Patent Publication Number: US-2022212526-A1

Title: Power shiftable multi-gear transmission having freewheel

Description:
BACKGROUND 
     The invention relates to a power-shiftable multiple-gear transmission with a freewheel. Furthermore, the invention relates to the use of the power-shiftable multiple-gear transmission for electric vehicles and hybrid vehicles in the passenger car, utility vehicle and truck field. 
     DE 10 2016 212 867 A1 relates to a transmission for an electric drive, in particular for a motor vehicle. The transmission comprises an electric machine, a drive shaft and at least a first and a second gear stage. The first gear stage can be shifted via a first clutch, and the second gear stage can be shifted via a second clutch. The first clutch is closed by means of a mechanical spring in the normal state, and can be opened by way of a pressure build-up which is, in particular, hydraulic by means of a pump. The second clutch is open in the normal state and can be closed by way of a pressure build-up which is, in particular, hydraulic by means of a pump. In the case of the transmission, the first gear is engaged in the normal state of the first and second clutch, the first clutch being closed and the second clutch being open. In order to shift over the transmission into the second gear, the first clutch is opened and the second clutch is closed. 
     DE 10 2015 121 157 A1 relates to a hybrid drive train for a motor vehicle. The drive train comprises a first drive unit and a second drive unit. In order to change the two drive units, the drive train comprises two clutches. In one preferred embodiment, a gear set of a first transmission arrangement is configured to set up a first forward gear stage, it being possible for an idler gear of said gear set to be connected by means of a freewheel to the shaft which is assigned to said idler gear. 
     SUMMARY 
     According to the invention, a power-shiftable multiple-gear transmission with a driven input shaft and a shaft is proposed, in the case of which multiple-gear transmission a first gear stage and at least one second gear stage are configured which are configured in each case as spur gear toothing systems. At least one first power transmission element is arranged by means of a freewheel on the input shaft. By way of the solution which is proposed according to the invention, in the case of shifting operations under load, firstly the shifting quality is improved considerably, and secondly smoother running of the multiple-gear transmission which is proposed according to the invention can be achieved on account of the freewheel; the NVH (Noise Vibration Harshness) behavior is considerably improved. 
     In one development of the solution which is proposed according to the invention, the power-shiftable multiple-gear transmission is driven on the driven input shaft via at least one electric machine. 
     In one development of the power-shiftable multiple-gear transmission which is proposed according to the invention, the first gear stage is configured with a first transmission ratio i 1  by way of the first power transmission element, configured as a first pinion on the freewheel, and a first gearwheel, in each case in a manner comprising spur gear toothing systems. The second gear stage of the power-shiftable multiple-gear transmission which is proposed according to the invention has a second transmission ratio i 2 , and is produced by way of a second pinion which meshes with a second gearwheel. Here too, spur toothing systems are configured on the second pinion and on the second gearwheel. 
     In one development of the solution which is proposed according to the invention, the power-shiftable multiple-gear transmission has, moreover, a final gear stage which is formed by way of a differential gear. In combination with the first transmission ratio i 1  or the second transmission ratio i 2 , the final gear stage forms the first gear or the second gear of the power-shiftable multiple-gear transmission. 
     In the case of the power-shiftable multiple-gear transmission which is proposed according to the invention, the final gear stage is also provided with a spur gear toothing system, and comprises a third pinion and a third gearwheel which mesh with one another. The third gearwheel serves as drive for the differential, via which the torques and rotational speeds are distributed to the wheels. This solution is extremely space-saving and weight-saving. 
     In the case of the power-shiftable multiple-gear transmission which is proposed according to the invention, a first clutch is used within the context of the first gear stage and a second clutch is used within the context of the second gear stage. If the first clutch is closed, a first gear with a first transmission ratio i 1  is realized at the power-shiftable multiple-gear transmission. If the first clutch is open and the second clutch is closed, the power-shiftable multiple-gear transmission which is proposed according to the invention is shifted into a second gear within the context of the second gear stage. In the second gear, there is the second transmission ratio i 2 , that is to say a different transmission ratio in comparison with the first gear stage. 
     In the case of the power-shiftable multiple-gear transmission which is proposed according to the invention, the second gearwheel of the second gear stage and the third pinion of the final gear stage are arranged fixedly on the shaft for conjoint rotation. 
     The power-shiftable multiple-gear transmission is configured in such a way that a component of the first gear stage, for example the first gearwheel, is part of the first clutch, a part of the second gear stage, namely the second pinion, being a part of the second clutch. Secondly, the first gearwheel of the first gear stage and the second gearwheel of the second gear stage are configured in each case in a sleeve shape on the power-shiftable multiple-gear transmission which is proposed according to the invention. The first gearwheel of the first gear stage is mounted rotatably on the shaft. In contrast, the second gearwheel of the second gear stage is mounted fixedly on the shaft for conjoint rotation. On account of the alternately non-rotational and rotational mountings of the components of the first gear stage and the second gear stage, the power-shiftable multiple-gear transmission which is proposed according to the invention can be shifted via the two clutches in each case into the first gear and into the second gear, without further shifting components being required. Moreover, the invention relates to an E-axle module which can be configured as a front axle E-axle module or as a rear axle E-axle module, and is used in the case of an electrically driven or hybrid driven vehicle. 
     The power-shiftable multiple-gear transmission which is proposed according to the invention and is preferably driven on its driven input shaft by way of at least one electric machine is used on the E-axle module, whether intended for the front axle or whether intended for the rear axle of an electrically driven or hybrid driven vehicle. 
     Moreover, the invention relates to the use of the power-shiftable multiple-gear transmission in an E-axle module of an electrically driven or hybrid driven vehicle. 
     Advantages of the Invention 
     The power-shiftable multiple-gear transmission which is proposed according to the invention realizes a shifting concept with at least two spur gear pairs, with the result that at least a first transmission ratio i 1  and a second transmission ratio i 2  can be realized. In comparison with shifting concepts from the prior art, in the case of which, for example, planetary gear transmissions are shifted, the driving comfort in the case of a required power-shifting capability of the power-shiftable multiple-gear transmission can be improved considerably by way of the power-shiftable transmission which is proposed according to the invention. Moreover, a parking lock function can be realized on the power-shiftable multiple-gear transmission by way of the simultaneous actuation of the two clutches, whether they are actuated electrically, electromagnetically, mechanically, electrohydraulically or hydraulically, which has up to now required expensive solutions. 
     A considerable cost saving can be realized by way of the omission of the conventional parking lock actuator system. Flexible adaptations to installation spaces which are required by the customer can be realized by way of the circumstance that the first clutch for the first gear stage and the second clutch for the second gear stage are disconnected from one another. In comparison with solutions, in the case of which, for example, electric machines interact with planetary transmissions or are even integrated into them, a considerably higher shifting comfort and/or a considerable improvement of the driving comfort in the case of shifting operations can be realized. Moreover, the smooth running of the power-shiftable multiple-gear transmission which is proposed according to the invention can be improved considerably by way of the use of the freewheel, on which the first power transmission element in the form of the first pinion is received. Thus, for example, in the case of an engaged first gear stage, the second pinion does not corotate, as a result of which the smooth running which is reflected in the NVH (Noise Vibration Harshness) behavior is improved considerably. In the case of an engaged second gear stage, the first power transmission element in the form of the first pinion and the second gearwheel which meshes with it do not corotate, as a result of which, in the case of an engaged second gear stage and a deactivated first gear stage, the Noise Vibration Harshness behavior of the multiple-gear transmission which is proposed according to the invention is improved considerably. 
     The final gear stage which is also called a “final drive” is at the same time the differential gear. Since the gearwheel of the final gear stage drives the differential gear, installation space, weight and resulting costs can be saved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in greater detail in the following text on the basis of the drawing, in which: 
         FIG. 1  shows a first design variant of a power-shiftable multiple-gear transmission, with an electric machine, a differential and output shafts which branch off from the latter, 
         FIG. 2  shows a diagrammatic illustration of the power-shiftable multiple-gear transmission which is proposed according to the invention, with an output shaft, 
         FIG. 3  shows the power-shiftable multiple-gear transmission in accordance with the illustration in  FIG. 2 , with the individual gear stages and the two clutches which are disconnected from one another, 
         FIG. 4  shows the power-shiftable multiple-gear transmission with an illustrated power flow in the case of an engaged first gear stage, 
         FIG. 5  shows the resulting power flow in the power-shiftable multiple-gear transmission which is proposed according to the invention, in the case of an engaged second gear stage, and 
         FIG. 6  shows an E-axle module for an electric vehicle with a power-shiftable multiple-gear transmission, an electric machine, a differential and two driven wheels. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a power-shiftable multiple-gear transmission  12  which is proposed according to the invention and is driven by an electric machine  10 . The power-shiftable multiple-gear transmission  12  comprises a driven input shaft  14  and a shaft  16 . The input shaft  14  is driven by the electric machine  10 . A first gear stage  18  with a first transmission ratio i 1  is realized on the power-shiftable multiple-gear transmission  12 . The first gear stage  18  comprises a first power transmission element, configured as a first pinion  20  which is arranged on a freewheel  21  on the input shaft  14 , and a first gearwheel  22  which is firstly part of a first clutch  24  and secondly is arranged rotatably on the shaft  16 . As is apparent from the diagrammatic illustration according to  FIG. 1 , the shaft  16  penetrates the first gearwheel  22  of the first gear stage  18 , which first gearwheel  22  is advantageously of sleeve-shaped configuration here. 
     Furthermore, the power-shiftable multiple-gear transmission  12  in accordance with the diagrammatic illustration in  FIG. 1  comprises a second gear stage  26 . This is produced by way of a second pinion  28  which is part of a second clutch  32 . This meshes with a second gearwheel  30  which is arranged fixedly on the shaft  16  for conjoint rotation. 
     Moreover, a final gear stage  34  is provided on the power-shiftable multiple-gear transmission  12 . The final gear stage  34  which is also called a “final drive” is the differential  46  and, in combination with the first transmission ratio i 1  or the second transmission ratio i 2 , forms the first gear or the second gear of the power-shiftable multiple-gear transmission. The two-gear transmission which is shown might be expanded to more than the two gears which are shown. 
     As is apparent, furthermore, from the illustration according to  FIG. 1 , a third pinion  36  is received fixedly on the shaft  16  of the power-shiftable multiple-gear transmission  12  for conjoint rotation. Said third pinion  36  meshes with a third gearwheel  38  which is part of a differential  46 . 
     A first axle output  48  and a second axle output  50  run from the differential gear  46  to driven wheels (not shown in  FIG. 1 ) of an electrically driven vehicle. 
     In the case of the power-shiftable multiple-gear transmission  12  which is proposed according to the invention in accordance with the illustration in  FIG. 1 , all the toothing systems on the first power transmission element, that is to say on the first pinion  20 , on the first gearwheel  22 , the second pinion  28 , the second gearwheel  30 , the third pinion  36  and the third gearwheel  38 , are configured as spur toothing systems. As a result, the shifting capability under load can be influenced favorably in an advantageous way, and the smooth running can be improved considerably on account of the damping of vibrations which are produced within the power-shiftable multiple-gear transmission  12 . Secondly, the freewheel  21  avoids that the rotation of non-required components is avoided in accordance with the engaged first or second gear stage, which considerably improves the NVH (Noise Vibration Harshness) behavior of the power-shiftable multiple-gear transmission  12  which is proposed according to the invention. In the case of an engaged first gear stage  18 , the second pinion  28  does not rotate; in the case of an engaged second gear stage  26 , the first power transmission element, configured as a first pinion  20 , received on the freewheel  21 , and the first gearwheel  22  do not corotate, which likewise has a positive influence on the smooth running, that is to say the Noise Vibration Harshness behavior of the power-shiftable multiple-gear transmission  12  which is proposed according to the invention. 
       FIG. 2  shows a slightly modified design variant of the power-shiftable multiple-gear transmission  12  which is proposed according to the invention. 
     In the design variant according to  FIG. 2  of the power-shiftable multiple-gear transmission  12 , the first gear stage  18 , the second gear stage  26  and the final gear stage  34  are realized. In contrast to the design variant of the power-shiftable multiple-gear transmission  12  according to  FIG. 1 , a differential  46  which is part of the third gearwheel  38  in the variant according to  FIG. 1  is missing in the embodiment according to  FIG. 2 . Instead, starting from the third gearwheel  38  of the final gear stage  34 , an output shaft  60  extends to a drive component (not shown in further detail here) of a drive train. 
     The components of the first gear stage  18 , that is to say the first power transmission element, that is to say the first pinion  20 , the first gearwheel  22  and the first clutch  24 , are identical to the components of the first gear stage  18  according to  FIG. 1 . The same applies to the components of the second gear stage  26  in the design variant according to  FIG. 2 , and to the components of the final gear stage  34  apart from the absence of a differential gear  46  in the design variant according to  FIG. 2 . 
     The individual gear stages of the power-shiftable multiple-gear transmission  12  can be gathered from the illustration according to  FIG. 3 . 
     In an analogous manner to the above-described  FIGS. 1 and 2 , the illustration according to  FIG. 3  shows that the power-shiftable multiple-gear transmission  12  has the first gear stage  18 , the second gear stage  26  and the final gear stage  34 . Depending on the actuation of the first clutch  24 , that is to say the engagement of the first gear stage  18  or the actuation of the second clutch  32  in order to realize the second gear stage  26 , the final gear stage  34  is driven via the shaft  16 . This means that the first transmission ratio i 1  is realized in the first gear stage  18 , whereas the second transmission ratio i 2  is realized in the second gear stage  26 . There is a corresponding rotational speed in the final gear stage  34  in a manner which is dependent on the output rotational speed, at which the shaft  16  rotates. The first transmission ratio i 1  and the second transmission ratio i 2  are then designed in such a way that i 1  is greater than i 2  . As a result, the transmission ratio in the third final gear stage  34  is either given by i ges1 =i 1 ·i Endgang  in the case of an engaged first gear stage  18 , or the transmission ratio i ges2 =i 2 ·i Endgang  is present if the second gear stage  26  is engaged. 
     The illustration according to  FIG. 4  shows the power flow  62  which is set in the case of an engaged first gear stage  18  in the power-shiftable multiple-gear transmission  12  which is proposed according to the invention. 
     For the activation of the first gear stage  18 , the first clutch  24  is closed. The power flow  62  runs, starting from the input shaft  14  which is driven, for example, via the electric machine  10 , the open second clutch  32  to the first power transmission element, for example a first pinion  20 . This is received in the freewheel  21  on the driven input shaft  14 . The first power transmission element, configured as a first pinion  20 , drives the first gearwheel  22  in accordance with the power profile of the power flow  62 , which first gearwheel  22  transmits a rotation via the closed first clutch  24  to the shaft  16  which for its part drives the third pinion  36 , arranged fixedly on it, of the final gear stage  34 . The third pinion  36  which is arranged fixedly on the shaft  16  for conjoint rotation drives the third gearwheel  38  which in turn drives the output shaft  60 . In the shifting state shown in  FIG. 4  of the power-shiftable multiple-gear transmission  12  which is proposed according to the invention, there is the transmission ratio i ges1 =i 1 ·i Endgang . In order to realize the power flow  62  (cf. dashed illustration in  FIG. 4 ) within the first gear stage  18 , the first clutch  24  is closed, whereas the second clutch  32  is opened. In the shifting state, shown in  FIG. 4 , of the power-shiftable multiple-gear transmission  12  which is proposed according to the invention, a part of the second clutch  32  corotates, just like the second gearwheel  30  which does not transmit any torque and is driven fixedly on the shaft  16  for conjoint rotation, but does not transmit any torque. 
       FIG. 5  shows the power flow  62  which is set in the power-shiftable multiple-gear transmission  12  which is proposed according to the invention, in the case of an engaged second gear stage  26 . 
     In the illustration according to  FIG. 5 , the first clutch  24  is open, whereas the second clutch  32  is closed. 
     Starting from the driven input shaft  14 , the drive torque, for example of an electric machine  10 , is transmitted via the closed second clutch  32  to the second pinion  28 . From there, the torque is transmitted via a spur toothing system to the second gearwheel  30  which is arranged fixedly on the shaft  16  for conjoint rotation. By the shaft  16 , the torque is transmitted to the third pinion  36  which, within the context of a spur gear toothing pairing, meshes with the third gearwheel  38  of the final gear stage  34  and transmits the torque to the output shaft  60  in accordance with the power flow  62  according to  FIG. 5 . In the shifting state which is shown in  FIG. 5 , there is the transmission ratio i ges2 =i 2 ·i Endgang . According to  FIG. 5 , no torque is transmitted via the first power transmission element which is arranged by way of the freewheel  21  on the driven input shaft  14  to the first gearwheel  22  which can be rotated on the shaft  16 , since the first clutch  24  is open. In the case of an engaged second gear stage  26 , the first power transmission element in the form of the first pinion  20  and the second gearwheel  30  are at a standstill. As a result, the smooth running of the power-shiftable multiple-gear transmission  12  which is proposed according to the invention is influenced in a positive manner, since only those components which are required for the transmission of torque rotate. 
     For the realization of a parking lock function, the two clutches  24 ,  32  are closed on the power-shiftable multiple-gear transmission  12 , with the result that the power-shiftable multiple-gear transmission  12  is blocked, and neither the driven input shaft  14  nor the shaft  16  can be set in rotation. All of the components which mesh with the blocked input shaft  14  or the blocked shaft  16  are likewise blocked, with the result that no rotation can take place, and a parking lock function can be realized without the provision of further components in the power-shiftable multiple-gear transmission  12 . 
       FIG. 6  shows a diagrammatic illustration of an E-axle module which can be used on the rear axle or on the front axle of an electric vehicle. 
     It is apparent from the illustration according to  FIG. 6  that the E-axle module  78  which is shown comprises the above-described power-shiftable multiple-gear transmission  12  and an electric machine  10  which drives the latter. Moreover, the E-axle module  78  according to  FIG. 6  has the differential gear  46  which is part of a final gear stage  34 . From the differential gear  46 , a first axle output  48  extends to the first driven wheel  74 , whereas a second axle output  50  extends to a second driven wheel  76 . 
     The power-shiftable multiple-gear transmission  12  which is shown comprises two spur gear stages, namely the first spur gear stage  70  and the second spur gear stage  72 . In the case of the power-shiftable multiple-gear transmission  12  which is proposed according to the invention, two gears are realized independently of the spur gear stages  70 ,  72 . A relatively great axle offset or axle spacing from a motor input shaft to a transmission output shaft can be realized by way of the second spur gear stage  72 . By way of adaptation of the axle deflection angle which is produced by way of the arrangement of the transmission input shaft, the intermediate shaft and the output shaft, the installation space which the power-shiftable multiple-gear transmission  12  which is proposed according to the invention takes up can be adapted in a flexible manner. 
     It can be gathered from  FIG. 6  that the power-shiftable multiple-gear transmission  12  which is shown here is driven as part of an E-axle module  78  on the driven input shaft  14  via the electric machine  10 . The construction of the power-shiftable multiple-gear transmission  12  which is shown in  FIG. 6  and is integrated into the E-axle module  78  corresponds substantially to the construction of the power-shiftable multiple-gear transmission  12  in accordance with the design variant which is shown in  FIG. 1 . The power-shiftable multiple-gear transmission  12  which is proposed according to the invention comprises the first gear stage  18  and, furthermore, the second gear stage  26  which interact with the final gear stage  34  in accordance with their first transmission ratio i 1  and their second transmission ratio i 2 , respectively. Depending on which of the two clutches  24  and  32  is activated, either the first gear stage  18  with the first transmission ratio i 1  is active on the power-shiftable multiple-gear transmission  12  or, in the case of actuation of the second clutch  32 , the second gear stage  26  with the second transmission ratio i 2  is active. Depending on whether, in the case of corresponding actuation of the two clutches  24 ,  32 , the first gear stage  18  or the second gear stage  26  is engaged, a corresponding output rotational speed is set at the third pinion  36  of the final gear stage  34 . In a manner which is dependent on the engaged gear stage  18 ,  26 , there is either the transmission ratio i ges1 =i 1 ·i Endgang  in the final gear stage  34  if the first gear stage  18  is active. As an alternative, there is the possibility, in the case of a closed second clutch  32 , to perform the drive via the second gear stage  26  with the second transmission ratio i 2 . In this case, there is the abovementioned transmission ratio i ges2 =i 2 ·i Endgang  at the final gear stage  34 . 
     In the design variant which is shown in  FIG. 6 , the final gear stage  34  comprises the differential gear  46  which is integrated into the third gearwheel  38 . 
     In a modification of the design variant of the E-axle module  78  according to  FIG. 6 , instead of the power-shiftable multiple-gear transmission  12  which is shown there and drives the final gear stage  34 , the final gear stage  34  can be modified in such a way that the differential gear  46  is dispensed with and the third gearwheel  38  drives the output shaft  60  which is coupled rigidly to it, as is shown in the design variant according to  FIG. 2 . 
     In relation to the preceding  FIGS. 1 to 6 , it is to be noted that the first clutch  24  and the second clutch  32  can be actuated electrically or hydraulically and can be shifted independently of one another. In an advantageous way, in the power-shiftable multiple-gear transmission  12  which is proposed according to the invention, the first pinion  20  which serves as a first power transmission element is arranged in the freewheel  21 , and the second gearwheel  30  and the third pinion  36  are arranged in each case fixedly on the driven input shaft  14  or on the shaft  16  for conjoint rotation. In contrast, both the second pinion  28  and the first gearwheel  22  are of sleeve-shaped configuration and are designed in such a way that one part of the mentioned components at the same time represents a friction disk or a friction component for the first clutch  24  or the second clutch  32 . In an advantageous way, both the components of sleeve-shaped nature, the second pinion  28  and the first gearwheel  22 , are configured in such a way that the driven input shaft  14  and the shaft  16  extend through said components of sleeve-shaped configuration and thus make the realization of the different gear stages, a first gear stage  18  and second gear stage  26 , with the dedicated transmission ratios i 1 , i 2  possible. 
     The invention is not restricted to the exemplary embodiments which are described here and the aspects which are emphasized therein. Rather, within the scope specified by way of the claims, a multiplicity of modifications are possible which lie within the capabilities of a person skilled in the art.