Transmission for a motor vehicle, as well as drivetrain for a motor vehicle

Abstract

Transmission (G) for a motor vehicle, wherein the transmission (G) comprises a drive shaft (GW1), an output shaft (GW2), a plurality of planetary gear sets (P1, P2, P3), and an electric machine (EM) arranged axially parallel to the drive shaft (GW1), wherein the electric machine (EM) is operatively connected to the drive shaft (GW1) via a constant transmission ratio by means of a spur gear transmission (STG) or a traction gear transmission (ZMG), characterized in that the transmission (G) comprises a plurality of switching elements (A, B, C, D, E), wherein different gear stages can be switched between the input shaft (GW1) and the output shaft (GW2) by selectively closing the switching elements (A, B, C, D, E) by means of the planetary gear sets (P1, P2, P3), wherein Elements (E13, E23, E33) of one of the gear-forming planetary gear sets (P3) - are arranged at least sectionally radially within an element (STG1, ZMG1) of the spur gear unit (STG) or the traction gear unit (ZMG) arranged coaxially to the drive shaft (GW1), and - are arranged together with the spur gear unit (STG) or the traction gear unit (ZMG) in a plane (E1) oriented perpendicular to the axis of rotation of the drive shaft (GW1) and The gearbox (G) has an interface (GA) at one end to a gearbox-external drive unit, by means of which a rotary movement of the gearbox-external drive unit can be transmitted to the drive shaft (GW1), wherein the spur gear unit (STG) or the traction gear unit (ZMG) is arranged at the end of the gearbox (G) opposite the interface (GA) to the gearbox-external drive unit.

Description

[0001] The invention relates to a transmission for a motor vehicle, as well as a drivetrain for a motor vehicle with such a transmission. Here, a transmission refers in particular to a multi-speed transmission in which a multitude of gears, i.e., fixed gear ratios between the input shaft and the output shaft of the transmission, can be selected, preferably automatically, by means of switching elements. These switching elements include, for example, clutches or brakes. Such transmissions are primarily used in motor vehicles to adapt the speed and torque output characteristics of the drive unit to the vehicle's driving resistances in a suitable manner.

[0002] German patent application DE 11 2012 003 406 T5 describes a hybrid drive device in which an electric motor is arranged on a second axis parallel to a first axis. A transmission with an input shaft and a countershaft is arranged on the first axis. The countershaft is connected to the drive wheels of a motor vehicle via a differential. The electric motor is connected to the input shaft via a connecting mechanism designed as a spur gear. The gear-forming section of the transmission is shown only schematically.

[0003] Patent application DE 10 2009 018 958 A1 describes a multi-stage transmission with a housing, three planetary gear sets, and a first, second, and third shaft, wherein the third shaft is arranged offset from the first and second shafts. According to the Fig. In the embodiment shown in section 3, the multi-stage transmission includes an electric machine which is arranged coaxially to the third shaft. The electric machine is in constant operative connection with the second shaft via a chain or belt connection.

[0004] The patent application DE 10 2015 105 040 A1 describes an electromechanical drive system with a plurality of bearings, wherein at least two bearings are aligned with each other along an axis, wherein this axis is aligned perpendicular to a main shaft axis.

[0005] The patent application DE 10 2014 000 880 A1 describes a hybrid multi-stage transmission for a motor vehicle, which is designed to switch at least four internal combustion engine forward gears, at least one electric motor forward gear and at least two EVT driving ranges.

[0006] DE 10 2014 218 622 A1 describes a load-shiftable multi-stage gearbox in planetary design.

[0007] Both devices known in the prior art are intended for use in a motor vehicle powertrain that is oriented transversely to the direction of travel of the motor vehicle. Such devices are typically optimized for the shortest possible axial length, since the axial assembly of the drive motor and transmission is to be arranged between the longitudinal members of the motor vehicle's front end.

[0008] The object of the invention is to provide a transmission for a motor vehicle which is characterized by a particularly short axial length.

[0009] The problem is solved by the features of claim 1. Advantageous embodiments result from the dependent claims, the description and the figures.

[0010] The transmission comprises an input shaft, an output shaft, multiple planetary gear sets, multiple switching elements, and an electric motor arranged parallel to the input shaft. Various gear ratios can be selected between the input and output shafts by selectively closing the switching elements via the planetary gear sets. The electric motor is in constant operative connection with the input shaft via a spur gear or a traction drive, with the gear ratio between the input shaft and the electric motor remaining constant.

[0011] The spur gear drive can have one or more intermediate gears whose axes of rotation are parallel to the axis of rotation of the electric motor rotor and parallel to the axis of rotation of the drive shaft. Examples of traction drives include chains, V-belts, and toothed belts.

[0012] According to the invention, elements of one of the gear-forming planetary gear sets are arranged at least partially radially within an element of the spur gear transmission or the traction element transmission arranged coaxially to the drive shaft. These elements are arranged together with the spur gear transmission or the traction element transmission in a plane perpendicular to the axis of rotation of the drive shaft.

[0013] In other words, one of the gear-forming planetary gear sets is nested, at least partially, radially within that element of the spur gear drive or the traction drive that is coaxial with the drive shaft. Elements of the spur gear drive or the traction drive and elements of this planetary gear set are arranged in a common plane, which is oriented perpendicular to the drive shaft.

[0014] The arrangement according to the invention allows the axial length of the gearbox to be reduced, since the spur gear drive, or the traction gear drive and the planetary gear sets are no longer arranged axially one behind the other.

[0015] According to the invention, the transmission has an interface to an external drive unit, for example, an internal combustion engine. The interface is designed to transmit rotary motion from the external drive unit to the transmission's drive shaft and can be configured, for example, as a flange or a splined connection. The interface can be located on the drive shaft or on a connecting shaft that can be joined to the drive shaft. The interface can also be located, for example, on a hydrodynamic torque converter connected to the drive shaft, which serves as a starting element. The spur gear unit, or the traction element unit, is arranged at the axial end of the transmission opposite the interface to the external drive unit.

[0016] According to a preferred embodiment, the spur gear drive or the traction drive is in direct operative connection with the ring gear of the planetary gear set, which is arranged radially within the element of the spur gear drive or the traction drive that is arranged coaxially to the drive shaft. A corresponding spur gear toothing or sprocket toothing can be formed integrally on the outer diameter of this ring gear. This eliminates the need for separate components and the corresponding connecting elements.

[0017] Preferably, the drive shaft is axially supported relative to a gearbox housing, with the aforementioned ring gear being permanently and rotationally fixed to the drive shaft. This simplifies the mounting of the element of the spur gear or traction element drive that is arranged coaxially to the drive shaft.

[0018] According to an alternative embodiment, the spur gear transmission or the traction drive is in direct operative connection with the planet carrier of the planetary gear set that is arranged radially within the element of the spur gear transmission or traction drive that is arranged coaxially to the drive shaft. The planet carrier, as the sum shaft of the planetary gear set, requires a rigid bearing in any case. The bearing of the planet carrier can therefore also serve as the bearing for the element of the spur gear transmission or traction drive that is arranged coaxially to the drive shaft.

[0019] Preferably, the remaining planetary gear sets, whose elements are not arranged radially within the spur gear or traction element drive, have a total of four shafts, one of which is part of the output shaft. The planetary gear set that is arranged radially within the spur gear or traction element drive is preferably part of a switchable power path between the input shaft and one of these four shafts. A switchable power path is defined as an active connection between the input shaft and one of the four shafts that can be established by closing one of the switching elements. This active connection can be established either directly or via an interposed planetary gear set within the power flow.

[0020] The transmission can be part of a motor vehicle's drivetrain. In addition to the transmission, the drivetrain also includes an internal combustion engine, which is torsionally connected to the transmission's input shaft via an internal or external torsional vibration damper, or can be connected via a disconnect clutch. The output shaft is operatively connected to an internal or external differential, with the differential's output shafts connected to the vehicle's drive wheels. The transmission, together with the electric motor, enables several drive modes for the vehicle. In electric mode, the vehicle is driven by the transmission's electric motor. In internal combustion mode, the vehicle is driven by the internal combustion engine.In hybrid operation, the motor vehicle is powered by both the internal combustion engine and the electric motor of the transmission.

[0021] Exemplary embodiments of the invention are described in detail below with reference to the accompanying figures. These show: Fig. 1 and Fig. 2 schematic views of gears according to the invention; Fig. 3 and Fig. 4 sectional views of areas of the gearboxes according to the invention; and Fig. 5 a powertrain for a motor vehicle.

[0022] Fig. Figure 1 shows a schematic view of a gearbox G according to a first embodiment. The gearbox G comprises a drive shaft GW1, an output shaft GW2, a first planetary gear set P1, a second planetary gear set P2, a third planetary gear set P3, five switching elements A, B, C, D, E, an electric machine EM, a torsional vibration damper TS, a connecting shaft AN and a disconnecting clutch K0.

[0023] The three planetary gear sets P1, P2, and P3 are arranged coaxially with the input shaft GW1. The planetary gear sets P1 and P2 together have four shafts, designated W1, W2, W3, and W4. The ring gear of the second planetary gear set, P2, is part of the third shaft, W3, and is permanently connected to the output shaft, GW2. The planet carriers of the planetary gear sets P1 and P2 are connected to each other and are part of the second shaft, W2. The sun gear of the first planetary gear set, P1, is part of the first shaft, W1. The ring gear of the first planetary gear set, P1, is permanently connected to the sun gear of the second planetary gear set, P2, and is part of the fourth shaft, W4. The first planetary gear set, P1, is arranged radially inside the second planetary gear set, P2.

[0024] By closing switching element A, the fourth shaft W4 can be connected to the planet carrier E23 of the third planetary gear set P3. By closing switching element B, the first shaft W1 can be connected to the planet carrier E23 of the third planetary gear set P3. By closing switching element C, the first shaft W1 can be locked against rotation relative to the housing GG of the gearbox G. By closing switching element D, the second shaft W2 can be locked against rotation in the same way. By closing switching element E, the drive shaft GW1 can be connected to the second shaft W2. The ring gear E33 of the third planetary gear set P3 is permanently connected to the drive shaft GW1. The sun gear E13 of the third planetary gear set P3 is permanently locked against rotation relative to the housing GG.

[0025] The gearbox G has an interface GA to an external drive unit, which can be, for example, an internal combustion engine. The interface GA is configured to transmit the rotational speed of the external drive unit to the drive shaft GW1. A torsional vibration damper TS and a disconnect coupling K0 are arranged between the interface GA and the drive shaft GW1. By closing the disconnect coupling K0, the drive shaft GW1 can be connected to a connecting shaft AN, on which the interface GA is located.

[0026] The output shaft GW2 has a spur gear section which serves to transmit power between the output shaft GW2 and a differential gear AG (not shown) arranged parallel to the output shaft GW2. The differential gear AG can be part of the gearbox G.

[0027] The electric machine EM has a stator that is fixed relative to the housing GG and a rotatable rotor, and is arranged parallel to the drive shaft GW1. The rotor is in constant operative connection to the drive shaft GW1 via a spur gear unit STG. In the illustrated embodiment, the spur gear unit STG has an intermediate gear which is rotatably mounted on the housing GG. This intermediate gear meshes with an element STG1 of the spur gear unit STG, which is arranged coaxially with the drive shaft GW1. The third planetary gear set P3 is arranged radially within the element STG1. Components of the spur gear unit STG, as well as the sun gear E13, the planet carrier E23, and the ring gear E33 of the third planetary gear set P3, are arranged in a plane E1, which is oriented perpendicular to the drive shaft axis. The element STG1 is directly connected to the ring gear E33.

[0028] Fig. Figure 2 shows a schematic view of a second embodiment of the gearbox G, which is essentially the same as the one described in Figure 2. Fig. This corresponds to the first embodiment shown in Figure 1. Instead of the spur gear STG, a traction gear ZMG is now used for power transmission between the electric machine EM and the drive shaft GW1. An element ZMG1 of the traction gear ZMG, arranged coaxially to the drive shaft GW1, is permanently connected to the planet carrier E23. Due to the permanently rotationally fixed position of the sun gear E13, a constant transmission ratio exists between the drive shaft GW1 and the rotor of the electric machine EM.

[0029] Fig. Figure 3 shows a partial sectional view of a gear G according to the one described in Fig. 1 first embodiment shown, while in Fig. 4 a partial sectional view of a gearbox G according to the one in Fig. The second embodiment is shown in 2.

[0030] Fig. Figure 4 schematically shows a drivetrain of a motor vehicle. An internal combustion engine (ICE) is connected to the drive shaft (AN) of the transmission (G) via the torsional vibration damper (TS). The in Fig. The gear G shown in section 4 corresponds to the one in Fig.Figure 1 shows the first embodiment of the invention. This is merely an example. The internal combustion engine (VKM) could also be directly connected to the drive shaft (GW1) of the transmission (G) via the torsional vibration damper (TS). The drivetrain could also include a hydrodynamic torque converter, which is to be arranged in the power flow between the internal combustion engine (VKM) and the drive shaft (GW1) of the transmission (G). Such a torque converter can also include a lock-up clutch. A person skilled in the art will freely configure the arrangement and spatial position of the individual components of the drivetrain according to the external boundary conditions. The output shaft (GW2) is operatively connected to a differential (AG), via which the power applied to the output shaft (GW2) is distributed to the drive wheels (DW) of the vehicle. Reference sign G gearbox GG housing GW1 drive shaft GW2 output shaft EM Electrical Machine P1 First planetary gear set P2 Second planetary gear set W1 First Wave W2 Second Wave W3 Third Wave W4 Fourth Wave P3 Third planetary gear set E13 Sun wheel E23 Planetary Carrier E33 ring gear A switching element B Switching element C switching element D Switching element E switching element STG spur gear STG1 element of the spur gear unit ZMG traction transmission ZMG1 element of the traction transmission E1 Level GA interface K0 disconnect coupling TS Torsional Vibration Damper ON connection shaft VKM internal combustion engine AG Differential Gearbox DW drive wheel

Claims

[1] Transmission (G) for a motor vehicle, wherein the transmission (G) comprises a drive shaft (GW1), an output shaft (GW2), a plurality of planetary gear sets (P1, P2, P3), and an electric machine (EM) arranged axially parallel to the drive shaft (GW1), wherein the electric machine (EM) is operatively connected to the drive shaft (GW1) via a constant transmission ratio by means of a spur gear transmission (STG) or a traction gear transmission (ZMG), characterized by , that the transmission (G) comprises a plurality of switching elements (A, B, C, D, E), wherein different gear stages can be switched between the input shaft (GW1) and the output shaft (GW2) by selectively closing the switching elements (A, B, C, D, E) by means of the planetary gear sets (P1, P2, P3), wherein Elements (E13, E23, E33) of one of the gear-forming planetary gear sets (P3) - are arranged at least sectionally radially within an element (STG1, ZMG1) of the spur gear unit (STG) or the traction gear unit (ZMG) arranged coaxially to the drive shaft (GW1), and - are arranged together with the spur gear unit (STG) or the traction gear unit (ZMG) in a plane (E1) oriented perpendicular to the axis of rotation of the drive shaft (GW1) and The gearbox (G) has an interface (GA) at one end to a gearbox-external drive unit, by means of which a rotary movement of the gearbox-external drive unit can be transmitted to the drive shaft (GW1), wherein the spur gear unit (STG) or the traction gear unit (ZMG) is arranged at the end of the gearbox (G) opposite the interface (GA) to the gearbox-external drive unit. [2] Gearbox (G) according to claim 1, characterized by, that the spur gear (STG) or the traction gear (ZMG) is in direct operative connection to the ring gear (E33) of that planetary gear set (P3) which is arranged radially within the element (STG1, ZMG1) of the spur gear (STG) or the traction gear (ZMG). [3] Gearbox (G) according to claim 2, characterized by , that the element (STG1, ZMG1) of the spur gear (STG) or the traction gear (ZMG) arranged coaxially to the drive shaft (GW1) is formed in one piece on the outer diameter of the ring gear (E33). [4] Gearbox (G) according to claim 3, characterized by , that the drive shaft (GW1) is axially supported relative to a housing (GG) of the gearbox (G), wherein the ring gear (E33) is permanently connected to the drive shaft (GW1) in a rotationally fixed manner. [5] Gearbox (G) according to claim 1, characterized by, that the spur gear unit (STG) or the traction gear unit (ZMG) is in direct operative connection to the planet carrier (E23) of that planet gear set (P3) which is arranged radially within the element (STG1, ZMG1) of the spur gear unit (STG) or the traction gear unit (ZMG). [6] Gearbox (G) according to any of the preceding claims, characterized by , that the remaining planetary gear sets (P1, P2) have a total of four shafts (W1, W2, W3, W4), one of these four shafts (W3) being part of the output shaft (GW2). [7] Gearbox (G) according to claim 6, characterized by , that the planetary gear set (P3) which is arranged radially within the element (STG1, ZMG1) of the spur gear unit (STG) or the traction gear unit (ZMG) is part of a switchable power path between the drive shaft (GW1) and one of the four shafts of the other planetary gear sets (P1, P2). [8] Powertrain for a motor vehicle, characterized bya transmission (G) according to any one of claims 1 to 7.

Images