Patent Application
20060289209
1. Field of the Invention
The invention pertains to an electromotive drive module for installation in a motor vehicle powertrain with an internal combustion engine and a transmission.
2. Description of the Related Art
It is well known that the integration of one or more electric machines into the powertrain of a motor vehicle and the realization of purely electric powertrains and of hybrid powertrains combining an electric motor with an internal combustion engine have been a long-term development goal of the automotive industry for many years. The efforts in this direction have intensified especially in recent years because of the continuous increase in the cost of fuel and the demand to reduce the pollution caused by internal combustion engines. Fundamental technical problems of integrating electric drives into motor vehicle powertrains have already been solved, but considerable cost problems still stand in the way of customer acceptance and thus of rapid market introduction. These cost problems are attributable at least in part to the fact that, to achieve the greatest possible functionality and/or a very high performance level for a hybrid vehicle, the entire powertrain has to be redesigned, which means that a great deal of modification and development work is required in association with massive changes to existing systems.
Against this background, the present invention is based on the problem of integrating an electric machine into a conventional vehicle powertrain, that is, a powertrain equipped with an internal combustion engine and a transmission, in such a way as to provide an especially low-cost hybrid powertrain.
According to the invention, an electromotive drive module represents a structural unit which includes the electric machine and two clutches and which is designed specifically to be installed in the vehicle's powertrain. With the help of the clutches, the rotor of the electric machine can be connected as desired either to the internal combustion engine, to the transmission, or to both the internal combustion engine and the transmission for the transmission of torque. A module of this type can be manufactured by a supplier, for example, with the use of standard components under automated conditions and thus at low cost. For installation, the module can be easily accommodated in its entirety inside the bell housing of a gear-shift transmission and mounted in place there. As a result, vehicle manufacturers can save considerable assembly time and cost, and the associated risks can also be eliminated. Because there are in practice only a limited number of standard transmission types, a module of this type can be used universally in various vehicle platforms.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.
It can be seen that, instead of the friction clutch or torque converter, an electromotive drive module 18a has been integrated into the powertrain inside the transmission bell housing 16, so that the vehicle can be driven as needed either purely by the electric motor, purely by the internal combustion engine, or by a combination of the two. For this purpose, the stator 20 of an electric machine 22 of the internal rotor type, excited by permanent magnets, is installed and nonrotatably supported inside the transmission bell housing 16 by screw joints 23, which anchor the stator carrier 110. The type of electric machine 22 is unimportant for the following discussion; that is, it can be, for example, an asynchronous (induction) machine, a reluctance machine, etc. In place of the internal rotor, which is preferred because of its compactness, furthermore, it is also possible to modify the design in such a way that an external rotor could be used.
The rotor 24, supported rotatably inside the stator 20, has a rotor carrier 72 with a radial section 72a and an axial section 72b and a laminated rotor yoke, on the outside circumferential surface of which a plurality of permanent magnets 26 is arranged, the magnetic field of which is capable of interacting with another magnetic field generated by the system of windings on the stator 20. This interaction is thus able to drive the rotor 24 and, as will become clear in the further course of this description, it can also be used to drive the vehicle or to start the internal combustion engine 12.
The rotor 24 is in working connection by means of a first, shiftable clutch 28 with the crankshaft 86 of the internal combustion engine 12 and by means of a second, also shiftable clutch 30, independent of the first, with the input shaft 32 of the transmission 14. The arrangement of the rotor 24 with the clutches 28, 30 has an extremely compact design, in that both clutches 28, 30 are arranged in a receiving space 25 inside the rotor 24, which means they require no additional axial or radial room.
The first clutch 28 is designed as a dry multi-plate clutch, where a section of the hollow cylindrical rotor 24, more precisely the axial section 72b of the rotor carrier 72, forms the outer plate carrier, carrying on its inside circumferential surface a set of teeth for accepting several outer plates 34, which are therefore able to shift axially within a certain range. Additional inner plates 38, mounted with freedom to shift axially on a toothed inner plate carrier 36, engage radially from the inside in the gaps between the outer plates. A pressure-actuated hydraulic piston 40 of an actuating device 42, comprising a hydraulic cylinder 41, can be used to exert load on the entire package formed by the plates 34, 38 in opposition to the force of a restoring element 44 designed as a disk spring or diaphragm spring 44, as a result of which torque can be transmitted between the rotor 24 and the inner plate carrier 36 and the following elements. The inner plates 38 of this dry multi-plate clutch 28 are preferably friction plates.
It can be seen that the clutch 28 is of the “normally open type”. The piston 40 is a component of a hydraulic cylinder 41, arranged concentrically around the transmission input shaft 32. The axially fixed housing of the cylinder is formed by an essentially radially oriented housing area 45 of the second clutch 30, as will be explained below. The variable pressure space 46 of the hydraulic cylinder 41 is bounded by the piston 40 and the housing area 45 and is supplied with a fluid by a pump arrangement 48 through the transmission input shaft 32, which is designed as a hollow shaft. The sealing of the pressure space 46 is accomplished by two O-ring seals 50, 52, which are inserted into ring-shaped grooves 54, 56 in the housing area 45.
The inner plate carrier 36 has a radially inward-pointing section by which it is permanently connected by riveted joints 61, for example, to a radial flange 58 of a clutch hub 60 and is supported by means of two radial bearings 62, 64, designed as roller bearings, in the interior of a tubular section 66 of an intermediate housing wall 68, which is connected to the housing or to the transmission bell housing 16 and to the stator carrier 110 by means of screw joints 23. One end of the rotor 24 of the electric machine 22 is supported on the outer circumferential surface of the tubular section 66 by way of another radial bearing 70 provided there, also a roller bearing, and by way of radial section 72a of the rotor carrier 72. On the axial side facing the internal combustion engine 12, the clutch hub 60 is in contact with a connecting disk 74, which is held axially against the clutch hub 60 by a locking disk 76 and a bolt 78 inserted into the clutch hub 60. The connecting disk is connected to the clutch hub 60 for rotation in common by means of positive-locking profiles such as serrations, which are provided on both of the elements 74 and 60 and which are thus able to engage with each other.
In its radially outer area, the connecting disk 74 is connected by means of rivets 80, for example, to an essentially rigid transmission disk 82 (driveplate). The diameter of the driveplate 82 is preferably more-or-less the same as that of the electric machine 22 and is connected nonrotatably to the crankshaft 86 of the internal combustion engine 12 radially on the outside by means of a torque-transmitting plate 84, especially one with axial flexibility (flexplate). As a result, axial crankshaft vibrations, a certain axial tolerance possibly associated with the installation of the electromotive drive module 18a, and changes in length which occur during operation can be easily compensated. This makes it possible to eliminate undesirable stresses in the torque-transmitting elements located in the path of torque transmission between the internal combustion engine 12 and the transmission 14.
The second clutch 30, which serves to transmit torque between the rotor 24 and the input shaft 32 of the transmission 14, is designed as a wet-running clutch, where its housing 88, which simultaneously functions as a clutch input element, is connected nonrotatably to the rotor 24 of the electric machine 22, which can be realized as a permanent connection such as a weld or possibly as a detachable connection by means of screws or bayonet joints. The housing 88 is supported on the transmission input shaft 32 in a manner familiar to the man of the art. The wet-running clutch 30 is shown only in outline in the figure, and with respect to the details of construction, it is designed preferably but not exclusively in the manner described in US 2004/0195068, which is incorporated herein by reference.
In addition to the fluid-filled or fillable housing 88, the second clutch 30 also includes at least one first friction element, which can rotate in common with the housing around the input shaft 32 of the transmission 14; and at least one second friction element, which rotates around the input shaft 32 in common with a takeoff element. The second friction element can be brought into contact with at least one first friction element to produce a frictional interaction, and where at least one first friction element and the minimum of one second friction element each have a friction lining carrier, which carries a friction lining arrangement on each of the frictionally active axial sides of this friction element. A fluid transport surface arrangement for generating a fluid circulation flowing around at least certain areas of the friction elements is provided on at least one friction element equipped with a friction lining carrier with a friction lining arrangement.
A takeoff hub, which is connected in the known manner by means of a set of teeth to the input shaft 32 of the transmission 14, serves as the takeoff element or output element.
The housing 88 has a multi-part design including a housing part 90, facing the transmission 14, by which it is permanently connected radially on the inside to a pump hub 92, which is supported by a bearing 89 on the transmission bell or bell housing 16. The pump hub 92 is a component of a pump 48, mounted on the transmission 14. The pump builds up a fluid pressure and can thus maintain a uniform exchange of oil between the clutch 30 and the transmission 14. Through the special design of the internal components of the clutch, a forced circulation of fluid, which can be extremely rapid if necessary, can be achieved inside the clutch 30.
The hydraulic cylinder 41 provided to actuate the clutch 28 has a stepped piston 96, which is situated in the radially inner area and which extends essentially in the axial direction. The piston is guided on a housing hub 98 of the second clutch 30 and cooperates with the hub to form the pressure space 46, which is sealed off in turn by two ring seals 100, 102 mounted on the housing hub. The stepped piston 96 has a radial flange 104 at one end, against which the actuating element 94 can act so that force can be transmitted to the plate package 34, 38. The particular advantage of the small outer diameter of the cylinder achievable by the use a stepped piston 96 is that the rotating fluid thus generates only a small amount of centrifugal force, which can be compensated for very easily. The centrifugal force can be compensated here without any special effort simply by the restoring force of the actuating element 94.
In the two exemplary embodiments according to
It should be mentioned that, as an alternative to the double or two-ended support of the rotor 24 via the rotor carrier 72 and the housing 88 as shown in
In the exemplary embodiment explained on the basis of
On the basis of a drive module 18c,
In the housing of the “normally open” clutch shown here, the piston 112 of the actuating cylinder 41 acts by way of a clutch-engagement bearing 114 and a spring lever plate 116 on the plate package 34, 38. It is an advantage of this embodiment that no changes of any kind are needed to the input side of the automatic transmission 14. The only measures which must be taken involve the actuation of the clutch 28 provided in addition to the automatic converter. The clutch can be actuated by means of a pressure medium supply, for example, which is integrated into the hydraulic system of the transmission 14 or provided as an external system.
Common to the exemplary embodiments explained on the basis of
In terms of its basic design, the electromotive drive module 18d shown in
The first clutch 28 is designed as a “normally open” clutch for push-type actuation, for which purpose a concentric hydraulic slave cylinder 41 is integrated into the intermediate wall 68. To form the cylinder housing and the pressure space, a ring-shaped recess 118 oriented toward the clutch 28 is introduced into the intermediate wall 68. A ring-shaped piston 120 fits into this recess. The ring-shaped piston 120, on the side facing away from the pressure space, rests against a cranked engaging plate 122, which can transmit the force required to close the clutch 28 to the fixed bearing ring of an axially movable clutch-engaging bearing 114 and onward from the rotating bearing ring of that bearing, i.e., the ring facing the clutch 28, to the radially inner edge of a spring lever plate 116. The outer area of the spring lever plate 116 is supported pivotably on a carrier section 124 projecting axially beyond the electrically active part of the rotor 24 and acts on several transmission elements 126, which are uniformly distributed around a graduated circle. These transmission elements are formed on the outer plate 34a adjacent to the lever plate 116 and project through segment-like access openings 128 in the rotor carrier 72a.
As an alternative to the integrated design described above, the actuating cylinder 41 can be an external element mounted on the intermediate housing wall 68. Regardless of how the actuating cylinder 41 is designed, it is actuated by way of a pressure line 108, previously explained in conjunction with
The direct, radially adjacent arrangement of the two bearings 70 and 114, i.e., one radially inside, the other radially outside the tubular section 66 of intermediate wall 68, has the effect of almost completely eliminating any flow of force between these two bearings 70, 114 in the event of an interaction between them.
The transmission input shaft 32 projects into the second clutch 30 and is supported there on a bearing 130, preferably mounted on the housing hub 98.
The inner plate carrier 36, as previously explained on the basis of
The drive module 18e of
In the housing of the exemplary embodiments of
According to the drive module 18f shown in
The compensating element 140 has here in particular the task of providing radial cushioning between the crankshaft 86 and the bearing 132 installed between the housing hub 98 and the clutch hub 60. Because of the limited ability of the parts 142, 144 to rotate relative to each other, torsional vibrations are damped to a negligible extent.
The desired radial cushioning serves to compensate for axial offsets between the crankshaft 86 and the transmission input shaft 32 and for wobbling movements of the crankshaft 86, so that these offsets and movements do not have to be absorbed by the flexplate 84 alone. The radial loads on the bearings 70, 132, and 89 are thus decreased. In addition, a mounting pin 148 is attached to the crankshaft 86. During the process of installing the complete module in the internal combustion engine, this pin serves a precentering function but no bearing function.
It can also be seen that, with respect to the path of torque transmission, the torsional vibration damper arrangement 150 is downline from the first clutch 28 when the vehicle is being driven by the internal combustion engine. This arrangement makes it possible, first, for the internal combustion engine 12 to be started extremely quickly by the electric machine 22 because of the low mass moments of inertia; second, the arrangement makes it possible for the masses of the input and output parts of the torsional vibration damper arrangement 150 to be distributed optimally for the damping of torsional vibrations when the internal combustion engine is driving the vehicle. In this way, therefore, the previous problems and compromises associated with the job of designing a torsional vibration damper arrangement 150 to be located between the starting clutch 28 and the internal combustion engine 12 are elegantly avoided.
It can also be seen that the energy-storing springs 156 of the torsional vibration damper arrangement 150 are located radially approximately in the area of the rotor 24 and the radially outer section of the housing 88, whereas axially they are located near the second clutch 30, which makes it possible to give the drive module 18g a compact design.
In
Yet another alternative variant of the support of the inner plate carrier 36 is shown in
As an alternative to the arrangement of the torsional vibration damper arrangement 150 shown in
In all of the exemplary embodiments presented so far, it can also be advantageous for the flexplate 84 and/or the driveplate 82, as shown in
The electromotive drive module 18a-i is prefabricated as a structural unit, this unit comprising at minimum the electric machine 22 and the two clutches 28, 30. The two clutches and the rotor 24 of the electric machine 22 form a subunit. Depending on the design, the intermediate wall 68 is also part of the drive module 18. This drive module 18a-i therefore represents an additional assembly unit available to transmission manufacturers, or auto manufacturers can install it themselves between the internal combustion engine and the transmission. The module 18a-f can be accommodated inside the transmission bell housing 16 and mounted on the transmission input shaft. Alternatively, the intermediate wall 68 can be designed as an independent housing, which can be installed between the front end of the internal combustion engine 12 and the transmission 14. For final installation, the stator 20 of the electric machine and possibly also the intermediate wall 68 are attached to the transmission housing 16 and, for the production of a torque-transmitting connection, the crankshaft 86 of the internal combustion engine 12 is connected to the flexplate or optionally to the driveplate or directly to the inner plate carrier 36.
Through the implementation of the electromotive drive module described above, a versatile hybrid drive is created, which makes it possible for the vehicle to be driven by the electric motor alone after the internal combustion engine has been disconnected by the opening of the first clutch. While the electric machine is operating as a motor, it can drive the pump arrangement of the automatic transmission directly and thus make it possible for all hydraulic transmission functions to be carried out even during periods when the vehicle is being driven by electricity alone.
In cooperation with the first clutch, the electric machine can start the internal combustion engine inertially. The powertrain 10 and especially the electromotive drive module 18a-i are designed in such a way, as illustrated in
While the rotor is rotating, this clutch is closed—and the turned-off internal combustion engine thus connected—in such a way as to increase the drive torque of the electric machine to the extent required to start the internal combustion engine. The drive torque at the wheels remains unaffected by this, and therefore the occupants of the vehicle remain almost completely unaware of this process.
It is also possible, however, to use the closed clutch 28 to connect the turned-off internal combustion engine nonrotatably to the rotor of the electric machine and to crank up both assemblies from a standstill together. This is known as a “direct start”.
When the vehicle is being driven by the internal combustion engine, the first and second clutches are both closed. The electric machine is running in this housing in generator mode. While the vehicle is being driven, the generator mode can, if necessary, be interrupted for a certain period of time, however, so that the electric machine can operate as a motor and thus assist the internal combustion engine by introducing additional torque to the vehicle powertrain.
When the vehicle is stopped and the first and second clutches are open, low drive rpm's of the electric machine are sufficient to maintain the fluid pressure in the transmission, which is a prerequisite for the realization of a start-stop function.
With respect to control technology, it is advisable to coordinate the hybrid vehicle control with the automatic transmission control and possibly to combine these control functions into a common control system.
In summary, the electromotive drive module explained above and a vehicle equipped with such a module offer a wide range of functionality in a very small space. The development effort is modest, because a module of this type can be built out of known individual components, a fact which also offers considerable cost advantages in terms of series production. With respect to the unit formed by the internal combustion engine and the transmission, the drive module can be located between the internal combustion engine and the transmission without increasing the amount of space required. Through the use of a wet-running clutch according to the specification, a large amount of start-up power can be provided. Because the electric machine is of the internal rotor type, furthermore, a low mass moment of inertia is also realized, which is desirable.
It should also be pointed out in particular that the scope of disclosure of the present patent application also comprises exemplary embodiments not illustrated in the drawings; that is, embodiments in which elements or variant arrangements of certain individual exemplary embodiments as explained on the basis of the figures can be transferred to other exemplary embodiments and can correspondingly supplement these arrangements or elements or replace them. This pertains in particular to the arrangement of the torsional vibration damper 150, of the compensating element 140, and of the additional mass 176, and to the way in which the rotor 24, the transmission input shaft 32, the second clutch 30, and the inner plate carrier 36 are supported.
Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 029 305.0 | Jun 2005 | DE | national |
| 10 2005 044 225.0 | Sep 2005 | DE | national |
| 10 2005 053 887.8 | Nov 2005 | DE | national |
