Initial correction factor determining device and device utilizing the same for vehicle
First Claim
1. A tire pressure drop detecting device for detecting drops in air pressure in a tires mounted on a vehicle, the tires including a driving tire and a following tire, the vehicle having a rotational velocity detector which detects, and provides an output indicative of the rotational velocities of the mounted tires, comprising:
- a slip factor calculating device, includingan initial correction factor calculating device havingmeans for accepting the output of said rotational velocity detector in a case where the vehicle is linearly coasting, andmeans for finding an initial correction factor for eliminating an effect of a relative difference in effective rolling radius depending on an initial difference among the mounted tires, on the rotational velocities, based on the accepted output of the rotational velocity detector,rotational velocity correcting means for correcting the accepted output of the rotational velocity detector, using the initial correction factor found by the initial correction factor calculating device, to determine corrected rotational velocities of the tires, andmeans for calculating a slip factor of the driving tire based on the corrected rotational velocities of the driving tire and the following tire;
lateral acceleration determining means for determining a lateral acceleration exerted on the vehicle based on the corrected rotational velocities of the tires;
substituting means for substituting the corrected rotational velocities of the tires in a predetermined expression, to determine an initial judged value;
judged value correcting means for correcting the determined initial judged value based on the calculated slip factor and the determined lateral acceleration, to obtain a corrected judged value; and
means for detecting a drop in air pressure in one of the tires based on the corrected judged value.
1 Assignment
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Accused Products
Abstract
A device for determining a correction factor for correcting an output of a rotational velocity mechanism for detecting the rotational velocity of a tire mounted on a vehicle, and a slip factor calculating device and a tire pressure drop detecting device utilizing the determining device. The rotational velocity of the tire is detected in response to the fact that an initializing switch is operated at the time of trial linear coasting. An initial correction factor is found on the basis of the rotational velocity. The initial correction factor is stored in an E2 PROM. At a time of normal traveling, the rotational velocity is initially corrected on the basis of the initial correction factor (S2). Further, the slip factor is calculated on the basis of the rotational velocity after the initial correction (S3). A judged value required to detect the drop in air pressure in the tire is corrected on the basis of the slip factor or the like (S9). The initial correction factor representing only a relative difference in effective rolling radius between tires can be acquired, so that an initial difference can be eliminated from the rotational velocity with high precision.
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Citations
9 Claims
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1. A tire pressure drop detecting device for detecting drops in air pressure in a tires mounted on a vehicle, the tires including a driving tire and a following tire, the vehicle having a rotational velocity detector which detects, and provides an output indicative of the rotational velocities of the mounted tires, comprising:
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a slip factor calculating device, including an initial correction factor calculating device having means for accepting the output of said rotational velocity detector in a case where the vehicle is linearly coasting, and means for finding an initial correction factor for eliminating an effect of a relative difference in effective rolling radius depending on an initial difference among the mounted tires, on the rotational velocities, based on the accepted output of the rotational velocity detector, rotational velocity correcting means for correcting the accepted output of the rotational velocity detector, using the initial correction factor found by the initial correction factor calculating device, to determine corrected rotational velocities of the tires, and means for calculating a slip factor of the driving tire based on the corrected rotational velocities of the driving tire and the following tire; lateral acceleration determining means for determining a lateral acceleration exerted on the vehicle based on the corrected rotational velocities of the tires; substituting means for substituting the corrected rotational velocities of the tires in a predetermined expression, to determine an initial judged value; judged value correcting means for correcting the determined initial judged value based on the calculated slip factor and the determined lateral acceleration, to obtain a corrected judged value; and means for detecting a drop in air pressure in one of the tires based on the corrected judged value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification