Method and system for ascertaining a pressure ratio between a setpoint tire pressure and an actual tire pressure for tire of a vehicle

Patent metadata

Field	Value
Publication number	US-10668778-B2
Application number	US-201414909332-A
Country	US
Kind code	B2
Filing date	Jul 18, 2014
Priority date	Aug 1, 2013
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

A pressure ratio between a setpoint tire pressure and an actual tire pressure for a tire of a vehicle is ascertained by the following steps:
Ascertaining a wheel load which is acting on the tire. Ascertaining a dynamic tire radius of the tire. Ascertaining the pressure ratio as a function of the wheel load and the dynamic tire radius.

First claim

The invention claimed is:

1. A method for indicating a vehicle tire pressure, the vehicle including a control device, a force sensor, a wheel sensor, a velocity sensor, and a display mounted in the vehicle, the method comprising:
measuring, by the force sensor, a wheel load acting on the tire based on a deflection of a suspension element;
measuring, by the wheel sensor, a number of rotations of the tire, and ascertaining, by the control device, a dynamic tire radius of the tire based on the number of rotations and a distance traveled by the vehicle;
measuring, by the velocity sensor, a velocity of the vehicle;
ascertaining by the control device, a tire rigidity based on a predefined tire rigidity function using the velocity of the vehicle and the wheel load;
ascertaining by the control device, a pressure ratio between a setpoint tire pressure and an actual tire pressure for the vehicle, as a function of the tire rigidity, the wheel load and the dynamic tire radius, and;
displaying, on the display, the pressure ratio.

2. The method according to claim 1 , wherein the pressure ratio is ascertained, by the control device, as a function of a constant of the tire, which indicates a setpoint ratio between the dynamic tire radius and an unloaded tire radius.

3. The method according to claim 2 , wherein:
the pressure ratio is calculated, by the control device, in accordance with the following equation:
p Rel =(1− c Actual )(1− c Ideal ),

p Rel being the pressure ratio, c Actual being a ratio between the dynamic tire radius and the unloaded tire radius, and c Ideal being the constant of the tire.

4. The method according to claim 1 , further comprising:
ascertaining, by a pressure sensor, an actual tire pressure of the tire; and
ascertaining, by the control device, a setpoint tire pressure of the tire, by multiplying the pressure ratio by the actual tire pressure.

5. The method according to claim 1 , further comprising:
ascertaining a tire rigidity;
ascertaining a difference between an unloaded tire radius of the tire in an unloaded state and the dynamic tire radius as a function of the wheel load and the tire rigidity; and
ascertaining the unloaded tire radius from a sum of the dynamic tire radius and the difference.

6. The method according to claim 5 , further comprising:
predefining a tire rigidity function;
detecting, by a pressure sensor, a tire pressure of the tire;
ascertaining, by a velocity sensor, a velocity of the vehicle; and
ascertaining, by the control device, the tire rigidity based on the tire rigidity function as a function of the tire pressure, the velocity, and the wheel load.

7. The method according to claim 5 , further comprising:
acquisition, by the control device, of measured values of an actual wheel load, by the force sensor, and an actual velocity of the vehicle, by a velocity sensor, at different points in time,
ascertaining a tire rigidity function, by the control device, which indicates the tire rigidity as a function of speed, the wheel load, and the tire pressure, based on the measured values recorded at different instants; and
ascertaining the tire rigidity, by the control device, as a function of the tire rigidity function.

8. A system for indicating a vehicle tire pressure, comprising:
a force sensor adapted to measure a wheel load acting on the tire based on a deflection of a suspension element;
a wheel sensor adapted to measure a number of rotations of the tire;
a velocity sensor adapted to measure a velocity of the vehicle; and a control device adapted to:
ascertain a dynamic tire radius of the tire based on the number of rotations of the tire the distance traveled by the vehicle;
ascertain a tire rigidity based on a predefined tire rigidity function using the velocity of the vehicle and the wheel load; and
ascertain a pressure ratio between a setpoint tire pressure and an actual tire pressure for the vehicle, as a function of the tire rigidity, the wheel load and the dynamic tire radius; and
a display, adapted to display the pressure ratio.

Assignees

• Volkswagen Ag

Inventors

• Steinmeyer Simon
• Meinecke Marc-Michael
• Degerman Pär
• Deeg Carsten

Classifications

• B60W40/13

  Load or weight · CPC title

• B60W40/105

  Speed · CPC title

• B60C23/061 Primary

  by monitoring wheel speed (measuring distance traversed on the ground by vehicles G01C22/00) · CPC title

• B60C23/0486 Primary

  comprising additional sensors in the wheel or tyre mounted monitoring device, e.g. movement sensors, microphones or earth magnetic field sensors · CPC title