Abstract:
An ignition lock for a motor vehicle includes a locking cylinder, which in the presence of a suitable key can be shifted along a path including a punctual directional change between a driving position and a stationary position. In the driving position the ignition lock allows operation of an engine of the motor vehicle. In the stationary position operation of the engine is blocked. An indicating device is controlled by a switch operable by the locking cylinder at the point of directional change.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to German Patent Application No. 102016003981.7, filed Apr. 1, 2016, which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The present disclosure pertains to an ignition lock for a motor vehicle. 
       BACKGROUND 
       [0003]    For decades, the use of ignition locks in motor vehicles has been known, where a locking cylinder receives a suitable key and is rotatable about an axis between an inactive position, a driving position and an intermediate position. In the inactive position, the key can be withdrawn and the engine and all or nearly all electrical components of the vehicle are switched off. In the operating position, the engine and the electrical components are in operation. In the intermediate position, the electrical components are switched on, but the engine is switched off. 
         [0004]    In recent years doubts have arisen as to the safety of ignition lock systems, which permit a changeover from the driving position into the intermediate position, while the vehicle is moving. If such a changeover is triggered without the driver&#39;s interference, for example, due to the pendulum action of a bunch of keys in the ignition lock, the risk of an accident my be increased. 
         [0005]    Therefore, an ignition lock has been proposed, where operational safety is improved, in that a locking cylinder, in the presence of a suitable key, can be shifted along a path between a driving position, in which the ignition lock permits the operation of an engine of the motor vehicle, and a stationary position, in which the operation of the engine is blocked. The path includes a directional change. Even if accidentally and without any interference from the driver, there were forces impacting the key, which might be suitable to move the same along a first section of this path up to the point of the directional change, it would be very unlikely for the same accidental forces to cause the movement of the key also in the changed direction. 
         [0006]    There is, however, the problem that drivers of motor vehicles have always been used to bringing the key into the stationary position by continuously rotating it out of the driving position and then withdrawing the key. With a lock of the above-mentioned kind, however, such a rotation is blocked immediately at the point of the directional change. In this position, the engine is not switched off nor can the key be withdrawn, so that a driver not familiar with the ignition lock is inclined to suspect a functional fault. A functional fault which prevents the engine from being switched off and the key from being withdrawn may be very irritating, since the driver would not be able to exit the vehicle and leave it unattended, in order to call help. 
         [0007]    Accordingly, there is a need to provide an ignition lock with improved operational safety, where an irritation of even a driver not familiar with this ignition lock can be safely avoided. 
       SUMMARY 
       [0008]    The present disclosure is directed to an ignition lock for a motor vehicle, in which a locking cylinder, in the presence of a suitable key, can be shifted between a driving position in which the ignition lock allows operation of an engine of the motor vehicle, and a stationary position in which operation of the engine is blocked, along a path including a punctual directional change. An indicating device or display is controlled by a switch operable by the locking cylinder. Because the indicating device reacts when the point of directional change is reached, it can be ensured that the driver perceives the information shown on the indicating device in good time and can use it to successfully bring the key into the stationary position. 
         [0009]    In order to be able to indicate the information in the form of text in the language of the user or in pictorial form, an indicating device is preferably a monitor. 
         [0010]    In particular the indicating device may include a multi-function indicating instrument. While driving, the multi-function indicating instrument can be used to display other information such as speed, engine revolutions etc., which at the moment of switch-off is no longer needed, so that an indication of information pertaining to movement of the key or the locking cylinder along the path the key movement can be substituted therefor. Since an indicating instrument can be used, which is provided in a prominent place in the vehicle, it is ensured that the driver will reliably perceive the information. 
         [0011]    Moving the locking cylinder from the driving position into the stationary position should include a first rotation to the point of directional change and a translation in direction of the axis of the first rotation. This can be followed by a second rotation in direction of the stationary position. 
         [0012]    The locking cylinder can be impacted by a spring against the direction of translation. This ensures that the probability of forces accidentally impacting the key thereby initiating the translation, are reliably minimized. On the other hand, a spring impact against the translation direction is not effective in order to inadvertently bring the locking cylinder into the driving position. 
         [0013]    The switch may be designed in such a way that the presence of the locking cylinder at the point of directional change is sufficient for operating the switch. In the simplest case, the switch is constructed analogously to conventionally existing switches controlling the electrical components of the vehicle. In particular, various contact fields may be arranged on a common surface, and contacts complementary to the contact fields are movably coupled to the locking cylinder on the surface between a position touching the contact field and a position separated from the contact field. 
         [0014]    In a preferred embodiment, the presence of the locking cylinder at the point of directional change is not enough in order to operate the switch; rather the switch is operable by a torque applied to the locking cylinder at the point of directional change. 
         [0015]    In order to avoid that a driver familiar with the ignition lock is notified by the hint on the indication the device every time the vehicle is switched off, a control unit may be adapted to function as a time switch member, which activates the indicating device only if the switch is continuously operated during a predefined time interval. If a driver familiar with the function of the ignition lock quickly moves the locking cylinder past the point of directional change thus operating the switch for a short time only, the indicating device remains inactive. 
         [0016]    Similarly, a control unit may be provided, which activates the indicating device if the switch is repeatedly operated during a predefined time interval, in particular if a driver, who assuming that the ignition lock is a conventional lock, repeatedly turns the key back and forth in his attempt to reach the stationary position. 
         [0017]    In order to mark the point of directional change, two stages extending in axial direction may be provided, of which one is movable with the locking cylinder, and where both meet up at the point of directional change. The other stage may be immovable or movable only to a limited extent in comparison to the first stage. For this reason at least part of the switch may be conveniently provided on the other stage. The other stage may be part of a transfer body, which extends annularly around the locking cylinder. If there is no space for the switch directly on the stages, it may be arranged at any point of the circumference of the transfer body between the same and a vehicle-fixed holder of the ignition lock. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements. 
           [0019]      FIG. 1  shows a schematic view of an ignition lock according a first embodiment of the present disclosure; 
           [0020]      FIG. 2  shows a circuit board with contact fields of the ignition lock of  FIG. 1 ; 
           [0021]      FIG. 3  shows a section through an ignition lock according to a second embodiment of the present disclosure; 
           [0022]      FIG. 4  shows a section analogous to  FIG. 3  according to a third embodiment; and 
           [0023]      FIG. 5  shows a section according to a fourth embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description. 
         [0025]      FIG. 1 , in a generalized schematic view, shows a locking cylinder  1  of an ignition lock with a key  2  in the lock. The locking cylinder  1  is surrounded by a sleeve  3  fixedly mounted in the dashboard of a motor vehicle. The locking cylinder  1  is movable in the sleeve  3  in direction of a longitudinal axis  4  and clockwise rotatable about the longitudinal axis  4 . A rotation of the locking cylinder  1  in clockwise direction into a driving position is possible out of the shown position, a rotation in anti-clockwise direction is blocked, because a blocking cam  5  at an inner end face of the sleeve  3  engages in a recess  7  of second sleeve  6 , which is non-rotatably connected to the locking cylinder  1 , and two stages  8 ,  9  of sleeves  3 ,  6  extending in axial direction are in contact with each other. 
         [0026]    A helical spring  10  holds the sleeve  6  pressed against the inner end face of the sleeve  3  and a projecting stop  11  of the locking cylinder  1 , which is hidden inside the sleeves  3 ,  6 . When the locking cylinder  1  is pressed in direction of the longitudinal axis  4 , the projecting stop  11  takes the sleeve  6  with it and in doing so compresses the helical spring  10 . This causes the blocking cam  5  to move out of the recess  7 , thereby making it possible for the locking cylinder  1  to be rotated in anti-clockwise direction into a stationary position. 
         [0027]    The helical spring  10  is supported against a contact carrier  12 , which is non-rotatably but axially movably connected with the locking cylinder  1  and is therefore not taken along, when the locking cylinder  1  is pressed in. The contact carrier  12 , on its side facing away from the observer, includes a plurality of contact pins in the known manner that during the course of a rotation of the closing cylinder  1  move past contact fields on the surface  13  of a circuit board, which in  FIG. 1  are hidden under the contact carrier  12 . Power supply circuits of electrical components of the vehicle are closed in succession during a movement of the closing cylinder  1  from the stationary position into the driving position/opened in succession during a movement of the locking cylinder  1  back into the stationary position. 
         [0028]      FIG. 2  shows a plan view onto contact fields  14 ,  15  on the surface  13  of the circuit board. The contact fields  14  extend as concentric circular arches around the longitudinal axis  4 . Most of these contact fields  14  are elongated and arranged in such a manner that the tips of the contact pins  16  facing the contact fields  14  in  FIG. 2 , during the movement from the driving into the stationary position, move as indicated by arrows in  FIG. 2 , on an electrically insulating area of the surface  13 . The contact fields  14  extends over merely a very short section of the arch and is placed on the surface  13  in such a way that it is contacted by the associated contact pin  16  at precisely the intermediate position shown in  FIG. 1 . 
         [0029]    Closing a switch  19  formed by the contact field  15  and its associated contact pin  16  via the contact field  15  activates the control unit  17  (see  FIG. 1 ) of an indicating instrument  18  on the dashboard of the vehicle. The indicating instrument  18  may be a monitor, which in driving position indicates the speed of the vehicle, the engine revolutions and/or operating parameters. In the intermediate position the control unit  17  replaces these display values by a hint in the form of a picture or of text, that in order to achieve the stationary position it is necessary to press down on the locking cylinder  1 . 
         [0030]    When rotating the locking cylinder  1  from the stationary into the driving position, a ramp  20  opposite the stage  8  of the blocking cam  5  glides along the sleeve  6  and in doing so, urges it inwards against the restoring force of the helical spring  10 . This rotational movement is therefore not interrupted at the intermediate position and the contact pin  16  moves quickly over and past the contact field  15 . A certain delay in switching by the control unit  17  is therefore enough in order to suppress the display of the hint which in this case is superfluous. Also during retracting the locking cylinder  1  into the stationary position provision may be made for the switch  19  formed by the contact field  15  and the pin  16  to be kept closed for a predefined timespan, before the hint is displayed. A experienced user who knows that he has to press down on the locking cylinder and therefore passes through the intermediate position in a shorter time, does not have the hint displayed, but an inexperienced user who holds the locking cylinder in the intermediate position because he believes to be able to rotate it straight into the stationary position, would have it displayed. 
         [0031]    The control unit  17  may further be configured to display the hint, even if the switch  19  is repeatedly closed within a second predefined timespan. In this case the hint will also be displayed to a user, who, in the attempt to overcome a suspected blockade of the ignition lock, turns the key  2  back and forth. 
         [0032]      FIG. 3  shows a schematic section through the ignition lock along a plane extending perpendicularly to the axis  4  through the blocking cam  5 , according to a second embodiment of the present disclosure. Here the contact field and the associated contact pin are replaced by a switch  21 , which includes two switching contacts  22 ,  23  on the shoulder  8  of the blocking cam  8  connected to the control unit  17  and a conductive platelet  24  on the shoulder  9  of the sleeve  6 . When rotating the locking cylinder  1  from the driving position into the intermediate position, the shoulders  8 ,  9  are pressed against each other and the switch  21  closes and the control unit  17  is activated in order to output the hint. When rotating the locking cylinder  1  from the stationary into the driving position the shoulders  8 ,  9  do not make contact and the switch  21  remains open. 
         [0033]    According to a variant shown in  FIG. 4 , one of the two switching contacts  22  is held by a spring  25  in a position, in which it projects past the other switching contact  23 . To close the switch  21  the spring  25  has to be compressed to the extent, where the platelet  24  also contacts the other switching contact  23 . A driver, who expects to be able to bring the locking cylinder  1  into the stationary position by a simple rotation, supplies the necessary force and therefore has the hint displayed to him. A driver who knows that he has to press down on the locking cylinder  1  and does so, does not have the hint displayed to him. 
         [0034]      FIG. 5  shows a section through the ignition lock along a plane extending perpendicularly to the axis through the sleeve  3 , according to a further variant. The sleeve  3  here is anchored in a holder  26  in that a radial projection  27  of the sleeve  3  engages in a recess of the holder  26 . When during the attempt to rotate the locking cylinder  1  into the stationary position the shoulders  8 ,  9  of sleeves  3 ,  6  come into contact with each other, the force exercised in the attempt is transferred to the projection  27 . A switch  29  on a flank of the projection  27  operable by this force can therefore replace the above-described switch  21 . Since the switch  28  may be attached at a larger distance from the locking cylinder  1  than the switch  21 , it is subject to merely loose marginal condition as regards its constructional form, so that a low-cost standard component can be used. 
         [0035]    While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.