Resilient tires and wheels – Tires – resilient – Inflating devices
Reexamination Certificate
2003-03-25
2004-08-10
Stormer, Russell D. (Department: 3617)
Resilient tires and wheels
Tires, resilient
Inflating devices
C152S429000, C137S224000
Reexamination Certificate
active
06772812
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates to vehicle tire air pressure maintenance systems. More specifically, the invention relates to dual-function tire inlet valves.
2. Technical Background
Monitoring and maintaining proper tire air pressure for vehicles has long been an important maintenance item carried out by a vehicle owner. In the past, vehicle owners regularly checked tire pressure because low-pressure tires were easily noticed. However, as tire technology has advanced, low tire pressure has become more difficult to notice by simple observation. This, and a perception that more advanced tires experience fewer slow leaks, has lead vehicle owners to stop or drastically reduce monitoring the tire pressure for their vehicles.
Tires are still subject to leaks. Generally, the leaks are slow and may not always completely deflate the tire. The leaks may be attributable to permeability of the tire material by failed tire valves, an opening between the tire and rim, or a puncture of the tire or inner tube by a foreign object such as glass or a nail. Natural leaks may reduce the pressure by as much as one pound per square inch (psi) per month. Seasonal temperature changes also reduce tire pressure by one psi for every drop of 10 F. degrees in temperature. Changes in altitude also affect tire pressure.
Low tire pressure may cause significant problems. Studies relied upon by the National Highway Traffic Safety Administration (NHTSA) indicate that low-pressure tires reduce vehicle safety. For example, lower pressure causes more wear on the tire sidewalls, which may lead to premature failure. The NHTSA estimates that 23,464 crashes were a result of under-inflated tires.
Low tire pressure also reduces the life of the tire. Data from Goodyear and Michelin indicate that 20% under-inflation can reduce tire life by up to 50%. Low tire pressure causes the tire tread to wear non-uniformly, which may also cause premature failure of the tire. Tire costs, particularly for the trucking industry, are the second highest operating expense behind fuel.
Low tire pressure reduces the fuel economy of the vehicle. Tires with lower pressure require more energy to rotate. Goodyear indicates that tires that are 15% under-inflated result in a 2.5% increase in fuel consumption.
Finally, a federal government agency is proposing to require tire pressure monitoring systems on all new cars, trucks, and multipurpose passenger vehicles. (See “Tire pressure monitoring systems; controls and displays” NHTSA, 49 CFR Part 571) This proposal would require tire pressure systems to notify the driver if the tire pressure descends below a threshold level. Such a proposal may be very costly if conventional tire pressure maintenance and monitoring systems must be used and maintained (e.g., by replacing batteries, etc.).
In response to the problems caused by low tire pressure, efforts have been made to provide devices and systems that monitor and/or maintain the pressure in a vehicle's tires. Known pressure maintenance efforts have generally focused on mechanisms for adding small amounts of air to the tire while the tire rotates to compensate for losses due to leaks.
These pressure maintenance devices include external or internal compressors that compress ambient air into an interior chamber of the tire. For the tire pressure maintenance systems to operate, air must pass into the tire via an inlet valve either before or after compression. Additionally, tires with pressure maintenance devices must have an inlet valve that allows users to manually adjust the tire pressure and allows tire professionals to service the tires.
Therefore, tires equipped with pressure maintenance devices utilize two inlet valves, one for pressure maintenance and another for traditional tire valve functions. Conventional tire inlet valves include a valve body, a valve spring, and a valve stem. The stem typically includes a valve actuator and a valve seal. The valve spring biases the valve seal against the valve body to close the valve. A user can open these conventional valves by engaging the actuator to compress the spring and move the valve seal away from the valve body.
The introduction of additional tire inlet valves for use with pressure maintenance systems is problematic during repair of damaged tires. Tire valves typically extend through the rim of the wheel. The valve must be withdrawn from the rim to service the tire and then reinserted through the rim to assemble the wheel. A second tire inlet valve presents many challenges to tire professionals that must service tires with tire pressure maintenance systems. For example, the position of the valve relative to the rim is important to ensure that the valve functions properly. A second tire valve will increase the incidence of errors in tire maintenance and the possibility of valve failure. Additionally, the costs of tire maintenance will increase with the increased complexity of the repair procedures.
Furthermore, tires often loose air pressure through valve failure. The introduction of a second tire inlet valve increases the probability of air pressure loss due to valve failure.
Accordingly, it would be an advancement in the art to provide a fail-safe tire inlet valve that can be used with existing tire pressure maintenance and monitoring systems. It would be a further advancement to provide a tire pressure maintenance and monitoring system that allows automatic and manual adjustment without requiring multiple valve structures to extend from the tire body. Additionally, it would be an advancement in the art to provide a tire inlet valve that selectively allows ambient air into a tire pressure maintenance and monitoring system only under certain conditions.
BRIEF SUMMARY OF THE INVENTION
The apparatus and method of the present invention have been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available tire pressure maintenance and monitoring devices. Thus, the present invention provides a tire pressure maintenance system with a dual-function tire inlet valve that is simple, inexpensive, and safe.
In one embodiment, the dual-function tire inlet valve is mountable on a tire in communication with a compressor in a tire pressure maintenance system. The inlet valve has a conduit with an exterior end and an interior end. When the inlet valve is mounted on a tire, the exterior end of the conduit is in fluid communication with an ambient air supply and the interior end is in fluid communication with an interior chamber of the tire. The dual-function inlet valve also includes a first check valve positioned adjacent to one end of the conduit and a second check valve adjacent to the other end of the conduit. The first check valve is automatically opened only when the compressor is active and the tire is rotating about its axis with at least a pre-determined velocity. The second check valve opens only upon manual actuation.
A pump channel may be formed within the conduit and in fluid communication with the compressor between the first and second check valves. The first check valve may preferably be positioned adjacent to the exterior end of the conduit with the second check valve positioned adjacent to the interior end of the conduit.
The conduit may comprise a sleeve that is removably disposed in a shell surrounded by an encasement configured for mounting on a conventional tire. A portion of the sleeve may have a threaded outer surface and a corresponding portion of the shell may have a threaded inner surface such that the threaded outer surface of the sleeve mates with the threaded inner surface of the shell when the sleeve is disposed in the shell.
The sleeve, the shell and the encasement of the dual-function tire inlet valve of the present invention may be configured to associate with conventional external tire valve devices such as pumps and pressure gauges. The tire inlet valve may further comprise an air-filter cap to allow
Autoliv ASP Inc.
Brown Sally J.
Stormer Russell D.
LandOfFree
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