Method and device for localizing the position of at least two emission units, especially for monitoring at least one parameter for a plurality of wheels pertaining to a motor vehicle

#The invention relates to a method and device for localizing the position of at least two emission units, especially for monitoring at least one parameter for a plurality of wheels pertaining to a motor vehicle.

#Monitoring the parameters of a wheel of a motor vehicle, for example, the tire pressure or the tire temperature is important for the reliability of the vehicle and/or the safety of the driver of the vehicle. In order to make the manual examination of such parameters unnecessary, devices were developed by means of which it is possible to automatically detect the important parameters of the wheels of a motor vehicle and to indicate them, for example, by means of corresponding display devices in the instrument panel. Because the usual requirement is to not only show the parameters, but also to ambiguously allocate the parameters shown to the position of the relevant wheel, it is necessary to develop such a device in such a way that this allocation is also retained or can be re-initialized after a wheel has been changed.

#To this end it is known that a receiver unit has to be allocated to each detector device which has been fitted to a wheel, in each case, and said receiver unit provided in the vicinity of the relevant wheel position. In this way, on the basis of the intensity of the signals received by a receiver unit it is possible to determine the signal of the neighboring detector device, in each case, by selecting the signal with the highest intensity. For this purpose it is assumed that the detector devices of the wheels of a motor vehicle essentially transmit with the same transmitting power so that the signal of the immediately neighboring wheel in each case or the neighboring detector device has the highest signal intensity at the receiving point.

#FIG. 1 a schematic diagram of a motor vehicle with a device for monitoring at least one parameter for a plurality of wheels pertaining to a motor vehicle and

#FIG. 2 diagrams with exemplary fictitious curves of reception signals depending on the angle position of the relevant wheel.

#The motor vehicle 1 shown schematically in FIG. 1 has a device 3 for monitoring at least one parameter for a plurality of wheels pertaining to a motor vehicle 1 and which includes a central evaluation and control unit 5 and four detector units 7, 9, 11, 13. The device 3 includes or at the same time serves as a device for localizing the position of emission units. One detector unit 7, 9, 11, 13 is allocated to one of the wheels 15, 17, 19, 21 of the motor vehicle 1 or fitted to said wheel and also fitted to said wheel when it is rotating.

#Each of the detector devices 7, 9, 11, 13 includes an emission unit 7a, 9a, 11a, 13a. Each of the emission units 7a, 9a, 11a, 13a transmits a short frequency or phase-modulated signal at predetermined times which, for the sake of information, includes a specific identification code for each detector device 7, 9, 11, 13 and possibly a value for the parameter of the wheel to be monitored. However, the latter is not required in the allocation mode. The specific identification code and the value of the parameter are preferably implemented in the form of digital information or in the form of a digital signal which is used as a modulation signal for the carrier signal of the transmitted signal.

#The signals sent by the detector units 7, 9, 11, 13 or their emission units 7a, 9a, 11a, 13a are received by the evaluation and control unit 5 by means of one of these included receiver units 23. The receiver unit 23 demodulates the reception signal and in this way enables the evaluation and control unit 5 to preferably evaluate the digital information signals, i.e. the specific identification code and the value for the parameter to be monitored. However, the latter is only mandatory in the normal monitoring mode.