Valve-integrated transponder

#This application claims benefit of the Japanese Patent Application No. 2007-151633 filed on Jun. 7, 2007, which is hereby incorporated by reference.

#1. Field of the Invention

#The present invention relates to a valve-integrated transponder that is integrated with an air valve fixed to a valve hole of a wheel rim and is disposed in a tire, and that is used in a system for monitoring the air pressure of the tire.

#FIG. 1 illustrates a mounting position of a valve-integrated transponder according to a first embodiment of the present invention inside a tire;

#FIG. 2 is an external view of the transponder shown in FIG. 1 and an air valve;

#FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2;

#Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 illustrates a mounting position of a valve-integrated transponder according to a first embodiment of the present invention inside a tire. FIG. 2 is an external view of the transponder and an air valve. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 illustrates the internal structure of the transponder as viewed from an external-antenna side. FIG. 5 illustrates the internal structure of the transponder as viewed from an air-valve side.

#A valve-integrated transponder 1 shown in these drawings is fitted to one end of a snap-in type air valve 20 and disposed within a tire 30, and is for enabling a driver at the driver seat to monitor the air pressure and temperature inside the tire 30. The transponder 1 has a synthetic-resin casing 10 that houses a detection circuit unit 2 having detecting elements such as a pressure sensor and a temperature sensor, a transmitter/receiver circuit unit 3, a substrate 4 having these circuit units 2 and 3 mounted on a first surface thereof, a shield cover 5 formed of sheet metal that covers both the circuit units 2 and 3, a synthetic-resin supporting member 6 disposed on a second surface of the substrate 4, and an inverse F antenna element 7 that is supported by the supporting member 6 and electrically connected to the transmitter/receiver circuit unit 3. The transponder 1 does not contain a battery power source. Instead, the transponder 1 is configured such that the antenna element 7 is excited by a radio wave from an external antenna 50 (see FIG. 1) provided in the vehicle body. Referring to FIG. 1, the air valve 20 is securely press-fitted in a valve hole 41 of a wheel rim 40, and the casing 10 is attached to an end portion of the air valve 20 that is located within the tire 30, such that the longitudinal direction of the antenna element 7 and the supporting member 6 are set substantially perpendicular to the axial direction of the air valve 20. Consequently, the transponder 1 is disposed within the tire 30 at an outer side of a well 42 of the wheel rim 40 as viewed in the radial direction of the tire 30.

#The casing 10 is a housing that is formed by joining together a casing body 11 and a lid body 12. The casing body 11 has a space 11a for accommodating a main portion of the transponder 1. The lid body 12 covers a side of the casing body 11 that exposes the space 11a. A first side surface of the casing body 11 has a central section in the longitudinal direction thereof, from which a connector portion 10a engageable to the air valve 20 extends. On the other hand, a second side surface of the casing body 11 has a central section in the longitudinal direction thereof, which is provided with an air hole 10b that takes in the air in the tire 30. Moreover, referring to FIG. 3, the casing body 11 has therein a partition-like reinforcement rib 11b that extends across the space 11a to separate the space 11a into two sections. The reinforcement rib 11b extends along an extension of the axis of the air valve 20.