Communications: electrical – Land vehicle alarms or indicators – Internal alarm or indicator responsive to a condition of the...
Reexamination Certificate
1999-03-19
2001-01-16
Hofsass, Jeffrey A. (Department: 2736)
Communications: electrical
Land vehicle alarms or indicators
Internal alarm or indicator responsive to a condition of the...
C340S445000, C340S447000, C073S146400, C116S03400R
Reexamination Certificate
active
06175301
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a warning system for indicating low tire pressure on a vehicle.
More particularly, the present invention relates to a wireless warning system for indicating low tire pressure on a vehicle.
In a further and more specific aspect, the instant invention concerns the use of a micropower transmitter in a warning system for indicating low tire pressure on a vehicle.
BACKGROUND OF THE INVENTION
This disclosure describes a wireless low-tire-pressure warning system for use on trailers, cars, trucks, and other vehicles. Although wireless tire pressure monitor systems are currently in use, they are fairly expensive and are typically only available as an original equipment option on new cars and trucks.
The available wireless tire pressure systems are typically sophisticated systems in that they measure and give a continuous readout of the actual pressure in each tire. Although this is a nice feature, it is not required simply to warn the driver of a hazardous condition. These extra features increase the complexity and cost of the system.
There have been numerous patents issued on tire pressure monitoring systems. However, most of the older patents describe mechanically complicated systems or systems that can only be installed as original equipment when the vehicle is manufactured. The newer patents typically describe wireless systems designed to display the tire's actual air pressure to the driver.
The primary challenge of electronic tire pressure monitors is battery life. It is easy to design a full featured unit inside the tire that measures and transmits actual tire pressure. However, to provide these features requires considerable battery current to operate the electronic pressure sensors that are typically used to measure air pressure in the tire. To conserve battery life, these units are typically designed to only transmit tire pressure periodically. To save battery power, some systems only provide pressure updates once a minute. This is a severe limitation in that a fast tire leak might not be detected for nearly a mile when traveling at highway speeds. A tire could completely deflate and disintegrate over this distance before the driver is alerted.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide a new and improved low tire pressure warning system.
Another object of the invention is to provide a new and improved low tire pressure warning system which is easy to install in the tires of vehicles presently being used, as well as in new vehicles.
And another object of the invention is to provide a new and improved low tire pressure warning system which is relatively inexpensive.
Still another object of the present invention is to provide a new and improved low tire pressure warning system with a very long operating life because of low battery drain.
Yet another object of the invention is to provide a new and improved low tire pressure warning system which gives an operator instant notification of low tire pressure.
SUMMARY OF THE INVENTION
Briefly, to achieve the desired objects of the instant invention in accordance with a preferred embodiment thereof, a low tire pressure warning system is provided that includes a tire pressure sensor constructed to be mounted within each of the tires on the wheels of a vehicle. Each tire pressure sensor includes a pressure switch coupled to a transmitter and a battery, with the pressure switch being constructed to connect the battery to the transmitter so as to activate the transmitter when pressure within the tire drops below a low (generally normal) value. A receiver is constructed to be mounted within the vehicle in communication with the transmitters and a low tire pressure warning indicator is coupled to the receiver so as to be activated when the receiver receives a signal from any one of the transmitters.
In a preferred embodiment, a low tire pressure warning system in accordance with the present invention includes a tire pressure sensor constructed to be mounted within a tire on a wheel of a vehicle. The tire pressure sensor includes a pressure switch coupled to a transmitter and a battery, and the pressure switch is constructed to connect the battery to the transmitter so as to activate the transmitter when pressure within the tire drops below a low (generally normal) value. The transmitter includes an oscillator for producing a carrier and a pseudo random noise generator connected to the oscillator for modulating the carrier. A receiver is constructed to be mounted within the vehicle in communication with the transmitter for receiving the carrier. The receiver includes a pseudo random noise generator similar to the pseudo random noise generator in the transmitter for decoding only valid pseudo random noise coded signals transmitted by the transmitter, and a low tire pressure warning indicator is coupled to the receiver so as to be activated when the receiver receives a signal from the transmitter.
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Hofsass Jeffrey A.
Pham Toan
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