Transmission and drive unit with a transmission for a vehicle

Abstract

The invention relates to a transmission (1) for a vehicle (100) comprising at least one planetary gear set (2) with a sun gear shaft (3), a ring gear shaft (4), a carrier shaft (5) and a plurality of planetary gears (10), and a differential (6) with a differential input shaft (7) and two differential output shafts (8, 9), wherein the planetary gear set (2) is arranged on a first rotational axis (14), wherein the differential (7) is arranged on a second rotational axis (15) which is axially parallel to the first rotational axis (14), wherein the sun gear shaft (3) is configured as the input shaft of the planetary gear set (2), wherein the ring gear shaft (4) is configured as the output shaft of the planetary gear set (2), wherein the carrier shaft (5) is connected in a rotationally fixed manner to a stationary component, characterized in that the ring gear shaft (4) has an internal toothing (11) and an external toothing (12),wherein the internal toothing (11) of the ring gear shaft (4) meshes with a toothing on the respective planetary gear (10), wherein the external toothing (12) of the ring gear shaft (4) meshes with a toothing on the differential input shaft (7).

Description

[0001] The invention relates to a transmission for a vehicle. Furthermore, the invention relates to a drive unit for a vehicle, wherein the drive unit comprises an electric motor and such a transmission. The invention also relates to a vehicle with such a drive unit.

[0002] Generally, transmissions for vehicles are known that have a planetary gear set with a sun gear shaft, a ring gear shaft, and a carrier shaft. Furthermore, such transmissions can also have a differential with a differential input shaft and two differential output shafts. In such transmissions, the differential is usually indirectly connected to the planetary gear set via at least one spur gear stage, in particular via an intermediate shaft with spur gears. Such an intermediate shaft requires not only radial but also axial installation space. With electric drive axles, installation space is limited because energy storage devices for supplying electrical energy to an electric drive motor take up installation space.

[0003] The object of the present invention is to provide an alternative transmission for a vehicle. In particular, the transmission should be compact. This object is achieved by a transmission having the features of independent patent claim 1. Advantageous embodiments are the subject of the dependent claims, the following description, and the figures.

[0004] A transmission according to the invention for a vehicle comprises at least one planetary gear set with a sun gear shaft, a ring gear shaft, a carrier shaft and a plurality of planetary gears and a differential with a differential input shaft and two differential output shafts, wherein the planetary gear set is arranged on a first axis of rotation, wherein the differential is arranged on a second axis of rotation, which is axially parallel to the first axis of rotation, wherein the sun gear shaft is configured as the input shaft of the planetary gear set, wherein the ring gear shaft is configured as the output shaft of the planetary gear set, wherein the carrier shaft is connected in a rotationally fixed manner to a stationary component, wherein the ring gear shaft has an internal toothing and an external toothing, wherein the internal toothing on the ring gear shaft meshes with a toothing on the respective planetary gear,wherein the external toothing on the ring gear shaft meshes with a toothing on the differential input shaft.

[0005] In other words, the internal and external gearing are designed as running gears and are functionally integrated into the ring gear, eliminating the need for additional components to connect the planetary gear set to the differential. The planetary gear set is thus directly connected to the differential, eliminating the need for additional components, particularly shafts and / or gears, in the power flow between the planetary gear set and the differential. This makes the transmission more compact axially and radially.

[0006] For the purposes of the invention, a “shaft” is understood to be a rotatable component of the transmission via which associated components of the transmission are connected to one another in a rotationally fixed manner or via which such a connection can be established upon actuation of one of the shift elements. The respective shaft can connect the components axially or radially, or even both axially and radially. The respective shaft can also be in the form of an intermediate piece via which a respective component is connected radially, for example. The term “shaft” does not exclude the possibility that the components to be connected can be designed as a single piece. In particular, two or more shafts connected to one another in a rotationally fixed manner can be designed as a single piece.

[0007] A “stationary component” is a component that is fixed in a stationary manner, in particular that is connected in a rotationally fixed manner or in one piece to a housing or part of a housing.

[0008] According to a preferred embodiment, the planetary gear set and the differential are arranged to overlap axially, at least partially or completely. This makes the transmission more axially compact.

[0009] According to a preferred embodiment, the internal gearing and the external gearing are integrally connected to the ring gear shaft and are designed as respective running gears. For example, the internal gearing and the external gearing are designed as respective spur gears on the ring gear shaft. Thus, the respective teeth of the respective spur gearing are designed parallel to the axis of rotation. Accordingly, spur gearing is designed on the planet gears as well as on the differential input shaft. Alternatively, the internal gearing and the external gearing are designed as respective helical gears on the ring gear shaft. Thus, the respective teeth of the respective helical gearing are not designed parallel to the axis of rotation. Accordingly, helical gearing is designed on the planet gears as well as on the differential input shaft, which has a pitch opposite to the respective helical gearing on the ring gear.The gear ratio between the planetary gear set and the differential can be adjusted by changing the number of teeth on the ring gear. For example, the ring gear with its two running gears is made of steel or aluminum.

[0010] For example, the differential is designed as a bevel gear differential. A differential designed as a bevel gear differential has two wheel-side output elements, in particular a first output gear and a second output gear. The two output gears each mesh with a compensating element. The compensating elements are mounted in a differential carrier so they can rotate about their own axis. The respective output gear is connected in a rotationally fixed manner to the respective differential output shaft. The differential is driven via the differential carrier, which is designed as a differential input shaft. The drive power fed into the differential gear is distributed between the differential output shafts and transmitted to the drive wheels of the axle. The differential output shafts are designed to be drivingly connected to the drive wheels of the vehicle. The respective differential output shaft can be directly or indirectly.be indirectly connected to the corresponding vehicle wheel via a joint, a cardan shaft and / or a wheel hub.

[0011] According to one embodiment, the differential is designed as an integral differential with a first planetary gear set and a second planetary gear set. In particular, the two planetary gear sets of the integral differential are radially nested, with the shift elements being arranged axially between the radially nested planetary gear sets of the manual transmission and the integral differential. This increases the compactness of the manual transmission. An “integral differential” is understood to mean a differential with a first planetary gear set and a second planetary gear set operatively connected to the first planetary gear set. The first planetary gear set of the integral differential is, on the one hand, drive-effectively connected to the output shaft of the manual transmission, and, on the other hand, drive-effectively connected to the second planetary gear set of the integral differential and at least indirectly to the first differential output shaft.The second planetary gear set of the integral differential is also drive-connected to the second differential output shaft and is supported on a stationary component, in particular a housing component. Using such an integral differential, the input torque introduced into the integral differential can be converted and distributed between the two differential output shafts in a defined ratio. In particular, the input torque is transmitted equally to the two differential output shafts.

[0012] At identical output shaft speeds, the integral differential has no gears rotating in the block or rotating without a rolling motion. Therefore, regardless of the output shaft speeds, there is always a relative movement between the meshing components of the integral differential. With an integral differential, the sum of both wheel torques is not combined or summarized into a common axle torque in one component; instead, the drive power is divided in the integral differential and transmitted to the differential output shafts connected to them in accordance with the design of the first and second planetary gear sets. This allows the components of the integral differential to be designed more slenderly due to the comparatively low torque. Furthermore, a reduction in components and weight is achieved.Using such an integral differential, the two functions of torque conversion and torque distribution, which are usually performed by two separate components, can be implemented by a single integral component. The integral differential is thus a combined transmission and differential gear that, on the one hand, realizes torque conversion and, on the other hand, torque distribution to the differential output shaft.

[0013] A drive unit according to the invention comprises an electric machine designed as a prime mover with a stator and a rotor, as well as a transmission according to the invention. According to one embodiment, the rotor is connected in a rotationally fixed manner to the sun shaft of the planetary gear set. In particular, the rotor is connected to the sun shaft of the planetary gear set via a drive shaft. For example, the sun shaft of the planetary gear set is integrally connected to the drive shaft.

[0014] According to one embodiment, the electric motor is arranged axially adjacent to the planetary gear set on the first rotational axis. Thus, the electric motor is arranged coaxially to the planetary gear set and axially parallel to the differential. In other words, no further components are arranged axially between the electric motor and the differential.

[0015] A vehicle according to the invention comprises at least one transmission according to the invention or at least one drive unit according to the invention. The above definitions as well as explanations regarding technical effects, advantages, and advantageous embodiments of the transmission according to the invention also apply mutatis mutandis to the drive unit according to the invention and the vehicle according to the invention.

[0016] Advantageous embodiments of the invention, which are explained below, are illustrated in the drawings, wherein identical or similar elements are provided with the same reference numerals. They show: Fig. 1 a highly abstracted schematic view of a vehicle with a drive axle having a drive unit according to the invention; Fig. 2 a highly abstracted schematic view of a transmission according to the invention; and Fig. 3 an abstract schematic perspective view of a ring gear of the transmission according to the invention.

[0017] Fig. 1 shows a vehicle 100 with a first axle 101 with two vehicle wheels R1, R2 and a second axle 102 with two vehicle wheels R3, R4. In the present case, the first axle 101 is designed as the rear drive axle of the vehicle 100 and is equipped with a drive unit according to the invention. The drive unit comprises an electric machine 16, which is configured to generate drive power, and a transmission 1, which is drivingly connected to the electric machine 16 and the wheels R1, R2 of the first axle 101. The vehicle 100 is designed as an electric vehicle and can therefore be driven electrically. The drive unit is arranged transversely to the vehicle's longitudinal direction. In the present case, no further drive unit is arranged on the second axle 102, i.e., on the front axle of the vehicle 100, thereby saving costs, weight, and installation space.Alternatively, the drive unit can be arranged on the front axle of the vehicle 100 instead of on the rear axle and can be drivingly connected to the vehicle wheels R3, R4 of the second axle 102. Furthermore, to implement an all-wheel drive system, in addition to the drive unit on the first axle 101, a further drive unit can be arranged on the second axle 102 and can be drivingly connected to the vehicle wheels R3, R4 of the second axle 102.

[0018] Fig. Figure 2 shows the drive unit according to the invention with the transmission 1 according to the invention. The transmission 1 has a planetary gear set 2 and a differential 6. The planetary gear set 2 is arranged on a first axis of rotation 14, and the differential 6 is arranged on a second axis of rotation 15, with the first axis of rotation 14 being axially parallel to the second axis of rotation 15. The differential 6 has a differential input shaft 7 and two differential output shafts 8, 9 and can be designed, for example, as a bevel gear differential. The drive of the differential 6 is via the differential carrier, which is designed as a differential input shaft 7 with teeth. The drive power fed into the differential 6 is distributed in a known manner between the two differential output shafts 8, 9 and transmitted to the drive wheels of the axle.The differential output shafts 8, 9 are designed to be drivingly connected to the drive wheels of the vehicle. The respective differential output shaft 8, 9 can be connected to the corresponding vehicle wheel directly or indirectly via a joint, a propeller shaft, and / or a wheel hub.

[0019] The planetary gear set 2 comprises three shafts, namely a sun gear shaft 3, a ring gear shaft 4, and a planetary gear shaft 5. The planetary gear shaft 5 carries several planetary gears 10 that mesh with the sun gear shaft 3 and the ring gear shaft 4. The sun gear shaft 3 is designed as the input shaft of the planetary gear set 2 and is rotationally fixedly connected to a drive shaft 19 of the transmission 1. Drive power is fed into the transmission 1 via the drive shaft 19, which in turn is rotationally fixedly connected to a rotor 18 of the electric machine 16. The planetary gear shaft 5 is rotationally fixedly connected to a stationary component designed as a housing 13. The planetary gear set 2 thus forms a constant transmission ratio. The ring gear shaft 4 is designed as the output shaft of the planetary gear set 2 and has internal gearing 11 and external gearing 12.The internal gearing 11 on the ring gear shaft 4 meshes with the gearing on the respective planetary gears 10, and the external gearing 12 on the ring gear shaft 4 meshes with the gearing on the differential input shaft 7. This generates an additional gear ratio, while no additional components are required to connect the planetary gear set 2 to the differential 6. The transmission 1 has a particularly compact design. The planetary gear set 2 and the differential 7 are arranged with axial overlap, thus saving axial installation space.

[0020] Fig. 3 shows the ring gear shaft 4 according to Fig. 2 in perspective. The internal gearing 11 and the external gearing 12 are one-piece and each formed as a helical gear on the ring gear shaft 4. The ring gear shaft 4 can be machined from a steel material, for example. Reference symbol 1 gearbox 2 planetary gear sets 3 Sunwave 4 ring gear shaft 5 web wave 6 Differential 7 Differential input shaft 8 first differential output shaft 9 second differential output shaft 10 Planetary gear 11 Internal gearing 12 external teeth 13 housings 14 first rotation axis 15 second rotation axis 16 electric machine 17 Stator 18 Rotor 19 Drive shaft 100 vehicles 101 first axis 102 second axis R1 vehicle wheel R2 vehicle wheel R3 vehicle wheel R4 vehicle wheel

Claims

[1] Transmission (1) for a vehicle (100) comprising at least one planetary gear set (2) with a sun gear shaft (3), a ring gear shaft (4), a carrier shaft (5) and a plurality of planetary gears (10) and a differential (6) with a differential input shaft (7) and two differential output shafts (8, 9), wherein the planetary gear set (2) is arranged on a first rotational axis (14), wherein the differential (7) is arranged on a second rotational axis (15) which is axially parallel to the first rotational axis (14), wherein the sun gear shaft (3) is configured as the input shaft of the planetary gear set (2), wherein the ring gear shaft (4) is configured as the output shaft of the planetary gear set (2), wherein the carrier shaft (5) is connected in a rotationally fixed manner to a stationary component, characterized bythat the ring gear shaft (4) has an internal toothing (11) and an external toothing (12), wherein the internal toothing (11) on the ring gear shaft (4) is in tooth engagement with a toothing on the respective planet gear (10), wherein the external toothing (12) on the ring gear shaft (4) is in tooth engagement with a toothing on the differential input shaft (7). [2] Transmission (1) according to claim 1, wherein the planetary gear set (2) and the differential (7) are arranged at least partially axially overlapping. [3] Gearbox (1) according to claim 1 or 2, wherein the internal toothing (11) and the external toothing (12) are integrally connected to the ring gear shaft (4) and are designed as respective running toothing. [4] Drive unit for a vehicle (100), comprising an electric machine (16) designed as a drive machine with a stator (17) and a rotor (18) and a transmission (1) according to one of the preceding claims. [5] Drive unit according to claim 4, wherein the rotor (18) is connected in a rotationally fixed manner to the sun shaft (3) of the planetary gear set (2). [6] Drive unit according to claim 4 or 5, wherein the electric machine (16) is arranged on the first rotational axis (14) axially adjacent to the planetary gear set (2). [7] Vehicle (100) comprising at least one transmission according to one of claims 1 to 5 or at least one drive unit according to one of claims 4 to 6.

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