Apparatus for estimating vehicle tire air pressure from not only tired wheel motion but also tire temperature

• US 5,913,241 A
• Filed: 05/22/1997
• Issued: 06/15/1999
• Est. Priority Date: 05/23/1996
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Fujiwara, Kenji, Umeno, Takaji, Kawai, Hiroyuki, Ohashi, Hideki, Taguchi, Takeyasu, Kojima, Hiroyoshi
• Primary Examiner(s): Patel, Harshad
• Assistant Examiner(s): Clark, Robin C.
• Application Number:
  US08/861,737
• Time in Patent Office: 754 Days
• Field of Search: 73/146, 73/146.2, 73/146.5, 73/146.8, 340/443, 340/448, 340/449
• US Class Current: 73/146.2
• CPC Class Codes: B60C 23/061 by monitoring wheel speed measuring distance traversed on the ground by vehicles G01C22/00
• CPC Class Codes: B60C 23/062 Frequency spectrum analysis of wheel speed signals, e.g. using Fourier transformation
• CPC Class Codes: B60C 23/20 Devices for measuring or signalling tyre temperature only

Abstract

An apparatus for estimating an air pressure of a tire of a tired wheel of a motor vehicle, on the basis of a temperature of the tire as well as a motion of the tired wheel, preferably including a temperature-related variable sensor for detecting a temperature-related variable related to the temperature of the tire, and an estimating device for estimating the air pressure of the tire on the basis of the temperature-related variable as well as the motion of the tired wheel.

Claims

1. An apparatus for estimating an air pressure of a tire of a tired wheel of a motor vehicle, on the basis of a motion of said tired wheel, said apparatus comprising:

a wheel motion sensor for detecting the motion of said tired wheel;

a temperature-related variable sensor for detecting a temperature-related variable related to said temperature of said tire; and

estimating means for estimating the air pressure of said tire on the basis of said temperature-related variable as well as the motion of said tired wheel, said estimating means including;

provisional value calculating means for calculating a provisional value of the air pressure of said tire, on the basis of the motion of said tired wheel detected by said wheel motion sensor, such that said provisional value represents an actual value of said air pressure when said temperature-related variable detected by said temperature-related variable sensor is equal to a reference value; and

provisional value compensating means for compensating said provisional value calculated by said provisional value calculating means, on the basis of said temperature-related variable and according to a predetermined relationship between said temperature-related variable and a final value of said air pressure which is said provisional value compensated by said provisional value compensating means;

wherein the air pressure of said tire is estimated on the basis of a temperature of said tire as well as the motion of said tired wheel.

2. An apparatus according to claim 1, wherein said wheel motion sensor comprises a wheel speed sensor for detecting a rotating speed of said tired wheel as the motion of said tired wheel, and said provisional value calculating means comprises a disturbance observer designed according to a dynamic model of said tired wheel in which a rim and a belt are connected to each other rotatably relative to each other by a torsion spring, said disturbance observer estimating, as a disturbance acting on said tire and as a variable indicative of a state of said dynamic model, an amount of deviation of a spring constant of said torsion spring from a nominal value, on the basis of the rotating speed of said tired wheel which is detected by said wheel speed sensor as a rotating speed of said rim, said provisional value calculating means calculating said provisional value of said air pressure of said tire on the basis of said disturbance estimated by said disturbance observer.

3. An apparatus according to claim 1, wherein said provisional value calculating means calculates said provisional value of said air pressure of said tire on the basis of a frequency of at least one of a plurality of frequency components of the motion of said tired wheel within a predetermined frequency range, said at least one of said plurality of frequency components having a substantially largest intensity.

4. An apparatus according to claim 1, wherein said provisional value compensating means determines a compensating coefficient on the basis of said temperature-related variable detected by said temperature-related variable sensor, and according to a predetermined relationship between said compensating coefficient and said temperature-related variable, said provisional value compensating means calculating said final value of said air pressure of said tire by multiplying said provisional value by said compensating coefficient.

6. An apparatus according to claim 1, wherein said temperature-related variable detected by said temperature-related variable sensor is an ambient temperature of said motor vehicle.

7. An apparatus according to claim 6, wherein said motor vehicle has an air conditioning apparatus including an ambient temperature sensor for detecting said ambient temperature to effect air conditioning in the motor vehicle, said ambient temperature sensor being utilized as said temperature-related variable sensor.

8. An apparatus according to claim 4, wherein said provisional value compensating means includes a memory in which said predetermined relationship is stored, said predetermined relationship is formulated to change said compensating coefficient in steps with said temperature-related variable.

5. An apparatus for estimating an air pressure of a tire of a tired wheel of a motor vehicle, on the basis of a motion of said tired wheel, said apparatus comprising:

a wheel motion sensor for detecting the motion of said tired wheel;

a temperature-related variable sensor for detecting a temperature-related variable related to said temperature of said tire;

estimating means for estimating the air pressure of said tire on the basis of the motion of said tired wheel detected by said wheel motion sensor;

determining means for determining whether said air pressure estimated by said estimating means is abnormal, on the basis of the estimated air pressure as compared with a predetermined threshold; and

compensating means for compensating said predetermined threshold on the basis of said temperature-related variable detected by said temperature-related variable sensor;

wherein the air pressure of said tire is estimated on the basis of a temperature of said tire as well as the motion of said tired wheel.