Electric motor and corresponding production process

Abstract

The electric motor (1) comprises a stator (3), a rotor (5), a rotating shaft (7) driven in rotation about a rotation axis (X) by the rotor (5), a fan (9), and a damper (13) that rotationally connects the fan (9) to the rotating shaft (7). The damper (13) comprises: - a hub (15) mounted on the rotating shaft (7); - a fan support (17) on which the fan (9) is fixed; - a damper (19) made of an elastically deformable material, the fan support (17) being fixed to the hub (15) only by means of the damper (19).

Description

[0001] The present invention relates in general to a self-ventilating electric motor, that is to say, comprising a fan arranged to cool the electric motor.

[0002] Such an electric motor may include a stator, a rotor, a rotating shaft driven by the rotor, and a fan mounted on the rotating shaft. The fan is arranged to blow an airflow over the rotor and stator when the rotor turns, thus cooling the electric motor.

[0003] Document JP H07 213017 A discloses an electric motor comprising a shock absorber according to the preamble of claim 1.

[0004] A constant objective in the field is to minimize the mass of rotating parts, and to improve the aerodynamic performance of the fan.

[0005] To this end, the invention relates to an engine according to claim 1 and a manufacturing method according to claim 9.

[0006] Because the fan bracket is attached to the hub only via the shock absorber, the fan bracket is mechanically decoupled from the hub, and therefore from the rotating shaft.

[0007] Vibration transfer between the rotor and the fan is reduced. As a result, it becomes possible to reduce the fan's mass and rigidity. Consequently, its aerodynamic performance can be improved.

[0008] The invention is particularly useful in the case of an electric motor powered by a PWM (Pulse Width Modulation) voltage signal. Such a voltage signal generates torque variations in the rotating shaft, which propagate to the fan in the absence of a shock absorber. The presence of the shock absorber protects the fan and leads to a reduction in its mechanical dimensions.

[0009] The electric motor may also have one or more of the following characteristics, considered individually or in all technically possible combinations: the hub and the fan support together define a substantially closed cavity, having a conjugate shape to that of the shock absorber, in which the shock absorber is cast; the hub is bonded to the shock absorber, and the fan support is bonded to the shock absorber; the shock absorber is a ring comprising: a ring centered on the axis of rotation having first and second large substantially annular faces, a radially internal slice and a radially external slice, and a cylindrical wing coaxial to the axis of rotation, extending axially from the second large face, having a radially internal surface, a radially external surface and an annular end surface;the hub is a plate rigidly fixed to the rotating shaft, having a slice and a large front face having an edge area adjoining the slice, the hub being in contact by the edge area with the second large face of the shock absorber and by the slice with the radially internal surface of the cylindrical wing of the shock absorber; the fan support comprises first and second half-rings removably fixed to each other, and arranged axially on either side of the shock absorber; the first half-ring comprises a first annular part in contact with the first large face of the shock absorber, and a first cylindrical part integral with the first annular part and in contact with the radially internal slice of the ring of the shock absorber;The second half-ring comprises a second annular part in contact with the annular end surface of the cylindrical part of the shock absorber, and a second cylindrical part integral with the second annular part in contact with the radially external surface of the cylindrical wing of the shock absorber and with the radially external edge of the shock absorber ring; the first annular part carries teeth cooperating with complementary teeth of the ring, the hub carrying other teeth cooperating with other complementary teeth of the ring.

[0010] According to a second aspect, the invention relates to a method for manufacturing an engine having the above characteristics, the method comprising the following steps: mounting the hub and fan support on a tool, the hub and fan support together defining the substantially closed cavity having a conjugate shape to that of the shock absorber; casting the shock absorber into the cavity, the hub and fan support being fixed to each other exclusively by the shock absorber after cooling of the shock absorber.

[0011] Other features and advantages of the invention will become apparent from the detailed description given below, by way of example and not limitation, with reference to the attached figures, including: There figure 1 is a perspective view, partially exploded, of an electric motor according to the invention, the stator being represented schematically; The figure 2 is an exploded perspective view of the shock absorber of the figure 1 ; and La figure 3 is an exploded perspective view of certain parts of the shock absorber of the figure 2 .

[0012] The electric motor 1 shown on the figure 1 is typically a traction motor of a railway vehicle, for example a train, or a tram.

[0013] Alternatively, this electric motor is a traction motor for a vehicle other than a railway vehicle, for example, a motor vehicle such as a car or truck. Conversely, the electric motor is not a traction motor but equips a static installation of any type.

[0014] As seen on the figure 1 , the electric motor 1 comprises a stator 3, a rotor 5, a rotating shaft 7 driven in rotation around an axis of rotation X by the rotor 5, and a fan 9.

[0015] The electric motor 1 is electrically powered by an electrical power supply 11.

[0016] The power supply 11 supplies the electric motor 1 with a PWM type electric current.

[0017] Typically, the power supply provides electrical power to stator 3.

[0018] The axis of rotation X corresponds to the central axis of the rotor 5 and the stator 3.

[0019] The rotating shaft 7 is fixed to the rotor 5, and protrudes out of the rotor 5 along the axis of rotation X.

[0020] Fan 9 is suitable for any type. It rotates around the X axis of rotation. It is configured to blow an airflow towards the rotor 5 and the stator 3, axially.

[0021] According to the invention, the electric motor includes a damper 13 linking the fan 9 in rotation to the rotating shaft 7.

[0022] Shock absorber 13, as seen on the figure 2 , understand : A hub 15, mounted on the rotating shaft 7; A fan support 17, on which the fan 9 is fixed; A shock absorber 19 made of an elastically deformable material.

[0023] The fan support 17 is advantageously fixed to the hub 15 only by means of the shock absorber 19.

[0024] In other words, all forces passing between the hub 15 and the fan support 17 are transmitted through the shock absorber 19. In particular, the vibrations propagating in the rotating shaft 17 are transmitted to the fan 9 through the shock absorber 19, and only through the shock absorber 19, these vibrations being at least partially absorbed by the shock absorber 19.

[0025] The shock absorber 19 is designed to absorb vibrations in three directions: radially with respect to the axis of rotation X, tangentially around the axis of rotation X, and axially along the axis of rotation X.

[0026] Advantageously, the hub 15 and the fan support 17 together define a substantially closed cavity 21, having a conjugate shape to that of the shock absorber 19.

[0027] As described below, the shock absorber 19 is advantageously cast in the cavity 21.

[0028] Thus, the hub 15 is adhered to the shock absorber 19, and the fan support 17 is also adhered to the shock absorber 19.

[0029] This makes it very easy to produce the shock absorber in the desired shape and dimensions.

[0030] This also allows for quick and convenient attachment of the hub 15 to the fan bracket 17. No further assembly steps are required to connect the hub and fan bracket. In particular, no mechanical components such as screws, tie rods, or any similar parts are used to secure the hub and fan bracket.

[0031] Vibration damping from the hub to the fan mount is excellent, because these vibrations are transmitted exclusively through the shock absorber.

[0032] As illustrated on the figures 2 And 3 The shock absorber 19 is a ring, comprising: a ring 23, centered on the axis of rotation X, having first and second large faces 25, 27 substantially annular, a radially internal slice 29 and a radially external slice 31; a cylindrical wing 33, coaxial with the axis of rotation X, extending axially from the second large face 27.

[0033] The ring 23 extends substantially in a plane perpendicular to the axis of rotation X. It is generally circular in shape, in the sense that the radially internal and external slices 31, 33 are circular.

[0034] The first and second large faces 25, 27 are rotated axially respectively in first and second directions D1, D2 opposite to each other, materialized on the figure 3 .

[0035] The cylindrical wing 35 extends axially from the ring 23 towards the rotor 5, that is to say along the second direction D2.

[0036] It is formed along the radially external edge of the ring, that is to say along the radially external slice 33. It has a small radial thickness in relation to the width of the ring 23, so that most of the second large face 29 remains free and is located radially towards the inside of the cylindrical wing 35.

[0037] The cylindrical wing 35 has a radially internal surface 37, a radially external surface 39 and an annular tip surface 41.

[0038] The radially external surface 39 is axially in line with the radially external slice 33.

[0039] The annular end surface 41 is centered on the axis of rotation X. It extends in a plane perpendicular to the axis of rotation X. It constitutes the end of the cylindrical wing 35, opposite the ring 23.

[0040] As seen on the figures 2 And 3, hub 15 is a plate rigidly fixed to the rotating shaft 7.

[0041] In the example shown, hub 15 is disc-shaped, and therefore generally has a circular shape.

[0042] It is rigidly fixed to the end of the rotating shaft 7 by screws 43, visible on the figure 1 .

[0043] The hub 15 generally extends in a plane perpendicular to the axis of rotation X.

[0044] The hub 15 has a slice 45, and a large front face 47.

[0045] The large front face 47 is rotated axially in the first direction D1.

[0046] The large front face 47 has an edge area 49 which adjoins the edge 45.

[0047] The hub 15 is in contact by its edge area 49 with the second large face 29 of the shock absorber 19.

[0048] The hub 15 is also in contact by its edge 45 with the radially internal surface 37 of the cylindrical wing 35 of the shock absorber 19.

[0049] The edge zone 49 and the slice 45 are supported and adhered to the shock absorber 19.

[0050] The fan support 17 includes first and second half-rings 51, 53 removably fixed to each other, and arranged axially on either side of the shock absorber 19.

[0051] Typically, the first and second half-rings 51, 53 are fixed to each other by screws 55, shown on the figures 1 And 2 .

[0052] The first half-ring 51 includes a first annular part 57 in contact with the first large face 27 of the ring 23 of the shock absorber 19.

[0053] The first half-ring 51 still includes a first cylindrical part 59, integral with the first annular part 57 and in contact with the radially internal edge 31 of the ring 23 of the shock absorber 19.

[0054] The first annular part 57 is centered on the axis of rotation X. It extends substantially in a plane perpendicular to the axis of rotation X.

[0055] The first cylindrical part 59 extends axially along the second direction D2 from the first annular part 57. It extends along a radially internal edge of the first annular part 57.

[0056] The second half-ring 53 includes a second annular part 61, in contact with the annular end surface 41 of the cylindrical part 35 of the shock absorber 19.

[0057] The second half-ring 53 also includes a second cylindrical part 63, integral with the second annular part 61 and in contact with the radially external surface 39 of the cylindrical wing 35 of the shock absorber 19, and with the radially external edge 33 of the ring 23 of the shock absorber 19.

[0058] The second annular part 61 is centered on the axis of rotation X and extends in a plane perpendicular to the axis of rotation X. It forms a re-entrant collar at an axial end of the second cylindrical part 53, opposite the first half-ring 51.

[0059] The second cylindrical part 53 is coaxial with the axis of rotation X.

[0060] Cavity 21 is thus delimited: by the slice 45 and the edge area 49 of the hub; by the first annular part 57 and the first cylindrical part 59 of the first half-ring 51; and by the second annular part 61 and the second cylindrical part 63 of the second half-ring 53.

[0061] This cavity is substantially closed in the sense that there are only narrow gaps between the first cylindrical part 59 and the hub 15, and between the second annular part 61 and the hub 15.

[0062] These gaps are narrow enough to allow the shock absorber 19 to be cast in place. They are wide enough so that, when the electric motor is running, there is no direct contact between the fan support 17 and the hub 15.

[0063] It should be noted that the fact that the shock absorber 19 is housed in a substantially closed cavity prevents the material constituting the shock absorber from creeping out of its housing.

[0064] The shock absorber is, for example, made of an elastomeric rubber.

[0065] Advantageously, the first annular portion 51 bears teeth 65 cooperating with complementary teeth 67 provided on the ring 23 of the shock absorber. The teeth 65 are arranged in a circle on the face of the first annular portion 57 that is in contact with the ring 23.

[0066] The complementary teeth 67 are provided on the first large face 27 of the ring 23. They are each delimited between two hollows 69, the teeth 65 being received in the hollows 69.

[0067] Similarly, the hub 15 carries other teeth 71, cooperating with other complementary teeth 73 of the ring 23.

[0068] The other teeth 71 are carried by the edge area 49 of the large front face 47 of the hub.

[0069] The other complementary teeth 73 are provided between hollows 75 formed in the second large face 29 of the ring 23 of the shock absorber.

[0070] The other teeth 71 are arranged in a circle, centered on the axis of rotation X. They are each engaged in one of the hollows 75.

[0071] Typically, the teeth 65 are circumferentially offset from the other teeth 71, each tooth 65 being circumferentially positioned between two other teeth 71 and vice versa.

[0072] Similarly, the complementary teeth 67 are circumferentially offset from the other complementary teeth 73. More precisely, each hollow 69 constitutes one of the other complementary teeth 73, and each hollow 75 constitutes one of the complementary teeth 67.

[0073] Thus, teeth 65 and other teeth 71 are arranged on the same circle, with circumferential interposition of a veil of shock absorber material between teeth 65 and 71.

[0074] The transmission of torque from the hub 15 to the fan support 17 is therefore particularly good.

[0075] The fan 9 is removably attached to the fan bracket 17, typically by screws such as the screws 77 shown on the figure 1 .

[0076] The engine manufacturing process described above will now be detailed.

[0077] The stator 3, rotor 5 and rotating shaft 7 are assembled in the usual way, so these steps are not described here.

[0078] The process also includes the following steps, aimed at manufacturing the shock absorber 13.

[0079] The hub 15, and the first and second half-rings 51, 53 of the fan support 17 are obtained first.

[0080] The first and second half-rings 51, 53 are then assembled together, trapping the hub 15 between the two half-rings 51, 53.

[0081] The process still involves the following steps: setting up the hub 15 and the fan support 17 on a tool, the hub 15 and the fan support 17 together defining the substantially closed cavity 21, having a conjugate shape to that of the shock absorber 19; casting the shock absorber 19 into the cavity 21.

[0082] The tool is typically an injection mold.

[0083] The hub 15 and the fan support 17 are held in place relative to each other in the tool.

[0084] The material constituting the shock absorber 19 is injected hot into the cavity 21.

[0085] After cooling of the shock absorber 19, the hub 15 and the fan support 17 are fixed to each other, exclusively by the shock absorber 19.

[0086] The shock absorber 19 is then extracted from the tool.

[0087] The process then includes a step of mounting the shock absorber 19 on the rotating shaft 7, and a step of mounting the fan 9 on the fan support 17.

[0088] Alternatively, the fan support 17 is a single piece.

[0089] Alternatively, the shock absorber is not a ring, but has a general disc shape, covering the large front face of the hub.

Claims

1. Electric motor (1) comprising a stator (3), a rotor (5), a rotary shaft (7) driven in rotation about an axis of rotation (X) by the rotor (5), a fan (9), and a damper (13) rotatably connecting the fan (9) to the rotary shaft (7), the damper (13) comprising: - a hub (15), mounted to the rotary shaft (7); - a fan support (17), to which the fan (9) is attached ; - a shock absorber (19) made of an elastically-deformable material, the fan support (17) being attached to the hub (15) only via the shock absorber (19); characterised in that the hub (15) and the fan support (17) together define a substantially closed cavity (21), having a shape complementary to that of the shock absorber (19), in which the shock absorber (19) is cast, the hub (15) and the fan support (17) being attached to each other exclusively by the shock absorber (19) after cooling of the shock absorber (19).

2. Motor according to claim 1, wherein the hub (15) is bonded to the shock absorber (19), and the fan support (17) is bonded to the shock absorber (19).

3. Motor according to any one of the preceding claims, wherein the shock absorber (19) is a ring comprising: - a ring (23) centred on the axis of rotation (X) having substantially annular first and second large faces (27, 29), a radially inner slice (31) and a radially outer slice (33), and - a cylindrical wing (35) coaxial to the axis of rotation (X), extending axially from the second large face (29), having a radially inner surface (37), a radially outer surface (39) and an annular tip surface (41).

4. Motor according to claim 3, wherein the hub (15) is a plate rigidly attached to the rotary shaft (7), having a slice (45) and a large front face (47) having an edge zone (49) adjoining the slice (45), the hub (15) being in contact through the edge zone (49) with the second large face (29) of the shock absorber (19) and through the slice (45) with the radially inner surface (37) of the cylindrical wing (35) of the shock absorber (19).

5. Motor according to claim 3 or 4, wherein the fan support (17) comprises first and second half-rings (51, 53) removably attached to each other, and arranged axially on either side of the shock absorber (19).

6. Motor according to claim 5, wherein the first half-ring (51) comprises a first annular part (57) in contact with the first large face (27) of the shock absorber (19), and a first cylindrical part (59) integral with the first annular part (57) and in contact with the radially inner slice (31) of the ring (23) of the shock absorber (19).

7. Motor according to claim 5 or 6, wherein the second half-ring (53) comprises a second annular part (61) in contact with the annular tip surface (41) of the cylindrical part (35) of the shock absorber (19), and a second cylindrical part (63) integral with the second annular part (61) in contact with the radially outer surface (39) of the cylindrical wing (35) of the shock absorber (19) and with the radially outer slice (33) of the ring (23) of the shock absorber (19).

8. Motor according to any one of the preceding claims in combination with claims 4 and 6, wherein the first annular part (57) carries teeth (65) cooperating with complementary teeth (67) of the ring (23), the hub (15) carrying other teeth (71) cooperating with other complementary teeth (73) of the ring (23).

9. Method for manufacturing a motor according to claim 1, the method comprising the following steps of: - placing the hub (15) and the fan support (17) on a tool, the hub (15) and the fan support (17) defining together the substantially closed cavity (21) having a shape complementary to that of the shock absorber (19); - casting the shock absorber (19) into the cavity (21), the hub (15) and the fan support (17) being attached together exclusively by the shock absorber (19) after cooling the shock absorber (19).

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