Abstract:
A hydrodynamic torque converter wherein the housing is connected to the output element of an engine in the power train of a motor vehicle and receives a coaxial hub which is rotatable by the turbine wheel in the housing or by a clutch disk forming part of a lockup clutch and being axially movably but non-rotatably mounted on the hub. The lockup clutch further comprises a piston which is rotatably and axially movably mounted on the hub, and a laimina which is non-rotatably but axially movably mounted in the housing and extends radially inwardly between the piston and the clutch disk. The clutch is engaged when the piston is moved axially of the housing to thus urge the lamina against the clutch disk and to thus bias the clutch disk against an adjacent wall of the housing so that the clutch disc then transmits torque between the housing and the hub to thus bypass the torque transmitting connection between the housing and the hub by way of a satator wheel in the housing and the turbine wheel.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a hydrodynamic torque converter with a turbine wheel and a converter lockup clutch accommodated in a housing, the converter lockup clutch having a piston which can be axially displaced on a hub, a clutch disk secured to the hub in such a way that it cannot rotate relative to the hub, and friction linings on the radially outer portion of the clutch disk. The radially outer part of the input section of the clutch disk is provided with friction linings, and the radially inner part of the output section of the clutch disk is connected to the hub by an internal gear. 
     Within the housing, hydrodynamic torque converters of such type normally have a pump wheel connected to the housing in such a way that it cannot rotate relative to the housing, and a stator between the turbine wheel and the pump wheel. The piston is normally connected to the hub so that it cannot rotate or can be rotated relative to the hub within a predetermined damper angle range. Torque converters of such type are known, for example, from DE 37 22 860 or DE 44 31 640. Rattling noises, which are generated by the engine-transmission unit when the vehicle is in use, develop due to the large rotary masses of the piston, especially when the combustion engine is idling. 
     OBJECTS OF THE INVENTION 
     An object of this invention is to provide a hydrodynamic torque converter with lockup clutch which exhibits acoustic characteristics superior to those of conventional torque converters, especially when the engine is idling, and which can be produced at a lower cost. Another object of the invention is to provide a torque converter which requires a small amount of space for installation, especially in the axial direction. 
     A further object of the invention is to simplify the making of torque converters and to reduce the number of component parts present in the hydrodynamic torque converter, thus achieving a more economical manufacture of such aggregates. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, this is accomplished in a hydrodynamic torque converter by attaching to the housing an axially movable lamina so that it cannot turn relative to the housing and is installed in an axial position between the radially outer marginal zone of the piston, which latter is mounted in such a way that it can turn freely on the hub, and the friction linings of the clutch disk. 
     It is particularly advantageous if the piston can turn freely on the hub and is separated from the torque transmitting path. The piston performs the sole function of building up pressure and biasing the lamina and the friction linings which are disposed between the lamina and the complementary friction surface. 
     It is advantageous if the lamina assumes the shape of an essentially annular element. It is desirable for the lamina to be manufactured as a shaped sheet metal component or a stamping. 
     It is further desirable to non-rotatably connect the lamina to the housing. 
     In accordance with one embodiment of the invention, it is advantageous if the lamina has a gear which is on its radially outer marginal portion and mates with an internal gear machined into the housing of the torque converter. 
     It is also desirable to provide the lamina with a toothed radially outer portion, a radially inner portion extending in a radial direction, and an angular portion disposed between the inner and outer portions and extending both in a radial and in an axial direction. 
     It is equally desirable if the radially inner marginal portion of the lamina is radially within a radially inner marginal portion of a friction lining. 
     It is particularly advantageous if the radially inner marginal portion of the lamina is located radially outwardly of a damper of the clutch disk. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in greater detail with reference to an embodiment which is illustrated in the accompanying drawings. There are shown in: 
     FIG. 1 a sectional view of a torque converter, and in 
     FIG. 2 a plan view of a clutch disc and a lamina. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows a hydrodynamic torque converter  1  in which the turbine wheel  2  is indicated by a turbine wheel shell  2   a . The turbine wheel/shell  2 ,  2   a  is non-rotatably mounted on or connected to a hub  3 . The connection normally employs rivets or welds. In addition to the turbine wheel  2 , the housing  13  of the torque converter  1  also receives a pump wheel and, if required, a stator. 
     The turbine wheel  2  of the torque converter  1  and the converter lockup clutch  10  with piston  11  and clutch disk  12  are installed within the housing  13 . The clutch disk  12  comprises a torsional vibration damper located between its input and output sections. 
     The clutch disk  12  consists essentially of a flange (output section)  22  mounted axially between two washers  20 ,  21  (input section). The washers are fixedly connected to each other at a fixed axial distance by at least one fastener  23  and/or  24 , such as a rivet, so that they cannot turn relative to each other. A friction lining carrying plate  25  is connected to the washers  20 ,  21  by a fastening element  24  and carries friction linings  26   a ,  26   b  on at least one side or, in accordance with a further advantageous embodiment, on both sides. The disk-shaped carrying plate  25  which constitutes a lining backing plate has radially inner tabs  25   a  which are riveted to the washer  21 . The washer  20  also has radially inner tabs  20   a  which extend into cutouts in the tabs  25   a  of the lining carrying plate  25 . The connection between the washers  20 ,  21  is then established by means of every second rivet  24 , and the other riveted joints  24  serve to connect the carrying plate with one of the wahers. In this way, each rivet is called upon to connect only two sheet metal parts. This brings about the advantage of reduced axial space requirements. 
     The flange  22  has a radially outwardly extending portion which is provided with windows  31  formed, for example, by punching and serving to receive energy storing devices  32 ,  33 . Furthermore, the flange includes a substantially washer-like leg  22   a  having a radially inner portion  22   b  with an internal gear  70 . The internal gear  70  meshes with an external gear  71  of the hub  3 . Torque is thus adapted to be transmitted from the flange  22  to the hub  3 . The hub  3 , in turn, also has an internal gear  73  which can be caused to mesh with a gear on a transmission input shaft (not shown) in order to transmit torque. 
     The normally circular or oval friction linings  26   a ,  26   b  are attached to the carrier plate  25  essentially by means of an adhesive or by pressing on. The friction linings may be provided with grooves to allow a fluid to flow there-through, also when the converter lockup clutch  10  is engaged. 
     The washers  20 ,  21  have apertures  30 , such as spring-receiving windows or recesses, as holders for the energy storing devices  32 ,  33 . The flange  22  has the afore-mentioned windows or cutouts  31 , such as spring-receiving apertures, to take the energy storing devices  32 ,  33 . The energy storing devices  32 ,  33 , such as compression springs, are installed in the windows  30 ,  31  of the washers  20 ,  21  and the flange  22  in such a way that, when the washers and the flange turn relative to each other, the energy storing devices transmit torque from the washers to the flange. This results in the making of a damper. An energy storing device  27 , such as a diaphragm spring, is disposed in the radially inner portion of the damper between the washer  21  and the flange  22  to center the washers  20 ,  21  and the flange  22  axially. The diaphragm spring  27  is supported radially inwardly by the washer  21  and radially outwardly by the flange  22 , whereby the diaphragm spring  27  can be provided with a gear mating with a complementary gear on the flange  22  or washer  21  and can thus be non-rotatably fixed to the flange  22  or washer  21 . The diaphragm spring  27  can be installed either between the flange  22  and the washer  20  at the engine side, or between the flange and the washer on the turbine wheel side. It is particularly advantageous if the other washer is in frictional engagement with the flange during relative rotation, as is shown radially inwardly of the fastener  23 . 
     The radially outer marginal portion of the piston  11  has a contact surface or friction surface  40 . The piston  11  is shown in the form of an annular element having a central opening which receives the hub  3 . Thus, the piston  11  is actually supported by the hub  3 . The radially inner portion  41  of the piston is bent in the axial direction and serves as a supporting foot for the hub. A sealing ring  43  is inserted in a circumferential groove  42  between the foot  41  and the hub  3  to seal the piston with reference to the hub. The piston  11  can turn freely and can be displaced axially relative to the hub, and its radially inner portion can be supported by the radially outer portion or collar  3   a  of the hub  3 , and this portion of the hub is provided with an axial bearing  90 , such as a bearing washer or a friction or roller bearing which is installed between the piston  11  and the hub portion  3   a . In accordance with an advantageous embodiment, the piston  11  is arranged so that it can rotate relative to the hub  3 . Therefore, if the input side of the torque converter is caused to vibrate, the torque converter does not cause torsional vibration of the piston and the moment of inertia of the piston is not affected by such vibrations. This enables the piston  11  to reduce, or even completely eliminate, rattling noises. 
     An annular lamina  50  is installed axially between the one friction lining  26   b  of the clutch disk  12  and the piston  11 , and such lamina is held against rotation relative to the housing  13  by means of a radially outer gear  52  forming part of the lamina and meshing with the internal gear  51  of the housing. The lamina  50  can be displaced axially within the gear  51  of the housing. The form-locking connection between the lamina and the housing is preferably established without the interposition of a further component. 
     The radially inner marginal portion  55  of the lamina  50  is located radially inwardly of the inner marginal portions of the friction linings. The lamina  50  has a substantially axially extending intermediate portion  50   a  located between its radially inner marginal portion  55  which extends in a radial direction and its radially outer marginal portion which also extends in a radial direction. 
     When the pressure in a plenum chamber  60  is caused to rise above that in a plenum chamber  61 , the lockup clutch  10  is engaged and the piston  11  is in contact with the friction linings  53 ,  54  of the lamina  50  and pushes the plate  25  against the friction lining  26   b  and the friction lining  26   a  against the friction surface of a radially extending wall of the friction clutch on the housing side. The lockup clutch is disengaged if the pressure in the plenum chamber  61  is higher than in the plenum chamber  60 . The friction linings  53 ,  54  may be replaced with a single friction lining. They serve to transmit axial forces from the piston  11  to the plate  25 ; at the same time, if there is a difference between the RPM of the lamina  50  and the piston  11 , they serve to reduce friction losses or to reduce wear. It is also advantageous for the friction linings to be relatively thin so that heat is dissipated easily via the friction ring(s). 
     FIG. 2 shows portions of the clutch disk  12  and of the lamina  50 . The internal gear  70  of the flange  22  for transferring torque to the hub  3  is also shown. The washer  21  is connected to the opposing washer  20 , not shown, so that it cannot turn relative to the washer  20  and is axially fixed thereto by means of the connecting elements  23 , such as rivets. The rivets  23  are evenly distributed around the circumference of the gear  70 . The windows  30  for the springs are provided in the washers  20  and  21 , for example, by punching, to hold the energy storing devices  32 ,  33 . These energy storing devices take the form of coaxially arranged coil springs having different diameters and having end convolutions at the ends  30   a ,  30   b  of the windows  30 , as seen in the circumferential direction of the flange  22 , to transmit torque between the flange  22  and the washers  20 ,  21 . 
     The annular backing plate  25  for the friction linings  26   a ,  26   b  is connected, by means of the rivets  24 , with at least one of the washers  20 ,  21  in the radially outer region of the clutch disk  12 . This backing plate has at least one friction lining or linings at both sides, and the friction linings preferably have grooves to allow fluids to pass therethrough for the purposes of cooling. 
     The present application also incorporates, by reference, the older application DE 196 34 029 the contents of which are to be considered as forming part of the disclosure in the specification of the present application. 
     The lamina  50  has a friction surface which can come into frictional contact with the adjacent surface of the friction lining  26   b  when subjected to pressure by the piston  11 . The gear  52  in the radially outer portion of the lamina  50  meshes with the internal gear  51  of the housing  13 . The mating gears  51 ,  52  cause the lamina  50  to rotate with the housing  13  but these gears allow the lamina  50  to move axially of the housing. 
     When the lockup clutch  10  is engaged, transmission of torque or forces takes place from the housing  13  of the torque converter  1  to the adjacent friction surface of the friction lining  26   a  of the clutch disk  12  as well as from the housing  13 , by way of the gears  51 ,  52 , to the lamina  50 , from the lamina  50  to the adjacent friction surface of the friction lining  26   b  on the clutch disk  12  and from there by way of the washers  20 ,  21  and the energy storing devices  32 ,  33  to the flange  22  and from the flange  22  by way of the gears  70 ,  71  to the hub  3  and from the hub  3  to the input shaft of the transmission, not shown. The piston  11  is not used for the transfer of torque because it can turn with respect to the hub  3  and with respect to the housing  13 . 
     The sequence of the components of the lockup clutch  10  is as follows (when viewed in the axial direction): housing  13  with its friction surface, friction lining  26   a  with its friction surface, backing plate  25  for the friction lining  26   b , friction lining  26   b  with its friction surface, the lamina  50  and the piston  11 . 
     The torque converter which is shown in FIGS. 1 and 2 consists essentially of sheet metal components which can be formed by shaping, such as for example deep drawing. At least some of the components, such as the piston  11  for example, may be made of aluminum. 
     If a suitable control system is provided with computerized controls, for example, and valves which can be actuated to apply pressure in the plenum chambers  60 ,  61 , the torque converter  1  and its lockup clutch  10  can be operated in such a way that the lockup clutch can be operated to slip within an operating range and can be fully engaged or disengaged, depending upon the selected operating point.