Device for supplying electrical power to a wound rotor

Abstract

Disclosed is a device for supplying electrical power to a wound rotor of an electric motor (1F) of a motor vehicle, comprising: - a rotor shaft (6F) comprising a first part (61F) and a second part (62F), the second part comprising an engagement portion (63F) via which the second part is attached to the first part, - an electrical connection element (10F) comprising a slip ring (16F, 17F), an electrical connector (22F) intended to be connected to a first end of a coil of the wound rotor, and a conductor (24F) electrically connecting the slip ring to the connector, the connection element further comprising a radial arm (27F), the conductor extending into the radial arm, the engagement portion (63F) comprising a notch (66F) through which the radial arm extends.

Description

Description Title of the invention: Power supply device for a wound rotor Technical field of the invention

[0001] The invention relates to a power supply device for a wound rotor of an electric motor in a motor vehicle. The invention also relates to an electric motor for a motor vehicle comprising such a power supply device. The invention further relates to a method for manufacturing such a power supply device. Prior art

[0002] So-called "electric" or "hybrid" motor vehicles include an electric motor capable of driving the vehicle's drive wheels. Among the various types of electric motors available, wound-rotor motors are well-known. Such electric motors consist of a rotor equipped with at least one coil for which an electric current flows. To supply the at least one coil with electric current, a rotor shaft typically includes two slip rings that cooperate with brushes. The two slip rings are connected by wires to the two ends of the at least one coil.

[0003] The rotor shaft is guided in rotation by bearings, usually roller bearings. The bearings are arranged at the interface between the electric motor housing and the rotor shaft. The electrical wires connecting the slip rings to the coils pass through the central opening of an inner ring of the roller bearing.

[0004] Furthermore, since the rotor shaft is likely to rotate at very high speeds, for example, over 10,000 revolutions per minute, the bearings are subjected to significant stress and must have an optimal geometry, free from any deformation. In addition, oil is present inside the housing to cool the electric motor and / or lubricate the bearings. Therefore, sealing devices must be provided at the interface between the housing and the rotor shaft to prevent any oil leakage.

[0005] Thus, the architecture of a wound rotor shaft is complex, as it must accommodate the power supply to at least one winding, while also integrating with bearings and sealing systems. Furthermore, the assembly process for a wound rotor must be as simple as possible. Finally, an electric motor incorporating such a wound rotor must be compact, reliable, and quiet. Presentation of the invention

[0006] The object of the invention is to provide an electric motor for a motor vehicle comprising a wound rotor remedying the above disadvantages and improving upon known electric motors of the prior art.

[0007] More specifically, a first object of the invention is a power supply device for a wound rotor of an electric motor which is both simple and allows for reliable operation of the electric motor even when the wound rotor rotates at high speed. Summary of the invention

[0008] The invention relates to a power supply device for a wound rotor of an electric motor of a motor vehicle, comprising: - a rotor shaft comprising a first part and a second part, the second part comprising a socket portion through which the second part is fixed to the first part, - an electrical connection element comprising at least one slip ring, at least one electrical connector intended to be connected to a first end of a coil of the wound rotor, and at least one conductor electrically connecting the slip ring to the connector, the connection element further comprising at least one radial arm, at least one conductor extending into at least one radial arm, the interlocking portion comprising at least one notch through which at least one radial arm extends.

[0009] The power supply device may further include a bearing support for guiding the rotation of the rotor around an axis of rotation, and the second part of the rotor shaft may include a support portion having a first receiving surface in the form of a continuous cylinder of revolution, the bearing support being fitted onto the first receiving surface.

[0010] At least one slip ring and at least one electrical connector can be positioned on either side of the bearing housing.

[0011] The electrical connection element may include a body made of insulating material, in particular plastic, with at least one slip ring arranged around an axial part of the body, at least one axial conductor embedded within the body, and at least one connector free from the body.

[0012] The power supply device may further include a sealing gasket intended to be fixed to a housing of the electric motor, and the second part of the rotor shaft may include a sealing portion provided with a second receiving surface in the form of a continuous cylinder of revolution, the sealing gasket including a lip in contact with the second receiving surface.

[0013] The first part of the rotor shaft may include a first axial opening, and the socket portion may be fitted inside the first axial opening.

[0014] The second part of the rotor shaft may include a second axial opening, and the electrical connection element may extend through the second axial opening.

[0015] The first part of the rotor shaft may include a first fitting surface cooperating with a second fitting surface of the socket portion to fix the second part to the first part, the first fitting surface comprising a continuous cylinder of revolution shape, the electrical connection element being positioned at the rear of the first part of the rotor shaft.

[0016] The second part of the rotor shaft may include a first thrust surface bearing axially against the first part of the rotor shaft.

[0017] The electrical connection element may include a first slip ring, a second slip ring, a first electrical connector for connection to a first end of a wound rotor coil, a second electrical connector for connection to a second end of the wound rotor coil, a first conductor electrically connecting the first slip ring to the first connector, a second conductor electrically connecting the second slip ring to the second connector, a first radial arm within which the first conductor extends, and a second radial arm within which the second conductor extends, the second radial arm being diametrically opposite to the first radial arm.the interlocking portion comprising a first notch through which the first radial arm extends and a second notch diametrically opposite the first notch and through which the second radial arm extends.

[0018] The invention also relates to an electric motor for a motor vehicle comprising a wound rotor equipped with at least one coil and a power supply device as defined above, the power supply device being configured to electrically supply F at least one coil of the wound rotor.

[0019] The invention also relates to a method for manufacturing an electrical power supply device as defined above, the method comprising: - supplying the first part of the rotor shaft, the second part of the rotor shaft, and the electrical connection element, then - the assembly of the electrical connection element to the second part of the rotor shaft such that at least one radial arm of the electrical connection element extends through at least one notch, then - the assembly of the second part of the rotor shaft to the first part of the rotor shaft. Presentation of the figures

[0020] These objects, features and advantages of the present invention will be described in detail in the following description of various specific embodiments presented by way of non-limiting example, in relation to the accompanying figures, among which:

[0021] Fig. 1 is a schematic radial cross-sectional view of part of an electric motor according to a first embodiment.

[0022] Figure [Fig. 2] is a perspective view of part of a rotor of the electric motor in Figure [Fig. 1].

[0023] Fig. 3 is a perspective view of an electrical connection element of the electric motor in Fig. 1.

[0024] Fig. 4 is a schematic radial cross-sectional view of part of an electric motor according to a second embodiment. Detailed description

[0025] Figure 1 illustrates, in cross-section, a first embodiment of an electric motor IA. The electric motor IA is intended to drive the drive wheels of a motor vehicle. The electric motor IA can, for example, be powered by an electric battery, in particular a lithium-ion battery. The electric motor IA comprises a housing 2A, a stator 3A fixed to the housing 2A, and a rotor 4A free to rotate relative to the housing 2A and the stator 3A about an axis of rotation X.

[0026] An axial direction is defined as a direction parallel to the axis of rotation X. A radial direction is defined as a direction perpendicular to the axis of rotation X and passing through the axis of rotation X. A radial direction is illustrated by arrow Y in [Fig. 1]. A radial cut is a cut made parallel to the axis of rotation X. An axial cut is a cut made perpendicular to the axis of rotation X.

[0027] The rotor 4A is a wound rotor, meaning it includes at least one coil 5A, or winding of an electric wire. The coil 5A is designed to carry an electric current. The flow of an electric current in the coil 5A produces a magnetic field capable of interacting with the stator 3A, leading to rotation of the rotor 4A around its axis of rotation X. The rotor 4A comprises a rotor shaft 6A and a ferromagnetic core 7A, both clearly visible in [Fig. 2]. The core The ferromagnetic core 7A comprises a set of radial protrusions 8A, notably with a "T"-shaped cross-section, around which the coils 5A are formed. According to the embodiment illustrated in [Fig. 2], the ferromagnetic core 7A comprises four radial protrusions 8A. Alternatively, this number could be different.

[0028] According to the embodiment presented, the electric motor IA is of the radial flux type, meaning that the magnetic flux between the stator 3A and the rotor 4A is oriented radially. Alternatively, the invention could be adapted to an axial flux type motor, that is, an electric motor in which the magnetic flux is oriented parallel to the axis of rotation X.

[0029] The rotor shaft 6A comprises two opposing ends. One end includes a rotational drive means, specifically splines 9A. This rotational drive means is intended to be mechanically coupled to a transmission system to drive the vehicle's drive wheels. A second end of the rotor shaft 6A, particularly visible in Fig. 1, accommodates an electrical connection element 10A configured to supply electrical current to the coils 5A. The "front" side of the first end is defined as F, and the "rear" side as F. The rotation axis X is oriented from front to rear.

[0030] The second end of the shaft 6A comprises a first portion 1 IA, a second portion 12A, and a third portion 13A. The three portions 1 IA, 12A, and 13A are generally cylindrical in shape. A diameter of the first portion 11A is strictly greater than a diameter of the second portion 12A. A diameter of the second portion 12A is strictly greater than a diameter of the third portion 13A. Furthermore, the second end of the rotor shaft 6A comprises two notches 14A and 15A, notably diametrically opposed, parallel to the axis of rotation X, and extending along the first portion 1 IA and the second portion 12A.

[0031] The 10A electrical connection element is shown in isolation on [Fig. 3]. The 10A electrical connection element comprises a first slip ring 16A and a second slip ring 17A. The two slip rings 16A and 17A cooperate with two brushes 18A and 19A (visible in Fig. 1) respectively to collect an electric current. The two slip rings may be, for example, made of copper. The two slip rings 16A and 17A are arranged on a body 20A of the 10A electrical connection element. The body 20A is made of an electrically insulating material, in particular plastic. The 10A electrical connection element also comprises a first electrical connector 21A and a second electrical connector 22A. The two electrical connectors 21A and 22A are electrically connected to at least one 5A coil at two ends of F. Electrical connectors 21A and 22A can be crimped around two ends of an electrical wire from the 5A coil. In Figure 3A, electrical connectors 21A and 22A are shown in a crimping-ready state. Both electrical connectors 21A and 22A extend radially. The electrical connection element 10A also includes a first electrical conductor 23A and a second electrical conductor 24A. The first electrical conductor 23A electrically connects the first slip ring 16A to the first electrical connector 21A. The second electrical conductor 24A electrically connects the second slip ring 17A to the second electrical connector 22A.

[0032] The body 20A comprises a tubular section around which the two slip rings 16A and 17A are arranged. Static sealing means, in particular O-rings 25A, are also arranged around this tubular section. The tubular section is then extended by two radial arms 26A and 27A, diametrically opposed, within which the first conductor 23A and the second conductor 24A extend respectively. The two radial arms are connected by an annular ring 28A.

[0033] The electrical connection element 10A is assembled to the rotor shaft 4A so that the two radial arms 26 A, 27 A are positioned respectively in the two notches 14A, 15A. The tubular part of the body 20A supporting the two slip rings 16A and 17A and the O-rings 25A thus extends to the height of the first portion 1 IA of the rotor shaft 6A.

[0034] The rotor shaft 6A is supported and guided in rotation by a bearing housing 29A. The bearing housing 29A is arranged at the interface between the rotor shaft 6A and the housing 2A. The bearing housing 29A includes an inner ring 30A mounted on the second portion 12A of the rotor shaft 6A. Since the second portion 12A is interrupted by notches 14A and 15A, the inner ring 30A does not have continuous support around its entire circumference. The radial arms 26A and 27A do not support the inner ring 30A, or only minimally. The radial arms 26A and 27A may not be in contact with the inner ring 30A. The absence of support for the inner ring 30A at the notches 14A and 15A can lead to a lack of circularity of the inner ring 30A, and therefore to undesirable noises when the rotor shaft rotates at high speed.

[0035] Furthermore, the electric motor 1 A also includes a dynamic seal 31 A arranged at an interface between the housing 2A and the inner ring 30A. The inner ring thus comprises, on the one hand, a raceway cooperating with the bearings of the roller bearing housing 29 A, and on the other hand, an external bearing surface in contact with the seal 31 A. The inner ring 30A of the roller bearing housing 29 A is wider than the outer ring of this bearing along the axis of rotation X.

[0036] Furthermore, the 25A O-rings are in contact with a bore of the inner ring 30A. Finally, secondary sealing means, in particular secondary O-rings 32A, are provided at the interface between the second end of the rotor shaft 4A and a bore of the electrical connection element 10A.

[0037] According to this first embodiment, a relatively simple and compact power supply device for the coils of a wound rotor is available. However, the lack of uniform support for the inner ring 30A of the bearing housing 29A can lead to undesirable operating noise and / or degradation of the sealing provided by the seal 31A. Furthermore, the bearing housing 29A has a wider inner ring 30A and is therefore non-standard.

[0038] Figure 4 schematically illustrates a second embodiment of an electric motor 1F. To describe this second embodiment, the same reference symbols are used as for the first embodiment described above, but replacing the suffix "A" with the suffix "F". To simplify the description, we will primarily describe the differences between the first and second embodiments, without repeating the common features. Note that Figure 4 shows only one half of a portion of the electric motor 1F positioned on one side of the rotation axis X. The other half of the electric motor 1F can be deduced by symmetry.

[0039] As in the first embodiment, the electric motor 1F also includes a housing 2F, a stator, a wound rotor equipped with at least one coil, and a rotor shaft 6F. Furthermore, the electric motor 1F also includes a bearing 29F and a seal 31F, both arranged at the interface between the rotor shaft 6F and the housing 2F. The bearing 29F is intended to guide the rotation of the rotor about the axis of rotation X. The seal 31F is fixed to the housing 2F and forms a sealing means at the interface between the housing 2F and the rotor shaft 6F.

[0040] According to this second embodiment, the rotor shaft 6F is formed by assembling two distinct parts. The rotor shaft 6F thus comprises a first part 61F and a second part 62F fixed to each other. In particular, the second part 62F includes a socket portion 63F rigidly fixed to the first part 61F. The assembly formed by the first part 61F and the second part 62F is rigid.

[0041] More specifically, the first portion 61F includes a first axial opening 64F within which the interlocking portion 63F is interlocked. The first portion 61F of the rotor shaft includes a first interlocking surface 65F. The first interlocking surface 65F forms a periphery of the first axial opening 64F. The interlocking portion also includes a second engagement surface 73F in direct contact with the first engagement surface 65F. "Interference engagement" means that the diameter of the second engagement surface 73F is slightly larger than the diameter of the first engagement surface 65F, so that the second part 62F is press-fitted into the first part 61F, thus providing a retaining function. Alternatively, the two parts 61F and 62F could be retained to each other differently, for example, by bonding, riveting, screwing, or welding.

[0042] Advantageously, the second part 62F of the rotor shaft 6F also includes a first thrust surface 72F bearing axially against the first part 61F of the rotor shaft. For assembling the two parts 61F and 62F, the second part 62F can be inserted into the first axial opening 64F until the first thrust surface 72F abuts the first part 61F. The assembly and correct relative positioning between the two parts 61F and 62F are thus ensured.

[0043] The first mounting surface 65E has the shape of a continuous cylinder of revolution. By "continuous" cylinder of revolution, it is understood that the first mounting surface 65F has 360° circular symmetry, or in other words, that the first mounting surface 65F is uninterrupted. Conversely, the interlocking portion 63F includes two notches 66F that interrupt the cylindrical shape of revolution. In other words, the second mounting surface 73F has the shape of a discontinuous cylinder of revolution. Each of the two notches 66F is designed to receive a radial arm 27F of an electrical connection element 10F, which will be described in more detail later. The two notches 66E extend parallel to the axis of rotation X from the front end of the second portion 62E. The two 66E notches are diametrically opposed.

[0044] The electric motor IL therefore includes an electrical connection element 10E. The electrical connection element 10E is similar, or even identical, to the electrical connection element 10A described previously. The electrical connection element 10E comprises a body 20E made of an electrically insulating material, in particular plastic, two slip rings, 16E, 17F, two electrical connectors 22F intended to be connected respectively to the two ends of the wound rotor coil, and two conductors 24F, each connecting a slip ring 16F, 17F to an electrical connector 22F. The slip rings, 16E, 17E, are coaxial and centered on the axis of rotation X. They are preferably made of copper. The conductors 24E may also be copper wires. The cross-section of the wires is suitable for carrying high-intensity electrical currents to supply the rotor coil with electric current. The electrical connection element 10E It further comprises two radial arms 27F, each conductor 24F extending into one radial arm. The two radial arms are diametrically opposed. The body 20F includes an axial portion around which the two slip rings 16F and 17F are arranged. The axial portion is then extended by the two radial arms 27F. The two radial arms 27F may optionally be connected by an annular ring.

[0045] The second portion 62F of the rotor shaft 6F comprises a tubular shape centered on the axis of rotation X. Consequently, the second portion of the rotor shaft includes a second axial opening 67F. The axial portion of the body 20F extends through the second axial opening 67F. The radial arms 27F extend through the two notches 66F at the rear of the first portion 61F. The electrical connection element 10F is therefore positioned at the rear of a rear edge of the first portion 61F. Static sealing means, including O-rings 25F, are arranged around the axial portion of the body 20F. The O-rings 25F are in direct contact with an internal surface of the second portion 62F.

[0046] The second part 62F of the rotor shaft 6F further comprises a support portion 68F having a first receiving surface 69F in the form of a continuous cylinder of revolution. The bearing housing 29F is press-fitted onto the first receiving surface 69F. The support portion 68F is positioned behind the socket portion 63F. The support portion 68F is also positioned in line with the first part 61F, behind the first part 61F. An inner ring 30F of the bearing housing 29F is in direct contact with the first receiving surface 69F. The diameter of the first receiving surface 69F can be substantially equal to the diameter of the second socket surface 73F.

[0047] Advantageously, the second part 62F of the rotor shaft 6F also includes a second thrust surface 74F against which the inner ring 30F bears axially. For assembling the bearing housing 26F to the second part 62F of the rotor shaft, the inner ring 30F can be pressed onto the support portion 68F until the inner ring 30F abuts against the second thrust surface 74F. The assembly and correct relative positioning between the second part 62F and the bearing housing 29F are thus ensured.

[0048] The second part 62F of the rotor shaft 6F further includes a sealing portion 70F provided with a second receiving surface 71F in the form of a continuous cylinder of revolution. The sealing gasket 31F includes a lip 75F in direct contact with the second receiving surface 71F. The sealing portion 70F is positioned at the rear of the support portion 68F. The bearing housing 29F is therefore located on the side of the electric motor through which oil circulates and It can therefore be lubricated by this oil. The sealing portion 70F and the support portion 68F are positioned at the height of the axial part of the body 20F of the electrical connection element 10F. The diameter of the second receiving surface 72F may be strictly smaller than the diameter of the first receiving surface 69F.

[0049] To manufacture a power supply device as described above, the following procedure can be used. First, the first part 61F of the rotor shaft 6F, the second part 62F of the rotor shaft 62, and the electrical connection element 10F are provided as three separate components. Next, the electrical connection element 10F is assembled to the second part 62F of the rotor shaft so that the two radial arms 27F each extend through a notch 66F. This is done by simply inserting the electrical connection element 10F into the second axial opening 67F from the front side of the second part 62F.

[0050] Next, the second part 62F of the rotor shaft is assembled to the first part 61F of the rotor shaft. To do this, the socket portion 63F is simply inserted into the first axial opening 64F from the rear side of the first part 61F until the first thrust surface 72F comes into contact with the first part 61F.

[0051] The fabrication of the power supply device can then be continued by fitting the bearing housing 29F onto the support portion 68F until the inner ring 30F abuts against the second thrust surface 74F. Alternatively, the bearing housing 29F could be assembled to the second part 62F before assembling the second part to the first part.

[0052] Ultimately, this invention provides a simple-to-manufacture power supply device for a wound rotor of an electric motor in a motor vehicle. The power supply device offers a primary receiving surface for the bearing that is not interrupted by a notch. Therefore, there is no risk of deforming the inner ring of the bearing when it is pressed onto this receiving surface. The rotor can thus rotate at high speed without causing noise or vibrations related to deformation of the inner ring of the bearing. Furthermore, a standard bearing can be used, which simplifies the manufacturing process.

Claims

Demands

1. Power supply device for a wound rotor of an electric motor (1F) of a motor vehicle, characterized in that it comprises: - a rotor shaft (6F) comprising a first part (61F) and a second part (62F), the second part comprising a socket portion (63F) through which the second part is fixed to the first part, - an electrical connection element (10F) comprising at least one slip ring (16F, 17F), at least one electrical connector (22F) intended to be connected to a first end of a coil of the wound rotor, and at least one conductor (24F) electrically connecting the slip ring to the connector, the connection element further comprising at least one radial arm (27F), at least one conductor extending into at least one radial arm, the socket portion (63F) comprising at least one notch (66F) through which at least one radial arm extends.

2. Power supply device according to the preceding claim, characterized in that it further comprises a bearing support (29F) intended to guide the rotation of the rotor about an axis of rotation (X), and in that the second part (62F) of the rotor shaft comprises a support portion (68F) provided with a first receiving surface (69F) in the form of a continuous cylinder of revolution, the bearing support being fitted onto the first receiving surface.

3. Power supply device according to any one of the preceding claims, characterized in that it further comprises a sealing gasket (31F) intended to be fixed to a housing (2F) of the electric motor, and in that the second part of the rotor shaft comprises a sealing portion (70F) provided with a second receiving surface (71F) in the form of a continuous cylinder of revolution, the sealing gasket comprising a lip (75F) in contact with the second receiving surface.

4. A power supply device according to any one of the preceding claims, characterized in that the first part (61F) of the rotor shaft comprises a first axial opening (64F), and in that the interlocking portion (63F) is fitted inside the first axial opening.

5. Power supply device according to any one of the preceding claims, characterized in that the second part (62F) of the rotor shaft comprises a second axial opening (67F), and in that the electrical connection element (10F) extends through the second axial opening.

6. Power supply device according to any one of the preceding claims, characterized in that the first part (61F) of the rotor shaft comprises a first engagement surface (65F) cooperating with a second engagement surface (73F) of the socket portion (63F) to fix the second part to the first part, the first engagement surface comprising a continuous cylinder of revolution, and in that the electrical connection element (10F) is positioned at the rear of the first part of the rotor shaft.

7. Power supply device according to any one of the preceding claims, characterized in that the second part (62F) of the rotor shaft comprises a first thrust surface (72F) axially supported against the first part (61F) of the rotor shaft.

8. Power supply device according to any one of the preceding claims, characterized in that the electrical connection element comprises a first slip ring (16F), a second slip ring (17F), a first electrical connector for connection to a first end of a wound rotor coil, a second electrical connector (22F) for connection to a second end of the wound rotor coil, a first conductor electrically connecting the first slip ring to the first connector, a second conductor (24F) electrically connecting the second slip ring to the second connector, a first radial arm within which the first conductor extends, and a second radial arm (27F) within which the second conductor extends, the second radial arm being diametrically opposite to the first radial arm,the interlocking portion comprising a first notch through which the first radial arm extends and a second notch (66F) diametrically opposite the first notch and through which the second radial arm extends.

9. Electric motor (1F) for a motor vehicle comprising a wound rotor equipped with at least one coil and an electric power supply device according to any one of the preceding claims, the electric power supply device being configured to electrically supply F at least one coil of the wound rotor.

10. A method for manufacturing a power supply device according to any one of claims 1 to 8, characterized in that it comprises: - the supply of the first part (61F) of the rotor shaft, the second part (62F) of the rotor shaft, and the electrical connection element (10F), then - the assembly of the electrical connection element to the second part of the rotor shaft such that at least one radial arm (27F) of the electrical connection element extends through at least one notch (66F), then - the assembly of the second part of the rotor shaft to the first part of the rotor shaft.

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