Device and method for monitoring the air pressure in the tires of a motor vehicle

• US 6,946,954 B2
• Filed: 06/05/2003
• Issued: 09/20/2005
• Est. Priority Date: 12/05/2000
• Status: Active Grant

• Current Assignee: Volkswagen AG
• Original Assignee: Volkswagen AG
• Inventors: Piëch, Ferdinand, Reinke, Rolf, Wegner, Berend
• Primary Examiner(s): Lieu, Julie Bichngoc
• Application Number:
  US10/455,177
• Publication Number:
  US 20030227380A1
• Time in Patent Office: 838 Days
• Field of Search: 340/442, 340/443, 340/444, 731/46, 731/463, 731/465
• US Class Current: 340/444
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/061 by monitoring wheel speed measuring distance traversed on the ground by vehicles G01C22/00

Abstract

A device for monitoring air pressure in the tires of a vehicle includes devices for determining the wheel speed or other characteristic variables for the speed of the tires of the vehicle, a device for calculating differential variables on the basis of the wheel speed variables, a device for evaluating the differential variables with respect to a setpoint value deviation and for generating a warning signal if the setpoint value deviation exceeds a threshold value, and a device for directly measuring the air pressure in the tire of a wheel and for transferring an air pressure characteristic variable to the evaluation device. A warning signal is generated if the deviation of the air pressure characteristic variable with respect to a setpoint value exceeds a corresponding threshold value. A method of monitoring tire pressures is also provided.

Claims

1. A device for monitoring an air pressure in vehicle tires, comprising:

determining units configured to determine wheel speed variables characterizing wheel speeds of a motor vehicle;

a calculating unit operatively connected to said determining units and configured to calculate differential variables from the wheel speed variables;

an evaluation unit configured to evaluate the differential variables with respect to a setpoint value deviation, said evaluation unit generating a warning signal if the setpoint value deviation exceeds a first threshold value;

a measuring unit operatively connected to said evaluation unit, said measuring unit being configured to directly measure an air pressure in a tire of a wheel and configured to transmit a pressure variable characterizing the air pressure to said evaluation unit; and

said evaluation unit further generating a warning signal if a deviation of the pressure variable from a pressure setpoint value exceeds a second threshold value, said evaluation unit using a first tolerance range for a permitted setpoint value deviation of the differential variables, the first tolerance range representing a first pressure difference range, said evaluation unit further using a second tolerance range for a permitted setpoint value deviation of the pressure variable, the second tolerance range representing a second pressure difference range, the first pressure difference range being smaller than the second pressure difference range.

2. The device according to claim 1, wherein:

said evaluation unit determines for each respective tire a respective pressure variable from an air pressure variable measured by said measuring unit and from the differential variables, the respective pressure variable determined by said evaluation unit characterizes a respective air pressure of a respective tire; and

said evaluation unit evaluates whether a respective setpoint value deviation of the respective pressure variable determined by said evaluation unit exceeds a corresponding threshold value.

3. The device according to claim 1, including a temperature compensation unit operatively connected to said evaluation unit, said temperature compensation unit being configured to compensate at least one quantity selected from the group consisting of a measured pressure variable and the pressure setpoint value in order to determine a deviation of the pressure variable characterizing the air pressure.

4. The device according to claim 1, wherein said evaluation unit compares the wheel speed variables with a setpoint value formed as a mean value of all wheel speed variables.

5. The device according to claim 1, wherein:

said calculation unit determines the differential variables for respective two wheels; and

said measuring unit for directly measuring an air pressure is assigned to one of the respective two wheels.

6. The device according to claim 1, including:

at least a further measuring unit operatively connected to said evaluation unit for directly measuring an air pressure; and

said measuring unit and said further measuring unit being respectively assigned to one wheel of a respective wheel axle of the motor vehicle.

7. A method for monitoring an air pressure in tires of a motor vehicle, the method which comprises:

sensing wheel speed variables for wheels of a motor vehicle, the wheel speed variables characterizing wheel speeds;

forming differential variables from the wheel speed variables;

generating a warning signal if the differential variables deviate from a first setpoint value by more than a first threshold value;

directly measuring an air pressure in a tire of one of the wheels for providing a measured air pressure value;

generating a warning signal if the measured air pressure value deviates from a second setpoint value by more than a second threshold value; and

setting a first tolerance range for a setpoint value deviation of the differential variables and setting a second tolerance range for a setpoint value deviation of a variable characterizing an air pressure in a tire such that the first tolerance range represents a first pressure difference range and the second tolerance range represents a second pressure difference range and such that the first pressure difference range is smaller than the second pressure difference range.

8. The method according to claim 7, which comprises:

determining for each respective tire a respective pressure variable from a measured pressure variable and from the differential variables such that the respective pressure variable characterizes a respective air pressure of a respective tire; and

evaluating whether a respective setpoint value deviation of the respective pressure variable exceeds a corresponding threshold value.

9. The method according to claim 7, which comprises temperature-compensating at least one quantity selected from the group consisting of a measured pressure variable and the second setpoint value.

10. The method according to claim 7, which comprises comparing the wheel speed variables with a setpoint value formed as a mean value of all wheel speed variables.

11. The method according to claim 7, which comprises:

determining the differential variables for respective two of the wheels; and

directly measuring an air pressure of one of the respective two of the wheels.

12. The method according to claim 7, which comprises directly measuring the air pressure of one wheel of each wheel axle of the motor vehicle.