GUIDE DEVICE FOR COOLING FLUID FLOWING AROUND A WINDING HEAD OF AN ELECTRIC MACHINE AND ELECTRIC MACHINE

Description

[0001] The invention relates to an electrical machine with a guide device for cooling fluid flowing around the winding heads of the electrical machine.

[0002] DE 10 2017 107 165 A1 discloses an electric machine for a vehicle comprising a stator, end windings extending on an end face of a core of the stator, and a cooling tunnel for a cooling fluid surrounding the end windings.

[0003] EP 2 461 463 A1 discloses a rotating electric machine comprising a stator having a stator core and a stator coil, and a guide member arranged along at least a portion of a coil end protruding from the stator core to allow a cooling medium to flow along the coil end. Above a horizontal plane containing a rotating shaft, the guide member is arranged on the inner circumference of the coil end.

[0004] When electrical machines are operated, stator windings heat up due to their ohmic resistance. The higher the current injected into the electrical machine, the greater the losses that cause this heating. It is well known that stator windings can be cooled using a cooling fluid. It has already been proposed to apply the cooling fluid as a jet to the winding heads for cooling.

[0005] Document DE 10 2017 211 135 A1 discloses an electrical machine with a housing in which a stator with multiple winding heads is arranged. The housing has a cooling channel through which a cooling medium flows. The cooling channel has a circular or circular segment-shaped annular channel section, through which the cooling medium can be sprayed onto some of the winding heads through several openings. A winding head located below is covered by the cooling medium collecting in an oil sump.

[0006] However, when spraying the winding ends of such an electrical machine, the cooling fluid reaches the shaft and is distributed within the electrical machine as the shaft rotates. The cooling fluid can then enter an air gap between the rotor and stator of the electrical machine and cause undesirable drag torques.

[0007] The invention is therefore based on the object of providing a possibility for improved distribution of a cooling fluid in an electrical machine.

[0008] This object is achieved according to the invention by an electrical machine according to claim 1. Advantageous embodiments are the subject of the dependent claims.

[0009] The invention is based on the idea of ​​guiding the cooling fluid circumferentially around the shaft and, in particular, also around an air gap between a stator and a rotor of the electric machine by means of the guide element, so that undesired distribution of the cooling fluid through the rotating shaft and penetration into the air gap is inhibited or completely suppressed. This improves the distribution of the cooling fluid in the electric machine; undesired drag losses during operation of the electric machine can be reduced or completely avoided.

[0010] Typically, the cooling fluid is a cooling liquid, in particular a cooling oil.

[0011] The second guide element serves to collect the cooling fluid flowing towards a machine base by gravity after flowing down from the first guide element and to allow it to flow around the lower winding heads of the stator windings for heat dissipation.

[0012] In this context, it is preferred if the respective centers in the circumferential direction of the guide elements are arranged so as to be connectable by a straight line intersecting the center of the recess.

[0013] Because, according to the invention, the outlet opening for the cooling fluid is formed in the center region in the circumferential direction of the second guide element, the cooling fluid can be effectively discharged upon reaching a lowest point of the second guide element. Preferably, the second guide element has a radial recess that opens into the outlet opening formed in the body.

[0014] According to an advantageous embodiment of the guide device, a radially outward-facing elevation is formed at the free end of the first guide element and / or a radially inward-facing elevation is formed at the free end of the second guide element. The elevation gives the corresponding guide element a trough-like structure, which, in the case of the first guide element, further inhibits or prevents the cooling fluid from penetrating the air gap and, in the case of the second guide element, inhibits or prevents the cooling fluid from axially escaping from the guide device, and in particular enables targeted guidance of the cooling fluid toward the outlet opening.

[0015] The first guide element preferably extends over at least 170 degrees, preferably at least 175 degrees and / or at most 200 degrees, preferably at most 185 degrees, particularly preferably at most 180 degrees, in the circumferential direction. Likewise, the second guide element can extend over at least 150 degrees, preferably at least 170 degrees, particularly preferably at least 175 degrees and / or at most 210 degrees, preferably at most 200 degrees, particularly preferably at most 185 degrees, in the circumferential direction.

[0016] Particularly preferably, the guide device is formed from a plastic.

[0017] Advantageously, a further guide device is arranged on the other end face.

[0018] In order to effectively inhibit or prevent penetration of the cooling fluid into the air gap, it is expedient if the electrical machine according to the invention further comprises a rotor arranged within the stator to form an air gap, wherein a radially outermost section at the free end of the first guide element is positioned radially further outward than the air gap.

[0019] Preferably, the electric machine according to the invention further includes a coolant supply arranged such that the cooling fluid is directed onto the first guide element in order to flow around it in the circumferential direction. It is particularly preferred if the coolant supply is arranged such that the cooling fluid is directed onto the first guide element in the radial direction. The coolant supply may have a plurality of supply openings, in particular arranged distributed in the circumferential direction.

[0020] According to the invention, the guide device is attached to a bearing plate of the electric machine. This allows the guide device to be easily retrofitted to existing machine architectures.

[0021] Particularly preferably, the stator windings are designed as hairpin windings.

[0022] Further advantages and details of the present invention will become apparent from the exemplary embodiments described below and from the drawings. These are schematic representations and show: Fig. 1 is a perspective view of a guide device; Fig. 2 is an axial plan view of the Fig. 1 shown guide device; Fig. 3 is a perspective sectional view of an embodiment of the electrical machine according to the invention; Fig. 4 is a perspective detailed view of the electrical machine in the region of a first guide element of the guide device; and Fig. 5 is a perspective detailed view of the electrical machine in the region of a second guide element of the guide device.

[0023] Fig. 1 is a perspective view of a guide device 1.

[0024] The guide device 1 comprises a body 2 with a recess 4 delimited by an inner edge 3, as well as a first guide element 5, which protrudes axially from the body and extends circumferentially at a first radial position located between the inner edge 3 and an outer edge 6 of the body 2. In addition, the guide device 1 additionally comprises a second guide element 7, which protrudes axially from the body 2 and extends circumferentially at a second radial position located between the first radial position and the outer edge 6. The entire body 2 is made of an electrically insulating material, in this case a plastic.

[0025] For this purpose, the body 2 has an inner section 8a which is delimited by the edge 3 and extends along a radial plane, and a second section 8b which is delimited by the outer edge 6 and is axially angled relative to the first section 8a. In a transition region between the first section 8a and the second section 8b, Fig. 1 The first guide element 5 is arranged on the first side of the body 2, which can be seen, and is fastened to the first section 8a by means of additional radially inwardly facing reinforcing elements 9. The second guide element 7 projects axially from the second section 8b of the body and is reinforced by additional radially outwardly facing reinforcing elements 10.

[0026] In the center region of the second guide element, an outlet opening 11 is formed in the body 2. The outlet opening 11 extends through the second section 8b of the body 2. In addition, a radially outward-facing recess 12 is formed in the second guide element 7, which opens into the outlet opening 11.

[0027] At a free end of the first guide element 5, a radially outwardly directed elevation 13 is formed, which will be described later with reference to Fig. 4 At a free end of the second guide element 7, a radially inwardly directed elevation 14 is formed, which will be explained later with reference to Fig. 5 is explained in more detail.

[0028] Furthermore, the body 2 has, in its second section 8b, a plurality of through-openings 15 formed in the circumferential direction, which can be used for fastening the guide device 1 or for introducing a cooling fluid onto the first guide element.

[0029] Fig. 2 is an axial plan view of the Fig. 1 shown side of the guide device 1.

[0030] The first guide element 5 extends circumferentially over an angular range of 180°. In contrast, the second guide element 7 extends over an angular range of approximately 195°, so that the guide elements 5, 7 form two overlapping areas 16a, 16b. The respective centers 17, 18 of the guide elements 5, 7 are arranged such that a straight line 19 connecting them intersects the center point 20 of the recess 4.

[0031] Fig. 3 is a perspective sectional view of an embodiment of an electrical machine 21 in the region of a first end face.

[0032] The electrical machine 21 comprises a stator 22 and a rotor 23, between which an air gap 24 is formed, a machine housing 25 and a bearing plate 26. In Fig. 3 An A-end shield is shown. The electric machine 21 has another end shield (B-end shield) on its second end face. A previously described guide device 1 is arranged on each of these end shields 26. The electric machine 21 is a drive machine for an electrically driven vehicle.

[0033] The stator 22 has stator windings 27 configured as hairpin windings. Winding heads 28 of the stator windings 27 protrude from the stator 22 toward the bearing plate 26. The first guide element 5 is arranged radially inside the winding heads 28, and the second guide element 7 is arranged radially outside the winding heads 28.

[0034] The electric machine 21 further comprises a coolant supply 29, which is arranged such that a cooling fluid is directed onto the first guide element 5 in order to flow around it in the circumferential direction. In the overlapping regions 16a, 16b (see Fig. 2 ), the cooling fluid flows from the first guide element 5 down to the second guide element 7 due to the force of gravity acting in the direction of a machine base 30. There it flows around the remaining winding heads 28 and reaches the outlet opening 11 at the lowest point of the second guide element 7 (see Fig. 1 ).

[0035] Fig. 4 is a perspective detailed view of the electric machine 21 in the region of the first guide element 5. It can be seen that a radially outermost section of the first guide element 5 is located radially further out than the air gap 24. The elevation 13 prevents the cooling fluid from escaping axially from the guide device 1 and entering the air gap 24.

[0036] Fig. 5 is a perspective detailed view of the electric machine 21 in the area of ​​the second guide element 7. Here, the elevation 14 prevents the cooling fluid from escaping axially from the guide device 1 and the guide device 1 from passing through the outlet opening 11 (see Fig. 1 ) leaves.

Claims

1. Electrical machine (21), comprising a stator (22) with stator windings (27) and a guide device (1) arranged on a front side for a cooling fluid flowing around winding heads (28) of the electrical machine (21), wherein the guide device (1) comprises - a body (2), with a recess (4) delimited by an inner edge (3), for guiding through a shaft of the electrical machine (21), and - a first guide element (5), which protrudes from the body (2) in the axial direction, extends in the peripheral direction at a first radial position lying between the inner edge (3) and an outer edge (6) of the body (2), and is arranged in the radial direction inside the winding heads (28) of the stator windings (27), characterized in that the guide device (1) is fixed to a bearing shield (26) of the electrical machine (21) and comprises a second guide element (7) which protrudes from the body (2) in the axial direction, extends in the peripheral direction at a second radial position lying between the first radial position and the outer edge (6) of the body (2), and is arranged in the radial direction outside the winding heads (28), wherein the first guide element (5) extends over at least 150 degrees in the peripheral direction, wherein the first guide element (5) and the second guide element (7) form two overlap regions (16a, 16b) extending in the peripheral direction, wherein an outlet opening (11) for the cooling fluid is formed in the region of the center (18) in the peripheral direction of the second guide element (7).

2. Electrical machine (21) according to claim 1, wherein the first guide element (5) extends over a maximum of 200 degrees in the peripheral direction.

3. Electrical machine (21) according to claim 1 or 2, wherein the respective centers (17, 18) in the peripheral direction of the guide elements (5, 7) are arranged so as to be connectable by a line (19) traversing the center point (20) of the recess (4).

4. Electrical machine (21) according to any one of the preceding claims, wherein the second guide element (7) has a radial indentation (12), which opens into the outlet opening (11) formed in the body (2).

5. Electrical machine (21) according to any one of the preceding claims, wherein a radially outwardly pointing elevation (13) is formed at the free end of the first guide element (5) and / or a radially inwardly pointing elevation (14) is formed at the free end of the second guide element (7).

6. Electrical machine (21) according to any one of the preceding claims, wherein the guide device (1) is formed from a plastic material.

7. Electrical machine (21) according to any one of the preceding claims, further comprising a rotor (23) which is arranged inside the stator (22) forming an air gap (24), wherein an radial outermost section on the free end of the first guide element (5) is positioned radially outside the air gap (24).

8. Electrical machine (21) according to any one of the preceding claims, further comprising a coolant feed (29) which is arranged in such a way that the cooling fluid is conducted to the first guide element (5), in order to flow around the first guide element (5) in the peripheral direction.

9. Electrical machine (21) according to any one of the preceding claims, wherein the stator windings (27) are formed as hairpin windings.

10. Electrical machine (21) according to any one of the preceding claims, further comprising an additional guide device, which is arranged at the other front side.