Drive system for a hybrid motor vehicle, with two electric motors and a longitudinally mounted internal combustion engine; and motor vehicle

Abstract

Drive system (1) for a hybrid motor vehicle (2), wherein the drive system (1) comprises: an internal combustion engine (3), a first electric machine (6) permanently coupled rotationally to an output shaft (5) of the internal combustion engine (3) on the side of its rotor shaft (4) and arranged coaxially to the output shaft (5), a second electric machine (9) arranged with its rotor shaft (7) coaxially to the output shaft (5), which can be decoupled from the first electric machine (6) via a coupling (8), and at least one differential gear (12, 13) having two outputs (10a, 10b; 11a, 11b), wherein the rotor shaft (7) of the second electric machine (9) is permanently connected via a fixed gear stage (16) designed as a planetary gear stage to an input (14, 15) of the at least one differential gear (12, 13), wherein a ring gear (35) of the fixed gear stage (16) with a connecting shaft (36) which can be coupled via the clutch (8) to the rotor shaft (4) of the first electric machine (6) and / or is permanently rotationally coupled to the input (14, 15) of the at least one differential gear (12, 13), characterized in that the ring gear (35) of the fixed gear stage (16) is connected via at least one gear stage (17) to an input (15) of a second differential gear (13).

Description

[0001] The invention relates to a drive system for a hybrid motor vehicle, such as a car, truck, bus, or other commercial vehicle, comprising an internal combustion engine, a first electric motor whose rotor shaft is permanently rotationally coupled to an output shaft of the internal combustion engine and arranged coaxially to this output shaft, a second electric motor whose rotor shaft is also arranged coaxially to the output shaft and can be decoupled from the first electric motor via a clutch, and at least one differential gear having two outputs. Furthermore, the invention relates to a motor vehicle with this drive system.

[0002] Drive systems are already well known in the art. For example, WO 2007 / 004356 A1 discloses a drive device for hybrid vehicles with two electric motors. Further prior art is disclosed in DE 10 2017 127 695 A1, DE 10 2018 103 245 A1, and US 2004 / 0 084 233 A1.

[0003] From US 6 886 648 B1 a drive system according to the preamble of claim 1 is known.

[0004] For further prior art, reference is made to US 2008 / 0 318 720 A1 and DE 11 2006 001 432 B4. Relevant hybrid drive devices are also known from DE 10 2016 100 788 A1 and CN 101 380 887 A.

[0005] However, one disadvantage of the drive systems known from the state of the art is that they are often relatively large and complex in design. In particular, additional complex manual transmissions, such as automatic transmissions, are often used, which, in addition to taking up additional installation space, also adversely impact the manufacturing and assembly costs of the drive system.

[0006] It is therefore an object of the present invention to eliminate the disadvantages known from the prior art and, in particular, to provide an efficiently operating drive system which is as simple and space-saving in its construction as possible.

[0007] This is achieved according to the invention by a generic drive system having the features of claim 1. The rotor shaft of the second electric machine is permanently rotationally coupled / connected to an input of at least one differential gear via a fixed / fixed / unchangeable gear stage.

[0008] This allows the connection between the rotor shaft of the second electric motor and the differential gear to be realized directly, using as few additional components as possible. This results in significant space savings compared to existing designs. Furthermore, it is possible to make at least the second electric motor smaller.

[0009] Since the gear stage is designed as a planetary gear stage, the required installation space is further reduced.

[0010] A ring gear of the gear stage is permanently rotationally coupled to a connecting shaft, which can be coupled to the rotor shaft of the first electric machine via the coupling, and / or to the input of the at least one differential gear.

[0011] Further embodiments according to the invention are claimed in the subclaims and explained in more detail below.

[0012] In order to achieve an optimized gear ratio, it has proven to be useful if a sun gear of the gear stage is connected to the rotor shaft of the second electric machine.

[0013] A planetary carrier of the gear stage is preferably supported fixed to the housing.

[0014] It is also advantageous to use a propeller shaft as a coupling element between the gear stage and the input of a first differential gear. This type of coupling further saves installation space.

[0015] In this regard, it is also expedient if the propeller shaft is connected to the input of the first differential gear via a gear stage. The gear stage is preferably implemented as a bevel gear stage.

[0016] According to the invention, the ring gear of the gear stage, in addition to being coupled to the first differential gear, is connected via at least one gear stage to an input of a second differential gear. The rotor shaft of the second electric motor is also permanently coupled to another differential gear. This allows for a simple implementation of either front-wheel drive, rear-wheel drive, or all-wheel drive.

[0017] In this context, it has also proven advantageous for a compact design if the ring gear is rotationally coupled via a first toothing stage to an intermediate shaft arranged parallel to the rotor shaft of the second electric machine, which intermediate shaft is further connected to the input of the second differential gear.

[0018] It is also advantageous if the intermediate shaft is connected to the input of the second differential gear via a second gear stage. The second gear stage is preferably implemented as a bevel gear stage.

[0019] Furthermore, it has proven advantageous if the output shaft of the internal combustion engine is connected to the rotor shaft of the first electric motor via a torsional vibration damper, preferably implemented as a dual-mass flywheel. This cleverly dampens the internal combustion engine's connection to the rest of the drive train in the respective operating mode.

[0020] Furthermore, the invention relates to a motor vehicle with a drive system according to the invention according to at least one of the previously described embodiments, wherein the output shaft of the internal combustion engine is arranged parallel or coaxially to a longitudinal axis of the motor vehicle.

[0021] In this respect, it is also advantageous if each output of the first differential gear is connected in a rotationally fixed manner to a rear wheel (of the motor vehicle) and / or each output of the second differential gear is connected in a rotationally fixed manner to a front wheel (of the motor vehicle).

[0022] In other words, according to the invention, a simple hybrid transmission with two electric machines for a longitudinally installed internal combustion engine (combustion engine) is implemented.

[0023] The invention will now be explained in more detail below with reference to figures, in which context various embodiments are also shown.

[0024] They show: Fig. 1 a schematic longitudinal sectional view of a drive system according to the invention according to a first embodiment, in which an output shaft of an internal combustion engine and two rotor shafts of two electric machines are arranged coaxially to each other and are coupled to a rear wheel differential via a gear stage and a cardan shaft, and Fig. 2 a schematic longitudinal sectional view of a drive system according to the invention according to a second embodiment, in which the gear stage directly coupled to a rotor shaft of a second electric machine is coupled both to the cardan shaft and, with the interposition of two gear stages, to a second differential gear.

[0025] The figures are merely schematic and serve solely to clarify the invention. The same elements are designated by the same reference numerals.

[0026] With Fig. 1 illustrates the structure of a drive system 1 according to the invention according to a first exemplary embodiment. The drive system 1 is implemented as a hybrid drive system 1 and is therefore preferably used in a hybrid motor vehicle 2, which is Fig. 1 is indicated schematically.

[0027] The drive system 1 has an internal combustion engine 3, for example in the form of a gasoline or diesel engine, which is aligned with its output shaft 5 (crankshaft) along, ie parallel or coaxial with, an imaginary vehicle longitudinal axis 22 / vehicle center axis of the motor vehicle 2.

[0028] The drive system 1 serves in the first embodiment according to Fig. 1, as described in more detail below, for driving two rear wheels 24 of a rear axle of the motor vehicle 2. In further embodiments, as described below in connection with Fig. 2, this drive system 1 is designed alternatively to drive two front wheels 25 of a front axle of the motor vehicle 2 or even as an all-wheel drive, ie to drive all wheels 24, 25 of the motor vehicle 2.

[0029] The output shaft 5 is arranged coaxially with a (first) rotor shaft 4 of a first electric machine 6. The output shaft 5 is permanently rotationally coupled / connected to the first rotor shaft 4. In this embodiment, the output shaft 5 is connected to the first rotor shaft 4 via a torsional vibration damper 21, here in the form of a spring damper (e.g., a dual-mass flywheel).

[0030] The first electric machine 6 is designed such that it can be switched as a generator machine in a first operating mode of the drive system 1. The first electric machine 6 has a (first) stator 26, which is fixedly accommodated in a housing 27. A (first) rotor 28 of the first electric machine 6 is rotatably mounted relative to the first stator 26. The first rotor 28 is connected in a rotationally fixed manner to the first rotor shaft 4. The first rotor shaft 4 is mounted relative to the housing 27 via two bearings 29a, 29b.

[0031] In addition to the first electric machine 6, a second electric machine 9 is present. The second electric machine 9 serves as a prime mover / traction machine in the first operating mode of the drive system 1. The second electric machine 9 also has a (second) stator 30 fixed to the housing and a (second) rotor 31 rotatably mounted relative to the second stator 30. The second rotor 31 is directly connected to a second rotor shaft 7 assigned to the second electric machine 9. In particular, the second rotor shaft 7 rotatably mounts the second rotor 31 directly on a lateral surface of a tube forming the second rotor shaft 7. The second rotor shaft 7 is arranged coaxially to the first rotor shaft 4 and to the output shaft 5. The second rotor shaft 7 is mounted relative to the housing 27 via two further bearings 29c, 29d.

[0032] Furthermore, it can be seen that the second rotor shaft 7 is formed as a hollow shaft and has a connecting shaft 36 axially penetrating it. This connecting shaft 36 is also arranged coaxially to the rotor shafts 4, 7 and the output shaft 5. The connecting shaft 36 can be coupled to or decoupled from the first rotor shaft 4 via a clutch 8, which is preferably implemented as a friction clutch. In a closed position of the clutch 8, the first rotor shaft 4 is consequently connected to the connecting shaft 36 in a rotationally fixed manner; in an open position of the clutch 8, the first rotor shaft 4 and the connecting shaft 36 are decoupled from one another, i.e. can rotate freely relative to one another.It can be seen that the coupling 8 is arranged axially between a flange region 32 of the first rotor shaft 4, on which the first rotor 28 is received, and the second rotor 31 / a casing region 33 of the second rotor shaft 7, on which the second rotor 31 is received. The connecting shaft 36 is mounted relative to the second rotor shaft 7 via a further bearing 29e.

[0033] The connecting shaft 36 is connected via an (optional) intermediate output shaft 41 to a cardan shaft 23, at its end facing away from the first electric motor 6, to an input 14 of the first differential gear 12. Accordingly, the output shaft 5, the first rotor shaft 4, the second rotor shaft 7, and the connecting shaft 36 are arranged coaxially with one another. The output shaft 5, the first rotor shaft 4, and the connecting shaft 36 are arranged in series with one another, while the second rotor shaft 7 radially surrounds the connecting shaft 36 from the outside.

[0034] According to the invention, a fixed gear stage 16 is operatively inserted between the second rotor shaft 7 and the connecting shaft 36, and consequently between the second rotor shaft 7 and the cardan shaft 23. In this embodiment, the gear stage 16 is provided by a planetary gear and is thus alternatively referred to as a fixed planetary gear stage.

[0035] The gear stage 16 has a sun gear 34, which is directly attached to the second rotor shaft 7 in a rotationally fixed manner or is formed by this second rotor shaft 7. Several planetary gears 37 of the gear stage 16, which mesh with the sun gear 34, are received / mounted on a planetary carrier 38 fixed to the housing. A ring gear 35 of the gear stage 16, which in turn meshes with the planetary gears 37, is directly connected to the connecting shaft 36 in a rotationally fixed manner. The gear stage 16 is preferably designed such that a slow gear ratio is transmitted from the second rotor shaft 7 to the connecting shaft 36.

[0036] Furthermore, it can be seen that in this embodiment, the output shaft 41, axially offset from the bearings 29a to 29e, is mounted relative to the housing 27 by two additional bearings 29f, 29g. Thus, in this embodiment, no more than seven bearings are used to support the two rotor shafts 4, 7, the connecting shaft 36, and the output shaft 41.

[0037] In the first exemplary embodiment, the cardan shaft 23 serves to implement the rotary connection of the output shaft 41 / the connecting shaft 36 / the second rotor shaft 7 with the input 14 of the first differential gear 12, wherein the cardan shaft 23 is connected to an end of the output shaft 41 facing away from the first electric machine 6. The cardan shaft 23 is coupled to the input 14 of the first differential gear 12 via a (third) gear stage 19. The input 14 is typically implemented as an input gear. In this embodiment, the input 14 is implemented as a bevel gear, and the third gear stage 19 is thus designed as a bevel gear.

[0038] Two outputs 10a, 10b of the first differential gear 12, each connected to a rear wheel 24 in this first embodiment, are arranged obliquely, namely substantially perpendicularly, to the output shaft 5 and the rotor shafts 4, 7.

[0039] When the clutch 8 is closed, the internal combustion engine 3 drives the motor vehicle 2 directly in a second operating mode (with optional drive support from the second electric machine 9).

[0040] In the second embodiment according to Fig. Figure 2 shows an alternative embodiment of the drive system 1 according to the invention. The basic structure of this second embodiment corresponds to the structure of the first embodiment, which is why, for the sake of brevity, only the differences between these two embodiments are described below.

[0041] With regard to the second embodiment of the Fig. 2 shows that the ring gear 35 simultaneously forms a connection to an intermediate shaft 20, which is further connected to a second differential gear 13. The ring gear 35 accordingly has external teeth 39 that mesh with a toothed section 40 of the intermediate shaft 20. Through the external teeth 39 and the toothed section 40, a first toothing stage 17 (in the form of a spur gear stage) is operatively inserted between the ring gear 35 of the gear stage 16 and the intermediate shaft 20.

[0042] The intermediate shaft 20 is arranged parallel to the rotor shafts 4, 7. The intermediate shaft 20 is connected to an input 15 of the second differential gear 13 via a further second gear stage 18, here in the form of a bevel gear. The input 15 is therefore implemented as a bevel gear. This results in a permanent rotational coupling of the second rotor shaft 7 to the input 15 of the second differential gear 13. The rotary connection of the connecting shaft 36 / second rotor shaft 7 to the input 15 of the second differential gear 13 is thus implemented by the intermediate shaft 20 and the two first and second gear stages 17, 18.

[0043] Thus, with Fig. 2, the connecting shaft 36 / second rotor shaft 7 is coupled to a further second differential gear 13 (front-wheel differential), implementing an all-wheel drive. In this context, it should be noted that in a further embodiment of the drive system 1 according to the invention, only the second differential gear 13 is present, i.e., without the first differential gear 12, implementing a front-wheel drive.

[0044] The two outputs 11a, 11b of the second differential gear 13 are also aligned obliquely, namely essentially perpendicularly, to the rotor shafts 4, 7 and the output shaft 5. In this context, for the sake of completeness, it should be noted that the illustration according to Fig. 2 is to be understood in such a way that the first output 11a of the second differential gear 13 crosses the first rotor shaft 4 below or above the plane of the drawing, so that of course the first rotor shaft 4 is not directly connected to the first output 11a.

[0045] In other words, according to the invention, all machines (comprising internal combustion engine 3, first electric machine 6 and second electric machine 9) are driven directly without variable gear ratios up to the differential 12, 13. Fig. 1 represents the simplest imaginable drive for a transmission with two electric motors 6, 9. In one (first operating mode), the internal combustion engine 3 transmits torque to a generator 6 via a torsional damper 21. When the clutch 8 is open (clutch K0), this first electric machine 6 thus generates electrical energy to charge a battery of the motor vehicle 2 or for the electrical operation / drive of the driving machine (second electric machine 9). When the clutch 8 is open, this second electric machine 9 drives a cardan shaft 23, which transmits the rotational movement to a rear wheel differential 12 and thus drives the vehicle 2. When the clutch 8 is closed (second operating mode), the internal combustion engine 3 can drive the vehicle 2 directly. This occurs without a downstream transmission. The gear ratio of the three motors 3, 6, 9 to the wheel 24 is defined only by the fixed differential ratio.

[0046] Through the drive system 1 of the Fig. 1 shows a configuration allowing the use of a higher-speed second electric machine 9, with a planetary gear set 16 with a fixed gear ratio connected upstream. This can be advantageous for making the second electric machine 9 smaller compared to the prior art while maintaining the same power. In addition to the rotor shafts 4, 7, there is a further rotor shaft (connecting shaft) 36, as well as an output shaft 41 coupled to the connecting shaft 36. Without the planetary bearings considered, no more than seven bearings are present.

[0047] With Fig. 2 is a variant of Fig.1, again with a longitudinal installation of the internal combustion engine 3, but with front-wheel drive, whereby an all-wheel drive is optionally implemented by retaining the propshaft 23 and the rear-wheel differential 12. For front-wheel drive, the torque is transmitted to a further shaft (intermediate shaft 20) on the differential 13 via a (fixed) gear ratio. It is advantageous to design the gear ratio (via the first and second gear stages 17, 18) with a gear ratio i=1, although this is not absolutely necessary. When providing an all-wheel drive, the gear ratio must always be selected so that the output speeds of both differentials 12, 13 are the same. List of reference symbols 1 drive system 2 motor vehicles 3 Internal combustion engine 4 first rotor shaft 5 Output shaft 6 first electric machine 7 second rotor shaft 8 Clutch 9 second electric machine 10a first output of the first differential gear 10b second output of the first differential gear 11a first output of the second differential gear 11b second output of the second differential gear 12 first differential gear 13 second differential gear 14 Input of the first differential gear 15 Input of the second differential gear 16 gear stages 17 first gearing stage 18 second gearing stage 19 third gearing stage 20 Intermediate shaft 21 torsional vibration dampers 22 Vehicle longitudinal axis 23 Cardan shaft 24 rear wheel 25 front wheel 26 first stator 27 housings 28 first rotor 29a first camp 29b second camp 29c third camp 29d fourth camp 29th fifth camp 29f sixth camp 29g seventh bearing 30 second stator 31 second rotor 32 Flange area of ​​the first rotor shaft 33 Shell area of ​​the second rotor shaft 34 Sun gear of the gear stage / second gear stage 35 Ring gear of the gear stage / second gear stage 36 Connecting shaft 37 Planetary gear of the gear stage / second gear stage 38 Planet carrier of the gear stage / second gear stage 39 External gearing 40 Gear section 41 Output shaft

Claims

[1] Drive system (1) for a hybrid motor vehicle (2), the drive system (1) comprising: an internal combustion engine (3), a first electrical machine (6) which is permanently rotationally coupled to an output shaft (5) of the internal combustion engine (3) by its rotor shaft (4) and arranged coaxially to the output shaft (5), a second electric machine (9) arranged with its rotor shaft (7) coaxial with the output shaft (5) and decoupleable from the first electric machine (6) via a coupling (8), and at least one differential gear (12, 13) having two outputs (10a, 10b; 11a, 11b), wherein the rotor shaft (7) of the second electric machine (9) is permanently connected to an input (14, 15) of the at least one differential gear (12, 13) via a fixed gear stage (16) designed as a planetary gear stage, wherein a ring gear (35) of the fixed gear stage (16) with a connecting shaft (36) which can be coupled via the coupling (8) to the rotor shaft (4) of the first electric machine (6) and / or is permanently rotationally coupled to the input (14, 15) of the at least one differential gear (12, 13), characterized by that the ring gear (35) of the fixed gear stage (16) is connected via at least one toothing stage (17) to an input (15) of a second differential gear (13). [2] Drive system (1) according to claim 1, characterized by that a sun gear (34) of the fixed gear stage (16) is connected to the rotor shaft (7) of the second electrical machine (9). [3] Drive system (1) according to claim 1 or 2, characterized by that a cardan shaft (23) is used as a coupling element between the fixed gear stage (16) and the input (14) of a first differential gear (12). [4] Drive system (1) according to one of claims 1 to 3, characterized by that the output shaft (5) of the internal combustion engine (3) is connected to the rotor shaft (4) of the first electrical machine (6) via a torsional vibration damper (21). [5] Motor vehicle (2) with a drive system (1) according to one of claims 1 to 4, wherein the output shaft (5) of the internal combustion engine (3) is arranged parallel or coaxially to a longitudinal axis (22) of the motor vehicle (2). [6] Motor vehicle (2) according to claim 5, characterized by that each output (10a, 10b) of the first differential gear (12) is connected in a rotationally fixed manner to a rear wheel (24). [7] Motor vehicle (1) according to claim 5 or 6, characterized by that each output (11a, 11b) of the second differential gear (13) is connected in a rotationally fixed manner to a front wheel (25).

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