Method and apparatus for estimating tire air pressure
First Claim
1. An apparatus for estimating tire air pressure comprising:
- a wheel speed detection component for detecting wheel speed of each of a front wheel and a rear wheel;
a characteristic amount calculation component for calculating a characteristic amount of a frequency characteristic of each of the wheel speeds detected by said wheel speed detection component;
a difference-value calculation component for calculating a value of difference which represents a degree of difference between a characteristic amount of the front wheel and a characteristic amount of the rear wheel, which characteristic amounts are calculated by said characteristic amount calculation component; and
a state determination component for determining a state of air pressure of a tire based on the value of difference calculated by said difference-value calculation component.
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Abstract
The present invention provides a method and apparatus for estimating a state of tire air pressure with high accuracy in a range of vehicle speeds from a low travel speed to a high travel speed. A wheel speed of each of a right-hand front wheel and a right-hand rear wheel is detected based on wheel speed signals outputted from vehicle speed sensors, and characteristic amounts (power) of frequency characteristics of the wheel speeds are calculated. A value of difference which represents a degree of difference between the obtained characteristic amounts of the right-hand front wheel and the right-hand rear wheel is calculated. Based on the value of difference, the state of air pressure of a tire is determined. As a result, it can be determined if the air pressure of one of tires on the right-hand front wheel and the right-hand rear wheel has been reduced.
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Citations
20 Claims
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1. An apparatus for estimating tire air pressure comprising:
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a wheel speed detection component for detecting wheel speed of each of a front wheel and a rear wheel;
a characteristic amount calculation component for calculating a characteristic amount of a frequency characteristic of each of the wheel speeds detected by said wheel speed detection component;
a difference-value calculation component for calculating a value of difference which represents a degree of difference between a characteristic amount of the front wheel and a characteristic amount of the rear wheel, which characteristic amounts are calculated by said characteristic amount calculation component; and
a state determination component for determining a state of air pressure of a tire based on the value of difference calculated by said difference-value calculation component. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for estimating tire air pressure comprising:
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a wheel speed detection component for detecting wheel speed of each of a right-hand front wheel, a right-hand rear wheel, a left-hand front wheel and a left-hand rear wheel;
a characteristic amount calculation component for calculating a characteristic amount of a frequency characteristic of each of the wheel speeds detected by said wheel speed detection component;
a right-hand wheels difference-value calculation component for calculating a value of difference between right-hand wheels, which represents a degree of difference between a characteristic amount of the right-hand front wheel and a characteristic amount of the right-hand rear wheel, which characteristic amounts are calculated by said characteristic amount calculation component;
a left-hand wheels difference-value calculation component for calculating a value of difference between left-hand wheels, which represents a degree of difference between a characteristic amount of the left-hand front wheel and a characteristic amount of the left-hand rear wheel, the characteristic amounts being calculated by said characteristic amount calculation component; and
a state determination component for determining a state of air pressure of a tire based on the value of difference between right-hand wheels and the value of difference between left-hand wheels. - View Dependent Claims (7, 8, 9, 10)
said left-hand wheels difference-value calculation component calculates, as the value of difference between left-hand wheels, one of a difference and a ratio between the characteristic amount of the left-hand front wheel and the characteristic amount of the left-hand rear wheel. -
8. The apparatus for estimating tire air pressure according to claim 6, wherein said state determination component calculates, as a value of difference between right and left, one of a difference and a ratio between the value of difference between right-hand wheels and the value of difference between left-hand wheels, and, when a degree of difference between the value of difference between right-hand wheels, and the value of difference between left-hand wheels represented by the value of difference between right and left, is at least a predetermined value, said state determination component determines that the air pressure of a tire has been reduced.
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9. The apparatus for estimating tire air pressure according to claim 6, wherein said state determination component calculates, as a value of difference between right and left, one of a difference and a ratio between the value of difference between right-hand wheels and the value of difference between left-hand wheels, and, when a degree of difference between the value of difference between right and left, and a predetermined reference value is at least a predetermined value, said state determination component determines that the air pressure of a tire has been reduced.
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10. The apparatus for estimating tire air pressure according to claim 6, wherein the characteristic amount of the frequency characteristic of the wheel speed is an amount related to power in a predetermined frequency range of the wheel speed.
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11. A method for estimating tire air pressure, comprising the steps of:
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(a) detecting wheel speed of each of a front wheel and a rear wheel;
(b) calculating a characteristic amount of a frequency characteristic of each of the wheel speeds detected in said step (a);
(c) calculating a value of difference which represents a degree of difference between a characteristic amount of the front wheel and a characteristic amount of the rear wheel, which characteristic amounts are calculated in said step (b); and
(d) determining a state of air pressure of a tire based on the value of difference calculated in said step (c). - View Dependent Claims (12, 13, 14, 15)
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16. A method for estimating tire air pressure, comprising the steps of:
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(a) detecting wheel speed of each of a right-hand front wheel, a right-hand rear wheel, a left-hand front wheel and a left-hand rear wheel;
(b) calculating a characteristic amount of a frequency characteristic of each of the wheel speeds detected in said step (a);
(c) calculating a value of difference between right-hand wheels, which represents a degree of difference between a characteristic amount of the right-hand front wheel and a characteristic amount of the right-hand rear wheel, which characteristic amounts are calculated in said step (b);
(d) calculating a value of difference between left-hand wheels, which represents a degree of difference between the characteristic amount of the left-hand front wheel and the characteristic amount of the left-hand rear wheel, which characteristic amounts are calculated in said step (b); and
(e) determining a state of air pressure of a tire based on the value of difference between right-hand wheels and the value of difference between left-hand wheels. - View Dependent Claims (17, 18, 19, 20)
said step (d) comprises calculating, as the value of difference between left-hand wheels, one of a difference and a ratio between the characteristic amount of the left-hand front wheel and the characteristic amount of the left-hand rear wheel. -
18. The method for estimating tire air pressure according to claim 16, wherein said step (e) comprises calculating, as a value of difference between right and left, one of a difference and a ratio between the value of difference between right-hand wheels and the value of difference between left-hand wheels, and determining, when a degree of difference between the value of difference between the right-hand wheels and the value of difference between the left-hand wheels, represented by the value of difference between right and left is at least a predetermined value, that the air pressure of a tire has been reduced.
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19. The method for estimating tire air pressure according to claim 16, wherein said step (e) comprises calculating, as a value of difference between right and left, one of a difference and a ratio between the value of difference between right-hand wheels, and the value of difference between left-hand wheels, and determining, when a degree of difference between the value of difference between right and left and a predetermined reference value is at least a predetermined value, that the air pressure of a tire has been reduced.
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20. The method for estimating tire air pressure according to claim 16, wherein the characteristic amount of the frequency characteristic of the wheel speed is an amount related to power in a predetermined frequency range of the wheel speed.
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Specification