Axial flux electric machine with cooling of the inter-tooth areas of the cylinder head

Abstract

The present invention relates to an axial flux electric machine comprising an outer casing (2) enclosing at least one stator and at least one rotor, each stator being a segmented stator comprising at least one yoke (1) and teeth (3) inserted into openings in the yoke (1), the teeth (3) projecting axially on either side of the yoke (1), the yoke (1) comprising inter-tooth zones (7) regularly distributed around the circumference of the yoke (1). Furthermore, the electric machine comprises at least one cooling fluid circuit with at least a portion of said circuit in contact with each inter-tooth zone (7) of the yoke, said portion of said cooling fluid circuit being positioned between the yoke (1) and the outer casing (2), said portion preferentially extending substantially radially. Figure 1 to be published

Description

Title of the invention: Axial flux electric machine with cooling of the inter-tooth areas of the cylinder head technical field

[0001] The invention relates to the field of axial flux electrical machines.

[0002] This type of axial flux electric machine can find applications in electric or hybrid vehicles, such as cars, buses, trucks, and construction equipment. This type of machine can also be used for stationary applications, such as industrial charging machines or electric generators. Previous technique

[0003] In recent decades, the development of electrical machines has focused primarily on radial flux electrical machines.

[0004] Radial flux electric machines generally comprise a coaxial rotor and stator, one surrounding the other. Thus, the magnetic flux can pass radially from the rotor to the stator and vice versa, via a radial air gap which is defined as the radial clearance between the rotor and the stator.

[0005] On the contrary, axial flux machines are characterized by at least one rotor and at least one stator arranged successively one behind the other in the axial direction (of the rotor's axis of rotation), such that the path of the magnetic flux between the rotor and the stator is axial. In other words, the rotor and the stator face each other and are separated by an air gap of axial thickness (or axial clearance between the rotor and the stator).

[0006] The rotor of axial flux permanent magnet electric machines generally comprises permanent magnets glued to the rotor yoke or inserted into a rotor body and, in this case, the permanent magnets are separated by radial arms from the rotor body.

[0007] The stator generally comprises a ferromagnetic stator body, which may or may not have teeth. The electrical winding in the stator slots may be distributed or concentric, i.e., each winding surrounds a tooth.

[0008] In the context of the development of high power and torque density machines for electric or hybrid traction, particularly for electric or hybrid vehicle applications, axial flux machine topology is among those with the highest potential, notably due to the significant axial space constraint. Axial flux electric machines are also of interest for stationary applications as well as for wind power applications.

[0009] In general, axial flux electrical machines allow higher power and torque densities than radial flux electrical machines due to their geometry.

[0010] This gain is generally achievable by increasing the number of pole pairs in the rotor, which implies an increase in the electrical frequency of the electrical and magnetic quantities, with in particular a negative impact on rotor losses (mainly losses in the magnets) due to space harmonics and electromagnetic effects and a negative impact on stator losses and in the coils.

[0011] The manufacturing of the stators for these machines is a crucial challenge for the development of axial flux electric machines. Stators, obtained by winding coils around teeth, present constraints related to the manufacturing of the yoke and teeth, as well as constraints related to winding the coils onto the teeth and closing the slots to hold the coils in position. For these reasons, segmented stators (particularly those with teeth attached to the stator yoke) represent a relevant approach for simplifying stator manufacturing. This solution avoids winding directly onto the teeth and facilitates the creation of slot closures.

[0012] Furthermore, stator cooling is also a crucial issue, given the power levels targeted for these electrical machines, in order to limit the heating of the stator and the electrical machine. This heating could lead to malfunctions and reduce the lifespan of the electrical machine.

[0013] We know of patent applications US2023 / 0082277 Al, US2022 / 028600 Al, US2019 / 0058374 Al, CN106452013 A and US2023 / 0412014 Al which relate to segmented stator electric machines with cooling.

[0014] Thus, the invention aims to enable the cooling of the stator, in particular a segmented stator, regardless of the segmentation principle used. In other words, the invention aims to ensure the adaptability of the stator head cooling solution to different types of segmented stators. Summary of the invention

[0015] The invention relates to an axial flux electric machine comprising an outer casing enclosing at least one stator and at least one rotor, each stator being a segmented stator comprising a yoke and teeth inserted into openings in the yoke, the teeth projecting axially on either side of the yoke, the yoke comprising inter-tooth areas regularly distributed around its circumference. Furthermore, the electric machine comprises at least one cooling circuit for the circulation of a cooling fluid, with at least one portion of said circuit in contact with at least one of said inter-tooth zones of the cylinder head, preferably with at least one portion of said circuit in contact with each inter-tooth zone, said portion of said cooling fluid circuit being positioned between the cylinder head and the outer casing, said portion extending preferably substantially radially.

[0016] According to a variant of the invention, the electric machine comprises a single cooling circuit which connects the different contact portions of the different inter-tooth zones of the cylinder head, preferably this cooling circuit comprising connecting parts between the portions, these connecting parts being positioned radially inside or outside and extending substantially circumferentially.

[0017] Alternatively, the electric machine includes several cooling fluid circuits, each cooling circuit preferably comprising a fluid supply through the outer casing, passage in a first portion of the cooling circuit radially from the outside to the inside or from the inside to the outside and then in a second portion of the cooling circuit radially, in the opposite direction to the first portion, and a cooling fluid outlet through the outer casing.

[0018] According to one configuration of the invention, at least one cooling fluid circuit, preferably each cooling fluid circuit, is a closed circuit internal to the electrical machine, and the electrical machine includes the cooling fluid which is a phase change fluid capable of vaporizing in at least one portion to capture heat from the inter-tooth area, and of condensing on contact with a cold area, the cold area being preferably an area of ​​the outer casing.

[0019] According to one embodiment of the invention, the teeth are in contact with the outer casing and the electric machine includes a gap between the cylinder head and the outer casing.

[0020] Advantageously, the cylinder head is in contact with the outer casing and the electrical machine includes a clearance between the teeth and the outer casing.

[0021] According to one embodiment of the invention, the electric machine includes first axial supply channels for supplying the cooling fluid into each portion and second axial collection channels for the outlet of the cooling fluid from each portion.

[0022] According to one configuration of the invention, at least one portion, preferably each portion, comprises a tube positioned between the cylinder head and the outer casing.

[0023] Preferably, each tube of each portion is at least partially embedded in a coating material, and preferably, the coating material fills the entire section, in axial cross-section, between the cylinder head, the teeth, and the outer casing.

[0024] Alternatively or additionally, each portion of the cooling circuit includes a passage of the cooling fluid directly in contact with the cylinder head in the inter-tooth area.

[0025] According to one embodiment of the invention, the outer casing comprises bosses in the direction of the inter-tooth areas of the cylinder head of at least one stator, the cooling fluid circuit comprising holes in the bosses and a sealing system between each inter-tooth area and the opposite boss so that the cooling fluid comes into direct contact with each inter-tooth area.

[0026] Advantageously, the electric machine includes intermediate parts, each intermediate part being positioned between each inter-tooth zone and the outer casing, and first and second sealing devices between each intermediate part and the opposite inter-tooth zone and between each intermediate part and the outer casing, said portion of the cooling circuit passing between the inter-tooth zone and the intermediate part so as to allow direct contact of the cooling fluid in the inter-tooth zone.

[0027] According to one embodiment of the invention, each intermediate piece includes at least one supply bore and one coolant collection bore for the portion.

[0028] Preferably, the electric machine comprises two stators and one rotor. List of figures

[0029] Other features and advantages of the electric machine according to the invention will become apparent from the following description of non-limiting examples of embodiments, with reference to the figures attached and described below. [Fig 1]

[0030] Fig. 1 represents a first variant of an axial flux electric machine according to the invention. [Fig 2]

[0031] Fig. 2 represents a view in a plane orthogonal to the longitudinal direction of an axial flux electrical machine according to the invention. [Fig 3]

[0032] Fig. 3 represents a second variant of an axial flux electric machine according to the invention. [Fig 4]

[0033] Figure 4 represents a third variant of an axial flux electric machine according to the invention. [Fig 5]

[0034] Figure 5 represents a fourth variant of an axial flux electric machine according to the invention. [Fig 6]

[0035] Figure 6 represents a fifth variant of an axial flux electric machine according to the invention. [Fig 7]

[0036] Figure 7 represents a sixth variant of an axial flux electric machine according to the invention. [Fig 8]

[0037] Figure 8 shows a cooling circuit connecting the different parts of an axial flux electric machine according to an embodiment of the invention. [Figure 9]

[0038] Figure 9 represents cooling circuits linking two by two the different portions of an axial flux electrical machine according to an embodiment of the invention. Description of the implementation methods

[0039] The "longitudinal" or "axial" direction is the direction of the longitudinal axis of the stator and the electrical machine.

[0040] The terms "front" and "rear" are understood in relation to the longitudinal axis, the term "front" being understood for the stator on the side of the coils, therefore on the side of the rotor, and the term "rear" being on the side opposite the coils (opposite the rotor, which may correspond to the side of the outer casing).

[0041] Thickness is understood to mean a length in the longitudinal direction.

[0042] The terms "internal" and "external" are understood relative to each other, the internal term being relatively closer to the longitudinal axis (which serves as the axis of rotation of the rotor) than the external term.

[0043] The invention relates to an axial flux electric machine comprising an outer casing (which may also be called the "outer casing" or "housing") enclosing at least one stator and at least one rotor. The stator(s) and rotor(s) are mounted in the outer casing. The rotor is free to rotate about an axis of rotation, called the longitudinal axis of the electric machine.

[0044] Each stator is a segmented stator comprising a yoke (which may be a circumferential yoke), this yoke comprising openings, and teeth inserted into openings in the yoke, the teeth protruding axially (i.e. longitudinally) on either side of the cylinder head. Coils can be wound around the teeth. The teeth extend longitudinally and are fairly evenly distributed around the circumference of the cylinder head.

[0045] By "circumferential cylinder head", we mean a cylinder head which extends substantially over the entire circumference of the electrical machine, that is to say over 360° around the longitudinal axis.

[0046] The segmented stator is particularly advantageous for simplifying the production of stators: this solution allows winding to be carried out without having to assemble the stator beforehand: for example, winding can be carried out directly on the teeth before insertion into the cylinder head, and it facilitates the closing of notches.

[0047] Alternatively, the cylinder head may comprise segments inserted between the teeth, the set of segments thus forming a cylinder head. The segments ensure the function of flow recirculation, as in a cylinder head made by stacking or winding sheets.

[0048] By design, the cylinder head (particularly a circumferential one) includes inter-tooth zones regularly distributed around its circumference. These inter-tooth zones are areas of the cylinder head located between the teeth. They therefore extend substantially radially between the teeth and are regularly distributed around the circumference of the cylinder head, just like the teeth themselves.

[0049] According to the invention, the electric machine comprises at least one cooling circuit through which a cooling fluid circulates to cool at least one of the inter-tooth areas, preferably to cool each inter-tooth area. In other words, at least one cooling circuit (or each circuit if there are several) is designed to allow the circulation of a cooling fluid within that circuit. As a result, the cooling fluid can absorb heat from each inter-tooth area with which it is in contact, thereby cooling each of these inter-tooth areas. To achieve this, the electric machine may comprise a single cooling circuit through which the cooling fluid circulates, and which allows the cooling of all the inter-tooth areas.Alternatively, the electric machine may include a cooling circuit through which a cooling fluid circulates to cool at least one of the inter-tooth zones, preferably to cool each inter-tooth zone: in this case, there are as many cooling circuits as there are inter-tooth zones. According to other variants, the electric machine could include several cooling circuits, each cooling several inter-tooth zones, for example, two at a time. As a non-limiting example, the cooling fluid could be glycol water.

[0050] At least one cooling circuit includes at least a portion of the circuit in contact with at least one of the inter-tooth areas of the cylinder head to facilitate the cooling of that area. The portion of the cooling circuit is positioned axially between the cylinder head (in the inter-tooth areas) and the outer casing so as to allow the recovery of heat from the inter-tooth area and the efficient transfer of this heat to the outer casing, where the heat is dissipated to the outside.

[0051] Preferably, at least one cooling circuit may include at least one portion of the circuit in contact with each inter-tooth area. For example, there may be several portions of the same cooling circuit or of several cooling circuits, and each of these different portions may be in contact with a distinct inter-tooth area.

[0052] Preferably, each portion of the cooling circuit in contact with each inter-tooth zone can extend substantially radially, to facilitate heat exchange and to increase the exchange surface.

[0053] Thereafter, the notion of "portion" always refers to a portion of a cooling circuit.

[0054] According to one embodiment of the invention, the electric machine may include a single cooling circuit that connects the various portions of the cooling circuit in contact with the different inter-tooth areas of the cylinder head. This makes it possible to limit the number of circuits and therefore the number of seals and the associated risk of leaks. When the cooling circuit is supplied with coolant from outside the electric machine and the coolant is also collected outside the electric machine, the number of coolant inlets / outlets of the electric machine can also be limited.

[0055] Preferably, this cooling circuit may include connecting sections between the portions, these connecting sections being positioned radially inside or outside and extending substantially circumferentially. These connecting sections may thus link: - the external radial ends of two adjacent portions (circumferentially): in this case, the connecting parts are positioned radially on the outside; - or connect the internal radial ends of two adjacent portions (circumferentially): in this case, the connecting parts are positioned radially inside.

[0056] Thus, the cooling circuit forms a serpentine (or coil) which passes in contact with the inter-tooth areas and winds around the teeth. This circuit allows a improved cooling as it allows cooling of the interdental areas and teeth.

[0057] Alternatively, the electric machine may include several cooling fluid circuits: one for each portion of each inter-tooth zone or one connecting two portions of each inter-tooth zone, for example. This allows for better distribution of cooling across the different inter-tooth zones on the cylinder head.

[0058] Each circuit may include, for example, a fluid supply passing through the outer casing, passage through a first portion of the cooling circuit radially from the outside to the inside or from the inside to the outside, then through a second portion of the cooling circuit radially, in the opposite direction to the first portion, and a cooling fluid outlet passing through the outer casing. In this case, each cooling circuit connects two portions of two circumferentially adjacent inter-tooth zones.

[0059] By "circumferentially adjacent", we mean two inter-tooth zones which follow one another in the circumferential direction: thus, there is not an inter-tooth zone, in the circumferential direction, between two circumferentially adjacent inter-tooth zones.

[0060] According to one embodiment of the invention, at least one cooling fluid circuit, preferably each cooling fluid circuit, may be a closed circuit internal to the electric machine. In other words, the electric machine does not include a cooling fluid supply or collection system from outside the electric machine. Furthermore, the electric machine may include a cooling fluid that is a phase-change fluid capable of vaporizing in at least a portion in contact with the inter-tooth area to absorb heat from the inter-tooth area, and of condensing upon contact with a cold area, the cold area being preferably an area of ​​the outer casing. Thus, the closed cooling circuit forms a heat pipe.

[0061] Advantageously, the stator teeth can be in contact with the outer casing, and the electrical machine can include a gap between the yoke and the outer casing. In this case, the stator is clamped to the outer casing by the contact of the teeth against the outer casing. The teeth can then be cooled directly by thermal conduction from the teeth to the outer casing.

[0062] Alternatively, the cylinder head may be in contact with the outer casing, and the electric machine may include a clearance between the teeth and the outer casing. In this case, the stator is clamped in the outer casing by the cylinder head contacting the outer casing (via a boss on the outer casing or by an intermediate part, for example).

[0063] According to one configuration of the invention, the electric machine may include first axial supply channels for supplying the cooling fluid to each portion and second axial collection channels for the outlet of the cooling fluid from each portion. These supply and collection channels may, in particular, pass through the outer casing (and a possible intermediate piece positioned between the outer casing and the inter-tooth area of ​​the cylinder head). Thus, each portion includes a specific supply and collection system. It is easier to cool the electric machine and to obtain homogeneous cooling around the circumference of the cylinder head.

[0064] According to one embodiment of the invention, at least one portion of the cooling circuit, preferably each portion of the cooling circuit, may include a tube (or cooling pipe) positioned (inserted in particular) between the cylinder head (in particular the inter-tooth area) and the outer casing. This tube may, in particular, be in contact with at least the inter-tooth area and preferably in contact with the outer casing so as to promote the recovery of heat from the inter-tooth area and its transfer to the outer casing, considered as a "cold" area of ​​the electrical machine, the term "cold" extending relative to the other parts of the electrical machine which are, in fact, hotter than the outer casing during the operation of the machine.

[0065] Advantageously, each tube in each portion can be at least partially embedded in a coating material, preferably filling the entire axial cross-section between the cylinder head, the teeth, and the outer casing. This coating material helps to hold the tube in position and also improves heat exchange between the inter-tooth area, the teeth, and the tube, and preferably the outer casing. Thus, the coating material facilitates heat recovery.

[0066] The coating material may in particular be a resin, such as an epoxy resin which has good thermal conductivity properties.

[0067] According to one configuration of the invention, each portion of the cooling circuit may include a passage for the cooling fluid in direct contact with the cylinder head in the inter-tooth area. This configuration allows for better cooling of the inter-tooth area through direct contact with the cooling fluid. Furthermore, the shape and surface area of ​​the portion can be optimized to further improve cooling (compared to a solution using a tube as the portion).

[0068] According to one embodiment of the invention, the outer casing may include bosses facing the inter-tooth areas of the cylinder head of at least one stator. Indeed, since the teeth protrude axially on either side of the cylinder head, the The bosses allow the outer casing of the cylinder head to be brought closer together, reducing the play between these parts. This facilitates the cooling of the inter-tooth areas.

[0069] In this embodiment, the cooling fluid circuit may include, in particular, (axial) holes in the bosses and a sealing system between each inter-tooth area and the opposite boss so that the cooling fluid comes into direct contact with each inter-tooth area. The axial holes allow the fluid to be supplied to and collected from each portion.

[0070] Alternatively, the electric machine may include intermediate parts, each intermediate part being positioned between each inter-tooth area and the outer casing. In other words, the bosses of the previous solution are replaced by intermediate parts. The electric machine may then include seals between each intermediate part and the opposite inter-tooth area, and between each intermediate part and the outer casing, so as to prevent leaks from the cooling circuit. The portion of the cooling circuit passes between the inter-tooth area and the intermediate part so as to allow direct contact of the cooling fluid in the inter-tooth area.

[0071] Preferably, each intermediate piece may include at least one (axial) supply bore and one (axial) collection bore for the cooling fluid of the portion to improve the cooling of each portion. The supply bore and the collection bore may, in particular, be aligned with the respective fluid supply and fluid outlet (which pass through the outer casing).

[0072] The cylinder head can be axially or radially rolled: in other words, the cylinder head is formed from axially or radially rolled sheets. Axial rolling is particularly advantageous for the invention, to ensure a good surface finish on the cylinder head so as to facilitate heat exchange.

[0073] The electric machine may also include a tooth cooling system, independent or not of the cooling circuit. If the tooth cooling system includes a cooling fluid, the supplies and collections of the cooling system may be separate from those of the cooling circuit (the system and the cooling circuit are in this case independent) or they may be common (the system and the cooling circuit are in this case dependent on each other).

[0074] In order to protect the rear sheet metal of the cylinder head from any oxidation in the case of axial rolling, this sheet metal can be covered with a coating such as a thermally conductive and electrically insulating sheet or a paint or other surface treatment.

[0075] For radially laminated cylinder heads, a coating layer may be applied to the rear surface of the cylinder head, so as to create a sealing layer, on the one hand between the edges of the sheets themselves, and on the other hand, between the edges of the sheets and the sealing gasket which bears on this surface.

[0076] Advantageously, the electric machine may comprise two segmented stators and a rotor. Each stator comprises a stator as described above according to the invention.

[0077] Figure 1 illustrates, schematically and without limitation, a first variant of an axial flux electric machine according to the invention. The diagram on the left illustrates this first variant in a plane including the axial direction of the electric machine, and the diagram on the right corresponds to section AA illustrated in the diagram on the left.

[0078] The electric machine here comprises an outer casing 2 which encloses a stator and a rotor (not shown).

[0079] The stator comprises a cylinder head 1 and teeth 3 inserted into openings in the cylinder head 1. The teeth 3 protrude axially on either side of the cylinder head 1.

[0080] The cylinder head 1 includes inter-tooth areas 7, between the teeth 3.

[0081] Coils can be wound around the teeth 3.

[0082] In addition, the outer casing 2 includes bosses 4 which extend towards the cylinder head 1. These bosses 4 include axial holes 5 which go completely through the outer casing 2 for the supply and collection of cooling fluid.

[0083] These axial holes 5 and the passage 6 for the cooling fluid between the bosses 4 and the inter-tooth area 7 form part of a cooling circuit. The passage 6 forms a portion of the cooling circuit in direct contact with the inter-tooth area 7.

[0084] The electric machine includes a sealing system 8 between the bosses 4 and the inter-tooth area 7. The sealing system 8 may in particular be a seal, such as an O-ring.

[0085] Figure 2 shows a view in a plane orthogonal to the longitudinal direction of an axial flux electrical machine according to the invention. Figure 2 is the orthogonal view of Figure 1.

[0086] The stator of the electric machine comprises a yoke and 3 teeth regularly distributed around the yoke. The teeth here have a trapezoidal cross-section as illustrated in [Fig.2].

[0087] The electrical machine also includes an outer casing 2.

[0088] Coils (not shown) can be wound around the teeth 3.

[0089] As shown, the cylinder head comprises inter-tooth zones 7 regularly distributed around the cylinder head. These inter-tooth zones 7 extend substantially radially between the teeth.

[0090] Furthermore, the electric machine includes a cooling circuit for cooling each inter-tooth area 7 using a portion of the cooling circuit for each inter-tooth area 7, each portion being formed here of a passage 6 of cooling fluid to cool this inter-tooth area 7. The passage 6 is formed between the cylinder head and the outer casing 2. The passage 6 is supplied with cooling fluid through one of the holes 5 through the outer casing 2 and the cooling fluid is collected through the other hole 5.

[0091] The passage 6 therefore extends essentially radially and the passage of the cooling fluid through this passage is also substantially radial from the inside to the outside or vice versa.

[0092] The outer casing 2 also includes a gasket groove 18 for positioning a sealing device, such as a gasket (not shown), between the outer casing 2 and the cylinder head.

[0093] Figure 3 represents, schematically and without limitation, a second variant of an axial flux electric machine according to the invention. [Fig.3] is a view similar to [Fig.1].

[0094] The electric machine here comprises an outer casing 2 which encloses a stator and a rotor (not shown).

[0095] The stator comprises a cylinder head 1 (which includes openings) and teeth 3 inserted into openings in the cylinder head 1. The teeth 3 protrude axially on either side of the cylinder head 1.

[0096] The cylinder head 1 includes inter-tooth areas 7, between the teeth 3.

[0097] Coils can be wound around the teeth 3.

[0098] Furthermore, the electric machine includes intermediate parts 15 extending between the cylinder head 1, at the inter-tooth area 7, and the outer casing 2. These intermediate parts 15 include axial bores 14 that pass completely through the intermediate parts for the supply and collection of cooling fluid. These axial bores 14 are aligned with axial holes that pass through the outer casing 2.

[0099] These axial bores 14 of the intermediate parts 15, the axial holes in the outer casing 2, and the passage 6 of the cooling fluid between the intermediate parts 15 and the inter-tooth area 7 form part of a cooling circuit. The passage 6 forms a portion of the cooling circuit in direct contact with the inter-tooth area 7.

[0100] The electric machine includes a first sealing device 16 between the intermediate parts 15 and the inter-tooth area 7 and a second sealing device 17 between the intermediate parts 15 and the outer casing 2. The first and second sealing devices 16 and 17 may in particular include seals, such as O-rings.

[0101] In figures 1 and 3, the teeth 3 are in contact with the outer casing 2 while the electric machine includes a gap between the cylinder head 1 and the outer casing 2 or the intermediate part 15.

[0102] Figure 4 represents, schematically and without limitation, a third variant of an axial flux electric machine according to the invention. [Fig.4] is a view similar to [Fig.1].

[0103] In [Fig. 4], the teeth 3 are not in contact with the outer sheath 2: a Functional play exists between the teeth 3 and the outer shell 2. On the other hand, the outer shell 2 is in contact with the cylinder head 1, at the level of the inter-tooth areas 7, thanks to bosses 4 of the outer shell 2, in the direction of the cylinder head 1.

[0104] The electric machine here comprises an outer casing 2 which encloses a stator and a rotor (not shown).

[0105] The stator comprises a cylinder head 1 and teeth 3 inserted into openings in the cylinder head 1. The teeth 3 protrude axially on either side of the cylinder head 1.

[0106] The cylinder head 1 includes inter-tooth areas 7, between the teeth 3.

[0107] Coils can be wound around the teeth 3.

[0108] In addition, the outer casing 2 includes bosses 4 which extend towards the cylinder head 1. These bosses 4 include axial holes 5 which go completely through the outer casing 2 for the supply and collection of cooling fluid.

[0109] These axial holes 4 and the passage 6 for the cooling fluid between the bosses 4 and the inter-tooth area 7 form part of a cooling circuit. The passage 6 forms a portion of the cooling circuit in direct contact with the inter-tooth area 7.

[0110] The electric machine includes a sealing system 8 between the bosses 4 and the inter-tooth area 7. The sealing system 8 may in particular be a seal, such as an O-ring.

[0111] Figure 5 represents, schematically and without limitation, a fourth variant of an axial flux electric machine according to the invention. [Fig.5] is a view similar to the diagram on the left of [Fig.1].

[0112] The electric machine here comprises an outer casing 2 which encloses a stator and a rotor (not shown).

[0113] The stator comprises a cylinder head 1 and teeth 3 inserted into openings in the cylinder head 1. The teeth 3 protrude axially on either side of the cylinder head 1.

[0114] The cylinder head 1 includes inter-tooth areas 7, between the teeth 3.

[0115] Coils can be wound around teeth 3.

[0116] In this embodiment, the cooling circuit includes a tube 9, which serves as a portion. This tube 9 is positioned between the inter-tooth area 7 of the cylinder head 1 and the outer casing 2; this tube has a radial direction (relative to the stator). This tube 9 is at least in contact with the inter-tooth area 7 and preferably also in contact with the outer casing 2.

[0117] Figure 6 schematically and non-limitingly represents a fifth variant of an axial flux electric machine according to the invention. Figure 6 is a view similar to the left-hand diagram of Figure 1.

[0118] The electric machine here comprises an outer casing 2 which encloses a stator and a rotor (not shown).

[0119] The stator comprises a cylinder head 1 and teeth 3 inserted into openings in the cylinder head 1. The teeth 3 protrude axially on either side of the cylinder head 1.

[0120] The cylinder head 1 includes inter-tooth areas 7, between the teeth 3.

[0121] Coils can be wound around teeth 3.

[0122] In this embodiment, the cooling circuit includes a tube 9, which serves as a portion. This tube 9 is positioned between the inter-tooth area 7 of the cylinder head 1 and the outer casing 2; this tube has a radial direction (relative to the stator). This tube 9 is at least in contact with the inter-tooth area 7 and preferably also in contact with the outer casing 2.

[0123] In addition, a coating material 10 is positioned around the tube 9. This coating material 10 is at least in contact with the inter-tooth area 7, the tube 9 and the teeth 3.

[0124] This coating material 10 may in particular include a resin, such as an epoxy resin.

[0125] Figure 7 schematically and non-limitingly represents a sixth variant of an axial flux electric machine according to the invention. Figure 7 is a view similar to the left-hand diagram of Figure 1.

[0126] The electric machine here comprises an outer casing 2 which encloses a stator and a rotor (not shown).

[0127] The stator comprises a cylinder head 1 and teeth 3 inserted into openings in the cylinder head 1. The teeth 3 protrude axially on either side of the cylinder head 1.

[0128] The cylinder head 1 includes inter-tooth areas 7, between the teeth 3.

[0129] Coils can be wound around teeth 3.

[0130] In this embodiment, the cooling circuit includes a tube 9, which serves as a portion. This tube 9 is positioned between the inter-tooth area 7 of the cylinder head 1 and the outer casing 2; this tube has a radial direction (relative to the stator). This tube 9 is at least in contact with the inter-tooth area 7 and preferably also in contact with the outer casing 2.

[0131] In addition, a encapsulating material 10 is positioned around the tube 9. This encapsulating material 10 is at least in contact with the inter-tooth area 7, the tube 9 and the teeth 3 as well as the outer casing 2: the encapsulating material 10 here fills all the space between the tube 9, the inter-tooth area 7 of the cylinder, the teeth 3 on each side and the outer casing 2.

[0132] This coating material 10 may in particular include a resin, such as an epoxy resin.

[0133] Figure 8 schematically and non-limitingly represents a cooling circuit connecting the various parts of an axial flux electric machine according to the invention. Figure 8 is an orthogonal view of Figure 1, that is, in a plane substantially orthogonal to the axial direction of the stator of the electric machine.

[0134] The electric machine here comprises an outer casing which encloses a stator and a rotor (not shown).

[0135] The stator comprises a breech and 3 teeth inserted into openings in the breech.

[0136] The cylinder head includes inter-tooth areas 7, between the teeth 3.

[0137] Coils 11 are wound around the teeth 3.

[0138] In addition, the electric machine includes a single cooling circuit 12 of coolant which includes portions 13 in contact with the inter-tooth areas 7 of the cylinder head, the portions 13 being located between the inter-tooth areas 7 and the outer casing and extending substantially radially.

[0139] This cooling circuit winds between the cylinder head and the outer casing, around the teeth 3. Thus, the cooling circuit 12 includes connecting parts between the portions 13, these connecting parts being positioned radially inside or outside (relative to the teeth 3 and the coils 11 surrounding them) and extending substantially circumferentially to connect the external radial ends of the adjacent circumferential portions together or to connect the internal radial ends of the adjacent circumferential portions together.

[0140] The embodiment of [Fig.8] is compatible with the implementations of Figures 1 to 7.

[0141] Figure 9 schematically and non-limitingly represents cooling circuits connecting, in pairs, the different portions of an axial flux electrical machine according to the invention. Figure 9 is an orthogonal view of Figure 1, i.e. to say in a plane substantially orthogonal to the axial direction of the stator of the electric machine.

[0142] The electric machine here comprises an outer casing which encloses a stator and a rotor (not shown).

[0143] The stator comprises a breech and 3 teeth inserted into openings in the breech.

[0144] The cylinder head includes inter-tooth areas 7, between the teeth 3.

[0145] Coils 11 are wound around the teeth 3.

[0146] Furthermore, the electric machine includes several coolant cooling circuits 12. Each cooling circuit comprises two adjacent circumferential portions 13 which it connects by means of a connecting portion, here internal, since this connecting portion links the internal radial ends of the two portions 13 of the cooling circuit (alternatively, the connecting portion could be external, i.e., linking the external radial ends of the two portions 13 of the cooling circuit). Each portion 13 is in contact with a tooth interlocking area 7 of the cylinder head, the portions 13 being situated between the tooth interlocking areas 7 and the outer casing and extending substantially radially.

[0147] The embodiment of [Fig.9] is compatible with the implementations of Figures 1 to 7.

[0148] Of course, the invention is not limited to the embodiments represented but includes all variants and combinations of variants of these embodiments, as long as they remain technically compatible with each other.

Claims

Demands

1. An axial flux electric machine comprising an outer casing (2) enclosing at least one stator and at least one rotor, each stator being a segmented stator comprising a yoke (1) and teeth (3) inserted into openings in the yoke (1), the teeth (3) projecting axially on either side of the yoke (1), the yoke (1) comprising inter-tooth zones (7) regularly distributed around the circumference of the yoke (1), characterized in that the electric machine comprises at least one cooling circuit (12) for the circulation of a cooling fluid, with at least one portion (13) of said circuit in contact with at least one of said inter-tooth zones (7) of the yoke (1), preferably with at least one portion (13) of said circuit in contact with each inter-tooth zone (7), said portion (13) of said cooling circuit (12) of cooling fluid being positioned between the yoke (1) and the outer casing (2),said portion (13) extending preferentially substantially radially.

2. Electric machine according to claim 1, characterized in that the electric machine comprises a single cooling circuit (12) which connects the different portions (13) in contact with the different inter-tooth areas (7) of the cylinder head (1), preferably this cooling circuit (12) comprising connecting parts between the portions (13), these connecting parts being positioned radially inside or outside and extending substantially circumferentially.

3. Electric machine according to claim 1, characterized in that the electric machine comprises several cooling circuits (12) of cooling fluid, each cooling circuit (12) preferably comprising a fluid supply through the outer casing (2), passage in a first portion of the cooling circuit (12) radially from the outside to the inside or from the inside to the outside and then in a second portion of the cooling circuit (12) radially, in the opposite direction to the first portion, and a cooling fluid outlet through the outer casing (2).

4. An electrical machine according to any one of the preceding claims, characterized in that at least one fluid circuit of cooling (12), preferably each cooling fluid circuit (12), is a closed circuit internal to the electrical machine, and the electrical machine includes the cooling fluid which is a phase change fluid capable of vaporizing in at least one portion (13) to capture heat from the inter-tooth area, and of condensing on contact with a cold area, the cold area being preferably an area of ​​the outer casing (2).

5. Electric machine according to any one of the preceding claims, characterized in that the teeth (3) are in contact with the outer casing (2) and the electric machine includes a clearance between the cylinder head (1) and the outer casing (2).

6. Electric machine according to any one of claims 1 to 4, characterized in that the cylinder head (1) is in contact with the outer casing (2) and the electric machine includes a clearance between the teeth (3) and the outer casing (2).

7. Electric machine according to any one of the preceding claims, characterized in that the electric machine comprises first axial supply channels (5) for supplying the cooling fluid into each portion (13) and second axial collection channels (5) for the outlet of the cooling fluid from each portion (13).

8. Electric machine according to any one of the preceding claims, characterized in that at least one of the at least one portion (13), preferably each portion, comprises a tube (9) positioned between the cylinder head (1) and the outer casing (2).

9. Electric machine according to the preceding claim, characterized in that each tube (9) of each portion (13) is at least partially embedded in a coating material (10), preferably the coating material (10) filling the entire section, in axial cross-section, between the cylinder head (1), the teeth (3), and the outer casing (2).

10. Electric machine according to any one of claims 1 to 7, characterized in that each portion (13) of the cooling circuit comprises a passage (6) of the cooling fluid directly in contact with the cylinder head (1) in the inter-tooth area (7).

11. An electric machine according to the preceding claim, characterized in that the outer casing (2) comprises bosses (4) directed towards the inter-tooth areas (7) of the cylinder head of at least one stator, the cooling circuit (12) of cooling fluid comprising drillings (5) in the bosses and a sealing system (8) between each inter-tooth zone (7) and the opposite boss (4) so ​​that the cooling fluid comes into direct contact with each inter-tooth zone (7).

12. Electric machine according to claim 10, characterized in that the electric machine comprises intermediate pieces (15), each intermediate piece (15) being positioned between each inter-tooth zone (7) and the outer casing (2), and first and second sealing devices (16, 17) between each intermediate piece (15) and the inter-tooth zone (7) opposite each other and between each intermediate piece (15) and the outer casing (2), said portion (13) of the cooling circuit passing between the inter-tooth zone (7) and the intermediate piece (15) so as to permit direct contact of the cooling fluid in the inter-tooth zone (7).

13. Electric machine according to the preceding claim, characterized in that each intermediate piece (15) comprises at least one supply bore (14) and one coolant collection bore (14) for portion (13).

14. Electric machine according to any one of the preceding claims with two stators and one rotor.

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