The invention relates to a hydrodynamic torque converter with a turbine shell connected jointly with a torsion damper support structure to a carrier part which is supported rotatably relative to the transmission input shaft hub and to a method for manufacturing such a hydrodynamic torque converter.
DE 19826351 C2 discloses a hydrodynamic torque converter with a torsion damper connected to a turbine shell.
Hot-riveting methods using hot rivets having rivet heads for interconnecting a torsion damper to a turbine shell are already known in principle from US 2005/0161442 A1, GB 3 1 528 730 and DE 31 40 368 A1.
It is the object of the present invention to provide a hydrodynamic torque converter and a method for manufacturing the same which makes it possible to attach the turbine shell of the torque converter after assembly of the torsion damper.
In a hydrodynamic torque converter having a turbine shell and a torsion damper spring carrier jointly mounted to a carrier part by way of rivets extending through aligned openings in the turbine shell and the spring carrier, rivets with rivet shanks and a rivet heads are inserted through the aligned openings and welded to the carrier part by pairs of electrode by which the rivets are pressed into contact with the carrier part while a welding current flow is established from one to the other of the pair of welding electrodes through the respective rivets and the carrier part.
It is an important advantage of the invention, that it makes it possible to completely assemble the torsion damper, and optionally to test it for correct operation, and then to connect the turbine of the torque converter non-rotatably to the torsion damper from one side by hot riveting. For this purpose, the head of the hot rivet is provided on the axial side of the turbine whereas the narrow shank of the hot rivet is passed through an opening of the turbine shell and welded to a carrier part of the torsion damper. As a result of this assembly from one side, the turbine can be fastened to the torsion damper after the assembly of the torsion damper. A pre-assembly of turbine and torsion damper can prove complex and costly if the turbine is produced at a different production site from the torsion damper. In that case the turbine and the torsion damper would first have to be brought together at one site for assembly, and possibly then have to be transported to another site for assembly to the housing. This problem is aggravated if the individual components are produced by different manufacturers—in particular OEMs (Original Equipment Manufacturers) and other suppliers. By contrast, delivery of all components to a particular site, where the largest components are produced, provides for the lowest production/assembly cost.
With hot-riveting, a method as described in DE 102005006253.9-34, which is not a prior publication, is used especially advantageously. In addition to the advantage mentioned in the introduction, a further advantage of this method is that no deposits, which would be in the oil circuit of the hydrodynamic torque converter as soon as it was put into operation, is released. The oil circuit of the transmission, which usually has a common oil circuit with the hydrodynamic torque converter, is therefore kept clean. This is because, with hot-riveting, the deposits—i.e. the weld spatter—can be held back in a special catching area which may be in the form, for example, of an annular pocket or an inner end wall of a rivet hole.
As compared to the non-rotatable connection using a spline toothing, for example, a connection by hot-riveting has the advantage that it is a rigid connection without tooth flank play, so that noises resulting from resonance oscillations cannot occur.
The turbine shell can be hot-riveted directly to a sheet metal portion of the torsion damper, so that this sheet metal portion forms the carrier part mentioned. However, for reasons of weight and dynamics, a turbine is made of very thin sheet metal, which in turn makes a connection by the hot-riveting method problematic. For this reason a separate carrier, which may be configured, in particular, as an annular carrier, may be provided. In this case and the hot rivets are welded to the carrier. The sheet metal of the torsion damper and the thin turbine shell are therefore clamped between the carrier and the head of the hot rivet.
The carrier can be made sufficiently thick and stiff for it to absorb the forces required for welding and riveting. Furthermore, the carrier may have a centering function for the turbine and/or can function as a spring carrier of the torsion damper. In order to receive deposits, this carrier may include a blind hole. Because the carrier can be produced, in particular, as a turned part, an annular groove may also be provided for the circumferentially distributed hot rivets. The depth of the annular groove advantageously determines the length of the hot rivets. Thus, an especially long rivet may be provided, the shrinkage of which upon cooling is correspondingly high, so that a high tensile stress is also achieved. This high tensile stress provides for an especially good connection.
Especially advantageously, an embossment may be provided between the sheet metal parts to be connected by means of hot rivets, that is, the sheet metal of the torsion damper and of the turbine shell. Such an embossment forms an element preventing rotation between the sheet metal parts prior to riveting. This embossment may be provided, in particular, in the region of the hot rivets.
A support of the carrier part on the transmission input shaft hub 4 advantageously ensures proper axial positioning of the torsion damper with respect to the transmission input shaft hub by the carrier part.
Indirect welding of at least two rivets simultaneously ensures that the main current does not flow via reciprocally movable parts, so that secondary welding and/or surface damage cannot occur on those parts. Welding with at least two welding electrodes distributed uniformly over the circumference provide security against tilting.
The invention will become more readily apparent from the following description of exemplary embodiments thereof on the basis of the accompanying drawings.
On the output side, the hydrodynamic torque converter 1 is connected via a spline toothing 52 to a coaxially arranged transmission input shaft (not shown in detail) of a transmission. The transmission input shaft, the hydrodynamic torque converter 1 and a crankshaft flange are arranged coaxially with a central axis 25.
The hydrodynamic torque converter 1 comprises the housing 50, a pump shell 35, a turbine 37 and a stator 38. The following detailed description of an exemplary embodiment follows the power flow from the crankshaft to the housing 50. From the housing 50 the power flow passes to the pump shell 35. With hydrodynamic power transmission the power flow is transmitted from this pump shell 35 to the turbine 37 and, via a torsion damper 17, to the transmission input shaft mentioned. By contrast, with a lock-up clutch 18 engaged, the power flow is transmitted from the housing 50 via the lock-up clutch 18 to the torsion damper 17 and then to the transmission input shaft.
The turbine 37 is arranged beside the pump shell 35 on the side of the latter oriented towards the drive engine. The stator 38, which is supported in the conventional manner on a freewheel 39, is arranged radially inside and axially between the pump shell 35 and the turbine 37.
An inner hub 40 of the freewheel 39 is connected non-rotatably to a stator shaft (not shown in detail) by means of an internal toothing.
The turbine 37 has in its radially inner region a plurality of circular openings 5a, which can be seen in more detail in
the sheet-metal support 46,
the spring carrier 44 and
a sheet-metal coupling element 53 riveted non-rotatably to the spring carrier 44.
The sheet-metal support 46 is provided, radially outside the curved springs 47, 14 in the circumferential direction, with curved attachment pieces 49 which guide the bow springs 14. The sheet-metal support 46 is connected non-rotatably by its radially inner portion to a transmission input shaft hub 51. This transmission input shaft hub 51 is connected non-rotatably to the transmission input shaft by means of the spline toothing 52 mentioned previously. The carrier 43 is supported radially and axially on the transmission input shaft hub 51 by means of a slide bearing. A lubricant channel 70 is provided for lubricating the axial pairing of slide surfaces. This lubricant channel 70 opens into a lubricant channel 71 which is provided for lubricating the radial pairing of sliding surfaces. At the same time the lubricant channel 70 ensures the lubricant circulation of the converter cooling circuit. The carrier part 43 is supported axially on an axial securing ring 73 via an axial roller bearing 72. The axial securing ring 73 is in turn supported axially on an outer race 74—i.e. clamping ring—of the freewheel 39.
The sheet-metal coupling element 53 is connected immovably to an inner disk carrier 54. The inner disk carrier 54 secures inner clutch disks of the lock-up clutch 18 by means of an axial toothing. These clutch disks are displaceable non-rotatably and axially with respect to the inner disk carrier 54. Likewise, outer clutch disks are secured non-rotatably and axially displaceably to an outer disk carrier 57 rigidly connected to the housing 50. For this purpose, an axially-oriented internal toothing, in which an external toothing of the outer clutch disks engages, is worked into the outer disk carrier 57. The outer disk carrier 57 extends coaxially to the housing 50 and is friction-welded immovably thereto. The outer and inner clutch disks engage in one another radially. The inner clutch disks 55 have friction linings which are fastened firmly to a base body on both sides. These friction linings are located on both sides of the outer clutch disks and on one side of the front clutch disk and on a bracing disk 63. A friction moment is transmitted by the contact surfaces. A piston 64 is provided in order to disengage and engage the lock-up clutch 18.
In the production process described below with reference to
the inner disk carrier 54,
the torsion damper 17,
the annular carrier 43 and
the transmission input shaft hub 51.
The transmission input shaft hub 51 is placed in a receptacle 101 of a machine and the turbine wheel or shell 37 together with the hot rivets 7 is placed in the constructional unit 100. The hot-riveting process, as illustrated in detail with reference to a single hot rivet in
The end face 9 of the hot rivet 7 is then welded to the surface 10 of the carrier 43. This is done here by a resistance welding process, for example. All electric welding methods are, however, suitable. As the resistance welding process, a projection welding process, in particular, is used here. For this purpose the end face 9 of the hot rivet 7 is formed appropriately as the tip 16. The welding is effected by an electrical welding pulse. In this exemplary embodiment the pulse has a length in the order of magnitude of 30-60 milliseconds, a usual value when resistance-welding the end faces of hot rivets 7.
At the same time a force which leads to a plastic deformation in the form of an upsetting of the shank 13 of the hot rivet 7 is exerted in the longitudinal direction 8 of the hot rivet 7. The upsetting force may have the same value as the welding force, or may be lower or higher than the welding force. This upsetting movement is carried out until at least a portion of the underside 12 of the head 15 of the hot rivet 7 rests against the surface 11 of the turbine 37. The material of the shank 13 forced to the sides during upsetting now completely fills the openings 5a, 5b zonally in the circumferential direction. The weld spatter produced during welding of the end face 9 of the hot rivet 7 to the surface 10 of the carrier part 43, as well as material displaced in this catching area during upsetting, is received in the catching area 23 of the opening 5b, so that a clean, smooth contact surface is present both
between the carrier 43 and the spring carrier 44, and
between the spring carrier 44 and the turbine 37.
The weld spatter cannot therefore enter the oil circuit of the hydrodynamic torque converter, or possibly of the transmission, as scale loss.
An electric welding circuit is established via two rivets as shown in
Because, according to this method, a welded connection is produced only between the hot rivet 7 and the carrier 43, it is possible to fasten the spring carrier 44 and the turbine 37, which do not need to be weldable, to the carrier 43. For example, the spring carrier 44 and the turbine 37 may be components made of aluminum, surface-coated steel—in particular nitrated steel—ceramics or plastics, in particular fiber-reinforced plastics—as well as composites of such components. Only the hot rivet 7 and the carrier part 43 must be made of a weldable material.
Furthermore, by virtue of the fact that the hot rivet 7 has clearance with respect to the bore 5 prior to the implementation of the method, the end face 9 of the hot rivet 7 can be welded to the carrier 43 without a short circuit even when connecting electrically conductive materials for the carrier 43, since the welding current is conducted only through the hot rivet 7 itself. In all cases the high electrical resistance needed for welding occurs between the end face 9 of the hot rivet 7 and the surface 10 of the carrier 43.
After implementation of the method, the hot rivet 7 shrinks because of the preceding thermal reshaping. In this way, additional clamping of the joint is obtained, resulting in high strength of the connection.
Furthermore, the welding and subsequent plastic deformation take place in one work cycle on a standard welding press, without the requirement for additional retooling or resetting.
Hardening of the weld zone 30 possibly occurring after the welding is reduced by the subsequent heating in connection with the plastic deformation.
Apart from the cylindrical geometry of the opening 5b described above, it is possible to provide a conical geometry, as represented in
For installation, the rivet is preferably attached to the welding electrode (102a, 102b) for example, by vacuum. However, the rivet may also be attached to the welding electrode magnetically or mechanically.
The openings in the turbine shell 37 may be punched or drilled.
In
The catching area 123 for receiving the weld spatter is configured differently in this case than as shown in
The embodiments described are only exemplary configurations. A combination of the features described for different embodiments is also possible. Further features of the device parts, which form part of the invention, are apparent from the geometries of the device parts shown in the drawings.
Number | Date | Country | Kind |
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10 2006 028 771.1 | Jun 2006 | DE | national |
This is a Continuation-In-Part Application of pending International patent application PCT/EP2007/004366 filed May 16, 2007 and claiming the priority of German patent application 10 2006 028 771.1 filed Jun. 23, 2006.
Number | Date | Country | |
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Parent | PCT/EP2007/004366 | May 2007 | US |
Child | 12317279 | US |