Abstract:
A powershift transmission, particularly for a construction machine such as backhoes or telehandlers, includes a mechanical power path and a hydrodynamic power path. The first, second and third gears can be engaged by way of the hydrodynamic torque converter ( 1 ) while the fourth, fifth and sixth gears can be engaged without the hydrodynamic torque converter ( 1 ). For this, the input shaft ( 6 ) is connected to the turbine ( 14 ) and the driveshaft ( 7 ) can be directly connected to the drive engine. The driveshaft ( 7 ) is located inside the input shaft ( 6 ).

Description:
[0001]    This application claims priority from German patent application serial no. 10 2015 219 000.5 filed Oct. 1, 2015. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a powershift transmission with several shiftable gears and with a hydrodynamic and a mechanical power path for construction machines, in particular backhoes or telehandlers. 
       BACKGROUND OF THE INVENTION 
       [0003]    The structural space available, in particular the distance between the driveshaft and the drive output shaft and thus the depth of the transmission, is limited. In addition, different axis distances between the transmission input shaft and the transmission output shaft should be possible. For that reason powershift transmissions of the type concerned have shafts at a distance apart from one another which preferably have only a single clutch, in order to be able to produce a compact transmission. 
         [0004]    EP 1 329 648 B1 discloses a powershift transmission with a hydrodynamic and an optional mechanical power path, in which the input shaft is connected to a fixed wheel and is in the form of a hollow shaft, and the driveshaft passes through the input shaft and can be connected to an auxiliary power take-off. Furthermore, the input shaft is also connected to an outer disk carrier of a clutch in a rotationally fixed manner. 
         [0005]    U.S. Pat. No. 6,513,399 B2 discloses a powershift transmission in which the driveshaft is connected to a pump wheel of a hydrodynamic torque converter and is also connected to an outer disk carrier of a clutch, and drives an auxiliary power take-off. The input shaft is in the form of a hollow shaft and is connected to the turbine wheel of the hydrodynamic torque converter rotationally fixed to a fixed wheel. In order to be able to shift the gears, two clutches have to be arranged on the shafts a distance apart, and for that reason the depth of the transmission has to be made greater such that it is not suitable for a telehandler. 
       SUMMARY OF THE INVENTION 
       [0006]    The purpose of the present invention is to provide a powershift transmission for construction machines, in particular for backhoes or telehandlers, which has a hydrodynamic power path and a mechanical power path and is of compact structure. In this context mechanical power path means that the drive output of the transmission can be connected to the drive engine independently of the function of the hydrodynamic torque converter. 
         [0007]    This objective is achieved with a powershift transmission of the type concerned which also incorporates the characterizing features specified in the principal claim. 
         [0008]    According to the invention, the powershift transmission comprises a hydrodynamic torque converter with a turbine and a pump, wherein the pump is in rotationally fixed connection with a driveshaft and this driveshaft can be connected to a drive engine such as a diesel internal combustion engine. The turbine of the hydrodynamic torque converter is connected in a rotationally fixed manner to an input shaft and a fixed wheel is also connected to the input shaft in a rotationally fixed manner. The input shaft is in the form of a hollow shaft and the driveshaft passes through the hollow shaft and is also connected in a rotationally fixed manner to a fixed wheel. The fixed wheel which is connected in a rotationally fixed manner to the input shaft is located between the hydrodynamic torque converter and the fixed wheel connected in a rotationally fixed manner to the driveshaft. Thus, the hydrodynamic torque converter and the two fixed wheels are arranged coaxially with one another. This makes it possible to arranged the shafts farther apart, with their shifting clutches and gearwheels, in such manner that a transmission of compact depth is obtained. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Other features emerge from the description of the figures. 
           [0010]    The figures show: 
           [0011]      FIG. 1 : A powershift transmission without a shifting clutch on the input shaft; 
           [0012]      FIG. 2 : A powershift transmission with a clutch for a reversing gear on the input shaft; 
           [0013]      FIG. 3 : The arrangement of the gearwheels of the powershift transmission shown in  FIG. 2 ; 
           [0014]      FIG. 4 : A powershift transmission with a clutch for the forward gear on the input shaft; 
           [0015]      FIG. 5 : The arrangement of the gearwheels of the powershift transmission shown in  FIG. 4 ; 
           [0016]      FIG. 6 : A powershift transmission with a clutch for driving in reverse on the input shaft; and 
           [0017]      FIG. 7 : The arrangement of the gearwheels of the powershift transmission shown in  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]      FIG. 1 : 
         [0019]    A drive engine (not shown), for example an internal combustion engine, drives the driveshaft  7 , which is connected in a rotationally fixed manner on one side with the pump  12  of the hydrodynamic torque converter  1  and on the other side with the fixed wheel  3 . Furthermore, the driveshaft  7  forms an auxiliary power take-off  13  opposite the hydrodynamic torque converter  1 , which for example can be connected to the working pump of the construction machine. The turbine  14  of the hydrodynamic torque converter  1  is connected in a rotationally fixed manner to the input shaft  6 , which is connected in a rotationally fixed manner to the fixed wheel  2 . The input shaft  6  is in the form of a hollow shaft. The fixed wheel  3  meshes with the loose wheel  8 , and the loose wheel  8  can be connected to the shaft  16  by means of the clutch formed as a fourth gear clutch  15 . The shaft  16  is connected in a rotationally fixed manner to the fixed wheel  4 . The fixed wheel  4  meshes on one side with the fixed wheel  17  and on the other side with the fixed wheel  18 . The fixed wheel  17  is connected in a rotationally fixed manner to the shaft  19 . By means of the clutch  20  for the reversing gear, the loose wheel  5  can be connected to the fixed wheel  17 . The fixed wheel  2  meshes both with the loose wheel  5  and also with the loose wheel  21 . By means of the clutch  9  for a forward gear, the loose wheel  21  can be connected to the fixed wheel  22  and the fixed wheel  23 , whereas the fixed wheel  22  and the fixed wheel  23  are connected to the shaft  24  and the loose wheel  21  is mounted to rotate on the shaft  24 . The fixed wheel  23  meshes with the fixed wheel  25 , which is arranged in a rotationally fixed manner on the shaft  26 . Mounted to rotate on the shaft  26  is the loose wheel  28 , which can be connected by means of the first gear clutch  27  to the fixed wheel  25 . The loose wheel  28  meshes with the fixed wheel  29 , which is connected in a rotationally fixed manner to the shaft  30  on which the loose wheel  32  is mounted to rotate. By means of the third gear clutch  31 , the fixed wheel  29  can be connected to the loose wheel  32 . The loose wheel  32  meshes with the fixed wheel  18 , which is connected in a rotationally fixed manner to the shaft  33  and can be connected by means of the second gear clutch  34  to the loose wheel  35  which is also arranged on the shaft  33 . 
         [0020]    Thus, by engaging the fourth gear clutch  15 , the mechanical power path can be connected through and the hydrodynamic torque converter  1  therefore put out of function in that shift position, whereby the efficiency is improved considerably. Preferably, by engaging the fourth gear clutch  15  those gears can be engaged which are used for driving at higher speeds. 
         [0021]    A first gear in the forward direction is engaged by actuating the clutch  9  for a forward gear and the first gear clutch  27  in the closing direction, whereby a first gear can be engaged by means of the hydrodynamic torque converter  1 . A second gear is engaged by keeping the clutch  9  for the forward gear engaged and, instead of the first gear clutch  27 , engaging the second gear clutch  34  by actuating it in the closing direction. This engages a second gear by way of the hydrodynamic torque converter  1 . A third gear is engaged by keeping the clutch  9  for the forward gear engaged and also actuating the third gear clutch  31  in the closing direction. This enables a third gear to be engaged by way of the hydrodynamic torque converter  1 . To engage a fourth gear in the forward driving direction, so that the vehicle is now in the higher speed range, the clutch  9  for the forward gear is actuated in the opening direction and the fourth gear clutch  15  is actuated in the closing direction. In addition, for this gear the first clutch  27  is actuated in the closing direction. This provides a gear, namely the fourth gear, without the hydrodynamic torque converter  1  and thus by direct drive by means of the drive engine. A fifth gear is engaged by keeping the fourth gear clutch  15  closed and actuating the second gear clutch  34  in the closing direction. This enables a fifth gear without the hydrodynamic torque converter  1 . A sixth gear is engaged by keeping the fourth gear clutch  15  closed and actuating the third gear clutch  31  in the closing direction. Thus, at the top speed of the vehicle too a gear without the hydrodynamic torque converter  1  is enabled. 
         [0022]      FIG. 2 : 
         [0023]    A drive engine (not shown), for example an internal combustion engine drives, on the one hand, the pump  12  of the hydrodynamic torque converter  1  and, on the other hand, the driveshaft  7 , which is connected in a rotationally fixed manner to the fixed wheel  3  and which at the same time forms the drive input for the auxiliary power take-off  13 . The turbine  14  is connected in a rotationally fixed manner to the input shaft  6 , which is connected to the fixed wheel  2 . The input shaft  6  can be connected by means of the clutch  20  for reverse driving to the loose wheel  5 . The fixed wheel  2  meshes with the loose wheel  21 , the fixed wheel  3  meshes with the fixed wheel  4  and the loose wheel  5  meshes with the fixed wheel  25 . The fixed wheel  4  is connected in a rotationally fixed manner to the shaft  16  and can be connected by means of the fourth gear clutch  15  to the loose wheel  8 . The loose wheel  8  meshes with the fixed wheel  25 . The loose wheel  21  is mounted to rotate on the shaft  24  and can be connected by means of the clutch  9  for the forward gear to the fixed wheel  23 . The fixed wheel  23  is connected in a rotationally fixed manner to the shaft  24 . The fixed wheel  23  meshes with the fixed wheel  25 , which is connected in a rotationally fixed manner to the shaft  26  and which can be connected by means of the first gear clutch  27  to the loose wheel  28 . The loose wheel  28  meshes with the fixed wheel  22 , which is connected rotationally fixed to the shaft  33  that forms the drive output. By means of the second gear clutch  34  the fixed wheel  22  can be connected to the loose wheel  35 . Also connected in a rotationally fixed manner to the shaft  33  is the fixed wheel  18 , which meshes with the loose wheel  32 . The loose wheel  32  meshes with the fixed wheel  29 , which is connected in a rotationally fixed manner to the shaft  30 . By means of the third gear clutch  31  the fixed wheel  29  can be connected to the loose wheel  32 . 
         [0024]    Thus, the first three gears are engaged by way of the hydrodynamic torque converter  1  and gears four, five and six are engaged without the hydrodynamic torque converter  1 , directly with the drive engine. The first gear in the forward direction is engaged by actuating the clutch  9  for the forward gear in the closing direction and likewise closing the first gear clutch  27 . A second gear in the forward driving direction is engaged by keeping the clutch  9  for the forward gear closed and also closing the second gear clutch  34 . A third gear in the forward driving direction is engaged by keeping the clutch  9  for the forward gear closed and also actuating the third gear clutch  31  in the closing direction. A fourth forward gear is engaged by actuating the clutch  9  for the forward gear in the opening direction and actuating the fourth gear clutch  15  in the closing direction and also the first gear clutch  27  in the closing direction. A fifth gear is engaged by actuating the fourth gear clutch  15  in the closing direction and also the second gear clutch  34  in the closing direction. A sixth gear is engaged by actuating the fourth gear clutch  15  in the closing direction and the third gear clutch  31  also in the closing direction. 
         [0025]      FIG. 3 : 
         [0026]    The arrangement of the gearwheels in the transmission layout according to  FIG. 2  is shown. 
         [0027]      FIG. 4 : 
         [0028]    A drive engine (not shown) drives on the one hand the pump  12  of the hydrodynamic torque converter  1  and on the other hand the driveshaft  7 , which is connected in a rotationally fixed manner to the fixed wheel  3  and which forms the drive output for the auxiliary power take-off  13 . The turbine  14  is connected in a rotationally fixed manner to the input shaft  6 , which is connected in a rotationally fixed manner to the fixed wheel  2 . In addition, for a forward gear  9  the input shaft  6  can be connected to the loose wheel  21 . The fixed wheel  2  meshes with the fixed wheel  22 , which is connected in a rotationally fixed manner to the shaft  19  and can be connected to the loose wheel  5  by means of the reversing gear clutch  20 . The loose wheel  5  meshes with the fixed wheel  4 , which can be connected by means of the fourth gear clutch  15  to the loose wheel  8  that is arranged on the shaft  16 . The loose wheel  21  also meshes with the fixed wheel  4 , which in turn meshes with the fixed wheel  25 . The fixed wheel  25  is arranged on the shaft  26  and can be connected by means of the first gear clutch  27  to the loose wheel  28 . The fixed wheel  25  meshes with the loose wheel  35  and the loose wheel  28  meshes with the fixed wheel  36 . The fixed wheel  36  is connected in a rotationally fixed manner to the shaft  33 , which forms the drive output of the transmission. By means of the second gear clutch  34 , the fixed wheel  36  can be connected to the loose wheel  35 . The fixed wheel  18  is connected in a rotationally fixed manner to the shaft  33  and meshes with the loose wheel  32 , which is arranged on the shaft  30 . The loose wheel  32  can be connected to the fixed wheel  29  by means of the third gear clutch  31 . 
         [0029]    Thus, the first three gears of the transmission can be engaged by way of the hydrodynamic torque converter  1  and gears four, five and six can be engaged without the hydrodynamic torque converter  1 . A first gear is engaged by actuating the clutch  9  for the forward gear in the closing direction and the first gear clutch  27  also in the closing direction. A second gear can be engaged by actuating the clutch  9  for the forward gear in the closing direction and the second gear clutch  34  also in the closing direction. A third gear can be engaged by actuating the clutch  9  for forward driving and the third gear clutch  31  in the closing direction. A fourth gear can be engaged without the hydrodynamic torque converter  1  by actuating the fourth gear clutch  15  in the closing direction and actuating the clutch  9  for the forward gear in the opening direction and the first gear clutch  27  in the closing direction. A fifth gear can be engaged by actuating the fourth gear clutch  15  and the second gear clutch  34 , both in the closing direction. A sixth gear can be engaged by actuating the fourth gear clutch  15  and the third gear clutch  31  in the closing direction. Thus, at higher speeds the transmission is shifted without the hydrodynamic torque converter  1 . 
         [0030]      FIG. 5 : 
         [0031]    The arrangement of the gearwheels in the transmission layout according to  FIG. 4  is shown in  FIG. 5 . 
         [0032]      FIG. 6 : 
         [0033]    In contrast to the transmission layouts according to  FIGS. 1, 2 and 4 , in the transmission layout according to  FIG. 6  it is not the case that only a single clutch is arranged on a shaft, but rather, two clutches are arranged on a shaft. On the shaft  24  are arranged both the clutch  9  for the forward gear and the fourth gear clutch  15 . The fourth gear clutch  15  can also be regarded as the clutch for a further forward gear. The input shaft  6  and the fixed wheel  2  are connected to the turbine  14 , whereas the fixed wheel  3  is connected to the driveshaft  7  and thus also to the drive engine (not shown), which also drives the pump  12 . The fixed wheel  2  meshes with the loose wheel  37  and the fixed wheel  3  meshes with the loose wheel  11 , both of which are arranged on the shaft  24 . The clutch  9  for the forward gear is arranged on the shaft  24  and the fourth gear clutch  15  is also arranged on the shaft  24 . By means of the clutch for forward driving the loose wheel  37  can be connected to the eighth fixed wheel  23 , and by means of the fourth gear clutch  15  the loose wheel  11  can be connected to the shaft  24  and thus to the fixed wheel  23 . The fixed wheel  23  meshes with the fixed wheel  25 , which can be connected by means of the first gear clutch  27  to the loose wheel  28 . The shaft  33  forms the drive output and is connected in a rotationally fixed manner to the fixed wheel  18  and to the fixed wheel  22 , whereas the loose wheel  35  can be connected by means of the second gear clutch  34  to the shaft  33 . The third gear clutch  31  is arranged on the shaft  30 , whereby the fixed wheel  29  can be connected to the loose wheel  32 . 
         [0034]    Thus, the first three gears of the transmission can be engaged by way of the hydrodynamic torque converter  1  and gears four, five and six can be engaged without the hydrodynamic torque converter  1 . A first gear is engaged by actuating the clutch  9  for a forward gear and the first gear clutch  27 , both in the closing direction. A second gear is engaged by keeping the clutch  9  for the forward gear closed and also actuating the second gear in the closing direction. The clutch for the third gear is engaged by keeping the clutch  9  for the forward gear closed and also actuating the third gear clutch  31  in the closing direction. A fourth gear without the hydrodynamic torque converter  1  is engaged by actuating the clutch  9  for the forward gear in the opening direction and the fourth gear clutch  15  in the closing direction, as well as the first gear clutch  27  in the closing direction. A fifth gear can be engaged by actuating the fourth gear clutch  15  and the second gear clutch  34 , both in the closing direction. A sixth gear can be engaged by actuating the fourth gear clutch  15  and the third gear clutch  31 , both in the closing direction. The reversing gears can be engaged by actuating the clutch  20  for reverse driving in the closing direction. This is arranged on the input shaft  6 . 
         [0035]      FIG. 7 : 
         [0036]    The arrangement of the gearwheels of the transmission layout according to  FIG. 6  is shown in  FIG. 7 . 
       INDEXES 
       [0000]    
       
           1  Hydrodynamic torque converter 
           2  Fixed wheel 
           3  Fixed wheel 
           4  Fixed wheel 
           5  Loose wheel 
           6  Input shaft 
           7  Driveshaft 
           8  Loose wheel 
           9  Clutch for a forward gear 
           10  Clutch for a further forward gear 
           11  Loose wheel 
           12  Pump 
           13  Auxiliary power take-off 
           14  Turbine 
           15  Fourth gear clutch 
           16  Shaft 
           17  Fixed wheel 
           18  Fixed wheel 
           19  Shaft 
           20  Clutch for the reverse gear, or reverse gear clutch 
           21  Loose wheel 
           22  Fixed wheel 
           23  Fixed wheel 
           24  Shaft 
           25  Fixed wheel 
           26  Shaft 
           27  First gear clutch 
           28  Loose wheel 
           29  Fixed wheel 
           30  Shaft 
           31  Third gear clutch 
           32  Loose wheel 
           33  Shaft 
           34  Second gear clutch 
           35  Loose wheel 
           36  Fixed wheel 
           37  Loose wheel 
           38  Shaft