Arrangement comprising an electric motor rotor and a ring attached to the rotor

Abstract

The invention relates to an arrangement comprising: • an electric motor rotor comprising a rotor shaft which extends along a first axis, and a circular structure which is arranged at one end of the rotor shaft in a plane perpendicular to the first axis, the circular structure comprising at least one rotor tooth and at least one winding of electric wire which is arranged around the at least one tooth; and • a ring which is attached to the circular structure so as to surround the circular structure, characterised in that the ring comprises a set of through-holes, each through-hole being arranged so as to be intersected by a radial plane which contains the first axis and passes through a centre of a winding of electric wire arranged around the at least one tooth, thus creating circulation of a cooling fluid through the winding.

Description

Description Title of the invention: Arrangement comprising an electric motor rotor and a ring gear fixed to the rotor.

[0001] The invention relates to an arrangement comprising an electric motor rotor and a ring gear attached to the rotor. The invention also relates to an electric motor comprising an arrangement according to the invention. The invention further relates to a vehicle equipped with such an electric motor. The invention also relates to a method of manufacturing a ring gear of an arrangement according to the invention.

[0002] Rotating electric machines are very efficient. However, the manufacturing process of such machines requires addressing significant challenges, particularly in improving the reliability of electric motors, especially electrically excited synchronous motors, and in increasing the rotational speed of the rotors of such motors.

[0003] For this purpose, optimizing the cooling of the rotor and stator windings of the electric motor is crucial.

[0004] Document FR3059487 discloses a rotor winding holding ring which improves the cooling of the rotor windings.

[0005] However, this solution has drawbacks. In particular, this solution generates a circulation of cooling fluid in an air gap bordering the rotor. In addition, this solution does not allow for optimized cooling of the stator windings.

[0006] The object of the invention is to provide an arrangement comprising an electric motor rotor and a ring gear fixed to the rotor, overcoming the above drawbacks and improving the arrangements comprising an electric motor rotor and a ring gear fixed to the rotor known from the prior art, as well as a method for manufacturing a ring gear of such an arrangement. In particular, the invention makes it possible to provide an arrangement and a method which are simple and reliable and which improve the reliability of an electric motor while making it possible to increase a rotational speed of the rotors of such motors.

[0007] For this purpose, the invention relates to an arrangement comprising • an electric motor rotor comprising o a rotor shaft extending along a first longitudinal axis and o a circular structure arranged at one end of the rotor shaft along a first plane perpendicular to the first axis, the circular structure comprising at least one tooth of the rotor and at least one winding of electric wire arranged around T at least one tooth, and • a crown fixed to the circular structure so as to envelop the circular structure, and the crown comprises a set of through holes, each through hole being arranged so as to be intersected by a radial plane containing the first longitudinal axis and passing through a center of a winding of electric wire arranged around the at least one tooth, so as to create a circulation of a cooling fluid through said winding of electric wire.

[0008] In one embodiment, the crown is capable of holding in place windings of electrical wires of the rotor.

[0009] In one embodiment, the through holes are arranged at a rounded corner of the crown, the rounded corner being located between on the one hand a tubular portion of the crown centered on a second longitudinal axis and on the other hand a given face of the crown, the given face being perpendicular to the second longitudinal axis.

[0010] In one embodiment, the crown comprises: - a first part comprising the tubular portion, the rounded angle and the given face, and - a second part, in particular in the form of a pancake, fixed to the given face of the first part.

[0011] In one embodiment, the arrangement further comprises a stator disposed around the ring gear, and the second portion provides a guide surface for a coolant flowing through a through hole in the ring gear, so as to direct the coolant toward electrical wire windings of the stator.

[0012] In one embodiment, the through holes of the crown are arranged so as to be crossed by a second plane perpendicular to the first longitudinal axis, the second plane passing through the center of at least one winding of electrical wires of the stator.

[0013] In one embodiment, the arrangement comprises at least one nozzle for delivering a cooling fluid near the winding disposed around the at least one tooth, and a projection of one end of the at least one nozzle onto a third plane passing through a through hole and perpendicular to the first longitudinal axis is substantially located on a straight line connecting a through hole of the crown to a point of intersection between the third plane and the first longitudinal axis.

[0014] In one embodiment, each through hole of the crown is oblong or oval in shape, and / or a smallest dimension of each through hole is measured along the second longitudinal axis.

[0015] The invention further relates to an electric motor comprising an arrangement according to the invention.

[0016] The invention also relates to a motor vehicle comprising an arrangement according to the invention or an electric motor according to the invention.

[0017] The invention further relates to a method of manufacturing a crown of an arrangement according to the invention, comprising • a step of drilling through holes in a given portion of a cylindrical part intended to form the first part of the crown, the given portion being defined along a longitudinal axis of the cylindrical part, then • a step of stamping the cylindrical part allowing the given portion to be curved, so that a given end of the cylindrical part is located in a plane perpendicular to the longitudinal axis of the cylindrical part, then • a step of fixing the second part of the crown on the given end.

[0018] Other details, characteristics and advantages will emerge more clearly on reading the detailed description given below, for informational and non-limiting purposes, in relation to the various examples of embodiment illustrated in the following figures:

[0019] [Fig.l] schematically represents a motor vehicle equipped with an arrangement according to the invention.

[0020] [Fig.2] is a perspective view of a crown of an arrangement according to the invention.

[0021] [Fig. 3] is a cross-sectional view of an arrangement according to the invention.

[0022] [Fig.4] is a longitudinal sectional view of an arrangement according to the invention.

[0023] [Fig.5] is a perspective view of a crown of an arrangement without implementing the invention.

[0024] [Fig.6] is a cross-sectional view of an arrangement without implementing the invention.

[0025] [Fig.7] is a longitudinal sectional view of an arrangement without implementing the invention.

[0026] An embodiment of a motor vehicle 100 is described below with reference to [Fig.l]. The motor vehicle 100 may be an electric or hybrid motor vehicle. Also, the vehicle 100 may be a private vehicle, a utility vehicle or one dedicated to public transport.

[0027] The motor vehicle 100 is equipped with an electric motor 1, of the rotating electric machine type, comprising a rotor 2 and a stator 3. The rotor 2 is part of an arrangement 10 according to the invention.

[0028] The arrangement 10 according to the invention comprises: - the rotor 2, comprising i) a rotor shaft 21 extending along a first longitudinal axis XI and ii) a circular structure 22 arranged at one end of the rotor shaft 21 and extending along a first plane PI perpendicular to the first axis XI, the circular structure 22 comprising at least one tooth 221 of the rotor 2 and a winding of electric wire 222 arranged around F at least one tooth 221, and - a crown 4 fixed to the circular structure 22 so as to envelop the circular structure 22. In addition, the crown 4 comprises a set of through holes 41, each through hole 41 being arranged to be intersected by a median radial plane PRM containing the first longitudinal axis XI and passing through the center of an electric wire winding 222 arranged around at least one tooth 221, so as to create a circulation of a cooling fluid through said electric wire winding 222.

[0029] In one embodiment, a hole 41 could be arranged to be intersected by a radial plane PR1 containing the first longitudinal axis XI, the plane PR1 making an angle of a few degrees with the median radial plane PRM. Thus, a tolerance of a few degrees could apply to a radial alignment between a hole 41 and the center of the electrical wire winding 222, this tolerance defining "a middle zone" of the winding 222.

[0030] In the remainder of the document, the winding of electric wire 222 is also called bun 222 or winding 222. The arrangement 10 advantageously comprises a plurality of buns 222, each bun 222 being able to be - wrapped around a tooth of the circular structure 22, or - wrapped around two adjacent teeth of the circular structure 22, or - wrapped around two non-adjacent teeth of the circular structure 22.

[0031] In the remainder of the document, we consider that the first longitudinal axis XI is oriented towards the crown 4.

[0032] With reference to [Fig.2], a second longitudinal axis X2 is also defined corresponding to a longitudinal axis of the crown 4. When the crown 4 is integrated into the arrangement 10, the first and second longitudinal axes XI, X2 are merged.

[0033] An embodiment of a circular structure 22 of an arrangement according to the invention is more specifically visible in Figures 3 and 4. [Fig. 3] is a view of an arrangement 10 in cross-section, that is to say according to a section made in a plane perpendicular to the first longitudinal axis XL [Fig. 4] is a partial view of an arrangement 10 in longitudinal section, that is to say according to a section made in a plane containing the first longitudinal axis XL

[0034] In the embodiment of the invention described in this document, one of the functions of the crown 4 is to hold the rotor windings in place.

[0035] Figures 3 and 5 illustrate the geometry of a crown 4 of an arrangement 10 according to an embodiment of the invention.

[0036] In one embodiment, the through holes 41 are arranged at a rounded angle 421 of the crown 4, the rounded angle 421 being located between on the one hand a tubular portion 420 of the crown 4 centered on a second longitudinal axis X2 and on the other hand a given face 422 of the crown 4, the given face 422 being perpendicular to the second longitudinal axis X2.

[0037] The through holes 41 are therefore made on a thickness of curved material.

[0038] In addition, the crown 4 comprises a first and a second disjointed part 42, 43, and a means 44 for fixing the second part 43 on the first part 42, - a first part 42 comprising the tubular portion 420, the rounded angle 421 and the given face 422, and - a second part 43, in particular in the form of a pancake, fixed to the given face 422 of the first part 42, the fixing means 44 being able to be produced by screws.

[0039] The second part 43 of the crown 4 is used for balancing the rotor 2. In particular, the second part 43 can be drilled to improve the rotation of the rotor 2, in particular to reduce the unbalance.

[0040] The through holes 41 of the crown 4 are distributed angularly around the second longitudinal axis X2 on the rounded angle 421, as is more particularly visible in [Fig.2],

[0041] In addition, the through holes 41 of the crown are oblong or oval in shape, and / or a smaller dimension of each through hole is measured along the second longitudinal axis X2. In other words, a dimension of a given hole 41, measured along the longitudinal axis XI, is strictly less than a dimension of the given hole 41 measured along a dimension perpendicular to the longitudinal axis XL.

[0042] When the crown 4 is mounted in the arrangement 10, the respective first and second longitudinal axes XI, X2 are substantially coincident.

[0043] The stator 3 of the arrangement 10 is arranged around the ring 4, and the second part 43 provides a guide surface 431 for a cooling fluid flowing through a through hole 41 of the ring 4, so as to direct the cooling fluid towards windings of electrical wires 32 of the stator 3. For this purpose, the surface 431 may be non-planar, so as to promote a direction of flow of the cooling fluid towards the coils 32.

[0044] Furthermore, advantageously, the through holes 41 of the crown 4 are arranged so as to be crossed by a second plane P2 perpendicular to the first longitudinal axis XI, the second plane P2 passing through the center of at least one winding 32 of electric wires of the stator 3.

[0045] In one embodiment, the center of the winding 32 could be separated from the plane P2 of a small longitudinal distance, for example the longitudinal distance being a few millimeters. Thus, a tolerance of a few degrees could apply to an alignment between a hole 41 and the center of the electric wire winding 32, this tolerance defining “a middle zone” of the winding 32.

[0046] The buns 222 are cooled by a circulation of cooling fluid. In one embodiment, the cooling fluid is conveyed to the buns 222 by nozzles 6 (not shown in the figures). Advantageously, the nozzles 6, in particular the ends 61 of the nozzles 6, are distributed around the rotor shaft 21 according to a circle 62 centered on the axis X and so as to be respectively located opposite each bun 222, in particular opposite a middle zone of each bun.

[0047] The circle 62 on which the ends 61 of the nozzles 6 are distributed is preferably defined in a plane perpendicular to the first longitudinal axis XL. Advantageously, a projection of the end 61 of each nozzle onto a third plane P3, passing through a through hole 41 and perpendicular to the first longitudinal axis XI, is substantially located on a straight line connecting a through hole 41 of the crown 4 to a point of intersection C2 between the third plane P3 and the first longitudinal axis XL.

[0048] A path of the cooling fluid in an arrangement according to the invention is shown in [Fig. 4] by arrows 11, 12, 13, 14. The nozzles 6 distributed opposite each rotor bun 222 around the circle 62 distribute a cooling fluid in a direction 11 perpendicular to the rotor bun 222. Then the fluid is guided by the surface of the bun 222 in a direction 12 substantially oriented towards the hole 41 located opposite the bun 222. After having passed along the bun 222, the fluid takes a direction 13 which directs it towards the guide surface 431 located opposite a middle zone of a stator bun. The fluid then follows the direction 14 favored by the guide surface 431, and reaches a middle zone of a stator bun.

[0049] The invention further relates to a method of manufacturing a crown 4 of an arrangement 10 according to the invention, comprising • a step E1 of drilling through holes 41 in a given portion 421 of a cylindrical part intended to form the first part 42 of the crown, the given portion 421 being defined along a longitudinal axis XI of the cylindrical part, then • a step E2 of stamping the cylindrical part making it possible to curve the given portion 421, so that a given end 422 of the cylindrical part is located in a plane perpendicular to the longitudinal axis XI of the cylindrical part, then • a step E3 of fixing the second part 43 of the crown 4 on the given end 422.

[0050] In step E1, through holes 41 are drilled in a given portion 421 of a cylindrical part intended to form the first part 42 of the crown, the given portion being defined along the longitudinal axis XI. In other words, the holes 41 of the crown 4 are drilled in a given portion of the cylinder intended to be stamped during step E2.

[0051] In step E2, the portion 421 of the first part 42 is stamped, which has the effect of curving it towards the inside of the cylinder. A first segment 421 of the curved end then has a profile in the shape of an arc of a circle. A second segment 422 of the curved end extends along a plane perpendicular to the longitudinal axis XI. The second segment 422 then provides a fixing surface 4221 for the second part 43 of the crown 4.

[0052] Then in step E3, the second part 43 is fixed to the fixing surface 4221 of the given end 422. In one embodiment, the second part 43 is screwed to the fixing surface 4221.

[0053] Thus, in the manufacturing method according to the invention, the cylindrical portion of the crown is not manufactured by stamping, unlike the crown which is described in patent FR3059487. This difference makes it possible to improve the fit between the cylindrical portion of the crown and an adjacent part which borders the cylindrical portion of the crown. This reduces the risk of creating an air gap between the cylindrical portion and the adjacent part. As a result, the losses of cooling fluid in the cooling circuit of the electric motor 1 are reduced.

[0054] Another difference with the invention described in patent FR3059487 lies in the fact that the drilling of the holes takes place before the stamping, which limits the risks of cracks around the holes during drilling. In addition, the fact that the stamping takes place after the drilling of the holes makes it possible to simply obtain holes on a curved area of ​​the crown 4.

[0055] We thus obtain a crown 4 intended to be arranged in an arrangement 10.

[0056] The shape of the crown 4 of the arrangement 10, and in particular the axial and angular positioning of the through holes 41, are advantageous compared to a prior art described in patent FR3059487 and illustrated by figures 5 to 7.

[0057] The technical solution described in patent FR3059487 implements a crown 8, which differs from the crown 4. One difference lies in the longitudinal position of the holes 81 of the crown 8, which are located in a middle zone of a cylinder formed by the crown 8. Thus, compared to the holes 41 of the crown 4, the holes 81 of the crown 8 are closer to an air gap 9 of the electric motor, which increases the risk of creating an undesirable flow of cooling fluid in the air gap, the flow taking place by capillarity on the crown. In addition, the longitudinal position of the holes 81 of the crown 8 is substantially offset relative to the stator windings, which does not allow the cooling efficiency to be optimized. stator windings. Furthermore, the crown 8 does not provide a surface intended to guide the cooling fluid exiting the holes 81 towards the stator windings.

[0058] Another difference between the invention of patent FR3059487 and the arrangement 10 according to the invention lies in the angular position of the holes 81 of the ring 8 relative to the rotor windings, the holes 81 being arranged facing a space separating two rotor windings. As a result, the cooling fluid only partially cools the rotor windings, because the angular position of the holes 81 promotes a movement of the cooling fluid towards the space separating two windings. Conversely, the axial and angular positioning of the through holes 41 of the arrangement 10 according to the invention improves and optimizes the cooling of the rotor2 and the stator 3. Indeed, the longitudinal position of the holes 41 of the ring 4 are located opposite the coils of the stator 3, which makes it possible to optimize the efficiency of the cooling of the windings of the stator 3.In addition, the holes 41 of the ring 4 are located at a distance from the air gap 9 of the electric motor, which considerably reduces the risk of creating an undesirable flow of cooling fluid in the air gap. Furthermore, the ring 4 comprises a surface 4213 intended to guide the cooling fluid leaving the holes 41 towards the stator windings. In addition, the angular position of the holes 41 of the ring 4 relative to the windings of the rotor 2 is optimized, because the holes 41 are arranged opposite a middle zone of a rotor winding. Thus, the angular position of the holes 41 promotes a movement of the cooling fluid from one end to the other of a rotor winding.

[0059] Another consequence of the differences between the crown 8 of the prior art and the crown 4 of an arrangement according to the invention relates to the mechanical strength of the crown. Cracks 82 have been observed around holes 81, the cracks being linked to a deformation of the crown created by centrifugal force during operation of the electric motor incorporating the crown 8. Calculation simulations have shown that, during operation of the electric motor, the mechanical stresses exerted on a hole 81 of the crown 8 of the prior art are significantly greater than the mechanical stresses exerted on a hole 41 of the crown 4 according to the invention. In particular, the arrangement of the holes 41 on the rounded part 421 of the crown 4 makes it possible to significantly reduce the mechanical stresses exerted on the holes 41.Results of calculation simulations have shown that a crown 4 of an arrangement 10 according to the invention has mechanical resistance characteristics which allow an increase in engine speed of a thousand revolutions per minute, corresponding to an increase in torque of the order of 15%, compared to a crown of the prior art.

[0060] Furthermore, the method of manufacturing the crown 4 according to the invention is simplified compared to a method of manufacturing the crown 8.

[0061] Finally, in an arrangement according to the invention, the positioning and shape of the cooling fluid discharge holes make it possible to improve the reliability and rotation speed of the rotors by reducing the mechanical stresses exerted around the holes.

[0062] In addition, an arrangement according to the invention makes it possible to improve the cooling of the rotor and the stator, thus improving the operation of the cooling circuit of the electric motor while reducing the flow rate of a pump in the cooling circuit. Reducing the flow rate of the pump makes it possible, on the one hand, to reduce the cost of the cooling circuit and, on the other hand, to increase the performance of the electric vehicle.

Claims

Claims

1. Arrangement (10) comprising • a rotor (2) of an electric motor (1) comprising - a rotor shaft (21) extending along a first longitudinal axis (XI) and - a circular structure (22) arranged at one end of the rotor shaft (21) along a first plane (PI) perpendicular to the first axis (XI), the circular structure (22) comprising at least one tooth (221) of the rotor (2) and at least one winding of electric wire (222) arranged around at least one tooth (221), and • a crown (4) fixed to the circular structure (22) so as to envelop the circular structure (22), characterized in that the crown (4) comprises a set of through holes (41), each through hole (41) being arranged so as to be intersected by a radial plane (PR) containing the first longitudinal axis (XI) and passing through a center of a winding of electric wire (222) arranged around the at least one tooth (221), so as to create a circulation of a cooling fluid through said winding of electric wire (222).

2. Arrangement according to the preceding claim, characterized in that the crown (4) is capable of holding in place windings of electrical wires of the rotor (2).

3. Arrangement (10) according to one of the preceding claims, characterized in that the through holes (41) are arranged at a rounded angle (421) of the crown (4), the rounded angle (421) being located between on the one hand a tubular portion (420) of the crown (4) centered on a second longitudinal axis (X2) and on the other hand a given face (422) of the crown (4), the given face (422) being perpendicular to the second longitudinal axis (X2).

4. Arrangement (10) according to the preceding claim, characterized in that the crown (4) comprises - a first part (42) comprising the tubular portion (420), the rounded angle (421) and the given face (422), and - a second part (43), in particular in the shape of a pancake, fixed to the given face (422) of the first part (42).

5. Arrangement (10) according to the preceding claim further comprising a stator (3) arranged around the crown (4), characterized in that the second part (43) provides a guide surface (431) for a cooling fluid flowing through a through hole (41) of the crown (4), so as to direct the cooling fluid towards windings of electrical wires (32) of the stator (3).

6. Arrangement according to one of the preceding claims, characterized in that the through holes (41) of the crown (4) are arranged so as to be crossed by a second plane (P2) perpendicular to the first longitudinal axis (XI), the second plane (P2) passing through the center of at least one winding (32) of electric wires of the stator (3).

7. Arrangement according to one of the preceding claims, characterized in that it comprises at least one nozzle (6) intended to convey a cooling fluid close to the winding (222) arranged around the at least one tooth (221), and in that a projection of one end (61) of the at least one nozzle (6) on a third plane (P3) passing through a through hole (41) and perpendicular to the first longitudinal axis (XI) is substantially located on a straight line connecting a through hole (41) of the crown (4) to a point of intersection (C2) between the third plane (P3) and the first longitudinal axis (XI).

8. Arrangement according to one of the preceding claims, characterized in that each through hole (41) of the crown (4) is oblong or oval in shape, and / or in that a smaller dimension of each through hole (41) is measured along the second longitudinal axis (X2).

9. An electric motor comprising an arrangement according to one of the preceding claims.

10. Motor vehicle comprising an arrangement according to one of claims 1 to 8 or an electric motor according to the preceding claim.

11. Method of manufacturing a crown (4) of an arrangement (10) according to one of claims 4 to 8, characterized in that it comprises a step (El) of drilling through holes (41) in a given portion (421) of a cylindrical part intended to form the first part (42) of the crown (4), the portion given (421) being defined along a longitudinal axis (XI) of the cylindrical part, then a step (E2) of stamping the cylindrical part making it possible to curve the given portion (421), so that a given end (422) of the cylindrical part is located in a plane perpendicular to the longitudinal axis (XI) of the cylindrical part, then a step (E3) of fixing the second part (43) of the crown (4) on the given end (422).

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