Electrically conductive element for a rotating electrical machine.

Abstract

Electrically conductive element for a rotating electrical machine.Electrical conductive element (20) for an electric machine of a vehicle, the electrical conductive element (20) being intended to be arranged between two members (16, 17) rotating relative to each other, at least one of the members (16, 17) of the machine (10) rotating about an axis of rotation (X), the electrical conductive element (20) being characterized in that it comprises a central electrical contact area (22) of spherical shape for establishing electrical contact between said members (16, 17), and a peripheral edge (24) intended to maintain the electrical conductive element (20) in position, said central contact area (22) being connected to the peripheral edge (24) by means of an elastic arm (26) configured to allow elastic deformation of the electrical conductive element (20) and displacement parallel to the axis of rotation of the central contact area (22) relative to the peripheral edge (24). Figure for the summary: Fig. 3.

Description

Title of the invention: Electrically conductive element for a rotating electrical machine.

[0001] The invention relates to an electrically conductive element for a rotating electrical machine, and in particular to a rotating electrical machine for a motor vehicle. The invention also relates to a rotating electrical machine equipped with such an electrically conductive element. Said electrical machine is a traction or propulsion electric motor intended to drive the drive wheels of a vehicle. The invention also relates to a motor vehicle comprising such a rotating electrical machine. Although such an electrically conductive element is intended for a rotating electrical machine for a motor vehicle, the invention may nevertheless be applicable in other fields.

[0002] Generally, an electrical machine comprises a stator, attached to a housing, and a rotor, attached to a shaft. During operation, the rotor becomes electrically charged and discharges, generating electric arcs between the rotor's teeth and the balls of the ball bearings that allow the shaft to rotate within the machine's housing. These electric arcs tend to damage the balls, or even destroy them. It is therefore necessary to connect the rotor to ground to prevent the generation of these electric arcs.

[0003] Various solutions have already been developed in this regard. One of them provides for a rotating electrical machine comprising a housing, a rotating assembly mounted inside the housing around an axis of rotation, a sensor for measuring one or more kinematic quantities of said rotating assembly, the sensor having a passage orifice and an electrically conductive element connected to the housing, the rotating assembly and said electrically conductive element being in sliding contact with each other through the sensor's passage orifice. The electrically conductive element serves to electrically connect the rotating assembly to ground in order to prevent the formation of electrical arcs.

[0004] The object of the invention is to provide an improved embodiment for the electrically conductive element. This embodiment is improved in that it reduces friction while exhibiting better electrical conductivity and a more reliable spring function. This embodiment also facilitates the mounting of the electrically conductive element within the rotating electrical machine.

[0005] To this end, the invention relates to an electrically conductive element for an electric machine of a motor vehicle, the electrically conductive element being intended to to be arranged between two parts rotating relative to each other, at least one of the parts of the machine rotating around an axis of rotation, the electrically conductive element being characterized in that it comprises a central electrical contact area of ​​spherical shape for establishing electrical contact between said parts, and a peripheral edge intended to maintain the electrically conductive element in position inside said electrical machine, said central contact area being connected to the peripheral edge by means of an elastic arm configured to allow elastic deformation of the electrically conductive element and in particular a displacement of the central contact area relative to the peripheral edge, the displacement being parallel to the axis of rotation.

[0006] According to one embodiment, the electrically conductive element is made of a metallic material, in particular copper.

[0007] According to one embodiment, the electrically conductive element is at least partially covered with a conductive coating configured to increase electrical conductivity, particularly in the central spherical electrical contact area.

[0008] According to one embodiment, the electrically conductive element is at least partially covered with a protective coating configured to protect the electrically conductive element against corrosion and / or oxidation.

[0009] According to one embodiment, the electrically conductive element is at least partially covered with a protective coating configured to protect the electrically conductive element against abrasion, particularly in the central spherical electrical contact area.

[0010] According to one embodiment, the electrically conductive element has a liquid evacuation means configured to expel the oil present in the rotating electrical machine.

[0011] According to one embodiment, the electrically conductive element includes a locking means configured to prevent rotation of the electrically conductive element when it is mounted in the rotating electrical machine.

[0012] According to one embodiment, the electrically conductive element further comprises a bottom wall configured to be mounted on the peripheral edge.

[0013] The invention also relates to a rotating electrical machine comprising an electrically conductive element as described above.

[0014] According to one embodiment, the electrically conductive element in the rotating electrical machine is arranged between an electrical grounding contactor of the rotating electrical machine and a rotor shaft of the rotating electrical machine, such that the central electrical contact area establishes electrical contact between said contactor and the rotor shaft.

[0015] The invention also relates to a motor vehicle equipped with a rotating electrical machine as described above.

[0016] These objects, features and advantages of the present invention will be described in detail in the following description of a particular embodiment, given by way of non-limiting example, with reference to the accompanying figures, among which:

[0017] Fig. 1 schematically illustrates a cross-sectional view of a sensor and a rotating assembly of a rotating electrical machine equipped with an electrically conductive element according to the invention.

[0018] [Fig.2] is a detail view of [Fig.1].

[0019] Fig. 3 is an exploded view of an electrically conductive element according to the invention.

[0020] Figure 1 shows a cross-sectional view of a portion of an electrical machine. 10 for a motor vehicle. This electric machine 10 is, for example, an electric traction or propulsion motor intended to drive the vehicle's drive wheels. The electric machine 10 comprises a housing 12 and a rotating assembly 14 with a rotor shaft 16, as well as an inductive sensor configured to evaluate the angular position and / or rotational speed of the rotor shaft 16 of said rotating electric machine 10. The rotating electric machine 10 also includes an electrical grounding contactor 17. As illustrated in [Fig. 1], the electrical grounding contactor 17 is aligned with the axis of rotation of the rotor shaft 16. In [Fig. 1], and in [Fig. 3], the electrical grounding contactor 17 has a protruding tip 18 aligned with an axis of rotation X of the rotating assembly 14 of the electric machine 10.

[0021] An electrically conductive element 20 is arranged between two members 16, 17 rotating relative to each other. At least one of the two members 16, 17 of the machine 10 rotates about the axis of rotation X. The location of the electrically conductive element 20 is particularly visible in [Fig. 2], which is a detailed view of [Fig. 1]. In [Fig. 1] and [Fig. 2], the electrically conductive element 20 is positioned between the electrical grounding contactor 17 and the rotor shaft 16.

[0022] The electrically conductive element 20 comprises a central electrical contact area 22 of spherical shape. The central electrical contact area 22 of spherical shape is intended to be in contact on one side with the center of the rotor shaft 16 and on the other side with the end of the protruding tip 18 of the electrical grounding contactor 17.

[0023] According to a particular embodiment of the rotor shaft 16, the latter comprises at one end a contact face having a spherical cavity in its center. The radius of the sphere of this cavity at the center of the contact face of the rotor shaft 16 is greater than the radius of the sphere of the spherically shaped central electrical contact zone 22 of the electrically conductive element 20. In this embodiment, a sphere / sphere contact is thus established for the passage of electric current between the rotor shaft 16 and the electrically conductive element 20.

[0024] A sphere-to-sphere contact is more reliable than a plane-to-plane or sphere-to-plane contact for ensuring the passage of electric current. Furthermore, an electrically conductive element 20 providing a sphere-to-sphere contact can be more compact than a plane-to-plane contact within the enclosure of the rotating electrical machine 10.

[0025] The electrically conductive element 20 also includes a peripheral edge 24 which at least partially surrounds the central spherical electrical contact area 22. The peripheral edge 24 is intended to hold the electrically conductive element 20 in position inside the electrical machine 10.

[0026] Said central electrical contact area 22 is connected to the peripheral edge 24 by means of an elastic arm 26, as illustrated in [Fig. 3]. By "elastic," it is understood that the electrically conductive element 20 can be slightly deformed so as to displace the central electrical contact area 22 relative to the peripheral edge 24, while being configured to return to its initial shape in the absence of external stress. The displacement of the central electrical contact area 22 relative to the peripheral edge 24 is parallel to the axis of rotation of the two rotating members 16, 17 between which the electrically conductive element 20 is intended to be arranged. In this way, the electrically conductive element 20 simultaneously provides electrical grounding and a spring function.

[0027] According to an embodiment not illustrated, the electrically conductive element 20 can comprise several elastic arms 26. For example, one can imagine an electrically conductive element 20 for which the peripheral edge 24 is discontinuous and for which each portion of the peripheral edge is linked to the central electrical contact area 22 by an elastic arm 26.

[0028] According to a specific embodiment, the electrically conductive element 20 is made of a metallic material, in particular copper. Copper is a very good electrical conductor, as well as an excellent thermal conductor. Thus, in the event of heating of the electrically conductive element 20, the heat is carried throughout the entire copper element 20, from the central spherical electrical contact area 22 to the peripheral edge 24. The peripheral edge 24 can then be used to efficiently cool the electrically conductive element 20 in the event of heating of the electrically conductive element 20.

[0029] In the case where the electrically conductive element 20 is made of a metallic material, the electrically conductive element 20 has a sufficiently thin thickness to allow elastic deformation of said element 20, and more particularly a displacement of the central electrical contact area 22 relative to the edge peripheral 24 via the elastic arm 26 which connects the central electrical contact area 22 to the peripheral edge 24.

[0030] According to an example, the electrically conductive element 20 has a thickness of a few mm, for example a thickness between 1mm and 6mm, and more particularly equal to 3mm.

[0031] According to a specific embodiment, the electrically conductive element 20 may be at least partially covered with a conductive coating configured to increase electrical conductivity, particularly in the central spherical electrical contact area 22. Such a coating, whether localized or not, may allow for improved electrical current flow and thus a more reliable grounding. The electrical coating may be in the form of a layer of silver or any other material exhibiting high electrical conductivity.

[0032] According to a specific embodiment, the electrically conductive element 20 may be at least partially covered with a protective coating configured to protect the electrically conductive element 20 against corrosion. Such a coating may extend the service life of the electrically conductive element 20.

[0033] In addition or alternatively, the electrically conductive element 20 may be at least partially covered with a protective coating configured to protect the electrically conductive element 20 against oxidation, particularly in the case where the electrically conductive element 20 is made of a metallic material such as copper, which tends to oxidize over time. Such a coating can extend the service life of the electrically conductive element 20.

[0034] According to a specific embodiment, the electrically conductive element 20 may be at least partially covered with a protective coating configured to protect the electrically conductive element 20 against abrasion, particularly in the central spherical electrical contact area 22. Such a coating may extend the service life of the electrically conductive element 20.

[0035] According to a specific embodiment, the electrically conductive element includes a locking means configured to prevent rotation of the conductive element when mounted in the rotating electrical machine. Such a locking means may be in the form of a layer of adhesive on the peripheral edge 24 of the electrically conductive element 20; the adhesive layer then holds the electrically conductive element 20 in place within the rotating electrical machine 10.

[0036] Alternatively, the blocking means may be in the form of a flat in the peripheral edge 24 of the electrically conductive element 20, in particular in the case where said edge 24 has a substantially circular shape.

[0037] Alternatively, the blocking means may affect the entire peripheral edge 24 of the electrically conductive element 20, said edge 24 may for example have a polygonal shape, in particular square, rectangular, pentagonal or hexagonal to prevent rotation of the electrically conductive element 20 when it is mounted in the rotating electrical machine 10.

[0038] According to a specific embodiment, the electrically conductive element 20 may have a liquid drainage means configured to expel oil present in the rotating electrical machine 10. The drainage means may be in the form of raised features, such as grooves, furrows, or ribs, on the surface of the electrically conductive element 20. The raised feature(s) may be spiral-shaped. Preferably, the winding direction of such a spiral-shaped feature is consistent with the preferred direction of rotation of the electrical machine. One end of such a feature may be located near the center of the central electrical contact area 22, while a second end of the same feature may be located near the peripheral edge 24 in order to expel oil present on the central electrical contact area 22.

[0039] According to a specific embodiment, the electrically conductive element 20 may comprise several parts, in particular two parts, and notably a bottom wall 28 configured to be mounted on the peripheral edge 24. In this specific embodiment, the bottom wall 28 and the peripheral edge 24 have a contact surface sufficient to avoid impairing electrical conductivity. The bottom wall 28 may, for example, be clipped, screwed, or glued to the peripheral edge 24. Such a bottom wall 28 allows for various shapes of the electrically conductive element 20 that are not feasible in the case of an electrically conductive element 20 comprising a single, monolithic piece. Furthermore, such a bottom wall 28 can facilitate the mounting of the electrically conductive element 20 within the rotating electrical machine 10.

[0040] In the embodiment illustrated in [Fig. 3], the bottom wall comprises in its center a hollow cylindrical bell 30 with a spherical end 32. This bell 30 is aligned with the axis of rotation X. The end 18 of the electrical grounding contactor 17 is intended to be housed inside this hollow bell 30, so that the end 18 of the electrical grounding contactor 17 touches the bottom of the hollow bell 30. Thanks to the elasticity of the elastic arm 26, the central spherical electrical contact area 22 is brought into contact with the outer surface of the spherical end 32 of the bell 30, thereby establishing an electrical contact to allow the passage of electric current between the rotor shaft 16 and the electrical grounding contactor 17.

[0041] It is thus possible to design another embodiment for electrically conductive element 20 which makes it possible to reduce friction while presenting better electrical conductivity as well as a more reliable spring function; and to facilitate the mounting of the electrically conductive element 20 within the rotating electrical machine 10.

Claims

Demands

1. An electrically conductive element (20) for an electric machine of a motor vehicle, the electrically conductive element (20) being intended to be arranged between two components (16, 17) rotating relative to each other, at least one of the components (16, 17) of the machine (10) rotating about an axis of rotation (X), the electrically conductive element (20) being characterized in that it comprises a central electrical contact area (22) of spherical shape for establishing electrical contact between said components (16, 17), and a peripheral edge (24) for maintaining the electrically conductive element (20) in position within said electric machine (10), said central contact area (22) being connected to the peripheral edge (24) by means of an elastic arm (26) configured to allow elastic deformation of the electrically conductive element (20) and in particular displacement of the central contact area (22) relative to the peripheral edge (24),the displacement being parallel to the axis of rotation (X) and characterized in that it is at least partially covered with a conductive coating configured to increase electrical conductivity, particularly in the central electrical contact zone (22) which is spherical in shape.

2. Electrically conductive element (20) according to the preceding claim, characterized in that it is made of a metallic material, in particular copper.

3. Electrically conductive element (20) according to any one of the preceding claims, characterized in that it is at least partially covered with a protective coating configured to protect the electrically conductive element (20) against corrosion and / or oxidation and / or characterized in that it is at least partially covered with a protective coating configured to protect the electrically conductive element (20) against abrasion, particularly in the central electrical contact area (22) which is spherical in shape.

4. Electrically conductive element according to any one of the preceding claims, characterized in that it has a liquid evacuation means configured to expel the oil present in the rotating electrical machine (10).

5. An electrically conductive element according to any one of the preceding claims, characterized in that it comprises a locking means configured to prevent rotation of the electrically conductive element (20) when mounted in the rotating electrical machine (10).

6. Electrically conductive element according to any one of the preceding claims, characterized in that it further comprises a bottom wall (28) configured to be mounted on the peripheral edge (24).

7. Rotating electrical machine (10), characterized in that it comprises an electrically conductive element (20) according to any one of the preceding claims.

8. Rotating electric machine (10) according to the preceding claim, characterized in that the electrically conductive element (20) is arranged between a contactor (17) for electrically grounding the rotating electric machine (10) and a rotor shaft of the rotating electric machine (10), such that the central electrical contact area (22) establishes electrical contact between said contactor (17) and the rotor shaft.

9. Motor vehicle, characterized in that it is equipped with a rotating electrical machine (10) according to the preceding claim.

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