Abnormal tire condition warning system

A device for sensing a condition of a pneumatic tire mounted on a tire rim comprising:

• a housing;
• a means for mounting said housing within said tire;
• sensing means associated with said housing for monitoring said condition within the tire;
• circuit means associated with said housing including:
• a radio transmitter circuit operatively connected to said sensing means for controlling and generating radio signals indicative of said tire condition;
• and,
• a microcontroller having a low power mode during operation of the device, means for monitoring device parameters and means for periodically generating said radio signals in an absence of an abnormal tire condition, thereby providing for self-checking of the device in operation;
• power supply means associated with said housing, opweratively connected to said circuit means to power the circuit means and to enable the generation of the radio signals, said power supply means including a battery adapted to be contained within said tire and a centrifugal switch means adapted to render the circuit means de-energized in a first stationary and low tire rotation mode and energized in a second high tire rotation mode;
• switching circuit means operatively connected to said sensing means for bypassing the centrifugal switch means upon an indiction of an abnormal tire condition;
• and
• means for receiving said radio signals.

A device for sensing an abnormal condition of a pneumatic tire preferably of the type used on a motor vehicle wherein the tire is mounted on a tire rim comprising:

• a housing;
• a means for mounting said housing within said tire;
• sensing means associated with said housing for monitoring the abnormal condition within the tire;
• circuit means associated with said housing including a microcontroller and oscillator circuit and a radio transmitter circuit operatively connected to said sensing means for controlling and generating radio signals indicative of said abnormal tire condition, said microcontroller having a low power consumption mode, means for selectively operating in said low power consumption mode for nearly all the time energized, means for monitoring device parameters and means for periodically generating said radio signals in an absence of said abnormal tire condition, thereby providing for self-checking of the device in operation;
• power supply means associated with said housing operatively connected to said circuit means to power the circuit means and enable the generation of the radio signals, said power supply means including a battery adapted to be contained within said tire and a centrifugal switch, the centrifugal switch adapted to render the circuit means de-energized in a first stationary and low tire rotation mode and energized in a second high tire rotation mode thereby with said microcontroller greatly limiting power required from the battery and increasing battery life;
• and
• means for receiving said radio signals.

A method of monitoring a pneumatic tire condition for use with an apparatus having a transmitter device including a power supply including a battery adapted for mounting in said tire, a centrifugal switch, a condition sensor, microcontroller with an extended low power consumption mode when energized during operation of the device, and a radio signal generating circuit, and a receiver device for receiving radio signals, the method comprising the steps of:

• disposing the transmitter device within the pneumatic tire;
• sensing a rotational frequency of the pneumatic tire with the centrifugal switch above a predetermined threshold rotational frequency;
• enabling the microcontroller by connection to the power supply through the centrifugal switch when the sensed rotational frequency exceeds the predetermined threshold frequency;
• using the microcontroller to monitor apparatus parameters;
• controlling the radio signal generating circuit to generate a first radio signal indicative of an abnormal tire condition;
• sensing said pneumatic tire condition with the condition sensor;
• controlling the radio signal generating circuit with the enabled microcontroller to periodically generate a second radio signal representative of the sensed pneumatic tire condition at a predetermined rate in an absence of an abnormal tire condition to provide a self-checking of the transmitter device;
• and
• receiving the generated periodic radio signal with the receiver device.