Electric machine with direct cooling of radial passages in the stator body

Abstract

The invention relates to an electrical machine comprising a stator, a housing (4), and two flanges (5), the two flanges (5) being arranged respectively at the longitudinal ends of the housing, said stator (3) comprising a stator body (8) and coils (6), the stator body (8) comprising a multitude of radial passages arranged circumferentially and extending along the entire length of the stator body (8) for the passage of the coils (6) in the radial passages. Furthermore, the electrical machine comprises at least one thermal guide in at least one radial passage, the thermal guide comprising a plate (21) extending along the entire longitudinal length of the stator body (8) and oriented substantially radially, and two extensions (22) fixed longitudinally on either side of the plate, at the level of the outer radial periphery of the plate (21), the extensions (22) being in contact with the housing and / or the flanges. Figure 2 to be published

Description

Title of the invention: Electric machine with direct cooling of radial passages in the stator body Technical field

[0001] The present invention relates to the field of electrical machines and in particular the cooling of these electrical machines which can operate as an electric motor or as an electric generator. The electrical machines of the invention can in particular be used as an electric motor in transport applications (automobile for example).

[0002] The invention can in particular be used for a synchronous-reluctant electric machine, assisted or not by permanent magnets, but can also be applied to other types of electric machines, such as synchronous or asynchronous machines.

[0003] An electrical machine conventionally comprises a fixed part, the stator, and a rotating part, the rotor, arranged substantially coaxially within each other. The rotor is generally housed inside the stator which carries electrical windings generating a magnetic field enabling the rotor to be driven in rotation (operation as an electric motor). The stator generally comprises a stator body and coils which at least partially surround the stator body.

[0004] During their operation, electrical machines heat up due to electromagnetic losses (Joule effect losses and iron losses) and mechanical losses. This heating impairs their operation and leads to a degradation of their performance. For example, if the stator is not cooled (or not sufficiently cooled), the temperature of the winding increases, which can lead to a decrease in the electrical conductivity of the copper constituting the coils and a reduction in the life of the winding. Thus, a significant proportion of losses in electrical machines (~20 to 30% for machines commonly found on the market and up to 70% on short machines) are joule losses in the copper or aluminum windings positioned at the stator. These losses reduce the performance of the machines by limiting the maximum temperature of the materials, whether for peak power operation or continuous operation.

[0005] As the electrical resistance of copper increases with temperature, there is also a loss of efficiency and an increase in losses in the form of heat. The various electromagnetic components of an electrical machine, as well as certain insulating materials used in the parts of the electrical machine, are thus sensitive to heating produced during operation, and their cooling is essential. to dissipate the heat produced, in order to maintain good machine efficiency, ensure repeatability of its performance, extend its lifespan and limit maintenance.

[0006] The search for efficient cooling is therefore a major concern for manufacturers and integrators of electrical machines. Prior art

[0007] In the conventional cooling system of electric motors, the liquid circulates in a "jacket" in contact with the stator and the heat flow passes by conduction / convection from close to the copper, to the stator iron then to the jacket before ending by convection in the heat transfer liquid. In addition, an electrical and thermal insulator is generally placed in the notch of the stator to avoid damaging the copper insulation in contact with the iron. This electrical and thermal insulator generates an additional thermal resistance between the copper and the iron.

[0008] This solution cools the stator well thanks to the solid contact between the stator and the sleeve, but the coils located in the stator slots are essentially in contact with the internal air of the machine, which does not allow the heat from the coils to be easily evacuated. This creates hot spots limiting both:

[0009] - The efficiency (because the losses evolve with the temperature of the copper);

[0010] - The torque density generated by the machine by limiting the density of surface current in the notches.

[0011] One variant is the circulation of the heat transfer fluid in channels in the stator body, thus eliminating the jacket. This variant is described in particular in patent application FR 21 / 07,709. However, the heat transfer fluid circulates within a tube inserted in the stator body and the wall of this tube creates a thermal resistance. In addition, the core of the notch remains a heat concentration zone. The core of the notch can be defined by copper conductors.

[0012] Direct oil cooling (dripping or jet) is an effective solution for removing heat, particularly in the jet impact zones, which mainly concern the coil heads. However, this solution does not allow the heat to be removed from the coils evenly at the notches because the oil cannot or can hardly reach this zone. Indeed, the cooling is significant at the level of the impact of the oil on the conductors, but it is low far from the impact zone.

[0013] Finally, such oil cooling requires a pumping and exchange system with the ambient environment, which is therefore complex and expensive.

[0014] Michael Galea, Chris Gerada, Tsarafidy Raminosoa, and Patrick Wheeler, 2012. A Thermal Improvement Technique for the Phase Windings of Electrical Machines. IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 48, NO. 1, JANUARY / FEBRUARY 2012 describes a cooling solution in the stator slot ("heat path"). This solution consists of introducing a thermal conductor element into the slot so as to conduct the heat from the core of the slot to the magnetic iron of the stator body. However, the thermal performance of this solution depends mainly on the quality of contact of the conductor with the bottom of the slot or any other part of the slot. As soon as the contact resistance due to the implementation appears, the gain obtained becomes negligible. However, the quality of this contact is difficult to implement because it requires precise positioning and maintaining "pressure" for the contact while the coils are positioned in this space.Furthermore, in this solution, the heat is evacuated from the core of the slot through the conductive element, then through the stator body by contact between the conductive element and the stator body (poor quality contact by nature as explained previously), then by contact between the stator body and the external jacket and finally by the heat transfer fluid. However, the iron of the stator body is not a good thermal conductor. Therefore, the cooling of the core of the slot is not satisfactory in this solution. In addition, its implementation is complex.

[0015] The technical problem that we wish to solve consists of improving the evacuation of heat by capturing it as close as possible to the coils and in particular at the heart of the notch, in the notches of the stator body, to improve the energy efficiency of the machine and increase its service life, and so as to increase the mass torque density of the machine at a lower cost compared to more complex existing solutions. Summary of the invention

[0016] The invention relates to an electrical machine comprising a stator extending along a longitudinal axis, a casing and two flanges, said two flanges being arranged respectively at the longitudinal ends of said casing and forming with said casing an outer envelope of said electrical machine, said stator comprising a stator body and coils, the stator body comprising a multiplicity of radial passages arranged circumferentially and extending over the entire longitudinal length of the stator body for the passage of the coils in the radial passages.In addition, the electrical machine comprises at least one thermal guide in at least one radial passage, the thermal guide comprising a plate extending over the entire longitudinal length of the stator body and oriented substantially radially, and two extensions fixed longitudinally on either side of the plate, at the level of the external radial periphery of the plate, the extensions being in contact with the casing and / or the end plates.

[0017] Preferably, each radial passage has a radial axis of symmetry, and the plate is positioned on the axis of symmetry of the radial passage in which the thermal guide is positioned.

[0018] Advantageously, the extensions extend first longitudinally starting from the plate, then radially towards the casing and then longitudinally, to come into longitudinal contact with the casing, so as to form an “S” or a “C”.

[0019] According to an advantageous configuration of the invention, the thermal guide comprises a solid part fixed to the external radial end of the plate and to the extensions.

[0020] Advantageously, the solid part and the extensions form a single piece.

[0021] According to a variant, said single part is a tube capable of circulating a heat transfer fluid, the tube being connected to the casing and / or to the flanges by sealing means and / or by being embedded in a coating material, such as a resin.

[0022] According to one embodiment of the invention, the plate comprises a part wound on itself at the level of the external radial end, the part wound on itself then cut forming the solid part.

[0023] Preferably, the extensions each consist of a longitudinal extension of the part wound on itself, each extension preferably being flattened at the level of contact with the casing or the flange.

[0024] According to one implementation, the stator body comprises a notch at the external radial surface of the radial passage, said notch being configured to receive said solid portion.

[0025] Advantageously, the plate is of constant thickness or of increasing thickness from the internal radial end to the external radial end.

[0026] Preferably, the thermal guide comprises a material with a thermal conductivity greater than the material of the stator body, preferably comprising aluminum or copper.

[0027] Preferably, the extensions are fixed by welding, screws and / or rivets to the casing or flange.

[0028] According to one embodiment, the electrical machine comprises a hooped or screwed ring at each longitudinal end of the stator body, each extension being positioned between the hooped or screwed ring and the casing.

[0029] Preferably, the electric machine comprises at least one thermal guide in each radial passage, preferably the electric machine comprises several thermal guides in each radial passage. List of figures

[0030] Other characteristics and advantages of the electrical machine according to the invention will appear on reading the following description of non-limiting examples of rea- lizations, with reference to the figures attached and described below. [Fig 1]

[0031] [Fig.l] represents a first view in a plane orthogonal to the longitudinal axis of an electrical machine according to the invention. [Fig Ibis]

[0032] [Fig.1bis] represents a variant of [Fig.1] of an electric machine according to the invention. [Fig 2]

[0033] [Fig.2] represents a view in a longitudinal plane of a first variant of electric machine according to the invention. [Fig 3]

[0034] [Fig. 3] represents a view in a longitudinal plane of a second variant of electric machine according to the invention. [Fig 4]

[0035] [Fig.4] represents a view in a longitudinal plane of a third variant of electric machine according to the invention. [Fig 5]

[0036] [Fig.5] represents a first embodiment of a thermal guide of an electric machine according to the invention. [Fig 6]

[0037] [Fig.6] represents a second embodiment of a thermal guide of a electric machine according to the invention. [Fig 7]

[0038] [Fig.7] represents a third embodiment of a thermal guide of an electric machine according to the invention. [Fig 8]

[0039] [Fig.8] represents the thermal guide housed in the radial passage with a notch according to the invention. [Fig 9]

[0040] [Fig.9] represents a fourth embodiment of a thermal guide of an electric machine according to the invention. Description of the embodiments

[0041] The term "plate" or "lamella" means a part whose length in one dimension is much less (for example less than a third) than the length in the other dimensions of this part. The length of this dimension is generally the thickness which is less than the length and the width of the part. It may be, for example, at least one solid sheet of material or at least one sheet of material including openings (holes).

[0042] The plate can be flat or not flat, it can then be wavy or bumpy for example.

[0043] By "solid part" is meant that the part concerned is of greater dimension (the dimension being the thickness of this part, in the same direction as the thickness of the plate, or the external diameter of this part when this part is a wire, a cable or a tube) than the thickness of the plate. It thus locally comprises a greater quantity of material.

[0044] By “longitudinal plane” is meant a plane comprising the longitudinal axis of the electrical machine

[0045] The invention relates to an electrical machine comprising a stator extending along a longitudinal axis. The electrical machine may also comprise a rotor, the stator and the rotor preferably being coaxial, the rotor being able to rotate around the longitudinal axis and the stator preferably surrounding the rotor. The electrical machine also comprises a casing (also called a "liner") and two flanges (which generally carry the rotor bearings). The two flanges are arranged respectively at the longitudinal ends of the casing and form with the casing an outer casing of the electrical machine. The casing and / or the flanges may in particular be made of aluminum or an aluminum alloy. This outer casing serves as protection for the stator and possibly the rotor which are located inside this outer casing.In addition, this outer casing can be used for cooling the electrical machine, by convection with the ambient outside air or by the circulation of a heat transfer fluid in and / or around the outer casing (in and / or around the casing and / or the end plates).

[0046] The stator comprises a stator body and coils, the stator body comprising a multiplicity of radial passages in longitudinal view (also called notches). These radial passages are arranged circumferentially on the stator body, preferably being regularly distributed over the circumference of the stator body, and extend over the entire longitudinal length of the stator body. In other words, the radial passages pass completely through the stator body to allow the passage of the coils in these radial passages. The radial passages thus constitute openings extending substantially in the radial direction, in the stator body.

[0047] Furthermore, the electrical machine comprises at least one thermal guide in at least one radial passage. The purpose of this thermal guide is to capture the heat generated by the coils, and in particular from the core of the notch which is the area furthest from the cold source, in order to evacuate it towards one of the cold sources. Thus, the heat is better evacuated, and the electrical resistance of the copper linked to the increase in temperature temperature is reduced. This allows the torque density generated by the electric machine to be increased and its efficiency to be increased.

[0048] According to the invention, the thermal guide comprises a plate extending over the entire longitudinal length of the stator body and oriented substantially radially, preferably over at least the entire radial height of the radial passages. Thus, the plate is of the largest possible dimension in the radial passages, which makes it possible to better capture the heat induced in the radial passages. In addition, the thermal guide comprises at least one and preferably two extensions fixed to the plate or forming part of the plate, and extending longitudinally at least from their fixing at the plate. The fixing of each extension with the plate is at the external radial periphery of each longitudinal end of the plate.Thus, the extensions extend from the outer radial end of the plate, at least longitudinally in the direction away from the stator body (towards each end plate), from each longitudinal end of the plate.

[0049] Preferably, the radial height (length along the radial direction) of the plate may be greater than the radial height of the radial passages, so that the plate protrudes from the radial passages towards the center of the stator, at least at the time of winding the stator and can be cut at the internal diameter of the stator once the winding is finished. Thus, the conductive elements of the coils can be inserted on either side of the plate without encountering sharp parts of the plate (end closest to the longitudinal axis in particular). Once the winding is finished, the plate can then be cut at the internal diameter of the stator.

[0050] Alternatively or additionally, the plate may comprise a rounded inner end. In other words, the end closest to the longitudinal axis may be rounded. This rounded inner end may be substantially set back from the inner diameter of the stator because the radial passage has a shape that closes at the inner diameter.

[0051] In addition, the extensions are in contact with the casing and / or the flanges. Thus, the thermal guide can capture the heat in the relevant radial passage, thanks to the plate. The heat is then conducted, from the plate to the extensions, on each side of the stator body, by thermal conduction. Then, the heat is conducted from the extensions to the outer casing via the casing and / or the flanges.

[0052] Unlike the prior art "heat path" mentioned, the contact between the extensions and the casing and / or the flanges can be much more easily controlled outside the stator body than the contact between the thermal guide in the radial passages and the stator body, due to the mounting of the coils in these radial passages. Thus, the implementation of the invention is simple and reproducible. In addition, the heat transfer can go directly from the thermal guide (which is a better thermal conductor than the rolled iron of the stator body) to the outer casing, bypassing the stator body, whose iron is a poor thermal conductor. Thus, in addition to simplifying assembly and improving contact, heat transfer is improved by reducing thermal resistance.

[0053] The invention thus consists of a simple and passive means for removing heat from the core of the radial passage, while being removable and recyclable. With the invention, the temperature in the radial passages can be reduced by at least 30°C. In addition, the invention can operate without a liquid pumping system, for example with air cooling of the engine.

[0054] Cooling of the outer casing may then include cooling by convection, natural or forced, with the ambient air of the casing and / or the flanges.

[0055] Cooling of the outer casing can also be ensured by channels for circulating a heat transfer fluid in the casing and / or in the end plates. This circulation makes it possible to improve the cooling of the machine. The heat transfer fluid can be, for example, water, glycol, glycolated water, a dielectric fluid or oil.

[0056] The electrical machine can operate (or be capable of operating) both as an electrical generator (it generates electricity from a rotational movement originating from the rotor, for example) and as an electric motor (it then generates a rotation of the rotor, for example, from electricity).

[0057] According to a variant, the electric machine may comprise several thermal guides as described previously (plate with extensions on each side, the extensions being in contact with the casing and / or the flange) in the same radial passage. The use of several thermal guides in the same radial passage makes it possible to improve the evacuation of heat.

[0058] Alternatively or additionally, the electrical machine may comprise at least one thermal guide (plate with extensions on each side, the extensions being in contact with the casing and / or the flange), and preferably several thermal guides, in each radial passage. Thanks to at least one thermal guide in each radial passage, it is easy to recover the heat in the stator body, within the radial passages themselves and thus limits the temperature rise of the coils, and this in a homogeneous manner over the circumference of the stator body, making it possible to improve the service life of the machine and its efficiency.

[0059] Preferably, each radial passage may have a radial axis of symmetry and the plate may advantageously be positioned on the axis of symmetry of the radial passage in which the thermal guide is positioned. Thus, the thermal guide is located at the center of the radial passage, which allows better temperature capture and a homogeneous temperature in the radial passage on either side of the thermal guide.

[0060] Advantageously, the plate may comprise at least one flat portion, extending radially. By flat portion, it is meant that the plate extends between the surfaces separated by the thickness of the plate (i.e. the smallest dimension of the plate) are flat and preferably parallel to each other (the plate therefore has a constant thickness). As a result, the production is simple.

[0061] Furthermore, the plate may have a thickness of between 0.1 mm and 1.5 mm, preferably between 0.1 mm and 0.9 mm. These thicknesses are sufficiently small so as not to unnecessarily hinder the space available in the radial passage and thus have sufficient space for the winding, and they are sufficiently thick to ensure sufficient heat conduction.

[0062] Advantageously, the extensions may each comprise a flattened (flat) area at the contact surface with the casing and / or the end plates so as to provide a contact surface and therefore heat exchange while minimizing thermal resistance. For example, the flattened (flat) extensions may be screwed or riveted to the casing directly or held in place by a screwed or shrink-fitted conical ring, the conical ring thus being able to press the extensions against the casing or the end plate, or they may be welded by a welding tool. This solution is compatible with manual disassembly of the stator by cutting the flattened extensions with pliers when the flattened extensions are welded and under pressure for automated disassembly.

[0063] Thus, assembly and disassembly are compatible with mass production, maintenance operations or separation of materials during a machine recycling process.

[0064] According to a configuration of the invention, the extensions can extend, from their attachment to the plate, first longitudinally in the direction opposite the stator body (towards the flange closest to this end), then radially in the direction of the casing and then longitudinally, to come into longitudinal contact with the casing. This configuration makes it possible to bring the extension into contact with the casing, while the external radial periphery of the radial passages is on a diameter strictly smaller than the internal diameter of the casing.The extension can then form substantially an "S" (having substantially the shape of a staircase step) when the two longitudinally extending parts are directed in the same direction or form substantially a "C" when the two longitudinally extending parts are directed in opposite directions, the first (that starting from the attachment with the plate) in the opposite direction to the stator body (towards the nearest flange) and the second (that located after the radially extending part) towards the stator body, in . starting from the end fixed to the radial part.

[0065] According to one implementation, the plate may be fixed, for example by welding, to a wire which extends over the entire longitudinal length of the plate and protrudes on each side of each longitudinal end of the plate so as to form the extensions.

[0066] Preferably, the wire may have a diameter at least equal to the thickness of the plate at the level of its attachment to the plate, preferably greater than the thickness of the plate at the level of its attachment to the plate, so as to facilitate the evacuation of heat.

[0067] Advantageously, the thermal guide may comprise a solid part fixed to the external radial end of the plate and to the extensions. This solid part has a dimension (width) greater than the thickness of the plate, taken in the same direction as the plate thickness. This solid part makes it possible to better recover the heat from the plate to evacuate it with less thermal resistance.

[0068] This massive part extends over the entire length of the plate, that is to say over the entire length of the stator body, in the longitudinal direction.

[0069] The solid part can thus comprise a wire as described previously whose diameter is greater (preferably strictly greater) than the thickness of the plate.

[0070] Preferably, the solid part and the extensions can form a single piece. Thus, they are produced together, which simplifies their manufacture. In addition, the extensions can then be of the same section as the solid part, which makes it possible to efficiently conduct heat to the outer casing, the extensions then being solid with a width or diameter greater, preferably strictly, than the thickness of the heat guide plate.

[0071] According to a first variant, the single part forming the solid part and the extensions may be a tube suitable for the circulation of a heat transfer fluid. Thus, the single part is then fixed to the plate, for example by welding. The tube extends over the entire length of the stator body and protrudes from each side of the stator body to form the extensions.

[0072] If the tube is in contact with the casing, it can in particular form an “S” or a “C” or a free shape making it possible to reach the casing as explained previously at the level of the extensions.

[0073] If the tube is in contact with the flanges, it can be a straight tube, extending only in the longitudinal direction. Thus, it is simpler to produce.

[0074] By using the tube as a solid part and as extensions and by using a heat transfer fluid, the temperature in the radial passages can be reduced by more than 30°C.

[0075] In this first variant, the tube can be connected to the casing and / or to the flanges by sealing means. Thus, it is possible to circulate a heat transfer fluid, such as a liquid or gas, into the tube in order to cool the radial passages even more efficiently by shortening the path between the heat source (the conductors in the notch) and the cold source (the heat transfer fluid). The heat transfer fluid can arrive through the casing and / or through the end plates via a cooling channel integrated into the casing and / or the end plates. The sealing means can in particular be seals compatible with the heat transfer fluid used and with the maximum temperature of the machine.

[0076] Alternatively, for this first variant, the tube can be connected to the casing and / or to the end plates by being embedded in a coating material, such as a thermally conductive resin. The combination of the use of the resin and a tube which allows the circulation of the fluid within the radial passages themselves, allows for improved cooling of the machine. The coating material can in particular also embed the coil heads (which protrude from the stator body at each longitudinal end) which also represent hot spots on the machine. Thus, it is possible to circulate a heat transfer fluid, such as a liquid or a gas, in the tube in order to cool the radial passages and the coating material even more effectively. The heat transfer fluid can arrive via the casing and / or via the end plates via a cooling channel integrated into the casing and / or the end plates.

[0077] In this first variant, the coating material can be limited to the level of the coil heads (and not be placed in the radial passages). Indeed, the presence of the thermal guide makes it possible to recover the heat sufficiently efficiently without the need for a coating material in the radial passages. By using a coating material only around the coil heads, the implementation of the coating material is simpler, less time-consuming and therefore less expensive. On the contrary, for the solutions of the prior art, it is necessary to make the resin penetrate around the conductors inside the radial passages, over their entire axial length in order to ensure good heat recovery. This installation requires specific equipment and is more complex and time-consuming and therefore more expensive.

[0078] For this first variant, the tube may comprise at least one portion which is inserted into a bore of the flange or the casing, with for example a sealing means between the tube and the bore of the flange or the casing. This solution allows disassembly while ensuring good contact between the tube and the casing or the flange, good holding in position and good heat conduction.

[0079] According to a second variant of the invention, the plate may comprise a part wound on itself at the external radial end, the part wound on itself and then cut forming the solid part. Indeed, the part wound on itself, thanks to the winding, forms a part whose width is greater than the thickness of the plate itself. Thus, it forms a solid part. This solution is particularly interesting because it is simple to manufacture and does not require welding operations between the plate and the solid part.

[0080] Advantageously, for this second variant of the invention, the extensions can each consist of a longitudinal extension of the part rolled up on itself and then cut. Thus, the plate, the solid part and the extensions are produced in a single assembly, without welding. In addition, this manufacture is simple. In addition, each extension of the extensions can, preferably, comprise a flattened end at the contact with the casing or the flange. The flattened end facilitates and improves the contact between the extension and the casing or the flange, whether by welding, by clamping or by shrink fitting. This solution also facilitates production. Indeed, the flattened end being outside the notches, it is easier to ensure contact. In addition, thanks to the flattened end, the contact surface and therefore the heat exchange between these parts are increased.

[0081] According to a third variant, the single part forming the solid part and the extensions, can be a wire of diameter greater, preferably strictly, than that of the plate at the level of its attachment with the wire. Thus, the single part is then attached to the plate, for example by welding. The wire extends over the entire length of the stator body and protrudes on each side of the stator body to form the extensions.

[0082] If the wire is in contact with the casing, it can in particular form an “S” or a “C” or a free shape making it possible to reach the casing and / or flange as explained previously at the level of the extensions.

[0083] Advantageously, when the thermal guide comprises a solid part, the stator body may comprise a notch (a groove) at the level of the external radial surface of the radial passage, the notch (the groove) being configured to receive (accommodate) the solid part, to hold it for example during the winding of the coils around the stator body, and to guide it during the insertion of the thermal guide into the radial passage. By using this notch, the solid part of the thermal guide is positioned outside the radial passage and thus does not hinder the size of the radial passage intended for the passage of the coils. In addition, this notch allows the thermal guide to be placed more easily in the radial passages. Indeed, this notch can allow the thermal guide to be held in position in the radial passage at the time of winding the coils in the radial passages to form the stator.For this, the notch can be suitable for holding the massive part in position in this notch.

[0084] The notch can preferably be positioned on the axis of symmetry of the radial passage. Thus, the thermal guide can be positioned in the center of the radial passage, which allows a homogeneous temperature on both sides of the thermal guide.

[0085] According to one implementation of the invention, the plate may be of constant thickness, in particular for the variants where a part of the plate is rolled up on itself then cut.

[0086] Alternatively, the plate may be of increasing thickness from the inner radial end to the outer radial end. With increasing thickness, heat conduction is improved and guided to the outer radial end which serves as the solid portion (because the thickness is greater in this area). Heat is then conducted from this solid portion to the extensions on each side.

[0087] Preferably, the thermal guide may comprise a material with a thermal conductivity greater than the material of the stator body (which is preferably magnetic iron). Preferably, the thermal guide may comprise aluminum or copper, for example being made of aluminum or copper or an alloy of aluminum and / or copper. Thus, the heat is easily conducted to the casing or the end plates. In addition, the use of these materials allows the plate to be produced with a portion wound on itself and then cut, this type of winding being facilitated by the use of such materials.

[0088] According to one embodiment of the invention, the extensions can be fixed by welding to the casing or to the flange. Welding to the casing, when the thermal guide is made of aluminum for example, can be easily removed by using pliers for example. In addition, welding ensures good contact and therefore heat exchange by conduction.

[0089] According to another embodiment, the electrical machine may comprise a shrink-fit ring at each longitudinal end of the stator body, each extension of the thermal guide being positioned between the shrink-fit ring and the casing. As a result, the contact between the extension and the casing is of good quality and maintained thanks to the shrink-fit ring.

[0090] According to another embodiment, the electrical machine may comprise a screwed ring at each longitudinal end of the stator body, each extension of the thermal guide being positioned between the screwed ring and the casing. As a result, the contact between the extension and the casing is of good quality and maintained thanks to the screwed ring. For this, the screwed ring may comprise a threaded portion on the external diameter of the ring and the casing comprises a tapped portion in which the threaded portion of the screwed ring can engage and be screwed.

[0091] Advantageously, the solid part or the external radial periphery of the plate may be in contact with the stator body at the level of the radial external surface of the radial passage. This contact further improves cooling by allowing part of the heat to pass through the magnetic iron of the stator body to reach the casing.

[0092] Preferably, the massive part and / or the external radial periphery of the plate may be glued to the stator body at the level of the radial external surface of the radial passage so as to ensure good contact and to ensure its maintenance over time. Thus, cooling can be further improved and in a more durable manner.

[0093] [Fig.l] illustrates, in a schematic and non-limiting manner, an electric machine according to one embodiment of the invention.

[0094] This electrical machine comprises a coaxial rotor 2 and stator 3, with stator 3 surrounding rotor 2.

[0095] The stator 3 comprises a stator body 8 which comprises radial passages 10 (here twelve radial passages 10). The radial passages 10 correspond to openings (or notches), extending substantially radially from the internal surface of the stator body 8 (cylindrical internal surface), over the entire length of the stator body 8. The radial passages 10 therefore pass through the stator body longitudinally along the common axis of the stator 3 and the rotor 2.

[0096] These radial passages 10 allow the passage of the coils 6. Each radial passage 10 comprises coils 6.

[0097] Outside the stator body 8, there is a casing 4, preferably made of aluminum.

[0098] At least one of the radial passages 10 (preferably each radial passage 10) comprises a thermal guide comprising a plate 21 oriented substantially along the axis AA which is the axis of symmetry of the radial passage 10 concerned. This axis of symmetry AA is oriented radially.

[0099] At the radial outer periphery of the plate 21, there is a solid part 27 fixed to the plate 21. As shown, the solid part 27 is in contact with the outer radial surface 32 of the radial passage 10, for example, the solid part 27 can be glued to the outer radial surface 32.

[0100] [Fig. 1bis] illustrates, in a schematic and non-limiting manner, an electrical machine according to one embodiment of the invention.

[0101] In this figure, the references identical to those in [Fig.l] correspond to the same elements and will not be detailed again.

[0102] [Fig.1bis] differs from [Fig.1] in that the plate 21 comprises a rounded internal end 50 at the end closest to the longitudinal axis, so as to limit the risk of damage to the wires of conductive elements with the internal end, in particular at the time of winding, which could happen with a pointed internal end.

[0103] [Fig.2] illustrates, in a schematic and non-limiting manner, a partial view along a longitudinal plane passing through a notch (radial passage) of the stator of the electrical machine according to one embodiment.

[0104] The horizontal dashed line represents the longitudinal axis of the electrical machine of the longitudinal plane.

[0105] The electrical machine comprises a stator with a stator body 8 extending along the longitudinal axis. The stator body 8 comprises radial passages, which are openings in the stator body 8 to allow the passage of the stator coils. The coils have coil heads 7 which protrude at each longitudinal end 9a and 9b of the stator body 8.

[0106] The stator is placed in an outer casing which comprises a casing 4, preferably cylindrical, and two flanges 5 each located at a longitudinal end of the casing 4. The outer casing makes it possible, among other things, to protect the internal parts of the electrical machine.

[0107] The machine comprises a thermal guide in at least one radial passage of the stator body 8 (preferably in each radial passage of the stator body 8).

[0108] The thermal guide comprises a plate 21, extending radially and extending over the entire longitudinal length L of the stator body 8.

[0109] At the outer radial end 23 (end furthest from the longitudinal axis) of the plate 21, the thermal guide comprises a solid part 27, which may be a wire or a tube for example, fixed to the plate 21.

[0110] The thermal guide also comprises extensions 22 at each longitudinal end 9a and 9b of the stator body 8 (and therefore of the plate 21). These extensions 22 may be an extension of the solid part 27, or even of the plate 21, or be added parts.

[0111] As shown, the extensions 22 each form an S: starting from the plate 21, they first extend over a first part 24 longitudinally in the direction of the nearest flange 5, then they extend over a second part 25 radially in the direction of the casing 4 then over a third part 26 longitudinally in the direction of the flange 5 starting from the connection with the second part (but for this third part, they could be in the direction of the stator body and thus form a “C” instead of an “S”).

[0112] The third part 26 of the extensions is in contact with the internal surface of the casing. A hooped ring 31 is positioned on each of these third parts 26 to ensure contact between the extension 22 made up of parts 24 / 25 / 26 and the casing 11 and its maintenance over time.

[0113] To do this, the fretted ring 31 may have a conical part to facilitate positioning and contact with the extension 22 and a cylindrical part.

[0114] The hooped ring 31 could of course be replaced by a weld between the third part 26 of the extension and the casing 4 or by a screwed ring with a thread on its external diameter adapted to a tapping on the internal diameter of the casing, or a screw for clamping each extension 26 in the casing 4.

[0115] [Fig.3] illustrates, in a schematic and non-limiting manner, a partial view in a longitudinal plane passing through a notch (radial passage) of the stator of a second variant of electric machine according to the invention.

[0116] In this illustration, only one longitudinal side is shown. It is understood that the other end of the machine (flange, extension of the thermal guide in particular) is similar and symmetrical with respect to a plane orthogonal to the longitudinal axis.

[0117] The horizontal dot-dash line represents the longitudinal axis of the electrical machine 1.

[0118] The electrical machine 1 comprises a stator with a stator body 8 which comprises radial passages. At least one thermal guide is positioned in these radial passages (preferably at least one thermal guide in each radial passage).

[0119] The thermal guide comprises a plate 21 which extends radially over the entire length of the stator body 8.

[0120] At the outer radial end 23 of the plate 21, a solid part 27 is fixed to the plate 21. Then at each longitudinal end of the plate 21, there are extensions 22 which protrude from each side of the plate. These extensions 22 extend first longitudinally over a first part 24 then radially over a second part 25.

[0121] Here, the solid part 27 and the extensions 22 are formed by a hollow tube, capable of allowing a heat transfer fluid to circulate, allowing improved cooling of the radial passages and therefore of the coils.

[0122] The second part 25 extends radially until it can be inserted into a radial bore 35 of the casing 4. It can be welded to the casing 4 in this position or else the sealing can be ensured by sealing means, such as O-rings, placed between the tube and the bore 35.

[0123] The bore 35 opens into a cooling channel 34 in the casing. As shown, the cooling channel 34 is longitudinal. Thus, a heat transfer fluid can circulate in the cooling channel 34 of the casing and then in the thermal guide.

[0124] A coating material 28, such as a resin, may optionally be placed on each side of the stator body, once the machine is assembled to fill the space located between the internal surface 33 of the casing 4, the flange 5, the stator body 8 and the extension 22. The coating material 28 also coats the coil heads 7 located in this space.

[0125] As shown, the coating material 28 is in contact with the flange 5 but it might not be in contact with the flange 5.

[0126] [Fig.4] illustrates, in a schematic and non-limiting manner, a partial view in a longitudinal plane passing through a notch (radial passage) of the stator of a third variant of electrical machine according to the invention.

[0127] In this illustration, only one longitudinal side is shown. It is understood that the other end of the machine (flange, extension of the thermal guide in particular) is similar and symmetrical with respect to a plane orthogonal to the longitudinal axis.

[0128] The horizontal dashed line represents the longitudinal axis of the electrical machine 1.

[0129] The electrical machine 1 comprises a stator with a stator body 8 which comprises radial passages. At least one thermal guide is positioned in these radial passages (preferably at least one thermal guide in each radial passage).

[0130] The thermal guide comprises a plate 21 which extends radially over the entire length of the stator body 8.

[0131] At the outer radial end 23 of the plate 21, a solid part 27 is fixed to the plate 21. Then, at each longitudinal end of the plate 21 on the radial periphery of the plate 21, there are extensions 22 which protrude from each side of the plate. These extensions 22 extend longitudinally to the flange.

[0132] Here, the solid part 27 and the extensions 22 are formed by a straight hollow tube, capable of allowing a heat transfer fluid to circulate allowing improved cooling of the radial passages and therefore of the conductors in the notch.

[0133] Each extension 22 extends to the flange 5 so as to be able to be inserted into a longitudinal bore 35 of the flange 5. It can be fixed to the flange 5 (by screwing, riveting, shrink fitting or welding for example) in this position or else the seal can be ensured by sealing means, such as O-rings, placed between the tube and the bore 35.

[0134] The bore 35 opens into a cooling channel 34 of the flange. As shown, the cooling channel 34 is radial. Thus, a heat transfer fluid can circulate in the cooling channel 34 of the flange 5 and then in the thermal guide.

[0135] A coating material 28, such as a resin, may optionally be placed on each side of the stator body 8, once the machine is assembled to fill the space located between the internal surface 33 of the casing 4, the flange 5, the stator body 8 and the extension 22. The coating material 28 also coats the coil heads 7 located in this space.

[0136] As shown, the coating material 28 is in contact with the flange 5 but it might not be in contact with the flange 5.

[0137] [Fig.5] illustrates, in a schematic and non-limiting manner, a first embodiment of a thermal guide according to the invention.

[0138] The thermal guide 20 comprises a plate 21, advantageously flat to be placed radially in the radial passage of the stator body of the electrical machine.

[0139] The length L of the plate 21 corresponds substantially to the longitudinal length of the stator body 8 (and therefore to that of the radial passage).

[0140] At a radial (external) end of the plate 21, there is a massive part 27 whose length is equal to the length L of the plate 21.

[0141] The thermal guide 20 also comprises extensions 22, at each longitudinal end (along the length L) of the solid part and of the plate 21.

[0142] These extensions 22 extend first longitudinally over a first part 24, then radially in the direction of the casing (not visible in the figure) over a second part 25 then longitudinally in the direction of the nearest flange (not shown in the figure) over a third part 26. Thus, these extensions 22 form an “S”.

[0143] The third part 26 may comprise a flattened portion 37 so as to facilitate contact with the casing, in particular if a shrink-fit or screwed ring is used to maintain contact between the casing and the extension 22. This flattened portion 37 may also facilitate welding of the third part 26 to the casing 4.

[0144] The extensions 22 and / or the solid part 27 may comprise a wire, a cable, a tube or a plate wound on itself then cut.

[0145] [Fig.6] illustrates, in a schematic and non-limiting manner, a second embodiment of a thermal guide according to the invention.

[0146] The thermal guide 20 comprises a plate 21, advantageously flat to be placed radially in the radial passage.

[0147] The length L of the plate 21 corresponds substantially to the longitudinal length of the stator body 8 (and therefore to that of the radial passage).

[0148] At a radial (external) end of the plate 21, there is a massive part 27 whose length is equal to the length L of the plate 21.

[0149] The thermal guide 20 also comprises extensions 22, at each longitudinal end (along the length L) of the solid part 27 and of the plate 21.

[0150] The extensions 22 and the solid part 27 are produced by a plate rolled up on itself and then cut 29. Thus, the thermal guide can be produced in a single piece, namely a plate, which is rolled up on itself at one end to form the solid part 27 and the extensions 22 then a part of the flat plate is removed by machining or cutting at each end, so as to leave only the extensions 22.

[0151] [Fig.7] illustrates, in a schematic and non-limiting manner, a third embodiment of a thermal guide according to the invention.

[0152] The thermal guide 20 comprises a plate 21, advantageously flat to be placed radially in the radial passage.

[0153] The length L of the plate 21 corresponds substantially to the longitudinal length of the stator body 8 (and therefore to that of the radial passage).

[0154] At one radial (external) end of the plate 21, there is a massive part 27 whose length is equal to the length L of plate 21.

[0155] The thermal guide 20 also comprises extensions (not visible), at each longitudinal end (along the length L) of the solid part 27 and of the plate 21.

[0156] The solid part 27 is made by a plate wound on itself 29. Thus, the plate 21, which is wound on itself at one end, can form the solid part 27. The extensions can also be made by a wound plate (preferably the same one) or the extensions can be added, which can take the form of a wire or a piece of plate, for example by welding.

[0157] [Fig.8] illustrates, in a schematic and non-limiting manner, the thermal guide housed in the radial passage with a notch according to the invention.

[0158] In this figure, the radial passage 10 is shown with an axis of symmetry AA. The thermal guide comprises a flat plate 21 extending radially over the entire length of the stator body and a massive part 27 fixed to the external radial end of the plate 21.

[0159] The radial passage 10 comprises a notch (groove or groove for example) 30 on its external radial surface 32 so as to receive the solid part 27 of the thermal guide and thus to hold it in position more easily, for example during the operation of winding the coils, around the thermal guide in the radial passages 10.

[0160] For this, the notch 30 has a shape substantially identical to the shape of the solid part 27.

[0161] [Fig.9] represents a fourth embodiment of a thermal guide of an electric machine according to the invention.

[0162] In this variant, the thermal guide comprises a plate 21 whose thickness e is variable along the radial direction.

[0163] The thickness e of the plate 21 may be smallest at the inner radial end (closest to the longitudinal axis) of the plate 21 and increase, preferably linearly, up to the outer radial end (furthest from the longitudinal axis) of the plate 21. Thus, the plate is thicker at the outer radial end which thus forms a solid part 27.

[0164] Preferably, as shown, the end of the plate closest to the longitudinal axis is rounded so as not to damage the conductive elements of the coils when they are put in place.

[0165] Extensions 22 (only one is shown but it is understood that a second similar extension and preferably symmetrical along a plane orthogonal to the longitudinal axis of the machine can be positioned at the other longitudinal end of the plate 21) are then fixed to each longitudinal end of the plate 22, in extension of the solid part 27 to ensure contact by conduction thermal insulation of the solid part 27 to the casing or to the flange (not shown).

[0166] Of course, the invention is not limited to the embodiments illustrated but on the contrary embraces all variants without departing from the scope of the invention.

Claims

Claims

1. An electrical machine (1) comprising a stator extending along a longitudinal axis, a casing (4) and two flanges (5), said two flanges (5) being arranged respectively at the longitudinal ends of said casing (4) and forming with said casing (4) an outer casing of said electrical machine (1), said stator (3) comprising a stator body (8) and coils (6), the stator body (8) comprising a multiplicity of radial passages (10) arranged circumferentially and extending over the entire longitudinal length (L) of the stator body (8) for the passage of the coils (6) in the radial passages (10), characterized in that the electrical machine (1) comprises at least one thermal guide (20) in at least one radial passage (10), the thermal guide (20) comprising a plate (21) extending over the entire longitudinal length (L) of the stator body (8 ... plate (21) being arranged in a longitudinal direction relative to the radial passages (10) of the stator body (8), the plate (21) being arranged in a longitudinal direction relative to the radial passages (10) of the stator body (8), the plate (21) being arranged in a longitudinal direction relative to the radial passages (10) of the stator body (8), the plate (21) being arranged in a longitudinal direction relative to the radial passages (10) of the stator body (8), the plate (21) being arranged in a longitudinal direction relative to the radial passages (10) of the stator body (8), the plate (21) being arranged in a longitudinal direction relative to the radial passages stator (8) and oriented substantially radially,and two extensions (22) fixed longitudinally on either side of the plate (21), at the level of the external radial periphery (23) of the plate (21), the extensions (22) being in contact with the casing (4) and / or the flanges (5).,

2. An electrical machine (1) according to claim 1, wherein each radial passage (10) has a radial axis of symmetry (AA), and wherein the plate (21) is positioned on the axis of symmetry (AA) of the radial passage (10) in which the thermal guide (20) is positioned.

3. Electrical machine (1) according to one of the preceding claims, in which the extensions (22) extend first longitudinally starting from the plate (21), then radially towards the casing (4) then longitudinally, to come into longitudinal contact with the casing (4), so as to form an “S” or a “C”.

4. Electrical machine (1) according to one of the preceding claims, in which the thermal guide (20) comprises a solid part (27) fixed to the external radial end (23) of the plate (21) and to the extensions (22).

5. Electrical machine (1) according to claim 4, in which the solid part (27) and the extensions (22) form a single piece.

6. Electrical machine (1) according to claim 5, in which said single part is a tube suitable for the circulation of a heat transfer fluid, the tube being connected to the casing (4) and / or to the flanges (5) by sealing means and / or by being embedded in a coating material (28), such as than a resin.

7. Electrical machine (1) according to one of claims 4 or 5, in which the plate (21) comprises a part wound on itself (29) at the level of the external radial end (23), the part wound on itself (29) then cut forming the solid part (27).

8. Electrical machine (1) according to claim 7, in which the extensions (22) each consist of a longitudinal extension of the part wound on itself (29), each extension preferably being flattened (37) at the level of contact with the casing (4) or the flange (5).

9. Electrical machine (1) according to one of claims 4 to 8, wherein the stator body (8) comprises a notch (30) at the external radial surface (32) of the radial passage (10), said notch (30) being configured to receive said solid part (27).

10. Electrical machine (1) according to one of the preceding claims, in which the plate (21) is of constant thickness or of increasing thickness from the inner radial end to the outer radial end (23).

11. Electrical machine (1) according to one of the preceding claims, wherein the thermal guide (20) comprises a material of thermal conductivity greater than the material of the stator body (8), preferably comprising aluminum or copper.

12. Electrical machine (1) according to one of the preceding claims, in which the extensions (22) are fixed by welding, by screws and / or by rivets to the casing (4) or to the flange (5).

13. An electrical machine (1) according to any preceding claim, wherein the electrical machine (1) comprises a shrink-fit or screw-fit ring (31) at each longitudinal end of the stator body (8), each extension (22) being positioned between the shrink-fit or screw-fit ring (31) and the casing (4).

14. Electrical machine (1) according to one of the preceding claims, wherein the electrical machine (1) comprises at least one thermal guide (20) in each radial passage (10), preferably the electrical machine (1) comprises several thermal guides (20) in each radial passage (10).

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