Axial flux rotary electric machine

Abstract

The invention relates to an axial flux rotary electric machine (1) comprising at least one stator (2) and at least one rotor (4) arranged along the axis of rotation (X), the stator (2) being cooled by a circulating coolant, the stator (2) comprising at least one tooth (20) bearing a coil (100) wound concentrically around the tooth (20), the coil (100) comprising at least one flattened wire (106) wound on itself around the corresponding tooth (20) in a plurality of layers, wherein two consecutive layers of the flattened wire (106) are spaced apart by a non-zero distance d, the stator (2) further comprising at least one shell (9) accommodating at least one coil (100) wound around the tooth (20), the machine (1) being configured to enable the coolant to circulate between the layers of wire (106) in the shell (9).

Description

[0001] Description

[0002] Title: Axial flux rotating electric machine

[0003] The present invention claims priority from French application 2302385 filed on March 15, 2023, the content of which (text, drawings and claims) is incorporated herein by reference.

[0004] Technical field

[0005] The present invention relates to the field of rotating electrical machines, and more particularly to that of axial flux rotating electrical machines. The invention relates more particularly to machines cooled by a circulation of a cooling fluid, in particular oil, circulating at least partially through the stator of the machine.

[0006] The invention relates more particularly to synchronous or asynchronous alternating current machines. It relates in particular to traction or propulsion machines for electric (Battery Electric Vehicle) and / or hybrid (Hybrid Electric Vehicle - Plug-in Hybrid Electric Vehicle) motor vehicles, such as private cars, vans, trucks or buses. The invention also applies to rotating electrical machines for industrial and / or energy production applications, in particular naval, aeronautical or wind power applications.

[0007] Prior art

[0008] By "axial flux", it is meant that the magnetic flux circulating in the machine is oriented in the air gap formed between the rotor and the stator in a direction parallel to an axis of rotation of the machine, in contrast to a so-called radial flux machine, in which the magnetic flux circulates between the rotor and the stator in a radial direction, therefore perpendicular to the axis of rotation of the machine.

[0009] Such machines have many advantages, particularly in terms of torque density. In addition, their topologies can be varied: a configuration with one or more rotors and one or more stators is significantly easier, compared to radial flux rotating electrical machines. As for the cooling of axial flux rotating electrical machines, this is generally carried out indirectly, i.e. with thermal conduction inside the material. This leads to having several thermal resistances between the cooling fluid and the parts to be cooled, resulting in poor use of the thermal potential, i.e. the temperature difference, between the hot source and the cold source. To increase the power density of the motors, there is a need to improve the cooling efficiency.

[0010] Axial flux machines are known, for example from applications EP 3 108 574, EP 2 606 561, EP 3 764 526, EP 4 018 529, WO 2022 / 214146, WO 2022 / 123408 in which the cooling fluid circulates between coils, at the periphery thereof. Thus, in these machines, the passage of the cooling fluid is very limited and the wires of the coil themselves have little contact with the cooling fluid.

[0011] International application WO 2021 / 180267 relates to an axial flow machine in which cooling takes place between the teeth and the coils, with an individual coolant inlet. The structure of the machine is complex.

[0012] There is therefore a need to benefit from a rotating electrical machine allowing the exchange surface between the cooling fluid and the coils to be increased, while not complicating the structure of the machine.

[0013] Summary of the invention

[0014] The invention aims to meet this need and achieves this, according to one of its aspects, by means of an axial flux rotating electrical machine, comprising at least one stator and at least one rotor, arranged along an axis of rotation X of the machine, the stator being cooled by a circulation of a cooling fluid, the stator comprising a plurality of teeth, at least one tooth, or even each tooth, carrying a coil wound concentrically around said tooth, the coil comprising at least one flattened wire wound on itself around the corresponding tooth in a plurality of layers, two consecutive layers of flattened wire being spaced apart by a non-zero distance d, the stator comprising at least one shell, in particular a plurality of shells, the shell, in particular each shell, housing at least one coil wound around said tooth, the machine being configured to allow the circulation of the cooling fluid between the layers of wire in the shell.

[0015] Thanks to the spacing between the wire layers, in which the cooling fluid circulates, direct cooling of the stator coils can be achieved by utilizing a large exchange surface between the winding wires and the cooling fluid. The fluid can follow a spiral path formed by the wound wire. This is made possible by the flattened shape of the wires. Indeed, said flattened wires can prevent leaks or slippage between the layers that would occur when using round wires, particularly two round wires juxtaposed one on top of the other.

[0016] "Direct cooling" means that the machine's cooling fluid comes directly into contact with the coils, particularly the coil wire(s). Direct cooling provides a large heat exchange surface. Since the fluid is in direct contact with the coils of the machine, this avoids any intermediate thermal resistance due to conduction in the material and intermediate interfaces.

[0017] The coolant may be a liquid, for example, water or oil. The coolant may be deionized water. Alternatively, the coolant may be a gas, for example, air. Preferably, the fluid is non-ionic.

[0018] By "arranged along an axis of rotation of the machine" is meant that when moving along the axis of rotation X of the machine, one encounters one of the stator and the rotor in succession, then the other of the stator and the rotor. The stator(s) and rotor(s) of the machine are thus arranged successively along the axis of rotation of the machine, and not arranged concentrically, as in radial flux machines.

[0019] Thanks to the axial orientation of the machine according to the invention, the size of the machine can be reduced and its compactness improved. The surface area of ​​the air gap between the rotor and the stator being larger, a better electromechanical conversion is obtained. Indeed, the surface area of ​​the air gap is, in the case of an axial flux machine, weakly linked to the length of the stator and the rotor. The machine can therefore be less bulky.

[0020] Disclosure of the invention The concentrated coil may comprise a flattened conductive wire. 'Flattened wire' means a wire having an elongated cross-section, for example rectangular or substantially rectangular in shape. A ratio between a largest dimension of the cross-section of the wire and a largest dimension perpendicular thereto, called the thickness e of the wire, may be strictly greater than 1, better still greater than 1.5, or even greater than 2, being for example of the order of 5 / 2. It is also possible to use flattened wires whose ratio between the largest dimension of the cross-section of the wire and a largest dimension perpendicular thereto may be greater than 3, better still greater than 3.5, or even greater than 4, being for example of the order of 5.

[0021] The wire(s) may be made of copper. Alternatively, the wire(s) may be made of aluminum. They may be enameled. Alternatively, the wire(s) may not be enameled, but covered with an unenameled insulation.

[0022] The flattened wire may be wound around the corresponding tooth by being bent parallel to the largest dimension of the wire cross-section. In one embodiment, the flattened wire is wound around the corresponding tooth without being bent around the thickness of the wire cross-section. Advantageously, such a configuration allows for a smaller wire curvature radius, thus allowing the wire to be bent more around the tooth.

[0023] Two consecutive layers of flattened wire may be spaced apart by a distance d of between 0.05 mm and 1 mm, preferably between 0.08 mm and 0.9 mm, more preferably between 0.1 mm and 0.5 mm.

[0024] A ratio d / e between the distance d and the thickness e of the wire may be between 0.02 and 0.5, preferably between 0.05 and 0.4, better still between 0.1 and 0.3.

[0025] "Two consecutive layers of wire" means two layers of the same wire. The wire can be wound on itself around the tooth along an axial axis of the tooth. The axial axis of the tooth extends parallel to the X axis of rotation of the machine.

[0026] When the coil has multiple wires, the wires can be stacked on top of each other along the axial axis of the tooth.

[0027] A wire is wound on itself parallel to its largest dimension of the cross-section of said wire. Two consecutive layers of flattened wire may be spaced apart by a spacing member, in particular comprising a plurality of pellets arranged between the layers of wire.

[0028] The spacer member may be removably or non-removably attached to the wire or shell. Alternatively, it may be integral with the wire or shell.

[0029] The spacer member may comprise a plurality of bars or pads, which may be disposed between the layers of wire.

[0030] A bar may be parallelepipedal in shape. It may be much longer than it is wide. It may thus define large faces and small faces. It may extend from a face of the corresponding shell between the layers of wire, in particular perpendicular to the direction of elongation of the wire. Alternatively, the bar may extend parallel to the direction of elongation of the wire. It may be attached to the shell by a small face. Alternatively, it may be attached to the wire, for example by a large face. It may be placed on the wire perpendicular to the direction of elongation of the wire. Alternatively, it may be placed on the wire parallel to the direction of elongation of the wire.

[0031] A pellet can be approximately as long as it is wide. It can be circular or any other shape, for example, rectangular. It can be attached to the shell. Alternatively, it can be attached to the wire.

[0032] The spacer member, which may comprise a plurality of bars or pads, may be arranged, in particular by gluing, on one face of the wire, in particular on the largest dimension of the cross-section of said wire.

[0033] A pad may be fixed, for example glued, to the largest dimension of the cross-section of the wire. It may be of a thickness smaller than the largest dimension of the cross-section of the wire. Alternatively, it may be of a thickness equal to or wider than the largest transverse dimension of the wire.

[0034] A pellet, in particular all the pellets, or a bar, in particular all the bars, may have a thickness Ea of between 0.01 mm and 0.9 mm, preferably between 0.05 and 0.7 mm, better still between 0.1 mm and 0.5 mm, in particular approximately 0.2 mm.

[0035] The pads or bars can be positioned on curved parts of the wire. Alternatively, they can be positioned on straight parts of the wire. They can also be positioned on curved and straight parts of the wire.

[0036] They can be arranged on a given wire at regular or irregular intervals. Several pellets of different shapes can be arranged on the same wire, following a regular or random pattern. An interval between two consecutive pellets on a given wire can be a non-zero distance D. They can also be distributed at different heights of the wire.

[0037] The pellets or bars can advantageously, in addition to their spacing function, act as flow disruptors. Indeed, they can generate local vortices, and thus promote the cooling of the coils. This increases the areas of turbulence and creates disturbances, improving the flow of the fluid, in particular by generating local vortices.

[0038] The spacer member may comprise pellets composed of a mineral material, in particular glass or ceramic. Alternatively, the pellets may be composed of an organic material, in particular a polymer. Preferably, this polymer material can withstand temperatures of the order of 200 to 250°C.

[0039] A shell may accommodate a single tooth. Alternatively, the shell may accommodate a plurality of teeth, including two teeth. In one embodiment, the shell may accommodate all of the stator teeth.

[0040] The shell may comprise internal partitions, in particular at least one internal partition. Alternatively, the shell may comprise more than two internal partitions. The shell may comprise as many internal partitions as there are teeth. Each tooth may be separated from the other teeth by two partitions extending on either side of said tooth.

[0041] According to this embodiment, the shell can provide rigidity to the stator. In addition, this embodiment allows for easier assembly of the machine.

[0042] The shell may include a wall surrounding the tooth carrying the coil housed in said shell. This wall may be in contact with the tooth.

[0043] The shell may comprise at least one air gap wall facing the air gap and the rotor. The air gap wall may cover the tooth. The shell may have an air gap wall thickness Ep of between 0.2 mm and 5 mm, preferably between 0.25 mm and 2 mm, more preferably between 0.3 mm and 1 mm. The thickness of the air gap wall is very small, which makes it possible to reduce the size of the shell at the air gap. The shell may also comprise a peripheral wall which connects to the air gap wall of the shell.

[0044] This peripheral wall may comprise two half-shells, a first half-shell and a second half-shell. These two half-shells may be symmetrical with respect to each other. Alternatively, they may not be symmetrical with respect to each other.

[0045] The two half-shells can be assembled together in a watertight manner. The two half-shells can be closed together with a good seal. A sealing gasket can be arranged between the two half-shells. One half-shell can have a sealing lip covering a groove in the other half-shell.

[0046] The shell can have a height Ec. The height Ec can be between 3 mm and 100 mm, preferably between 5 mm and 50 mm, better between 10 mm and 30 mm.

[0047] The shell can be made of plastic, especially molded plastic.

[0048] The air gap wall may cover the tooth, or alternatively not cover it. The air gap wall may provide a window for the tooth. The tooth may be visible from outside the shell, when the shell is in place on the tooth. The tooth may be flush with the shell, particularly at its air gap wall. Alternatively, the tooth may be slightly set back from the shell or, on the contrary, be prominent relative to the shell to reduce the magnetic air gap.

[0049] The shell can be closed over the tooth tightly at the window surrounding the tooth.

[0050] When the stator has no yoke, the tooth is inserted into the shell, in particular in its entirety. In this case, the shell may include two air gap walls, each facing a rotor, and which face the two air gaps.

[0051] When the stator is provided with a yoke, the shell may then not be drilled at the wall facing the yoke. The tooth may be inserted between an edge of the yoke and the air gap walls of the shell.

[0052] The characteristics described above are valid for at least one shell, in particular two shells, better still several shells, or even all the shells of the stator, better still all the shells of the machine. The shell may include an inlet tube for the coolant and a coolant outlet tube.

[0053] The inlet tube and the outlet tube of the shell can be configured to provide electrical connection to the corresponding coil. They can, for example, be made of electrically conductive material, in particular metal, for example copper.

[0054] Alternatively, the inlet and outlet tubes may not be configured to provide electrical connection. For example, they may be made of plastic.

[0055] The inlet tube and the outlet tube may have a similar shape to each other. Alternatively, they may have a different shape. Said shape may for example be hollow, in particular cylindrical. In cross-section, the shape may be substantially circular, or alternatively substantially square, or alternatively substantially triangular.

[0056] The inlet tube may have a first open end. The inlet tube may have a second closed end. The closed end may be opposite the open end along the longitudinal axis of the inlet tube.

[0057] The inlet tube may have one or more slots, including a single slot. The slot may be closer to the closed end of the inlet tube.

[0058] The discharge tube may have a first open end. The inlet tube may have a second closed end. The closed end may be opposite the open end along the longitudinal axis of the discharge tube.

[0059] The discharge tube may have one or more slits, including a single slit. The slit may be closer to the closed end of the discharge tube.

[0060] The slots in the inlet tube and the outlet tube can serve as an inlet and / or outlet into the corresponding tube.

[0061] The slot in the inlet tube may serve as an inlet to a chamber in the shell. The slot in the outlet tube may serve as an outlet to a chamber in the shell. The chamber in the shell may accommodate the flattened wire wound on itself.

[0062] The inlet tube and the outlet tube may have the sole function of circulating the coolant and may not provide the electrical connection of the coil. Alternatively, the inlet tube and the outlet tube may have the dual function of circulating the coolant as well as establishing the electrical connection of the coil.

[0063] The tooth may have a groove in which the coolant inlet tube can be housed. The tooth may have a groove in which the coolant outlet tube can be housed.

[0064] The coil may have a single wire.

[0065] Alternatively, the coil may comprise at least two wires, in particular two wires, preferably superimposed on one another. The coil may thus comprise several wires, in particular superimposed on one another, for example superimposed along the axial axis of the tooth.

[0066] According to one embodiment, the coil may comprise two wires stacked on top of each other along the axial axis of the tooth. The two wires may be superimposed on top of each other around the same tooth. The two wires may be superimposed along the axial axis of the tooth. The two wires may be superimposed around the same tooth by being wound in the same direction of rotation. Alternatively, the two wires may be superimposed around the same tooth by being wound in two different directions.

[0067] The arrangement of the wires superimposed on each other makes it possible to minimize AC Joule losses.

[0068] The two wires can be electrically connected to each other by soldering.

[0069] The two wires of a single coil can be separated in the corresponding shell by a separating wall. The shell can be arranged in three parts. The shell can thus comprise two half-shells as well as a separating wall. The shell need not be in one piece. Alternatively, the shell can be in one piece.

[0070] The partition wall can be used to separate two chambers. Each chamber can accommodate one wire from the coil. Alternatively, each chamber can have at least two wires, in particular two wires.

[0071] The partition wall can allow each wire to come into contact with a large amount of coolant, which improves cooling.

[0072] The cooling fluid can flow from one chamber to the other through an orifice provided in the separating wall. This orifice allows the fluid connection between the two chambers separated by the separating wall. Alternatively, a connection element can be inserted into the orifice provided in the wall in order to ensure the electrical connection. The orifice provided in the wall can be slightly wider in order to ensure the insertion of said connection element as well as the fluid connection between the two chambers. The connection element can be made of a conductive material, in particular copper.

[0073] Alternatively, the machine may include a connecting tube that provides a fluid connection between the two chambers. The connecting tube may or may not also provide an electrical connection between the two wires. Alternatively, it is possible to omit the connecting tube. In this case, soldering can electrically connect the two wires.

[0074] The connection tube may, for example, be made of electrically conductive material, in particular metal, for example copper.

[0075] Alternatively, the connecting tube may not be configured to provide the electrical connection. For example, it may be made of plastic.

[0076] The shape of the connecting tube may, for example, be hollow, in particular cylindrical. In cross-section, the shape may be substantially circular, or alternatively substantially square, or alternatively substantially triangular.

[0077] The connecting tube may have two slots, namely a first slot and a second slot. The first slot may be closer to one end of the connecting tube. The second slot may be closer to the opposite end of the connecting tube. The first and second slots may be arranged opposite each other with respect to a cross-section of the connecting tube. The first and second slots may be arranged opposite each other with respect to a longitudinal axis of the connecting tube.

[0078] The first slot of the connecting tube may serve as an outlet to a first chamber provided in the hull. The second slot of the connecting tube may serve as an inlet to a second chamber provided in the hull.

[0079] The connecting tube allows the circulation of the cooling fluid between the two chambers, in particular between the first chamber and the second chamber. It ensures the fluid connection between the two chambers.

[0080] In one embodiment, the current inlet and outlet and the cooling fluid inlet and recovery may be located on the outer diameter of the stator. The electrical connection may be made via the inlet tube. The fluid connection may be made via the inlet tube. The fluid connection may be made between the two chambers, in particular between the first and second chambers.

[0081] In one embodiment, the electric current may flow in the same direction in both wires. Alternatively, the electric current may flow in a first direction in the first wire, and in an opposite direction in the second wire.

[0082] The teeth of the stator may each be of a generally substantially prismatic shape, in particular substantially trapezoidal, triangular, or even circular, comprising in particular, in cross-section taken perpendicular to the axis of rotation of the machine, one or two portions of circles, in particular concentric, connected by two radii or, alternatively, one or two linear portions connected by two radii.

[0083] The larger portion of the two linear or partially circular portions may be located towards the outside of the machine. Alternatively, the stator teeth may be of a different shape, for example rectangular. The axial length of a stator tooth, measured along the axis of rotation of the machine, may be greater than the axial length of a winding measured along the axis of rotation of the machine.

[0084] The stator coils may be of corresponding shape. The stator teeth have a front face facing the rotor. Said faces are preferably flat and extend perpendicular to the axis of rotation of the machine.

[0085] The stator may be without a yoke.

[0086] The stator may be concentrated wound, i.e. wound on teeth, with each coil surrounding a tooth, and each tooth carrying a coil. The stator winding may be multiphase. The number of phases may be at least 3, for example equal to 3, or greater than 3, for example 5, 7, 11, 13, or 17, or even more.

[0087] The wires used can be insulated at low voltage, being enamelled or even covered with enamel, or at medium voltage, being insulated with mica paper for example, or even at very high voltage, being for example made with high voltage cable.

[0088] The stator may have between 6 and 48 teeth, for example 12 teeth in one embodiment. The stator may have at least 6 teeth, for example 6, 12 or 18 teeth, or even more. The stator coils are preferably each wound around a winding axis parallel to the axis of rotation X of the machine. The coils may comprise copper or aluminum wires, or any other electrically conductive material.

[0089] The stator teeth can be attached to an annular stator armature. The teeth can be made in one piece with this annular stator armature, or alternatively be held on it by any means such as for example gluing, welding, screwing, assembly, for example by dovetails, this list not being exhaustive.

[0090] The teeth can be formed from a stack of sheets, held together by any means such as, for example, gluing, snap-fastening, riveting and attached to the annular stator armature, for example by screwing.

[0091] The teeth can also be made from an isotropic material, such as magnetic powders agglomerated by sintering or bonding, anisotropic magnetic materials such as magnetic sheets, possibly with oriented grains, amorphous magnetic materials, or by adding metal using so-called 3D printing processes.

[0092] The annular stator armature is preferably non-magnetic. It is made of aluminum, for example. Thus, the stator can be without a magnetic yoke, which is less expensive. Alternatively, the annular stator armature is not non-magnetic. It can, in particular, be magnetic when it serves as a yoke.

[0093] The machine may have a single stator and a single rotor.

[0094] Alternatively, the machine may comprise at least two rotors arranged on either side of the stator along the axis of rotation of the machine. The machine may comprise a single stator and two rotors. The stator is then said to be central. The two rotors may be arranged on either side of the central stator, in particular at an equal distance from the central stator.

[0095] The two rotors surrounding the stator may or may not be angularly offset from each other. In one embodiment, there may be no angular offset between the two rotors. The two rotors may be symmetrical about a plane perpendicular to the axis of rotation of the machine.

[0096] The stator teeth may each carry two coils arranged on the corresponding tooth on either side of the annular stator armature, each of the two coils facing one of the two rotors. The stator teeth may in particular be attached by their middle to said annular stator armature. The two resulting half-teeth may be of the same size, as may the coils they carry.

[0097] The stator can be symmetrical about a plane perpendicular to the axis of rotation of the machine.

[0098] In another embodiment, the machine may comprise two stators and a central rotor. In another embodiment, the machine may comprise several stators and several rotors.

[0099] The machine can be a synchronous or asynchronous motor or a synchronous or asynchronous generator.

[0100] The machine may have at least 4 stator teeth, for example 4, 6, 8, 10 or 12 stator teeth or any multiple thereof.

[0101] The machine according to the invention may constitute a motor. In the case of a motor, the number of poles of the rotor of the machine may be at least 4, being for example 4, 6, 8, 10 or 12 or one of their multiples. One of the advantages of such a machine is its compactness.

[0102] Alternatively, the machine can also be a generator. In this case, it can have 4, 6, 8, 10 or 12 poles on the rotor of the machine, for example, or one of their multiples.

[0103] In an alternative embodiment, the machine comprises, for example, 12 teeth and

[0104] 10 poles

[0105] The rotor may comprise a rotor mass and housings provided in the rotor mass, these housings being in particular in the form of slots. The housings define magnetic poles of the rotor, said housings being able to contain or not each at least one permanent magnet.

[0106] The rotor may have permanent magnets inserted into the rotor mass.

[0107] 11 may include permanent magnets, including surface or buried magnets. The rotor may be flux-concentrating. It may include one or more layers of magnets arranged in an I, U or V shape, in one or more rows. The housings for the permanent magnets may be made entirely by cutting into the sheets.

[0108] The rotor may comprise a shaft extending along an axis of rotation, on which the rotor mass is arranged. This shaft is integral with the rotor(s), and rests by at least one bearing, for example one or two bearings, on a casing of the machine, in particular one or two end flange(s) of the machine.

[0109] The shaft may be made of a magnetic material, which advantageously reduces the risk of saturation in the rotor mass and improves the electromagnetic performance of the rotor. The shaft may include a magnetic sleeve in contact with the rotor mass, the sleeve being mounted on an axis, magnetic or not.

[0110] Alternatively, the rotor may comprise a non-magnetic shaft on which the rotor mass is arranged. The shaft may, for example, be made at least in part from a material from the following list, which is not limiting: non-magnetic steel, stainless steel, titanium or any other non-magnetic material. The rotor mass may, in one embodiment, be arranged directly on the non-magnetic shaft, for example without an intermediate rim. Alternatively, in particular in the case where the shaft is not non-magnetic, the rotor may comprise a rim surrounding the rotor shaft and bearing on the latter.

[0111] The rotor magnetic mass can be made in whole or in part with magnetic laminations.

[0112] Brief description of the drawings

[0113] The invention will be better understood by reading the detailed description which follows, non-limiting examples of its embodiment, and by examining the attached drawing in which:

[0114] [Fig 1] Figure 1 is a schematic view of different machine configurations, with different numbers of stators and rotors,

[0115] [Fig 2] Figure 2 is a schematic and partial perspective view of a stator according to the invention,

[0116] [Fig 3] Figure 3 is a schematic and partial top view of the stator of Figure 2,

[0117] [Fig 4] Figure 4 is a schematic and partial side view of the stator of Figure 2,

[0118] [Fig 5] Figure 5 is a schematic, partial perspective view of a coil having a single wire, [Fig 6] Figure 6 is a schematic, partial perspective top view of the coil of Figure 5,

[0119] [Fig 7] Figure 7 is a top, schematic and partial view of the direction of current flow in the coil of Figure 6,

[0120] [Fig 8] Figure 8 is an isolated perspective view of the coil inlet tube of Figure 6,

[0121] [Fig 9] Figure 9 is an isolated perspective view of the coil exhaust tube of Figure 6,

[0122] [Fig 10] Figure 10 is a schematic and partial view of the coil spacing member of Figure 6, according to a first embodiment,

[0123] [Fig 11] Figure 11 is a schematic and partial view of the coil spacer member of Figure 6, according to a second embodiment,

[0124] [Fig 12] Figure 12 is a schematic and partial view of the coil spacer member of Figure 6, according to a third embodiment,

[0125] [Fig 13] Figure 13 is an exploded, schematic and partial view of an alternative embodiment of a coil comprising two wires superimposed along the axial axis of the tooth,

[0126] [Fig 14] Figure 14 is a schematic and partial perspective view of the closed hull of Figure 13,

[0127] [Fig 15] Figure 15 is a schematic and partial perspective view of the hull of Figure 13, without an air gap wall,

[0128] [Fig 16] Figure 16 is a section along axis AA of Figure 14,

[0129] [Fig 17] Figure 17 is a schematic and partial perspective view of the two wires superimposed around the tooth of the coil of Figure 13,

[0130] [Fig 18] Figure 18 is a perspective view of the inlet tube of the coil of Figure 13,

[0131] [Fig 19] Figure 19 is a perspective view of the coil exhaust tube of Figure 13,

[0132] [Fig 20] Figure 20 is a perspective view of the coil connecting piece of Figure 13,

[0133] [Fig 21] Figure 21 is a schematic and partial perspective view of another alternative embodiment, [Fig 22] Figure 22 is a schematic and partial perspective view of the coil of Figure 21,

[0134] [Fig 23] Figure 23 is an isolated view of the coil connecting piece of Figure 21, and

[0135] [Fig 24] Figure 24 is a schematic and partial view of the direction of flow of the electric current within the coil of Figure 21.

[0136] Detailed description

[0137] Figure 1 illustrates three examples of rotating electrical machines 1a, 1b and 1c. Each machine comprises at least one stator 2 and at least one rotor 4, arranged along the axis of rotation X of the machine, according to the axis 5 of the machine. The stator 2 is cooled by a circulation of a cooling fluid.

[0138] The rotating electrical machine 1a comprises a stator 2 and a rotor 4 separated by an air gap 3. The rotating electrical machine 1b comprises a stator 2 and two rotors 4 separated by two air gaps 3. The rotating electrical machine 1c comprises two stators 2 and a rotor 4 separated by two air gaps 3.

[0139] We will now describe in more detail, with reference to figures 2 to 12, an exemplary embodiment of the invention comprising a single stator 2 and two rotors 4. The two rotors 4 are arranged on either side of the central stator 2, at an equal distance from the stator 2. The stator 2 may not have a yoke.

[0140] The stator 2 comprises twelve shells 9, as illustrated in Figures 2 and 3. Each shell 9 is arranged between two neighboring shells. All the shells 9 are arranged in a circle, forming a central recess 16 for the passage of the axis 5.

[0141] Each shell 9 houses a single tooth 20. The shell 9 has two air gap walls 11, each facing an air gap 3 and a rotor 4. Each air gap wall 11 covers the tooth 20.

[0142] The shell 9 also comprises a peripheral wall 17 which connects to the air gap walls 11 of the shell 9. The peripheral wall 17 is in one piece. The shell 9 is closed on the tooth 20 in a sealed manner at the junction between the air gap walls 11 and the peripheral wall 17.

[0143] The shell has a height Ec of between 10 mm and 30 mm. The air gap wall 11 which covers the tooth has a thickness Ep of between 0.3 mm and 1 mm. The teeth 20 of the stator 2 are each of a substantially triangular general shape, comprising in cross section taken perpendicular to the axis of rotation X of the machine a portion of a circle and two radii.

[0144] The characteristics described above are valid for all teeth 20 of machine 1.

[0145] Each tooth 20 carries a coil 100 wound concentrically around said tooth 20. The coil 100 comprises a flattened wire 106. The wire 106 is wound on itself around the corresponding tooth 20. The flattened wire 106 has an elongated cross-section, of substantially rectangular shape. A ratio between a larger dimension of the cross-section of the wire 106 and a larger dimension perpendicular thereto, called the thickness e of the wire, is of the order of 5 / 2, as illustrated in Figure 10.

[0146] The wire 106 is wound into a plurality of consecutive layers of flattened wire 106. Two consecutive layers of wire 106 are spaced apart by a non-zero distance d. Two consecutive layers of wire 106 are spaced apart by a distance d of between 0.1 mm and 0.5 mm.

[0147] Machine 1 is configured to allow circulation of the cooling fluid between the layers of wire 106 in shell 9. The fluid follows a spiral path formed by the wound wire 106, as shown in Figure 6.

[0148] The flattened wire 106 is wound around the corresponding tooth 20 by being curved around a straight line parallel to the largest dimension of the cross-section of the wire 106. The flattened wire 106 is wound around the corresponding tooth 20 without being curved around the thickness of the cross-section of the wire 106. The wire 106 is wound on itself around the tooth 20 along an axial axis of the tooth, the axial axis of the tooth 20 extending parallel to the axis of rotation X of the machine.

[0149] Each shell 9 contains a tooth 20. Each shell 9 has an inlet tube 12 for the cooling fluid and an outlet tube 18 for the cooling fluid, as illustrated in Figure 4.

[0150] The tooth 20 has a groove 109, illustrated in Figure 5 and Figure 6, in which the cooling fluid discharge tube 18 is housed.

[0151] The inlet tube 12 and the discharge tube 18 of the shell 9 are configured to ensure the electrical connection of the corresponding coil 100. The inlet tube 12 and the discharge tube 18 have in this example a shape similar to each other, as illustrated in FIGS. 8 and 9. Said shape is hollow, forming a cylinder of revolution 108a and 108b, respectively for the inlet 12 and discharge 18 tubes. In cross section, the shape is substantially circular. The inlet tube 12 and the discharge tube 18 respectively comprise a bottom 115a and 115b.

[0152] The inlet tube 12, illustrated in Figure 8, has a single slot 112. Said slot is closer to the closed circular end of the inlet tube 12. The open and closed circular ends of the inlet tube are arranged opposite each other with respect to a longitudinal axis of the inlet tube 12.

[0153] The slot 112 of the inlet tube 12 serves as an inlet to a chamber 102 provided in the shell. The slot 102 of the discharge tube 18 serves as an outlet from the chamber. Each chamber 102 provided in the shell 9 houses a flattened wire 106 wound on itself. The open circular end of the discharge tube 18 serves as an outlet from the corresponding chamber. The discharge tube 18, illustrated in Figure 9, has a single slot 111. Said slot 111 is closer to the closed circular end of the discharge tube 18. The open and closed circular ends of the discharge tube are arranged opposite each other with respect to a longitudinal axis of the discharge tube 18.

[0154] The slot of the inlet tube 12 serves as an inlet to the chamber 102 provided in the shell 9. The slot 111 of the discharge tube 18 serves as an outlet to the chamber 102 provided in the shell 9. The open circular end of the discharge tube 13 serves as an outlet from the corresponding tube.

[0155] The inlet tube 12 and the outlet tube 18 have the dual function of circulating the cooling fluid as well as establishing the electrical connection of the coil. The electric current flows from the current inlet 104 to the current outlet 103, through the wound coil 100, as illustrated in Figure 7.

[0156] Two consecutive layers of flattened wire 106 are spaced apart by a spacer member 120, different possible variants of which are illustrated in Figures 10 to 13. In the embodiment of Figure 10, the spacer member 120 comprises a plurality of pellets 123. The pellets 123 are arranged between the layers of wire 106. All of the pellets have a thickness Ea of approximately 0.2 mm.

[0157] According to a second embodiment illustrated in Figure 11, the spacer member 120 comprises a plurality of bars 121. A bar 121 is parallelepipedal in shape. The bars 121 are much longer than they are wide. They define large faces and small faces. They extend from a face of the corresponding shell 9 between the layers of wire 106, perpendicular to the direction of elongation of the wire 106. They are fixed to the wire 106 by a large face.

[0158] According to a third embodiment illustrated in Figure 12, the spacing member 120 comprises a plurality of bars 122. The bars 122 are of different sizes than the bars 121. In an exemplary embodiment not shown, the bars 122 may be of the same size as the bars 121. They are placed at different heights of the wire 106 and are fixed to the wire 106 in the direction of elongation of said wire 106.

[0159] The spacer member 120 comprises a plurality of bars or pads depending on the chosen embodiment. The spacer member 120 is arranged by gluing on one face of the wire 106. It is glued on the largest dimension of the cross-section of said wire 106.

[0160] The pads or bars are positioned on curved portions of the wire 106 and straight portions of the wire 106. They are arranged on a given wire 106 at regular intervals. An interval between two consecutive pads or bars on a given wire is a non-zero distance D. They are also distributed at different heights of the wire 106, as illustrated in Figures 10 and 12.

[0161] A second embodiment of the invention is illustrated in more detail in Figures 13 to 21. In this example, the machine 1 comprises a single stator 2 and two rotors 4.

[0162] In this embodiment, the coil 100, illustrated in detail in FIG. 13, comprises two concentrated wires 106, superimposed on one another along the axial axis of the tooth 20.

[0163] The shell 9, illustrated in figure 14, has two air gap walls 11. Each air gap wall has a hole 19 allowing the passage of the inlet tube 12 and the discharge tube 18.

[0164] According to this embodiment, the coil 100 comprises two wires 106 stacked on top of each other along the axial axis of the tooth 20, as illustrated in Figures 15 and 16. The two wires 106 are superimposed along the axial axis of the tooth 20, around the same tooth 20 while being wound on themselves in opposite directions of rotation. The two wires 106 of the same coil 100 are separated in the corresponding shell 9 by a separating wall 21. The separating wall is made in this example in a single piece with the peripheral wall 17, as illustrated in Figures 13 and 16. In addition, the two air gap walls 11 are identical to each other.

[0165] The separating wall 21 makes it possible to separate two chambers 102. Each chamber 102 houses a wire 106 from the coil.

[0166] The coil 100, formed of the two wires 106, comprises an inlet tube 12 shown in Figure 18. The inlet tube has a single slot 112. The coil 100 also comprises an evacuation tube 18, shown in Figure 19, having a single slot 111.

[0167] The inlet tube 12 and the discharge tube 18 have a shape similar to each other. Said shape is hollow, cylindrical in shape, forming a cylinder of revolution respectively 138a and 138b. In cross section, the shape is substantially circular.

[0168] The connection element 113 between the two wires 106 is rectangular in shape and does not have a slot, as illustrated in Figure 20. The connection element 113 provides the electrical connection between the two wires. According to this embodiment, the connection element 113 is inserted into an orifice 130 provided in the separation wall 21. The connection element 113 provides the fluid connection. It is made of copper. The orifice 130 provides the fluid connection between the two chambers, as illustrated in Figure 20.

[0169] Another example embodiment of the invention has also been illustrated with reference to Figures 21 to 24.

[0170] The shell 9, illustrated in Figures 21 and 22, comprises three separate parts: two half-shells 17a and 17b and a separating wall 21. According to this embodiment, the shell 9 is not in one piece. A seal 13 is arranged between the two half-shells 17a and 17b. The two half-shells 17a and 17b are assembled together in a sealed manner. The closure of the two half-shells 17a and 17b on each other is achieved with good sealing.

[0171] According to this embodiment, the connecting element between the two wires is a connecting tube 113, illustrated in Figure 23. The shape of the connecting tube 113 is hollow, cylindrical. In cross-section, its shape is substantially square. According to an alternative embodiment not shown, the shape of the connecting tube could be substantially round in cross-section. The connecting tube 113 has two slots, namely a first slot 114a and a second slot 114b. The first slot 114a is closer to one end of the connecting tube 113. The second slot 114b is closer to the opposite end of the connecting tube 113.

[0172] The first and second slots 114a and 114b are arranged opposite each other with respect to a cross-section of the connection tube 113. The first and second slots 114a and 114b are arranged opposite each other with respect to a longitudinal axis of the connection tube 113. According to an alternative embodiment not shown, the first and second slots can be arranged on the same face of the connection tube.

[0173] The first slot 114a of the connecting tube 113 serves as an outlet to a first chamber 102 provided in the shell 9. The second slot 114b of the connecting tube 113 serves as an inlet to a second chamber 102 provided in the shell 9.

[0174] The connecting tube 113 allows the circulation of the cooling fluid between the two chambers 102.

[0175] According to this same embodiment, the machine 1 comprises an inlet tube 12 and an outlet tube 18, each respectively comprising a single slot, which are similar to the inlet and outlet tubes illustrated in figures 8 and 9.

[0176] When the coil 100 comprises two wires 106, the input 104 allowing the arrival of the current and the output 103 of the current in the concentrated coils are located on the external diameter of the stator 2.

[0177] The current inlet 104 and outlet 103 as well as the cooling fluid inlet and recovery are located on the external diameter of the stator 2.

[0178] The electric current flows in the same direction in both wires, as shown in Figure 24.

Claims

Claims 1. Axial flux rotating electrical machine (1), comprising at least one stator (2) and at least one rotor (4), arranged along the axis of rotation (X) of the machine, the stator (2) being cooled by a circulation of a cooling fluid, the stator (2) comprising a plurality of teeth (20), at least one tooth (20), or even each tooth (20), carrying a coil (100) wound concentrically around said tooth (20), the coil (100) comprising at least one flattened wire (106) wound on itself around the corresponding tooth (20) in a plurality of layers, two consecutive layers of flattened wire (106) being spaced apart by a non-zero distance d, the stator (2) comprising at least one shell, in particular a plurality of shells (9), the shell, in particular each shell (9), housing at least one coil (100) wound around said tooth (20), the machine (1) being configured to allow circulation of the cooling fluid between the layers of wire (106) in the shell (9).

2. Machine according to the preceding claim, the flattened wire (106) being wound around the corresponding tooth (20) while being curved parallel to the largest dimension of the cross-section of the wire (106).

3. Machine according to any one of the preceding claims, two consecutive layers of flattened wire (106) being spaced apart by a distance d of between 0.05 mm and 1 mm, preferably between 0.08 mm and 0.9 mm, better still between 0.1 mm and 0.5 mm.

4. Machine according to any one of the preceding claims, two consecutive layers of flattened wire (106) being spaced apart by a spacing member (120), comprising in particular a plurality of pellets (123) arranged between the layers of wire.

5. Machine according to any one of the preceding claims, a shell (9) housing a single tooth (20).

6. Machine according to any one of the preceding claims, the shell (9) comprising an inlet tube (12) for the cooling fluid and an evacuation tube (18) for the cooling fluid.

7. Machine according to the preceding claim, the inlet tube (12) and the discharge tube (18) of the shell (9) being configured to ensure the electrical connection of the corresponding coil (100).

8. Machine according to any one of the preceding claims, the coil (100) comprising at least two wires (106), in particular two wires (106), preferably superimposed on one another.

9. Machine according to the preceding claim, the two wires (106) of the same coil (100) being separated in the corresponding shell by a separating wall (21).

10. Machine according to the preceding claim, the machine comprising a connection tube (113) allowing the fluid connection between two chambers (102) separated by the separation wall.

11. Machine according to the preceding claim, the connection tube (113) ensuring the electrical connection between the two wires (106).

12. Machine according to claim 9, the machine comprising an orifice (130) provided in the separating wall (21) allowing fluid connection between two chambers (102) separated by the separating wall.

13. Machine according to any one of claims 8 to 12, the input (104) and the output (103) of the current in the concentrated coils being located on the outer diameter of the stator (2).

14. Machine according to any one of the preceding claims, in which the teeth (20) of the stator (2) are each of a substantially prismatic general shape, in particular substantially triangular.

15. Machine according to any one of the preceding claims, comprising at least two rotors (4) arranged on either side of the stator (2) along the axis of rotation (X) of the machine (1).

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