Planetary gear transmission systems or components – Input from independent power sources – Including electric motor input
Reexamination Certificate
2000-09-29
2002-05-28
Marmor, Charles A (Department: 3681)
Planetary gear transmission systems or components
Input from independent power sources
Including electric motor input
Reexamination Certificate
active
06394924
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a drive arrangement for a motor vehicle, having an internal combustion engine with a crankshaft which can be connected, via an interposed clutch, to a gearbox input shaft of a change-speed gearbox. An electric machine is provided in the drive arrangement and has a stator and a rotor.
DISCUSSION OF THE PRIOR ART
Such a drive arrangement is disclosed, for example, by German reference DE 43 23 601 A1, in which a drive arrangement for a motor vehicle, in particular for a hybrid vehicle, is described. On account of the drive arrangement, which is constructed as above, the vehicle can be driven on the one hand by the internal combustion engine and on the other hand by the electric machine. The electric machine can also be activated, supporting the internal combustion engine, to drive the motor vehicle. Driving the vehicle by the electric machine alone is expedient, particularly in the range of low traveling speeds. However, in order then to make it possible to start up by means of the electric motor drive on its own, powerful electric machines are required which, on the one hand, have a large axial overall length and, on the other hand, are very costly.
In WO 98/40647, which, in relation to the first application on which priority is based, was published after the present application, a description is given of an electric machine integrated into a gearbox for motor vehicle internal combustion engines, and for the control thereof. Here too, the internal combustion engine can be connected, via a crankshaft and an interposed clutch, to a gearbox input shaft of a change-speed gearbox. Furthermore, an electric machine is provided which is switched via an intermediate gear mechanism in parallel with the gearbox input shaft. The intermediate gear mechanism is designed in the form of a step-up gear mechanism. As a result of the parallel arrangement of the intermediate gear mechanism, however, a relatively large amount of installation space is needed which, in particular from the point of view of passenger cars, is not available in the engine compartment thereof.
The electric machine described in WO 98/40647 can be designed as a so-called starter-generator. If the electric machine is switched as a starter motor, the internal combustion engine can be started thereby. When the internal combustion engine is in operation, it is possible to supply the on-board motor vehicle network via the electric machine switched as a generator. Starter-generators are normally slipped onto the crankshaft or the gearbox input shaft, so they must have the lowest possible space requirement.
SUMMARY OF THE INVENTION
On the basis of the above-mentioned prior art, the present invention is based on the object of developing a drive arrangement for a motor vehicle of the type mentioned at the beginning in such a way that the above-described disadvantages are avoided. In particular, it is intended to provide a drive arrangement which is particularly powerful and in which the production costs are reduced with respect to comparable drive arrangements. Furthermore, it is intended that the electric machine should also be designed to be particularly space-saving.
This object is achieved by a development of the drive arrangement mentioned at the beginning which, according to the invention, is defined by the fact that the electric machine, in order to step down its rotational speed, is operatively connected to the crankshaft and/or the gearbox input shaft via a step-down gear mechanism. The step-down gear mechanism is designed as an epicyclic gear mechanism which has a sun gear, an internal gear and a number of planet gears.
The drive arrangement designed in accordance with the invention makes it possible to circumvent the disadvantages described further above. If the electric machine is used, for example, as a starter-generator, the configuration according to the invention also makes it possible, even with relatively small electric machines, to produce such high torques when starting so that even the starting of large internal combustion engines is made possible. If the electric machine, for example, is used as an electric motor and is connected to the gearbox input shaft, it is made possible to start using the electric drive on its own with an acceleration response which is virtually identical in comparison to drive by the internal combustion engine. In this case, the overall axial length of the drive arrangement does not exceed a predetermined amount permitting transverse installation.
A basic idea of the present invention resides in the fact that the electric machine is operatively connected to the crankshaft and/or the gearbox input shaft via a separate step-down gear mechanism.
The use of an epicyclic gear mechanism as the step-down gear mechanism has proven to be particularly advantageous. Such an epicyclic gear mechanism can be arranged coaxially with the gearbox input shaft or with the crankshaft of the internal combustion engine. As a rule, epicyclic gear mechanisms have a sun gear, an internal gear and various planet gears, the individual gears being arranged and aligned coaxially with one another. In this way, an epicyclic gear mechanism constitutes a very effective gear mechanism with only a low space requirement.
The electric machine can advantageously be designed as a synchronous machine, especially a permanently excited synchronous machine, or as an asynchronous machine. The electric machine can be designed both as an external rotor type and as an internal rotor type. If an asynchronous motor is provided as the electric machine, its maximum rotational speed is around 10,000 rev/min. If the electric machine is designed as a synchronous motor, its maximum rotational speed lies in the range from 5000 to 10,000 rev/min. On the other hand, the maximum rotational speed of a modern internal combustion engine, especially of a diesel engine, lies in the range of 4000 rev/min. As a result of the measure of coupling the electric machine to the drivetrain via a step-down gear mechanism which steps down the rotational speed of the electric machine, the torque acting on the drivetrain from the electric machine is stepped up in such a way that the maximum permissible rotational speed of the electric machine is not exceeded. The torque which can be provided by the electric machine corresponds to a torque from a more powerful electric machine, which would take up many times the axial installation space. As a result of the drive arrangement according to the invention, the higher rotational speed of the electric machine can be stepped down by the step-down gear mechanism to the lower rotational speed of the internal combustion engine. At the same time, however, a high torque is transmitted.
The electric machine can be designed, for example, as an electric motor in a hybrid vehicle. The torque transmitted from the electric machine corresponds, inter alia as a result of the step-down gear mechanism, to a torque from a more powerful engine, in particular in the range of lower traveling speeds.
An electric machine which is particularly worth mentioning is, for example, also the starter-generator for vehicles. This is an electric machine whose rotor is mounted via the crankshaft mounting of the internal combustion engine. The starter-generator is used not only for starting and stopping the internal combustion engine but can also perform different functions during engine operation, such as supplying the on-board network with electrical energy (generator function), braking functions, booster functions, battery management, active vibration damping, synchronization of the internal combustion engine with the gearbox during change-speed operations, and the like.
The epicyclic gearbox can preferably be designed as a fixed-speed (fixed) epicyclic gear mechanism or as a clutch-operated or change-speed epicyclic gear mechanism.
In the following text, firstly some exemplary embodiments will be described in which a fixed-speed step-down gear mechanism is provided between engine and gearbox or
Röder Manfred
Schiebold Stefan
Cohen & Pontani, Lieberman & Pavane
Mannesmann Sachs AG
Marmor Charles A
Parekh Ankur
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