Electric motor with intrinsic cooling system

Abstract

The present disclosure relates to an electric motor comprising a stator (101), which is a stationary part of the electric motor, the stator (101) having a plurality of radially mounted poles, and a rotor (102) having a plurality of magnets and arranged to rotate freely around the stator (101), the stator (101) and the rotor (102) being molded into an epoxy layer of a housing of the motor in such a way that channels (106) are formed that allow a cooling medium to flow through an inner part of the electric motor.

Description

[Technical field]

[0001] Technical Field The present disclosure relates generally to the field of electric motors. More particularly, the present disclosure relates to a system for cooling electric motors, and more particularly, to an outer rotor motor. [Background technology]

[0002] Background technology In recent years, there has been an increasing interest in using electric motors in various applications such as electric vehicles, drones, boats, pumps, etc. There are many different types of electric motors, some examples are synchronous or asynchronous motors, DC or AC motors, brushed or brushless motors, inrunner or outrunner motors.

[0003] In general, an electric motor is an electric machine that converts electrical energy into mechanical energy in the form of rotation. Electric motors work by the interaction of the motor's magnetic field with the electromagnetic fields that arise from electrically induced windings. The interaction between these magnetic fields is a rotating electromagnetic field, which in turn produces a rotational force, called torque, in the form of, for example, rotation of a shaft.

[0004] While there are many different types of motors on the market, this disclosure will focus primarily on electric brushless DC electric motors with an outer rotor, known as an outrunner.

[0005] A typical configuration for an outrunner includes a stator having windings or poles located at the center of the motor, and a rotor having permanent magnets adapted to rotate around the stator. This configuration is usually larger in diameter than other types of electric motors, allowing more windings, poles or magnets to be placed on the rotor, increasing the rotating magnetic field.

[0006] Additionally, a larger diameter travels a larger circumference during one revolution of the motor. A larger diameter also results in a larger outrunner moment arm, which results in higher torque. A larger outrunner moment arm can potentially provide higher torque at a constant speed.

[0007] A recognized problem with outrunners is that heat from the stator poles is conducted to the center of the motor, causing the outrunner to overheat and limiting the maximum power that can be applied. Also, large amounts of heat can weaken the magnets and damage the winding or pole insulation, severely limiting the range of applications in which outrunners can be implemented. Summary of the Invention [Problem to be solved by the invention]

[0008] Summary of the Invention SUMMARY OF THE DISCLOSURE It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and shortcomings in the prior art or to solve at least the above-stated problems. [Means for solving the problem]

[0009] According to a first aspect, there is provided an electric motor comprising a housing having a stationary inner portion and a rotatable outer portion, a stator attached to the stationary inner portion of the housing, and a rotor attached to the rotatable outer portion of the housing and arranged to rotate freely around the stator, the rotatable outer portion having at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium, the stator and rotor being separately moulded in respective epoxy layers, and a channel being disposed between the moulded rotor and the moulded stator for directing the cooling medium axially of the housing and in fluid communication with the at least one inlet and the at least one outlet, forming an inherent cooling system of the electric motor.

[0010] The epoxy layer protects the stator and rotor from liquids leaking into the electrical circuitry. This is accomplished by molding the stator in an epoxy layer and the rotor in another epoxy layer, so no additional seals are needed.

[0011] This channel or passage between the stator and the rotor allows a cooling medium to pass through, thus reducing the temperature of the inner portion of the rotor facing the stator.

[0012] The combination of the use of an electric motor capable of reaching high torque forces with an intrinsic cooling system according to the present disclosure provides an electric motor that does not require a gearbox, is much more efficient than previous versions of electric motors, and allows for a higher power density than previous motor designs.

[0013] Furthermore, no additional seals are required, providing robustness to the motor and reducing standard wear parts.

[0014] Further, the channel allows a cooling medium to flow through the electric motor and is formed in fluid communication with at least one inlet adapted to introduce the cooling medium into the channel and at least one outlet adapted to expel the cooling medium from the channel by centrifugal force during rotation of the rotor.

[0015] Additionally, the at least one outlet may discharge the cooling medium due to centrifugal forces generated during rotation of the rotor.

[0016] Since the rotor is in the outer part of the housing, when the rotor is rotated, it is possible to discharge the cooling medium through at least one outlet arranged in the outer part of the housing. When the electric motor is in operation, the cooling medium can be expelled from the outlet by using rotational or centrifugal forces. In this way, the cooling medium is always kept at a low temperature because it moves continuously from the at least one inlet to the at least one outlet.

[0017] According to some embodiments, the motor may further comprise an additional channel. The additional channel may be arranged to allow the cooling medium to flow through the motor. The additional channel may extend, for example, axially through a center of the motor. The additional channel may extend, for example, axially through a center of the stationary inner portion of the housing. By providing the additional channel, the cooling medium may flow through the motor.

[0018] According to some embodiments, the electric motor may include at least one outlet, the outlet being disposed in an outer portion of the housing and adapted to expel the cooling medium from the channel by centrifugal force during rotation of the rotor.

[0019] According to some embodiments, an electric motor may include a housing, a stator, a rotor, a channel, and at least one outlet. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be separately molded in a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium in an axial direction of the housing and in fluid communication with the at least one inlet and the at least one outlet to form an inherent cooling system of the electric motor. The at least one outlet may be disposed in the outer portion of the housing and adapted to exhaust the cooling medium from the channel by centrifugal force during rotation of the rotor.

[0020] According to some embodiments, the at least one inlet may be arranged on the inner surface of the stationary inner part. By providing the at least one inlet on the inner surface of the stationary inner part, the flow of the cooling medium through the channel can be improved. For example, the cooling medium can be pushed towards the at least one inlet by centrifugal forces or by rotational forces occurring during rotation of the rotor. Furthermore, the cooling medium discharged from the at least one outlet can provide suction at the at least one inlet through the channel. According to some embodiments, the at least one inlet may be arranged on the stator towards the additional channel. By providing the at least one inlet on the inner surface of the stationary inner part, the flow of the cooling medium through the channel can be improved. For example, the cooling medium can be pushed from the additional channel towards the at least one inlet by centrifugal forces or by rotational forces occurring during rotation of the rotor. Furthermore, the cooling medium discharged from the at least one outlet can provide suction at the at least one inlet through the channel.

[0021] According to some embodiments, at least one inlet may comprise a fluid directing means, such as an extension located at an edge of the inlet to direct the flowing cooling medium towards the inlet. The extension may be located in a portion of the inlet that is downstream from the flowing cooling medium or after the inlet. The extension may further have a concave surface to further direct the flowing cooling medium towards the inlet.

[0022] According to some embodiments, at least one inlet may comprise a fluid directing means, such as a recessed portion located at an edge of the inlet to direct the flowing cooling medium towards the inlet. The recessed portion may be located at a portion of the inlet that is upstream from the flowing cooling medium or in front of the inlet. The extension may further have a concave surface to further direct the flowing cooling medium towards the inlet.

[0023] According to some embodiments, the position of the fluid directing means may be determined based on the direction of the coolant flow during operation of the motor. According to some embodiments, the additional channel may be or may be referred to as a central channel and / or a motor channel.

[0024] According to some embodiments, an electric motor may include a housing, a stator, a rotor, and a channel. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be separately molded within a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium axially of the housing and in fluid communication with the at least one inlet and at least one outlet to form an inherent cooling system of the electric motor.

[0025] Additionally, the inherent cooling system may include an additional channel extending axially through the center of the stationary inner portion of the housing and arranged for the flow of a cooling medium.

[0026] Additionally, some of the outlets may be aligned on the circumference of the rotating outer portion of the housing.

[0027] When the outlets are aligned on the periphery of the outer portion of the housing, the cooling medium is discharged in a distributed manner around the surface of the outer portion.

[0028] Additionally, the rotating outer portion of the housing is at least partially cylindrical.

[0029] The partial cylindrical shape allows the cooling medium to flow axially, thereby cooling a large portion of the internal motor.

[0030] Furthermore, the outlet can be either a circular opening, a slit, or a conical opening. The shape depends, for example, on the density of the cooling medium or the position of the magnets on the rotor. The flexibility of the electric motor configuration provides optimal efficiency.

[0031] According to some embodiments, the epoxy layer may be at least partially electrically insulating. For example, the at least partially electrically insulating epoxy layer may have an electrical insulation greater than 100 Ω per mm thickness. Also, the electrically insulating epoxy layer may have an electrical insulation greater than 1 kΩ per mm thickness, 10 kΩ per mm thickness, 100 kΩ per mm thickness, 1 MΩ per mm thickness, 10 MΩ per mm thickness, 100 MΩ per mm thickness, 1000 MΩ per mm thickness, or 10,000 MΩ per mm thickness.

[0032] According to some embodiments, the epoxy layer may be electrically insulating. For example, the electrically insulating epoxy layer may have an electrical insulation of greater than 100 Ω per mm thickness. Also, the electrically insulating epoxy layer may have an electrical insulation of greater than 1 kΩ per mm thickness, 10 kΩ per mm thickness, 100 kΩ per mm thickness, 1 MΩ per mm thickness, 10 MΩ per mm thickness, 100 MΩ per mm thickness, 1000 MΩ per mm thickness, or 10,000 MΩ per mm thickness.

[0033] According to some embodiments, the epoxy layer may be at least partially thermally conductive. For example, the at least partially thermally conductive epoxy layer may have a thermal conductivity of greater than 0.5 Watts per millikelvin (W / mK). Also, the thermally conductive epoxy layer may have a conductivity of 1 W / mK.

[0034] According to some embodiments, the epoxy layer can be thermally conductive. For example, the thermally conductive epoxy layer can have a thermal conductivity of greater than 0.5 Watts per millikelvin (W / mK). Also, the thermally conductive epoxy layer can have a conductivity of 1 W / mK.

[0035] According to some embodiments, the epoxy layer may be at least partially thermally conductive and electrically insulating. For example, the at least partially electrically insulating epoxy layer may have an electrical insulation of greater than 100 Ω per mm thickness. The electrically insulating epoxy layer may have an electrical insulation of greater than 1 kΩ per mm thickness, 10 kΩ per mm thickness, 100 kΩ per mm thickness, 1 MΩ per mm thickness, 10 MΩ per mm thickness, 100 MΩ per mm thickness, 1000 MΩ per mm thickness, or 10,000 MΩ per mm thickness. For example, the at least partially thermally conductive epoxy layer may have a thermal conductivity of greater than 0.5 Watts per millikelvin (W / mK). The thermally conductive epoxy layer may have a conductivity of 1 W / mK.

[0036] According to some embodiments, the epoxy layer may be thermally conductive and electrically insulating. For example, the electrically insulating epoxy layer may have an electrical insulating property of more than 100 Ω per mm thickness. The electrically insulating epoxy layer may have an electrical insulating property of more than 1 kΩ per mm thickness, 10 kΩ per mm thickness, 100 kΩ per mm thickness, 1 MΩ per mm thickness, 10 MΩ per mm thickness, 100 MΩ per mm thickness, 1000 MΩ per mm thickness, or 10,000 MΩ per mm thickness. For example, the thermally conductive epoxy layer may have a thermal conductivity of more than 0.5 Watts per millikelvin (W / mK). The thermally conductive epoxy layer may have a conductivity of 1 W / mK. According to some embodiments, the epoxy layer may have a low viscosity, such as in the range of 1400-2200 cPs at 23° C. and 100 rpm. The epoxy layer may further be homogenous and / or thermally stable.

[0037] According to some embodiments, the epoxy layer may be curable at room temperature.

[0038] According to some embodiments, an electric motor may include a housing, a stator, a rotor, and a channel. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be separately molded in a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium axially of the housing and in fluid communication with the at least one inlet and the at least one outlet to form an inherent cooling system of the electric motor. The epoxy layer may be thermally conductive and electrically insulating.

[0039] Furthermore, the electric motor is arranged to operate submerged and the cooling medium is water.

[0040] The advantage of arranging the motor to operate submerged is that it can be used in offshore or marine applications such as submarines, boats, pumps, etc. Furthermore, the operation of the electric motor is facilitated since no additional vessel with a cooling medium is required.

[0041] According to some embodiments, the magnets of the rotor may be arranged in a magnetization pattern that concentrates their combined magnetic flux at the center of the rotor. The rotor may be hollow, for example having a cylindrical shape, in which case the magnetic flux may be concentrated at the hollow center of the cylindrical rotor. The hollow center may comprise additional components.

[0042] According to some embodiments, the magnets of the rotor may be arranged in a Halbach configuration, which directs the magnetic field strength toward the center of the rotor. By directing the magnetic field, a more efficient and / or compact arrangement of the magnets may be achieved, which may maximize the size of the cooling fluid channel between the stator and the rotor without reducing the motor efficiency. The rotor may be hollow, e.g., having a cylindrical shape, and the magnetic flux may be concentrated in the hollow center of the cylindrical rotor. The hollow center may include additional components.

[0043] According to some embodiments, the magnets may include a high magnetic flux alloy, such as, for example, neodymium steel.

[0044] According to some embodiments, magnets arranged in a Halbach configuration may be arranged in a spatially rotating magnetization pattern to enhance the magnetic field on one side of the configuration while canceling the magnetic field to near zero on the other side of the configuration.

[0045] According to some embodiments, an electric motor may include a housing, a stator, a rotor, and a channel. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotor may include magnets arranged in a Halbach configuration. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be molded separately within a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium axially of the housing and in fluid communication with the at least one inlet and the at least one outlet to form an inherent cooling system of the electric motor.

[0046] According to some embodiments, the motor may further comprise at least one propeller, which may be disposed on a rotatable portion of the motor, such as the rotor, and / or in communication with the rotor, such that rotational force that the electric motor may provide to the rotor may be converted into thrust by rotational motion of the rotor and the propeller.

[0047] According to some embodiments, the motor may further comprise a propeller connector, the propeller connector arranged to be connected to the at least one propeller.

[0048] According to some embodiments, the propeller may include a hub and a number of radial blades set at a pitch that forms a helix that, as it rotates, acts on a working fluid, such as water, thereby converting rotational force into linear thrust.

[0049] According to some embodiments, the propeller may be a screw propeller.

[0050] According to some embodiments, the propellers may be arranged to operate submerged.

[0051] According to some embodiments, the motor may further comprise an impeller.

[0052] According to some embodiments, an electric motor may include a housing, a stator, a rotor, a channel, and a propeller. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be separately molded in a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium axially of the housing and in fluid communication with the at least one inlet and the at least one outlet to form an inherent cooling system of the electric motor. The propeller may be disposed on the rotor, and the epoxy layer may be thermally conductive and electrically insulating.

[0053] According to some embodiments, an electric motor may include a housing, a stator, a rotor, a channel, and a propeller. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be separately molded within a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium axially of the housing and in fluid communication with the at least one inlet and the at least one outlet to form an inherent cooling system of the electric motor. A propeller may be disposed on the rotor.

[0054] According to some embodiments, the motor may be arranged in a jet configuration with a second housing, which may be arranged to at least partially surround the motor and the propeller, thereby forming a peripheral channel between the second housing and the rotor, within which the propeller may interact with the liquid.

[0055] According to some embodiments, the motor may be arranged with the rotor in a hollow stator and the propeller disposed in the hollow rotor. This arrangement allows the propeller to interact with the fluid carried in the additional channel. Protecting the propeller inside the motor may provide a more durable motor.

[0056] According to some embodiments, the motor may be arranged with the rotor in a hollow stator and the propeller disposed in the hollow rotor. This arrangement allows the motor to drive the propeller from a position surrounding the propeller. Such an arrangement can be used to allow for a more easily constructed jet configuration by providing a motor drive closer to the housing as opposed to a centrally located drive.

[0057] According to some embodiments, the motor may be arranged in a jet configuration with a second housing, which may be arranged to at least partially surround the motor and the propeller, thereby forming a peripheral channel between the second housing and the rotor, within which the propeller may interact with the liquid.

[0058] According to some embodiments, there is provided an electric motor for powering a craft underwater. The craft may be, for example, a boat, a jet ski, a watercraft, a submarine, or the like. The motor powers a propeller and may operate submerged. The motor may be described in any of the embodiments disclosed herein.

[0059] According to some embodiments, the electric motors may be arranged as outboard motors, inboard motors, or as pods.

[0060] According to some embodiments, the electric motor may further comprise mounting means suitable for mounting the motor to a boat, for example the motor may be mounted to the transom, stern, hull, rudder and / or hydrofoil.

[0061] According to some embodiments, the electric motor may be configured to be mounted, for example, to the transom, stern, hull, rudder, and / or hydrofoil.

[0062] The present invention will become apparent from the detailed description given below. The detailed description and specific examples disclose preferred embodiments of the present invention for illustrative purposes only. Those skilled in the art will understand that, from the guidance of the detailed description, changes and modifications may be made within the scope of the present invention.

[0063] Thus, it will be understood that the invention disclosed herein is not limited to the specific components of the apparatus described or the steps of the methods described, as such apparatus and methods may vary. It will also be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in this specification and the appended claims, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of an element, unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include a plurality of apparatuses, and the like. Furthermore, the words "comprising," "including," "containing," and similar words do not exclude other elements or steps.

[0064] Terminology - The term "channel" is to be interpreted as a gap, passage or space that conveys a liquid from an origin to an end point.

[0065] BRIEF DESCRIPTION OF THE DISCLOSURE The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully understood by reference to the following illustrative and non-limiting detailed description of exemplary embodiments of the invention, when considered in conjunction with the accompanying drawings. [Brief description of the drawings]

[0066] [Figure 1] 1 illustrates a cross-sectional view of an electric motor according to an example of the present disclosure. [Figure 1b] 1 shows a schematic cross-sectional view of an electric motor according to an example of the present disclosure. [Figure 1c] 1 shows a schematic cross-sectional view of an inlet according to an example of the present disclosure. [Figure 1d] 1 shows a schematic cross-sectional view of an inlet according to an example of the present disclosure. [Figure 2A] 1 illustrates an exploded view of a rotating outer portion of a housing of an example electric motor according to the present disclosure. [Figure 2B] 1 illustrates a perspective view of a rotating outer portion of a housing of an example electric motor according to the present disclosure; [Figure 2C] 1 illustrates a perspective view of a stationary inner portion of a housing of an example electric motor according to the present disclosure. [Figure 3A] 1 shows a perspective view of one embodiment of an electric motor according to the present disclosure; [Figure 3B] 1 shows a perspective view of one embodiment of an electric motor according to the present disclosure; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0067] Detailed Description The present invention will now be described with reference to the accompanying drawings, in which preferred embodiments of the present invention are shown. However, the present invention may be embodied in other forms and should not be construed as being limited to the embodiments disclosed herein. The disclosed embodiments are provided to fully convey the scope of the present invention to those skilled in the art.

[0068] 1 shows a cross-sectional view of an electric motor according to an embodiment of the present disclosure. The electric motor comprises a housing 100 having a rotating outer portion 120 made of a non-oxidizing material and that is at least partially cylindrical. However, various shape variations are possible. For example, a partially cylindrical shape with conical or rounded ends is also considered a viable option.

[0069] The housing 100 has a stationary inner portion 110 and a rotatable outer portion 120, with a stator 101 supported on the stationary inner portion 110 and a rotor 102 attached to the rotatable outer portion 120. The rotor is arranged to rotate freely around the stator 101.

[0070] The stator 101, supported by the stationary inner part 110, comprises a stator core with a number of radially arranged poles and a winding or conductor attached to each pole. The rotating outer part of the housing 120 houses the rotor 102, which includes a number of permanent magnets. The rotor 102 is also attached to the stator 101 by ball bearings 103A, 103B or any similar element at either end of the housing 100 so as to rotate freely around the stator and leave a channel 106 between them. The size of the channel 106 may vary depending on the result to be achieved. To obtain an efficient electric motor, the electromagnetic field in the channel 106 between the rotor and the stator needs to be as small as possible. At the same time, the channel 106 should be as large as possible to provide a more efficient cooling system. A balance between these two constraints therefore provides an optimal approach to obtain an efficient electric motor.

[0071] When the stator operates in conjunction with the rotor 102 and is powered by direct current DC, the pole currents interact with the motor's magnetic field, generated by the magnets in the rotor 102, to provide a rotational force or torque that rotates the rotor. The motor may be mounted on a propeller shaft or any other rotatable shaft, depending on the application of the electric motor.

[0072] As can be seen by the dashed lines in Fig. 1, the stator 101 and rotor 102 are each separately molded in their own epoxy layer 107A, 107B. In other words, the stator is encapsulated or molded in the epoxy layer 107A, which prevents and protects the stator from being damaged by any cooling medium such as water. However, it does not necessarily have to be an epoxy layer, but can be any other layer, for example plastic or resin, that protects the stator and rotor from damage due to ingress of water and dust.

[0073] Like the stator 101, the rotor 102 may be encapsulated or molded in an epoxy layer 107B to prevent moisture, rust, dust, cooling medium or water from entering the inner portion of the rotor. By encapsulating the rotor 102 and the stator 101 in separate epoxy layers, the channel 106 between the rotor 102 and the stator 101 is isolated and sealed from the inner portions of the stator and rotor. This isolation or sealing allows a cooling medium, such as water, to flow through the channel 106, which has at least inlets 104A, 104B and at least outlets 105A, 105B. The exemplary embodiment of FIG. 1 shows a rotatable outer portion 100 having at least one inlet 104A, 104B at the junction of each bearing 103A, 103B mounted at each end of the housing 100. These inlets 104A, 104B are configured to receive a cooling medium and may be natural inlets caused by joints when bearings are used to attach the rotor 102 to the stator 101 or other edge differences between the stator and rotor. The cooling medium may be introduced through at least one of the inlets 104A, 104B in different ways depending on the application of the electric motor.

[0074] In some embodiments, the application of the electric motor is outside of an aqueous environment and the cooling medium is introduced from an external vessel through an inlet, such as a joint associated with a bearing or any other suitable support element, and reintroduced into the vessel through one of the outlets described below.

[0075] Returning to FIG. 1 , a cooling medium, such as water, enters through inlets 104A, 104B and flows through channels 106. The channels 106 are disposed between the formed rotor and the formed stator to direct the cooling medium in the axial direction of the housing 100 and in fluid communication with at least one inlet 104A, 104B and at least one outlet 105A, 105B to form an inherent cooling system of the electric motor. The inherent cooling system is configured to cool an inner portion of the motor. The introduced cooling medium is then discharged from the channels 106 through at least one outlet 105A, 105B configured to discharge the cooling medium by centrifugal or rotational forces generated during rotation of the rotor 102 on the rotatable outer portion 120 of the housing.

[0076] The outlets 105A, 105B are openings that pass through both the rotatable outer portion of the housing 120 and the rotor 102 and are in fluid communication with the inner channel 106. The shape of the outlets 105A, 105B can be any type of circular opening, slit, square, star, borehole, conical opening, or small diameter opening arranged on a circular ring or arranged around the circumference of the rotating outer portion of the housing 120. The outlets 105A, 105B can be single or multiple and can be located anywhere on the rotating outer portion of the housing 120.

[0077] However, magnets located inside the rotor limit the space available to locate these outlets, so the location of the outlets and the spacing between them may vary, as well as the size of the diameter of each outlet.

[0078] FIG. 1b shows a schematic diagram of a subset of an electric motor, which shows a stator 101 and a rotor 102. The stator and rotor are part of the electric motor and are arranged in a rotationally symmetrical manner. In the center of the figure, an additional channel 108 is shown, which runs axially through the center of the electric motor and is arranged to allow the flow of cooling medium inside the stator 101. The additional channel 108 runs along the motor axis of the electric motor. The counter-rotating electric motor configuration therefore comprises a central channel 108 for the cooling medium, referred to herein as the additional channel, which runs through the center of the inner stator 101 along the motor axis of the electric motor. The figure further shows a channel 106 arranged between the rotor and the stator to guide the cooling medium at least partially in the axial direction of the motor and in fluid communication with at least one inlet 104 and at least one outlet 105 to form an inherent cooling system of the electric motor. The at least one inlet 104 is shown arranged on the inner surface of the stator 101, which inner surface faces the additional channel 108. At least one outlet 105 is located on the outer surface of the rotor 102. In the figure, four inlets and two outlets are shown, but it should be understood that this is shown by way of example and other combinations are possible. The stator and / or rotor may be provided with inlets and / or outlets located on the rims of the stator and / or rotor and / or between them. In the figure, an inlet 104 is shown located on the stator 101.

[0079] FIG. 1c shows a schematic diagram of an inlet 104 with an extension 109c located at the edge of the inlet to direct the flowing cooling medium towards the inlet 104. The extension is located downstream of the inlet 104 in the flow direction of the cooling medium. The extension may have different shapes, the triangular shape shown is only an example. In the example shown, the extension protrudes from the inner surface of the stator into the additional channel 108 and increases the flow of cooling medium from the additional channel through the inlet 104 into the channel 106 of the intrinsic cooling system.

[0080] FIG. 1d shows a schematic diagram of an inlet 104 with a recessed portion 109d located at the edge of the inlet to direct the flowing cooling medium towards the inlet 104. The recessed portion 109d is located upstream of the inlet 104 in the flow direction of the cooling medium. The recessed portion may have different shapes, the illustrated triangular cutout shape being an example. In the illustrated example, the recessed portion forms a recess in the inner surface of the stator and increases the flow of the cooling medium from the additional channel through the inlet 104 to the channel 106 of the intrinsic cooling system.

[0081] In another exemplary embodiment, the electric motor may operate underwater or submerged and may be used in a variety of applications, such as dredge pumps, deep well pumps, sewage pumps, boats, ships or submarines.

[0082] The electric motor may further be arranged to operate in submersible conditions, and the cooling medium may be water. In the case of a submersible electric motor, the cooling system described above may be enhanced by having an additional channel 108 extending axially through the center of the stationary inner part of the housing and arranged to allow the cooling medium to flow. The center of the stationary inner part 110 is hollow to allow the water to flow axially through the outer part of the stator 101. The water may be introduced from the hollow part of the housing via a fan or propeller P arranged on the outer front part of the rotor 102. The water is then led axially of the housing towards the back side of the electric motor, as shown in Figures 1 and 3. The hollow part or additional channel 108 may be a single channel or may be configured to be a number of small channels or openings parallel to each other through which the water can flow. The more the water passes through the additional channel, the cooler the electric motor will be.

[0083] In another exemplary embodiment, the electric motor is outside the water environment and the additional channel 108 is closed or sealed at both ends leaving an empty space inside the motor with access to at least one inlet for introducing the cooling medium from an external container and at least one outlet for discharging the cooling medium to the same or another external container. Once introduced in this additional channel 108, the cooling medium cools the inner parts of the motor, specifically the rotating outer parts of the stator. Other variations in the introduction or discharge of the cooling medium are possible.

[0084] The motor may further comprise an additional channel 108. The additional channel 108 may be arranged such that the cooling medium can flow through the motor. The additional channel 108 may extend, for example, axially through the center of the motor. The additional channel may extend, for example, axially through the center of the stationary inner part of the housing. By providing the additional channel, the cooling medium can flow through the motor.

[0085] The electric motor may comprise at least one outlet, which may be disposed in an outer portion of the housing and adapted to expel the cooling medium from the channel by centrifugal force during rotation of the rotor.

[0086] In another exemplary embodiment, an electric motor may include a housing, a stator, a rotor, a channel, and at least one outlet. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be separately molded in a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium axially of the housing and in fluid communication with the at least one inlet and the at least one outlet to form an inherent cooling system of the electric motor. The at least one outlet may be disposed in the outer portion of the housing and adapted to exhaust the cooling medium from the channel by centrifugal force during rotation of the rotor.

[0087] The at least one inlet may be disposed on an inner surface of the stationary inner portion.

[0088] At least one inlet may be disposed in the stator towards the additional channel.

[0089] At least one inlet may comprise a fluid directing means, such as an extension located at an edge of the inlet, for directing the flowing cooling medium towards the inlet. The extension may be located at a portion of the inlet that is behind the inlet from the flowing cooling medium. The extension may further have a concave surface to further direct the flowing cooling medium towards the inlet. According to some embodiments, at least one inlet may comprise a fluid directing means, such as a recessed portion located at an edge of the inlet, for directing the flowing cooling medium towards the inlet. The recessed portion may be located at a portion of the inlet that is ahead of the inlet from the flowing cooling medium. The extension may further have a concave surface.

[0090] The position of the flow directing means may be determined based on the direction of coolant flow during operation of the motor.

[0091] The additional channel 108 may be or may be referred to as a central channel and / or a motor channel.

[0092] In another exemplary embodiment, an electric motor may include a housing, a stator, a rotor, and a channel. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be separately molded within a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium axially of the housing and in fluid communication with the at least one inlet and at least one outlet to form an inherent cooling system of the electric motor.

[0093] FIG. 2A shows an exploded view and FIG. 2B shows a perspective view of a rotating outer portion of a housing 220 of an example electric motor according to the present disclosure.

[0094] The housing 220 is cylindrical in shape with an enclosing surface, a top surface and a bottom surface. A series of openings 205A, 205B are visible in the outer enclosing surface of the housing 220. The openings 205A, 205B are outlets spaced apart from one another and aligned along each end side of the enclosing surface, forming a ring shape around the outer part of the housing, allowing the cooling medium or water to be discharged from the stationary inner part of the housing during use. Each ring shape formed by the outlets 205A or 205B is at a different distance from the inlet. These distances leave enough space for the introduced cooling medium or water to flow through the stationary inner part of the housing and reduce the internal temperature of the outer motor.

[0095] In some embodiments, only some of the outlets are arranged in a ring around the outer portion of the housing, while other outlets are located on different parts of the outer surface of the housing. In some examples, the outlets can be located in any suitable manner that allows the water or cooling medium to be discharged from the housing, without necessarily forming a shape in the space between the permanent magnets of the rotor, i.e., in the center of the outer surface. Other examples may include only one outlet located anywhere on the outer surrounding surface 220.

[0096] FIG. 2C illustrates a perspective view of a stationary inner portion 210 of a housing of an electric motor according to one example of the present disclosure.

[0097] The stationary inner part 210 of the housing supports the stationary part of the motor, i.e. the stator. The stationary inner part 210 comprises a hollow structure in which the stator is attached after encapsulation in an epoxy layer. Such epoxy layer is moldable and protects any molded device from any liquid, dust, sand or moisture.

[0098] The molded stator is at least waterproof and dustproof. The same procedure is used for the rotor, which is then attached to the stator by bearings. The bearings allow the rotor to rotate freely without friction while leaving channels such as spaces, cavities, gaps, etc. between the rotor and the stator. Liquid introduced into the at least one inlet is carried by the channels to the at least one outlet without leaking into the rotor or stator.

[0099] The hollow portion of the structure is large enough to allow cooling media or water to flow through the center of the motor without adversely affecting the efficiency of the motor.

[0100] 3A and 3B show an example of a boat motor equipped with an electric motor of the present disclosure.

[0101] The boat motor shown in Figure 3A is an embodiment of the electric motor shown in Figure 1 mounted on an external propeller. When viewed from the front, it can be seen that the propeller is located forward of the electric motor on a shaft connected to the electric motor. The electric motor provides a rotational force or torque to the shaft with the intention of transmitting power by rotating the propeller 330 and converting the rotational motion into thrust.

[0102] In another embodiment (not shown), the propellers may be mounted on the rotating outer portion of the housing, utilizing the outer rotation of an electric motor. Other configurations are possible.

[0103] The shape of the propeller 330 blades is specially designed to create a pressure differential that accelerates water past the propeller 330 when the motor is submerged in water.

[0104] The cooled exterior water may flow not only along the exterior surface of the electric motor, but also through additional channels 308 inside the structure to reduce heat in the interior parts of the electric motor. Figure 3B shows another view of the electric motor showing the end of the additional channel 308 in the form of a tunnel or passageway.

[0105] The epoxy layer may be at least partially electrically insulating. For example, the at least partially electrically insulating epoxy layer may have an electrical insulation greater than 100 Ω per mm thickness. Also, the electrically insulating epoxy layer may have an electrical insulation greater than 1 kΩ per mm thickness, 10 kΩ per mm thickness, 100 kΩ per mm thickness, 1 MΩ per mm thickness, 10 MΩ per mm thickness, 100 MΩ per mm thickness, 1000 MΩ per mm thickness, or 10,000 MΩ per mm thickness.

[0106] The epoxy layer may be electrically insulating. For example, the electrically insulating epoxy layer may have an electrical insulation greater than 100 Ω per mm thickness. Also, the electrically insulating epoxy layer may have an electrical insulation greater than 1 kΩ per mm thickness, 10 kΩ per mm thickness, 100 kΩ per mm thickness, 1 MΩ per mm thickness, 10 MΩ per mm thickness, 100 MΩ per mm thickness, 1000 MΩ per mm thickness, or 10,000 MΩ per mm thickness.

[0107] The epoxy layer can be at least partially thermally conductive. For example, the at least partially thermally conductive epoxy layer can have a thermal conductivity of greater than 0.5 Watts per millikelvin (W / mK). And, the thermally conductive epoxy layer can have a conductivity of 1 W / mK.

[0108] The epoxy layer can be thermally conductive. For example, the thermally conductive epoxy layer can have a thermal conductivity of greater than 0.5 Watts per millikelvin (W / mK). For example, the thermally conductive epoxy layer can have a conductivity of 1 W / mK.

[0109] The epoxy layer may be at least partially thermally conductive and electrically insulating. For example, the at least partially electrically insulating epoxy layer may have an electrical insulation of greater than 100 Ω per mm thickness. The electrically insulating epoxy layer may have an electrical insulation of greater than 1 kΩ per mm thickness, 10 kΩ per mm thickness, 100 kΩ per mm thickness, 1 MΩ per mm thickness, 10 MΩ per mm thickness, 100 MΩ per mm thickness, 1000 MΩ per mm thickness, or 10,000 MΩ per mm thickness. For example, the at least partially thermally conductive epoxy layer may have a thermal conductivity of greater than 0.5 Watts per millikelvin (W / mK). The thermally conductive epoxy layer may have a conductivity of 1 W / mK.

[0110] The epoxy layer may be thermally conductive and electrically insulating. For example, the electrically insulating epoxy layer may have an electrical insulation of greater than 100 Ω per mm thickness. The electrically insulating epoxy layer may have an electrical insulation of greater than 1 kΩ per mm thickness, 10 kΩ per mm thickness, 100 kΩ per mm thickness, 1 MΩ per mm thickness, 10 MΩ per mm thickness, 100 MΩ per mm thickness, 1000 MΩ per mm thickness, or 10,000 MΩ per mm thickness. For example, the thermally conductive epoxy layer may have a thermal conductivity of greater than 0.5 Watts per millikelvin (W / mK). The thermally conductive epoxy layer may have a conductivity of 1 W / mK. According to some embodiments, the epoxy layer may have a low viscosity, such as in the range of 1400-2200 cPs at 23° C. and 100 rpm. The epoxy layer may also be homogeneous and / or thermally stable.

[0111] The epoxy layer may be allowed to cure at room temperature.

[0112] According to some embodiments, an electric motor may include a housing, a stator, a rotor, and a channel. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be separately molded in a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium axially of the housing and in fluid communication with the at least one inlet and the at least one outlet to form an inherent cooling system of the electric motor. The epoxy layer may be thermally conductive and electrically insulating.

[0113] The magnets of the rotor may be arranged in a magnetization pattern that concentrates their combined magnetic flux at the center of the rotor. The rotor may be hollow, for example having a cylindrical shape, in which case the magnetic flux may be concentrated at the hollow center of the cylindrical rotor. The hollow center may include additional components.

[0114] The magnets of the rotor may be arranged in a Halbach configuration, which directs the magnetic field strength toward the center of the rotor. The rotor may also be hollow, for example having a cylindrical shape, in which case the magnetic flux may be concentrated in the hollow center of the cylindrical rotor. The hollow center may include additional components.

[0115] The magnets may include a high magnetic flux alloy, such as, for example, neodymium steel.

[0116] Magnets arranged in a Halbach configuration may be arranged in a spatially rotating pattern of magnetization to increase the magnetic field on one side of the configuration and cancel the magnetic field to near zero on the other side of the configuration.

[0117] According to some embodiments, an electric motor may include a housing, a stator, a rotor, and a channel. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotor may include magnets arranged in a Halbach configuration. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be molded separately within a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium axially of the housing and in fluid communication with the at least one inlet and the at least one outlet to form an inherent cooling system of the electric motor.

[0118] The motor may further include at least one propeller, which may be disposed on and / or connected to a rotatable portion of the motor, such as a rotor.

[0119] The motor may further comprise a propeller connector, the propeller connector arranged to be connected to the at least one propeller.

[0120] A propeller may include a hub and a number of radial blades set at a pitch that forms a helix that, when rotated, acts on a working fluid, such as water, thereby converting rotational force into linear thrust.

[0121] The propeller may be a screw propeller.

[0122] The propeller may be arranged to operate underwater.

[0123] The motor may further include an impeller.

[0124] According to some embodiments, an electric motor may include a housing, a stator, a rotor, a channel, and a propeller. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be separately molded in a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium axially of the housing and in fluid communication with the at least one inlet and the at least one outlet to form an inherent cooling system of the electric motor. A propeller may be disposed on the rotor, and the epoxy layer may be thermally conductive and electrically insulating.

[0125] According to some embodiments, an electric motor may include a housing, a stator, a rotor, a channel, and a propeller. The housing may have a stationary inner portion and a rotatable outer portion. The stator may be supported by the stationary inner portion of the housing. The rotor may be attached to the rotatable outer portion of the housing, and the rotor may be arranged to rotate freely around the stator. The rotatable outer portion may have at least one inlet configured to receive a cooling medium and at least one outlet configured to exhaust the cooling medium. The stator and rotor may each be separately molded within a respective epoxy layer. A channel may be disposed between the molded rotor and the molded stator to direct the cooling medium axially of the housing and in fluid communication with the at least one inlet and the at least one outlet to form an inherent cooling system of the electric motor. A propeller may be disposed on the rotor.

[0126] The motor may be arranged in a jet configuration with a second housing, the second housing may be arranged to at least partially enclose the motor and the propeller.

[0127] The motor may be arranged with the rotor within the hollow stator and the propeller disposed within the hollow rotor.

[0128] The motor may be arranged with the rotor within the hollow stator and the propeller disposed within the hollow rotor.

[0129] The motor may be arranged in a jet configuration with a second housing, the second housing may be arranged to at least partially enclose the motor and the propeller.

[0130] The electric motor may be suitable for powering a vessel underwater, which may be, for example, a boat, a jet ski, a ship, a submarine or the like. The motor powers a propeller and may operate submerged.

[0131] The electric motors may be arranged as outboard motors, inboard motors, or as pods.

[0132] The electric motor may further comprise mounting means suitable for mounting the motor to a boat, for example the motor may be mounted to the transom, stern, hull, rudder and / or hydrofoils.

[0133] The electric motor may be configured to be mounted, for example, to the transom, stern, hull, rudder, and / or hydrofoil.

[0134] The electric motor according to the present disclosure may be used in marine or offshore applications as well as other applications, such as drones, electric vehicles, and all kinds of electric toys. However, in non-marine applications, it is necessary to replace the water with a cooling medium, which may be introduced into the closed or sealed channel 308 by at least one inlet and discharged by at least one outlet (not shown). Both the at least one outlet and the at least one inlet may be connected to an external vessel or similar device containing the cooling medium. In some applications, the propellers need to be replaced by fans or similar devices to operate properly.

[0135] Those skilled in the art will understand that the present invention is not limited to the preferred embodiments described above. Those skilled in the art will further understand that modifications and variations are possible within the scope of the appended claims. Furthermore, variations to the disclosed embodiments can be understood and effected by those skilled in the art practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

Claims

1. a housing (100) having a stationary inner part (110) and a rotatable outer part (120); a stator (101) supported on said stationary inner part (110) of said housing (100); a rotor (102) mounted on said rotatable outer part (120) of said housing (100) and arranged to rotate freely around said stator (101); An electric motor comprising: said rotatable outer part (100) has at least one inlet (104A, 104B) configured to receive a cooling medium and at least one outlet (105A, 105B) configured to discharge said cooling medium; - said stator (101) and said rotor (102) are each separately molded in a respective epoxy layer (107A, 107B); a channel (106) is disposed between the formed rotor and the formed stator, directing the cooling medium in the axial direction of the housing (100) and in fluid communication with the at least one inlet (104A, 104B) and the at least one outlet (105A, 105B), forming an inherent cooling system of the electric motor; the at least one outlet (105A, 105B) is disposed in the rotatable outer portion (120) of the housing (100) and configured to discharge the cooling medium from the channel (106) by centrifugal force during rotation of the rotor (102), the at least one outlet (105A, 105B) being an opening through both the rotatable outer portion (120) of the housing (100) and the rotor (102).

1. An electric motor comprising:

2. The electric motor of claim 1 , wherein the at least one outlet (105A, 105B) discharges the cooling medium by centrifugal force generated while the rotor (102) rotates.

3. 3. The electric motor of claim 1 or 2, wherein the intrinsic cooling system further comprises an additional channel (108) extending axially through a center of the stationary inner portion of the housing and arranged to allow a cooling medium to flow therethrough.

4. An electric motor as claimed in any one of claims 1 to 3, wherein some of the outlets (105A, 105B) are aligned on the outer periphery of the rotatable outer portion of the housing.

5. An electric motor as claimed in any preceding claim, wherein the rotatable outer portion of the housing is at least partially cylindrical.

6. An electric motor according to any one of claims 1 to 5, wherein the at least one outlet (105A, 105B) is any one of a circular opening, a slit, a star, a square, a borehole and a conical opening.

7. An electric motor as claimed in any one of the preceding claims, wherein the electric motor is arranged to operate submerged and the cooling medium is water.

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