Abstract:
A shifting device for the shifting of a transmission with a shifting shaft ( 2 ), upon which a multiplicity of shifting forks ( 8, 10, 12, 14 ) are placed in an axial, slidable manner for the carrying out of a shifting procedure, with a selection apparatus ( 28, 30, 32, 42, 44, 46 ) for the choice of the shifting fork from the multiplicity of shifting forks for the carrying out of the shifting procedure and with a blocking mechanism ( 52 ) for the prevention of the movement of non-chosen shifting fork. The blocking mechanism is to be found on an additional shaft ( 46 ) which is parallel to the shifting shaft, upon which the elements of the selection apparatus are provided. An actuator ( 60 ) exists which axially displaces the shifting shaft for the carrying out of the shifting procedure and another actuator ( 48 ) is provided, which causes to rotate the additional shaft for the choice of a shifting fork and for the prevention of the movement of non-chosen shifting forks.

Description:
[0001]     This application is a national stage completion of PCT/EP2004/010292 filed Sep. 15, 2004 which claims priority from German Application Serial No. 103 47 491.9 filed Oct. 13, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention concerns a shifting device.  
       BACKGROUND OF THE INVENTION  
       [0003]     For the shifting of a transmission, especially where vehicles are concerned, a shifting device is provided in the transmission, which aids in engaging individual gear stages. As this is done, it is possible that parts of the shifting device can be manually moved by the vehicle driver or as an alternate, this function may be carried out by actuators, which are energized by at least one auxiliary power medium to execute the necessary movements of parts of the shifting device required for the shifting of gear stages.  
         [0004]     DE-A1 198 43 584 discloses a shifting apparatus for a multi-stage shifting transmission wherein, on a single shifting shaft, a multiplicity of shifting forks (or shifting levers (hereinafter “shifting forks”) are placed. A means of selection enables the choice of one of the shifting forks by a turning of a shifting shaft. Alternately, if the shifting shaft is axially displaced, then the respectively selected shifting fork is activated to carry out the shifting action. A blocking shaft, placed parallel to the shifting shaft, is likewise rotated upon the turning of the shifting shaft and thereby, in its function as a blocking shaft, employing the prevention of movement of such shifting forks which were not chosen as indicated above. In spite of this well functioning shifting apparatus, problems still remain with regards to a lock-up of a shifting apparatus in an operation including actuators.  
         [0005]     The purpose of the invention is to make a shifting apparatus known, which obviates the presently existing problems and which enables the functioning of actuators in a simple manner.  
       SUMMARY OF THE INVENTION  
       [0006]     According to the invention, a shifting device for the shifting of a transmission possesses a shifting shaft upon which a multiplicity of shifting forks are placed in an axial, slidable alignment for the execution of shifting procedures. Likewise, a selection apparatus for the choice of one of the shifting forks out of the multiplicity of shifting forks and blocking disks for the prevention of an axial motion of the non-chosen shifting fork are provided. To accomplish this, the blocking apparatuses are placed on an additional shaft; essentially in parallel alignment with the shifting shaft. A first actuator is provided which axially displaces the shifting shaft for the execution of the of the shifting procedure. Additionally, elements are provided for the selection apparatus on the additional shaft. A further actuator is, likewise, provided which turns the additional shaft for the choice of a shifting fork and for the prevention of the movement of non-selected shifting forks.  
         [0007]     In an advantageous embodiment, the elements of the selection apparatus make use of ring-shaped engagement units, specifically for each shifting fork. The ring-shaped engagement units are axially affixed and slidable along the shifting shaft to enable the execution of the shifting procedure. The ring-shaped engagement units are rotatable about the shifting shaft for the selection of one of the shifting forks and possess elements of a come-along apparatus, which enable an axial sliding of the ring-shaped engagement unit because of the axial motion of the shifting shaft in the shifting procedure.  
         [0008]     Another advantageous embodiment demonstrates, that the ring-shaped engagement units on the shaping fork co-act with a blocking mechanism for prevention of axial motion of non-chosen shifting forks on the shifting shaft.  
         [0009]     In a particularly advantageous embodiment, elements of the blocking mechanism incorporate rotatable blocking disks, the circumferences of which extend into an axial movement area of the ring-shaped engagement units. The contour of a blocking disk is designed in such a manner that the eliminated zone of the blocking disks, which is in segmental shape, allow an axial movement of the ring-shaped engagement units on the shifting shaft, while other areas of the blocking disks are appropriate for preventing an axial movement of the ring-shaped engagement units.  
         [0010]     Advantageously, recesses are present on the ring-shaped engagement units, which recesses co-act with projections on the shifting shaft. The projections penetrate the recesses, if the associated shifting fork is not engaged and further the projections slide the ring-shaped engagement units axially if the selected shifting fork is in a displaced position which changes the gear stage.  
         [0011]     Advantageously, the elements of the selection apparatus exhibit complementary toothings which mesh and enable a rotation of the elements of the selection apparatus in relation to one another. In this operation, only parts of the ring-shaped engagement unit possess toothing due to their formation.  
         [0012]     Representing one embodiment, an area of a section in a blocking disk can exhibit a toothing, which can mesh into the toothing of a ring-shaped engagement unit.  
         [0013]     An inventive embodiment would be especially advantageous, if the elements for the carrying out of shifting procedure were made of steel or aluminum, while the elements of the selection apparatus and of the blocking disks are constructed of aluminum or plastic or again from a combined compounding.  
         [0014]     In the case of a particularly advantageous design of the invention, a transmission can be provided for ratio control of rotation of the shifting shaft actuator in an axial movement thereof.  
         [0015]     Advantageously, at least one actuator is provided, which is designed to operate electromechanically, pneumatically or hydraulically. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     The invention will now be described, by way of example, with reference to the accompanying drawings in which:  
         [0017]      FIG. 1  is a first shifting device with individual elements, and  
         [0018]      FIG. 2  is a second presentation of detailed elements of a second embodiment of the shifting device.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]     According to  FIG. 1 , four shifting forks, namely  8 ,  10 ,  12  and  14  are placed on a shifting shaft  2 . Shifting shaft  2  is axially slidably supported in bearings  4  and  6  which, in turn, are affixed in a housing (not shown) of the shifting transmission. The shifting forks  8 ,  10 ,  12  and  14  are installed so as to be moveable in relation to the shifting shaft  2 . For the purposes of clarity of illustration and better understanding, not all possible shifting forks are shown on the shaft  2 . Further, individual elements of the shifting device are presented in a somewhat exploded view separate from the shifting shaft. In a completed assembly, however, all shifting forks are located in a manner similar to that of shifting fork  12 , which is shown on the shifting shaft  2 . Presented in  FIG. 1  is an arrangement of the three shifting forks  8 ,  10  and  12  of the shifting shaft  2 , while the shifting fork  14 , is placed in this arrangement underneath the shifting shaft  2 . The following components, described here, serve analogously for every shifting fork, if these also can be described and explained by a single typical shifting fork because of common characteristics.  
         [0020]     On the shift fork  10 , the shifting shaft  2  possesses projections in the form of two pins  16  and  18 , which enclose the shifting fork  10  between them. Between the pins  16  and  18  and the shifting fork  10  is to be found at each side of the shifting fork  10 , one sheet metal, contoured disk  20  and  22 . The contoured disks  20  and  22  are bounded on their inner circumference by similar openings  24  through which the pins  16  and  18  can be axially inserted, respectively. The remaining area between each of the openings  24 , bounded by the inner circumference of the contoured disk  20  and  22  is able, by a mutual turning of the contoured disk  20  and  22  on the shifting shaft  2  with the aid of the pins  16  and  18 , to make a mutual overlap. Thereby, in a case of an axial movement of the shifting shaft  2  over the pin  16  and  18  wherein the contoured disk  20  and/or  22  and even the shifting fork  10  is axially displaced and a gear stage can be engaged in the transmission.  
         [0021]     In order to turn the contoured disk  20  and  22  on the shifting shaft  2 , this disk possesses on a contour surface (hereinafter “contour  26 ”) on its outer circumference which co-acts with a complementary contour on a ring-shaped engagement unit  28  and/or  30  and forms a turn-fast connection between the contoured disks  20  and  22  and the ring-shaped engagement unit  28  and/or  30 .  
         [0022]     Such a device, basically including a ring-shaped engagement unit  32 , is pictured in its location on the shifting fork  12 , wherein currently two single, ring-shaped engagement units are combined to form one component. In order to enable a rotation of the ring-shaped engagement unit  32  on the shifting shaft  2 , without interfering with the arms of the shifting fork  12 , the ring-shaped engagement unit  32  is furnished with a recess  34 . On the outer circumference of the ring-shaped engagement units  28 ,  30 ,  32  is provided a toothing  36 , which can stand in engagement with corresponding toothings  38 ,  40  on gears  42  and  44 . This is correspondingly valid for all shifting fork  8 ,  10 ,  12  and  14 . The gears  42  and  44  are turn-fast affixed on a shaft  46 , which is essentially aligned parallel to shifting shaft  2 . The shaft is rotated by an actuator  48  such as, for example, an electric motor through a ratio train with a toothing  50 . The arrangement, however, can also be so designed so that the actuator  48  is directly bound to the shaft  46  without the ratio train. Laterally, located to the gears  42  and  44  is respectively a blocking disk  52  of a blocking apparatus, which does not possess a complete, circular circumference, but has a recess in the form of the circular segment  54 .  
         [0023]     The blocking disks  52  of the differing shifting forks  8 ,  10 ,  12 ,  14  also exhibit such segmental cutoffs at various positions on their circumferences, so that the two blocking disks  52  always present the same cutoffs to one shifting fork, while otherwise, the cutoffs on the blocking disks  52  of the other shifting forks are provided for rotation about the axis of the common shaft  46 . The blocking disks  52  co-act with the ring-shaped engagement units  28 ,  30 ,  32  to form the blocking apparatus, for example by the edges of the toothings of the ring-shaped engagement unit  28 ,  30 ,  32 . In this way, the blocking disks  52  restrain the ring-shaped engagement units  28 ,  30 ,  32  and therewith also hold the shifting forks in their axial positions on the shifting shaft  2  and permit only an axial movement of the currently selected shifting fork, in the area of the segment  54  on the blocking disk  52 .  
         [0024]     The shifting shaft  2  is connected to an actuator  60  by way of a transfer block  56  having a ball-joint drive  58  which is, in turn, connected to an electric motor. Instead of the ball drive  58 , this power transfer can be accomplished by a gear drive (not shown). The illustrated actuators  48  and  60  are shown in  FIG. 1  as being co-axial, or axis parallel to the shaft of  2  and  46  which is to be placed in motion. By way of an appropriate directive gear drive, the possibility exists that an assembly, which stands at an angle to the shaft, may also be installed, for instance, at a right angle.  
         [0025]     In order to shift a gear stage, it is necessary that the shifting fork  8 ,  10 ,  12  or  14  be pushed axially. The shifting fork  8 , 10 , 12  and  14  are freely supported on the shifting shaft  2  and for engagement, these must be axially shape-fit with the shifting shaft  2  by the pins  16 ,  18  and the contoured disk  20 ,  22 . The toothed ring-shaped engagement units  28 ,  30 ,  32  are rotated by the shaft  46 , which shaft is provided with gears  42 ,  44 . The shifting shaft  2  moves itself for the engagement of the gear stages only in the axial direction. The selective preliminary choice of the gear stage to be shifted is carried out in that the contoured disk  20 ,  22  are rotated by the ring shaped engagement units  28 ,  30 ,  32  which encompass them and thereupon close a discrete angle. Analogous to this angle, the internal opening  24  in the contoured disks  20 ,  22  are provided which, by way of the non-shifted gear stages, as soon as the shifting shaft moves itself, lead to an engagement of the pins  16  and/or  18  and thereby to no correspondingly movement contoured disk of the corresponding shifting fork. In the case of the fork to be shifted, which is in this position, its necessary contoured disk  20  and/or  22  lacks the internal opening  24 , so that the fork undergoes an axial movement and the desired gear stage is engaged. In each of the different selection positions, there is always one contoured pair  20 ,  22  without internal openings  24  in overlap with the pins  16 ,  18  so that an action can be initiated. All of the rest of the ring-shaped engagement units are coinciding with the internal openings  24  with the appropriate pins  16 , 18  and no axial motion can occur.  
         [0026]      FIG. 2  shows a shifting device, according to  FIG. 1 , in a partially released condition. In this case, the segments  54  on the blocking disks  52  are provided with a toothing, so that the blocking disks in the non-blocking angular position can mesh into the outer toothing of the appropriate ring-shaped engagement unit  28 ,  30 . The ring shaped engagement units  28 ,  30  are designed here as separate components so that the necessity of the formation of toothing  36 , as is required with the ring-shaped engagement unit  32 , is eliminated.  
         [0027]     Since the elements taking part in the selection of the shifting fork to be shifted are exposed only to comparatively small forces, the design of these elements finds that a construction material of a lesser structural strength will suffice. Such a material would be plastic or a metal other than steel, but possibly including aluminum. Aluminum, in comparison to steel, is a low strength metal and plastic, both in comparison to steel and aluminum, is in turn a material of lesser strength.  
         [0028]     Appropriate for a plastic construction, in the present embodiment, is the ratio determining stage with the toothing  50  to which can be added the shaft  46  and the gears  42 ,  44  and the blocking disks  52  which are on the shaft  46 . Likewise, the ring-shaped engagement units  28 ,  30 ,  32  can be made of plastic, both in the assembled state as well as in the separate part versions. The elements of plastic can be pre-manufactured and require no or only minuscule reworking. This is thereby essentially cheaper than the construction materials for systems built of greater structural strength. A further advantage can be found where the elements made of plastic produce a lesser generation of noise, since plastic essentially possesses a noise dampening function. Known to the present time, and generally criticized noise problems, such as rattling in the transmission and scraping of gears can be avoided by the above system.  
       REFERENCE NUMERALS  
       [0000]    
       
           2  shifting shaft  32  ring-shaped engagement unit  
           4  bearing  34  recess  
           6  bearing  36  toothing  
           8  shifting fork  38  toothing  
           10  shifting fork  40  toothing  
           12  shifting fork  42  gear  
           14  shifting fork  44  gear  
           16  pin  46  shaft  
           18  pin  48  actuator  
           20  contoured disk (externally)  50  toothing  
           22  contoured disk (externally)  52  blocking disk  
           24  internal opening of  20 ,  22   54  segment  
           26  contour at outer circumference  56  transfer block  
           28  ring-shaped engagement unit  58  universal ball-joint  
           30  ring-shaped engagement unit  60  actuator