US 20040021559 A1
An improved electronics device for a tire includes a radio device and an antenna intended to be attached to or embedded in a tire, the antenna being shaped to absorb tensile stress applied by the tire, and having a meandering shape. A preferred shape is a sinusoidal wave pattern. The antenna body may be a wire formed of spring steel, brass coated spring steel, or spring brass.
1. An improved electronics device for a tire of a vehicle, comprising:
a radio device for communicating information from said tire with a remote radio device; and,
at least a first antenna wire connected to and extending from said electronics package, wherein, the at least first antenna wire is shaped to have at least one undulation for relieving tension applied in the direction of the at least first antenna wire.
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 Electronic devices integrated in a tire can provide functions such as identification and tracking during manufacture, distribution, and use, and measurement of physical parameters such as pressure and temperature during use of the tire. Many systems utilize radio frequency communication between the tire and the external monitoring or interrogating device. A radio frequency communication link requires one or more antennas.
 Electronics devices that mount to a surface of the tire or the wheel, or are incorporated in the tire inflation valve are available. An electronic device and antenna that is securely attached to a tire structure, for example, by being embedded in the elastomeric material of the tire or attached by means of an elastomeric patch that is bonded to the tire, is desirable. Such mounting or attachment provides a permanent, tamper-proof integration. Integrating an antenna in the tire, however, presents difficulties. A tire undergoes flexing and distortions during normal use that can the antenna to fracture and separate from the electronics device. Further, if the electronics device and antenna are to be integrated with the tire during manufacture and before curing of the tire, the manufacturing process includes many steps, such as shaping and curing, that could cause the wire to break.
 The invention provides an improved electronics device with a radio frequency antenna for integration with a tire that avoids problems in the art. According to the invention, the improved electronics device includes an antenna that is shaped to absorb stresses imposed on it by the tire or tire manufacturing process. According to a preferred embodiment, the antenna is a meandering antenna, having one or more undulations along its length to allow the antenna to stretch along with any stretching of the tire substrate on which the device is mounted. According to another aspect of the invention, the undulations or bending portions of the antenna are substantially perpendicular to the direction in which the antenna extends from the electronics package.
 Other meandering antennas may be used, for example, sine wave shaped, square wave shaped, a single broad undulation, or other shapes capable of absorbing tensile stress imposed on the direction the wire extends from the electronics package.
 The antenna body can be any body capable of transmitting radio frequency energy. Advantageously, and preferably for use in a tire because of its durability under fatigue conditions, the antenna body is a wire formed of spring steel, brass coated spring steel, or spring brass. Such materials are capable of surviving the bending and flexing deformations typically experienced by the tire.
 The invention will be better understood by reference to the following detailed description in conjunction with the appended drawings.
FIG. 1 is an illustration of an electrical device having an antenna in accordance with the invention;
FIG. 2 is a perspective view of a tire showing one placement for an electrical device with an antenna; and,
FIG. 3 is an illustration of an antenna and electronics device showing an alternative embodiment of the antenna;
FIG. 4 is an illustration of an antenna and electronics device showing another alternative embodiment of the antenna having a squared meandering pattern; and,
FIG. 5 is an illustration of an antenna and electronics device showing an alternative embodiment of the antenna having a single broad undulation or swoop shape.
FIG. 1 shows an electronics device 10 for a tire which includes a radio device 12 and an antenna 14 in accordance with the invention. The electronics device 10 itself may be an identification or tracking device, such as may be used in manufacturing, distribution, and sale activities. The device 10 may also be a monitoring device for measuring temperature, pressure or other physical parameters in an operating tire. The radio device 12 is used to transmit information from the electronics device to a remote device (not illustrated) external of the tire, and/or to receive information from the remote device. The antenna 14 in such a device is used to transmit to and/or receive from the external device information by radio frequency. In addition, the antenna may also serve to receive energy from an interrogation device. Such radio devices may operate as receivers, transmitters, transponders or reflectors, and, because the antenna of the invention is useful for all these devices, in the following description, the term “radio device” is intended to be inclusive.
 The antenna 14 is shown as a dipole, having two branches 16, 18 extending from the radio device. The invention may advantageously be used with dipoles, monopoles, or multiple antennas as the transmission and space conditions require.
 The antenna 14 is shaped to meander to provide some longitudinal flexibility (in the direction the antenna extends from the radio device 12) and bending flexibility (in the direction normal to the view shown). The illustrated embodiment of FIG. 1 shows a sinusoidal wave pattern, and is considered a preferred embodiment.
 As shown in FIG. 2, advantageously, the radio frequency device 10 may be positioned in a number of different places in a tire 30. A single tire may include one or several such devices, for example, if it is desired to monitor physical parameters at different locations in the tire or to monitor different parameters. The electronics device 10 may be positioned on the sidewall 32 or at the tread or crown portion 34. The electronics device 10 may be applied under or embedded in a rubber patch (not illustrated) which is adhered to a surface of a tire 14. Alternatively, the radio device 11 and antenna 12 may be embedded in the tire structure itself or layered under rubber material in the tire 14 which forms a surface of the tire. For example, the radio frequency device 10 may be positioned between a carcass ply and an inner liner, between the carcass ply and the sidewall cover, and/or between the belt package and the tread. By “integrated” the inventors refer to any manner of incorporating the antenna 12 and radio device 11 in a tire in a way that positions the device and antenna on or in a surface of the tire.
 Referring now also to FIG. 1, those skilled in the tire art understand that a tire experiences significant deformation during the manufacturing process, from shaping from a cylindrical shape on the tire building drum to the familiar toroidal tire shape, and from pressure during curing. Also, during use of the tire, the sidewall and tread area undergo tensile and compressive forces as that portion of the tire moves into, through, and out of ground contact. A tensile force T is indicated in FIG. 1 being applied in the antenna 14 extension direction. The undulations or curves along the length of the antenna 14 allow it to absorb and relieve tensile force similar to a spring, by permitting some extension along the length of the antenna, length being understood to mean the general direction in which the antenna extends from the radio device. This helps prevent damage or breakage of the antenna 14 when tension is applied, and is a significant advantage for an antenna attached to a tire.
 Other meandering patterns may be used, and may be selected according to the length of antenna needed, the space available in the patch or in the portion of the tire selected for embedding the device, and the material from which the antenna is formed.
FIG. 3 shows an alternative embodiment of the device 10, in which an antenna 20 is shaped with a saw-tooth pattern.
FIG. 4 shows an antenna 22 having a shape similar to a square wave, which may be advantageous if the antenna is printed on a surface.
FIG. 5 shows an antenna 24 having a single undulation or swoop shape.
 The curves or undulations in the various antenna embodiments are directed generally perpendicular to the direction in which the antenna extends from the radio device. The antennas do not encircle the radio device, as this is believed to present additional opportunity for tension to damage the wire.
 The invention has been described in terms of preferred principles, embodiments, and structures for the purposes of description and illustration. Those skilled in the art will understand that substitutions may be made and equivalents found without departing from the scope of the invention as defined by the appended claims.