DRIVE ARRANGEMENT FOR A MOTOR VEHICLE

Description

[0001] The invention relates to a drive arrangement for a motor vehicle, comprising a housing with an engine compartment and a gear compartment adjacent to the engine compartment and delimited therefrom by an inner end wall, each delimited by said inner end wall, an associated outer end wall and a casing wall extending in the axial direction between the inner and associated outer end walls, an electric machine arranged in the engine compartment with a stator fixed to the housing and a rotor arranged radially inside the stator with a hollow rotor shaft which penetrates the inner end wall and the outer end wall of the engine compartment and is rotatably mounted in the engine compartment and is provided with an open end face having a central through-opening, and an active oil circuit with an oil pump, by means of which oil is pumped from an oil reservoir through an oil distribution channel comprising at least one first branch via an oil guide pipe (88) connected to the downstream end of the first branch (78a) of the oil distribution channel,which projects with its free end through the central through-opening into the interior of the rotor shaft and can be pumped into the interior of the hollow rotor shaft.

[0002] Such a drive arrangement is known from US 2020 / 0052534 A1.

[0003] EP 3 028 888 B1 discloses an electric drive for a motor vehicle, which is designed as a compact drive arrangement comprising, on the one hand, the actual drive unit and, on the other hand, a transmission for translating and distributing the torque supplied by the electric machine. Both units are arranged in a common housing, which, however, is divided into essentially separate compartments, namely an engine compartment and a transmission compartment, due to the different requirements of the individual units. Both compartments are penetrated by a common shaft, which acts as a rotor shaft in the engine compartment and as a transmission input shaft in the transmission compartment. This means that the engine compartment and transmission compartment are arranged adjacent to one another in the axial direction and share a common end wall, referred to here as the inner end wall.On the axially opposite side, each chamber is bounded by another end wall, referred to here as the outer end wall. Between the (common) inner end wall and each outer end wall, a corresponding shell wall extends axially.

[0004] Those skilled in the art will understand that terms describing general relative alignments or positioning, such as "next to," "below," "above," etc., unless otherwise stated, always refer to the final assembly position of the drive assembly in the motor vehicle. The same applies to absolute alignment specifications such as "vertical" and "horizontal." Symmetry-specific terms such as "axial," "radial," etc., are always to be understood in the context of the respective symmetry unit described.

[0005] The gearbox and the electric machine are cooled and lubricated by a shared, oil-based cooling system. This comprises a reservoir from which oil is drawn by an oil pump and fed into an oil distribution channel. The oil distribution channel runs part way in the shared end wall and then branches off into two different branches. The first branch is connected to the interior of the rotor shaft, which is designed as a hollow shaft, via a rotary union. The second branch opens into the gearbox chamber. The oil fed into the rotor shaft initially serves as an internal rotor cooling system. The oil can leave the interior of the rotor shaft via radial openings on both sides of the electric machine, i.e. close to the respective end wall, and when the shaft rotates it does so in the form of a centrifugal force-driven, radially outward-directed spray.The spray oil wets the axially terminal areas of the rotor and stator, in particular the stator winding heads located there, which are also cooled in this way. The oil draining from the stator collects, driven by gravity, at the bottom of the motor compartment, which has a drain to the other areas of the reservoir. This prevents the formation of an engine oil sump, which, if its level rises excessively, could lead to oil contamination of the air gap between the rotor and stator, which would adversely affect the efficiency of the electric machine. The second branch of the oil distribution channel opens, as already mentioned, into the gear compartment and, in particular, penetrates the inner end wall at the level of the toothing between a drive pinion arranged on the drive shaft (rotor shaft) and an output gear meshing with it. The wall opening, i.e.The channel opening is located so close in the axial direction to the meshing gears that the pressure of the oil pump is sufficient to actively spray the gearing area with oil. The oil, which flows under gravity from the gears and the gear chamber walls, collects in the lower area of the gear chamber, where it forms a low gear oil sump that overflows to the other areas of the reservoir. The rotary union, via which the first branch of the oil distribution channel is connected to the hollow interior of the rotor shaft, must be considered disadvantageous due to its complex structure and susceptibility to wear. In addition, the rotary union and the inner end wall, which must be made correspondingly thick to accommodate it, reduces the installation space available for the electric machine in the engine compartment.

[0006] US 2020 / 0052534 A1, already mentioned at the beginning and forming a generic type, provides for the hollow rotor shaft to be provided with a central through-opening on each of its two end faces. At the same time, an oil distribution channel is provided inside the housing wall, in particular inside the outer end wall, which penetrates the housing wall inwards at the level of the central through-opening of the rotor shaft and merges into an oil guide tube, which projects through the associated through-opening into the interior of the rotor shaft. To enable access to the through-opening, an inwardly projecting bearing base, which supports the rotor shaft bearing, is arranged on the inside of the outer end wall. This bearing base has a cavity inside it in which the through-opening of the rotor shaft and the oil guide tube meet. This type of oil supply to the interior of the rotor shaft is structurally much simpler than the aforementioned rotary union.

[0007] The device of US 2019 / 0229582 A1 is designed in a similar way, but the oil guide tube is omitted and the cavity of the bearing socket is flooded with oil so that the oil overflows into the rotor shaft when a certain level is reached.

[0008] A structurally simpler approach is known from DE 10 2017 128 551 A1. For this purpose, an additional cover chamber is provided axially adjacent to the outer end wall. The rotor shaft extends through the outer end wall at its end there and protrudes into said cover chamber. Likewise, an oil guide channel in the outer wall of the cover chamber opens into the interior of the cover chamber and merges there into an oil guide tube, which protrudes through the central through-opening in the end face of the rotor shaft located in the cover chamber.

[0009] WO 2021 / 042466 A1 also discloses the axial feed of cooling oil into the hollow rotor shaft, but without any structural details of the transfer being discernible.

[0010] A completely different cooling principle is known from US 2011 / 0285220 A1. Here, the stator of the electric machine is cooled by oil dripping from a channel in the casing wall along its upper apex onto the resin-encapsulated stator, where it is collected in an oil sump extending along the lower apex of the stator. The oil also flows over lateral areas where electrical connections penetrate the resin. These are also cooled as a result.

[0011] It is the object of the present invention to further develop a generic device in such a way that a more efficient use of the available cooling oil results.

[0012] This object is achieved in conjunction with the features of the preamble of claim 1 in that a cover space is arranged as a further space of the housing axially adjacent to the outer end wall of the engine compartment, into which space the end face of the rotor shaft having the central through-opening and the downstream end of the first branch of the oil distribution channel project, wherein the cover space is penetrated by busbars and the oil guide tube has lateral nozzle openings spaced from its free end, through which oil can be sprayed onto said busbars.

[0013] Firstly, the invention provides for the arrangement of an additional space adjacent to the outer end face of the engine compartment, referred to here as the cover space, which is basically known from the prior art. The cover space can initially serve, as is also known in the art, as a collecting space for oil, which is used to lubricate the rotor shaft bearing arranged in the outer engine compartment end wall and from there partially penetrates to the outside. In addition, this cover space has an additional function, which is also known in the art, namely to accommodate a preferably contactless, axial oil feed into the hollow rotor shaft. For this purpose, the rotor shaft has a central through-opening in its end face facing away from the gearbox, which projects into the cover space. The interior of the rotor shaft is therefore accessible from the cover space. Furthermore, it is provided that the first branch of the oil distribution channel also opens into the cover space. Both openings, i.e.The oil distribution channel opening on the one hand and the central through-opening in the rotor shaft end face on the other hand are connected via an oil guide tube, which on the one hand can be firmly connected to the oil distribution channel opening and on the other hand projects axially, preferably in the form of a rigid pipe socket, into the interior of the rotor shaft. The oil pump therefore pumps oil through the first branch of the oil distribution channel to the cover chamber, where the oil is transferred to the oil guide tube and pumped into the interior of the rotor shaft. Rotating parts (rotor shaft) and stationary parts (oil guide tube) preferably do not come into contact with each other. Accordingly, no seals are required between rotating and stationary parts. This considerably simplifies the design of the oil transfer point to the rotor shaft and, above all, represents a wear-free solution. The pipe socket can have an axial opening at its end so that oil is pumped into the rotor shaft in an axial spray direction.Alternatively or additionally, radial or oblique openings can be provided in the pipe socket so that the oil is pumped into the rotor shaft with a radial or oblique spray direction.

[0014] In order to ensure that the oil pumped into the rotor shaft is distributed over the entire length of the rotor shaft and does not immediately escape back into the cover chamber around the unsealed pipe socket of the oil guide tube, it is preferably provided that the clear width of the through-opening widens gradually to the larger clear width of the interior of the rotor shaft, with the oil guide tube projecting beyond at least one step (preferably at least one of several steps) in the axial direction. If the oil pressure is sufficiently high, said step can alternatively also be overcome in a free jet. This step ensures that an oil sump can form in the rotor shaft, which only exceeds the edge of the through-opening in the rotor shaft end face when a comparatively high level is reached and can escape into the cover chamber.Depending on the relative dimensions of the clear width of the through-hole and the interior of the rotor shaft, it can be ensured that there is always a sufficient oil volume in the rotor shaft for rotor cooling.

[0015] The scenario described above of oil escaping from the through-hole in the rotor shaft end face into the cover chamber is, however, unlikely in the preferred embodiment of the invention. Here, the hollow rotor shaft is provided with radial openings in its axial end regions near the end wall within the motor chamber, through which oil can be or is thrown from the hollow interior of the rotor shaft onto the axial end regions of the stator upon rotation of the rotor. The oil will therefore predominantly leave the interior of the rotor shaft via said radial openings, thereby also cooling the stator, in particular its winding heads. From there, it collects in the motor chamber and flows into other areas of the reservoir. For example, an emergency overflow to the transmission chamber can be provided to ensure that no engine oil sump forms in the engine chamber, which could lead to oil contamination of the air gap.

[0016] According to the invention, the cover chamber is penetrated by busbars, for example those of a power electronics system, and the oil guide tube has lateral nozzle openings spaced from its free end, through which oil can be sprayed onto said busbars. The busbars are thus wetted by the oil that is sprayed through the nozzle openings of the oil guide tube when the oil pump is in operation. These busbars are also effectively cooled in a location where there is no risk of oil contamination of the associated power electronics. For this purpose, the busbars only have to be guided in a sealed manner from an oil-free power electronics chamber over the cover chamber on their way to the stator, to which they must be electrically connected.

[0017] The oil guide tube is exposed to various forces in the cover space. In addition to the vibrations and acceleration forces to which the drive assembly as a whole is exposed during driving, the advantageously provided nozzle openings lead to recoil forces. However, since the oil guide tube preferably represents a comparatively delicate structure that could yield to such forces, it is advantageous to provide a separate fixing for the oil guide tube in the cover space. In a corresponding embodiment of the invention, the free end of the oil guide tube is therefore designed as a pipe socket that extends axially from the center of a fixing star with a plurality of radially extending cantilever arms, which are fixed at their free ends to the outer end wall of the engine compartment.This means that the free end area of the oil guide tube, which should be held particularly rigidly to avoid contact with the rotating rotor shaft, is fixed with a spider-shaped fixing star on the outer engine compartment bulkhead, preferably symmetrically around the rotor shaft.

[0018] As explained at the beginning, the first branch, which opens into the oil guide tube, constitutes only one of two branches of the oil distribution channel supplied by the oil pump. Its second branch, as already mentioned, opens into the transmission compartment. In order to make the internal structures of the housing, in particular the inner bulkhead, particularly delicate and thus space-saving, it is preferably provided that the two branches of the oil distribution channel extend from a branching point in opposite directions parallel to the axial direction of the electric machine. This can be achieved, in particular, in the gusset between the outer side of the engine compartment shell wall and a reservoir space located beneath the engine compartment. This represents a favorable use of "lost" space without having to modify structures optimized for other functions.This housing area can be easily reached from the oil pump by a supply line that extends perpendicular to the axial direction of the electric machine and leads from the oil pump to the branching point.

[0019] However, the alignment of the two oil distribution channel branches parallel to the axial extent of the electric machine means that the openings of the first channel in the cover chamber and the second channel in the gear chamber are at the same height. This could create the risk of pumping too much oil directly into the gear chamber via the second branch and too little oil via the first branch into the cover chamber or via the oil guide tube into the rotor shaft. To counteract this, an advantageous embodiment of the invention provides for a constriction orifice to be arranged in the second branch of the oil distribution channel. This limits the volume flow into the gear chamber, so that the majority of the oil is pumped through the unconstricted second branch into the oil guide tube and the rotor shaft.

[0020] In the direction of flow, upstream of the constriction orifice, a settling zone for the oil is formed, into which any entrained debris sinks. In order to permanently fix this debris here, i.e., at a non-disruptive location, a magnet, in particular a ring magnet, can be arranged in the second branch of the oil distribution channel upstream of, in particular upstream of, the constriction orifice, as preferably provided. This permanently fixes the sinking or flowing metallic debris. If necessary, the ring magnet can be designed to be replaceable, so that the entire system can be cleaned of debris by replacing the magnet during maintenance work.

[0021] Further details and advantages of the invention will become apparent from the following specific description and drawings.

[0022] They show: Figure 1: a highly schematic longitudinal section through a preferred embodiment of a drive arrangement not according to the invention, Figure 2: a sectional view according to section line II-II in Figure 1 , Figure 3: a sectional view according to section line III-III in Figure 1 , Figure 4: a sectional view analogous Figure 3 by an alternative embodiment, Figure 5: a Figure 1 analog sectional view through a further alternative embodiment, Figure 6: a sectional view according to section line VI-VI in Figure 5 , Figure 7: a partially sectioned view of an embodiment according to the invention, Figure 8: a sectional view according to section line VIII-VIII in Figure 7 , Figure 9: a schematic representation of the oil tank to illustrate its position in the gearbox, Figure 10: a sectional view of the oil tank of Figure 9 with marked strong flow path, Figure 11: a sectional view of the oil tank of Figure 9 with the weak flow path shown and Figure 12: an inverted sectional view of the oil tank of Figure 9 .

[0023] The same reference numerals in the figures indicate the same or analogous elements.

[0024] Figure 1shows a highly schematic representation of a longitudinal section through a drive arrangement 10 not according to the invention. The drive arrangement 10 comprises a housing 12 which is divided into an engine compartment 14 and a transmission compartment 16. The engine compartment 14 and the transmission compartment 16 are arranged axially adjacent to one another. They are separated from one another by an intermediate wall, referred to here as the inner end wall 18. Opposite the inner end wall 18 in the axial direction, the engine compartment 14 is delimited by an outer (engine compartment) end wall 20 and the transmission compartment 16 by an outer (transmission compartment) end wall 22. In the radial direction, the engine compartment 14 is delimited by an (engine compartment) shell wall 24 and the transmission compartment 16 by a (transmission compartment) shell wall 26.

[0025] Arranged in the engine compartment 14 is an electric machine 28 with a stator 30 fixed to the housing and a rotor 32 rotatable within the stator 30. The rotor 32 has a rotor shaft 34, which is mounted on the one hand in the inner end wall 18 and on the other hand in the outer engine compartment end wall 20. The rotor shaft 34 is hollow—at least in its central region. The rotor shaft 34 penetrates the inner end wall 18 to protrude into the transmission compartment 16 as a drive shaft 36. Alternatively, the drive shaft 36 can be a separate shaft connected coaxially to the rotor shaft 34.

[0026] A transmission 38, in particular a transmission gear, is arranged in the transmission chamber 16. A drive pinion 40, which is fixed in a rotationally fixed manner on the drive shaft 36, acts as the input gear of the transmission 38. The term "pinion" is to be understood broadly and encompasses both a gear mounted on a shaft and a toothing formed integrally with the shaft. This gear is connected to an output gear 42 via several toothing stages in a torque-transmitting connection. The output gear 42 is coupled to an output, in particular a differential gear, in a manner not shown in detail.

[0027] Furthermore, an oil tank 44 is arranged in the gear chamber 16, the special design of which will be discussed in more detail below in the context of Figures 9 to 14.

[0028] Located in the lower area of the gear chamber 16 is a gear oil sump 46, into which the lower area of the output gear 42 projects from above. During rotation, its gear teeth absorb oil from the gear oil sump 46 and discharge it into the oil reservoir 44. The oil exits the reservoir at least partially via a rotor shaft outlet 48 and flows through a corresponding oil line into the hollow rotor shaft 34.

[0029] The hollow rotor shaft 34 is provided with a step 50 on both sides, which essentially allows the formation of an oil sump within the hollow rotor shaft 34 and thus a distribution of the oil over its axial length. However, the oil can leave the hollow rotor shaft 34 via radial openings 52. When the rotor shaft 34 rotates, this occurs driven by centrifugal force in the form of a centrifugal movement of the oil, which in this way reaches the winding heads 54 of the stator 30 if the radial openings 52 are correctly positioned.

[0030] The path taken by the oil, which is described in more detail below, is indicated in the figures as hatched oil production arrows.

[0031] In the illustrated embodiment, a cooling water jacket 56 is integrated into the casing wall 24 of the engine compartment 14. In the illustrated embodiment, it is designed as an arrangement of flat tubes encircling the interior of the engine compartment casing wall 24. The connections of the cooling water jacket 56 to a more complex water distribution system are not shown in detail in the figures as they are not relevant to the invention.

[0032] Below the engine compartment 14, separated by the lower part of the engine compartment shell wall 24, there is a labyrinth chamber 58, which is connected to the engine compartment 14 via engine compartment drains 60. In particular, the oil that has entered the engine compartment 14 via the route described above can flow into the labyrinth chamber 58 via the engine compartment drains 60 without the risk of an excessively high engine oil sump forming. For safety reasons, as in the illustrated embodiment, it can be provided that the engine compartment 14 is additionally connected to the transmission compartment 16, in particular the transmission oil sump 46, via an engine compartment overflow 62. In this way, oil contamination of the air gap 64 between the stator 30 and the rotor 32 of the electric machine 28 can be reliably prevented.

[0033] The cover of the labyrinth chamber 58, i.e., the outer side of the lower region of the engine compartment shell wall 24, is provided with cooling fins 66 that extend sufficiently deep into the labyrinth chamber 58 to be surrounded by accumulated oil. In an alternative embodiment, the thermal coupling between the oil in the labyrinth chamber 58 and the cooling water jacket 56 is not only provided via the cooling fins 66, but the engine compartment shell wall 24 extends deeper into the labyrinth chamber 58 and is directly wetted by the oil. The maximum oil level in the labyrinth chamber 58 is determined by the height of a labyrinth chamber overflow 68, via which the labyrinth chamber 58 is connected to the transmission chamber 16, in particular the transmission oil sump 46.In this way, heat exchange between the cooling water jacket 56 and the oil located in the labyrinth chamber 58 can take place via the cooling fins 66. The oil is further cooled by the fact that the bottom 70 of the labyrinth chamber 58 represents an outer wall of the housing 12, which in turn is surrounded by ambient air. This achieves particularly efficient cooling of the oil and water.

[0034] Figure 2 shows a section along the section line II-II in Figure 1 . Figure 3 shows a section along the section line III-III in Figure 1 These two illustrations illustrate that the labyrinth chamber 58 has several oil guide elements 72 extending throughout its entire height, forcing the oil flowing in through the engine compartment outlets 60 to meander. This intensifies the thermal contact with the cooling fins 66 and thus improves the thermal exchange.

[0035] Further on in the Figures 2 and 3 It can be seen that the labyrinth chamber 58 merges into a suction chamber 74 of an oil pump 76, whose suction nozzle 77 projects into the suction chamber 76. From here, oil can be pumped to various positions of the drive arrangement 10 requiring lubrication and cooling during active pumping operation. Figure 2 a corresponding oil distribution channel 78 connected to the oil pump 76 can be seen, which will be discussed in more detail below.

[0036] Furthermore, excess oil from the labyrinth chamber 58 or the suction chamber 74 can pass via the labyrinth chamber overflow 68 into the gear chamber 16 and in particular the gear oil sump 46 there.

[0037] In the embodiment of Figure 3 The labyrinth chamber 58 essentially comprises a single labyrinth chamber into which both engine compartment drains 60 open. This means that oil which is discharged from the Figure 3left engine compartment drain 60 into the labyrinth chamber 58, at Figure 3 right engine compartment drain 60 and mixes there with the oil flowing in through it. Regarding the dimensioning, care must be taken to ensure that large volume flows do not lead to an oil back-up at this point, even in particularly unfavorable situations. To completely rule this out, in one embodiment, such as in Figure 4 As shown, it is provided that the labyrinth space is divided into two different labyrinth space chambers, into each of which one of the engine compartment drains 60 opens. Furthermore, reference can be made in full to what has been said above.

[0038] Figure 5 shows an analog Figure 1 constructed representation of an alternative embodiment of the drive arrangement 10. In this embodiment, axially adjacent to the outer end face 20 of the engine compartment 14, ie right in Figure 5, a cover chamber 80, whose primary function is to collect oil seeping through the outer end wall 20. In particular, it will be difficult to ensure lubrication of the rotor shaft bearing in the outer engine compartment end wall 20 (not shown in detail in the figures) without oil leaking through the bearing to the outside of the engine compartment 14. This oil can be collected in the cover chamber 80 and returned to the previously described oil circuit in the manner explained in more detail below. In addition, the presence of the cover chamber 80 offers the possibility of targeted further use.

[0039] Thus, in the embodiment of Figure 5provided that the outer engine compartment bulkhead 20, analogous to the engine compartment overflow 62 in the inner bulkhead 18, another engine compartment overflow 82 is located, via which oil from the engine compartment 14 can flow into the cover chamber 80. In the embodiment shown, the cover chamber 80 is connected via a labyrinth chamber overflow 84 to the oil reservoir, in particular to an antechamber downstream of the labyrinth chamber 58, e.g. the suction chamber 74. As in Figure 6 shown, can be done similar to the one in Figure 4 shown embodiment, the labyrinth chamber 58 can be divided into two chambers. The oil flowing through the gearbox-side engine compartment drain 60 into the labyrinth chamber 58 flows through only one in this embodiment, namely the one shown in Figure 6 upper labyrinth chamber and then circulates through the lid chamber 80 to the second, in Figure 6lower labyrinth chamber. The oil flowing through the cover-side engine compartment drain 60 into the labyrinth chamber 58, however, only flows through the other, namely the Figure 6 Lower labyrinth chamber. Both oil flows only merge in a chamber downstream of the labyrinth chamber, e.g., the suction chamber 74. This reliably prevents oil buildup in the labyrinth chamber. This form of oil diversion is also conceivable for variants without the cover chamber 80. Here, the outlet from the (upper) labyrinth chamber and the inlet to the suction chamber could be connected via a corresponding line. It is also conceivable that the additional engine compartment overflow 82 replaces the cover-side engine compartment drain 60.

[0040] Figure 7shows an embodiment according to the invention in which the cover chamber 80 has an alternative or additional use. This type of embodiment requires an oil pump 76, which sucks oil from the oil reservoir, in particular from the suction chamber 74, and feeds it into an oil distribution channel 78. In the Figure 7 In the embodiment shown, the oil distribution channel 78 runs as shown in Figure 2 visible, in the gusset between the engine compartment shell wall 24 and the cover of the suction chamber 74. In the embodiment shown, it is divided into two opposing branches 78a, 78b. The branch 78b, referred to here as the second branch, Figure 7The left branch of the oil distribution channel 78 opens into the gear chamber 16, passing through a constriction orifice 85 to prevent excessive outflow into the gear chamber 16. The majority of the pumped oil is therefore discharged via the first branch 78a of the oil distribution channel, as described in more detail below. The constriction orifice 85 in the second branch 78b of the oil distribution channel 78 is preferably equipped with a magnet 86, in particular a ring magnet, adjacent to it upstream, to remove metallic abrasion from the oil circuit.

[0041] The first branch 78a of the oil distribution channel 78 opens into the cover chamber 80, where an oil guide pipe 88 is connected to its free end. Figure 8 shows a sectional view according to section line VIII-VIII in Figure 7 and will subsequently be published together with Figure 7be discussed. The oil guide tube 88 leads in an arc to a fixing star 98, which is fixed with its arms to the outside of the outer engine compartment bulkhead 20. In its center, it fixes an end of the oil guide tube 88 designed as a pipe socket 92, which projects into the open end of the hollow rotor shaft 34. As at its end facing the transmission compartment, the hollow rotor shaft 34 is also equipped with a step 50 on its interior, over which the pipe socket 92 projects axially. Consequently, oil pumped via the second branch 78a of the oil distribution channel 78 is pumped directly into the interior of the rotor shaft 34, where it contributes to the formation of the oil sump there. Regarding the further oil flow, reference is made to the above explanations, particularly in the context of Figure 1 referred to.

[0042] In the Figures 7 and 8However, in the embodiments shown, the oil guide tube 88 fulfills another function. In this embodiment, busbars 94 for supplying current to the stator 30 are guided sectionally through the cover space 80. The oil guide tube 88 describes an arc in the cover space 80 which leads it close to these busbars 94. In the area of closest approach, the side wall of the oil guide tube 88 has nozzle openings 96 from which oil is sprayed onto the busbars in order to cool them. The dimensioning of the nozzle openings 96 is, as the person skilled in the art will recognize, preferably such that, at the oil pressure in the oil guide tube 88 specified by the oil pump 76, a continuous, sufficient flushing of the busbars 96 can take place, although enough oil still remains in the oil guide tube 88 to be pumped into the hollow rotor shaft 34 for cooling it.

[0043] Figure 9shows a particularly preferred embodiment of the oil container 44 in its final assembly position in the gearbox 38. Of the latter, the drive pinion 40 and the output gear 42 are particularly important in this case.

[0044] As in the context of Figure 1 describe, the output wheel 42 is in a Figure 9not shown gear oil sump 46, so that its teeth absorb oil during rotation and, as illustrated by the hatched oil feed arrows, are thrown into an inlet opening 98. The oil reservoir 44 has a plurality of drains in its side wall, which will be discussed in more detail below. Here, only the gear oil sump outlet 100, marked with an oil feed arrow, will be mentioned, which allows oil to drain from the oil reservoir 44 into a drive pinion pan 102. The drive pinion pan 102 is arranged below the drive pinion 40 in such a way that the latter is partially immersed in it, so that its lower region is wetted by an oil sump accumulated in the drive pinion pan.The transmission oil sump outlet 100 represents the lowest oil outlet of the oil reservoir 44, which allows for its maximum emptying into the transmission oil sump via the drive pinion pan 102, which overflows to the transmission oil sump 46. This ensures that even after long downtimes, the drive pinion 40 remains at least partially oiled, so that wear-reducing lubrication of all gears of the transmission 38 begins very quickly after the drive assembly is restarted.

[0045] Figure 10 shows a section through the oil tank 44 of Figure 9in normal operation, referred to here as high-flow operation. In particular, the inside of the container wall of the oil container 44 is illustrated as viewed from the engine compartment. The inlet opening 98 merges into an inlet channel 104, which is oriented essentially vertically. Its channel wall opposite the inlet opening 98 is designed as a concavely curved baffle 106, against which oil thrown in during high-flow operation impacts and flows downwards in a comparatively strong stream. Only a small portion of this main oil flow flows through a passage opening 108 in the baffle 106, which will be discussed in more detail below. The majority of the oil flow flows around the lower free end 110 of the baffle 106 and rises behind it again. In particular, when an oil level corresponding to the Figure 10upper dashed level line, oil can flow outwards through the rotor shaft outlet 48 in the wall of the oil container 44 and via a correspondingly connected line into the interior of the hollow rotor shaft 34, as already described in the context of Figure 1 explained. At the same time, oil can flow through the transmission oil sump outlet 100 and the drive pinion pan 102 into the transmission oil sump 46. Only a drainless pocket 112 below the transmission oil sump outlet 100 permanently houses an internal oil sump, which is particularly suitable for separating dirt. Figure 10 The lower dashed level line illustrates the oil level in the oil tank 44 after maximum emptying.

[0046] Figure 11 shows the same section through the oil tank 44 as Figure 10, however, not in high-flow operation, but in low-flow operation during very slow operation of the drive arrangement 10 or immediately after its start. The oil flow is correspondingly low, as indicated by the modified oil feed arrows in Figure 11 opposite Figure 10indicated. The oil, which is only conveyed in trickle or drop form, does not reach the baffle 106 but flows off the channel wall opposite it. Below the inlet opening 98, this channel wall is therefore equipped with an oil guide projection 114, which ends diagonally above the passage 108, so that oil dripping or running off its edge flows through said passage 108 to the rear of the baffle 106. There it is caught by a trough-like intermediate floor 116, which directs it directly to the rotor shaft outlet 48. This means that even with a very low, slow oil flow, lubrication of the rotor shaft interior is possible, and there is no need to wait for the previously described rise in the oil level around the lower, free end 110 of the baffle 106. For the sake of completeness, reference should also be made to a vent opening 118 in the upper part of the reservoir 44, above any conceivable oil level during normal operation.

[0047] Figure 12 also shows a section through the oil tank 44, but illustrated with a view into the engine compartment 14. Immediately above the intermediate floor 116, two differently dimensioned bearing outlets 120 and, further above, an emergency outlet 122 to the engine compartment 14 are arranged. The bearing outlets 120 at the designated location ensure that, in addition to the rotor shaft cooling, the lubrication of essential bearings, which are connected to the bearing outlets 120 via oil guide systems not shown in detail, is also guaranteed even during slow operation or immediately after starting the drive arrangement 10.

[0048] Of course, the embodiments discussed in the specific description and shown in the figures represent only illustrative embodiments of the present invention. In light of the disclosure herein, a wide range of possible variations is available to the person skilled in the art. List of reference symbols

[0049] 10Drive arrangement 12Housing 14Engine compartment 16Gearbox compartment 18Inner bulkhead 20Outer bulkhead of engine compartment 14 22Outer bulkhead of gearbox compartment 16 24Shell wall of engine compartment 14 26Shell wall of gearbox compartment 16 28Electric machine 30Stator 32Rotor 34Rotor shaft 36Drive shaft 38Gearbox 40Drive pinion 42Output gear 44Oil reservoir 46Gearbox oil sump 48Rotor shaft outlet 50Stage 52Radial opening of rotor shaft 54Stator winding head 56Cooling water jacket 58Labyrinth compartment 60Engine compartment drain 62Engine compartment overflow 64Air gap 66Cooling fin 68Labyrinth compartment overflow 70Floor of Labyrinth chamber 72 Oil guide element 74 Suction chamber 76 Oil pump 78 Oil distribution channel 78a First branch of 78 78b Second branch of 78 80 Cover chamber 82 Further engine compartment overflow 84 Labyrinth chamber overflow 85 Restriction orifice 86 Ring magnet 88 Oil guide tube 90 Fixing star 92 Pipe socket 94 Busbar 96 Nozzle opening 98 Inlet opening of oil reservoir 44 100 Gearbox oil sump outlet 102 Drive pinion pan 104 Inlet channel 106 Baffle wall 108 Passagein 106 110free end of 106 112pocket 114oil guide projection 116intermediate floor 118vent opening 120bearing outlet 122engine compartment (emergency) outlet

Claims

1. Drive assembly (10) for a motor vehicle, comprising - a housing (12) having an engine compartment (14) and a transmission compartment (16) which adjoins the engine compartment (14) and is delimited therefrom by means of an inner bulkhead (18), in each case delimited by said inner bulkhead (18), an associated outer bulkhead (20, 22) and a casing wall (24, 26) extending in the axial direction between the inner and the associated outer bulkhead (18; 20, 22), - an electric machine (28) which is arranged in the engine compartment (14) and has a stator (30) which is fastened to the housing, and a rotor (32) which is arranged radially within the stator (30) and has a hollow rotor shaft (34) which passes through the inner bulkhead (18) and the outer bulkhead (20) of the engine compartment (14) and is rotatably mounted in the engine compartment (14), which rotor shaft is provided with an open end face that has a central through-opening, and - an active oil circuit which has an oil pump (76) by means of which oil can be pumped from an oil reservoir, through an oil distribution channel (78) which comprises at least a first branch (78a), and into the interior of the hollow rotor shaft (34) via an oil guide tube (88) connected to the downstream end of the first branch (78a) of the oil distribution channel (78), which tube projects with its free end through the central through-opening into the interior of the rotor shaft (34), characterized in that a cover compartment (80) is arranged axially adjacent to the outer bulkhead (20) of the engine compartment (14) as an additional compartment of the housing (12), into which cover compartment the end face of the rotor shaft (34) which has the central through-opening and the downstream end of the first branch (78a) of the oil distribution channel (78) project, wherein busbars (94) pass through the cover compartment (80), and the oil guide tube (88) has lateral nozzle openings (96) spaced apart from its free end, through which oil can be sprayed onto said busbars.

2. Drive assembly (10) according to claim 1, characterized in that the clear width of the through-opening widens in stages towards the larger clear width of the interior of the rotor shaft (34), wherein the oil guide tube (88) projects beyond at least one stage (50) in the axial direction.

3. Drive assembly (10) according to either of the preceding claims, characterized in that the hollow rotor shaft (34) has radial openings (52) in its axial end regions within the engine compartment (14) that are close to the bulkhead, through which openings oil can be thrown from the hollow interior of the rotor shaft (34) onto the axial end regions of the stator (30) during rotation of the rotor (32).

4. Drive assembly (10) according to any of the preceding claims, characterized in that the free end of the oil guide tube (88) is designed as a tubular connecting piece (92) which extends in the axial direction from the center of a fixing star (90) with a plurality of radially extending cantilever arms which are fastened at their free ends to the the outer bulkhead (20) of the engine compartment (14).

5. Drive assembly (10) according to any of the preceding claims, characterized in that an overflow (84) to the oil reservoir is arranged in the lower region of the cover compartment (80).

6. Drive assembly (10) according to any of the preceding claims, characterized in that the oil distribution channel (78) branches into two branches, namely said first branch (78a) and a second branch (78b), wherein oil can be pumped, by means of the oil pump (76), from the oil reservoir into the transmission compartment (16) via the second branch (78b).

7. Drive assembly (10) according to claim 6, characterized in that the two branches (78a, 78b) of the oil distribution channel (78) extend from a branching point in opposite directions, in parallel with the axial direction of the electric machine (28).

8. Drive assembly (10) according to claim 7, characterized in that a supply line extending perpendicularly to the axial direction of the electric machine leads from the oil pump (76) to the branching point.

9. Drive assembly (10) according to any of claims 6 to 8, characterized in that a narrowing aperture (85) is arranged in the second branch (78b) of the oil distribution channel (78).

10. Drive assembly (10) according to claim 9, characterized in that a ring magnet (86) is arranged upstream, adjacent to the narrowing aperture (85), in the second branch (78b) of the oil distribution channel (78).