Core sleeve arrangement for axial flux motor

Abstract

A stator (100) for an axial flux electric machine, comprising:-a plurality of stator members (200), each stator member comprising a core sleeve (109) placed between a core (105) and a coil (106); -a housing surrounding the stator members (200) wherein, for each of the stator members (200):-the core sleeve (109) extends at least partially between the top wall (111) and the bottom wall (110), thereby defining in the housing a cavity (600, 700) adapted to receive a cooling fluid flowing at the outside of the core sleeve (109); -at least some of the successive turns of the coil (106) are spaced apart thereby defining a fluid passage (602) towards the core sleeves (109) such that the pressurized cooling fluid supplied to the cavities (600, 700) creates a pressure difference between the outside and the inside of each core sleeve (109) thereby pressing the core sleeve (109) against the respective core (105).

Description

Technical Field

[0001] This invention generally relates to the field of axial flux motors. Specifically, a stator for an axial flux motor is proposed, thereby allowing improved electrical insulation between coils, while achieving improved cooling efficiency and improved liquid sealing. Background Technology

[0002] An axial flux motor is a type of motor in which flux is generated in the axial direction, which is the direction of the axis of rotation. Typically, an axial flux motor comprises a disc or ring rotor and a stator, both having a central axis corresponding to the motor's axis of rotation, with a narrow air gap axially spaced between them. The rotor comprises a magnetic material (typically a permanent magnet) that generates the axial magnetic flux. The stator comprises multiple coils in which current can flow. Typically, each stator coil is wound around a core made of a ferromagnetic material to guide and concentrate the magnetic flux. During motor operation, the rotor is driven by the magnetic field generated by the stator current, while in generator mode, current is induced in the stator coils due to the rotor's rotation. Different topologies are known for axial flux motors (e.g., comprising one rotor disc and one stator disc, one rotor disc and two stator discs, or two rotor discs positioned on opposite sides of a stator disc). An axial flux motor can be a toroidal type with a stator yoke or a yokeless type without a stator yoke.

[0003] The stator design of axial flux motors presents several technical challenges, particularly regarding the electrical insulation of these coils from the core and the cooling of these stator components. These challenges are especially relevant in high-power axial flux motors operating at high voltages and high speeds.

[0004] In practice, when an axial flux motor operates, a voltage difference is generated between the motor's coil and the corresponding core around which the coil is wound. Therefore, to prevent current from flowing between the winding and the core, the coil must be electrically isolated from the core. The voltage difference between the coil and the corresponding core depends on the motor's operating voltage. In electric vehicles, there is a clear trend towards higher operating voltages, as this increases the vehicle's range, charging speed, and efficiency. Therefore, high requirements are placed on the electrical insulation between the coil and the core to ensure the motor can operate safely in such applications. The effectiveness of this insulation is determined by the electrical properties of the insulating material and depends on the degree to which the insulating portion physically shields the coil and the core. High voltage can bridge a distance or gap between conductors. Therefore, even a small gap or tear in the insulation material between the coil and the core can allow an arc to form, resulting in a short circuit.

[0005] Stator cooling can be achieved in different ways. For example, in high-performance axial flux motors, the stator can be liquid-cooled, where a coolant circulates within a hollow stator housing, directly immersing the coils in the coolant. In such a stator, the stator housing needs to be perfectly fluid-tight to prevent coolant leakage, presenting additional technical challenges.

[0006] To electrically isolate the core from the coil, an insulating layer is typically placed between the coil and the corresponding core. In known solutions in the prior art, the insulating layer is made of an electrically insulating sheet (e.g., Nomex paper) wound around the core. This insulating sheet can be used, for example, in conjunction with a liquid-cooled stator disclosed in WO2010 / 092400 or EP2606561B1. However, for the insulating layer to fit over the core, it needs to be slightly larger to compensate for manufacturing variations in the core and the insulating layer. Therefore, a gap exists between the core and the insulating layer, increasing the thermal resistance between them. Consequently, the amount of heat that can be extracted from the core by the cooling liquid is significantly reduced, thus decreasing the motor's power. Furthermore, during operation, the gap can be filled with stagnant cooling liquid, further affecting heat transfer from the core. Additionally, the insulating layer may not fit perfectly between the disc-shaped walls of the housing, potentially leaving a non-insulating gap between the coil and the core around which it is wound. Such a gap can allow arcing to occur, resulting in a short circuit.

[0007] Furthermore, in WO2010 / 092400, the housing seal is achieved by extending the disc-shaped wall of the housing through the air gap, thus covering the end face of the ferromagnetic core. However, extending the disc-shaped wall into the air gap reduces the mechanical air gap of the motor. This tightens manufacturing tolerances because there is less available space between the rotor and stator to accommodate any mechanical deviations, which therefore increases manufacturing costs and complexity. Additionally, it increases the risk of rotor-stator collisions due to mechanical disturbances to the motor, such as shocks or vibrations. In EP2606561B1, the liquid seal of the housing is achieved by overmolding the end face of the ferromagnetic core into the disc-shaped wall of the housing. Therefore, this approach relies on establishing a liquid seal by overmolding two different materials (the housing and the core, respectively), which is challenging due to the difference in thermal expansion between these materials and the difficulty in establishing reliable adhesion between the different materials of the housing and the core.

[0008] In other known solutions in the prior art, the insulation layer between the core and the coil is provided as a rigid component, such as a rigid component molded from an electrically insulating material (e.g., plastic). CN212969228U proposes a solution in which an insulating chamfered component is arranged on the outside of the ferromagnetic core body, at least near the side corner of the core body, such that the winding wound on the ferromagnetic core is spaced apart from the core. In US20150229177A1, an insulating molded component consisting of a rigid sleeve and two side caps is used to separate the core from the corresponding coil. The article mentions that the sleeve, for example, made of polyester material, should be manufactured as thin as possible, however, subject to a minimum thickness determined by the strength of the insulating molded component. In both of these example solutions, the rigid component used to insulate the core from the coil forms an additional, relatively thick layer between the core and the corresponding coil, thereby hindering effective heat transfer from the core.

[0009] The object of this invention is to disclose an axial flux motor that addresses one or more of the aforementioned disadvantages of prior art solutions. More specifically, the object of this invention is to provide a stator for an axial flux motor that allows for improved electrical insulation between coils and corresponding coils, while achieving improved cooling efficiency and improved liquid sealing. Summary of the Invention

[0010] According to a first aspect of the invention, the objective determined above is achieved by a stator for an axial flux motor as defined in claim 1, the stator comprising: - The central axis, during installation, corresponds in the axial direction to the rotation axis of the axial flux motor; - Multiple stator components arranged rotationally symmetrically about a central axis, wherein each stator component comprises: ○ Ferromagnetic core; ○ A coil comprising multiple turns wound around a core; ○ Core sleeve, which is placed between the core and the coil, having an inner side facing the core and an outer side facing the coil; - A housing surrounding a stator assembly, the housing including a top wall, a bottom wall, an inner circumferential wall, and an outer circumferential wall extending between the top and bottom walls, and the housing also including one or more ports adapted for supplying cooling fluid. For each of the stator components: - The core sleeve extends at least partially between the top and bottom walls, thereby defining a cavity in the housing adapted to receive cooling fluid flowing at the outside of the core sleeve. - At least some of the consecutive turns of the coil are spaced apart, thereby defining a fluid passage toward the core bushing; - The core sleeve may be made of elastic or flexible material. The pressurized cooling fluid supplied to the cavity causes the cooling fluid to flow through the fluid passage between the continuous turns of the coil (106) and reach the core sleeve (109), thereby creating a pressure difference between the outer and inner sides of each core sleeve and pressing the core sleeve against the corresponding core while elastically deforming the core sleeve.

[0011] Therefore, the present invention relates to a stator for an axial flux motor. An axial flux motor can be equivalently referred to, for example, an axial air gap motor, a generator, or an axial flux permanent magnet motor. An axial flux motor is a type of motor in which magnetic flux is generated in an axial direction, the direction of the axis of rotation. Typically, depending on the operating conditions, the motor is adapted to operate as a motor and as a generator. An axial flux motor has at least one stator and at least one rotor. The rotor comprises a magnetic material (typically a permanent magnet) that generates axial magnetic flux. During operation, the stator remains stationary, while the rotor, mounted on the shaft, rotates during motor operation. Typically, both the stator and rotor comprise disc-shaped or annular components, referred to as stator discs and rotor discs, respectively. The stator discs and rotor discs are axially spaced apart by a narrow air gap. Different topologies are possible. For example, the motor may include one rotor disc and one stator disc, one rotor disc and two stator discs, or two rotor discs and one stator disc. The axial flux motor may be a toroidal type with a stator yoke or a YASA type without a stator yoke. YASA type motors are also known as, for example, yokeless and segmented armature (YASA) motors or generators, or simply yokeless axial flux motors.

[0012] The stator comprises multiple stator components arranged typically in a rotationally symmetrical manner with respect to a central axis. Each stator component includes a coil and a core made of a ferromagnetic material, each coil having a central axis in the axial direction. The coil comprises multiple turns wound around the ferromagnetic core. During motor operation, the rotor is driven by a magnetic field generated by stator currents flowing in the coils, while in generator mode, current is induced in the stator coils due to the rotation of the rotor. In one embodiment, each core may include an elongated central portion (e.g., referred to as a core rod) and pole shoes positioned at two opposite ends of the core rod. In another embodiment, such pole shoes are absent.

[0013] The stator also includes a housing, which comprises a top wall, a bottom wall, and two circumferential walls. The top and bottom walls serve as opposing cover plates and are typically configured as two parallel disc-shaped walls. The top and bottom walls are connected by circumferential walls extending in the axial direction, one circumferential wall positioned at the outer circumference and the other at the inner circumference. The stator member is positioned between the inner and outer circumferential walls. In one embodiment, the stator core is entirely located inside the stator housing and therefore does not extend through the top and bottom walls. In another embodiment, the stator core extends through holes provided in the top and bottom walls. Thus, in the latter case, when two rotor discs are positioned on opposite sides of the stator discs, the end face of the ferromagnetic core contacts the air gap, and the end face is the surface of the ferromagnetic core facing the two respective rotors. In any embodiment, the housing thus surrounds the stator member, although in certain embodiments, the stator member may contact the surrounding environment of the housing via the aforementioned holes.

[0014] In addition to the top wall, bottom wall, and circumferential wall, the stator housing may also include internal structures. For example, the stator housing may include inner walls positioned between adjacent stator components, for example, to guide stator cooling fluid. Typically, such guide walls extend in both radial and axial directions. The inner wall or guide wall may connect the bottom wall and the top wall. In another embodiment, no such guide wall or other type of internal structure is present.

[0015] The stator housing also includes one or more ports adapted for supplying cooling fluid. During operation, the stator is thus cooled by a liquid, wherein a cooling liquid (e.g., oil or water) is supplied to the interior of the housing via one or more ports. The cooling liquid thus circulates between the stator components, thereby contacting the coils and extracting heat from the stator components.

[0016] Each stator component includes a core sleeve positioned between the core and the coil. The sleeve is a hollow structure in which the core is placed inside the hollow sleeve. Therefore, the sleeve is positioned around the core, and the coil is positioned around the sleeve. The side of the sleeve facing the core is called the inner side, and the side of the sleeve facing the coil is called the outer side.

[0017] Each core sleeve comprises a flexible or elastic material. A flexible material is a non-rigid material that can be easily deformed without breaking or leaving any plastic deformation. For example, it is an elastic material (like a synthetic elastomer or fabric). An elastic material is a stretchable material, that is, a material that tends to return to its initial shape after being stretched by an external force. Elastic materials are, for example, elastic polymers, elastomers, elastically deformable plastics, or rubbers. For example, the fact that the sleeve is supplied in the form of a flexible or elastic material means that each sleeve is entirely made of a flexible or elastic material.

[0018] For each stator component, a core sleeve extends at least partially between a top wall and a bottom wall. This means the core sleeve extends axially and can be positioned completely or partially between the top and bottom walls. In one embodiment, one end of the core sleeve is connected to the top wall of the housing, and the other end is connected to the bottom wall. In another embodiment, one end of the core sleeve is connected to a first pole shoe of the core, and the other end is connected to a second pole shoe of the core. Multiple core sleeves present within the stator housing together define a cavity within the housing, located outside the respective core sleeves and, for example, hydraulically sealed. In addition to the outer surfaces of the core sleeves, the cavity is also defined by a bottom wall, a top wall, and a circumferential wall. In possible embodiments, the cavity may also be defined by multiple portions of the core or by internal guide walls positioned between adjacent stator components.

[0019] The cavity defined by the core sleeve and the stator housing is adapted to receive cooling fluid, which is supplied via one or more ports in the housing. As the cooling fluid is supplied to the inner cavity of the housing, it flows outside the core sleeve. For each stator component, at least some of the consecutive turns of the coil are spaced apart, thereby leaving some space between two adjacent turns. Thus, the fluid passage is defined toward the core sleeve, meaning that as the cooling fluid flows within the cavity, the fluid can flow between the consecutive coil turns, thereby reaching the sleeve.

[0020] Therefore, the pressurized cooling fluid supplied to the cavity causes the fluid to reach the outside of the sleeves, creating a pressure difference between the outside and inside of each core sleeve. The stator design thus maintains a low pressure inside the sleeves during operation, while the flowing cooling fluid causes a higher pressure on the outside. Due to this pressure difference, the core sleeves press against the corresponding cores. Specifically, because each core sleeve comprises an elastic material, the pressure difference causes the core sleeve to elastically deform when pressed against the corresponding core. Thus, under the influence of the cooling fluid, the sleeves elastically deform, and after the fluid pressure is removed, the sleeves return to their initial shape without permanent deformation. When the core sleeves press against the cores, for example, due to irregularities at the core surface or because the cross-section of the sleeve is slightly larger than the cross-section of the core, any gaps that existed between the core and the corresponding sleeve before the supply of cooling fluid will close. In other words, under the influence of the cooling fluid, the sleeves conform to the shape of the cores, thereby closing any gaps that might have existed between the core and the sleeves before the supply of cooling fluid. Furthermore, during manufacturing, the sleeve can be stretched before sliding onto the core, allowing for a tight fit between the sleeve and the core. Even when this tight fit is applied, for example, due to irregularities on the surface of the core, a small gap can still be maintained between the sleeve and the core.

[0021] This invention offers several advantages. First, because the sleeve presses against the core during motor operation, there is no gap between the sleeve and the corresponding core, and no static cooling fluid can remain between the core and the corresponding sleeve. This helps improve heat transfer from the core to the cooling fluid, thereby increasing cooling efficiency and motor power. It also facilitates stator assembly, as the sleeve can be slightly larger to compensate for manufacturing variations, thus ensuring the sleeve fits snugly onto the core and preventing damage to either the core or the sleeve during assembly. Preventing damage to either the core or the sleeve during assembly is particularly relevant when the core is divided into two parts, necessitating that individual core portions be slid into the sleeve during assembly, thereby risking damage to the sharp edges at the interface of the core portions.

[0022] Secondly, the core sleeve design of this invention allows the sleeve to be positioned so that the coil and core are completely shielded, thereby preventing potential arcing. This results in improved electrical insulation, thus ensuring safe operation of the motor (even under high voltage). In summary, this invention ensures the required electrical insulation while allowing for optimal cooling of the stator components.

[0023] Finally, the solution of the present invention contributes to improved sealing of liquid-cooled stators. In effect, the sleeves together define a cavity inside the housing in which the cooling fluid flows, and this cavity can be easily sealed. This means that a completely closed disc wall covering the ferromagnetic core is not required to achieve a liquid seal. Therefore, a stator design can be used where the core extends through holes in the top and bottom plates, thereby allowing for less stringent manufacturing deviations relative to the mechanical air gap and reducing the risk of rotor-stator collision. Furthermore, the sleeves (e.g., by means of adhesive) can be easily sealed relative to the housing and / or the core, resulting in a more reliable seal when the seal will depend on different materials for molding the core and the disc wall.

[0024] Optionally, according to claim 2, the pressure difference causes any gaps that existed between the sleeve and the corresponding core before the supply of cooling fluid to close while simultaneously pressing the sleeve against the corresponding core. Prior to the supply of cooling fluid, gaps may potentially exist, for example, due to irregularities in the core surface, manufacturing deviations, or the expected gap between the sleeve and the core required to allow the sleeve to slide over the core.

[0025] Optionally, according to claim 3, the cavity defined by the outer side of the core sleeve and the housing is hydraulically sealed, thereby preventing cooling fluid from flowing toward the inner side of the core sleeve. The sealing of the sleeve can be relative to the housing and / or relative to the core. Because the cavity is sealed, no cooling fluid can enter between the sleeve and the corresponding core, thus allowing a pressure difference between the outer and inner sides of the corresponding sleeve.

[0026] Optionally, according to claim 4, each core sleeve is hydraulically sealed at both ends relative to the housing and / or relative to the core. Each core sleeve extends in the axial direction and has two opposite ends, namely, a top end at the top wall side and a bottom end at the bottom wall side. The two sleeve ends are hydraulically sealed, for example, by providing adhesive or rubber material between the sleeve end and the housing wall or between the sleeve end and the pole shoe of the core, or by pressing the core sleeve ends against the housing or the core.

[0027] Optionally, according to claim 5, each core sleeve is connected to the bottom wall and top wall and / or connected to the core, such that the cavity is at least partially defined by the outer side, circumferential wall, and top and bottom walls of the core sleeve. In an embodiment, the cavity within the housing is defined only by the outer side, two circumferential walls, and top and bottom walls of the plurality of core sleeves. Furthermore, the cavity may be defined by the outer side of a guide wall positioned between adjacent stator members. In another embodiment, the cavity within the housing is defined by the outer side, two circumferential walls, top and bottom walls, and a portion of the core of the plurality of core sleeves. Furthermore, the cavity may be defined by the outer side of a guide wall positioned between adjacent stator members.

[0028] Optionally, according to claim 6, each core sleeve is hydraulically sealed at both ends at the locations where it connects to the top and bottom walls and / or to the core. For example, the connection is provided by adhesive, which also ensures a liquid-sealed connection.

[0029] Optionally, according to claim 7, the housing includes guide walls, any of which are positioned between adjacent stator members and extend between the top and bottom walls, the sides of which help define the cavity. The guide walls (also referred to as inner walls or radial walls) form part of the internal structure of the stator housing. The guide walls are positioned between the top and bottom walls of the housing, thereby extending in the axial direction, and are positioned between two adjacent stator members, thereby extending in the radial direction. The guide walls define fluid passages, allowing cooling fluid to flow between the coils and the respective guide walls. Typically, such guide walls help guide the cooling fluid, for example, causing the fluid to flow against the coils. When guide walls are present, their sides or multiple portions of their sides form the boundaries of the cavity within the stator housing. For example, in an embodiment, the cavity within the housing is defined by the outer sides of multiple core sleeves, two circumferential walls, the top and bottom walls, and the outer sides of the radial walls.

[0030] Optionally, according to claim 8, each core sleeve comprises a polymer material. For example, the core sleeve is made of an elastically deformable type or plastic, rubber, etc.

[0031] Optionally, according to claim 9, the polymer material includes a thermally conductive filler. A thermally conductive filler can be added to the polymer material of the sleeve to enhance the thermal conductivity of the sleeve material. This helps to improve heat extraction from the core.

[0032] Optionally, according to claim 10, the turns of the coil have a tapered cross-section, such that there is a gap between the turns of the coil having a V-shaped cross-section, the size of which gradually decreases in the direction toward the core. This has the advantage that the flow of cooling liquid toward the core sleeve is increased, thereby helping to improve heat extraction from the core.

[0033] Optionally, according to claim 11, the top wall and the bottom wall each include a plurality of holes adapted to receive a corresponding core, such that in the installed state, the core extends through the corresponding hole. Thus, the end face of the ferromagnetic core contacts the air gap and is not covered by the top or bottom wall. In embodiments, a seal (e.g., by adhesive) may be present between the corresponding core and the top wall, and between the corresponding core and the bottom wall.

[0034] In one embodiment, each core includes a central portion extending in the axial direction, the central portion being laterally divided into at least two separate portions, the separate portions being mechanically connected to each other in the installed state.

[0035] In one embodiment, each core includes a pole shoe on the opposite side of the central portion, the pole shoe being adapted to interlock with the top and bottom walls, thereby securing the core to the housing.

[0036] In one embodiment, the cores are interconnected by a ferromagnetic stator yoke. In another embodiment, the stator is yokeless.

[0037] According to a second aspect of the invention, the above-mentioned objective is achieved by an axial flux motor as defined in claim 12, which includes a stator according to a first aspect of the invention.

[0038] According to a third aspect of the invention, the object specified above is achieved by a method for operating the stator of an axial flux motor as defined in claim 13, the method comprising: - A stator for an axial flux motor, comprising: ○ Central axis: During installation, the central axis corresponds to the rotation axis of the axial flux motor in the axial direction; ○ Multiple stator components arranged rotationally symmetrically about a central axis, wherein each stator component includes: ■ Ferromagnetic core; ■ A coil comprising multiple turns wound around a core; ■ Core sleeve, which is placed between the core and the coil, having an inner side facing the core and an outer side facing the coil; ○ A housing surrounding the stator component, the housing including a top wall, a bottom wall, an inner circumferential wall, and an outer circumferential wall extending between the top wall and the bottom wall. For each of the stator components: ○ The core sleeve extends between the top and bottom walls, thereby defining a cavity within the housing, and ○ At least some of the consecutive turns of the coil are spaced apart, thereby defining a fluid passage, and ○ The core sleeve may be made of elastic or flexible material; - Cooling fluid under pressure is supplied to the housing through one or more ports in the housing; - Allows the cooling fluid to flow within the cavity, outside the core sleeve; - This allows the cooling fluid to flow through the fluid passage toward the outside of the core sleeve, thereby creating a pressure difference between the outside and inside of each core sleeve; - Due to the pressure difference established between the outer and inner sides of each core sleeve, after the supply of cooling fluid, the core sleeve is pressed against the corresponding coil while being elastically deformed. Attached Figure Description

[0039] Figure 1 The illustration shows a stator and two rotor disks according to an embodiment of the present invention.

[0040] Figure 2 The illustration shows a stator according to an embodiment of the present invention, in which the top wall of the stator has been removed.

[0041] Figure 3 The illustration shows liquid cooling of a stator according to an embodiment of the present invention.

[0042] Figures 4 to 9 Each is given a cross-section of the stator based on a bending plane parallel to the axial direction, thereby illustrating different embodiments of the core sleeve arrangement according to the invention. Detailed Implementation

[0043] Figure 1The diagram illustrates the stator 100 and rotor of an axial flux motor. Two rotor disks 101 and 102 are positioned on either side of the stator disk 100. The stator disk 100 is axially spaced from the first rotor disk 101 by a first air gap 103, and from the second rotor disk 102 by a second air gap 104. The stator disk 100 and rotor disks 101 and 102 have a central axis, labeled "X" in the diagram, corresponding to the axis of rotation of the motor in the axial direction. Both rotor disks 101 and 102 include a magnet 108. The magnet 108 generates magnetic flux in the axial direction X.

[0044] Figure 2 A stator 100 is shown, with its top wall 111 removed. The stator 100 includes a plurality of stator members 200 arranged rotationally symmetrically about a central axis. Each stator member 200 includes a coil or winding 106 wound around a ferromagnetic core 105 extending in an axial direction. The stator housing includes a bottom wall 110 and a top wall 111, which are configured as disc-shaped walls perpendicular to the axial direction 115 and serve as cover plates. The stator housing also includes an inner circumferential wall 112 and an outer circumferential wall 113, both extending in the axial direction and connecting the bottom wall 110 to the top wall 111. Furthermore, the stator housing includes an inner wall or guide wall 107, any guide wall 107 extending in both axial and radial directions and positioned between two adjacent stator members 200. The guide wall 107 is connected to the outer circumferential wall 113 at one end. In the axial direction, the guide wall 107 extends between the bottom wall 110 and the top wall 111, thereby connecting the two cover plates 110, 111.

[0045] The outer circumferential wall 113 includes outer channels 201, 202, while the space between the endpoints of the guide wall and the inner circumferential wall 112 defines an inner channel 203. Channels 201, 202, 203 form part of a cooling circuit for stator cooling (intended for liquid cooling of stator components 200). This stator cooling scheme is known in the prior art and is described, for example, in EP3764526A1. The outer channel 201 and inner channel 203 are arranged to allow stator cooling fluid to flow tangentially about a central axis. On the other hand, the guide wall 107 is arranged to allow stator cooling fluid to flow in a radial direction. For this purpose, a radial fluid passage is provided between each coil 106 and the adjacent radial wall 107. The cold channel 201 includes a supply port 300, which is not located in... Figure 1 and Figure 2 As shown in the text, but Figure 3 As can be seen in the text. Figure 3The stator fluid circulation, indicated by arrows, is schematically illustrated. In channel 201, cooling fluid circulates tangentially. The cooling fluid enters the interior of the stator housing via supply port 300 (see arrow 301), and is then guided radially toward the inner circumference (see arrow 302). As it flows through the radial fluid passage, the fluid is guided by the radial wall 107, thus being forced against and flowing through the coils 106 to dissipate heat from them. The fluid is then collected in inner channel 203. For adjacent stator components, radial flow occurs in the opposite direction (from the inner circumference to the outer circumference, see arrow 303). The heated fluid is collected in hot channel 202, which is connected to a port for discharging the stator cooling fluid.

[0046] Figures 4 to 8 The illustration shows a first embodiment of the core sleeve arrangement according to the present invention. Figures 4 to 6 In the middle, the stator housing 100 includes a guide wall 107, and... Figure 1 and Figure 2 The same as in, and in Figures 7 to 8 The diagram shows a variation without guide walls. Figure 9 The illustration shows a second embodiment of the core sleeve arrangement according to the present invention.

[0047] Figure 4 A sleeve 109 is shown, having a top end portion 402 on the top wall 111 side and a bottom end portion 401 on the bottom wall 110 side. The sleeve 109 is positioned between a core 105 and a coil 106, with the outer side of the sleeve 109 facing the coil 106 and the inner side of the sleeve 109 facing the core 105. The height of the sleeve 109, measured in the axial direction, is greater than the height of the coil 106, thereby shielding the core 105 from the coil 106. A radial wall 107 is placed between any pair of adjacent coils 106 and connects the top wall 111 to the bottom wall 110. The core 105 extends through holes 400 in the top wall 111 and the bottom wall 110, such that the end face of the core 105 contacts the corresponding air gaps 103, 104. The sleeve 109 extends in the axial direction, with its two ends 401, 402 connected to the bottom wall 110 and the top wall 111, respectively. The sleeve is mainly positioned between the top wall 111 and the bottom wall 110, but due to the recess 403 in the walls 110 and 111, the sleeve is not completely positioned between the top wall 111 and the bottom wall 110.

[0048] The core sleeve 109 is sealed at both ends 401 and 402 relative to the top wall 111 and the bottom wall 110. Figure 5The figure illustrates a possible manner in which such a hydraulic seal is provided. In this embodiment, sleeve end 401 is connected to bottom wall 110 by means of adhesive 501, and sleeve end 402 is connected to top wall 111 by means of adhesive 500, wherein the adhesive ensures a hydraulic seal. As can be seen in the figure, adhesives 500 and 501 also extend between core 105 and top wall and between core 105 and bottom wall, respectively, thereby also sealing core 105 relative to the housing wall.

[0049] In this way, a hydraulically sealed cavity 600 is obtained inside the stator housing, such as... Figure 6 As further illustrated, cavity 600 is defined by the outer side 604 of core sleeve 109, the side side 605 of guide wall 107, top wall 111, bottom wall 110, and circumferential walls 112, 113. Cavity 600 is adapted to receive cooling fluid supplied via port 300. Figure 6 The diagram also illustrates a space 603 between the consecutive turns of coil 106. For illustrative purposes, space 603 appears excessively large in the diagram.

[0050] Before cooling fluid is supplied to cavity 600, a gap 601 exists between sleeve 109 and core 105, for example, due to the large size of sleeve 109 relative to core 105. When cooling fluid (such as oil or water) is supplied to cavity 600, fluid flows at the outer side 604 of sleeve 109, and thus between sleeve 109 and guide wall 107. Due to hydraulic sealing, no fluid enters between the inner side 606 of sleeve 109 and core 105. Therefore, a pressure difference exists between the outer side 604 and the inner side 606 of sleeve 109. During flow, cooling fluid enters the gap 603 between multiple turns, which define a fluid passage 602 toward sleeve 109. In the illustrated embodiment, sleeve 109 is made of an elastic type of plastic, such that sleeve 109 elastically deforms and presses against core 105. Therefore, the gap 601 initially present between the core 105 and the sleeve 109 is closed, thereby achieving improved heat extraction from the core 105. It is worth noting that in Figure 6 The deformed state of the sleeve 109 is not shown in the figure, wherein the gap between the sleeve 109 and the core 105 is closed.

[0051] It is worth noting that, in Figure 5 and Figure 6 In one embodiment, a pressure difference occurs on the sleeve due to the pressurized fluid flowing in the cavity and reaching the outside of the core sleeve via passage 602, wherein the cavity 600 is hydraulically sealed. In other embodiments, it is possible that the cavity is not perfectly hydraulically sealed, and for example, due to the velocity of the fluid at the outside of the core sleeve or the combination of static and dynamic pressure of the fluid flow at the outside of the sleeve, the pressure difference required for the sleeve to press against the core may still exist.

[0052] Figure 7 Another variation of the stator is shown, in which a method using the same... Figures 4-6 A similar core sleeve arrangement is used. Unlike the previous figures, the stator housing does not include the guide wall 107. In this embodiment, a hydraulically sealed cavity 700 is present, defined by the outer side of the core sleeve 109, the top wall 111, the bottom wall 110, and the circumferential walls 112, 113. Similar to... Figures 4-6 The cavity 700 is adapted to receive cooling fluid, and due to the pressure difference between the outer and inner sides of the sleeve 109, the sleeve 109 presses against the core 105, thereby closing the gap 701 between the sleeve 109 and the corresponding core 105.

[0053] exist Figures 4 to 7 In the illustrations provided, the gaps 601 and 701 between the sleeve 109 and the corresponding core 105 are presented as slits that extend along the height of the sleeve 109. Figure 8 The illustration shows that the gap between the sleeve 109 and the corresponding core 105 can also be presented as a small opening 800, due to the irregularities on the surface of the core 105. Therefore, even when using an elastic sleeve 109 fastened around the core 105, the core sleeve arrangement of the present invention has the advantage of closing any small opening 800 under the influence of the cooling fluid.

[0054] Figure 9 A second embodiment of the core sleeve arrangement is shown. In this embodiment, each core 1105 includes a centrally located core rod 900 and two pole shoes 901, 902. The pole shoes 901, 902 extend through holes in the top wall 111 and bottom wall 110, such that the end faces of the pole shoes 901, 902 contact corresponding air gaps 103, 104. Any sleeve 1109 extends axially and is positioned between the core 1105 and the coil 106. The bottom end of the sleeve 1109 connects to the first pole shoe 901, and the top end of the sleeve 1109 connects to the second pole shoe 902. The sleeve 1109 is sealed relative to the core 1105 and relative to the top wall 111 and bottom wall 110 by means of adhesives 903, 904. Similar to the first embodiment, the sleeve 1109 helps to define a hydraulically sealed cavity within the stator housing. Figure 9 In one embodiment, the cavity is defined by the outer side of the core sleeve 1109, the side of the guide wall 107, the top wall 111, the bottom wall 110, and the circumferential walls 112 and 113.

[0055] Although the invention has been described with reference to specific embodiments, it will be clear to those skilled in the art that the invention is not limited to the details of the illustrative embodiments described above, and that the invention can be practiced with various changes and modifications without departing from its scope. Therefore, these embodiments are to be considered illustrative rather than restrictive in all respects, and the scope of the invention is indicated by the appended claims rather than by the foregoing description, and all variations falling within the meaning and scope of the equivalents of the claims are therefore intended to be included therein. In other words, it is contemplated to cover any and all modifications, variations, or equivalents that fall within the scope of the basic principles and whose essential properties are claimed in this patent application. Furthermore, the reader of this patent application will understand that the words “comprising” or “comprise” do not exclude other elements or steps, the words “a” or “an” do not exclude a plurality, and a single element (such as a computer system, processor, or other integrated unit) can perform the functions of several means recited in the claims. Any reference numerals in the claims should not be construed as limiting the corresponding claims. When used in the specification or claims, the terms "first," "second," "third," "a," "b," "c," etc., are introduced to distinguish similar elements or steps and do not necessarily describe a sequence or chronological order. Similarly, the terms "top," "bottom," "above," "below," etc., are introduced for descriptive purposes and do not necessarily indicate relative positions. It should be understood that the terms thus used are interchangeable where appropriate, and embodiments of the invention can operate in other orders or in directions different from those described or shown according to the invention.

Claims

1. A stator (100) for an axial flux motor, the stator (100) comprising: - Central axis, which, when installed, corresponds in the axial direction to the rotation axis of the axial flux motor; - A plurality of stator components (200) arranged rotationally symmetrically about the central axis, wherein each of the stator components (200) includes: ○ Ferromagnetic core (105); ○ Coil (106), the coil (106) comprising a plurality of turns wound around the core (105); ○ Core sleeve (109), the core sleeve (109) is placed between the core (105) and the coil (106), the core sleeve (109) has an inner side (606) facing the core (105) and an outer side (604) facing the coil (106). - A housing surrounding the stator member (200), the housing including a top wall (111), a bottom wall (110), an inner peripheral wall (112), and an outer peripheral wall (113) extending between the top wall (111) and the bottom wall (110), and the housing also including one or more ports (300) adapted for supplying cooling fluid. Its features are: For each of the stator components (200): - The core sleeve (109) extends at least partially between the top wall (111) and the bottom wall (110) to define cavities (600, 700) in the housing, the cavities (600, 700) being adapted to receive cooling fluid flowing outside the core sleeve (109); - At least some of the continuous turns of the coil (106) are spaced apart, thereby defining a fluid passage (602) toward the core sleeve (109). - The core sleeve (109) comprises an elastic material or a flexible material; The pressurized cooling fluid supplied to the cavities (600, 700) causes the cooling fluid to flow through the fluid passage between the successive turns of the coil (106) and reach the core sleeve (109), thereby creating a pressure difference between the outer and inner sides of each core sleeve (109) and pressing the core sleeve (109) against the corresponding core (105) while elastically deforming the core sleeve (109).

2. The stator (100) according to any one of the preceding claims. in, The pressure difference causes any gaps (601, 800) that existed between the sleeve (109) and the corresponding core (105) before the supply of the cooling fluid to close while pressing the sleeve (109) against the corresponding core (105).

3. The stator (100) according to any one of the preceding claims. in, The cavity (600, 700) defined by the outer side of the core sleeve (109) and the housing is hydraulically sealed to prevent cooling fluid from flowing toward the inner side of the core sleeve (109).

4. The stator (100) according to any one of the preceding claims. in, Each of the core sleeves (109) is hydraulically sealed at both ends (401, 402) relative to the housing and / or relative to the core.

5. The stator (100) according to any one of the preceding claims. in, Each of the core sleeves (109) is connected to the bottom wall (110) and the top wall (111) and / or to the core (105), such that the cavity (600, 700) is at least partially defined by the outer side of the core sleeve (109), the circumferential walls (112, 113), and the top wall (111) and the bottom wall (110).

6. The stator (100) according to claim 5. in, At the connection to the top wall (111) and the bottom wall (110) and / or at the connection to the core (105), each of the core sleeves (109) is hydraulically sealed at both ends (401, 402).

7. The stator (100) according to any one of the preceding claims. in, The housing includes guide walls (107), any one of which is positioned between adjacent stator members (200) and extends between the top wall (111) and the bottom wall (110), the sides of which help define the cavity (600).

8. The stator (100) according to any one of the preceding claims. in, Each of the core sleeves (109) comprises a polymer material.

9. The stator (100) according to claim 8. in, The polymer material includes thermally conductive fillers.

10. The stator (100) according to any one of the preceding claims. in, The turns of the coil (106) have a tapered cross-section, such that there is a gap between the turns of the coil (106) having a V-shaped cross-section, the size of which gradually decreases in the direction toward the core (105).

11. The stator (100) according to any one of the preceding claims. in, Both the top wall (111) and the bottom wall (110) include a plurality of holes (400) adapted to receive a corresponding core (105) such that, in the installed state, the core (105) extends through the corresponding hole (400).

12. An axial flux motor comprising a stator (100) according to any one of the preceding claims.

13. A method for operating the stator (100) of an axial flux motor, comprising: - A stator (100) for an axial flux motor, the stator (100) comprising: ○ Central axis, during installation, the central axis corresponds in the axial direction to the rotation axis of the axial flux motor; ○ A plurality of stator components (200) are arranged rotationally symmetrically about the central axis, wherein each stator component (200) includes: ■ Ferromagnetic core (105); ■ Coil (106), the coil (106) comprising a plurality of turns wound around the core (105); ■ Core sleeve (109), the core sleeve (109) is placed between the core (105) and the coil (106), the core sleeve (109) has an inner side facing the core (105) and an outer side facing the coil (106); A housing surrounding the stator component (200), the housing including a top wall (111), a bottom wall (110), an inner circumferential wall (112), and an outer circumferential wall (113), the circumferential walls (112, 113) extending between the top wall (111) and the bottom wall (110). For each of the stator components (200): ○ The core sleeve (109) extends between the top wall (111) and the bottom wall (110), thereby defining cavities (600, 700) in the housing, and ○ At least some of the consecutive turns of the coil (106) are spaced apart, thereby defining a fluid passage (602), and; ○ The core sleeve (109) comprises an elastic material or a flexible material; - Cooling fluid under pressure is supplied to the housing through one or more ports (300) in the housing; - The cooling fluid flows in the cavity (600, 700) and outside the core sleeve (109); - The cooling fluid flows through the fluid passage (602) toward the outside of the core sleeve (109), thereby creating a pressure difference between the outside and inside of each core sleeve (109); - Due to the pressure difference established between the outer and inner sides of each core sleeve (109), after the cooling fluid is supplied, the core sleeve (109) is pressed against the corresponding core (105) while elastically deforming the core sleeve (109).

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