Tire pressure drop detecting device
First Claim
1. A device for detecting a drop in air pressure of any of tires mounted on a vehicle, comprising:
- rotational angular velocity detection means for detecting a rotational angular velocity of each of the tires for each of predetermined sampling periods;
initial correction factor calculation means for finding an initial correction factor for eliminating an effect of a difference in effective rolling radius depending on an initial difference among the tires on the rotational angular velocities, the initial correction factor calculation means including means for finding as the initial correction factor a ratio of the rotational angular velocities of a predetermined pair of the tires on the basis of the rotational angular velocities detected by the rotational angular velocity detection means, means for averaging and updating the initial correction factor for each sampling period, and means for taking the initial correction factor found when a number of times of the updating reaches a predetermined number of times as a final initial correction factor;
correction means for correcting the rotational angular velocities detected by the rotational angular velocity detection means for each sampling period on the basis of the initial correction factor found by the initial correction factor calculation means;
judgment means for finding a judged value on the basis of the rotational angular velocities corrected by the correction means and judging whether the air pressure of any of the tires has dropped on the basis of the found judged value; and
calculation stop means for stopping operation of the initial correction factor calculation means when it is judged by the judgment means that the air pressure of any of the tires has dropped before the final initial correction factor is taken in the initial correction factor calculation means.
1 Assignment
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Accused Products
Abstract
An apparatus for detecting the drop in air pressure of any of tires mounted on a vehicle. The device finds, in finding an initial correction factor for eliminating the effect of a difference in effective rolling radius depending on an initial difference among the tires on the rotational angular velocities of the tires, the ratio of the rotational angular velocities of a predetermined pair of the tires as an initial correction factor, averaging and updating the initial correction factor for each sampling period, and taking the initial correction factor found when the number of times of the updation reaches a predetermined number of times as the final initial correction factor. When it is judged that the air pressure of any of the tires drops before the final initial correction factor is found, the calculation of the initial correction factor is stopped.
29 Citations
5 Claims
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1. A device for detecting a drop in air pressure of any of tires mounted on a vehicle, comprising:
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rotational angular velocity detection means for detecting a rotational angular velocity of each of the tires for each of predetermined sampling periods; initial correction factor calculation means for finding an initial correction factor for eliminating an effect of a difference in effective rolling radius depending on an initial difference among the tires on the rotational angular velocities, the initial correction factor calculation means including means for finding as the initial correction factor a ratio of the rotational angular velocities of a predetermined pair of the tires on the basis of the rotational angular velocities detected by the rotational angular velocity detection means, means for averaging and updating the initial correction factor for each sampling period, and means for taking the initial correction factor found when a number of times of the updating reaches a predetermined number of times as a final initial correction factor; correction means for correcting the rotational angular velocities detected by the rotational angular velocity detection means for each sampling period on the basis of the initial correction factor found by the initial correction factor calculation means; judgment means for finding a judged value on the basis of the rotational angular velocities corrected by the correction means and judging whether the air pressure of any of the tires has dropped on the basis of the found judged value; and calculation stop means for stopping operation of the initial correction factor calculation means when it is judged by the judgment means that the air pressure of any of the tires has dropped before the final initial correction factor is taken in the initial correction factor calculation means. - View Dependent Claims (2, 3, 4, 5)
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Specification