Patent Document

[0001]     This application is a national stage completion of PCT/EP2004/005331 filed May 18, 2004 which claims priority from German Application Serial No. 103 26 677.1 filed Jun. 13, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention concerns a planetary transmission.  
       BACKGROUND OF THE INVENTION  
       [0003]     Commercial vehicles with a large number of gear positions frequently possess an auxiliary range gear train, which acts on the main drive shaft and engages itself with the existing gear stages. With such an auxiliary range gear train, it is possible that the total ratio of the main transmission is increased, since all gear stages of this main transmission can be employed along with each gear stage of the auxiliary range gear train, and in at least one gear stage of the auxiliary range gear train, the ratio of the gear stages of the main transmission are adjusted to be either under or over their designed ratio.  
         [0004]     An auxiliary range gear train for automobiles has been made known by DE 41 21 709 A1. With a planet gear arrangement of this kind installed following the main transmission, the possibility exists, of operating the motor vehicle within the framework of the gear stages of its main transmission, respectively, in two different speed ranges. When shifted into a first, slow ratio stage of the auxiliary range gear train, the internal gear of the planetary transmission is coupled by means of a clutch to the transmission housing so that the output shaft of the auxiliary range gear train possesses a lesser speed of rotation than does the output shaft of the main transmission. In a second shifting stage, a direct through-drive from the output shaft of the main transmission onto the output shaft of the auxiliary range transmission is effected, whereby a clutch establishes a direct connection between the output shaft of the main transmission and the output shaft of the auxiliary range gear train. The shifting mechanism to carry this out is expensive in its design and fabrication.  
         [0005]     As a further development, DE 198 51 895 A1 teaches an auxiliary range gear train constructed as a planet gear system. In this case, the internal gear of the planet gearing is non-rotatably bound to the housing of the transmission. The sun gear of the planetary transmission is coaxially aligned to the output shaft of the main transmission and, compared to the output shaft of the main transmission, it is free in its rotation. For the construction of a step-down ratio between the output shaft of the main transmission and the output shaft of the auxiliary range gear train, the sun gear can be non-rotatably bound with the output shaft of the main transmission. Once again, this design is complex, expensive in design and time consuming. Furthermore, the individual components raise problems with regard to support.  
         [0006]     Thus the invention has the purpose of improving a planetary transmission and especially improving the component structure of the bearing support.  
       SUMMARY OF THE INVENTION  
       [0007]     A planetary transmission comprising an internal gear, a sun gear and a planet carrier, upon which at least one planet gear is supported, possesses a clutch featuring a sliding sleeve which, in one stage suitable for one gear position, establishes a direct connection between a shaft driving the planetary transmission and an output shaft of the planetary transmission. In a shifting position, other than that above, a speed of rotation change is effected between the driving shaft and the output shaft of the planetary transmission. The planet gear is so mounted on the bearing of the planet carrier, that upon a shifting from one given stage into a respective successive stage, the planet gear on the planet carrier is axially displaceable. Normally, in a planetary transmission of this design, three or five planet gears are to be found which are distributed about the circumference thereof.  
         [0008]     Advantageously, relative to the internal gear and to the sun gear, the planet gear is axially affixed so that an axial sliding of the planet gear simultaneously enables, an axial sliding of the internal gear and the sun gear.  
         [0009]     In the case of a particularly advantageous embodiment, the planet gear experiences a smaller return displacement than does the sliding sleeve, when sliding from the one gear position into the respective next position, which impels the planet gear.  
         [0010]     In one advantageous embodiment, the sliding sleeve has the capability of moving the sun gear axially and thereby the planet gear on the planet carrier, likewise, slides axially.  
         [0011]     One design example of the present invention shows the sun gear accompanied by a pressure bolt, which coacts with the sliding sleeve, even though, in another embodiment, the sliding sleeve and the sun gear are constructed together as a one-piece component.  
         [0012]     Advantageously, both the internal gear as well as the sun gear possess toothed pressure compensators which adjoin the planet gear.  
         [0013]     In another embodiment, the sliding clutch has a neutral position, which lies between the two shift-positions and by which the output shaft of the planetary transmission is not driven.  
         [0014]     A further advantageous embodiment of the invention shows the planet gear on the planet carrier running in a roller bearing. Advantageously, the roller bearing has a multi-row design. The combined relative support of the sun gear plus the driving gear of the planetary transmission, likewise, form a possibility for another embodiment design.  
         [0015]     The planetary transmission presents itself especially advantageous here as an auxiliary range gear of a motor vehicle, which is designed as a torque transmitting drive string interlocked to a main transmission. By this addition, the output shaft of the main transmission forms the driving shaft of the planetary gear transmission.  
         [0016]     Likewise, as an exceptionally advantageous embodiment, the main transmission comprises two countershafts and one floating principal shaft supported between the countershafts, which serves as an output of the main transmission which, in turn, forms the input shaft of the planetary gear transmission and which, at its end, is supported by the sun gear of the planetary transmission.  
         [0017]     Advantageously, the bearing of the end of the main drive shaft includes a pin with a slotted profile. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     The invention will now be described, by way of example, with reference to the accompanying drawings in which:  
         [0019]      FIG. 1  is a planetary transmission with a first shifting apparatus in a neutral position;  
         [0020]      FIG. 2  is the shifting apparatus according to  FIG. 1  in a first gear position;  
         [0021]      FIG. 3  is the shifting apparatus according to  FIG. 1  in a second shifting position; and  
         [0022]      FIG. 4  is a planetary transmission with a second shifting apparatus in a neutral position. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     In a transmission housing  4  of a vehicle, a shifting transmission  2  possesses a main transmission  6  and thereon, an auxiliary range gearing in the form of a planetary transmission  8 . The planetary transmission  8  includes a planet carrier  10 , which is designed as a common component with an output drive  12  of the shifting transmission  2 . About the output drive shaft  12  is a flange  14  and the output drive  12  is supported by a bearing arrangement  16  in the transmission housing  4 . The planet carrier  10  has several, evenly distributed planet bolts  18  about its circumference. Of these planet bolts  18 , in the illustrations, only one bolt is shown. On the planet bolt  18 , supported by a roller bearing  22 , is shown only one planet gear  20 . Distributed orderly about the circumference of the planet carrier  10  would normally be three or five such planet gears  20 . The roller bearing  22  is constructed as a double row, cylindrical roller bearing or an equivalent needle bearing. The planet gear  20  is externally encompassed by an internal gear  24 , which exhibits a shift toothing  26 . The shift toothing  26  engages itself in a base plate  30 . The base plate  30  is held in non-rotatable fashion in the transmission housing  4 . In this arrangement, the base plate  30  can be cast into the transmission housing  4 , or be clamped between the individual elements of the transmission housing  4  as a separate plate. A shaft  32  serves as the possible drive of an auxiliary power take-off and is supported by a bearing arrangement  34  in the transmission housing  4 .  
         [0024]     The planet carrier  10  has a projection  36  located on that side of the planetary transmission  8  which is opposite to the output drive shaft  12 , on which the planet carrier  10  is held by a roller bearing  38  in the transmission housing  4 . Also, a countershaft  40  of the main transmission  6  is supported in a bearing arrangement  42  in the transmission housing  4 . A main drive shaft  44  of the main transmission  6  carries a toothed gear  46  on its end for the reverse gear ratio. The gear  46  is placed on the main drive shaft  44  with allowance for small radial play. This light play is typical for a shifting transmission with a power branching into two countershafts. At the end of the main drive shaft  44  is provided a pin  45 , which exhibits a slotted profile. The pin  45  includes a pressure bolt  48 , which is pressed in an outward direction by a spring  50 . On this account, the pressure bolt  48  extends itself through a sun gear  52  of the planetary transmission  8 , which has been placed on the pin  45  of the main drive shaft  44 , whereby the main drive shaft  44  bases itself in the sun gear  52 . Between the sun gear  52  and the output drive shaft  12 , i.e., the planet carrier  10 , is placed a shell  54  with a disk. This arrangement allows a common fitting and a mutual sliding between the sun gear  52  on the output drive shaft  12 . Accordingly, the speed of rotation of the sun gear  52  and that of the output drive shaft  12  need not be the same.  
         [0025]     On the sun gear  52  are two toothed pressure compensators  56  and  58 , which restrict any axial movement of the planet gear  20  relative to the sun gear  52 . However, in this connection, a contact of the planet gear  20  against the toothed pressure compensators  56 ,  58  is allowed, in order to pick up an axially directed force, which said force results from inclined toothing of the planetary transmission  8 . Two additional toothed pressure compensators  60  and  62  are placed radially within the internal gear  24  and again permit a contacting meeting of the planet gear  20 . The two toothed pressure compensators  60  and  62  restrict an axial movement of the planet gear  20  relative to the internal gear  24 . By way of this arrangement of the toothed pressure compensators  56 ,  58 ,  60  and  62 , the sun gear  52 , the planet gear  20  and the internal gear  24  move themselves as a packet. This unified movement is such that an axial movement, introduced by the sun gear  52 , and transferred by the planet gear  20  results in an equally directed axial movement of the internal gear  24 .  
         [0026]     In  FIG. 1 , the pressure bolt  48  coacts with a detent  64 , i.e., a holding means, within a sliding sleeve  66  and thereby engage the detent  64 . By this means, the sliding sleeve  66  is held in a neutral position. The sliding sleeve  66  has a first internal toothing  68  ( FIG. 2 ), which engages itself in an external toothing  70  on the sun gear  52  and a non-rotatable connection between the sliding sleeve  66  and the sun gear  52  is established (see  FIG. 2 ). For the formation of a non-rotatable connection between the sliding sleeve  66  and the main drive shaft  44 , the sliding sleeve  66  has a second internal toothing  72 , which engages itself in an external toothing  74  on the main drive shaft  44 .  
         [0027]     For the bringing about of an optional, non rotatable connection of the main drive shaft  44  with the planet carrier  10  for the formation of a direct binding of the main transmission  6  with the output drive shaft  12  at a continuing equal speed of rotation, the sliding sleeve  66  has a shift-toothing  76 , which can engage itself in a shift toothing  78  on the projection  36  of the planet carrier  10 .  
         [0028]      FIG. 1  presents the planetary transmission  8  in a neutral position. Neither the shift-toothing  26  and  28 , nor the shift-toothing  76  and  78  engage each other.  
         [0029]     The pressure bolt  48  enters into the detent  64  on the sliding sleeve  66 . The sun gear  52  finds itself positioned to the right (as seen in the drawing). The planet gear  20  is supported on the planet bolt  18  only on a cylindrical roller bearing of the roller bearing  22 . The planetary transmission  8  is load free, hence a simple bearing suffices, which brings about a small loss.  
         [0030]     If now the sliding sleeve  66  is pushed to the left by an actuator (not shown in the drawing), then the sliding sleeve  66 , likewise, draws the sun gear  52  to the left by actuating a ring  80  left being in accord with the drawing. This motion is described in  FIG. 2 . The planet gear  20  is, likewise, moved and accompany therewith by the toothed pressure compensators  56  and  58  and, in turn, brings the internal gear  24  to the left along with it, powered by the toothed pressure compensators  60  and  62 . By this action, the two shift toothings  26  and  28  engage each other, whereby the internal gear  24  becomes non-rotatably affixed. Thereby, the planet carrier  10  turns in a known manner, as compared to the main drive shaft  44  in a slower ratio. At this point, the planetary transmission  8  is under a loaded condition, because the total torque is now being taken over by the planet gear  20 . On this account, it is necessary, that the bearing support of the planet gear  20  be reinforced by the planet bolt  18 . Due to the sliding of the planet gear  20  to the left by the sun gear  52 , the planet gear  20  is also drawn onto the second cylindrical roller bearing of the roller bearing support  22 . The situation now is that a clearly increased load capacity of the roller bearing support  22  is made available. Instead of several cylindrical roller bearings, a multi-row bearing can be considered, in particular, a two-row needle bearing.  
         [0031]     If now, the sliding sleeve  66 , as illustrated in  FIG. 2 , is pushed to the right by the (unseen) actuator, then the sliding sleeve  66  moves the sun gear  52 , likewise, to the right (per the drawing) by way of the detent  64  and the pressure bolt  48 . The planet gear  20  is pushed by the toothed pressure compensators  56  and  58  onto the sun gear  52  and of itself then pushes, the internal gear  24  to the right into the neutral position by way of the toothed pressure compensators  60  and  62  according to  FIG. 1 . At this point, the sun gear  52  with the shell  54  lies against the planet carrier  10 .  
         [0032]     If the sliding sleeve  66  is caused to move to the right out of the neutral position ( FIG. 1 ), then the force of the spring  50  on the pressure bolt  48  is overcome by the detent  64  and the sliding sleeve  66  moves further to the right. When this occurs, the sun gear  52  is not complementarily moved axially. On this account, the sun gear  52  and therewith the planet gear  20  slidingly cover a small path back, as does the sliding sleeve  66  which moves the sun gear  52  and therewith the planet gear  20 . The shift toothing  76  on the sliding sleeve  66  engages the complementary shift toothing  78  on the projection  36  of the planet carrier  10 , whereby a non-rotatable connection between the main drive shaft  44  and the output drive shaft  12  is achieved. This is presented in  FIG. 3 . Thereby, in a known way, the planet carrier  10  turns itself in reference to the main drive shaft  44  at the same speed of rotation. Now the planetary transmission  8  runs free from load, while the total torque is taken over by the planet carrier  10 . The bearings of the planet gear  20  on the planet bolt  18  must not be supported, so that the planet gear  20  can be carried only on a cylindrical roller bearing of the roller bearing  22  as is the case in the neutral position.  
         [0033]      FIG. 4  illustrates a changed design of the sliding sleeve  66 . In this case, the sliding sleeve  66  is constructed as being of one part with the sun gear  52 .  
         [0034]     In this arrangement, during an axial sliding of the sliding sleeve  66 , within the three possible shift positions, the sun gear  52  and therewith the planet gear  20  and the internal gear  24  always move in common. On this account, it is necessary that sufficient operational space be made available in the planetary transmission  8 .  
         [0035]     The attainment of the slow ratio is carried out as is explained in regard to  FIG. 2 . By means of the one piece design of the sliding sleeve  66  and the sun gear  52 , the pressure bolt and the detent can be eliminated. If now the sliding sleeve  66  is pushed to the right, (per drawing) by an actuator and out of the shifting position for the slow ratio, then the sliding sleeve  66  necessarily pushes the attached sun gear  52  with it, likewise to the right. The planet gear  20  slides along, being pushed by the toothed pressure compensators  56  and  58  on the sun gear  52  and, on its own, pushes the internal gear  24  with the aid of the toothed pressure compensators  60  and  62 . As this occurs, the internal gear  24  moves to the right until the neutral position shown in  FIG. 4  is reached. The sun gear  52  does not lie on the planet carrier  10 .  
         [0036]     If the sliding sleeve  66  is pushed further to the right out of the neutral position (shown in  FIG. 4 ), then accordingly, the sleeve  66  also axially pushes the sun gear  52  to the right. The shift toothing  76  on the sliding sleeve  66  engages in the shift toothing  78  on the projection  36  of the planet carrier  10 , whereby a non-rotatable connection is brought about between the main drive shaft  44  and the output drive shaft  12 . The planetary transmission  8  runs free of load again, because the entire torque is taken over by the planet carrier  10 . The support of the planet gear  20  on the planetary bolt  18  must not be reinforced, so that the planet gear  20 , as is the case in the neutral position, can be carried only by a cylindrical roller bearing of the roller bearing  22 .  
         [0037]     For the formation of a stable end position, and for the avoidance of an undesirable problematic sliding, it is possible that the toothing  26 ,  28  and  76  to  78  be designed with a roll-back.  
         [0038]     By way of the arrangement, according to the invention, a dog-clutch type shifting device is formed for a planetary transmission which is placed on the main drive shaft of the transmission. The shifting of the rapid ratio of the auxiliary range gear train by direct connection is done free of load. The short shifting path of the toothings on the auxiliary range gear train enables short operating levers on the planetary bolts. Roll bearings carry the planet gears safely on the planetary bolts.  
         [0039]     Fundamentally, the invented shifting apparatus is adaptable, both for a shifting transmission with one countershaft as well as for a shifting transmission with a load splitter requiring several countershafts.  
       REFERENCE NUMERALS  
       [0000]    
       
           2  shifting transmission  
           4  transmission housing  
           6  main transmission  
           8  planetary transmission  
           10  planet carrier  
           12  output drive shaft  
           14  flange for  12   
           16  bearing arrangement  
           18  planet bolt  
           20  planet gear  
           22  roller bearing  
           24  internal gear  
           26  shift toothing  
           28  shift toothing  
           30  support base plate  
           32  shaft  
           34  bearing arrangement  
           36  projection  
           38  roller bearing  
           40  countershaft  
           42  bearing arrangement  
           44  main drive shaft  
           45  pin  
           46  gear  
           48  pressure bolt  
           50  spring  
           52  sun gear  
           54  shell  
           56  toothed pressure compensator  
           58  toothed pressure compensator  
           60  toothed pressure compensator  
           62  toothed pressure compensator  
           64  detent  
           66  sliding sleeve  
           68  internal toothing  
           70  external toothing  
           72  internal toothing  
           74  external toothing  
           76  shift toothing  
           78  shift toothing  
           80  ring

Technology Category: f