Powertrain for a vehicle

Abstract

A drive train for a vehicle, comprising an internal combustion engine (VM) arranged coaxially to a first axis (A1), at least one first electric machine (EM1) and a second electric machine (EM2), and a transmission arrangement (G) connectable to an output (Ab), wherein the first electric machine (EM1) is dimensionally larger than the second electric machine (EM2), and wherein the second electric machine (EM2) is connectable at least to the internal combustion engine (VM) and the first electric machine (EM1) is connectable at least to the transmission arrangement (G), wherein the first electric machine (EM1) and the second electric machine (EM2) are arranged offset from each other with respect to their rotor axes, characterized in thatthat the second electric machine (EM2) can be connected via a shaft (W) arranged coaxially to the first axis (A1) to a first gearbox input shaft (W1) of the gearbox arrangement (G) arranged coaxially to the second axis (A2) without reversing the direction of rotation, and that a rotor of the first electric machine (EM1) can be connected to a second gearbox input shaft (W2) of the gearbox arrangement (G) arranged coaxially to the second axis (A2).

Description

[0001] The present invention relates to a powertrain for a vehicle of the type defined in more detail in the preamble of claim 1. The invention further relates to a vehicle with the powertrain.

[0002] In automotive engineering, drive trains for vehicles with an internal combustion engine and two electric machines, both assigned to the same axle, are known. Furthermore, a multi-stage transmission arrangement is provided, connected to an output shaft. Axially, the electric machines are arranged sequentially after the internal combustion engine and a torsional damper. A superimposed gear set is located between the electric machines. One of the electric machines has significantly smaller dimensions, specifically a significantly smaller outer diameter, and serves as a starter-generator for the internal combustion engine, while the other electric machine has significantly larger dimensions and serves as the drive system.

[0003] It has been shown that electric motors used as drive systems require a large amount of installation space, as they need considerable dimensions in terms of their outer diameter and axial length. Therefore, these electric motors should be positioned as close as possible to the combustion engine, since that is where the most installation space is available. A coaxial arrangement of the electric motor significantly limits the available installation space.

[0004] US Patent 2004 / 0144576A1 discloses a drive system for an electric vehicle comprising a machine-driven electric generator and a motor for driving drive wheels using electrical energy from the electric generator. The drive system includes an internal combustion engine-side input shaft connected to and driven by the internal combustion engine's crankshaft, and an electric motor-side input shaft connected to and driven by the electric motor's rotor. Furthermore, an output shaft is provided, connected to both the internal combustion engine-side and electric motor-side input shafts, which transmits drive power to the drive wheels.Furthermore, a gearbox is provided which is located in an engine power transmission channel formed by the internal combustion engine-side input shaft and the output shaft, wherein the speed of the engine power transmission channel can be switched into several switching ranges.

[0005] US Patent 2017 / 0 217 298 A1 discloses an electro-hydraulic hybrid drive system comprising an internal combustion engine, a first electric motor, a second electric motor, a first planetary gear set, a second planetary gear set, and a hydraulic control switch assembly connected to the internal combustion engine. The first electric motor is axially connected to the internal combustion engine, and the second electric motor is axially connected to the first and second planetary gear sets. The first planetary gear set is coaxially connected to the second planetary gear set. The hydraulic control switch assembly comprises a first gear and a second gear, with a double wet clutch arranged between the first and second gears. The first gear, the second gear, and the double wet clutch are coaxially connected to the internal combustion engine.

[0006] Further drive trains of the same type are disclosed in DE 10 2005 035 328 A1 and JP 2011 - 011 706 A.

[0007] The present invention is based on the objective of proposing a drive train and a vehicle of the type described above in which the electric machines are arranged in the most space-saving way possible.

[0008] This problem is solved according to the invention by the features of claim 1 or 16. Advantageous and claimed embodiments are described in the dependent claims, the description, and the drawings.

[0009] Thus, a powertrain for a vehicle with an internal combustion engine arranged coaxially to a first axle is proposed. Furthermore, the powertrain comprises at least a first electric machine and a second electric machine, wherein the first electric machine is larger in size and therefore suitable as a drive system, and the second electric machine is smaller and therefore suitable as a starter-generator for the internal combustion engine. In addition, a multi-stage transmission arrangement is provided, which can be connected to an output shaft. Furthermore, the powertrain provides that the second electric machine can be connected at least to the internal combustion engine and the first electric machine can be connected at least to the transmission arrangement.In order to arrange the differently dimensioned electric machines in the proposed drive train in the most space-saving way possible, it is provided that the first electric machine and the second electric machine are arranged offset from each other with respect to their rotor axes.

[0010] In the proposed powertrain, the smaller second electric machine can thus be positioned as close as possible to the combustion engine with the first, larger electric machine. The offset arrangement of the two electric machines allows for optimal use of the available installation space.

[0011] If, within the context of an offset arrangement of the electric motors, the second electric motor is arranged coaxially to the first axis and the first electric motor is arranged coaxially to a second axis, with the first and second axes offset from each other, this results, for example in a vehicle with a longitudinally mounted front engine, in more radial installation space available for the first electric motor, for example in the vehicle tunnel. The axis offset can be selected such that the outer diameter of the electric motors can be as large as possible while simultaneously maintaining sufficient underbody clearance in the vehicle.

[0012] An alternative embodiment of the offset arrangement of the electric machines can provide for the second electric machine to be arranged coaxially to a fourth axis, with the fourth axis being offset from the first axis, which corresponds, for example, to the crankshaft axis of the internal combustion engine, and from the second axis, which corresponds, for example, to the rotor axis of the first machine. Such an axially parallel arrangement of the rotor axis of the second electric machine to the axes of rotation of the internal combustion engine and the first machine allows for an alternative utilization of the available installation space by positioning the second electric machine radially outwards, thus providing additional installation space for the first electric machine.

[0013] In this alternative axially parallel arrangement, it is further provided that, in order to connect the second electric machine, a rotor of the second electric machine can be connected to the internal combustion engine via a wrap-around drive, via several meshing gears or the like.

[0014] For connecting the second electric machine to the transmission arrangement designed as a switchable transmission, the second electric machine in the proposed drive train can be connected, according to the invention, to a first transmission input shaft of the transmission arrangement, which is arranged coaxially to the second axis, via a shaft arranged coaxially to the first axis, without reversing the direction of rotation. This connection is independent of whether the second electric machine is arranged with its rotor axis coaxially to the first axis or to the fourth axis. For example, the connection without reversing the direction of rotation can be realized by means of a drive gear or the like. For this purpose, a toothed section fixed on the shaft arranged coaxially to the first axis can engage with a toothed section on the first transmission input shaft.Specifically, the gearing can be achieved, for example, by external teeth on a pinion of the shaft arranged coaxially to the first axis and by internal teeth on a ring gear or similar component of the first transmission input shaft, which mesh with each other. Other connections are also conceivable that can be implemented structurally simply without reversing the direction of rotation.

[0015] Regarding the gearbox configuration, various types of gearboxes can be used. For example, a planetary gearbox, a countershaft gearbox, or a combination thereof can be employed. In this context, various output configurations can also be implemented.

[0016] For example, the output shaft can be arranged coaxially to the first axis, i.e., coaxially to the crankshaft axis of the internal combustion engine, or offset from the first axis. Regarding the arrangement of the planetary gear set or the layshaft drive, the proposed drivetrain allows for either a coaxial or an offset orientation with respect to the output shaft.

[0017] In the proposed powertrain, the first, larger electric machine, or one with a larger outer diameter, is preferably used as the drive unit, as it can deliver higher power. The second electric machine in the proposed powertrain is smaller than the first and is therefore preferably used as a starter-generator, i.e., for starting the combustion engine, and / or as a generator. However, it is possible that in certain driving situations the second electric machine could be used to increase power output while driving.

[0018] In order to implement a purely electric drive system in the proposed powertrain, in which at least the first electric machine but also the second electric machine can be used, it is planned that the combustion engine can be decoupled from the powertrain via a switching element, for example a clutch.

[0019] The proposed powertrain can optionally include an all-wheel drive transfer case downstream of the output to implement all-wheel drive in the vehicle.

[0020] Another aspect of the present invention claims a vehicle with the aforementioned drivetrain oriented in the longitudinal direction of the vehicle, resulting in the advantages already described and further advantages. In the proposed vehicle, a longitudinally mounted combustion engine at the front is therefore implemented.

[0021] The present invention will now be explained in more detail with reference to the drawings. The drawings show: Fig. 1 a schematic view of a first embodiment of a drive train according to the invention with offset electric machines and with coaxially arranged drive and output; Fig. 2 a schematic view of a second embodiment of the drive train according to the invention with offset electric machines and with drive and output arranged offset from each other; Fig. 3 a schematic view of a third embodiment of the drive train according to the invention with an alternatively axis-offset arrangement of the electric machines in relation to Fig. 2; Fig. 4 a schematic view of a fourth embodiment of the drive train according to the invention with a planetary gear as a gear arrangement with an arrangement offset from the drive axis; and Fig. 5 a schematic view of a fifth embodiment of the drive train according to the invention with a planetary gear as a gear arrangement with a coaxial arrangement for the drive and output.

[0022] In the Fig. Figures 1 to 5 are examples of different embodiments of a drive train according to the invention in a vehicle. The different embodiments differ in the arrangement of individual transmission components. It is possible to transfer arrangements from one embodiment to another, so that the different embodiments can be combined.

[0023] Regarding the described connections between gearbox components, the term "connectable" is used, which implies both a detachable and a fixed connection. Furthermore, the chosen wording also implies a direct or indirect connection via other components.

[0024] Regardless of the various embodiments, the proposed powertrain features an internal combustion engine VM arranged coaxially to a first axis A1, which corresponds to the crankshaft axis of the internal combustion engine VM in the figures. Furthermore, a first electric machine EM1 and a second electric machine EM2 are provided, with the first electric machine EM1 being larger in dimensions than the second electric machine EM2. This means that the first electric machine EM1 has a higher power output and, consequently, a larger outer diameter than the second electric machine EM2. Therefore, the first electric machine EM1 is preferably or exclusively used for propulsion, and the second electric machine EM2 is preferably or exclusively used for starting the internal combustion engine VM and as a generator.Thus, the second electric machine EM2 can be connected at least to the combustion engine VM, and the first electric machine EM1 can be connected at least to the transmission arrangement G. Transmission arrangement G is, for example, a switchable multi-stage transmission that can be connected to an output Ab.

[0025] To achieve the most space-efficient arrangement of the electric machines EM1 and EM2, the first electric machine EM1 and the second electric machine EM2 are arranged offset from each other with respect to their rotor axes. This axial offset, or the axially parallel arrangement of the two electric machines EM1 and EM2, results in more radial space being available in the vehicle tunnel for the larger first electric machine EM1.

[0026] In all versions, except for the third version according to Fig. 3, the second electric machine EM2 is arranged coaxially to the first axis A1, while the first electric machine EM1 is arranged coaxially to a second axis A2, wherein the first axis A1 and the second axis A2 are offset from each other.

[0027] In contrast, the third version according to Fig. 3. It is provided that the second electric machine EM2 is arranged coaxially to a fourth axis A4, wherein the fourth axis A4 is arranged offset from the first axis A1 and the second axis A2. In order to create a drive connection between the rotor of the second electric machine EM2 and a shaft W arranged coaxially to the first axis A1 in the third embodiment, it is provided in Fig. 3. A wrap-around drive, for example, is represented as a chain drive. In this way, the rotor of the second electric machine EM2 can be connected to the internal combustion engine VM via the shaft W and a coupling K0, if provided.

[0028] In all embodiments, it is provided that the second electric machine EM2 can be connected via the shaft W, which is arranged coaxially to the first axis A1, to a first gearbox input shaft W1 of the gearbox assembly G, which is arranged coaxially to the second axis A2, without reversing the direction of rotation. For this purpose, the following is specified in the Fig. Figures 1 to 5 provide that the axis offset between the two electric machines EM1 and EM2 is achieved via a transmission unit that does not result in a reversal of rotational speed or direction of rotation between the first axis A1 and the second axis A2. As shown in the figures, this is exemplified by a connection between an external tooth on a pinion of the shaft W arranged coaxially to the first axis A1 and an internal tooth on a ring gear on the first transmission input shaft W1.

[0029] In the embodiments according to the invention, the rotor of the first electric machine EM1 can be connected to a second gearbox input shaft W2 of the gearbox arrangement G, which is arranged coaxially to the second axis A2.

[0030] As in the Fig. As illustrated in Figures 1 to 3, the transmission arrangement G can have at least one intermediate shaft VW arranged coaxially to a third axis A3, wherein the third axis A3 is arranged offset from the first axis A1, the second axis A2 and, if applicable according to the third embodiment variant, from the fourth axis A4.

[0031] In the first version variant according to Fig. In addition, the output Ab is arranged coaxially to the first axis A1, so that the drive and output are arranged coaxially to each other, whereas in the second and third embodiments according to Fig. 2 and Fig. 3 the output Ab is arranged coaxially to the third axis A3 of the gear arrangement G.

[0032] In the fourth and fifth versions according to Fig. 4 and Fig. 5. A planetary gear set is provided as the gear arrangement. In the fourth embodiment according to Fig. 4. The planetary gear set and the output Ab are arranged coaxially to the second axis A2, with the second axis A2 being offset from the first axis A1. In the fifth embodiment according to Fig. 5 is provided that the planetary gear and the output Ab are arranged coaxially to the first axis A1, wherein the planetary gear can be connected via at least one spur gear stage ST to the first and second gear input shafts W1, W2 which are arranged coaxially to the second axis A2.

[0033] In all embodiments, the figures illustrate by way of example that the second electric machine EM2 is arranged axially upstream of the first electric machine EM1, and that the first electric machine EM1 is arranged axially upstream of the transmission assembly G. Thus, starting from the internal combustion engine VM in the axial direction, the second electric machine EM2 is arranged first, followed by the first electric machine EM1, and then the transmission assembly G with the output Ab. Furthermore, a torsional vibration damper T is connected downstream of the internal combustion engine VM, which can be connected via a switching element K0 to the shaft W, which is coaxial with the first axis A1. Reference sign EM1 first larger-sized electric machine EM2 second smaller dimensioned electric machine VM internal combustion engine A1 first axle or crankshaft axle A2 second axis A3 third axis A4 fourth axis From drive G Multi-stage gear arrangement W wave coaxial to the first axis W1 first gearbox input shaft W2 second transmission input shaft VW countershaft K0 clutch T Torsional vibration damper ST Spur Gear Stage

Claims

[1] Drive train for a vehicle, with an internal combustion engine (VM) arranged coaxially to a first axle (A1), with at least a first electric machine (EM1) and a second electric machine (EM2), and with a transmission arrangement (G) which can be connected to an output (Ab), wherein the first electric machine (EM1) is dimensioned larger than the second electric machine (EM2) and wherein the second electric machine (EM2) is connectable at least to the internal combustion engine (VM) and the first electric machine (EM1) is connectable at least to the transmission arrangement (G), wherein the first electric machine (EM1) and the second electric machine (EM2) are arranged axially offset from one another with respect to their rotor axes, characterized bythat the second electrical machine (EM2) can be connected via a shaft (W) arranged coaxially to the first axis (A1) to a first transmission input shaft (W1) of the transmission arrangement (G) arranged coaxially to the second axis (A2) without reversing the direction of rotation and that a rotor of the first electrical machine (EM1) can be connected to a second transmission input shaft (W2) of the transmission arrangement (G) arranged coaxially to the second axis (A2). [2] Drive train according to claim 1, characterized by that the second electrical machine (EM2) is arranged coaxially to the first axis (A1) and that the first electrical machine (EM1) is arranged coaxially to a second axis (A2), wherein the first axis (A1) and the second axis (A2) are axially offset. [3] Drive train according to claim 1, characterized bythat the second electrical machine (EM2) is arranged coaxially to a fourth axis (A4), wherein the fourth axis (A4) is arranged axially offset to the first axis (A1) and to the second axis (A2). [4] Drive train according to claim 3, characterized by that a rotor of the second electric machine (EM2) can be connected to the internal combustion engine (VM) via a belt drive or via several meshing gears. [5] Drive train according to one of the preceding claims, characterized by that the transmission arrangement (G) has at least one countershaft (VW) arranged coaxially to a third axis (A3), wherein the third axis (A3) is arranged axially offset to the first axis (A1), to the second axis (A2) and optionally to the fourth axis (A4). [6] Drive train according to claim 5, characterized by that the output (Ab) is arranged coaxially to the first axis (A1). [7] Drive train according to claim 5, characterized bythat the output (Ab) is arranged coaxially to the third axis (A3) of the gear arrangement (G). [8] Drive train according to one of the preceding claims, characterized by that a planetary gear is provided as the gear arrangement. [9] Drive train according to claim 8, characterized by that the planetary gear and the output (Ab) are arranged coaxially to the second axis (A2), wherein the second axis (A2) is arranged axially offset from the first axis (A1). [10] Drive train according to claim 8, characterized by that the planetary gear and the output (Ab) are arranged coaxially to the first axis (A1), wherein the planetary gear is connectable via at least one spur gear stage (ST) to the first and second transmission input shafts (W1, W2) arranged coaxially to the second axis (A2). [11] Drive train according to one of the preceding claims, characterized bythat the second electrical machine (EM2) is arranged axially in front of the first electrical machine (EM1) and that the first electrical machine (EM1) is arranged axially in front of the transmission arrangement (G). [12] Drive train according to one of the preceding claims, characterized by that the first electric machine (EM1) is provided as a drive and the second electric machine (EM2) is provided for starting the internal combustion engine (VM) and / or as a generator. [13] Drive train according to one of the preceding claims, characterized by that a torsional vibration damper (T) is connected downstream of the combustion engine (VM). [14] Drive train according to one of the preceding claims, characterized by that the internal combustion engine (VM) can be decoupled from the shaft (W) arranged coaxially to the first axis (A1) via a switching element (K0). [15] Drive train according to one of the preceding claims, characterized bythat an all-wheel drive transfer case is connected downstream of the output (output). [16] Vehicle with a drive train aligned in the vehicle longitudinal direction according to one of the preceding claims.

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