Tire condition monitoring system

Details Tire condition monitoring system Tire condition monitoring system

1999-12-01

2001-06-05

Pope, Daryl (Department: 2632)

Communications: electrical

Land vehicle alarms or indicators

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

C340S442000, C340S445000, C073S146500

Reexamination Certificate

active

06243007

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention pertains to a tire monitoring system. More particularly, the present invention relates to a tire monitoring system which monitors tire engineering conditions, including pressure and temperature, using a monitoring device which is generally installed on the interior portion of a pneumatic tire or tire rim and in electronic communication with a receiver.
The need to maintain tires at the correct pressure level to eliminate driving on under-inflated tires is fundamental in preventing undue tread wear, increased fuel consumption and flat tire accidents. If the average passenger car tire pressure decreases from 32 p.s.i. to 25 p.s.i., the life of the tire is reduced by 20% due to uneven tread wear and fuel consumption increases by up to 10%. A vehicle's handling and braking are also adversely affected by tires having low air pressure. The U.S. National Highway Traffic and Safety Administration has reported that almost half of the tires on the road are under-inflated and may account for as many as 250,000 annual accidents. It has also been estimated that over five million gallons of gasoline are wasted each year due to tire under-inflation.
Tires known as “run-flat” tires have recently been developed which have reinforced side walls so that the tire can be driven on for a certain number of miles with little or no physical manifestation even though the tire is completely deflated. Without a tire monitoring system, the driver will not be aware that he or she has a flat tire and may destroy the tire before having it repaired or replaced.
An operational and practical design for remote tire pressure and/or temperature measuring devices has been attempted for many years. Unfortunately, none of these devices has achieved acceptance for many reasons including the unreliability and fragility of the components. Not until the invention of miniature solid state sensors and microprocessors has any degree of success been achieved. However, these systems can also be unreliable and very expensive.
Many modern tire monitoring systems consist of pressure and temperature transducers as well as a transmitter. Power is supplied by utilizing a battery, inductive coils or piezo-electric power. Although there are a myriad of combinations of these components, considerable effort is required to design a system that is reliable, easily used by non-technical personnel, and cost effective.
Accordingly, what is needed is a tire pressure monitoring system utilizing modern electronics which are internally mounted within a tire. What is further needed is a tire pressure monitoring system which is reliable, cost-effective and easily used by non-technical personnel. The present invention fulfills these needs and provides other related advantages.
SUMMARY OF THE INVENTION
A tire condition monitoring system is provided which informs the driver of the condition, including air pressure, of one or more of the tires so that the driver is alerted when a tire is deflated. Other engineering data, including tire temperature, can also be relayed to the driver or maintenance personnel. The system is cost-effective and reliable and can be used by non-technical personnel for the life of the tire.
In accordance with the invention, a tire condition monitoring device having a unique identification code is positioned within a pneumatic tire. The tire condition monitoring device includes a battery, at least one sensor in electrical circuit with the battery, a programmable microprocessor in circuit with the battery, a transmitter in circuit with the battery and a pick-up coil in electrical circuit with the microprocessor. The sensors include a pressure sensor and a temperature sensor. The transmitter includes a SAW filter for pulse modulated transmissions. The unique identification code comprises a multiple bit code which specifically identifies the device. The monitoring device is securely attached to either a rim for the tire or an inner surface of the tire itself.
The tire condition monitoring device is shipped in a dormant mode. After installation, the monitoring device can be activated and assigned a tire location by pressurizing each tire to a predetermined level to activate the monitoring device from a dormant state to an operational state. Alternatively, the monitoring device is activated and assigned a tire location by use of a portable hand-held wand transmitter. This is accomplished by holding the hand-held transmitter close to the tire and actuating a switch of a keypad on the hand-held transmitter and subsequently transmitting a signal to the monitoring device through the tire. The keypad has at least one switch to assign a tire location for every tire on the vehicle.
The tire condition monitoring device periodically senses a condition within the tire, including measurement of tire temperature and/or air pressure. The sensed condition information is then electronically stored and the sensed condition information is compared with preset parameters based on previously stored condition information.
If the sensed tire condition data falls within the preset parameters, the transmitter of the monitoring device periodically telemeters the sensed condition information and the monitoring device identification code in pulse modulated signal to a receiver in electronic communication with the monitoring device. The receiver is usually mounted in the cab of the vehicle. The receiver communicates this information to a cab mounted visual display unit which visually displays the information.
The monitoring device immediately telemeters the sensed condition information and identification code to the receiver if the sensed condition information falls without the preset parameters. The visual display unit includes an audible alarm for alerting a vehicle passenger of a change of sensed tire conditions.
The sensed condition information is telemetered less frequently during periods of low vehicle and tire activity. The monitoring device is reactivated upon tire or vehicle reactivity.
In another embodiment of the present invention, a monitoring device having a battery, an air pressure sensor in circuit with the battery, a transmitter in circuit with the air pressure sensor and the battery, and a motion detector in circuit with the battery is positioned within the tire. The air pressure sensor comprises a mechanical sensor which is positioned entirely within the tire. The mechanical air pressure sensor includes a housing having a conductive portion, a pressure sensitive diaphragm positioned within the housing, a first conductive terminal in contact with the battery and the conductive diaphragm, and a second conductive terminal in physical contact with the conductive portion of the housing and the transmitter.
A receiver is in electronic communication with the transmitter and a cab mounted alarm. An encoder can be included in the monitoring device for generating a vehicle specific signal.
The motion detector is used to determine whether the tire is rotating at a predetermined velocity. Once the predetermined velocity is reached, power is supplied from the battery to the first terminal and the diaphragm. Tire pressure which has dropped below a predetermined level is determined when the ambient pressure within the tire decreases to the point where the diaphragm expands to physically contact the conductive portion of the housing, creating a conductive relationship between the diaphragm and the conductive portion of the housing, and thus the second terminal. Electrical power is transferred from the diaphragm to the transmitter via the conductive portion of the housing and the second terminal. The transmitter generates a signal to the receiver to activate the alarm and alert the driver of existence of a low pressure tire.
Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.


REFERENCES:
patent: 4334215 (1982-0

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