Abstract:
A device for producing an operative connection between an internal combustion engine of a motor vehicle and a downstream transmission is described. The device is a substitute for a torque converter and can be designed as a wet clutch or a torsion damper. The installation space between the internal combustion engine and the transmission does not have to be redesigned. The only requirement for the installation of the device is to replace the transmission/engine control software.

Description:
[0001]     Priority to U.S. Provisional Patent Application Ser. No. 60/590,119, filed Jul. 22, 2004 is claimed, the entire disclosure of which is hereby incorporated by reference herein.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to a device for establishing power flow between an internal combustion engine and a transmission.  
       BACKGROUND  
       [0003]     It is known from the related art that a torque converter is located between an internal combustion engine and a downstream transmission—preferably an automatic transmission. This torque converter is composed of an outer housing which is composed of two housing shells. One housing shell is connected indirectly to the drive shaft/crankshaft of the internal combustion engine in a non-rotatable manner. The second housing shell faces the downstream transmission. The two shells are interconnected at their point of contact in an oil-tight manner, preferably by means of welding. Pump vanes are located in the shell on the transmission side. Due to the rotary motion of the torque converter, and because the interior of the housing is filled with oil, a toroidal flow results. This flow acts on a turbine, which is also provided with corresponding vanes. The result is rotary motion of the turbine. A stator which returns the oil. flow to the pump in a suitable manner is located in the radially interior region between the turbine and the pump.  
         [0004]     Since slippage always exists between the pump and the turbine, and this slippage results in a considerable loss of efficiency, torque converters have been equipped for decades with a converter lock-up clutch. In the closed state, this converter lock-up clutch is a non-rotatable connection between the housing and the transmission input shaft. A damper is often also located in the power flow from the internal combustion engine via the torque converter to the transmission input shaft to minimize rotational non-uniformities. This damper can be designed as a turbine damper or a pure torsion damper.  
         [0005]     A torque converter is therefore a very complex component, which also makes it expensive.  
       SUMMARY OF THE INVENTION  
       [0006]     The object of the present invention, therefore, is to provide a device for operatively connecting an internal combustion engine to a downstream transmission which is a more cost-effective means of achieving the object.  
         [0007]     In accordance with certain embodiments of the present invention, the installation space between the internal combustion engine and the transmission remain unchanged, i.e., an existing design implemented using a torque converter can be retained, the only difference being that the device according to the present invention is used instead of the torque converter.  
         [0008]     In accordance with an embodiment of the present invention, a device for operatively connecting an internal combustion engine in motor vehicles to a downstream transmission is provided. The device includes an enclosed housing having an axis of rotation. The enclosed housing is at least partially filled with oil, and is hydraulically connectable to an oil pump located outside the enclosed housing. The enclosed housing includes a first housing shell on an engine side of the device and a second housing shell on a transmission side of the device. The first and second housing shells are interconnected in an oil-tight manner. The first housing shell is non-rotatably connected to a driveshaft/crankshaft of the internal combustion engine via a driving disk. A concentric opening is provided on the transmission side of the second housing shell for receiving in a transmission input shaft of the downstream transmission. A hub is located in the interior of the enclosed housing, and the transmission input shaft is non-rotatably connectable to the hub. A piston located in the interior of the enclosed housing. The piston is located concentrically to the axis of rotation of the enclosed housing and is axially displaceable along said axis. A plurality of friction disks are located in a power flow between the housing and the hub, wherein the friction disks can be pressed against each other, directly or indirectly, by the piston, by way of which pressing the power flow between the enclosed housing and the transmission input shaft is controlled.  
         [0009]     According to the present invention, to adapt the engine speeds to the rotational speeds of the transmission input shaft, slippage is allowed to occur briefly between the disks of the disk assembly during rotation. The heat which develops as a result is dissipated via an oil cooling system. In this case, it is advantageous when the device according to the present invention is used as a substitute for a torque converter, since a considerable amount of heat is also produced with a torque converter and an external oil pump is therefore also provided for it, the oil pump ensuring continuous oil exchange in the converter. The heated oil is directed to an oil cooling system and at least a portion of it is pumped back to the converter. For this reason, the device according to the present invention—as is the case with a torque converter—may be provided with a pump neck which engages in an oil pump on the transmission side. In a further embodiment of the present invention, a pump neck is not required, however, since, in this case, the oil pump is operated independently of the engine speed, e.g., using an oil pump driven by an electric motor. In a special case of the means of achieving this object, the amount of oil pumped by the oil pump—which is independent of engine speed—can be changed as a function of the temperature which the oil has when it exits the device according to the present invention.  
         [0010]     The non-rotatable coupling of the device according to the present invention with the internal combustion engine can take place using a flywheel, whereby the flywheel is mounted non-rotatably on the drive shaft/crankshaft of the internal combustion engine, and the device is also fixed in position, non-rotatably, on this flywheel. The coupling may also be implemented using a flexible disk (i.e., a disk with a low intrinsic mass). A flexible disk of this type is often referred to in the industry as a “flexplate.” 
         [0011]     The devices according to the present invention include two preferred embodiments. In a first embodiment, the device is implemented as a wet clutch. In a second embodiment, it is implemented as a torsion damper. These differences will be explained in greater detail in conjunction with the description of the figures. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The invention will be explained in greater detail below with reference to the figure description.  
         [0013]      FIG. 1  shows a cross section through a wet clutch according to the present invention having a radially outwardly located damper and two discharge devices;  
         [0014]      FIG. 2  shows two oil circuits based on  FIG. 1 ;  
         [0015]      FIG. 3  shows an oil ring based on  FIGS. 1 and 2 ;  
         [0016]      FIG. 4  shows a further embodiment of  FIGS. 1 through 3  having a pair of disks as the oil return device;  
         [0017]      FIG. 5  shows a further wet clutch according to the present invention with a damper in the center region of the diameter;  
         [0018]      FIG. 6  shows a perspective sectional illustration based on  FIG. 5 ;  
         [0019]      FIG. 7  shows a torsion damper according to the present invention;  
         [0020]      FIG. 8  shows a front view of a friction disk;  
         [0021]      FIG. 9  shows a partial view Z from  FIG. 8 . 
     
    
     DETAILED DESCRIPTION  
       [0022]     First, it should be noted that because the components shown in the figures are largely rotationally symmetrical, circular edges result. Since these edges would greatly impair the clarity of the drawing, they have been largely omitted from the figures.  
         [0023]     A device according to the present invention is shown in  FIG. 1 , the device being designed as a wet clutch. This wet clutch is enclosed in a housing  1 . Housing  1  is composed essentially of a housing shell  2  on the engine side and a housing shell  3  on the transmission side. Shells  2  and  3  are connected to a weld  23 . Housing  1  having a driving disk  4  (flywheel, flexplate, dual-mass flywheel), which is not shown in  FIG. 1 , is connected in a non-rotatable manner by a plurality of fastening lugs  21  (only one of which is shown in  FIG. 1 ) to a drive shaft/crankshaft  5 , which is also not shown in  FIG. 1 . Housing  1  is guided in a concentric recess of drive shaft/crankshaft  5  using a guide device  22 . Housing shell  3  on the transmission side is non-rotatably connected to a pump neck  11  in the region of a concentric opening  6 . Pump neck  11  engages in an oil pump  12 , which is not shown in  FIG. 1 . Oil pump  12  is driven by the rotary movement of housing  1  around an axis of rotation  7 .  
         [0024]     The illustrated wet clutch is provided with a damper. The damper shown here is located in the radially outward region of the wet clutch. Drivers (e.g., cams stamped in housing  1 ), which are not shown in  FIG. 1 , rest against one end of damping spring  13 . Damping springs  13  are designed in this case as curved spiral coiled springs which rest in a slide channel  25 . The other ends of springs  13  act on an outlet part  18  which is in turn interlocked with a first disk carrier  14 . Disks (friction disks)  8  are located between this first disk carrier  14  and a second disk carrier  15 . Disks  8  are interlocked, in an alternating manner, with either disk carrier  14  or disk carrier  15  and are axially displaceable. Disk carrier  15  is non-rotatably connected to a hub  16 . Hub  16  has a multi-toothed profile (not shown) which is complementary with the multi-toothed profile of transmission input shaft  10 .  
         [0025]     As shown in  FIG. 1 , transmission input shaft  10  has a bore extending through it. Via this bore, a pumped flow of oil (further details are provided in  FIG. 2 ) travels between housing shell  2  on the engine side and a piston  9 . Piston  9  is sealed off from input shaft  10  via an inner gasket  24  and is sealed off from an annular shell  27  via an outer gasket  24 . Annular shell  27  is connected to housing shell  2  on the engine side, e.g., via laser welding. If oil pressure now increases between housing shell  2  on the engine side and piston  9 , piston  9  presses indirectly against disks  8 , since the piston acts on a right-angle bend of disk carrier  14 . As the pressure of piston  9  increases, the friction torque in the clutches ultimately increases in such a way that full engine torque and engine speed are transferred to transmission input shaft  10 .  
         [0026]     To ensure that oil can also be directed over disks  8  without using a further oil passage, piston  9  has a point of restriction  20  which may be designed, e.g., as a stamped-out area. As a result of point of restriction  20 , the oil pressure to the left of piston  9  is substantially maintained, while still allowing oil cooling for disks  8  to be implemented.  
         [0027]     To make it possible for the oil supplied to the wet clutch to be returned to pump  12  before it overheats, two return devices  19   a ,  19   b  retained by a support sleeve  26  are provided in this exemplary embodiment. Support sleeve  26  can be mounted on the wall of a transmission, for example, similar to the support tube for the stator in the case of torque converters.  
         [0028]     As mentioned above, the oil circuits in the wet clutch are explained with reference to  FIG. 2 . An oil flow coming from oil pump  12  is pumped via hollow transmission input shaft  10  in the region between housing shell  2  on the transmission side and piston  9 . The piston force increases as a result, and oil flow for disks  8  is implemented via point of restriction  20 . To ensure that a good oil supply is possible over preferably all friction surfaces of disks  8 , disk carriers  14  and  15  have a plurality of radial passages.  FIG. 2  should therefore not be misunderstood to mean that the flow of oil is directed only over the friction surfaces in the center of the disk assembly, as indicated by the arrow. After the oil flows out of the disk assembly, it enters the radially outward region of housing  1 —due to the centrifugal force produced by the rotary motion of the wet clutch—where it lubricates the relative motions of damping spring  13  and slide channel  25 .  
         [0029]     As a result of the centrifugal force, an oil ring  28  forms in the radially outward region of the wet clutch, as shown in  FIG. 3 . Due to return devices  19   a ,  19   b,  which are designed as discharge tubes and are arranged in the shape of a spiral relative to axis of rotation  7 , the oil is pumped either into the region of concentric opening  6  or essentially to the inner diameter of disk carrier  14 . Return devices  19   a ,  19   b  shown here are configured in the shape of a spiral because rotating oil ring  28 , due to its kinetic energy, impacts the inlet openings which are located radially outwardly and are not rotating. As a result, the oil is then “screwed” radially back into the interior.  
         [0030]     A further embodiment of return device  19   a ,  19   b  is disclosed with  FIG. 4 . Return device  19   a ,  19   b  is composed of two parallel disks having an annular passage between them. At their outer diameters, these disks form an inlet opening for the oil to be pumped between pump neck  11  and back to support sleeve  26 . This functions in this manner because air is also enclosed in the wet clutch and, therefore, when new oil flows in, the excess oil between the disks of return device  19   a  is pressed out.  
         [0031]     The damper shown in  FIG. 5  has a different design from the damper shown in  FIGS. 1 through 4 . In  FIG. 5 , springs  13  are located downstream from disks  8  in the power flow from housing  1  to hub  16 . This means that the inner disk carrier  15  acts on an inlet part  17 . Inlet part  17 , in turn, acts on one end of the springs, while the other end of the springs bears against outlet part  18 . Since springs  13  in this illustration are not located directly in the section plane, but rather behind the section plane, they look like diagonally positioned cylinders. This cylindrical appearance is also due to the fact that springs  13  do not have a curved design in this case, as in  FIGS. 1 through 4 , but rather have a substantially cylindrical shape. The purpose of  FIG. 5  is to show that the device according to the present invention may also be equipped with this type of damper.  
         [0032]     With regard to the exemplary embodiment in  FIG. 5 , it should be emphasized that piston  9  does not press disks  8  directly, nor does it act directly on disks  8  via a disk carrier  14 ,  15 . Instead, an additional component  29 , e.g., designed as a pressure plate or disk spring, exerts the compression force of piston  9  on disks  8 .  
         [0033]      FIG. 6  is provided as a supplement to  FIG. 5 , with the aim of better illustrating the spiral-shaped character of return devices  19   a  and  19   b .  
         [0034]     The embodiment of the device according to the present invention shown in  FIG. 7  is an adjustable torsion damper. It is clear in this case as well that this damper may be considered to be a substitute for a torque converter, since it is fixed in position to drive shaft/crankshaft  5  with the aid of a driving disk  4  (shown as a flexplate here), as is the case with a torque converter, and power is output via multi-toothed profile  32  into transmission input shaft  10 . As is the case with the torque converter, pump neck  11  is also provided here, and it also engages in an oil pump  12 . The outlines on the right side of the figure, which are not described in greater detail, represent the outer wall of a transmission on the engine side. This adjustable torsion damper is therefore also located in the power flow between the internal combustion engine and a transmission—preferably an automatic transmission.  
         [0035]     As indicated in the drawing, the power flow in this case travels via housing  1  and the indicated drivers (dashed lines) to the one end of springs  13 . Springs  13  are arranged in two layers in this case. This means that an inner spring  13  is additionally located in an outer spring  13 . In this case as well, springs  13  are located in the radially outward region of the torsion damper and slide on a slide channel  25 . Outlet part  18  acts on the other end of the springs. The arrangement of disk carriers  14 ,  15  and, therefore, disks  8 , is an unusual feature in this design, because outer disk carrier  14  is connected to outlet part  18  via a weld  23 . Since inner disk carrier  15  is connected to housing shell  3  on the transmission side using a joint composed of rivet buttons, when disks  8  are pressed together (when piston  9  acts on them), it is no longer possible for relative rotary motion to take place between outlet part  18  and the housing. In other words: The power flow would then be through housing  1 , disk carriers  14 ,  15  and disks  8  to outlet part  18 . If piston  9  is pressed weakly against disks  8 , only a portion of the rotary motion of outlet part  18  relative to housing  1  is captured and converted to thermal energy.  
         [0036]     If one considers the further flow of power in this torsion damper, one recognizes that a central component—a piston centering device  30 —is non-rotatably connected to outlet part  18 . Since a multi-toothed profile  32  is also provided on the central component, which serves simultaneously as a piston centering device  30  in this case, this establishes a non-rotatable connection with transmission input shaft  10 .  
         [0037]     From the perspective of damping and, therefore, the conversion of rotational vibration energy into thermal energy, it follows that, if disks  8  are not pressed together and if disks  8  are pressed tightly together (no relative motion between disks  8 ), damping cannot occur.  
         [0038]     Since transmission input shaft  10  is hollow in design, oil can be pumped via a radial bore between outlet part  18  and piston centering device  30  using an insert  33 . To enable oil to flow here—since outlet part  18  and piston centering device  30  are interconnected via a riveted joint  31 —oil guide grooves are provided in at least one of these parts (created via stamping, for example). In this manner, oil may be pumped into the chamber between outlet part  18  and piston  9 . If the oil pressure subsides, a return spring  34  ensures that the piston lifts away from disks  8 . (Reference numerals in  FIG. 7  which are not discussed have the same significance as in the other figures.)  
         [0039]     It is apparent from  FIG. 7  that insert  33  does not completely fill the interior of transmission input shaft  10 . A second oil flow is therefore feasible, which exits at the left end of transmission input shaft  10  in this case and then flows along between housing shell  2  on the engine side and outlet part  18 , and is subsequently redirected in the region of springs  13 . Using appropriate return devices  19   a ,  19   b  (as described initially), the oil may also be pumped over disks  8 . This oil, which is used as coolant, could subsequently flow in the gap between pump neck  11  and transmission input shaft  10 . A reverse flow of pumped cooling oil would also be feasible within the framework of the present invention.  
         [0040]     Finally, it should be stated that a dual-channel oil pumping system is tacitly assumed in the exemplary embodiments shown in  FIGS. 1 through 7 . Since the described wet clutches and torsion damper are intended to substitute for torque converters, but there are also torque converters which have not only two passages for their oil circulation, but also a third passage for actuating the converter lock-up clutch, it is also feasible within the framework of the present. invention to use a three-passage system of this type in this application. The exemplary embodiments in  FIGS. 1 through 7  would then need to be adapted accordingly to this application.  
         [0041]     Shown in  FIGS. 8 and 9  (which is detail Z from  FIG. 8 ) is a friction disk  8  which is positioned on an inner disk carrier  14 ,  15  in a torsion-proof but axially displaceable manner via its internal toothing  37 . A friction lining  39  is located in an annular shape on the carrier material of disk  8 . Friction lining  39  is composed of individual segments which are joined at an S-shaped contact line  40 . The carrier material of disks  8  has longitudinal slots  38  outside of the region of the friction lining, which allow oil to flow in an axial direction. Oil grooves  35 ,  36  are provided in friction lining  39 . Oil grooves  35 ,  36  may be impressed in friction lining  39 , for example. The special arrangement and shape of oil grooves  35 ,  36  are advantageous, however. Oil grooves  35  form a curve which starts at the inner diameter of friction lining  39  and also ends here. Oil grooves  35  have a larger cross-sectional area than oil grooves  36 , which essentially contact the curve of oil grooves  35  at an acute angle. Oil grooves  36  also create a flow connection to the outer diameter of friction lining  39 . Their orientation relative to large oil groove  35  may also point in the other direction (i.e., other than the direction shown), depending on the direction of rotation of this friction lining relative to the adjacent friction lining and on how the oil is to be pumped via the entrainment effect from the outside to the inside or from the inside to the outside.  
       LIST OF REFERENCE NUMERALS  
       [0000]    
       
           1  Housing  
           2  Housing shell on engine side  
           3  Housing shell on transmission side  
           4  Driving disk  
           5  Drive shaft/crankshaft  
           6  Concentric opening  
           7  Axis of rotation of the housing  
           8  Disks/friction disks  
           9  Piston  
           10  Transmission input shaft  
           11  Pump neck  
           12  Oil pump  
           13  Damper spring (spiral coiled spring)  
           14  Disk carrier  
           15  Disk carrier  
           16  Hub  
           17  Inlet part  
           18  Outlet part  
           19  Return device  
           20  Point of restriction in the piston  
           21  Fastening lug  
           22  Guide device (tab or sleeve)  
           23  Weld  
           24  Gasket  
           25  Slide channel  
           26  Support sleeve  
           27  Annular shell  
           28  Oil ring  
           29  Pressure plate/disk spring  
           30  Piston centering device  
           31  Riveted joint  
           32  Multi-toothed profile  
           33  Insert  
           34  Return spring  
           35  Oil groove  
           36  Oil groove  
           37  Internal teeth of disks  
           38  Slot  
           39  Friction lining  
           40  Contact line