Automotive powertrain

Abstract

Motor vehicle drive train comprising a planetary gear (1) for transmitting a torque generated by a drive unit (2) to an output-side torque distribution device (3) and a spur gear group (13) provided for the operative connection of the drive unit (2) to the planetary gear (1), wherein the spur gear group (13) has at least two toothing stages (14, 15) with different gear ratios, the planetary gear has a planetary gear set (4) with at least one planetary gear, comprising a first planetary stage (5) and a second planetary stage (6), which are connected to one another in a rotationally fixed manner, wherein the second planetary stage (6) is in meshing engagement with a fixed ring gear (7) and the first planetary stage (5) is in meshing engagement with a first sun gear (8), wherein the first sun gear (8) is connected to a first sun shaft (11), and the planetary gear set (4) is rotatably mounted on a planet carrier (10) which is connected to an output shaft which is connected to the torque distribution device (3) and at least one stage of the spur gear group (13) can be brought into operative connection with the first sun shaft (11) via a coupling element, wherein the first toothing stage (14) of the spur gear group (13) is connected via a first coupling element (17) and the second toothing stage (15) of the spur gear group (13) can be brought into operative connection with the first sun shaft (11) via a second coupling element (18).

Description

The present invention relates to a motor vehicle drive train having a planetary gear set with a planetary gear set with double-stepped planetary gears for transmitting a torque, which is generated by a drive unit, for example an electric motor or an internal combustion engine, to a torque distribution device on the output side.For example, DE 10 2016 202 723 B4 discloses a planetary gear transmission which has a power input, a power output, a pre-stage transmission which is driven by the power input, with a fixed occupancy ratio with a pre-stage sun gear, a pre-stage planetary set, a pre-stage planetary carrier and a pre-stage ring gear, and a stepped load transmission which is driven by the pre-stage transmission, with a first stepped load sun gear, a second stepped load sun gear, a stepped load planetary gear, a first stepped load planetary carrier and a first stepped load ring gear, and a dual clutch device, with a first clutch and a second clutch which is arranged in an intermediate region situated spatially axially between the pre-stage transmission and the stepped load transmission. In this case, the power take-off from the stepped load transmission takes place via the stepped load planet carrier and the planets of the first stepped load planet set engage radially from the inside into the stepped load ring gear. The characteristic of this planetary gear transmission is that the first clutch serves for the selective coupling of the first load stage sun gear to the pre-stage planet carrier, the second clutch serves for the selective coupling of the second load stage sun gear to the pre-stage planet carrier, the first load stage planet set and the second load stage planet set together form a stepped planet set with stepped planets and the first load stage ring gear is fixed stationary on a transmission housing of the planetary gear transmission.DE 10 2016 200 644 A1 shows a multi-stage transmission for a motor vehicle having a transmission housing of a transmission input shaft and a transmission output shaft and having an input subtransmission and an output subtransmission arranged axially parallel to the latter, which is designed in planetary transmission design, wherein drive power can be transmitted from the input subtransmission to the output subtransmission by a first and a second spur gear stage, and wherein the transmission output shaft can be coupled to an output planetary gear carrier, and wherein the input subtransmission is designed as a four-shaft transmission and has the following transmission elements, an input sun gear, two input planetary gears and an input ring gear, and, in addition to these transmission elements, the input subtransmission has two further transmission elements from a group of transmission elements, which comprises the following elements, a further input sun gear, a further input annulus gear and an input planetary gear carrier, wherein said input planetary gear carrier is configured for transmitting torque, wherein said first and said second input planetary gear are connected to one another in a rotationally fixed manner.Proceeding from the currently known prior art, it is an object of the invention to propose a motor vehicle drive train, the gear jumps of the previous planetary transmissions and the gearbox spread thereof being optimized. It is also an object of the invention to design the transmission architecture such that a dual clutch or triple clutch can be integrated into a drive train with planetary gearing without great effort.Therefore, this invention provides a motor vehicle drive train with a planetary gear set, which is provided to transmit a torque, which is generated by a drive unit, for example, by an electric motor or by an internal combustion engine, to a torque distribution device on the output side, for example, a differential gear set. The planetary gear set has a planetary gear set with at least one double-stepped planetary gear, wherein one of the stages / planetary stages meshes with a fixed ring gear and the further planetary stage meshes with a sun gear. The drive unit is connected via a shaft, i.e. for example in the case of an electric motor via a rotor shaft, to a spur gear group which has at least two toothed stages with different transmission ratios. In this context, a spur gear group is understood to be any configuration which leads to an external toothing on the shaft or rotor shaft, which has two toothing stages of different transmission ratio. The external toothing can thus be directly structurally integrated in the shaft or be applied as a separate gearwheel on the shaft.The planets of the planetary gear set are rotatably mounted on a planet carrier which is designed to transmit the torque to the torque distribution device. At least one of the toothed stages of the spur gear group can be operatively connected to a first sun shaft via a coupling element.The advantageous effect of such an arrangement lies in the optimization of the power density of the drive train and in the optimization of the gear jumps and the transmission spread.Advantageous embodiments of the invention form part of the dependent claims and are explained in more detail below.A further preferred embodiment provides that a second toothed stage of the spur gear group can be brought into operative connection with the first sun shaft via a second coupling element.More preferably, a sun gear connected to the second sun shaft is in meshing operative connection with the second toothed stage of the planetary gear set.In a further preferred embodiment, the spur gear group has a third toothed stage which can likewise be brought into operative connection with the first sun shaft via a third clutch element.In a further embodiment, the spur gear group likewise has three toothing stages. In this case, a first toothed stage can be brought into operative connection with the first sun shaft via a first clutch element, and a second toothed stage can be brought into operative connection with a second sun shaft via a second clutch element and a third toothed stage can be brought into operative connection with a second sun shaft via a third clutch element. The second sun shaft is in turn connected to a second sun gear, which is operatively connected in meshing fashion to the second stage of the planetary gear set.In a further embodiment, the spur gear group likewise has three toothing stages. In this case, the first toothed stage can be brought into operative connection via a first clutch element and the second toothed stage can be brought into operative connection via a second clutch element with the first sun shaft, and a third toothed stage can be brought into operative connection via a third clutch element with a second sun shaft. The second sun shaft is in turn connected to a second sun gear, which is operatively connected in meshing fashion to the second stage of the planetary gear set.Preferably, the two sun shafts are arranged coaxially with respect to one another. A coaxial arrangement of the sun shafts is particularly space-saving.Preferably, the transmission ratio of the first toothed stage of the spur gear group is greater than the transmission ratio of the second toothed stage. However, the transmission ratio of the first toothed stage can also be smaller than the transmission ratio of the second toothed stage.Preferably, the at least one planetary gear is further connected to a planetary carrier, which is provided for transmitting torque to a torque distribution device. The planet carrier thus reliably transmits the torque generated by the drive unit to the torque distribution device.Furthermore, the planetary carrier can be provided in such a way that a plurality of planetary gears uniformly distributed over the circumference are present.Furthermore, it can be provided that the clutches are arranged as a dual clutch or as a triple clutch. Such clutch arrangements make possible a particularly efficient control of the drive train.Advantageously, the drive train can be designed such that the drive unit to be connected thereto can be aligned coaxially or axially parallel to the axis of rotation of the planetary gearing and / or the torque distribution device can be aligned coaxially or axially parallel to the axis of rotation of the planetary gearing. If the drive unit and / or the torque distribution device is arranged coaxially to the axis of rotation of the planetary gearing, this arrangement is particularly space-saving. If the arrangement of the drive unit and / or torque distribution device is arranged axially parallel to the axis of rotation of the planetary gearing, the drive unit or the torque distribution device can be easily mounted.Hereinafter, embodiments of the motor vehicle drive train according to the invention will be described in detail with reference to the accompanying drawings. FIGS. 1 to 5 each show a schematic representation of the motor vehicle drive train according to the invention in five different embodiments.The figures are merely schematic in nature and serve only to understand the invention. The same elements are assigned the same reference numerals. The embodiments are only exemplary and the invention is not limited thereto.FIG. 1 shows a motor vehicle drive train with a planetary gear 1 for transmitting a torque generated by the drive unit 2, such as an electric motor or an internal combustion engine, to a torque distribution device 3 arranged on the output side, such as a differential gear. The planetary gear set 1 has a planetary gear set 4 with at least one double-stepped planetary gear. The smaller second stage 6 of the planetary gear set meshes with a fixed ring gear 7, the larger first stage 5 meshes with the first sun gear 8, and the first sun gear 8 is connected to the first sun shaft 11. The shaft of the drive unit, here an electric machine, i.e. thus the rotor shaft 20, has two toothings. Shown here is a spur gear group 13 connected to the rotor shaft 20, which has a first toothing stage 14 and a second toothing stage 15. Each of the two toothed stages can be connected to the first sun shaft 11 via an associated coupling element 17, 18.The planetary gear set 4 or the planetary gears are connected to a planetary carrier 10 or rotatably mounted thereon, wherein the planetary carrier 10 drives off onto the torque distribution device 3.FIG. 2 shows a drive train according to the invention, in which the second toothed stage 15 of the spur gear group 13 is connectable not to the first sun shaft 11 as in the first embodiment, but to a second sun shaft 12 via the second clutch element 18. The second sun shaft 12 is connected to a second sun gear 9 which meshes with the second step 6 of the stepped planetary gear.FIG. 3 shows, in a further embodiment according to the invention, a three-step spur gear group 13, wherein the third toothed stage 16 can be connected to the first sun shaft 11 via a third clutch element 19 and the two first toothed stages of the first embodiment.FIGS. 4 and 5 show two further embodiments according to the invention with a triple-stepped spur gear group 13.In the embodiment shown in FIG. 5, the third toothed stage 16 can be connected to the second sun shaft 12 via the third clutch element 19, and the first toothed stage 14 and the second toothed stage 15 can be connected to the first sun shaft 11 via the first clutch element 17 or via the second clutch element 18.The motor vehicle drive train is not limited to the embodiments shown above and can also be designed differently as long as this design does not deviate from the essence of the invention.List of reference characters1 Planetary gear set 2 Drive unit 3 Torque distribution device 4 Planetary gear set 5 First stage of the planetary gear set 6 Second stage of the planetary gear set 7 Ring gear 8 First sun gear 9 Second sun gear 10 Planetary carrier 11 First sun shaft 12 Second sun shaft 13 Spur gear group 14 First toothing stage of the spur gear group 15 Second toothing stage of the spur gear group 16 Third toothing stage of the spur gear group 17 First clutch element 18 Second clutch element 19 Third clutch element 20 Rotor shaft

Claims

Motor vehicle drive train comprising a planetary gear (1) for transmitting a torque generated by a drive unit (2) to a torque distribution device (3) on the output side and a spur gear group (13) provided for operatively connecting the drive unit (2) to the planetary gear (1), wherein the spur gear group (13) has at least two toothed stages (14, 15) with different transmission ratios, the planetary gear has a planetary gear set (4) with at least one planetary gear, which comprises a first planetary stage (5) and a second planetary stage (6), which are connected to one another in a rotationally fixed manner, wherein the second planetary stage (6) is connected to a fixed ring gear (7) and the first planetary stage (5) is connected to a first sun gear (8) in a meshing operative relationship in each case, wherein the first sun gear (8) is connected to a first sun shaft (11), and the planetary gear set (4) is rotatably mounted on a planetary carrier (10), which is connected to an output shaft which is connected to the torque distribution device (3) and at least one stage of the spur gear group (13) can be brought into operative connection with the first sun shaft (11) via a coupling element, wherein the first toothed stage (14) of the spur gear group (13) can be brought into operative connection with the first sun shaft (11) via a first coupling element (17) and the second toothed stage (15) of the spur gear group (13) can be brought into operative connection with the first sun shaft (11) via a second coupling element (18).Motor vehicle drive train according to Claim 1, wherein a first toothed stage (14) of the spur gear group (13) can be brought into operative connection with the first sun shaft (11) via a first clutch element (17), and a second toothed stage (15) of the spur gear group (13) can be brought into operative connection with a second sun shaft (12) via a second clutch element (18), wherein the second sun shaft (12) is connected to a second sun gear (9) which is in meshing operative connection with the second stage (6) of the planetary gear set (4).Motor vehicle drive train according to Claim 1, wherein a third toothed stage (16) of the spur gear group (13) can furthermore be brought into operative connection with the first sun shaft (11) via a third clutch element (19).Motor vehicle drive train according to Claim 1, wherein a first toothed stage (14) of the spur gear group (13) can be brought into operative connection with the first sun shaft (11) via a first clutch element (17), and a second toothed stage (15) of the spur gear group (13) can be brought into operative connection with a second sun shaft (12) via a second clutch element (18), and a third toothed stage (16) of the spur gear group (13) can be brought into operative connection with a second sun shaft (12) via a third clutch element (19), wherein the second sun shaft (12) is connected to a second sun wheel (9) which is in operatively meshing connection with the second stage (6) of the planetary gear set (4).Motor vehicle drive train according to Claim 1, wherein a first toothed stage (14) of the spur gear group (13) can be brought into operative connection with the first sun shaft (11) via a first clutch element (17) and a second toothed stage (15) of the spur gear group (13) can be brought into operative connection with the first sun shaft (11) via a second clutch element (18), and a third toothed stage (16) of the spur gear group (13) can be brought into operative connection with a second sun shaft (12) via a third clutch element (19), wherein the second sun shaft (12) is connected to a second sun wheel (9) which is in operatively connection with the second stage (6) of the planetary gear set (4).Motor vehicle drive train according to Claim 2, 4 or 5, wherein the first sun shaft (11) and the second sun shaft (12) are arranged coaxially with respect to one another.Motor vehicle drive train according to one of Claims 1 to 6, wherein the transmission ratio of the first toothed stage (14) of the spur gear group (13) is nominally greater than the transmission ratio of the second toothed stage (15) of the spur gear group (13).Motor vehicle drive train according to one of Claims 1 to 6, wherein the transmission ratio of the first toothed stage (14) of the spur gear group (13) is nominally smaller than the transmission ratio of the second toothed stage (15) of the spur gear group (13).Motor vehicle comprising a drive unit (2), a motor vehicle drive train according to one of Claims 1 to 6 and a torque distribution device (3), wherein the drive unit is an electric motor (2) and the toothed stages (14, 15, 16) of the spur gear group (13) are connected to a rotor shaft (20) of the electric motor.

Images