System for monitoring the tire pressure in vehicles
Described is a procedure for controlling the transmission operation of a tire pressure monitoring device ( 1 ) arranged in a pneumatic tire of a vehicle, whereby data telegrams are transmitted in a normal mode of operation ( 13 ) in first time intervals, and there is a changeover from the normal mode of operation ( 13 ) to a pressure drop mode, if an inspection of the pressure signals indicates a drop in the pressure of a drop speed exceeding a pre-defined threshold value, and data telegrams are transmitted in the pressure drop mode in second time intervals, which are shorter than the first time intervals, and the tire pressure monitoring devices ( 1 ) are put into a travel starting mode ( 10, 11, 12 ) at the beginning of the travel by activation a roll sensor. Data telegrams are transmitted in the travel starting mode in shorter third time intervals as compared to the normal mode of operation.
1. System for monitoring the tire pressure in vehicles, comprising tire pressure monitoring devices, which are each to be arranged in one of the pneumatic tires of the vehicle and comprise a pressure sensor, a roll sensor, a control unit, a power source and a transmitter, an evaluation unit for installing in the vehicle in a stationary manner comprising a receiver for evaluating data telegrams transmitted by the tire pressure monitoring devices, said data telegrams containing a pressure information and a characteristic identifier of the tire pressure monitoring device, whereby the tire pressure monitoring devices transmit the data telegrams in first time intervals in a normal mode of operation, switch from the normal mode of operation to a pressure drop mode if an evaluation of pressure signals shows a pressure drop having a pressure drop speed exceeding a pre-defined threshold value and transmit data telegrams in the pressure drop mode in second time intervals, which are smaller than the first time intervals, the evaluation unit assigns the characteristic identifiers to the respective wheel positions at the beginning of the travel by means of a statistic evaluation of the reception level of data telegrams, and an activation of the roll sensor at the beginning of a travel causes the corresponding tire pressure monitoring devices to switch to a travel starting mode, in which data telegrams are sent in third time intervals, which are shorter than the first time intervals of the normal mode of operation, wherein the tire pressure monitoring devices begin with the process of transmitting a data packet comprising several data telegrams after switching to the travel starting mode, it is checked, after the transmission of a first part of the data packet, if the roll sensor is still detecting a turning of the wheel, and if not, the process of transmission of the data packet is interrupted, whereby the process of transmitting the data packet is continued further if the roll sensor is re-activated within a pre-defined time span, and the process of transmitting the data packet is started all over again if the roll sensor is re-activated only after the lapse of the pre-defined time span, and whereby the tire pressure monitoring devices switch to the normal mode of operation after complete transmission of a data packet.
2. System as defined in claim 1 , wherein the pre-defined time span has the duration of 5 to 30 minutes, preferably 10 to 20 minutes.
3. System as defined in claim 1 , wherein the number of data telegrams of the data packet is specified.
4. System as defined in claim 1 , wherein the data packet contains a total of 15 to 25 data telegrams.
5. System as defined in claim 1 , wherein the first part of the data packet contains several data telegrams, preferably 4 to 6 data telegrams.
6. System as defined in claim 1 , wherein it is checked, after the transmission of a second part of the data packet, whether the roll sensor continues detecting a turning of the wheel, and if not, the process of transmission of the data packet is interrupted, whereby the process of transmitting the data packet is continued further if the roll sensor is re-activated within another pre-defined time span and the process of transmitting the data packet is started all over again if the roll sensor is re-activated only after the lapse of this other pre-defined time span.
7. System as defined in claim 1 , wherein the duration of the first time intervals depends on the traveling speed.
8. System as defined in claim 1 , wherein the second time intervals are constant.
9. System as defined in claim 1 , wherein the third time intervals are constant.
10. System as defined in claim 1 , wherein a changeover from the normal mode of operation to the travel starting mode takes place only if the rolling switch does not detect a turning of the wheels beforehand during a pre-defined time span.
11. System as defined in claim 10 , wherein the pre-defined time span is at least 10 minutes, preferably 15 to 30 minutes.