Time based low tire pressure warning sensor
AssigneeDelco Electronics Corporation
InventorsTodd D. Eberwine, Victor Mendez, Nguyen Phu Nguyen
Life of this patent
Estimating the term…
Abstract
A battery powered sensor in a tire has a microprocessor and a transmitter circuit permanently connected to a battery and a pressure switch or pressure sensor coupled to the microprocessor. The microprocessor has a sleep state and wakes up every few minutes to execute an algorithm which determines on a time basis whether to read the pressure state and transmit a report of significant changes, and determines on a randomly timed basis whether to transmit a status report. A factory test state permits only one signal transmission when the tire is inflated and inhibits other signals for a period to allow testing of many tires without interference from one another.
Claims7
In a low tire pressure warning system having a transmitter and a pressure sensor wherein the transmitter has a sleep mode of low energy consumption, a wake mode of normal energy consumption and a transmission timer, a method of using the transmission timer for intermittently transmitting a pressure message comprising the steps of:
- periodically entering the wake mode and determining whether the transmission timer indicates that it is time to transmit a pressure message;
- when the transmission timer indicates that it is time to transmit a pressure message,
- transmitting a status report,
- selecting a random time within a prescribed time range,
- initializing the transmission timer with the selected random time, and
- returning to the sleep mode.
In a low tire pressure warning system having a factory test state for pressurizing a tire and an in-use state, the system including a transmitter and a pressure sensor wherein the transmitter has a sleep mode of low energy consumption and a wake mode of normal energy consumption, the method of intermittently transmitting a pressure message comprising the steps of:
- periodically waking the transmitter from the sleep mode and checking an IN-USE flag;
- if an IN-USE flag is not set, entering a factory test state and then setting the IN-USE flag a delay time after the tire is pressurized;
- if the IN-USE flag is set, entering the in-use state and then
- transmitting a status report at selected times, and
- periodically monitoring the pressure sensor for changes and transmitting a warning when a significant pressure change is detected.
Dependencies are inferred from the claim text.