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

• US 20030076223A1
• Filed: 10/04/2002
• Published: 04/24/2003
• Est. Priority Date: 02/08/2001
• Status: Active Grant

• Current Assignee: DENSO Corporation, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: DENSO Corporation, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Tabata, Masaaki, Ohashi, Hideki, Naito, Toshiharu, Mori, Yukio, Tominaga, Motonori, Taguchi, Takeyasu
• Granted Patent: US 6,768,418 B2
• Time in Patent Office: Days
• US Class Current: 340/443
• CPC Class Codes: B60C 23/061 by monitoring wheel speed measuring distance traversed on the ground by vehicles G01C22/00

Abstract

A tire air pressure detection device of the present invention includes a warning anticipation timing calculating portion for anticipating a warning timing at which tire air pressure decrease detecting portion will detect the tire air pressure decrease based on rotational status value compensated for by a rotational status value compensating portion. A tire air pressure decrease detecting portion detects a decrease in tire air pressure when a clocked determination time reaches the warning anticipation timing anticipated by the warning anticipation timing calculating portion.

Claims

1. 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 tire air pressure decrease based on the rotational status value compensated for by the rotational status value compensating portion; and

a warning anticipation timing calculating portion for anticipating a warning timing at which the tire air pressure decrease detecting portion will detect the tire air pressure decrease based on the rotational status value compensated for by the rotational status value compensating portion;

wherein the tire air pressure decrease detecting portion detects that tire air pressure decreases when a clocked determination time reaches the warning anticipation timing anticipated by the warning anticipation timing calculating portion.

2. The tire air pressure detection device according to claim 1, wherein the warning anticipation timing calculating portion calculates a timing when the rotational status compensated for by the rotational status value compensating portion will exceed a predetermined threshold as the warning anticipation timing.

3. The tire air pressure detection device according to claim 2, wherein the warning anticipation timing calculating portion calculates the warning anticipation timing based on a change in value per predetermined interval of the rotational status compensated for by the rotational status value compensating portion.

4. The tire air pressure detection device according to claim 1, further comprising:

a memory portion (3g) for memorizing warning anticipation timing data calculated by the warning anticipation timing calculating portion,

wherein the memory portion renews previously stored warning anticipation timing data stored before to new calculated warning anticipation timing data when the new warning anticipation timing data is earlier than the previously stored warning anticipation timing data.

5. The tire air pressure detection device according to claim 1, further comprising:

an ideal driving status calculating portion (3e) for calculating an ideal status value (β

id) corresponding to a slip value when there is no tire slippage;

wherein the rotational status value compensating portion (3f) calculates an ideal rotational status value when there is no tire slippage based on the regression line calculated by the regression line calculating portion and the ideal slip status value calculated by the ideal driving status calculating portion.

6. The tire air pressure detection device according to claim 1, wherein the rotational status value calculating portion calculates a wheel speed variation (D) corresponding to a difference in wheel speed ratios of wheels located diagonally from each other.

7. 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 tire air pressure decrease based on a determination value (Δ

D″

_AVE) that is defined based on the rotational status value compensated for by the rotational status value compensating portion; and

a tread-lift compensation processing portion (3j) for determining whether the determination value exceeds a predetermined threshold (Cth) and compensating for the determination value when the determination value exceeds the predetermined threshold,

wherein the tire air pressure decrease detecting portion detects that the tire air pressure decreases based on the determination value calculated by the tread-lift compensation processing portion.

8. 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 tire air pressure decrease based on a determination value (Δ

D″

_AVE) that is defined based on the rotational status value compensated for by the rotational status value compensating portion; and

a tread-lift compensation processing portion (3j) for executing compensation processing for removing an effect of tread-lift from the determination value and for adjusting a degree of the compensation processing with respect to a scale of the determination value,

wherein the tire air pressure decrease detecting portion detects that the tire air pressure decreases based on the determination value compensated by the compensation processing of the tread-lift compensation processing portion.

9. The tire air pressure detection device according to claim 8, wherein the tread-lift compensation processing portion enlarges the degree of the compensation when the scale of the determination value is larger.

10. The tire air pressure detection device according to claim 8, wherein the tread-lift compensation processing portion executes the compensation after an initializing mode at which the post-compensation rotational status value has not yet been calculated by the rotational status value calculating portion.

11. 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 tire air pressure decrease based on a determination value (Δ

D″

_AVE) that is defined based on the rotational status value compensated for by the rotational status value compensating portion; and

a tread-lift compensating processing portion (3j) for executing compensation processing to remove an effect of tread-lift from the determination value and for adjusting a degree of the compensation processing with respect to a scale of the determination value, wherein the compensation is executed after an initializing mode at which the post-compensation rotational status value has not yet been calculated by the rotational status value calculating portion

wherein the tire air pressure decrease detecting portion detects that tire air pressure decreases based on the determination value calculated by the tread-lift compensation processing portion.

12. The tire air pressure detection device according to claim 11, wherein the tire air pressure decrease detecting portion (3h) detects the tire air pressure decrease based on the determination value (Δ

D″

_AVE) that corresponds to a difference between a post-compensation value calculated at the initializing mode and that calculated after the initializing mode.

13. 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 first rotational status value compensation portion (3n) for compensating for the rotational status value calculated by the rotational status value calculating portion using vehicle speed as a parameter;

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 (D*) compensated for by the first rotational status value compensating portion and the slip status value calculated by the slip status value calculating portion;

a second rotational status value compensating portion (3f) for further compensating for the rotational status value (D*) compensated for by the first rotational status value compensating portion based on the regression line calculated by the regression line calculating portion;

a tire air pressure decrease detecting portion (3h) for detecting tire air pressure decrease based on the rotational status value compensated for by the second rotational status value compensating portion.

14. The tire air pressure detection device according to claim 13, wherein the second rotational status value compensating portion calculates a change in value of rotational status value relative to the vehicle speed based on a relationship between the rotational status value calculated by the rotational status value calculating portion and the vehicle speed, and compensates for the rotational status value by adding the change in value as a compensation value.

15. The tire air pressure detection device according to claim 14, further comprising:

a rotational status value memorizing portion (3b) for memorizing data regarding the rotational status value calculated by the first rotational status value calculating portion,

wherein the first rotational status value calculating portion calculates the relationship between the rotational status value calculated by the rotational status value calculating portion and the vehicle speed based on the data regarding the rotational status value stored in the rotational status value memorizing portion, compensates for the rotational status value based on a predetermined deformation feature when the relationship has not yet been calculated, and compensates for the rotational status value based on the relationship after the relationship has been calculated.

16. The tire air pressure detection device according to claim 13, further comprising:

an ideal driving status calculating portion (3e) for calculating an ideal status value (β

id) corresponding to a slip value when there is no tire slippage;

wherein the second rotational status value compensating portion (3f) calculates an ideal rotational status value when there is no tire slippage based on the regression line calculated by the regression line calculating portion and the ideal slip status value calculated by the ideal driving status calculating portion.

17. 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 classifying vehicle speed into several speed ranges, distinguishing the rotational status value and the slip status value for each related speed range of the several speed ranges, and 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 at each speed range of the several speed ranges;

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 at the each speed range by the regression line calculating portion;

a tire air pressure decrease detecting portion (3h) for calculating a regression curve based on the rotational status value of the each speed range compensated for by the rotational status value compensating portion, and detecting tire air pressure decrease based on a determination value (Δ

D″

_AVE) that is defined based on the rotational status value at the each speed ranges compensated for by the rotational status value compensating portion.

18. The tire air pressure detection device according to claim 17, further comprising:

a memory portion (3n) or distinguishing and memorizing the data of 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 at the each speed range; and

a counter for counting each interval since the data has been stored in the memory portion;

wherein the memory portion deletes the data when the interval reaches a predetermined time.