WO2009040316A1

WO2009040316A1 - Keyless access system having emergency operation function

Info

Publication number: WO2009040316A1
Application number: PCT/EP2008/062564
Authority: WO
Inventors: Stefan Hermann; Michael Bräuer; Franz Plattner
Original assignee: Continental Automotive Gmbh
Priority date: 2007-09-20
Filing date: 2008-09-19
Publication date: 2009-04-02
Also published as: DE102007044871A1

Abstract

The invention relates to a keyless access system for a vehicle having a semi-stationary unit (1) mounted in or on the vehicle, comprising a transmitting (2) and receiving stage (3) for high-frequency signals (16), a semi-stationary transmitting stage (5) mounted in or on the vehicle for low-frequency signals (17), and a mobile unit (6) comprising a transmitting (7) and receiving stage (8) for high-frequency signals (16), a receiving stage (9) for low-frequency signals (17), and a power source (10) for providing its own power, and energy storage (11), wherein the mobile and the semi-stationary unit (1) exchange information wirelessly by means of the high-frequency signals (16) and, in case of emergency operation, if the power source (10) is not providing sufficient power to the transmitting and receiving stages (7, 8) for high-frequency signals (16), the semi-stationary transmitting stage (5) transmits energy to the receiving stage for low-frequency signals (17) in the mobile unit (6) by means of the low-frequency signals (17), said energy being stored in the energy storage (11) of the mobile unit and supplying the transmitting and receiving stage (7, 8) for high-frequency signals (16) in the mobile unit (6).

Description

description

Keyless entry system with emergency function

The invention relates to a keyless entry system with emergency function.

In a large number of vehicles, in particular motor vehicles, a large number of functions are already triggered or controlled via remote controls. Usually, a radio link is used in license-free frequency bands for the high-frequency transmission to and from the motor vehicle. For vehicle access and, for example, engine startup, these are so-called "remote keyless entry" systems (RKE systems for short), as used, for example, for centralized radio interlocking. RKE systems are now the standard solution not only for the comfortable locking and unlocking of a vehicle, but also for additional comfort functions. The control of these comfort functions by means of a usually integrated in a Fahrzeυgschlüssel radio control, which are used in addition to the locking and unlocking of the doors and the trunk also for activating and deactivating the immobilizer.

Other functions, such as comfortable opening and closing of windows, sunroofs, sliding doors or tailgates can also be integrated. Another comfort function and safety function is the activation of the apron lighting of the vehicle. Additional security is provided by a so-called integrated key

Emergency button that triggers an audible and visual alarm on the vehicle when pressed.

Depending on the requirements, such RKE systems work with uni- or bidirectional communication in the area of ISM frequencies released worldwide for this purpose. Further features include, for example, increased data transmission security through a challenge-response authentication. coding process (bidirectional) and low energy consumption. In addition, further applications provide for personalization of the functions of a RKE system to selected persons.

Another radio communication based system is the so-called PASE system. PASE stands for PAsive Start and Entry and describes a keyless access and start system. In this keyless vehicle access system, the driver only has to carry an identification transmitter (ID) with him and gets access to the vehicle by simply touching the door handle. As soon as the driver is inside the vehicle and there is valid communication between the transmitting and receiving unit of the mobile identification transmitter and a transmitting and receiving unit arranged quasi stationary in the motor vehicle, the motor can be started by pressing a button.

If the driver leaves the vehicle, the PASE system locks the vehicle either automatically or at the push of a button. The driver's identification card replaces conventional mechanical or radio controlled keys to provide maximum comfort and ease of use for the driver. Again, there is the possibility of personalization on selected people. Usually, a multi-channel bidirectional data transmission is used, which also takes place wirelessly and encrypted, for example in the range of the above-mentioned ISM frequencies.

All functions which enable such wireless data transmission via a keyless entry system require a source of energy which provides the energy necessary for the operation of the mobile transceiver unit (for example an identification transmitter). This energy source is usually a battery.

It is obvious that the above functions of the mobile transceiver are no longer available stand if the battery can no longer provide the energy necessary for the proper operation of the mobile transceiver unit, for example due to discharge or defect in the battery. Since a user usually does not constantly carry a replacement battery with him, in such a case, even access to the motor vehicle itself (see keyless identification transmitter and PASE) and its operation, such as the engine start (see deactivation of the immobilizer), not more is possible.

For this reason, a so-called emergency function has been integrated into such mobile, in-room access systems, which enables access to the motor vehicle and the starting of the motor vehicle, ie in particular the deactivation of the immobilizer. In this case, the energy supply of the mobile transmitting and receiving unit in the emergency case and the communication with the mobile transmitting and receiving unit according to the prior art via a field with low frequency, for example a magnetic field instead. The transmission of energy through a field of low frequency is known by so-called transponders.

A magnetic field with low frequency is limited in its range and therefore allows a safe restriction of the distance from which the corresponding functions can be performed. For safety reasons, for example, the immobilizer suspension may only be carried out if the mobile transmitting and receiving unit of the keyless entry system is within a maximum distance of 10 cm from a predefined point in the vehicle.

In the case of the emergency function, the transmission of the energy required for operating the mobile transmitting and receiving unit to the latter is usually carried out by the low-frequency magnetic field. The disadvantage here is that the communication also taking place via the low-frequency magnetic field between the mobile transmitting and receiving unit and a stationary transmitting and receiving unit in the motor vehicle generates a high level of energy. needs, which in turn has a negative impact. This leads to the fact that stronger magnetic fields are required for the power supply in order to continuously provide sufficient energy of the mobile transmitting and receiving unit.

At the same time in an emergency case, the possible removal of mobile transmitting and receiving unit to the vehicle or the defined point from which the low-frequency power supply from the vehicle takes place, limited. If the magnetic field drops below a value due to the distance, which no longer ensures the power supply of the mobile transmitting and receiving unit, no emergency function of the mobile transmitting and receiving unit can then be maintained. This may, for example, lead to a keyless PASE function that no access to the vehicle is possible because the said point could be due to the required proximity to the start button within the vehicle.

Object of the present invention is therefore to provide a mobile transmitting and receiving unit, the reliable power supply and a low-frequency magnetic field with a lower level can be used.

The object is achieved by a transmitting and receiving unit according to claim 1. refinements and developments of the inventive concept are the subject of dependent claims.

The task is solved by a mobile transmitting and receiving unit for a keyless entry system for a

Motor vehicle with at least one energy storage, which is charged by the low-frequency magnetic field and ensures the power supply of the transmitting and receiving unit in the emergency case, the mobile transmitting and receiving unit in case of emergency continue ausfuhrt a high-frequency communication with the vehicle-side transmitting and receiving unit, the less energy needed as a corresponding low-frequency communication. The invention will be explained in more detail with reference to the exemplary embodiments illustrated in the figures of the drawings, wherein like elements are provided with the same reference numerals. It shows:

1 shows a block diagram of a first exemplary embodiment of an inventive access system with a quasi-stationary unit with transmitting and receiving stage for high-frequency signals and a separate quasi-stationary unit with transmission stage for low-frequency signals;

FIG. 2 is a block diagram of a second exemplary embodiment of an access system according to the invention with a quasi-stationary unit which has both a transmitting and receiving stage for high-frequency signals and a transmitting stage for low-frequency signals;

FIG. 3 shows in a diagram the course of a low-frequency energy transmission and the high-frequency communication between the quasi-stationary and the mobile units; and

FIG. 4 is a diagram showing the sequence of the time-limited low-frequency energy transmission and the high-frequency communication between the quasi-stationary and the mobile units.

FIG. 1 shows in a block diagram an exemplary embodiment of an inventive access system, in which a quasi-stationary unit 1, a transmission stage 2 for generating high-frequency signals 16a (for example, large 200 kHz), a receiving stage 3 for evaluating high-frequency signals 16b and an antenna 12 for radiating and receiving the high-frequency signals 16a, 16b. The access system further comprises an activatable and deactivatable quasi- stationary unit 4 with a transmission stage 5 for generating never ^¬ derfrequenter signals 17 (for example, less than 200 kHz) and an antenna 13 for emitting these signals.

Furthermore, the access system according to FIG. 1 comprises a mobile unit 6 with a transmitting stage 7 for generating the high-frequency signals 16b and a receiving stage 8 for evaluating the high-frequency signals 16a and an antenna 14 for emitting and receiving the high-frequency signals 16b, 16a. Furthermore, the unit 6 according to Figure 1 on a Energiequel ^¬ le 10, an energy storage 11, a receiver stage 11 for evaluating the low-frequency signals 17 and an antenna 15 for receiving the low frequency signals 17th The quasi-stationary units 1 and 4 are for example mounted in or on a vehicle and the mobile unit 6 is carried along by a user of the vehicle.

According to FIG. 1, the transmitting and receiving antenna 12 of the quasi-stationary unit 1 is connected both to the transmitting stage 2 and to the receiving stage 3, and the transmitting antenna 13 is connected to the transmitting stage 5. In the mobile unit 6, the transmitting stage 7 and the receiving stage 8 are coupled to the transmitting and receiving antenna 14, and the receiving stage 9 is coupled to the receiving antenna 15. Furthermore, in the mobile unit 6, an energy source 10 is connected to the transmission stage 7 and the reception stage 8. The energy storage device 11 of the mobile unit 6 is connected to the transmitter stage 7, with the reception ^¬ stage 8 and to the receiving stage. 9

In a normal operating condition, when the power source 10 provides sufficient power for the operation of the transmitting stage 7 and the receiving stage 8, the receiving stage 8 and the transmitting stage 7 are energized by the power source 10 for their operation, as shown in FIG the arrows leading from the power source 10 to the transmitting and receiving stages 7 and 8 are shown. In this case, as a power source 10 of a mobile unit 6, a battery, for. As a non-rechargeable dry cell provided. about the high-frequency transmit and receive signals 16a, 16b (collectively also referred to as "16") are exchanged high-frequency information between the units 1, 6 when the mobile unit 6 is in sufficient proximity to the quasi-stationary unit 1, to a sufficient Field strength of the high-frequency signals 16 to ensure.

These information exchanged at high frequency between units 1 and 6 enable the convenience functions described above in vehicles such as the centralized radio interlock, the activation of the anti-theft device and the activation or deactivation of the immobilizer. The function of a keyless entry and start system (PASE) is also provided via the high-frequency communication between units 1 and 6. The additional processing logic necessary for this purpose is not shown in FIG. 1 for reasons of clarity.

In an emergency case, when the energy source 10, for example a battery, does not provide sufficient energy for the operation of the transmission stage 7 and the reception stage 8, the reception stage 8 and the transmission stage 7 are energized by the energy store 11 for their operation supplied, as indicated in Figure 1 by the energy storage 11 to the transmitting and receiving stages 7 and 8 leading arrows. If the low-frequency signals 17 are not transmitted continuously, this presupposes that such an emergency situation is detected by the keyless entry system and the energy store 11 is correspondingly charged with energy in order to enable the operation of the mobile unit 6 in such an emergency case ,

The triggering of the detection of an emergency case is carried out, for example, by a specific event and subsequent non-occurrence of a high-frequency communication between the quasi-stationary unit 1 and the mobile unit 6. This Nichtzeitandommen one due to the If the high-frequency communication between the units 1 and 6 triggered by the event is detected by the quasi-stationary unit 1 in the absence of corresponding high-frequency response signals of the mobile unit 6 upon request.

The particular events that draw lots a high-frequency communication between the quasi-steady unit 1 and the mobile unit 6, to an actuation of the start button for Mo ^¬ gate start of the vehicle or an operation of a door handle to be (PASE) at a schlussellosen access system, for example. If such a specific event occurs and then an emergency operation is detected, the transmission stage 5 of the quasi-stationary unit 4 is activated. As a result, the transmission stage 5 of the quasi-stationary unit 4 transmits a low-frequency signal 17 via the transmitting antenna 13 (see FIG. 1). Depending on the application, the signal can also contain information (compatibility with existing systems) or serve purely for energy transfer.

If the mobile unit 6 is sufficiently close to the transmission stage 5 at this point in time, the low-frequency signal 17 is received by the reception antenna 15 and evaluated by the reception stage 9, ie in any case the energy transmitted is processed and any information still contained is removed and forwarded to other units (not shown). However, the low-frequency signal 17 serves exclusively or at least primarily for the transmission of energy to the mobile unit 6 and supplies the mobile unit 6 with energy for its operation with sufficient field strength at the receiving location. For this purpose, the receiving stage 9 prepares the energy transmitted via the low-frequency signal 17 so that the energy store 11 can be charged with it. This is indicated in FIG. 1 by the arrow directed from the receiving stage 9 to the energy store 11. The energy storage ^device 11 is, for example, a capacitor, in particular a so-called gold cap of sufficient capacity. As soon as the energy accumulator 11 is ^¬ load with sufficient energy, it can now be used in emergency operation as a substitute for the power source 10 to operate the receiver stage 8 and the transmitter stage 7, whereby the desired high-frequency communication (signals 16) between the quasi-stationary unit 1 and the mobile unit 6 can be made available even in an emergency case. This is indicated in FIG. 1 by corresponding connections with arrows which lead from the energy store 11 to the transmitting stage 7 and to the receiving stage 8.

In contrast to known systems, in the case of systems according to the invention, a bidirectional high-frequency communication between quasi-stationary and mobile unit is maintained even in the emergency case of the wireless keyless system, whereby less energy is required for the communication without limiting the range of functions than with bidirectional low-frequency communication in an emergency situation would be the case. Moreover, in the present invention, without major losses, unidirectional communication from the quasi-stationary unit 4 to the mobile unit 6 would also be possible as well.

As described above, the quasi-stationary unit 1 can also be designed to control an immobilizer of the vehicle. In such a case must, for safety, in order to start the engine from a distance to unterbin ^¬, only a signal for deactivation of the immobilizer can be generated when the mobile unit is less than a maxi- mum distance from a certain point away on the vehicle. Such a certain point is typically located in the interior of a motor vehicle, for example at a distance from a receptacle for the mobile unit 6, in which it must be used in order to enable the engine to start the vehicle. The maximum distance to this particular point in the vehicle is for example 10 cm. The particular point in or on the vehicle may be given by the antenna 12, for example. In this case, the distance between the antenna 12 and the mobile unit 6 is determined via a field strength measurement. For this purpose, the field strength generated at the transmitting and receiving antenna 14 by means of the reception is ^¬ stage 8 in the mobile unit 6, and evaluated the value of the measured field strength is sent to the quasi-stationary unit. 1 In this way, the respective actual distance between the specific point in or on the vehicle and the mobile unit 6 can be reliably determined. Based on this information, the decision is then made as to whether the immobilizer can be deactivated.

Alternatively, in particular in an emergency case, the field strength of the low-frequency signal 17 can be evaluated that is transmitted to the mobile unit 6 for energy transmission by the transmission stage 5 of the quasi-stationary unit 4. In such a case, the transmitting antenna 13 defines the particular point in or on the vehicle, which is referred to for determining the distance of the mobile unit 6 by means of a field strength measurement, which in turn serves as a criterion for deactivating the immobilizer. For field strength measurement, the field strength generated by the quasi-steady unit 4 is at the location of the mobile unit 6, and more precisely at the location of the receiving antenna 15 evaluated and the value of the measured field strength is determined using high-frequency communication (signals 16) sent to the quasistatio ^¬ nare unit. 1

Furthermore, the quasi-stationary unit 1 of the in-lock access system can (also) be designed to control a keyless access control to a vehicle. In this case, as described above, an emergency case is determined when the operation of a door handle of a vehicle no high-frequency communication between the quasi-stationary unit 1 and the mobile unit 6 comes about, which initially would not be possible to access the vehicle. This access to the vehicle is then again allows when in case of emergency, as described above, the charge ^¬ the energy storage 11 is done and thus the high-frequency communication is possible.

In such a case, the transmission stage 5 of the quasi-stationary unit 4 must emit the low-frequency signal via the transmitting antenna 13 mounted in or on the vehicle with such high energy that charging of the energy accumulator 11 also occurs in the immediate vicinity of the vehicle (outside the vehicle interior). space). Here too, it is advantageously noticeable that the high-frequency communication between the mobile unit 6 and the quasi-stationary unit 1, even in an emergency case, requires significantly less energy than the hitherto customary bidirectional low-frequency communication in the emergency case.

The radiated energy or the field strength of the low-frequency signal 17 of the quasi-stationary unit 4 can accordingly be made smaller, which in turn has a favorable effect on costs and structural dimensions.

As shown in FIG. 1, the quasi-stationary units 1 and 4 can consist of two physically separate units, so that the installation location of the quasi-stationary unit 4 can be determined separately from the quasi-stationary unit 1, depending on the application and vehicle body requirements. The antenna 12 may be located for example near the centra ^¬ len-board electronics of the vehicle or in the region of the dashboard. In such a case, the antenna 13 could, for example, be mounted in such a way that the mobile unit 6 can already be supplied with energy outside the vehicle at low field strength in an emergency case, for example to ensure the Turoffnungsfunktion. As a location for the antenna 13, for example, a location on the outer body of the vehicle from where the low-frequency transmission of energy to the mobile unit 6 is less attenuated than would be the case with a transmitting antenna arranged in the vehicle interior. Mobile units known Schluselloser access systems can be converted with little effort to a mobile unit 6 for an inventive access system. As mentioned above, a mobile unit of a known keyless entry system usually already includes the components for high-frequency communication and the receiving stage for low-frequency signals in an emergency case. Since the control of such a mobile unit is often carried out by software, an adaptation in the simplest case can already take place by correspondingly modifying the software and adding at least the energy store 11 (for example a capacitor) and thus represents a cost-effective and easy-to-implement solution ,

When implementing the quasi-stationary unit 4, it is also possible to resort to other components already present in or on the vehicle. If, for example, the vehicle is equipped with a PASE function, then the associated transmission stage for the low-frequency transmission of energy to the mobile unit 6 can be used. In this case, instead of the transmitting stage 5 and the transmitting antenna 13 according to FIG. 1, the corresponding components, namely the transmitting stage and the antenna of the PASE unit already present and interposed in the vehicle, are used for low-frequency energy transmission. These components are accordingly included in the operation and function of the schlussellosen ^¬ access system in accordance with Figure 1, whereby the number of required components, and in addition, the effort for integration be further reduced in the vehicle.

FIG. 2 shows in a block diagram a further exemplary embodiment, which is shown in FIG. 1 in that the transmission stage 5 for low-frequency signals 17 and the associated transmitting antenna 13 are in the quasi-stationary manner

Transmission unit 1 mitintegriert and not as shown in Figure 1 is housed in a separate quasi-stationary transmitting unit 4. This may result in further cost savings and reduction of the wiring and integration costs of the keyless entry system.

FIG. 3 shows a time diagram of the sequence of continuous low-frequency energy transmission and high-frequency communication between the quasi-stationary and mobile units in the exemplary embodiments according to FIGS. 1 and 2, which has been triggered by a specific event Startup of the engine or Betati ^¬ conditions of a door handle, in which initially no high-frequency communication between the mobile unit 6 and the quasi-stationary unit 1 takes place, so an emergency case is detected by the quasi-stationary unit 1.

The abscissa of the diagram according to FIG. 3 designates the time t, the ordinate schematically the activities in connection with a specific event 21, a determination of the emergency case 24, a low-frequency energy transmission 22 to the mobile unit 6 and a high-frequency, bidirectional communication 23 between the mobile Unit 6 and the quasi-stationary unit 1 in an access system according to Figures 1 and 2. The low-frequency power transmission 22 to the mobile unit 6 is activated after the event 21 has occurred and a determination of the emergency case 24 has been made.

After a certain period of time, which is, for example, between 100 ms and 2 s (eg at 500 ms), the energy storage 11 of the mobile unit 6 is sufficiently charged by the low-frequency energy transfer 22 to execute the desired high-frequency communication 23. The amount of time that is needed to adequately aufzula- an energy store in a mobile unit for the operation of the mobile unit to, depends among other things on the capacity of Energiespei ^¬ Chers, the field strength of the low frequency signal at the location of the antenna 15 and the efficiency of the antenna 15 and the receiving stage 9 from. The duration of such a high-frequency bidirectional communication 23 between the mobile unit 6 and the quasi-stationary unit 1 shown schematically in FIG. 3 is for example between 10 ms and 200 ms (eg at 50 ms). The short communication time represents a significant advantage over a known bidirectional low-frequency communication in the emergency case, since the same information content due to the higher transmission frequency and the associated higher data rate can be transmitted in a much shorter period.

The energy storage 11 of the mobile unit 6 must therefore provide significantly less energy for the operation of the mobile unit than would be the case with a corresponding low-frequency communication. It can therefore have a lower capacity and accordingly be charged faster and with less energy required. In addition, even in such an emergency case, as in an undisturbed operating state, continue all high-frequency information signals of units 1 and 6 are exchanged and are not limited to a never ^¬ derfrequente emergency communication. The original functional scope of the mobile unit thus remains completely preserved even in an emergency situation.

A further advantage results from the fact that the transmission stage 5 of the quasi-stationary unit for low-frequency signals 17 can be inexpensively designed as a pure transmission stage for energy transmission to the mobile unit 6, since no bidirectional low-frequency communication must take place even in an emergency case and no corresponding low-frequency reception stage and downstream Processing logic needed. In this case, energy is continuously transmitted to the mobile unit 6 in an emergency case as long as the energy store 11 is charged, as long as high-frequency communication takes place between the mobile unit 6 and the quasi-stationary unit 1. Is such a high-frequency communica- tion no longer necessary, can set the quasi-stationary Sendestu ^¬ fe 5 optionally also the transmission of low-frequency signal in order to save energy.

Another situation in which the quasi-stationary transmission stage 5 can stop transmitting the low-frequency signal in order to save energy is the case in which no high-frequency communication takes place despite the occurrence of a specific event and determination of the emergency case, since in this case the mobile Unit 6 is obviously so far away from the quasi-stationary transmission stage 5 that sufficient charging of the energy store is not possible and / or no high-frequency communication between mobile unit 6 and quasi-stationary unit 1 can take place.

This may be the case, for example, if the specific event is the actuation of a door handle of the vehicle, without the mobile unit 6 actually being in sufficient proximity to the vehicle or to the transmission antenna 13 of the quasi-stationary transmission stage 5. In this case, for security reasons, no further action should be taken in response to the particular event.

Figure 4 is a diagram showing the the drawn by a particular sequence of events of a non-continuous low energy transfer and the high-frequency Kom ^¬ communication between the quasi-steady and the mobile units according to the figures 1 and 2. The basic structure of the chart corresponds to that shown in FIG. 3 From FIG. 4, however, it can be seen that, in contrast to the diagram shown in FIG. 3, the low-frequency energy transmission 22 is terminated after a certain period of time (again, for example, about 500 ms), assuming that the energy store 11 of the mobile unit is assumed 6 is sufficiently charged to perform the desired high-frequency communication 23. Instead of a draw by a certain Event can also occur in the same way a cyclic firing without occurrence of a specific event.

The duration of this high-frequency bidirectional communication 23 between the mobile unit 6 and the quasi-stationary unit 1 again amounts to about 50 ms, for example. If the reaction to a specific event, for example the actuation of a door handle or the actuation of a start button for the engine start, is processed by the high-frequency communication carried out in this way, no further low-frequency signals are initially emitted by the quasi-stationary transmission stage 5. Only when a certain event occurs again and when the emergency operation is detected again is a corresponding low-frequency signal sent to the mobile unit 6 again. Compared to an exemplary embodiment according to FIG. 3 with a low-frequency signal 17 transmitted further for at least a certain period of time, the energy required in the overall system can be further reduced as a result.

In an interim replacement of the spent or failed energy source 10 in the mobile unit 6 no more emergency case is determined by the keyless entry system (high-frequency communication is instantaneous, see above), and in this case, the quasi-stationary transmission stage 5 for low-frequency signals for energy transmission is not activated becomes.

In addition to the illustrated and illustrated exemplary embodiments, there are a variety of other configurations, such as the installation of one of the quasi-stationary antennas, in the start-stop button of the vehicle or in the door handle, specially designed coils as antennas or the use of micro-controllers in the individual Emheite. Reference sign

1 quasi-stationary unit

2 transmission levels

3 reception level

4 activatable and deactivatable quasi-stationary unit

5 transmission levels

6 mobile unit

7 transmission levels

8 reception level

9 reception level

10 energy source

11 energy providers

12 antenna

13 antenna

14 antenna

15 antenna

16 high-frequency signals

17 low-frequency signals

21 event

22 energy transfer

23 high-frequency communication

24 emergency case

Claims

claims

1. A keyless entry system for a vehicle having a quasi-stationary unit (1) mounted in or on the vehicle, having a transmitting (2) and receiving stage (3) for high-frequency signals (16), m or attached to the vehicle quasistationa- ren transmission stage (5) for low frequency signals (17) and a mobile unit (6) comprising a transmission (7) and reception stage (8) for high-frequency signals (16), a reception ^¬ stage (9) for Low-frequency signals (17) and for own power supply an energy source (10) and an energy storage (11), wherein the mobile and the quasi-stationary unit (1, 6) wirelessly on the basis of the high-frequency signals (16) exchange information and in an emergency case if in the mobile unit (6) the energy source (10) does not sufficiently supply energy to the transmitting and receiving stage (7, 8) for high-frequency signals (16), the quasi-stationary transmitting stage (5) reaches the receiving stage (9) for low frequency sign ale (17) in the mobile unit (6) transmits, on the basis of the low-frequency signals (17), energy stored in the energy store (11) of the mobile unit and the transmitting and receiving stage (7, 8) for high-frequency signals (16) in the mobile unit (6) supplied.

2. Access system according to claim 1, wherein the energy store (11) of the mobile unit (6) is a capacitor.

3. Access system according to claim 1 or 2, wherein the power source (10) of the mobile unit is a battery.

4. Access system according to one of the preceding claims, wherein the quasi-stationary unit (1) is designed to control a Weg ^¬ vehicle locking of the vehicle and only then generates a signal for deactivating the immobilizer when the mobile unit (6) is less than 10cm from a certain point on the vehicle.

5. Access system according to claim 4, wherein the distance between see the certain point on the vehicle and the mobile unit (6) is determined by a field strength measurement.

6. Access system according to claim 5, wherein for the field strength measurement of the transmission stage (2) for high-frequency signals (16) in the quasi-stationary unit (1) or the quasi-stationary transmission stage (5) for low-frequency signals (17) generated by the field strength mobile unit (6) is evaluated and the value of the field strength is sent to the quasi-stationary unit (1).

7. Access system according to one of claims 4 to 6, wherein the certain points the transmission stage (2) for high-frequency signals (16) in the quasi-stationary unit (1) and the qua ^¬ sistationare transmission stage (5) for low-frequency signals (17) Antenna (12, 13), one of which represents the particular point on the vehicle.

8. Access system according to claim 7, in which the antenna (13) of the quasi-stationary transmission stage (5) for low-frequency signals (17) represents the specific point on the vehicle and the mobile unit (6) evaluates the field strength of the low-frequency signals.

9. Access system according to one of the preceding claims, wherein the quasi-stationary transmission stage (5) for low-frequency

Signals (17) comprises an antenna (13) for passive start-and-entry (PASE) applications.

10. Access system according to one of the preceding claims, wherein the high-frequency signals (16) has a frequency of large 200th

Kilo-Hertz and the low-frequency signals (17) have a frequency less than 200 kilohertz.

11. Access system according to one of the preceding claims, in which the low-frequency signals (17) predominantly comprise a magnetic component.

12. Access system according to one of the preceding claims, in which the quasi-stationary transmission stage (5) for low-frequency signals (17) is integrated in the quasi-stationary unit (1) for high-frequency signals (16).

13. Access system according to one of the preceding claims, in which the quasi-stationary transmission stage (5) for low-frequency signals (17) can be activated and deactivated and is only activated when a specific event occurs.

14. Access system according to claim 13, wherein the quasi-stationary transmission stage (5) for low-frequency signals (17) is activated upon actuation of a door handle or the start button of the vehicle.

15. Access system according to claim 13 or 14, wherein the quasi-stationary transmission stage (5) for low-frequency signals (17) is activated after the occurrence of the specific event for a predetermined period of time and then deactivated again.

16. Access system according to one of claims 13, 14 or 15, in which the quasi-stationary transmission stage (5) for low-frequency signals (17) is activated only when a failure of the energy source (10) is detected in the mobile unit.

17. Access system according to claim 16, wherein a failure of the

Power source (10) in the mobile unit (6) is assumed when a high-frequency signal (16) of the quasi-stationary unit (1) no high-frequency signal (16) in response to the mobile unit (6) is sent.