Abstract:
A locking device with a key-actuated cylinder core has a cylinder guide rotationally supporting the cylinder core and stopping points for tumblers. One area of the cylinder guide is received axially fixed but rotatably in a housing, while the other area is surrounded by a sliding member non-rotatably but axially slidably supported on the cylinder guide. A turning member surrounds the sliding member and is rotatable relative to and synchronously axially movable with the sliding member. A spring acts axially on the turning member. An overload protection device has a control element arranged on the housing and a counter control element, arranged on the sliding member and spring-loaded against the control element, for axially moving the sliding and turning members in an overload situation to release an axial coupling having one coupling member fixedly connected to the cylinder core and another coupling member arranged on the turning member.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a locking device, in particular, in a motor vehicle, with a key-activated cylinder core which performs locking functions upon rotation. For a rotational support of the cylinder core a cylinder guide is provided having stopping points for tumblers positioned within the cylinder core. In order to make the locking device theft-proof, an overload protection device is provided which is comprised of, on the one hand, an axially fixed profiled control element and a profiled counter control element that is axially movable and spring-loaded against the profiled control element. An overload situation occurs when, without key, a forced rotation is exerted on the cylinder core. In this case, the profiled counter control element is axially lifted off the profiled control element and decouples a turning member relative to the cylinder core, and the cylinder guide is freely rotatable relative to the cylinder core because the cylinder core is fixedly connected thereto by the tumblers. The turning member is now inactive, while normally, upon actuation by the key, it performs the desired locking function, for example, in a lock. 
     2. Description of the Related Art 
     In a known locking device of this kind (DE 41 22 414 C1) the profiled control element and the profiled counter control element of the overload securing device are arranged between the housing and the overload protection device while the coupling is realized between the turning member and the cylinder core. The cylinder guide is axially spring-loaded relative to the housing. Between the housing and the cylinder guide a large annular space for a coil spring which surrounds a portion of the cylinder guide must be arranged. Mounting of these components is cumbersome and time-consuming. The transition of the normal situation into the overload situation results in an axial movement of the cylinder guide together with the cylinder core supported therein because the profiled control element of the overload protection device is lifted off the profiled counter control element. This is disruptive. This disruptive axial movement from the normal situation into the overload situation can be oriented axially outwardly (compare FIGS. 1 through 9) or axially inwardly (compare FIG.  10 ). 
     There are also locking devices of the aforementioned kind (DE 44 10 783 C1) in which the cylinder guide is not spring-loaded and, together with the cylinder core supported therein, always has an axially fixed position within the housing. In the transition between the key-activated normal situation into the overload situation resulting from the use of a burglary tool, the cylinder core therefore does not perform a disruptive axial movement. Moreover, radial space is also saved in this context because there is no pressure spring acting on the cylinder guide. 
     The disadvantage of this device is however the large axial construction length. The profiled control element and the profiled counter control element of the overload protection device are arranged between the inner end face of the cylinder guide and a pressure ring which is longitudinally slidable but rotationally fixedly connected to the turning member performing the locking function. 
     SUMMARY OF THE INVENTION 
     The invention has the object to develop a locking device of the aforementioned kind in which the cylinder guide and the cylinder core are axially fixedly received in the housing and freely rotatable in the overload situation, but characterized by a minimal axial construction length. 
     In accordance with the present invention, this object is solved in that: 
     for rotationally supporting the cylinder core a cylinder guide is provided which has stopping points for tumblers located in the cylinder core; 
     the cylinder guide is received axially fixed but rotatably in a housing that supports the cylinder guide in the area facing the 
     key, while the other area of the cylinder guide is surrounded by a sliding member fixed against rotation relative to the cylinder guide but axially slidably supported thereon, wherein the sliding member is surrounded by a turning member that is rotatable relative to the sliding member and synchronously axially movable with it; 
     a spring supported on the housing acts axially on the turning member and thus onto the sliding member synchronously movable with the turning member; 
     an overload protection device has a profiled control element arranged on the housing and a profiled counter control element, arranged on the sliding member and spring-loaded against the profiled control element, for axially moving the sliding member and the turning member synchronously movable therewith in the overload situation in order to release an axial coupling whose one coupling member is non-rotatingly fixedly connected to the cylinder core and whose other coupling member is arranged on the turning member. 
     The housing supports only an area of the cylinder guide facing the key while the other area of the cylinder guide is surrounded by a sliding member which is secured against rotation relative to the cylinder guide but is axially slidable thereon. The sliding member is surrounded by the turning member that transmits the locking functions and is rotatable relative to the sliding member and axially synchronously movable with it. The spring serving as overload protection acts axially onto the turning member and thus onto the sliding member which is movable synchronously with the turning member. The profiled elements of the overload protection device are arranged between the sliding member, on the one hand, and the housing provided for supporting the cylinder guide, on the other hand. According to the invention, the profiled elements of the overload protection device can be arranged easily in that axial portion of the cylinder core where the cylinder core has the tumblers and the cylinder guide the stopping points for the tumblers. This results in a reduction of the axial construction length relative to the latter prior art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further measures and advantages of the invention result from the dependent claims, the following description, and the drawings. One embodiment of the invention is represented in the drawings. It is shown in: 
     FIG. 1 a plan view onto the locking device before its mounting in the door of a motor vehicle; 
     FIG. 2 schematically an axial section along section line II—II of FIG. 1 with the components in their rest position and initial rotational position, wherein the cylinder core as well as the cylinder guide are shown in the lower half section with the inner end broken away in order to allow viewing of the inner surfaces of the components radially surrounding it, i.e., a cylinder housing and a sliding member; and in the upper half section in the representation of 
     FIG. 2 a  a sectional view perpendicular thereto along the section line IIa—IIa of FIG. 1 through a cylinder core and a cylinder guide; 
     FIG. 3 in a representation analog to FIGS. 2 and 2 a , an axial section of the device along the section lines II—II and IIa—IIa of FIG. 1, of an overload situation wherein by means of a burglary tool the forced rotation of the components is carried out; and 
     FIG. 4 a cross-section of the device along the section line IV—IV of FIG.  2 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The locking device comprises a cylinder core  10  with tumblers  12  force-loaded by springs  11  and received radially movably in the cylinder core  10  so as to engage normally with their ends stopping points  13  of a cylinder guide  14 . The stopping points  13  of neighboring tumblers  12  in the present case are separated from one another by stays in the cylinder guide  14  which increases stability. A key  15  with matched key profile is correlated with the cylinder core  10  which, when inserted, sorts the projecting ends of the tumblers  12  in the key channel  16  of the cylinder core  10  with respect to the core cross-section and thus releases the cylinder core  10  relative to the cylinder guide  14  for rotation. 
     The cylinder guide  14  serves normally as a rotational support for the cylinder core  10 . 
     The cylinder guide  14  is axially fixedly but rotatably received in the housing  17  which is fastened stationarily within the interior of the motor vehicle door. By means of an overload protection device  30 , to be explained in more detail in the following, the cylinder guide  14  is usually non-rotatably indirectly secured in the housing  17  by a sliding member, here in the form of a sleeve  20 . Between the inner surface of the sliding sleeve  20  and the circumferential surface of the cylinder guide  14  radial toothings  21 , complementary relative to one another, are provided which generate an axial guiding of the sliding sleeve  20  on the cylinder guide  14  as well as a rotationally fixed connection between the cylinder guide  14  and the sliding sleeve  20 . This not only holds true for the normal situation of the locking device, shown in FIG. 2, but also for the overload situation represented in FIG.  3  and to be explained in more detail in the following. 
     In the normal situation, according to FIG. 2, the cylinder core  10  is secured by an impulse spring in the initial rotational position indicated by the auxiliary line  19  in FIG.  1 . By means of the key  15  inserted into the key channel  16 , the cylinder core  10  can now be moved into the rotational working positions indicated by auxiliary lines  19 ′ and  19 ″ and corresponding to a secured and an unsecured position of the locking device. The rotations of the cylinder core  10  illustrated by the arrows of rotation  18 ,  18 ′ of FIG. 1 namely effect in this normal situation analog rotations  48  and  48 ′ of a working arm  41  belonging to the turning member  40 . This working arm  41  is normally positioned in the initial rotational position indicated by the auxiliary line  49  in FIG. 1 which is transformed into the rotational positions illustrated by corresponding auxiliary lines  49 ′,  49 ″ in the direction of the rotational arrows  48 ,  48 ′. As illustrated in FIG. 1, a working rod is connected to a pivot joint  42  of the working arm  41  and extends in the direction of the dash-dot arrow  43 ; it is the first member of a lock, not represented in detail. The rotational positions  49 ′,  49 ″ correspond to a secured or unsecured position of the locking device. In the secured position the actuation of a handle on the motor vehicle door is successful, but in the unsecured position the actuation of the handle has no effect. In the portion of the housing  17  referenced by  39 , control means for a so-called “central locking device” of a motor vehicle are provided by which locking devices on different doors of the motor vehicle cooperate. 
     As can be seen in FIG. 2, the turning member  40  has a cylinder portion  44  which is rotatably supported on the sliding sleeve  20 . The sliding sleeve  20  has an axial inner shoulder  25  at its inner end, and on its outer side an axial counter shoulder  45  provided at the turning member  40  is supported. At this location the transmission of the axial spring load illustrated by the force arrow  34  in FIG. 2 between the turning member  40  and the sliding sleeve  20  takes place. This spring load  34  is the result of a rotation and pressure spring  33  which is arranged in an axial receptacle  46  in the turning member  40 . The outer end  47  of the turning member  40  facing the housing  17  remains without support. 
     The axial coupling between the turning member  40  and the cylinder core  10 , respectively, its axial extension is realized by two coupling members  51 ,  52  of a coupling  50  which in the normal situation engage one another. In the represented embodiment, as illustrated in FIG. 4, one of the coupling members is comprised of diametrically radially extending projections  51  on the cylinder core  10  and the other coupling member is comprised of corresponding recesses  52  on an inner flange of the cylinder portion  44 . The spring  33  secures the turning member  40  usually in the coupled position according to FIGS. 2 and 4. The spring load is supported namely by the aforementioned counter shoulder  45  and the inner shoulder  25  on the sliding sleeve  20  which, in turn, rests against an inner surface of the housing  17  or, via an inner flange provided in the area of the inner shoulder  25 , against the inner end face of the cylinder guide  14 . This results in the effective initial coupling position  53 , illustrated by the auxiliary line  53  in FIG. 2, of the turning member  40  relative to the cylinder core  10 . The aforementioned rotations  18 ,  18 ′ of the cylinder core  10  cause analog rotations  48 ,  48 ′ of the working arm  41  of the turning member  40 . 
     The spring  33  is supported with its inner end on an end disc  22  which engages with a cylindrical projection  23 , illustrated in the sectional view of FIG. 4, the aforementioned axial receptacle  46  of the turning member  40 . The end disc  22  is axially fixedly positioned relative to the cylinder core  10 , respectively, the stationary housing  17 . In the present case a fixed connection  24 , illustrated in FIG. 3, is provided between the end disc  22  and the inner end of the cylinder core  10 . 
     In the embodiment the axial spring load  34  also serves to maintain engagement of the overload protection device  30  in the normal situation, according to FIG.  2 . The overload protection device is comprised of two profiled elements  31 ,  32  which cooperate in a control-effecting manner with one another. They are comprised of an axially fixedly positioned profiled control element  32 , that is a component of the housing  17  and in the present case is comprised of a recess  32  delimited by two slanted surfaces in the inner wall of the housing  17 . The movable profiled counter control element is positioned at the outer end face of the sliding sleeve  20  and is comprised of a cam  31  with correspondingly slanted flanks. It is understood that the profiled elements cooperating in pairs with one another, i.e., a radial projection  31  and a recess  32 , can be arranged in multiples over the circumference of the sliding sleeve; for example, two pairs in a diametric position relative to one another. 
     In the normal situation of FIG. 2, as mentioned above, the engagement position of the cam  31  in the recess  32  is present so that the sliding sleeve  20  is non-rotatable. Moreover, the sliding sleeve  20  is secured by profiled elements  31 ,  32  of the overload protection device in a certain rotational position. By means of the aforementioned radial toothings  21  this results in a corresponding rotational position of the cylinder guide  14 . Thereby, the aforementioned initial rotational position  19  of the cylinder core  10  is determined via the tumblers  12  falling into the stopping points  13  of the cylinder guide  14 . 
     In FIG. 3, as already mentioned, the overload situation of the device is shown. Burglary tool  35  engaging the cylinder core  10  has caused a forced rotation  36  of the cylinder core  10 . In this case the tumblers  12  are in locking engagement at the cylinder guide  14 , as illustrated in the lower half section of FIG.  2 . Upon forced rotation  36  the cylinder guide  14  is thus entrained by the cylinder core  10 . Between the slanted flanks of the two profiled elements  31 ,  32  a force acting axially against the spring load  34  results which lifts the cam(s)  31  of the stationary recess(es)  32 . The cam tip of the cam  31  comes to rest against an inner end face  27  on which it will glide upon further forced rotation  36 . Accordingly, the sliding sleeve  20  has been moved inwardly according to the profile height of  31 ,  32  by a travel stroke corresponding to the axial movement arrow  26  in FIG.  3 . Via the inner shoulder  25  of the sliding sleeve  20  and the counter shoulder  45  the turning member  40  has also been entrained by this travel stroke  26  and is positioned in the axially displaced “push position” illustrated by auxiliary line  53 ′ in FIG.  3 . This has two effects. 
     As can be seen in FIG. 3, the turning member  40  with its afore described coupling member  52  is disengaged relative to the counter coupling member  51  of the cylinder core  10 . The forced rotation  36  of the cylinder core  10  can thus not be transmitted onto the turning member  40 . Via the toothings  21  the sliding sleeve  20  will rotate because of the forced rotation  36  of the cylinder guide  41 ; however, this has no effect on the turning member  40 . The turning member  40  is only axially displaced by the travel stroke  26 . Its working arm  41  remains in the initial rotational position illustrated in FIG.  1 . An actuation of the working rod  43  extending to the lock thus is not taking place upon forced rotation  36 . 
     Moreover, manipulations for rotation  48  or  48 ′ of the working arm  41  of the turning member  40  in other ways is prevented by rotational blocking. In the push position  53 ′ the turning member  40  is aligned with surfaces at the housing, not illustrated in more detail, which prevent an adjustment of the working arm  41  by manipulations. 
     The inventive device is characterized by a surprisingly small axial construction length  28 . Such a minimal axial dimension is very favorable for the arrangement of the device in the interior of a vehicle door. This minimal axial size is firstly the result of the sliding sleeve  20  being positioned with substantial radial overlap on the cylinder guide  14  and thus in the axial section of the locking cylinder indicated by  29  in FIG. 2 where the last tumblers  12  are located. The sliding sleeve  20  is thus positioned in this inner control portion  29  between cylinder core  10  and cylinder guide  14 . However, the turning member  40  is also positioned in this control portion  29 . Accordingly, no or minimal axial space for the arrangement of the sliding sleeve  20  and of the turning member  40  is required. The space required for the arrangement of the axial coupling  50  is sufficient. 
     As shown in FIG. 1, the housing  17  can be a component of a bracket-shaped arrangement  37 . Supports  56 , illustrated in FIG. 2, are provided at the housing with which the housing or the bracket  37  can be supported on the inner surface of the door panel. 
     The afore described spring  33  can have spring legs  38 , as illustrated in FIG. 4, between which, on the one hand, a segment  54  of the turning member  40  and, on the other hand, a stationary segment  55  of the housing  17  are positioned. Accordingly, the afore described initial rotational position  49  of the turning member  40  of FIG. 1 is ensured. When the key  15  in the normal situation is released after rotation  18  or  18 ′ of FIG. 1, the spring  33  returns the turning member  40  by means of the spring legs  38 . Via the aforementioned coupling  50  this return movement results in a corresponding automatic return of the cylinder core  10  into its initial rotational position  19  of FIG.  1 .