CN115467950A

CN115467950A - Transmission for a motor vehicle

Info

Publication number: CN115467950A
Application number: CN202210198910.XA
Authority: CN
Inventors: F·库特尔; M·布雷默; M·霍恩; O·拜耳; J·卡尔滕巴赫; T·马丁; M·维克斯; T·克罗; M·巴赫曼; P·齐默; J·帕夫拉克维奇; S·贝克
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2021-06-11
Filing date: 2022-03-02
Publication date: 2022-12-13
Also published as: DE102021205948B4; DE102021205948A1

Abstract

The invention relates to a transmission for a motor vehicle, comprising a drive shaft and an input shaft, which can each be coupled to the output side via at least one spur gear stage. The drive shaft is designed to connect the transmission to a drive machine of a motor vehicle, while the input shaft is coupled to a rotor of an electric machine. The drive shaft and the input shaft can be connected to each other in a rotationally fixed manner by closing the first switching element. In order to be able to realize a compactly designed transmission at low production costs, a planetary stage is provided which has a first, a second and a third element in the form of a sun gear, a planet carrier and a ring gear. The first element is connected in a rotationally fixed manner to the input shaft and the second element is coupled to the output side via a first spur gear stage, while the third element can be fixed by the second shift element and connected in a rotationally fixed manner to the drive shaft by means of the third shift element. Furthermore, the input shaft can be fixed by means of a fourth switching element.

Description

Transmission for a motor vehicle

Technical Field

The invention relates to a transmission for a motor vehicle, comprising a drive shaft and an input shaft, which can be coupled to the output side via at least one spur gear stage, wherein the drive shaft is designed to connect the transmission to a drive machine of the motor vehicle, wherein the input shaft is coupled to a rotor of an electric machine, and wherein the drive shaft and the input shaft can be connected to each other in a rotationally fixed manner by closing a first switching element. The invention also relates to a motor vehicle drive train having a transmission of this type and to a method for operating a transmission.

Background

In motor vehicles, multi-stage transmissions are known in which a plurality of different transmission ratios can be shifted as gears by actuating corresponding shift elements, wherein this is preferably effected automatically. In this case, the transmission is used to appropriately implement the tractive power supply of the drive machine of the motor vehicle in terms of different standards. In the case of transmissions for hybrid vehicles, the above-described transmissions are often also combined with one or more electric machines, which can be incorporated in the transmission in different ways in order to assume different operating modes, for example a purely electric drive.

From FR2811395A1 a transmission is known, which has a drive shaft and an input shaft. The drive shaft can be connected to a drive machine in the form of an internal combustion engine via a separating clutch, and two spur gear stages are provided between the drive shaft and a countershaft arranged parallel to the drive shaft axis, each of which is formed by a fixed gear arranged in a rotationally fixed manner on the drive shaft and a loose gear rotatably mounted on the countershaft. In this case, the respective loose gear meshes with the associated fixed gear of the respective spur gear stage and can be fixed to the countershaft by the associated shift element, so that the drive shaft is subsequently coupled to the countershaft by the respective spur gear stage. Furthermore, the countershaft carries a fixed gear wheel which is in toothed engagement with a disk drive gear (antitriebsellerrad) of the differential, which forms the output side of the transmission. Furthermore, an input shaft is arranged coaxially with the drive shaft, which is embodied as a hollow shaft and is connected in a rotationally fixed manner to the rotor of the electric machine. In addition to the torsionally fixed connection of the input shaft to the drive shaft by the associated shift element, the input shaft is also coupled to the countershaft, which can each be realized by one of two spur gear stages, which are arranged between the input shaft and the countershaft and can each be incorporated into the force flow by actuating the respective associated shift element.

Disclosure of Invention

Starting from the prior art described above, the object of the invention is to make a transmission as compact as possible with low manufacturing costs, wherein hybrid functions are to be achieved by means of the transmission.

The object is achieved in accordance with the preamble of claim 1 in combination with the features of the characterizing part of this claim. The following dependent claims each provide advantageous further developments of the invention. The subject matter of claim 16 is also a motor vehicle drive train in which the above-mentioned transmission is provided. In addition, claims 17 to 19 each relate to a method for operating a transmission.

According to the invention, the transmission comprises a drive shaft and an input shaft which can each be coupled to the output side via at least one spur gear stage. The drive shaft is designed to connect the transmission to a drive machine of a motor vehicle, while the input shaft is coupled to a rotor of an electric machine. The drive shaft and the input shaft can be connected to each other in a rotationally fixed manner by closing the first switching element.

A "shaft" in the sense of the present invention is understood to mean a rotatable component of the transmission, by means of which a force flow between the components can be guided, if necessary, when the respective shift element is actuated at the same time. The respective shafts may connect the components to one another in the axial direction or in the radial direction or both in the axial direction and in the radial direction. The respective shaft can therefore also be present as an intermediate piece, by means of which the respective components are connected, for example, in the radial direction.

In the sense of the present invention, "axially" means an orientation in the direction of a longitudinal center axis of the transmission, in which the axis of rotation of the shaft of the transmission is also oriented parallel to the longitudinal center axis. "radial" is therefore to be understood as meaning the radial orientation of the respective component of the transmission, in particular of the respective shaft.

Preferably, the coupling of the differential, which is arranged axially parallel to the drive shaft and the input shaft of the transmission, is established via the driven side of the transmission. The output side is preferably located in the axial direction in the region of or in the vicinity of a connection point of the drive shaft, at which connection point a connection of the drive shaft to a drive machine connected upstream is established in the installed state of the transmission. In principle, however, the output side can also be arranged in the region between the axial ends of the transmission. This type of arrangement is particularly suitable for use in motor vehicles with a drive train oriented transversely to the direction of travel of the motor vehicle.

Instead of this, the output side of the transmission can in principle also be arranged at the axial end of the transmission opposite the connection point with the drive shaft. The drive means are therefore placed on the mutually opposite axial ends of the transmission by means of the drive shaft and the driven means of the transmission. The transmission thus constructed is suitable for use in a motor vehicle having a drive train oriented in the direction of travel of the motor vehicle. In both cases, the drive shaft and the input shaft are preferably coaxial with one another, wherein the drive shaft is further preferably embodied here as a solid shaft and the input shaft is embodied as a hollow shaft which is arranged radially around the solid shaft and partially overlaps the solid shaft in the axial direction.

A part of the transmission according to the invention is furthermore at least one spur gear stage, which in the sense of the invention is in each case assembled from at least two spur gears, which are permanently in toothed engagement with one another. In this case, the spur gears of the at least one spur gear stage can each be arranged as a fixed gear on the shafts to be connected above it in a rotationally fixed manner, so that the shafts between which the at least one spur gear stage is arranged are continuously coupled to one another. However, one or more spur gears of the at least one spur gear stage may also be so-called loose gears which are rotatably mounted on the respective shaft and which may be connected in a rotationally fixed manner to the respective shaft, if appropriate via associated shift elements, in order to establish a coupling of the shaft via the spur gear stage to one or more parallel shafts. In particular, the spur gears of the at least one spur gear stage are each embodied with helical teeth, on which the spur gears are in toothed engagement with one another.

The transmission according to the invention has at least one electric machine, which makes it suitable for use in hybrid or electric vehicles. The rotor of the electric machine is then connected directly or indirectly to the input shaft. Particularly preferably, but not exclusively, the transmission has two electric machines. In this case, the individual electrical machines can preferably be operated within the scope of the invention as generators on the one hand and as motors on the other hand. The "coupling" of the rotor of the respective electric machine to the shaft is to be understood in the sense of the present invention as a connection therebetween, so that a constant rotational speed relationship exists between the rotor of the respective electric machine and the respective shaft.

The invention now includes the technical teaching that a planetary stage is furthermore provided, which has a first, a second and a third element in the form of a sun gear, a planet carrier and a ring gear. The first element is connected in a rotationally fixed manner to the input shaft and the second element is coupled to the output side via a first spur gear stage, while the third element can be fixed by the second shift element and connected in a rotationally fixed manner to the drive shaft by means of the third shift element. Furthermore, the input shaft may be fixed by the fourth switching element.

In other words, the transmission according to the invention therefore has a planetary stage which comprises three elements, one of which is a sun gear, one of which is a planet carrier and one of which is a ring gear. Of these three elements, the first element is permanently connected to the input shaft in a rotationally fixed manner, while the second element is connected to the output side via the first spur gear stage. Furthermore, the third element of the planetary stage can be stopped by actuating the second shift element on the one hand and thus prevents a rotational movement, wherein the third element can be connected to the driveshaft in a rotationally fixed manner by closing the third shift element on the other hand. Finally, the input shaft can also be stopped by closing the fourth switching element and thus a rotational movement is prevented.

In this case, such a design of the transmission has the advantage that, via the planetary stages and their different shift states, on the one hand, the fixability of the third element and on the other hand its torque-proof connection to the driveshaft and the different possibilities of connection of the driveshaft to the input shaft, the drive machine and the electric machine connected upstream subsequently can be integrated into the power flow to the output side in a plurality of different ways. In this case, this is possible with a planetary stage having a compact design while the manufacturing effort is low. In this case, different hybrid functions can also be shown subsequently by the drive machine and the electric machine. In order to couple the drive shaft to the drive machine connected upstream, the intermediate starting element can be dispensed with, which further reduces the production costs.

In this case, the first shifting element and the fourth shifting element are particularly preferably combined to form a shifting device, wherein the shifting device has an actuating element by means of which the first shifting element and the fourth shifting element can be transferred from the neutral position into the closed state.

Alternatively or additionally to this, the second shifting element and the third shifting element also form a shifting device, by means of which the second shifting element and the third shifting element can be moved from a neutral position into an actuated state by a common actuating element. In particular, two of the aforementioned shifting devices are preferably implemented in the transmission according to the invention, as a result of which the manufacturing effort can be further reduced, since in this way four shift elements can be controlled with two actuating actuators.

According to one embodiment, a first gear between the drive shaft and the output side is achieved by actuating the first and second shift elements, while a second gear between the drive shaft and the output side can be achieved by closing the third and fourth shift elements. Furthermore, a third gear position between the drive shaft and the output side can be shifted by actuating the first and third shift elements. In this way, it is advantageously possible, from the transmission point of view, to realize three different gears between the drive shaft and the output side, which gears can therefore be used for driving by a drive machine connected upstream.

Instead, in particular in combination with the above-mentioned embodiment, a gear between the input shaft and the output side is also implemented by actuating the second shift element. In this case, the transmission ratio can be used for driving by the electric machine and thus for electric-only driving, wherein forward driving or backward driving can be provided depending on the direction of rotation induced by the electric machine.

The transmission according to the invention can be operated such that a charging operation or a starting operation is carried out, for which purpose the first shift element is closed. Since the drive shaft and the input shaft are connected to one another in a rotationally fixed manner by closing the first switching element, the electric machine connected to the input shaft can also start the drive machine connected upstream in motor mode operation or can be driven via the drive machine connected upstream in generator mode operation. Likewise, the charging operation or the starting operation can be carried out by actuating the third shift element, since the planetary stage in this case takes care of the coupling of the input shaft and the drive shaft when supporting the second element of the planetary stage via the output side.

Furthermore, as a further operating mode, a start mode for forward travel can be implemented when driving via the drive shaft and thus the drive machine connected upstream. For this purpose, the third switching element is closed, so that the drive machine is driven by the third element of the planetary stage and at the same time the electric machine is supported on the first element of the planetary stage, while the output is realized by the second element of the planetary stage and also by the first spur gear stage. Starting for forward travel can be achieved in this case by supporting the torque via the electric machine accordingly.

Furthermore, the parking lock can preferably be realized in that the second shift element and the fourth shift element are actuated simultaneously, which results in a simultaneous fixing of the first element and the third element of the planetary stage and thus also of the second element of the planetary stage. In addition, a simplified form of such a parking lock can be achieved by switching one of the gear positions acting between the drive input shaft and the output side, wherein the drive machine connected upstream is in each case coupled to the output side and the drag torque of the drive machine can thus be used to achieve the parking lock.

According to one embodiment of the invention, a further input shaft is provided, which is coupled with the rotor of the further electric machine. In one variant of this embodiment, the further input shaft is connected to the second element of the planetary stage. This has the advantage that, in its electric motor mode, the further electric machine can also selectively input a drive torque in parallel with the drive torque generated by the drive machine and/or the first electric machine, and thus the drive output can be increased. In this case, this can also be achieved during the operation or starting operation of the drive machine with the charging of the first electric machine, so that in parallel with the starting of the drive machine by the charging of the drive machine or by the first electric machine, the propulsion of the motor vehicle can still be achieved.

An alternative variant of this embodiment is that the further input shaft can be connected to the output side via the second spur gear stage by actuating the fifth shift element. The second spur gear stage can thus be used purely for the further input shaft and thus also for operation by means of an additional electric machine, as a result of which an independent coupling thereof to the output side can be achieved. In this way, a first gear between the further input shaft and the output side is achieved by closing the fifth shift element in such a way that the force flow is then directed from the further input shaft via the second spur gear stage to the output side. In this case, this can be done without consideration or also in parallel with the drive by the drive machine or the first electric motor, in order to be able to realize the assistance by the additional electric motor, i.e. additionally to the input torque.

In a further development of the second variant of this embodiment, the further input shaft can also be connected in a rotationally fixed manner to the second element of the planetary stage via a sixth shift element. Alternatively, the further input shaft can also be coupled to the output side via the third spur gear stage by closing the sixth shift element. In the latter case, a second gear is then realized between the further input shaft and the drive shaft by actuating the sixth shifting element, so that a further transmission ratio between the further input shaft and the driven side can be established. The second variant of this embodiment has the advantage over the permanent connection of the further input shaft to the second element of the planetary stage that the further electric machine can thus also be completely decoupled, which is accompanied by a reduction in the drag torque.

Within the scope of the invention, the further electrical machine can in particular likewise be operated as a generator on the one hand and as a motor on the other hand. In the generator mode of operation, the further electric machine can therefore be used for electrical energy recovery in the region of braking processes of the motor vehicle, while in the motor mode of operation, a drive torque can be supplied in a targeted manner. In this case, the further electric machines are particularly preferably of larger dimensions than the first electric machine, in order to be able to use them for purely electric driving. In this case, the two electric machines can therefore also be considered for jointly driving the motor vehicle by switching the respective gear between the input shaft and the output side or the further input shaft and the output side.

During the implementation of the start mode for forward driving, the fifth switching element or the sixth switching element can therefore be additionally closed, so that an additional torque is applied by the further electric machine during the start.

According to one embodiment of the invention, the second element of the planetary stage is connected in a rotationally fixed manner to a hollow shaft which is arranged coaxially to the drive shaft and the input shaft and is coupled to a countershaft, which is parallel to at least one axis, by means of a first spur gear stage. Furthermore, the at least one auxiliary shaft is connected to the output side. If, in addition, a second spur gear stage and, if appropriate, a third spur gear stage are provided, preferably in each case one loose gear of the second or third spur gear stage is rotatably mounted on the hollow shaft.

In a further development of the above-mentioned embodiment, the at least one auxiliary shaft and the output side are each coupled via an output constant. In this case, a drive constant is in particular formed by a spur gear stage in the form of two mutually meshing fixed gears, one of which is connected in a rotationally fixed manner to the at least one countershaft and one of which is connected in a rotationally fixed manner to the driven side. If several axially parallel countershafts are provided in the transmission according to the invention, each of the countershafts is coupled to the output side via an associated output constant, wherein the fixed gears disposed in a rotationally fixed manner on the countershafts are in toothed engagement with a common spur gear of the output constant.

In the sense of the invention, the spur gears of the driven constant which are arranged on the respective layshaft can also be formed by spur gears on the driven side of one of the spur gear stages, by means of which the second element of the planetary stage or the further input shaft is coupled or can be coupled to the driven side.

In a further development of the invention, the output side is formed by a disk drive gear of the differential. Alternatively, it is also conceivable within the scope of the invention for the output side to be formed by an output shaft which is coupled via a first spur gear stage to the second element of the planetary stage and, if appropriate, can be coupled via a further spur gear stage to the further input shaft.

According to an embodiment of the invention, the first element of the planetary stage is formed by the sun gear, the second element of the planetary stage is formed by the planet carrier if the planetary stage is designed as a negative planetary gear set and by the ring gear if the planetary stage is designed as a positive planetary gear set, and the third element of the planetary stage is formed by the ring gear if the planetary stage is designed as a negative planetary gear set and by the planet carrier if the planetary stage is designed as a positive planetary gear set.

In the minus planetary gear set, the planet carrier carries at least one, but preferably a plurality of planet gears which are each in individual toothed engagement both with the sun gear and with the ring gear. According to the invention, in this embodiment of the planetary stage, the first element is formed by the ring gear, the second element by the planet carrier and the third element by the ring gear.

If, on the other hand, the planet carrier is present as a plus planetary gear set, wherein the planet carrier rotatably guides at least one planet gear pair, one of the planet gears is in toothed engagement with the sun gear and one planet gear is in toothed engagement with the ring gear and the planet gears mesh with one another, the first element is in turn formed by the sun gear. In contrast to the embodiment as a negative planetary gear set, the second element is therefore a ring gear and the third element is a planet carrier. Compared to the negative planetary gear set, the standard transmission ratio of the further planetary stage is increased by 1.

In a further development of the invention, the rotor of the electric machine can be arranged coaxially with the input shaft. In this case, the rotor of the electric machine can be connected directly to the input shaft in a rotationally fixed manner or can also be coupled to the input shaft via one or more intermediate gear stages, wherein the latter makes possible a more advantageous design of the electric machine at higher rotational speeds and lower torques. The at least one gear stage can be embodied as a spur gear stage and/or a planetary stage.

Preferably, however, the electric machine is arranged offset to the input shaft axis, wherein the coupling is effected by one or more intermediate gear stages and/or traction mechanism gears. The one or more gear stages can also be embodied in detail here as spur gear stages or planetary stages. The traction mechanism drive may be a belt drive or a chain drive.

Furthermore, if a further electric machine is provided, it is particularly preferred that the further electric machine is arranged coaxially to the further input shaft, wherein the rotor of the further electric machine can thus be coupled directly to the further input shaft in a torque-proof manner or via one or more intermediate gear stages. Alternatively, it is also conceivable, however, for the further electric machine to be disposed offset with respect to the further input shaft axis and for the coupling to be realized by one or more gear stages or by the traction mechanism gear.

One design possibility of the invention is that the individual shift elements are present as form-fitting shift elements, in particular as jaw shift elements. Alternatively, the form-locking shift element can also be a lock-up synchronization. The form-locking shift elements basically have the advantage that they have only a low drag torque in the open state and are correspondingly characterized by a high efficiency. Alternatively, however, the individual shift elements can also be designed as force-fitting shift elements, for example as film-forming shift elements, wherein the force-fitting shift elements can advantageously also be transferred into an actuated state under load.

Within the scope of the invention, a starting element, for example a hydrodynamic torque converter or a friction clutch, can be connected upstream of the transmission. The starting element may thus be a component of the transmission and be used to configure the starting process by enabling a slip speed (Schlupfdrehzahl) between the internal combustion engine and the drive shaft of the transmission. In particular, the drive shaft is preferably coupled, in the installed state of the transmission, but without a starter element located in between, to an upstream drive machine, wherein a torsional vibration damper can be inserted in the middle, in particular in the case of the drive machine embodied as an internal combustion engine. In addition, a freewheel can in principle be arranged on each axle of the transmission relative to the transmission housing or relative to the other axle.

The transmission according to the invention is part of a motor vehicle drive train, in particular for a hybrid or electric vehicle, and is therefore arranged between a drive machine of the motor vehicle, which is designed as an internal combustion engine or as an electric machine, and further components of the drive train which are behind in the direction of the force flow to the drive wheels of the motor vehicle. The first driveshaft of the transmission is either permanently coupled to a crankshaft of the internal combustion engine in a rotationally fixed manner or can be connected to the crankshaft via a separating clutch or a starting element located therebetween, wherein a torsional vibration damper can also be provided between the internal combustion engine and the transmission. Even in the case of a drive machine embodied as an electric motor, a direct rotationally fixed connection of the drive shaft to the rotor of the electric motor can be achieved. On the output side, the transmission is then preferably coupled in the vehicle drive train to a differential of a drive axle of the vehicle, although there may also be a connection to a longitudinal differential via which the distribution to a plurality of driven axles of the vehicle takes place. The differential or longitudinal differential can be arranged in a common housing with the transmission. Likewise, the torsional vibration damper which is optionally present can also be integrated into the housing.

In the sense of the present invention, two structural elements of a transmission are "connected" or "coupled" or "connected to one another" in such a way that they are permanently coupled, so that they cannot rotate independently of one another. In this connection, no shift elements are provided between the structural elements (which may be elements of the planetary stage and/or spur gears of the spur gear stage and/or anti-torsion structural elements of the shaft and/or transmission), but rather the corresponding structural elements are rigidly coupled to one another.

If a switching element is provided between two components, these components are not permanently coupled to one another, but rather only by actuating the switching element located between them. In this context, in the sense of the present invention, actuating the switching elements means bringing the switching elements concerned into the closed state and subsequently coordinating the structural elements directly connected thereto in terms of their rotational movement. In the case of a shift element in question which is designed as a form-fitting shift element, the structural elements which are directly connected to one another in a rotationally fixed manner thereby operate at equal rotational speeds, while in the case of a non-positive shift element, after actuation of the shift element, there may also be a rotational speed difference between the structural elements. However, within the scope of the invention, such a desired or undesired state is referred to as a torsionally fixed connection of the respective structural element by the switching element.

The invention is not limited to the combinations given of the features of the main claim or its dependent claims. Furthermore, the following possibilities exist: the individual features of the claims, the following description of preferred embodiments of the invention or directly from the drawings are combined with one another. The claims should not limit their scope by reference to the drawings by the use of reference signs.

Drawings

In the drawings, there are shown advantageous embodiments of the invention which are set forth below. In the drawings:

fig. 1 shows a schematic view of a motor vehicle drive train;

FIG. 2 shows a schematic diagram of a portion of the automotive powertrain of FIG. 1 having a transmission according to a first embodiment of the present invention;

FIG. 3 illustrates an exemplary shift schedule for the transmission of FIG. 2;

fig. 4 shows a diagram in table form of different operating modes of the motor vehicle drive train according to fig. 2;

fig. 5 shows a schematic representation of a part of the motor vehicle drive train from fig. 1 with a transmission according to a second design possibility of the invention;

FIG. 6 shows a schematic diagram of a portion of the automotive powertrain of FIG. 1 having a transmission according to a third embodiment of the present invention;

FIG. 7 shows a schematic sketch of the part of the motor vehicle powertrain of FIG. 6;

FIG. 8 illustrates an exemplary shift pattern for the transmission of FIG. 5 or FIG. 6;

fig. 9 shows tabular representations of different operating modes of the motor vehicle drive train according to fig. 5 or 6 and 7.

Detailed Description

Fig. 1 shows a schematic representation of a motor vehicle drive train of a hybrid vehicle, in which an internal combustion engine 2 is connected to a transmission 4 via a torsional vibration damper 3 located therebetween. Downstream of the transmission 4 on the output side, a differential 5 is connected, via which the drive power is distributed to the drive wheels 6 and 7 of the drive axle of the motor vehicle. In this case, the transmission 4 and the torsional vibration damper 3 are arranged in a common transmission housing 8 of the transmission 4, into which the differential 5 can also be integrated. As can also be seen in fig. 1, the internal combustion engine 2, the torsional vibration damper 3, the transmission 4 and the differential 5 are oriented transversely to the direction of travel of the motor vehicle.

Fig. 2 shows a schematic representation of a part of the motor vehicle drive train from fig. 1 in the region of a transmission, wherein the transmission is designed according to a first embodiment of the invention. The transmission 4 comprises a drive shaft 9, an input shaft 10 and a further input shaft 11, which are arranged coaxially with one another. The drive shaft 9 is connected in a rotationally fixed manner to the torsional vibration damper 3 and is designed as a solid shaft which extends over substantially the entire axial structural length of the transmission 4. The input shaft 10 and the further input shaft 11 are each present as hollow shafts, wherein the two hollow shafts in this case axially overlap the drive shaft 9 and are arranged radially around it. The input shaft 10 is located radially between the drive shaft 9 and the further input shaft 11.

The input shaft 10 is coupled to a rotor 12 of an electric machine 13, wherein the electric machine 13 is arranged axially offset from the input shaft 10 and has, in addition to the rotor 12, a stator 14 which is permanently fixed to the transmission housing 8. The coupling between the rotor 12 and the input shaft 10 is realized here by a spur gear stage 15, which is assembled from three

spur gears

16, 17 and 18. The spur gear 16 is arranged on a rotor shaft 19 in a rotationally fixed manner, via which rotor shaft 19 the spur gear 16 is connected to the rotor 12 in a rotationally fixed manner. The spur gear 16 meshes with a spur gear 17, which spur gear 17 is at the same time in toothed engagement with a spur gear 18 of the spur gear stage 15. The spur gear 18 is then placed on the input shaft 10 in a rotationally fixed manner. The electric machine 13 can be operated as a motor on the one hand and as a generator on the other hand.

In addition to the electric machine 13, a further electric machine 20 is provided which is assembled from a rotor 21 and a stator 22 and which likewise can be operated as a motor on the one hand and as a generator on the other hand. In this case, the stator 22 of the further electric machine 20 is also fixed to the transmission housing 8, while the rotor 21 is permanently connected in a rotationally fixed manner to the further input shaft 11. The further electric machine 20 is arranged coaxially with the further input shaft 11 and therefore also coaxially with the input shaft 10 and the drive shaft 9.

In addition to the drive shaft 9 and the two

input shafts

10 and 11, the transmission 4 in fig. 2 also has a countershaft 23, which is arranged axially offset from the drive shaft 9 and the two

input shafts

10 and 11. The countershaft 23 is permanently coupled to the further input shaft 11 via a spur gear stage 24, which has a spur gear 25 and a spur gear 26. In this case, a spur gear 25 is arranged on the further input shaft 11 in a rotationally fixed manner and meshes with a spur gear 26, which is arranged on the countershaft 23 in a rotationally fixed manner. In addition to the spur gear 26, the countershaft 23 carries a spur gear 27 which is placed on the countershaft 23 in a rotationally fixed manner and is in toothed engagement with a disk-shaped drive gear 28 of the differential 5 which is arranged parallel to the axis. The disk drive gear 28 here forms the output side 29 of the transmission 4. In this connection, the spur gear 27 and the disk drive gear 28 together form a drive output constant, by means of which the countershaft 23 is permanently coupled to the drive output side 29.

As can be seen in fig. 2, the transmission 4 further comprises a planetary stage 30, which is assembled from a first element 31, a second element 32 and a third element 33. The first element 31 is formed by a sun gear 34, the second element 32 by a planet carrier 35 and the third element 33 by a ring gear 36. The carrier 35 in this case supports a plurality of planet gears which are in toothed engagement with a radially inner sun gear 34 and with a radially outer ring gear 36. In this regard, the planetary stage 30 is embodied here as a negative planetary gear set. The planetary stage 30 is also arranged coaxially with the

input shafts

10 and 11 and the drive shaft 9, wherein the planetary stage 30 is arranged here substantially axially overlapping and radially inside the further electric machine 20.

In principle, however, it is also conceivable within the scope of the invention to design the planetary stage 30 as a spur planetary gearset, in which at least one planetary gear pair is rotatably mounted on a carrier, of which one planetary gear is in toothed engagement with the sun gear and one planetary gear is in toothed engagement with the ring gear, and which also mesh with one another. Furthermore, compared to the embodiment as a negative planetary gear set, the connection of the ring gear and the connection of the planet carrier can be interchanged and the standard transmission ratio of the planetary stages can be increased by 1.

The sun gear 34 of the planetary stage 30 is connected in a rotationally fixed manner to the input shaft 10, while the planet carrier 35 is connected in a rotationally fixed manner to the further input shaft 11 and is correspondingly also permanently coupled to the countershaft 23 via the spur gear stage 24 and thus also to the output side 29.

The transmission 4 also has four shift elements U, D, V and a, wherein these shift elements U, D, V and a are designed as form-fitting shift elements in the form of claw shift elements. The shift elements U and a are present here as brakes, while the shift elements D and V are clutches.

The shift element U fixes the input shaft 10 to the transmission housing 8 during actuation and then prevents it from rotating. If the switching element D is closed, the drive shaft 9 and the input shaft 10 are connected to one another in a rotationally fixed manner. If the shift element V is actuated, the ring gear 36 is connected to the driveshaft 9 in a rotationally fixed manner, while closing of the shift element a causes the ring gear 36 to be fixed to the transmission housing 8, so that the ring gear 36 is then prevented from rotating.

The shift element U and the shift element D are combined in the present case to form a shifting device 37, by means of which the shift element U on the one hand and the shift element D1 on the other hand can be transferred from the neutral position into the closed state by means of their actuation devices (not shown in any further detail in the present case). Likewise, the shift element V and the shift element a also form a shifting device 38, in which the shift element V on the one hand and the shift element a on the other hand can be actuated from a neutral position via a common actuating device.

At the axial end of the transmission 4, at which it is connected to the drive shaft 9 on the torsional vibration damper 3, the shifting device 37, then the spur gear stage 15, then the output side 29 and the spur gear stage 24 are axially followed, the electric motor 13 being substantially axially superposed on this spur gear stage, then the further electric motor 20 and the planetary stage 30 and finally the shifting device 38.

Fig. 3 shows an exemplary shifting diagram for the transmission 4 from fig. 2 in the form of a table. As can be seen, different gears V1, V2, V3, E1, EDA-V can be realized in this case, wherein in the columns of the shift diagram which of the shift elements U, D, V and a is respectively closed is marked with X.

As can be seen from fig. 3, the first gear V1 between the drive shaft 9 and the output side 29 is shifted by closing the shift element a and the shift element D, so that the internal combustion engine 2 is coupled via the drive shaft 9, the input shaft 10 connected in a rotationally fixed manner thereto, and the planetary stage 30 via the fixed ring gear 36 to the further input shaft 11, from which the force flow is conducted via the spur gear stage 24 to the countershaft 23 and then further to the output side 29. The second gear V2 between the drive shaft 9 and the driven side 29 is achieved by closing the shift elements V and U, whereby the drive shaft 9 is connected in a rotationally fixed manner to the ring gear of the planetary stage 30, while the sun gear 34 of the input shaft 10 is fixed and then output via the planet carrier 35 to the further input shaft 11, which is coupled to the driven side 29 via the spur gear stage 24 and the countershaft 23. Furthermore, a third gear V3 between the drive shaft 9 and the output side 29 is achieved by simultaneous actuation of the shift elements V and D, so that both the sun gear 34 and the ring gear 36 are each connected in a rotationally fixed manner to the drive shaft 9, which effects a blocking of the planetary stage 30 and thus a rigid direct drive transmission (durchtriib) to the further input shaft 11. The further input shaft is then permanently coupled to the output side 29, as in the two previous gears V1 and V2.

A gear E1 can be realized between the input shaft 10 and the output side 36 in such a way that only the shift element a is closed, so that the ring gear 36 is fixed to the transmission housing 8, while the electric machine 13 can drive the input shaft 10 via the spur gear stage 15 and can output via the planet carrier 35, via the further input shaft 11, the spur gear stage 24 to the countershaft 23 and thus also to the output side 29. Due to the permanent, rotationally fixed connection of the rotor 21 of the further electric machine 20 to the further input shaft 11, which is of course permanently coupled via the spur gear stage 24 to the countershaft 23 and thus also to the output side 29, a drive can be realized at any time in the motor mode operation of the further electric machine 20 and a current generation can be realized at any time in the generator mode operation thereof. However, the further electric motor 20 is also permanently dragged thereby.

In addition, an electrodynamic starting of the motor vehicle can be achieved in the gear EDA-V, for which only the shift element V is actuated. The drive shaft 9 and therefore the internal combustion engine 2 are thus also connected to the ring gear 36 of the planetary stage 30, so that driving can be effected via the ring gear 36. At the same time, the electric machine 13 can support the torque via the sun gear 34 of the planetary stage 30, while the output is realized via the planet carrier 35 toward the output side 29. By corresponding control of the internal combustion engine 2 and the electric machine 13 and, if appropriate, the further electric machine 20, a starting operation of the motor vehicle in forward travel can be achieved.

Different operating modes I to XII of the motor vehicle drive train 1 can be realized by means of the transmission 4 in fig. 2, which operating modes are shown in table form in fig. 4: in the operating mode I, the switching element V is actuated in order to carry out a charging operation or a starting operation of the internal combustion engine 2 in the stationary state of the motor vehicle. The former is achieved here in that the internal combustion engine 2 drives the ring gear 36 of the planetary stage 30, while the output is delivered via the sun gear 34 to the electric machine 13, which operates as a generator, and is supported on the carrier 35 of the planetary stage 30 by the vehicle mass. Conversely, to start the internal combustion engine 2, it is driven by the electric machine 13 as an electric motor and is output to the internal combustion engine 2 via the ring gear 36 of the planetary stage 30 in order to start the internal combustion engine.

In operating mode II, a charging operation or a starting operation can also be carried out, wherein in this case the switching element D is switched into the closed state. The drive shaft 9 and the input shaft 10 are therefore connected to one another in a rotationally fixed manner, so that the internal combustion engine 2 and the electric machine 13 are also coupled to one another via the spur gear stage 15. Here, the charging of the electrical energy store takes place again by driving the internal combustion engine 2 and by generator operation of the electric machine 13, while a starting of the internal combustion engine 2 can be completed in the case of motor operation of the electric machine 13.

In operating mode III, however, parking lock is achieved by simultaneous actuation of the switching elements a and U. This results in the carrier 35 and therefore ultimately also the driven side 29 being fixed, as a result of the accompanying fixation of both the sun gear 34 via the input shaft 10 and the ring gear 36.

In operating modes IV to VI, the vehicle is then driven purely internal combustion, by shifting in each case one of the gears V1 to V3, as already described with reference to fig. 3. In operating mode VII, the electric machine 13 is driven purely electrically in its motor mode, for which purpose the gear E1 is shifted. This is also described in fig. 3 in the preparation phase. The implementation of the electrodynamic starting EDA-V, which is shown in the present case in operating mode VIII and for which the switching element V is actuated, is also already carried out in the preparation phase for fig. 3.

In operating mode IX, a series operation can then be achieved by closing the switching element D, wherein a current is generated by the generator operation of the internal combustion engine 2 and the electric machine 13 by means of a rotationally fixed connection between the drive shaft 9 and the input shaft, while the electric machine 20 is driven purely electrically in its electric motor operation. In the other operating modes X to XII, a hybrid drive is then carried out by switching in each case one of the gears V1 to V3 and simultaneously driving the internal combustion engine 2 and the further electric machine 20. In operating modes X and XII, in addition, drive torques can also be supplied by electric machine 13. In the operating modes X to XII, a common braking can also be carried out by the internal combustion engine 2 and the further electric machine 20 and, if appropriate, the electric machine 13, respectively, in such a way that the internal combustion engine 2 is in drag operation and the further electric machine 20 and, if appropriate, the electric machine 13 are operated as generators.

Fig. 5 shows a schematic representation of a part of the motor vehicle drive train 1 from fig. 1, which, however, in this case has a transmission 4' corresponding to a second design possibility of the invention. The design possibility corresponds essentially to the variant in fig. 2, with the difference that the planet carrier 35 of the planet stage 30 and the spur gear 25 of the spur gear stage 24 are connected to one another in a rotationally fixed manner in this case by a hollow shaft 39 arranged coaxially to the drive shaft 9 and the input shaft 10. The hollow shaft 39 is arranged radially around the input shaft 10. A further input shaft 11', which is connected in a rotationally fixed manner to the rotor 21 of the further electric machine 20 analogously to fig. 2, can be connected in a rotationally fixed manner to the hollow shaft 39 via a shift element H, wherein the further input shaft 11' can alternatively be connected in a rotationally fixed manner to a further hollow shaft 40 by actuating the shift element L. A spur gear 41 is fixedly mounted on the hollow shaft 40, is part of a spur gear stage 42 and is permanently in toothed engagement with a spur gear 43 inside the spur gear stage 42. In this case, the spur gear 43 is in turn placed on the countershaft 23 in a rotationally fixed manner, so that the spur gear stage 42 couples the countershaft 23 and the hollow shaft 40 to one another.

The shift elements L and H are combined in the present case to form a shifting device 44, which can be shifted from a neutral position into a corresponding actuated state by their actuating device (not shown in further detail in the present case). The shifting device 44 is arranged axially at the level of the further electric machine 20 and radially inwardly with respect to the latter. Furthermore, a spur gear stage 42 is arranged axially between the spur gear stage 24 and the further electric machine 20. For the rest, the design possibilities according to fig. 5 correspond to the variant according to fig. 2, so reference is made to what is described here.

Fig. 6 shows a schematic representation of a part of the motor vehicle drive train from fig. 1 with a transmission 4 ″ according to a third embodiment of the invention. This embodiment corresponds essentially to the variant described above with reference to fig. 5, in which, in contrast, the further input shaft 11 ″ can be connected via a shift element H' to a spur gear 35, which is part of a spur gear stage 46, in a rotationally fixed manner. The spur gear 45 is in toothed engagement with a further spur gear 47, which is placed on the countershaft 23 in a rotationally fixed manner. In this regard, the further input shaft 11 'can be coupled to the countershaft 23 via the spur gear stage 45 by closing the shift element H'. As already in the variant according to fig. 5, the further input shaft 11' can be connected in a rotationally fixed manner to the hollow shaft 40 by closing the shift element L. The torque-proof connection of the further input shaft 11' to the planet carrier 35 is not possible in the case of the variant according to fig. 6.

The shift element L and the shift element H' are in turn assembled to form a shifting device 44, which, however, are now replaced in the axial direction in comparison with the variant according to fig. 5. In this case, the further spur gear stage 46 is arranged axially between the shifting device 44 and the spur gear stage 42. In other cases, the variant according to fig. 6 corresponds to the variant described above with reference to fig. 5, and reference is therefore made to what is described here.

Fig. 7 also shows a schematic representation of the part of the motor vehicle drive train 1 from fig. 6, from which the connection or the possibility of connecting the individual components of the transmission 4 ″ can be seen.

Fig. 8 shows an exemplary shifting scheme of the transmission 4' from fig. 5 and of the transmission 4 ″ from fig. 6 and 7, wherein the scheme largely corresponds to the shifting scheme from fig. 3. Thus, even though the gears V1 to V3, E1 and EDA-V can be realized as gears in the transmission 4' or 4 ″, reference is made in respect of which to what has been described with respect to fig. 3, respectively. Additionally, the gears E2, E3, EDA-V2 and EDA-V3 can still be implemented, wherein the shift element L is actuated in order to assume the gear E2 acting between the further input shaft 11 ″ and the output side, so that the further input shaft 11 ″ is connected in a rotationally fixed manner to the hollow shaft 40. The further input shaft 11 ″ is thereby coupled via the spur gear stage 42 to the countershaft 23 and thus also to the output side 29.

For shifting the gear E3, the shift element H or H' is shifted into the actuated state, so that the further input shaft 11 ″ is connected in a rotationally fixed manner to the hollow shaft 39 and thus also to the planet carrier 35 and the spur gear 25 or to the spur gear 45. As a result, the further input shaft 11 ″ is then also coupled via the

spur gear stage

24 or 26 to the countershaft 23 and thus also to the output side 29.

The gears EDA-V2 and EDA-V3 are each used to form an electrodynamic start, similarly to what has already been described for the gears EDA-V of fig. 3. In the gear position EDA-V2, the shift element L is also shifted into the closed state in addition to the shift element V, so that the further electric machine 20 can also be assisted during starting by the spur gear stage 42. In the gear position EDA-V3, the shift element H or H' is closed in addition to the shift element V, so that the further electric machine 20 is assisted during the start-up process on the driven planet carrier 35 of the planetary stage 30 or is connected via the spur gear stage 46 and can likewise be assisted.

Even in the motor vehicle drive train with the transmission 4' or 4 ″ according to fig. 5 or 6 and 7, different operating modes can be implemented, which are shown in table form in fig. 9. In addition to the operating modes I to VIII already described in the preparation phase for fig. 4, further operating modes XIII to XXVI can also be described, which are only briefly described in each case: in operating modes XIII and XIV, pure electric drive is thus achieved by the additional electric machine 20, by shifting gear E2 or gear E3 in transmission 4' or 4 ″. The corresponding representation of the gear E2 or the gear E3 has already been described in relation to fig. 8.

In the operating modes XV and XVI, respectively, an electric-powered start of the motor vehicle is then effected, for which purpose the gear EDA-V2 or EDA-V3 is shifted, as was also described with reference to fig. 8. In the operating mode XVII, a series operation is shown, in which the switching elements D and L are closed. By means of the closed switching element D, the drive shaft 9 is thereby coupled to the input shaft 10 and therefore the internal combustion engine 2 is also coupled to the electric machine 13, so that charging of the electrical energy store is possible by driving via the internal combustion engine 2 and in generator mode operation of the electric machine 13. At the same time, the further electric machine 20 can be operated purely electrically in its electric motor mode, for which purpose the gear E2 in the transmission 4' is shifted.

In the operating mode XVIII, the series operation is likewise implemented, but in this case, unlike the operating mode XVII, the switching element H or H' is actuated instead of the switching element L. In this case, in parallel with the charging by electric machine 13, purely electric driving by additional electric machine 20 is thus achieved, wherein this takes place in gear E3.

In operating modes XIX to XXIV, a hybrid operation is shown, in which gears V1 to V3 are combined with gears E2 and E3. This allows a simultaneous drive by the internal combustion engine 2 and also by the additional electric machine 20, wherein the electric machine 13 can also be additionally assisted in this case. A common braking can be achieved by the internal combustion engine 2 in its drag mode and by the further electric machine 20 and, if appropriate, the electric machine 13 in the respective generator mode.

Finally, in both operating modes XXV and XXVI, the two

electric machines

13 and 20 are operated purely electrically in their respective electric motor mode, wherein in operating mode XXV the gears E1 and E2 are shifted in this case and in operating mode XXVI the gears E1 and E3 in the transmission 4' or 4 ″ are shifted.

With the configuration according to the invention, a compactly designed transmission can be realized at low production costs.

Reference numerals

1. Motor vehicle drive train

2. Internal combustion engine

3. Torsional vibration damper

4. 4', 4' speed variator

5. Differential gear

6. Driving wheel

7. Driving wheel

8. Transmission housing

9. Drive shaft

10. Input shaft

11. 11' additional input shaft

12. Rotor

13. Electric machine

14. Stator

15. Spur gear stage

16. Spur gear

17. Spur gear

18. Spur gear

19. Rotor shaft

20. Electric machine

21. Rotor

22. Stator

23. Auxiliary shaft

24. Spur gear stage

25. Spur gear

26. Spur gear

27. Spur gear

28. Disk-shaped driving gear

29. Driven side

30. Planetary stage

31. First element

32. Second element

33. Third component

34. Sun wheel

35. Planet carrier

36. Gear ring

37. Gear shifting device

38. Gear shifting device

39. Hollow shaft

40. Hollow shaft

41. Spur gear

42. Spur gear stage

43. Spur gear

44. Gear shifting device

45. Spur gear

46. Spur gear stage

47. Spur gear

U fourth switching element

Vthird switching element

A second switching element

D first switching element

L fifth switching element

H sixth switching element

H' sixth switching element

V1 gear

V2 gear

V3 gear

E1 Gear position

E2 Gear position

E3 Gear position

EDA-V gear

EDA-V1 gear

EDA-V2 gear

I to XXVI modes of operation

Claims

1. A transmission (4 '; 4') for a motor vehicle, comprising a drive shaft (9) and an input shaft (10), the drive shaft and the input shaft can be coupled to the output side (29) via at least one spur gear stage (24), the drive shaft (9) is designed to connect the transmission (4, the input shaft (10) is coupled to a rotor (12) of an electric machine (13), furthermore, the drive shaft (9) and the input shaft (10) can be connected to each other in a rotationally fixed manner by closing the first switching element (D), characterized in that a planetary stage (30) is also provided, which has a first element (31), a second element (32) and a third element (33) in the form of a sun gear (34), a planet carrier (35) and a ring gear (36), the first element (31) is connected to the input shaft (10) in a rotationally fixed manner and the second element (32) is coupled to the output side (29) via a first spur gear stage (24), while the third element (33) can be fixed by means of a second switching element (A) on the one hand and can be connected in a rotationally fixed manner to the drive shaft (9) by means of a third switching element (V) on the other hand, and the input shaft (10) can be fixed by means of a fourth switching element (U).

2. Transmission (4, 4';4 ") according to claim 1,

-a first gear (V1) between the drive shaft (9) and the driven side (29) is obtained by operating a first switching element (D) and a second switching element (A),

-a second gear (V2) between the drive shaft (9) and the driven side (29) is obtained by closing a third switching element (V) and a fourth switching element (U), and

-a third gear (V3) between the drive shaft (9) and the driven side (29) is obtained by operating a first switching element (D) and a third switching element (V).

3. Transmission (4, 4'; 4') according to claim 1 or 2, characterized in that one gear (E1) between the input shaft (10) and the driven side (29) is obtained by operating a second shift element (A).

4. Transmission (4) according to any of claims 1 to 3, characterized in that a further input shaft (11) is provided which is coupled with the rotor (21) of a further electrical machine (20), which further input shaft (11) is in connection with the second element (32) of the planetary stage (30).

5. Transmission (4 '; 4') according to any one of claims 1 to 3, characterized in that a further input shaft (11 ') is provided, which is coupled with the rotor (21) of a further electric machine (20), which further input shaft (11') can be connected with the driven side (29) via a second spur gear stage (42) by operating a fifth switching element (L).

6. Transmission (4 ';4 ') according to claim 5, characterized in that the first gear (E2) between the further input shaft (11 ') and the driven side (29) is obtained by closing a fifth switching element (L).

7. Transmission (4 ') according to claim 5 or 6, characterized in that the further input shaft (11') is further connectable torsionally with the second element (32) of the planetary stage (30) via a sixth shift element (H).

8. Transmission (4 ") according to claim 5 or 6, characterized in that the further input shaft (11 ') can also be coupled with the driven side (29) via a third spur gear stage (46) by closing a sixth switching element (H').

9. Transmission (4 ") according to claim 7 or 8, characterized in that the second gear (E3) between the further input shaft (11 ') and the driven side (29) is obtained by operating a sixth switching element (H; H').

10. Transmission (4 '; 4') according to any one of the preceding claims, characterized in that the second element (32) of the planetary stage (30) is connected torsionally stiff with a hollow shaft (11, 39) placed coaxially with the drive shaft (9) and the input shaft (10) and coupled via a first spur gear stage (24) with at least one axially parallel countershaft (23), said at least one countershaft (23) being in connection with the driven side (29).

11. Transmission (4 ';4 ') according to any one of claims 5 to 8 and claim 10, characterized in that said second spur gear stage (42) and/or a third spur gear stage (46) are provided between said further input shaft (11 ') and said at least one countershaft (23).

12. Transmission (4'; 4 ") according to claim 10 or 11, characterized in that said at least one countershaft (23) is coupled with said driven side (29) by an output constant, respectively.

13. Transmission (4 '; 4') according to any one of the preceding claims, characterized in that the driven side (29) is constituted by a disk-shaped driving gear (28) of the differential (5).

14. Transmission (4 '; 4') according to any one of the preceding claims, characterized in that the first element (31) of the planetary stage (30) is constituted by a sun gear, the second element (32) of the planetary stage (30) is constituted by a planet carrier (35) in case the planetary stage (30) is embodied as a negative planetary gear set and by a ring gear in case the planetary stage is embodied as a positive planetary gear set, and the third element (33) of the planetary stage (30) is constituted by a ring gear (36) in case the planetary stage (30) is embodied as a negative planetary gear set and by a planet carrier in case the planetary stage is embodied as a positive planetary gear set.

15. Transmission (4 ';4 ') according to one of the preceding claims, characterized in that each shift element (V, A, U, D; V, A, U, D, L, H ') is embodied as a form-locking shift element, in particular as a dog shift element.

16. Automotive power train, in particular for a hybrid vehicle or an electric vehicle, comprising a transmission (4.

17. Method for operating a transmission (4 '; 4') according to claim 1, characterized in that only the first shift element (D) or the third shift element (V) is closed for the purpose of carrying out a charging operation or a starting operation.

18. Method for operating a transmission (4 '; 4') according to claim 1, characterized in that, in order to achieve a starting mode for forward travel when driven by the drive shaft (9), the third shift element (V) is closed.

19. Method according to claim 18 and for operating a transmission (4 ';4 ') according to one of claims 5 to 9, characterized in that additionally the fifth shift element (L) or the sixth shift element (H; H ') is closed.