Differential gear arrangement and drivetrain for a motor vehicle

Abstract

Differential gear arrangement with a housing arrangement (30) in which an input shaft (4), a first and second output shaft (32, 34) and at least a first, a second and a third planet gear set (10, 12, 38) are rotatably mounted, wherein each planet gear set (10, 12, 38) has a planet carrier (14, 16, 52) on which several rotatably mounted planet gears (18, 20, 44; 54, 56) are provided which mesh with a sun gear (22, 24, 46) and / or a ring gear (26, 28, 42), wherein the planet gear sets (10, 12, 38) are operatively connected to the output shafts (32, 34), wherein the third planet gear set (38) together with an actuator (40) forms a torque vectoring superposition unit (36) forms, wherein the actuator (40) is operatively connected to the third planet carrier (52) of the third planet gear set (38), wherein the first and the third planet gear set (10, 38) are radially nested,wherein the second planetary gear set (12) is provided offset with the actuator designed as an electric motor (40), wherein the second planetary gear set (12) is designed as a positive gear, wherein the second planet carrier (16) is operatively connected to the second output shaft (34), characterized in that the electric motor (40) is arranged radially outside, but axially inside a housing connection of the second planetary gear set (12).

Description

The invention relates to a differential gear arrangement with a housing arrangement in which an input shaft, a first and second output shaft, and at least a first, a second, and a third planetary gear set are rotatably mounted, wherein each planetary gear set has a planet carrier on which several rotatably mounted planet gears are provided, which mesh with a sun gear and / or a ring gear, wherein the planetary gear sets are operatively connected to the output shafts, wherein the third planetary gear set together with an actuator forms a torque-vectoring superposition unit, wherein the actuator is rotationally fixed to the third planet carrier of the third planetary gear set, wherein the first and the third planetary gear sets are radially nested, and wherein the second planetary gear set is offset from an actuator designed as an electric motor.wherein the second planetary gear set is designed as a positive gear set, wherein the second planet carrier is operatively connected to the second output shaft. Furthermore, the invention relates to a drive train for a motor vehicle with a drive unit that is operatively connected to the input shaft of such a differential gear arrangement. The basic principle of such a differential gear arrangement is known from the international publication WO 2005 / 120 877 A1. Due to its compact design, this differential gear arrangement is particularly suitable for use as an integral differential gear arrangement in combination with a drive unit for the powertrain of a motor vehicle. However, such a differential gear arrangement requires the use of a so-called torque vectoring superposition unit to enable active drive torque distribution. In this context, a particular embodiment is known from DE 10 2019 209 461 A1, in which the torque vectoring superposition unit is provided next to the first and second planetary gear sets of the differential gear arrangement. However, accessibility to the torque vectoring superposition unit is severely restricted and therefore only conditionally suitable for installation. A generic prior art is known from DE 10 2022 000 042 B3. Because the second planetary gear set is designed as a plus gear, with the torque transmission to the output shaft being carried out by two meshing, series-connected planetary gears in the second planetary gear set, it is possible to increase the gear ratio of the differential gear arrangement while maintaining a compact diameter for the second planetary gear set and still incorporating sufficiently large planetary gears to accommodate adequately dimensioned planetary bearings. Furthermore, it is noted that a similar differential gear arrangement is known from the subsequently published DE 10 2024 108 052 A1. The invention is based on the objective of further developing a differential gear arrangement or a drive unit in such a way that the above-mentioned problem is avoided in a simple manner. This problem is solved by arranging the electric motor radially outside, but axially inside, a housing connection of the second planetary gear set. This makes it possible to provide an accessible torque vectoring superposition unit with a short overall length of the differential gear assembly. In a particularly preferred embodiment, the input shaft is operatively connected to the first planetary gear set via a sun gear. This results in a very simple and reliable power transmission into the differential gear assembly. Advantageously, the first ring gear of the first planetary gear set and the third sun gear of the third planetary gear set are formed integrally as a sun gear ring assembly. Advantageously, the sun ring gear is operatively connected to the second sun gear of the second planetary gear set, wherein the first output shaft is operatively connected to the third ring gear of the third planetary gear set. The problem is also solved by a drive train for a motor vehicle with a drive unit that is operatively connected to the input shaft of such a designed differential gear arrangement. The invention is explained in more detail with reference to a drawing. Here, Fig. 1a shows a sectional view of a differential gear arrangement known per se, Fig. 1b a simplified, schematic view of the differential gear arrangement from Fig. 1a, Fig. 2 a non-inventive embodiment of a differential gear arrangement, and Fig. 3 an embodiment of a differential gear arrangement according to the invention. Fig. 1a shows a sectional view of a differential gear assembly 2, which is known per se from the prior art. The differential gear assembly 2 is part of a drive train for a motor vehicle (not shown in detail). A rotor shaft 4, which together with a stator 6 forms a drive unit 8 shown in Fig. 1b, constitutes an input shaft 4 of the differential gear assembly 2. The differential gear assembly 2 combines the functions of transmission and differential operation. The differential gear assembly 4 is essentially composed of two radially nested planetary gear sets 10, 12. The first planetary gear set 10 can also be referred to as the inner planetary gear set 10 and the second planetary gear set 12 as the outer planetary gear set 12. Each planetary gear set 10, 12 has a planet carrier 14, 16, on which several rotatably arranged planet gears 18, 20 are provided in a known manner. These planet gears 18, 20 mesh with a sun gear 22, 24 and a ring gear 26, 28 in a known manner. The first ring gear 26 of the first planet gear set 10 and the second sun gear 24 of the second planet gear set 12 are formed integrally as component 29. The planet gear sets 10, 12 are provided within a housing arrangement 30, which is only partially shown here, and in which the input shaft 4, as well as a first output shaft 32 and a second output shaft 34, which are operatively connected to the differential gear arrangement 2 in a known manner, are rotatably mounted by means of a bearing arrangement not described in detail. Fig. 1b shows the differential gear arrangement 2 described above with the drive unit 8 in a highly simplified, schematic view, which is intended to serve as the basis for the embodiment of a differential gear arrangement 3 according to the invention shown in Fig. 2 and Fig. 3.Fig. 2 shows a non-inventive embodiment of the differential gear arrangement 3 according to the invention. To enable active drive torque distribution, a torque vectoring superposition unit 36 ​​is provided, which essentially consists of a third planetary gear set 38 and an actuator 40 operatively connected thereto, which here is designed as a second electric motor. Here too, the input shaft 4 engages the planet gears 18 of the first planetary gear set 10 via the sun gear 22 and thus drives the first output shaft 32 via the first planet carrier 14. According to the invention, the third planetary gear set 38 is arranged radially nested with respect to the first planetary gear set 10. A third ring gear 42 for planet gears 44 of the third planetary gear set 38 is also operatively connected to the first planet carrier 14.Furthermore, the first ring gear 26 of the first planetary gear set 10 is integrally connected to a sun gear 46 of the third planetary gear set 38, thus forming a sun-ring gear assembly 48, which in turn is operatively connected to the sun gear 24 for the planet gears 20 of the second planetary gear set 12, the ring gear 28 of which is operatively connected to the second output shaft 34. The planet carrier 16 of the second planetary gear set 12 is connected to the housing assembly 30. The second electric motor 40 is rotationally connected to a third planet carrier 52 via a gear 50 in order to distribute the drive torque to the output shafts 32 and 34 in a known manner. It is, of course, conceivable and practical to implement further transmission elements between the electric motor 40 and the planet carrier 52.The embodiment shown here corresponds to a negative gear with second planet gears 20, which have a small diameter, resulting in a low overall gear ratio of the differential gear arrangement 3. To achieve a higher overall gear ratio of the differential gear assembly 3, the second planetary gear set 12 can also be designed as a plus gear (see Fig. 3), wherein there is an inner planet gear 54 that meshes with the sun gear 24 and an outer planet gear 56 that meshes with the inner planet gear 54 and the second ring gear 28. In this embodiment, the second planet carrier 16 is operatively connected to the second output shaft 34.

Claims

Differential gear arrangement with a housing arrangement (30) in which an input shaft (4), a first and second output shaft (32, 34) and at least a first, a second and a third planet gear set (10, 12, 38) are rotatably mounted, wherein each planet gear set (10, 12, 38) has a planet carrier (14, 16, 52) on which several rotatably mounted planet gears (18, 20, 44; 54, 56) are provided which mesh with a sun gear (22, 24, 46) and / or a ring gear (26, 28, 42), wherein the planet gear sets (10, 12, 38) are operatively connected to the output shafts (32, 34), wherein the third planet gear set (38) together with an actuator (40) forms a torque vectoring superposition unit (36) forms, wherein the actuator (40) is operatively connected to the third planet carrier (52) of the third planet gear set (38), wherein the first and the third planet gear set (10, 38) are radially nested,wherein the second planetary gear set (12) is provided offset with the actuator designed as an electric motor (40), wherein the second planetary gear set (12) is designed as a positive gear, wherein the second planet carrier (16) is operatively connected to the second output shaft (34), characterized in that the electric motor (40) is arranged radially outside, but axially inside a housing connection of the second planetary gear set (12). Differential gear arrangement according to claim 1, characterized in that the input shaft (4) is operatively connected to the first planet gear set (10) via a sun gear (22). Differential gear arrangement according to claim 2, characterized in that the first ring gear (26) of the first planet gear set (10) is formed in one piece with the third sun gear (46) of the third planet gear set (38) as a sun ring gear element (48). Differential gear arrangement according to claim 3, characterized in that the sun ring gear element (48) is operatively connected to the second sun gear (24) of the second planet gear set (12). Differential gear arrangement according to one of the preceding claims, characterized in that the first output shaft (32) is operatively connected to the third ring gear (42) of the third planetary gear set (38). Drive train for a motor vehicle with a drive unit (8) which is operatively connected to the input shaft (6) of a differential gear arrangement (3) according to one of the preceding claims.

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