EP1713648A1

EP1713648A1 - Device for monitoring a motor vehicle tyre pressure

Info

Publication number: EP1713648A1
Application number: EP05716668A
Authority: EP
Inventors: Andreas Heise; Jens Bachon; Ralf Hartmann; Artur Otto
Original assignee: Continental Teves AG and Co OHG
Current assignee: Continental Teves AG and Co OHG
Priority date: 2004-02-12
Filing date: 2005-02-11
Publication date: 2006-10-25
Also published as: CN1918012A; JP2007522464A; US20070277602A1; WO2005077681A1; KR20060130654A

Abstract

The invention concerns a device for monitoring a motor vehicle tyre pressure, said device comprising at least one control apparatus (6) and/or at least one central box (10), which are connected by conduits of wheel speed sensors and control conduits (5) or still by conduits of wheel speed sensors (11) and by steering conduits (13) to transceivers (4) mounted in the wheel passage zones. Said transceivers are used for wireless transmission of the information in one or two directions and energy transmission with a transponder (1) arranged in a wheel or tyre proximate the wheel passage.

Description

Tire pressure monitoring device for a motor vehicle

The invention relates to a tire pressure monitoring device for a motor vehicle according to the preamble of claim 1.

Reliable monitoring of the tire pressure on all wheels of a motor vehicle or a motorcycle is of great importance for the safety of the vehicle. There are various approaches as to how the tire pressure monitoring systems can be implemented. In the case of the so-called directly measuring tire pressure monitoring systems, the tire air pressure is measured directly in the tire and transmitted to an evaluation electronics by means of transmitting and receiving devices. Such a directly measuring tire pressure monitoring system is described, for example, in DE 199 38 431 C2. The tire air pressure is usually recorded by means of a battery-powered pressure module and sent to one or more receiver modules by means of radio transmission. A major disadvantage of these known systems is that the use of a battery severely limits the service life of the printing module and the limited environmental compatibility due to pollutants in the batteries. Another disadvantage is that usually a high level of electronics is required if the individual pressure modules are to be assigned to certain installation positions (e.g. front left wheel, front right wheel, etc.). From DE 199 26 616 C2, for example, a method for carrying out an assignment of tire pressure control devices is known. A further possibility for monitoring the tire air pressure is that a batteryless transponder is attached in or on the tire, which is supplied with energy externally, for example by means of radio waves. This transponder records the tire air pressure and sends it to an evaluation unit for further processing. For example, from DE 199 24 830 AI a device for measuring pressure and temperature in motor vehicle tires and for wear monitoring is known, which includes a transponder for detecting the tire air pressure. Another tire pressure monitoring system with a transponder is known from EP 0 832 765 B1. A method for tire condition monitoring by means of a transponder is also known from US 6,400,261 B1. Furthermore, a device for monitoring and identifying pneumatic tires is described in EP 1 354 729 AI.

The object of the present invention is to provide a tire pressure monitoring device which can detect and assign a pressure loss on several tires of a motor vehicle or motorcycle in a reliable and inexpensive manner.

This object is achieved according to the invention by a tire pressure monitoring unit according to claim 1.

In a preferred embodiment, in the vicinity of each wheel, particularly preferably in each wheel arch of the vehicle, there is a wheel arch transceiver which corresponds to a transponder and is connected to a wheel speed sensor. All wheel box transceivers are preferably connected to a single control unit and / or a single central box via wheel speed sensor and control lines.

In a further preferred embodiment, data is only sent and received between the wheel arch transceiver and the transponder in a certain angular range of the wheel, the so-called transmission range A.

The circuit board of a transmission antenna is preferably connected to a wiring harness of the vehicle by means of press-in contacts.

In a further preferred embodiment, data of the transponder are only transmitted after sufficient energy has been collected over a number of wheel revolutions by means of an intermediate store arranged in the transponder.

The transmission frequency of the wheel arch transceiver is preferably in the range from approximately 0.8 kHz to approximately 800 kHz, particularly preferably in the range from approximately 70 kHz to approximately 200 kHz.

The transmission frequency of the transponder is preferably in the range from approximately 0.8 MHz to approximately 800 MHz, particularly preferably in the range from approximately 5 MHz to approximately 100 MHz.

In a further preferred embodiment, the transmission frequency of the transponder is modulated for data transmission.

The data transmission from the wheel arch transceivers to the control unit or the central box preferably takes place via the wheel speed sensor lines already present in the vehicle. The data are also particularly preferably transmitted from the control unit or the central box via the wheel speed sensor lines to the wheel arch transceivers or the transponders.

It is further preferred to modulate the data of the wheel arch transceiver to be transmitted onto the data of the wheel speed sensors.

The control device is preferably integrated into a brake control device (ECU) of the motor vehicle.

Further preferred embodiments result from the subclaims. The invention is described below with reference to figures. Here shows:

1 shows a tire pressure monitoring system according to the invention,

2 is a view of the built-in transponder,

3 shows a second embodiment of the tire pressure monitoring system according to the invention,

4 shows a third embodiment of the tire pressure monitoring system according to the invention,

Fig. 5 possible arrangements of transmit antennas and transponders on the vehicle wheel, and

Fig. 6 shows the structure of a transmission antenna according to the invention.

1 shows an overview of the tire pressure monitoring system according to the invention. A transponder 1 sends tire information and / or other data to a wheel arch transceiver 4 and receives energy and / or data signals from the wheel arch transceiver 4. The wheel arch transceiver 4 keeps further data via a wheel speed sensor line 3 from a wheel speed sensor 2. The wheel arch transceiver 4 is supplied with energy via a supply line 7 and exchanges data via a wheel speed sensor and control line

5 with the control unit 6. In Fig. 1 only the connection of a wheel arch transceiver 4 with the control unit 6 is shown. According to the invention is located near each wheel, for. B. in each wheel arch of the vehicle, a wheel arch transceiver 4, which corresponds to a transponder 1 and is connected to a wheel speed sensor 2. All wheel arch transceivers 4 are in this case via wheel speed sensor and control lines 5 with a single control device

6 connected. A tire pressure monitoring system according to the invention for a four-wheel vehicle thus has a control unit 6, four wheel box transceivers 4 connected to the control unit 6, four transponders 1 and four wheel speed sensors 2 connected to the wheel box transceivers 4.

A tire pressure monitoring system according to the invention for a two-wheeled vehicle thus has a control unit 6, two wheel arch transceivers 4 connected to control unit 6, two transponders 1 and two wheel speed sensors 2 connected to wheel arch transceivers 4. In the case of motorcycles, the wheel arch transceivers 4 are arranged on the inside of the fender. If this is not possible, e.g. B. in off-road motorcycles (enduro) due to the large distance between the fenders to the tires, which would make the transmission path between the wheel arch transceiver 4 and transponder 1 too large, the wheel arch transceiver 4 can also at other suitable locations, for example on the immersion or stanchions be arranged. FIG. 2 shows a wheel 9 of a vehicle, in the interior of which the transponder 1 is located. The wheel arch transceiver 4 is arranged above the wheel. Data from and to the transponder 1 can only be sent and received in a certain angular range of the wheel, the so-called transmission range A.

A second embodiment of the tire pressure monitoring system according to the invention is shown in FIG. 3. 1, the wheel arch transceivers 4 are not connected directly to the control unit 6, but a central box 10 is interposed between the wheel speed sensor lines 11a-11d and 12a-12d. Furthermore, the central box 10 is connected to wheel arch transceivers 4 (not shown) via control lines 13a-13d. The central box 10 is supplied with energy via the connections 14, 15, 16. The central box 10 can exchange data with a vehicle data bus (CAN, LIN, etc.) or other systems via a data line 17.

FIG. 4 shows a third embodiment of the tire pressure monitoring system according to the invention. The tire pressure monitoring system known from FIG. 3 is supplemented in that an additional transponder antenna is installed on the central box 10. B. corresponds to another transponder in an ignition key, can be connected to a connecting line 18. This additional transponder antenna can then be controlled via an additional control line 19. This makes it possible, for example, to deactivate an immobilizer when the transponder is in the ignition key is recognized as belonging to the vehicle.

5 shows possible arrangements of transmission antennas 20, 21 and transponders 1 on the vehicle wheel 9. The transmission antennas 20, 21 can be components which can be connected to the transceivers 4, or the transmission antennas 20, 21 are structurally combined with the transceivers 4. The transmission antennas 20, 21 essentially consist of coils without a ferrite filling (transmission antennas 20) or of coils with a filling (transmission antenna 21), for example a ferrite core for magnetic circuit optimization. It is of course possible to replace the coils shown in FIGS. 5a, 5b, 5d, 5e without a ferrite filling by coils with a ferrite core, as shown in FIG. 5c, to optimize the magnetic circuit. Fig. 5a shows a wheel 9 with two laterally arranged transmission antennas 20 and a vertically standing transponder 1. This arrangement is very well suited for motorcycles, in particular for enduros, in which the transmission antennas 20 or the transceivers 4 are mounted on the inside of the Fender is not possible. Furthermore, the arrangement according to FIG. 5a offers the advantage that, owing to the two coils, a stronger field (electric or magnetic field) is established with a lower current strength or a lower number of turns of the coil. FIG. 5b shows an arrangement similar to FIG. 5a, only the transmit antennas 20 being arranged in a common housing. 5c, like FIG. 5b, has two coils in a common housing, the coils here having a ferrite core for optimizing the magnetic circuit. 5d shows the preferred arrangement of the transmission antenna 20 to the transponder 4 for use in cars and trucks. 5e shows a ne lateral arrangement of the transmitting antenna 20 to the wheel and a transponder arranged on the tire flank 1. Especially in vehicles with large travel, z. B. Enduros or SUVs, the lateral arrangement of the transmitting antenna (s) 20 only enables transmission between transponder 1 and transceiver 4, which would not be possible in an arrangement according to FIG. 5d due to the large distances between transponder 1 and transceiver 4.

The structure of a transmission antenna 20 according to the invention is shown in FIG. 6. 6a shows a lower housing part 29 with a printed circuit board 26 on which several components 28, here SMD components, are arranged. The connection between the printed circuit board 26 and a cable harness (not shown) of the vehicle takes place, for example, by means of press-in contacts 24. Of course, other connection techniques, such as soldered plug contacts, etc., are also possible. A coil 23 is connected to the printed circuit board 26 by means of insulation displacement contacts 25. Above the lower housing part 29 there is an upper housing part 22 which, as shown in FIG. 6b, is connected to the lower housing part 29 by means of a friction welding process, represented by a friction welding contact point 27. In addition to a friction welding process, other processes, such as. B. a screw or an adhesive, for connecting the lower housing part 29 to the upper housing part 22 is conceivable. 6c shows a variant of a transmission antenna 20, in which instead of plug-in contacting, direct connection of a cable outlet 30 to the printed circuit board 26 is made by means of insulation displacement contacts 31. The coils 23 can either have a material filling, for example a ferrite filling, or no ferrite filling. The components 28 serve for reinforcement of signals. Since the electrical or magnetic field of a coil is never actually optimally aligned, further coils can be used to “guide” the field. The field profile of a coil can be influenced by a coil with another field that has the same or an inverse field profile As a result, the field of the coil can be directed onto the transponder 1, which results in an increase in efficiency.

In a vehicle with an electronic braking system (EBS), such as. B. an anti-lock braking system (ABS) or an electronic stability system (ESP), wheel speed sensors 2 are already available for detecting wheel speeds, which are connected to a brake control unit via connecting lines. These wheel speed sensors 2 and partly also the connecting lines are used by the tire pressure monitoring system according to the invention. In the tire pressure monitoring system according to the invention, a wheel arch transceiver 4 is attached near each wheel, which is connected to the wheel speed sensor 2 located on this wheel and to the control unit 6 or a central box 10. There is also between the wheel arch transceiver 4 and a transponder 1 in or on a tire, in the vicinity thereof, for. B. in the wheel arch, the wheel arch transceiver 4 is a wireless connection. The wheel arch transceiver 4 essentially comprises a transmission antenna 20, 21 with control electronics, which transmits energy to the transponder 1. Furthermore, data can also be transmitted into the transponder 1 via the transmission antenna 20, 21. The wheel arch transceiver 4 further comprises a receiving antenna for receiving the data transmitted by the transponder 1 and an amplifier circuit for amplification of the received data. The transmit and receive antennas work in different frequency ranges. The transmission frequency of the transponder 1 is expediently designed such that only a low transmission energy is necessary. The transmission frequency of the wheel arch transceiver 4, on the other hand, must be designed so that even when the vehicle is traveling fast enough energy can be transmitted in the short transmission range A from the wheel arch transceiver 4 to the transponder 1 so that the transponder 1 can transmit tire information. There is also the possibility for the transponder 1 to collect sufficient energy over several wheel revolutions (temporary storage) and to send the data at the appropriate time only when there is sufficient energy. Furthermore, the frequencies used should correspond to the country-specific regulations on the freely usable frequency ranges. Suitable frequencies are, for example, in the HF or MF range, for the transmission frequency of the wheel arch transceiver 4 z. B. a frequency in the range of about 0.8 kHz to about 800 kHz, in particular about 70 kHz to about 200 kHz, and for the transmission frequency of the transponder 1 z. B. a frequency in the range of about 0.8 MHz to about 800 MHz, in particular about 5 MHz to about 100 MHz, is suitable. Previous transponder-receiver systems are usually only designed for short transmission distances (approx. 30 cm distance between transponder and receiver). By separating the receiving device into a control device 6 or a central box 10 and a plurality of wheel arch transceivers 4, this small transmission distance can be increased to a few meters by the tire pressure monitoring system according to the invention. The transponder 1 sends and receives data or energy via the wheel arch transceivers 4 arranged in the immediate vicinity of the transponder 1. The wheel arch transceivers 4 are received Control signals from the remote control device 6 or the remote central box 10. Modulation, for example amplitude modulation (ASK), frequency modulation (FSK) or phase modulation (PSK), is recommended for the data transmission to the transponder 1, the transmission frequency. With (analog) amplitude modulation (ASK) (digital) data is transmitted by switching the signal amplitude between normal power (corresponds to the digital "1") and zero power (corresponds to the digital "0") an actually analog data transmission it is nevertheless possible to transmit digital signals.

The data transmission from the wheel arch transceivers 4 to the control unit 6 or the central box 10 takes place here via the wheel speed sensor lines 3, 11 already present in the vehicle. The data to be transmitted from the wheel arch transceiver 4 are modulated onto the data from the wheel speed sensors 2. Data can also be transmitted from the control unit 6 or the central box 10 via the wheel speed sensor lines 3, 11 to the wheel arch transceiver 4 or the transponder 1.

The control unit 6 can e.g. B. be integrated in a brake control unit (ECU). If this integration is not possible, a central box 10 is used, which takes over the tasks of the control device. The central box 10 is connected between the wheel speed sensor lines 11, 13. The central box 10 forwards the data received and evaluated via the wheel speed sensor lines 11 to a vehicle data bus (for example CAN, LIN, etc.) for further processing, display or evaluation. This data can can also be passed on in a manner known per se in the form of digital signals. If, for example, there is a loss of tire air pressure, this can be communicated to the driver and possibly other vehicle systems.

To determine a tire pressure, control signals are transmitted from the control unit 6 or the central box 10 to the wheel arch transceiver 4. The wheel arch transceivers 4 send energy and / or data signals to the associated transponders 1. The energy and / or data signals of the wheel arch transceivers 4 are received and / or converted by the associated transponders 1. After sufficient energy has been received, the transponders 1 use sensors to read tire information, such as e.g. B. the tire air pressure or the tire temperature, and then send out this tire information by means of a transmitter arranged in the transponder 1. The transmitted tire information is received by receiving antennas arranged in the associated transceivers 4 or connectable to the transceivers 4. The received tire information may be forwarded to the control unit 6 or the central box 10. The tire information is then evaluated in control unit 6 or central box 10 and displayed to the driver in general, or only in the event of a tire defect.

The control signals for controlling the wheel arch transceivers 4 can be transmitted either simultaneously or in succession. When the wheel arch transceivers 4 are activated simultaneously, which means that all wheel arch transceivers 4 carry out an energy transfer to the transponder 1 assigned to them, the transponders 1, as soon as they have sufficient energy to transmit tire information (tire pressure, temperature, etc.), transmit the tire information to the wheel arch transceiver 4. The wheel arch transceivers 4 amplify the tire information received from the transponders 1 and send this to the control unit 6 or the central box 10. As a result, as quickly as possible, e.g. B. already when starting the vehicle, tire information available, which can be evaluated with regard to a possible loss of tire pressure. This can be done for all wheels or only for the front wheels or only for the rear wheels. An assignment of the received tire information to an installation position is not possible without further information, for example in the form of tire identifiers, which are sent together with the tire information.

If, however, the wheel arch transceivers 4 are individually controlled, it is possible to assign the received tire information to an installation position. Here, the control unit 6 or the central box 10 must know the installation position of a wheel arch transceiver 4. It can also e.g. B. all wheel arch transceivers 4 are controlled in succession to teach the positions of the transponder 1. In this case, the wheel arch transceiver which is in the installation position "wheel front left" is then first activated. The transponder signal then received is assigned to the installation position "wheel front left". An identifier can then also be written into the transponder so that this transponder is in the installation position "wheel front left". This identifier can be implemented in the form of a number code the further data transmission are also sent by the transponders, which means that the transmitted tire information is always associated with an installation position.

If tire information in the form of data signals is transmitted from the wheel arch transceivers 4 to the control unit 6 or to the central box 10 by means of modulation onto existing wheel speed sensor lines 3, 11, these modulated data signals can be recovered by using transmitters. One transformer is required for each wheel speed sensor line. The output signals of the transmitters can then be permanently connected to a line without the option of recognizing the installation position of the transponder 1 being eliminated. Since the control unit 6 or the central box 10 can specifically address the wheel arch transceivers 4, and thus also the transponders 1, the data sent by the wheel arch transceivers 4 to the control unit 6 or to the central box 10 can be transmitted on only one line, despite transmission be specifically assigned to an installation position. The use of a multiplexer or similar devices as is required in the prior art is not necessary here, since the transponders 1 only send out tire information after the energy has been supplied beforehand.

In one embodiment of the tire pressure monitoring system according to the invention, the control device 6 or the central box 10 has a further input for a transponder antenna which, for. B. can evaluate and / or optionally describe a transponder integrated in the ignition key or a module (eg identification card) serving as an ignition key replacement. The control electronics for controlling the transmission antenna 20,

21 of the wheel arch transceiver 4 can consist of a conventional resonant circuit. However, depending on the power requirement, it is advisable to operate the transmission antenna by means of an H-bridge control, which means that practically no response times are required until the transmission power is reached, and by specifying the exact frequency, including the switch-off time, the coupling of data, for. B. by amplitude modulation (ASK) can be done exactly in time and very quickly. The transmission antenna 20, 21 can be implemented in the form of a flat-wound air coil (“flat antenna”), which is inserted into a housing 22, 29, for example made of plastic. This housing 22, 29 can also simultaneously control the control electronics and the receiving antenna for reception of the data transmitted by the transponder 1. The transmitting antenna 20, 21, the control electronics and the receiving antenna can also be integrated together with other components directly in the housing 22, 29 of the wheel arch transceiver 4. To protect the components, the housings 22, 29 are encapsulated , for example by a friction welding process, which comprises a lower housing part 29 of a two-part housing 22, 29 with an upper housing part

22 connects. In the transmitting antenna 20, 21, the magnetic field of the antenna is used for energy transmission. The contacting of the transmitting antenna 20, 21 and / or of connecting lines can, for. B. by means of insulation displacement contacts. For a plug connection, for example between the housing 22, 29 of the transmitting antenna 20, 21 or the transceivers 4, press-in technology is used for contacting. A learning phase for recognizing the relative position of the transponder 1 to the associated wheel arch transceiver 4 can also be carried out. Since a certain distance between the transponder 1 and the wheel arch transceiver 4 may not be exceeded in the transponder technology for transmitting data, only a certain transmission area A for transmitting data between the transponder can be attached to a transponder 1 in or on a tire 1 and the wheel arch transceiver 4 can be used. When the wheel arch transceiver 4 receives data from the transponder 1, a counter assigned to the associated wheel speed sensor 2 can be read out or reset at this point in time, as a result of which the position of the transponder 1 relative to the wheel rotation is known. For example, the wheel speed sensor 2 has a number of edges of 42 edges per wheel revolution. If data is now received by the transponder 1, the number of edges of the wheel speed sensor 2 is also counted. For example, the edge 23 is determined when the transponder data is received. The information about the relative position of the transponder 1 to the wheel speed sensor 2 is determined by the control unit 6 or the central box 10. In the following, only the power or data transmission from the wheel arch transceiver 4 to the transponder 1 is carried out if the transponder 1 is in the vicinity, in the example at the flank 23 of the wheel speed sensor 2, of the wheel arch transceiver 4. An area can also be defined, for example five edges before the edge 23 and five edges after the edge 23, in which the wheel arch transceiver 4 transmits due to the control by the control unit 6. By determining the position of the transponder 1, the power consumption can be drastically reduced compared to conventional transponder solutions. The Information about the relative position can also be stored via an ignition run of the vehicle, so that this information is immediately available even when the ignition is restarted.

Furthermore, the wheel speed sensors 2 can be evaluated to determine whether there is excessive wheel slip, which could result from a loss of tire pressure, on individual wheels. The information about the wheel slip can, for. B. can also be queried directly from the vehicle data bus or from the brake control unit. If there is no excessive wheel slip, the evaluation of the data sent by the transponders 1 can be reduced, which can be achieved by the control unit 6 or the central box 10 being controlled less frequently by the wheel arch transceiver 4.

The tire information sent from the transponders 1 via the wheel arch transceivers 4 to the control unit 6 or the central box 10 can be shown to the vehicle driver by a warning lamp or a display.

If runflat tires are used and it is recognized that the tire is being run in runflat mode, this can be indicated to the vehicle driver, or this information can also be passed on to other systems, for example by an intervention in the engine electronics to limit the maximum possible maximum speed of the vehicle.This monitoring of the run-flat tires and, for example, limitation of the maximum speed in the event of a defect in the run-flat wheels, means that the run-flat tires used can also be dimensioned weaker, which means costs and weight for the tires saves. The transponder 1 used comprises a converter which obtains energy and in particular data from electrical or magnetic waves, at least one sensor for detecting tire information and a transmitter for transmitting the tire information. Furthermore, at least one data memory for storing tire information and / or other data is present in the transponder 1. In the transponders 1, for example, data such as the date of manufacture of the tire, the mileage of the tire (by querying the mileage), possible tire damage or trips with insufficient air pressure can be stored, which, for. B. can be read out by a workshop.

The data stored in the transponders 1 data and / or the data collected from the transponders 1 (tire air pressure, temperature, etc.) can also be external to the receiver, for example by telemetry, ^"are transmitted.

The wheel speed sensor lines 3, 11, 12 are expediently designed in the form of twisted lines. If a control device 6 is used, the wheel speed sensor and control lines 5 can also be designed as twisted lines. Furthermore, the supply line 7 can be routed to the wheel arch transceivers 4 either together with the wheel speed sensor and control lines 5 or separately therefrom.

Claims

claims:

1. Tire pressure monitoring device for a motor vehicle with transponders (1) arranged in or on the wheels or tires, which communicate by means of wireless unidirectional or bidirectional information and energy transmission with in each case an associated wheel arch transceiver (4), characterized in that the tire pressure monitoring device has at least one Control unit (6) and / or at least one central box (10), which is connected via wheel speed sensor and control lines (5) or via wheel speed sensor lines (11) and control lines (13) to the wheel arch transceivers (4) arranged in the area of the wheel arches /are.

2. Tire pressure monitoring device according to claim 1, characterized in that the wheel arch transceivers (4) are connected to wheel speed sensors (2).

3. Tire pressure monitoring device according to claim 1 or 2, characterized in that the control device (6) or the central box (10), the wheel speed sensor and control lines (5) or the wheel speed sensor lines (11) for transmitting data from and to the wheel arch transceivers (4) used.

4. Tire pressure monitoring device according to at least one of the preceding claims, characterized in that the wheel arch transceivers (4) each have at least one transmitting antenna (20, 21) with control electronics for transmitting energy and / or data to the associated one Transponder (1), and a receiving antenna with amplifier circuit for receiving and amplifying the tire information sent by the associated transponder (1).

5. Tire pressure monitoring device according to claim 4, characterized in that the at least one transmission antenna (20, 21) of the wheel arch transceiver (4) for transmitting energy and / or data has an H-bridge control.

6. Tire pressure monitoring device according to at least one of the preceding claims, characterized in that the control device (6) or the central box (10) exchanges data with other systems in the vehicle via a data line (17).

7. Tire pressure monitoring device according to at least one of the preceding claims, characterized in that the control device (6) or the central box (10) has at least one connection line (18) and at least one additional control line (19) for controlling a further transponder.

8. Tire pressure monitoring device according to claim 7, characterized in that the further transponder is integrated in an ignition key or in an assembly suitable for starting the vehicle or for deactivating an immobilizer (e.g. card or key fob etc.).

9. Tire pressure monitoring device according to at least one of the preceding claims, characterized in that the at least one transmitting antenna (20, 21) for the energy transmission to the transponder (1) comprises at least one coil (23).

10. Tire pressure monitoring device according to at least one of the preceding claims, characterized in that the transmitting antenna (20, 21) for the energy transmission to the transponder (1) comprises at least one coil (23) with a ferrite core or a ferromagnetic core, which improves the magnetic flux for better Leads to the transponder (1).

11. Tire pressure monitoring device according to one of the preceding claims, characterized in that the transmitting antenna (20, 21) for energy transmission to the transponder (1) in addition to at least one coil (23) for energy transmission to the transponder (1) via further coils to increase the efficiency Guidance of the magnetic flux through the transponder (1).