Rotor for a rotating electrical machine

Abstract

The present invention provides a rotor for a rotating electrical machine comprising a body with an X-axis of rotation in which magnets are inserted, a balancing washer mounted on the body and extending transversely to the X-axis of rotation, and a fan mounted on the balancing washer, on the side of the washer opposite the body. The fan comprises at least one pad made of deformable polymer material, and the balancing washer comprises at least one cavity in which the deformable pad is housed such that the pad is axially retained within the cavity. Figure for the abstract: Fig. 5a

Description

Title of the invention: Rotor for a rotating electrical machine

[0001] The invention relates in particular to a rotor for a rotating electrical machine.

[0002] The invention finds a particularly advantageous application in the field of rotating electrical machines such as alternators, alternator-starters or even reversible machines or electric motors. It is recalled that a reversible machine is a rotating electrical machine capable of working reversibly, on the one hand, as an electric generator in alternator function and, on the other hand, as an electric motor for example to start the thermal engine of the vehicle such as a motor vehicle.

[0003] A rotating electrical machine comprises a rotor that rotates about an axis and a fixed stator, mounted in a casing. In alternator mode, when the rotor is rotating, it induces a magnetic field in the stator which transforms it into electric current in order to supply the electrical consumers of the vehicle and recharge the battery. In motor mode, the stator is electrically powered and induces a magnetic field driving the rotor into rotation, for example to start the heat engine.

[0004] The rotor may advantageously comprise a body in which magnets are inserted and a metal balancing washer mounted on the body allowing the machine to be balanced by extrusion of material after its assembly.

[0005] An air-cooled machine also includes fan blades inside the housing. Openings in the housing allow ambient air to circulate between the inside and outside of the machine under the effect of the blades.

[0006] Machine architectures are known in which the balancing washer is provided with fan blades. Such fan blades help to cool the electronic components of the machine. The blades, for example, molded with the metal washer, have relatively simple geometries, which from a thermal point of view does not optimally promote cooling. In addition, several operations in the rotor manufacturing process require the use of the flat surface of the balancing washer as a support or counter-support. The fan blades on the surface of the balancing washer reduce and sometimes make these support surfaces inaccessible.

[0007] The present invention makes it possible to overcome these drawbacks.

[0008] To this end, the present invention therefore relates to a rotor for a rotating electrical machine comprising a body with an axis X of rotation in which magnets are inserted, a balancing washer mounted on the body and extending transversely to the axis X of rotation, a fan mounted on the balancing washer, on the side of the washer opposite the body, characterized in that the fan comprises at least one pad made of deformable polymer material, the balancing washer comprising at least one cavity in which the deformable pad is housed so that the pad is axially retained in the cavity.

[0009] The invention protects a solution for assembling an additional fan on the metal washer. The studs make it possible to guide the positioning of the fan on the washer by assembling the studs in the cavities of the balancing washer. Such cavities dug in the non-magnetic balancing washer do not modify the magnetic properties of the machine.

[0010] A fan with blades of more thermally efficient geometry can therefore be mounted on the washer. The flat surface of the balancing washer can be used as a support or counter-support during the manufacture of the rotor before assembly of said fan. This makes assembly easier and improves cooling.

[0011] The rotor may also comprise at least one pin inserted at least partially into the stud, the pin deforming the stud of the fan so as to axially retain the stud in the cavity.

[0012] The cavity may have a shoulder forming a stop for retaining the stud in the axial direction.

[0013] The stud may comprise a fixing groove which cooperates with the shoulder to ensure the axial retention of the stud in the cavity.

[0014] The fan may comprise a body having a first face from which at least one blade extends and a second face opposite the first face from which the at least one stud extends.

[0015] The at least one stud may be hollow, defining an interior space opening into the first face of the fan body in an opening.

[0016] The opening may have an oblong section in the first face.

[0017] The fan may be annular, a diameter of an outer periphery of the fan being less than a diameter of an outer periphery of the balance washer.

[0018] The blades and the openings may be angularly distributed on the first face of the fan, the first face having a regular alternation of the blades and the openings.

[0019] The invention also relates to a rotating electrical machine comprising such a rotor.

[0020] The present invention also relates to a rotating electrical machine. The rotating electrical machine can, advantageously, form an alternator, an alternator-starter, a reversible machine or an electric motor.

[0021] The present invention may be better understood by reading the description detailed description which will follow, of non-limiting examples of implementation of the invention and of the examination of the appended drawings.

[0022] [Fig.l] represents, schematically and partially, a sectional view of a rotating electrical machine according to the invention.

[0023] [Fig.2] is an exploded view of the rotor according to the invention.

[0024] [Fig. 3] shows, schematically and partially, the balancing washer including cavities.

[0025] [Fig.4] schematically represents the assembly of the fan on the washer.

[0026] [Fig.5a] and [Fig.5b] illustrate the assembly of the fan on the balancing washer.

[0027] [Fig.6a] illustrates the fan provided with studs.

[0028] [Fig.6b] is an enlarged view of an opening in the fan at a plot.

[0029] [Fig.7a] illustrates a centrifugal fan.

[0030] [Fig.7b] illustrates a helical fan.

[0031] Identical, similar or analogous elements retain the same references from one figure to another. It will also be noted that the different figures are not necessarily on the same scale. Furthermore, the exemplary embodiments described below are in no way limiting. In particular, it will be possible to imagine variants of the invention comprising only a selection of characteristics described below isolated from the other characteristics described. In particular, all the variants and all the embodiments described can be combined with each other if nothing prevents this combination from a technical point of view.

[0032] In the following description the term “axially” will designate the direction of the X axis, the term “radially” will designate one of the directions extending from the X axis in a plane perpendicular to the X axis and the term “angularly” will designate one of the directions around the X axis in the plane mentioned previously.

[0033] In the remainder of the description the elements will be described mounted together around the X axis.

[0034] [Fig.l] represents a partial schematic sectional view of a rotating electrical machine 1 having an axis of rotation X. The rotating electrical machine 1 comprises a stator 2 and a rotor 3 in a casing 32. The casing comprises for example a first bearing 5, a second bearing 6 and a tubular spacer 7. The tubular spacer 7 is for example clamped between the first bearing 5 and the second bearing 6, for example by means of tie rods not shown between the first bearing 5 and the second bearing 6. The stator is fixed inside the casing 32, for example mounted tightly in the tubular spacer 7.

[0035] The stator 2 comprises a stator body 9 and a winding 8. The stator body 9 comprises for example a stack of magnetic sheets. For example, the winding 8 comprises electrical conductors, an active part of which passes through notches formed in the body 9 and a connection part or bun 10 is formed outside the notches. The winding 8 is for example a hairpin type winding.

[0036] The rotor 3 comprises a shaft 4 with an axis of rotation X. The shaft is guided in rotation by a first bearing 11 mounted in the first bearing 5 and a second bearing 12 mounted in the second bearing 6. A drive element 13, for example a pulley or a gear, is fixed to the shaft 4.

[0037] The rotor 3 illustrated in exploded view in [Fig.2] also comprises:

[0038] - a body 15 mounted on the shaft 4 and comprising cavities 24, the body having a first end 33 and a second end 34, opposite the first end, in the direction of the axis of rotation X,

[0039] - magnets 23 received in the cavities 24,

[0040] - a first balancing washer 16 mounted on the rotor body at its first axial end 33 and extending transversely to the X axis of rotation of the machine.

[0041] The balancing washer 16 makes it possible to hold the magnets 23 in the cavities 24. The balancing washer 16 comprises a first side 160a and a second side 160b axially opposite the first side 160a, the second side 160b being directly opposite the axial end of the rotor body.

[0042] The washer 16 illustrated in [Fig. 3] comprises cavities 160 hollowed out in the washer and opening out on the first side of the washer 160a. A cavity 160 can be obtained by a forging process, in particular by hot stamping, or by machining.

[0043] The rotor may optionally comprise a second balancing washer preventing the magnets from exiting through the second end 34. This second balancing washer will not be described here.

[0044] The balancing washer 16 advantageously has an annular shape which comprises concentrically from the inside to the outside a central annular portion 16c advantageously perforated connected to an annular portion comprising the cavities 16b connected to an external annular portion 16a. The perforated portion contributes to better ventilation and to lightening the machine.

[0045] The annular portions comprising the cavities 16b and outer 16a advantageously have different thicknesses along X E1, E2 respectively so that the junction between these two portions 16b and 16a creates a step 16d. E1 is typically between 4mm and 10mm to allow good balancing recovery and advantageously greater than 6mm.

[0046] The cavities 160 are advantageously located in the annular portion 16b, on the same circumference of the washer, that is to say a circle drawn on the first side of the washer 160a and having as its center the axis X passes through at least a portion of each cavity 160. Preferably, the radial distances between the axis X and the centers of the cavities 160 are equal for the same washer. In addition, the cavities 160 are angularly spaced from each other by the same angle around the axis X. A symmetrical washer 16 is then obtained. In addition, the cavities 160 are closer to the outer periphery of the washer 163a, defined by the circumference of the largest diameter of the washer, than to the inner periphery, defined by the opening crossed by the shaft.

[0047] Each cavity 160 extends along an axis Y which is parallel to the axis X of rotation of the machine and has a cylindrical or conical shape. Each cavity has a depth PI in an axial direction of between 5% and 100% of the thickness El of the washer taken at the level of said cavity and preferably between 30% and 60%. For example, the cavity has a depth of between 3 and 20 mm. For a washer thickness El of the order of 6 mm, the depth PI of the cavity is typically of the order of 3 mm. Each cavity 160 has a maximum diameter of between 0.02 and 0.2, and in particular between 0.03 and 0.08, times the external diameter of the washer.

[0048] A cavity 160, as illustrated in [Fig.5a], is formed of a bottom 161 and a side wall 162 having a first axial end defining an inlet opening 163 of the cavity and a second axial end opposite said first end which connects the side wall with the bottom. Fillet radii may be provided between the side wall and the bottom and between the side wall and the first side 160a of the washer.

[0049] The cavity 160 advantageously has a shoulder 164 extending from the side wall 162 to form a stop. The shoulder 164 extends substantially transversely, relative to the Y axis of the cavity 160, over the entire circumference of the side wall 162. The shoulder defines an opening 163e whose diameter is less than the largest diameter of the side wall 162.

[0050] For example, the shoulder 164 extends over a height H1, in an axial direction relative to the axis Y, of at least 30% of the depth PI of the cavity 160. Still for example, the shoulder 164 extends over a length L1, in a radial direction relative to the axis Y, comprised between 10% and 30% of the maximum diameter of the cavity taken axially between the bottom 161 and the shoulder 164.

[0051] The shoulder 164 extends at a distance from the first side 160a of the washer. The opening 163e formed by the shoulder is then distinct from the inlet opening 163 of the cavity 160. For example, an axial height H2 between the shoulder 164, in particular the apex 164s of said shoulder, and the first side of the plate of the washer 160a is at least 15% of the depth PI of the cavity. The apex 164s of the shoulder is the point from which the shoulder has the smallest diameter. For example, the axial height H2 is at least 2 mm and the depth PI of the cavity is 6 mm.

[0052] For example, in this variant embodiment, the cavity 160 has an upper portion 162a located axially between the first side of the washer 160a and the shoulder 164 and a lower portion 162b located axially between the shoulder 164 and the bottom 161 of the cavity. The portions 162a, 162b are independent of one another and may have characteristics such as a different shape, dimensions or angle of inclination relative to the Y axis of the cavity. For example, a maximum diameter of the upper portion 162a is greater than a maximum diameter of the lower portion 162b. Still for example, the upper portion 162a may have a different shape from the lower portion 162b. Thus, the lower portion 162b may have a cylindrical shape and the upper portion 162a may have a rectangular shape. This rectangular shape allows the fan to be locked in rotation relative to the polar wheel.

[0053] The shoulder has a first portion 164a and a second portion 164b, said portions being separated from each other by the top 164 of the shoulder defining the opening 163e. The first portion 164a extends opposite the upper part 162a and the second portion 164b extends opposite the lower part 162b. For example, the first portion 164a extends substantially radially relative to the Y axis and the second portion 164b forms a curvature.

[0054] The rotor 3 also comprises a fan 20 mounted on the balancing washer 16 on the first side of the washer 160a. The fan comprises blades 202 capable of moving a fluid, in particular air, from a first radially inner position to a second radially outer position.

[0055] The fan 20 advantageously comprises a body 201 from which blades 202 extend. The blades 202 extend from a first face of the body 201a.

[0056] The body 201 of the fan advantageously has an annular shape extending between an inner periphery 20a and an outer periphery 20b. The radial distance between the inner peripheries 20a and outer 20b of the fan, that is to say the diameter of the fan, is advantageously the same as that between the inner and outer peripheries 161b and 162b respectively of the annular portion 16b, that is to say the diameter of said portion 16b. In addition, the diameter of the outer periphery of the fan 20b is advantageously the same as the diameter of the outer periphery 162b of the portion 16b. The fan 20 is advantageously wedged in the recess 16d of the balancing washer 16. The fan 20 advantageously does not cover the perforated central annular portion of the washer 16c.

[0057] The blades 202 advantageously protrude radially from the body 201 as illustrated in [Fig.4] and extend axially above the outer annular part 16a of the balancing washer. The body 201 therefore only covers part of the face of the washer 16, the rest of the face of the washer being able to be used as a support surface for example.

[0058] The fan 20 is mounted on the balancing washer 16 by a second face of the body 201b opposite the first face 201a.

[0059] The second face of the fan 201b comprises studs 50 made of deformable polymer material. These studs 50 extend in projection transversely to this second face 201b. These studs extend in an axial direction opposite to the direction of extension of the blades 202 of the fan.

[0060] The fan 20 is mounted on the washer 16 by inserting the pads 50 of the fan into the cavities 160 of the washer. For this purpose, each pad 50 of the fan is opposite at least one cavity 160 of the washer. There is therefore a radial and angular distribution of the pads 50 of the fan around the axis X, which is the same as the distribution of at least a portion of the cavities 160 of the washer.

[0061] In a first embodiment, the polymer studs 50 are overmolded onto the body 201 of the fan. The stud 50 is mounted housed in the cavity 160 of the corresponding balancing washer 16 and then a pin 51 inserted at least partially into the stud 50 deforms the stud so as to retain it axially in the cavity.

[0062] The stud 50 advantageously has a substantially hollow cylindrical shape defining an interior space opening into the first face of the body 201 in an opening 54. The stud 50 extends into a hollow insertion portion 55, a pin being inserted into said insertion portion 55. The cavity 160 therefore surrounds the insertion portion 55.

[0063] The insertion portion 55 may comprise a fixing groove 56 whose shape is complementary to the shape of the shoulder 164 to cooperate with said shoulder in order to hold the fan 20 in the balancing washer 16, under the action of the pin 51, this action of the pin being carried out by a mechanical constraint of the insertion portion 55 in a transverse direction towards the outside, that is to say towards the wall 162 of the cavity 160.

[0064] Thus, the insertion portion 55 has a first position before fixing, illustrated in [Fig.5a] in which the pin 51 is not inserted into the opening 54 or is inserted only on a small portion not allowing the deformation of said fixing portion. In this position, the insertion portion 55 extends in an axial direction and does not cooperate with the cavity 160.

[0065] The insertion portion 55 has a second fixing position, illustrated in [Fig.5b], in which the pin 51 is inserted through the opening 54 exerting a mechanical stress on said insertion portion 55 to ensure mechanical cooperation between the insertion portion 55 and the cavity 160 and in particular between the groove fixing portion 56 and the shoulder 164 to allow the fan 20 to be fixed to the washer 16. The insertion portion 55 therefore passes from a position before fixing to a fixing position by deformation under the stress of the pin 51. In this position, the insertion portion 55 extends in a direction inclined relative to an axial direction.

[0066] In an exemplary embodiment illustrated in Figures 6a and 6b and compatible with any of the embodiments described above, the opening 54 is extended by two grooves 60 extending transversely in the body 201 and forming a through opening of oblong shape. The two grooves 60 extend for example in a diametrically opposite manner relative to each other around the opening 54. For example, an adhesive such as resin or a varnish may be placed in the cavity 160 in order to improve the retention of said fan on the balancing washer, said groove 160 facilitating this insertion.

[0067] In a variant not illustrated, the cavities may open out on either side of the balancing washer.

[0068] The blades 202 and the openings 54 are angularly distributed on the first face 201a of the fan, the first face 201a having a regular alternation of the blades 202 and the openings 54, as illustrated in [Fig.6a].

[0069] As a variant of this embodiment, the fan will be entirely made of deformable polymer. The deformable polymer used may optionally contain fibers, typically long fibers for mechanical strength, for example with a content of 30%.

[0070] The fan will for example be obtained by plastic molding, the blades 202 being for example formed from the same material as the body 201. The weight of the machine is reduced by the use of such a fan in comparison with metal blades according to the prior art.

[0071] In addition, the molding makes it possible to provide fans with blades whose geometries make it possible to optimize cooling. The plastic fan has, for example, blades 202 deformed along a single axis, as illustrated in [Fig.7b] forming a helical fan. Alternatively, the blades of the plastic fan are deformed axially and radially, as illustrated in [Fig.7a] forming a centrifugal fan.

[0072] In a second embodiment the fan will be mounted on the balancing washer by snap-fastening, the stud being deformed to be inserted into the cavity of the washer then being locked in position in the cavity after having substantially returned to its initial shape.

[0073] The rotor may optionally comprise a clamping means supporting the assembly formed by the balancing washer 16 and the fan 20 directly or indirectly. on the first end 33 of the body 15..

Claims

Claims

1. Rotor (3) for a rotating electrical machine comprising: - a body (15) with an axis X of rotation in which magnets (23) are inserted, - a balancing washer (16) mounted on the body (15) and extending transversely to the axis X of rotation, - a fan (20) made entirely of deformable polymer mounted on the balancing washer (16), on the side of the washer (160a) opposite the body, characterized in that the fan (20) comprises at least one stud (50) made of deformable polymer material, the balancing washer (16) comprising at least one cavity (160) in which the deformable stud (50) is housed so that the stud (50) is axially retained in the cavity (160).

2. Rotor for a rotating electrical machine also comprising at least one pin (51) inserted at least partially into the stud (50), the pin (51) deforming the stud (50) of the fan so as to axially retain the stud (50) in the cavity (160).

3. Rotor for a rotating electrical machine according to any one of the preceding claims in which the cavity (160) has a shoulder (164) forming a stop for retaining the stud (50) in the axial direction.

4. Rotor according to claim 3 in which the stud (50) comprises a fixing groove (56) which cooperates with the shoulder (164) to ensure the axial retention of the stud (50) in the cavity (160).

5. Rotor according to any one of the preceding claims in which the fan (20) comprises a body (201) having a first face (201a) from which at least one blade (202) extends and a second face (201b) opposite the first face from which the at least one stud (50) extends.

6. Rotor according to claim 5 in which the at least one stud (50) is hollow defining an interior space opening into the first face (201a) of the fan body in an opening (54).

7. Rotor according to claim 6 in which the opening (54) is of oblong section in the first face (201a).

8. A rotor according to any one of claims 5 to 7 wherein the fan (20) is annular, a diameter of an outer periphery of the fan (20b) being less than a diameter of an outer periphery of the balance washer (163a).

9. Rotor according to any one of claims 6 to 8 in which the blades (202) and the openings (54) are angularly distributed on the first face (201a) of the fan, the first face (201a) having a regular alternation of the blades (202) and the openings (54).

10. Rotating electrical machine comprising a rotor (3) according to one of the preceding claims.

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