Set of elements of a power train

Abstract

The invention relates to a set of elements of a power train for a motor vehicle, comprising: - an axial flux electric machine comprising a rotor (110), a stator and a first casing (130) to which the stator is fixed; - a second casing (230). According to the invention, the set of elements comprises at least one elastically deformable means (301, 302) sandwiched between the first casing and the second casing.

Description

DESCRIPTION TITLE OF THE INVENTION: SET OF ELEMENTS OF A POWERTRAIN TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates generally to the field of electrical machines.

[0002] It relates more specifically to a set of elements of a powertrain.

[0003] The invention finds a particularly advantageous application in the production of powertrains for electric or hybrid motor vehicles (car, truck, bus, etc.). STATE OF THE ART

[0004] An axial flux electric machine typically consists of at least a stator and a rotor, with a magnetic gap separating them. The rotor carries a series of large permanent magnets, while a series of tooth-mounted coils are carried by the stator. When the coils are energized with an electric current, the rotor, which is secured to the output shaft of the electric machine, is subjected to a torque resulting from the magnetic field (the magnetic flux created being an axial flux for an axial flux electric machine).

[0005] The teeth are conventionally fixed to a casing surrounding the stator and rotor. In order to limit the axial size of the electrical machine, the thickness of the casing under the teeth is limited. This thickness is often even more limited as the casing delimits internal channels for cooling the coils within its thickness.

[0006] When the electrical machine is in operation, the coils and teeth are subjected to forces, mainly radial and axial but also tangential. They are subjected to electromagnetic forces which are due to the rotating magnetic field and the attraction of the rotor, and mechanical forces due to the rotation of the shaft driven by the rotor. These mechanical forces are mainly transmitted at the level of bearings between the housing and the rotor. They can come from a misalignment of the shaft or the rotor, an unbalanced rotor, or even from the splined connection between the rotor and the shaft ensuring the drive of the shaft by the rotor.

[0007] All these efforts generate vibrations within the electrical machine. In particular, they generate deformation of the casing, and therefore movement of the casing and teeth. This makes the electric machine noisy. In addition, the air gap varies as the teeth move, which greatly affects the performance of the electric machine. PRESENTATION OF THE INVENTION

[0008] In this context, the present invention provides a set of elements of a powertrain for a motor vehicle comprising: - an axial flux electric machine comprising a rotor, a stator and a first casing to which the stator is fixed; - a second casing; said set of elements comprising at least one elastically deformable means sandwiched between the first casing and the second casing.

[0009] Thus, thanks to the invention, the casing of the electric machine is supported, via the elastically deformable means, on another part of the powertrain. The casing of the electric machine thus has increased stiffness at the level of the elastically deformable means which acts as a return means opposing the movement of the casing. In other words, the elastically deformable means (which is light, compact and very inexpensive) limits the movement of the casing of the electric machine by securing it to the second casing.

[0010] The casing of the electric machine is thus less subject to deformations linked to the operation of the electric machine.

[0011] As a result, the electric machine is quiet because vibrations are reduced. In addition, the air gap is stabilized in the sense that it varies little during operation of the electric machine. This allows, for example, in upstream design, to reduce the air gap in order to increase the power produced by the electric machine.

[0012] Other advantageous and non-limiting characteristics of the set of elements according to the invention, taken individually or in all technically possible combinations, are the following: - the set of elements comprises a shaft rotatably connected to the rotor, and the first casing comprises a central edge which faces the shaft, the elastically deformable means being arranged in contact with the central edge; - the second casing comprises an extension which is designed to fit within a clearance in the central edge, the elastically deformable means being interposed between the extension of the second casing and the central edge of the first casing; - the set of elements comprises a shaft connected in rotation to the rotor around an axis of rotation, the elastically deformable means being sandwiched between a surface of the first casing substantially perpendicular to the axis of rotation and a surface of the second casing substantially perpendicular to the axis of rotation; - the set of elements comprises at least one bearing ensuring a mechanical connection of the first casing with the rotor or of the second casing with a shaft connected in rotation to the rotor, and the elastically deformable means is positioned opposite the bearing; - the elastically deformable means is annular; - the elastically deformable means is made of elastomer; - the elastically deformable means is in compression when the electrical machine is stopped; - the set of elements comprises a powertrain element housed in the second casing, the powertrain element being one of the following parts: a gearbox, a speed reducer, another electric machine. DETAILED DESCRIPTION OF THE INVENTION

[0013] The description which follows with reference to the appended drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

[0014] On the attached drawings:

[0015] [Fig. 1] is a schematic sectional view of a set of elements of a powertrain according to the invention.

[0016] [Fig. 2] is a detail view of zone II of figure 1.

[0017] A set of elements 1 of a powertrain according to the invention is shown in Figure 1. Here, the set of elements 1 equips an electric or hybrid motor vehicle.

[0018] In the embodiment described here, this powertrain comprises two separate casings which house different components, namely here an electric machine (on the left in FIG. 1) and a reducer 200 or a gearbox or another electric machine (right in Figure 1).

[0019] As shown in Figure 1, the set of elements 1 thus includes in particular: - an axial flux electric machine 100 comprising a rotor 110, at least one stator 120 and a first casing 130; - a second 230 casing; and - at least one elastically deformable means 301, 302.

[0020] The rotor 110 conventionally comprises a body 111 which may have a star shape with branches extending radially, around an axis of rotation A1 (figure 1), from a central hub. The axial direction here corresponds to the direction of the axis of rotation A1 and a radial direction to a direction perpendicular to the axis of rotation A1. The branches then delimit between them notches radially open towards the outside, a magnetic pole element 112 being inserted in each notch. The magnetic pole elements 112 may then be surrounded by a hoop 113 to be blocked. The rotor 110 thus has an overall disc shape centered around the axis of rotation A1.

[0021] The set of elements 1 also comprises a shaft 400 connected in rotation to the rotor 100, in particular to be driven by the rotation of the rotor 110 around the axis of rotation A1. The shaft 400 therefore makes it possible in particular to transmit the rotational movement of the rotor 110 to the wheels of the motor vehicle. The shaft 400 is here mechanically coupled to the rotor 110 by means of a splined connection.

[0022] As shown in Figure 1, the body 111 of the rotor 110 comprises for this purpose a shaft portion 114 that is generally tubular around the axis of rotation A1. One end of the shaft 400 is fitted into the shaft portion 114 of the body 111 of the rotor 100. The shaft 400 and the shaft portion 114 each have ribs 115, 401 extending parallel to the axis of rotation A1, as can be seen in Figure 2 (which is an enlargement of a central part of the set of elements), to form said splined connection. Thus, the ribs 115 of the shaft portion 114 cooperate with the ribs 401 of the shaft 400 to transmit the rotation of the rotor 110.

[0023] As shown in Figure 1, the axial flux electric machine 100 here comprises two stators 120 located on either side of the rotor 110. The stators 120 have the shape of flattened rings and are equipped, on their faces located on the rotor side, with teeth 121 around which windings 122 are wound. of electrically conductive wires. When these windings 122 are supplied with electric current, they generate a rotating magnetic field driving the magnetic pole elements 112, which sets the rotor 110 in motion around the axis of rotation A1.

[0024] In the following, we are more particularly interested in the stator 120 located on the side of the shaft 400 (to the right of the rotor 110 in figure 1) and which is called “the stator” 120. The teeth 121 and the windings 122 mentioned subsequently are those of this stator 120.

[0025] Within the electrical machine 100, the distance between the magnetic pole element 112 and each tooth 121 axially facing it is called the magnetic air gap. The magnetic air gap is preferably short so that the attractive force of the winding 122 on the magnetic pole element 112 is high.

[0026] The first housing 130 surrounds the stator 120 and the rotor 110. The first housing 130 is a protective enclosure in the sense that it is designed to protect the stator 120 and the rotor 110.

[0027] The first casing 130 also serves as a support for the stator 120. The stator 120, and more particularly its teeth 121, are in fact fixed to the first casing 130. The first casing 130 therefore has a rigidity suitable for holding the teeth. The first casing 130 is for example made of metal, for example aluminum, die-cast aluminum alloy ALSi9Cu3, steel, or cast iron.

[0028] As shown in Figure 1, the first casing 130 comprises several assembled parts, one of which is located on the side of the second casing 230. This part has a substantially planar wall orthogonal to the axis of rotation A1, hereinafter called the side wall 133. This side wall 133 is bordered on its periphery by a peripheral wall 132 surrounding the stator 120.

[0029] This part has a central opening delimited by a central edge 131. The central edge 131 of the first casing 130 extends here along a cylindrical surface of revolution centered around the axis of rotation A1, as shown in Figure 1.

[0030] The teeth 121 of the stator 120 are here fixed on an inner face 134 of the side wall 133, which is substantially orthogonal to the axis of rotation A1. Here, the term “substantially orthogonal” or “substantially perpendicular” to the axis of rotation A1 means a direction or a surface forming an angle between 89 degrees and 91 degrees relative to the axis of rotation A1. For example, a maximum offset of the axis of rotation of 0.12° may be provided in the rib chain. The side wall 133 of the first casing 130 has, for example, a thickness, i.e. an axial dimension, of 7 mm.

[0031] The second casing 230 has, over at least part of its axial length, a diameter, that is to say a dimension in a direction perpendicular to the axis of rotation A1, similar to that of the first casing 130. The second casing 230 is for example made of the same material as that of the first casing 130.

[0032] The second casing 203 is here structurally linked to the first casing 130, in particular at the peripheral wall 132 of the first casing 130. The first casing 130 and the second casing 230 are for example fixed to each other by screws.

[0033] As shown in Figure 2, the second casing 230 comprises on the side of the first casing 130 a flat wall 233 which has an opening through which the shaft 400 extends. This flat wall 233 carries, on the side of the first casing, an extension 231, here tubular, which extends around the opening and which is designed to fit, with the assembly clearance, into the opening delimited by the central edge 131 of the first casing 130. The clearance between the extension 231 and the central edge 131 is for example between 20 μm and 60 μm. The extension 231, also called the “centering surface”, makes it possible, during assembly of the powertrain, to center the first casing 130 relative to the second casing 230. This makes it possible in particular to center, and therefore here to align, the ribs 115 of the rotor 110 with the ribs 401 of the shaft 400.

[0034] The set of elements 1 comprises first bearings 501 arranged between the first casing 130 and the rotor 110, and second bearings 502 arranged between the second casing 230 and the shaft 400. The first bearings 501 provide a mechanical connection between the first casing 130 and the rotor 110, and more particularly between the shaft portion 114 of the rotor 110 and the first casing 130. The second bearings 502 provide a mechanical connection between the shaft 400 and the second casing 230. These mechanical connections thus provide rotational guidance for these shafts 400 and shaft portion 114.

[0035] As Figure 2 clearly shows, element set 1 here includes: - a first elastically deformable means 301; and - a second elastically deformable means 302.

[0036] Each elastically deformable means 301, 302 is arranged between, that is to say interposed between, the first casing 130 and the second casing 230. Each elastically deformable means 301, 302 is more particularly sandwiched between the first casing 130 and the second casing 230. Each elastically deformable means 301, 302 is here directly in contact with the first casing 130 and the second casing 230.

[0037] Each elastically deformable means 301, 302 is here arranged to oppose a movement of the first casing 130 relative to the second casing 230. Each elastically deformable means 301, 302 is thus a damper in the sense that it attenuates the movements of the first casing 130, here by bearing on the second casing 230.

[0038] Each elastically deformable means 301, 302 is “elastically deformable” in the sense that it undergoes elastic (and not plastic) deformation when the first casing 130 moves relative to the second casing 230 during normal use of the powertrain.

[0039] Preferably, each elastically deformable means 301, 302 is in compression when the electrical machine 100 is stopped. This means that each elastically deformable means 301, 302 is sandwiched between the first casing 130 and the second casing 230.

[0040] Advantageously, the elastically deformable means 301, 302 are located close to the shaft 400 (and therefore the bearings 501, 502), that is to say here in or close to the central opening of the first casing 130. This means in particular that the elastically deformable means 301, 302 are closer to the central edge 131 than to the peripheral wall 132 of the first casing 130. Indeed, the movement of the first casing 130 relative to the second casing 230 is mainly composed of a deformation of the first casing 130 at the central opening of the first casing 130, the peripheral wall 132 of the first casing 130 being here secured to the second casing 230 by the screws. Positioning the elastically deformable means 301, 302 near the shaft 400 thus makes it possible to limit the movements of the first casing 130 in the area where these are potentially the largest.

[0041] As shown in Figure 2, the first elastically deformable means 301 is arranged between the central edge 131 of the first casing 130 and an external face of the extension 231 of the second casing 230. The first elastically deformable means 301 is therefore in particular arranged to oppose a radial movement (i.e. perpendicular to the axis of rotation A1) of the first casing 130, in particular towards the axis of rotation A1. The first elastically deformable means 301 is here located, relative to the extension 231 of the second casing 230, opposite the second bearings 502. The first elastically deformable means 301 is thus located opposite the first bearings 501.

[0042] The first elastically deformable means 301 is here annular and extends around the shaft 400. It has for example a diameter of 64 mm.

[0043] As shown in Figure 2, the first elastically deformable means 301 is arranged in a shoulder 232 provided at the free end of the extension 231 of the second casing 230. The first elastically deformable means 301 has for example a substantially rectangular section, in a plane containing the axis of rotation A1. The stiffness of the first elastically deformable means 301 depends in particular on the dimensions of the section. The stiffness is for example chosen to filter certain specific vibration frequencies.

[0044] Advantageously, the position and the annular shape of the first elastically deformable means 301 allows effective centering of the second casing 230 relative to the first casing 130. In other words, the first elastically deformable means 301 improves the coaxiality of the extension 231 of the second casing 230 and of the central edge 131 of the first casing 130 with the axis of rotation A1. Preferably, the extension 231 of the second casing 230 is in contact with the first elastically deformable means 301 without being in contact with the central edge 131 of the first casing 130. Remarkably, this centering improves the alignment of the ribs 115 of the rotor 110 with the ribs 401 of the shaft 400, which reduces the forces on the first casing 130 during rotation of the rotor 110. In addition to reducing the movements of the first casing 130 by damping the vibrations, the first elastically deformable means 301 therefore contributes to reducing the occurrence of these movements.

[0045] As shown in Figure 2, the second elastically deformable means 302 is arranged at one end of the central edge 131 in the direction of the second casing 230. The second elastically deformable means 302 is interposed more precisely between the first casing 130, around its central opening, and the flat wall 233 of the second casing, around the extension 231 (figure 2). The second elastically deformable means 302 is in particular arranged to oppose an axial movement, i.e. along the axis of rotation A1, of the first casing 130 towards the second casing 230. The second elastically deformable means 302 is here located, relative to the side wall 133, opposite the first bearings 501. The second elastically deformable means 302 is also located, relative to the flat wall 233, opposite the second bearings 502. The second elastically deformable means 302 is thus located at the height (radially) of the first bearings 501 and the second bearings 502. It also has a diameter similar to those of these bearings. In the example of FIG. 1, it is for example located less than 10 mm from the first bearings 501 and the second bearings 502.

[0046] The second elastically deformable means 302 is sandwiched between two surfaces, one of the first casing 130 and the other of the second casing 230, substantially perpendicular to the axis of rotation A1. The second elastically deformable means 302 is here substantially flat and extends more particularly along a plane substantially perpendicular to the axis of rotation A1.

[0047] The second elastically deformable means 302 is for example annular. The stiffness (and therefore the section) of the second elastically deformable means 302 can also be chosen to filter certain specific vibration frequencies.

[0048] Here, the second elastically deformable means 302 is formed from a single piece and extends all around the axis of rotation A1. Alternatively, the set of elements comprises a plurality of second elastically deformable means separated from each other and distributed around the shaft between the first and second casings. Each second means of the plurality can then have the shape of a rectangular parallelepiped.

[0049] Advantageously, the second elastically deformable means 302 makes it possible to effectively limit the movements of the first casing 130 along the axis of rotation A1 and therefore the variations in the air gap. This makes the performance of the electrical machine 100 more stable and also makes it possible, in upstream design, to provide a short air gap.

[0050] Each elastically deformable means 301, 302 is for example made of elastomer. Advantageously, in combination with an annular shape, each elastically deformable means 301, 302 then makes it more watertight. the junction between the first casing 130 and the second casing 230 at the level of the shaft 400, which makes it possible, for example, to protect the bearings 501, 502 from possible dust.

[0051] Preferably, the stiffness of each elastically deformable means 301, 302 is chosen so as to filter specific vibration frequencies, i.e. those of maximum amplitude, of the first casing 130.

[0052] The present invention is in no way limited to the embodiment described and shown, but those skilled in the art will be able to provide any variation in accordance with the invention.

[0053] Thus, the set of elements may comprise only the first elastically deformable means or only the second elastically deformable means.

[0054] Alternatively, the set of elements may comprise a single elastically deformable means acting as both the first elastically deformable means and the second elastically deformable means. Such an elastically deformable means has, for example, a ring shape with an L-shaped section, i.e. extending both axially and radially. It is, for example, arranged against the central edge of the first casing and against the extension and base of the second casing.

[0055] The elastically deformable means could also be fixed to the casings, for example by gluing. They could then work in compression and traction.

Claims

CLAIMS

1. Set of elements (1) of a powertrain for a motor vehicle comprising: - an axial flux electric machine comprising a rotor (110), a stator (120) and a first casing (130) to which the stator (120) is fixed; - a second casing (230); characterized in that said set of elements (1) comprises at least one elastically deformable means (301, 302) sandwiched between the first casing (130) and the second casing (230).

2. An assembly of elements (1) according to claim 1, wherein the assembly of elements (1) comprises a shaft (400) rotatably connected to the rotor (110), and wherein the first casing (130) comprises a central edge (131) which faces the shaft (400), the elastically deformable means (301, 302) being arranged in contact with the central edge (131).

3. Set of elements (1) according to claim 2, in which the second casing (230) comprises an extension (231) which is designed to fit with a clearance in the central edge (131), the elastically deformable means (301) being interposed between the extension (231) of the second casing (230) and the central edge (131) of the first casing (130).

4. Set of elements (1) according to one of claims 1 to 3, in which the set of elements (1) comprises a shaft (400) linked in rotation to the rotor (110) around an axis of rotation (A1), the elastically deformable means (302) being sandwiched between a surface of the first casing (130) substantially perpendicular to the axis of rotation (A1) and a surface of the second casing (230) substantially perpendicular to the axis of rotation (A1).

5. Set of elements (1) according to one of claims 1 to 4, in which the set of elements (1) comprises at least one bearing (501, 502) ensuring a mechanical connection of the first casing (130) with the rotor (110) or of the second casing (230) with a shaft (400) linked in rotation to the rotor (110), and in which the elastically deformable means (301, 302) is positioned opposite the bearing (501, 502).

6. Set of elements (1) according to one of claims 1 to 5, in which the elastically deformable means (301, 302) is annular.

7. Set of elements (1) according to one of claims 1 to 6, in which the elastically deformable means (301, 302) is made of elastomer.

8. Set of elements (1) according to one of claims 1 to 7, wherein the elastically deformable means (301, 302) is in compression when the electric machine (100) is stopped.

9. Set of elements (1) according to one of claims 1 to 8, further comprising a powertrain element (200) housed in the second casing (230), the powertrain element (200) being one of the following parts: a gearbox, a speed reducer, another electric machine.

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