Method for using time measurements for detecting pressure loss in vehicle tires

• US 6,439,045 B1
• Filed: 01/19/2001
• Issued: 08/27/2002
• Est. Priority Date: 05/23/1997
• Status: Expired due to Fees

• Current Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Original Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Inventors: Latarnik, Michael, Griesser, Martin, Zenzen, Markus
• Primary Examiner(s): OEN, WILLIAM L
• Application Number:
  US09/424,205
• Time in Patent Office: 585 Days
• Field of Search: 340/442, 340/443, 340/444, 340/669, 340/670, 340/671, 731/465, 731/462, 731/464
• US Class Current: 73/146.5
• CPC Class Codes: B60C 23/061 by monitoring wheel speed measuring distance traversed on the ground by vehicles G01C22/00

Abstract

The present invention relates to a method of detecting pressure loss in vehicle tires, wherein a reference value is produced from signals, especially time measurement values, representative of the wheel rotational speeds of a plurality of vehicle wheels, and pressure loss is concluded from a comparison of a currently determined reference value with at least one comparative value in case the currently determined reference value exceeds or falls below the comparative value, and pressure loss in vehicle tires is detected by using at least one reference value which is produced by dividing the sums of respectively two signals representative of the wheel rotational speeds.

Claims

1. Method of detecting pressure loss in tires of a vehicle with wheels, comprising the steps of:

measuring rotational speeds of each wheel;

determining a plurality of reference values representative of the rotational speeds of the wheels as a function of time;

determining a statistical value of the plurality of reference values;

determining a comparative value from the statistical value of the plurality of reference values;

comparing the reference value and the comparative value; and

applying an offset to the statistical value, wherein when a deviation of the statistical value does not exceed a defined value, wherein the offset is applied when pressure loss occurs when a currently determined reference value is not equal to the comparative value.

2. The method of detecting pressure loss according to claim 1, wherein the function of time is further defined by the steps of:

using a signal representative of the wheel rotational speeds to define a time measurement for a predetermined number of wheel revolutions;

issuing a joint start signal of the time measurement for each individual wheel, wherein the time measurement of each wheel is further defined when the following edge of the signal representative of the rotational speed of the respective wheel is detected;

initiating a scanning interval for the time measurement period for each signal edge so that a scanning sensor opens and closes with individual signal edges;

defining an interpolation with reference to the corresponding signal edge defined by the time measurement; and

concluding the joint start signal individually for each wheel upon termination of the number of wheel revolutions predetermined for all wheels.

3. The method of detecting pressure loss according to claim 1, wherein the determining a plurality of reference values step further includes the step of:

establishing at least one filtered reference value,

establishing at least one unfiltered reference value, and

determining a maximum and minimum reference value from the filtered reference values.

4. The method of detecting pressure loss according to claim 3, wherein the determining a statistical value is the mean value of the unfiltered reference values.

5. The method of detecting pressure loss according to claim 3, wherein the determining a statistical value is the average value of the unfiltered reference values.

6. The method of detecting pressure loss according to claim 4, wherein the maximum value is set by adding the offset to the maximum value.

7. The method of detecting pressure loss according to claim 6, wherein the minimum value is set by subtracting the offset from the minimum value.

8. The method of detecting pressure loss according to claim 7 further including the step of:

checking the currently determined reference value against the minimum and maximum values.

9. The method of detecting pressure loss according to claim 5, wherein the determining a predefined comparative value step includes the addition of the offset to the average of the plurality of reference values.

10. The method of detecting pressure loss according to claim 5, wherein the determining a predefined comparative value step includes the subtraction of the offset to the average of the plurality of reference values.

11. The method of detecting pressure loss according to claim 1, wherein the determining a plurality of reference values is carried out by dividing the sums of two signals representative of the wheel rotational speeds.

12. The method of detecting pressure loss according to claim 1, wherein the offset is generally 0.5 pro mille.

13. The method of detecting pressure loss according to claim 1, wherein the number of wheel revolutions is predetermined as a function of the vehicle speed.

14. Method as claimed in claim 1, wherein the comparative value is determined in dependence on axles.

15. The method of detecting pressure loss according to claim 1, wherein the comparative value is determined speed-responsively.

16. The method of detecting pressure loss according to claim 1, further including the step of actuating a reset key when a wheel is changed.

17. The method of detecting pressure loss according to claim 1, further including the step of providing a manually operable reset key.

18. The method of detecting pressure loss according to claim 1, further including the step of interrupting the production of the reference values when defined threshold values of the longitudinal acceleration, transverse acceleration and/or wheel acceleration are exceeded.

19. Method of detecting pressure loss in tires of a vehicle with wheels, comprising the steps of:

measuring rotational speeds of each wheel;

determining a plurality of reference values representative of the rotational speeds of the wheels as a function of time, wherein the determining a plurality of reference values step further comprises the steps of;

establishing at least one filtered reference value,

establishing at least one unfiltered reference value,

determining a maximum and minimum reference value from the filtered reference values, and

checking the currently determined reference value against the minimum and maximum values;

determining a mean value of the unfiltered reference values;

determining a comparative value from the mean value of the unfiltered reference values;

comparing the reference value and the comparative value; and

applying an offset to the mean value, wherein when a deviation of the statistical value does not exceed a defined value, wherein the offset is applied when pressure loss occurs when a currently determined reference value is not equal to the comparative value, wherein the maximum value is set by adding the offset to the maximum value, wherein the minimum value is set by subtracting the offset from the minimum value.

20. The method of detecting pressure loss according to claim 19, wherein the function of time is further defined by the steps of:

using a signal representative of the wheel rotational speeds to define a time measurement for a predetermined number of wheel revolutions;

issuing a joint start signal of the time measurement for each individual wheel, wherein the time measurement of each wheel is further defined when the following edge of the signal representative of the rotational speed of the respective wheel is detected;

initiating a scanning interval for the time measurement period for each signal edge so that a scanning sensor opens and closes with individual signal edges;

defining an interpolation with reference to the corresponding signal edge defined by the time measurement; and

concluding the joint start signal individually for each wheel upon termination of the number of wheel revolutions predetermined for all wheels.

21. Method of detecting pressure loss in tires of a vehicle with wheels, wherein the number of wheel revolutions is predetermined as a function of the vehicle speed, comprising the steps of:

measuring rotational speeds of each wheel;

determining a plurality of reference values representative of the rotational speeds of the wheels as a function of time, wherein the determining a plurality of reference values is carried out by dividing the sums of two signals representative of the wheel rotational speeds, wherein the determining a plurality of reference values step further comprises the steps of;

establishing at least one filtered reference value,

establishing at least one unfiltered reference value,

determining a maximum and minimum reference value from the filtered reference values, and

checking the currently determined reference value against the minimum and maximum values, wherein the function of time is further defined by the steps of;

using a signal representative of the wheel rotational speeds to define a time measurement for a predetermined number of wheel revolutions,

issuing a joint start signal of the time measurement for each individual wheel, wherein the time measurement of each wheel is further defined when the following edge of the signal representative of the rotational speed of the respective wheel is detected,

initiating a scanning interval for the time measurement period for each signal edge so that a scanning sensor opens and closes with individual signal edges,

defining an interpolation with reference to the corresponding signal edge defined by the time measurement, and

concluding the joint start signal individually for each wheel upon termination of the number of wheel revolutions predetermined for all wheels;

interrupting the production of the reference values when defined threshold values of the longitudinal acceleration, transverse acceleration and/or wheel acceleration are exceeded;

determining a mean value of the plurality of unfiltered reference values;

determining a comparative value from the statistical value of the plurality of reference values, wherein the comparative value is determined in dependence on axles, wherein the comparative value is determined speed-responsively;

comparing the reference value and the comparative value; and

applying an offset to the statistical value, wherein the offset is generally 0.5 pro mille, wherein when a deviation of the statistical value does not exceed a defined value, wherein the offset is applied when pressure loss occurs when a currently determined reference value is not equal to the comparative value, wherein the maximum value is set by adding the offset to the maximum value, wherein the minimum value is set by subtracting the offset from the minimum value, wherein the determining a predefined comparative value step includes the addition of the offset to the average of the plurality of reference values, wherein the determining a predefined comparative value step includes the subtraction of the offset to the average of the plurality of reference values.