Method for winding an electrical machine rotor

Abstract

The present invention relates to a wound rotor (20), in particular a wound rotor (20) for an electric machine (30), comprising a shaft (21) with a main axis (A) and with current collecting rings (22), windings (25), and n magnetic poles (1, 2, 3, ..., n-2, n-1, n) wound in increasing orders obtained by rotation around the main axis (A), in particular n wound magnetic poles (1, 2, 3, ..., n-2, n-1, n) distributed radially around the main axis (A), in which the n magnetic poles are wound successively with wire (25) in order according to the increasing orders of the magnetic poles, but the last magnetic pole (n) is not the pole wound last with wire.

Description

[Technical field]

[0001] The invention relates to a wound rotor for an electric machine. The invention also relates to an electric machine equipped with such a wound rotor. The invention also relates to a vehicle equipped with such a wound rotor and / or such an electric machine. The invention finally relates to a method for obtaining such a wound rotor. [Background technology]

[0002] Electric machines, in particular electric traction machines for motor vehicles, may comprise a wound rotor. Such a wound rotor generally comprises a shaft and slip rings and a number of magnetic poles wound with wire. The windings of the wire, generally of the enamelled copper type, are placed on a bundle or lamination of armature soft iron sheets. To allow the passage of current through the coils, both ends of the copper wire are connected by hooks to slip rings. Such slip rings make it possible to transmit electrical energy between the fixed part and the wound rotor (rotating part).

[0003] The routing or path of the windings in the slots and / or to the adjacent connections of the shaft and / or the slip ring is important.

[0004] In particular, poor routing of the windings to the connection can result in improper positioning of the wires on the connection hook. Residual stresses (tension in the wire and connection at the time of attaching the wire to the hook, typically by crimping) and / or mechanical rotational stresses (centrifugal forces) can then occur in the connection. Poor crimping of the wire can also cause the wire to slip out of the hook. Opening of the hook and / or breakage of the wire and / or breakage of the connection hook can also occur.

[0005] Moreover, this winding path must be compatible with the complex coil manufacturing method. It must allow both ends of the winding to be crimped reliably in the two hooks to make the connection. The winding path must give the winding a mechanical integrity that is compatible with the operating stresses, especially centrifugal forces and / or vibrations. Summary of the Invention

[0006] The object of the present invention is to provide a method for obtaining a wound rotor which overcomes the above-mentioned drawbacks, in particular the invention makes it possible to ensure the mechanical robustness of the connections of the windings to the shaft and / or to the slip rings of the wound rotor.

[0007] To this end, the invention relates to a wound rotor, in particular a wound rotor for an electric machine, comprising a shaft having a main axis, optionally equipped with slip rings, windings and n winding poles ordered in increasing orders obtained by rotation around the main axis, in particular n winding poles distributed radially around the main axis, in which the n poles are wound successively with windings in order according to their increasing orders, except that the last pole is not the pole to which a winding is wound last.

[0008] The penultimate pole may be wound after the ultimate pole.

[0009] The third to last pole is wound after the last pole.

[0010] Upstream of the first pole, the line may abut the shaft at a first non-zero angle about the major axis.

[0011] Downstream of the last wound pole, the wire abuts the shaft at a second non-zero angle about the major axis.

[0012] A wound rotor may comprise pins configured to facilitate winding of wire, in particular between two adjacent magnetic poles and / or between each magnetic pole and the shaft and / or slip rings, in particular the pins extending parallel or substantially parallel to the main axis.

[0013] The invention further relates to an electric machine, in particular for motor vehicles, in particular a vehicle traction electric machine, comprising a wound rotor as defined above.

[0014] The invention further relates to a vehicle, in particular a motor vehicle, comprising a wound rotor as defined above and / or an electric machine as defined above.

[0015] The invention further relates to a method for obtaining a wound rotor as defined above, comprising the steps of successively winding the n poles with windings in order of increasing orders of said poles, the last pole not being the pole to be wound last with a winding.

[0016] These objects, features and advantages of the present invention will be mentioned in detail in the following description of several embodiments thereof, illustrated non-limitingly with reference to the accompanying drawings. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic diagram of a vehicle having an electric machine with a four-pole wound rotor according to one embodiment. [Diagram 2] FIG. 13 is a schematic diagram of a six-pole wound rotor according to another embodiment. [Diagram 3] FIG. 13 is a schematic diagram of an eight-pole wound rotor according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 1 shows a schematic representation of a vehicle, e.g., a motor vehicle 40, according to an embodiment. The vehicle comprises an electric machine 30, e.g., an electric motor for traction and / or propulsion of the vehicle, according to an embodiment. The electric machine 30 comprises a wound rotor 20, according to an embodiment. The wound rotor 20 comprises a shaft 21, which defines a main axis A, and slip rings 22 (also known as sliding rings). The slip rings 22 and the shaft 21 are assembled coaxially or substantially coaxially along the main axis of rotation A about which the wound rotor 20 is adapted to rotate.

[0019] 1, 2 and 3, the wound rotor 20 includes windings 25. The windings 25 are made, for example, from copper, for example enameled copper.

[0020] More specifically, the wound rotor 20 comprises n winding poles, 1, 2, 3, ..., n-2, n-1, n. The n poles are preferably ordered in increasing degrees in the direction of rotation about the main axis A. Preferably, as shown in the figure, the n winding poles 1, 2, 3, ..., n-2, n-1, n are numbered, denoted or otherwise identified by assigning them numbers in a numerical sequence that increases clockwise about the axis A, with each pole being associated with a single number in the numerical sequence. Furthermore, the n poles are distributed radially or substantially radially about the main axis A. The n poles are wound successively by wires 25 in the order of their increasing degrees, although the last pole n is not the last pole to be wound, as will be explained below.

[0021] Thus the first pole is numerically associated with the number 1. The second pole is numerically associated with the number 2. The third-to-last pole is numerically associated with the number n-2. The second-to-last pole is numerically associated with the number n-1. The last pole is numerically associated with the number n.

[0022] Thus, the topological order of the poles defined above differs from the chronological order in which the poles are wound, as will be explained in more detail below.

[0023] It should be noted that prior to winding, the first end 28 of the wire 25 is first secured to the first connection means 26 arranged on the shaft 21 and / or the slip ring 22 .

[0024] Preferably, as shown in the figure, the first connection means 26 is arranged on the opposite side of the main axis A from the magnetic pole 1. In other words, the first connection means 26 is arranged near a magnetic pole that is arranged facing or substantially facing the magnetic pole 1 from the opposite side of the main axis A.

[0025] The first connection means 26 is, for example, a hook. Preferably, the fixing of the first end 28 of the wire 25 to or on the first connection means 26 is performed by hot or cold crimping.

[0026] For example, the penultimate pole, n-1, is wound after the last pole, n. Thus, for example, for a four-pole wound rotor having poles 1, 2, 3, 4 as shown in Figure 1, pole 1 is wound first, then pole 2, then pole 4, and finally pole 3 is wound last. Thus, for example, for a six-pole rotor having poles 1, 2, 3, 4, 5, 6 as shown in Figure 2, pole 1 is wound first, then pole 2, then pole 3, then pole 4, then pole 6, and finally pole 5 is wound last.

[0027] Or, for example, the third to the end pole, n-2, is wound after the end pole, n (this is not shown).

[0028] Alternatively or additionally, the third to last pole n-2 and the second to last pole n-1 are wound after the last pole n (not shown).

[0029] Preferably, as shown in detail in Figures 1 and 3, the wire 25 is pressed against the shaft 21 and / or the slip ring 22 before it reaches the first pole 1 and is wound around this pole, i.e. upstream of the first pole 1 according to the winding direction. In other words, before the first pole 1, the wire rests on a portion 10 (shown in dotted lines in Figure 3) of the circumference of the shaft 21 and / or the slip ring 22. This resting spans a first non-zero angle α about the main axis A, the size of which depends on the number of poles of the rotor. For example, as shown in Figure 3, the angle is greater than 45°. What is needed is to make contact and to maximize this contact.

[0030] It should be noted that after winding the n magnetic poles, a second end 29 of the wire 25 is attached to a second connection means 27 arranged on the shaft 21 and / or on the slip ring 22 .

[0031] Preferably, the second connection means 27 is arranged on an opposite side of the main axis A to the first connection means 26. In other words, the first connection means 26 and the second connection means 27 are arranged symmetrically or substantially symmetrically about the main axis A. Thus, preferably, the second connection means 27 is arranged close to the magnetic pole 1.

[0032] The second connection means 27 is for example a hook. Preferably, the second end 29 of the wire 25 is attached to or at the second connection means 27 by hot or cold crimping.

[0033] Preferably, after the last wound pole, before reaching the second connection means 27, i.e. downstream of the last wound pole in the winding direction, the wire 25 is pressed against the shaft 21 and / or the slip ring 22. In other words, after the last pole has been wound, the wire is mounted over a portion 11 (shown by a dotted line in FIG. 3 ) of the circumference of the shaft 21 and / or the slip ring 22. This mounting spans a second non-zero angle β about the main axis A, the magnitude of which depends on the number of poles the rotor has.

[0034] Advantageously, as shown in Fig. 3, the rotor 20 comprises pins 23 configured in particular to facilitate winding of the wires 25. For example, at least one pin 23 is arranged between two adjacent magnetic poles and / or at least one pin 23 is arranged between each magnetic pole and the shaft 21 and / or the slip rings 22. For example, as in the case of the embodiment shown in Fig. 3, two pins 23 are arranged near each magnetic pole and between each magnetic pole and the shaft 21 and / or the slip rings 22. Preferably, the pins 23 extend parallel or substantially parallel to the main axis A.

[0035] One embodiment of a method for obtaining the wound rotor 20 shown in FIG. 3 will now be described.

[0036] Firstly, an unwound rotor is obtained, which is provided with n magnetic poles and a winding 25 with a first end 28 and a second end 29. The unwound rotor is previously fitted with a shaft 21 having a main axis of rotation A and / or with slip rings 22. The unwound rotor is furthermore already provided with first and second connection means 26 and 27.

[0037] Firstly, the first end 28 of the wire 25 is attached to the first connection means 26, for example by crimping. The wire 25 is then brought close to the pole 1, thereby abutting against the shaft 21 and / or the slip ring 22 over the entire angular section 10, in other words, on the opposite side of the first connection means 27 with respect to the main axis A. Preferably, in the case of a rotor provided with pins 23, the wire 25 is passed along at least one pin, for example thereby orienting the wire in a direction suitable for winding the pole 1, which is thus wound with the wire 25.

[0038] Then, a step of winding pole 1 with wire 25 is performed. The next step is winding pole 2, possibly after passing wire 25 over one or more pins 23 to orient it towards the winding of pole 2 and / or away from the winding of pole 1. The next step is winding pole 3, possibly after passing wire 25 over one or more pins 23 to orient it towards the winding of pole 3 and / or away from the winding of pole 2. The next step is winding pole 4, possibly after passing wire 25 over one or more pins 23 to orient it towards the winding of pole 4 and / or away from the winding of pole 3. The next step is winding pole 5, possibly after threading wire 25 over one or more pins 23 to orient the wire towards the winding of pole 5 and / or away from the winding of pole 4. The next step is winding pole 6, possibly after threading wire 25 over one or more pins 23 to orient the wire towards the winding of pole 6 and / or away from the winding of pole 5. The next step is winding pole 8, possibly after threading wire 25 over one or more pins 23 to orient the wire towards the winding of pole 8 and / or away from the winding of pole 6. The next step is to wind the pole 7, which may be after threading the wire 25 over one or more pins 23 to orient the wire against the shaft 21 and / or slip rings 22 and / or to move the wire away from the winding of the pole 7.

[0039] Preferably, the "outgoing" line leaving the coil is offset, in a direction parallel or substantially parallel to the main axis A, from the "incoming" line starting the winding of the next coil. For example, a lower wall along the face of the coil is manufactured to ensure a distance between the "outgoing" and "incoming" lines. Thus, preferably, said parts of the line do not touch each other, since the positions where they leave and enter the coil are offset. For example, the line leading to a connection or hook passes over other parts of the line.

[0040] The wire 25 is then placed in abutment against the shaft 21 and / or the slip ring 22 over the entire angular section 11, thereby bringing the wire 25 closer to the pole 1, or in other words to the side of the second connection means 27. The next step is to attach the second end 29 of the wire 25 to the second connection means 27, for example by means of crimping.

[0041] Thus, the n poles are wound successively in order with their increasing orders, but the last pole n, pole 8 in the case of Figure 3, is not the last coil to be wound, but the penultimate. The last pole to be wound is the penultimate pole n-1.

[0042] For example, the windings of n poles are sequentially performed in increasing order of their poles, with pole n-2, the third from the end, being wound after the last pole n (not shown). For example, the windings of n poles are sequentially performed in increasing order of their poles, with pole n-3 being wound after the last pole n (not shown).

[0043] According to the invention it is possible to obtain a six-pole rotor whose six poles are wound in the following pole order: 1, 2, 3, 4, 6, 5 or 1, 2, 3, 5, 6, 4 or 1, 2, 3, 6, 5, 4.

[0044] According to the invention it is possible to obtain an 8-pole rotor whose poles are wound in the following pole order: 1, 2, 3, 4, 5, 6, 8, 7 or 1, 2, 3, 4, 5, 8, 6, 7 or 1, 2, 3, 4, 5, 8, 7, 6.

[0045] In general it is possible to obtain an n-pole rotor with the poles wound in the following sequence: 1, 2, ..., n-2, n, n-1 or 1, 2, ..., n-3, n, n-1, n-2 or 1, 2, ..., n-3, n-1, n, n-2.

[0046] In essence, the solution allows the winding scheme to be modified in order to increase the area of ​​contact with the shaft and / or slip rings, both when the wire 25 leaves the first connection 26 and when it reaches the second connection 27. For example, by changing the order of winding the poles, the wire 25 is angled back by around 45 degrees around the main axis A when it reaches the second connection 27 (i.e. counterclockwise, with the poles numbered clockwise). Preferably, as mentioned above, what is obtained is not just a point contact with the shaft and / or slip rings, but an angled contact portion 10 when the wire leaves the first connection 26 and an angled contact portion 11 when it reaches the second connection 27.

[0047] Preferably, the contact of the wire 25 over the entire angle portion 10, 11 is directly with the slip ring, in particular with an insulated portion of the slip ring, e.g. plastic coated and / or made from plastic. Alternatively or additionally, the wire may be provided with an insulating sheath, in particular over the entire relevant length of the wire, to achieve this insulation.

[0048] Furthermore, the above-described relative arrangement of the connection means 26, 27 opposite each other with respect to the axis A serves to provide a greater length of contact of the wire 25 against the shaft or slip ring before and after winding.

[0049] The present solution therefore significantly relieves the load on each angular bearing part 10, 11 and ensures the mechanical robustness of each connection of the lines to the slip rings and / or shafts.

[0050] This solution makes it possible to avoid having to resort to overmolding, a lengthy, costly and potentially dangerous process, especially if the overmolding material should tear during operation, which could result in the wires breaking.

[0051] The solution can be applied to electric machines with various polarities, for example with rotors with six magnetic poles or even with more than eight magnetic poles. As shown in Figure 1, the solution is also suitable for electric machines with a four-pole rotor, thereby increasing the area of ​​contact with the slip rings if necessary.

[0052] With this solution, the path of the windings for both the connections, i.e. the first connection and the second connection, prevents any misalignment of the wire. Residual stresses in the connections (e.g. tensions in the wire and the connection at the time of attaching the wire to the hook by crimping) and / or mechanical rotational stresses (centrifugal forces) are reduced, if not eliminated. The positioning of the wire in each hook is optimal for the crimping operation, so that the wire is completely prevented from slipping out of the hook during crimping, i.e. any opening of the hook and / or breakage of the wire and / or of the connecting hook is prevented. In particular, the angle of the wire reaching the second connection 27 ensures that the wire stays at the closed end of the hook throughout the crimping, which is crucial for the quality of the crimping.

[0053] The present winding method in combination with section 11 improves the repeatability of the position of the wire exiting the winding of the last pole wound, particularly due to the smaller exit angle θ (shown in FIG. 3) compared to the winding made on the last pole wound.

[0054] The present winding path solution gives the winding a mechanical integrity capable of withstanding the operating stresses, in particular the centrifugal forces and / or vibrations associated with the rotation of the rotor. In particular, the mechanical tension of the wire at the connection is reduced, in particular during the operation, i.e. rotation, of the rotor. This is achieved in particular as a result of the wire coming into contact with the slip ring before it reaches the connection means 27 for its second end 29. Furthermore, the bearing parts 10, 11 contribute to an improved vibration state of the wire between the connection 26, 27 and the pin 23 and / or the nearest winding. This results in a reduced propagation of vibrations of the wire 25 to the connection 26, 27, thereby eliminating the risk of the wire breaking at the connection.

[0055] It should therefore be noted that the solution according to the invention achieves the intended objective of ensuring the mechanical robustness of the connections of the windings to the shaft and / or to the slip rings of a wound rotor and offers the following advantages: - there is little or no modification to the wound rotor to implement the present winding method, so the cost is significantly lower; - Surrounding elements are not affected.

Claims

1. A wound rotor (20) comprising a shaft (21) having a main axis (A) with slip rings (22), windings (25) and n magnetic poles (1, ..., n-2, n-1, n) ordered in increasing degrees obtained by rotation around the main axis (A), the n magnetic poles (1, ..., n-2, n-1, n) being radially distributed around the main axis (A), for example a wound rotor (20) for an electric machine (30), characterized in that n is a natural number equal to or greater than 4, the n magnetic poles are wound successively with the windings (25) in order according to the increasing degrees of the magnetic poles, but the last magnetic pole (n) is not the last magnetic pole wound.

2. 2. The wound rotor (20) of claim 1, wherein the penultimate pole (n-1) is wound after the last pole (n).

3. 3. A wound rotor (20) according to claim 1 or 2, characterized in that the third to the last magnetic pole (n-2) is wound after the last magnetic pole (n).

4. A wound rotor (20) as described in any one of claims 1 to 3, characterized in that the winding (25) abuts the shaft (21) over a first non-zero angle (α) around the main axis (A) before being wound around the first magnetic pole (1).

5. A wound rotor (20) as described in any one of claims 1 to 4, characterized in that after being wound around the last to be wound magnetic pole (n-1; n-2), the winding (25) abuts against the shaft (21) over a second non-zero angle (β) around the main axis (A).

6. 6. A wound rotor (20) according to any one of claims 1 to 5, characterized in that it comprises pins (23) between two adjacent magnetic poles and / or between each magnetic pole and the shaft (21) and / or the slip rings (22) configured to wind the windings (25), the pins (23) extending parallel or substantially parallel to the main axis (A).

7. An electric machine (30), for example a vehicle traction electric machine, for a motor vehicle (40) characterized in that it comprises a wound rotor (20) according to any one of claims 1 to 6.

8. A vehicle, e.g. a motor vehicle (40), characterized in that it comprises a wound rotor (20) according to any one of claims 1 to 6 and / or an electric machine (30) according to claim 7.

9. A method for obtaining a wound rotor (20) according to any one of claims 1 to 6, characterized in that it includes the step of winding the n poles successively with the winding (25) in the order of increasing pole order, the last pole (n) being not the last pole wound.

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