Method for cooling an electrical machine, and an electrical machine applying the method

Abstract

A method for cooling an electrical machine includes the following steps: guiding a coolant in an axial coolant supply line which is arranged in the rotor shaft, and conducting the coolant into an interior chamber of the electrical machine via a radial coolant supply line which is connected in a coolant-conducting manner to the axial coolant supply line. The electrical machine has an axial coolant supply line and at least one radial coolant supply line connected in a coolant-conducting manner to the axial coolant supply line, both of which are arranged in the rotor shaft. An interior chamber of the electrical machine is connected in a coolant-guiding manner to the radial coolant supply line.

Claims

1. A method for cooling an electrical machine having a rotor arranged on a rotor shaft for rotation therewith, and having a stator, the method comprising the steps of: a) guiding a coolant expelled via an expelled coolant line of a transmission of the electrical machine to a coolant pump that supplies the coolant in parallel to both an input coolant line of the transmission and to an axial coolant supply line arranged in the rotor shaft, wherein the axial coolant supply line is introduced to the rotor shaft via a coolant inlet stub at least partially disposed within the transmission and axially aligned with the rotor shaft; and b) introducing the coolant into an interior chamber of the electrical machine via a radial coolant supply line which is connected in a coolant-conducting manner to the axial coolant supply line and is arranged in the rotor shaft, wherein at least the rotor is arranged in the interior chamber, the rotor comprises a laminated rotor core comprising a stack of individual rotor laminations, the radial coolant supply line is disposed substantially in axial alignment with at least one lamination intermediate space disposed between the individual rotor laminations of the stack, and the coolant introduced into the interior chamber of the electrical machine via the radial coolant supply line is conveyed through the at least one lamination intermediate space.

2. The method according to claim 1, wherein the coolant is an electrically non-conducting coolant.

3. The method according to claim 2, wherein the coolant is a transmission oil.

4. The method according to claim 1, wherein the laminated rotor core of the rotor and/or at least one end side of the rotor are acted upon with the coolant.

5. The method according to claim 1, wherein during a rotational movement of the rotor, the coolant in the interior chamber and/or in the radial coolant supply line is transported radially outward by centrifugal force.

6. The method according to claim 5, wherein the coolant is transported through the rotor or along at least one end side of the rotor.

7. The method according to claim 6, wherein the coolant is transmitted from the rotor onto the stator.

8. The method according to claim 1, wherein the coolant is guided in a coolant circuit.

9. The method according to claim 8, wherein a coolant cooler is arranged in the coolant circuit.

10. The method according to claim 1, wherein the coolant is used for cooling and/or lubricating a bearing of the rotor.

11. An electrical machine, comprising: a rotor arranged on a rotor shaft for rotation therewith; a stator; a coolant pump to supply coolant in parallel to both an input coolant line of a transmission and to an axial coolant supply line arranged in the rotor shaft, wherein the axial coolant supply line is introduced to the rotor shaft via a coolant inlet stub at least partially disposed within the transmission and axially aligned with the rotor shaft; at least one radial coolant supply line connected in a coolant-conducting manner to the axial coolant supply line; an expelled coolant line connected in the coolant-conducting manner via the coolant pump to the axial supply line and the input coolant line to convey expelled coolant from the transmission of the electrical machine; and an interior chamber of the electrical machine connected in a coolant-guiding manner to the at least one radial coolant supply line, wherein the rotor comprises a laminated rotor core comprising a stack of individual rotor laminations, and the radial coolant supply line is disposed substantially in axial alignment with at least one lamination intermediate space disposed between the individual rotor laminations of the stack.

12. The electrical machine according to claim 11, wherein a plurality of radial coolant supply lines are arranged in the rotor shaft.

13. The electrical machine according to claim 12, wherein either two, four, six or eight radial coolant supply lines are provided.

14. The electrical machine according to claim 12, wherein at least two of the radial coolant supply lines are arranged axially outside the rotor on an outer side on opposite axial sides of the rotor.

15. The electrical machine according to claim 11, wherein an electrically non-conducting coolant is arranged in the axial coolant supply line, in the radial coolant supply line and/or in the interior chamber.

16. The electrical machine according to claim 11, wherein the rotor is arranged in the interior chamber.

17. The electrical machine according to claim 16, wherein the stator is also arranged in the interior chamber.

18. The electrical machine according to claim 11, wherein the axial coolant supply line and the radial coolant supply line are components of a coolant circuit which comprises a coolant cooler.

19. The electrical machine according to claim 11, wherein the axial coolant supply line, the rotor, the stator and/or a bearing of the rotor are arranged in a coolant-permeable manner with respect to one another.

20. A method for cooling an electrical machine having a rotor arranged on a rotor shaft for rotation therewith, and having a stator, the method comprising the steps of: a) guiding a coolant in an axial coolant supply line which is arranged in the rotor shaft, wherein the axial coolant supply line is introduced to the rotor shaft via a coolant inlet stub at least partially disposed within a transmission and axially aligned with the rotor shaft; and b) introducing the coolant into an interior chamber of the electrical machine via a radial coolant supply line which is connected in a coolant-conducting manner to the axial coolant supply line and is arranged in the rotor shaft, wherein at least the rotor is arranged in the interior chamber, the rotor comprises a laminated rotor core comprising a stack of individual rotor laminations, the radial coolant supply line is disposed substantially in axial alignment with at least one lamination intermediate space disposed between the individual rotor laminations of the stack, and the coolant introduced into the interior chamber of the electrical machine via the radial coolant supply line is conveyed through the at least one lamination intermediate space.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 schematically shows an electrical machine according to an embodiment of the invention with which a method for cooling an electrical machine can be carried out.

DETAILED DESCRIPTION OF THE DRAWING

(2) FIG. 1 shows a drive unit with an electrical machine 10 which is designed in the example illustrated as an electric motor, and a transmission 12 connected to said electrical machine.

(3) The electrical machine 10 comprises a stator 14 and a rotor 18 arranged on a rotor shaft 16 for rotation therewith. The rotor shaft 16 is mounted rotatably here in a housing 20 via a first bearing 22 and a second bearing 24.

(4) Both the stator 14 and the rotor 18 are arranged in an interior chamber 26 of the housing 20.

(5) For the cooing of the electrical machine 10, an axial coolant supply line 28 which, in the embodiment illustrated, is designed as a blind bore is arranged in the rotor shaft 16. The coolant supply line 28 is connected in a coolant-conducting manner to a coolant inlet stub 30 via which said coolant supply line is supplied with coolant.

(6) Furthermore, the rotor shaft 16 comprises a first radial coolant supply line 32, a second radial coolant supply line 33, a third radial coolant supply line 34 and a fourth radial coolant supply line 35.

(7) The first radial coolant supply line 32 and the second radial coolant supply line 33 are radially continuous here.

(8) The radial coolant supply lines 32-35 are connected in a coolant-conducting manner to the axial coolant supply line 28 and in a coolant-guiding manner to the interior chamber 26.

(9) The first radial coolant supply line 32 is arranged axially outside the rotor 18 in such a manner that it borders the outer side of an axial end side 36 of the rotor 18. The second radial coolant supply line 33 is arranged on an opposite side of the rotor 18 in such a manner that it borders the outer side of an opposite end side 38 of the rotor 18.

(10) In the embodiment illustrated, the rotor 18 is designed as a laminated rotor. The rotor 18 therefore comprises a laminated rotor core 39 consisting of a plurality of laminations.

(11) The third and fourth radial coolant supply lines 34, 35 are arranged here in such a manner that they are connected in a coolant-conducting manner to in each case one lamination intermediate space 40, 41 of the laminated rotor 18.

(12) An electrically non-conductive coolant which, in the embodiment illustrated, is a transmission oil is guided in the axial coolant supply line 28 and the radial coolant supply lines 32-35 and also in the interior chamber 26. The coolant is not illustrated specifically.

(13) The axial coolant supply line 28 and the radial coolant supply lines 32-35 are parts of a coolant circuit which also comprises a coolant sump 42, a coolant pump 44, a coolant reservoir 46 and a coolant cooler 48.

(14) The course of the coolant through the coolant inlet stub 30 and the axial coolant supply line 28 are illustrated by an arrow 50a. The course of the coolant through the first radial coolant supply line 32 is depicted by arrows 50b and 50c, the course of the coolant through the second radial coolant supply line 33 by arrows 50d and 50e.

(15) The path of the coolant through the third and fourth coolant supply line 34, 35 is not illustrated in detail, but takes place analogously to the arrows 50b and 50d.

(16) The axial coolant supply line 28, the rotor 18, the stator 14, the bearing 22 and/or the bearing 24 are therefore each arranged in pairs in a coolant-permeable manner with respect to one another.

(17) The draining of the coolant via the coolant sump 42 is symbolized by arrows 50f and 50g and the connecting line between the coolant sump 42 and the coolant pump by an arrow 50h.

(18) An inlet and an outlet of the coolant reservoir 46 are illustrated by arrows 50i and 50j.

(19) The coolant-conducting connection of the coolant pump 44 to the coolant cooler 48 is illustrated by an arrow 50k.

(20) Since the coolant in the embodiment illustrated is a transmission oil, the drive unit also comprises a coolant line which connects the coolant cooler 48 to the transmission 12. Said coolant line is illustrated by an arrow 50l.

(21) The coolant line by means of which the coolant is introduced from the transmission 12 into the coolant pump 44 is symbolized by an arrow 50m.

(22) The cooling of the electrical machine 10 takes place as follows.

(23) First of all, the coolant is introduced via the coolant inlet stub 30 into the axial coolant supply line 28. From there, it is introduced via the radial coolant supply lines 32-35 into the interior chamber 26 of the electrical machine, in which interior chamber the rotor 18 and the stator 14 are arranged.

(24) Via the radial coolant supply lines 32-35, the end sides 36, 38 of the rotor 18 and also the laminated rotor core 39 of the rotor 18, more precisely the lamination intermediate spaces 40 and 41, are acted upon with coolant.

(25) When the rotor 18 rotates, the coolant is transported radially outward by a centrifugal force arising because of the rotational movement.

(26) This applies in particular to the coolant present in the radial coolant supply lines 32-35. The coolant present in the radial coolant supply lines 34, 35 is transported radially outward through the rotor 18. Heat is transmitted here from the rotor 18 to the coolant, which is illustrated by arrows 52a, 52b.

(27) The coolant present in the radial coolant supply lines 32 and 33 is transported radially outward via the end sides 36, 38. Heat is likewise transmitted here from the rotor 18 to the coolant. This is symbolized by arrows 52c and 52d.

(28) In addition, during rotation of the rotor 18, coolant is transmitted from the rotor 18 to the stator 14. This preferably takes place portion by portion, for example by coolant being sprayed from the rotor 18 onto the stator 14.

(29) The coolant can then absorb heat from the stator 14. This is depicted by arrows 54a and 54b.

(30) The coolant is also used for cooling and/or lubricating the bearings 22, 24.

(31) Finally, the coolant is supplied via the coolant sump 42 and the coolant pump 44 to the coolant cooler 48. The coolant is then introduced again via the coolant inlet stub 30 into the rotor shaft 16. The coolant circuit is therefore closed.

(32) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.