Construction of motorized wheel for vehicle motorization

A motorization apparatus for a motorized wheel comprises an axle secured to a frame of a vehicle. A rotor unit has poles of magnet material. A stator unit having slots and teeth secured to the axle is inward of said rotor to define a clearance gap therewith such that the rotor unit is rotatable about the stator core. An arrangement of coils is wound around the teeth of the stator unit, the coils adapted to be powered to induce a rotation of the rotor unit relative to the stator unit. A structure comprises hub portions rotatably mounted to the axle, the structure having lateral walls defining an inner volume for the rotor unit and the stator unit, the structure supporting the rotor unit. The structure comprises attachment members connected to spokes of the motorized wheel, located radially inward of the clearance gap between the rotor unit and the stator unit.

TECHNICAL FIELD

The present application pertains to a construction of a wheel featuring a wheel motor, a.k.a., motorized wheel, wheel hub drive, wheel hub motor, hub motor, in-wheel motor, etc, for vehicle motorization.

BACKGROUND OF THE ART

Wheel motors are commonly used for the motorization of vehicles, such as bicycles, scooters, lightweight motorcycles, cars, etc. A wheel motor comprises a stator hub with windings, and a rotor wheel rotating about the hub. The rotor wheel comprises a plurality of magnets driven by the current in the windings. Advantageously, the wheel motor operates as a direct drive; there is no transmission to convert the motor output to a given speed. The power output of the wheel motor is as a function of the electrical current fed to the wheel motor.

There are continuous efforts to increase the power output from wheel motors. Some parameters can be used to alter the power output of the wheel motors, such as rotor size. However, there may be constraints to adjusting a rotor size, as wheels come in standard dimensions. For instance, bicycle wheels for adult bicycles typically come within standard diameters, such as 26 inches, 29 inches, 700 mm or 650 mm. In order to maximize the size of the motors, spokes are conventionally attached to an outer periphery of the motor casings, with substantially shorter spokes than usual for standard-diameter wheels. As spoke add to the comfort of the rider for instance by their flexing action, the shortening of the spokes may have an adverse effect on the riding experience.

SUMMARY

It is therefore an aim of the present disclosure to provide a construction of a wheel and wheel motor that addresses issues associated with the prior art.

Therefore, in accordance with the present disclosure, there is provided a motorization apparatus for a motorized wheel comprising: an axle adapted to be secured to a frame of a vehicle; a rotor unit having a plurality of poles of magnet material; a stator unit secured to the axle and being inward of said rotor and defining a clearance gap with the rotor unit such that the rotor unit is rotatable about the stator core, said stator unit having slots and defining teeth between said slots; an arrangement of coils of insulated wire being wound around the teeth of the stator unit, the coils adapted to be powered to induce a rotation of the rotor unit relative to the stator unit; a structure comprising hub portions rotatably mounted to the axle, the structure having lateral walls defining an inner volume for the rotor unit and the stator unit, the structure supporting the rotor unit relative to the stator unit for the rotor unit to rotate with the structure about the stator unit, the structure further comprising attachment members adapted to be connected to spokes of the motorized wheel, the attachment members being located radially inward of the clearance gap between the rotor unit and the stator unit.

Further in accordance with the embodiment, the hub portions are on opposite sides of the motorization apparatus and each have: a tubular portion; and at least one bearing per tubular portion connecting the tubular portion to the axle for rotation of the tubular portion relative to the axle.

Still further in accordance with the embodiment, each of the hub portions has a flange projecting radially from the tubular portion, the attachment members being on the flange.

Still further in accordance with the embodiment, the flange has a crenellated periphery and the attachment members are holes in the crenellated periphery.

Still further in accordance with the embodiment, the attachment members are on a diameter of the flange ranging between 20 and 500 mm.

Still further in accordance with the embodiment, the structure comprises cover plates connected to the hub portions, the cover plates extending radially from the hub portions and interconnected to one another at an outer periphery of the motorization apparatus, the cover plates defining concurrently a substantial portion of the inner volume enclosing the rotor unit and the stator unit.

Still further in accordance with the embodiment, the cover plates are made of a non-ferrous material.

Still further in accordance with the embodiment, at least the tubular portions of the hub portions are made of metal.

Still further in accordance with the embodiment, one of the hub portions further comprises one of a freehub and a freewheel hub having a first end connected to and rotating with the tubular body, and a second cantilevered end projecting away from the hub portion.

Still further in accordance with the embodiment, at least one channel is defined in an outer surface of the shaft for routing at least one cable for powering or controlling a power to the arrangement of coils, a first end of the at least one channel communicating with the inner volume of the structure, and a second end of the at least one channel being exterior to the structure.

Still further in accordance with the embodiment, a dropout abutment on the axle is adapted to prevent rotation of the axle relative to the frame of the vehicle.

Still further in accordance with the embodiment, a printed circuit board (PCB) is secured to the stator unit and wired to the arrangement of coils.

Still further in accordance with the embodiment, at least one receptacle is fixedly secured to the stator unit and positioned in one of the slots, the at least one receptacle adapted to receive therein a sensor of the PCB to determine an orientation of the rotor unit relative to the stator unit.

Still further in accordance with the embodiment, the stator unit comprises eighty-four of the slots.

Still further in accordance with the embodiment, the eighty-four slots are regrouped in four continuous sets of teeth per phase.

Still further in accordance with the embodiment, each of the continuous sets of teeth per phase has seven teeth.

Still further in accordance with the embodiment, there are one of eighty, eighty-eight and ninety-two of the poles.

Still further in accordance with the embodiment, one of spline connection, knurling, serrated splines is between the axle and the stator unit.

Still further in accordance with the embodiment, a ratio of rotor radius to rotor width of at least 10.

Still further in accordance with the embodiment, there is provided a motorized wheel comprising: the motorization apparatus according to the above; a rim; and spokes extending from the rim to the hub portions of the structure, a wheel inner volume being bound by innermost ones of the spokes, with at least the rotor unit being within the wheel inner volume.

Still further in accordance with the embodiment, the arrangement of coils of insulated wire being wound around the teeth of the stator unit is within the wheel inner volume.

Still further in accordance with the embodiment, the rim has a diameter between 584 mm and 700 mm.

In accordance with a further embodiment of the present disclosure, there is provided a motorization apparatus comprising an outer rotor with eighty, eighty-eight or ninety-two poles constructed with segments of permanent magnet material sequentially magnetized north and south, the outer rotor adapted to be part of a wheel and rotating with the wheel about an axis thereof; a stator core of ferromagnetic material spaced inwardly of said rotor and defining a clearance gap with the rotor such that the rotor is rotatable about the stator core, the stator core having an outer diameter ranging between 150 mm and 500 mm, said stator core having eighty-four slots and defining teeth between said slots; and a three-phase winding with coils of insulated wire being wound around the teeth of the stator core.

Still further in accordance with the further embodiment, the outer rotor has eighty-eight poles, and wherein the three-phase winding is divided in four sets of consecutive teeth for each of the three phases

Still further in accordance with the further embodiment, each of the four sets of a same phase has two pairs of sets that are diametrically opposed in the stator core.

Still further in accordance with the further embodiment, the three-phase winding are divided into four sets of seven consecutive teeth for each of the three phases.

Still further in accordance with the further embodiment, each said phase of the three-phase winding is divided into sets of six and eight consecutive teeth.

Still further in accordance with the further embodiment, the stator is fixed to an axle of the wheel.

Still further in accordance with the further embodiment, the rotor is adapted to be operatively connected to a freewheel or freewheel hub of a vehicle to rotate therewith in one rotational orientation.

Still further in accordance with the further embodiment, each said phase comprises 28 teeth.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings and more specifically toFIGS. 1 and 2, a wheel with wheel motor in accordance with the present disclosure is generally shown at10. The motorized wheel10is of the type that is used in vehicles such as bicycles, tricycles, scooters and any other appropriate type of vehicle. The motorized wheel10is shown in a configuration particularly well suited to be used in a bicycle, notably by the diameter and width of the motorized wheel10. For example, the motorized wheel10is essentially similar to a back wheel of an adult size bicycle, such as a 700 mm wheel, a 650 mm wheel, a 26 inch wheel, a 29 inch wheel, (i.e., ISO5775, ISO 622 (700C and 29po), ISO 584 (650B), ISO 559 (26po)—range of 584 to 700 mm in diameter) despite the fact that wheels of smaller or larger diameters could be used as well. Moreover, although the motorized wheel10is shown as having a freehub or a freewheel hub for supporting a cassette of cogs or freewheel, as discussed hereinafter, the motorized wheel10could be without such a freewheel hub. As an example, the motorized wheel10could be used as the front wheel of a bicycle, which does not require a freewheel hub.

The motorized wheel10has a motorization apparatus featuring a synchronous machine12. The synchronous machine12may also be referred to as a motor, a synchronous motor, an electric motor among other names. The synchronous machine12is configured to act as the hub of the motorized wheel10and is therefore connected to rim13by way of spokes14, so as to transmit its output to the rim13. It is observed that, in similar fashion to typical wheels, the spokes14define an inner volume A between innermost ones of the spokes14on either side of the motorized wheel10, as best seen inFIG. 3. The inner volume A is bound by the rim13and by the spokes14.

The synchronous machine12is substantially lodged into the inner volume A, and also serves as connection for ends of the spokes14, in similar fashion to a hub. More specifically, as shown hereinafter, at least some of the active components of the machine12are in the inner volume A, including the rotor, magnets, stator coils, and/or stator, etc. An axle15will interface the synchronous machine12and thus the motorized wheel10to a frame component of the vehicle, for instance chain stays, a fork of a bicycle, or any other frame component, depending on the type of vehicle with which the motorized wheel10is used. The axle15has a given geometry that will be discussed hereinafter, but has ends extending beyond the synchronous machine12, at which ends nuts16are provided along with spacers17of different shapes for the motorized wheel10to be releasably secured to a frame of the vehicle, for instance in the drop outs thereof. Although not shown, the axle, nuts and spacers may for instance be part of a quick release skewer. The axle15may also define an inner channel18by which wires may be introduced into the synchronous machine12to provide power to the synchronous machine12as well as commands.

Referring concurrently toFIGS. 3, 4 and 5, the synchronous machine12is shown in greater detail as having a structure rotatably mounted to the axle, the structure comprising a drive side hub shell20, a driven side hub shell30, a drive side cover40, a driven side cover50. The spokes14are connected to the structure as described hereinafter for concurrent rotation. InFIGS. 5 to 7, a rotor unit60and a stator unit70are shown being located in an inner volume B of the structure, substantially defined by the covers40and50of the synchronous machine12.

The drive side hub shell20is the component of the structure by which the synchronous machine12is rotatably mounted to the axle15.

The driven side hub shell30is the component of the structure by which the synchronous machine12is rotatably mounted to the axle15on the driven side of the vehicle or the brake side in a configuration of the wheel10with a disc brake. In an embodiment of the motorized wheel10used without a freehub, there is no drive or driven side, whereby the hub shells20and30may be mirror images of one another. The hub shells20and30concurrently form the hub of the wheel10.

The drive side cover40and the driven side cover50concurrently form the inner volume B of the synchronous machine12and will therefore concurrently house the rotor unit60and the stator unit70, i.e., the active components of the synchronous machine12.

The rotor unit60is fixably secured to the covers40and50and will provide rotational forces thereto, which rotational forces are sustained by the rotor unit60by the powering of the stator unit70.

The stator unit70is fixed to the axle15for instance by way of spline arrangement, knurling, serrated spline, etc and therefore does not rotate with the rotor unit60. The stator unit70provides driving forces that will induce a rotation of the rotor unit60.

Referring concurrently toFIGS. 3 and 4, the drive side hub shell20is shown in greater detail. The drive side hub shell20has a tubular portion21. The tubular portion21is generally coaxial with the axle15. A freehub22is connected to the tubular portion21, and bearings23rotatably support the tubular portion21about the axle15. A pair of the bearings23are at an inside end of the tubular portion21and freehub22, whereas a seal23A is at the outer end of the freehub22(although a third bearing could be used instead of the seal23A). As is known in the art, the freehub22rotates concurrently with the tubular portion21in one direction. By using a seal23A instead of a bearing, the end of the freehub22is cantilevered and, as such, is particularly well suited to receive thereon strain gauges to measure the chain tension on the freehub22to calculate the pedalling power. In the other direction, a ratchet mechanism included in the freehub22will allow the freehub22to remain stationary while the tubular portion21(and thus the drive side hub shell20) rotates. The freehub22may be a standard freehub. It is pointed out that, as an alternative to a freehub22, a freewheel hub could be provided as well. Moreover, although not shown, it is contemplated to use an internal gear mechanism with the synchronous machine12.

A radial flange24projects radially from the tubular portion21. The radial flange24may have a crenellated periphery defining a plurality of spoke supports25by which ends of the spokes14will be connected to the drive side hub shell20. Throughbores or holes26are therefore provided on the spoke supports25to receive the ends of the spokes14. The holes26in the spoke supports25are one of multiple attachment members that may be used to connect spokes14to the structure, with other attachment members including tapped bores, nipples, etc. It is also considered to connect the spokes14directly to the tubular portion21, with appropriate attachment members being provided in the tubular portion21.

Referring toFIGS. 1 and 2, one contemplated wheel construction is shown with a given number of straight pull spokes. However, any other appropriate spoke arrangement is considered (e.g., hook spokes, etc). It is considered to use spokes of standard size and construction for convenience and ease of repair.

The drive side hub shell20defines a shoulder27of generally circular shape, upon which the drive side cover40will be abutted when the synchronous machine12is assembled. Fasteners such as bolts, screwing engagement, and/or adhesives, etc may be used to secure the cover40to the shell20. Other connection arrangements are also considered for the junction of the cover40to the shell20.

The driven side hub shell30is generally speaking a mirror image of the drive side hub shell20, with the exception of the freehub22, absent from the driven side hub shell30, and with additional differences is general shapes, for example. Hence, the driven side hub shell30has a tubular portion31rotatably mounted to the axle15by bearings33. A radial flange34with crenellated periphery for example projects from the tubular portion31and has spoke supports35by which the driven side hub shell30is connected to spokes14. Throughbores36in the spoke support35will receive the ends of the spokes14(as one of numerous possible attachment members considered to connect the spokes14to the structure). A shoulder37is oriented toward the inner volume B and serves as an abutment for the driven side cover50, although other connection arrangements are considered for the junction of the cover50to the shell30.

Referring concurrently toFIGS. 5, 6 and 7, the drive side cover40is shown having a cover plate41. A connector rim42is at an outer periphery of the cover plate41and will serve to connect the drive side cover40to the driven side cover50. Driven side cover50also has a cover plate51and has a complementary connector rim52that will cooperate with the connector rim42in the manner shown inFIG. 6to form the casing of the synchronous machine12. Referring toFIG. 1, the cover plates41and51and the connector rims42and52are respectively fastened to the hub shells20and30, and to one another by way of fasteners such as bolts, appropriate washers, bolts/screws and tapping, press-fitting, etc. It is shown that the covers40and50concurrently define an inner volume B. Moreover, the combined geometry of the covers40and50tapers in a radial direction, whereby a casing concurrently formed by the covers40and50fits inside the inner volume A defined by the spokes14, as observed inFIG. 3. In any event, the structure has lateral walls, for instance as defined partially by the covers40and50, which may or may not close the inner volume B.

Referring toFIG. 1, the covers40and50are shown having a generally octagonal outline, although other shapes may be used, such as circular, pentagonal, hexagonal, among numerous other possibilities. In order to optimize the performance of the motorized wheel10, the covers40and50must be as light as possible, yet be capable of sustaining the stresses associated with a motorized wheel. For instance, the covers40and50may be in a non-ferrous material such as a composite material while the hub shells20and30are made of ferrous material or a metal, as the hub shells20and30are connected to the spokes14. In selecting the materials, the coefficients of thermal expansion should be taken into consideration, so as not to impede the rotation of the rotor unit60relative to the stator unit70. Moreover, although the hub shells20and30are shown as being separate from the covers40and50, the structure could consist of the two half members, each half member being an integral assemble of hub shell (e.g.,20or30) and cover (e.g.,40and50). In such a case, the structure would have a hub portion integrated with a cover. Other arrangements are considered as well.

As shown in the embodiment ofFIGS. 3 and 4, the cover plates41and51may be relatively thin, but with reinforcement ribs thereon. Due to the limited space within the inner volume A, there is limited space for the ribs on the outer surfaces of the cover plates41and51. In the embodiment ofFIG. 1, ribs are shown having different segments53and54. The segments53each extend along a first one of the spokes14, and when a second one of the spokes14crosses over the first spoke14, the segments53end and the segments54commence, with the segments54extending along the second one of the spokes14. Hence, each rib has a pair of segments53,54, to follow a pattern of the spokes14. Although not visible, the cover40may have a similar pattern of ribs.

Referring concurrently toFIGS. 6, 7 and 8, the rotor unit60is shown as having an annular body61. The annular body61serves as a support for magnets62. The magnets62are typically made of a ferro-magnetic material and may be of any appropriate shape, such as rectangular shape. Any appropriate number of magnets could be used as a function of the configuration of the stator unit70.

Still referring toFIGS. 6, 7 and 8, the stator unit70is shown as having a stator support71by which the stator unit70is fixedly secured to the axle15. A yoke72is located on a circumferential surface of the stator support71and is configured to define a plurality of teeth75, with windings73thereon. The stator support71may be configured to support a printed circuit board74that will communicate with the control by wires passing through the channel18of the axle15, to control current circulation in the windings73.

Any appropriate number of teeth for magnets is considered. For instance inFIG. 8, there is illustrated the yoke of the stator support71as having eighty-four slots, separated by teeth75, typically made of iron (i.e., ferromagnetic material). Although not shown inFIG. 8(but show inFIG. 6), the coils of insulated wire are wound about at least some of the teeth75, in accordance with a phase interconnection described below.

The rotor unit60is mounted about the stator unit70, and is separated from the stator unit70by a suitable clearance gap. InFIG. 1, there is illustrated eighty-eight of the permanent magnets62, although eighty or ninety-two magnets may be used as well with the eighty-four slots of the stator unit70. Due to the large diameter of the machine10(and resulting lever arm effect), the magnets62may be significantly reduced in size as compared to standard machines. Hence, the high number of poles reduces the iron volume. By increasing the number of poles, the flux per pole during operation is reduced as compared with a machine producing a similar power output with a lesser amount of poles. Accordingly, as the sectional dimensions of teeth are proportional to the flux, the sectional dimensions for a eighty-four slot machine are smaller than the sectional dimensions for the teeth of a machine with fewer slots, for a similar power output. There results a lower weight for the eighty-four slot machine when compared to machines having a fewer amount of poles for a similar power output.

The configuration of eighty-four slots allows some form of repeatability in the phase structure. The repeatability is well suited to balance radial forces on the axle, thereby reducing the subharmonics which may cause vibrations. An example of a phase interconnection of the machine12is shown, for the embodiment with eighty-eight magnets62for the eighty-four slots. The teeth75are regrouped in four continuous sets of teeth per phase, as shown by sets A, B, and C. According to one embodiment, each set comprises seven consecutive teeth75. However, other arrangements of sets may also be used, for instance phases each consisting of a set of six and a set of eight consecutive teeth75. It is also considered to have other phase configurations, for instance with four sets of six consecutive teeth75, four sets of seven consecutive teeth75, and four sets of eight consecutive teeth75, as an example. Any appropriate number of consecutive teeth per set for a total of six sets may be used. By the arrangement of six sets of teeth with two sets per phase, it is observed that the four sets of a same phase are diametrically opposed in the stator unit70, as shown by lines A-A, B-B, and C-C. In the embodiment featuring seven consecutive teeth per set, the centers of the sets of a same phase are diametrically opposed. Accordingly, the magnetic forces to which are exposed the sets of teeth75operated in a same phase oppose each other and minimize their effect on the center of the stator unit70. With the 3-phase interconnection described above, the above-referred phase interconnections and components of the system ofFIG. 8may be off-the-shelf products.

In the embodiments of eighty-four slots and ninety-two magnets, the periodicity of the back EMF sinusoidal signal generated by the magnet is 2, so the teeth75are separated in two sets for each phase.

Although only shown schematically, the stator unit70has coils of insulated wire wound on the teeth75. There are two coils per slot, although other suitable configurations may be used as well in the machine12. Adjacent coils of a same set are typically wound in opposite directions.

The interconnection of phases and the coil winding may be any other appropriate alternative. For instance, there may be used a single coil per slot.

The 84-slot arrangement is relatively lightweight compared to machines with similar power output but with fewer poles, notably because of the substantial reduction of size of the magnets62. The 84-slot arrangement on the other hand has greater diameter than machines with fewer poles, whereby the resulting machine is well suited to be wheel-mounted, as bicycle wheels commonly have large diameters, for instance between 584 mm and 700 mm (e.g., ISO5775: ISO 622 (700C and 29po), ISO 584 (650B), ISO 559 (26po)). Even more specifically, the 84-slot arrangement is relatively narrower compared to machines with similar power output but with fewer poles, resulting in a machine that is well suited to be mounted in between regular spoke patterns of a bicycle, not affecting the ride comfort of the bicycle. In the direct-drive configuration on a bicycle, the rotor may be operatively connected to a freehub as mentioned and illustrated inFIGS. 1-7, such that pedaling actuation is transmitted to the rotor via the cassette on the freewheel. On the other hand, in the absence of a pedaling input, the freehub22allows idling of the cassette while the machine12may actuate the wheel. As an alternative, the direct-drive configuration may be used for the front wheel of a bicycle.

Referring toFIG. 9, there is illustrated an arrangement to ensure the precise positioning of sensors between the teeth75of the stator unit70. A receptacle76is fixedly lodged between the teeth75, the receptacle76being sized to accommodate a Hall effect sensor77or equivalent. The sensor77(a few of which are used but only one shown inFIG. 9) is connected to the printed circuit board74, for instance by way of a flexible strip78(e.g., copper strips). Hence, the receptacle76is structurally connected to the teeth75, and the sensor77may simply be inserted in the receptacle76to be aligned with the rotor unit60to measure the orientation of the rotor unit60relative to the stator unit70.

Hence, the structure of the machine12has a geometry sized and shaped to fit in the inner volume A defined by the spokes14. Conventional spoke arrangements can thus be used for the motorized wheel10, with standard-size spokes. The use of such standard-size long spokes may result in a more effective wheel construction (in terms of mass, strength, assembly and/or comfort) than wheels in which short spokes extend from the circumference of the motor to the rim of the wheel. This specific arrangement of machine12serving as a hub for the wheel10allows the use of a large diameter motor, with the sturdy construction of long spoke wheels. For instance, the arrangement show in the figures may have a ratio of maximum rotor radius to maximum rotor width of at least 10. The spokes14may connect to the structure of the machine12at a connection diameter ranging between 20 and 500 mm

Referring toFIG. 10, an alternative embodiment of the axle15is shown, in which channels90are defined in the outer surface of the axle15. The channels90represent a suitable configuration for wires91of the electronic components of the active components of the machine12to be routed out of the machine12to be connected to a battery and to a user interface, as commonly known and used for such machines. The configuration ofFIG. 10may increase the strength of the axle15and improve its waterproofness. An abutment92is also visible inFIG. 10, the abutment92cooperating with the walls of the dropouts to prevent rotation of the stator unit70relative to the frame of vehicle.