Vehicle axle for a two-track hybrid vehicle and method for operating a vehicle axle

Abstract

Vehicle axle for a two-track hybrid vehicle, comprising a drive unit with an internal combustion engine (1), a gearshift (3), an electric motor (5), and an axle differential (7) for compensating between the axle shafts (11) leading to the vehicle wheels (9), wherein in a torque flow direction (M) of an internal combustion engine drive torque, the internal combustion engine (1) is directly connected to the gearshift (3), i.e., without the intermediate electric motor (5), wherein the electric motor (5) is arranged downstream of the gearshift (3) in the torque flow direction (M), and wherein, to provide a stationary charging operation, one of the axle shafts (11) is divided into an axle-side shaft section (21) and a wheel-side shaft section (23), which can be coupled via a disconnect clutch (25), characterized in thatthat the electric motor (5) is arranged in series between the gearbox (3) and the axle differential (7) in the torque flow direction (M), and that the electric motor (5) is directly connected to the axle differential (7) without an intermediate disconnect clutch (25).

Description

The invention relates to a vehicle axle for a two-track hybrid vehicle according to the preamble of claim 1 and according to claim 4 to a vehicle axle for a two-track hybrid vehicle and according to claim 9 to a method for operating a vehicle axle according to claim 1 or 4.Such a vehicle axle has a drive unit with an internal combustion engine, an electric machine, a gear shift transmission and an axle differential for a compensating action between the axle shafts leading to the vehicle wheels.Usually, the internal combustion engine, the electric machine and the gear shift transmission are positioned in series in the torque flow direction of an internal combustion engine drive torque as follows: The internal combustion engine is directly drive-connected to the electric machine. This is drivingly connected to the axle differential via the gear shift transmission. In this case, the electric machine is therefore positioned in front of the gear shift transmission in the torque flow direction. In this vehicle axle, a parking mode can be implemented as follows: Thus, the gear shift transmission is shifted to a non-torque-transmitting neutral stage, in which the drive connection between the electric machine and the axle shafts leading to the vehicle wheels is decoupled. In addition, the internal combustion engine generates a parking load torque with which the electric machine can be driven.In contrast to the vehicle axle outlined above, an exemplary vehicle axle has the following structure from structural conditions: the gear shift transmission is thus arranged not upstream of, but rather downstream of, the gear shift transmission in the torque flow direction. In addition, in the vehicle axle of the generic type, the internal combustion engine is directly drivingly connected to the gear shift transmission in the torque flow direction, that is to say without the intermediate connection of the electric machine.In the exemplary vehicle axle, no parking mode can be realized for the following reason: in order to enable a vehicle standstill, the gear shift transmission must be shifted into an idling stage. In the idling stage, however, there is no drive connection between the internal combustion engine and the electric machine, so that no parking load torque can be transmitted either.A hybrid vehicle is known from DE 10 2013 204 506 A1. WO 2012 / 146 416 A1 discloses a drive unit for a hybrid vehicle. DE 10 2018 204 570 A1 discloses a vehicle axle of the generic type. JP 2011-161 939 A discloses a power transmission device for hybrid vehicles. DE 11 2016 004 789 T5 discloses a power transmission device for a vehicle and a power transmission system for a vehicle. DE 22 58 707 A discloses a motor vehicle with a hybrid drive.The object of the invention is to provide a vehicle axle in which a parking mode can be realized in a structurally simple manner.The object is achieved by the features of the independent claims. Preferred developments of the invention are disclosed in the dependent claims.The invention relates to a vehicle axle in which the internal combustion engine is drive-connected to the gear shift transmission directly in the torque flow direction, i.e. without the intermediate connection of the electric machine. In addition, the electric machine is arranged after the gear shift transmission in the torque flow direction. According to claim 1, in order to provide the parking mode in the vehicle standstill, one of the axle shafts is divided into a wheel-side shaft section and an axle-side shaft section. The two shaft sections can be coupled to one another via a separating clutch.According to the invention, the parking mode is implemented as follows: Thus, in the parking mode, the separating clutch is opened, so that the differential between the two axle shafts is deactivated in its compensating action. Accordingly, the axle shafts are drive-decoupled from the drive unit. In addition, the gear shift transmission is shifted into a torque-transmitting drive stage in order to establish a drive connection between the internal combustion engine and the electric machine, so that a parking load torque can be transmitted from the internal combustion engine to the electric machine.According to a first embodiment of the invention, the electric machine is arranged in series between the gear shift transmission and the axle differential in the torque flow direction. According to the first embodiment of the invention, the electric machine is directly, i.e. without an interposed separating clutch, drivingly connected to the axle differential, preferably to a connection (for example an input-side gearwheel) of the axle differential. In the parking mode, a load path is therefore formed in which a parking torque is conducted from the internal combustion engine to the electric machine via the torque-transmittingly shifted gear shift transmission.According to a second embodiment according to the invention, viewed in the torque flow direction, the gear shift transmission is directly, i.e. without an interposed electric machine, drivingly connected to the axle differential, namely in particular at a first connection of the axle differential, i.e. an input-side gear wheel which is formed on the differential housing of the axle differential.The electric machine can be drivingly connected to a second port of the axle differential separately from the gear shift transmission. The axle shafts leading to the vehicle wheels may be drivingly connected to third and fourth ports of the axle differential. In this embodiment, the axle differential with its first to fourth ports may be formed in the manner of a conventional four-wheel differential.A preferred embodiment variant of the vehicle axle for package reasons is described below: accordingly, the internal combustion engine and the gear shift transmission can be positioned in front of the axle shafts in the transverse installation and in the direction of travel. In contrast, the electric machine according to the second embodiment of the invention is positioned behind the axle shafts in the direction of travel. The electric machine is preferably installed in the drive unit not in the transverse installation, but in the longitudinal installation with the electric machine shaft aligned in the longitudinal direction of the vehicle.In the electric machine installed in longitudinal installation, according to the second embodiment of the invention, the differential connection is implemented in a structurally simple manner via an angle drive.According to the second embodiment according to the invention, the axle differential installed in the vehicle axle has a differential housing with differential gears and axle gears meshing therewith, which are seated on the axle shafts. Preferably, the differential gears and the axle gears interacting therewith are arranged in the differential housing, which are seated on the axle shafts. According to the second embodiment according to the invention, the differential housing has, preferably on the outside, an input-side gearwheel which can be brought into driving connection with the electric machine or with the gear shift transmission.According to the second embodiment of the invention, the differential housing, and preferably in the case of an embodiment of the axle differential as an all-wheel differential, additionally has a differential toothing with respect to the input-side gearwheel, which differential toothing forms the angle drive together with a bevel gear mounted on the electric machine shaft.Two exemplary embodiments of the invention are described below with reference to the attached figures.The following are shown: FIG. 1 shows a vehicle axle with a drive unit according to the first exemplary embodiment; FIG. 2 shows a vehicle axle with a drive unit according to a second exemplary embodiment; and FIG. 3 shows a detailed view of the transmission structure of an axle differential used in FIG. 2.Referring to FIG. 1, there is shown a vehicle axle for a two-lane hybrid vehicle according to a first embodiment. The vehicle axle includes a prime mover that is constructed of an internal combustion engine 1, a gear shift transmission 3 (for example, a dual clutch transmission or an automatic transmission), an electric machine 5, and an axle differential 7. The axle differential 7 compensates for the rotational speed between the axle shafts 11 leading to the vehicle wheels 9.In FIG. 1, the internal combustion engine 1, the gear shift transmission 3 and the electric machine 5 are positioned behind the axle shafts 11 in longitudinal installation and in the direction of travel FR.The axle differential 7 is realized in FIG. 1 as a bevel gear differential with a differential housing 13. In its housing interior, two mutually coaxially spaced, opposite differential bevel gears 15 are rotatably mounted. In addition, two axle shaft bevel gears 17 which are coaxially opposite one another at a distance are arranged in the differential housing 13. These are positioned at right angles to the differential gears 15 and in toothed engagement with the two differential gears 15. Each of the two axle bevel gears 17 is seated on an axle shaft 11 which is guided on a hub section 19 of the differential housing 13 outwards towards the vehicle wheel 9.In FIG. 1, one of the two axle shafts 11 is divided into a wheel-side shaft section 21 and an axle-side shaft section 23, and the two shaft sections 21, 23 can be coupled to one another via a separating clutch 25. The separating clutch 25 has a clutch body 26 on each shaft section 21, 23. The two clutch bodies 26 can be coupled to one another or decoupled from one another by means of an adjustable shift sleeve 27. The shift sleeve 27 can be actuated by an actuator 29. In FIG. 1, this is operatively connected to the shift sleeve 27 with the interposition of a two-armed lever arm.In FIG. 1, in a torque flow direction M of an internal combustion engine drive torque, the internal combustion engine 1 is directly, i.e. without the intermediate connection of the electric machine 5, drivingly connected to the gear shift transmission 3. In FIG. 1, the electric machine 5 is arranged in series connection between the gear shift transmission 3 and the axle differential 7 in the torque flow direction M. Both the internal combustion engine 1 and the gear shift transmission 3 and the electric machine 5 are positioned in longitudinal installation. In addition, the electric machine 5 is drivingly connected to the axle differential 7 by way of an angle drive 33 with its electric machine shaft 31 oriented in the vehicle longitudinal direction x. In FIG. 1, the angle drive 33 is realized by a bevel gear 35 seated on the electric machine shaft 31 and an input-side gearwheel 36 meshing therewith, which is formed on the outside on the differential housing 13 of the axle differential 7.In FIG. 1, the actuator 29 is switched to the zero current state. In this case, the separating clutch 25 is in the closed state, in which the shift sleeve 27 is prestressed into the closed position by a prestressing spring 39.For a parking mode, actuator 29 is activated to open disconnect clutch 25. In this way, the balancing action of the axle differential 7 is deactivated and the axle shafts 11 are driveally decoupled from the drive unit. In addition, the gear shift transmission 3 is shifted into a torque-transmitting drive stage in order to establish a drive connection between the internal combustion engine 1 and the electric machine 5, so that a parking torque can be transmitted from the internal combustion engine via the transmission to the electric machine 5.FIG. 2 shows the vehicle axle according to a second exemplary embodiment. Consequently, the internal combustion engine 1 and the gear shift transmission 3 are no longer positioned in longitudinal installation but in transverse installation and are arranged in front of the axle shafts 11 in the direction of travel FR.In contrast, the electric machine 5 is positioned behind the axle shafts 11 in the direction of travel FR. In contrast to the gear shift transmission 3 and to the internal combustion engine 1, the electric machine 5 is not installed in transverse installation, but in longitudinal installation in the vehicle axle. Accordingly, the electric machine shaft 31 is oriented in the vehicle longitudinal direction x.In contrast to FIG. 1, in FIG. 2 the axle differential 7 is realized in the manner of an all-wheel differential with a total of four connections 41, 43, 45. The gear shift transmission 3 is drivingly connected to a first connection 41 of the axle differential 7. At a second connection 43 of the axle differential 7, separately from the gear shift transmission 3, the electric machine 5 is drivingly connected. At a third connection 45 and a fourth connection, the two axle shafts 11 leading to the vehicle wheels 9 are drivingly connected.Analogously to the first exemplary embodiment, in FIG. 2 as well, one of the two axle shafts 11 is formed in two parts with an axle-side shaft section 21 and a wheel-side shaft section 23, which can be coupled to one another or decoupled from one another via a separating clutch 25.The parking mode takes place as described with reference to FIG. 1.FIG. 3 shows, by way of example, a transmission structure of the all-wheel differential 7 installed in FIG. 2. As in FIG. 1, the all-wheel differential 7 is realized as a bevel gear differential in which, in addition to the input-side gearwheel 36, a differential toothing 49 is formed on the differential housing 13. The differential toothing 49 forms the angle drive 33 together with a bevel gear 35 seated on the electric machine shaft 31.LIST OF REFERENCE CHARACTERS:1 Internal combustion engine 3 gear shift transmission 5 electric machine 7 axle differential 9 vehicle wheels 11 axle shafts 13 differential housing 15 differential wheels 17 axle wheels 19 hub section 21 axle-side shaft section 23 wheel-side shaft section 25 separating clutch 27 shift sleeve 29 actuator 31 electric machine shaft 33 angle drive 35 bevel gear 36 input-side gearwheel 37 differential gearing 39 preload spring 41 first differential connection 43 second differential connection 45 third differential connection 49 differential gearing FR direction of travel M torque flow direction

Claims

Vehicle axle for a two-track hybrid vehicle, which has a drive assembly with an internal combustion engine (1), a gear shift transmission (3), an electric machine (5) and an axle differential (7) for a balancing effect between the axle shafts (11) leading to the vehicle wheels (9), wherein, in a torque flow direction (M) of an internal combustion engine drive torque, the internal combustion engine (1) is directly, i.e. without the intermediate connection of the electric machine (5), drivingly connected to the gear shift transmission (3), wherein the electric machine (5) is arranged after the gear shift transmission (3) in the torque flow direction (M), and wherein, in order to provide a parking mode, one of the axle shafts (11) is divided into an axle-side shaft section (21) and a wheel-side shaft section (23), which can be coupled via a separating clutch (25), characterized in that, the electric machine (5) being arranged in series connection between the gear shift transmission (3) and the axle differential (7) in the torque flow direction (M), and the electric machine (5) being connected in driving fashion to the axle differential (7) directly, that is to say without the intermediate separating clutch (25).Vehicle axle according to Claim 1, characterized in that, in the parking mode, the separating clutch (25) is opened, with the result that the axle shafts (11) are drive-decoupled from the drive unit, and the gear shift transmission (3) is shifted into a torque-transmitting drive stage in order to produce a drive connection between the internal combustion engine (1) and the electric machine (5).Vehicle axle according to Claim 1 or 2, characterized in that, in the parking mode, a load path is formed in which the internal combustion engine torque is conducted to the electric machine (5) via the torque-transmittingly shifted gearshift transmission (3).Vehicle axle for a two-track hybrid vehicle, which has a drive assembly with an internal combustion engine (1), a gear shift transmission (3), an electric machine (5) and an axle differential (7) for a balancing effect between the axle shafts (11) leading to the vehicle wheels (9), wherein, in a torque flow direction (M) of an internal combustion engine drive torque, the internal combustion engine (1) is directly, i.e. without the intermediate connection of the electric machine (5), connected in a driving manner to the gear shift transmission (3), wherein the electric machine (5) is arranged after the gear shift transmission (3) in the torque flow direction (M), wherein, in order to provide a parking mode, one of the axle shafts (11) is divided into an axle-side shaft section (21) and a wheel-side shaft section (23), which can be coupled via a separating clutch (25), wherein, in the torque flow direction (M), the gear shift transmission (3) is directly, i.e. without the intermediate connection of the electric machine (5), drivingly connected to the axle differential (7), wherein the axle differential (7) has a differential housing (13) with differential gears (15) and axle gears (17) which mesh therewith and are seated on the axle shafts (11), and wherein the differential housing (13) has an input-side gear (36) which is drivingly connected to the electric machine (5) or to the gear shift transmission (3), wherein the electric machine (5) is positioned behind the axle shafts (11) in the direction of travel (FR), and / or the electric machine (5) is installed in the drive unit in longitudinal installation with the electric machine shaft (31) oriented in the vehicle longitudinal direction (x), and the electric machine (5) is drive-connected to the axle differential (7) via an angle drive (33), and wherein the differential housing (13) has, in addition to the input-side gearwheel (36), a differential toothing (49) which forms the angle drive (33) together with a bevel gear (35) seated on the electric machine shaft (31).Vehicle axle according to Claim 4, characterized in that the electric machine (5), separately from the gear shift transmission (3), is drivingly connected to a second connection (43) of the axle differential (7).Vehicle axle according to Claim 5, characterized in that the axle shafts (11) leading to the vehicle wheels (9) are drivingly connected to third and fourth connections (45, 47) of the axle differential (7).Vehicle axle according to Claim 6, characterized in that the axle differential (7) with its first to fourth connections (41, 43, 45, 47) is designed in the manner of an all-wheel differential.Vehicle axle according to one of the preceding claims, characterized in that the internal combustion engine (1) and the gear shift transmission (3) are positioned in front of the axle shafts (11) in the transverse installation and in the direction of travel (FR).Method for operating a vehicle axle according to one of the preceding claims.

Images