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CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a continuation of co-pending International Application No. PCT/EP2004/003717 filed Apr. 7, 2004 which designates the United States of America, and claims priority to German Application No. 103 22 853.5 filed May 21, 2003, the contents of which are hereby incorporated by reference in their entirety. 

   TECHNICAL FIELD 
   The invention concerns a key system for a vehicle with transmitting electronics arranged in housing for contactless locking and/or unlocking of a door of a vehicle and/or operation of a vehicle, and with an emergency key for mechanical locking and/or unlocking of the door of the vehicle and/or for operation of the vehicle. 
   BACKGROUND 
   The task of the invention is to improve such a key system. 
   The aforementioned task is solved by a key system for a vehicle with transmitting electronics arranged in a housing for contactless locking and/or unlocking of a door of a vehicle and/or for operation of a vehicle, as well as an emergency key for mechanical locking and/or unlocking of the door of the vehicle and/or operation of the vehicle, in which the emergency key can be accommodated (essentially) fully in the housing (and advantageously locked into this position). 
   A vehicle according to the invention is especially a ground vehicle, usable individually in traffic. The vehicles according to the invention are not particularly restricted to ground vehicles with an internal combustion engine. A door (of a vehicle) according to the invention can be a door, front or rear hatch or trunk. An emergency key designed for mechanical operation of the vehicle according to the invention corresponds, in particular, to a mechanical ignition key. 
   For essentially full accommodation of the emergency key in the housing of the key system, the emergency key, in an advantageous embodiment of the invention, can be accommodated essentially fully in one edge of the housing. 
   In another advantageous embodiment of the invention, the emergency key and the housing are fully separable from each other. That the emergency key and the housing are fully separable from each other according to the invention means especially that the emergency key and the housing can be fully separated from each other without destruction and without a tool. This means, in particular, that the emergency key and the housing can be fully separated from each other for use of the emergency key without difficulty. 
   In another advantageous embodiment of the invention, the emergency key is designed to be mounted on a key ring. 
   In another advantageous embodiment of the invention, the emergency key has a closure element for mechanical locking and/or unlocking of the door of the vehicle and/or for operation of the vehicle and a receiving element appropriate to receive a key ring. The closing element and the receiving element in another advantageous embodiment of the invention are then movably connected to each other, advantageously by means of a link, especially by means of a hinge. 
   In another advantageous embodiment of the invention, the closure element or emergency key has a closure piece for mechanical locking and/or unlocking of the door of the vehicle and/or for operation of the vehicle and an insertion element, into which the closure piece can be inserted. 
   In another advantageous embodiment of the invention, the emergency key, has a receiving element appropriate to receive a key ring. 
   In another advantageous embodiment of the invention, the insertion element and the receiving element are movably connected to each other, advantageously by means of a link, especially a hinge. 
   In another advantageous embodiment of the invention, the emergency key can be locked in a first locking position and in a second locking position different from the first locking position in the housing. 
   The emergency key, in another advantageous embodiment of the invention in the first locking position, is essentially fully in the housing and advantageously in the second locking position (especially only in this position), is accommodated in the housing to the extent that the receiving element for a key ring (for the purpose of threading) can be reached. 
   In another advantageous embodiment of the invention, the emergency key in the second locking position (especially only in this position) is accommodated in the housing to the extent that the receiving element can be pivoted. 
   In another advantageous embodiment of the invention, the emergency key in the second locking position (especially only in this position) is accommodated in the housing, so that (only) the closure element is essentially accommodated in the housing. 
   In another advantageous embodiment of the invention, the emergency key can be pushed into the housing when the second locking position is released. 
   In another advantageous embodiment of the invention, the emergency key is separable from the housing, when released in the second locking position. 
   In another advantageous embodiment of the invention, the key system has a pushbutton to release the second locking position. 
   It can be prescribed that the housing have a receiving element appropriate to accommodate a key ring. The receiving element can be connected movably to the housing and, at least in one closure position, in which the receiving element forms a closed unit with the housing, and can be arranged in a threading position, in which a key ring can be threaded onto the receiving element. 
   The aforementioned task is additionally solved by a key system for a vehicle with transmitting electronics arranged in the housing for contactless locking and/or unlocking of a door of the vehicle and/or for operation of the vehicle, in which the housing has a receiving element suitable for receiving a key ring, which is movably connected to the housing and can be arranged, at least one closure position, in which the receiving element forms a closed unit with the housing, and in a threading position, in which a key ring can be threaded onto the receiving element. 
   In advantageous embodiment of the invention, the key system has an emergency key for mechanical locking and/or unlocking of the door of the vehicle and/or operation of the vehicle, in which the emergency key can be accommodated, at least partially, preferably essentially fully, in the housing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Additional advantages and details are apparent from the following description of practical examples. In them: 
       FIG. 1  shows a practical example of a key system in a first locking position. 
       FIG. 2  shows the practical example of the key system according to  FIG. 1  in a second locking position. 
       FIG. 3  shows the practical example of the key system according to  FIG. 1  with an emergency key separated from the housing. 
       FIG. 4  shows the practical example of the key system according to  FIG. 1  in a first locking position in a three-dimensional view. 
       FIG. 5  shows the practical example of the key system according to  FIG. 1  in a second locking position in a three-dimensional view. 
       FIG. 6  shows the practical example of the key system according to  FIG. 1  in a second locking position in a three-dimensional view. 
       FIG. 7  shows a practical example of an emergency key. 
       FIG. 8  shows another practical example of a key system. 
       FIG. 9  shows a practical example of the key system according to  FIG. 8  with a key ring. 
       FIG. 10  shows the practical example of a key system according to  FIG. 8  in a three-dimensional view. 
       FIG. 11  shows the practical example of a key system according to  FIG. 9  in a three-dimensional view. 
       FIG. 12  shows another practical example of a key system. 
       FIG. 13  shows the practical example of the key system according to  FIG. 12  in an opened state. 
       FIG. 14  shows the practical example of the key system according to  FIG. 12  with a threaded key ring. 
       FIG. 15  shows the practical example of the key system according to  FIG. 12  in a three-dimensional view. 
       FIG. 16  shows the practical example of the key system according to  FIG. 13  in a three-dimensional view. 
       FIG. 17  shows the practical example of the key system according to  FIG. 14  in a three-dimensional view. 
       FIG. 18  shows another practical example of the key system in a three-dimensional view. 
       FIG. 19  shows the practical example of the key system according to  FIG. 18  in an open state. 
       FIG. 20  shows the practical example of the key system according to  FIG. 18  in a closed state with a threaded key ring. 
       FIG. 21  shows another practical example of the key system. 
       FIG. 22  shows the practical example of the key system according to  FIG. 21  in an opened state in a three-dimensional view. 
       FIG. 23  shows the practical example of the key system according to  FIG. 21  in an opened state. 
       FIG. 24  shows the practical example of the key system according to  FIG. 21  in a closed state with a threaded key ring. 
       FIG. 25  shows the practical example of the key system according to  FIG. 21  in a half-opened state. 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows a practical example for a key system  1  situated in a first locking position for a vehicle, with transmitting electronics arranged in a housing  2  for contactless locking and/or unlocking of the door of a vehicle and/or for operation of the vehicle, and with an emergency key  3  for mechanical locking and/or unlocking of the door of the vehicle and/or operation of the vehicle. The emergency key  3  is fully accommodated in the upper edge  4  of housing  2 . The emergency key  3  has an opening  5 , into which, as shown in  FIG. 5  and  FIG. 6 , a key ring  10  can be threaded. 
   The emergency key  3 , as shown in  FIG. 2 , can be partly pushed out from housing  2  into a second locking position. In this second locking position, the opening  5 , as shown in  FIG. 5  and  FIG. 6 , a key ring  10  can be threaded. In addition, the emergency key in the second locking position releases a pushbutton  6 . By pressing pushbutton  6 , a locking mechanism in the housing  2  is released, so that housing  2  and the emergency key are separable and can form two separate objects, as shown in  FIG. 3 . 
     FIG. 4 ,  FIG. 5 , and  FIG. 6  show the key system  1  in a three-dimensional view. The key system  1  in  FIG. 4  is shown in its first locking position. Arrow  7  shows that the emergency key  3  can be pushed (partially) from housing  2  into a second locking position.  FIG. 5  and  FIG. 6  show the key system in its second locking position, in which a key ring  10  is threaded through opening  5 . 
     FIG. 7  shows the emergency key  3  in a three-dimensional view. The emergency key  3  has a closing element  20  with a closing piece  22  for mechanical locking and/or unlocking of the door of the vehicle and/or for operation of the vehicle and with an insertion element  23 , into which the closure element  22 , as indicated by the double arrow  25 , can be pushed in and out. The insertion element  23  is connected to tilt via a hinge  24  to a receiving element  21 . In this way, the hazard of injury during an accident can be reduced. The receiving element  21  in  FIG. 6  of the emergency key pushed into the second locking position in the housing  2  is tilted back. An opening  5  is arranged in the receiving element  21 . 
     FIG. 8  shows another practical example of a key system  30  for a vehicle,  FIG. 9  shows the practical example of the key system  30  according to  FIG. 8  with a key ring  33 ,  FIG. 10  shows the practical example of the key system  30  according to  FIG. 8  in a three dimensional view and  FIG. 11  shows the practical example of the key system  30  according to  FIG. 9  in a three-dimensional view. The key system  30  has transmitting electronics arranged in a housing  31  for contactless locking and/or unlocking of the door of the vehicle and/or for operation of the vehicle, as well as a loop-like receiving element  32 , appropriate to accommodate a key ring  33 , which is connected movably to housing  31 . 
   In the position depicted in  FIG. 8  and  FIG. 10 , the loop-like receiving element  32  is flush with the surface of housing  31 , so that it does not protrude beyond the basic outline of housing  31 . The loop-like receiving element  32 , as shown in  FIG. 9  and  FIG. 11 , can be tilted back, so that the key ring  33  can be threaded into the receiving element. 
   Another practical example of a key system  40  is shown in  FIG. 12 ,  FIG. 13  shows the practical example of the key system  40  according to  FIG. 12  in an opened state,  FIG. 14  shows the practical example of the key system  40  according to  FIG. 12  with a threaded key ring  45 ,  FIG. 15  shows the practical system of the key system  40  according to  FIG. 12  in a three-dimensional view,  FIG. 16  shows the practical example of the key system  40  according to  FIG. 3  in a three-dimensional view, but without the key ring  45 , for reasons of clarity, and  FIG. 17  shows the practical example of the key system  40  according to  FIG. 14  in a three-dimensional view. The key system  40  has transmitting electronics arranged in a housing  41  for contactless locking and/or unlocking of a door of the vehicle and/or for operation of the vehicle, as well as receiving element  42 , suitable for receiving key ring  45 , which is movably connected to housing  41 . 
   In the position depicted in  FIG. 12  and  FIG. 15 , the receiving element  42  covers a face of housing  41  flush. The housing has a pushbutton  43 . If the pushbutton  43  is pressed, the receiving element  42  is moved in the direction of arrow  44  into a position depicted in  FIG. 13  and  FIG. 16 . The receiving element  42  has a long retaining pin  48 , which, in the position depicted in  FIG. 13  and  FIG. 16 , connects the receiving element  42  to housing  41 , and a short retaining pin  49 . In this position, the key ring  45 , as shown in  FIG. 13 , can be threaded between housing  41  and the short retaining pin  49 . 
   After threading of key ring  45 , the receiving element  42  can be moved in the direction of arrow  46  on housing  41 , so that both the long retaining pin  48  and the short retaining pin  49  connect the receiving element  42  to housing  41  and the key ring  45  is enclosed. 
     FIG. 18  shows another practical example of a key system  50  in a three-dimensional view. The key system  50  has transmitting electronics arranged in a housing for contactless locking and/or unlocking of the door of a vehicle and/or for operation of the vehicle, as well as a receiving element  52 , suitable for accommodating a key ring  56  with an opening  54 . The receiving element  52  is connected by means of a pin  53  to housing  51 , pivotable in the direction of arrow  57 . 
     FIG. 19  shows the key system  50  in an opened state, i.e., after pivoting of he receiving element  52 . In this state, the key ring  56  can be threaded into opening  54 . After threading of the key ring  56 , the receiving element  52  can be pivoted back, in which case a recess  55  is provided for the key ring  56  on housing  51 .  FIG. 20  shows the key system  50  in this newly closed state with the threaded key ring  56 . 
     FIG. 21  shows another practical example of a key system  60 . The key system  60  has transmitting electronics arranged in a housing  61  for contactless locking and/or unlocking of a door of a vehicle and/or for operation of a vehicle, and a receiving element  62 , removable from housing  61 , suitable for accommodating a key ring  65 .  FIG. 22  shows the key system  60  in a three-dimensional view, in which the receiving element  62  is separated from housing  61 . The receiving element  62  has an opening  63 , through which the key ring  65  is threaded. 
   The housing  61  has a recess  64 , into which the receiving element  62  can be snapped when it is pushed, as shown in  FIG. 23 , in the direction of arrow  66 , onto housing  61 .  FIG. 24  shows the key system  60  in a closed state, i.e., after the receiving element  62  has been pushed onto housing  61 , with the threaded-on key ring  65 . 
     FIG. 25  shows the key system  60  in a half-opened state. By pushing the receiving element  62  relative to housing  61  in the direction of arrow  67 , the receiving element  62  can be separated from housing  61 . 
   The key systems  30 ,  40 ,  50  and  60  each have an emergency key (not shown) for mechanical locking and/or unlocking of the door of a vehicle and/or operation of a vehicle, in which the emergency key can be accommodated, at least partly and advantageously essentially fully, in housing  31 ,  41 ,  51  or  61 . 
   Especially in connection with the key systems  30 ,  40 ,  50  and  60 , it can be prescribed to design the housings  31 ,  41 ,  51  and  61  at least in two parts, i.e., from at least two parts, in which the two parts of housing  31 ,  41 ,  51  or  61  permit opening of housing  31 ,  41 ,  51  or  61  by tilting a part of the opening or are completely separable from each other. The fact that the two parts of housing  31 ,  41 ,  51  and  61  are fully separable from each other means, according to the invention, in particular, that the two parts of housing  31 ,  41 ,  51  and  61  can be separated from each other fully, free of destruction and without a tool. This means that the two parts of housing  31 ,  41 ,  51  and  61  are fully separable from each other for a user of the key without difficulty. If the housing  31 ,  41 ,  51  or  61  is opened, an emergency key can be removed.

Summary:
A key system ( 1 ) for a motor vehicle comprises transmitter electronics arranged inside a housing ( 2 ) and used for the contactless locking and/or unlocking of a door of the motor vehicle and/or operation of the motor vehicle. The system further comprises an emergency key ( 3 ) for mechanically locking and/or unlocking the door of the motor vehicle and/or for the operation of the motor vehicle. The emergency key is received inside the housing ( 2 ) in a substantially complete manner.