Abstract:
An antitheft device for the steering column of a motor vehicle, in which a movable indexer includes a return spring for returning the movable indexer such that the indexer engages with at least one profile of a cam of the antitheft device, and in which the return spring of the indexer and a return spring of a bolt of the antitheft device are separate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a national stage application based on PCT/EP2012/050113, filed on Jan. 4, 2012. This application claims the priority from the same, and hereby incorporates the same by reference in its entirety. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
     Not Applicable 
     INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC OR AS A TEXT FILE VIA THE OFFICE ELECTRONIC FILING SYSTEM (EFS-WEB) 
     Not Applicable 
     STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINT INVENTOR 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     The invention relates to steering-column locks of the electrically motorized type. 
     Many constructions of steering-column locks are known. First, steering-column locks have been proposed comprising a motor and a gearwheel which drives a locking bolt via a cam or a gradient associated with the gearwheel, wherein the gearwheel rotates about a shaft which is parallel to an output shaft of the electric motor, or else in which the gearwheel rotates about a shaft which is perpendicular to the output shaft of the electric motor. 
     The bolt then travels slidingly closer to the steering column, under the action of a profile arranged on the gearwheel, to a locked position of the steering column. 
     Conventionally, the bolt is designed to immobilize the shaft of the steering column by fitting into a longitudinal groove arranged on the contour of this shaft. For this purpose, the shaft comprises several grooves distributed angularly on its contour. The portions of the contour of the shaft separating two successive grooves are called teeth. When the bolt is in protruding position of interaction with the contour of the column shaft, it is either fitted into a groove for immobilizing this shaft, or in contact with a tooth. In the latter case, the column shaft is not prevented from rotating. However, as this is conventional, if the steering wheel connected to the shaft is operated, this shaft is automatically immobilized after a brief angular travel of the latter having the effect of placing a groove in line with the bolt so as to allow the latter to fit into this groove. 
     In the case of a motorized steering lock, it is essential to define positions called unlocking and locking positions in order to switch off the motor when they are reached. Accordingly, an indexing device and indexer associated with the bolt are provided, that is to say that the motor will be switched off only when the bolt has reached the unlocked position or the locked position. With respect to the position called the locked position, because the bolt may be either on a tooth or in a groove, two options can be used. The first option consists in defining the locked position for a bolt that is in a groove, this position corresponds to the lowest position of the bolt. If, in this indexation configuration of the locked position, the bolt is not in a groove but on a tooth, the bolt has not been able to reach its bottom position and therefore the locked position has not been able to be detected. The motor therefore continues to run. In order to prevent this phenomenon, it is therefore preferred to define the position called the locked position for a bolt that is on a tooth. In this indexation configuration of the locked position, the motor is stopped for a bolt position that has not reached the bottom level, that is to say in a groove. In order to compensate for this difference, provision is made to keep the motor running for a certain period of time. Unfortunately, with this additional rotation, the gearwheel risks reaching its position of abutment and causing a repetition of mechanical force on this abutment. 
     BRIEF SUMMARY OF THE INVENTION 
     The object of the invention is to alleviate these drawbacks while maintaining a compact configuration of a steering lock that can be housed in a restricted space at the bottom of the steering column. 
     This object is achieved according to the invention by virtue of a motorized steering-column lock for a motor vehicle capable of adopting a locked configuration and an unlocked configuration of the steering column of the vehicle, said steering lock comprising:
         an electric motor driving a gearwheel,   at least one profile placed on at least one face of the gearwheel,   a bolt that can move between a locked position and an unlocked position of the steering column, said bolt comprising:
           a main bar of which one end interacts with an element of the steering column in the locked position,   the bolt interacting with said profile such that the profile drives the bolt between the locked position and the unlocked position of the column,   a return spring for returning the bolt to the locked position,   
           a movable indexer interacting with at least one sensor in order to detect a position of the profile controlling a locked configuration of the column of the steering lock,
 
characterized in that it comprises a return spring to return the movable indexer in interaction with said at least one profile and in that the return spring of the indexer and the return spring of the bolt are distinct.
       

     A steering lock according to the invention may also have one or more of the features below considered individually or in all the technically possible combinations:
         The indexer comprises a magnet and said at least one sensor is a Hall effect sensor.   The sensor is a mechanical commutator and in that the indexer is furnished with a surface element capable of interacting with said at least one mechanical commutator.   The indexer is translatably mounted in a channel arranged on the bolt.   The return spring of the bolt is mounted between the bolt and a fixed element of the steering lock such that the compression of the spring does not depend on a relative position of the bolt and of the movable indexer.   The output shaft of the motor, the direction of movement of the bolt and the direction of movement of the movable indexer are parallel.   The bolt and the movable indexer rest on the profile of the gearwheel from the same side of said profile and move in the same direction against the profile.       

     The invention also relates to a module for assisting the rotation of a steering column, comprising an assistance motor applying a pivoting force to the steering column, characterized in that it comprises a steering lock according to any one according to the preceding features. 
     The invention also relates to an assembly consisting of a steering column of a motor vehicle and a steering lock according to any one of the preceding features. 
     Finally, the invention relates to a combined assembly of a steering column of a motor vehicle and a module for assisting the rotation of the steering column according to the preceding features, wherein the steering column comprises a peripheral ring gear in which the bolt is engaged in the locked position and which peripheral ring gear receives a steering-column pivoting force delivered by the assistance motor. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Other features, objects and advantages of the invention will become apparent on reading the following detailed description made with reference to the appended figures in which: 
         FIG. 1   a  is a view of a steering lock according to a preferred embodiment of the invention in an unlocked configuration of the steering column of the vehicle; 
         FIG. 1   b  is a view of a steering lock according to a preferred embodiment of the invention in a locked configuration of the steering column of the vehicle; 
         FIG. 1   c  is a view of a steering lock according to a preferred embodiment of the invention in an intermediate configuration of locking of the steering column of the vehicle; 
         FIG. 2   a  is a view of the column in the unlocked position, 
         FIG. 2   b  is a view of the steering column in a locked position, 
         FIG. 2   c  is a view of the column in the RTL (ready to lock) position, 
         FIG. 3  is a view representing a combined assembly consisting of a steering column and a module for assisting the rotation of the steering column according to a preferred embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The steering lock shown in  FIG. 1   a  comprises an electric motor  10  furnished with an output shaft forming a worm  15 , a gearwheel  20  engaged on the worm  15 , and a bolt  30  mounted slidingly, these various elements being placed in a housing not shown. 
     The gearwheel  20  is mounted so as to rotate about a shaft  21  which extends perpendicularly to the output shaft of the motor  10  such that the output shaft of the motor is indistinguishable in the geometric plane of the wheel. 
     The wheel  20  has a first face  22 , turned toward a steering column not shown, which is furnished with a cam  23  in a disk portion which interacts with the bolt. Accordingly, the bolt  30  has, in addition to a main bar  31 , a lateral appendage  32  capable of being interposed, at its first end  33 , onto the path of the cam  23  when the latter pivots with the gearwheel  20 . The lateral appendage  32  is pushed against the cam  23  under the effect of the return spring  40  which returns the bolt  30  to the locked position. This interaction of the lateral appendage  32  of the bolt  30  with the cam  23  therefore has the effect of bringing the main bar  31  closer to an outer ring gear  50  of the steering column. 
     In an alternative embodiment not shown, the cam  23  is replaced by a gradient. 
     The steering lock also comprises a control unit advantageously implemented in the form of an electronic circuit placed in the housing. In addition to implementing the control of the electric motor  10 , the control unit also takes account of the information supplied by an indexation device. 
     This indexation device makes it possible to inform the motorized control unit that the gearwheel has reached a position allowing the main bar  31  of the bolt to carry out the locking and the unlocking. In response to this information, the control unit commands the stopping of the motor. 
     This indexation device essentially comprises a movable indexer  60  interacting with two sensors not shown of which one is used for detecting the position called the unlocked position and the other for the detection of the position called the locked position. 
     The position called the unlocked position is illustrated in  FIG. 3   a  and corresponds to a position in which the main bar  31  of the bolt  30  is at a distance from the outer ring gear of the steering column. As can be seen also in  FIGS. 3   b  and  3   c , the ring gear  50  of the column consists of grooves  51  surrounded on either side by teeth  52 . The locking of the column takes place when the main bar  31  of the bolt  30  is at the bottom of a groove  51 , resting against an interstice of the ring gear  50 , thus preventing the ring gear  50  and hence the column from rotating. In certain conditions, although the gearwheel has reached the position called the locked position, the main bar  31  of the bolt  30  may be resting on a tooth  52  of the ring gear  50 . This position is called the RTL (ready to lock) position. Specifically, in this position, the column can be rotated. However, as is conventional, if the steering wheel connected to the column is operated, a brief angular travel of the latter will have the effect of placing a groove  51  in line with the main bar  31  of the bolt  30  so as to allow the latter to fit into this groove  51 . This fitting will take place with the aid of the return spring  40  of the bolt. 
     The movable indexer  60  advantageously consists of a bar extending longitudinally parallel to the sliding axis of the bolt  30 , a first end  61  of the movable indexer  60  pressing on the cam  23  of the gearwheel  20 . The movable indexer  60  is held, at its first end  61 , pressing on the cam  23  by a return spring  62 , advantageously placed on the second end of the movable indexer  60 . It is also on this second end that a magnet  63  is placed. In this case, the two indexation sensors are of the Hall effect or Reed switch type. In an alternative embodiment, a boss is placed on the second end of the indexer  60 , and the two magnetic sensors are replaced by mechanical commutators. Thus configured, the movable index  60  will, under the rotary action of the gearwheel  20 , follow the contour of the cam  23  and move in a direction parallel to the sliding direction of the bolt  30 . 
     In one advantageous embodiment, notably for requirements of compactness, the movable indexer  60  is placed so as to slide freely in a groove  34  arranged on the lateral appendage  32  of the bolt  30 . 
     Starting from an unlocked position illustrated in  FIGS. 1   a  and  2   a , and to reach a locked position illustrated in  FIGS. 1   b  and  2   b  or  FIGS. 1   c  and  2   c , the gearwheel  20  will turn in the clockwise direction. The end  33  of the lateral appendage  32  of the bolt  30  and the end  61  of the movable indexer will both initially follow the contour of the cam  23  and respectively drive the bolt  30  and the movable indexer  60  to slide parallel in the same direction. As illustrated in  FIGS. 1   c  and  2   c , because the movable indexer  60  slides freely in the groove  34  arranged on the lateral appendage  32  of the bolt  30 , the movable indexer  60  can reach the locked position while the bar  31  is in the RTL (ready to lock) position, the motor will then receive a stop instruction via one of the sensors of the indexation device. 
     In one advantageous embodiment, the steering-column lock is an element of forming a module for motorized assistance to the rotation of the steering column. Incorporating the steering lock in a module for motorized assistance to the pivoting of the steering column provides an advantage in terms of safety since the steering lock is then in a particularly low portion of the steering column, at a particularly great distance from the instrument panel where a thief by predilection takes action and in a particularly inaccessible portion of the vehicle. 
     As illustrated in  FIG. 3 , in this case the motorized assistance module comprises an assistance motor  70  which is oriented such that its output shaft  75  extends parallel to the steering column. The output shaft  75  of the motor  70  has peripheral gear teeth which mesh with a ring gear  50  surrounding the steering column in order to rotate the latter. The ring gear  50  is advantageously the ring gear in which the bolt engages such that only one ring gear is used for both functions of driving and immobilizing, further reducing the space requirement necessary for the implementation of the assistance module described. 
     Advantageously, the steering lock and the assistance motor are placed radially opposite with respect to the steering column, such that the bolt and the output shaft  75  of the assistance motor do not interfere. The motorized assistance module advantageously comprises one and the same electronic control unit for the assistance of pivoting and for controlling the immobilization of the column, which ensures that no assistance control is applied to the assistance motor when the steering lock is in the locked position. 
     Due to the fact that the steering-column lock, in this instance referenced  71 , is a portion of the module for motorized assistance to the rotation of the steering column, the control unit that is common to the motorized assistance and the locking of the steering column is advantageously fitted with a control logic applying a slight rotational movement of the steering column when it simultaneously controls a driving force to unlock the bolt. Thus, by this slight movement, any frictional retention is removed between the bolt and the steering column, for example between the bolt and a lateral edge of a tooth of the ring gear  50  and the bolt slides reliably each time the vehicle is switched on. 
     The control unit is advantageously implemented in the form of an electronic circuit placed in a common housing  80  of the assistance motor  70  and of the steering lock  71 . The electronic circuit is advantageously positioned outside the housing specific to the steering lock. In addition to implementing the control of the steering lock via this control unit notably in this instance takes account of the position of the bolt which is indicated to it by the receipt of output signals from the indexer positioning sensors as described above. 
     Naturally, many modifications can be made to the invention without departing from the context of the latter.