NL2016126B1

NL2016126B1 - Wheel comprising an in-wheel electric motor.

Info

Publication number: NL2016126B1
Application number: NL2016126A
Authority: NL
Inventors: Johannes Heinen Adrianus
Original assignee: E-Traction Europe B V
Priority date: 2016-01-20
Filing date: 2016-01-20
Publication date: 2017-07-25
Also published as: WO2017126963A1

Abstract

A wheel comprises an in-wheel electric motor. The electric motor comprising permanent magnets and electromagnets, wherein the permanent magnets and the electromagnets are placed in compartments of the wheel that are open to ingress and egress of the environment, and are coated with a hermetically sealing coating. The electromagnets may comprise a metal core and windings of a conducting wire, and the metal core may comprise layers of a ferrous metal. The hermetically sealing coating can be formed by applying a powder coating and curing the powder coating. The wheel can further comprising electronics placed in an electronics compartment that is open to ambient air and sealed off from water and dirt.

Description

Wheel comprising an in-wheel electric motor FIELD OF THE INVENTION

[01 ] The invention relates to awheel comprising an in-wheel electric motor, said electric motor comprising permanent magnets and electromagnets.

BACKGROUND OF THE INVENTION

[ 02 ] Wheels driven by an electric motor are known. The electric motor can be provided in the vehicle and drive the axis of the wheel to rotate the wheel. This requires the electric motor to be located in the vehicle. Another possibility is to position the electric motor in the wheel itself. Such wheels having an in-wheel electric motor are known as well. Part of the electric motor is generally coupled to the rim of the wheel, the rim carrying the tire of the wheel. Another part of the in-wheel electric motor is generally positioned centrally in the wheel and will constitute a non-rotating part of the wheel. The non-rotating part and part coupled to the rim are generally referred to as stator and rotor. The interaction between rotor and stator is magnetic; at least one of the rotor and stator comprising electromagnets. Their mutual distance should be small enough for the electric motor to be able to deliver enough power and torque to the wheel. On the other hand, their mutual distance should be large enough to be able to absorb mechanical impacts on the wheel. Contamination and water entering the wheel may cause damage to the various electrical and other components andean result in break-down of the electric wheel. Various solutions have been proposed, but they are all quite complicated.

SUMMARY OF THE INVENTION

[ 03 ] It is an objective of the invention to provide a wheel having an in-wheel electric motor that is insensitive to water from the environment.

[ 04 ] It is another or alternative objective of the invention to provide a wheel with an in-wheel electric motor can well withstand mechanical impact on the wheel when driving.

[ 05 ] It is yet another or alternative objective of the invention to provide a wheel with an in-wheel electric motor that is of a simple and economic design.

[ 06 ] It is yet another or alternative objective of the invention to provide an electric wheel for a more efficient and durable and clean solution for inner city transportation.

[ 07 ] At least one of the above objectives is achieved by a wheel comprising an in-wheel electric motor, said electric motor comprising permanent magnets and electromagnets, wherein the permanent magnets and the electromagnets are placed in compartments of the wheel that are open to ingress and egress of the environment, and are hermetically sealed from the environment, especially by plating or coating with a hermetically sealing coating.

[ 08 ] In an embodiment the hermetically sealing coating comprises electrostatically applied zinc.

[ 09 ] In an embodiment the electromagnets comprise a metal core and windings of a conducting wire.

[ 10 ] In an embodiment the metal core comprises layers of a ferrous metal.

[ 11 ] In an embodiment the hermetically sealing coating is formed by applying a powder coating, especially by electrostatically applying a powder coating, and curing the powder coating, especially at a high temperature, to achieve an optimal protective layer.

[ 12 ] In an embodiment the wheel of further comprises electronics placed in an electronics compartment that is open to ambient air and sealed off from water and dirt.

[ 13 ] In an embodiment the electronics compartment is provided with one or more filters that are permeable to air and impermeable to liquid water, especially permeable to water vapor in one direction and impermeable to liquidwater in an opposing direction.

[ 14 ] In an embodiment the electric motor comprises a rotor and a stator separated by an air gap having a width in the range of 1 to 5 mm, especially 1.6 mm to 3 mm in the absence of any mechanical impact on the wheel.

[ 15 ] In an embodiment the stator is mechanically configured such that any mechanical impact acting on the wheel during driving incidentally and locally reduces a width of the air gap to a value in the range of 0.5 mm to 1 mm.

[ 16 ] In an embodiment the permanent magnets are placed in the rotor.

[ 17 ] In an embodiment the rotor surrounds the stator.

[ 18 ] In an embodiment the rotor has a substantially cylindrical shape having a diameter and an axis, said rotor having an axle hub configured for mating with a shaft, especially a spline axle, in a form fixed connection.

[ 19 ] In an embodiment the axle hub has a length in the range of 30% to 75% of the length of the spline axle.

[ 20 ] In an embodiment a first end of the cylindrically shaped rotor is attached to the shaft, a bearing being provided at the first end of the rotor between rotor and stator, and characterized by the absence of a bearing between the cylindrical shape of the rotor and the stator at a second end of the rotor.

[ 21 ] In an embodiment the wheel is capable of bearing a weight of up to 6000 kilograms.

[ 22 ] In another embodiment a first end of the cylindrically shaped rotor is attached to the shaft, a bearing being provided at the first end of the rotor between rotor and stator, and characterized by another bearing provided between the cylindrical shape of the rotor and the stator at a second end of the rotor.

[ 23 ] In an embodiment the wheel is capable of bearing a weight of up to 12000 kilograms.

[ 24 ] In an embodiment the rotor comprises a first material, especially a first metal, having a magnetic permeability (μ) of at least 5.0x1 O'3 H nv1 at non-saturated conditions, and a second material, especially a second metal, having yield strength of at least 700 MPa.

[ 25 ] In an embodiment the permanent magnets are embedded in the first material.

[ 26 ] In an embodiment the second material surrounds the first material at an external perimeter.

[ 27 ] In an embodiment the wheel comprises interlocking components between rotor and stator.

[ 28 ] In an embodiment at least some of the interlocking components define a labyrinth for letting moisture ingress and egress between the permanent magnets and the electromagnets and keeping dirt out.

[ 29 ] In an embodiment the rim comprises a demountable rim flange.

[ 30 ] In an embodiment the demountable rim flange comprises a wedge-shaped flange element and a circular retainer element, the wedge-shaped element being configured for sliding onto the rim, and the rim comprising a retainer groove having an opening at a side of the retainer groove for receiving the retainer element so as to allow sliding the retainer element into the retainer groove, the retainer element retaining the flange element on the rim when the retainer element has been slid into the retainer groove.

BRIEF DESCRIPTION OF THE DRAWINGS

[ 31 ] Further features and advantages of the invention will become apparent from the description of the invention by way of non-limiting and non-exclusive embodiments. These embodiments are not to be construed as limiting the scope of protection. The person skilled in the art will realize that other alternatives and equivalent embodiments of the invention can be conceived and reduced to practice without departing from the scope of the present invention. Embodiments of the invention will be described with reference to the accompanying drawings, in which like or same reference symbols denote like, same or corresponding parts, and in which Figure 1 shows a wheel according to the invention;

Figure 2 shows the rotating part of the wheel of figure 1, without a shaft;

Figure 3 shows the static part of the wheel and the shaft of the rotating part;

Figure 4 shows the electromagnets of the electric motor of the wheel of figure 1;

Figure 5a and 5b shows details of the permanent magnets and electromagnets with a coating provided;

Figure 6 shows another embodiment of a wheel according to the invention:

Figure 7 shows an exploded view of the rim of the wheel shown in figures 1 and 6; and

Figure 8 shows details of a back plate of the wheel shown in figures 1 and 6. DETAILED DESCRIPTION OF EMBODIMENTS

[ 32 ] A wheel 10 for a vehicle, such as a car, bus or truck, is shown in figure 1 and comprises a rotating part 100 and a static part 200. An electric motor 12 is arranged inside the wheel to provide for an in-wheel electric motor. A tire 11 is mounted on a rim 120 of the wheel, the rim being fixedly attached to a shaft 130 through its integral front plate 121. The rim and shaft are rotating parts of the wheel in the embodiment shown.

[ 33 ] The electric motor comprises a rotor arranged on the rotating part 100 and a stator arranged on the static part 200. The rotor is provided with permanent magnets 110 as shown in more detail in figure 2, and the stator is provided with electromagnets 210, as shown in more detail in figure 3, that are shaped as coils 211 and layers of a ferrous metal 212 in the embodiment shown. A phase and direction of electrical currents through the electromagnets is controlled so as to provide forces between the electromagnets of the stator and permanent magnets of the rotorto induce rotation of the rotor with respect to the stator. Such techniques are generally known and will not be further explained in the present description. The rotating part 100 as a whole may be referred to as the rotor, and the static part 200 as a whole may be referred to as the stator. Bearings 13 are provided in between rotating part 100 and static part 200.

[ 34 ] The rotating part 100, excluding the shaft 130, is shown as an individual part in figure 2. The permanent magnets are mounted on a bushing 112. The material of the bushing 112 is selected for its good magnetic flux guiding properties. The permanent magnets 110 may be glued and/or mechanically fixed, such as by appropriate bolts, to the bushing. Since the bushing is selected for its magnetic flux guiding properties, the material of the rim can be selected for mechanical strength.

The bushing is mounted inside the rim by a press fitting. Additionally or alternatively, a glue can be applied for mounting the bushing 112 inside the rim 120. The bushing comprises a first material, especially a metal, having a magnetic permeability (μ) of at least 5.0x10'3 H nv1 at non-saturated conditions to provide for the appropriate magnetic flux guiding properties. The rim comprises a second material, especially a metal, having a yield strength of at least 700 MPa to provide for the required strength. The rotor therefore comprises both these first and second materials, especially first and second metals, to provide the appropriate flux guiding properties and mechanical strength. The permanent magnets are, at least partially, embedded in the first material, especially the first metal. The second material, especially the second metal, surrounds the first material at an external perimeter thereof.

[ 35 ] Figure 3 shows the static part 200 as an individual part, and the shaft 130 of the rotating 100. Electromagnets 210 are mounted on the outside of the stator 200. The electromagnets 210 comprise a metal core 212 and windings of a conducting wire 211a as shown in figure 4. The metal core 212 comprises layers of a ferrous metal.

[ 36 ] The static part 200 is mounted inside the rotating part 100 so that the rotor surrounds the stator, while leaving an air gap 14 between the permanent magnets 110 and electromagnets 210. The permanent and electromagnets 110, 210 and air gap 14 are placed in an open compartment 15 of the wheel 10. On its outside the open compartment is bounded by the rim 120, shaft 130, front plate 121 and a back plate 220. A gap 15a is present between the back plate 15 and the rim 120 so that the open compartment 15 is open to ingress and egress of the environment E outside the wheel. A labyrinth seal 15b is provided in the gap 15a provides a protection barrier against larger contamination, but is still open to moisture and water penetrating the labyrinth seal. The labyrinth seal 15b provides for interlocking components that define a labyrinth, at least some of the interlocking components defining a labyrinth for letting moister ingress and egress between the permanent magnets 110 and the electromagnets 210 and keeping dirt out. Even in case of a submergence of the wheel water can ingress in the air filled compartment 15 without damaging the components in the wheel itself. When the wheel is in dry circumstances again, centrifugal forces will sweep water inside the wheel to the outside environment E and the average temperature of the wheel, which internally of the wheel may be in the order of 50 to 60 degrees Celsius, will evaporate any remaining water.

[ 37 ] The electromagnets 210 and the permanent magnets 110 may be vulnerable to corrosion. Especially, neodymium permanent magnets 110 are extremely corrosion sensitive and will lose their magnetic capabilities when corroded. Both the electromagnets and the permanent magnets are therefore coated with a hermetically sealing coating or even a double hermetically sealing coating, as is shown in figures 5a and 5b. During manufacturing a powder coating is applied over the magnets, which is subsequently cured at the required temperature especially by baking at a high temperature, to yield the hermetically sealing coating over the magnets. A powder coating can be applied, for instance, using electrostatic means. Such a coating is extremely shock proof and can withstand high temperatures. An example is a coating of electrostatically applied zinc. The coating may further be applied on various parts, such as the windings, cables and the protecting material necessary to ensure electrical insulation of the electrical motor. The coating may generally be applied is a state of sub-assembling of the rotor and sub-assembling of the stator.

[ 38 ] The rotating part and rotor 100 has a substantially cylindrical shape with a diameter D and an axis A. The rotating part and rotor further have an axle hub 122 that is configured to mate with the shaft 130 in the form of a spline axle in a form fixed connection. Rim 120, front plate 121 and axle hub 122 are molded as one piece of material in the embodiment shown. The axle hub has a length L1 that is in the range of 30% to 75% of the length of the spline axle 130. At a first end the cylindrical shape is closed off by a front plate 121 as an extension of the rim 120 through which the substantially cylindrical rim is connected to the shaft or spline axle 130. Openings may be present in the front plate 121 that is part of the rotor or rotating part 100, so as to further allow for ingress and egress from the environment. At a second end of the cylindrical shaped rotor 100 a back plate 220 is provided, leaving an open connection between rotor 100 and back plate 220 as described earlier. The back plate is part of the static part or stator 200. A bearing is not provided and thus absent at the second end of the cylindrically shaped rotor between the rotor and stator, especially the back plate of the stator.

[ 39 ] An air gap in the range of 1 mm to 5 mm, especially 1.6 mm to 3 mm is present between the permanent magnets 110 of the rotor 100 and electromagnets 210 of the stator 200. The stator is mechanically configured such that any mechanical impact acting on the wheel during driving incidentally and locally may reduce the air gap to a value in the range of 0.1 mm to 3 mm, especially 0.5 mm to 1 mm in the absence of a bearing at the second end of the rotor between the rotor and the stator. The stator is configured such that the wheel is capable of bearing a weight up to 6,000 kilograms.

[ 40 ] An additional bearing 16, as shown in figure 6 may be provided at the second end of the cylindrically shaped rotor between the rotor and stator, especially the back plate of the stator. Awheel provided with such an additional bearing is capable of bearing a weight up to 12,000 kilograms.

[41 ] Figures 1 and 6 show that the rim has two rim flanges 123, 124 on either side of the tire 11. Rim flange 123 at the second side of the rotating part 100 is a fixed rim flange that is an integral part of the rim 120. The second side of the rotor 100 will in use be turned towards the vehicle on which the wheel is mounted. Rim flange 124 at the first side of the rotating part 100 is a separated part that can be mounted onto and demounted from the rim 120. To exchange a tire 11, the demountable rim flange 124 is taken off. Subsequently, the tire can be removed and a new tire mounted, after which the rim flange 124 is mounted onto the rim again. To this end the rim flange 124 comprises a wedge-shaped flange element 124.1, a resilient O-ring 124.2 and a sliding circular retainer element 124.3. The resilient O-ring 124.2 is inserted into a groove 125.1 provided in rim 120, after which the wedge-shaped flange element 124.1 is slid onto the rim 120 over O-ring 124.2. Subsequently, the sliding circular element 124.3 is inserted in an opening of retainer groove 125.3 and slid into the retainer groove until a thicker part 124.3a of the circular element 124.3 locks into the opening of retainer groove 125.2. The circular element 124.3 made from spring steel inserted into groove 125.3 retains the wedge-shaped flange element 124.1 in place. After mounting and inflation, the tire 11 presses against the wedge-shaped flange element 124.1 and circular element 124.3 to safely keep these elements in place. The O-ring 124.2 acts as a seal in between flange element 124.1 and rim 120.

[ 42 ] It is further shown in figures 1 and 6 that electronics 240 for driving and controlling the electric motor 12 is placed in an electronics compartment 230 of the static part 200. The back plate 220 closes off the electronics compartment 230 such that the compartment is not exposed to water and dirt from the outside environmentE. Mounting holes 222 are provided in the back plate 220 to provide for a connection between the electronics compartment and the outside environment, and a filter 223 is mounted on or within each mounting hole 222. The filter 223 comprises a membrane that is not permeable to liquid water, but is permeable to water vapor in a direction from the electronics compartment to the outside environment. Such membrane filter is, for instance, available under the trade name GORE-TEX. Any water that may have entered the electronics compartment is thus allowed to escape from the electronics compartment 230, especially when the temperature and therefore pressure rises in the electronics compartment rises during operation. In operation of the electric motor the temperature of the electronics 240 will increase. When the electronics cools down again after use of the electric motor 12, air without water vapor is allowed to enter the compartment 230 through the channel elements 222 with filters 223. The hole 222 with filters 223 allow the electronics compartment 230 to “breath”.

Claims

A wheel (10) comprising an in-wheel motor (12), which electric motor comprises permanent magnets (110) and electromagnets (210), wherein the permanent magnets and the electromagnets are placed in compartments of the wheel that are open to entry and exit from the environment, and hermetically sealed from the environment, in particular by plating or coating with a hermetically sealing coating.

The wheel of claim 1, wherein the hermetically sealing coating comprises electrostatically applied zinc.

The wheel of claim 2, wherein the electromagnets comprise a metal core and turns of a conductive wire.

The wheel of claim 3, wherein the metal core comprises layers of a ferrous metal.

The wheel according to one or more of the preceding claims, wherein the hermetically sealing coating is formed by applying a powder, in particular by electrostatically applying a powder coating, and curing the powder coating, in particular by baking on a high temperature.

The wheel of any one of the preceding claims, further comprising electronics (240) disposed in an electronics compartment (230) that is open to ambient air and sealed from water and dirt.

The wheel of claim 6, wherein the electronics compartment (230) is provided with one or more filters (223) that are permeable to air and impermeable to liquid water, in particular permeable to water vapor in one direction and impermeable to liquid water in a opposite direction.

The wheel according to one or more of the preceding claims, wherein the electric motor comprises a rotor and a stator separated by an air gap with a width in the range of 1 mm to 5 mm, in particular 1.6 mm to 3 mm in the absence of mechanical stress on the wheel.

The wheel of claim 8, wherein the stator is mechanically configured such that a mechanical impact that acts on the wheel while driving occasionally and locally reduces a width of the air gap to a value in the range of 0.1 mm to 3 mm , in particular 0.5 mm to 1 mm.

The wheel according to claim 8 or 9, wherein the permanent magnets are placed in the rotor.

The wheel according to one or more of claims 8-10, wherein the rotor surrounds the stator.

The wheel of claim 11, wherein the rotor (100) has a substantially cylindrical shape with a diameter (D) and a shaft (A), which rotor has a shaft stub (122) configured to suitably engage with a shaft, in particular a key shaft (130), in a form-retaining connection.

The wheel of claim 12, wherein the axle stub (122) has a length in the range of 30% to 75% of the length of the key axis (130).

The wheel according to claim 12 or 13, wherein a first end of the cylindrically shaped rotor (100) is connected to the shaft (130), a bearing (13) is provided at the first end of the rotor between rotor and stator ( 200), and characterized by the absence of a bearing between the cylindrical shape of the rotor and the stator at a second end of the rotor.

The wheel of claim 14, capable of supporting a weight of up to 6000 kilograms.

The wheel of claim 12 or 13, wherein a first end of the cylindrically shaped rotor (100) is connected to the shaft (130), a bearing (13) is provided at the first end of the rotor between rotor and stator ( 200), and characterized by another bearing (16) provided between the cylindrical shape of the rotor and the stator at a second end of the rotor.

The wheel of claim 16, capable of supporting a weight of up to 12,000 kilograms.

The wheel according to one or more of claims 10 to 15, wherein the rotor comprises a first material, in particular a first metal, with a magnetic permeability (μ) of at least 5.0 x 10'3 H rrr1, and a second material, in particular a second metal, with a strain strength of 700 MPa.

The wheel of claim 16, wherein the permanent magnets are embedded in the first material.

The wheel of claim 16 or 17, wherein the second material surrounds the first material at an external perimeter.

The wheel according to one or more of the preceding claims, comprising interlocking components between rotor and stator.

The wheel of claim 21, wherein at least some of the interlocking components define a labyrinth for allowing moisture to enter and exit between the permanent magnets (110) and the electromagnets (210) and keep dirt out.

The wheel of any one of the preceding claims, wherein the rim (120) comprises a demountable rim rim (124).

The wheel of the preceding claim, wherein the demountable rim edge (124) comprises a wedge-shaped flange element (124.1) and a circular retaining element (124.3), which wedge-shaped element is configured for sliding on the rim, and the rim (120) comprises a retaining groove (125.2) having an opening on one side of the retaining groove for receiving the retaining element to allow sliding of the retaining element into the retaining groove, which retaining element holds the flange element on the rim when the retaining element is slid into the retaining groove.