Tire air pressure detection device for detecting air pressure based on vehicle speed signal

A tire air pressure detection device comprising:

• a vehicle wheel speed detecting portion (2a-2d, 3a) for detecting respective vehicle wheel speeds;
• a rotational status value calculating portion (3b) for calculating a rotational value (D) expressing a relationship of the respective vehicle wheel speeds to cancel a wheel speed variation between left and right wheels generated due to vehicle turns;
• a slip status value calculating portion (3c) for calculating a slip status value (β) based on the vehicle wheel speeds detected by the vehicle wheel speed detecting portion, the slip status value depending on a slip status between driven wheels and non-driven wheels;
• a regression line calculating portion (3d) for calculating a regression line that is a linear function expressing a relationship between the rotational status value calculated by the rotational status value calculating portion and the slip status value calculated by the slip status value calculating portion;
• a rotational status value compensating portion (3f) for compensating for the rotational status value calculated by the rotational status value calculating portion based on the regression line calculated by the regression line calculating portion;
• a tire air pressure decrease detecting portion (3h) for detecting a tire air pressure decrease based on the rotational status value compensated for by the rotational status value compensating portion;
• and
• a selecting portion for selecting the rotational status value calculated by the rotational status value calculating portion and the slip status value calculated by the slip status value calculating portion within a predetermined available range;
• wherein the regression line calculating portion calculates the regression line based on the rotational status value and the slip status value selected by the selecting portion.

A tire air pressure detection device comprising:

• a vehicle wheel speed detecting portion (2a-2d, 3a) for detecting respective vehicle wheel speeds;
• a rotational status value calculating portion (3b) for calculating a rotational value (D) expressing a relationship of the respective vehicle wheel speeds to cancel wheel speed variation between left and right wheels generated due to vehicle turns;
• a slip status value calculating, portion (3c) for calculating a slip status value (β) based on the vehicle wheel speeds detected by the vehicle wheel speed detecting portion, and the slip status value depending on a slip status between driven wheels and non-driven wheels;
• a regression line calculating portion (3d) for calculating a regression line that is a linear function expressing a relationship between the rotational status value calculated by the rotational status value calculating portion and the slip status value calculated by the slip status value calculating portion;
• a rotational status value compensating portion (3f) for compensating for the rotational status value calculated by the rotational status value calculating portion based on the regression line calculated by the regression line calculating portion;
• a tire air pressure decrease detecting portion (3h) for detecting a tire air pressure decrease based on the rotational status value compensated for by the rotational status value compensating portion;
• and
• a non-uniformity detecting portion (3i) for detecting non-uniform of driven forces;
• wherein the rotational status value compensating portion compensates for the rotational value based on the regression line now calculated by the regression line calculating portion when the non-uniformity detecting portion detects the non-uniform of the driven forces, and compensates for the rotational value based on the regression line previously calculated before by the regression line calculating portion when the non-uniformity detecting portion has not detected the non-uniform of the driven forces.

A tire air pressure detection device comprising:

• a vehicle wheel speed detecting portion (2a-2d, 3a) for detecting respective vehicle wheel speeds;
• a rotational status value calculating portion (3b) for calculating a rotational value (D) expressing a relationship of the respective vehicle wheel speeds to cancel a wheel speed variation between left and right wheels generated due to vehicle turns;
• a slip status value calculating portion (3c) for calculating a slip status value (β) based on the vehicle wheel speeds detected by the vehicle wheel speed detecting portion, the slip status value depending on a slip status between driven wheels and non-driven wheels;
• a regression line calculating portion (3d) for calculating a regression line that is a linear function expressing a relationship between the rotational status value calculated by the rotational status value calculating portion and the slip status value calculated by the slip status value calculating portion;
• a rotational status value compensating portion (3f) for compensating for the rotational status value calculated by the rotational status value calculating portion based on the regression line calculated by the regression line calculating portion;
• a tire air pressure decrease detecting portion (3h) for detecting a tire air pressure decrease based on the rotational status value compensated for by the rotational status value compensating portion;
• and
• a selecting portion for selecting data from data regarding the wheel speeds detected by the wheel speed detecting portion by removing data when the vehicle turns based on left and right non-driven wheels speeds (VFL, VFR);
• wherein the rotational status value calculating portion calculates the rotational status value and the slip status value calculating portion calculates the slip status value based on the data selected by the selecting portion.

A tire air pressure detection device comprising:

• a vehicle wheel speed detecting portion (2a-2d, 3a) for detecting respective vehicle wheel speeds;
• a rotational status value calculating portion (3b) for calculating a rotational value (D) expressing a relationship of the respective vehicle wheel speeds to cancel a wheel speed variation between left and right wheels generated due to vehicle turns;
• a slip status value calculating portion (3c) for calculating a slip status value (β) based on the vehicle wheel speeds detected by the vehicle wheel speed detecting portion, the slip status value depending on a slip status between driven wheels and non-driven wheels;
• a regression line calculating portion (3d) for calculating a regression line that is a linear function expressing a relationship between the rotational status value calculated by the rotational status value calculating portion and the slip status value calculated by the slip status value calculating portion;
• a rotational status value compensating portion (3f) for compensating for the rotational status value calculated by the rotational status value calculating portion based on the regression line calculated by the regression line calculating portion;
• a tire air pressure decrease detecting portion (3h) for detecting a tire air pressure decrease based on the rotational status value compensated for by the rotational status value compensating portion;
• and
• a selecting portion for defining an available range based on data regarding left and right non-driven wheel speeds included in the wheel speeds detected by the wheel speed detecting portion, and selecting data within the available range from the data regarding left and right non-driven wheel speeds;
• wherein the rotational status value calculating portion calculates the rotational status value and the slip status value calculating portion calculates the slip status value based on the data selected by the selecting portion, and
• the available range is defined initially based on the data regarding left and right non-driven wheel speeds, and is then repeatedly renewed each time the selecting portion selects the data regarding left and right non-driven wheel speeds.

A tire air pressure detection device comprising:

• a vehicle wheel speed detecting portion (2a-2d, 3a) for detecting respective vehicle wheel speeds;
• a rotational status value calculating portion (3b) for calculating a rotational value (D) expressing a relationship of the respective vehicle wheel speeds to cancel a wheel speed variation between left and right wheels generated due to vehicle turns;
• a slip status value calculating portion (3c) for calculating a slip status value (β) based on the vehicle wheel speeds detected by the vehicle wheel speed detecting portion, the slip status value depending on a slip status between driven wheels and non-driven wheels;
• a regression line calculating portion (3d) for calculating a regression line that is a linear function expressing a relationship between the rotational status value calculated by the rotational status value calculating portion and the slip status value calculated by the slip status value calculating portion;
• a rotational status value compensating portion (3f) for compensating for the rotational status value calculated by the rotational status value calculating portion based on the regression line calculated by the regression line calculating portion;
• a tire air pressure decrease detecting portion (3h) for detecting a tire air pressure decrease based on the rotational status value compensated for by the rotational status value compensating portion;
• a left and right non-driven wheel speed ratio calculating portion for calculating a left and right non-driven wheel speed ratio (R) based on data of left and right non-driven wheel speeds detected by the wheel speed detecting portion;
• and
• a left and right non-driven wheel speed ratio determining portion for defining an available range based on the left and right non-driven wheel speed ratio calculated by the left and right non-driven wheel speed ratio calculating portion, and determining whether the left and right non-driven wheel speed ratio is in the available range;
• wherein the left and right non-driven wheel speed ratio determining portion selects the data within the available range from data regarding the wheel speed detected by the wheel speed detecting portion, and
• the rotational status value calculating portion calculates the rotational status value and the slip status value calculating portion calculates the slip status value based on the data selected by the left and right non-driven wheel speed ratio determining portion.