ROTATABLE ELECTRICAL MACHINE

Abstract

A rotatable electrical machine (1), particularly for a motor vehicle starter. The machine has an axis of rotation (X) and comprises a stator (2a) including: a generator field coil (4); including at least one wire (4a) comprising aluminum; and at least one pole shoe (3), including a winding core (31) whereon at least part of the stator winding is formed. The core has a center and a perimeter having at least one curved portion when observing the perimeter along an observational axis perpendicular to the rotational axis and through the center of the core.

Claims

1. Rotary electrical machine (1), in particular for a starter of a motor vehicle, this machine, having an axis of rotation (X) and comprising a stator (2a) comprising: an inductor winding (4), which in particular is concentric, comprising at least one wire (4a) comprising aluminium; at least one pole shoe (3) comprising a winding core (31) on which at least part of the stator winding is formed, the core having a centre and a periphery with at least one portion which is curved (313), when the periphery is observed according to an observation axis perpendicular to the axis of rotation and passing via the centre of the core.

2. Rotary electrical machine according to claim 1, wherein the machine is designed to function with a supply voltage of 12 V and in that: the winding is arranged in 2 parallel tracks, and each winding core is surrounded by 4 turns of the winding; or the winding is arranged in 4 parallel tracks, and each winding core is surrounded by 8 turns of the winding.

3. Rotary electrical machine according to claim 1, wherein the machine is designed to function with a supply voltage of 24 V and in that: the winding is arranged in 2 parallel tracks, and each winding core is surrounded by 4 turns of the winding; or the winding is arranged in 4 parallel tracks, and each winding core is surrounded by 16 turns of the winding.

4. Rotary electrical machine according to claim 1, wherein the machine is designed to function with a supply voltage of 48 V and in that: the winding is arranged in 2 parallel tracks, and each winding core is surrounded by 16 turns of the winding; or the winding is arranged in 4 parallel tracks, and each winding core is surrounded by 32 turns of the winding.

5. Rotary electrical machine according to claim 1, wherein the machine comprises an armature, the length (Lr) of the armature measured according to the axis of rotation being greater than, or equal to, the length (Ls) of the pole shoe measured according to the axis of rotation.

6. Rotary electrical machine according to claim 5, wherein the length of the pole shoe is greater than, or equal to, 90% of the length of the armature, in particular 95%, and preferably 97%.

7. Rotary electrical machine according to claim 5, wherein the length of the armature is between 30 and 40 mm, and in particular is substantially equal to 35 mm.

8. Rotary electrical machine according to claim 5, wherein the length of the pole shoe is between 30 and 40 mm, and in particular is substantially equal to 34 mm.

9. Rotary electrical machine according to claim 1, wherein, when observed according to the observation axis, the periphery of the polar core has an elongate form according to the axis of rotation.

10. Rotary electrical machine according to claim 9, wherein the periphery of the polar core has a form comprising two segments of straight line (312), which are preferably parallel, and are connected to one another by two portions of curve (313).

11. Rotary electrical machine according to claim 10, wherein at least one of the portions of curve corresponds to an arc of a circle.

12. Rotary electrical machine according to claim 9, wherein the periphery (311) of the polar core has an elliptical form when observed according to the observation axis, perpendicular to the axis of rotation.

13. Rotary electrical machine according to claim 1, wherein the winding wire has on at least part of its length a transverse cross-section with at least one flattened part.

14. Rotary electrical machine according to claim 1, wherein at least one alloy element which constitutes the wire (4a) is copper.

15. Rotary electrical machine according to claim 1, forming a starter of a motor vehicle.

16. Rotary electrical machine according to claim 2, wherein the machine comprises an armature, the length (Lr) of the armature measured according to the axis of rotation being greater than, or equal to, the length (Ls) of the pole shoe measured according to the axis of rotation.

17. Rotary electrical machine according to claim 3, wherein the machine comprises an armature, the length (Lr) of the armature measured according to the axis of rotation being greater than, or equal to, the length (Ls) of the pole shoe measured according to the axis of rotation.

18. Rotary electrical machine according to claim 4, wherein the machine comprises an armature, the length (Lr) of the armature measured according to the axis of rotation being greater than, or equal to, the length (Ls) of the pole shoe measured according to the axis of rotation.

19. Rotary electrical machine according to claim 6, wherein the length of the armature is between 30 and 40 mm, and in particular is substantially equal to 35 mm.

Description

[0050] The invention will be able to be better understood by reading the following detailed description of non-limiting embodiments of the invention and by examining the appended drawing in which:

[0051] FIG. 1 represents schematically and partially a cross-section of the electrical machine according to the invention;

[0052] FIG. 2 represents a pole shoe of the machine in FIG. 1, which shoe is observed according to an observation axis perpendicular to the axis of rotation;

[0053] FIG. 3 represents a pole shoe according to another embodiment of the invention, observed according to the observation axis perpendicular to the axis of rotation, and

[0054] FIG. 4 illustrates schematically and partially a cross-section representing a portion of an electrical machine according to another embodiment of the invention.

[0055] FIG. 1 represents schematically a starter 1 for an internal combustion engine of a motor vehicle.

[0056] This direct current starter 1 comprises a stator 2a, or inductor, comprising a head 2 on which pole shoes 3 are secured, and a winding 4 formed by conductive wires 4a wound on these pole shoes 3. This starter 1 also comprises a rotor 5, also known as an armature, which can rotate around an axis of rotation X, inside the stator 2a. The rotor 5 comprises notches 51 which comprise wound armature wires which are not represented in FIG. 1. As can be seen in FIG. 2, the length Lr of the rotor 5 measured according to the axis of rotation X is greater than the length Ls of the pole shoe measured according to the axis X, such as to exploit the surface area of the armature to the maximum from an electromagnetic point of view, without increasing the electrical resistance of the device. In the example, the length of the pole shoe measured according to the axis X is more than 90% of the length of the armature. In the example, the length Lr of the rotor 5 is 35 mm and the length Ls is 34 mm.

[0057] As can be seen in FIG. 2, the pole shoe 3 comprises a core 31 and a widening 32.

[0058] The core 31 comprises a periphery 311 with a form which is elongate according to the axis of rotation X.

[0059] As illustrated in FIG. 2, the periphery 311 of the core 31 has a form comprising two parallel segments 312 which are connected to one another by two portions of curve 313, and at least one of the portions of curve corresponds substantially to an arc of a circle.

[0060] As illustrated in FIG. 3, as a variant, the periphery 311 of the core 31 has a globally elliptical form when observed according to the observation axis perpendicular to the axis of rotation X, with two parallel straight segments 315. In a variant not represented, the periphery 311 of the polar core 31 has a circular form when observed according to the observation axis perpendicular to the axis of rotation X.

[0061] The widening 32 is connected to the core 31 and is arranged radially on the interior relative to the core 31. The widening 32 has a substantially rectangular form when observed according to the observation axis perpendicular to the axis of rotation X, and has a span larger than that of the core 31 when observed according to the observation axis perpendicular to the axis of rotation X.

[0062] The widening 32 also has a circumferential dimension which is larger than that of the core 31.

[0063] As illustrated in FIG. 1, the machine comprises a number of pairs of pole shoes 3 equal to 2.

[0064] The core 31 is secured on the head 2 of the stator by being screwed. This permits simple assembly and dismantling of the core 31.

[0065] The pole shoe 3 comprises a recess 33 which passes through in the radial direction, this recess being used for the screwing of the pole shoe onto a head. This recess permits the passage of a securing screw for screwing onto the head 2 of the stator.

[0066] As a variant, the core 31 is secured on the head 2 of the stator by crimping.

[0067] The thickness of the core 31 measured in the radial direction is 6.5 mm.

[0068] As illustrated in FIG. 4, as a variant, the machine 1 comprises an inductor winding 4, the wire of which has on at least part of its length a transverse cross-section with at least one flattened part 41.

[0069] The winding is arranged in 2 parallel tracks and each winding core 34 is surrounded by 4 turns of the winding.