WO2016162750A1

WO2016162750A1 - Motorized wheel with cooling

Info

Publication number: WO2016162750A1
Application number: PCT/IB2016/000536
Authority: WO
Inventors: Duncan Richard QUICK; Peter Hill
Original assignee: Globe International Nominees Pty Ltd
Priority date: 2015-04-09
Filing date: 2016-04-08
Publication date: 2016-10-13

Abstract

A motorized wheel is disclosed. The motorized wheel includes an electric motor having a stator and a rotor, the rotor surrounding the stator. The motorized wheel also includes a tire that can be mounted to the stator such that the stator supports the tire as a rim and the electric motor drives the tire directly. A cooling system for the motorized wheel is also disclosed. The cooling system can include a hollow axle having an interior channel for directing a heat transfer medium. The motorized wheel is mounted on the axle. The cooling system may be a forced air or liquid cooling system. A skateboard including the motorized wheel is disclosed. The skateboard may also include the cooling system.

Description

MOTORIZED WHEEL WITH COOLING

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 62/145137, filed April 9, 2015, U.S. Provisional Application No. 62/242919, filed October 16, 2015, and U.S. Provisional Application No. 61/253635, filed November 10, 2015, each of which is incorporated by reference in its entirety and for all purposes.

BACKGROUND

Field

[0002] This disclosure relates to electric vehicles. In particular, it relates to a motorized wheel for a vehicle.

Description

[0003] Lightweight personal vehicles, such as skateboards, scooters, roller skates, and others are common for recreational use and transportation. These vehicles are commonly non-motorized, requiring the user to provide the power for motion. Several motorized personal vehicles have been developed. For example, commercially available motorized skateboards typically use a motor to drive a toothed belt that drives one or two wheels. While these types of motorized vehicles do not require the user to provide the power for motion, they may be significantly heavier and more complicated than traditional non-motorized versions.

SUMMARY

[0004] This disclosure describes a motorized wheel for use in personal vehicles, such as skateboards, scooters, roller skates, and the like. The motorized wheel may drive (or assist in driving) the motion of the vehicle. The motorized wheel may include an electric motor. A tire may be mounted on the rotor of the electric motor. In some embodiments, the electric motor is positioned substantially within the tire. The electric motor may drive the tire directly, without requiring an intermediary mechanical transmission, such as a belt or gearbox. Thus, the motorized wheel may be lightweight and relatively simple for an end user to use.

[0005] In some embodiments, the motorized wheel may include or be used with a cooling system. The cooling system can be a fluid cooling system using a gas or a liquid, such as air or water, as a heat transfer medium. The cooling system may deliver the heat transfer medium through a hollow axle to the motorized wheel. The hollow axle may be part of a wheel assembly that connects the motorized wheel to a deck of a skateboard. The wheel assembly may be configured to deliver the heat transfer medium between the deck and the hollow axle. The cooling system may advantageously increase the power to weight ratio of the motorized wheel.

[0006] According to the disclosure, a motorized wheel assembly that is configured to be cooled while propelling a vehicle includes one or more of the following: an electric motor; and/or a tire on a rotor of the electric motor, the tire configured to support a vehicle relative to a support surface. The electric motor includes one or more of the following; a stator; a rotor about the stator, the rotor configured to rotate relative to the stator; an outer bell end connected to a first end of the rotor, the outer bell end comprising one or more first openings configured to allow a fluid to pass through the one or more first openings; and/or an inner bell end connected to a second end of the rotor, the inner bell end comprising one or more second openings configured to allow the fluid to pass through the one or more second openings, wherein the stator is between the outer and inner bell ends. The electric motor is configured to cause the rotor to rotate relative to the stator to cause the tire to rotate relative to the support surface to propel the vehicle against the support surface. The fluid flows between the one or more first openings and the one or more second openings to cool the electric motor during operation of the electric motor.

[0007] According to the disclosure, the assembly further includes one or more of the following: the fluid flows within the rotor between the one or more first and second openings, the fluid flowing proximate to the stator to cool at least the stator; an axle, the stator fixed to the axle to cause the rotor to rotate relative to the axle to propel the vehicle relative to the support surface during operation of the electric motor, wherein the axle comprises a channel extending along a central axis, the channel configured to direct the fluid toward or away from the one or more first and second openings to cool the electric motor; a cap connected to the electric motor, the cap configured to direct fluid from or to the channel of the axle and toward or away from the one or more first and second openings, respectively; the axle comprises a first orifice in fluid communication with the channel of the axle, the first orifice configured to direct fluid from or to the channel of the axle and toward or away from the one or more first and second openings, respectively, wherein the cap impinges the fluid to flow away from or toward the central axis and toward or away from the one or more first and second openings, respectively; the axle further comprises a second orifice in fluid communication of the channel of the axle, the second orifice configured to direct fluid into or out of the channel; the fluid flows into the second orifice, flows through the channel, flows out of the first orifice, impinges against the cap toward the one or more first openings, flows through the one or more first openings into the electric motor, flows through the electric motor toward the one or more second openings, and flows out through the one or more second openings; electrical wiring to power or control the electric motor extends through at least a part of the channel to the electric motor; the cap and the tire are connected to the outer bell end via one or more fasteners; the cap comprises one or more slots configured to mate with the one or more fasteners, wherein the cap is configured to rotate relative to the fasteners to position the one or more fasteners within the slots to facilitate retaining the cap relative to the electric motor or the tire; a fluid moving device configured to direct the fluid toward or away from the one or more first and second openings; the fluid moving device is positioned in a central opening in the tire, the central opening in fluid communication with the one or more first and second openings; the fluid moving device comprises a fan configured to direct the fluid toward the one or more first openings, and wherein the fluid comprises air; the cap comprises one or more apertures in fluid communication with the one or more first and second openings, the one or more apertures configured to direct the fluid toward the one or more first and second openings to cool the electric motor during operation of the electric motor; a fan positioned in a central opening of the tire, the fan configured to direct the fluid from the one or more apertures toward the one or more first openings, and wherein the fluid comprises air; the vehicle is a skateboard and the motorized wheel assembly is configured for use with the skateboard; a fluid moving device is positioned in the vehicle, the fluid moving device in fluid communication with the one or more first and second openings via one or more fluid channels, wherein the fluid moving device is configured to direct the fluid toward the one or more first and second openings via the one or more fluid channels; and/or the vehicle is a skateboard and the motorized wheel assembly is configured to be connected to a hanger of the skateboard, wherein the hanger is connected to a truck that is connected to a deck of the skateboard, wherein the fluid moving device is mounted in the deck, and wherein the one or more fluid channels extend at least in part through the hanger and the truck to fluidly connect the fluid moving device and the one or more first and second openings.

[0008] According to this disclosure, a motorized wheel assembly for propelling a vehicle includes one or more of the following: an axle comprising a channel extending along a central axis, the channel configured to direct a fluid along the central axis; and/or an electric motor. According to this disclosure, the electric motor includes one or more of the following; a stator connected to the axle, the stator positioned over at least a part of the channel; and/or a rotor extending along the central axis, the rotor positioned about the stator, the rotor configured to rotate relative to the stator. The electric motor is configured to cause the rotor to rotate relative to the stator to propel a vehicle. The fluid flows through at least a part of the channel over which the stator is positioned to cool the electric motor during operation of the electric motor.

[0009] According to this disclosure, the assembly further includes one or more of the following: a tube extending through at least a portion of the channel along the central axis, the tube configured to direct the fluid toward the electric motor, wherein after the fluid exits from the tube, the fluid flows proximate to the at least a pari of the channel over which the stator is positioned when the electric motor is being cooled; after flowing proximate to the at least a part of the channel over which the stator is positioned, the fluid is directed through the channel over the tube to exit the channel of the axle; an end of the tube is positioned within the channel for the fluid to exit from the end of the tube into the channel; an outer bell end connected to a first end of the rotor, an inner bell end connected to a second end of the rotor, wherein the stator is between the outer and inner bell ends, wherein an end of the tube is positioned between the outer beli end and the inner beli end outside of the channel of the axle, wherein the outer and inner bell ends and stator are configured to contain the fluid exiting from the end of the tube for the fluid to cool at least the stator of the electric motor; the fluid exits the electric motor into the channel of the axle through an exit hole in the axle, the exit hole fluidly connecting the channel and the end of the tube; the fluid circulates in a closed loop cooling system; electrical wiring to power or control the electric motor extends through at least some of the channel to the electric motor; a fluid moving device is positioned in the vehicle, the fluid moving device in fluid communication with the channel of the axle, wherein fluid moving device is configured to direct the fluid toward or away from the electric motor; the vehicle is a skateboard and the motorized wheel assembly- is configured to be connected to a hanger of the skateboard, wherein the hanger is connected to a truck that is connected to a deck of the skateboard, wherein the fluid moving device is mounted in the deck, and wherein one or more fluid channels extend at least in part through the hanger and the truck to connect the fluid moving device and the at least a part of the channel over which the stator is positioned; the vehicle is a skateboard and the motorized wheel assembly is configured for use with the skateboard; the fluid comprises a liquid phase heat transfer medium; and/or the fluid comprises a gas.

[0010] According to this disclosure an electric motor includes one or more of the following: a stator; a rotor about the stator, the rotor configured to spin relative to the stator; a first bell end connected to a first end of the rotor, the first bell end comprising one or more first openings configured to allow a fluid to pass through the one or more first openings; and/or a second bell end connected to a second end of the rotor, the second bell end comprising one or more second openings configured to allow the fluid to pass through the one or more second openings, wherein the stator is between the first and second bell ends. The rotor is configured to spin relative to the stator while the electric motor operates. The fluid flows between the one or more first openings and the one or more second openings to cool the electric motor during operation of the electric motor.

[0011] According to this disclosure the electric motor further comprises one or more of the following: the fluid flows within the rotor between the one or more first and second openings, the fluid flowing proximate to the stator between the first and second bell ends to cool at least the stator; the electric motor is configured to be used with a vehicle for the electric motor to propel the vehicle when the electric motor is operating; the vehicle is a skateboard, wherein the electric motor is connected to an axle of the skateboard, and wherein the axle comprises a channel configured to direct the fluid toward or away from the one or more first and second openings; and/or the electric motor is cooled via forced convection with a fluid moving device moving the fluid through the one or more first and second openings.

[0012] According to this disclosure, a method of manufacturing an electric motor includes one or more of the following: providing a stator; positioning a rotor about the stator, the rotor configured to rotate relative to the stator; connecting a first bell end to a first end of the rotor, the first bell end comprising one or more first openings configured to allow a fluid to pass through the one or more first openings; and/or connecting a second bell end to a second end of the rotor to position the stator between the first and second bell ends, the second bell end comprising one or more second openings configured to allow the fluid to pass through the one or more second opening. The one or more first and second openings are configured to allow the fluid to flow between the one or more first and second openings to cool at least the stator.

[0013] According to this disclosure a method of manufacturing a motorized wheel includes manufacturing an electric motor as described above, and/or positioning a tire on the rotor, the tire configured to support a vehicle relative to a support surface. A fluid is capable of flowing between the one or more first openings and the one or more second openings to cool the electric motor during operation of the electric motor to propel the vehicle.

[0014] According to this disclosure, the method further includes one or more of the following: connecting the stator to an axle, wherein the axle comprises a channel extending along a central axis, the channel configured to direct the fluid toward or away from the one or more first and second openings of the electric motor to cool the electric motor; connecting a cap to the electric motor, the cap configured to direct fluid from or to the channel of the axle and toward or away from the one or more first and second openings, respectively; rotating the cap to nest fasteners with slots of the cap to promote retaining the cap relative to the electric motor via the fasteners; fluidly connecting a fluid moving device to the one or more first and second openings, the fluid moving device configured to direct the fluid toward or away from the one or more first and second openings; positioning the fluid moving device in the vehicle and fluidly connecting the fluid moving device with the one or more first and second openings via one or more fluid channels in the vehicle; connecting the electric motor to a hanger of a skateboard, connecting the hanger to a truck of the skateboard, connecting the truck to a deck of the skateboard, and mounting the fluid moving device in the deck, wherein the one or more fluid channels extend at least in part through the hanger and the truck to fluidly connect the fluid moving device and the one or more first and second openings; and/or positioning the fluid moving device in a central opening in the tire, the central opening in fluid communication with the one or more first and second openings.

[0015] According to this disclosure, a method of manufacturing a motorized wheel includes one or more of the following: connecting an electric motor to an axle, the axle comprising a channel extending along a central axis, the electric motor connected to the axle over at least a portion of the channel, and the channel configured to direct a fluid along the central axis. The channel is configured to direct flow of the fluid into the at least portion of the channel over which the electric motor is connected to the axle to cool the electric motor during operation of the electric motor.

[0016] According to this disclosure, the method further includes one or more of the following: extending a tube through at least part of the channel to direct flow of the fluid to the at least portion of the channel over which the electric motor is connected to the axle; and/or extending the tube into an interior of the electric motor.

[0017] According to this disclosure, a motorized wheel for a vehicle includes one or more of the following: a coreless tire and/or an electric motor. A rotor of the electric motor functions as a rim of the tire. The tire is removably mounted on and directly fastened to the electric motor. A stator of the electric motor may be connected to the vehicle. The motorized wheel is configured such that the electric motor directly drives the tire. The electric motor y directly drives the tire without a tire retaining rim.

[0018] According to this disclosure, the motorized wheel may include a cooling system. The cooling system may be a sealed liquid coolant system in which coolant circulates from the electric motor to a heat sink mounted remotely from the motorized wheel. The coolant may be circulated by a pump. The cooling system may be a forced air cooling system. In the forced air cooling system, air may be ducted to the motorized wheel from a fan mounted remotely from the wheel. In the forced air cooling system, air may be moved through the electric motor by a fan located inside the motorized wheel.

[0019] According to this disclosure, a skateboard includes one or more of the following: a deck, trucks; hangers; and/or one or more of the motorized wheels described above. The skateboard may include one or more non-motorized wheels. The wheels (motorized wheels and/or non-motorized wheels) may be mounted from the hangers. The hangers may be mounted from trucks. The trucks may be mounted underneath the deck. According to this disclosure the skateboard may further include a cooling system. According to this disclosure the cooling system for the one or more motorized wheels, the cooling system includes one or more of the following: a fan; air may flow in to an electric motor of the one or more motorized wheels via an air duct formed by a hollow axle; and/or air may flow to an outer side of a stator of the electric motor; air may then be directed to turn approximately 180 degrees and pass through the electric motor, exhausting on an inner side of the electric motor. The skateboard may further include one or more of the following: a flexible duct joint between the hollow axle and the deck; the flexible duct joint may be part of a wheel assembly; the fan may be mounted on the deck; the flexible duct may be integrated with either a kingpin or a pivot post joint between the hanger and truck, by means of a hollow post and a socket; electrical cables connecting the electric motors of the one or more motorized wheels to power systems in the deck may run inside the duct; a hubcap; the hubcap may retain a tire of the motorized wheel onto an electric motor of the motorized wheel; the hubcap may be removably retained on the electric motor by a hubcap fastener; the hubcap fastener may include bolts, studs, locking pins, or nuts; and/or the hubcap may be removably retained on the electric motor by a plurality of keyhole slots engaging mating retaining members projecting from the electric motor.

[0020] The foregoing is a summary and contains simplifications, generalization, and omissions of detail. Those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, features, and advantages of the devices and/or processes and/or other subject matter described herein will become apparent in the teachings set forth herein. The summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of any subject matter described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The foregoing and other features of the present disclosure will become more fully apparent from the following description, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.

[0022] FIG. 1 shows a perspective view of a motorized wheel, including a tire retained on an electric motor by a hubcap.

[0023] FIG. 2 shows another perspective view of the motorized wheel of FIG. 1 , illustrated with the hubcap and tire removed from the electric motor.

[0024] FIG. 3 is a perspective view of the tire of FIGS. 1 and 2, viewed from the inner side.

[0025] FIG. 4 shows an exploded perspective view of the motorized wheel of

FIG.

FIG. 5A is a perspective view of a skateboard including the motorized wheels of FIG.

FIG. 5B is a perspective view of a wheel assembly that may be used with the skateboard of FIG. 5 A.

[0028] FIG. 5C is a sectional view of the wheel assembly of FIG. 5B.

[0029] FIG. 5D is another sectional view of the wheel assembly of FIG. 5B, illustrated with the motorized wheels removed.

[0030] FIG. 6 shows a front view of the motorized wheel of FIG. 1 connected to a hollow axle.

[0031] FIG. 7 is a cross-sectional view of the motorized wheel and axle of FIG. 6.

[0032] FIG. 8 shows a partially exploded view of a motorized wheel that includes a fan.

[0033] FIG. 9 shows a partially exploded view of the motorized wheel of FIG. 8, illustrating the fan positioned within the tire.

[0034] FIG. 10 is a cross-sectional view of a motorized wheel mounted on an axle that includes an axle-mounted fluid cooling system. [0035] FIG. 11 is a cross-sectional view of a motorized wheel mounted on an axle that includes an axle and motor fluid cooling system.

[0036] FIG. 12 shows a perspective view of a motorized wheel that includes a hubcap with keyhole slots that engage the electric motor.

[0037] FIG. 13 is an exploded view of the motorized wheel of FIG. 12.

DETAILED DESCRIPTION

[0038] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description and the drawings are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, may be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and made a part of this disclosure.

[0039] This disclosure relates to a motorized wheel and applications therefore. As will be described more fully below, the motorized wheel may include a tire mounted on an electric motor. The electric motor may be a brushless outrunner motor, and the tire can be mounted on a rotor thereof, although the use of other types of electric motors is possible. The rotor of the electric motor may serve as the hub for the tire. This may substantially mitigate or eliminate the need for a mechanical power transmission between the motor and the wheel (such that the motorized wheel may be considered a direct drive system), and further may substantially mitigate or eliminate the need for a wheel hub.

[0040] The motorized wheel can optionally include, or be configured for use with, a cooling system. The cooling system may use forced fluid cooling, for example, using water, air, or other heat transfer media to cool the electric motor. Inclusion or use with a cooling system may allow for a reduction in the size and/or weight of the motorized wheel, while still allowing the electric motor to produce a desired or predetermined torque. This may also mitigate the use of a transmission, such that the electric motor drives the tire substantially directly (e.g., the electric motor or a part or portion of motor directly connects, mates, and/or engages the tire).

[0041] The motorized wheel may be used in a wide variety of applications including electric skateboards, scooters, street luges, and roller skates, among many others.

[0042] The motorized wheel described herein may provide several notable advantages, some of which are described herein. For example, the motorized wheel may be able to freely coast, even when battery power is unavailable. The motorized wheel may be useable in space-limited applications. For example, in roller skates and luges, there may be insufficient space available for a belt driven wheel, while the motorized wheel of this disclosure may fit. Maintenance, cost, and weight of vehicles including motorized wheels as described herein may be reduced in comparison to vehicles with belt driven motors and wheels. The motorized wheel may be advantageously be used in last leg vehicles, such as skateboards or others, that are hand carried on trains or other public transportation because they may be lightweight. The motorized wheel may use a coreless tire. Coreless tires may be less expensive to produce than tires with cores. As noted above, the motorized tire may be used with a cooling system that may allow for both a higher sustained power output and a higher peak torque for short term acceleration. The cooling systems described herein may allow for a higher power to weight ratio for the motorized wheel, when compared to devices that do not use a cooling system.

[0043] Some existing electric skateboards use a mechanical power transmission element between the electric motor and the wheel. This may allow for a step up speed ratio between the motor and the wheels, such that the motor spins faster than the wheels. This may be done to allow the motor to run at a higher speed, which may allow a smaller self-cooled motor to be used. However, this also requires an increased number of parts, increased overall size of the drive system, and an increased complexity. For example, in some electric skateboards a planetary gear drive may be used, having a single motor driving both wheels via single stage planetary gearboxes with a one way bearing (clutch) in each wheel. These planetary gearboxes are similar to those used in electric drills. However, when used in an electric skateboard the weight, power losses, and acoustic noise is undesirable. Accordingly, most commercially available electric skateboards use a toothed belt to couple the motor with the wheels. However, this also is disadvantageous for the reasons provided previously. [0044] Some electric scooters and bicycles may use wheel motors, sometimes without gearing. However, these hub motors are much larger and heavier than is suitable for an electric skateboard.

[0045] In some electric vehicles, a split rim wheel is used in which the rim is mounted on an electric motor. However, in contrast with the motorized wheel described herein, in these vehicles a rotor of the electric motor does not function as the rim for the tire. This may because in these vehicles the motor is too large.

[0046] In some electric vehicles, a wheel motor can includes cooling fins on a rotor of an electric motor to cool the electric motor and to possibly prevent magnets of the rotor from demagnetizing. For example, N52 magnets have such a temperature of approximately 80 degrees C (176 degrees F) as the maximum recommended operating temperature limit. However, rotation of the motor can be ineffective in cooling the motor windings at ail practical road speeds. Further, such fins may be the most lateral projection of the wheels, the fins may be struck when the board impacts a wall or gutter. In such a system, a tire is not easily replaceable. These and other problems with existing technologies may be overcome by the motorized wheel and cooling systems described herein.

[0047] FIG. 1 shows a perspective view of a motorized wheel 100. In the figure, the motorized wheel 100 (motorized wheel assembly) is illustrated in an assembled state, with a tire 200 mounted to an electric motor 300 (the electric motor 300 is not visible in FIG. 1, but is shown in, for example, FIG. 2). As illustrated in FIG. 1, a hubcap 250 (cap, end, disk, plate, etc.) is used to retain the tire 200 onto the electric motor 300, although other methods for retaining the tire 200 to the electric motor 300 may be used. For example, alternative fastening mechanisms may include bolts, clips, circlips, threading the inside of the tire 200 and the outside of the electric motor 300, and/or using studs and nuts. As illustrated, the hubcap 250 is secured to the electric motor 300 by means of an array of bolts 253 (or screws fasteners, clasps, locks, etc.). In this example six bolts 253 are shown. However, any suitable number of bolts can be used, including one, two, three, four, five, seven, eight, etc. In some embodiments, the hubcap 250 may secured by other means.

[0048] The tire 200 may be configured in various sizes and/or shapes or from different materials and/or constructions, depending upon the desired application, performance, and/or durability. For example, the tire 200 may be configured in size and shape for use on skateboards or other small recreational vehicles, such as scooters, roller skates, or street luge boards, among others. The tire 200 may comprise polyurethane.

[0049] In some embodiments, the tire 200 may be coreiess. A coreless tire is one which has no such core. A coreless tire may include a lumen or opening 207 along a central axis 2 6 of the tire 200 as discussed herein. By way of explanation, in many instances conventional polyurethane tires for skateboards have a hard, substantially rigid core usually made from plastic or aluminum, which supports the typically more elastic tire by functioning as a rim. The tire and the core together form the wheel. In some embodiments of a cored tire, the tire is mechanically keyed and/or chemically bonded to the core, such that the tire and core form an unserviceable wheel. In contrast, in some embodiments of the motorized wheel 100, the tire 200 is coreless. Rather than being bonded to a core, a coreless tire is removably attachable to a rim.

[0050] As will be described in greater detail below, in the motorized wheel 100, the electric motor 300 may serve as the rim. That is, the tire 200 may be removably mounted directly on the electric motor 300. The tire 200 may be attached using any suitable fastening mechanism, including bolts, clips, circlips, male/female fasteners, snapping fasteners, threading the inside of the tire and the outside of the rim, and/or using studs and nuts. The fastening mechanisms may be removable and replaceable to allow the replacement of the tire 200 when it is worn. This may be advantageous as the tire 200 may be a consumable part subject to wear. Having no core, the tire 200 may be cheaper (in other words, more cost effective) to produce. This may provide advantages for the user and/or manufacturer, including reduced maintenance costs, as well as advantages for the environment, since no cores are wasted once the tire is worn and discarded.

[0051] FIG. 2 shows another perspective view of the motorized wheel 100 of FIG. 1 , illustrating the motorized wheel 100 in an unassembled state, with the hubcap 250 and tire 200 removed from the electric motor 300. As illustrated, the hubcap 250 is a substantially flat, thin, and circular plate, although other configurations are possible. The hubcap 250 includes bolt holes 251 extending therethrough. The bolt holes 251 are configured to receive the bolts 253. The bolt holes 251 may be internally threaded to engage outer threads on the bolts 253. The bolt holes 251 may be counter-bored into the outer surface of the hubcap 250 to receive a portion of a head of the bolts 253. When the bolts 253 are mserted into the bolt holes 251, the heads of the bolts 253 may be flush with the outer surface of the hubcap 250. Sleeves 255 may extend from the inner surface of the hubcap 250 at the bolt holes 251. The sleeves 255 may be internally threaded.

[0052] As shown, the tire 200 includes an outer surface 201. The outer surface is configured to contact the ground or supporting surface (support surface) during use of the motorized wheel 100. As illustrated, the tire 200 includes an interior flange 215 that extends from an inner surface 205. The interior flange 215 may be oriented so as to be substantially perpendicular to the outer surface 201 and/or the inner surface 205 of the tire 200. An opening 207 may extend through the interior flange 215 (lumen forming a coreless tire). The opening 207 may be centered on the central axis 216 of the tire 200. As shown, bolt holes 211 extend longitudinally through the interior flange 215. The bolt holes 211 are positioned on the interior flange 215 so as to align with the bolt holes 251 on the hubcap 250. Where the bolts 253 are of small diameter and/or have no shoulder, wheel bolt sleeves 257 may be used to reduce the stress on the bolt holes 211. The wheel bolt sleeves 257 may be configured to fit within the bolt holes 211. The wheel bolt sleeves 257 may be integrally formed with the bolts 253. Alternatively, the wheel bolt sleeves 257 may be omitted. The bolt holes 21 1 may be internally threaded.

[0053] As illustrated, an outside edge 203 of the tire 200 may include a lip 204. The lip 204 may be configured in size and shape to correspond to an outer edge of the hubcap 250, such that the hubcap 250 can be received within the lip 204 of the tire 200. In the assembled state (as shown in FIG. 1), an inner surface of the hubcap 250 may contact an outer surface of the interior flange 215. In the assembled state the hubcap 250 may be substantially flush with the outside edge 203 of the tire 200.

[0054] FIG. 3 is a perspective view of the tire 200, viewed from the inside. As shown, the interior flange 215 may be positioned in the tire 200 closer to the outside edge 203 (proximate to the outside edge 203 relative to opposing (interior) edge of the tire 200) such that a receiving space 206 (lumen, cavity, etc.) is created within the interior of the tire 200. In the assembled state, as shown in FIG. 1, the electric motor 300 is inserted into the receiving space 206. An outer surface of the electric motor 300 may contact the mner surface 205 of the tire 200. Thus, the electric motor 300 may serve as a rim for the tire 200. [0055] Returning to FIG, 2, the electric motor 300 is illustrated removed from the tire 200. The electric motor 300 may be an outrunner motor. Outrunner motors are those that have an internal stator that is surrounded by an external rotor. The external rotor spins relative to the internal stator, which generally remains in a rotationaliy fixed orientation. The electric motor 300 may be brushless. The internal features of the electric motor 300 will be described in greater detail below, in reference to FIG. 4. Other types of electric motors, including inrunner motors and others, may be used.

[0056] As shown in FIG. 2, the outer casing of the electric motor 300 is formed by an outer bell end 310, an outer surface 351 of a rotor 350, and an inner bell end 320. The outer casing surrounds a stator 340 (shown in FIG. 4). The stator 340 is mounted on a boss 355. The boss 355 is configured to mount on an axle 600 (see for example, FIGS. 6 and 7). The boss 355 is further connected to the outer bell end 310 via a bearing 315 (see for example, FIG. 4). Similarly, the boss 355 is further connected to the inner bell end 320 via a bearing 325 (see for example, FIG. 4). The bearings 315, 325 allow the outer casing of the electric motor 300 (in other words, the outer bell end 310, the rotor 350, and the inner bell end 320) to rotate relative to the boss 355 and the stator 340.

[0057] The outer bell end 310 of the electric motor 300 includes bolt holes 311. The bolt holes 31 1 are configured in size and shape and positioned to align with the bolt holes 21 1 of the tire 200, and the bolt holes 251 of the hubcap 250. The bolt holes 31 1 can be internally threaded to engage with the bolts 253. Thus, in the assembled state, the bolts 253 secure the hubcap 250 and tire 200 to the outer bell end 310 of the electric motor 300, such that the electric motor 300 is at least partially positioned within the receiving space 206 of the tire 200. Further, when the boss 355 is attached to the axle of a vehicle, such as a skateboard, the electric motor 300 can drive the tire 200. For example, the boss 355 and stator 340 may be substantially fixedly attached to the axle. The tire 200 may be attached to the outer bell end 310 of the electric motor 300 via the bolts 253 and the hubcap 250. When the electric motor 300 is powered, the rotor 350 spins relative to the stator 340. This rotation may be imparted to the tire 200 by means of the outer bell end 310, hubcap 250, and bolts 253.

[0058] FIG. 4 shows an exploded view of the motorized wheel 100 of FIG. 1. The hubcap 250 and tire 200 include the features previously described. Additional features of the electric motor 300, visible in the exploded view will now be described in greater detail. In addition to the bolt holes 311, the outer bell end 310 may also include cooling holes 313 (openings, cutouts, slots, apertures, etc.). The cooling holes 311 allow cooling fluid (for example, air or water) to flow into and out of the interior of the electric motor 300. The cooling holes 313 may have a larger diameter than the bolt holes 311. The cooling holes 313 may be positioned in between each of the bolt holes 31 1. There may be greater, equal, or fewer numbers of cooling holes 313 than bolt holes 311. The outer bell end 310 also includes an opening 314 for receiving the bearing 315 to facilitate rotation of the relative parts as discussed herein. The opening 314 may be aligned with the central axis of the electric motor 300. The outer bell end 310 also includes an inner flange 317 that mates with the rotor 350. The outer bell end 310 and the rotor 350 may be fixedly attached so that they rotate together.

[0059] On the opposite end of the electric motor 300, the inner bell end 320 includes features similar to the outer bell end 310, including cooling holes 323 and an inner flange 327. In some embodiments, the inner bell end 320 does not include bolt holes. The number of cooling holes 323 of the inner bell end 320 is greater than the number of cooling holes 313 of the outer bell end 310. In some embodiments, the electric motor 300 may have cooling holes 313 without cooling holes 323. In some embodiments, the electric motor 300 may have cooling holes 323 without cooling holes 313. The bearing 325 is received within an opening 324 in a similar manner as described above to facilitate rotation of the relative parts as discussed herein. The inner bell end 320 and the rotor 350 may be fixedly attached so that they rotate together.

[0060] Each of the bearings 31 5, 325 may be ring bearings, including a central opening formed there through. The boss 355 is received within the central openings of the bearings 315, 325. The bearings 315, 325 allow the outer bell end 310, the rotor 350, and the inner bell end 320 to rotate together relative to the boss 355. The boss 355 may be configured as a substantially cylindrical tube. One or more of the ends of the boss 355 may be open. The boss 355 may be configured to receive or otherwise attach to an axle of a vehicle to which the motorized wheel 100 is to be attached. As illustrated, the boss 355 includes a dual D- bored outer shape that corresponds with a dual D-bored shape opening 345 in the stator 340. When the stator 340 is positioned on the boss 355, the corresponding D-bore shapes rotationally fix the boss 355 and the stator 340 together. The D-bore shape may be omitted and other shapes or methods may be used to attach the stator 340 to the boss 355. An inner spacer 356 and an outer spacer 357 may be included to limit axial movement of the stator 340 along the boss 355. In some embodiments, axial movement of the stator 340 is substantially restrained.

[0061] As illustrated, the stator 340 is shown as a lamination stack without copper windings (for ease of illustration), although the windings would be included in use. The rotor 350 includes one or more magnets 354 mounted on an inner surface 353 thereof. A wide variety of configurations for the stator 340 and the rotor 350 are possible, including various numbers of poles and magnets. The rotor 350 may comprise a mild steel cylinder fitted with neodymium boron permanent magnets on its inner surface. The stator 340 can be formed from laminated sheet steel, wound with copper wire. Other configurations and materials for the rotor 350 and/or the stator 340 are possible. A control board for the electric motor 300 may be included and may be housed within the housing of the electric motor 300 or may be remotely located, for example, on or within the deck of a skateboard.

[0062] The motorized wheel 100 may be considered direct drive systems because power is transferred substantially directly from the electric motor 300 to the tire 200. Other mechanical structures or linkages, including gears and/or belts are not necessary. Utilizing a motorized wheel 100 as discussed herein can substantially mitigate or negate the need for a transmission (for example, a transmission including a gear box). This may provide several advantages. For example, without a gearbox with chain or belt means, maintenance of the vehicle can be substantially minimized or mitigated because, for example, there are minimal wearing parts other than the two inner and outer bearings 315, 325 per motorized wheel 100 (and the tire 200). Accordingly, where the motorized wheel 100 is included on an electric skateboard, the maintenance of the electric skateboard may be substantially the same as the maintenance on an unpowered board. Further, the bearings 315, 325 on a motorized wheel 100 may be larger than those of an unpowered board, so that the bearing maintenance is also significantly reduced.

[0063] Additionally, a motorized wheel 100 as discussed herein (without a transmission) can provide lower rolling drag or coasting losses in use. in vehicle designs that include a belt or gearbox transmission, by comparison, the transmission element typically loses energy, as well as all the bearings necessary to carry the various shafts. For example, in a typical belt driven skateboard, each motor will have one or two additional bearings to support the belt tension, so each driven wheel may have five, six, or more bearings in the power train. The losses in such a dual motor belt driven board may be about 17% higher than a board including the motorized wheel 100. These losses make a notable difference in the ease with which the board can be pushed when the motor is not powered, for example, when the battery is dead (depleted of power).

[0064] Further, because the motorized wheel 100 does not have any belts, there is no belt tensioning required, and unskilled users can operate the board without having to consider routine maintenance on the power transmission. No belt, chain, or gear transmission system means that there are no transmission losses while motoring, which can improve the battery range. Additionally, the weight of such a system is lower, using the rotor 350 as the rim for the tire 200. Accordingly, integrating the electric motor 300 with the wheel rim provides a relatively simpler design.

[0065] Because the motorized wheel 100 does not use a cored tire, the size of the electric motor 300 can be larger for a given overall tire diameter, providing for more torque. Conversely, the whole motorized wheel 100 can be made smaller for a given electric motor 300 diameter, if desired. Smaller diameter wheels can reduce the weight of the vehicle, and reduce the chance of the tire digging in and "high siding" a rider during a sideways slide. A wheel that is square or oversquare, such that its diameter is less than its width, is more likely to slip than dig in during a sideways slide. A smaller diameter wheel reduces the center of gravity of the rider, and also reduces the distance between the tail of the board and the riding surface, thereby allowing "Ollie's" and other skateboard maneuvers. A lower center of gravity also reduces instability and "speed wobbles" common in high center of gravity boards. Speed wobble can be described as a quick (for example, 4-10 Hz) oscillation of increasing amplitude until loss of control. Speed wobbles on an electric skateboard, which can be capable of speeds in excess of 30km/h (up to 19 mph), are undesirable, since above about 15km/h (about 9 mph), the rider cannot safely jump off in the event of a speed wobble incident.

[0066] Adding a cooling system to the motorized wheel 100 may increase the power to weight ratio and reduce the weight of the motor. Because the electric motor is a substantial portion of the weight of a vehicle, reducing the weight of the motorized wheel may have a large impact on reducing the overall weight of the vehicle. As will be discussed in greater detail below, the motorized wheel 100 may be used with various cooling systems and methods.

[0067] FIG. 5A is a perspective view of a skateboard 500 including one or more of the motorized wheels 100 of FIG. 1. The skateboard 500 includes a deck 510, under which a wheel assembly 530 is mounted that supports the motorized wheels 100. The skateboard 500 may include one or more motorized wheels 100 and one or more non-motorized (conventional) wheels. For example, one, two, three, or four motorized wheel 100 may be used on the skateboard 500, depending on the user's requirements or desire for speed and acceleration versus battery and motor weight and the remaining wheels may be non- motorized wheels. A user may modify or alter the vehicle after purchase to include less or more motorized wheels 100. Similarly, tire 200 replacement may be done with relative ease because, for example, there is no tension to be released prior to removing the bolts 253.

[0068] Various components 512 may be mounted on, below, or within the deck 510. The components 512 may include electronics, including batteries, electronic speed controllers, a mam controller, operator interfaces, radio interfaces, braking resistors, wiring harnesses, and/or other electronic components. Components 512 may also include various components for a cooling system, which can include pumps, fans, heatsinks, radiators, compressors, evaporators, condensers and/or other components. As illustrated, the components 512 include a fan 575. The fan 575 may be positioned on, under, or within the deck 510. The fan 575 is connected to a passageway (fluid channel) that routes air from the fan 575 to the motorized wheel 100. An example direction of flow is indicated with arrows 586. The direction of flow may also in the opposite direction of the arrows 586. The flow may be bidirectional. The flow may be a closed circuit. As described below, the passageway may extend through the wheel assembly 530. The components 512 may be connected to the one or more motorized wheels 100 through the deck 510 and/or the wheel assembly 530. As illustrated in FIG. 5 A, the components 512 are housed inside the deck 510, making their appearance non-obvious to a viewer. The components 512 may be accessible via a hatch through the top and/or bottom of the deck 510.

[0069] FIG. 5B shows a perspective view of the wheel assembly 530. The wheel assembly 530 includes a truck 540. The truck 540 is configured to mount to the underside of the deck 510, As illustrated, the truck 540 includes a flange 541. The flange 541 may be attached by bolts 542 (or other types of fasteners) to the deck 510. The truck 540 may also include an opening 543. The opening 543 may extend into the truck 540 from a side that, when mounted, contacts the deck 510. When mounted, the opening 543 may be aligned with a corresponding opening into the deck 510, thus allowing for a duct between the deck 510 and the truck 540. The truck 540 is also connected to a hanger 550. The truck 540 may be connected to the hanger 550 by a kingpin 556. The kingpin 556 may extend through the hanger 550 and into the truck 540. The kingpin 556 may be secured by a nut or other type of fastener. Although not visible in FIG. 5B, an axle 600 (see FIG. 5D) extends through the hanger 550. Motorized wheels 00 (or non-motorized wheels) are connected to the axle 600.

[0070] FIG. 5C shows a longitudinal sectional view of the wheel assembly 530. As illustrated, the kingpin 556 extends through the truck 540 and the hanger 550. A kingpin bushing 557 on each side of the hanger 550 allows for a resilient connection between the hanger 550 and the truck 540. This resilient connection allows a rider to steer the skateboard 500. Also visible in FIG. 5C, the axle 600 extends through the hanger 550. The axle 600 may be pressed or glued into hanger 550. The axle 600 may not rotate relative to the hanger 550. The axle 600 may be hollow, including an interior channel 605 therein. The interior channel 605 may be a fluid channel. The motorized wheel 100 (or non-motorized wheel) is mounted to the axle 600.

[0071] As illustrated in FIG. 5C, the hanger 550 and truck 540 may include a hollow pivot tube 545. The hollow pivot tube 545 may extend from the opening 543 in the truck 540 (which can be aligned with a corresponding opening into the deck 510), through the hanger 550, and into the interior channel 605 of the axle 600. The pivot tube 545 can be fitted in to a kingpin socket in the hanger 550 and allowed to flex by a pivot bush 553. The pivot bush 543 and kingpin bushings 557 may function to resiliency allow the movement of the hanger 550 relative to the truck 540, thus allowing it to function as a steerable axle. Components of a cooling system, such as cooling air or other media, electrical cables, hydraulic fluid, liquid coolant and others, or other components, such as electrical wiring for the motorized wheels 100 can be routed from the deck 510, through the hollow pivot tube 545 to the motorized wheels 100. The hollow pivot tube 545 may be connected with ducts 563 in the hanger 550. The ducts 563 may connect into the interior channel 605 of the axle 600, and/or into the motorized wheels 100. The ducts 563 and hollow pivot tube 545 may form part of a passageway through the wheel assembly 530. Flow (for example, of a heat transfer medium) may flow through the passageway as indicated by the arrows 586 in FIGS. 5C and 5D. The flow may also be in the opposite direction of the arrows 586. A heat transfer medium, such as air, water or others, may be piped through the passageway. In some embodiments, a flexible tube runs through the passageway, the flexible tube carrying the heat transfer medium. In some embodiments, the passageway may include a supply and a return flow path for the heat transfer medium.

[0072] FIG. 5D shows another sectional view of the wheel assembly 530, with the motorized wheels 100 removed. The passageway through the wheel assembly is illustrated, as well as an example flow path indicated by the arrows 586. As noted above, the flow may also go in the opposite direction, or form part of a closed loop system. The passageway extends through the hollow pivot tube 545, ducts 563, and into the interior channel 605 of the axle 600. Openings in the axle 600 can be connected with the ducts 563 in the hanger 550.

[0073] A user may alter the skateboard 500 after purchase, for example, by changing the number of motorized wheels 100. An idler wheel (in other words a non- motorized wheel) with no stator and no rotor magnets can be fitted, in place of a motorized wheel 100, in any of the four wheel positions. Tire replacement may be easier on the skateboard 500 including one or more motorized wheels 100 than on other powered skateboards that include a belt or chain drive, since there is no tension to be released prior to removing the wheel bolts. Further, the motorized wheel 100 may be configured to have the same external appearance as a non-motorized, conventional skateboard wheel. Thus, there may be no external giveaways (appearance) indicating whether the wheel is motorized. This may be desirable to some users.

[0074] Although, shown with the example of the skateboard 500, the motorized wheel 100 can be also useful for other weight and/or space sensitive wheeled sports applications, including road luge, roller skates, inline skates, grass skiing, and small wheeled scooters, among others types of vehicles. As used herein, a vehicle is a platform which ma ^¬ be used for the transport of goods and/or people. Small wheeled vehicles can include electric warehouse and factory cars, buggies, autonomous vehicles, skateboards, scooters, roller skates and street luge. Vehicles may be unpowered, for example, as in the case of most skateboards, roller skates and street luge, or may have one or more wheels driven by electric motors. Powered vehicles can include electric vehicles, where the power supply is usually a battery, and can also include vehicles such as slot cars, dodgem cars, tracked vehicles and trams, where a sliding contact, often a pantograph, is used to connect the vehicle to a fixed power supply such as overhead electrified mesh, wire or rails. The motorized wheel 100 may have beneficial application in last leg commuting vehicles because it is both powered and lightweight. A last leg commuting vehicle is one that can be hand carried, or slung from a backpack, then used to transport the user from a train, plane, tram, or other public transport system, to their final destination.

[0075] When using a direct drive system (such as the motorized wheel 100 described above), the electric motor 300 may run very hot at low speeds and/or high loads, as well as under several other regimes of operation, including acceleration from rest, riding uphill, or braking. Accordingly, a cooling system may be beneficial. As used herein, a cooling system is one in which additional components, beyond the natural circulation of air caused by the rotation of the wheel and/or motor, are used to cool the windings of the electric motor. Several example embodiments will be described below.

[0076] In some embodiments, a fluid cooling system may be employed. Fluid cooling can include any fluid heat transfer medium. The heat transfer medium can include water or a water glycol mixture. The heat transfer medium can also include corrosion inhibitors. In some embodiments, light oil may be used as the heat transfer medium. The fluid heat transfer medium can be a gas, such as air, for example. The fluid cooling system may be a forced fluid cooling system, for example, one in which the fluid heat transfer medium is actively pumped or otherwise moved through the system.

[0077] Forced air cooling can be achieved by inclusion of a hub fans (as described below in reference to FIGS. 8 and 9), or by air ducts and remotely mounted fans. Liquid cooling systems may include phase change cooling and pumped liquid where, for example, no phase change occurs (using liquid phase heat transfer medium). An example of phase change cooling is a refrigeration cycle, which can be either powered by a compressor, or passively circulated by heat pipes containing closed tubing filled with refrigerant. A third type of cooling system that can be used with the motorized wheels described herein includes the use of solid state Peltier junctions (for example, a thermoelectric assembly or device) to move heat from one side of a junction to another. This can be used to move heat from stator windings to a heat pipe or other type of thermal carrier such as a heat sink.

[0078] A forced cooling system can be implemented by using a hollow axle. The hollow axle can either be fully hollow, as in a hollow tube, or it can be partly hollowed, forming a C-shaped section. A flexible duct (such as a flexible plastic tube) may be fitted through the hollow axle, between the motorized wheel and the deck. The fluid heat transfer medium (for example, air or liquid) can be delivered to the motorized wheel through the flexible duct. In the case of liquid cooling, a liquid supply line and a liquid return line may be routed through the flexible duct. With suitable sealing, one hose can be used to achieve desired functionality as discussed herein, using the hollow axle itself as the return path, cooling the wiring. Liquid and air cooling via a hollow axle may advantageously use the heat loss through the axle itself as part of the system. Fins and other methods for increasing the surface area of the axle can be used to increase heat dissipation from the axle. Thermally bonding the axle to the hanger also can increase heat dissipation by including losses from the hanger area.

[0079] Wiring for the motorized wheel and/or the cooling system can be run through the hollow axle or flexible duct. Thus, the wiring may be mechanically protected from damage, and the wiring can be cooled by virtue of being inside of the flexible duct. This may allow a smaller gauge wire to be used, reducing weight and cost.

[0080] FIG. 6 shows a front view of the motorized wheel 100 (for example, as described above in reference to FIG. 1 ) connected to a hollow axle 600 as part of a cooling system 700 for a motorized wheel assembly. FIG. 7 is a cross-sectional view of the motorized wheel 100 and axle 600 of FIG. 6. The hollow axle 600 may be used, for example, in the skateboard 500 of FIGS. 5A-5D, or in many other types of electric vehicles as described throughout this application. In these figures, for ease of illustration, one motorized wheel 100 has been included. However, a second motorized wheel or a non-motorized wheel may be included on the opposite end of the axle 600.

[0081] As shown in FIG. 6, the axle 600 may include an opening 610 (orifice, aperture, cutout, slit, funnel, inlet, etc.). The opening 610 is an inlet point into the interior of the axle 600. In some embodiments, multiple openings 610 may be used. The opening 610 may align with the ducts 563 in the hanger 550 described above. The opening 610 may be in fluid communication with the passageway. As illustrated, a single opening 610 may be positioned at the midpoint of axle 600 and generally extends through a top surface thereof. However, other positionings for the opening 610 are possible. The illustrated configuration may beneficially allow for passage of elements between the axle 600 and the deck of a skateboard through the wheel assembly 530 described above. Such a configuration may conceal the cooling path and the wiring between the deck 510 and motorized wheels 100. Indeed, such a board may be mistaken for a non-powered board as there are no obvious features such as motors and wiring which would otherwise indicate that the board is motorized. Batteries, controllers, pumps, and other components may be mounted on or in the deck.

[0082] Turning now to the cross-sectional view of FIG. 7, an interior channel 605 (lumen, conduit, duct, passage, etc.) within the holiow axle 600 is visible. The interior channel 605 of the axle 600 includes open ends 607 at each end thereof. For example, as illustrated in FIG. 7, the axle 600 can have an opening (orifice, aperture, cutout, slit, funnel, outlet, etc.) on an end 607 of the axle 607. An opening of an end 607 can be positioned on one or both ends 607 of the axle 600. The diameter of the openings of the ends 607 can be substantially the same as the diameter of the channel 605. The diameter of the openings of the ends 607 may less than the diameter of the channel 605. As shown, the motorized wheel 00 is mounted on one end of the axle 600. The boss 355 may be rigidly attached to the outer wall of the axle 600. The outer end of the boss 355 may be substantially flush with an open end 607 of the axle 600. As described above the stator 340 is rigidly attached to the boss 355. The outer bell end 310, rotor 350, and inner bell end 320 are each rigidly connected to each other as described above. Outer and inner bearings 3 5, 325 allow the outer bell end 310, rotor 350, and inner bell end 320 to rotate together relative to the boss 355 and the stator 340. The tire 200 is retained on the electric motor 300 by the hubcap 250 as described above. Accordingly, when the electric motor 300 is operated, the motorized wheel 100 is driven.

[0083] Arrows 615 in FIGS. 6 and 7 illustrate on example flow path for a fluid cooling system that uses air as the heat transfer medium. As shown by the arrows 615 in FIG. 6, air can enter the hollow axle 600 through the opening 610. The air may be ambient air or may be air forced through the opening 610 as part of a forced cooling system. As shown by the arrows 615 in FIG. 7, the air bifurcates upon entry into the interior channel 605 of the axle 600. The flow the heat transfer medium may be in the opposite direction from the arrows 615 illustrated in FIG. 7 to, for example, flow from cooling holes 323 to cooling holes 313. The axle 600 may be fully hollowed out, forming a lumen with a circumscribing surface that is substantially coaxial with the outer surface of the axle. The axle 600 may partially hollowed out, forming a C-section through a part of the axle along the central axis.

[0084] Following the arrows 615, the air travels out the open end 607 of the hollow axle 600, where it impinges on the inner surface of the hubcap 250. The air is then redirected by the hubcap 250 through the opening 207 (see FIG. 3) in the tire 200. The tire 200 can include a shape and/or passages that act as a centrifugal fan to guide the air toward the electric motor 300. However, the performance of the tire 200 as a centrifugal fan will vary depending on the speed of the tire. Regardless, the tire 200 and the hubcap 250 direct the air flow toward the electric motor 300. As shown, the air enters the electric motor 300 through cooling holes 313 of the outer bell end 310. The air then travels through the gaps in the windings of the stator 340, cooling them. The air then proceeds out through the cooling holes 323 in the inner bell end 320. Thus, air may be fed through the axle 600 and through the motorized wheel 100 to cool the electric motor 300 as part of the cooling system 700. Thermal energy from the electric motor 300 (various parts as discussed herein) is transferred to the airflow, which is then directed or channeled out of the motorized wheel 100.

[0085] Air (or other cooling fluids) can be directed into the electric motor 300, where it can extract heat from the stator windings and laminations before being exhausted to the atmosphere. The air can be run to the electric motor 300 from a port on the outboard side of the axle 600. The air can run through the axle 600 and then turn 180 degrees, pass through the outer bell end 310 of the electric motor 300, then through the windings of the stator 340, exhausting through the inner bell end 325 (as described above and shown with the arrows 615). Such a system can use the hubcap 250 as an air duct cover, reversing the flow of air from the hollow axle 600 into the electric motor 300.

[0086] As previously noted, using a hollow axle 600 can also allow for the wiring between the electric motor 300 and the deck to be run through the interior channel 605. The interior channel 605 can thus both cool the wiring and protect the wiring mechanically. Visually, the appearance of the board is improved by hiding the wiring in the hollow axle 600,

[0087] In the cooling system 700, fan blades may be molded into the outer bell end 310, inner bell end 320, tire 200, and/or hubcap 250 of the motorized wheel 100 to help move air through the system (e.g., through the motorized wheel 100). However, as previously noted, the speed of such a fan (and accordingly the cooling power of the system) is at least partially dependent on the speed at which the tire 200 rotates. Accordingly, at low speeds, such a fan may not adequately cool the motor windings. However, a forced air cooling system can be implemented by fitting a separately powered electric cooling fan to the motorized wheel. Such an arrangement may increase the size of the motorized wheel as the tire is extended to accommodate the fan. A cooling system is shown and described in reference to FIGS. 8 and 9.

[0088] FIG. 8 shows a partially exploded view of a motorized wheel 100a that includes a fan 275 (or other fluid moving device such as a pump). The fan 275 may be separately powered (in other words, powered by an additional electric motor), such that it can operate at a speed that is independent of the rotational speed of the tire. The fan 275 is a commonly available brushless DC type, wherein the fan motor is housed inside the fan blade molding. Other types of fans are possible.

[0089] As illustrated, the motorized wheel 100a may include a hubcap 250a. The hubcap 250a may be similar to the hubcap 250 previously described. For example, the hubcap 250a may be used to retain the tire 200a onto the electric motor 300. The hubcap 250a may also include bolt holes 251 for receiving bolts 253. However, unlike the hubcap 250, the hubcap 250a includes cooling holes 252, The cooling holes 252 may allow air flow to or from the fan 275. The number and arrangement of the cooling holes 252 on the hubcap 250a can vary. The hubcap 250a may include twelve cooling holes 252 arranged in a circle, although other numbers and arrangements are possible. The cooling holes 252 may be replaced by a screen or mesh. The cooling holes 252 may be omitted. As illustrated, the cooling holes 252 of the hubcap 250a may function as air inlet ports, with the fan blades pitched as shown and the fan 275 rotating counterclockwise.

[0090] The motorized wheel 100a includes a tire 200a. The tire 200a may be similar to the tire 200 described above. However, the tire 200a may be modified to accommodate the fan 275. For example, the width of the tire 200a may be extended when compared to the tire 200 to accommodate the fan 275, although this need not be the case in all embodiments. Additionally, an interior flange 215a of the tire 200a may be shaped to include a fan shroud 219 to help control air flow through the fan 275. FIG. 9 shows a partially exploded view of the motorized wheel 100a, illustrating an embodiment of the fan 275 positioned within the tire 200a. As shown in this figure, there may be a close relationship (for example, a narrow gap) between the surface of the fan shroud 219 of the interior flange 2 5a and the fan 275. The interior flange 215a may also include bolt holes 21 1 and a central opening 207 as described above in reference to the tire 200. The tire 200a is configured to mount on an electric motor 300a. The hubcap 250a may aid in retaining the tire 200a on the electric motor 300a as previously described.

[0091] The motorized wheel 100a also includes an electric motor 300a. The electric motor 300a may include features similar to those described above in reference to the electric motor 300. For example, the electric motor 300a includes an outer bell end 310 having bolt holes 3 1 and cooling holes 313 as shown. The electric motor 300a can include an inner bell end 320 having cooling holes 323 such that cooling air flows from the cooling holes 313 to the cooling holes 323 as discussed herein, with the airflow being forced or pumped by the fan 275 from the hubcap 250 to toward the electric motor 300a.

[0092] The electric motor 300a also includes a boss 355 as described above. A plug 302 for connecting to the fan 275 may be positioned within the boss 355. Wiring to the plug 302 can be run through the boss 355 and through a hollow axle (for example the hollow axle 600 described above). The plug 302 can provide structural support to position the fan 275 within the fan shroud 2 9.

[0093] Other embodiments of using a fan as part of a cooling system are possible. For example, to connect the hollow axle to the fan, several methods can be used. The fan may be mounted directly on the axle, blowing ambient screened air into the axle. However, this may put the fan in a position exposed to impact from curbs and potholes. The fan may also be mounted on the deck of a skateboard, or in the deck in the case where the deck is hollow, and the air (or other cooling fluids) can be ducted to a hollow axle by means of hollow flexible air ducts, such as corrugated plastic tubes. In some embodiments, non-hollow or solid axle may be used with the motorized wheel 100a where the fan 275 provides the desired cooling of the electric motor 300a.

[0094] FIG. 10 is a cross-sectional view of the motorized wheel 100 mounted on an axle 600 that includes an axle-mounted fluid cooling system 1000. The fluid cooling system 1000 may use a fluid, for example, water, as the heat transfer medium. The motorized wheel 100a, including the fan 275, may also be used with the cooling system 1000. As shown in the figure, the motorized wheel 100 is mounted on an axle 600a. The motorized wheel 100 has been previously described.

[0095] The axle 600a is hollow and includes an interior channel 605. The interior channel 605 may be a fluid channel. However, in contrast with the axle 600 previously described, the interior channel 605 of the axle 600a includes closed ends 608. The closed ends 608 may substantially contain the fluid heat transfer medium within the axle 600a. The axle 600a also includes a cooling fluid inlet tube 609. The cooling fluid inlet tube 609 may be located at least partially within the interior channel 605. The cooling fluid inlet tube 609 may be connected to a supply for the fluid heat transfer medium. The supply may be located, for example, on or in the deck of a skateboard. As shown by the arrows 616, the fluid heat transfer medium is pumped in to a hollow axle 600a through the cooling fluid inlet tube 609. Upon exiting the cooling fluid inlet tube 609, the fluid heat transfer medium reverses direction as it impinges on the closed end 608 and travels back through the space between the cooling fluid inlet tube 609 and the axle 600. The flow the heat transfer medium may be in the opposite direction from the arrows 616 illustrated in FIG. 10. Thus, the fluid heat transfer medium can provide cooling for the axle 600, which can be made of aluminum. Further, the heat of the motorized wheel 100 can transfer by solid thermal conduction from the motorized wheel 100, where heat is generated mostly in the motor windings by copper losses and in the silicon steel laminations through eddy currents and hysteresis, to the axle 600. Thus, the cooling system 1000 may also cool the motonzed wheel 100. The heat conducts through the laminations of the stator 340, through the axle 600, and into the fluid heat transfer medium. The axle 600a and the cooling fluid inlet tube 609 may form part of a closed loop cooling circuit. [0096] Wiring entry and exit holes 601 are shown in FIG.10, but the wiring itself has been omitted for clarity. The wiring entry and exit holes 601 may be fluid sealed such that the fluid heat transfer medium is contained within the axle 600.

[0097] The cooling system illustrated in FIG. 10, may provide a low cost and reliable method of removing heat from the electric motor 300 of the motorized wheel 100. Advantageously, rotating fluid (e.g., liquid) seals are not necessary. The wiring to the electric motor 300 can be water jacketed within the axle 600, meaning much smaller wiring can be used for a given peak motor current. Further, the inner bearing 325 and the outer bearing 315 can be also cooled via thermal contact with the axle 600 and fluid heat transfer medium, extending their life. Additionally, the surfaces that are in contact with the fluid heat transfer medium can act as heat sinks, particularly if they are made of thermally conductive metal, or are of a large area. Significant cooling can be achieved by using the axle 600 as a heat sink, particularly in applications such as a skateboard where there is cooling air (in other words, ambient air) flowing over the outside of the axle 600. In battery powered applications, the same cooling circuit can be used to cool other parts of the system, such as the speed controller heatsinks and the batteries. This allows for smaller and lighter components than otherwise would be possible. Fluid cooling of batteries allows a faster charging and discharging rate. Adding a fluid cooling circuit for the motors lends itself to also cooling the batteries to take this advantage. Many other fluid cooled (in other words, water or other liquid cooled) embodiments are possible.

[0098] The axle can be a custom extrusion, with fluid ducts (such as the cooling fluid supply tube or line) built in, to separate the wiring from the fluid path. This design can substantially negate the need to seal the wiring entry and exit points. To improve the conduction of heat from the windings to the axle, silicon thermal grease, gel, silicon rubber, or similar paste can be used to improve the thermal coupling between them. In addition or alternatively, a liquid cooled system can include filling the axle with cooling fluid and adding cooling surface area to the axle for improved heat dissipation, such as cooling fins, and rely on natural convection of fluid inside the axle.

[0099] FIG. 11 is a cross-sectional view of a motorized wheel 100 mounted on an axle 600b that includes an axle and motor fluid cooling system 1100. The fluid cooling system 1100 may use a fluid, for example, water, as the heat transfer medium. The motorized wheel 100a, including the fan 275 may also be used with the cooling system 1000. As shown in the figure, the motorized wheel 100 is mounted on an axle 600b. The motorized wheel 100 has been previously described.

[0100] The axle 600b is hollow and includes an interior channel 605. The axle 600b also includes closed ends 608. A cooling fluid inlet tube 609b extends partially through the interior channel 605. The cooling fluid inlet tube 609b may enter and exit interior channel 605 of the axle 600 through exit holes 601. The cooling fluid inlet tube 609b extends into an interior of the electric motor 300, such as the space contained within the outer bell end 310, the stat or 340, and the inner bell end 320.

[0101] The cooling fluid inlet tube 609b may also be connected to a supply of the heat transfer medium. The supply may be located on or in the deck of a skateboard, for example. As such the cooling fluid inlet tube 609b delivers the fluid heat transfer medium into the electric motor 300. The outer bell end 310 and inner bell end 320 may be enclosed to substantially contain the fluid heat transfer medium within the electric motor, where it cools the magnets of the rotor 350, copper windings steel laminations of stator 340, inner bearing 325, and outer bearing 325, as well as removing heat generated by the tire 200. The fluid heat transfer medium exits the electric motor 300 through the exit hole 601 and travels back through the hollow axle 600a, and out exit hole 602. One example flow path for the fluid heat transfer medium is shown with the arrows 617. The flow the heat transfer medium may be in the opposite direction from the arrows 617 illustrated in FIG. 11. The cooling system 1100 may be a closed loop cooling circuit.

[0102] Embodiments like those illustrated in FIG. 11 may allow for increased cooling for the electric motor 300 because direct fluid cooling of the copper windings of the stator 340 can be achieved. This may allow for increased possible motor power to weight ratio. For example, when the motorized wheel 100 is used in a slow speed application such as in a skateboard, the electric motor 300 can be pumped with cooling fluid, using an axle with a high pressure feed line and a hollow void return path (such as the axle 600b described above). Since there are substantially no exposed electrical components, water with anti corrosion additives can be used as a coolant. Where the electric motor 300 contains a circuit board, the circuit board can be potted or epoxy encapsulated before being installed in the motor. Fluid cooling substantially the entirety motor can thus be achieved, and such an arrangement can cool the magnets as well as the windings. The variation in temperature of the windings can be improved, since hot spots may then occur where the copper is buried under other turns. However, in random wound brushless motors, the windings tend to be open enough to allow adequate cooling of even the inner layers of copper. Further, cooling the whole electric motor 300 may include simultaneously cooling rotor magnets. This may allow the use of higher strength magnets, for example, N52 magnets. This can further increase the power to weight ratio of the motor. N52 magnets may have an operation temperature limitation of about 80 degrees Celsius, above which they can demagnetize.

[0103] Where the application of the motor requires a speed high enough that fluid friction losses are unacceptabiy high, then the windings can still be fluid cooled by a forced (e.g., liquid) cooling system while enclosed in a container to prevent the fluid (e.g., liquid) from contacting the moving rotor, magnets, and bell ends.

[0104] FIG. 12 shows a perspective view of a motorized wheel 100b that includes a hubcap 250b with keyhole slots 251b that engage an electric motor via bolts 253 and other mechanisms as discussed herein. FIG. 13 is an exploded view of the motorized wheel 100b of FIG. 12. The motorized wheel 100b may be similar to the motorized wheels previously described. However, the motorized wheel 100b is retained onto the electric motor via a hubcap 250b that includes keyhole slots 251b. The keyhole slots 251b engage with bolts 253b to secure the hubcap. Bolts 253b extend from the bolt holes 311 in the outer bell end 310 through the bolt holes 211 in the tire 200. Wheel bolt sleeves 257b may be used as previously described above. The heads of the bolts 253b extend free through the bolt holes 211 of the tire.

[0105] As illustrated in FIGS. 12 and 14, Each of the keyhole slots 251b includes a round open end connected to a slot. To engage the hubcap 250b, the heads of the bolts 253 b are inserted through the round open end of the keyhole slots. The hubcap 250b can then be rotated relative to the tire 200, using the handle 256 or other suitable gripping protrusion or ridge, such that the bolt heads nest within the slots of the keyhole slots 251b. Thus, the bolts 253b lock the hubcap 250b on to the wheel when the hubcap 250b is rotated relative to the motor. The resilience of the tire 200 retains the hubcap 250b. However, other anti-rotation locking mechanisms to prevent the hubcap from undoing (rotating off) can be implemented, including spring loaded locking pawls, locking pins, clips, bolts, and releasable ratchet pawls,

[0106] The color, embellishments, and exterior decoration of the motorized wheels and other elements described herein are not relevant to the function and may be of any style the market desires.

[0107] It is contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments disclosed above may be made and still fall within one or more of the inventions. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with an embodiment can be used in all other embodiments set forth herein. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, it is intended that the scope of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above. Moreover, while the inventions are susceptible to various modifications, and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail It should be understood, however, that the inventions are not to be limited to the particular forms or methods disclosed, but to the contrary, the inventions are to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the various embodiments described and the appended claims. Any methods disclosed herein need not be performed in the order recited. The methods disclosed herein include certain actions taken by a practitioner; however, they can also include any third-party instruction of those actions, either expressly or by implication. For example, actions such as "passing a suspension line through the base of the tongue" include "instructing the passing of a suspension line through the base of the tongue." It is to be understood that such depicted architectures are merely examples, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. The ranges disclosed herein also encompass any and all overlap, sub-ranges, and combinations thereof. Language such as "up to," "at least," "greater than," "less than," "between," and the like includes the number recited. Numbers preceded by a term such as "approximately", "about", and "substantially" as used herein include the recited numbers, and also represent an amount close to the stated amount that still performs a desired function or achieves a desired result, For example, the terms "approximately", "about", and "substantially" may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount. Features of embodiments disclosed herein preceded by a term such as "approximately", "about", and "substantially" as used herein represent the feature with some variability that still performs a desired function or achieves a desired result for that feature.

[0108] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

[0109] It will be understood by those within the art that, in general, terms used herein, are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least" the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced embodiment recitation is intended, such an intent will be explicitly recited in the embodiment, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the disclosure may contain usage of the introductory phrases "at least one" and "one or more" to introduce embodiment recitations. However, the use of such phrases should not be construed to imply that the introduction of an embodiment recitation by the indefinite articles "a" or "an" limits any particular embodiment containing such introduced embodiment recitation to embodiments containing only one such recitation, even when the same embodiment includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce embodiment recitations. In addition, even if a specific number of an introduced embodiment recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, embodiments, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

[0110] Although the present subject matter has been described herein in terms of certain embodiments, and certain exemplar}' methods, it is to be understood that the scope of the subject matter is not to be limited thereby. Instead, the Applicant intends that variations on the methods and materials disclosed herein which are apparent to those of skill in the art will fall within the scope of the disclosed subject matter.

Claims

WHAT IS CLAIMED IS:

1. A motorized wheel assembly that is configured to be cooled while propelling a vehicle, the assembly comprising:

an electric motor comprising:

a stator;

a rotor about the stator, the rotor configured to rotate relative to the stator:

an outer bell end connected to a first end of the rotor, the outer bell end comprising one or more first openings configured to allow a fluid to pass through the one or more first openings; and

an inner bell end connected to a second end of the rotor, the inner bell end comprising one or more second openings configured to allow the fluid to pass through the one or more second openings, wherein the stator is between the outer and inner bell ends; and

a tire on the rotor, the tire configured to support a vehicle relative to a support surface,

wherein the electric motor is configured to cause the rotor to rotate relative to the stator to cause the tire to rotate relative to the support surface to propel the vehicle agamst the support surface, and

wherein the fluid flows between the one or more first openings and the one or more second openings to cool the electric motor during operation of the electric motor.

2. The assembly of claim 1, wherein the fluid flo ws within the rotor between the one or more first and second openings, the fluid flowing proximate to the stator to cool at least the stator.

3. The assembly of claim 1 or 2, further comprising an axle, the stator fixed to the axle to cause the rotor to rotate relative to the axle to propel the vehicle relative to the support surface during operation of the electric motor, wherein the axle comprises a channel extending along a central axis, the channel configured to direct the fluid toward or away from the one or more first and second openings to cool the electric motor.

4. The assembly of claim 3, further comprising a cap connected to the electric motor, the cap configured to direct fluid from or to the channel of the axle and toward or away from the one or more first and second openings, respectively.

5. The assembly of claim 4, wherein the axle comprises a first orifice in fluid communication with the channel of the axle, the first orifice configured to direct fluid from or to the channel of the axle and toward or away from the one or more first and second openings, respectively, wherein the cap impinges the fluid to flow away from or toward the central axis and toward or away from the one or more first and second openings, respectively.

6. The assembly of claim 5, wherein the axle further comprises a second orifice in fluid communication of the channel of the axle, the second orifice configured to direct fluid into or out of the channel.

7. The assembly of claim 6, wherein the fluid flows into the second orifice, flows through the channel, flows out of the first orifice, impinges against the cap toward the one or more first openings, flows through the one or more first openings into the electric motor, flows through the electric motor toward the one or more second openings, and flows out through the one or more second openings.

8. The assembly of any one of claims 3 to 7, wherein electrical wiring to power or control the electric motor extends through at least a part of the channel to the electric motor.

9. The assembly of any one of claims 4 to 8, wherein the cap and the tire are connected to the outer bell end via one or more fasteners.

10. The assembly of claim 9, wherein the cap comprises one or more slots configured to mate with the one or more fasteners, wherein the cap is configured to rotate relative to the fasteners to position the one or more fasteners within the slots to facilitate retaining the cap relative to the electric motor or the tire.

11. The assembly of any one of claims 1 to 10, further comprising a fluid moving device configured to direct the fluid toward or away from the one or more first and second openings.

12. The assembly of claim 1 1 , wherein the fluid moving device is positioned in a central opening in the tire, the central opening in fluid communication with the one or more first and second openings.

13. The assembly of any one of claim 11 or 12, wherein the fluid moving device comprises a fan configured to direct the fluid toward the one or more first openings, and wherein the fluid comprises air.

14. The assembly of any one of claims 4 to 11, wherein the cap comprises one or more apertures in fluid communication with the one or more first and second openings, the one or more apertures configured to direct the fluid toward the one or more first and second openings to cool the electric motor during operation of the electric motor.

15. The assembly of claim 14, further comprising a fan positioned in a central opening of the tire, the fan configured to direct the fluid from the one or more apertures toward the one or more first openings, and wherein the fluid comprises air.

16. The assembly of any one of claims 1 to 15, wherein the vehicle is a skateboard and the motorized wheel assembly is configured for use with the skateboard.

17. The assembly of any one of claims 1 to 10, wherein a fluid moving device is positioned in the vehicle, the fluid moving device in fluid communication with the one or more first and second openings via one or more fluid channels, wherein the fluid moving device is configured to direct the fluid toward the one or more first and second openings via the one or more fluid channels.

18. The assembly of claim 17, wherein the vehicle is a skateboard and the motorized wheel assembly is configured to be connected to a hanger of the skateboard, wherein the hanger is connected to a truck that is connected to a deck of the skateboard, wherein the fluid moving device is mounted in the deck, and wherein the one or more fluid channels extend at least in part through the hanger and the truck to fluidly connect the fluid moving device and the one or more first and second openings.

19. A motorized wheel assembly for propelling a vehicle, the assembly comprising:

an axle comprising a channel extending along a central axis, the channel configured to direct a fluid along the central axis; and

an electric motor comprising: a stator connected to the axle, the stator positioned over at least a part of the channel; and

a rotor extending along the central axis, the rotor positioned about the stator, the rotor configured to rotate relative to the stator,

wherein the electric motor is configured to cause the rotor to rotate relative to the stator to propel a vehicle, and

wherein the fluid flows through at least a part of the channel over which the stator is positioned to cool the electric motor during operation of the electric motor.

20. The assembly of claim 19, further comprising a tube extending through at least a portion of the channel along the central axis, the tube configured to direct the fluid toward the electric motor, wherein after the fluid exits from the tube, the fluid flows proximate to the at least a part of the channel over which the stator is positioned when the electric motor is being cooled.

21. The assembly of claim 20, after flowing proximate to the at least a part of the channel over which the stator is positioned, the fluid is directed through the channel over the tube to exit the channel of the axle.

22. The assembly of claim 20 or 21, wherein an end of the tube is positioned within the channel for the fluid to exit from the end of the tube into the channel.

23. The assembly of claim 20 or 21, further comprising an outer bell end connected to a first end of the rotor, an inner bell end connected to a second end of the rotor, wherein the stator is between the outer and inner bell ends, wherein an end of the tube is positioned between the outer bell end and the inner bell end outside of the channel of the axle, wherein the outer and inner bell ends and stator are configured to contain the fluid exiting from the end of the tube for the fluid to cool at least the stator of the electric motor.

24. The assembly of claim 23, wherein the fluid exits the electric motor into the channel of the axle through an exit hole in the axle, the exit hole fluidly connecting the channel and the end of the tube.

25. The assembly of any one of claims 19 to 24, wherein the fluid circulates in a closed loop cooling system.

26. The assembly of any one of claims 19 to 25, wherem electrical wiring to power or control the electric motor extends through at least some of the channel to the electric motor.

27. The assembly of any one of claims 19 to 26, wherein a fluid moving device is positioned in the vehicle, the fluid moving device in fluid communication with the channel of the axle, wherein fluid moving device is configured to direct the fluid toward or away from the electric motor.

28. The assembly of claim 27, wherein the vehicle is a skateboard and the motorized wheel assembly is configured to be connected to a hanger of the skateboard, wherein the hanger is connected to a truck that is connected to a deck of the skateboard, wherem the fluid moving device is mounted in the deck, and wherein one or more fluid channels extend at least in part through the hanger and the truck to connect the fluid moving device and the at least a part of the channel over which the stator is positioned.

29. The assembly of any one of claims 19 to 27, wherein the vehicle is a skateboard and the motorized wheel assembly is configured for use with the skateboard.

30. The assembly of any one of claims 19 to 29, wherein the fluid comprises a liquid phase heat transfer medium.

31. The assembly of any one of claims 19 to 30, wherein the fluid comprises a gas.

32. An electric motor comprising:

a stator;

a rotor about the stator, the rotor configured to spin relative to the stator;

a first bell end connected to a first end of the rotor, the first bell end comprising one or more first openings configured to allow a fluid to pass through the one or more first openings; and

a second bell end connected to a second end of the rotor, the second bell end comprising one or more second openings configured to allow the fluid to pass through the one or more second openings, wherein the stator is between the first and second bell ends,

wherein the rotor is configured to spin relative to the stator while the electric motor operates, and wherein the fluid flows between the one or more first openings and the one or more second openings to cool the electric motor during operation of the electric motor.

33. The electric motor of claim 32, wherein the fluid flows within the rotor between the one or more first and second openings, the fluid flowing proximate to the stator between the first and second bell ends to cool at least the stator.

34. The electric motor of claim 32 or 33, wherein the electric motor is configured to be used with a vehicle for the electric motor to propel the vehicle when the electric motor is operating.

35. The electric motor of claim 34, wherein the vehicle is a skateboard, wherein the electric motor is connected to an axle of the skateboard, and wherein the axle comprises a channel configured to direct the fluid toward or away from the one or more first and second openings.

36. The electric motor of any one of claims 32 to 35, wherein the electric motor is cooled via forced convection with a fluid moving device moving the fluid through the one or more first and second openings.

37. A method of manufacturing an electric motor, the method comprising:

providing a stator;

positioning a rotor about the stator, the rotor configured to rotate relative to the stator;

connecting a first bell end to a first end of the rotor, the first bell end comprising one or more first openings configured to allow a fluid to pass through the one or more first openings;

connecting a second bell end to a second end of the rotor to position the stator between the first and second bell ends, the second bell end comprising one or more second openings configured to allow the fluid to pass through the one or more second openings,

wherein the one or more first and second openings are configured to allow the fluid to flow between the one or more first and second openings to cool at least the stator.

38. A method of manufacturing a motorized wheel, the method comprising: manufacturing an electric motor according to claim 37;

positioning a tire on the rotor, the tire configured to support a vehicle relative to a support surface,

wherein a fluid is capable of flowing between the one or more first openings and the one or more second openings to cool the electric motor during operation of the electric motor to propel the vehicle.

39. The method of claim 38, further comprising connecting the stator to an axle, wherein the axle comprises a channel extending along a central axis, the channel configured to direct the fluid toward or away from the one or more first and second openings of the electric motor to cool the electric motor.

40. The method of claim 39, further comprising connecting a cap to the electric motor, the cap configured to direct fluid from or to the channel of the axle and toward or away from the one or more first and second openings, respectively.

41. The method of claim 40, further comprising rotating the cap to nest fasteners with slots of the cap to promote retaining the cap relative to the electric motor via the fasteners.

42. The method of any of claims 38 to 41, further comprising fluidly connecting a fluid moving device to the one or more first and second openings, the fluid moving device configured to direct the fluid toward or away from the one or more first and second openings.

43. The method of claim 42, further comprising positioning the fluid moving device in the vehicle and fluidly connecting the fluid moving device with the one or more first and second openings via one or more fluid channels in the vehicle.

44. The method of claim 43, further comprising connecting the electric motor to a hanger of a skateboard, connecting the hanger to a truck of the skateboard, connecting the truck to a deck of the skateboard, and mounting the fluid moving device in the deck, wherein the one or more fluid channels extend at least in part through the hanger and the truck to fluidly connect the fluid moving device and the one or more first and second openings.

45. The method of claim 42, further comprising positioning the fluid moving device in a central opening in the tire, the central opening in fluid communication with the one or more first and second openings.

46. A method of manufacturing a motorized wheel, the method comprising: connecting an electric motor to an axle, the axle comprising a channel extending along a central axis, the electric motor connected to the axle over at least a portion of the channel, and the channel configured to direct a fluid along the central axis,

wherein the channel is configured to direct flow of the fluid into the at least porti on of the channel over which the electric motor i s connected to the axle to cool the electric motor during operation of the electric motor.

47. The method of claim 46, further extending a tube through at least pari of the channel to direct flow of the fluid to the at least portion of the channel over which the electric motor is connected to the axle.

48. The method of claim 47, further comprising extending the tube into an interior of the electric motor.