Tire pressure gauge with temperature correction

• US 6,722,193 B1
• Filed: 03/13/2003
• Issued: 04/20/2004
• Est. Priority Date: 03/13/2003
• Status: Expired due to Fees

• Current Assignee: David Lee Conway
• Original Assignee: David Lee Conway
• Inventors: Conway, David Lee
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): ALLEN, ANDRE J
• Application Number:
  US10/388,069
• Time in Patent Office: 404 Days
• Field of Search: 731/46, 731/462, 731/463, 731/465, 731/468
• US Class Current: 73/146.8
• CPC Class Codes: G01L 17/00 Devices or apparatus for measuring tyre pressure or the pressure in other inflated bodies

Abstract

A hand-held digital tire pressure gauge is designed such that it will provide valid tire pressure readings even for tires that have an elevated temperature due to the vehicle having been recently driven. The measurement from an ambient (outside) air temperature sensor is subtracted from the measurement of a sensor that employs a unique device for sampling inner tire air temperature and the result is then multiplied by a known factor representing the normal unit of air pressure variance experienced per unit of temperature variance. This value is then subtracted from the measurement of a tire air pressure gauge sensor to derive and display a “corrected” air pressure that the tire would have had if its inner air temperature were equal to the surrounding air temperature. The objective of the gauge is to help the user to realize increased fuel mileage, reduced tire wear, and improved handling and safety of the vehicle.

Claims

1. A method for deriving a valid tire pressure reading even after the vehicle has been recently driven and comprising:

a means to obtain a carefully-measured volume of air drawn from within the tire to flow over a temperature sensor and into an internal air chamber in the gauge;

a means to provide a delay time that disregards the initial said volume of air so as to purge the air pathways into the gauge and to allow the temperature sensor to acclimate to the changed air temperature;

a means to determine the ambient (outside of tire) air temperature also with a delay time to permit the sensor to acclimate;

a means to determine the internal tire (gauge) pressure;

an equation;

[Psub c=Psub t−

(Tsub t−

Tsub o×

C)] where Psub c is the corrected tire air pressure, Psub t is the actual tire pressure, Tsub t is the tire air temperature, Tsub o is the outside (of tire) air temperature, and C is a constant value representing the normal variance of air pressure as its temperature changes (estimated here at 0.08 psi per degree Fahrenheit) calculates a “

corrected”

tire air pressure,

wherein the said “

corrected”

tire pressure is a valid (equal to a “

cold”

tire) pressure reading even if the vehicle has been recently driven.

2. The method of claim 1 further comprising a passive (requiring no extra overt action by the user) piston and spring mechanism within an internal displacement air chamber that requires no battery power and wherein said piston is initially moved upward by the tire air pressure and shutting off, in positive manner, any further air entry into the gauge, after which said piston is then returned to the initial resting position by said spring following release of pressure from said gauge.

3. The method of claim 1 further comprising a fast-acting temperature sensor placed strategically within said gauge such that it ensures accurate tire air temperature measurement.

4. The method of claim 1 further comprising a hollow tube within said gauge which acts in the multiple capacities of:

conveying tire air to said displacement chamber as well as to a pressure sensor, providing a protected conduit for said tire temperature sensor wires, and serving as a guide for said piston within said air chamber.

5. The method of claim 1 further comprising a fast-acting ambient air temperature sensor strategically placed within a protective grid on said gauge where it is free from temperature influences from either tire air or user'"'"'s hand.

6. The method of claim 1 further comprising an automatic digital delay timer providing sufficient time following initial applied air pressure to allow for acclimation of temperature sensors.

7. The method claim 1 further comprising electronic circuits and components that accept the highest measurement of said tire pressure sensor and the delayed results of said temperature measurements.

8. The method of claim 1 further comprising of vent holes between said air displacement chamber and said circuit board portion of said gauge and holes to vent air from within said circuit board portion to the outside of said gauge.

9. The method of claim 1 further comprising a grip ring around outside of said gauge body place to assist user'"'"'s grip.