Drive unit for a vehicle

Abstract

The invention relates to a drive unit (10) for a vehicle, having an electric machine (12) with a rotor shaft (14) and a transmission (16) with a transmission shaft (18). It is proposed that the rotor shaft (14) and the transmission shaft (18) are plugged into one another and coupled by means of a plug-in toothing (44), wherein a lubricant channel (46) is configured in the transmission shaft (18), which opens into an interior space (48) of the rotor shaft (14) on an end facing the rotor shaft (14) in order to supply the plug-in toothing (44) with lubricant, wherein the rotor shaft (14) has an end side (50) on an axial end facing the transmission shaft (18), on which one or more openings (52) are configured, which extend from an inner circumferential surface (54) of the rotor shaft (14) delimiting the interior space (48) to an outer circumferential surface (56) of the rotor shaft, such that the lubricant channel (46) is fluidically connected to the openings (52) via the interior space (48) and the plug-in toothing (44).

Description

TECHNICAL FIELD

[0001] The invention relates to a drive unit for a vehicle, having an electric machine with a rotor shaft and a transmission mechanism with a transmission shaft. BACKGROUND

[0002] Drive units of the type mentioned at the outset are known from the prior art as electrified axles, for example from DE 10 2018 210 452 A1.

[0003] From DE 10 2015 211 789 A1 a transmission arrangement assembly is known, which has a hollow shaft which guides lubricating oil, on the end side of which a centrifugal disc is arranged in order to guide the lubricating oil past the transmission mechanism components and to deliver the lubricating oil to an oil sump. SUMMARY

[0004] The problem underlying the invention is solved by a drive unit for a vehicle according to the invention. Advantageous refinements of the invention include that the openings extend from the inner circumferential surface to the outer circumferential surface of the rotor shaft along the radial direction or at an angle to the radial direction, the openings on the end side are regularly distributed over the circumferential surface, the openings on the end side are configured as grooves, a lubricant output site is arranged in the transmission mechanism for introducing lubricant into the lubricant channel of the transmission shaft, a lubricant barrier cap is arranged in the lubricant channel on the end of the transmission shaft facing away from the rotor shaft, a support section is configured between the plug-in toothing and the axial end of the rotor shaft, in which the rotor shaft and the transmission shaft abut against one another, wherein grooves are configured in the support section on the transmission shaft and / or the rotor shaft, which extend between the plug-in toothing and the axial end of the rotor shaft, the transmission shaft passes through a rolling bearing arranged / mounted in the transmission mechanism housing, wherein the rotor shaft abuts indirectly or directly with the end side against the inner ring of the rolling bearing, a radial shaft seal ring is arranged in the region in which the rotor shaft and the transmission shaft are inserted into one another, which is mounted in the transmission mechanism housing.

[0005] According to the application, a drive unit for a vehicle is proposed, which has an electric machine with a rotor shaft and a transmission mechanism with a transmission shaft. The rotor shaft and the transmission shaft are inserted into one another (axially) and coupled by means of a plug-in toothing. A lubricant channel is configured in the transmission shaft, which opens into the interior space of the rotor shaft on the end (end side) facing the rotor shaft in order to supply the plug-in toothing with lubricant. The rotor shaft has an end side on the axial end facing the transmission shaft, wherein one or more openings are configured on the end side, which extend from the inner circumferential surface delimiting the interior space of the rotor shaft to the outer circumferential surface of the rotor shaft. The lubricant channel is thus fluidically connected via the interior space and the plug-in toothing to the openings. This fluidic connection guides the lubricant from the lubricant channel in the transmission shaft to the openings on the end side of the rotor shaft.

[0006] In this way, an improved lubrication and cooling of the plug-in toothing can be achieved. By means of the continued guiding of the lubricant to the openings on the end side, other transmission mechanism components can be lubricated and / or cooled. The construction of the lubricant flow by means of existing structural elements allows a higher degree of integration. This contributes to weight minimization, compact construction space and cost reduction.

[0007] The lubricant is transported along the fluidic connection, which has an approximately fork-shaped course. The lubricant is introduced into the lubricant channel and flows to the end of the transmission shaft facing the rotor shaft. There, the lubricant opens into the interior space of the rotor shaft (hollow section of the rotor shaft). When the rotor shaft or the transmission shaft is rotating, the lubricant is guided radially outward by centrifugal force to the plug-in toothing. From there, the lubricant is guided to the openings in the end side of the rotor shaft. Here, the lubricant flows for a distance against the direction of travel of the lubricant in the lubricant channel of the transmission shaft.

[0008] The electric machine can have a housing (motor housing). On the end facing away from the transmission mechanism, the electric machine or its housing can have a bearing cover with a rolling bearing in which the rotor shaft is supported. Possibly, no further bearing mechanism for the rotor shaft is provided in the electric machine.

[0009] The transmission mechanism can also have a housing (transmission mechanism housing). The motor housing and the transmission mechanism housing can each have a delimitation at which the motor housing and the transmission mechanism housing abut against one another. The delimitation can be arranged orthogonally to the central longitudinal axis of the rotor shaft or the transmission shaft, respectively. As an alternative, the motor housing and the transmission mechanism housing can be merged into one component or one housing, for example a housing or a system housing. The housing is then one component (not separated at the delimitation).

[0010] The drive shaft can be, for example, a transmission input shaft. The drive shaft can have a pinion which meshes or engages with a further transmission gear. The transmission housing can optionally be configured in multiple parts, for example with an (intermediate) housing section and a transmission cover.

[0011] The drive shaft can be supported by two rolling bearings. One rolling bearing can be arranged at or in the transmission housing, for example in the intermediate housing section, and the other rolling bearing can be arranged at or in the transmission cover.

[0012] The lubricant channel can extend completely through the drive shaft. The drive shaft can thus be configured as a hollow shaft. The drive unit can be configured, for example, as an E-shaft or form a component part of an E-shaft. The lubricant can be, for example, oil. The rotor shaft and the drive shaft are in particular arranged coaxially with one another.

[0013] In order to provide a plug-in toothing, the rotor shaft has an inner toothing on its inner circumferential face (axially sectionally) and the drive shaft has an outer toothing on its outer circumferential face (axially sectionally). If the rotor shaft and the drive shaft are inserted into one another, the outer toothing and the inner toothing mesh with one another. The rotor shaft and the drive shaft are thus coupled to one another in a torsionally rigid manner.

[0014] According to an improvement, the openings on the end side can extend from the inner circumferential face to the outer circumferential face of the rotor shaft along the radial direction or at an angle with respect to the radial direction. A conveying action is thus produced by the centrifugal force acting on the lubricant when the rotor shaft is rotated or when the drive shaft is rotated.

[0015] According to an improvement, the openings on the end side can be regularly distributed over the circumferential face, for example at the same spacing or at the same angle on the circumferential face of the rotor shaft. This facilitates uniform discharge of the lubricant.

[0016] According to an improvement, the openings on the end side can be configured as grooves. Grooves can be easily configured compared to drilled holes, for example. Only a relatively small weakening of the rotor shaft or of a hollow section of the rotor shaft is caused by the grooves.

[0017] According to an improvement, a lubricant output site can be arranged in the transmission for introducing lubricant into the lubricant channel of the drive shaft. The lubricant can thus be provided purposefully. The lubricant output site can be arranged on the end of the drive shaft which faces away from the rotor shaft, for example on the transmission cover side.

[0018] A lubricant can be fed to the lubricant output site by means of a lubricant output device (actively or passively). In order to actively deliver lubricant, a lubricant pump can be provided, which can be arranged, for example, in the transmission. In an embodiment without a lubricant pump (passive sump lubrication), the lubricant can be guided into the transmission shaft by means of a corresponding guide geometry (for example, configured in the housing).

[0019] According to an improvement, a lubricant barrier cap can be arranged in the lubricant channel on the end of the transmission shaft facing away from the rotor shaft. The lubricant barrier cap prevents lubricant or oil from running off on the end of the transmission shaft facing away from the rotor shaft. The lubricant barrier cap can have a circular ring profile. The lubricant barrier cap can be configured open-centrally, for example, with a central passage, in order to enable the introduction of lubricant.

[0020] According to an improvement, a support section can be configured (axially) between the plug-in toothing and the axial (towards the transmission shaft) end of the rotor shaft, in which support section the rotor shaft (with an inner circumference) and the transmission shaft (with an outer circumference) abut against one another, wherein grooves are configured on the transmission shaft and / or on the rotor shaft in the support section, which grooves extend between the plug-in toothing and the axial end of the rotor shaft. The grooves in the support section facilitate the delivery of lubricant from the plug-in connection to the openings or grooves in the end side of the rotor shaft. In particular, the grooves can extend parallel to the axial direction or at an angle to the axial direction or to a parallel line of the axial direction.

[0021] According to an improvement, the transmission shaft can pass through a rolling bearing arranged in or seated in the transmission housing, wherein the rotor shaft abuts indirectly (for example, by means of an intermediate ring seated on the transmission shaft) or directly on the inner ring of the rolling bearing with an end side (towards the transmission shaft). Thereby, the rotor shaft can be axially supported. Thus, by means of the support on the inner ring, the transmission of relative forces between the rotor shaft and the transmission shaft, for example, in the region of the plug-in toothing or the support section, is avoided.

[0022] According to an improvement, a radial shaft seal ring can be arranged in the region in which the rotor shaft and the transmission shaft are inserted into one another (axial overlap of the rotor shaft and the transmission shaft), which radial shaft seal ring is seated in the transmission housing. Thus, the lubricant can be used to lubricate the radial shaft seal ring. The lubricant can flow back into the oil sump of the drive unit or the transmission via the lubricant channel (oil hole) or through the rolling bearing. BRIEF DESCRIPTION OF DRAWINGS

[0023] Possible embodiments of the application are explained below with reference to the drawings. Therein:

[0024] Figure 1 a schematic sectional view through the drive unit is shown;

[0025] Figure 2 a schematic and enlarged partial section of the drive unit from Figure 1 in the region of the transmission shaft; and

[0026] Figure 3 a schematic perspective view of the rotor shaft of the drive unit from Figure 1 . DETAILED DESCRIPTION

[0027] The drive unit for a vehicle has the reference number 10 in general in Figure 1 . The drive unit 10 can be configured for example as an E-axle or form a component part of an E-axle.

[0028] The drive unit 10 has an electric machine 12 with a rotor shaft 14 and a transmission 16 with a transmission shaft 18. Furthermore, in the electric machine 12 a stator and a rotor coupled with the rotor shaft 14 can be arranged, the rotor having rotor components, for example a lamination stack with windings (not shown).

[0029] The electric machine 12 has a housing 20 (motor housing). On the end facing away from the transmission 16, the electric machine 12 or its housing 20 has in the present example a bearing cover 22 with a roller bearing 24 in which the rotor shaft 14 is supported (see Figure 1 ). In the present example, no other bearing arrangement for the rotor shaft 14 is provided in the electric machine 12.

[0030] The transmission 16 also has a housing 26 (transmission housing). In the present example, the motor housing 20 and the transmission housing 26 each have a boundary surface 28, 30 at which the motor housing 20 and the transmission housing 26 abut against one another. The boundary surfaces 28, 30 are each arranged in the present example orthogonally to a central longitudinal axis 32 (axial direction 32) of the rotor shaft 14 or the transmission shaft 18. As an alternative (not shown), the motor housing 20 and the transmission housing 36 can be combined into one component, for example one housing or one system housing (not divided at the boundary surface 28 / 30).

[0031] The transmission shaft 18 is a transmission input shaft. The transmission shaft 18 has in the present example a pinion 34 which meshes with further transmission gears (not shown). The transmission housing 26 is in the present example constructed in multiple parts and has a housing section 36 which adjoins the motor housing and a transmission cover 38.

[0032] The transmission shaft 18 is supported in the transmission housing 26 by two rolling bearings 40, 42. One rolling bearing 40 is arranged at or in the housing section 36 and the other rolling bearing 42 is arranged at or in the transmission housing cover 38.

[0033] The rotor shaft 14 and the transmission shaft 18 are inserted into each other (axially) and coupled by means of a plug-in toothing 44 (see Figure 2 ). The rotor shaft 14 and the transmission shaft 18 are arranged coaxially to each other. In the transmission shaft 18 a lubricant channel 46 is configured, which opens into an inner space 48 of the rotor shaft 14 on an end side facing the rotor shaft 14 in order to supply the plug-in toothing 44 with lubricant.

[0034] The rotor shaft 14 has an end side 50 on an axial end facing the transmission shaft 18, wherein one or more openings 52 are configured on the end side 50, which extend from an inner circumferential face 54 of the rotor shaft 14 to an outer circumferential face 56 thereof (see Figure 2 and 3 ). The lubricant channel 46 is thus fluidically connected via the inner space 48 and the plug-in toothing 44 with the openings 52. This fluidic connection guides lubricant from the lubricant channel 46 in the transmission shaft 18 to the openings 52 of the end side of the rotor shaft 14.

[0035] The lubricant channel 46 extends in the present example completely through the transmission shaft 18 (see Figure 2 ). The transmission shaft 18 is thus configured as a hollow shaft. The lubricant can be oil, for example.

[0036] The openings 52 extend from the inner circumferential face 54 to the outer circumferential face 56 of the rotor shaft 14 along or at an angle to the radial direction. Thus, a transport effect is generated by the centrifugal force acting on the lubricant when the rotor shaft 14 is turned or when the transmission shaft 18 is turned.

[0037] The openings 52 are regularly distributed on the circumferential face on the end side 50, for example at the same spacing or angle on the circumferential face of the rotor shaft 14 (see Figure 3 ). The openings 52 on the end side 50 are configured as grooves.

[0038] A lubricant output device (not shown) is arranged in the transmission, which serves to introduce lubricant into the lubricant channel 46 of the transmission shaft 18 at a lubricant output site 60 (see Figure 2 ). The lubricant output device is arranged on an end of the transmission shaft 18 facing away from the rotor shaft 14 (transmission housing cover side). The lubricant output device can be configured as described above.

[0039] In the lubricant channel 46, a lubricant barrier cap 62 is arranged on the end of the transmission shaft 18 which faces away from the rotor shaft 14. The lubricant barrier cap 62 has a circular ring-shaped contour which has a centrally arranged passage (no reference sign).

[0040] Between the plug-in toothing 44 and the axial end of the rotor shaft 14 (towards the transmission shaft 18), a support section 64 is configured in the axial direction, in which the rotor shaft 14 (with the inner peripheral surface 5) and the transmission shaft 18 (with the outer peripheral surface 66) abut against one another (see Figure 2 ). In the support section 64, grooves (not shown) can be configured on the transmission shaft 18 and / or on the rotor shaft 14, which extend between the plug-in toothing 44 and the axial end of the rotor shaft 14. The grooves extend in particular from the plug-in toothing towards the axial end of the rotor shaft, for example parallel to the axial direction 32 or at an angle with respect to the axial direction or to a parallel line to the axial direction 32.

[0041] The transmission shaft 18 passes through the rolling bearing 40 which is arranged or seated in the transmission housing 26, wherein the rotor shaft 14 directly abuts against the inner ring 68 of the rolling bearing 40 (see Figure 2 ).

[0042] In the region in which the rotor shaft 14 and the transmission shaft 18 are inserted into one another (axial overlap of the rotor shaft 14 and the transmission shaft 18), a radial shaft seal ring 70 is arranged in the transmission housing 26. Lubricant can thus be used to lubricate the radial shaft seal ring 70. The lubricant can flow back into the oil sump of the drive unit 10 or the transmission 16 or through the rolling bearing 40 (not shown in detail) via lubricant channels (oil holes).

[0043] The lubricant is conveyed along a fluid connection, for example with a hairpin-shaped or back-and-forth reciprocating course (see Figure 2 ). The lubricant is introduced into the lubricant channel 46 and flows towards the end of the transmission shaft 18 which faces the rotor shaft 14. There, the lubricant channel 46 opens into the interior space 48 of the rotor shaft 14 (hollow section of the rotor shaft), so that the lubricant reaches the interior space 48. Upon rotation of the rotor shaft 14 or the transmission shaft 18, the lubricant is directed radially outwards by centrifugal force to the plug-in toothing 44. From there, the lubricant is directed to the openings 52 in the end side 50 of the rotor shaft 14. Here, the lubricant flows for a distance against the direction of travel of the lubricant in the lubricant channel 46 of the transmission shaft 18.

Claims

1. A drive unit (10) for a vehicle, the drive unit having a motor (12) with a rotor shaft (14) and a transmission mechanism (16) with a drive shaft (18), characterized in that, The rotor shaft (14) and the drive shaft (18) are inserted into each other and coupled by means of interlocking teeth (44), wherein a lubricant channel (46) is constructed in the drive shaft (18), the lubricant channel opening into the internal space (48) of the rotor shaft (14) at its end toward the rotor shaft (14) to provide lubricant to the interlocking teeth (44), wherein the rotor shaft (14) has an end side (50) at its axial end toward the drive shaft (18), in which One or more openings (52) are constructed on the end side, the openings extending from the inner circumferential surface (54) of the inner space (48) of the rotor shaft (14) to the outer circumferential surface (56) of the rotor shaft, such that the lubricant channel (46) is fluidly connected to the opening (52) via the inner space (48) and the insert teeth (44), so that lubricant is guided from the lubricant channel (46) via the inner space (48) and the insert teeth (44) to the opening (52).

2. The driving unit (10) according to claim 1, characterized in that, The opening (52) extends from the inner circumferential surface (54) of the rotor shaft (14) to the outer circumferential surface (56) along the radial direction or at an angle relative to the radial direction.

3. The driving unit (10) according to claim 1 or 2, characterized in that, The openings (52) on the end side (50) are regularly distributed on the circumferential surface.

4. The driving unit (10) according to claim 1 or 2, characterized in that, The opening (52) on the end side (50) is constructed as a groove.

5. The driving unit (10) according to claim 1 or 2, characterized in that, A lubricant output section (60) is arranged in the transmission mechanism (16) for introducing lubricant into the lubricant channel (46) of the transmission shaft (18).

6. The driving unit (10) according to claim 1 or 2, characterized in that, A lubricant blocking cap (62) is arranged in the lubricant channel (46) at the end of the drive shaft (18) opposite to the rotor shaft (14).

7. The driving unit (10) according to claim 1 or 2, characterized in that, A support section (64) is constructed between the insertion tooth (44) and the axial end of the rotor shaft (14), in which the rotor shaft (14) and the drive shaft (18) abut against each other, wherein a groove is constructed in the support section (64) on the drive shaft (18) and / or the rotor shaft (14), the groove extending between the insertion tooth (44) and the axial end of the rotor shaft (14).

8. The driving unit (10) according to claim 1 or 2, characterized in that, The drive shaft (18) passes through a rolling bearing (40) arranged / placed in a transmission housing (26), wherein the rotor shaft (14) abuts against the inner ring (68) of the rolling bearing (40) indirectly or directly at the end side (50).

9. The driving unit (10) according to claim 1 or 2, characterized in that, A radial shaft sealing ring (70) is arranged in the region where the rotor shaft (14) and the transmission shaft (18) are inserted into each other, and the radial shaft sealing ring is placed in the transmission housing (26).

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