MAGNETIC DIRECT COOLING WITH FLOW RESTRICTION HOLES IN A SHEET METAL DESIGN TO REDUCE ROTATIONAL LOSS

Abstract

An electric machine rotor comprises a rotor body formed from stacked laminations with aligned magnetic slots and central apertures defining a shaft slot. A shaft within the slot has radial apertures connected to an axial channel. A first subset of laminations defines a primary fluid passage with sections oriented radially and axially to guide fluid to the magnetic slots. The fourth section of the passage has a triangular cross-section to divide the fluid flow evenly. A second subset of laminations defines a secondary fluid passage with similar features. The rotor contains eight radial apertures evenly spaced around the shaft circumference, with laminations having openings aligned with these apertures to regulate fluid flow, thus improving cooling and reducing rotational losses.

Description

BACKGROUND

[0001] The disclosure in question relates to vehicles and in particular to motors with internal permanent magnets with improved cooling mechanisms and features of reduced rotational loss.

[0002] Electric motors, especially internal permanent magnet motors (IPM motors), are widely used in various applications due to their high efficiency and power density. These motors use permanent magnets embedded in the rotor to generate a magnetic field that interacts with the stator windings to produce torque. However, IPM motors often face challenges related to efficient cooling and reducing rotational energy losses, commonly referred to as rotational loss.

[0003] Conventional designs typically circulate oil through the rotor to cool the internal components containing the magnets. However, this approach may not adequately cool the magnets or optimize rotational energy efficiency. The oil may not effectively reach the magnets, resulting in suboptimal cooling and potential overheating. Furthermore, the distribution of oil within the rotor can negatively impact the motor's rotational energy efficiency, as the oil may not be optimally circulated to reduce friction and other drag forces.

[0004] Existing solutions do not necessarily provide a mechanism to control the distribution of oil between the rotor and the magnets, resulting in cooling inefficiencies and increased rotational energy losses. Uneven cooling can occur, with some areas receiving excessive oil while others remain insufficiently cooled. Furthermore, the inability to regulate oil flow can lead to increased rotational losses, negatively impacting the overall performance and reliability of the motor.

[0005] German patent application DE 10 2023 206 887 A1 discloses an electric machine with a rotor and a rotor shaft rotatable about a rotor axis. The rotor shaft has a shaft cooling channel and a rotor body arranged on the rotor shaft, which has several rotor poles, each with at least one V-shaped, C-shaped, or arc-shaped magnet pocket containing several magnets. At least one pocket cooling channel is formed in each magnet pocket, which is fluidically connected to the shaft cooling channel and is provided for cooling at least one magnet in the magnet pocket. The respective pocket cooling channel can be formed in the central region or in one of the edge regions of the magnet pocket, as a cavity in the filler material, as an embedded separate cooling tube, or between a narrow side of the magnet and a tube half-shell embedded in the filler material.

[0006] US Patent 2016 / 0036276 A1 describes another rotor for a rotating electric machine, comprising a rotor core, a shaft with a coolant flow channel and a coolant supply port, and a magnet arranged along the axis of the rotor core. The rotor core has a coolant flow path comprising a first flow channel along the axial direction near the magnet and a second flow channel, which connects the coolant supply port of the shaft to the first flow channel and is formed by overlapping, differently positioned slots in the steel plates. The first and second flow channels meet in the axial intermediate region of the rotor core, with the second flow channel being branched and radially symmetrical.

[0007] Another rotor of a rotating electric machine, comprising a rotor core, a permanent magnet embedded in the rotor core and a rotating shaft, wherein the shaft contains a shaft coolant passage through which a coolant flows, is described in DE 10 2016 211 872 A1.

[0008] From DE 10 2020 204 467 A1, a rotor for an electric machine is known, comprising a rotor shaft and a laminated core attached to the rotor shaft. Cooling channels are arranged within the laminated core, extending radially outwards from the rotor shaft.

[0009] Accordingly, there is a need for a design that allows precise control of the oil flow to the magnets and rotor, thereby improving cooling efficiency and reducing rotational energy losses. Such a design would enable better temperature management of the magnets and improve overall motor performance, ensuring optimal operation and motor longevity. SUMMARY

[0010] According to one aspect of the present invention, a rotor for an electric machine comprises a rotor body formed from several stacked laminations defining a first axial end and an opposing second axial end, each of the several stacked laminations having several magnetic slots aligned through the rotor body and central apertures aligned to define a shaft slot. The rotor also includes a shaft arranged in the shaft slot, and the shaft has several radial apertures fluidically connected to an axial channel arranged in the shaft. A first subset of the several stacked laminations contains openings defining a first fluid passage, which includes a first section extending radially away from the shaft from a first aperture of the several radial apertures.The first fluid passage also includes a second section extending from the first section in an axial direction to the first axial end, a third section extending from the second section in a radial direction away from the shaft, a fourth section extending from the third section in an axial direction to the second axial end, a fifth section extending from the fourth section to a first magnetic slot of the multiple magnetic slots, and a sixth section extending from the fourth section to a second magnetic slot of the multiple magnetic slots.

[0011] According to another aspect, the rotor contains the fourth section of the first fluid passage, which has a cross-sectional shape that is triangular and has a first, a second and a third side, the first side being generally parallel to the second section of the first fluid passage, the fifth section extending from the second side and the sixth section extending from the third side.

[0012] According to yet another aspect, the rotor has a cross-sectional shape in the fourth section of the first fluid passage that is configured to evenly distribute the fluid flowing through the fourth section to the fifth and sixth sections during the operation of the electric machine.

[0013] According to another aspect, the rotor contains the first subset of several stacked laminations, which have a first lamination containing an opening configured to be aligned with the first aperture, with dimensions of the opening configured to regulate a flow of fluid through the first fluid passage.

[0014] According to yet another aspect, the rotor contains a second subset of the multiple stacked laminations, which have openings defining a second fluid passage, comprising a first section extending radially away from the shaft from a second aperture of the multiple radial apertures, a second section extending axially from the first section to the second axial end, a third section extending radially away from the shaft from the second section, a fourth section extending axially from the third section to the first axial end, a fifth section extending from the fourth section to a third magnetic slot of the multiple magnetic slots, and a sixth section extending from the fourth section to a fourth magnetic slot of the multiple magnetic slots.

[0015] According to another aspect, the rotor contains the second subset of the multiple stacked laminations, which is arranged adjacent to the first subset of the multiple stacked laminations.

[0016] According to yet another aspect, the rotor contains several radial apertures, which have eight apertures evenly spaced around the circumference of the shaft.

[0017] According to another aspect, the rotor contains the several stacked laminations, which have a first lamination with four openings configured to be aligned with the first four of the eight apertures.

[0018] According to yet another aspect, the rotor contains the several stacked laminations, which have a second lamination with four openings, each configured to be aligned with the second four of the eight apertures.

[0019] According to another aspect, the rotor contains at least two of the first four apertures that are immediately adjacent to each other.

[0020] According to a further aspect, an electric machine comprises a stator and a rotor rotatably mounted within the stator. The rotor has several stacked laminations defining a first axial end and an opposite second axial end. Each of the stacked laminations has several magnetic slots aligned through a rotor body and central apertures aligned to define a shaft slot. The rotor also includes a shaft located within the shaft slot, and the shaft has several radial apertures fluidically connected to an axial channel located within the shaft. A first subset of the stacked laminations contains openings defining a first fluid passage, which includes a first section extending radially away from the shaft from a first of the multiple radial apertures.The first fluid passage also includes a second section extending from the first section in an axial direction to the first axial end, a third section extending from the second section in a radial direction away from the shaft, a fourth section extending from the third section in an axial direction to the second axial end, a fifth section extending from the fourth section to a first magnetic slot of the multiple magnetic slots, and a sixth section extending from the fourth section to a second magnetic slot of the multiple magnetic slots.

[0021] According to another aspect, the electric machine contains the fourth section of the first fluid passage, which has a cross-sectional shape that is triangular and has a first, a second and a third side, the first side being generally parallel to the second section of the first fluid passage, the fifth section extending from the second side and the sixth section extending from the third side.

[0022] According to yet another aspect, the electric machine contains the shape of the fourth section of the first fluid passage having a cross-sectional shape that is configured to evenly divide, during the operation of the electric machine, a fluid flowing through the fourth section into the fifth section and the sixth section.

[0023] According to another aspect, the electric machine contains the first subset of several stacked laminations, which have a first lamination containing an opening configured to be aligned with the first aperture, with dimensions of the opening configured to regulate a flow of fluid through the first fluid passage.

[0024] According to yet another aspect, the electric machine contains a second subset of the multiple stacked laminations, which have openings defining a second fluid passage, comprising a first section extending radially away from the shaft from a second aperture of the multiple radial apertures, a second section extending axially from the first section to the second axial end, a third section extending radially away from the shaft from the second section, a fourth section extending axially from the third section to the first axial end, a fifth section extending from the fourth section to a third magnetic slot of the multiple magnetic slots, and a sixth section extending from the fourth section to a fourth magnetic slot of the multiple magnetic slots.

[0025] According to another aspect, the electric machine contains the second subset of the multiple stacked laminations, which is arranged adjacent to the first subset of the multiple stacked laminations.

[0026] According to yet another aspect, the electric machine contains several radial apertures, which have eight apertures evenly spaced around the circumference of the shaft.

[0027] According to another aspect, the electric machine contains the several stacked laminations, which have a first lamination with four openings configured to be aligned with the first four of the eight apertures.

[0028] According to yet another aspect, the electric machine contains the several stacked laminations, which have a second lamination with four openings, each configured to be aligned with the second four of the eight apertures.

[0029] According to another aspect, the electric machine contains at least two of the first four apertures that are immediately adjacent to each other.

[0030] The features and advantages described above, and further features and advantages of the disclosure, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Further features, advantages and details appear only as examples in the following detailed description, which refers to the drawings; they show: Fig. 1 a schematic diagram of a vehicle for use in conjunction with one or more embodiments of the present disclosure; Fig. 2A a lamination design of a first lamination of a rotor body in conjunction with one or more embodiments of the present disclosure; Fig. 2B a lamination design of a second lamination of a rotor body in conjunction with one or more embodiments of the present disclosure; Fig. 2C a lamination design of a core lamination of a rotor body in conjunction with one or more embodiments of the present disclosure; Fig. 2D a side view of a rotor stack illustrating an arrangement of laminations in connection with one or more embodiments of the present disclosure; Fig. 3 a composite view of a stack of laminations comprising a first lamination, a second lamination and one or more core laminations, in conjunction with one or more embodiments of the present disclosure; Fig. 4 a schematic diagram of a rotor shaft with radial apertures for oil distribution; Fig. 5 a cross-sectional view of the rotor arrangement showing the oil flow paths through the rotor and magnetic slots in conjunction with one or more embodiments of the present disclosure; Fig. 6A a cross-sectional view of the rotor arrangement showing the oil flow through a first fluid passage through the rotor body and rotor shaft in conjunction with one or more embodiments of the present disclosure; Fig. 6B a cross-sectional view of the rotor arrangement showing the oil flow through a second fluid passage through the rotor body and rotor shaft in conjunction with one or more embodiments of the present disclosure; and Fig. 7A, Fig. 7B, Fig. 7C, Fig. 7D Sheet metal designs of a rotor body in connection with one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0032] The following description is merely exemplary and is not intended to limit the present disclosure, its application, or uses. It should be understood that, throughout the drawings, corresponding reference numerals denote similar or corresponding sections and features.

[0033] Electric motors, especially internal permanent magnet (IPM) motors, often face significant challenges in achieving efficient cooling and minimizing rotational losses. Cooling internal components such as magnets is crucial for maintaining optimal motor performance and longevity. Conventional cooling methods typically involve circulating oil through the rotor, which may not effectively reach the magnets, resulting in suboptimal cooling and potential overheating. Furthermore, the distribution of oil within the rotor can affect a motor's rotational energy efficiency, commonly referred to as rotational loss.

[0034] Existing solutions in the field of internal permanent magnet motors generally lack mechanisms to precisely control the distribution of oil between the rotor and the magnets. This can result in uneven cooling, with some areas receiving excessive oil while others remain insufficiently cooled. Furthermore, the inability to regulate oil flow can lead to increased rotational energy losses, as the oil does not need to be optimally guided to reduce friction and other resistance forces. These inefficiencies can negatively impact the overall performance and reliability of a motor.

[0035] The present design addresses these challenges by introducing a novel internal permanent magnet rotor arrangement that incorporates specific features into the rotor laminations, end rings, and shaft. This design allows oil entering the rotor shaft to be divided between a path directly to the magnets and a path through the rest of the rotor. The oil is fed to the rotor via the shaft's inner diameter and radially drilled holes in the shaft that guide the oil to the rotor. The lamination features create a flow path that allows some of the oil to penetrate the magnet slots, while the remainder flows between the inner diameter channels and the shaft's outer diameter.

[0036] The lamination embossing design and the stacking of the laminations in specific rotational orientations create the oil flow path to the magnet slots. The size of the opening that allows oil to enter the magnet slots can be modified to control the amount of oil directed to the magnets. The remaining oil moves axially between the inner diameter and the shaft's outer diameter and exits through openings in the end rings that clamp the inner diameter. This design provides a mechanism for precise control of the oil distribution, improving cooling efficiency and reducing rotational losses.

[0037] Now, with reference to Fig. Figure 1 shows a schematic diagram of a vehicle 100 for use in conjunction with one or more embodiments of the present disclosure. The vehicle 100 includes a charging port 102, a battery 104, and an electric motor 106. In one embodiment, the vehicle 100 is a hybrid vehicle that uses both an internal combustion engine and an electric motor. In another embodiment, the vehicle 100 is an electric vehicle that uses only electric motors. In exemplary embodiments, the vehicle 100 is configured to be connected, via the charging port 102, to a high-voltage power source (i.e., a voltage source of at least 200 volts (V)), which is used to charge the battery 104. The electric motor 106 is configured to receive energy from the battery 104 to provide propulsion for the vehicle 100.In exemplary embodiments, the battery 104 is configured to supply direct current (DC) power to an inverter (not shown), which converts the DC power into three-phase alternating current (AC) power. The three-phase AC power is supplied to the electric motor 106 to provide propulsion for the vehicle 100.

[0038] Now, with reference to Fig. Figure 2A shows a lamination design of a first lamination 200 of a rotor body according to one embodiment. The first lamination 200 includes magnet slots 201, a central aperture 202, first openings 203, second openings 204, third openings 205, and fourth openings 206. The first lamination 200 forms part of the rotor body and is designed to facilitate cooling and reduce rotational losses in the rotor. The first lamination 200 is one of several laminations stacked to form the rotor body. In exemplary embodiments, the magnet slots 201 are distributed circumferentially around the first lamination 200 and are designed to accommodate the magnets. These slots ensure that the magnets are securely positioned in the rotor body, enabling efficient magnetic interaction with the stator windings. In exemplary embodiments, the central aperture 202 is located at the center of the first lamination 200.This aperture is aligned with the central apertures of further laminations to define a shaft slot that accommodates the rotor shaft.

[0039] In exemplary embodiments, the first opening 203 is positioned radially near the central aperture 202 and is designed to be aligned with a radial aperture in the rotor shaft. This opening allows oil to flow from the shaft to the magnetic slots 201. The second opening 204 is located radially between the central aperture 202 and the magnetic slots 201. The openings of the core lamination rotor body, in combination, define a fluid passage for oil distribution. This fluid passage extends between the first opening 203 and the magnetic slots 201. The third openings 205 and the fourth openings 206 are distributed circumferentially around the first lamination 200 and are designed to further facilitate oil flow within the rotor body. These openings assist in directing the oil to the magnetic slots 201.

[0040] Fig. Figure 2B illustrates a lamination design of a second lamination 210 of a rotor body according to one embodiment. The first lamination 200 contains magnetic slots 201, a central aperture 202, a first opening 203, a second opening 204, third openings 205, and fourth openings 206. In exemplary embodiments, the second lamination 210 has a configuration substantially similar to that of the first lamination 200, rotated about the central aperture by forty-five degrees.

[0041] Now, with reference to Fig. Figure 2C shows a lamination design of a core lamination 220 of a rotor body according to one embodiment. The core lamination 220 includes magnet slots 201, a central aperture 202, a first axial channel opening 207, a second axial channel opening 208, and a recess 209. The magnet slots 201 are distributed around the lamination and are designed to receive the magnets. These slots ensure that the magnets are securely positioned in the rotor body, enabling efficient magnet interaction with the stator windings. The central aperture 202 is located at the center of the lamination. This aperture is aligned with the central apertures of other laminations to define a shaft passage that receives the rotor shaft.

[0042] In exemplary embodiments, the first axial channel opening 207 is part of the axial channel system in the rotor. The first axial channel opening 207 allows oil to flow axially through a section of the rotor body. The second axial channel opening 208 is another component of the axial channel system. In exemplary embodiments, the second axial channel opening 208 has a triangular cross-sectional shape with a first surface that is generally parallel to the first axial channel opening 207. In exemplary embodiments, the recesses 209 are configured to partially overlap with the first opening 203 of one of the first laminations 200 and the second lamination 210 when the core lamination 220 is arranged adjacent to one of the first laminations 200 and the second lamination 210.In exemplary embodiments, the dimensions of the overlap between the first opening 203 and the recess 209 are configured to control the percentage of oil flowing radially into the rotor body and the percentage of oil flowing axially between the rotor body and the rotor shaft.

[0043] Now, with reference to Fig. Figure 2D shows a side view of a rotor stack illustrating an arrangement of laminations in connection with one or more embodiments of the present disclosure. The rotor body 250 comprises several stacked laminations stacked between a first axial end 250-1 and a second axial end 250-2. The rotor body 250 is formed from several stacked laminations comprising a first lamination 200, core laminations 210-1, twisted core laminations 210-2, and the core lamination 220.

[0044] In exemplary embodiments, a rotor body 250 comprises a first subset of stacked laminations 230, which includes one or more twisted core laminations 210-2 arranged between a first lamination 200 and a second lamination 210. The first subset of stacked laminations 230 includes openings such as those shown in Fig. 2A- Fig. Figure 2C shows a first fluid passage that allows an oil flow through a first section of a rotor body to cool the magnets and reduce rotation loss in the rotor.

[0045] In exemplary embodiments, a rotor body 250 also includes a second subset of stacked laminations 240, which contains one or more core laminations 210-1 arranged between a first lamination 200 and a second lamination 210. The first subset of stacked laminations 230 contains openings such as those shown in Fig. 2A- Fig. Figure 2C shows a second fluid passage that allows oil to flow through a second section of a rotor body to cool the magnets and reduce rotational losses in the rotor. In exemplary embodiments, the twisted core laminations 210-2 have the same layout as the core laminations 210-1, except that the twisted core laminations 210-2 have been rotated about the shaft of the rotor body by forty-five degrees.

[0046] In exemplary embodiments, the first subset of stacked laminations 230 is arranged adjacent to the second subset of stacked laminations 240. The first fluid passage is configured to provide an oil flow to a different set of magnets than the second fluid passage. Although the first subset of stacked laminations 230 and the second subset of stacked laminations 240 are illustrated as having three stacked core laminations 210-1 and twisted core laminations 210-2, it is recognized by those skilled in the art that any number of core laminations can be used.

[0047] Now, with reference to Fig. Figure 3 shows a composite view of a stack of laminations comprising a first lamination, a second lamination, and one or more core laminations according to one embodiment. The first opening 203 is positioned near the central aperture and aligned with a radial aperture in the rotor shaft. As illustrated, the recess 209 of the core laminations overlaps with a first end of the first opening 203 of the first lamination. An opposite end of the first opening 203 overlaps with the first axial channel opening 207 of the core laminations. The second opening 204 on the second lamination overlaps with both the first axial channel opening 207 and the second axial channel opening 208.In exemplary embodiments, the second axial channel opening 208 has a triangular shape and includes a first side 208-1, which is generally parallel to the first axial channel opening 207, and a second and a third side 208-2 and 208-3, which extend from the first side 208-1 away from the first axial channel opening 207. In exemplary embodiments, the second side 208-2 of the second axial channel opening 208 overlaps with one of the third openings 205, and the third side 208-3 of the second axial channel opening 208 overlaps with the other of the third openings 205 of the first lamination. Furthermore, each of the third openings 205 of the first lamination overlaps with fourth openings 206 of the second lamination. The fourth openings 206 of the second lamination are configured to connect to the magnetic slots 201.In exemplary embodiments, a combination of the first openings 203, the second openings 204, the third openings 205, the fourth openings 206, the first axial channel opening 207 and the second axial channel opening 208 in the stack of laminations defines a fluid passage extending from the radial aperture in the rotor shaft to the magnet slots 201 to allow an oil flow through the rotor body to the magnets.

[0048] Fig. Figure 4 shows a schematic diagram of a shaft 310 with radial apertures 312 for oil distribution according to one embodiment. In exemplary embodiments, the shaft 310 is a cylindrical component that forms the central axis of the rotor assembly. The shaft 310 is configured to be inserted into the central apertures of the rotor laminations. The shaft 310 includes a central aperture 311 that extends axially through at least one section of the shaft 310 and connects to the radial apertures 312. In exemplary embodiments, several radial apertures 312 are distributed along the circumference of the shaft 310. These apertures are designed to allow oil flow from the shaft 310 to the rotor laminations and the magnet slots.The radial apertures 312 connect the internal axial channel of the shaft 310 to the outer surface, allowing oil to be directed radially outwards to cool the internal components of the rotor assembly. In one embodiment, the shaft 310 contains eight radial apertures 312 evenly distributed around its circumference. In another embodiment, the multiple radial apertures 312 are arranged in a central section of the shaft 310.

[0049] Fig. Figure 5 shows a cross-sectional view of a rotor assembly illustrating the oil flow paths through the rotor body 250. The rotor assembly includes a rotor body 250, a first lamination 302, core laminations 303, a second lamination 304, turned core laminations 305, a shaft 310, radial apertures 312, a first axial channel 314, a radial channel 315, and a second axial channel 316.

[0050] The rotor body 250 forms the central structure of the rotor assembly and is composed of several stacked laminations, including the first lamination 302, core laminations 303, the second lamination 304, and twisted core laminations 305. These laminations are arranged to allow oil flow and improve the cooling efficiency of the rotor assembly. The first lamination 302 is positioned near the central section of the rotor body 250. The first lamination 302 contains openings aligned with the radial apertures 312 in the shaft 310, allowing oil to flow from the shaft 310 into the rotor body 250. The first lamination 302 also helps to direct the oil to the magnetic slots in the rotor body 250.

[0051] In exemplary embodiments, the core laminations 303 are arranged between the first lamination 302 and the second lamination 304. The core laminations 303 have openings that define channels allowing axial oil flow through a section of the rotor body 250. These channels include a first axial channel (not shown) and a second axial channel (not shown) that guide the oil flow through different sections of the rotor body 250. In exemplary embodiments, a first fluid flow channel is defined through the first lamination 302, the core laminations 303, and the second lamination 304. The first fluid flow channel allows fluid flow from a radial aperture 312 of the shaft to a first and a second magnetic slot.In exemplary embodiments, the axial oil flow in the second axial channel 316 ensures a uniform distribution of the oil to the two magnetic slots, which are fluidically connected to the radial channel 315. In exemplary embodiments, when the rotor body 250 rotates, a centrifugal force acts on the oil located in the second axial channel 316, and the geometry of the second axial channel 316 is configured to distribute the oil uniformly to the two magnetic slots, which are fluidly connected to the radial channel 315.

[0052] In exemplary embodiments, the turned core laminations 305 are stacked between the first lamination 302 and the second lamination 304. The turned core laminations 305 have openings that define channels allowing axial oil flow through a section of the rotor body 250. These channels include a first axial channel 314 and a second axial channel 316, which guide the oil flow through different sections of the rotor body 250. In exemplary embodiments, a second fluid flow channel is defined through the first lamination 302, the turned core laminations 305, and the second lamination 304. The second fluid flow channel allows fluid flow from a radial aperture 312 of the shaft to a third and a fourth magnet slot.In exemplary embodiments, the axial oil flow in the second axial channel 316 ensures a uniform distribution of the oil to the two magnetic slots, which are fluidically connected to the radial channel 315. In exemplary embodiments, when the rotor body 250 rotates, a centrifugal force acts on the oil located in the second axial channel 316, and the geometry of the second axial channel 316 is configured to distribute the oil uniformly to the two magnetic slots, which are fluidly connected to the radial channel 315.

[0053] In exemplary embodiments, the shaft 310 is positioned in the central aperture of the rotor body 250. The shaft 310 contains radial apertures 312, see Fig. 4, which allow oil to flow from the internal axial channel of the shaft 310 into the rotor body 250. The radial apertures 312 connect the internal axial channel of the shaft 310 to the outer surface, thus enabling radial oil flow into the rotor body 250.

[0054] Now, with reference to Fig. Figure 6A shows a cross-sectional view of the rotor assembly, illustrating the oil flow through a first fluid passage through the rotor body and rotor shaft in conjunction with one or more embodiments of the present disclosure. The rotor assembly comprises a rotor body 250 formed from several stacked laminations designed to allow oil flow and improve the cooling efficiency of the rotor assembly. The rotor body 250 includes a first fluid passage 603 extending through the rotor body 250 and the shaft 310. The first fluid passage 603 is configured to conduct an oil flow through the rotor body 250 to cool the magnets and reduce rotational losses in the rotor.

[0055] The shaft 310 is positioned in the central aperture of the rotor body 250. The shaft 310 contains several radial apertures 312, which are fluidically connected to an axial channel located within the shaft 310. The radial apertures 312 allow oil to flow from the internal axial channel of the shaft 310 into the rotor body 250. The radial apertures 312 connect the internal axial channel of the shaft 310 to the outer surface, enabling oil to be directed radially outwards to cool the internal components of the rotor assembly.

[0056] The first fluid passage 603 comprises a first section 603-1, which extends from a first aperture of the multiple radial apertures 312 in a radial direction 601 away from the shaft 310. The first section 603-1 of the first fluid passage 603 directs oil radially outward from the shaft 310. The first fluid passage 603 further comprises a second section 603-2, which extends from the first section 603-1 in an axial direction 602 to a first axial end 250-1 of the rotor body 250. The second section 603-2 of the first fluid passage 603 allows axial oil flow through a section of the rotor body 250.

[0057] The first fluid passage 603 also includes a third section 603-3, which extends from the second section 603-2 in the radial direction 601 away from the shaft 310. The third section 603-3 of the first fluid passage directs oil radially outward from the axial channel to the magnet slots. The first fluid passage 603 further includes a fourth section 603-4, which extends from the third section 603-3 of the first fluid passage 603 in the axial direction 602 to the second axial end 250-2 of the rotor body 250. The fourth section 603-4 of the first fluid passage allows axial oil flow through a section of the rotor body 250.

[0058] The first fluid passage 603 contains a fifth section 603-5, which extends from the fourth section 603-4 to a first magnetic slot 610 of the multiple magnetic slots. The fifth section 603-5 directs oil to the first magnetic slot 610 to cool the magnet held therein. The first fluid passage 603 also contains a sixth section 603-6, which extends from the fourth section 603-4 to a second magnetic slot 612 of the multiple magnetic slots. The sixth section 603-6 directs oil to the second magnetic slot 612 to cool the magnet held in the slot.

[0059] In exemplary embodiments, the fourth section 603-4 of the first fluid passage 603 has a triangular cross-sectional shape and comprises a first side, a second side, and a third side. The first side is generally parallel to the second section 603-2 of the first fluid passage 603. The fifth section 603-5 of the first fluid passage 603 extends from the second side, and the sixth section 603-6 of the first fluid passage 603 extends from the third side. The cross-sectional shape of the fourth section 603-4 of the first fluid passage 603 is configured to distribute, during operation of the electric machine, a fluid flowing through the fourth section 603-4 of the first fluid passage 603 evenly between the fifth section 603-5 and the sixth section 603-6 of the first fluid passage 603.

[0060] In exemplary embodiments, the first subset of the multiple stacked laminations includes a first lamination containing an opening configured to be aligned with the first aperture of the multiple radial apertures 312. The dimensions of the opening are configured to regulate the fluid flow through the first fluid passage 603. The first subset of the multiple stacked laminations ensures that the oil flow through the rotor body 250 is efficiently directed to the magnet slots, thereby improving cooling efficiency and reducing rotational losses in the rotor.

[0061] Now, with reference to Fig. Figure 6B shows a cross-sectional view of the rotor assembly, illustrating the oil flow through a second fluid passage through the rotor body and rotor shaft in conjunction with one or more embodiments of the present disclosure. The rotor assembly includes a rotor body 250 formed from several stacked laminations designed to allow oil flow and improve the cooling efficiency of the rotor assembly. The rotor body 250 includes a second fluid passage 605 extending through the rotor body 250 and the shaft 310. The second fluid passage 605 is configured to conduct an oil flow through the rotor body 250 to cool the magnets and reduce rotational losses in the rotor.

[0062] The shaft 310 is positioned in the central aperture of the rotor body 250. The shaft 310 contains several radial apertures which are located in Fig. Figure 4 shows the components that are fluidically connected to an axial channel located in the shaft 310. The radial apertures allow oil to flow from the internal axial channel of the shaft 310 into the rotor body 250. These radial apertures connect the internal axial channel of the shaft 310 to the outer surface, allowing oil to be directed radially outwards to cool the internal components of the rotor assembly.

[0063] The second fluid passage 605 comprises a first section 605-1, which extends from a second aperture of the multiple radial apertures in a radial direction 601 away from the shaft 310. The first section 605-1 of the second fluid passage 605 directs oil radially outward from the shaft 310. The second fluid passage 605 further comprises a second section 605-2, which extends from the first section 605-1 in an axial direction 602 to a second axial end 250-2 of the rotor body 250. The second section 605-2 of the second fluid passage 605 allows axial oil flow through a section of the rotor body 250.

[0064] The second fluid passage 605 also includes a third section 605-3 of the second fluid passage, which extends from the second section 605-2 in the radial direction 601 away from the shaft 310. The third section 605-3 of the second fluid passage directs oil radially outward from the axial channel to the magnet slots. The second fluid passage 605 further includes a fourth section 605-4 of the second fluid passage, which extends from the third section 605-3 of the second fluid passage in the axial direction 602 to the first axial end 250-1 of the rotor body 250. The fourth section 605-4 of the second fluid passage allows axial oil flow through a further section of the rotor body 250.

[0065] The second fluid passage 605 contains a fifth section 605-5, which extends from the fourth section 605-4 to a third magnetic slot 614 of the multiple magnetic slots. The fifth section 605-5 directs oil to the third magnetic slot 614 to cool the magnet held in the slot. The second fluid passage 605 also contains a sixth section 605-6, which extends from the fourth section 605-4 to a fourth magnetic slot 616 of the multiple magnetic slots. The sixth section 605-6 directs oil to the fourth magnetic slot 616 to cool the magnet held in the slot.

[0066] In exemplary embodiments, the fourth section 605-4 of the second fluid passage 605 has a triangular cross-sectional shape and comprises a first side, a second side, and a third side. The first side is generally parallel to the second section 605-2 of the second fluid passage 605. The fifth section 605-5 of the second fluid passage 605 extends from the second side, and the sixth section 605-6 of the second fluid passage 605 extends from the third side. The cross-sectional shape of the fourth section 605-4 of the second fluid passage 605 is configured to distribute, during operation of the electric machine, any fluid flowing through the fourth section 605-4 of the second fluid passage 605 evenly to the fifth section 605-5 and the sixth section 605-6 of the second fluid passage 605.

[0067] In exemplary embodiments, the second subset of the multiple stacked laminations includes a second lamination containing an opening configured to be aligned with the first aperture of the multiple radial apertures. The dimensions of the opening are configured to regulate the fluid flow through the second fluid passage 605. The second subset of the multiple stacked laminations ensures that the oil flow through the rotor body 250 is efficiently directed to the magnet slots, thereby improving cooling efficiency and reducing rotational losses in the rotor.

[0068] In exemplary embodiments, the rotor assembly shaft incorporates several radial apertures, specifically eight apertures, evenly spaced around the shaft's circumference. This configuration ensures that oil is distributed uniformly from the shaft to the rotor body, providing consistent cooling of the internal components. The uniform spacing of the radial apertures around the shaft's circumference enables a symmetrical and efficient oil flow, reducing the risk of localized overheating and ensuring optimal temperature management across the entire rotor assembly.

[0069] In the rotor assembly, the multiple stacked laminations include a first lamination containing four openings. These openings are positioned to align with the first four of the eight radial apertures in the shaft. This alignment ensures precise oil flow from the shaft through the first lamination and into the rotor body, guaranteeing that the oil reaches the designated magnetic slots for effective cooling. The design of the first lamination with its four openings ensures efficient oil flow, enhancing the overall cooling performance of the rotor assembly. Additionally, the multiple stacked laminations include a second lamination, which also contains four openings. Each of these openings is configured to align with the second four of the eight radial apertures in the shaft.This orientation ensures that the oil flow through the second lamination is evenly distributed, further improving the cooling efficiency of the rotor assembly. By having openings in both the first and second laminations aligned with different sets of radial apertures, the design ensures a comprehensive and balanced distribution of oil throughout the rotor body.

[0070] In one exemplary embodiment, at least two of the first four apertures in the first lamination are directly adjacent to each other. This proximity allows for a concentrated oil flow to specific areas of the rotor body, providing targeted cooling of critical components. The strategic arrangement of adjacent apertures ensures that areas with high heat generation receive adequate cooling, thereby improving the overall temperature management and reliability of the rotor assembly. This design feature ensures that the rotor assembly can maintain optimal operating temperatures even under challenging conditions, reducing the risk of overheating and improving the service life of the electric machine.

[0071] In exemplary embodiments, the fourth section of the first fluid passage has a cross-sectional shape configured to evenly distribute the fluid flowing through the fourth section to the fifth and sixth sections during operation of the electric machine. In these exemplary embodiments, a uniform distribution is necessary to maintain consistent cooling across the magnets accommodated in the first and second magnet slots, thereby preventing localized overheating and ensuring optimal temperature management of the rotor assembly. By evenly distributing the fluid flow, the design minimizes the risk of uneven oil distribution, which can lead to uneven cooling and potential hot spots in the rotor.This symmetrical flow contributes to the overall efficiency and reliability of the electric machine, as it ensures that all magnets receive adequate cooling, thus reducing the likelihood of thermal stress and aging over time. As described above, the cross-sectional shape of the fourth section of the first fluid passage can be triangular. However, as will be recognized by those skilled in the art, the cross-sectional shape of the fourth section of the first fluid passage can also be circular or semicircular.

[0072] With reference to Fig.Figures 7A-7D show the lamination design for a subset of laminations 700, 710, 720, and 730 in a rotor body according to one embodiment. In exemplary embodiments, the laminations 700, 710, 720, and 730 are stacked in the following sequence: lamination 700 is adjacent to lamination 710, and lamination 720 is adjacent to lamination 730. Lamination 710 is positioned between lamination 700 and lamination 720. Likewise, lamination 720 is positioned between lamination 710 and lamination 730. Each of the laminations 700, 710, 720, and 730 contains magnetic slots 711 and a central aperture 702. In exemplary embodiments, the magnetic slots 711 are distributed around the perimeter of the laminations 700, 710, 720, and 730 and are designed to receive the magnets. These slots ensure that the magnets are securely positioned in the rotor body, enabling efficient magnetic interaction with the stator windings.In exemplary embodiments, the central aperture 702 is arranged at the center of the laminations 700, 710, 720 and 730. This aperture is aligned with the central apertures of further laminations to define a shaft slot that accommodates the rotor shaft.

[0073] In exemplary embodiments, the lamination 700 includes first openings 701, which are positioned near the central aperture 702 and are designed to be aligned with a radial aperture in the rotor shaft. These openings allow oil to flow from the shaft to the magnet slots 711. In exemplary embodiments, the first opening 701 has a hemispherical cross-section. The lamination 710 includes second openings 703, fourth openings 705, sixth openings 707, and eighth openings 709, and the lamination 720 includes third openings 704, a fifth opening 706, and seventh openings 708. When the laminations 700, 710, 720, and 730 are stacked as described above, two fluid channels are formed through the openings 701-709. The fluid channels are each configured to provide an oil flow to one of the magnets arranged in magnet slots 711.In exemplary embodiments, the subset of laminations 700, 710, 720, and 730 can contain multiple laminations 710 and / or 720, and the number of these laminations determines an axial length of the first fluid channel. In exemplary embodiments, the geometry of the first opening 701 is configured to distribute the oil flow from the rotor shaft evenly into each of the second openings 703, thereby distributing the oil flow evenly between the two fluid channels.

[0074] The terms "a" and "an" do not denote a limit on the number of elements, but rather indicate the presence of at least one of the referenced element. The term "or" means "and / or" unless clearly indicated otherwise by context. A reference to "an aspect" in the application text means that a specific element (e.g., a feature, a structure, a step, or a property) described in connection with that aspect is contained in at least one aspect described therein and may or may not be present in other aspects. It should also be understood that the described elements in the various aspects may be combined in any suitable manner.

[0075] When an element, such as a layer, a thin layer, an area, or a substrate, is described as "attached" to another element, it may be located directly adjacent to that element, or there may be intervening elements. Conversely, when an element is described as "directly adjacent" to another element, there are no intervening elements.

[0076] Unless otherwise specified herein, all testing standards shall be the most recent valid standard as of the filing date of this application or, if priority is claimed, as of the filing date of the earliest priority application in which the testing standard appears.

[0077] Unless otherwise defined, technical and scientific terms used herein have the same meaning as would normally be understood by a person skilled in the field to which this disclosure belongs.

[0078] While the disclosure described above has been described with reference to exemplary embodiments, those skilled in the art will understand that various modifications can be made and elements can be replaced by their equivalents without altering its scope. Furthermore, many adaptations can be made to fit a particular situation or material to the instructions given in the disclosure without deviating from its essential scope. Therefore, it is intended that the present disclosure is not limited to the specific embodiments disclosed, but includes all embodiments that fall within its scope.

Claims

[1] Rotor for an electric machine comprising: a rotor body (250) formed from several stacked laminations (200, 210, 220, 302, 303, 304, 305, 700, 710, 720, 730) defining a first axial end (250-1) and an opposite second axial end (250-2), each of the several stacked laminations containing several magnetic slots (201, 610, 612, 614, 616, 711) aligned through the rotor body (250) and central apertures (202, 311, 702) aligned to define a shaft slot; and a shaft (310) arranged in the shaft slot, wherein the shaft (310) contains several radial apertures (312) which are fluidically connected to an axial channel (314, 316) arranged in the shaft (310); wherein a first subset of the several stacked laminations (230) contains openings (203, 204, 205, 206, 701, 703, 704, 705, 706, 707, 708, 709) which define a first fluid passage (603),a first section (603-1) extending from a first aperture of the several radial apertures (312) in a radial direction (601) away from the shaft (310), a second section (603-2) extending from the first section (603-1) in an axial direction (602) to the first axial end (250-1), a third section (603-3) extending from the second section (603-2) in the radial direction (601) away from the shaft (310), a fourth section (603-4) extending from the third section (603-3) in the axial direction (602) to the second axial end (250-2), a fifth section (603-5) extending from the fourth section (603-4) to a first magnetic slot (610) of the several magnetic slots (201, 610, 612, 614, 616, 711), and includes a sixth section (603-6) extending from the fourth section (603-4) to a second magnetic slot (612) of the multiple magnetic slots (201, 610, 612, 614, 616, 711). [2] Rotor according to claim 1, wherein the fourth section (603-4) of the first fluid passage (603) has a cross-sectional shape that is triangular and has a first, a second and a third side, wherein the first side is generally parallel to the second section (603-2) of the first fluid passage (603), the fifth section (603-5) extends from the second side and the sixth section (603-6) extends from the third side. [3] Rotor according to claim 1, wherein the fourth section (603-4) of the first fluid passage (603) has a cross-sectional shape configured to distribute fluid flowing through the fourth section (603-4) evenly to the fifth section (603-5) and the sixth section (603-6) during operation of the electric machine. [4] Rotor according to claim 1, wherein the first subset of the multiple stacked laminations (230) includes a first lamination (200, 302, 700) which includes an opening (203, 701) configured to be aligned with the first aperture of the multiple radial apertures (312), wherein the dimensions of the opening (203, 701) are configured to regulate a flow of a fluid through the first fluid passage (603). [5] Rotor according to claim 1, wherein a second subset of the multiple stacked laminations (240) includes openings (204, 205, 206, 703, 704, 705, 706, 707, 708, 709) defining a second fluid passage (605) comprising a first section (605-1) extending from a second aperture of the multiple radial apertures (312) in the radial direction (601) away from the shaft (310), a second section (605-2) extending from the first section (605-1) in an axial direction (602) to the second axial end (250-2), a third section (605-3) extending from the second section (605-2) in the radial direction (601) away from the shaft (310), and a fourth section (605-4) extending extending from the third section (605-3) in the axial direction (602) to the first axial end (250-1), a fifth section (605-5) extending from the fourth section (605-4) to a third magnetic slot (614) of the several magnetic slots (201, 610, 612, 614, 616,711), and includes a sixth section (605-6) extending from the fourth section (605-4) to a fourth magnetic slot (616) of the multiple magnetic slots (201, 610, 612, 614, 616, 711). [6] Rotor according to claim 5, wherein the second subset of the multiple stacked laminations (240) is arranged adjacent to the first subset of the multiple stacked laminations (230). [7] Rotor according to claim 1, wherein the multiple radial apertures (312) comprise eight apertures spaced equally apart around the circumference of a shaft (310). [8] Rotor according to claim 7, wherein the multiple stacked laminations (200, 210, 220, 302, 303, 304, 305, 700, 710, 720, 730) include a first lamination (200, 302, 700) comprising four openings (203, 701) configured to be aligned with the first four of the eight apertures (312). [9] Rotor according to claim 8, wherein the multiple stacked laminations (200, 210, 220, 302, 303, 304, 305, 700, 710, 720, 730) include a second lamination (210, 304, 710) comprising four openings (204, 703) each configured to be aligned to the second four of the eight apertures (312). [10] Rotor according to claim 8, wherein at least two of the first four apertures (312) are directly adjacent to each other.

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