Tires equipped with an information gathering device

Abstract

A tire (1) provided with an information gathering device (100) comprising: a sensor (410) that is configured to detect a predetermined physical information; a transmission circuit (400) configured to transmit the physical information detected by the sensor (410); a spiral antenna (450) connected to the transmission circuit (400) and configured to emit a signal comprising the physical information as a radio wave of a specified frequency, wherein the tire (1) has a steel carcass (24); wherein the information acquisition device (100) is provided in an inner space of the tire (1) and is mounted on a rim (4) of the tire (1) such that an angle formed by a spiral axis (C) of the antenna (450) relative to the axis of rotation (x) of the tire (1) is in a range of 0° to 40°, and the information acquisition device (100) is provided in a virtual plane (PL) which includes the spiral axis (C) of the antenna (450) and has a perpendicular line (P) orthogonal to the axis of rotation (x) of the tire (1); and wherein the steel carcass (24) is installed inside the tire (1), in a side surface of the tire (1), such that it extends only in a radial direction around the axis of rotation (x) of the tire (1), the antenna (450) is arranged inside the tire (1), such that the steel carcass (24) is arranged between the antenna (450) and an outside surface of the tire (1), and the gap bounded by an adjacent steel carcass (24) is used to increase the ability to emit the radio waves emitted from the antenna (450) to the outside surface of the tire (1).

Description

[Technical field]

[0001] The present invention relates to a tire equipped with an information retrieval device for transmitting information by means of radio waves using a spiral antenna; in particular, the present invention relates to a tire in which the attenuation of the transmitted radio waves by an information retrieval device is reduced. [Technical background]

[0002] In vehicles, it is usually very important to check and regulate the tire pressure, and cases where tire pressure reaches an abnormal value have very often been the cause of accidents. For this reason, a tire status monitoring system is known (see, for example, patent literature 1) in which each wheel is equipped with a tire information receiving device to detect the air pressure within the tires and transmit this information. The system is equipped with a monitoring device to receive the air pressure information transmitted by each tire information receiving device and to monitor the air pressure in each tire, sending an alarm if there is any irregularity in the air pressure.

[0003] The tire information acquisition devices in this tire status monitoring system are arranged in an internal space formed between the tire and the wheel. The tire information acquisition device has a housing adapted to accommodate, among other things, an air pressure sensor comprising a pressure detection element for detecting the air pressure within the tire, as well as a transmitter for converting the detection result from the air pressure sensor into an electrical signal and for wirelessly transmitting it to the monitoring device.

[0004] The housing is equipped with a ventilation hole, allowing air within the inner space formed between the tire and the wheel to reach the tire pressure sensor. The monitoring device is located near the driver's seat. It receives tire pressure information transmitted by the tire pressure monitoring system and generates a pre-defined alarm for the driver if the tire pressure falls below a predetermined reference pressure. [Standard technical literature][Patent literature]

[0005] [Patent Literature 1] Japanese Patent JP 3962073 B2

[0006] EP 2 474 429 A1 discloses a tire condition detection device and in particular a tire condition detection device for transmitting detection results by means of radio signals to an external receiver, wherein the device is used by being attached to a rim inside a tire.

[0007] US 2006 / 0061463A1 relates to a system for monitoring the pressure in a pneumatic tire mounted on a wheel of a vehicle, wherein the wheel is rotatable about an axis of rotation and defines a plane of rotation perpendicular to the axis of rotation.

[0008] EP 1 818 237 A1 describes a vehicle drive control system that performs the stability control of a vehicle by highly accurate and simple detection of accelerations generated in each tire and detection of a tire-ground contact pattern, a sensor unit and a tire.

[0009] DE 603 ​​19 027 T2 discloses a pneumatic tire to which at least one receiving antenna of a receiving device is assigned, the receiving device comprising at least one transmitting device arranged outside the pneumatic tire. The receiving device and the transmitting device communicate without physical contact via the receiving antenna, which is particularly advantageous since they are in relative motion to each other.

[0010] JP 2010-179 888 A describes a pneumatic tire with a sound-absorbing element and a wireless label on an inner surface of the tire, wherein the sound-absorbing element consists of a nonwoven fabric formed by interlacing fiber filaments.

[0011] US 2010 / 0123584 A1 describes a method for embedding an RFID tag in a pneumatic tire. The RFID tag has extended antennas, preferably spiral-shaped. Inside the tire, the tag is oriented so that one longitudinal axis of the dipole antenna is perpendicular to the cord threads of a tire ply. [Disclosure of the invention][Problems solved by the invention]

[0012] However, a housing where the information gathering device is located, for example in an inner space of a larger tire, may cause the radio waves to be blocked by a metal element (a steel carcass or the like) inserted into the tire to increase its strength, or it may cause a dramatic attenuation of the transmitted radio waves that reach the outside of the tire.

[0013] An objective of the present invention is to provide a tire equipped with an information acquisition device in an inner space of the tire in such a way that the attenuation of the transmitted radio waves, which are transmitted to the outside of the tire, is reduced. [Means used to solve the above-mentioned problems]

[0014] The present invention proposes, for the purpose of achieving the aforementioned objective, a tire equipped with an information acquisition device comprising: a sensor configured to detect predetermined physical information; a transmission circuit configured to transmit the physical information detected by the sensor; a spiral antenna connected to the transmission circuit and configured to emit a signal comprising the physical information as a radio wave of a specific frequency, wherein the tire has a steel carcass;wherein the information gathering device is provided in an inner space of the tire such that an angle formed by a spiral axis of the antenna relative to the axis of rotation of the tire is in a range of 0° to 40°, and the information gathering device is provided in a virtual plane that includes the spiral axis of the antenna and has a perpendicular line orthogonal to the axis of rotation of the tire; and; wherein the steel carcass is installed inside the tire, in a side surface of the tire, so that it extends only in a radial direction around the axis of rotation of the tire, the antenna is arranged inside the tire, so that the steel carcass is located between the antenna and an outside of the tire, and the gap limited by an adjacent steel carcass is used to increase the ability to emit the radio waves emitted from the antenna to the outside of the tire.

[0015] In a case where a steel carcass is incorporated into a tire, such as a tire for a large vehicle, a steel carcass incorporated into a tire sidewall is arranged such that it extends only in the tire's radial direction. Therefore, in a case where the present invention is adapted to a tire for a large vehicle, the gap bounded by an adjacent steel carcass can be used to enhance the ability to emit the radio waves emitted from the antenna to the outside of the tire.

[0016] In particular, an arrangement of the antenna such that the direction of the emitted electric field from the antenna is maximally orthogonal to the direction of the steel carcass extending in the tire radial direction reduces the blocking of radio waves by the steel carcass and makes it possible to suppress the extent to which the transmitted radio waves emitted to the outside of the tire are attenuated. [Effect of the invention]

[0017] According to the present invention, the emission efficiency of the radio waves emitted from an antenna to the outside of the tire can be improved, and the attenuation of the transmitted radio waves can be reduced. [Brief description of the drawings] Fig. Figure 1 is a view illustrating a tire loaded with a tire information acquisition device in an embodiment of the present invention; Fig. Figure 2 is a view illustrating a tire structure in one embodiment of the present invention; Fig. Figure 3 is an external perspective view illustrating an information gathering device in an embodiment of the present invention; Fig. Figure 4 is a top view illustrating an information gathering device in an embodiment of the present invention; Fig. Figure 5 is a side cross-sectional view illustrating an information gathering device in an embodiment of the present invention; Fig. Figure 6 is an external perspective view illustrating a device main body in an embodiment of the present invention; Fig. Figure 7 is an external perspective view illustrating a device main body in an embodiment of the present invention; Fig. Figure 8 is an external perspective view illustrating a device main body in an embodiment of the present invention; Fig. Figure 9 is a top view which schematically illustrates a first printed wiring provided on a device main body in an embodiment of the present invention; Fig. Figure 10 is a top view which schematically illustrates a second printed wiring provided on a device main body in an embodiment of the present invention; Fig. 11 is a drawing of a superimposed illustration of the Fig. 9 and Fig. 10 in an embodiment of the present invention; Fig. 12 is a view illustrating the arrangement of a column-like connecting conductor provided on a device main body in an embodiment of the present invention; Fig. Figure 13 is a block diagram illustrating the electrical circuit of an information retrieval device in an embodiment of the present invention; Fig. Figure 14 is an external perspective view illustrating a planar conductive plate and a retaining element in an embodiment of the present invention; Fig. Figure 15 is an external perspective view illustrating a holding element in an embodiment of the present invention; Fig. Figure 16 is a perspective view illustrating the arrangement of an antenna in relation to a tire rotation axis in an embodiment of the present invention; Fig. Figure 17 is a top view illustrating the arrangement of an antenna in relation to a tire rotation axis in one embodiment of the present invention; Fig. Figure 18 is a top view illustrating the arrangement of an antenna in relation to a tire rotation axis in one embodiment of the present invention; Fig. Figure 19 is a view illustrating a relationship between a steel carcass and an emitted electric field of a spiral antenna in an embodiment of the present invention; Fig. Figure 20 is a view illustrating a characteristic curve representing an emission change quantity in one embodiment of the present invention; Fig. Figure 21 is a view illustrating another example of a configuration for a spiral antenna; Fig. Figure 22 illustrates a different example of a configuration for a spiral antenna; and Fig. Figure 23 is a view illustrating a characteristic curve representing an emission change quantity in an embodiment of the present invention. [Preferred embodiments of the invention]

[0018] The following is a description of an embodiment of the present invention with reference to the accompanying drawings.

[0019] Fig. Figure 1 is a view illustrating a tire loaded with a tire information acquisition device in an embodiment of the present invention; and Fig. Figure 2 is a view illustrating a tire structure in one embodiment of the present invention;

[0020] As in Fig. Figure 1 illustrates a tire 1 according to the present embodiment comprising a tire body 2, a rim 4, a wheel 5 and an information acquisition device 100. The information acquisition device 100 is attached to an outer peripheral surface of the rim 4, and the information acquisition device 100 is provided on the inside of an air chamber 3 of the tire 1.

[0021] The information gathering device 100 is equipped with a sensor part that has a pressure detection element and a temperature detection element, as described below, and the sensor part detects the pressure and temperature inside the air chamber 3.

[0022] The Information Acquisition Device 100 converts the temperature and pressure detection results into digital values ​​and generates and transmits digital information including these digital values. In addition to the digital values ​​of the temperature and pressure detection results within air chamber 3, the digital information also includes identification information that uniquely identifies the Information Acquisition Device 100.

[0023] The tire 1 according to the present embodiment is typically used in a large truck, a bus, a construction vehicle, or a similarly sized vehicle. The tire 1 is, for example, a known tubeless radial tire. As in Fig. Figure 2 illustrates that steel belts 23A, 23B (steel belts) and a steel carcass 24 (steel carcass) are incorporated into the tire 1 (the tire body 2). The tire body 2 comprises, among other things, a known top tread 21, a bottom tread 22, the belts 23A, 23B, the carcass 24, and the like.

[0024] Fig. Figure 3 is an external perspective view of the information gathering device 100. Fig. Figure 4 is a top view of the information gathering device 100, and Fig. 5 is a side cross-sectional view (a cross-sectional view of line VV in Fig. 4) of the information gathering device 100. For the sake of simplicity, the length direction, width direction, and height direction of the information gathering device 100, which are orthogonal to each other, shall be referred to below as the front-back direction, the left-right direction, and the up-down direction, respectively, and the arrangement of each of the parts shall be described in accordance with these definitions. The front-back direction, for example, corresponds to the direction of travel of tire 1, and the left-right direction corresponds, for example, to the direction of rotation of tire 1.

[0025] As in Fig. As illustrated in Figure 3, the information gathering device 100 is equipped at its outermost part with a housing 130 of an essentially cuboid shape extending in the front-to-back direction. "Of an essentially cuboid shape" refers to a cuboid shape or a substantially cuboid form and includes such shapes that are basically identical to a cuboid. As shown in the Fig. 3 and Fig. As illustrated in Figure 4, the housing 130 is formed from a main housing body 131, the upper surface of which is open, and a cover body 132, which is attached to the upper surface of the main housing body 131. The main housing body 131 has a projecting part 131a for screwing onto each of the two front and rear end pieces, and correspondingly, the cover body 132 also has a projecting part 132a onto each of the two front and rear end pieces.

[0026] As in Fig. As illustrated in Figure 5, a compartment 134 is formed inside the housing 131 to accommodate a device main body 300. A screw hole 131b is provided on the projecting parts 131a of the device main body 131, and screws 141, which pass through the projecting part 132a of the cover body 132, are screwed into the screw holes 131b, with the cover body 132 being screwed to the upper surface of the housing 131. The opening of the upper surface of the compartment 134 is thereby closed. A mounting element for the information retrieval device 100 is formed on a base surface 131c of the device main body 131. The information gathering device 100 is attached to the rim 4, the fastening part being brought into contact with an outer peripheral surface of the rim 4 on the base surface 131c.The information gathering device 100 is attached to a rim by an adhesive medium, a fastening strap or the like, or it is attached to a tire valve of the rim 4.

[0027] As in Fig. As illustrated in Figure 4, a ventilation hole 133 is open at a front end of the cover body 132 (further away from the rear end than the projecting part 132a). Air can thus pass between the interior and exterior of the housing 130 through a ventilation hole 133 in the state where the cover body 132 is attached to the main housing body 131, allowing the temperature and pressure of the air within the air chamber 3 to be detected.

[0028] Each of the Fig. 6 and Fig. Figure 7 is an external perspective view of the main device body 300 housed in the casing 130, and Fig. Figure 8 is an external perspective view showing the main parts (on the front section) of the device main body 300. Fig. Figure 6 is a drawing where the main body of the device 300 is seen from a slightly oblique angle above, and Fig. Figure 7 is a drawing where the main body of the device is seen from a slant below.

[0029] As in the Fig. 6, Fig. 7 to Fig. As illustrated in Figure 8, the main body of the device 300 comprises: a first printed circuit board 351 of a substantially rectangular shape corresponding to the shape of the housing space 134 in a top view; a second printed circuit board 352 of a substantially rectangular shape, arranged above the first printed circuit board 351 and separated from the first printed circuit board 351 by a predetermined interval, such that it is substantially parallel to the first printed circuit board 351; a third printed circuit board 353, extending in the top-bottom direction at the rear end of the main body of the device 300 and connecting the rear end of the first printed circuit board 351 and the rear end of the second printed circuit board 352;and a plurality of column-like connecting conductors 354 extending in the top-bottom direction along the front section of the main body of the device 300, connecting the first circuit board 351 and the second circuit board 352. "Substantially rectangular" here refers to a rectangular shape or a substantially rectangular shape, and includes those shapes which are essentially identical to a rectangle. "Substantially parallel" refers to being parallel or substantially parallel, and includes being essentially parallel. The third circuit board 353 and the connecting conductors 354 are each soldered to the first circuit board 351 and the second circuit board 352, respectively.

[0030] A predetermined conductor pattern comprising a plurality of first printed wires 351a extending in the front-to-back direction is formed on the first printed circuit board 351. A predetermined conductor pattern comprising a plurality of second printed wires 352a extending in the front-to-back direction is formed on the second printed circuit board 352. Fig. Figure 9 is a top view schematically illustrating the first printed wiring diagrams 352a; Fig. Figure 10 is a top view schematically illustrating the second printed wiring 352a; and Fig. Figure 11 is a top view that schematically illustrates the positional relationships between the first printed wiring 351a and the second printed wiring 352a (a drawing of the superimposed representation of the Fig. 9 and Fig. 10). The Fig. 9, Fig. 10 to Fig. Figure 11 shows four of each of the first printed wiring diagrams 351a and the second printed wiring diagrams 352a, but the number of printed wiring diagrams 351a, 352a is not limited to this.

[0031] As in Fig. As shown in Figure 9, a plurality (here, four) of connecting elements C11-C14 are provided at regular intervals in the left-right direction on the front end of the first printed circuit board 351. Furthermore, a plurality (here, four) of connecting elements C15-C19 are provided at regular intervals in the left-right direction on the first printed circuit board 351, at positions that are spatially separated from the connecting elements C11-C14 by a predetermined distance L0. The first printed wiring connections 351a are arranged such that they extend from C11 to C15, from C12 to C16, from C13 to C17, and from C14 to C18. The first printed wiring connections 351a are arranged parallel to each other and at regular intervals in the left-right direction.

[0032] As in Fig. As illustrated in Figure 10, a plurality (here, four) of connecting elements C21-C24 are provided at regular intervals in the left-right direction on the front end of the second printed circuit board 352. Furthermore, a plurality (here, four) of connecting elements C24-C28 are provided at regular intervals in the left-right direction on the second printed circuit board 352, at positions spatially separated from the connecting elements C21-C24 by a predetermined distance L0. The second printed wiring assemblies 352a are arranged such that they extend from C21 to C25, from C22 to C26, from C23 to C27, and from C24 to C28. The second printed wiring assemblies 352a are arranged parallel to each other and at regular intervals in the left-right direction.

[0033] As in Fig. As illustrated in Figure 11, the connecting elements C11-C14 of the first printed circuit board 351 and the connecting elements C21-C24 of the second printed circuit board 352 are arranged in identical positions relative to each other in a top view. The connecting elements C16-C19 of the first printed circuit board 351 and the connecting elements C25-C28 of the second printed circuit board 352 are also arranged in identical positions relative to each other in a top view. The first printed wires 351a and the second printed wires 352a are connected to each other by the connecting elements C11-C19, C21-C28, and the overall configuration forms a zigzag shape.

[0034] As in the Fig. 6, Fig. 7 to Fig. As illustrated in Figure 8, the multitude of column-like connecting conductors 354 are arranged separately at the front and rear so that they correspond to the positions of the connecting parts C11-C19, C21-C28. Fig. Figure 12 is a drawing showing the main body of the device 300 from the front and illustrates, in principle, the arrangement of the column-like connecting conductors 354. Fig. In Figure 12, the left-right positioning of the front-side connection conductors 354 (called first connection conductors 354a) and the left-right positioning of the back-side connection conductors 354 (called second connection conductors 354b) are offset from each other, but the printed wirings 351a and 352a can also be shaped so that the left-right positioning of the two overlaps. The length of each of the connection conductors 354 is equal to the distance H0 between the first printed circuit board 351 and the second printed circuit board 352. Four of each of the first connection conductors 354a and second connection conductors 354b are provided; in total, eight connection conductors 354 are provided. The number of connection conductors 354 is determined in accordance with the number of first printed wirings 351a and second printed wirings 352a and is not limited to eight.

[0035] As in Fig. As illustrated in Figure 12, the upper and lower ends of each of the first connecting conductors 354a are soldered to the connecting parts C21-C24 of the second circuit board 352 and the connecting parts C11-C14 of the first circuit board 351, respectively. The upper and lower ends of each of the second connecting conductors 354b are soldered to the connecting parts C25-C28 of the second circuit board 352 and the connecting parts C16-C10 of the first circuit board 351, respectively.

[0036] This, as in the Fig. 6, Fig. 7 to Fig. As illustrated in Figure 8, the first printed wires 351a and the second printed wires 352a are connected to each other by the connecting conductors 354, and a helically wound antenna 450 is formed by the first printed wires 351a, the second printed wires 352a, and the connecting conductors 354. More specifically, the upper and lower ends of each of the connecting conductors 354 are connected to the first printed wires 351a and the second printed wires 352a, forming a spiral antenna 450 overall. Here, "spiral" refers not only to conductors wound along a cylindrical surface but also includes conductors wound along the side faces of a cuboid, as in the present embodiment.More precisely, the helically shaped antenna 450, which is formed when the first printed wires 351a, the first connecting conductors 354a, the second printed wires 351b and the second connecting conductors 354b are connected to each other in the specified order, can be shaped according to a curve or a curved straight line.

[0037] The starting point of the antenna 450 helix, formed from the first printed wires 351a, the second printed wires 352a, and the connecting conductors 354, is the junction C15 at the right rear end of the first printed circuit board 351, and its endpoint is the junction C19 at the left rear end of the first printed circuit board 351. These junctions C15 and C19 are connected to a conductor pattern (current source circuit or the like) of the first printed circuit board 351, and current flows to the antenna 450 through the junctions C15 and C19.An axis passing through the center of the cuboid space enclosed by the first printed wiring 351a, the second printed wiring 352a, the first connecting conductors 354a and the second connecting conductors 354b, that is, a spiral axis C passing through the center of the spiral antenna 450, extends in the left-right direction (the latitude direction of the information gathering device 100), as in . Fig. 11 illustrated.

[0038] As in the Fig. 6, Fig. 7 to Fig. As illustrated in Figure 8, the antenna 450 is formed at the front end of the main body of the device 300; at the rear end of the main body of the device 300, a sensor part 410 and an electrical cell 420 or a similar electronic component are mounted. The sensor part 410 and the electrical cell 420 form an electrical circuit.

[0039] Fig. Figure 13 is a block diagram illustrating the electrical circuit of the Information Retrieval Device 100. As shown in Fig. As illustrated in Figure 13, the main body of the device 300 includes a detection and transceiver circuit 400. The detection and transceiver circuit 400 is configured to include the sensor 410, the electrical cell 420, a main control unit 430, a transceiver unit 440, and an antenna 450.

[0040] As in Fig. As illustrated in Figure 7, the sensor part 410 is applied to the surface of the device main body 300 (the lower surface of the first circuit board 351). As shown in Fig. As illustrated in Figure 13, the sensor part 410 consists of an air pressure detection element 411, a temperature detection element 412, and an analog-to-digital conversion circuit 413. The sensor part 410 detects the air pressure and temperature inside, for example, an air chamber of a pneumatic fender, using the air pressure detection element 411 and the temperature detection element 412, converts the detection result into digital values ​​using the analog-to-digital conversion circuit 413, and outputs them to the main control unit 430.

[0041] The electrical cell 420 is connected to the main body of the device 300 by a connecting conductor (not shown) and supplies power to the detection and transmit-receiver circuit 400 of the main body of the device 300.

[0042] The main control unit 430 consists of a known main processor, memory, and the like. The main control unit 430 receives the detection results from the sensor part 410 as digital values ​​and generates digital information comprising these digital values, which it then outputs to the transmitter / receiver unit 440. In addition to the digital values ​​of the detection results, the digital information also includes preset identification information unique to the main device body 300 (which has either been previously written to memory or set by a dual in-line package (DIP) switch).

[0043] The transmitter-receiver unit 440 switches between transmitting and receiving based on a command from the main control unit 430. During transmission, the transmitter-receiver unit uses radio waves of a predetermined frequency, for example, 315 MHz, to transmit digital information received from the main control unit 430 via the antenna 450. During reception, the transmitter-receiver unit 440 detects the digital signal from radio waves of the predetermined frequency (315 MHz) received by the antenna 450, extracts the digital information from the detected digital signal, and outputs it to the main control unit 430. The transmit frequency and the receive frequency of the transmitter-receiver unit 440 are both set to the same frequency.

[0044] The antenna 450 is a spiral antenna with a resonant frequency set to the transmitter reception frequency of the transmitter / receiver unit 440. As described above, the antenna 450 is formed from the first printed wires 351 provided on the first circuit board 351, the second printed wires 352a provided on the second circuit board 352, and the column-like connecting conductors 354 for electrically connecting the first printed wires 351a and the second printed wires 352a and for fastening the circuit boards 351 and 352 to one another.

[0045] As in Fig. As illustrated in Figure 8, a rectangular, planar conductive plate 361 is attached to the lower surface of the first printed circuit board by four retaining elements 371. The planar conductive plate 361 is positioned below the antenna 450 so that it is parallel to the first printed circuit board 351, which is located on the bottom surface of the housing main body 351 when the device main body 300 is housed within the enclosure 130. A predetermined gap D is maintained between the planar conductive plate 361 and the first printed circuit board 351 by the retaining elements 371. The planar conductive plate 361 is electrically connected to a predetermined conductor pattern of the first printed circuit board 351 (to a conductor pattern connected to a negative electrode of the electrical cell 420) and is set to a reference potential.

[0046] Fig. Figure 14 is a perspective view where the planar conducting plate 361 is viewed from an oblique angle above, and Fig. Figure 15 is a perspective view of the support elements 371. As in Fig. As illustrated in Figure 14, each of the retaining elements 371 is provided to be attached to each of the four corners of the upper surface of the planar conductive plate 361. As shown in Fig. As illustrated in Figure 15, the retaining elements 371 have a column-shaped main body 371a and a pair of column-shaped projecting parts 371b of a smaller diameter than that of the main body 371a, the projecting parts being designed to protrude from both end surfaces of the main body 371a. One of the projecting parts 371b engages in a recess or through-hole provided at the four corners of the planar conductive plate 361, thereby joining the planar conductive plate 361 and the retaining elements 371. The other of the projecting parts 371b engages in a recess or through-hole provided in the first circuit board 351, thereby fastening the planar conductive plate 361 to the first circuit board 351 by the retaining elements 371.

[0047] In a state where the planar conductive plate 361 is attached to the first conductive plate 351, the resonant frequency of the antenna 450 is, for example, 315 MHz. The antenna impedance at 315 MHz is 50 Ω. The gap D ( Fig. 8) The distance between the first circuit board 351 and the planar conductive board 361 is set to, for example, 1.5 mm at such a time using the retaining elements 371.

[0048] The description now refers to the arrangement of the information gathering device 100, which is designed within the tire 1 as described above. Fig. Figure 16 is a three-dimensional view of the arrangement of the antenna 450 according to the present embodiment, and the Fig. 17 and Fig. Figure 18 are top views illustrating the arrangement of antenna 450. Fig. Figure 19 is a view of the three-dimensional representation of the relationship between the steel carcass 24 inside the tire 1 and the emitted electric field of the spiral antenna 450.

[0049] The Fig. 17 and Fig. Figure 18 illustrates the arrangement of the 450 antenna on a virtual plane PL, as in Fig. As shown in Figure 16, the virtual plane PL is defined as a plane encompassing the spiral axis C of the antenna 450 and having a perpendicular line P orthogonal to the rotation axis x of the tire 1. As shown in the Fig. 16, Fig. 17 to Fig. As illustrated in Figure 18, the information gathering device 100 is arranged inside the tire 1 such that the angle formed by the spiral axis C relative to the tire rotation axis x is within a range of 0° ± 40° in the virtual plane PL. Here, as in Fig. As illustrated in Figure 19, the emitted electric field (Eφ) from antenna 450 is generated circumferentially around the spiral axis C. Fig. Figure 19 illustrates an antenna arranged such that the spiral axis C is parallel to the tire rotation axis x as “450a”, and illustrates an antenna arranged such that the spiral axis is orthogonal to it as “450b”.

[0050] If the spiral axis C is set at 0° relative to (parallel with) the rotation axis x of tire 1, as in the Fig. 17 and Fig. 19 (450a in Fig. 19) illustrated, then an electric field (Eφ) orthogonal to the steel carcass 24 is present. This orthogonal component is emitted to the outside of the tire without being influenced by the presence of the steel carcass 24. Conversely, if the spiral axis C is at 90° relative to the rotation axis x of the tire 1 (450b in Fig. 19) is set, the entire electric field (Eφ) is parallel with the steel carcass 24, and therefore the emission of the electric field to the outside is significantly reduced.

[0051] Fig. Figure 20 illustrates the properties of an emission change quantity that has been measured in practice. Fig. The vertical axis represents the emission change (dB), and the horizontal axis represents the number of steel carcasses 24 incorporated into the tire sidewall. If, for example, the information gathering device 100 was positioned such that the spiral axis of the antenna 450 is parallel to the tire rotation axis x, then the emission change was determined as shown by curve A in Fig. 20 illustrated, measured. In contrast, when the information gathering device 100 was arranged such that the spiral axis C of the antenna 450 formed a 90° angle relative to the tire rotation axis x, the emission change quantity, as shown by curve B in Fig. Figure 20 illustrates and measures were taken. In this way, when the information gathering device 100 was arranged so that the spiral axis C was parallel to the tire rotation axis x, the emission change was successfully improved by approximately 6 dB compared to the case when the information gathering device was arranged so that the spiral axis C formed a 90° angle relative to the tire rotation axis x.

[0052] According to the above, the angle formed by the spiral axis C relative to the tire rotation axis x is preferably closer to 0°. However, provided that the angle formed by the spiral axis C relative to the tire rotation axis x is in the range of ±40°, although the emission change decreases below curve A, the amount of reduction can be kept below 2 dB. For this reason, in a case where the angle formed by the spiral axis C relative to the tire rotation axis x is ±40°, as in Fig. Figure 18 illustrates that the emission change is still significantly different compared to curve B in Fig. The number will be reduced by 20.

[0053] In the tire 1 equipped with the information acquisition device 100 according to the present embodiment, as described above, the information acquisition device 100 is arranged within the tire 1 such that the angle formed by the spiral axis C of the antenna 450 relative to the tire's axis of rotation x is within ±40°. In a tire 1 in which a steel carcass 24 has been incorporated, as in a tire 1 for a large vehicle, the steel carcass 24, which is incorporated into the tire's sidewall surface, is arranged such that it extends in the tire's radial direction. In particular, the steel carcass is arranged on a plane that encompasses the tire's axis of rotation x.For this reason, the tire sidewall surface is less likely to interfere with a magnetic current forming a magnetic field in the spiral antenna 450, which is a magnetic field antenna, in contrast to a tread section (the top tread 21) where the steel carcasses 23A, 23B, and the steel carcass 24 are embedded. As a result, the blocking of radio waves emitted by the antenna 450 by the steel carcass 24 is reduced, and the attenuation of the transmission of radio waves emitted to the outside of the tire 1 can be decreased. This makes it possible to increase the distance of radio wave transmission / reception between the information gathering device 100 and a device that has a communication function on the outside of the tire.

[0054] In the embodiment described above, the information gathering device 100 was configured to detect both the air pressure and the temperature inside the tire 1. However, the information gathering device can also be configured to detect either the air pressure or the temperature. It would also be possible to configure the information gathering device to detect other physical quantities that correlate with the air pressure or the temperature inside the tire 1, i.e., other physical quantities that represent the state within the tire 1 or of the tire itself, for example, the temperature of the tire, the amount of deformation in the tire, the acceleration, or the like.

[0055] In the embodiment described above, the antenna 450 of the information retrieval device 100 was configured using the printed patterns of the circuit boards, but the configuration of the antenna 450 is not limited to this. For example, a similar effect can also be achieved by using a rod antenna 460 formed by winding an electrically conductive wire onto a magnetic body, as shown in Fig. 21 is illustrated, or by using a coil antenna 470, where an electrically conductive wire, as in Fig. Figure 22 illustrates that it is simply wound into an air coil. In particular, the configuration of the antenna can be as desired, provided that the information gathering device is designed such that the angle formed by the spiral axis C relative to the tire rotation axis x is within a range of 0 to 40° inside a virtual plane PL that encompasses the spiral axis C of the antenna and has a perpendicular line orthogonal to the rotation axis x of the tire 1.

[0056] Fig. Figure 23 illustrates the relationship between the angle at which the information gathering device 100 is installed (the angle formed by the spiral axis C relative to the tire rotation axis x) and the emission change rate (dB). As in Fig.As illustrated in Figure 23, the emission change rate increases progressively as the angle at which the information gathering device 100 is installed increases. In practical use, the emission change rate is preferably not greater than 2 dB, and this requirement is met whenever the installation angle is in a range of 0 to 40°.

[0057] In the embodiment described above, the information gathering device 100 was attached to the rim 4, but the attachment position of the information gathering device 100 is not limited to this. The information gathering device 100 can be located at a different location than the rim 4, for example, an inner surface of the tire body 2 or elsewhere, in which case an effect similar to the one described above can still be achieved. [Commercial Applicability]

[0058] It is therefore possible to construct a tire equipped in the inner space with an information acquisition device provided with a spiral antenna and a transmission circuit, whereby the emission change quantity of the radio waves from the antenna to the outside of the tire has been reduced, and therefore the distance of the radio wave transmission / radio wave reception between the information acquisition device and a device on the outside of the tire is allowed to be increased. [Legend] 1 tire 2 tire main bodies 3 air chambers 4 rim 100 information gathering devices 130 cases 131 Main housing body 132 lid bodies 133 Ventilation hole 134 Accommodation room 141 screw 300 main device bodies 351 First circuit board 351a First printed wiring 352 Second circuit board 352a Second printed wiring 353 Third circuit board 354 Column-like connecting conductor 361 Planar conducting plate 371 Holding element 400 Detection and transceiver circuit 410 Sensor part 411 Air pressure detection element 412 temperature detection element 413 Analog / digital conversion circuit 420 Electrical Cell 430 Main control unit 440 transmitter / receiver unit 450 antenna

Claims

[1] A tire (1) provided with an information gathering device (100) comprising: a sensor (410) that is configured to detect a predetermined physical information; a transmission circuit (400) configured to transmit the physical information detected by the sensor (410); a spiral antenna (450) connected to the transmission circuit (400) and configured to emit a signal comprising the physical information as a radio wave of a specified frequency, wherein the tire (1) has a steel carcass (24); wherein the information acquisition device (100) is provided in an inner space of the tire (1) and is mounted on a rim (4) of the tire (1) such that an angle formed by a spiral axis (C) of the antenna (450) relative to the axis of rotation (x) of the tire (1) is in a range of 0° to 40°, and the information acquisition device (100) is provided in a virtual plane (PL) which includes the spiral axis (C) of the antenna (450) and has a perpendicular line (P) orthogonal to the axis of rotation (x) of the tire (1); and wherein the steel carcass (24) is installed inside the tire (1), in a side surface of the tire (1), such that it extends only in a radial direction around the axis of rotation (x) of the tire (1), the antenna (450) is arranged inside the tire (1), such that the steel carcass (24) is arranged between the antenna (450) and an outside surface of the tire (1), and the gap bounded by an adjacent steel carcass (24) is used to increase the ability to emit the radio waves emitted from the antenna (450) to the outside surface of the tire (1).

Images