Abstract:
A disengageable lock for a motor vehicle locking system includes a fixed stator, a sleeve, a rotor, a driver, and an indexer. The sleeve is mounted rotatably in the stator and is fixed axially relative to the stator. The rotor is mounted rotatably in the sleeve and is fixed axially in the sleeve. The driver is connected in disengageable rotation on the rotor. The indexer, which is axially mobile between rest and disengagement positions, is connected in translation in the stator by ribs surrounding the sleeve. When an appropriate key is inserted in the rotor, the driver couples the rotor and a cam actuator in rotation, releasing the lock. When an inappropriate key is inserted, the rotor and the sleeve rotate, causing the indexer to move toward the cam actuator. Because the indexer is rotationally immovable as a result of its connection with the stator, the cam actuator cannot rotate.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a disengageable cylinder for an automobile lock mechanism. 
     The addition of a disengageable mechanism to a cylinder intended for an automobile lock makes it possible to prevent this cylinder from being forced. Specifically, if an improper key, or any other flat tool of suitable shape, is inserted into the rotor, and if an attempt is then made to rotate the rotor, the disengagement mechanism enables the rotor and an intermediate sleeve to pivot freely inside the stator without considerable stresses being exerted on the tumblers. 
     The fact is that, in the presence of excessive stresses, the tumblers are liable to be damaged or be retracted by force, thus allowing the cylinder to be unlocked without the appropriate key. 
     The invention is concerned more precisely with a disengageable cylinder, in particular for a motor vehicle lock mechanism, comprising a fixed stator, a tubular intermediate sleeve which is mounted in rotation about its axis in the stator and which is fixed axially with respect to the stator, a rotor which is mounted in rotation in the sleeve, which is fixed axially in the sleeve and which comprises tumblers which can move radially under the action of a key intended to be inserted axially into the rotor. Tumblers are fully retracted inside the rotor when the key is appropriate, so as to allow a free rotation of the rotor with respect to the sleeve and the stator and thus allow a lock operating lever, called a cam actuator, to be rotated, this lever being coupled to the rotor via a driver. The rotor and the intermediate sleeve are blocked against rotation with respect to one another by the tumblers when the key is not appropriate. The cylinder also comprises an indexer which can move axially between a rest position and a disengagement position, under the effect of a rotation of the sleeve with respect to the stator subsequent to the rotor being rotated by means of an inappropriate key, so as to move the driver axially toward a disengaged position. 
     Such a disengageable cylinder is described in patent document FR 2 748 513. 
     In this known cylinder, the indexer and the driver are in a configuration with a substantially end-to-end arrangement. These two parts are substantially arranged as a continuation of one another. 
     The indexer is coupled in rotation with the intermediate sleeve and is guided in translation therein. The driver for its part is guided in rotation on the rotor. 
     The indexer comprises a main ring and guide tabs which extend axially from the ring and which are intended to be accommodated in corresponding axial notches of the intermediate sleeve. It also comprises two lugs which extend axially in the opposite direction in the continuation of two diametrically opposed guide tabs. 
     This cylinder arrangement poses the following technical problems. 
     Due to its configuration with an end-to-end arrangement, the length of such a cylinder is relatively large. 
     Moreover, the indexer is a relatively fragile part due to its construction. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention solves these problems by providing a disengageable cylinder which is particularly compact, that is to say one with a limited length and particularly robust construction. 
     Accordingly, the invention provides a disengageable cylinder, in particular for a motor vehicle lock mechanism, comprising a fixed stator, a tubular intermediate sleeve which is mounted in rotation about its axis in the stator and which is fixed axially with respect to the stator, a rotor which is mounted in rotation in the sleeve, which is fixed axially in the sleeve and which comprises tumblers which can move radially under the action of a key intended to be inserted axially into the rotor, the rotor and the intermediate sleeve being blocked against rotation with respect to one another by the tumblers when the key is not appropriate, a driver providing coupling between the rotor and an operating lever, called a cam actuator, when the key is appropriate, and an indexer which can move axially between a rest position and a disengagement position, under the effect of a rotation of the sleeve with respect to the stator subsequent to the rotor being rotated by means of an inappropriate key, so as to move the driver axially toward a disengaged position, characterized in that the indexer and the driver are cylindrical parts surrounding the rotor and can move while bearing on one another, in that the driver is connected in disengageable rotation on the rotor, and in that the indexer is connected in translation in the stator by means of ribs surrounding the intermediate sleeve. 
     According to a preferred embodiment, the driver is uncoupled from the rotor, in said disengaged position. 
     Preferably, the driver comprises internal ribs inserted in corresponding grooves of the rotor, in the engaged position, these grooves being open toward the rear of the rotor over a cylindrical portion whose diameter is less than the internal diameter of the driver. 
     Advantageously, the cylinder comprises a compression spring interposed between the cam actuator and the driver. 
     Preferably, the driver comprises, on its edge facing the cam actuator, at least one guide tab intended to cooperate with a corresponding notch belonging to the cam actuator, this notch allowing a translation of the driver toward the cam actuator against the force of the compression spring. 
     Said notch may be open on the rear end face of the cam actuator. 
     The driver may comprise a collar and two guide lugs which extend axially toward the cam actuator from the collar. 
     Preferably, the indexer is coupled in rotation with the cam actuator, in said disengaged position. 
     Advantageously, the indexer comprises, on its edge facing the cam actuator, at least one guide tab intended to cooperate with a corresponding notch belonging to the cam actuator. 
     Preferably, the indexer comprises, on its edge facing the key entry, at least one guide tab intended to cooperate with a corresponding notch belonging to the intermediate sleeve. 
     Advantageously, the indexer comprises a main ring, two first guide tabs of trapezoidal shape, as seen in cross section through a plane tangential to the ring, which extend axially toward the key entry from the ring, and two second guide tabs which extend axially toward the cam actuator from the ring. 
     The intermediate sleeve may comprise two notches corresponding to said first guide tabs, and the cam actuator comprises two notches corresponding to said second guide tabs. 
     The invention is described in more detail below with the aid of figures representing only one preferred embodiment of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a disengageable cylinder according to the invention. 
         FIG. 2  is a view in longitudinal section of the disengageable cylinder according to the invention, in the initial position. 
         FIG. 3  is a view in cross section on G in  FIG. 2 . 
         FIG. 4  is a view in cross section on I in  FIG. 2 . 
         FIG. 5  is a view in longitudinal section on C in  FIG. 2 . 
         FIG. 6  is a view in cross section on J in  FIG. 2 . 
         FIG. 7  is a view in cross section on K in  FIG. 2 . 
         FIG. 8  is a perspective view of a cylinder according to the invention, in the engaged position, the stator not being represented. 
         FIG. 9  is a view in longitudinal section of the disengageable cylinder according to the invention, in the disengaged position. 
         FIG. 10  is a view in cross section on P in  FIG. 9 . 
         FIG. 11  is a view in longitudinal section on R in  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a rotary cylinder of longitudinal axis A 1  that comprises disengagement means according to the teachings of the invention. This cylinder is represented in  FIGS. 2 to 7  in the initial position before insertion of a key. 
     The cylinder  10  essentially comprises a rotor  12  which is rotatably mounted, about the axis A 1 , inside a fixed stator  14 , with a tubular intermediate sleeve  16  being interposed between the two of them, this sleeve being mounted in rotation about its axis in the stator and being fixed axially with respect to the stator. 
     A ball  60  is mounted intermediately in a radial through orifice  16 A formed in the intermediate sleeve  16 . The rotor  12 , on the one hand, has an external cavity  12 R for accommodating this ball, and the stator  14 , on the other hand, has an internal cavity (not shown) for accommodating this ball. This orifice  16 A, this cavity  12 B in the rotor and this cavity  14 B in the stator are arranged such that in the rest position, before rotation of a key, the orifice  16 A, the cavity  12 B in the rotor and the internal cavity in the stator are aligned as represented in  FIG. 2 . 
     The rotor  12  is intended to be rotated by means of a key (not shown) inserted axially inside the rotor  12  through a key entry  18  arranged in a front transverse face  20  of the rotor  12 , which face  20  is intended, for example, to be flush with the outside of a vehicle body panel (not shown). 
     The rear axial end  22  of the rotor  12  is intended to rotate a lever  24  which operates a lock mechanism (not shown) so as to allow the locking and unlocking of an opening leaf of the vehicle. 
     The rotor  12  is able to rotate the operating lever  24 , only in the presence of an appropriate key, via a driver  26  which can move axially in the cylinder  10 , under the action of an indexer  28 , between an engaged position in which it connects the rotor  12  and the operating lever  24  in rotation, and a disengaged position in which the rotor  12  is no longer able to rotate the lever  24  and in which the indexer  28  ensures that the lever  24  is blocked against rotation with respect to the stator  14  of the cylinder  10 . 
     The rotor  12 , the stator  14  and the intermediate sleeve  16  are not able to move in translation along the axis A 1  with respect to one another, and a helical compression spring  30  is interposed between the cam actuator  24  and the driver  26  so as to urge the latter axially rearward toward its engaged position. 
     The stator  14  has a cylindrical tubular general shape and it comprises means (not shown) which allow the cylinder  10  to be mounted and fastened on the vehicle. 
     In a known manner, the rotor  12  is intended to receive tumblers  32  arranged in transverse planes which follow one another at regular intervals in the direction of the axis A 1  of the cylinder  10 , these tumblers being received in corresponding housings of the rotor  12 . 
     The tumblers  32  can move radially in the rotor  12  and they are urged elastically toward a projecting position in which they partially protrude outside the housings of the rotor  12 . 
     However, when an appropriate key is inserted inside the rotor  12 , the tumblers  32  are fully retracted radially inward into the rotor  12 . 
     Thus, when the appropriate key is inserted into the rotor  12 , the latter can pivot freely with respect to the cylindrical intermediate sleeve  16  and with respect to the stator  14 . 
     However, if an inappropriate key, or any other tool, is inserted into the rotor  12 , the tumblers  34  are not fully retracted and are received inside corresponding apertures  36  arranged in the intermediate sleeve  16 . Thus, the tumblers  34  immobilize the rotor  12  in rotation with respect to the intermediate sleeve  16  which, for its part, remains free to rotate with respect to the stator  14 . 
     The indexer  28 , which can move axially between a rest position and a disengagement position, is connected in translation on the stator  14  via grooves arranged inside the stator and via ribs  38 A,  38 B which slide inside these grooves and surround the intermediate sleeve  16 . The ribs  38 A,  38 B and the grooves are two in number and are diametrically opposed. 
     The indexer  28  particularly comprises a main ring  38  and first guide tabs  40  of trapezoidal shape, as seen in cross section through a plane tangential to the ring  38 , which extend axially toward the front from the ring  38 . These first tabs  40  are intended to be received in corresponding axial notches  42  of the intermediate sleeve  16 . These first guide tabs  40  are two in number and are diametrically opposed on the ring  38 . 
     The notches  42  open out axially toward the rear in the rear axial end of the sleeve  16  such that, together with the guide tabs  40 , they make it possible to rotationally connect the indexer  28  with the intermediate sleeve  16 , while still allowing the possibility for the indexer  28  to move axially in the cylinder  10 . 
     The indexer also comprises second guide tabs  41  of rectangular shape, as seen in cross section through a plane tangential to the ring  38 , which extend axially toward the rear from the ring  38 . These second tabs  41  are intended to be received in corresponding axial notches  43  of the cam actuator  24 . These second guide tabs  41  are two in number, are diametrically opposed on the ring  38  and are arranged substantially opposite the first guide tabs  40 . 
     The driver  26  provides coupling between the rotor  12  and the cam actuator  24  when the key is appropriate. It is connected in translation on the rotor via internal ribs  26 A and via grooves  12 A belonging to the rotor  12 . 
     The internal ribs  26 A are inserted in the corresponding grooves  12 A of the rotor, in the engaged position, these grooves being open toward the rear of the rotor  12  over a cylindrical portion whose diameter is less than the internal diameter of the driver. 
     The driver  26  comprises a collar  39  whose outside or inside diameter is substantially equal to the outside or inside diameter of the ring  38  of the indexer  28 , the indexer and the driver being arranged end to end. 
     The driver  26  comprises guide lugs  45  of rectangular shape, as seen in cross section through a plane tangential to the collar  39 , which extend axially toward the rear from the collar  39 . These guide lugs  45  are intended to be received in corresponding axial notches  47  of the cam actuator  24 , these notches allowing a translation of the driver toward the cam actuator against the force of the compression spring  30  and advantageously being open on the rear end face of the cam actuator. These guide lugs  45  are two in number and are diametrically opposed on the collar  39 . 
     The cylinder  10  also comprises a return spring  50  which operates in torsion and which serves to return the cam actuator  24  to the initial position. 
     The operation of the cylinder according to the invention will now be described with reference to the other figures. 
     In  FIG. 8 , an appropriate key has been inserted into the rotor  12  through the key entry  18 , and the cylinder is thus in the engaged position. The tumblers  32  are thus retracted inside the rotor  12 , which can turn in the intermediate sleeve  16 . 
     In this position, the rotor  12  can be turned with the key and drives the driver  26  along with it, this driver, by virtue of its lugs  45  fitting into the corresponding notches  47  of the cam actuator  24 , causing said actuator to rotate, releasing the lock. 
     The other parts remain immovable, more precisely the intermediate sleeve  16 , which is rotationally immovable and connected to the stator  14  by the ball  60 , and the indexer  28  fitted into said sleeve by its front guide tabs  40 . 
     The rotation of the cam actuator  24  is obtained by the rotation of the following parts: key/rotor/driver/cam actuator. 
     At the end of travel, when the key is released, the return spring  50 , whose one end is fixed and other end butts against a lug  24 A of the cam actuator  24 , returns the cam actuator to the initial position along with the driver and the rotor. 
     In  FIGS. 9 to 11 , an inappropriate key has been inserted into the rotor  12  through the key entry  18 , and the cylinder is thus in the disengaged position. The tumblers  32  are thus not retracted inside the rotor  12 , which is consequently rotationally connected to the intermediate sleeve  16  as a result of the tumblers being inserted in the latter. 
     The rotation of the inappropriate key thus causes the rotor  12  and intermediate sleeve  16 , which are interconnected and take along the ball  60  in the orifice  16 A of the intermediate sleeve  16  and in the cavity  12 B in the rotor  12 , to be rotated. The rotation of the sleeve  16  results in the translation of the indexer  28  in the direction of the cam actuator  24  by virtue of the front guide tabs  40  of the indexer sliding out of the corresponding notches  42  of the sleeve  16 . In this translated position, the rear guide tabs  41  of the indexer  28  become inserted in the corresponding notches  43  of the cam actuator  24 . Since the indexer  28  is rotationally immovable as a result of its connection with the stator, the cam actuator cannot turn. 
     The driver  26  for its part is uncoupled from the rotor  12 , since it is pushed against the force of the compression spring  30  by the indexer  28  which bears on the front end face. Its ribs  26 A thus leave the corresponding notches  12 A of the rotor, and the rotational connection of the rotor and the driver is broken. 
     In this disengaged position, during the rotation of an inappropriate key, the ball rotationally connects the intermediate sleeve  16  and the rotor  12 , that is to say is inserted in the external cavity  12 B in the rotor. 
     The deliberate rotation of the key thus results in the movement of the following parts: rotation of the rotor/rotation of the intermediate sleeve/translation of the indexer and blocking of the cam actuator against rotation/rotation of the driver and uncoupling of the cam actuator. 
     During the subsequent insertion of an appropriate key, the rotor  12  is turned by virtue of the rotation of the key to the initial position represented in  FIGS. 2 to 7 , the ball  60  being released from the rotor, and then the cylinder is engaged if the key is appropriate or is disengaged if the key is inappropriate.