Apparatus and method for power management in a tire pressure monitoring system
First Claim
1. A method for power management in a tire pressure monitoring system for indicating when air pressure in a tire is below a predetermined amount, comprising:
- sensing the air pressure with a pressure sensor;
sensing air temperature with a temperature sensor;
determining whether the air pressure is increasing or decreasing with respect to time;
determining whether a ratio of the air pressure and the air temperature is increasing, decreasing or remaining constant with respect to time to infer that the tire is moving, motion of the tire being determined without directly sensing acceleration or movement of the tire; and
performing the sensing of air pressure and sensing of air temperature at measurement intervals which are longer in time than when the tire is not in motion to save power in the tire pressure monitoring system when the tire is not in motion.
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Accused Products
Abstract
A system (10) and method manages battery (13) power in a wheel module (11) for indicating when air pressure in a tire falls below a recommended value. Tire air pressure is sensed with a pressure sensor (16). Tire air temperature is sensed with a temperature sensor (18). A determination is made whether the air pressure is increasing or decreasing with respect to time. Based upon whether a ratio of the air pressure and the air temperature is increasing, decreasing or remaining constant with respect to time, tire motion is inferred without directly sensing acceleration or movement of the tire. Power management circuitry (14) controls battery power to enable sensing of air pressure and air temperature at measurement intervals that are longer in time when the tire is not in motion.
30 Citations
12 Claims
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1. A method for power management in a tire pressure monitoring system for indicating when air pressure in a tire is below a predetermined amount, comprising:
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sensing the air pressure with a pressure sensor;
sensing air temperature with a temperature sensor;
determining whether the air pressure is increasing or decreasing with respect to time;
determining whether a ratio of the air pressure and the air temperature is increasing, decreasing or remaining constant with respect to time to infer that the tire is moving, motion of the tire being determined without directly sensing acceleration or movement of the tire; and
performing the sensing of air pressure and sensing of air temperature at measurement intervals which are longer in time than when the tire is not in motion to save power in the tire pressure monitoring system when the tire is not in motion. - View Dependent Claims (2, 3, 4, 5)
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6. A tire air pressure monitoring system in a tire, comprising:
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a battery for powering the tire pressure monitoring system;
a pressure sensor for sensing air pressure in the tire;
a temperature sensor for sensing air temperature in the tire;
control circuitry for determining whether the air pressure is increasing or decreasing with respect to time and determining whether a ratio of the air pressure and the air temperature is increasing, decreasing or remaining constant with respect to time to infer that the tire is moving, motion of the tire being determined without directly sensing acceleration or movement of the tire; and
power management circuitry coupled to the battery, the pressure sensor and the temperature sensor for selectively powering the pressure sensor and temperature sensor at measurement intervals which are shorter when the control circuitry has inferred that the tire is moving than when the tire is not moving. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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Specification