Vehicle axle for a two-track vehicle

Abstract

The invention relates to a vehicle axle for a two-track vehicle, with a main drive (EM1) which, in a train operation, drives via an axle differential-free torque distribution unit (3) to the two flange shafts (17, 18) of the vehicle axle (HA) leading to the vehicle wheels, wherein the torque distribution unit (3) has an output gear (15) arranged rotationally fixed on the first flange shaft (17). According to the invention, the torque distribution unit (3) also has a superimposed transmission (20) with at least one planetary gear (PG1, PG2), the input element (31; 43) of which is non-rotatably connected at a node (K) to the output gear (15) of the first flange shaft (17), the output element (29; 31) of which is non-rotatably connected to the second flange shaft (18), and the reaction element (19; 25) of which is drivenly connected to an auxiliary drive (EM2).

Description

[0001] The invention relates to a vehicle axle for a two-track vehicle according to the preamble of claim 1.

[0002] In a conventional, for example, electrified vehicle rear axle, a state-of-the-art axle differential is installed. This differential can be connected on the input side to a primary drive motor (e.g., an electric motor or internal combustion engine) and on the output side to the vehicle wheels of the axle via flanged shafts on both sides. Such a vehicle axle also features a superimposed transmission, which allows a drive torque generated by a secondary drive motor (e.g., an electric motor) to be coupled into a flanged shaft on the transmission side to perform electronic torque vectoring.

[0003] Such a vehicle axle is therefore built with the axle differential and the superimposed transmission, which usually consists of two planetary gears arranged side by side, resulting in a correspondingly high overall installation space requirement for the vehicle axle.

[0004] A drive system for a hybrid vehicle is known from US patent 8,425,375 B2. The drive system includes a transmission mechanism that combines and distributes the power generated by an internal combustion engine and an electric motor. Furthermore, the drive system includes a transmission mechanism located between the internal combustion engine and a vehicle axle. This transmission mechanism is a planetary gear arrangement.

[0005] From DE 10 2008 061 945 A1, an electric axle drive unit with variable torque distribution within a vehicle axle is known. A main motor acts via a first shaft on a first planetary gear set. A torque-vectoring motor acts via a first shaft on a second planetary gear set. The first planetary gear set is mounted to the housing via a second shaft and connected to a first wheel of the vehicle axle via a third shaft. A second shaft of the second planetary gear set is connected to a second wheel of the vehicle axle, and a third shaft is rotationally fixed to the third shaft of the second planetary gear set.

[0006] From DE 10 2018 101 980 A1, a drive device with variable torque distribution on a first and second output shaft, arranged within an output axle of a motor vehicle, is known. The drive device comprises a main motor, a torque-vectoring motor, and a transmission device with a first and second planetary gear set. From DE 10 2021 006 011 A1, an electric drive system is known that has a reduced coupling transmission comprising a first planetary gear set, a second planetary gear set, a first input shaft, a second input shaft, a first output shaft, and a second output shaft. From DE 10 2022 000 543 A1, another electric drive system is known that can be switched from a torque distribution mode to an assistance mode. The drive system includes a four-shaft planetary differential.

[0007] The object of the invention is to provide a vehicle axle for a two-track vehicle whose installation space requirement is reduced compared to the prior art.

[0008] The problem is solved by the features of claim 1. Preferred embodiments of the invention are disclosed in the dependent claims.

[0009] The invention relates to a vehicle axle for a two-track vehicle, in which a main drive (for example, an electric motor) transmits power in traction mode via an axle differential-free torque distribution unit to the two flange shafts of the vehicle axle leading to the vehicle wheels, namely the first and second flange shafts. The torque distribution unit has an output gear mounted non-rotatably on the first flange shaft. By omitting an axle differential, the installation space required for the vehicle axle can be significantly reduced compared to the prior art. With regard to a uniform torque distribution or torque differential between the two flange shafts during traction mode, the torque distribution unit, according to the characterizing part of claim 1, comprises a superimposed transmission with at least one planetary gear set.Its input element is fixedly connected at a node to the output gear of the first flange shaft. Furthermore, an output element of the superimposed transmission is fixedly connected to the second flange shaft, with a reaction element of the superimposed transmission being driven by an auxiliary drive. This auxiliary drive can also be implemented as an electric motor, which has a significantly reduced motor power compared to the main drive.

[0010] In the transmission structure according to the invention, a load path coming from the main drive can be split at the node into a first partial load path leading via the drive gear to the first flange shaft and a second partial load path leading via the superimposed gear to the second flange shaft. According to the invention, it is relevant that the drive torque flowing in the second partial load path is supported on the reaction element, which is connected to the auxiliary drive.

[0011] During train operation, the main drive and the auxiliary drive operate in parallel, meaning that both the main drive and the auxiliary drive continuously generate drive torque. Depending on the driving situation, the torque distribution unit can vary the drive torque generated by the auxiliary drive to either apply a uniform 50 / 50 torque distribution to the two flange shafts, or alternatively, to create a torque difference between the two flange shafts.

[0012] A key aspect of the invention is a space-saving design of the vehicle axle. This can be achieved through the following measures: The superimposed transmission can be arranged, in axial terms, in a space between the output gear and the auxiliary drive. The main drive and the auxiliary drive can be installed transversely within the vehicle axle, so that both the main and auxiliary drives are aligned parallel to the flange sources and the transmission shafts of the torque distribution unit.

[0013] In a specific embodiment, the superimposed transmission can comprise two coupled planetary gear sets. These can be mounted axially side by side and coaxially to the flange shafts. Of the two planetary gear sets, one input-side planetary gear set is non-rotatably connected to the output gear via its input element, forming the node. In contrast, one output-side planetary gear set is non-rotatably connected to the second drive shaft via its output element.

[0014] Of the two flange shafts, the first flange shaft is located farther from the gearbox, meaning it is axially separated from the superimposed gearbox. In contrast, the second flange shaft is located close to the superimposed gearbox; that is, the second flange shaft extends coaxially through the superimposed gearbox.

[0015] Depending on the design of the superimposed gearbox's transmission structure, both the main drive and the auxiliary drive can operate in motor mode during train operation. For this purpose, the transmission structure can be designed as follows, according to which - the input-side planetary gear has a ring gear or a hollow shaft gear as its input element; - the output-side planetary gear unit has a planet carrier as its output element, which is connected to the second flange shaft via a drive flange in a rotationally fixed manner; - the input-side planetary gear has a sun gear as a reaction element, which is arranged as a fixed gear on a radially inner hollow shaft, which is connected to the auxiliary drive via a secondary drive reduction gear; - the planet carrier of the input-side planetary gear set is connected to the sun gear of the output-side planetary gear set via a coupling flange; and - the ring gear of the input-side planetary gear set and the ring gear of the output-side planetary gear set are formed on a common ring gear shaft. In this case, the common ring gear shaft is non-rotatably connected to the output gear at the coupling point.

[0016] In contrast, according to another embodiment, in vehicle-train operation the main drive can operate in motor mode while the auxiliary drive operates in generator mode. This is achieved with the following transmission structure, according to which - the input-side planetary gear unit has a planetary gear carrier as its input element; - the output-side planetary gear has a ring gear shaft as its output element, on which the ring gears of the two planetary gears are formed, wherein the ring gear shaft is connected to the second drive shaft in a rotationally fixed manner via an output flange; - the output-side planetary gear set has a sun gear as a reaction element, which is arranged as a fixed gear on a radially inner hollow shaft, which is connected to the auxiliary drive via a secondary drive reduction gear; and / or - the sun gear of the input-side planetary gear is connected to the planet carrier of the output-side planetary gear via a coupling flange.

[0017] In a preferred technical implementation, the main drive can be rigidly connected to the output gear via a main drive reduction gear. The main drive reduction gear effects a torque conversion. Furthermore, the main drive reduction gear can be designed as a spur gear stage with a short axial profile, in particular a double spur gear stage. In such a double spur gear stage, a fixed gear arranged on the power output shaft of the main drive meshes in a first transmission stage with an input gear arranged non-rotatably on an intermediate shaft, and in a second transmission stage, an output gear arranged non-rotatably on the intermediate shaft meshes with the output gear of the first flange shaft.

[0018] In a further development of the invention, the provision of conventional vehicle wheel brakes can be dispensed with. Instead, each of the flange shafts can have a multi-disc brake as a vehicle wheel brake, with the aid of which vehicle braking can be carried out.

[0019] Exemplary embodiments of the invention are described below with reference to the accompanying figures.

[0020] They show: Fig. 1 and Fig. 2 the transmission structure according to a first and second embodiment; as well as Fig. 3 and Fig. 4 the transmission structure according to a third and fourth embodiment.

[0021] In the Fig. Figure 1 shows the transmission structure of, for example, an electrified rear axle of a two-track vehicle. The vehicle axle has an electric motor as its main drive EM1, which is connected via a main drive reduction gear 1 to an axle differential-free torque distribution unit 3. From each of its output sides, an output shaft 17, 18 leads to a vehicle wheel (not shown). The main drive reduction gear 1 is located in the Fig. 1 is realized as a double spur gear stage, namely with a first transmission stage 4, in which a fixed gear 7 arranged on the power output shaft 5 of the main drive EM1 meshes with an input gear 11 arranged non-rotatably on an intermediate shaft 9, and in a second transmission stage 12 an output gear 13 arranged non-rotatably on the intermediate shaft 9 meshes with an output gear 15 of the torque distributor unit 3, which is mounted non-rotatably on a first flange shaft 17.

[0022] The torque distribution unit 3 also includes a superimposed gearbox 20 with an electric motor as a power take-off EM2. The power take-off EM2 and the main drive EM1 are installed transversely in the vehicle axle. Accordingly, their rotor shafts, as well as the rotating components of the vehicle axle and the two flange shafts 17, 18, are aligned parallel to each other. The superimposed gearbox 20 consists of the Fig. 1 consists of two axially adjacent and coupled planetary gear sets PG1, PG2, which are aligned coaxially to the flange shafts 17, 18. Furthermore, the superimposed gear set 20 with its two planetary gear sets PG1, PG2 is positioned in an installation space between the output gear 15 and the auxiliary drive EM2.

[0023] Of the two flange shafts 17, 18, the first flange shaft 17 runs far from the gearbox, i.e. with an axial distance to the superimposed gearbox 20, while the second flange shaft 18 runs close to the gearbox, i.e. extends coaxially through the superimposed gearbox 20.

[0024] In the Fig. In Figure 1, the vehicle axle features a transmission structure that enables both the main drive EM1 and the auxiliary drive EM2 to operate in motor mode during train operation. Accordingly, the input-side planetary gear set PG1 has a sun gear 19 connected via planet gears to a radially outer ring gear 21. The planet gears are rotatably mounted on a rotating planet carrier 23. Similarly, the output-side planetary gear set PG2 has a sun gear 25 connected via planet gears to a radially outer ring gear 27. The planet gears are rotatably mounted on a rotating planet carrier 29. The ring gears 21 and 27 of both planetary gear sets PG1 and PG2 are connected to a common ring gear shaft 31. This shaft forms an input element that is non-rotatably connected to the output gear 15 at a coupling point K.

[0025] In the output-side planetary gear unit PG2, the planet carrier 29 forms an output element which is rotationally fixed to the second flange shaft 18 via a drive flange 31. Furthermore, the planet carrier 23 of the input-side planetary gear unit PG1 is coupled to the sun gear 25 of the output-side planetary gear unit PG2 via a coupling flange 33.

[0026] The sun gear 25 of the input-side planetary gear set PG1 forms a reaction element, which is arranged as a fixed gear on a radially inner hollow shaft 35. This shaft is connected to the auxiliary drive EM2 via a secondary drive reduction gear 37. The secondary drive reduction gear 37 consists of a fixed gear 39 arranged non-rotatably on the rotor shaft of the auxiliary drive EM2 and a meshing fixed gear 41 arranged on the radially inner hollow shaft 35.

[0027] During train operation, both the main drive EM1 and the auxiliary drive EM2 continuously generate a drive torque. Depending on the driving situation, the drive torque generated by the auxiliary drive EM2 can be varied to ensure that the two flange shafts 17 and 18 are subjected to a uniform torque distribution, or a torque difference between the two flange shafts 17 and 18 can be generated.

[0028] During train operation, a load path L coming from the main gearbox EM1 ( Fig. 1) at node K, the load is split into a partial load path L1 leading via the drive gear 15 to the first flange shaft 17 and a partial load path L2 leading via the superimposed gear 20 to the second flange shaft 18. The drive torque flowing in the second partial load path L2 is supported against the sun gear 19 of the input-side planetary gear PG2, which acts as a reaction element and is connected to the auxiliary drive EM2.

[0029] In the Fig. 2 shows the transmission structure of a vehicle axle according to a second embodiment, which is essentially identical to that shown in the Fig. The gearbox structure shown in section 1 is shown. Therefore, reference is made to the preliminary description. In the Fig. 2. Each of the flange shafts 17, 18 is assigned a multi-disc brake 45 as a wheel brake. Vehicle braking can be carried out by means of the multi-disc brakes 45.

[0030] In the Fig. Figure 3 shows the gearbox structure of a third embodiment. Its basic design and function also largely correspond to that shown in the Fig. The first embodiment shown in 1, so reference is made to its description. In contrast to the first embodiment, in the Fig. 2. The transmission structure of the vehicle axle is designed such that, in vehicle-train operation, the main drive EM1 operates in motor mode and the auxiliary drive EM2 operates in generator mode: In the transmission structure of the Fig. 3. The planet carrier 23 of the input-side planetary gear PG1 is connected to a radially outer hollow shaft 43, which is rotationally fixed to the output gear 15 of the first flange shaft 17 by forming the coupling point K. Therefore, the planet carrier 23 of the input-side planetary gear PG1, or the radially outer hollow shaft 43, forms an input element via which the partial load path L2 (only in the Fig. 1 shown) is introduced into the superimposed gear 20.

[0031] In the output-side planetary gear set PG2, the common ring gear shaft 31 forms an output element, which is rotationally fixed to the second input shaft 18 via the output flange 31. Furthermore, in the output-side planetary gear set PG2, the sun gear 25 forms a reaction element, which, as a fixed gear on the radially inner hollow shaft 35, is drivenly connected to the auxiliary drive reduction gear 37. The sun gear 19 of the input-side planetary gear set PG1 is connected to the planet carrier 29 of the output-side planetary gear set PG2 via the coupling flange 33.

[0032] In the Fig. 4 shows the transmission structure of a vehicle axle according to a fourth embodiment, which is essentially identical to that shown in the Fig. The gearbox structure shown in section 1 is shown. Therefore, reference is made to the preliminary description. In the Fig.Each of the flange shafts 17, 18 is assigned a multi-disc brake 45 as a wheel brake. Vehicle braking can be carried out using the multi-disc brakes 45. REFERENCE MARK LIST: 1 Main drive reduction gear 3 torque distribution unit 4 first translation stage 5 Power output shaft 7 Fixed gear 9 Intermediate shaft 11 Input gear 12 second translation stage 13 Output gear 15 Output gear 17 first flange shaft 18 second flange shaft 19 Sun wheel 20 superimposed gear units 21 Ring gear 23 planetary gear carriers 25 sun wheel 27 Ring gear 29 planetary gear carriers 31 common ring gear shaft 32 Drive flange 33 Coupling flange 35 radial inner hollow shaft 37 Auxiliary drive reduction gear 39 Fixed gear 41 Fixed gear 43 radial outer hollow shaft PG1 input-side planetary gear PG2 output-side planetary gearbox K coupling point EM1 main drive EM2 auxiliary drive QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 8 425 375 B2

[0004] DE 10 2008 061 945 A1

[0005] DE 10 2018 101 980 A1

[0006] DE 10 2021 006 011 A1

[0006] DE 10 2022 000 543 A1

[0006]

Claims

[1] Vehicle axle for a two-track vehicle, with a main drive (EM1) which, in train operation, drives via an axle differential-free torque distribution unit (3) to the two first and second flange shafts (17, 18) of the vehicle axle (HA) leading to the vehicle wheels, wherein the torque distribution unit (3) has an output gear (15) arranged non-rotatably on the first flange shaft (17), characterized by , that the torque distribution unit (3) also has a superimposed transmission (20) with at least one planetary gear (PG1, PG2), the input element (31; 43) of which is non-rotatably connected at a node (K) to the output gear (15) of the first flange shaft (17), the output element (29; 31) of which is non-rotatably connected to the second flange shaft (18), and the reaction element (19; 25) of which is drivenly connected to an auxiliary drive (EM2). [2] Vehicle axle according to claim 1, characterized by, that a load path (L) coming from the main drive (EM1) is split at the node (K) into a partial load path (L1) leading via the drive gear (15) to the first flange shaft (17) and into a partial load path (L2) leading via the superimposed gear (20) to the second flange shaft (18), and that in particular the drive torque flowing in the second partial load path (L2) is supported on the reaction element (19; 25) which is connected to the auxiliary drive (EM2) in a drive direction. [3] Vehicle axle according to claim 1 or 2, characterized by, that in train operation both the main drive (EM1) and the auxiliary drive (EM2) permanently generate a drive torque, and / or that depending on the driving situation, by varying the drive torque generated by the auxiliary drive (EM2), the torque distribution unit (3) either applies a uniform torque distribution to the two flange shafts (17, 18), or the torque distribution unit (3) generates a torque difference between the two flange shafts (17, 18). [4] Vehicle axle according to one of the preceding claims, characterized by , that the superimposed gear (20) is arranged in a space-saving manner in the axial direction in a space between the output gear (15) and the auxiliary drive (EM2). [5] Vehicle axle according to one of the preceding claims, characterized by, that the superimposed transmission (20) has two coupled planetary gear sets (PG1, PG2) which are arranged axially next to each other and coaxially to the flange shafts (17, 18), and that in particular of the two planetary gear sets (PG1, PG2) an input-side planetary gear set (PG1) with the input element (31; 43) is connected non-rotatably to the output gear (15) forming the node (K), and an output-side planetary gear set (29; 31) is connected non-rotatably to the second drive shaft (18). [6] Vehicle axle according to one of the preceding claims, characterized by , that of the two flange shafts (17, 18) the first flange shaft (17) is arranged far from the gearbox, i.e. with axial distance to the superimposed gearbox (20), and the second flange shaft (18) is arranged close to the gearbox, i.e. extends coaxially through the superimposed gearbox (20). [7] Vehicle axle according to one of the preceding claims, characterized by, that both the main drive (EM1) and the auxiliary drive (EM2) operate in motor mode during train operation, which is achievable with the following gearbox structure, according to which - the input-side planetary gear (PG1) has a ring gear or a ring gear shaft (31) as its input element, - the input-side planetary gear (PG1) has a sun gear (19) as a reaction element, which is arranged as a fixed gear on a radially inner hollow shaft (35) which is connected to the auxiliary drive (EM2) via a secondary drive reduction gear (37); - the output-side planetary gear (PG2) has as its output element a planet carrier (29) which is connected to the second flange shaft (18) in a rotationally fixed manner via a drive flange (32); - the planet carrier (23) of the input-side planetary gear (PG1) is connected to the sun gear (25) of the output-side planetary gear (PG2) via a coupling flange (33); and / or - the ring gear (21) of the input-side planetary gear (PG1) and the ring gear (27) of the output-side planetary gear (PG2) are formed on a common ring gear shaft (31), which is connected to the output gear (15) in a rotationally fixed manner by forming the coupling point (K). [8] Vehicle axle according to any one of claims 1 to 6, characterized by , that in train operation the main drive (EM1) operates in motor mode and the auxiliary drive (EM2) in generator mode, which can be realized with the following gearbox structure, according to which - the input-side planetary gear (PG1) has a planet gear carrier (23) as its input element, - the output planetary gear (PG2) has as its output element a ring gear shaft (31) on which the ring gears (21, 27) of the two planetary gears (PG1, PG2) are formed, wherein the ring gear shaft (31) is connected to the second drive shaft (18) in a rotationally fixed manner via an output flange (32); - the output-side planetary gear (PG2) has a sun gear (25) as a reaction element, which is arranged as a fixed gear on a radially inner hollow shaft (35) which is connected to the auxiliary drive (EM2) via an auxiliary drive reduction gear (37); and / or -the sun gear (19) of the input-side planetary gear (PG1) is connected to the planet carrier (29) of the output-side planetary gear (PG2) via a coupling flange (33). [9] Vehicle axle according to any one of the preceding claims, characterized by, that the main drive (EM2) is rigidly connected to the output gear (15) via a main drive reduction gear (1), and that in particular the reduction gear (1) has a spur gear stage, in particular a double spur gear stage, in which a fixed gear (7) arranged on the power output shaft (5) of the main drive (EM1) meshes in a first transmission stage (4) with an input gear (11) arranged non-rotatably on an intermediate shaft (9), and in a second transmission stage (12) an output gear (13) arranged non-rotatably on the intermediate shaft (9) meshes with the output gear (15) of the first flange shaft (17). [10] Vehicle according to any one of the preceding claims, characterized by , that each of the flange shafts (17, 18) has a multi-disc brake (45) as a wheel brake, and that vehicle braking can be carried out by means of the multi-disc brakes (45).

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