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, 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 coupled 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), the first sun gear (8) being connected to a first sun shaft (11), at least one toothing stage 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 planetary gear set (4) is rotatably mounted on a planet carrier (10) which is connected to a through-drive shaft (21) which can be brought into operative connection with a further toothing stage of the spur gear group (13) via a further coupling element.

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 transmission which is provided for transmitting 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 transmission, wherein the planetary transmission has a planetary gear set with at least one double-stepped planetary gear, wherein one of the two 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. 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.Furthermore, the planetary carrier can be provided in such a way that a plurality of planetary gears uniformly distributed over the circumference are present. 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.The planetary gear set is rotatably mounted on a planet carrier which is connected to a drive shaft which can be brought into operative connection with a toothed stage of the spur gear group via a clutch element.Advantageous embodiments of the invention form part of the dependent claims and are explained in more detail below.In a further advantageous embodiment, the spur gear group has at least three toothing stages of different circumference. In this case, a first toothed stage can be brought into operative connection with the first sun shaft via a first clutch element and, furthermore, a second toothed stage can be brought into operative connection with the drive shaft via a second clutch element and a third toothed stage can be brought into operative connection with the drive shaft via a third clutch element.In a further preferred embodiment, the spur gear group again has at least three toothing stages of different circumference. In this case, a first toothed stage can be operatively connected to the first sun shaft via a first clutch element and a second toothed stage can be operatively connected to the first sun shaft via a second clutch element. A third toothed stage can be operatively connected to the drive shaft via a third clutch element.Preferably, the first sun shaft and the drive shaft are arranged coaxially with respect to one another.In a further preferred embodiment, the spur gear group has at least three toothing stages of different circumference. In this case, the first toothed stage can be brought into operative connection with the first sun shaft via a first clutch element, and the second toothed stage can be brought into operative connection with a second sun shaft via a second clutch element, and the third toothed stage can be brought into operative connection with the drive shaft via a third clutch element.In this case, the sun shafts and the drive shaft are preferably arranged coaxially with respect to one another.Preferably, the transmission ratio of the first toothed stage of the spur gear group is nominally greater than the transmission ratio of the second toothed stage of the spur gear group. Alternatively, the transmission ratio of the first toothed stage is nominally smaller than the transmission ratio of the second toothed stage of the spur gear group.Further preferably, the transmission ratio of the third toothed stage of the spur gear group is smaller than the transmission ratio of the second toothed stage of the spur gear group.Furthermore, it can be provided that the clutches are arranged as a dual clutch or as a triple clutch. Such a clutch enables a particularly efficient control of the drive train.Advantageously, the drive train can be designed such that the drive unit is aligned coaxially or axially parallel to the axis of rotation of the planetary gearing and / or the torque distribution device is 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.An embodiment of the motor vehicle drive train according to the invention is described in detail below with reference to the attached drawings. FIGS. 1 to 4 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 toothing stages. 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.The first toothed stage 14 can be connected to the first sun shaft 11 via the first clutch element 17. The second toothed stage 15 can be connected to the drive shaft 21 via the second clutch element 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 and is connected to the drive shaft 21, which can be connected via the second clutch element 18 to the second toothed stage 15 of the spur gear group 13.FIG. 2 shows a further drive train according to the invention with a triple-stepped spur gear group 13, in which, in addition to the second toothed stage 15, the third toothed stage 16 can also be connected to the drive shaft 21 via a clutch element, namely via the third clutch element 18.FIG. 3 shows a further drive train according to the invention having a triple-stepped spur gear group 13, in which the first toothed stage 14 and the second toothed stage 15 of the spur gear group 13 can be connected to the first sun shaft 11 via the first clutch element 17 or the second clutch element 18, respectively, and the third toothed stage 16 can be connected to the drive shaft 21 via the third clutch element 18.FIG. 4 shows a further drive train according to the invention having a triple-stepped spur gear group 13, in which the first toothed stage 14 of the spur gear group 13 is connectable via the first clutch element 17 to the first sun shaft 11, the second toothed stage 15 of the spur gear group 13 is connectable via the second clutch element 18 to the second sun shaft 12 and the third toothed stage 16 is connectable via the third clutch element 18 to the drive shaft 21.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 21 Through-drive 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, 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 coupled to one another in a rotationally fixed manner, wherein the second planetary stage (6) is operatively connected to a fixed ring gear (7) and the first planetary stage (5) is operatively connected to a first sun gear (8), in each case, wherein the first sun gear (8) is connected to a first sun shaft (11), at least one toothed stage 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 the planetary gear set (4) is rotatably mounted on a planetary carrier (10) which is connected to a drive shaft (21) which can be brought into operative connection with a further toothed stage of the spur gear group (13) via a further clutch element.Motor vehicle drive train according to Claim 1, wherein the spur gear group (13) has at least three toothed stages with different transmission ratios, wherein a first toothed stage (14) can be brought into operative connection with the first sun shaft (11) via a first clutch element (17), and a second toothed stage (15) can be brought into operative connection with the drive shaft (21) via a second clutch element (18), and a third toothed stage (16) can be brought into operative connection with the drive shaft (21) via a third clutch element (19).Motor vehicle drive train according to Claim 1, wherein the spur gear group (13) has at least three toothed stages with different transmission ratios, wherein a first toothed stage (14) can be operatively connected to the first sun shaft (11) via a first clutch element (17) and a second toothed stage (15) can be operatively connected to the first sun shaft (11) via a second clutch element (18), and a third toothed stage (16) can be operatively connected to the drive shaft (21) via a third clutch element (19).Motor vehicle drive train according to one of Claims 1 to 3, wherein the first sun shaft (11) and the drive shaft (21) are arranged coaxially with respect to one another.Motor vehicle drive train according to Claim 1, wherein the spur gear group (13) has at least three toothed stages (14, 15, 16) with different transmission ratios, wherein a first toothed stage (14) can be brought into operative connection with the first sun shaft (11) via a first clutch element (17), a second toothed stage (15) 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 wheel (9) which is operatively connected in meshing connection with the second planetary stage (6), and a third toothed stage (16) can be brought into operative connection with the drive shaft (21) via a third clutch element (19).Motor vehicle drive train according to Claim 5, wherein the sun shafts (11, 12) and the drive shaft (21) 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 drive train according to one of Claims 2 to 8, wherein the transmission ratio of the third toothed stage (16) 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).The motor vehicle drive train according to any one of the preceding claims, wherein at least one gearwheel of the toothed stages (14, 15, 16) of the spur gear group (13) is coupled to the rotor shaft (20) in a rotationally fixed manner.

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