Disclosure of Invention
Starting from this, the object of the invention is to at least partially overcome the disadvantages known from the prior art. The features according to the invention result from the independent claims, for which advantageous embodiments are shown in the dependent claims. The features of the claims may be combined in any technically reasonable way, wherein the following description, including additional embodiments of the invention, as well as features from the drawings, may also be used for this purpose.
The invention relates to a stator unit of a drive unit, which stator unit has at least the following components:
-a first stator having an axially extending first stator coolant passage;
a second stator having an axially extending second stator coolant passage, and
-A stator housing;
wherein the first stator and the second stator are arranged axially in series.
In particular, the stator unit is characterized in that the stator unit has a central coolant supply which is arranged at least partially in the stator housing and which has a separate fluid connection to the first stator coolant passage and to the second stator coolant passage for the purpose of supplying the cooling fluid.
Unless explicitly stated otherwise, when axial direction, radial direction or direction of rotation and corresponding terms are used, reference is made below to the stated axis of rotation. Unless explicitly stated otherwise, ordinal numbers used in the foregoing and following description are for clarity of distinction only and do not indicate the order or hierarchy of the named components. An ordinal number greater than one does not necessarily mean that another such component must be present.
The stator unit proposed at present is designed as part of a drive unit and has at least a first stator, a second stator and a stator housing. In this context, the first stator has an axially extending first stator coolant passage. The second stator has an axially extending second stator coolant passage. The first stator and the second stator are axially connected in series, i.e. the first stator and the second stator are arranged axially one behind the other and do not overlap in the axial direction.
The stator unit has a central coolant supply that is at least partially disposed in the stator housing. In this respect, the central coolant supply has separate fluid connections to the first stator coolant passage and to the second stator coolant passage in order to supply the first stator and the second stator with cooling fluid by means of the central coolant supply.
For example, the drive unit is a drive unit of a motor vehicle, preferably a hybrid vehicle. For example, the drive unit is an electric transmission.
The two electric machines are generators and/or electrically driven machines. Preferably, the first electric machine is a generator and the second electric machine is an electrically driven machine. Both electric machines have a rotor receiving portion in which the rotor is rotatably received in each case in the mounted state. In an exemplary embodiment, the first rotor and the second rotor are non-rotatably connected to each other. In alternative exemplary embodiments, the first rotor and the second rotor may rotate relative to each other.
The rotor is preferably rotatable about a common rotation axis defining an axial direction. Preferably, the stators are arranged coaxially with each other and with the axis of rotation. For example, a stator includes a laminated core having stator slots and stator windings extending in the stator slots and wound around the laminated core.
For example, the magnetic field may be generated by supplying power to the stator windings. The rotor may be set to rotate or a magnetic field may be used in combination with the permanent magnets of the rotor to generate torque from the rotor. Alternatively or additionally, by rotating the rotor, an electric current may be induced in the stator windings by the interaction between the permanent magnets and the stator windings.
The conversion of current into torque or torque into current, also referred to as torque conversion in the following, generates heat. The heat is discharged by means of a cooling fluid. An axially extending stator coolant passage is provided in each stator for directing a cooling fluid through the stator.
Preferably, such cooling fluid is a dielectric fluid. Some components are denoted by the term "coolant", but this does not exclude embodiments in which the stator unit or the drive unit may be cooled with a refrigerant. Thus, the cooling fluid is a coolant or refrigerant. For example, the cooling fluid may be sub-cooled in a cooling unit.
It is now possible to supply the cooling fluid to both stator coolant channels via a common central coolant supply. Preferably, the central coolant supply is formed by or arranged in the stator housing. In this regard, the stator coolant passages each have a separate fluid connection to the central coolant supply. In this case, the term "alone" means that the cooling fluid does not pass through one stator coolant passage to reach the other stator coolant passage. For this purpose, the coolant supply is arranged centrally, preferably in the axial direction, between the two stators.
This means that two stators arranged axially in series can be cooled effectively. The stator may be cooled, in particular at hot spots, by means of a stator coolant passage.
In an advantageous embodiment of the stator unit, it is further proposed that the fluid connection at the two stator coolant passages is arranged in each case between the two stators in the axial direction.
According to this embodiment, the fluid connection between the central coolant supply and the stator coolant channels is arranged in each case between two stators in the axial direction. This means that the fluid connection is arranged in each case at one axial end or on one axial side of the respective stator coolant channel, which is aligned in the direction of the respective other stator. Preferably, the central coolant supply is arranged axially between the two stators, and the fluid connection is arranged axially outwardly from the two stators. This means that both stators or both stator coolant passages can flow from an axially central location to the outside.
Such an embodiment allows a simple and small part design of the stator unit.
In an advantageous embodiment of the stator unit it is further proposed that the first stator coolant channel comprises stator slots and/or stator holes in the first stator and/or that the second stator coolant channel comprises stator slots and/or stator holes in the second stator.
According to this embodiment, the first stator coolant passage comprises stator slots and/or stator holes. Alternatively or additionally, the second stator coolant passages include stator slots and/or stator holes.
Preferably, the stator slots and/or stator bores extend axially through the laminated core of the stator. Preferably, the cooling fluid flowing through the stator slots is thus in direct contact with the stator windings.
According to this embodiment, particularly efficient cooling may be achieved by flowing directly to the hottest spot of the stator.
In an advantageous embodiment of the stator unit, it is further proposed that the stator unit has at least one stator cover closing a stator wet chamber of a respective stator in the stator housing, wherein the at least one stator cover forms a coolant connection between the central coolant supply and a first stator coolant channel of the respective stator, wherein preferably the stator wet chamber is part of the coolant connection of the associated stator cover and is particularly preferably designed for distributing the cooling fluid in the circumferential direction.
According to this embodiment, the stator unit has at least one stator cover. The stator cover encloses the stator wet chamber of the associated stator in the stator housing. Further, the stator cover is formed with a coolant connection between the central coolant supply and the first stator coolant passage. In this respect, the stator wet chamber is preferably part of the coolant connection of the respective stator cover. The stator wet chamber is particularly preferably designed to distribute the cooling fluid in the circumferential direction.
The stator unit thus has a first stator cover, preferably an annular first stator cover, which closes off the first stator wet space of the first stator in the stator housing, and/or a second stator cover, preferably an annular second stator cover, which closes off the second stator wet space of the second stator in the stator housing. The stator covers are each arranged axially on the inner side of the respective stator, i.e. in the direction of the respective other stator.
In this regard, the first stator cover forms a first coolant connection between the central coolant supply and the first stator coolant passages, and/or the second stator cover forms a second coolant connection between the central coolant supply and the second stator coolant passages. Preferably, the first coolant connection and/or the second coolant connection has a tangential extension and/or an axial extension.
The first stator wet chamber and/or the second stator wet chamber are preferably part of the first coolant connection or the second coolant connection, and are particularly preferably designed to distribute the cooling fluid in the circumferential direction, i.e. before the cooling fluid enters the respective stator or the respective stator coolant channel.
Preferably, at least one stator cover is provided for each stator.
In an advantageous embodiment of the stator unit, it is further proposed that at least one stator cover is clamped under preload between the stator housing and the respective stator, and wherein preferably the at least one stator cover is C-shaped in cross section, said at least one stator cover being made of plastic and/or comprising a rubber sealing ring by means of which the same stator cover is sealed against the stator housing or stator in order to generate at least part of the preload.
According to this embodiment, at least one stator cover is under preload. For example, the stator cover is clamped between the respective stator and the stator housing, so that a preload is thereby generated.
Preferably, the stator cover has a shape that achieves or improves the spring effect and at the same time defines a stator wet chamber. For example, the cross section of the stator cover is C-shaped when viewed in tangential direction, or the cross section of the annular stator cover is C-shaped.
Preferably, the stator cover is made of a material that achieves or improves the spring effect. Such a material is preferably elastic, generates a high restoring force in the case of elastic deformation and exhibits low relaxation. One such material is, for example, plastic.
Preferably, the at least one stator cover comprises at least one rubber sealing ring which is arranged circumferentially between the stator cover and the stator housing and seals the stator cover and the stator housing relative to each other. Alternatively or additionally, the at least one stator cover comprises at least one rubber sealing ring which is arranged circumferentially between the stator cover and the respective stator and seals the stator cover and the respective stator with respect to each other. Preferably, such a rubber sealing ring is arranged between the laminated core of the stator and the stator cover. The rubber sealing ring is particularly preferably arranged radially outside the stator wet chamber.
In an advantageous embodiment of the stator unit, it is further proposed that the central coolant supply comprises a radial section which extends from a radially outer side to a radially inner side, preferably up to a fluid connection with the at least one stator cover, and which is arranged in the axial direction between the first stator and the second stator.
According to this embodiment, a radially extending radial section of the coolant supply is arranged axially between the two stators.
Preferably, the radial section of the coolant supply extends from a radially outer side to a radially inner side up to a radius on which the at least one coolant connection is arranged. In a preferred embodiment, if one coolant connection is provided for each stator, the radial section preferably extends up to a radius at which one of the coolant connections, preferably the radially inner one of the two coolant connections, is arranged.
In an advantageous embodiment of the stator unit, it is further proposed that the first stator and the second stator are axially spaced apart from each other by an axial intermediate space in which an intermediate housing section of the stator housing is arranged, which intermediate housing section extends radially and on which the at least one stator cover is preferably supported.
According to this embodiment, the first stator and the second stator are axially spaced apart from each other such that an axial intermediate space is arranged between the first stator and the second stator. A radially extending intermediate housing section is arranged in the axial intermediate space between the two stators. The intermediate housing section thus axially divides the receiving space of the stator housing into two sections, in each of which the stator is received. For example, two stators may be pushed into the stator housing from opposite axial sides for assembly. For example, the respective stator cover is placed on the stator in a preassembly step.
Preferably, the stator cover is in axial contact with or pressed against the intermediate housing section in order to provide the preload.
For example, a part of the radial section of the central coolant supply is arranged in the intermediate housing section. Preferably, a portion of the radial section is formed by the intermediate housing section.
In an advantageous embodiment of the stator unit, it is further proposed that at least one stator cover is arranged in the axial intermediate space, in which the first stator cover and/or the second stator cover is arranged.
According to this embodiment, at least one stator cover is now arranged in the axial intermediate space, preferably both stator covers are arranged in the axial intermediate space. In this respect, the stator cover preferably rests with the side facing away from the respective stator against the middle housing section of the stator housing or presses against the middle housing section of the stator housing in order to generate the preload.
In an alternative exemplary embodiment, the stator covers are pressed against each other with the sides facing away from the stator respectively. This exemplary embodiment may also be used to provide a preload to the stator cover.
In an advantageous embodiment of the stator unit, it is further proposed that a fluid flow regulating unit is arranged between at least one of the two stator coolant passages and the central coolant supply, by means of which a distribution of the cooling fluid between the first stator and the second stator can be defined, wherein the fluid flow regulating unit is preferably a restrictor.
According to this embodiment, a first fluid flow regulating unit is arranged between the first stator coolant passage and the central coolant supply and/or a second fluid flow regulating unit is arranged between the second stator coolant passage and the central coolant supply. Thus, there is at least one, preferably at least two, particularly preferably exactly two fluid flow regulating units. By means of at least one fluid flow regulating unit, the distribution of cooling fluid between the first stator and the second stator may be defined.
Preferably, the at least one fluid flow regulating unit is a restrictor. In such an exemplary embodiment, the distribution of the cooling fluid to the two stators is passively defined by the flow cross section of the at least one restrictor.
Alternatively, at least one fluid flow regulating unit is a controllable valve. In such exemplary embodiments, the cooling fluid flowing through the first stator or the second stator may be actively controlled.
According to another aspect, a drive unit is proposed, which has at least the following components:
-a stator unit according to an embodiment as described above;
-a first rotor magnetically connected with the first stator for torque conversion;
-a second rotor magnetically connected with the second stator for torque conversion;
a first shaft connected to the first rotor in a torque transmitting manner, and
-A second shaft connected in torque transmitting manner to the second rotor.
According to this aspect, a drive unit is now proposed, which has a stator unit, a first rotor, a second rotor and at least one shaft which is connected to one rotor or in each case to one rotor in a torque-transmitting manner.
In this context, the stator unit is a stator unit as described above. Preferably, the drive unit has a first shaft which is connected to the first rotor in a torque-transmitting manner, and a second shaft which is connected to the second rotor in a torque-transmitting manner.
For example, the drive unit is a drive unit of a motor vehicle, preferably a hybrid vehicle. For example, the drive unit is an electric transmission.
Preferably, at least one of the shafts is a hollow shaft in which the respective other shaft is rotatably received. Preferably, an axial coolant line is formed in at least one of the two shafts, preferably at least in the interior of the two shafts, by means of which the first rotor and/or the second rotor can be cooled.
For example, branch lines are formed from the axial coolant lines in order to cool the rotor.
In an advantageous embodiment of the drive unit, it is further proposed that the first electric machine comprising the first rotor and the first stator is an electric generator and the second electric machine comprising the second rotor and the second stator is a drive machine.
Detailed Description
Fig. 1 shows a perspective cross-section of a drive unit 2 with a stator unit 1 and a rotor unit. The cross-sectional view shows the drive unit 2 seen in a direction orthogonal to the axial direction. Here, the cross section through the stator housing 7 of the stator unit 1 does not extend along a straight plane, but the stator housing 7 is further partially cut out in order to improve visibility.
The stator unit 1 includes a first stator 3 and a second stator 4. The rotor unit comprises a first rotor 22 having a first shaft 24 and a second rotor 23 having a second shaft 25. In this respect, the first rotor 22 is in torque-converting connection with the first stator 3 and the second rotor 23 is in torque-converting connection with the second stator 4. The term "torque conversion" is understood herein to mean that a current may be converted to a torque or that a torque may be converted to a current. Preferably, the electric machine 26 comprising the first stator 3 and the first rotor 22 is designed to convert the torque in the first rotor 22 into a current in the first stator 3. In this context, the second electric machine 27 is designed to convert the current in the second stator 4 into a torque in the second rotor 23. In other words, the first motor 26 is a generator and the second motor 27 is a drive machine. In the drawing, the first motor 26 is shown on the left side, and the second motor 27 is shown on the right side.
By means of such a drive unit 2, for example, an electric transmission can be realized which is designed to convert an input torque at the generator into an output torque at the drive machine by intermediate conversion into an electric current.
The two stators 3, 4 comprise a laminated core 32 comprising a plurality of stator laminations. For example, the stator laminations are annularly arranged and form stator teeth around which the stator windings 33 are wound. In the axial direction, the stator windings 33 extend correspondingly through stator slots 9, which are formed between the stator teeth.
The two rotors 22, 23 each comprise permanent magnets and are each connected to a shaft 24, 25 in a torque-transmitting manner. As shown, the first shaft 24 of the first rotor 22 is arranged inside the second shaft 25. The two shafts 24, 25 are designed as hollow shafts. An axial coolant line 28 is disposed in a corresponding cavity of the first shaft 24. The first shaft 24 is arranged in a corresponding cavity of the second shaft 25.
The stator housing 7 has an intermediate housing section 19 which axially divides the stator housing 7 into two sections. One of the two stators 3,4 is arranged in each of the two sections, respectively. The two stators 3,4 comprise stator wet chambers 12, 13. The stator wet chambers 12, 13 are preferably fluid tight sealed from the environment and are designed to receive a cooling fluid. The cooling fluid is preferably a dielectric liquid and is transported in the cooling circuit, for example using a pump and sub-cooling means.
The cooling fluid is supplied to the stators 3, 4 via the central coolant supply 8. The central coolant supply 8 extends through the stator housing 7. The stator coolant passages 5, 6 of the stators 3, 4 have fluid connections with the coolant supply 8 by means of respective coolant connections 14, 15. Thus, the first coolant connection 14 connects the central coolant supply 8 to the first stator coolant passages 5 and the second coolant connection 15 connects the central coolant supply 8 to the second stator coolant passages 6 (not shown herein; see, e.g., fig. 6).
The central coolant supply 8 has a radial section 17 in the stator housing 7. The two axial sections branch off from the radial section 17 at the radially inner end in opposite directions. The two axial sections are then correspondingly coolant connections 14, 15. The radial section 17 is correspondingly arranged in the axial direction between the two stators 3, 4.
The stator coolant passages 5, 6 extend axially through the respective stator 3, 4. In the shown preferred embodiment, the stator coolant passages 5, 6 are arranged in stator slots 9 or are formed by stator slots 9. Alternatively or additionally, further stator passages are provided in the stators 3,4, by means of which the cooling fluid can pass through the stators 3,4 in the axial direction. For example, additional holes are arranged in the stator laminations or the laminated core 32.
In each case, the stator wet chambers 12, 13 of the stators 3, 4 are closed off by the stator covers 10, 11 in the axial direction. The stator covers 10, 11 are arranged axially between the two stators 3, 4, i.e. axially in the axial intermediate space 18.
The stator covers 10, 11 are axially supported between the respective stator 3,4 and the intermediate housing section 19. This allows for easy assembly and sealing of the stator wet chambers 12, 13.
The first coolant connection 14, which connects the first stator wet chamber 12 to the central coolant supply 8, is also connected to the rotor coolant supply 29 as shown. The rotor coolant supply 29 is guided radially outwards here through the first stator 3 and radially inwards at the outer axial end of the drive unit 2, which is shown on the left, in order to be connected to the rotor cooled there.
Fig. 2 shows a detailed view of the cross-sectional view according to fig. 1. Only the half of the substantially rotationally symmetrical drive unit 2 above the rotation axis 31 is shown here. In this regard, reference is made to the description above. Further, indication lines for the cross-sectional views shown in fig. 3 and 4 are also shown.
Fig. 3 shows a cross-sectional view of the drive unit 2 from fig. 1. The viewing direction shown here is aligned parallel to the axis of rotation 31. In this respect, the cross section extends through the first stator 3 along the left-hand cross section line shown in fig. 2.
Fig. 4 shows a cross-sectional view of the drive unit 2 from fig. 1. The viewing direction shown here is aligned parallel to the axis of rotation 31. In this respect, the section extends through the second stator 4 along the right-hand section line shown in fig. 2.
Fig. 5 shows a detailed view from the cross-sectional view of fig. 1. The sealing of the stator wet chamber with respect to the stator lamination of the stator 3, 4 is particularly noticeable here. For this purpose, in each case a rubber sealing ring 16 is arranged between the first laminated core 32 of the stator 3 and the first stator cover 10 and between the laminated core 32 of the second stator 4 and the second stator cover 11. The stator wet chambers 12, 13 are sealed by the preload of the stator covers 10, 11, as described above.
Fig. 6 shows an exploded view of the first stator 3 and the second stator 4 of the stator unit 1 according to fig. 1. Here, compared to fig. 1, the view is rotated such that the first stator 3 is arranged on the left side and the second stator 4 is arranged on the right side. In particular, the arrangement of the coolant connections 14, 15 can be seen in the drawing. Furthermore, it can be seen that the annular stator covers 10, 11 form a wet chamber around the stator windings 33, so that these stator windings can be cooled by means of a cooling fluid. The stator windings 33 extend in the axial direction through the likewise identifiable stator slots 9, and the cooling fluid can be conducted through the stators 3,4 in the axial direction along the stator windings 33.
As shown, the cooling fluid is supplied to the stator wet chambers 12, 13 in a generally tangential direction. This results in a good distribution of the cooling fluid over the circumference of the stator 3, 4 or the stator wet chamber 12, 13 and thus in a uniform flow of the cooling fluid through all the stator slots 9.
The rotors 22, 23 are not shown here, so that the rotor receptacle 30 of the stator unit 1 is empty.
Fig. 7 shows a perspective view of the second stator cover 11 of the drive unit 2 according to fig. 1. For example, the second stator cover 11 is made of plastic and has a tangential inlet area as coolant connection 15. The external ribs stabilize the second stator cover 11.
Fig. 8 shows a detailed view of the second stator cover 11 from fig. 7. The second stator cover 11 is shown here as seen from the second stator wet chamber 13. Thus, a U-shaped cross section of the second stator cover 11 can be seen. The passive restrictor 21, which has a reduced flow cross section compared to the second coolant connection 15, defines how much cooling fluid flows into the second stator cover 11 and thus into the second stator wet chamber 13 and through the second stator 4 during operation.
Fig. 9 shows a further detailed view of the second stator cover 11 according to fig. 7 in a sectional view. The figure clearly shows that the second restrictor 21 narrows the flow cross section.
Fig. 10 shows a perspective view of the first stator cover 10 of the drive unit 2 according to fig. 1. For example, the first stator cover 10 is made of plastic and has a tangential inlet area as coolant connection 14. The external ribs stabilize the first stator cover 10.
The rotor coolant supply 29 further branches from the first coolant connection 14.
Fig. 11 shows a detailed view of the first stator cover 10 from fig. 10. The first stator cover 10 is shown here as viewed from the first stator wet chamber 12. Thus, the C-shaped cross-section of the first stator cover 10 can be identified in the tangential viewing direction. The passive restrictor 20, which has a reduced flow cross section compared to the first coolant connection 14, defines how much cooling fluid flows into the first stator cover 10 and thus into the first stator wet chamber 12 and through the first stator 3.
Fig. 12 shows a further detailed view of the first stator cover 10 according to fig. 7 in a sectional view. The figure clearly shows that the first restrictor 20 narrows the flow cross section.
The proposed stator unit is particularly inexpensive to manufacture and allows for efficient cooling of the components of the stator unit.
List of reference numerals
1. Stator unit
2. Driving unit
3. First stator
4. Second stator
5. First stator coolant passage
6. Second stator coolant passage
7. Stator housing
8. Coolant supply unit
9. Stator groove
10. First stator cover
11. Second stator cover
12. First stator wet chamber
13. Second stator wet chamber
14. First coolant connection
15. Second coolant connection
16. Rubber sealing ring
17. Radial segment
18. Intermediate space
19. Intermediate housing section
20. First flow restrictor
21. Second flow restrictor
22. First rotor
23. Second rotor
24. First shaft
25. Second shaft
26. First motor
27. Second motor
28. Coolant line
29. Rotor coolant supply
30. Rotor receiving portion
31. Axis of rotation
32. Laminated core
33. Stator winding