Communications: electrical – Land vehicle alarms or indicators – Internal alarm or indicator responsive to a condition of the...
Reexamination Certificate
1998-07-13
2001-07-10
Pope, Daryl (Department: 2736)
Communications: electrical
Land vehicle alarms or indicators
Internal alarm or indicator responsive to a condition of the...
C340S442000, C340S444000, C073S146200, C116S03400R, C200S061220
Reexamination Certificate
active
06259361
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a tire pressure monitoring system for a vehicle and particularly one which can identify the location of a tire without reprogramming upon rotation of tires on the vehicle.
The utilization of tire pressure monitors has been described in numerous patents in which tire pressure sensors have been mounted in the wheel, attached to the valve stem, or embedded in the tire itself. Such systems typically use a sensor and associated circuit for each tire which transmits a modulated radio frequency signal to a receiver in the vehicle for sending information indicating when the pressure of a tire has reached a predetermined low threshold. The receiver and associated circuitry, upon receipt of information indicating a low pressure condition, provides the driver with an alerting signal to the low tire pressure condition. Many systems utilize a tire pressure sensor and transmitter which uniquely identify each tire with an identification code also transmitted to the receiver such that not only is the operator made aware of the existence of a low pressure condition in one of the tires, the tire location is also identified. U.S. Pat. No. 5,661,651 discloses one such system in which the frequency of the transmitted signal identifies the tire. In other systems, a binary code identifying each tire is employed.
A problem with such systems occurs upon the rotation of tires, which is recommended on a frequent basis by many tire or vehicle manufacturers. Thus, tires are rotated from front to rear, from side to side, or both to promote even wear. In such case, a tire which originally was identified to the operator as being located, for example, on the left front of the vehicle may now be located on the right rear and a system which identifies tire location would now indicate a tire problem at the wrong location to the vehicle operator. It has been suggested that this problem can be overcome by reprogramming the tire location as suggested by, for example, U.S. Pat. No. 5,463,374 where it is necessary to manually place a strong magnet near each of the remote wheel-mounted transmitters upon rotation of a tire to reidentify the location of the tire. This not only requires a manual step of having the operator or service personnel place a magnet near each tire, it also requires the tire-mounted transmitter to include a magnetic switch as part of the mechanism, thereby adding to the cost, reliability and complexity of the overall system. Other approaches also suggest the use of a service tool which must be manually coupled to each tire to reprogram the tire location upon rotation of the tires.
Thus, with existing systems, the rotation of tires on a vehicle requires intervention, typically with service personnel or by an operator sufficiently skilled to reprogram the tire location, so that the monitoring system can recognize the new location of a tire. There exists a need, therefore, for a system which allows rotation of tires on a vehicle and which automatically identifies the new tire location to the system display and monitor.
With the introduction of “run-flat” tires, a new tire related problem has also been introduced, namely, the requirement that an operator only drive on a “run-flat” tire for about fifty miles at a maximum speed of 55 mph. There is a need also, therefore, to notify a driver that a “run-flat” tire has lost its pressure and alert the driver to the speed and distance limitations upon such occurrence.
SUMMARY OF THE PRESENT INVENTION
The system of the present invention allows for tire location identification by recognizing that certain characteristics are unique to front-located tires verses rear-located tires as well as left-side tires and right-side tires. It has been discovered that, when a vehicle is in operation, front tires typically have a higher operating temperature than rear tires. Thus, by sensing tire temperature information, such information can be employed to discriminate between front-mounted and rear-mounted tires. Additionally, sensors can be provided which distinguish between left- and right-side mounting of wheels. One such sensor can be an accelerometer-type device which, when a vehicle accelerates, makes contact with two of three contacts and, when the vehicle decelerates, makes contact with a different two of three contacts. When such a sensor is mounted on a left-side wheel of the vehicle, upon acceleration, one set of contacts are closed, however, when the same type of sensor is positioned in the same location on a wheel on the right side, the other set of contacts are closed. With this information, therefore, the signal generated by such sensors can be employed to discriminate between left- and right-side mounted tires. With the information provided by these sensors, a control circuit can identify each tire's location and provide the operator with accurate pressure information for each tire. By coupling the control circuit to the vehicle's speed and distance signal information, typically available on the vehicle bus, “run-flat” warning signals can also be provided to the vehicle operator.
These and other features, objects and advantages of the present invention will become apparent upon reading the following description thereof together with reference to the accompanying drawings.
REFERENCES:
patent: 5463374 (1995-10-01), Mendez et al.
patent: 5540092 (1996-07-01), Handfield et al.
patent: 5600301 (1997-02-01), Robinson, III
patent: 5612671 (1997-03-01), Mendez et al.
patent: 5661651 (1997-08-01), Geschke et al.
patent: 5760682 (1998-06-01), Liu et al.
patent: 5764137 (1998-06-01), Zarkhin
patent: 5774048 (1998-06-01), Achterholt
patent: 5825286 (1998-10-01), Coulthard
Geschke James R.
Honeck Brian S.
Robillard James P.
Suman Michael J.
Foley & Lardner
Pope Daryl
Prince Corporation
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