 1 dB were obtained.
[0035]
The sensor device 20 is fixed to the rim 15 such that the directivity of the antenna 23 is oriented in the circumferential direction of the tire 10 as indicated by a direction 30 in FIG.
[0036]
Next, features and effects of the present embodiment when the tire 10 having the above-described configuration is used will be described with reference to FIG.
[0037]
In the tire 10 of the present embodiment, a sensor device 20 is fixed to the rim 15 so as to have the directivity of the antenna 23 in the circumferential direction. For this reason, since the direction 31 of the electromagnetic wave radiated from the sensor device 20 when the tire 10 rotates while the vehicle is running can be specified, the position where the electromagnetic wave can be received in the tire house 40 with a high electric field strength can be specified. Can be. Therefore, it is possible to reduce the multipath caused by the scattering of the electromagnetic wave on the metal wall or the road surface of the tire house 40, and to greatly reduce the deterioration of the reception probability in the receiving device 50 provided in the tire house 40 as compared with the related art. Communication quality can be improved.
[0038]
Further, since the loop antenna 23 can be formed smaller than a general Yagi antenna, the shape of the sensor device 20 can be reduced.
[0039]
Note that the present invention is not limited to only the configuration of the above-described embodiment. An antenna having directivity is used, and if the direction of the antenna is set so that the directivity is in the circumferential direction of the tire 10, it is almost possible. The same effect can be obtained, and it goes without saying that another directional antenna may be used as the antenna.
[0040]
Further, in the present embodiment, the air pressure in the tire is detected by the sensor device 20 and the detection result is transmitted by an electromagnetic wave. However, a sensor for detecting a physical quantity in the tire other than the air pressure is provided. May be transmitted.
[0041]
【The invention's effect】
As described above, according to the tire mounting sensor device of the present invention, since the front-rear ratio includes the antenna having the directivity greater than 1, the direction of the electromagnetic wave radiated from the antenna is a specific direction. Since the receiving direction of the electromagnetic wave on the receiving side can be specified, the receiving probability can be improved.
[0042]
Further, according to the sensor mounting tire of the present invention, since the front-rear ratio includes the sensor device having the antenna having the directivity larger than 1, the electromagnetic wave radiated from the antenna is applied to the metal wall or the road surface of the tire house. Multipath generated by scattering can be reduced, and even if multipath occurs, the direction of the electromagnetic wave radiated from the antenna can be specified. Since the direction can be specified, there is an extremely excellent effect that the reception probability and the communication quality can be improved.
[Brief description of the drawings]
FIG. 1 is a partially cutaway perspective view showing a sensor mounting tire according to an embodiment of the present invention. FIG. 2 is an external perspective view showing a sensor device according to an embodiment of the present invention. FIG. FIG. 4 is a side view showing a sensor device; FIG. 4 is an electrical configuration diagram showing an antenna according to an embodiment of the present invention; FIG. FIG. 7 is a diagram illustrating the sensitivity and the front-rear ratio of the antenna according to one embodiment. FIG. 7 is a diagram illustrating the features and effects of the sensor-equipped tire according to one embodiment of the present invention.
DESCRIPTION OF SYMBOLS 10 ... Tire mounting tire, 11 ... Carcass, 12A, 12B ... Belt, 13 ... Under tread, 14 ... Cap tread, 15 ... Rim, 20 ... Sensor device, 21 ... Circuit board, 22 ... Sensor device main body, 23 ... Antenna, 23a: Boom, 23b: Supporting member, 231: Radiator, 232: Reflector, 233: Power supply unit, 234: Connection unit, 233a to 233c, 234a, 234b: Inductor, 24 batteries, 40: Tire house, 50: Reception vessel.

Claims (7)

A tire mounting sensor device which is mounted on the tire and has a sensor for detecting a physical quantity inside the tire, and transmits a detection result by the sensor to the outside of the tire by electromagnetic waves.
A tire mounting sensor device comprising: an antenna having a directivity having a level ratio (front-to-back ratio: F / B) between a maximum point of a main beam and a maximum point in a range on a rear side thereof. Comprising an insulating circuit board on which electronic components are mounted,
The antenna has a plurality of elements arranged in parallel with the circuit board,
The tire mounting sensor device according to claim 1, wherein the antenna is covered with an insulating member. The tire mounting sensor device according to claim 1, wherein the antenna is mounted on the circuit board such that a direction of directivity of an electromagnetic wave radiated from the antenna is parallel to the circuit board. . The antenna includes a radiator disposed on one semicircle on the circumference of the virtual plane and a reflector disposed on the other semicircle.
The radiator,
A first element having a loop shape in which both ends are arranged at predetermined intervals in a direction perpendicular to the virtual plane and which is folded back into a U-shape;
Power supply units provided at both ends of the first element;
A second loop-shaped member symmetrically arranged with the first element with respect to the power supply portion, and both ends are arranged at predetermined intervals in a direction perpendicular to the virtual plane and are folded in a U-shape. Consisting of elements,
The reflector is
A loop-shaped third element having both ends arranged at predetermined intervals in a direction perpendicular to the virtual plane and folded back into a U-shape;
Connecting portions provided at both ends of the third element,
A fourth element which is arranged symmetrically with the third element with respect to the connection portion, has both ends arranged at predetermined intervals in a direction perpendicular to the virtual plane, and is folded in a U-shape. Become
The power supply unit,
First and second inductors connecting both ends of the first element and both ends of the second element so as to cross each other;
A third inductor electromagnetically coupled to the first and second inductors and having both ends connected to a power supply line,
The connection unit is
The tire mounting sensor device according to claim 1, comprising fourth and fifth inductors that connect both ends of the third element and both ends of the fourth element so as to cross each other. The tire mounting sensor device according to claim 1, wherein the sensor includes a pressure sensor that detects an air pressure in the tire. A sensor-equipped tire having a sensor that detects a physical quantity inside the tire and having a sensor device that transmits a detection result by the sensor to the outside of the tire by electromagnetic waves,
The sensor device includes an antenna having a directivity in which a level ratio (front-to-back ratio: F / B) between a maximum point of the main beam and a maximum point in a range on a rear side thereof is larger than 1.
The sensor-equipped tire, wherein the antenna is arranged so that the directionality of the directivity of the antenna is a circumferential direction of a circle centered on a rotation axis of the tire. The sensor mounting tire according to claim 6, wherein the sensor device is the sensor device according to any one of claims 1 to 5.

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