Hybrid drive system of a motor vehicle with axial flux machine

Abstract

The present invention relates to a hybrid drive system (1) of a motor vehicle. The hybrid drive system (1) comprises an internal combustion engine (10) and a transmission (20), wherein the internal combustion engine (10) has an output shaft (11) and the transmission (20) has an input shaft (21), wherein the hybrid drive system (1) comprises an axial flux machine (30), wherein the axial flux machine (30) has a stator (34) and a rotor (31) rotatable relative to the stator with at least one rotor disk, wherein the hybrid drive system (1) comprises a dual-mass flywheel (70), wherein the output shaft (11) of the internal combustion engine (10) is rotationally fixedly coupled to a first flywheel of the dual-mass flywheel (70), wherein the rotor (31) of the axial flux machine (30) is rotationally fixedly coupled to a second flywheel of the dual-mass flywheel (70), and wherein the input shaft (21) of the transmission (20) is connected to the rotor (31) of the axial flux machine (30). is coupled in a rotationally fixed manner.

Description

[0001] The present invention relates to a hybrid drive system of a motor vehicle with an axial flux machine.

[0002] In order to reduce the emission behavior of motor vehicles and / or to create particularly high-performance motor vehicles, motor vehicles are nowadays often equipped with a hybrid drive system that has both an internal combustion engine, i.e. a combustion engine drive unit, and an electric motor drive unit, i.e. an electric motor.

[0003] It is generally known that axial flux machines are used as electric drive units in hybrid vehicles. An axial flux machine is a dynamo-electric machine in which the magnetic flux between the rotor and stator runs parallel to the rotor's axis of rotation. Often, both the stator and rotor are largely disc-shaped.

[0004] DE 10 2022 114 472 A1 discloses a motor vehicle with an axial flux engine. EP 3 493 372 B1 and EP 1 860 759 A2 disclose further prior art.

[0005] Particularly in motor vehicles with a longitudinally mounted internal combustion engine, i.e., an installation of the internal combustion engine such that an output shaft, for example a crankshaft, points in the longitudinal direction of the motor vehicle, and with a longitudinally mounted transmission, it is particularly advantageous to keep the axial expansion of other components coupled to the output shaft and / or the transmission input shaft as small as possible.

[0006] The object of the present invention is to create a novel hybrid drive system characterized by a particularly small installation space.

[0007] This problem is solved by the object that has the features of claim 1. The dependent claims relate to advantageous further developments.

[0008] The hybrid drive system according to the invention is a hybrid drive system for a motor vehicle, in particular for a passenger car, and especially preferably for a sports car. The hybrid drive system comprises an internal combustion engine and a transmission, wherein the internal combustion engine has an output shaft and the transmission has an input shaft, wherein the hybrid drive system comprises an axial flux machine, wherein the axial flux machine has a stator and a rotor rotatable relative to the stator with at least one rotor disk, wherein the hybrid drive system comprises a dual-mass flywheel, wherein the output shaft of the internal combustion engine is rotationally fixed to a first flywheel of the dual-mass flywheel, wherein the rotor of the axial flux machine is rotationally fixed to a second flywheel of the dual-mass flywheel, and wherein the input shaft of the transmission is rotationally fixed to the rotor of the axial flux machine.

[0009] The design of the drive system according to the invention only slightly increases the space requirement of the drive system compared to a purely internal combustion engine drive system, since an axial flux machine is characterized by a particularly short axial length. Furthermore, an axial flux machine exhibits a comparatively high torque density. In particular, compared to a radial flux machine with comparable torque, an axial flux machine is distinguished by its smaller installation space in the axial direction. Therefore, a more powerful hybrid drive system can be created with an axial flux machine within a given or limited installation space in the axial direction.

[0010] The rotationally fixed coupling of the rotor to the dual-mass flywheel is advantageous in that torsional vibrations of the combustion engine's output shaft are not transmitted to the rotor, or are only weakened. This reduces the forces that the rotor bearings must absorb, which has a beneficial effect on the design and service life of the axial flux machine.

[0011] It is considered particularly advantageous if the internal combustion engine is a longitudinally mounted internal combustion engine, i.e., an internal combustion engine whose output shaft is aligned in the longitudinal direction of the motor vehicle.

[0012] In particular, the internal combustion engine is either a mid-mounted engine or a rear-mounted engine.

[0013] In a particularly preferred embodiment, the rotor is coupled to the output shaft of the internal combustion engine without a coupling and / or to the input shaft of the transmission without a coupling. This reduces the installation space required compared to a design with a coupling.

[0014] It is considered particularly advantageous if an output shaft rotation axis of the output shaft, an input shaft rotation axis of the input shaft and a rotor rotation axis of the rotor are designed coaxially to each other.

[0015] It is considered particularly advantageous if the rotor is connected to the second flywheel via a splined connection and / or if the rotor is connected to the transmission input shaft via a splined connection. Such a design allows for particularly good and reliable torque transmission and enables easy assembly of the hybrid drive system, especially simple coupling between the dual-mass flywheel and the rotor, or between the rotor and the transmission input shaft.

[0016] Given the need for a particularly small installation space in the axial direction, it is considered advantageous for the axial flux machine to have exactly one stator disk and exactly one rotor disk. Conventional axial flux machines typically have two stator disks and a rotor disk positioned between them, or two rotor disks and a stator disk positioned between them. While such designs offer smooth running and inherent stability of the rotor against tilting moments, they are disadvantageous with regard to the axial expansion of the axial flux machine. Particularly due to the coupling of the rotor with the dual-mass flywheel, good rotor support with minimal axial expansion is achieved despite the use of only one rotor disk and one stator disk.

[0017] Preferably, the first flywheel of the dual-mass flywheel is bolted to the output shaft of the internal combustion engine.

[0018] In a particularly preferred embodiment, the at least one rotor disk is arranged between the stator and the dual-mass flywheel. Such an arrangement has proven particularly advantageous with regard to ease of assembly, since otherwise the output shaft of the internal combustion engine would have to pass at least partially through the axial flux machine.

[0019] In a particularly preferred embodiment, the transmission is a dual-clutch transmission. Dual-clutch transmissions, in particular, have a greater longitudinal extent in the input shaft direction, so the use of an axial flux machine offers advantages, especially in dual-clutch transmissions.

[0020] The axial flux machine is preferably a single-disc rotor axial flux machine.

[0021] Preferably, the transmission is a transverse transmission.

[0022] In a particularly preferred embodiment, it is provided that further advantages in the axial design for a compact drive unit can be achieved by combining the axially compact single-disc rotor axial flux machine in conjunction with a transverse gearbox.

[0023] It is considered particularly advantageous if the axial flux machine is a high-voltage axial flux machine.

[0024] The axial flux machine is therefore, in particular, a high-voltage component whose DC voltage, especially its operating or rated voltage, is preferably greater than 50 volts, particularly greater than 60 volts, and most preferably several hundred volts. This allows for the realization of particularly high electrical power outputs, especially for purely electric propulsion of the motor vehicle.

[0025] In a particularly preferred embodiment, the axial flux machine has a housing, wherein the housing is mechanically connected to an engine block of the internal combustion engine and / or to a gearbox housing of the transmission. Such a design has the advantage that the axial flux machine is integrated particularly stably into the hybrid drive system and, due to the housing, can be sealed particularly well against the environment. In particular, by providing a separate housing for the axial flux machine, independent cooling can be provided for the axial flux machine as a separate electric motor module.

[0026] It is considered particularly advantageous if the rotor shaft of the axial flux machine is independently supported within the housing, preferably by at least one rolling bearing. Such a design ensures that the rotor is not supported by the output shaft of the internal combustion engine, the dual-mass flywheel, or the input shaft of the transmission. This prevents tilting moments and forces.

[0027] In a particularly preferred embodiment, the housing has a fluid-tight receiving chamber, the stator being housed within this chamber, while the rotor disk is arranged outside the receiving chamber, and the receiving chamber being permeable to a coolant. This design allows for particularly effective cooling of the current-carrying stator, especially since the axial flux machine's arrangement between the internal combustion engine and the transmission restricts heat dissipation to the environment and also results in additional heat input from the internal combustion engine's waste heat.

[0028] In a particularly preferred embodiment, the housing comprises a bell-shaped housing cover, a housing base, and a radially outer annular support housing part, wherein the receiving space is formed between the bell-shaped housing cover and the housing base, and wherein the support housing part has an inlet opening and an outlet opening for the coolant. Such a design is advantageous in that, in particular, the stator can project axially from the annular support housing part and yet still be enclosed by the housing due to the bell-shaped design of the housing cover.In particular, this design allows for an arrangement of the axial flux machine in which the stator is at least partially enclosed by the gearbox housing, and the annular support housing section is located axially outside the gearbox housing. This still enables a good and simple connection of the axial flux machine to a cooling system via the inlet and outlet openings formed on the annular support housing section. Therefore, a nested arrangement of the gearbox housing and axial flux machine is possible while still providing easily accessible connection points for a cooling system.

[0029] Preferably, the base of the case is also bell-shaped.

[0030] Preferably, the bell-shaped housing base and the bell-shaped housing lid are arranged nested inside each other.

[0031] It is considered particularly advantageous if the support housing part has an electrical interface, whereby the axial flux machine can be connected via the electrical interface to a pulse inverter for controlling the axial flux machine. The aforementioned statements regarding the annular support housing part with respect to connection to a cooling system apply accordingly to the connection of the axial flux machine to the pulse inverter.

[0032] In a particularly preferred embodiment, it is provided that the housing base is sealed against the support housing part and the housing cover is sealed against the support housing part.

[0033] Furthermore, it is considered particularly advantageous if the ring-shaped support housing part seals against both the engine block and the housing part. This achieves particularly good protection and shielding of the axial flux machine and the dual-mass flywheel against external influences.

[0034] Another advantage of this design is that the hybrid drive system, consisting of combustion engine, axial flux machine and gearbox, can be pre-assembled and then installed in the vehicle as a complete assembly unit.

[0035] In a further advantageous embodiment, the bell-shaped housing cover, the housing base, the support housing part, and the stator are arranged to form an assembly unit independent of the rotor. To create the hybrid drive system, it is then only necessary to position the axial flux machine between the combustion engine and the transmission, and then to connect the dual-mass flywheel, pre-mounted on the combustion engine, to the rotor in a rotationally fixed manner. This can be achieved, in particular, via a splined connection, thus simplifying assembly. Similarly, the input shaft of the transmission must be connected to the rotor in a rotationally fixed manner, again via a splined connection, thus simplifying assembly.

[0036] It is considered particularly advantageous if the receiving chamber is cup- or bell-shaped with an annular secondary section and a main section accommodating the stator, wherein the main section and the secondary section are fluid-connected, and the secondary section radially surrounds the at least one rotor disk. This design allows for optimal indirect cooling of the bell-shaped chamber of the electric machine in addition to immersion cooling. Such a design also allows for particularly advantageous cooling of the rotor disk, although stator cooling can be more efficient, especially if the stator is directly exposed to the cooling fluid, provided immersion cooling is used. In the case of immersion cooling, it is considered advantageous if the cooling fluid is a dielectric fluid, for example, a cooling oil.

[0037] It is considered particularly advantageous if the axial flux engine has a self-contained, separate primary coolant circuit in which the coolant can circulate. Providing a separate coolant circuit for the axial flux engine has the advantage that the axial flux engine can be controlled to a desired temperature independently of other components via this independent coolant circuit. For example, it is generally necessary to cool the axial flux engine to a lower temperature than the internal combustion engine to ensure high operational reliability and / or efficiency. Particularly due to the relatively close proximity of the axial flux engine to the internal combustion engine, a self-contained, separate primary coolant circuit for the axial flux engine is therefore considered especially advantageous.This type of design is particularly advantageous when high power is demanded from the hybrid drive system, so that both the combustion engine and the axial flux machine run under high load and thus generate a lot of heat.

[0038] In a particularly preferred embodiment, the transmission has a second coolant circuit in which a second coolant can circulate for cooling the transmission. The hybrid drive system includes a common heat exchanger, the common heat exchanger being integrated into both the first and second coolant circuits. The common heat exchanger is designed such that the coolant of the first circuit and the coolant of the second circuit flow through the common heat exchanger in fluid separation. Such a design reduces the number of necessary components and, in particular, the required pipe lengths.Furthermore, practical experience has shown that the necessary temperature ranges for the first coolant for cooling the axial flux machine and for the second coolant for cooling the gearbox are similar, so that a single combined heat exchanger can be advantageously used to cool both the first and second coolants.

[0039] It is considered particularly advantageous if the heat exchanger is attached to the gearbox housing.

[0040] In a particularly preferred embodiment, the common heat exchanger is an oil-water heat exchanger, wherein the coolant of the first coolant circuit is a cooling oil, wherein the second coolant of the second coolant circuit is another cooling oil, and wherein the oil-water heat exchanger is connected to a cooling water circuit of the internal combustion engine.

[0041] The following figures explain the invention in more detail with reference to exemplary embodiments, without being limited to these. They show: Fig. 1 a hybrid drive system of a motor vehicle according to the invention with an axial flux machine shown only schematically in a longitudinal section, Fig. 2 an embodiment of the axial flux machine in a perspective view, Fig. 3 the axial flux machine according to Fig. 2 together with a dual-mass flywheel in an exploded view, Fig. 4 a sub-area of ​​the arrangement according to Fig. 3 in a longitudinal section, Fig. 5 the axial flux machine according to Fig. 2 in a cross-section, Fig. 6 the axial flux machine in a sectional view along line AA in Fig. 5, Fig. 7 the axial flux machine in a sectional view along line BB in Fig. 5, Fig. 8a a first embodiment of a cooling system of the axial flux machine according to Fig. 2 in a schematic representation, Fig. 8b a second embodiment of a cooling system of the axial flux machine according to Fig. 2 in a schematic representation, Fig. 9 a partial area of ​​a hybrid drive system with an axial flux machine according to a further embodiment in a perspective view, Fig. 10 the hybrid drive system according to Fig. 9 in an exploded view, Fig. 11 a gearbox with an axial flux machine arranged thereon according to a further embodiment of the hybrid drive system in a perspective view, Fig. 12 a cooling system of the arrangement according to Fig. 11 in a schematic representation.

[0042] The Fig. Figure 1 shows a hybrid drive system 1 of a motor vehicle, wherein the hybrid drive system 1 comprises an internal combustion engine 10, a transmission 20 in the form of a dual-clutch transmission, and an axial flux machine 30. The internal combustion engine 10 has an output shaft 11, with an output shaft rotation axis D10 pointing in the longitudinal direction of the motor vehicle. Accordingly, the internal combustion engine 10 is a longitudinally mounted internal combustion engine. The transmission 20 is arranged in front of the internal combustion engine 10 in the direction of travel. An input shaft 21 of the transmission 20 has an input shaft rotation axis D20, which is coaxial with the output shaft rotation axis D10 of the output shaft 11. The axial flux machine 30 is arranged between the internal combustion engine 10 and the transmission 20. The axial flux machine 30 has a stator 34 with exactly one stator disk and a rotor 31 rotatable relative to the stator 34 with exactly one rotor disk 32.A rotor rotation axis D30 of the rotor 31 is designed coaxially to the output shaft rotation axis D10 and the input shaft rotation axis D20.

[0043] The hybrid drive system 1 has a dual-mass flywheel 70, wherein the output shaft 11 of the internal combustion engine 10 is rotationally fixedly coupled to a first flywheel 71 of the dual-mass flywheel 70. In this case, the output shaft 11 is bolted to the first flywheel 71. The rotor 31 of the axial flux machine 30 is rotationally fixedly coupled to a second flywheel 72 of the dual-mass flywheel 70. This rotationally fixed coupling is achieved by means of a splined connection. The input shaft 21 of the gearbox 20 is rotationally fixedly coupled to the rotor 31 of the axial flux machine 30. This rotationally fixed coupling is also achieved by means of a splined connection. The axial flux machine 30 is arranged such that the single rotor disk 32 is positioned axially between the stator 34 and the dual-mass flywheel 70.

[0044] The axial flux machine 30 has a multi-part housing 36, 37, 38, wherein a rotor shaft 33 of the rotor 31, which is non-rotatably connected to the rotor disk 32, is independently supported in the housing 36, 37, 38 by a rolling bearing 39, namely a shoulder ball bearing.

[0045] The multi-part housing 36, 37, 38 encloses a fluid-tight receiving chamber 41, 42, wherein the stator 34 is received in the receiving chamber 41, 42 and the rotor disk 32 is arranged outside the receiving chamber 41, 42. This is particularly evident from the sectional views of the Fig. 4, Fig. 6 and Fig. 7. The receiving chamber 41, 42 is circulated during operation by a cooling fluid, namely a dielectric cooling fluid, for example a cooling oil, to cool the stator 34 arranged in the receiving chamber 41, 42 in the form of immersion cooling.

[0046] Specifically, the housing 36, 37, 38 comprises a bell-shaped housing cover 37, a bell-shaped housing base 38, and a radially outer annular support housing part 36. The receiving chamber 41, 42 is formed between the bell-shaped housing cover 37 and the bell-shaped housing base 38. The support housing part 36 has an inlet opening 43 and an outlet opening 44 for the coolant, as can be seen in particular in the sectional views of the Fig. 5, Fig. 6 and Fig. 7 can be seen. In addition, the carrier housing part 36 has an electrical interface 50 in the form of plug connections, wherein the axial flux machine 30 is electrically connected via the electrical interface 50 to a pulse inverter for controlling the axial flux machine 30, specifically for controlling the stator windings of the stator 34.

[0047] The support housing part 36 also serves to mechanically connect the axial flux machine 30 to an engine block 16 of the internal combustion engine 10 and to mechanically connect the axial flux machine 30 to a gearbox housing 26 of the gearbox 20. In this case, the support housing part 36 is bolted to the engine block 16 and the gearbox housing 26.

[0048] As seen in particular in the sectional views of the Fig. 4, Fig. 6 and Fig. As can be seen from Figure 7, the housing cover 37 has an end wall section 371 facing the transmission 20 and a circumferential shell section 372 connected to the end wall section 371 and extending towards the internal combustion engine 10, and the housing base 38 has an end wall section 381 facing the transmission 20 and a circumferential shell section 382 connected to the end wall section 381 and extending towards the internal combustion engine 10. The housing cover 37 and the housing base 38 are arranged nested within each other, so that the receiving space 41, 42 is also cup-shaped or... The bell-shaped structure includes an annular secondary section 42 formed between the circumferential shell sections 372, 382 and a main section 41, which accommodates the stator 34 and is formed between the two end wall sections 371, 371. The main section 41 and the secondary section 42 are fluidly connected to each other.The secondary section 42 extends axially beyond the rotor disk 32, so that the secondary section 42 radially surrounds the rotor disk 32 on its outer edge. The feed opening 43 and the outlet opening 44 open into the secondary section 42.

[0049] The housing cover 37 also has a flange section 373 connected to the shell section 372, wherein the housing cover 37 is screwed to the support housing part 36 in the area of ​​the flange section 373.

[0050] The carrier housing part 36 has a radially inward projecting circumferential projection 362, against which the housing base 36 with its shell section 372 is supported in the axial direction.

[0051] In the embodiment according to the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. Figure 7 provides that the axial flux machine 30 has a self-contained, independent first coolant circuit 60 with a pump 61 for circulating the coolant in the first coolant circuit 60, an expansion tank 63 for coolant, and a heat exchanger 62 for tempering the circulating coolant. The pump 61, the expansion tank 63, and the heat exchanger 62 are attached to the support housing part 36, thus enabling pre-assembly of these components of the first coolant circuit 60 on the axial flux machine 30. After or during the assembly of the hybrid drive system 1, only the connection of the heat exchanger 62 to a second fluid circuit is then necessary. This fluid circuit can, for example, be a low-temperature water circuit of the vehicle. Fig. Figure 8a schematically shows the first coolant circuit 60 according to a first embodiment. In addition to the aforementioned components, the first coolant circuit 60 also includes two pressure relief valves 64 and a coolant filter 65. In the Fig. Figure 8b schematically shows the first coolant circuit 60 according to a second embodiment. The design of the second embodiment differs from the design of the first embodiment essentially in the arrangement of the expansion tank 63.

[0052] The Fig. 9 and Fig. Figure 10 shows a second embodiment of the hybrid drive system 1, wherein this embodiment differs from the embodiment according to the Fig. 1 to 6 differs essentially by the design of the axial flux machine 30, namely in this case by the design of the electrical interface 50.

[0053] The Fig. Figure 11 shows a further embodiment of the hybrid drive system 1. In this embodiment, the transmission 20 has a second coolant circuit 80. The first coolant circuit 60 and the second coolant circuit 80 are each designed as self-contained, separate coolant circuits. Therefore, there is no mixing or division of coolant flows between the first coolant circuit 60 and the second coolant circuit 80. However, it is provided that the first coolant circuit 60 and the second coolant circuit 80 have a common heat exchanger 90, wherein the common heat exchanger 90 is designed such that the coolant of the first coolant circuit 60 and the second coolant of the second coolant circuit 80 flow through the common heat exchanger 90 in fluid separation.The common heat exchanger 90 is an oil-water heat exchanger. Both the coolant in the first coolant circuit 60 and the coolant in the second coolant circuit 80 are cooling oils. The oil-water heat exchanger is fluidly connected to a cooling water circuit 100 of the internal combustion engine 10 to cool the cooling oils flowing through the heat exchanger 90. The first coolant circuit 60 has a pump 61 to circulate the coolant. The pump 61 is attached to the gearbox housing 26.

[0054] In the Fig. Figure 12 shows a schematic representation of the cooling system described above for gearbox 20 and axial flux machine 30. Reference symbol list 1 Hybrid drive system 10 Internal combustion engine 11 Output shaft 16 Engine block 20 gearboxes 21 Input wave 26 Gearbox housings 30 Axial flux machine 31 Rotor 32 Rotor disc 33 Rotor shaft 34 Stator 36 Carrier housing part 37 Housing cover 38 Case base 39 rolling bearings 41 Main Section 42 Subsection 43 Feed opening 44 Outlet opening 50 electrical interface 60 first coolant circuit 61 Pump 62 heat exchangers 63 expansion tanks 64 Pressure relief valve 65 filters 70 Dual-mass flywheel 71 first flywheel 72 second flywheel 80 second coolant circuit 90 common heat exchanger 100 Cooling water circuit 371 End wall section 372 Mantle section 373 Flange section 381 End wall section 382 Mantle section 362 Support section D10 Output shaft rotation axis D20 Input shaft rotation axis D30 Rotor axis 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] DE 10 2022 114 472 A1

[0004] EP 3 493 372 B1

[0004] EP 1 860 759 A2

[0004]

Claims

[1] Hybrid drive system (1) of a motor vehicle, wherein the hybrid drive system (1) comprises an internal combustion engine (10) and a transmission (20), wherein the internal combustion engine (10) comprises an output shaft (11) and the transmission (20) comprises an input shaft (21), wherein the hybrid drive system (1) comprises an axial flux machine (30), wherein the axial flux machine (30) comprises a stator (34) and a rotor (31) rotatable relative to the stator, with at least one rotor disk (32), wherein the hybrid drive system (1) comprises a dual-mass flywheel (70), wherein the output shaft (11) of the internal combustion engine (10) is rotationally fixedly coupled to a first flywheel (71) of the dual-mass flywheel (70), wherein the rotor (31) of the axial flux machine (30) is rotationally fixedly coupled to a second flywheel (72) of the dual-mass flywheel (70), wherein the input shaft (21) of the gearbox (20) is coupled to the rotor (31) of the axial flux machine (30) in a rotationally fixed manner. [2] Hybrid drive system (1) according to claim 1, wherein an output shaft rotation axis (D10) of the output shaft (11), an input shaft rotation axis (D20) of the input shaft (21) and a rotor rotation axis (D30) of the rotor (31) are formed coaxially to each other. [3] Hybrid drive system (1) according to claim 1 or 2, wherein the axial flux machine (30) has exactly one stator disk and exactly one rotor disk (32). [4] Hybrid drive system (1) according to one of claims 1 to 3, wherein the at least one rotor disk (32) is arranged between the stator (34) and the dual-mass flywheel (70). [5] Hybrid drive system (1) according to any one of claims 1 to 4, wherein the axial flux machine (30) is a high-voltage axial flux machine. [6] Hybrid drive system (1) according to any one of claims 1 to 5, wherein the axial flux machine (30) has a housing (36, 37, 38), wherein the housing (36, 37, 38) is mechanically connected to an engine block (16) of the internal combustion engine (10) and / or is mechanically connected to a gearbox housing (26) of the gearbox (20). [7] Hybrid drive system (1) according to claim 6, wherein the housing (36, 37, 38) has a fluid-tight receiving space (41, 42), wherein the stator (34) is received in the receiving space (41, 42), wherein the rotor disk (32) is arranged outside the receiving space (41, 42), wherein the receiving space (41, 42) is permeable to a coolant. [8] Hybrid drive system (1) according to claim 7, wherein the housing (36, 37, 38) has a bell-shaped housing cover (37), a housing base (38) and a radially outer annular support housing part (36), wherein the receiving space (41, 42) is formed between the bell-shaped housing cover (37) and the housing base (38), wherein the support housing part (36) has an inlet opening (43) and an outlet opening (44) for the coolant. [9] Hybrid drive system (1) according to claim 8, wherein the receiving space (41, 42) is cup- or bell-shaped with an annular secondary section (42) and a main section (41) receiving the stator (34), wherein the main section (41) and the secondary section (42) are fluidly connected, wherein the secondary section (42) radially surrounds the at least one rotor disk (32). [10] Hybrid drive system (1) according to claim 9, wherein the feed opening (43) opens into the secondary section (42) and / or the outlet opening (44) opens into the secondary section (45).

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