Abstract:
A drive system includes a hydrodynamic coupling device having a housing assembly, which is to be connected to an input shaft for rotating therewith, and an output element, which is to be brought into drive connection with a transmission arrangement. The hydrodynamic coupling device also comprises an electric machine equipped with a rotor assembly, which is connected to the housing assembly for rotating therewith, and with a stator assembly, wherein the stator assembly is supported on a housing that surrounds the hydrodynamic coupling device at least in areas. The area of the housing which supports the stator assembly has a cooling medium channel arrangement.

Description:
TECHNICAL AREA  
         [0001]    The present invention pertains to a drive system comprising a hydrodynamic clutch device, especially a hydrodynamic torque converter, which has a housing arrangement to be connected to a drive shaft for rotation in common and a power takeoff element to be brought into drive connection with a transmission arrangement, where the drive system also comprises an electrical machine, comprising a rotor arrangement connected to the housing arrangement for rotation in common and a stator arrangement, where the stator arrangement is supported on a housing, which at least partially surrounds the hydrodynamic clutch device.  
         STATE OF THE ART  
         [0002]    A drive system is known from DE 199 45 475 A1, in which a rotor arrangement of the electrical machine is connected to the radially outer area of the housing arrangement of a hydrodynamic torque converter. For this purpose, a rotor bracket is welded to the housing arrangement. The stator arrangement is held in place on a nonrotating part such as the transmission.  
           [0003]    DE 100 48 838 A1 presents a similar drive system, in which the rotor arrangement is screwed to a drive shaft together with an element that connects the hydrodynamic clutch arrangement nonrotatably to the drive shaft. The stator arrangement is supported on a housing, which radially surrounds the outside of the hydrodynamic clutch device and which also carries the transmission.  
         TASK OF THE INVENTION  
         [0004]    The task of the present invention is to provide a drive system, which, although of simple and compact design, allows the efficiency of the electrical machine to be improved.  
         DESCRIPTION OF THE INVENTION  
         [0005]    According to the invention, the task is accomplished by a drive system comprising a hydrodynamic clutch device, especially a hydrodynamic torque converter, which has a housing arrangement to be connected to a drive shaft for rotation in common and a power takeoff element to be brought into drive connection with a transmission arrangement, where the drive system also comprises an electrical machine, comprising a rotor arrangement connected to the housing arrangement for rotation in common and a stator arrangement, where the stator arrangement is supported on a housing at least partially surrounding the hydrodynamic clutch device.  
           [0006]    In the drive system according to the invention, a coolant channel arrangement is provided in the housing in the area where the housing supports the stator arrangement.  
           [0007]    Because a coolant channel arrangement is provided in the area of the housing in which the stator arrangement is also supported, additional heat can be carried away from the area of the stator arrangement, to which current is generally supplied. This helps to improve the efficiency of the electrical machine during its operation. This improved efficiency is especially advantageous when the essential components of a drive system of this type are surrounded by a housing, which means that the amount of heat which can be carried away by the surrounding air is reduced.  
           [0008]    An especially easy-to-build arrangement, which also leaves a comparatively large amount of space free for the hydrodynamic clutch arrangement, can be provided by supporting the stator arrangement on a radially outer section of the housing. If the electrical machine is of the external rotor design, it is advantageous for an axially projecting stator support section to be provided on the housing; the stator arrangement can then be supported on the outer circumferential area of this support section.  
           [0009]    In the drive system according to the invention, furthermore, it is also possible for the coolant channel arrangement to be connected to an engine coolant circuit. Of course, a separate coolant circuit could also be provided just for the electrical machine.  
           [0010]    The housing is preferably a transmission housing.  
           [0011]    According to another aspect of the present invention, a drive system is provided, comprising a hydrodynamic clutch device, especially a hydrodynamic torque converter, which has a housing arrangement to be connected to a drive shaft for rotation in common and a power takeoff element to be brought into drive connection with a transmission arrangement, and also comprising an electrical machine, which itself comprises a rotor arrangement connected to the housing arrangement for rotation in common and a stator arrangement.  
           [0012]    According to the present invention, it is also provided that at least one preferably ring-shaped connecting element is attached to the housing arrangement, which element carries at least one connecting part, and that the rotor arrangement is supported on the minimum of one connecting element.  
           [0013]    In this design, therefore, a double function is assigned to the minimum of one connecting element, the connecting part or parts of which are to be connected to the drive shaft. This simplifies the design.  
           [0014]    It is also possible according to the invention for the minimum of one connecting element to have a rotor support section in the area radially outside the minimum of one connecting part.  
           [0015]    According to another aspect, the present invention provides a drive system comprising a hydrodynamic clutch device, especially a hydrodynamic torque converter, which comprises a housing arrangement to be connected to a drive shaft for rotation in common and a power takeoff element to be brought into drive connection with a transmission arrangement, and also comprising an electrical machine, which itself comprises a rotor arrangement connected to the housing arrangement for rotation in common and a stator arrangement.  
           [0016]    According to another aspect of the present invention, it is also provided in this drive system that the rotor arrangement is supported on at least one rotor support element connected by welding to the housing arrangement. This minimum of one rotor support element is connected by welding to the housing arrangement in at least two areas a certain axial distance apart.  
           [0017]    In this way a very stable connection is established between the rotor arrangement and the housing arrangement, so that, especially when torque is to be introduced via the rotor arrangement to the drive train, the deformations which could be caused by the forces acting in the area of the housing arrangement can be significantly reduced.  
           [0018]    With this design of the drive system according to the invention, it can also be provided that the rotor arrangement is essentially located axially between the minimum of two welded areas. 
       
    
    
       [0019]    The present invention is described in detail below with reference to the attached drawings on the basis of preferred embodiments:  
         [0020]    [0020]FIG. 1 shows a partial axial cross-sectional view of a first embodiment of a drive system according to the invention;  
         [0021]    [0021]FIG. 2 shows a view, corresponding to FIG. 1, of an alternative embodiment;  
         [0022]    [0022]FIG. 3 shows another view, corresponding to FIG. 1, of an alternative embodiment; and  
         [0023]    [0023]FIG. 4 shows another view, corresponding to FIG. 1, of an alternative embodiment. 
     
    
       [0024]    [0024]FIG. 1 shows a drive system according to the invention, designated  10  overall. This drive system  10  comprises a hydrodynamic clutch device in the form of a hydrodynamic torque converter  12 . The hydrodynamic torque converter  12  has a housing arrangement  14 , which in turn comprises a housing cover  16  and a pump wheel shell  18 . The housing cover  16  carries in its radially inner area a guide journal  20 , which is concentric to the axis of rotation A and can be inserted into an appropriately formed opening in a drive shaft (not shown), such as the crankshaft of an internal combustion engine. In addition, the housing cover  16  also carries a connecting element  22 , possibly designed with a ring-like shape, which is welded to the cover. This connecting element itself carries in its radially outer area, distributed in the circumferential direction around the axis of rotation A, several connecting parts  24 , which can be designed, for example, as nut elements. Into these, fastening screws  26  are screwed, by means of which the radially outer area of a connecting disk  28 , designed as, for example, a flexplate, is connected to the connecting element  22  and thus to the housing arrangement  14 . In its radially inner area, this connecting disk  28  is then screwed in the conventional manner to the drive shaft.  
         [0025]    On the side facing the interior  30  of the housing, the pump wheel shell  18  carries a plurality of pump wheel vanes  32 . In its radially inner area, the pump wheel shell  18  is rigidly connected to a pump wheel hub  36 , which extends through an end wall  34  of the housing.  
         [0026]    In the interior  30  of the housing, furthermore, a turbine wheel, designated  38  overall, is provided. The turbine wheel  38  comprises a turbine wheel shell  40 , which is connected in the radially inner area to a turbine wheel hub  42  and which carries a plurality of turbine wheel vanes  44 . The turbine wheel hub  42  can be connected nonrotatably in the conventional manner to a power takeoff element, such as a transmission input shaft (not shown), concentric to the pump wheel hub  36 , by means of a set of wedge-shaped teeth.  
         [0027]    A stator  48  is installed between the turbine wheel  38  and the pump wheel  46 , which comprises essentially the pump wheel shell  18 , the pump wheel vanes  32 , and the pump wheel hub  36 . The outer circumferential area of a stator ring  50  carries a plurality of stator vanes  52  and is supported in such a way via a freewheel arrangement  54  on a support element (not shown), such as a hollow support shaft, that it, together with the stator vanes  52 , is free to rotate in one direction around the axis of rotation A but is blocked from rotating in the other direction.  
         [0028]    It should also be pointed out that the hydrodynamic torque converter  12  has a bridging clutch arrangement, designated  56  overall, with a clutch piston  58 . This piston can be pressed toward the housing cover  16  by an appropriate increase in hydraulic pressure, so that, by way of a disk  60 , which is connected nonrotatably to the turbine wheel  38  and carries friction linings, a direct, mechanical, torque-transmitting connection can be established between the housing arrangement  14  and the turbine wheel  38  under at least partial “bridging” of the otherwise prevailing fluid circulation.  
         [0029]    The drive system according to the invention also has an electrical machine, designated  62  overall. The electrical machine  62  comprises a rotor arrangement  64 . This has, for example, a plurality of sheet-metal elements  66  resting against each other, which, in the example illustrated here, carry a plurality of permanent magnets  68  on their inner circumferential side. The rotor arrangement  64  is fastened to a rotor support element  70 , designed in the form of, for example, a ring, by means of, for example, several screw bolts  72 . In the exemplary embodiment shown in FIG. 1, the rotor support element  70  is connected in turn by welding to the radially outer, essentially axially oriented section  73  of the housing cover  16 .  
         [0030]    The axial end wall  34  of a housing  74 , which encloses the hydrodynamic torque converter  12  essentially completely, has an axially projecting stator support section  76 . This can be designed to extend continuously in a ring-like manner in the circumferential direction around the axis of rotation A, but it could also be made up of several sections. On an outer circumferential side of the stator support section  76 , a stator arrangement  78  of the electrical machine  62  is supported, which can have windings wound around a yoke in the conventional manner. In the present case, the stator arrangement  78  lies radially directly inside the rotor arrangement  64 , which means that the electrical machine  62  is designed in the manner of an external rotor machine.  
         [0031]    It can also be seen in FIG. 1 that a coolant channel arrangement  80  is provided in the stator support section  76 . This can be connected by a hose connection  82  to the engine coolant circuit, for example, but it can also be connected to a separate coolant circuit. By conducting coolant through the coolant channel arrangement  80 , it is ensured that the heat generated in the area of the electrical machine  62  is carried away. This is important especially in the case of the arrangement shown in FIG. 1, because here both the electrical machine  62  and the hydrodynamic torque converter  12  are essentially completely enclosed by the housing  74 , and thus it is essentially impossible for the ambient air to flow around them to dissipate the heat. The housing  74  can be, for example, a part of the housing of a transmission (not shown), which is to be brought into torque-transmitting connection with the main (drive) engine by the hydrodynamic torque converter  12 . On the axially open side, the housing  74  can be tightly screwed by several screw bolts  84 , for example, to an engine block  86  or the like.  
         [0032]    In the embodiment shown in FIG. 1, a very compact design is achieved, in which it is ensured that the hydrodynamic torque converter  12  can be connected in the conventional manner, that is, for example, by the use of a so-called flexplate, to the drive shaft. A torque can also be introduced by the electrical machine  62  into the drive train in order, for example, to start the main engine. Of course, a drive torque can also be supplied by the electrical machine  62 . When the main engine is running, electrical energy can then be recovered by the electrical machine  62 , which thus acts as a generator, and this energy can be stored in a battery.  
         [0033]    To assemble the arrangement shown in FIG. 1, it is possible to proceed by first attaching the stator arrangement  78  to the stator support section  76 . Then the rotor arrangement  64  is connected to the rotor support element  70 , which has already been welded to the housing arrangement  14 . Thus a preassembled unit is formed, which comprises the hydrodynamic torque converter  12  and the rotor arrangement  64 . This unit is then introduced into the housing  74  and connected to the transmission (not shown) for the transmission of torque. The module thus formed is then brought axially into position against the main engine, to the drive shaft of which the connecting disk  28  has already been attached. Then, by means of openings provided in, for example, the housing  74  or in the engine block, the screw bolts  26  can be inserted and tightened, and thus the solid connection of the housing arrangement  14  to the drive shaft is accomplished.  
         [0034]    A modified embodiment of the drive system  10  according to the invention is illustrated in FIG. 2. In the following, only the differences with respect to the embodiment described in reference to FIG. 1 will be discussed.  
         [0035]    First, it is possible to see that the stator arrangement  78  is no longer supported on a stator support section especially provided for it; instead, it is attached to a radially outer, approximately cylindrical area  88  of the housing  74  in such a way that it essentially overlaps the pump wheel shell  18  in the axial direction. The ring-like rotor support element  70  is now attached to the pump wheel shell  18  by means of welding, for example, and again carries in its radially outer area the rotor arrangement  64  with its permanent magnets  68 , which are now located radially on the outside. A machine of the internal rotor type is therefore obtained. The coolant channel arrangement  76  is now provided in the radially outer area  88  of the housing  74 ; this channel arrangement is open on the axially open side of the housing  74  and can therefore be connected very easily to the coolant circuit of the engine.  
         [0036]    Because, in the modified embodiment shown in FIG. 2, the stator arrangement  78  is connected directly to an area of the housing  74  surrounded by ambient air, it is possible to provide the stator arrangement  78  with a more effective cooling action.  
         [0037]    In the case of the embodiment shown in FIG. 3, which is essentially the same as that shown in FIG. 2, the ring-shaped rotor support element  70  is connected by welding not only at one axial end area to the housing arrangement  14 , i.e., to the pump wheel shell  18 . The ring-shaped rotor support element  70  is now also connected by welding to the housing arrangement  14  (i.e., the pump wheel shell  18  in the example shown here) at the other axial end area, that is, at the axial end area near the connection between the pump wheel shell  18  and the housing cover  16 . The rotor arrangement  64  is located essentially between these two axially offset welded areas. A very stable connection of the rotor arrangement  64  to the housing arrangement  14  is thus obtained without the danger of generating tilting torques or excessive deformations in the area of the housing arrangement  14 .  
         [0038]    Another modified embodiment of the drive system  10  according to the invention is shown in FIG. 4. Here, too, essentially only the differences with respect to the previous embodiments will be discussed.  
         [0039]    First, it can be seen that the electrical machine  62  in this embodiment is closer to the main engine, i.e., to the engine block  86  of that engine, and essentially overlaps the housing cover  16  of the housing arrangement  14  in the axial direction. The stator arrangement  78  is again attached to the radially outer, essentially cylindrical area  88  of the housing  74 . The rotor arrangement  64  is again radially inside the stator arrangement  78 , so that again an electrical machine  62  of the internal rotor type is obtained.  
         [0040]    It can be seen in FIG. 4 that the ring-shaped connecting element  22  is extended in the radially outward direction beyond the area where its carries the connecting parts  24 , and in this outer, extended area it forms a rotor support section  90 . The rotor arrangement  64  can then be attached by means of, for example, screw bolts again or the like to this rotor support section  90 , which can be in the form of a ring or which can be tongue-like with several projections. In this way, a very easy-to-construct and also very compact arrangement is created, in which, furthermore, very effective cooling can be provided for the stator arrangement.  
         [0041]    The present invention provides a drive system which, although compact, makes it possible to integrate a hydrodynamic clutch device, such as a hydrodynamic torque converter, and an effectively cooled electrical machine, which acts as a crankshaft starter-generator, in a single housing. It is obvious that various parts of the drive system according to the invention can be designed differently from the way shown in the figures. For example, the illustrated hydrodynamic torque converter is only one example of these types of torque converters. Of course, a fluid clutch could also be used in place of a torque converter. It is also obvious, for example, that, in the design variant shown in FIG. 1, the stator support section of the housing could be designed as a separate component instead of as an integral piece as shown. It is also obvious, furthermore, that the housing shown in the figures can be designed in various ways to adapt it to the various types of engine blocks and/or various transmission arrangements. This housing is preferably a part of the transmission housing, however, because of the simplicity of design and construction thus offered. It should also be pointed out, even though it is obvious, that the coolant channel arrangement can have various configurations with respect to the path of the channels, such as a meander-like configuration. Several coolant inlets and/or outlets can also be provided, as is also obvious.