Abstract:
The invention relates to a hybrid drive-train of a motor vehicle ( 1 ) equipped with a mechanical all-wheel drive, said drive-train comprising a combustion engine ( 5 ) which can be drive-connected to two axles ( 5 ) by means of a transmission ( 6 ), and a transversally installed electric machine arrangement ( 10 ). In order to improve the hybrid drive-train, particularly with regard to an operational mode that is highly dynamic, the electric machine arrangement is arranged approximately central in relation to the transverse direction of the vehicle.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a hybrid drive train of a motor vehicle which is equipped with a mechanical all-wheel drive, having an internal combustion engine which can have a drive connection to two axles via a transmission, and having a transversely installed electric machine arrangement. 
     2. Description of the Related Art 
     The object of the invention is to improve a hybrid drive train according to the preamble of claim  1 , in particular with respect to a highly dynamic driving style. 
     The object is achieved in a hybrid drive train of a motor vehicle which is equipped with a mechanical all-wheel drive, having an internal combustion engine which can have a drive connection to two axles via a transmission, and having a transversely installed electric machine arrangement, in that the electric machine arrangement is arranged approximately centrally in the transverse direction of the vehicle. The terms transverse and transverse direction relate to a motor vehicle having the hybrid drive train. The electric machine arrangement can be assigned alone or together with the internal combustion engine to a front axle or a rear axle of the motor vehicle. The approximately central arrangement of the electric arrangement considerably reduces the expenditure in terms of manufacturing in order to implement the motor vehicle as a right-handed steered or left-handed steered vehicle. 
     SUMMARY OF THE INVENTION 
     One preferred exemplary embodiment of the hybrid drive train is characterized in that a crown wheel of a bevel gear drive is attached to a rotor of the electric machine arrangement. The rotor of the electric machine arrangement can be coupled to the internal combustion engine via the bevel gear drive. Alternatively, the crown wheel of the bevel gear drive is attached to a transmission arranged downstream of the electric machine arrangement, for the purpose of coupling the electric machine arrangement to the internal combustion engine. When a spur gear drive which is arranged downstream of the electric machine arrangement is used, the crown wheel of the bevel gear drive can also be mounted on a lay shaft with a spur gear of the spur gear drive in order to couple the electric machine arrangement to the internal combustion engine. This requires only slight modifications in the configuration in order to permit coupling of the electric machine arrangement to the internal combustion engine. 
     A further preferred exemplary embodiment of the hybrid drive train is characterized in that a differential, which is preferably partially locked or can be locked in a controlled fashion, is assigned to the electric machine arrangement. As a result, in the case of a highly dynamic driving style it is also ensured that the power of the electric machine arrangement can be utilized in an optimum way. 
     A further preferred exemplary embodiment of the hybrid drive train is characterized in that the electric machine arrangement comprises an internal rotor electric machine with a rotor and a stator which is divided in two and comprises two stator halves which are spaced apart from one another in the transverse direction. According to one exemplary embodiment, the electric machine arrangement comprises precisely one internal rotor electric machine. The two stator halves are preferably energized equally during operation. 
     A further preferred exemplary embodiment of the hybrid drive train is characterized in that a device for outputting and/or distributing torque is arranged between the two stator halves, which device comprises, for example a crown wheel of a bevel gear drive and/or a differential. The device for outputting or distributing torque is preferably arranged centrally in the transverse direction of the vehicle. 
     A further preferred exemplary embodiment of the hybrid drive train is characterized in that the two stator halves comprise windings which are connected to one another. This provides the advantage that only one power electronic system is required to operate the electric machine. 
     A further preferred exemplary embodiment of the hybrid drive train is characterized in that the electric machine arrangement comprises an external rotor electric machine having a rotor to which a crown wheel of a bevel gear drive is attached. According to one exemplary embodiment, the electric machine arrangement comprises precisely one external rotor electric machine. 
     A further preferred exemplary embodiment of the hybrid drive train is characterized in that the rotor can have a drive connection to a transmission input shaft via a clutch. When the clutch is closed, a torque can be transmitted from the rotor to the transmission input shaft, or vice versa. 
     A further preferred exemplary embodiment of the hybrid drive train is characterized in that the rotor can have a drive connection to a differential via a clutch. A torque can be transmitted via the clutch and the differential from the rotor to driven wheels of the motor vehicle. 
     If the rotor can have a drive connection to the transmission input shaft via a first clutch and to the differential via a second clutch, it is possible to charge a battery of the motor vehicle in the stationary state by means of the electric machine. 
     A further preferred exemplary embodiment of the hybrid drive train is characterized that the electric machine arrangement comprises two electric machines which are spaced apart from one another in the transverse direction and between which a device for outputting and/or distributing torque is arranged, which device comprises, for example, a crown wheel of a bevel gear drive and/or a differential. The two electric machines are preferably embodied as internal rotor electric machines. The device for outputting and distributing torque is preferably arranged centrally in the transverse direction of the vehicle. 
     The invention also relates to a motor vehicle having a hybrid drive train which is described above. 
     Further advantages, features and details of the invention can be found in the following description in which various exemplary embodiments are described in particular with reference to the drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a highly simplified illustration of a motor vehicle with a hybrid drive train according to the invention. 
         FIG. 2  shows an enlarged detail from  FIG. 1  according to a further exemplary embodiment. 
         FIG. 3  shows a detail from  FIG. 1  according to a further exemplary embodiment with a stator divided in two. 
         FIG. 4  shows a detail from  FIG. 1  with an electric machine arrangement which comprises two electric machines. 
         FIG. 5  shows an enlarged detail from  FIG. 3  according to further exemplary embodiments. 
         FIG. 6  shows a simplified illustration of a gantry transmission. 
         FIG. 7  shows a simplified illustration of a planetary gear mechanism. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1 , a motor vehicle  1  having a hybrid drive train  2  is illustrated in a highly simplified form. The motor vehicle  1  is also referred to as a hybrid vehicle. A forward direction of travel of the motor vehicle  1 , which coincides with the longitudinal direction of the vehicle, is indicated by an arrow  3 . 
     The hybrid drive train  2  comprises an internal combustion engine  5  and a transmission  6 . A center tunnel  8 , in which a Cardan shaft  9 , which forms a drive connection between the transmission  6  and an electric machine  10 , is arranged proceeds from the transmission  6 . 
     The electric machine  10  is embodied as an external rotor with a stator which is arranged within a rotor. The Cardan shaft  9  is coupled via a bevel gear drive  12  with the rotor of the electric machine  10 . The bevel gear drive  12  comprises a crown wheel  14 , which is attached directly to the outside of the rotor of the electric machine  10 . 
     In  FIG. 1 , the electric machine  10  is arranged in the region of a front axle of the motor vehicle  1  with axle shafts  15 ,  16 . Driven wheels (not illustrated) of the front axle are attached to the free ends of the axle shafts  15 ,  16 . The internal combustion engine  5  is arranged in the region of a rear axle of the motor vehicle  1 . The Cardan shaft  9  rotates with the output rotation speed of the transmission  6  during operation. 
       FIG. 2  illustrates a detail from  FIG. 1  according to an exemplary embodiment, in which exemplary embodiment the Cardan shaft  9  is equipped with a clutch  18 . The drive connection between the transmission  6  and the electric machine  10  can be interrupted if required by means of the clutch  18 . 
       FIG. 3  illustrates in highly simplified form a hybrid drive train  22  with an internal combustion engine  25  and a transmission  26 . The transmission  26  has a drive connection to a rotor  34  of an electric machine  35  via a transmission input shaft  28  and a bevel gear drive  30  which comprises a crown wheel  31 . 
     The electric machine  35  is embodied as an internal rotor with a stator  40  which is divided into two stator halves  41 ,  42 . The crown wheel  31  is attached directly to the rotor  34  of the electric machine  35 . In this context, the crown wheel  31  is arranged centrally between the two stator halves  41  and  42 . 
     A clutch  44  is connected between the transmission  26  and the bevel gear drive  30 . A clutch  45  is connected between the rotor and a differential  48 , via which two driven wheels are driven. The two clutches  44 ,  45  can be installed alternately or together in the hybrid drive train  22 . 
     If the clutch  44  is opened in  FIG. 2  and at the same time the clutch  44  is closed, batteries of the motor vehicle can be charged via the electric machine  35  by the running internal combustion engine when the motor vehicle is stationary. This charging mode is also referred to as stationary charging mode. 
     In order to drive electrically, the clutch  44  is opened and the clutch  45  is closed. In order to form a mechanical all-wheel operating mode, the clutch  44  is operated closed with controlled slip. 
       FIG. 4  illustrates an electric machine arrangement  50  with two electric machines  51 ,  52  in a highly simplified form. The two electric machines  51 ,  52  are embodied as internal rotors and are installed in the transverse direction of the vehicle. Each of the electric machines  51 ,  52  comprises a stator  53 ;  55  and an internally running rotor  54 ;  56 . 
     A differential  58  is arranged between the two electric machines  51 ,  52 . Two axle shafts  59 ,  60  can be driven via the differential  58 . The two axle shafts  59 ,  60  can alternatively also each be driven directly by the rotors  54 ,  56  of the two electric machines  51 ,  52 . 
     A crown wheel  61  is coupled to the two rotors  54 ,  56  of the two electric machines  51 ,  52 . A further crown wheel  62 , which is coupled to the rotor  54 , is indicated on the side of the rotor  54  facing away from the differential  58 . 
     A dashed border  64  indicates a further exemplary embodiment with just one electric machine  51 . In this exemplary embodiment, the crown wheel  61  is arranged on one side of the rotor  54 , and the differential  58  is arranged on the other side of the rotor  54 . 
     In the exemplary embodiment  64 , the electric machine  51  is arranged centrally in the transverse direction of the vehicle. In the exemplary embodiment illustrated in  FIG. 4  with the two electric machines  51 ,  52 , the differential  58  or the crown wheel  61  is arranged centrally in the transverse direction of the vehicle. 
       FIG. 5  illustrates a detail from  FIG. 3  in enlarged form, according to further exemplary embodiments.  70  indicates a connection by which windings of the two stator halves  41 ,  42  are connected to one another. The two stator halves  41 ,  42  are energized equally. The connection  70  extends in a U shape around the crown wheel  31 . The coupling of the crown wheel  31  to the bevel gear drive occurs at a side facing away from the connection  70 . 
     On the side of the rotor  34  facing away from the connection  70 , that is to say at the bottom in  FIG. 5 , a planetary differential  74  is indicated, by means of which axle shafts can be coupled to the rotor  34 . At the end of the rotor  34  which is on the left in  FIG. 5  a normal differential  78  is indicated, by means of which the axle shafts can be coupled to the rotor  34 . 
     The term “can be coupled” means can have a drive connection in conjunction with the differential. 
     The exemplary embodiments illustrated in  FIGS. 1 to 5  all relate to a hybrid vehicle having at least one electric machine which is installed transversely with respect to the direction of travel. One of the axles is driven by the internal combustion engine. The other axle can be driven by the electric machine via the bevel gear drive. 
     The electric machine is connected mechanically here to the transmission input shaft or the internal combustion engine or to the transmission output shaft. As a result, a mechanical all-wheel drive which can be used universally is provided for a hybrid vehicle with a front-mounted engine arrangement, rear-mounted engine arrangement or center-mounted engine arrangement. 
     The gantry transmission indicated in  FIG. 6  allows the respective electric machine to be positioned lower, than in the case of a direct arrangement, in order to shift the center of gravity. 
       FIG. 7  indicates a planetary gear mechanism such as can be used for illustrating the planetary differential  74  in  FIG. 5 .