Method and monitoring unit for monitoring a tire of a motor vehicle

1. A method for monitoring a tire of a vehicle, the method comprising the following steps:

a) recording a first measured value of revolutions of the tire with a first chassis-mounted sensor;

b) recording a second measured value of the revolutions of the tire or a second measured value of a second, different measured variable of the tire with a second sensor of a direct tire pressure monitoring system;

c) determining a deviation by comparing the first measured value with the second measured value or comparing the second measured value with a value of the second measured variable derived from the first measured value or comparing a value of a third measured variable of the tire derived from the second measured value with a value of the third measured variable derived from the first measured value; and

d) generating an error signal if the determined deviation is greater than a predefinable tolerance value.

2. The method according to claim 1 , which further comprises providing one or more of the following group of measured variables as the second or third measured variable: tire pressure, temperature, revolution time, rotational speed, wheel load, surface area of tire contact area or length of tire contact area.

3. The method according to claim 1 , which comprises, rather than performing a direct comparison of the measured values, carrying out one or more of the following: comparing the first time derivative of the measured values, comparing the second time derivative of the measured values, comparing a direction of change of the measured values, correlating the measured values over a predefinable time period.

4. The method according to claim 1 , which further comprises carrying out step c) by performing a reasonableness check of a first measured value and a second measured value of different measured variables, rather than a comparison of a first measured value and a second measured value of the same measured variable, and carrying out step d) by generating an error signal if the reasonableness check yields an implausible result.

5. A monitoring unit for monitoring a tire of a vehicle, the monitoring unit comprising:

a) means for recording a first measured value of revolutions of the tire with a first chassis-mounted sensor;

b) means for recording a second measured value of the revolutions of the tire or a second measured value of a second, different measured variable of the tire with a second sensor of a direct tire pressure monitoring system;

c) means for comparing the first measured value with the second measured value or comparing the second measured value with a value of the second measured variable derived from the first measured value or comparing a value of a third measured variable of the tire derived from the second measured value with a value of the third measured variable derived from the first measured value; and

d) means for generating an error signal if the determined deviation is greater than a predefinable tolerance value.

6. The monitoring unit according to claim 5 , wherein one or more of the following group of measured variables is provided as the second or third measured variable: tire pressure, temperature, revolution time, rotational speed, wheel load, surface area of a tire contact area or length of a tire contact area.

7. The monitoring unit according to claim 5 , wherein rather than directly comparing the measured values, said comparing means is configured to perform at least one of the following: a comparison of the first time derivative of the measured values, a comparison of the second time derivative of the measured values, a comparison of a direction of change of the measured values, a correlation of the measured values over a predefinable time period.

8. The monitoring unit according to claim 5 , wherein a reasonableness check of a first measured value and a second measured value of different measured variables is provided, rather than a comparison of a first measured value and a second measured value of the same measured variable, and an error signal is generated if the reasonableness check yields an implausible result.

9. The monitoring unit according to claim 5 , which further comprises a semiconductor device, said means for comparing and said means for generating an error signal being disposed in said semiconductor device, and at least one of a receiving means representing at least one input or a radio receiving module of said semiconductor device.

10. A monitoring unit for monitoring a tire of a vehicle, the monitoring unit comprising:

a) a first chassis-mounted sensor configured for monitoring a tire pressure and for recording a first measured value of revolutions of the tire;

b) a second sensor configured for directly monitoring the tire pressure and for recording a second measured value of the revolutions of the tire or a second measured value of a second, different measured variable of the tire;

c) a device for comparing the first measured value with the second measured value or comparing the second measured value with a value of the second measured variable derived from the first measured value or comparing a value of a third measured variable of the tire derived from the second measured value with a value of the third measured variable derived from the first measured value; and

d) a device for generating an error signal if the determined deviation is greater than a predefinable tolerance value.

11. A method for monitoring a tire of a vehicle, the method comprising the following steps:

a) recording a first measured value of revolutions of the tire with a first chassis-mounted sensor;

b) recording a second measured value of the revolutions of the tire or a second measured value of a second, different measured variable of the tire with a second sensor;

c) determining a deviation by performing one or more of the following process steps:

comparing a first time derivative of the measured values;

comparing a second time derivative of the measured values;

comparing a direction of change of the measured values; or

correlating the measured values over a predefinable time period; and

d) generating an error signal if the determined deviation is greater than a predefinable tolerance value.