Magnetic field generating part of an electric machine such as a stator and / or a rotor with improved winding head front plate and electric machine and vehicle thereto

Abstract

A magnetic field generating part (6, 10) of an electric machine (1) such as a stator (6) or a rotor (10) is disclosed. It comprises a lamination stack (7, 12), a winding head front plate (16, 16a, 16b) and wire windings (9, 14). The winding head front plate (16, 16a, 16b) has a star shape with a central opening (E) and radially extending arms (17) each having lateral boundary surfaces (G1, G2). On the arms (17), there are outer circumferential side walls (18) projecting away from a front face (C1, C2) of the lamination stack (7, 12). Axially beneath the wire windings (9, 14), the winding head front plate (16, 16a, 16b) has clearance areas (J) adjacent to the lamination stack (7, 12), which each are spaced from an outer circumference of the winding head front plate (16, 16a, 16b) and continuously lead from a first lateral boundary surface (G1) to a second lateral boundary surface (G2) of a corresponding one of the arms (17). Moreover, an electric machine (1) with such a stator (6) and / or rotor (10) and a vehicle (20) with such an electric machine (1) are presented.

Description

[0001] Magnetic field generating part of an electric machine such as a stator and / or a rotor with improved winding head front plate and electric machine and vehicle thereto

[0002] TECHNICAL FIELD

[0003] The invention relates to a magnetic field generating part of an electric machine such as a stator and / or a rotor. It comprises a lamination stack, a winding head front plate and wire windings. The lamination stack comprises a plurality of laminations axially stacked over another with winding slots arranged therein, wherein the lamination stack has a first front face and a second front face axially vis-a-vis of the first front face. The winding head front plate is arranged on the lamination stack at the first front face. Seen in a front viewing direction perpendicular to the first front face, it has a star shape with a central opening and radially extending arms each having a first and a distant second lateral boundary surface. Further on, on the arms the winding head front has outer circumferential side walls projecting away from the first front face. The wire windings are arranged in the winding slots of the lamination stack and are wound around the arms of the winding head front plate radially within the outer circumferential side walls, Moreover, the invention relates to an electric machine with such a stator and / or rotor and to a vehicle with such an electric machine, wherein the electric machine is provided to propel the vehicle. Finally, the invention relates to a method of manufacturing a magnetic field generating part of an electric machine as defined hereinbefore.

[0004] BACKGROUND ART

[0005] A magnetic field generating part, an electric machine, a vehicle and a method of the above kinds are each generally known. Winding head front plates are generally used for guiding the wire winding during production of the electric machine. Further on, they can be used for axial fixation of the lamination stack and to avoid axial diverging of the rotor laminations during production and operation of the electric machine. During the winding process, a tension force is applied to the wire windings, which naturally causes an elastic deformation of the wire windings and in turn a force acting inwards in relation to windings. Because usually the winding wire has a circular cross section and because the wire windings have a number of layers, also lateral force components between the winding wires of the different layers are caused. These lateral forces act in circumferential direction in the winding slots and in radial direction at the winding heads. The lamination stack by nature is comparably rigid so that these lateral, circumferential forces do not play an essential role during manufacturing an electric machine. However, the situation is different at the winding head front plates. Because the wire windings reach out far in radial direction, outer circumferential side walls holding back the wire windings naturally are comparably thin. That is why these lateral, radial forces can bend the circumferential side walls outwards and widen the outer diameter of the winding head front plates what can lead to problems during production and operation of the electric machine. To avoid this phenomenon, comparably strong materials can be used for the winding head front plates which unfortunately is relatively expensive and increases the total costs for the electric machine.

[0006] DISCLOSURE OF INVENTION

[0007] Accordingly, an object of the invention is to provide an improved magnetic field generating part of an electric machine such as a stator and / or a rotor, an improved electric machine, an improved vehicle and an improved method for manufacturing a magnetic field generating part. In particular, a cost-effective solution for winding head front plates shall be proposed, which avoids widening of the outer diameter of the winding head front plates during the winding process.

[0008] The object of the invention is solved by a magnetic field generating part as disclosed in the opening paragraph, wherein the winding head front plate, axially beneath the wire windings, has clearance areas adjacent to the lamination stack. Seen in the front viewing direction, the clearance areas each are spaced from an outer circumference of the winding head front plate and continuously lead from the first lateral boundary surface to the second lateral boundary surface of a corresponding one of the arms.

[0009] Generally, the aforementioned magnetic field generating part can be a) a stator for the electric machine, wherein the lamination stack is a stator lamination stack, the winding slots are stator slots and the wire windings are stator wire windings, or b) a rotor for the electric machine, wherein the lamination stack is a rotor lamination stack, the winding slots are rotor slots and the wire windings are rotor wire windings.

[0010] Further on, the object of the invention is solved by an electric machine, which comprises a stator and a rotor rotatably arranged relative to the stator, wherein the stator is embodied according to case a) and / or wherein the rotor is embodied according to case b).

[0011] Moreover, the object of the invention is solved by a vehicle, wherein the vehicle comprises an electric machine of the above kind and wherein the electric machine is provided to propel the vehicle.

[0012] In addition, the object of the invention is solved by a method of manufacturing a magnetic field generating part of an electric machine as defined hereinbefore, wherein the method comprises the following steps: providing the lamination stack, arranging the winding head front plate on the first front face and arranging the wire windings in the winding slots of the lamination stack and winding them around the arms of the winding head front plate radially within the outer circumferential side walls, wherein a tension force in the wire windings leads to a partial decrease of the height of the clearance areas and to an inward tilt of the outer circumferential side walls and / or to a bending tension within the winding head front plate causing an inward force acting on the outer circumferential side walls.

[0013] By use of the clearance areas and the tension force in the wire windings, which naturally occurs during the winding process, said inward tilt of the outer circumferential side walls and / or said inward force acting on the outer circumferential side walls are caused which in turn also causes a radial inward compression of the wire windings. In this way, widening of the outer diameter of the winding head front plates during the winding process is avoided at low costs, and in particular, the winding head front plate can be made of comparably cheap plastic.

[0014] Generally, because the clearance areas are spaced from the outer circumference of the winding head front plate, outer supporting surfaces are provided. Moreover, if the clearance areas are spaced from the central opening in an optional embodiment, additional inner supporting surfaces are provided. In both cases, said inward tilt of the outer circumferential side walls and / or said inward force acting on the outer circumferential side walls are caused by the tension force in the wire windings. However, it should be noted at this point that the inner supporting surfaces are not mandatory, and the outer circumferential side walls tilt also inwards without an inner supporting surface.

[0015] The arms, each seen in a tangential viewing direction perpendicular to the first lateral boundary surface of a corresponding one of the arms, can have a substantially h-shaped profile. This h-shaped profile is a product of the outer circumferential side wall and the outer supporting surface (which together form the left long leg of the “h”), the inner supporting surface (which forms the right short leg of the “h”) and the clearance area (which forms the gap in the “h”).

[0016] In yet another beneficial embodiment, the arms each can have inner circumferential side walls projecting away from the first front face, wherein the wire windings are wound around the arms of the winding head front plate radially in-between the inner circumferential side walls and the outer circumferential side walls. In this way, the winding wire is reliably guided also on the radially inner side.

[0017] The arms, each seen in a tangential viewing direction perpendicular to the first lateral boundary surface of a corresponding one of the arms, can have a substantially H-shaped profile. This H-shaped profile is a product of the outer circumferential side wall and the outer supporting surface (which together form the left long leg of the “h”), the inner circumferential side wall and the inner supporting surface (which together form the right long leg of the “H”) and the clearance area (which forms the lower gap in the “H”).

[0018] It should be noted that that the proposed technical features generally relate to a magnetic field generating part with a lamination stack, laminations, winding slots and wire windings. As already mentioned, the magnetic field generating part can be embodied as a stator or a rotor. Accordingly, if the magnetic field generating part is embodied as a stator, the aforementioned disclosure relates to a stator lamination stack, stator laminations, stator winding slots and stator wire windings. Likewise, if the magnetic field generating part is embodied as a rotor, the aforementioned disclosure relates to a rotor lamination stack, rotor laminations, rotor winding slots and rotor wire windings.

[0019] BRIEF DESCRIPTION OF DRAWINGS

[0020] The invention now is described in more detail hereinafter with reference to particular embodiments, which the invention however is not limited to.

[0021] Fig. 1 shows a half sectional view of an exemplary electric machine;

[0022] Fig. 2 shows a cross sectional view of an exemplary winding head front plate;

[0023] Fig. 3 shows a front view of the winding head front plate of Fig. 2, Fig. 4 shows a detailed view of the winding head front plate of Fig. 2 in the radially outer region and

[0024] Fig. 5 shows a schematic view of an electric vehicle.

[0025] DETAILED DESCRIPTION

[0026] Generally, same parts or similar parts are denoted with the same / similar names and reference signs. The features disclosed in the description apply to parts with the same / similar names respectively reference signs. Indicating the orientation and relative position is related to the associated figure.

[0027] Fig. 1 shows a half sectional view of an exemplary electric machine 1 . The electric machine 1 comprises a stator housing 2, a first bearing shield 3 and a second bearing shield 4. The stator housing 2, the first bearing shield 3 and the second bearing shield 4 together form a machine housing 5. The design of the machine housing 5 is just exemplary and other designs are possible as well. For example, the stator housing 2 with one of the bearing shields 3, 4 may form a pot-shaped housing part.

[0028] Moreover, the electric machine 1 comprises a stator 6 arranged in the stator housing 2, which comprises a stator lamination stack 7 with a plurality of stator laminations 8 axially stacked over another with winding slots (not visible in Fig. 1 ) arranged therein. Additionally, the stator 6 comprises stator wire windings 9, which are arranged in the winding slots of the stator lamination stack 7, from which only the stator winding heads are visible in Fig. 1 .

[0029] Further on, the electric machine 1 comprises a rotor 10 with a rotor shaft 1 1 and a rotor lamination stack 12 mounted on the rotor shaft 1 1 . The rotor lamination stack 12 comprises a plurality of rotor laminations 13 axially stacked over another with winding slots B arranged therein. Additionally, the rotor 10 comprises rotor wire windings 14, which are arranged in the rotor winding slots B of the rotor lamination stack 12.

[0030] Moreover, the electric machine 1 comprises a first (roller) bearing 15a in the first bearing shield 3 and a second (roller) bearing 15b in the second bearing shield 4 for rotatably supporting the rotor 10 around a rotor axis or stator axis RA.

[0031] The rotor 10 comprises a first winding head front plate 16a at a first front face C1 of the rotor lamination stack 12 and a second winding head front plate 16b at a second front face C2 axially vis-a-vis of the first front face C1 . Finally, Fig. 1 shows a front viewing direction D, which is oriented perpendicular to the first front face C1 .

[0032] Figs. 2 to 4 now show a winding head front plate 16, which may be an example for one of the or both winding head front plates 16a, 16b of Fig. 1 , in detail. Concretely, Fig. 2 shows a cross sectional view of the winding head front plate 16, Fig. 3 shows a front view of the winding head front plate 16 and Fig .4 shows a detail of the winding head front plate 16 in the radially outer region. For example, the winding head front plate 16 can be made of plastic.

[0033] The winding head front plate 16, seen in the front viewing direction D, has a star shape with a central opening E and radially extending arms 17 each having a first and a distant second lateral boundary surface G1 , G2. On the arms 17, the winding head front plate 16 has outer circumferential side walls 18 projecting away from the first front face C1 , wherein the rotor wire windings 14 are wound around the arms 17 of the winding head front plate 16 radially within the outer circumferential side walls 18.

[0034] Axially beneath the rotor wire windings 14, the winding head front plate 16 has clearance areas J adjacent to the rotor lamination stack 7, which, seen in the front viewing direction D, each are spaced from an outer circumference of the winding head front plate 16 and continuously lead from the first lateral boundary surface G1 to the second lateral boundary surface G2 of a corresponding one of the arms 17. The clearance areas J can be spaced from the central opening E what is the case in the example of Figs. 2 to 4. Moreover, the arms 17, each seen in a tangential viewing direction H perpendicular to the first lateral boundary surface G1 of a corresponding one of the arms 17, can have a substantially h-shaped profile I what is the case in the example of Figs. 2 to 4, too.

[0035] The winding head front plate 16 may comprise optional inner circumferential side walls 19 projecting away from the first front face C1 like this is depicted in Figs. 2 and 4 with dashed lines. The rotor wire windings 14 are wound around the arms 17 of the winding head front plate 17 radially in-between the inner circumferential side walls 19 and the outer circumferential side walls 18 then. In this case, the arms 17, each seen in a tangential viewing direction H perpendicular to the first lateral boundary surface G1 of a corresponding one of the arms 17, can have a substantially H-shaped profile I’ which is indicated with dashed lines in Fig. 2.

[0036] A method of manufacturing a rotor 10 of an electric machine 1 can comprise the following steps, where reference is particularly made to Fig. 4: providing the rotor lamination stack 12, arranging the winding head front plate 16, 16a, 16b on the first front face C1 and arranging the rotor wire windings 14 in the winding slots B of the rotor lamination stack 12 and winding them around the arms 17 of the winding head front plate 16, 16a, 16b radially within the outer circumferential side walls 18.

[0037] Generally, because the clearance areas J are spaced from the outer circumference of the winding head front plate 16, outer supporting surfaces K are provided. In addition, if the clearance areas J are spaced from the central opening E, optional inner supporting surfaces L are provided which is true for Figs. 2 to 4. In both cases, the tension force FT in the rotor wire windings 14 leads to a partial decrease of the height d of the clearance areas J and to an inward tilt M of the outer circumferential side walls 18 and / or to a bending tension within the winding head front plate 16, 16a, 16b causing an inward force FIN acting on the outer circumferential side walls 18. It should be noted at this point that the inner supporting surfaces L are not mandatory, and the outer circumferential side walls 18 tilt also inwards without an inner supporting surface L.

[0038] It should be noted that the square profile of the clearance areas J shown in the cross section of Fig. 4 is not mandatory, and other shapes are possible as well. For example, Fig. 4 in this context schematically depicts an alternative chamfered or angled clearance profile N and a rounded clearance profile N’.

[0039] It should also be noted that although the proposed technical features have been presented by reference to the rotor 10, the very same technical teaching is true for the stator 6. So, in the above disclosure, the rotor 10 can be replaced by the stator 6, the rotor lamination stack 12 can be replaced by the stator lamination stack 7, the rotor lamination 13 can be replaced by the stator lamination 8, the rotor winding slots B can be replaced by stator winding slots and the rotor wire winding 14 can be replaced by the stator wire winding 9. In more general terms, the stator 6 and the rotor 10 are magnetic field generating parts and can be denoted the same. In this context, reference can also be made simply to a lamination stack 7, 12, a lamination 8, 13, a winding slot B and a wire winding 9, 14.

[0040] Generally, by use of the clearance areas J, a radial inward compression of the wire windings 9, 14 is provided and in turn, widening of the outer diameter of the winding head front plates 16, 16a, 16b during the winding process can be avoided.

[0041] Fig. 5 finally shows an electric vehicle 20 with an electric machine 1 as defined hereinbefore, which is provided to propel the electric vehicle 20. In detail, the electric machine 1 is coupled to an optional gearbox 21 , side shafts 22 and finally to the wheels 23. The electric machine 1 may be provided for powering the electric vehicle 20 permanently in a pure electric car or intermittently, e.g. in combination with a combustion engine in a hybrid car. It is noted that the invention is not limited to the embodiments disclosed hereinbefore, but combinations of the different variants are possible. In reality, the electric machine 1 and the electric vehicle 20 may have more or less parts than shown in the figures. It is also noted that the electric machine 1 and the electric vehicle 20 or parts thereof are not necessarily drawn to scale in the Figs. Moreover, the description may comprise subject matter of further independent inventions.

[0042] It should also be noted that the term "comprising" does not exclude other elements and the use of articles "a" or "an" does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

[0043] List of References

[0044] 1 electric machine

[0045] 2 stator housing

[0046] 3 first bearing shield

[0047] 4 second bearing shield

[0048] 5 machine housing

[0049] 6 magnetic field generating part (stator)

[0050] 7 (stator) lamination stack

[0051] 8 (stator) lamination

[0052] 9 (stator) wire winding

[0053] 10 magnetic field generating part (rotor)

[0054] 11 rotor shaft

[0055] 12 (rotor) lamination stack

[0056] 13 (rotor) lamination

[0057] 14 (rotor) wire winding

[0058] 15a, 15b (roller) bearing

[0059] 16, 16a, 16b winding head front plate

[0060] 17 arm of winding head front plate

[0061] 18 outer circumferential side wall

[0062] 19 inner circumferential side wall

[0063] 20 vehicle

[0064] 21 gear

[0065] 22 side shaft

[0066] 23 wheel RA rotor axis / stator axis

[0067] B winding slot

[0068] C1 , C2 front face rotor lamination stack

[0069] D front viewing direction E central opening of winding head front plate

[0070] FIN inward force

[0071] FT tension force

[0072] G1 , G2 lateral boundary surface of winding head front plate arm

[0073] H tangential viewing direction I h-shaped profile

[0074] I’ H-shaped profile

[0075] J clearance area

[0076] K outer supporting surface

[0077] L inner supporting surface M inward tilt I inward tilting movement

[0078] N chamfered clearance profile

[0079] N’ rounded clearance profile d height of the clearance area

Claims

Claims1 . Magnetic field generating part (6, 10) of an electric machine (1 ), comprising a lamination stack (7, 12), a winding head front plate (16, 16a, 16b) and wire windings (9, 14), wherein the lamination stack (7, 12) comprises a plurality of laminations (8, 13) axially stacked over another with winding slots (B) arranged therein and wherein the lamination stack (7, 12) has a first front face (C1 ) and a second front face (C2) axially vis-a-vis of the first front face (C1 ), wherein the winding head front plate (16, 16a, 16b)-) is arranged on the lamination stack (7, 12) at the first front face (C1 ),-) seen in a front viewing direction (D) perpendicular to the first front face (C1 ), has a star shape with a central opening (E) and radially extending arms (17) each having a first and a distant second lateral boundary surface (G1 , G2), and -) on the arms (17) has outer circumferential side walls (18) projecting away from the first front face (C1 ), and wherein the wire windings (9, 14) are arranged in the winding slots (B) of the lamination stack (7, 12) and are wound around the arms (17) of the winding head front plate (16, 16a, 16b) radially within the outer circumferential side walls (18), characterized in that the winding head front plate (16, 16a, 16b), axially beneath the wire windings (9, 14), has clearance areas (J) adjacent to the lamination stack (7, 12), which, seen in the front viewing direction (D), each are spaced from an outer circumference of the winding head front plate (16, 16a, 16b) and continuously lead from the first lateral boundary surface (G1 ) to the second lateral boundary surface (G2) of a corresponding one of the arms (17).

2. Magnetic field generating part (6, 10) as claimed in claim 1 , characterized in that the clearance areas (J) are spaced from the central opening (E).

3. Magnetic field generating part (6, 10) as claimed in claim 2, characterized in that the arms (17), each seen in a tangential viewing direction (H) perpendicular to the first lateral boundary surface (G1 ) of a corresponding one of the arms (17), have a substantially h-shaped profile (I).

4. Magnetic field generating part (6, 10) as claimed in claim 1 or 2, characterized in the arms (17) each have inner circumferential side walls (19) projecting away from the first front face (C1 ), wherein the wire windings (9, 14) are wound around the arms (17) of the winding head front plate (17) radially in-between the inner circumferential side walls (19) and the outer circumferential side walls (18).

5. Magnetic field generating part (6, 10) as claimed in claim 4, characterized in that the arms (17), each seen in a tangential viewing direction (H) perpendicular to the first lateral boundary surface (G1 ) of a corresponding one of the arms (17), have a substantially H-shaped profile (I’).

6. Magnetic field generating part (6, 10) as claimed in any one of claims 1 to 5, characterized in that the winding head front plate (16, 16a, 16b) is made of plastic.

7. Magnetic field generating part (6, 10) as claimed in any one of claims 1 to 6, characterized in that the magnetic field generating part (6, 10) is a) a stator (6) for the electric machine (1 ), wherein the lamination stack (7, 12) is a stator lamination stack (7), the winding slots (B) are stator slots and the wire windings (9, 14) are stator wire windings (9), or b) a rotor (10) for the electric machine (1 ), wherein the lamination stack (7, 12) is a rotor lamination stack (12), the winding slots (B) are rotor slots and the wire windings (9, 14) are rotor wire windings (14).

8. Electric machine (1 ), comprising a stator (6) and a rotor (10) rotatably arranged relative to the stator (6), wherein the stator (6) is embodied as claimed in case a) of claim 7 and / or wherein the rotor (10) is embodied as claimed in case b) of claim 7.

9. Vehicle (20) with an electric machine (1 ) according to claim 8 provided to propel the vehicle (20).

10. Method of manufacturing a magnetic field generating part (6, 10) of an electric machine (1 ) as claimed in any one of the claims 1 to 7, comprising the steps providing the lamination stack (7, 12), arranging the winding head front plate (16, 16a, 16b) on the first front face (C1 ) and - arranging the wire windings (9, 14) in the winding slots (B) of the lamination stack (7, 12) and winding them around the arms (17) of the winding head front plate (16, 16a, 16b) radially within the outer circumferential side walls (18), wherein a tension force (FT) in the wire windings (9, 14) leads to a partial decrease of the height (d) of the clearance areas (J) and to an inward tilt (M) of the outer cir- cumferential side walls (18) and / or to a bending tension within the winding head front plate (16, 16a, 16b) causing an inward force (FIN) acting on the outer circumferential side walls (18).

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