Transmission for a motor vehicle

Abstract

Transmission (G) for a motor vehicle, which is configured to provide different transmission ratios between a drive shaft (G1) and an output shaft (G2) of the transmission (G) by means of a transmission changing device (GA), wherein the transmission (G) has a housing (GG), a hub (N) connected to a torsional vibration damper (TS), and a disconnecting clutch (K) with a first clutch half (KA) and a second clutch half (KG), wherein the hub (N) is connected to the first clutch half (KA), wherein the drive shaft (G1) is rotationally fixed to the second clutch half (KG) and projects axially into the transmission changing device (GA), characterized in that the drive shaft (G1) - is supported at a first axial end (G1Ab) via a first bearing (L1) in a radial direction directly or indirectly on the housing (GG), and - is supported at a second axial end (G1An) via a second bearing (L2) in a radial direction directly on the hub (N), wherein the hub (N) is supported in a radial direction via a third bearing (L3) directly on a bearing shield (LS) connected to the housing (GG) in a rotationally fixed manner.

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] Patent application DE 10 2008 040 498 A1 of the applicant describes a hybrid powertrain of a motor vehicle, wherein a hybrid module is connected upstream of an automatic transmission. The hybrid module comprises a torsional vibration damper, an electric motor, an input transmission stage, and a disconnect clutch. The rotor of the electric motor is rotatably mounted via a double-shear bearing relative to the module housing, on an output shaft of the hybrid module, or on a planetary carrier of the input transmission stage.

[0003] Such a mounting of the electric motor in the hybrid module can lead to different axes of rotation for the electric motor and the downstream transmission. Depending on the coupling between the hybrid module and the downstream transmission, this can result in over-constrained mounting. This can reduce the service life of the components involved.

[0004] Patent application DE 10 2014 202 621 A1 proposes a hybrid module as a solution to this problem, in which the rotor is supported radially against a housing on one side and against a transmission shaft on the other. The transmission shaft is supported axially in the housing and radially via two bearing points on a non-rotating support shaft. However, the input shaft of the hybrid module, which is equipped with a torsional vibration damper, is independently supported via two rolling bearings, so that an axial misalignment between the input shaft and the transmission shaft can occur. This can negatively affect the service life of the multi-plate clutch located between the input and output shafts.

[0005] It is therefore an object of the invention to provide a gearbox which is characterized by improved bearing compared to the prior art.

[0006] The problem is solved by the features of claim 1. Advantageous embodiments are shown in the dependent claims, the description and the figures.

[0007] To solve the problem, a transmission for a motor vehicle is proposed, which is designed to provide different gear ratios between an input shaft and an output shaft of the transmission by means of a gear-changing device. The transmission also includes a housing, a hub connected to a torsional vibration damper, and a disengaging clutch with a first and second clutch half. The hub is connected to the first clutch half. The second clutch half is connected to the input shaft. The input shaft projects axially into the gear-changing device. The gear-changing device can, for example, be formed by gear-forming planetary gear sets and the switching elements interacting with them.

[0008] According to the invention, the drive shaft is supported at a first axial end by a first bearing in the radial direction directly or indirectly on the housing. At a second axial end, the drive shaft is supported in the radial direction directly on the hub by a second bearing. The hub is supported in the radial direction by a third bearing directly on a bearing plate that is rotationally fixed to the housing. This prevents any axial misalignment between the hub and the drive shaft.

[0009] In direct support, there is no component other than the bearing between the respective elements. Indirect support is achieved through the interposition of one or more additional elements. For example, the drive shaft can be supported directly at its first axial end by the housing, or indirectly by the interposition of, for example, the output shaft and another bearing.

[0010] According to a preferred embodiment, the first coupling half is rotationally fixed or connected to the hub via the second torsional vibration damper.

[0011] Preferably, the second coupling half, or a component rigidly connected to it, is rigidly connected to the drive shaft via a splined connection. Since the splined connection allows axial displacement in the unloaded state, this design can compensate for the axial positional tolerance between the drive shaft and the second coupling half.

[0012] The hub is preferably directly supported by a radial bearing on the second coupling half or on the component rigidly connected to it. This supports the hub against tilting on the drive shaft.

[0013] In the axial direction, the second coupling half, or the component rigidly connected to it, is preferably mounted between the hub and the housing. The connection to the housing is preferably indirect, i.e., via the interposition of further transmission components.

[0014] According to a preferred embodiment, the transmission comprises an electric machine with a rotationally fixed stator and a rotatable rotor. The rotor is either permanently and rotationally fixed to the drive shaft or operatively connected via a fixed transmission ratio. The rotor is supported radially on the drive shaft by an element that is rotationally fixed to the rotor, preferably exclusively.

[0015] If the rotor is permanently and rotationally fixed to the drive shaft, the element rigidly connected to the rotor is preferably supported radially on the drive shaft by means of a splined connection and a centering seat. Preferably, this is the same splined connection with which the second coupling half is connected to the drive shaft. In other words, the rotor is rotationally fixed to the second coupling half. If the rotor is operatively connected to the drive shaft via a fixed transmission ratio, the element rigidly connected to the rotor is preferably supported radially on the drive shaft by means of two bearings.

[0016] If the rotor is operatively connected to the drive shaft via a fixed transmission ratio, the second coupling half is preferably supported on the element which is non-rotatably connected to the rotor via an additional radial bearing.

[0017] If the rotor is operatively connected to the drive shaft via a fixed gear ratio, the rotor is preferably mounted axially between the second coupling half or the component rigidly connected to it and the housing. The connection to the housing is preferably indirect, i.e., via the interposition of further transmission components.

[0018] Preferably, the fixed gear ratio between the rotor and the drive shaft is provided by means of a planetary gear set, the planet carrier of which is supported on the drive shaft via a splined connection. This support ensures that the planet carrier is both rotationally fixed to the drive shaft and radially supported.

[0019] The drive shaft can optionally be supported against the housing by a support bearing. This support bearing is arranged axially between the first and second bearings. Such a support bearing can limit deflection, especially in the case of a long drive shaft. The support from the support bearing to the housing is preferably achieved via a second bearing shield, which is connected to the housing.

[0020] According to a preferred embodiment, the first bearing and / or the second bearing is designed as a plain bearing. The first and / or the second plain bearing is preferably lubricated hydrostatically by the lubrication pressure applied in the gearbox. Alternatively, the first and / or the second bearing can be designed as a needle roller bearing with an integrated seal.

[0021] Preferably, the bearing shield is connected to the housing by means of three screws. This significantly reduces axial and radial compliance of the bearing shield.

[0022] The transmission can be a component 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 hub via at least one torsional vibration damper. The transmission's output shaft is driven by a differential, either internal or external, which in turn is driven by the vehicle's wheels. If the transmission incorporates an electric motor, the drivetrain enables multiple drive modes for the vehicle. In electric mode, the vehicle is propelled by the transmission's electric motor. In combustion engine mode, the vehicle is propelled by the internal combustion engine. In hybrid mode, the vehicle is propelled by both the internal combustion engine and the transmission's electric motor.

[0023] Exemplary embodiments of the invention are described in detail below with reference to the accompanying figures. These show: Fig. 1 to Fig. 3. Each schematic representation of a first to third embodiment of the gearbox; as well as Fig. 4 and Fig. 5 each a schematic representation of a motor vehicle powertrain.

[0024] Fig. Figure 1 shows a schematic representation of a first embodiment of the gearbox G. The gearbox G has a drive shaft G1, an output shaft G2 and a gear ratio changing device GA, which are arranged in Fig. 1 is only indicated. The transmission changing device GA is designed to provide different transmission ratios between the drive shaft G1 and the output shaft G2, for example by means of planetary gear sets and switching elements interacting with them.

[0025] The gearbox G further comprises a housing GG, a hub N, a disconnect clutch K with a first clutch half KA and a second clutch half KG, and an electric machine EM with a stator S that is rotationally fixed relative to the housing GG and a rotatable rotor R. The disconnect clutch K is exemplified as a wet multi-plate clutch, which is engaged by means of a suitable, in Fig. The coupling can be actuated by an actuating device (not shown), for example, by means of a hydraulically actuated piston. The hub N is connected to a torsional vibration damper TS and, via an optional second torsional vibration damper TS2, to the first coupling half KA. A torsional vibration damper DAT is also attached to the hub N. The coupling K, the torsional vibration damper DAT, and the second torsional vibration damper TS2 are located in the wet chamber of the gearbox G, while the torsional vibration damper TS is located in a dry chamber. The wet chamber and dry chamber are separated by a bearing shield LS, which is connected to the housing GG by three screws (not shown). The second coupling half KG is permanently and rotationally fixed to the drive shaft G1 via the rotor R, a rotor carrier RT, and a rotor hub RN.

[0026] The drive shaft G1 is indirectly supported at a first axial end G1Ab by a first bearing L1 on the housing GG in the radial direction. This indirect support is exemplified by the output shaft G2, which is itself rotatably mounted on the housing GG via a bearing Lx. The first axial end G1ab of the drive shaft G1 projects axially into the transmission change device GA. Alternatively, the drive shaft G1 could be directly supported at its axial end G1Ab by the first bearing L1 on the housing GG in the radial direction.

[0027] The drive shaft G1 is supported radially at its second axial end G1An by a second bearing L2 directly against the hub N. The hub N is supported radially by a third bearing L3 directly against the bearing shield LS.

[0028] Optionally, an additional support bearing L8 can be provided, which supports the drive shaft G1 against a second bearing plate LS2. The second bearing plate LS2 is connected to the housing GG. Such a support bearing L8 can limit deflection of the drive shaft G1, especially in the case of a long one.

[0029] The rotor R and the second coupling half KG are non-rotatably connected, so that the second coupling half KG is supported by the rotor R, the non-rotatably connected rotor carrier RT, and the non-rotatably connected rotor hub RN. The non-rotatable connection between the rotor hub RN and the drive shaft G1 is achieved via a splined connection S1, which also serves as a bearing for the rotor R. The assembly of rotor R, rotor carrier RT, and rotor hub RN is additionally supported on the drive shaft G1 via a centering seat Z1. The hub N is also supported directly on the second coupling half KG via a radial bearing L4. In the axial direction, the assembly of rotor R, rotor carrier RT, and rotor hub RN is supported axially between the hub N and the second bearing shield LS2. This axial support is provided by axial bearings A2 and A3.The hub N is axially supported between the bearing shield LS and the rotor hub RN, with the support provided by the axial bearing A2 and an axial bearing A1.

[0030] The electric machine EM in the first embodiment is merely an optional component of the gearbox G. In this case, the second coupling half KG is connected to the drive shaft G1 via a coupling carrier instead of via the rotor carrier RT, for example.

[0031] Fig. Figure 2 shows a schematic representation 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. The rotor R is now connected to the drive shaft G1 via a fixed gear ratio, which is provided by a planetary gear set P. For this purpose, a sun gear of the planetary gear set P is fixed against rotation relative to the second bearing shield L2, a ring gear is connected to the rotor R via the rotor carrier RT, and a planet carrier PS is connected to the drive shaft G1 via a splined connection S2. The second coupling half KG is no longer connected to the rotor R. Instead, the second coupling half KG is connected against rotation to a coupling carrier KGT, which in turn is connected against rotation to a coupling hub KGN. The coupling carrier KGT and coupling hub KGN can be manufactured as a single piece or, for example, welded together. The second coupling half KG can be manufactured as a single piece with the coupling carrier KGT.

[0032] The coupling hub KGN is connected to the drive shaft G1 via the first splined connection S1 and supported on the rotor hub RN by an additional radial bearing L7. The rotor hub RN is radially supported on the drive shaft G1 by two bearings L5 and L6. The coupling hub KGN is axially supported between the hub N and the rotor carrier RT, with support provided by thrust bearing A2 and thrust bearing A4. The rotor carrier RT is axially supported between the coupling hub KGN and the planet carrier PS, with support provided by thrust bearing A4 and thrust bearing A5. The planet carrier PS is axially supported between the rotor carrier RT and the second bearing shield LS2, with support provided by thrust bearing A5 and thrust bearing A6. The sun gear of the planetary gear set P may be located within the force transmission path of this axial support.

[0033] Fig. Figure 3 shows a schematic representation of a second embodiment of the gearbox G, which is essentially the same as the one described in Figure 3. Fig. This corresponds to the first embodiment shown in Figure 2. The first coupling half KA is now directly connected to the hub N, thus eliminating the need for the second torsional vibration damper TS2.

[0034] In all exemplary embodiments, the bearing arrangement of the gearbox G is not fully shown. In particular, additional bearings are required in the area of ​​the gear ratio changer GA. The radial bearing arrangement of the drive shaft G1 is fully shown.

[0035] Fig. Figure 4 shows an example of a motor vehicle drivetrain with an internal combustion engine VM and a downstream transmission G. The drivetrain is aligned parallel to the direction of travel of the motor vehicle. The internal combustion engine VM is connected to the hub N of the transmission G via the torsional vibration damper TS. The output shaft G2 of the transmission G is connected to an external differential AG, which distributes the power applied to the output shaft G2 to the drive wheels DW.

[0036] Fig.Figure 5 shows an example of a motor vehicle's drivetrain, which is oriented transversely to the vehicle's direction of travel. The internal combustion engine VM is connected to the hub N of the transmission G via the torsional vibration damper TS. The output shaft G2 of the transmission G is operatively connected to an internal differential gear AG, which is arranged parallel to the output shaft G2. The differential gear AG distributes the power applied to the output shaft G2 to the drive wheels DW. Reference sign G gearbox G1 drive shaft G1Ab First axial end of the drive shaft G1An Second axial end of the drive shaft G2 output shaft GA translation change device GG housing LS storage shield LS2 Second Storage Shield N hub TS Torsional Vibration Damper TS2 Second Torsional Vibration Damper DAT torsional vibration damper K disconnect coupling KA First clutch half KG Second coupling half KGT coupling carrier KGN coupling hub EM Electrical Machine R Rotor RT rotor carrier RN rotor hub S Stator L1 First Camp Lx bearing L2 Second Camp L3 Third Camp L4 radial bearing L5 bearing L6 bearing L7 Additional radial bearing L8 support bearing S1 splined connection S2 Second splined connection Z1 Centering Seat A1 axial bearing A2 axial bearing A3 axial bearing A4 axial bearing A5 axial bearing A6 axial bearing P Planetary gear set PS Planetary carrier VM internal combustion engine AG Differential Gearbox DW drive wheel

Claims

[1] Transmission (G) for a motor vehicle, which is equipped to provide different transmission ratios between a drive shaft (G1) and an output shaft (G2) of the transmission (G) by means of a transmission changing device (GA), wherein the transmission (G) has a housing (GG), a hub (N) connected to a torsional vibration damper (TS) and a disconnecting clutch (K) with a first clutch half (KA) and a second clutch half (KG), wherein the hub (N) is connected to the first clutch half (KA), wherein the drive shaft (G1) is rotationally fixed to the second clutch half (KG) and projects axially into the transmission changing device (GA), characterized by , that the drive shaft (G1) - is supported at a first axial end (G1Ab) via a first bearing (L1) in a radial direction directly or indirectly on the housing (GG), and - is supported at a second axial end (G1An) via a second bearing (L2) in a radial direction directly on the hub (N), wherein the hub (N) is supported in a radial direction via a third bearing (L3) directly on a bearing shield (LS) connected to the housing (GG) in a rotationally fixed manner. [2] Gearbox (G) according to claim 1, characterized by that the first coupling half (KA) is rotationally fixed or connected to the hub (N) via a second torsional vibration damper (TS2). [3] Gearbox (G) according to claim 1 or claim 2, characterized by , that the second coupling half (KG) or a component connected to it in a rotationally fixed manner is connected to the drive shaft (G1) via a splined connection (S1) in a rotationally fixed manner. [4] Gearbox (G) according to claim 3, characterized by , that the hub (N) is supported via a radial bearing (L4) on the second coupling half (KG) or on the component connected to it in a rotationally fixed manner. [5] Gearbox (G) according to claim 3 or claim 4, characterized by , that the second coupling half (KG) or the component connected to it in a rotationally fixed manner is mounted in the axial direction between the hub (N) and the housing (GG). [6] Gearbox (G) according to any of the preceding claims, characterized by , that the gearbox (G) comprises an electric machine (EM) with a rotatable rotor (R) and a rotationally fixed stator (S), wherein the rotor (R) is either permanently connected to the drive shaft (G1) in a rotationally fixed manner or operatively connected via a fixed transmission ratio, and wherein the rotor (R) is supported in a radial direction on the drive shaft (G1) via an element (RN) which is rotationally fixed to the rotor (R). [7] Gearbox (G) according to claim 6, characterized by , that the rotor (R) is supported in the radial direction exclusively on the drive shaft (G1). [8] Gearbox (G) according to claim 6 or claim 7, characterized by, that the rotor (R) is permanently connected to the drive shaft (G1) in a rotationally fixed manner, wherein the element (RN) connected to the rotor (R) in a rotationally fixed manner is supported in the radial direction on the drive shaft (G1) via a splined connection (S1) and via a centering seat (Z1). [9] Gearbox (G) according to claim 6 or claim 7, characterized by , that the rotor (R) is operatively connected to the drive shaft (G1) via a fixed transmission ratio, wherein the element (RN) which is rotationally fixed to the rotor (R) is supported in the radial direction on the drive shaft (G1) via two bearings (L5, L6). [10] Gearbox (G) according to claim 9, characterized by , that the second coupling half (KG) is supported on the element (RN) which is non-rotatably connected to the rotor (R) via an additional radial bearing (L7). [11] Gearbox (G) according to claim 9 or claim 10, characterized by, that the rotor (R) is mounted in the axial direction between the second coupling half (KG) or the component connected to it in a rotationally fixed manner and the housing (GG). [12] Gearbox (G) according to any one of claims 9 to 11, characterized by , that the fixed transmission ratio between rotor (R) and drive shaft (G1) is provided by a planetary gear set (P), whose planet carrier (PS) is supported on the drive shaft (G1) via a splined connection (S2). [13] Gearbox (G) according to any of the preceding claims, characterized by , that the drive shaft (G1) is supported relative to the housing (GG) via a support bearing (L8), wherein the support bearing (L8) is arranged axially between the first and second bearings (L1, L2). [14] Gearbox (G) according to any of the preceding claims, characterized by that the first bearing (L1) and / or the second bearing (L2) is designed as a plain bearing or as a needle sleeve with an integrated seal. [15] Gearbox (G) according to any of the preceding claims, characterized by , that the bearing shield (LS) is connected to the housing (GG) by means of three screws. [16] Powertrain for a motor vehicle, characterized by a transmission (G) according to any one of claims 1 to 15.

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