Method and system for a cooling-integrated pole retainer

Abstract

The disclosed devices, systems, and techniques described herein allow the pole retaining hardware of an electric motor to also function as a cooling manifold to remove heat generated by the electric coil. The pole retainer device can include a pole retainer that retains the pole to the hub. The pole retainer can include a proximal end and a distal end that are attached to the hub. The pole retainer can include a channel that extends through the pole retainer from the proximal end of the pole retainer that is attached to the hub to the distal end of the pole retainer. The device can include a mount disposed at the distal end of the pole retainer and configured to retain the pole on the hub. The device can include a fluid transfer duct connected to the mount. The cooling system can be employed in TORUS axial flux permanent magnet motors, as well as a variety of other motor designs.

Description

[Technical Field]

[0001] Cross-reference of related applications

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 188,043, filed on 13 May 2021, entitled “Method and System for a Cooled Integrated Pole Retainer,” the disclosures of which are incorporated by reference in whole and for all purposes. [Background technology]

[0002]

[0002] Generally, the performance of an electromechanical device is limited by mechanical stress and thermal performance. Cooling techniques for current toroidal stator (TORUS) axial flux permanent magnet (AFPM) electric motors can rely on air cooling or direct oil cooling. Direct oil cooling may include immersing the electric coils in oil or spraying oil onto the electric coil windings when higher power density is required. Rotating the rotor assembly of an electric motor in oil reduces the overall efficiency of the motor, as losses due to the fluid density and dynamic viscosity of the oil interact with the stationary and rotating parts, resulting in friction losses and airflow losses.

[0003]

[0003] Toroidal stator AFPM motors are widely considered to have high torque density or power density in foot-pounds per pound or Newton-meters per kilogram due to the elimination of back iron in the stator assembly, and allow flux wires to travel straight across the stator. However, cooling torus AFPM motors can be difficult because the back iron is usually used for cooling or as a heat transfer medium between the stator and the heat-generating components of the cooling system. Thus, there is a need in the art for improved methods and systems for cooling electric motors. [Overview of the project] [Means for solving the problem]

[0004]

[0004] The apparatus, systems, and techniques disclosed herein enable the pole retainer hardware of an electric motor to function as a cooling manifold for removing heat generated by the electric coil. The disclosed apparatus, systems, and techniques may be particularly useful in the context of toroidal winding, axial flux motors, and enable the cooling water to be placed adjacent to or near the loss source (e.g., coil conductors and pole stack). Furthermore, since the technique can be implemented on wound-field rotor poles, it enables the elimination of rotor losses common in high-speed permanent magnet machines by direct pole cooling or permanent magnet rotor poles.

[0005]

[0005] In aspects of the disclosure, a pole retainer device may include a pole retainer for holding a pole to a hub, the pole retainer including a proximal end and a distal end attached to the hub. The device may include a channel extending through the pole retainer from the proximal end to the distal end of the pole retainer. The device may include a mount located at the distal end of the pole retainer and configured to hold the pole on the hub. The device may include a fluid transfer duct connected to the mount.

[0006]

[0006] In various embodiments, the fluid transfer duct is connected to a condenser which includes one or more fins and a reservoir.

[0007]

[0007] In various embodiments, the channel is configured to be connected to a manifold integrated into the hub.

[0008]

[0008] In various embodiments, the channel is configured to contain liquid cooling water.

[0009]

[0009] In various embodiments, the channel is configured to include a heat pipe.

[0010]

[0010] In various embodiments, the distal end of the pole retainer is threaded.

[0011]

[0011] In various embodiments, the fluid transfer duct comprises a tube.

[0012]

[0012] In various embodiments, the fluid transfer duct comprises pipes.

[0013]

[0013] In aspects of the present disclosure, a system for cooling an electric motor may include a stator pole configured to hold at least one of a coil or a magnet. The stator pole includes a recess. The system may include a pole retainer configured to fit inside the recess of the stator pole and to mount the stator pole to a hub, the pole retainer may include a channel extending through the pole retainer shaft from a proximal end of the pole retainer shaft, configured to mount to the hub, to a distal end of the pole retainer. A proximal mount may be located at the proximal end of the pole retainer and configured to mount the pole retainer to a hub. The system may include a distal mount located at the distal end of the pole retainer and configured to connect the channel to a fluid transfer duct.

[0014]

[0014] In various embodiments, the hub includes an integrated fluid manifold.

[0015]

[0015] In various embodiments, the system includes a fluid seal positioned between the proximal mount and the hub.

[0016]

[0016] In various embodiments, the fluid transfer duct is connected to a condenser which includes one or more fins and a reservoir.

[0017]

[0017] In various embodiments, the channel is configured to be connected to a manifold integrated into the hub.

[0018]

[0018] In various embodiments, the channels are configured to contain liquid cooling water.

[0019]

[0019] In various embodiments, the channels are configured to comprise heat pipes.

[0020]

[0020] In an aspect of the present disclosure, a method of cooling an electric motor comprises guiding cooling fluid from a manifold in a hub through a first channel extending through a first pole retainer configured to mount a first pole to the hub. The method can comprise absorbing heat generated by one or more first coils of one or more first permanent magnets attached to the first pole by the cooling fluid. The method can comprise guiding the cooling fluid from the first channel to a second channel extending through a second shaft pole retainer configured to mount a second pole to the hub via a fluid transfer duct. The method can comprise absorbing heat generated by one or more second coils or one or more second permanent magnets attached to the second pole by the cooling fluid. The method can comprise guiding the cooling fluid from the second channel back to the manifold in the hub.

[0021]

[0021] In various embodiments, the method comprises guiding the cooling fluid through a heat exchanger in the manifold within the hub.

[0022]

[0022] In various embodiments, the method comprises guiding the cooling fluid through a heat exchanger disposed between the first channel and the second channel.

[0023]

[0023] In various embodiments, the method comprises circulating the cooling fluid by rotating the hub.

[0024]

[0024] In various embodiments, the method comprises measuring the temperature of the cooling fluid via a temperature sensor in communication with the cooling fluid.

[0025]

[0025] For a better understanding of the nature and advantages of the present disclosure, reference should be made to the following description and the accompanying drawings. It should be understood, however, that the drawings are provided for illustrative purposes only, and are not intended to define the limitations of the scope of the present disclosure. Furthermore, as a general rule, unless the contrary is clear from the description, when elements in different drawings use the same reference numerals, the elements are generally identical, or at least similar in function or purpose. Brief Description of the Drawings

[0026]

[0026] The accompanying drawings are for illustrative purposes, and serve only to provide examples of possible structures and arrangements for the disclosed inventive apparatus and method for integrated cooling for pole retainers. The drawings in no way limit changes in form and detail that may be made to the disclosure by those skilled in the art without departing from the spirit and scope of the disclosure. Embodiments will be readily understood from the following detailed description taken in conjunction with the accompanying drawings, wherein like reference numerals indicate like structural elements. [Figure 1] 1 illustrates an exemplary pole retainer cooler according to an embodiment of the present disclosure. [Figure 2] 2 illustrates an exemplary pole retainer cooler integrated with a hub according to an embodiment of the present disclosure. [Figure 3] 3 illustrates an exemplary TORUS axial flux permanent magnet motor pole with pole windings removed from the illustration for clarity according to an embodiment of the present disclosure. [Figure 4] 4 illustrates an exemplary isometric view of a wound field salient pole synchronous rotor assembly with a direct pole cooling system according to an embodiment of the present disclosure. [Figure 5] 5 illustrates a side view of a direct pole cooling system of a wound field salient pole synchronous rotor assembly according to an embodiment of the present disclosure. [Figure 6] 6 illustrates an enlarged view of a pole in a direct pole cooling system of a wound field salient pole synchronous rotor assembly according to an embodiment of the present disclosure. [Figure 7] A side view of a salient pole retainer cooler according to one embodiment of the present disclosure is shown. [Figure 8] This shows an enlarged view of the pole and retainer of a salient pole retainer cooler according to one embodiment of the present disclosure. [Figure 9] An exemplary heat pipe integrated pole retainer according to one embodiment of the present disclosure is shown. [Figure 10] A profile diagram of a first exemplary rotor cooling system for an axial magnetic field topology according to one embodiment of the present disclosure is shown. [Figure 11] A cross-sectional view of an exemplary rotor cooling system for an axial magnetic field topology according to one embodiment of the present disclosure is shown. [Figure 12] A second exemplary rotor cooling system for an axial magnetic field topology according to one embodiment of the present disclosure is shown in a top view. [Figure 13] A top view of a third exemplary rotor cooling system for an axial magnetic field topology according to one embodiment of the present disclosure is shown. [Figure 14] A profile diagram of an exemplary rotor cooling system for a radiation field topology according to one embodiment of the present disclosure is shown. [Figure 15] An overview view of an exemplary rotor cooling system for a radiation field topology according to one embodiment of the present disclosure is shown. [Figure 16] A profile diagram of an exemplary linear motor rotor pole cooling system according to one embodiment of the present disclosure is shown. [Figure 17] An exemplary linear motor rotor pole cooling system according to one embodiment of the present disclosure is shown as a side view. [Figure 18] A graph of airflow loss versus rotor speed for an exemplary motor having air in an air gap and oil in an air gap, according to one embodiment of the present disclosure, is shown. [Figure 19] An illustrative flowchart illustrating a method for cooling an electric motor according to one embodiment of the present disclosure is shown. [Modes for carrying out the invention]

[0027]

[0046] For a detailed explanation of the following implementation examples, please refer to the attached drawings. The same reference number in different drawings may identify the same or similar elements.

[0028]

[0047] This disclosure generally applies to the field of electromechanics, more specifically to the mechanical holding and cooling of rotor (rotating) and stator (stationary) poles. Typically, the performance of electric motors is limited by mechanical stress and thermal performance. Embodiments of this disclosure allow pole holding hardware to function not only as a mechanical function but also as a cooling manifold. The apparatus, systems, and techniques described herein allow pole holding hardware of an electric motor to function as a cooling manifold for removing heat generated by the electric coils and / or permanent magnets. The apparatus, systems, and techniques described herein may be particularly beneficial in the context of toroidal winding and axial flux motors, where cooling water can be placed adjacent to or near the loss source (e.g., coil conductors and pole stacks). Furthermore, embodiments of this disclosure can be implemented on wound-field rotor poles, enabling the use of direct pole cooling and permanent magnet rotor poles to remove heat arising from rotor losses present in high-speed permanent magnet machines.

[0029]

[0048] Electric motors generate heat from various sources (for example, by passing an electric current through a wire coil to generate a magnetic field). Current cooling techniques attempt to reduce the heat generated from these various sources by immersing the motor in a viscous coolant. Immersing the motor in a viscous fluid can limit the motor's speed due to the force required to overcome the fluid's viscous drag. These losses become greater with larger motors. Conventional pole retainer devices are constructed using solid metal mechanical mounting mechanisms or pole retainers, which obstruct the flow of coolant through the pole retainer device. The techniques described herein enable motor operation at high speeds (e.g., exceeding 3000 revolutions per minute (RPM)). As an example of a high-speed motor, a motor that allows speeds exceeding 3000 RPM is provided, but the actual speed is not a limitation of this disclosure.

[0030]

[0049] Figure 1 shows a cutaway, profile diagram of a pole retainer cooler 100 according to one embodiment of the present disclosure. The pole retainer cooler 100 may include a pole retainer 102. The pole retainer 102 holds poles 112 to a hub 104. The pole retainer 102 may be made of a metal (e.g., iron or titanium) or a metal alloy (e.g., steel). The pole retainer 102 may include a proximal end 103 and a distal end 109. The proximal end 103 of the pole retainer 102 may be attached to the hub 104. Multiple pole retainers 102 may be attached to the hub 104. The pole retainer 102 may include a channel 105 running through the center of the pole retainer 102, from the proximal end 103 to the distal end 109 of the pole retainer 102. In various embodiments, the channel 105 may be perforated in the pole retainer 102. The pole retainer 102 can be coupled to the hub 104 via a hub mount 106. The hub mount 106 may also be known as the proximal mount 106. The hub mount 106 may be formed as part of the pole retainer 102, or as one or more separate parts that can be coupled to each other as appropriate. The hub mount 106 can be coupled to the hub 104 using one or more fasteners 108. To prevent fluid leakage, a fluid seal 110 can be placed between the hub mount 106 and the hub 104. The fluid seal 110 may include one or more O-rings.

[0031]

[0050] The pole retainer 102 can be sized to fit within a recess 114 of the pole 112 in order to hold the pole 112 in the hub 104. In various embodiments, the recess 114 can be rectangular in shape. In various embodiments, the recess 114 can be slightly larger than the external dimensions of the pole retainer 102. This allows for thermal expansion and contraction of the pole retainer 102 and the pole 112. The pole 112 may include multiple windings of a coil 116. The windings of the coil 116 can generate a magnetic field when alternating current passes through the coil 116. The pole 112 may also include a lamination 118 between the coil 116 and the pole retainer 102. The lamination 118 can minimize losses by oriented the magnetic flux and reducing eddy currents in the electric motor. The lamination can be made from a variety of materials.

[0032]

[0051] In various embodiments, a thermally conductive compound 120 (e.g., thermal grease, thermal interface pad, epoxy, etc.) can be applied between the pole retainer 102 and the inner surface of the recess 114 of the pole 112. The thermal compound 120 can facilitate heat transfer from the laminate 118 and coil 116 to the cooling fluid flowing through the channel 105. A liquid coolant (e.g., liquid cooling fluid) can be circulated through the channel 105, for example, as illustrated by the arrows in Figure 1. The cooling fluid can absorb the heat generated by the coil 116 and / or permanent magnets.

[0033]

[0052] The cooling fluid can be any fluid or gas currently in use, such as fresh water, seawater, oil, glycols and glycol mixtures, or cryogenic fluids such as liquid nitrogen. Other coolants include air or other gases in liquid or gaseous state.

[0034]

[0053] The distal end 109 of the pole retainer 102 may include a pole mount 111 (also known as a distal mount) which can be configured to hold the pole 112 on the hub 104. The distal end 109 of the pole retainer 102 may include multiple threads 121. A washer plate 122 and a retaining nut 124 can secure the pole 112 on the pole retainer 102. The distal end 109 of the pole retainer 102 may also include a fluid connection 126. The fluid connection 126 can connect the channel 105 to a fluid transfer duct. The fluid transfer duct may be a tube, duct, manifold, or a combination of these.

[0035]

[0054] Hub 104 may include a manifold 107. The manifold 107 may be an integrated fluid manifold 107. The manifold 107 allows for the transfer of cooling fluid from one pole to an adjacent pole (not shown). The manifold 107 can also transfer cooling fluid to or from a pump, or to or from a reservoir. The reservoir stores the cooling fluid until needed. Excess cooling fluid remains in the reservoir until the system is sufficiently cooled and negative pressure is generated, returning the excess coolant from the reservoir to circulation. The arrows shown in Figure 1 indicate the direction of cooling fluid flow in the channel 105 and manifold 107, flowing from the distal end 109 to the proximal end 103, but the actual direction of cooling fluid flow may vary depending on the application. For example, in some poles, the fluid flow may flow from the proximal end to the distal end or vice versa. Similarly, the direction of cooling fluid flow in the manifold may be either the direction shown or the opposite direction. Those skilled in the art will recognize many variations, modifications, and substitutions.

[0036]

[0055] The temperature probe 128 can be installed within the manifold 107. In various embodiments, the temperature probe 128 can be installed in the channel 105, the fluid transfer duct 208 shown in Figure 2, or a radiator (not shown). In various embodiments, multiple temperature probes 128 can be installed in the fluid path. The temperature probe 128 can measure the temperature of the cooling fluid. One or more temperature probes 128 can provide an estimate of the effectiveness of the cooling fluid in reducing heat from the coil.

[0037]

[0056] Figure 2 shows a portion of an exemplary pole retainer cooler 200 according to an embodiment of the present disclosure, along with arrows indicating the path through which the coolant flows. While the coolant is common, other series-parallel flow configurations are also possible. The exemplary pole retainer cooler 200 shown in Figure 2 can correspond to the pole retainer cooler 100 as shown in Figure 1. Figure 2 shows a plurality of pole retainers 202, a plurality of stator poles 204, and a hub 206. The pole retainers 202 can correspond to the pole retainers 102 as shown in Figure 1. Each of the pole retainers 202 can be configured to hold the stator poles 204 in the hub 206. A fluid transfer duct 208 can transfer the cooling fluid from a channel in a pole retainer 202 to a channel in an adjacent pole retainer 202. The hub 206 may include a manifold 210 that facilitates the flow of cooling fluid between the pole retainers 202 after the cooling fluid has passed through the channels in the corresponding pole retainers. Figure 2 also shows the coil of wire 212 that encloses the stator pole 204.

[0038]

[0057] Figure 3 shows an exemplary toroidal winding (TORUS) AFPM motor pole 300 according to an embodiment of the present disclosure. The motor pole 300 can be made using a metal (e.g., iron) or a metal alloy (e.g., steel) by casting, forging, machining, laminating individual sheet metal laminates, or by any appropriate process. The TORUS AFPM motor pole 300 may include a recess 302. The recess 302 may be sized to receive a pole retainer 202, as shown in Figure 2. In various embodiments, the recess 302 may be rectangular, although other geometric shapes are included within the scope of the present disclosure. The pole 300 may include end plates 304 at the ends of each arm 306 of the motor pole 300. A coil 116 may be wound around each arm 306 of the motor pole 300, as shown in Figure 1. The coil 116 can generate a magnetic field when an alternating current is guided through and passes through the coil 116. Laminations 118 may be formed around each arm 306 of the motor pole 300, as shown in Figure 1.

[0039]

[0058] In addition to the stationary stators shown in Figures 2 and 3, the cooling structures and techniques described herein can be applied to rotating components such as electric motor rotors (e.g., salient pole rotors).

[0040]

[0059] Figure 4 shows an exemplary isometric view of a salient pole direct pole cooling system 400 according to an embodiment of the present disclosure. The salient pole rotor may have a diameter that is large relative to its length. The salient pole rotor can be used in low-speed electromachines (e.g., electromachines operating in the range of 100 RPM to 1500 RPM). The salient pole rotor may include damper windings to avoid rotor vibration during operation.

[0041]

[0060] The direct pole cooling system 400 can be coupled to the rotor shaft 402 of an electric motor. The electric motor may include a plurality of poles 404. Each set of poles 404 can hold a set of rotor pole coils 406. An alternating current flows through each set of rotor pole coils 406, generating heat. Multiple channels (not shown) can pass through each pole of the plurality of poles 404. A cooling fluid can pass through the multiple channels. The cooling fluid can absorb the heat generated by the rotor pole coils 406. The multiple channels can be connected to a manifold (not shown) inside a hub 408. The channels can also be connected to a cooling manifold 410. The cooling manifold 410 can radiate the heat absorbed by the cooling fluid as the rotor shaft 402 rotates.

[0042]

[0061] Figure 5 shows a side view of a salient pole direct cooling system 500 according to an embodiment of the present disclosure, with arrows indicating the path through which the coolant flows. The coolant is common, but other series-parallel flow configurations are also possible. This configuration includes a rotary fluid coupler 514 that connects a fixed coolant supply to a rotary cooling system. In other embodiments, the cooling system may be integrated into a rotary assembly. The salient pole direct cooling system 500 corresponds to the salient pole direct cooling system 400 in Figure 4. The salient pole direct cooling system 500 may include a rotor 501 coupled to a rotor shaft 502 of an electric motor. The electric motor may include a plurality of poles 504. Each pole of the plurality of poles 504 may hold a set of rotor pole coils 506. An alternating current flows through each set of rotor pole coils 506, generating heat. A plurality of channels (not shown) can pass through each pole of the plurality of poles 504. The cooling fluid can pass through the plurality of channels. The cooling fluid can absorb the heat generated by the rotor pole coils 506. Multiple channels can be connected to a manifold in the hub 408, as shown in Figure 4. The channels can also be connected to a cooling manifold 510. The cooling manifold can radiate the heat absorbed by the cooling fluid as the rotor shaft 502 rotates. The cooling fluid can be guided through the channels 512. As the rotor 501 rotates, a rotating union 514 can be used to transfer the cooling fluid between the channels 512 in the rotor 501 and the rotating union 514. The cooling fluid can flow through the channels 512, then through the rotating union 514, then through channels inside the rotor (not shown), and into the rotor manifold (not shown). The cooling fluid can flow through various cooling manifolds 510 through one or more channels in each of the poles 504 and out of the rotor through the rotating union 514 and channels 512.

[0043]

[0062] In various embodiments, one or more pumps, filters, and radiators can be connected to the channel. In this way, the pumps can pressurize the fluid and allow it to flow through the channel. The filters can remove impurities from the cooling fluid. The radiators can dissipate the heat absorbed by the cooling fluid. The cooled cooling fluid can return to the channel and rotor via the rotating union 514, which forms a closed-loop system. The directional arrows showing the directional flow of the cooling fluid in Figure 5 are illustrative, and this disclosure is not so limited, as the fluid flow can be directed in other directions. Those skilled in the art will recognize many variations, modifications, and substitutions.

[0044]

[0063] Figure 6 shows an enlarged view of the poles of a salient pole direct pole cooling system 600 according to one embodiment of the present disclosure. The portion of the salient pole direct pole cooling system 600 shown in Figure 6 corresponds to the salient pole direct pole cooling systems 400 and 500. The rotor poles 604 can hold a set of rotor pole coils 606. An alternating current flows through each set of rotor pole coils 606, generating heat. As shown in Figure 6, a cooling manifold 614 is connected to a channel through which the rotor poles 604 pass. A cooling fluid can pass through the cooling manifold 614 to cool the fluid via radiation. A pole retainer 610 can be screwed in so that the rotor poles 604 are secured with nuts 612.

[0045]

[0064] Figure 7 shows a side view of another exemplary embodiment of the salient pole retainer cooler 700 according to one embodiment of the present disclosure. The salient pole retainer cooler 700 is similar to the salient pole direct cooling system 500 as shown in Figure 5. However, the cooling manifold 710 is mounted on wedges positioned between the rotor poles 704 and the rotor pole coils 706, respectively, rather than passing through the rotor poles 504 as shown in Figure 5.

[0046]

[0065] The direct pole cooling system 700 may include a rotor 701 coupled to the rotor shaft 702 of an electric motor. The electric motor may include a plurality of poles 704. Each pole of the plurality of poles 704 may hold a set of rotor pole coils 706. An alternating current flows through each set of rotor pole coils 706, generating heat.

[0047]

[0066] Multiple channels (not shown) can pass through wedges positioned between each of the poles of multiple poles 704. Cooling fluid can pass through multiple channels. Cooling fluid can absorb the heat generated by the rotor pole coils 706. Multiple channels can be connected to manifolds in a hub (not shown). Channels can also be connected to a cooling manifold 710. The cooling manifold can transfer the heat absorbed by the cooling fluid as the rotor shaft 702 rotates. Cooling fluid can be guided through channels 712. As the rotor 701 rotates, a rotating union 714 can be used to transfer fluid to and from channels within the rotor 701. Cooling fluid can pass through channels 712, through the rotating union 714, through channels inside the rotor (not shown), through various cooling manifolds 710, through one or more channels in each of the wedges positioned between the poles 704, into the rotor manifolds (not shown), and exit from the rotor through channels 712 via the rotating union 714.

[0048]

[0067] Figure 8 shows an enlarged view of a portion of a pole retainer cooling system 800 according to one embodiment of the present disclosure. Figure 8 is not drawn to scale for illustrative purposes. Figure 8 shows a plurality of rotor poles 804 that hold the rotor pole coil 806 in a hub 808. The cooling manifold 810 can be attached to the wedge 816 via a threaded pole retainer 812 using fasteners 814 (e.g., retaining nuts). The pole retainer 812 may include channels for circulating a cooling fluid from the manifold in the hub 808, through a wedge 816 positioned between the rotor coils 806, through the cooling manifold 810, and then back to the manifold in the hub 808. The cooling fluid can absorb the heat generated by the coils 806.

[0049]

[0068] Figure 9 shows a cutaway profile diagram of an exemplary heat pipe integrated pole retainer 900 according to one embodiment of the present disclosure. In this arrangement, the heat pipe replaces the conventional fluid cooling system, eliminating the need for a coolant fluid. The pole retainer device 900 may comprise a pole retainer 902. The pole retainer 902 may be formed of a metal (e.g., iron or titanium) or a metal alloy (e.g., steel). The pole retainer 902 may include a proximal end 903 and a distal end 909. The proximal end 903 of the pole retainer 902 may be attached to a hub 904. The pole retainer 902 may include a channel 905 formed through the center of the pole retainer 902. The pole retainer 902 may be coupled to a hub 904 via a hub mount 906. The hub mount 906 may be formed as part of the pole retainer 902 or as one or more separate parts coupled to one another. The hub mount 906 can be connected to the hub 904 using one or more fasteners 908.

[0050]

[0069] The pole retainer 902 can be sized to fit within a recess in the pole 912 in order to hold the pole 912 in the hub 904. In various embodiments, the recess can be rectangular in shape. The pole 912 may include multiple windings of the coil 916. The windings of the coil 916 can generate a magnetic field as alternating current passes through the coil 916. The pole may also include a laminate 918 between the coil 916 and the pole retainer 902. The laminate 918 can minimize losses by oriented the magnetic flux and reducing eddy currents in the motor.

[0051]

[0070] In various embodiments, a thermal compound 920 (e.g., thermal grease) can be applied between the pole retainer 902 and the inner surface of the recess of the pole 912. The thermal compound 920 facilitates the transfer of heat from the lamination 918 and coil 916 to the heat pipe 922 located in the channel 905. The heat pipe 922 is a heat transfer device that effectively transfers heat between two solid interfaces by combining the principles of both thermal conductivity and phase transition. At the high-temperature interface of the heat pipe 922, a liquid in contact with a thermally conductive solid surface turns into vapor by absorbing heat from its surface. The vapor then travels along the heat pipe 922 to the low-temperature interface, where it condenses back into a liquid, releasing latent heat. The liquid then returns to the high-temperature interface by either capillary action, centrifugal force, or gravity, and the cycle repeats. Due to its very high heat transfer coefficient for boiling and condensation, the heat pipe 922 is a very effective heat conductor.

[0052]

[0071] The distal end 909 of the pole retainer 902 may include a pole mount 911 which can be configured to hold a pole 912 on the hub 904. The distal end 909 of the pole retainer 902 may be screwable. A washer plate 923 and a retaining nut 924 can secure the pole 912 on the pole retainer 902. The distal end 909 of the pole retainer 902 may also include a condenser 926. The condenser 926 is connected to the heat pipe 922, allowing heat transfer from the heat pipe 922 via one or more fins and / or a coolant reservoir such as water, oil, or air present on the condenser 926. The one or more fins (e.g., condenser fins) may be thin metal slats running along the contour of the heat exchanger. The purpose of the one or more fins may be to keep warm air away from the heat exchanger during the operation of an electric motor.

[0053]

[0072] Figure 10 shows a profile diagram of an axial field topology cooling system 1000 according to one embodiment of the present disclosure. This configuration includes a rotary fluid coupler (item 1014) for coupling a fixed coolant supply to a rotary cooling system. In other embodiments, the cooling system may be integrated into a rotary assembly. An axial field electric motor includes one or more elements, such as a rotor mounted for rotation and a plurality of axial flux permanent magnets carried by the rotor. The axial flux permanent magnets are oriented such that the associated magnetic flux they generate is at least substantially axial. The axial flux permanent magnets can be arranged around the rotor with their flux directions alternating such that the magnetic flux directions of adjacent magnets are at least substantially axial, but opposite. Radial flux permanent magnets are also carried by the rotor and oriented such that the associated magnetic flux they generate is at least substantially radial.

[0054]

[0073] Instead of coils, the rotor shown in Figure 10 uses permanent magnets 1008 separated by a pole retainer 1004 for the axial field topology cooling system 1000. The pole retainer 1004 can fix one or more permanent magnets 1008 to the rotor 1001. If the permanent magnets exceed a threshold temperature (e.g., 80°C), the permanent magnets 1008 may lose their magnetism or even be permanently demagnetized if heated above the Curie temperature. Therefore, embodiments of the present disclosure provide a method and system for cooling the permanent magnets 1008 used in the axial field topology cooling system 1000 shown in Figure 10. Channels passing through the pole retainer 1004 allow heat to be removed from the rotor 1001 and heat transfer to be carried out using a cooling fluid flowing through the channels within the pole retainer 1004. In the embodiment of the present disclosure shown in Figure 10, the cooling fluid can be guided through the channel 1010, through the rotating union 1014, and then through the channel 1010 in the rotor shaft 1002. The rotating union 1014 can connect the cooling medium to the rotating parts of the rotor. The cooling fluid can be guided through the manifold in the rotor shaft 1002, through the channel 1010, and through the cooling duct to the pole retainer 1004.

[0055]

[0074] Figure 11 shows a cross-sectional view of an exemplary rotor cooling system 1100 for an axial magnetic field topology according to one embodiment of the present disclosure, where arrows indicate the path through which the coolant flows. The coolant is common, but other series-parallel flow configurations are also possible. The exemplary rotor cooling system 1100 corresponds to the rotor cooling system shown in Figure 10. Figure 11 shows a rotor mounted on a rotor shaft 1102. The rotor may include a plurality of pole retainers 1104. Cooling fluid can be guided through channels 1110, through a rotating union 1114, and through channels 1110 that pass through the pole retainers. The embodiment shown in Figure 11 includes a cooling duct 1130 for guiding the cooling fluid from a manifold in the rotor shaft 1102 to channels 1110 in the pole retainers 1104.

[0056]

[0075] Figure 12 shows a top view of a second exemplary rotor cooling system 1200 for an axial field topology according to one embodiment of the present disclosure. The pole retainer 1204 for the second exemplary rotor cooling system 1200 extends from the rotor shaft 1202. Thus, the cooling duct 1130 shown in Figure 11 is optional in this embodiment. The cooling fluid can be guided through channel 1210, through the rotating union 1214, through channel 1230 which passes through the pole retainer 1204, and back through the rotating union 1214.

[0057]

[0076] Figure 13 shows an overhead view of a third exemplary rotor cooling system 1300 for an axial field topology according to one embodiment of the present disclosure. A pole retainer 1304 for the third exemplary rotor cooling system 1300 extends from the rotor shaft 1302. In the embodiment shown in Figure 13, the spindle topology shown in Figure 12 is optional. A cooling duct 1330 guides fluid into and out of the manifold within the rotor shaft 1302. The cooling fluid can be guided through channel 1310, through the rotating union 1312, through channel 1310, through the pole retainer 1304, and back through the rotating union 1312.

[0058]

[0077] Figure 14 shows a profile diagram of an exemplary rotor cooling system 1400 for a radiant field topology according to one embodiment of the present disclosure. Figure 14 shows a rotor mounted on a rotor shaft 1402. The rotor may include a plurality of pole retainers 1404 capable of holding a plurality of permanent magnets 1408. Cooling fluid can be guided through channels 1410, through a rotating union 1414, and to a manifold (not shown) in the rotor shaft 1402. The manifold can guide the cooling fluid to the pole retainers 1404 through cooling ducts 1432. The cooling fluid guided through channels 1410 in the pole retainers 1404 absorbs heat from the permanent magnets 1408 and can return to the manifold and rotating union 1414 through cooling ducts 1432 and back to a heat exchanger via channels 1410.

[0059]

[0078] Figure 15 shows an exemplary rotor cooling system 1500 for a radiant field topology according to one embodiment of the present disclosure, with arrows indicating the coolant flow path. The coolant is common, but other series-parallel flow configurations are also possible. This configuration includes a rotary fluid coupler (item 514) for connecting a fixed coolant supply to the rotary cooling system. In other embodiments, the cooling system may be integrated into a rotary assembly. Figure 15 shows a rotor mounted on a rotor shaft 1502. The rotor may include multiple pole retainers 1504 capable of holding multiple permanent magnets 1508. Coolant can be guided through a channel 1510, through a rotary union 1514, and to a manifold (not shown) in the rotor shaft 1502. The manifold can guide the coolant to the pole retainers 1504 via a cooling duct 1532. The cooling fluid guided through the channel 1510 within the pole retainer 1504 absorbs heat from the permanent magnet 1508 and can be sent back to the heat exchanger via the channel 1510 through the cooling duct 1532 to the manifold and through the rotating union 1514. In various embodiments, the cooling duct 1532 can be secured to the pole retainer 1504 using retainer hardware 1534 (e.g., retaining nuts).

[0060]

[0079] Figure 16 shows a profile diagram of an exemplary linear motor rotor pole cooling system 1600 according to one embodiment of the present disclosure, with arrows indicating the path through which the coolant flows. The coolant is common, but other series-parallel flow configurations are also possible. A linear motor is an electric motor with a stator and rotor "unfolded". Therefore, instead of generating torque (i.e., rotation), it generates a linear force along its length. The linear motor may include a plurality of magnets 1608 which can be held by a pole retainer 1604. The linear motor rotor pole cooling system 1600 can guide a cooling fluid through a cooling duct (not shown) located inside the pole retainer 1604 and oriented along its length. The cooling fluid can be guided to the cooling duct inside the pole retainer via a fluid connector 1610. The fluid connector 1610 can be connected to one or more hoses or a cooling manifold. The fluid connector 1610 is screwable. The pole retainer 1604 can be coupled to the magnetic backing iron 1612 via fasteners or other common fastening methods (e.g., rivets, welds, tension rods, adhesives, etc.). Those skilled in the art will understand that not all pole retaining hardware must pass through a coolant.

[0061]

[0080] Figure 17 shows a side view of an exemplary linear motor rotor pole cooling system 1700 according to one embodiment of the present disclosure. Figure 17 shows a portion of a linear motor including a plurality of pole retainers 1704 that hold magnets 1708 to a magnetic backing iron 1712. A fluid connector 1710 guides cooling fluid through cooling ducts formed inside the pole retainers 1704. The fluid connector 1710 can be screwed in and can receive fasteners 1714 for holding the pole retainers 1704 to the magnetic backing iron 1712.

[0062]

[0081] FIG. 18 is a graph of windage loss versus rotor speed for an exemplary motor having air in the air gap and oil in the air gap. In embodiments of the present disclosure, the oil-filled air gap for cooling can be replaced with air using the pole retainer cooling method of the present disclosure, enabling low loss and high rotor speed with the same electromagnetic motor design. TORUS-style axial flux electrical machines can feature air cooling or direct oil cooling of the windings (either immersion in oil or spray cooling with oil) when higher power density is required. This is necessary to remove losses incurred during motoring or power generation (e.g., I 2 R copper loss, or hysteresis and eddy current loss in the core and / or magnets). The stator pole retainer with integrated cooling provided by embodiments of the present disclosure allows TORUS axial flux style motors to achieve higher speed and higher efficiency for applications requiring high power density. This advantage is achieved through the reduction of windage loss caused by immersing rotating motor components in oil, or spraying or dripping coolant onto rotating components. In an axial flux motor, windage loss can be a direct result of fluid density and dynamic viscosity, as expressed by the following equation: Pw = 0.5C f ρ(2πn) 3 (R 5 out - R 5 sh ) where, C f = drag coefficient ρ = coolant density (kg / m 2 ) R out = rotor outer diameter (m) R in = shaft diameter (m) C f =3.87 / R e 0.5 Re = 2πn ρR 2 out / μ Here, μ = kinematic viscosity of the working fluid (Pa S)

[0063]

[0082] For a fixed rotor size (e.g., 10-inch outer diameter, 2-inch shaft diameter), the electromachine will only be able to generate a fixed amount of power (e.g., 1,000 watts), limited by the capacity of the cooling system to remove heat and the electromagnetic design. If this fixed amount of power is exceeded due to windage losses, the machine will no longer be able to operate at that speed and supply power. This can usually be observed during acceleration, during which the motor will stop accelerating once it reaches its maximum available power. For example, Figure 18 shows a plot of windage losses (watts) against rotor speed (revolutions per minute). The first line 1810 represents an oil-cooled motor, and the second line 1820 represents an air-cooled motor. The maximum power line limit 1830 represents the maximum power that can be generated, limited by the capacity of the cooling system to remove heat and the electromagnetic design. In Figure 18, the maximum power limit 1830 is 1,000 watts.

[0064]

[0083] As shown in Figure 18, oil-cooled motors reach their maximum power limit at low speeds (e.g., 440 rpm), while air-cooled motors only reach their maximum power limit at 6400 rpm. Therefore, air-cooled motors can reach higher speeds because they do not need to overcome the viscous drag of the cooling fluid. Thus, cooling technologies that do not immerse the motor in a cooling fluid can realize motors that can reach higher speeds and have higher power density.

[0065]

[0084] Figure 19 shows an exemplary flowchart illustrating a process 1900 for cooling an electric motor according to one embodiment of the present disclosure. In some implementations, one or more process blocks of Figure 19 can be executed by an electromechanical device. In some implementations, one or more process blocks of Figure 19 can be executed by a separate device or group of devices, either separate from or including an electromechanical device.

[0066]

[0085] The method may include guiding a cooling fluid from a manifold in a hub through a first channel extending through a first pole retainer configured for attaching a first pole to a hub (1910). This technique can be applied to one or more components of a TORUS AFPM pole (e.g., a stator), a salient pole retainer for a rotor, an axial field topology rotor, a radiating field topology rotor, a linear motor, or several combinations thereof. The cooling fluid can be pressurized with a pump and guided through a channel passing through one or more pole retainers of the motor poles to the manifold in a hub.

[0067]

[0086] The method may include absorbing heat generated by one or more first coils attached to a first pole using a cooling fluid (1920). When an alternating current is passed through the coils of a motor to generate a magnetic field, heat is generated from the coils of the motor. The heat can be transferred via conduction from one or more first coils or one or more first permanent magnets attached to the pole. The heat can be further transferred by convection into the surrounding air and by a cooling fluid circulating through the pole.

[0068]

[0087] The method may include a fluid transfer duct and a cooling fluid from a first channel to a second channel extending through a second pole retainer configured to attach a second pole to a hub (1930). The fluid transfer duct may be a manifold. The fluid transfer duct may be a tube or a pipe. Pressure from a pump can guide the fluid through the fluid transfer duct from the first channel to the second channel.

[0069]

[0088] The pump can pressurize the cooling fluid, guiding it through the channel, through one or more pole retainers on the motor poles, and through the manifold in the hub. In various embodiments, a second pole retainer may be adjacent to the first pole retainer. The second pole may be a stator for the TORUS AFPM pole.

[0070]

[0089] The method may include absorbing heat generated by one or more second coils attached to a second pole using a cooling fluid (1940). Heat can be transmitted to the pole via conduction from one or more second coils or one or more second permanent magnets. Heat can be further transmitted by convection into the surrounding air and by a cooling fluid circulating through the pole.

[0071]

[0090] This method may include guiding the cooling fluid from a second channel to a manifold in the hub (1950). Pressure from a pump can guide the cooling fluid from the second channel to the manifold.

[0072]

[0091] In various embodiments, the method may include guiding the cooling fluid through a heat exchanger in a manifold within a hub.

[0073]

[0092] In various embodiments, the method may include guiding the cooling fluid through a heat exchanger positioned between a first channel and a second channel.

[0074]

[0093] In various embodiments, the method may include circulating the cooling fluid by rotating the hub.

[0075]

[0094] In various embodiments, the method may include measuring the temperature of the cooling fluid via a temperature sensor in communication with the cooling fluid.

[0076]

[0095] The specific details of particular embodiments may be combined in any suitable manner without departing from the spirit and scope of the embodiments disclosed, or may differ from those shown and described herein.

[0077]

[0096] Process 1900 may include additional implementations, such as any single implementation or any combination of implementations described below, and / or in relation to one or more other processes described elsewhere in this specification. It should be understood that the specific steps shown in Figure 19 provide a particular technique for cooling an electric motor according to various embodiments of this disclosure. Other sequences of steps may also be carried out according to alternative embodiments. For example, alternative embodiments of this disclosure may perform the steps outlined above in a different order. Furthermore, the individual steps shown in Figure 19 may include multiple substeps that can be performed in various orders as appropriate to the individual steps. While Figure 19 shows an example of the steps of Process 1900, in some implementations, Process 1900 may include additional steps, fewer steps, different steps, or steps in different arrangements than those depicted in Figure 19. Additionally or alternatively, two or more steps of Process 1900 may be performed in parallel. Furthermore, additional steps may be added or removed depending on the specific application. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0078]

[0097] The above description of exemplary embodiments of the Disclosure is provided for illustrative and explanatory purposes only. The above description is not intended to be exhaustive or to limit the Disclosure to the exact form described, and many modifications and variations are possible in light of the above teachings. The embodiments are selected and described to best illustrate the principles of the Disclosure and its practical applications, thereby enabling those skilled in the art to best utilize the Disclosure with various embodiments and modifications suited to their specific intended applications.

[0079]

[0098] All publications, patents, and patent applications cited herein are incorporated herein by reference in their entirety for all purposes.

[0080]

[0099] The methods, systems, and devices discussed above are examples. Various configurations may omit, substitute, or add various procedures or components as appropriate. For example, in alternative configurations, the method may be performed in a different order than described, and / or various steps may be added, omitted, and / or combined. Also, features described for a particular configuration may be combined in various other configurations. Different aspects and elements of configurations may be combined in similar ways. Furthermore, technology evolves, and therefore many elements are illustrative and do not limit the scope of disclosure or claims.

[0081]

[0100] Specific details are given in the description to provide a complete understanding of the example configuration (including implementation). However, the configuration may be carried out without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques are shown without unnecessary details to avoid obscuring the configuration. The description provides only example configurations and does not limit the claims, applicability, or configurations. Rather, the foregoing description of the configuration will provide a valid explanation for those skilled in the art to carry out the described techniques. The function and arrangement of elements may be modified in various ways without departing from the spirit or scope of the disclosure.

[0082]

[0101] Furthermore, the configuration may be described as a process, depicted as a flow chart or block diagram. Each may describe operations sequentially, although many operations can be executed in parallel or concurrently. The order of operations may also be rearranged. The process may include additional steps not shown in the diagram. In addition, examples of methods may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. If implemented in software, firmware, middleware, or microcode, the program code or code segments for performing the required tasks may be stored in a non-temporary computer-readable medium such as a storage medium. The processor may perform the described tasks.

[0083]

[0102] Having described several exemplary configurations, various variations, alternative configurations, and equivalents may be used without departing from the spirit of this disclosure. For example, the elements described above may also be components of a larger system, and other rules may take precedence over the application of the disclosure, or may otherwise be modified. Furthermore, many steps may be taken before, during, and after considering the elements described above.

Claims

1. A pole retainer having a proximal end attached to the hub and a distal end, for holding the pole to the hub, A channel extending through the pole retainer from the proximal end to the distal end of the pole retainer, A mount positioned at the distal end of the pole retainer and configured to hold the pole on the hub, A fluid transfer duct connected to the mount, A pole retainer device equipped with the following features.

2. The pole retainer device according to claim 1, wherein the fluid transfer duct is connected to a capacitor including one or more fins and a reservoir.

3. The pole retainer device according to claim 1, wherein the channel is configured to be connected to a manifold integrated with the hub.

4. The pole retainer device according to claim 1, wherein the channel is configured to contain a liquid coolant.

5. The pole retainer device according to claim 1, wherein the channel is configured to include a heat pipe.

6. The pole retainer device according to claim 1, wherein the distal end of the pole retainer is threaded.

7. The pole retainer device according to claim 1, wherein the fluid transfer duct comprises a tube.

8. The pole retainer device according to claim 1, wherein the fluid transfer duct comprises a pipe.

9. The stator pole includes a recess and is configured to hold at least one of a coil or a magnet, A pole retainer configured to fit inside the recess of the stator pole and to attach the stator pole to the hub, wherein the pole retainer is A channel extending through the pole retainer from the proximal end to the distal end of the pole retainer, which is configured to be attached to the hub, A proximal mount is positioned at the proximal end of the pole retainer and configured to attach the pole retainer to the hub, A pole retainer comprising: a distal mount positioned at the distal end of the pole retainer and configured to connect the channel to a fluid transfer duct; A system for cooling electric motors, equipped with [a specific feature / feature].

10. The hub comprises an integrated fluid manifold, further comprising the system for cooling an electric motor according to claim 9.

11. The system for cooling an electric motor according to claim 10, further comprising a fluid seal disposed between the proximal mount and the hub.

12. The system for cooling an electric motor according to claim 9, wherein the fluid transfer duct is connected to a capacitor having one or more fins and a reservoir.

13. The system for cooling an electric motor according to claim 9, wherein the channel is configured to be connected to a manifold integrated with the hub.

14. The system for cooling an electric motor according to claim 9, wherein the channel is configured to contain a liquid coolant.

15. The system for cooling an electric motor according to claim 9, wherein the channel is configured to include a heat pipe.

16. To guide cooling fluid from the manifold within the hub through a first channel extending through a first pole retainer configured to attach the first pole to the hub, The cooling fluid absorbs the heat generated by one or more first coils or one or more first permanent magnets attached to the first pole, The cooling fluid is guided through a fluid transfer duct from the first channel to a second channel extending through a second pole retainer configured to attach a second pole to the hub, The cooling fluid absorbs the heat generated by one or more second coils or one or more second permanent magnets attached to the second pole, The cooling fluid is guided from the second channel to the manifold of the hub, A method for cooling an electric motor, comprising [a specific component].

17. The method according to claim 16, further comprising guiding the cooling fluid through a heat exchanger in the manifold within the hub.

18. The method according to claim 16, further comprising guiding the cooling fluid through a heat exchanger positioned between the first channel and the second channel.

19. The method according to claim 16, further comprising circulating the cooling fluid by rotating the hub.

20. The method according to claim 16, further comprising measuring the temperature of the cooling fluid via a temperature sensor in communication with the cooling fluid.

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