Abstract:
A method of synchronizing a double clutch transmission having two input shafts and an output shaft. The input shafts can couple a motor drive shaft via an input friction clutch to synchronize rotation of the forward gears. The input shafts are coaxial with one located within the other, and the transmission output shaft is likewise coaxial. Each of the forward and reverse gears are arranged in a respective gearset plane. The gear clutches for the forward and reverse gears form gear shifting devices with some being actuated on two sides. Progressive gear steps are realized between the forward gears, and the gear clutches are unsynchronized shift elements. The rotational speed of one or more gear clutches, necessary for a gear change, is adapted as needed by actuating one or both of the input clutches and controlling the rotational speed of the motor.

Description:
[0001]    This application is a National Stage completion of PCT/EP2012/051769 filed Feb. 2, 2012, which claims priority from German patent application serial no. 10 2011 006 004.9 filed Mar. 24, 2011. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a method for synchronizing a double clutch transmission, and a double clutch transmission. 
       BACKGROUND OF THE INVENTION 
       [0003]    Double clutch transmissions that have friction clutches arranged at the input side and are each connected by an input shaft to a group of uneven or even gears and constitute two subtransmissions with a common output shaft are known in various designs. The two friction clutches can for example be designed nested in a compact double clutch unit, the two input shafts being arranged coaxially one upon the other. One input shaft is designed as an exterior, shorter hollow shaft out of which the other input shaft extends as a longer, inner solid shaft. Alternately, two individual clutches can also be arranged in an axially parallel arrangement of two input shafts. The output shaft can be arranged differently. 
         [0004]    The shifting operations of such a transmission are sequential, wherein the next gear is preselected in the currently load-free transmission train such that two gears are simultaneously engaged, and the gear change transitions from one gear to the next gear while largely retaining traction, by an overlapping disengagement and engagement of the two friction clutches. 
         [0005]    Double clutch transmissions are capable of meeting the requirements of commercial vehicle transmissions to enable start-off and maneuvering processes under heavy vehicle loads on gradients, or during difficult road conditions, and also enable fast and efficient driving during long-distance haulage and therefore require a relatively large overall gear ratio spread. Known multi-group transmissions for commercial vehicles are more likely to have geometrical gear steps with approximately equal step changes, the difference of the maximum speeds varying between the gears, and they achieve the requirements by having a high number of gears, typically 12 or 16 gears, in a combination of two or three individual transmissions; however, double clutch transmissions can have a comparable overall spread with fewer gears due to their self-contained design, and are more likely to have progressive gear steps with varying step changes, and the difference of the maximum speeds scarcely changes between the gears. The sequential shifting of double clutch transmissions is traction-supported per se, whereas multi-group transmissions require additional effort for traction-supported gear changing with a largely optional shifting sequence. 
         [0006]    A nine gear double clutch transmission is known from DE 10 2005 005 942 A1 with progressive step changes that has a relatively large overall spread. Provided therein are a first gear as a crawler gear, a second gear as a start-off gear, a seventh gear as a direct gear, as well as two useful overdrive gears for full load haulage in which the maximum speed is not reached. The nine forward gears are achieved with seven gear set planes. A reverse gear can be coupled to one of the gear set planes of the forward gears. Overall, 10 gear clutches are arranged for shifting gears, partially in clutch devices that can be actuated from two sides. 
         [0007]    DE 10 2007 049 270 A1 discloses a double clutch transmission having at least eight power-shiftable forward gears. On each of both sides of a main shaft arrangement, the transmission has a countershaft arrangement. The two countershaft arrangements are arranged axially parallel to each other. The main shaft arrangement comprises two transmission input shafts arranged coaxially over each other, which are each connected to an input-side friction clutch and one output shaft arranged coaxially upstream therefrom. The eight forward gears, as well as one or two reverse gears, are configured in five gear set planes and one output step, and can be shifted with eight gear clutches as well as one additional shifting element. At least one gear is designed as a winding path gear that can be shifted via the additional shifting element by means of which the two transmission input shafts can be coupled to each other. 
         [0008]    With double clutch winding transmissions, the flow of power of one or more gears alternates over a number of gear planes to between the main shaft arrangement and a parallel countershaft arrangement. The flow of power therefore winds through the transmission. In comparison to conventional transmission structures, winding transmissions manage with fewer pairs of gears, or gear set planes, to generate a specific number of gears; however, the flow of power runs through numerous components. 
         [0009]    For synchronizing the rotational speed in the shifting operations of double clutch transmissions, synchronization units are provided that can be actuated on two sides or at least one side. However, in comparison to simple form-locking claw clutches, synchronization units are more complex and expensive. Consequently, double clutch transmissions with unsynchronized shifting elements have already been proposed. However, measures for adapting the rotational speed are required to shift gears in such a transmission. 
         [0010]    A synchronization method for a double clutch transmission with unsynchronized gear clutches is known from DE 102 32 837 A1. The transmission comprises a double clutch consisting of two separate friction clutches that are arranged axially parallel and are drive-connected with each other. One input shaft is assigned to each of the two friction clutches, and the double clutch transmission has a common, axially parallel output shaft arranged between the input shafts. Idler gears that are arranged on the input shafts are connectable in a rotationally fixed manner to the shafts by means of claw couplings and engage with assigned fixed gears on the output shaft, whereby two subtransmissions are formed. Each fixed gear forms a transmission ratio alternatingly with an idler gear of one input shaft or the other input shaft. Gear shifting occurs in the normal, sequential manner for double clutch transmissions in which a subsequent gear is preselected in the presently load-free subtransmission and while the other subtransmission is within the flow of power. By overlapping the disengagement and engagement of the two friction clutches, the torque is smoothly transferred without an interruption in tractive force from one subtransmission to the other. To synchronize the shifting clutch of the respective subsequent gear in the load-free subtransmission, the previously open associated friction clutch of the subtransmission is operated in slip mode until achieving the necessary adaptation of speed of the shift dogs to be engaged. Then the subsequent gear can be engaged, and the gear shifting can be executed as described. 
       SUMMARY OF THE INVENTION 
       [0011]    Against this background, the object of the invention is to present a method for synchronizing the speed in shifting procedures in a double clutch transmission with a comparatively large number of gears. In addition, a double clutch transmission of the initially-cited type is proposed that enables such a method to be performed and can be manufactured comparatively economically and constructed in a compact manner. 
         [0012]    The invention is based on the knowledge that all the upshifting and downshifting of a double clutch transmission can be synchronized by variable use of both clutches and suitable engine speed guidance. Accordingly, a compact double clutch transmission with more than eight gears can have a branching flow of power for winding path gears, and can possess gear sets that yield at least partially progressive gear steps to realize a comparatively high overall gear ratio spread, and nevertheless be equipped with economical unsynchronized claw shift elements. A double clutch transmission that enables such synchronization of rotational speed of more than eight gears can be realized by suitably arranging fixed and idler gears in an interactive system of hollow shafts and solid shafts in a main shaft and a parallel idler shaft. 
         [0013]    The invention is accordingly based on a method for synchronizing a double clutch transmission with two transmission input shafts and one transmission output shaft, wherein the two transmission input shafts are each connectable to a driveshaft of a drive motor by means of an assigned input-side friction clutch, wherein gears are arranged in a plurality of gear set planes and are designed as idler gears or fixed gears and are each connected in a rotationally fixed manner to one of the two transmission input shafts or to a shaft that is drive-connectable thereto, or are pivoted thereto, wherein gear clutches are assigned to the idler gears by means of which the idler gears are connectable in a rotationally fixed manner to the relevant shaft, and the rotational speed is adapted by means of one or more of the gear clutches. 
         [0014]    The stated problem regarding the method is solved according to the invention in that an adaptation of the rotational speed of one or more of the gear clutches necessary for a gear change is performed as needed by means of actuating one or both of the input side friction clutches and controlling the rotational speed of the drive motor. 
         [0015]    In one embodiment of the method, a speed adaptation is performed as needed to shift nine forward gears by means of six gear set planes and eight unsynchronized gear clutches in which the load-free friction clutch of the two friction clutches is engaged when upshifting, and the load-transmitting friction clutch of the two friction clutches is operated in slip mode when downshifting, and/or the load-free friction clutch of the two friction clutches is engaged. 
         [0016]    Furthermore, the invention is based on a double clutch transmission with two transmission input shafts and one transmission output shaft, wherein the two transmission input shafts are each connectable to a driveshaft of a drive motor by means of an assigned input-side friction clutch, wherein gears are arranged in a plurality of gear set planes and are designed as idler gears or fixed gears and are each connected in a rotationally fixed manner to one of the two transmission input shafts or to a shaft that is drive-connectable thereto, or are rotatable thereto, wherein gear clutches are assigned to the idler gears by means of which the idler gears are connectable in a rotationally fixed manner to the relevant shaft. 
         [0017]    In order to solve the stated problem regarding the double clutch transmission, the invention proposes designing a transmission structure for shifting at least nine forward gears, wherein the two transmission input shafts are arranged coaxially one over the other, and the transmission output shaft is arranged coaxially behind them, wherein the gears of the forward gears are arranged in six gear set planes, wherein the gears of a reverse gear are arranged in a separate gear set plane, wherein at the most eight gear clutches for the forward gears, and one gear clutch for the reverse gear, are arranged in gear shifting devices that are partially actuatable on two sides, wherein at least partially progressive gear steps are realized between the forward gears, and wherein the gear clutches are designed as an unsynchronized shift elements. 
         [0018]    Progressive gear steps are to be understood as gear steps that sequentially vary. 
         [0019]    This transmission has a particularly compact design by combining the arrangement of the two friction clutches into one nested double clutch unit, wherein the two input shafts are arranged coaxially one over the other, and the transmission output shaft is arranged coaxially behind them, and by a transmission structure in which the gears are predominately mounted for rotation as shiftable idler gears on shaft segments that can be coupled with each other. This enables nine to ten gears with only six gear set planes and eight gear clutches. A plurality of the gears, especially the lower gears, can be realized as winding path gears. 
         [0020]    With nine or ten gears in this arrangement, an overall gear ratio spread can be achieved with progressive gear steps that is comparable to a group transmission with a much higher number of gears, and that satisfies the requirements of a transmission for a commercial vehicle, such as a truck in long-distance haulage. This enables easy and reliable startup, even with a full load on gradients, as well as efficient long-term operation. The ninth gear can be designed as a direct gear. The transmission structure also enables a tenth gear that preferably can be designed as a fast gear with a similar gear ratio. All gear changes can occur without interrupting the tractive force as is normally the case with double clutch transmissions. 
         [0021]    Construction space and cost can be further saved by an embodiment of the double clutch transmission in which six of the eight gear clutches of the forward gears are combined in three gear shifting devices that can be actuated from two sides, and by another embodiment that can be successfully combined therewith in which only one gear shifting device is arranged in a large majority of the axial gaps each existing between two respective gear set planes. 
         [0022]    In addition, an axial free space without a gear shifting device can exist between at least two of the gear set planes. This allows a support wall for mounting a shaft to be arranged there with relatively slight effort. It is, however, possible to design the individual shafts or shaft segments of the transmission structure to be short enough to dispense with an additional support wall for mounting a shaft in order to save additional cost and weight. 
         [0023]    Significant additional advantages relative to conventional transmissions result in regard to design complexity, cost, the required construction space and weight, in particular because the rotational speed of the transmission can be synchronized by means of the method according to the invention. Accordingly, all the gears can be synchronized while upshifting and downshifting by means of motor rotational speed guidance and the double clutch. All of the shifting elements are therefore designed as a simple claw shifting elements. 
         [0024]    In the cited embodiment of the transmission, six of the gear clutches for the forward gears can be combined in three claw shifting devices actuatable from two sides. The two other gear clutches, as well as the gear clutch for reverse gear, can be designed as individual claw shifting devices. Synchronous clutches and transmission brakes can be completely discarded. 
         [0025]    Accordingly, starting from a set motor rotational speed, the rotational speed of the gear clutches of the target gear can be adapted by engaging the load-free clutch for all sequential upshifting and downshifting that require it. With some downshifts, it may also be necessary to guide the target rotational speed by means of the load-transmitting clutch. The load-transmitting clutch is temporarily put into slip mode as needed to enable the rotational speed of the relevant shift dogs to be adapted. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    A drawing of an exemplary embodiment accompanies the description to illustrate the invention. Shown are: 
           [0027]      FIG. 1  A schematic representation of a double clutch transmission, 
           [0028]      FIG. 2  A shift pattern of the double clutch transmission according to  FIG. 1  with an example of a series of transmission ratios of the gear sets and an associated step series in a table, and 
           [0029]      FIG. 3  A synchronization diagram of the double clutch transmission according to  FIG. 1  with an example of rotational speed of the transmission ratio series according to  FIG. 2  in a table. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    Accordingly,  FIG. 1  shows a diagram of a double clutch transmission with unsynchronized shifting elements which, for example, can be provided for a commercial vehicle. A comparable double clutch transmission with synchronized shifting elements is disclosed in the unpublished DE 10 2010 030 264 A1 by the applicant. 
         [0031]    The double clutch transmission comprises a double clutch device  7  with two input side friction clutches K 1 , K 2  and two coaxial transmission input shafts  10 ,  11  that are arranged one over the other. A common clutch drum  8  of the double clutch  7  is connected to a driveshaft  9  of a drive motor (not shown). The first transmission input shaft  10  is designed as an inner, solid shaft that is concentrically guided in the second transmission input shaft  11  designed as a shorter, hollow shaft  11  out of which it extends at the transmission side. The inner transmission input shaft  10  is drive-connectable to the drive motor by means of the first friction clutch K 1  close to the motor, and the outer transmission input shaft  11  is drive-connectable to the drive motor by means of the second friction clutch K 2  close to the transmission. 
         [0032]    The two transmission input shafts  10 ,  11  and a transmission output shaft  12  coaxially arranged therebehind form a main shaft arrangement  13 . A countershaft arrangement  14  is axially parallel thereto. Arranged on the main shaft arrangement  13  and the countershaft arrangement  14  are six gear set planes Z 1 , Z 2 , Z 3 , Z 4 , Z 5 , Z 6  for forward gears that are each formed by a pair of gears  15 / 16 ,  18 / 19 ,  21 / 22 ,  24 / 25 ,  27 / 28 ,  30 / 31 , and one gear set plane ZR is available for a reverse gear that is formed by a trio of gears  32 / 33 / 34 . The proportions of the two gears of each gear set plane are not depicted to scale. 
         [0033]    The first gear set plane Z 1  is designed as an input stage. It has a first gear  15  that is connected in a rotationally fixed manner to the second transmission input shaft  11 , and a second gear  16  that meshes with this gear  15  and is connected in a rotationally fixed manner to a central counter shaft segment  17 . 
         [0034]    The second gear set plane Z 2  is formed by a first gear  18  and a second gear  19 . The first gear  18  is rotatably supported on the first transmission input shaft  10 . The second gear  19  is arranged in a rotationally fixed manner on an outer countershaft segment  20  that is rotatably mounted as a hollow shaft on the central countershaft segment  17 . 
         [0035]    The third gear set plane Z 3  possesses a gear  21  that is connected to a central main shaft segment  23  of the main shaft arrangement  13 , and a gear  22  that is arranged in a rotationally fixed manner on the outer countershaft segment  20 . 
         [0036]    The fourth gear set plane Z 4  possesses a gear  24  that is arranged in a rotationally fixed manner on a main shaft segment  26  designed as a hollow shaft, which in turn is rotatably supported on the central main shaft segment  23 . The gear  24  engages with a gear  25  which is rotatably supported on the central countershaft segment  17 . 
         [0037]    The fifth gear set plane Z 5  is formed by a gear  27  that is connected in a rotationally fixed manner to the outer main shaft segment  26 , and a gear  28  that is connected in a rotationally fixed manner to an output side countershaft segment  29 . 
         [0038]    The sixth gear set plane Z 6  comprises a gear  30  that is connected in a rotationally fixed manner to the transmission output shaft  12 , and a gear  31  that is rotatably mounted on the countershaft segment  29 . 
         [0039]    A reverse gear set plane ZR is arranged between the first gear set plane Z 1  and the second gear set plane Z 2 . It comprises a gear  32  that is rotatably supported on the first input shaft  10 , a gear  33  that is connected in a rotationally fixed manner to the outer countershaft segment  20 , as well as an intermediate gear  34  for reversing the direction of rotation. 
         [0040]    The described system of gears and shafts can be actuated by a total of six gear shifting devices  1 ,  2 ,  3 ,  4 ,  5 ,  6  with nine gear clutches A, B, C, D, E, F, G, H, I designed as unsynchronized claw shifting elements. There is an arrangement of three claw clutches  2 ,  3 ,  4  actuatable from two sides and three individual claw clutches  1 ,  5 ,  6 . 
         [0041]    The first gear shifting device  1  is arranged on the countershaft arrangement  14  between the first gear set plane Z 1  and the reverse gear set plane ZR. It is actuatable on one side by means of the gear clutch F for coupling the central countershaft segment  17  to the outer countershaft segment  20 . 
         [0042]    The second gear shifting device  2  is arranged on the main shaft arrangement  13  between the second gear set plane Z 2  and the third gear set plane Z 3 . It is equipped on two sides with gear clutches B and C, and serves to couple the gear  18  of the second gear set plane Z 2  to the first input shaft  10 , and to couple the gear  21  of the third gear set plane Z 3  and the associated central main shaft segment  23  to be first input shaft  10 . 
         [0043]    Between the third plane Z 3  and the fourth plane Z 4 , there is an axial free space that can be used for an optional support wall  35  for mounting a shaft for the central shaft segment  23  on the main shaft plane  13  and the central shaft segment  17  on the countershaft plane  14 . Such an additional gap for a bearing (not shown) of the inner transmission input shaft  10  on the main shaft plane  13 , and for the outer shaft segment  20  on the countershaft plane  14  is between the reverse gear plane ZR and the second gear set plane Z 2 . 
         [0044]    The third gear shifting device  3  is arranged on the countershaft arrangement  14  between the fourth gear set plane Z 4  and the fifth gear set plane Z 5 . It can be actuated on two sides with the gear clutches G and H. It serves to couple the gear  25  of the fourth gear set plane Z 4  to the central countershaft segment  17 , and to couple the gear  28  of the fifth gear set plane Z 5  and the associated output side countershaft segment  29  to the central countershaft segment  17 . 
         [0045]    The fourth gear shifting device  4  is arranged on the main shaft arrangement  13  between the fifth gear set plane Z 5  and the sixth gear set plane Z 6 . This gear shifting device can be actuated on both sides by means of the gear clutches A and D. In addition, the gear  27  of the fifth gear set plane Z 5  can be coupled to the inner main shaft segment  23 , and the gear  30  of the sixth gear set plane Z 6  and associated transmission output shaft  12  to the central main shaft segment  23 . 
         [0046]    The fifth gear shifting device  5  is downstream from the sixth gear set plane Z 6  on the countershaft arrangement  14 . It can be connected on one side by means of the gear clutch E to couple the gear  31  of the sixth gear set plane Z 6  to the output side countershaft segment  29 . 
         [0047]    The sixth gear shifting device  6  is arranged on the main shaft arrangement  13  between the first gear set plane Z 1  and the reverse gear set plane ZR. The reverse gear ZR can be actuated by means of this one-sided gear shifting device  6  with the gear clutch I that couples the gear  32  of the reverse gear set plane ZR to the first transmission input shaft  10 . 
         [0048]      FIG. 2  shows a shift pattern of the transmission of a design with nine forward gears G 1  to G 9  and one reverse gear R. Ten forward gears can also be realized with this transmission structure. 
         [0049]    From the table, it can be seen that the gears G 1  to G 9  can be shifted in an alternating sequence by means of the two input clutches K 1 , K 2 , wherein at least two, and a maximum of four, of the gear clutches A to I can be or are engaged. The flow of force of the gears G 1 , G 3 , G 4  one, three and four, as well as the reverse gear R, proceeds several times alternatingly via the main shaft arrangement  13  and the countershaft arrangement  14 . They are configured as winding path gears and are correspondingly marked in the table (G 1 (W), G 3 (W), G 4 (W)). 
         [0050]    The three last columns of the table show a numerical example for a transmission ratio of the transmission. The individual transmission ratios i_Z of the gear set planes or gear sets Z 1  to Z 6  yield the transmission ratios i_G of gears G 1  to G 9  according to the shift pattern from the product of the shifted individual transmission ratios i_Z. The individual transmission ratios i_Z are each indicated as the ratio of the rotational speed of the gear arranged on the top shaft in  FIG. 1  to the rotational speed of the gear arranged on the bottom shaft in  FIG. 1 . The associated step changes φ between the gears each result from the ratio of the transmission ratios i_G of the neighboring gears. The steps series has step changes φ that vary between φ=1.28 and φ=1.55. The transmission is accordingly stepped progressively, that is with decreasing step changes φ between the gears, although not continuously. From the ratio of the transmission ratios of the first gear i_G 1 =15.96 designed as a starting gear and the highest ninth gear i_G 9 =1 designed as a direct gear yields an overall gear ratio of i_ges=i_G 1 /i_G 9 =15.96. 
         [0051]    The rotational speed synchronization of this transmission is illustrated as an overview in the table in  FIG. 3 . As an example of a predetermined transmission input speed or drive motor speed, the following is assumed for all shift procedures: n_Mot =2100 rpm. The respective target rotational speeds n_sync of the gear clutches to be engaged or synchronized results, according to  FIG. 1  and  FIG. 2 , from the branching of the flow of power through the individual transmission ratios of the gear set planes. 
         [0052]    For the gear shift from the starting gear G 1  to second gear G 2 , only a load transition of input clutches K 1 , K 2  is required. A gear clutch F is disengaged when the load transition of the input clutches K 1 , K 2  is over and the relevant gear clutch F has thereby become load-free. A prior adaptation of the rotational speed is unnecessary since no new gear clutches need to be engaged in the target gear G 2 . Another gear clutch B that also becomes load-free in the target gear G 2  can usefully remain engaged since it is required again in the following third gear G 3 . 
         [0053]    All of the additional sequential upshifting can be synchronized by adapting the rotational speed of each load-free input clutch K 1 , K 2 . 
         [0054]    As an example, the shifting process will be further explained for upshifting from fourth to fifth gear G 4 →G 5 : 
         [0055]    In the currently engaged gear G 4 , the second input clutch K 2  transmits the load. Three gear clutches D, E, F are engaged. Two of the gear clutches D, E remain engaged for the target gear G 5  to be engaged. The third gear clutch F engaged in the original gear can be disengaged load-free after the gear change. A new gear clutch C is engaged for the target gear G 5 . The corresponding synchronous rotational speed can be derived according to the transmission structure and shift pattern. The gear pairs  15 / 16  and  21 / 22  of the first and third gear set planes Z 1 , Z 3 . Accordingly: 
         [0000]    
       
         
           
             
               n 
               sync 
             
             = 
             
               
                 
                   n 
                   Mot 
                 
                 · 
                 
                   1 
                   
                     
                       i 
                       
                         Z 
                          
                         
                             
                         
                          
                         1 
                       
                     
                     · 
                     
                       i 
                       
                         Z 
                          
                         
                             
                         
                          
                         3 
                       
                     
                   
                 
               
               = 
               
                 
                   2100 
                   · 
                   
                     1.21 
                     1.55 
                   
                 
                 = 
                 
                   1639 
                    
                   
                       
                   
                    
                   
                     
                       min 
                       
                         - 
                         1 
                       
                     
                     . 
                   
                 
               
             
           
         
       
     
         [0056]    The rotational speed of the gear clutch C is adapted to this end value by the slipping engagement of the current load free first input clutch K 1 . Once the rotational speed of the shifting element driven by the input clutch K 1  equals that of the corresponding shifting element on the driven gear  21  of gear clutch C, gear clutch C can be engaged. Then, the clutch K 2  transmitting load in the original gear can be disengaged, and the clutch K 1  transmitting load in the subsequent gear can be engaged in order to complete the shifting of the gear from fourth to fifth gear G 4 →G 5  with no interruption in tractive force. 
         [0057]    In the case of some downshifts, the load-transmitting input clutch is temporarily put into slip mode when engaging the load-free input clutch K 1 , K 2 , and the motor speed is adjusted to n_sync in order to bring the gear clutch to be engaged to the synchronous rotational speed. The target rotational speed in these downshifts is guided by means of the load-transmitting input clutch K 1 , K 2 . 
         [0058]    As an example, the shifting process will be further explained for downshifting from fifth to fourth gear G 5 →G 4 : 
         [0059]    In the currently engaged gear G 5 , the first input clutch K 1  transmits the load. 
         [0060]    Three gear clutches C, D, E are engaged. Two of the gear clutches D, E remain engaged in the target gear G 4  to be engaged. The third gear clutch C engaged in the original gear can be disengaged load-free after the gear change. There is a new gear clutch F to shift the target gear G 5 . The corresponding synchronization speed of the gear clutch F is: 
         [0000]    
       
         
           
             
               n 
               sync 
             
             = 
             
               
                 
                   n 
                   Mot 
                 
                 · 
                 
                   1 
                   
                     i 
                     
                       Z 
                        
                       
                           
                       
                        
                       1 
                     
                   
                 
               
               = 
               
                 
                   2100 
                   · 
                   
                     1 
                     1.55 
                   
                 
                 = 
                 
                   1355 
                    
                   
                       
                   
                    
                   
                     
                       min 
                       
                         - 
                         1 
                       
                     
                     . 
                   
                 
               
             
           
         
       
     
         [0061]    Due to the gear clutch C drive-connected and engaged with it, the gear clutch F has an actual speed of: 
         [0000]    
       
         
           
             
               n 
               ist 
             
             = 
             
               
                 
                   n 
                   Mot 
                 
                 · 
                 
                   1 
                   
                     i 
                     
                       Z 
                        
                       
                           
                       
                        
                       3 
                     
                   
                 
               
               = 
               
                 
                   2100 
                   · 
                   
                     1 
                     1.21 
                   
                 
                 = 
                 
                   1736 
                    
                   
                       
                   
                    
                   
                     
                       min 
                       
                         - 
                         1 
                       
                     
                     . 
                   
                 
               
             
           
         
       
     
         [0062]    The speed of the relevant gear clutch F is therefore adapted by engaging the current load-free input clutch K 2  and slip-controlling the current load free input clutch K 1  at the regulated motor speed n_Mot. Once the relevant gear  33  reaches the same speed, the gear clutch F can be engaged. Then the clutch K 1  transmitting the load in the original gear can be disengaged, and the clutch K 2  transmitting the load in the subsequent gear can be engaged. 
         [0063]    For three downshifts G 7 →G 6 , G 6 →G 5 , G 2 →G 1  and one upshift G 6 →G 7 , two gear clutches are engaged each time in the target gear, and one of the two gear clutches is always load-free. In these cases, the load-free gear clutch is engaged first before the speed of the other gear clutch is adapted. 
         [0064]    List of Reference Characters 
         [0065]      1  First gear shifting device 
         [0066]      2  Second gear shifting device 
         [0067]      3  Third gear shifting device 
         [0068]      4  Fourth gear shifting device 
         [0069]      5  Fifth gear shifting device 
         [0070]      6  Sixth gear shifting device 
         [0071]      7  Double clutch device 
         [0072]      8  Clutch basket 
         [0073]      9  Driveshaft 
         [0074]      10  Transmission input shaft 
         [0075]      11  Transmission input shaft 
         [0076]      12  Transmission output shaft 
         [0077]      13  Main shaft arrangement 
         [0078]      14  Countershaft arrangement 
         [0079]      15  Gear 
         [0080]      16  Gear 
         [0081]      17  Countershaft segment 
         [0082]      18  Gear 
         [0083]      19  Gear 
         [0084]      20  Countershaft segment 
         [0085]      21  Gear 
         [0086]      22  Gear 
         [0087]      23  Main shaft segment 
         [0088]      24  Gear 
         [0089]      25  Gear 
         [0090]      26  Main shaft segment 
         [0091]      27  Gear 
         [0092]      28  Gear 
         [0093]      29  Countershaft segment 
         [0094]      30  Gear 
         [0095]      31  Gear 
         [0096]      32  Gear 
         [0097]      33  Gear 
         [0098]      34  Gear 
         [0099]      35  Support wall 
         [0100]    A Gear clutch 
         [0101]    B Gear clutch 
         [0102]    C Gear clutch 
         [0103]    D Gear clutch 
         [0104]    E Gear clutch 
         [0105]    F Gear clutch 
         [0106]    G Gear clutch 
         [0107]    H Gear clutch 
         [0108]    I Gear clutch 
         [0109]    G 1  First gear 
         [0110]    G 2  Second gear 
         [0111]    G 3  Third gear 
         [0112]    G 4  Fourth gear 
         [0113]    G 5  Fifth gear 
         [0114]    G 6  Sixth gear 
         [0115]    G 7  Seventh gear 
         [0116]    G 8  Eighth gear 
         [0117]    G 9  Ninth gear 
         [0118]    G(W) Winding path gear 
         [0119]    K 1  First input clutch, friction clutch 
         [0120]    K 2  Second input clutch, friction clutch 
         [0121]    R Reverse gear 
         [0122]    Z 1  Gear set plane, gear set 
         [0123]    Z 2  Gear set plane, gear set 
         [0124]    Z 3  Gear set plane, gear set 
         [0125]    Z 4  Gear set plane, gear set 
         [0126]    Z 5  Gear set plane, gear set 
         [0127]    Z 6  Gear set plane, gear set 
         [0128]    ZR Reverse gear set plain, reverse gear set 
         [0129]    i_G Gear ratio 
         [0130]    i_Z Individual transmission ratio, gear set plane ratio 
         [0131]    n_Mot Motor rotational speed 
         [0132]    n_sync Synchronous rotational speed 
         [0133]    φ Step change