Rim mounted tire pressure monitoring system

#The invention relates generally to tire pressure monitoring systems and, more specifically, to housing assemblies for such systems.

#Typical commercially available tire pressure monitoring system units are mounted to the inside of a tire in a position from which the air pressure within the tire cavity may be measured. Data representing pressure within the tire is then communicated by a transmitted signal to a reader external to the tire. For example, certain available units integrate a pressure sensing module with the valve stem of a tire. Electronics within the sensor unit measure the air pressure at the valve stem and transmit an appropriate signal to an external receiver. The receiver may be located proximally located to the sensor unit or in a remote location such as the passenger compartment.

#While working well, such systems are not useful in meeting the industry's needs in certain applications. For example, in some applications such as in NASCAR race tires, there is a need for a tire pressure-measuring device that may be used conveniently in a two tire system by officials to check start inflation pressure. Such a system should functionally measure inflation pressure without requiring an official to touch the tire. A suitable pressure measuring system will give a positive indication of specific tire read and, for competition reasons, preclude one team from reading another team's tire information. In addition, the pressure measuring system and device must be capable of validation with a mechanical pressure gauge if necessary. In such applications, the tire pressure measuring device should be hardy and capable of surviving multiple races. Ideally, the device will be a standard supported component of the tire/wheel assembly. The operation of the device should further be capable of operational verification before the tire/wheel assemblies are released for control purposes and function without requiring an electromagnetic radiation shield.

#The invention will be described by way of example and with reference to the accompanying drawings in which:

#FIG. 1 is a perspective view of a tire rim portion having a tire pressure monitoring module (TPMM) mounted thereto.

#FIG. 2 is an exploded perspective view of a rim portion and tire pressure monitoring module configured pursuant to the invention.

#With reference to FIGS. 1, 2, and 3, a tire, rim, and tire pressure monitoring module assembly 10 is shown. The rim 12 is of a conventional rim configuration. A two tire system, such as that used in NASCAR racing is depicted for the purpose of illustration, it being understood that the subject rim mounted tire pressure monitoring system is capable of utilization in a single tire and rim application. A pair of spaced apart tire bodies 14, 16 of conventional tire configuration are mounted to the rim 12, the tire body 16 representing an inner tire and the tire body 14 representing an outer tire. The inner tire 16 functions to maintain stability in the event the outer tire 14 is damaged or otherwise deflates. In a two tire system such as that shown, both tires are mounted to a common rim internal surface region 20. With the beads of the tire bodies 14, 16 properly seated on surface 20, the inner tire 16 (which has higher inflation pressure than the outer tire) pushes both beads against the rim flange 22. The inner tire 16 is formed to provide molded grooves 88 to allow the inflation pressure in the cavity 30 of the outer tire 14 to reach the area adjacent to the flange between the two beads for tire pressure measurement.

#As described above, the air pressure within the tire cavity 32 of the inner tire 16 is maintained higher than the pressure of the outer tire body 14. In order to achieve competitive equality between racing cars and for safety considerations, the air pressure within the tire body 14 is monitored. A tire pressure monitoring module 18 is employed for this purpose. Module 18 is mounted to an outward facing rim surface 24 adjacent a rim well wall 26. As best seen from a collective consideration of FIGS. 1, 2, and 3, the module 18 includes a casing or housing 34, an end cap 36, an insert body 38, a gasket 40, a circuit board 41, a sealing washer 42, and bolt 44.

#With reference to FIGS. 4, 5, 6, and 7, the module housing 34 includes an internal pressure chamber 46 enclosed by three sidewalls 47 and end cap 36. An internal shoulder 48 is formed within the chamber 46 opposite an open side 58. A generally circular collar 52 projects from the housing 34 and an annular shoulder 50 projects into a collar passageway 56. The passageway 56 extends through the collar 52 and the annular shoulder 50 into communicating relationship with the chamber 46. A pair of circuit board supporting rail flanges 54 extend along the interior of the housing 34 as shown and a flat surface 57 is formed in a side of the collar defining bore 56. The housing 34 may be formed from any suitable material such moldable thermoplastic or thermoset plastics material having sufficient temperature and strength characteristics for strength and dimensional stability in a tire/wheel rim environment.