Coil head guide, wound rotor of electric machine and electric machine comprising such a wound rotor

Abstract

Coil head guide (40) for winding electrical coil conductor wires (30) around a plurality of rotor teeth (16) of a wound rotor (10) comprising a cylindrical core (41) provided with a central orifice (42) intended to accommodate a rotor shaft, and radial branches or guide teeth (43) extending from the cylindrical core (41) and each intended to be positioned opposite a corresponding rotor tooth (16) of the rotor (10). The guide (40) comprises at least one radial rib (47) for holding the coil wires extending radially towards the central orifice (42) and each arranged circumferentially between two guide teeth (43). Figure for abstract: Fig. 3

Description

Title of the invention: Coil head guide, wound rotor of an electric machine and electric machine comprising such a wound rotor

[0001] The present invention relates to the field of rotating electrical machines and in particular rotors for rotating electrical machines, for example used in electric or hybrid type motor vehicles.

[0002] More particularly, the present invention relates to coil head guides for winding conductive electrical wires around poles of a wound rotor.

[0003] A wound rotor generally comprises a rotor shaft intended to be rotatably mounted around its axis, a metal core fixed on the rotor shaft and comprising a stack of thin sheets mounted coaxially on the rotor shaft.

[0004] The stack of laminations comprises a plurality of radially projecting rotor teeth and at least one axial opening, a winding of electrically conductive wires being intended to be wound around each rotor tooth. For this purpose, the rotor comprises heads for guiding the electrically conductive wires around each rotor tooth arranged axially on either side of the stack of laminations. Each guide head is provided with a central orifice for the passage of the rotor shaft.

[0005] Rotors with high rotational speeds are subject to difficult operating conditions and in particular to high stresses in the radial direction. In particular, the rotor windings are subjected to significant centrifugal forces during rotation of the rotor.

[0006] The guide heads of the winding wires are also highly stressed during rotation of the rotor by centrifugal force and must be adapted to operate under such conditions. For this purpose, each guide head is conventionally secured to a crown, independent of the body of the rotor, arranged at the outer periphery of a guide head, in order to form a means of radially holding the guide head.

[0007] Generally, the crown is annular in shape around the outer periphery of the guide head, with a profile comprising an L-shape comprising a wing oriented axially and resting on the outer periphery of the guide head and a wing oriented radially towards the rotor shaft and resting on a radial end face of each pole of the guide head.

[0008] Conventionally, the crown has holes made in its radial wing to allow the passage of tie rods and fix the crown to the guide head. The radial end faces of the poles of the guide head and the stack of sheets have holes coaxial with the holes in the crown to allow the tie rods to pass axially from the crown, through the guide head and the stack of sheets to the opposite side of the rotor.

[0009] Other solutions exist for securing the crown to the guide head.

[0010] In existing solutions, the wires of the coils, when passing from one pole to another pole adjacent, is subjected to the centrifugal force due to the rotation of the rotor. Thus, during accelerations and decelerations of the rotation of the rotor, the wire elongates and works in fatigue, which can cause it to break.

[0011] In order to limit damage to the coil wire, it is known to reduce the rotation speed of the rotor. However, such a solution is not satisfactory.

[0012] There is therefore a need to improve the life of the coil wire.

[0013] The object of the present invention is to limit damage to the coil wire, in particular between two adjacent poles, without increasing the size and manufacturing cost.

[0014] The subject of the invention is a coil head guide for winding electrical coil conductor wires around a plurality of rotor teeth of a wound rotor comprising a cylindrical core provided with a central orifice intended to accommodate a rotor shaft, and radial branches or guide teeth extending from the cylindrical core and each intended to be positioned opposite a corresponding rotor tooth of the rotor.

[0015] The coil head guide comprises at least one radial rib for holding the coil wires extending radially towards the central orifice and each arranged circumferentially between two guide teeth, in a notch.

[0016] Each radial rib makes it possible to hold the wires radially between the poles on the coil head guide, in particular in the event of centrifugal force linked to the rotation of the rotor.

[0017] The radial ribs make it possible to limit the elongation of the wire during rotation of the rotor and thus reduce the risk of fatigue failure.

[0018] As a result, such radial support thanks to the radial ribs makes it possible to increase the rotation speed of the rotor.

[0019] Advantageously, the coil head guide further comprises a plurality of guide pins or lugs each extending axially beyond the cylindrical core, a first guide pin of a guide tooth being connected to a second guide pin of an adjacent guide tooth by a connection portion extending circumferentially between two guide teeth, at least one radial rib for holding the coil wires extending radially from each connection portion, in particular from its lower surface.

[0020] For example, each connection portion extends axially beyond the cy- lindric.

[0021] For example, each guide pin extends axially beyond each connection portion.

[0022] Preferably, each radial rib has a parallelepiped shape whose contours allow easy demolding of the coil head guide.

[0023] Alternatively, any other shape could be provided projecting radially from the connection portion, the contours of which allow easy demolding of the coil head guide, such as, for example, a semi-circular shape.

[0024] Two radial ribs extending radially from a connection portion could also be provided.

[0025] The guide pins of one of the coil head guides make it possible to connect some of the coils together to form pairs of poles.

[0026] Advantageously, the guide teeth are regularly arranged on the periphery of the cylindrical core, the number of guide teeth being equal to the number of rotor teeth.

[0027] Advantageously, the coil head guide comprises guide grooves arranged on the lateral edges of each guide tooth so as to cooperate with the wires of the coils.

[0028] According to a second aspect, the invention relates to a wound rotor for a rotating electrical machine comprising a rotor shaft with an axis of rotation, two coil head guides as described previously, each arranged at an opposite end of the rotor shaft, and coils each wound around a rotor tooth and a guide tooth of the two coil head guides so as to form a rotor pole.

[0029] Advantageously, the cylindrical core of each coil head guide and the rotation shaft of the rotor are concentric with the rotation axis and each guide tooth of each coil head guide is axially located opposite a rotor tooth.

[0030] The coil head guides allow wires to be correctly positioned in the notch during a winding step to make the coils.

[0031] Advantageously, the rotor further comprises a core comprising a pack of laminations and mounted coaxially on the rotor shaft, the pack of laminations of the core comprising an alternation of rotor teeth and notches regularly distributed in a circumferential direction over a diameter of the core, at least each radial rib of the coil head guides being arranged circumferentially in a corresponding notch.

[0032] For example, the core comprises an axial stack of laminations which extend in a radial plane perpendicular to the axis of the rotor shaft.

[0033] In this radial plane, the sheets of the core sheet pack all have a identical outline.

[0034] For example, the rotor teeth extend radially outward from the rotation shaft toward the outer periphery of the rotor.

[0035] The core is advantageously fitted onto the cylindrical external surface of the rotation shaft, for example by shrink fitting.

[0036] Each rotor tooth may comprise an arm extending radially towards the outer periphery of the rotor.

[0037] The free end of each rotor tooth terminates, for example, in a circumferentially projecting return on either side of the arm. The function of the projecting return of each rotor tooth is to retain in the radial direction an electrically conductive excitation winding wound around the radial arm of each rotor tooth, against the centrifugal force experienced by said winding during rotation of the rotor.

[0038] Thus, each rotor tooth comprises such an excitation winding.

[0039] Advantageously, the wire of the coils connecting two adjacent rotor teeth is arranged radially between the corresponding radial rib and the central orifice of the cylindrical core of each coil head guide.

[0040] According to another aspect, the invention relates to a rotating electrical machine comprising a wound rotor as described above.

[0041] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

[0042] [Fig.l] schematically illustrates an example of a wound rotor according to the invention;

[0043] [Fig.l A] is a partial view of one end of the wound rotor of [Fig.l]; illustrates very schematically in section a wound rotor according to the invention, without the winding;

[0044] [Fig.2] represents a front view of the wound rotor of [Fig.l]; and

[0045] [Fig.3] is a detail view of [Fig.2].

[0046] As illustrated in [Fig.l], a rotor 10, for a winding electrical machine, of longitudinal axis X-X', comprises a rotation shaft 12 or rotor shaft extending axially through the body of the rotor. The rotor 10 further comprises a core 14 comprising a pack of laminations.

[0047] Said core 14 is mounted coaxially on the rotor shaft 12 or rotation shaft and comprises an axial stack of sheets which extend in a radial plane perpen- dicular to the axis of rotation X-X' of the rotation shaft 12.

[0048] In this radial plane, the sheets of the core sheet pack 14 all have an identical outline.

[0049] The core sheet pack 14 comprises an alternation of rotor teeth 16 and notches 18 regularly distributed in a circumferential direction over a diameter of the core 14.

[0050] The rotor teeth 16 extend radially projecting from the rotation shaft 12 towards the outer periphery of the rotor 10.

[0051] As illustrated and in a non-limiting manner, core 14 comprises eight rotor teeth 16.

[0052] However, the invention is not limited to this type of configuration and applies to a pack of sheets comprising a plurality of rotor teeth, and preferably at least three rotor teeth.

[0053] The core 14 is fitted onto the cylindrical external surface of the rotation shaft 12, for example by shrink fitting.

[0054] Each rotor tooth 16 comprises an arm 21 extending radially towards the outer periphery of the rotor 10.

[0055] The free end 22 of each rotor tooth 16 ends with a circumferentially projecting return on either side of the arm 21. The function of the projecting return 22 of each rotor tooth 16 is to retain in the radial direction an electrically conductive excitation winding 30 wound around the radial arm 21 of each rotor tooth 16, against the centrifugal force experienced by said winding 30 during rotation of the rotor 10.

[0056] Thus, each rotor tooth 16 comprises such an excitation winding 30.

[0057] The rotor 10 further comprises guide heads 40 mounted coaxially with the rotation shaft 12 and axially on either side of the core 14. The guide heads 40 make it possible to guide the conductive wires constituting the excitation winding 30 around a corresponding rotor tooth 16.

[0058] The rotor 10 here comprises two guide heads 40, only one of which is visible in the figures. The second guide head 40 is mounted axially on the side opposite the first guide head 40 visible in the figures.

[0059] Each guide head 40 has the shape of a disc extending in a radial plane perpendicular to the axis X-X' of the rotation shaft 12.

[0060] As illustrated, each guide head 40 comprises a cylindrical core 41 provided with a central orifice 42 coaxial with the rotation shaft 12 of the rotor 10.

[0061] Each guide head 40 comprises radial branches or guide teeth 43, here eight in number, extending from the cylindrical core 41 and each intended to be positioned opposite a corresponding rotor tooth 16 of the rotor 10, and in particular a radial arm 21.

[0062] The guide teeth 43 are regularly arranged on the periphery of the cylindrical core 41, the number of guide teeth 43 being equal to the number of rotor teeth 16.

[0063] Each coil 30 is wound around a rotor tooth 16 and a guide tooth 43 of the two coil head guides 40 so as to form, for example, a rotor pole.

[0064] The cylindrical core 41 and the rotation shaft 12 are concentric to the axis X-X'.

[0065] Each coil head guide 40 is immobilized on the rotation shaft 12 so that each guide tooth 43 is axially opposite a rotor tooth 16.

[0066] The coil head guides 40 make it possible to correctly position wires in the notch 18 during a winding step to produce the coils 30.

[0067] As visible in [Fig. 1A], in which the coils 30 have not been reproduced, each coil head guide 40 comprises guide grooves 44 arranged on the lateral edges of each guide tooth 43 so as to hold the wires of the coils 30.

[0068] The positioning of the coil head guides 40 on the rotation shaft 12 makes it possible to repeatably fix the start of each coil 30 in the guide grooves 44 of each guide tooth 43.

[0069] Each coil head guide 40 further comprises guide pins or lugs 45.

[0070] Each guide pin 45 here extends axially parallel to the axis X-X' of rotation and axially beyond the cylindrical core 41 of the coil head guide 40.

[0071] The guide pins 45 of one of the coil head guides 40 make it possible to connect a portion of the coils 30 together to form pairs of poles.

[0072] As illustrated, each coil head guide 40 comprises two guide pins 45a, 45b associated with each guide tooth 43.

[0073] The first guide pin 45a of a guide tooth 43 is connected to the second guide pin 45b of an adjacent guide tooth 43 by a connection portion 46.

[0074] The connection portion 46 extends circumferentially between two guide teeth 43.

[0075] Each connection portion 46 here extends axially beyond the cylindrical core 41 of the coil head guide 40.

[0076] Each guide pin 45 here extends axially beyond each connection portion 46 of the coil head guide 40.

[0077] As illustrated, each connecting portion 46 includes a radial rib 47 projecting radially from a lower surface of the connecting portion 46 toward the rotation shaft 12.

[0078] As illustrated in [Fig.2], the wire of the coils 30 connecting two adjacent poles is arranged radially below the corresponding connection portion 46, and in particular the radial rib 47. By “arranged radially below”, it is meant that the wire is arranged radially between the corresponding connection portion 46, and in particular the radial rib 47 and the central orifice 42 of the cylindrical core 41 of each coil head guide 40.

[0079] The radial rib 47 makes it possible to hold the wires radially between the poles on the coil head guide 40, in particular in the event of centrifugal force linked to the rotation of the rotor 10.

[0080] Generally, the coil head guide 40 comprises radial ribs 47 for holding the coil wires, each arranged circumferentially between two rotor teeth 16, in a notch 18.

[0081] The radial ribs 47 make it possible to limit the elongation of the wire during rotation of the rotor 10 and thus to reduce the risk of fatigue failure. As a result, such radial support thanks to the radial ribs makes it possible to increase the rotation speed of the rotor 10.

[0082] Each guide head 40 is a single piece and made of a plastic material with high mechanical strength, and generally obtained by plastic injection processes or by molding from, for example, a thermosetting material.

[0083] Each radial rib 47 here has a parallelepiped shape whose contours allow easy demolding of the coil head guide 40.

[0084] Alternatively, any other shape could be provided projecting radially from the connection portion 46, the contours of which allow easy demolding of the coil head guide 40, such as, for example, a semi-circular shape.

[0085] Two radial ribs extending radially from a connection portion 46 could also be provided.

Claims

Claims

1. Coil head guide (40) for winding conductive electrical wires of coils (30) around a plurality of rotor teeth (16) of a wound rotor (10) comprising a cylindrical core (41) provided with a central orifice (42) intended to accommodate a rotor shaft (12), and radial branches or guide teeth (43) extending from the cylindrical core (41) and each intended to be positioned opposite a corresponding rotor tooth (16) of the rotor (10), characterized in that it further comprises a plurality of guide pins (45) each extending axially beyond the cylindrical core (41),a first guide pin (45a) of a guide tooth (43) being connected to a second guide pin (45b) of an adjacent guide tooth (43) by a connection portion (46) extending circumferentially between two guide teeth (43) and in that it comprises at least one radial rib (47) for holding the coil wires extending radially towards the central orifice (42) and each arranged circumferentially between two guide teeth (43), at least one radial rib (47) for holding the coil wires extending radially from each connection portion (46).,

2. A coil head guide (40) according to claim 1, wherein each connecting portion (46) extends axially beyond the cylindrical core (41).

3. A coil head guide (40) according to claim 1 or 2, wherein each guide pin (45) extends axially beyond each connection portion (46).

4. A coil head guide (40) according to any preceding claim, wherein each radial rib (47) has a parallelepiped shape.

5. A coil head guide (40) according to any preceding claim, wherein the guide teeth (43) are regularly arranged on the periphery of the cylindrical core (41), the number of guide teeth (43) being equal to the number of rotor teeth (16).

6. A coil head guide (40) according to any preceding claim, comprising guide grooves (44) arranged on the lateral edges of each guide tooth (43) so as to cooperate with the wires of the coils (30).

7. Wound rotor (10) for a rotating electrical machine comprising a rotor shaft (12) with an axis of rotation (X-X'), two coil head guides (40) according to any one of the preceding claims, each arranged at an opposite end of the rotor shaft (12) and coils (30) each wound around a rotor tooth (16) and a guide tooth (43) of the two coil head guides (40) so as to form a rotor pole.

8. Rotor (10) according to claim 7, wherein the cylindrical core (41) of each coil head guide (40) and the rotation shaft (12) of the rotor (10) are concentric with the rotation axis (X-X') and wherein each guide tooth (43) of each coil head guide (40) is axially located opposite a rotor tooth (16).

9. Rotor (10) according to claim 7 or 8, further comprising a core (14) comprising a stack of laminations and mounted coaxially on the rotor shaft (12), the stack of laminations of the core (14) comprising an alternation of rotor teeth (16) and notches (18) regularly distributed in a circumferential direction over a diameter of the core (14), at least each radial rib (47) of the coil head guides (40) being arranged circumferentially in a corresponding notch (18).

10. Rotor (10) according to any one of claims 7 to 9, in which the wire of the coils (30) connecting two adjacent rotor teeth (16) is arranged radially between the corresponding radial rib (47) and the central orifice (42) of the cylindrical core (41) of each coil head guide (40).

11. A rotating electrical machine comprising a rotor (10) wound according to any one of claims 7 to 10.

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