Self training tire pressure monitoring system

Details Self training tire pressure monitoring system Self training tire pressure monitoring system

2002-07-26

2004-05-04

Pham, Toan Ngoc (Department: 2632)

Communications: electrical

Land vehicle alarms or indicators

Internal alarm or indicator responsive to a condition of the...

C340S442000, C340S443000, C116S03400R, C073S146200

Reexamination Certificate

active

06731205

ABSTRACT:

FIELD OF INVENTION
The present invention relates to tire pressure monitoring systems and, more particularly, to the characterization of a low-pressure or high-pressure condition occurring in one or more tires of a set of tires mounted on the vehicle, and most particularly, to identification of the location or particular wheels of the vehicle that the particular tire or tires are located.
BACKGROUND OF INVENTION
There are several advantages to maintaining the pneumatic tires of an automobile at the inflation pressure recommended by the tire or vehicle manufacturer. Vehicle handling characteristics are maintained when all tires are inflated to the condition specified by the vehicle designer. The loss of pressure in one or more tires on the vehicle may result in less than optimum driver control and therefore a reduced safety condition. Inadvertent over-inflation of one or more tires may also result in less than optimum vehicle handling. Operating a vehicle with tire pressures outside the recommended inflation range can also reduce tire life due to excessive flexing and heating and resultant fatigue or wear. Also, operating a vehicle with under-inflated tires can significantly decrease fuel efficiency. Tire pressure monitoring systems have been developed which alert the vehicle operator when the pressure in one or more of the tires fitted to the vehicle is outside a predetermined range.
So called run-flat tires can puncture and lose air pressure without the drivers knowledge. The tire manufacturer typically specifies a distance and maximum speed for operation in the run-flat condition. It is important for the driver to know when the run flat condition occurred so that operating the tire beyond its safe limits may be avoided. Consequently, tire pressure monitoring systems are typically installed on vehicles equipped with run-flat tires, but due to the dangers associated with sudden tire degradation on the likes of sports utility vehicles and the like, tire monitoring systems are being used widely on many types of vehicles.
Indeed, following an increase in public awareness of the potential consequences of operating tires outside the manufacturers recommended pressure range, legislation has been introduced such as proposed FMVSS 138 which requires that a tire pressure monitoring system be installed as original equipment on all new vehicles sold in the United States after November, 2003.
While several tire pressure-monitoring methods have been proposed, two general approaches have been favored. One is indirect and relies on the determination of the rolling radius of each hub and tire assembly (and often linked to the anti-lock brake system (ABS) of the vehicle). The second is direct and relies on the wireless transmission of a signal from a transducer module installed in the pressurized cavity of each tire. Such systems work well for their intended purposes, but there are disadvantages.
The rolling radius method relies on the signals generated by wheel rotation sensors, typically installed as part of an anti-lock braking system. The rolling radius represents the actual radius from the center of the tire to the generally flattened area of the tire in contact with the ground. Because of the flattening at the point of contact of the tire and the road or surface, the rolling radius measures smaller than the nominal radius of the tire as manufactured or unloaded, since the nominal radius does not account for variation in pressure within the tire and load on the tire. Since the rotational speed of each wheel is known accurately, the rolling radius of the hub and tire assembly mounted at each wheel can be inferred. This system of tire pressure monitoring (frequently referred to in the art as ABS-tire pressure monitoring) does not, however, provide absolute values of pressure, nor does it provide tire temperature information. If all of the tires on the vehicle were to lose pressure equally over time, such a system may fail to detect a reduction in pressure in any tire. Also, this system requires that data be gathered over some minimum number of wheel rotations in order to allow tire temperatures to equalize to some extent, to determine relative rolling radii, and then to approximate each tire pressure. This type of system is not well suited to anything other than installation as original equipment. While this type of system is a low cost addition to a vehicle equipped with anti-lock brakes, it has many performance shortcomings. Since the wheel rotation can only be monitored when the wheel is rotating, this type of system cannot be used to monitor the condition of a spare tire carried on the vehicle, nor can it provide an instant indication of a flat tire when the ignition switch is operated. It is not uncommon to have a slow air leak from a tire due to the penetration of a sharp object such as a nail, screw or other small metallic object, through the tire wall, typically in the tread area. Such a rate of pressure loss may not cause the driver to notice the condition while driving, but when left for a prolonged period, such as overnight parking, the pressure loss may result in a sufficiently flat tire such that driving the vehicle may permanently damage or weaken the tire. Since the driver may approach the vehicle without sight of the damaged or at least partially deflated tire, it is preferable that the pressure monitoring system provides warning immediately on operation of the ignition switch.
The direct sensing method requires the installation of a wireless module in contact with the gas within the pressurized cavity of each tire and hub assembly. A matched receiving module is installed on a fixed portion of the vehicle such that the transmitted data may be processed and presented to the vehicle operator as required. A receiver may be positioned within each wheel well of the vehicle, in which case it is necessary to install one receiver for each monitored tire on the vehicle, or, a single receiver may be placed approximately centrally within the vehicle, such as at the interior rearview mirror location. The advantages of multiple receivers are that transmission distances can be short, thus conserving power, and that data is associated with the receiver location, thus avoiding system training. The significant disadvantage of multiple receivers is the high additional cost. Additionally, installation is difficult unless as original equipment. The potential disadvantages of a single receiver include more complex coding to avoid transmitter confusion, and the need for a greater transmission range, both of which have adverse power implications. A significant disadvantage of the single receiver approach is the need for system training. Each transmitter in the system is identified by a unique code so the receiver always associates data with a particular tire being monitored by a particular pressure sensor but, without a complex and currently impractical antenna configuration, the system cannot determine the wheel location that the particular tire is actually located on. Also, since tires are commonly rotated or replaced by a spare, it is necessary to train the system. Training may consist of manually reducing the air pressure in a predetermined tire until the system indicates it has detected a loss of pressure, re-inflating to the correct pressure and, repeating for all other monitored tires in the system in a predetermined sequence. Training must be repeated whenever a receiver position is changed.
It is known to identify the tire location by utilizing a temperature sensor and an accelerometer sensor at each tire of the vehicle, such as disclosed in U.S. Pat. No. 6,259,361, which is hereby incorporated herein by reference. The temperature sensor may indicate whether it is positioned at the front or rear tires due to temperature differences typically present between the front and rear tires. The accelerometer sensor may determine a rolling direction of the tires, in order to determine whether the tires are on the left or right side of the vehicle. Such a pressure sensing system may include multipl

Affiliated with

Also associated with

Rating

Self training tire pressure monitoring system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Self training tire pressure monitoring system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Self training tire pressure monitoring system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3214825