Abstract:
The present invention relates to a blocking mechanism for a parking lock of a shaft in a motor vehicle. The blocking mechanism includes a pawl pivotable about a pivot axis and which, in a blocked position, engages into at least one latch cut-out of a ratchet wheel connected to the shaft. The blocking mechanism includes an actuating mechanism having an actuating device for moving an actuation slider. The pawl is pivotable by a movement of the actuation slider. The actuation slider includes a first U-shaped component and a second U-shaped component which each have two side sections and a transverse section connecting the side sections. The first component and the second component are plugged into one another in opposite directions such that the transverse section of the one component at least partly closes the open end of the U shape of the component and vice versa.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit and priority of German Patent Application No. 10 2011 018 862.2 filed Apr. 28, 2011 and U.S. Provisional Application No. 61/367,170 filed Jul. 23, 2010. The entire disclosures of the above-applications are incorporated herein in their entirety by reference. 
     FIELD 
     The present invention relates to a blocking mechanism for the rotationally fixed locking of a shaft. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Such blocking mechanisms are used, for example, as parking locks to secure a motor vehicle when stationary. For this purpose, for example, a transmission shaft of a motor vehicle is rotationally fixedly locked. Parking locks are in particular used in motor vehicles having automatic transmissions and/or in hybrid vehicles or electric vehicles. 
     On the actuation of the parking lock, substantial loads on the components involved can occur. If the vehicle is still rolling, for example, on the actuation of the parking lock, a torque is applied at the shaft of the vehicle to be locked. The components of the parking lock have to take up the forces related thereto to effect the reliable locking of the shaft. 
     SUMMARY 
     This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features. 
     It is therefore an object of the present invention to provide a blocking mechanism which can take up high loads and which can at the same time be manufactured inexpensively and which has a compact construction. 
     The blocking mechanism in accordance with the invention has a pawl which is pivotable about a pivot axis and which, in a blocked position, engages into at least one latch cut-out of a ratchet wheel connected to the shaft. An actuating mechanism is furthermore provided which has an actuating device for moving an actuation slider. The pawl is pivotable by a movement of the actuation slider. The actuation slider includes a first U-shaped component and a second U-shaped component which each have two side sections and a transverse section connecting the side sections. The first component and the second component are plugged into one another in opposite directions such that the transverse section of the one component at least partly closes the open end of the U shape of the other component and vice versa. 
     In other words, the actuation slider has at least two components which are each designed in U shape. They can be produced separately in a simple manner. The installation of the actuation slider is possible in a simple manner since the first component and the second component are only plugged into one another in the simplest case. For this purpose, for example, the first U-shaped component is placed onto the limbs of the second U-shaped component formed by the side sections such that the transverse section of the first component at least partly covers the open end of the U shape of the second component. In this state, the transverse section of the two components can extend parallel to one another, for example, with their spacing being defined by the length of the side sections of at least one of the components. The side sections in particular contact one another in parallel at least sectionally in the installed state of the actuation slider. 
     The above-described embodiment of the actuation slider not only allows a simple installation, but also results in a stable construction of the actuation slider since the U-shaped components are mutually stabilized by the plugging into one another. 
     The first and/or the second component can be made in one piece to keep the manufacturing costs of the blocking mechanism low. Both components are preferably made in one piece. 
     In accordance with an embodiment which is favorable from a technical manufacturing aspect and which moreover provides a high stability of the actuation slider, the side sections and the transverse section each include an angle of approximately 90.degree. A body having a substantially rectangular shape is produced by the plugging into one another of the two components in opposite directions—at least in a plane defined by the U shapes of the components. 
     The components can generally have similar longitudinal extents in the longitudinal direction of the U shape. Provision can, however, also be made that one of the components has an elongated U shape, whereas the other component has a comparatively “flat” U. One of the two components, for example, forms a base body by its U shape which is closed by the other component having a bracket-like U shape—for instance, a shape which has comparatively short side sections in comparison with the length of the transverse section. 
     The first component in particular completely engages around the second component in the longitudinal extent of the actuation slider. I.e. one of the components is—at least viewed in the longitudinal direction of the actuation slider—arranged in the interior of the U-shape of the first component. 
     The first and the second components can be fixedly connected to one another by a clamping effect exerted by one of the components on the other component. Provision can additionally or alternatively be made that the first component and the second component are fixedly connected to one another by stamping. Other kinds of connection, for example weld connections, can likewise be used. 
     To be able to guide the actuation slider reliably during the movement and/or to be able to restrict its movement, a guide rail can be provided which cooperates with at least one guide element formed at the first component and/or at the second component. The guide rail is in particular arranged spatially fixedly and can act as a counter-bearing at which the actuation slider is supported during its movement to effect a pivoting of the pawl. The guide rail is in particular arranged at the side of the actuation slider remote from the pawl. 
     The guide rail can have a side wall section which extends at right angles from a section of the guide rail supporting the actuation slider in the direction toward the pawl in order thus also to provide a guidance in the lateral direction. The side wall section can also serve for stiffening the guide rail and/or for its fastening. 
     The at least one guide element at at least one of the components is in particular provided at one of the side sections. It can also be arranged at a prolongation which is provided at an end of at least one of the side sections remote from the transverse section. The guide element, for example, engages laterally around the guide rail sectionally. The guide element can be made in L-shape or hook-shape for this purpose. 
     The guide element can be guided at least partly in a guide device of the guide rail. The guide device is, for example, a recess, a cut-out, an elongate hole, a groove or a slit. It is understood that the guide element has a corresponding complementary design. 
     In accordance with an embodiment, the actuation slider cooperates via at least one roller with a control cam formed at the pawl. An intermediate roller can additionally be provided which rolls off at the guide rail on a movement of the actuation slider and which is in contact with the roller cooperating with the control cam. The roller cooperating with the control cam and/or the intermediate roller are in particular supported in the first component and/or in the second component. The support can take place, for example, by an elongate hole or a U-shaped slit formed at the first component and/or at the second component. 
     The actuating device can include an eccentric part or a lever which converts a rotary movement into a pushing movement acting on the actuation slider. 
     A damping device via which the actuating device acts on the actuation slider can be provided to set the latching characteristics of the pawl. The damping device is a spring device, for example. The damping device also prevents damaging tensioning of the involved components on an “out-of-mesh” position of the pawl and of the ratchet wheel which prevents a latching of the pawl into the blocking position. In this situation, the damping device at least partly takes up the actuation movement produced by the actuating device and outputs it again when the above-described “out-of-mesh” position is cancelled again and a latching is again possible. 
     The actuating device can be pivotally connected to a guide bar which projects through an opening in the transverse wall of one of the components into the interior of the actuation slider to provide additional guidance of the movement of the actuation slider. 
     Further embodiments of the invention are set forth in the claims, in the description and in the enclosed drawings. 
    
    
     
       DRAWINGS 
       The present invention will be described in the following purely by way of example with reference to advantageous embodiments and to the enclosed drawings. There are shown: 
         FIG. 1  illustrates an embodiment of the blocking mechanism in accordance with the invention; 
         FIGS. 2   a - 2   d  are different perspective views of an actuation slider associated with the blocking mechanism shown in  FIG. 1 ; 
         FIG. 3  illustrates a second embodiment of the blocking mechanism in accordance with the invention; 
         FIGS. 4   a - 4   d  are different perspective views of a second embodiment of the actuation slider associated with the blocking mechanism shown in  FIG. 3 ; 
         FIGS. 5   a  and  5   b  illustrate a third embodiment of the blocking mechanism in accordance with the invention; and 
         FIGS. 6   a  and  b  are different perspective views of the third embodiment of the actuation slider associated with the blocking mechanism shown in  FIGS. 5   a  and  5   b.    
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a parking lock  10  which is provided, for example, for locking an intermediate shaft, not shown, of a transmission of a motor vehicle which is connected to an electric motor of an electric vehicle or of a hybrid vehicle. It is understood that the parking lock  10  can also be used in other application areas such as in a conventional automatic transmission. The parking lock  10  serves for the rotationally fixed securing of the intermediate shaft. Ultimately, it is rotationally fixedly coupled to a transmission housing, which has the result that the transmission is blocked and that the vehicle is secured in a parked state. 
     The parking lock  10  includes a ratchet wheel  12  which is connected to the intermediate shaft directly or indirectly via a damping element—for example a rubber component or a plastic component, a torsion spring or similar—for damping peak loads. A blocking position for the parking lock  10  is shown in  FIG. 1  in which a pawl  14  engages into latch cut-outs  16  of the ratchet wheel  12 . The pawl  14  is arranged pivotably about a pivot axis  18 . 
     An actuating mechanism  20  is provided to produce a pivoting movement of the pawl  14 . The actuating mechanism  20  includes a latching disk  22  which acts as an eccentric part and which is pivotable about an actuation shaft  24 , for example, by means of a Bowden cable. The latching disk  22  has latch cut-outs  24   a  into which a latching mechanism  24   b —it e.g. includes a spring-loaded ball—engages to define specific positions of the parking lock  10 . 
     The latching disk  22  is connected to an actuating bar  26  which, on the one hand, represents a guide for an actuation slider  28  for pivoting the pawl  14  and, on the other hand, forms an abutment for a spring  30 . A rotational movement of the shaft  24  is converted into a movement in translation of the actuation slider  28  by the latching disk  22 , the bar  26  and the spring  30 . 
     The actuation slider  28  supports a roller  32  which cooperates with a control cam  34  which is provided at a side  12  of the pawl  14  remote from the ratchet wheel  12 . A movement in translation of the actuation slider  28  from an unblocked position into the blocking position shown in  FIG. 1  results in a rolling off of the roller  32  on the control cam  34  which becomes steeper in its part at the left in  FIG. 1 . Since the actuation slider  28  can only be moved in translation by the effect of a spatially fixedly arranged guide rail  36 , the movement of the actuation slider  28  to the left effects a pivoting of the pawl  14  until it engages into one of the cut-outs  16  of the ratchet wheel  12 . 
     For an unblocking of the parking lock  10 , the actuation slider  28  is moved to the right out of the position shown in  FIG. 1 . A restoration spring  30 ′ which is supported at a housing component, not shown, urges the pawl  14  away from the ratchet wheel  12  so that it is released again. 
     The guide rail  36  has a shape of a U lying on its side in its region at the right in  FIG. 1 . In the left region, the limb of the U facing the pawl  14  is missing. The guide rail  36  serves for the guidance of the actuation slider  28  and provides that it only carries out the movement in translation required for the actuation of the parking lock  10 . It also represents a kind of counter-bearing at which the actuation slider  28  is supported, while the roller  23  rolls off at the control cam  34 . An intermediate roller  38  which can hardly be recognized in FIG.  1  is provided to reduce the friction between the actuation slider  28  and the guide rail  36 . 
     The guidance of the actuation slider  28  in the guide rail  36  takes place via guide noses  40  which cooperate with a limb of the guide rail  36  facing the pawl  14  or with the limb disposed opposite this limb. A slit  42  is formed at the upper side of the guide rail  36  and receives a guide element explained in more detail in the following. 
       FIGS. 2   a  to  2   d  show the actuation slider  28  in different perspective views. The actuation slider  28  includes two components  44 ,  46  which each have the shape of a U in a plan view—i.e. in a direction perpendicular to the direction of translation of the actuation slider  28  and perpendicular to an axis of rotation of the ratchet wheel  12  or at the pivot axis  18 . The component  46  is inserted into the component  44  in the opposite direction so that the Us close one another. Together, the components  44 ,  46  form a box-shaped assembly which—viewed in a plan view—has a rectangular base shape. 
     The components  44 ,  46  each have side sections  44   a  or  46   a  which are each connected to one another by a cross-section  44   b  or  46   a . In an installed state, the side sections  44   a ,  46   a  contact one another in parallel, whereas the transverse sections  44   b ,  46   b  close the open end of the U shape of the respective other component  46  or  44 . 
     In an installed state, the component  44  engages around the component  46  in the longitudinal direction of the actuation slider  28 . Figuratively speaking, the U shape of the component  44  completely receives the U shape of the component  46 . The two components  44 ,  46  are reliably connected to one another by a clamping effect which is exerted by the component  44  on the component  46 . 
     The side sections  44   a  each have prolongations  48  at the end remote from the transvers section  44   b  at which prolongations the guide noses  40  already named above are formed. Furthermore, one of the side sections  44   a  has a guide projection  50  which engages into the slit  42  already described in connection with  FIG. 1  to guide the actuator slider  28  during the movement in translation and to limit the movement in translation. 
       FIG. 2   c  shows the actuation slider  28  in an exploded view, whereby the view of the roller  32  and of the intermediate roller  38  is improved. They are supported in U-shaped slits  52  provided in the slide sections  46   b  of the component  46 . The component  46  has cut-outs  54  which serve for the guidance of a transverse bar  54 ′ connected to the actuating bar  26  (see  FIG. 1 ). 
     An opening  56  can be recognized in  FIG. 2   d  through which the actuating bar  26  projects into the interior of the rectangular base body of the actuation slider  28  formed by the components  44 ,  46  to exert a guiding function. 
     It is understood that the most varied embodiments of the actuation slider  28  and of the guide rail  36  can be imagined which likewise enable a reliable actuation of the parking lock  10 . 
     A further embodiment  20 ′ of the actuating mechanism is shown by way of example in  FIG. 3 . The pawl  14  and the elements associated with the latching disk  22 , including the actuating bar  26  and the spring  30  are substantially the same as the corresponding components shown in  FIG. 1 . The actuating mechanism  20 ′, however, includes an actuation slider  28 ′ which has a somewhat different design. The actuation slider  28 ′ admittedly likewise has two U-shaped components  44 ′,  46 ′; however, the component  44 ′ does not completely engage around the component  46 ′, as can in particular be seen from  FIGS. 4   a  to  4   d . The side sections  44   a ′ of the component  44 ′ are made substantially shorter than the side sections  46   a ′ of the component  46 ′. In addition, the rollers  32 ,  38  in the actuation slider  28 ′ are, unlike the embodiment of the actuation slider  28 , arranged in elongate holes  60  formed in the side sections  46   a ′ of the component  46 ′. 
     On the installation of the actuation slider  28 ′, the component  44 ′ is placed onto the open end of the component  46 ′, with plug-in elements  58  of the component  46 ′ penetrating into corresponding openings (not shown) of the component  44 ′. The connection can be secured in that a stamping process is carried out. 
     The guidance of the actuation slider  28 ′ by a guide rail  36 ′ takes place by means of guide hooks  62  which are arranged at the side sections  46   a ′ and which partly engage around the guide rail  36 ′ at both sides. In this respect, they are arranged in grooves  64  of the guide rail  36 ′ shaped in a complementary manner. 
     An embodiment  28 ″ of the actuation slider is shown in  FIGS. 5   a  and  5   b  which is to a large extent, in particular with respect to the embodiment of the U shape of the components  44 ′,  46 ′, substantially the same as the actuation slider  28 ′, as in particular  FIGS. 6   a  and  6   b  show. The guidance of the actuation slider  28 ″, however, takes place in a somewhat different manner. Only one guide hook  62  is provided which laterally engages around the guide rail  36 ″. A guide groove  64  is not provided. The second guide hook  62  of the actuation slider  28 ′ is replaced with a guide projection  50 ′ which engages into a slit  42 ′. It is thereby possible to provide the guide rail  36 ″ with a side wall  66  which extends perpendicular to the direction of the movement in translation of the guide slider  28 ″ and perpendicular to the pivot axis  18  of the pawl  14 . This increases the stability of the guide rail  36 ″ and facilitates their fastening. In addition, the side wall  66  provides an additional lateral guide for the actuation slider  28 ″. 
     REFERENCE NUMERAL LIST 
     
         
         
           
               10  parking lock 
               12  ratchet wheel 
               14  pawl 
               16  latch cut-out 
               18  pivot axis 
               20 ,  20 ′ actuating mechanism 
               22  latching disk 
               24  actuation shaft 
               24   a  latch cut-out 
               24   b  latching mechanism 
               26  actuating bar 
               28 ,  28 ′,  28 ″ actuation slider 
               30  spring 
               30 ′ restoration spring 
               32  roller 
               34  control cam 
               36 ,  36 ′,  36 ″ guide rail 
               38  intermediate roller 
               40  guide nose 
               42 ,  42 ′ slit 
               44 ,  46 ,  44 ′,  46 ′,  44 ″,  46 ″ component 
               44   a ,  46   a ,  44   a ′,  46   a  side section 
               44   b ,  46   b  transverse section 
               48  prolongation 
               50 ,  50 ′ guide prolongation 
               52  slit 
               54  cut-out 
               56  opening 
               58  plug-in element 
               60  elongate hole 
               62  guide hook 
               64  groove 
               66  side wall