Abstract:
The invention relates to a structural theft protection system for motor vehicles with a blocking control device ( 30 ) for releasing a motor control device ( 31 ), a code acquisition device ( 20, 21 ) that is connected to the blocking control device, and a device ( 32 ) connected to the blocking control device ( 30 ) for acquiring a vehicle use parameter (T, S), as well as with several locally fixed code takeover/output stations ( 10, 11 ), wherein the blocking control device ( 30 ) keeps the motor control device ( 31 ) in the release position only if the blocking control device ( 30 ) is fed a new release information by one of the locally fixed code takeover/output stations ( 10, 11 ), preferably at regular intervals.

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a theft protection device for motor vehicles. In order to counter a rising number of motor vehicle thefts, stop-drive devices are used increasingly especially in new vehicles. The operation of said devices is based on releasing the functions of at least one motor control device that is essential for the vehicle operation only if a code that is entered from the outside into the stop-drive device coincides with a code previously stored inside the stop-drive device. Devices of this type ensure a high degree of safety against attempted thefts, provided the secured vehicle is parked and the potential thief is not in possession of the regular means for starting. However, there has been a tendency in recent times to steal vehicles not through irregular starting, but through so-called “car-jacking.” In that case, a thief forces the vehicle user to hand over the regular starting means and then has unlimited access to the vehicle. A device for safeguarding a vehicle, which at least makes car-jacking more difficult, is known from the U.S. Pat. No. 4,302,747. A vehicle secured in accordance with the suggestion in this reference is shut down following a predetermined time interval that begins with the starting of the engine, provided a hidden switch to prevent this is not activated. However, even this known device loses its protective effect, in particular for a car-jacking, if a thief proceeds on the assumption that such a switch exists—which will usually be the case when such protective devices are more widely used—and orders the user to provide a complete explanation of all safety devices. A safety device using the option of wireless communication between a vehicle and a locally fixed monitoring station is known from the DE-OS 42 43 482. In this case, a check is made with the aid of signals exchanged between a locally fixed monitoring station and the secured vehicle to determine whether an authorization-check communication occurs as required within the vehicle between a transmitting device on the vehicle and a transmitting device integrated into the ignition key that is handled by the user. If an error occurs in the authorization-check communication, in particular if it does not occur at all because the vehicle was short-circuited, then this is detected in the locally fixed monitoring station. The stolen vehicle can be located with the aid of identification data transmitted to the monitoring station without the knowledge of the illegal user. This arrangement as well is useless in cases where the thief has taken possession of the regular starting means, in this case the ignition key. 
     SUMMARY OF THE INVENTION 
     It is the object of the invention to provide a safety device for vehicles, which prevents the illegal takeover of a vehicle even in cases where a potential thief has taken possession of the standard starting means. 
     Vehicles equipped according to the invention require the regular renewal of the release for operation by feeding in a release information, generated by locally fixed code takeover/output stations. By blocking the output of this release information, the further operation of a vehicle can be prevented easily. The release information functions like a necessary operating means, which is no longer supplied in case of an illegal start-up. This makes the theft of a vehicle unappealing, even if the thief is in possession of the correct starting means and has knowledge of the design of the safety device. 
     In an advantageous embodiment, the release information that is necessary for further operation is supplied with the aid of a chip card of the type like a credit or telephone card. Code acquisition devices on the vehicle or locally fixed code takeover/output stations are correspondingly designed as card reading or card reading/recording devices. It is particularly advantageous if the locally fixed card reading/recording stations are erected at gasoline stations. The release information on the chip card is renewed each time during the fueling. 
     Another advantageous embodiment provides that the code acquisition device on the vehicle is designed as a receiving device for the radio signals and the locally fixed code takeover/output device as a radio signal transmitter/receiver. The regular renewal of the release information occurs via wireless in this case. For a sensible modification of this embodiment, the code acquisition device is also suited for emitting signals, by means of which it requests the release information in each case. 
     In a simple way, the operating time or the distance are applied as a vehicle use parameter for determining the driving range that is respectively valid following the input of a release information. 
     In accordance with another advantageous embodiment, the respective vehicle position is acquired as a vehicle use parameter, and the acquired position is compared to a driving range that was previously defined as release information. 
     If the release information does not arrive, it is further advisable to shut down the vehicle gradually upon leaving the driving range, for example by initially limiting the maximum speed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a safety device that operates with a chip card; 
     FIG. 2 shows a safety device that operates by means of radio signals; 
     FIG. 3 shows a flow diagram of a first operational mode; 
     FIG. 4 a flow diagram of a second operational mode; 
     FIG. 5 a realization of the blocking function. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiment shown in FIG. 1 is based on the use of a recordable magnetic or chip card  40 . It has a card reader  20  on the vehicle side to read the chip card  40 . This can be either a card reader already existing in the vehicle, as is increasingly used to secure auto radios, or a separate device. A blocking control device  30  is connected to the card reader  20  via an advisably serial transmission path. Via a connection  23 , it controls the release or blocking of a downstream motor control device  31 . The motor control device  31  can be any optional control device in a vehicle, which if blocked prevents a continued operation or renewed start of the vehicle. Also, several control devices can be connected simultaneously via this connection  23  to the blocking control device  30 . A legitimizing device  33  can additionally be provided to ensure that the card reader  20  and the blocking control device  30  belong together, for example a type of keyboard as indicated in FIG.  1 . Via this keyboard, a user assigns an authorization code to the card reader  20 , which is fed to the blocking control device  30  and is checked there. Of course, the legitimizing device  33  can be realized in any optional form in place of a keyboard, such as for example in the form of an infrared sensor. Also, the legitimizing device  33  can act directly upon the blocking control device  30  instead of the card reader  20 . Also connected to the blocking control device  30  is a device  32  for detecting or acquiring a vehicle use parameter. Detected parameters are preferably the traveled distance, the operating time and/or the vehicle position. Other components of the safety device are furthermore several locally-fixed card/reading/recording stations  10  that do not belong to the secured vehicle, which can read the code card  40  as well as record new information on it. It is preferable, if the card reading/recording stations  10  are located at gasoline stations. It is also advisable if the vehicle owner has a separate card reading/recording station  10 , which can access only the cards associated with a specific vehicle. The standard magnetic or chip cards in credit-card format are used as code cards  40 . They have an additional area for recording. It is useful if the code card  40  simultaneously functions as a gasoline credit card. 
     By taking reference to FIG. 2, the operation of the arrangement shown in FIG. 1 is described in the following. In order to start the vehicle, an initialization is required first, the step  100 . For this, the user inserts the code card  40  into the card reader  20 . At the same time, the user legitimizes him-/herself by entering a code via the keyboard  33 . If the blocking control device  30  accepts the code entered via the keyboard  33  as being valid, then the card reader  20  reads the information supplied by the code card  40  and transmits it to the blocking control device  30 . This device subsequently checks if a valid old release information is present, step  101 . It is always present if the detected vehicle use parameter has not exceeded a maximum value and can, for example, be realized in the form of data for the still allowable residual vehicle operation time. The old release information is stored in the vehicle, in a memory designed for this, but can also be fed in each time via the code card  40 . 
     If no valid old release information exists, then the blocking control device  30  subsequently checks whether a new release information exists on the code card  40 , step  102 . If this is the case, then it generates an old release information and records this in the memory existing for this or alternatively on the code card  40 , thereby deleting the new release information from the code card  40 . Furthermore, in step  103 , it resets the values detected for the vehicle use parameters to their predetermined starting values. For example, if the traveled distance is used as a vehicle use parameter, then it will be reset to the value zero. Following that, the blocking control device  30  starts the acquisition of the vehicle use parameter; step  104 . 
     If as a result of the check in step  101  it turns out that a valid old release information exists in the blocking control device  30 , then step  104  follows directly after step  102 . In that case, the vehicle use parameters are not reset. 
     In the subsequent step  105 , the blocking control device  30  checks whether a predetermined maximum value was exceeded for the detected vehicle use parameter, for example the distance traveled since the point of access to the last new release information and/or the operating time accrued since then. 
     The maximum value is advisably matched to the technical design of the respective vehicle. It makes sense if the maximum value for the traveled distance is, for example, selected such that it is slightly higher than that for the distance a vehicle can travel under favorable conditions with one tank filling. In a similar way, the maximum value for the operating time usefully corresponds to the idle operating life resulting from a full tank. Alternatively to the fixed, predetermined value, variable maximum values can also be provided and can be fed via the code card  40  to the blocking control device  30 , respectively together with the release information. In this way, the length of use can be limited to an agreed-upon value, for example for rental vehicles. 
     As long as the maximum value has not been reached, the acquisition of the vehicle use parameter is continued, step  104 . Following each completion of a cycle interval, which can last from 1 to 60 seconds for example, the interrogation according to step  105  is repeated and subsequently step  104  if necessary. 
     If the check during step  105  shows that the maximum vehicle use parameter value has been reached, then the blocking control device  30  deletes the existing old release information and subsequently checks during step  102  whether a new release information from code card  40  is present. If this is the case, then the steps  103  are subsequently repeated in the following. If a new release information is not present during the step  102 , then the blocking control device  30  limits the use of the vehicle during the step  106 . For this, it reduces the maximum possible rotational speed of the motor, for example, or limits the top speed. It is advisable if the limited operation is signaled to the user acoustically or optically, for example through blinking or an error lamp. The blocking control device  30  checks in the following step  108  whether a predetermined overtime has passed since the lack of a valid old release information was detected during step  102 . If this is not yet the case, then it repeats step  102  and checks again whether a new release information has arrived. If the check during step  108  finally shows that the predetermined overtime has passed, then the blocking control device  30  blocks the motor control device  31  during the step  110 . 
     FIG. 3 shows a second embodiment of the suggested safety device. In place of a card reader  20 , a transmitting/receiving device  21  is provided on the vehicle side for this arrangement. It is preferable if the transmitting/receiving device  21  comprises a transmitting/receiving antenna attuned to an existing radio network. The other elements of the device on the vehicle side correspond to those already described with the aid of the device in FIG.  1 . For this embodiment, a transmitting/receiving station  11  serves as locally fixed element for emitting radio signals. It is useful if the transmitting/receiving stations  11  are stationary transmitting/receiving devices of an existing movable radio network  21 . 
     The operation of the second embodiment corresponds for the most part to the device according to FIG.  1  and can also be described with the aid of FIG.  2 . After initiating the start of operations, the blocking control device  30  first checks whether a valid old release information exists, step  101 . If this is the case, then the acquisition of the vehicle use parameters during step  104  follows immediately. 
     If this is not the case, then the blocking control device  30  requests a new release information via the transmitting/receiving device  21  and the radio network  41  of a transmitting/receiving station. This is followed by a check during step  102  on whether a new release information has arrived. If this is the case, an old release information is generated in step  103  and the values for the acquired vehicle use parameters are reset to their initial values. It is advisable if the acquired parameters are the traveled distance and/or the operating time since the arrival of the last preceding new release information, the same as for the device in FIG.  1 . This is again followed by the acquisition of the vehicle use parameters during the step  104 , as well as the check on whether the acquired parameters exceed predetermined maximum values, step  105 . The predetermined maximum values here are adapted to the frequency, used to supply new release information to the transmitting/receiving device  21  via the radio network  41 . It can assume an optional value between several seconds and several hours. If the result of the check in step  105  is negative, then step  104  is repeated once more. If the result of the check in step  105  is positive, meaning if the acquired vehicle use parameter has reached the predetermined limit value, then the blocking control device  30  repeats the step  102  and checks whether a new release information has arrived. It is conceivable that the blocking control device  30  requests a new release information only if the acquired vehicle use parameter value reaches the maximum value. In that case, the check in step  102  is preceded by a request (not shown) for a new release signal. If the check in step  102  shows that a new release information is not present, the blocking control device  30  reduces the vehicle use in step  106 . This is followed by a check on whether a predetermined overtime has passed, during which a limited use of the vehicle is still possible despite the lack of a release information, step  108 . If this is not yet the case, then it is checked again—step  102 —whether a new release information has arrived. If the check in step  106  reveals that the overtime has passed, then the blocking control device  30  blocks the motor control device  31  and thus stops the vehicle, step  110 . 
     FIG. 4 demonstrates another option of operating the device according to FIG.  3 . For this operational mode, information is transmitted in place of the release information via the radio network  41 , which permits the blocking control device  30  to determine the actual vehicle position, step  120 . The respectively determined position is subsequently analyzed by the blocking control device  30  as to whether it is located within a predetermined driving range, step  122 . 
     The driving range is determined before the vehicle starts operating and is stored in a memory in the blocking control device. The driving range is defined outside of the vehicle, for example with the aid of a home computer or a special programming device. A code card system with code card  40  and card reader  20 , analogous to the arrangement in FIG. 1, is again useful for transferring the data determining the driving range to the blocking control device  30 . 
     The programming station used for this is clearly assigned to the vehicle by a code determined by the vehicle manufacturer. A programming can take place only if the vehicle code and a code determined by the user match. 
     If the check during step  122  shows that the detected position is within the predetermined driving range, then the position determination according to step  120  is repeated following the completion of a suitable time interval, which can optionally be between several seconds and several hours. If the check in step  122  shows that the detected position is located outside of the predetermined driving range, then the blocking control device  30  reduces the use of the vehicle during the step  124 . This can be achieved, for example, again by limiting the rotational speed of the engine or the maximum speed. In the following, the blocking control device  30  checks in step  126  whether the detected vehicle use parameter has reached a predetermined maximum value. In this case, the maximum value gives the user the option of returning the vehicle to the predetermined driving range after it has accidentally left the permissible driving range; it is determined accordingly. If the maximum value for the vehicle use parameters has not been reached, then step  120  is repeated. If the check in step  126  shows that the detected vehicle use parameter has reached the maximum value, then the blocking control device  30  again blocks the motor control device  31 , step  128 . 
     FIG. 5 provides a detailed illustration of the elements of the device that realize the blocking function. The blocking control unit  30  is here realized as a component of the motor control device  31 . The transmission path from the card reading or transmitting/receiving module that is not shown in FIG. 5, is conducted to a receiver  50 . From it, a reset output  60  leads to a first integration element  51  for acquiring the traveled distance and a second integration element  52  for acquiring the operating time. Two other outputs  61 ,  62  for presetting a maximum operating time t MAX  or maximum distance S MAX  respectively lead to a threshold value controller  55 ,  56 . Integration element  51  and threshold value controller  56  are connected to a performance characteristic controller  54  via a joint output  63 . The integration element  52  and the threshold value controller  55  are connected in the same way via a joint output  64  with the performance characteristic controller  54 . Via outputs  65 ,  66 , the threshold value controllers  55  or  56  are connected to an OR element  57 . Its output controls a circuit  58  that permits separating a connection  67  between performance characteristic controller  54  and a downstream rotational speed limiter  59 . Furthermore, a time counter  53  for detecting the operating time is connected via an input  68  to the integration element  52 . The pulses of a tacho-transmitter  32  are fed in a similar way to the second integration element  51  via an input  69 . 
     The device shown in FIG. 5 functions as follows: If a user has legitimized him-/herself by entering a correct code, for example via a keyboard  33 , then the release information supplied to the card reader  20  or the transmitting/receiving module  21  is fed via the serial transmission path  22  to the receiver  50 . This receiver resets the information elements  51 ,  52  to their starting values. Furthermore, it transmits the previously programmed limit values for the operating time T or the distance S to the threshold controllers  55 ,  56 . While the vehicle is in operation, the integrating elements  51 ,  52  continuously add the information supplied by the time counter  53  or the tacho transmitter  32  with respect to the operating time T or the traveled distance S. The determined values for the operating time T or the traveled distance S are supplied to the performance characteristic controller  54 , which assigns them a maximum rotational motor speed N MAX  and transmits it to the rotational speed limiter  59 . The circuit  58  here is initially closed. At the same time, the vehicle use parameters T, S that are detected by the integration elements  51 ,  52 , are fed to the threshold value controllers  55 ,  56 . This controller assigns them the logical values zero to 1, in accordance with a non-linear control function. In this case, the value logic zero is assigned as long as the respective vehicle use parameter has not yet reached the limit value t MAX  or S MAX  preset by the receiver  50 . If the detected vehicle use parameters t, S exceed the preset limit values T MAX , S MAX , then the values logic ONE are assigned to them the more they exceed. At the same time, the performance characteristic controller  54  assigns increasingly smaller maximum motor speeds N MAX  to the vehicle use parameters T, S that exceed the preset maximum values T MAX , S MAX  and transmits these to the rotational speed limiter  59 . As long as the inputs  65  and  66  at the OR element  57  together do not result in the logic value ONE, it is possible to operate the vehicle at a reduced maximum speed N MAX . However, the circuit  58  is activated as soon as the sum of the inputs  65  and  66  at the OR element  57  results in the value ONE. The rotational speed limiter  59  is then supplied a desired rotational speed determined by the performance characteristic controller  54 . This speed decreases the more the maximum values T MAX , S MAX  are exceeded, until finally the value zero is reached, whereupon the vehicle is stopped. If a new release information arrives at the receiver  50  while the integration elements  51 ,  52  add the traveled distance S or the operating time t, then the integration elements  51 ,  52  are reset. A continuous operation of the device according to FIG. 5 is therefore possible if a new release information arrives regularly, before the detected vehicle performance parameters T, S reach the preset maximum values S MAX , T MAX . 
     By holding on to the underlying idea, a plurality of embodiments of the invention is possible. This is true for the structural design of the safety devices used, as well as in particular for the operating modes of the device.