STATOR ARRANGEMENT WITH A COOLANT SYSTEM AND ELECTRIC MACHINE WITH THE STATOR ARRANGEMENT

Abstract

A stator assembly for an electric machine may have a stator including a stator core and a plurality of stator windings, which has a cooling system for cooling the stator, where the cooling system includes a cooling shell 10 encompassing the stator core, which is thermally coupled to the stator core, where the cooling system has a supply line connected to the cooling shell at the intake end and a return line connected to the cooling shell at the outlet end, where the cooling system has at least one coolant pump and one coolant container, where the coolant pump is connected to the supply line in the flow path between the coolant container and the cooling shell in order to supply coolant to the cooling shell through the supply line.

Claims

1. A stator assembly for an electric machine, comprising: a stator, the stator having a stator core and stator windings; and a cooling system for cooling the stator, wherein the cooling system includes a cooling shell at least partially encompassing the stator core and thermally coupled to the stator core, wherein the cooling system has a supply line connected to the cooling shell at an intake end and a return line connected to the cooling shell at an outlet end, wherein the cooling system has at least one coolant pump and one coolant container, wherein the coolant pump is connected to the supply line in a flow path between the coolant container and the cooling shell in order to supply coolant to the cooling shell through the supply line, and wherein the return line is connected in the flow path between the coolant container and the coolant pump such that the coolant pump is supplied with coolant from the return line.

2. The stator assembly according to claim 1, wherein a supply flow path runs from the coolant container through the supply line to an intake in the cooling shell, and wherein a return flow path runs from an outlet in the cooling shell through the return line and ends in the supply flow path.

3. The stator assembly according to claim 1, wherein the return line opens into or adjacent to a coolant pump at a suction point.

4. The stator assembly according to claim 1, wherein the cooling system includes a coolant tank that is connected in the flow path between the coolant container and the coolant pump, and wherein the return line opens into the coolant tank.

5. The stator assembly according to claim 4, wherein the cooling system has a second coolant pump, and wherein the second coolant pump is connected to a connecting line in the flow path between the coolant container and the coolant tank in order to supply coolant to the coolant tank through the connecting line.

6. The stator assembly according to claim 1, wherein the cooling shell is formed by a plurality of cooling channels that extend in an axial direction of the stator core, wherein the cooling channels are connected to the supply line in the flow path at a first axial end surface of the stator core through a first annular channel, and wherein the cooling channels are connected to the return line in the flow path at a second axial end surface of the stator core through a second annular channel.

7. The stator assembly according to claim 6, wherein the cooling channels each have a coolant intake and a coolant outlet, wherein the coolant intakes are connected to one another in the flow path at the first axial end surface through the first annular channel, and wherein the coolant outlets are connected to one another in the flow path at the second axial end surface through the second annular channel.

8. The stator assembly according to claim 6, wherein the first annular channel is at least partially formed by a first coolant guide ring and the second annular channel is at least partially formed by a second coolant guide ring, wherein the first coolant guide ring is supported on the first axial end surface of the stator core, and wherein the second coolant guide ring is supported on the second axial end surface of the stator core.

9. The stator assembly according to claim 1, wherein the supply line and return line in an intended installation state of the stator assembly are connected to the cooling shell at an upper surface of the stator core.

10. The stator assembly according to claim 1, further comprising a housing, wherein the supply line and/or return line are formed in the housing.

11. The stator assembly according to claim 1, wherein the stator windings form at least one winding head adjoining the stator core in the axial direction, and wherein the cooling system is configured to cool the at least one winding head.

12. The stator assembly according to claim 11, wherein the cooling system is configured to cool the at least one winding head with a minimal amount of coolant.

13. The stator assembly according to claim 11, wherein the first and/or second coolant guide ring has holes distributed over a circumference, such that a portion of the coolant conveyed in the supply line can be diverted toward the at least one winding head through the holes.

14. The stator assembly according to claim 13, wherein the first and/or second coolant guide rings are located on a radial outer surface of the at least one winding head, and wherein the holes are directed radially toward the winding heads to form a winding head shower.

15. An electric machine that has a stator assembly according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further features, advantages, and effects of the invention can be derived from the following description of preferred exemplary embodiments. Therein:

[0031] FIG. 1 shows a schematic illustration of an electric machine forming an exemplary embodiment of the invention;

[0032] FIG. 2 shows an illustration like that in FIG. 1 of an alternative embodiment of the electric machine;

[0033] FIG. 3 shows an illustration like that in FIG. 1 of another alternative embodiment of the electric machine;

[0034] FIG. 4 shows an axial view of the electric machine in a concrete structural embodiment;

[0035] FIG. 5 shows a cutaway illustration of the electric machine shown in FIG. 4; and

[0036] FIG. 6 shows another axial view of the electric machine shown in FIG. 4.

DETAILED DESCRIPTION

[0037] FIG. 1 shows a highly simplified illustration of an electric machine 1 as an exemplary embodiment of the invention. The electric machine 1 is designed and/or suitable for an electric vehicle. When operated as a motor, the electric machine 1 can be used as an electric motor for generating a drive torque, and when operated as a generator, the electric machine 1 can form a generator for generating electricity.

[0038] The electric machine 1 contains a stator assembly 2, which comprises a stator 3 and a cooling system 4 for cooling the stator 3. The electric machine 1 also contains a rotor 5, which can rotate in relation to the stator 3 about a main axis 100. The electric machine 1 is designed as an internal rotor machine in which the rotor 5 is located radially inside the stator 3.

[0039] The stator 3 is substantially composed of a stator core 6 with numerous stator windings 7 that form protruding winding heads 8, 9 above the end surfaces of the stator core 6.

[0040] The cooling system 4 has a cooling shell 10 that is thermally coupled to the stator core 6, formed on a radial outer surface of the stator core 6 such that it encompasses the main axis 100. The cooling shell 10 is formed by way of example by numerous cooling channels 11 running in an axial direction to the main axis 100, which pass through the stator core 6 in the same direction to one another. By way of example, the individual cooling channels 11 can each be formed by axial holes therein.

[0041] The cooling system 4 also contains a first and a second coolant guide ring 12, 13, in which the first coolant guide ring 12 is located on a first axial end surface of the stator core 6 to form a first annular channel 14, and the second coolant guide ring 13 is located on a second axial end surface of the stator core 6 to form a second annular channel 15. The two coolant guide rings 12, 13 are coaxial to the main axis 100 and supported axially on the respective end surfaces of the stator core 6 in a liquid-tight manner.

[0042] The electric machine 1 has a housing 16 in which the stator 3 and the rotor 5 are housed. The stator 3 can be permanently connected to the housing 16. The annular channels 14, 15 are delimited radially on one side by the respective associated coolant guide rings 12, 13 and on the other side by the housing 16, and axially on one side by the respective associated coolant guide rings 12, 13, and on the other side by the stator core 6. By way of example, the coolant guide rings 12, 13 can have an L-shaped cross section, in which the one leg is formed by a cylindrical shell for delimiting the respective annular channel 14, 15 in the radial direction, and the other leg is formed by a collar for delimiting the respective annular channel 14, 15 in the axial direction. By way of example, the two coolant guide rings 12, 13 can each be made of plastic and/or as identical parts.

[0043] The cooling system 4 also has a coolant container 17 and a coolant pump 18, which is connected in the flow path by a supply line 19 to the cooling shell 10 at an intake end. The cooling system 4 also has a return line 20, which is connected in the flow path to the cooling shell 10 at an outlet end.

[0044] The coolant container 17 forms a tank in which a coolant in the interior of the housing 16 is contained or collected. In a stationary installation state, a coolant sump 21 is formed in the coolant container 17, and the coolant pump 18 is connected to the supply line 19 such that a portion of the coolant is conveyed from the coolant sump 21 along a supply flow path 101 toward the cooling shell 20 and returned along a return flow path 102 to the supply flow path 101.

[0045] The supply line 19 is connected in the flow path to the first annular channel 14, and the coolant is distributed evenly to the cooling channels 11 through the first annular channel 12. The cooling channels 11 each open at a coolant intake 22 into the first annular channel 14, such that the coolant intakes 22 are connected to one another by the first annular channel 14 on the first axial end surface.

[0046] The return line 20 is connected in the flow path to the second annular channel 15, and the coolant is removed evenly from the cooling channels 11 through the second annular channel 13. The cooling channels each open with a coolant outlet into the second annular channel 15, such that the coolant outlets 23 are connected to one another by the second annular channel 14 on the second axial end surface.

[0047] In the stationary installation state of the electric machine 1, the supply line 19 and return line 20 are connected to an upper surface of the respective annular channels 14, 15. By way of example, the supply line 19 and return line 20 are located opposite one another at a 12 o'clock position, when seen along the circumference, in particular. The return of the coolant can therefore take place at the highest point, thus ensuring that the cooling shell 10 is always full of coolant, and that an optimal flow or heat dissipation of the stator core 6 can therefore be obtained. The uniform flow therethrough is also improved by the two coolant guide rings 12, 13.

[0048] The cooling system 4 is also designed to cool the winding heads 8, 9. The two coolant guide rings 12, 13 each have numerous radial holes 24 formed in the cylindrical shell in particular, which are spaced apart evenly along the circumference. The two coolant guide rings 12, 13 thus form a winding head shower, where the first coolant guide ring 12 is located on a radial outer surface of the first winding head 8, and the second coolant guide ring 13 is located on a radial outer surface of the second winding head 9. The holes 24 are each directed radially inward toward the respective winding heads 8, 9, such that they are supplied directly with coolant. By way of example, the holes 24 are designed such that the winding heads 8, 9 are sprayed with a fine mist formed by the coolant. The coolant diverted for the purpose of cooling the winding heads can be subsequently collected in the coolant container 17 and returned to the coolant pump 18.

[0049] The size of the holes 24 is such that no more than 30% of the coolant is diverted for cooling the winding heads 8, 9. In other words, if the cooling system 4 has a volumetric flow of 10 liters/minute, then a maximum volumetric flow of 1.5 liters/minute is allowed to flow through the holes in each of the first and second coolant guide rings 12, 13, thus forming a total maximum of 3 liters/minute that is diverted thereto. The remaining coolant can be returned to the cooling system 4 through the return line 20.

[0050] As can be seen in FIG. 1, the return line 20 is connected to a point 25 where the coolant pump 18 draws in fluid. The supply flow path 101 therefore runs from the coolant container 17 through the coolant pump 18 and the supply line 19 to the cooling shell 10 and return flow path 102 returns to the coolant pump 18 through the return line 20. By returning the remaining coolant, the pump can draw in coolant at the suction point 25, such that a liquid pressure is generated at this suction point 25 that is at least nearly equal, or equal, to the conveyance pressure generated by the coolant pump 18. By way of example, the coolant pump 18 can be a rotary vane pump. This significantly improves the efficiency of the coolant pump 18. Moreover, the winding head cooling obtained with the coolant guide rings 12, 13 can be set to a minimum, such that the coolant located in the interior of the housing 16, or the machine chamber, is reduced to a minimum. This can reduce the drag torque in the electric machine, in particular when coolant gets into the gap between the stator 3 and the rotor 5, and therefore improve the efficiency of the electric machine 1. This also ensures the reliability of the cooling system 4.

[0051] FIG. 2 shows an illustration like that in FIG. 1 of an alternative embodiment of the electric machine. The electric machine 1 substantially differs from the embodiment shown in FIG. 1 in that there is also a coolant tank 28 in the flow path between the coolant container 17 and the coolant pump 18. The cooling system 4 also has a second coolant pump 27, which is connected to a connecting line 28 in the flow path between the coolant container 17 and the coolant tank 26.

[0052] To form a coolant intake, the return line 20 and the connecting line 28 each open into the coolant tank 26, and the second coolant pump 27 is configured to supply the coolant tank 26 with coolant from the coolant container 17. The second coolant pump 27 is formed by at least one bilge pump, by way of example. To form a coolant outlet, the supply line 19 is connected to the coolant tank 26, and the coolant tank 18 is configured to supply the cooling shell 10 with coolant from the coolant tank 26. By returning the coolant directly to the coolant tank 26, the volume conveyed by the second coolant pump 27 is reduced, such that the second coolant pump 27 can be operated more efficiently. Moreover, the coolant is not sloshed around, and cannot be splashed away, thus improving the reliability of the coolant circulation. Furthermore, the coolant supply is ensured independently of the movement of the vehicle.

[0053] FIG. 3 shows an illustration like that in FIG. 1 of another alternative embodiment of the electric machine 1. The electric machine 1 substantially differs from the embodiment in FIG. 1 in that the return line 20 opens directly into the coolant container 17, in particular into the coolant sump 21. The coolant in the coolant container 17 can be conducted directly into another suction point 29 in the coolant pump 18, such that the reliability of the circulation can likewise be improved.

[0054] FIG. 4 shows the electric machine 1 described above in an axial view, in a concrete structural embodiment. The housing 16 is formed by a cast metal housing, and the supply line 19 is formed at least in part in the housing 16. The supply line 19 can be formed in this case by at least one hole 30 drilled in the housing 16, that opens into the first annular channel 22 at an upper surface of the stator core 6.

[0055] FIG. 5 shows the electric machine 1 described in reference to FIG. 4 in a longitudinal cut along the main axis 100. By way of example, the stator core 6 is a laminated metal core formed by numerous stator layers 31 laminated in the axial direction. The stator layers 31 have numerous axial holes, for example, that form the cooling channels 11.

[0056] The first and second coolant guide rings 12, 13 are formed in this embodiment by cylindrical sleeves, which are supported axially at one side on the end surface of the stator core 6 and at the other side on the housing 16. The two annular channels 14, 15 are therefore formed in the radial direction between the housing 16 and the respective coolant guide rings 12, 13, and in the axial direction between the housing 16 and the stator core 6. The electric machine 1 can consequently be significantly more compact.

[0057] FIG. 6 shows the electric machine 1 described in reference to FIG. 4 in another axial view. The electric machine 1 has the cooling system described in reference to FIG. 2 in this case, in which the coolant tank 26 is adjacent to the machine chamber in the housing 16. The return line 20 is formed at least in part in the housing 16, in that the return line 20 is formed by at least one second hole 32 drilled in the housing 16. The second hole 32 opens into the coolant tank 26, in particular at the top. By integrating the coolant tank 26 in the housing 16, a particularly space-saving electric machine 1 can be obtained.

REFERENCE SYMBOLS

[0058] 1 electric machine [0059] 2 stator assembly [0060] 3 stator [0061] 4 cooling system [0062] 5 rotor [0063] 6 stator core [0064] 7 stator winding [0065] 8 first winding head [0066] 9 second winding head [0067] 10 cooling shell [0068] 11 cooling channel [0069] 12 first coolant guide ring [0070] 13 second coolant guide ring [0071] 14 first annular channel [0072] 15 second annular channel [0073] 16 housing [0074] 17 coolant container [0075] 18 coolant pump [0076] 19 supply line [0077] 20 return line [0078] 21 coolant sump [0079] 22 coolant intake [0080] 23 coolant outlet [0081] 24 holes [0082] 25 suction point [0083] 26 coolant tank [0084] 27 second coolant pump [0085] 28 connecting line [0086] 29 second suction point [0087] 30 hole [0088] 31 stator laminate [0089] 32 second hole [0090] 100 main axis [0091] 101 supply flow path [0092] 102 return flow path