Patent ID: 8013724

Claim:
A tire-pressure control apparatus comprising a plurality of wheel speed sensors for respectively detecting rotational speeds of a plurality of wheels of a vehicle; a plurality of air pressure generation units respectively provided for the plurality of wheels and each including an air pump driven through rotation of the corresponding wheel so as to generate compressed air to be supplied to a tire air chamber of the wheel and being capable of maintaining a tire pressure of the wheel between a lower limit set value and an upper limit set value; and a plurality of pressure sensors respectively detecting the tire pressures of the plurality of wheels, the tire-pressure control apparatus further comprising for each wheel: up-time calculation means for calculating an up time, which is a time period over which the tire pressure of the wheel increases from the lower limit set value to the upper limit set value, on the basis of a detection value of the corresponding pressure sensor; down-time calculation means for calculating a down time, which is a time period over which the tire pressure of the wheel decreases from the upper limit set value to the lower limit set value, on the basis of the detection value of the pressure sensor; average-rotational-speed calculation means for calculating an average rotational speed of the wheel during the up time calculated by the up-time calculation means, on the basis of the detection value of the wheel speed sensor; first-pump-supplied-air-quantity calculation means for calculating a first pump-supplied air quantity of the corresponding air pressure generation unit in a single generation and non-generation cycle on the basis of the up time and the average rotational speed; second-pump-supplied-air-quantity calculation means for calculating a second pump-supplied air quantity of the air pressure generation unit in a single generation and non-generation cycle on the basis of the up time and the down time; and determination means for comparing the first pump-supplied air quantity and the second pump-supplied air quantity.