Tire pressure leak detection method and system

• US 20050241380A1
• Filed: 01/11/2005
• Published: 11/03/2005
• Est. Priority Date: 04/29/2004
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Welch, Shawn M., McCarthy, Victor A.
• Granted Patent: US 7,225,666 B2
• Time in Patent Office: Days
• US Class Current: 73/146
• CPC Class Codes: B60C 23/00 Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements

Abstract

A method of determining whether a tire will satisfy a t hour pressure retention standard in about x hours, where x is less than t, that involves determining a tire pressure stabilization time z (120), inflating a tire at time t0 to a first pressure (122), taking a first pressure measurement at (x-y) hours after t0 where (x-y)≧z (124), taking a second pressure measurement at x hours (126), determining a change in pressure between the first pressure measurement and the second pressure measurement (128) and determining from the change in pressure whether the tire will satisfy the t hour pressure retention standard (130).

Claims

1. A method of aircraft tire inspection comprising the steps of:

inflating an aircraft tire;

taking a first pressure measurement of tire pressure about four hours after inflating the tire;

taking a second pressure measurement of tire pressure about two hours after the first measurement;

determining a difference between the first pressure measurement and the second pressure measurement; and

determining whether the difference is indicative of an acceptable leakage rate.

2. The method of claim 1 wherein said step of determining whether the difference is indicative of an acceptable leakage rate comprises the steps of:

determining an acceptable 12 hour pressure loss;

determining one sixth of the acceptable 12 hour pressure loss to obtain an acceptable two hour pressure loss; and

determining whether the acceptable two hour pressure loss is greater than the difference between the first pressure measurement and the second pressure measurement.

3. The method of claim 2 including the additional steps of:

taking a first temperature measurement when the first pressure measurement is taken;

taking a second temperature measurement when the second pressure measurement is taken;

determining a difference between the first temperature and the second temperature; and

compensating for pressure changes caused by the temperature difference when determining the acceptable two hour pressure loss.

4. A method of tire inspection comprising the steps of:

inflating a tire;

allowing the tire to rest until a moving one hour average of tire pressure loss for the tire falls below 0.1 percent;

after allowing the tire to rest, taking a first tire pressure measurement at a first time;

taking a second tire pressure measurement at a second time after the first time; and

determining whether a difference between the first tire pressure measurement and the second tire pressure measurement is indicative of an acceptable leakage rate.

5. The method of claim 4 wherein said step of determining whether a difference between the first tire pressure measurement and the second tire pressure measurement is indicative of an acceptable leakage rate comprises the step of comparing the pressure change between the first time and the second time with an acceptable pressure change over a time period longer than the time between the first time and the second time.

6. The method of claim 5 including the additional steps of measuring the temperature of the tire at the first time and measuring the temperature of the tire at the second time and wherein said step of determining whether a difference between the first tire pressure measurement and the second tire pressure measurement is indicative of an acceptable leakage rate comprises the step of compensating for pressure changes caused by a difference between the first temperature and the second temperature.

7. A method of determining whether a tire will satisfy a t hour pressure retention standard in about x hours where x is less than t comprising the steps of:

determining a tire pressure stabilization time z;

inflating a tire at time t0 to a first pressure;

taking a first pressure measurement at (x-y) hours after t0 where (x-y)≧

z;

taking a second pressure measurement at x hours;

determining a change in pressure between the first pressure measurement and the second pressure measurement; and

determining from the change in pressure whether the tire will satisfy the t hour pressure retention standard.

8. The method of claim 7 including the additional step of setting z equal to 3.5.

9. The method of claim 7 wherein said step of determining from the change in pressure whether the tire will satisfy the t hour pressure retention standard comprises the steps of determining the pressure loss L allowable under the t hour pressure retention standard, determining L times y/t, and determining whether the determined change in pressure is greater than L×

y/t.

10. The method of claim 9 wherein said step of determining whether the determined change in pressure is greater than L times y/t comprises the step of compensating for pressure changes caused by temperature changes between the first pressure measurement and the second pressure measurement.

11. The method of claim 10 wherein said step of determining whether the determined change in pressure is greater than L times y/t includes the additional step of correcting for measurement-related pressure loss.

12. A tire pressure retention calculator comprising:

input means for inputting starting and ending tire pressure data, starting and ending tire temperature data and a percentage of loss allowed;

calculating means for calculating from the tire pressure data a tire pressure change;

from the tire temperature data a tire temperature change and a temperature effect; and

from the starting tire pressure and temperature effect a pressure loss allowed; and

determining means for determining from the pressure loss allowed and ending tire pressure whether the tire pressure change is greater than or less than the pressure loss allowed.