Patent Description:
In the prior art, the idea of integrating an electric motor on a wheel of a motor vehicle has been explored on numerous occasions.

The integration of an electric motor on a wheel renders the use of transmissions superfluous, which renders the motor vehicle more efficient.

Positioning an electric motor in a wheel allows the interior space of the motor vehicle to be increased significantly in favour of passengers and baggage. Moreover, an appropriate suspension system enables a better control of pitch and roll motions during transient events.

On the other hand, the complexity of the wheel increases with an increase in the number of necessary components
together with the related costs.

Examples of complex known wheel devices, which could be difficult to be inspected and efficiently cooled are disclosed in <CIT>, <CIT>, and <CIT>.

Therefore, there is a need to provide wheel devices with an integrated electric motor that constitute alternatives to those already known and are more specifically simplified, for example by reducing the number of components and/or mechanical connections, without sacrificing performance, efficiency, or reliability.

Moreover, there is a need to provide wheel devices with an integrated electric motor that allow a simple tyre change or a simple removal of the rim, in particular without necessarily also having to remove the electric motor.

An object of the invention is to satisfy at least one of the needs set forth above, preferably in a simple and cost-effective manner.

The object is achieved by a wheel device as defined in claim <NUM>.

The dependent claims define particular embodiments of the invention.

In the following, an embodiment of the invention is described for a better understanding of the same by way of a non-limiting example and with reference to the accompanying drawings, wherein:.

In <FIG>, the reference number <NUM> is used to indicate, as a whole, a motor vehicle.

The motor vehicle <NUM> comprises a body <NUM>, which in turn includes a chassis that is not illustrated and a shell <NUM> carried by the chassis and defining the external surfaces of motor vehicle <NUM>.

Moreover, the motor vehicle <NUM> comprises a plurality of wheels or wheel devices <NUM>, of which only two are illustrated in <FIG>. The wheels <NUM> are coupled to the body <NUM> or more precisely to the chassis via suspensions that are not illustrated.

The wheels <NUM> define the non-suspended mass of the motor vehicle <NUM>. The suspensions suspend the body <NUM> or more precisely the chassis relative to the wheels <NUM>, so that the body <NUM> forms part of the suspended mass of the motor vehicle <NUM>.

The wheels <NUM> have similar characteristics to one another, with the possible exception of their dimensions, so that only one of the wheels <NUM> will be described in greater detail, it being understood that the characteristics described for one of the wheels <NUM> will also be applicable to the others.

The wheel <NUM> comprises a rim <NUM> having in particular a tubular geometry. The rim <NUM> has an axis H, around which the rim <NUM> extends, thus defining a solid of revolution.

The axis H is transversal to a direction of travel of the motor vehicle <NUM>.

The rim <NUM> also has an outer surface <NUM> extending around the axis H, thus defining a surface of revolution.

The outer surface <NUM> defines a seat or channel <NUM> configured to receive a tyre <NUM> of the wheel <NUM>. The tyre <NUM> is fitted on the rim <NUM> at the seat <NUM>, in particular according to typical procedures.

In other words, the seat <NUM> allows the fitting of the tyre <NUM>.

Moreover, the wheel <NUM> comprises a wheel hub <NUM>, an electric motor <NUM> with a stator <NUM> fixed relative to the wheel hub <NUM> and a rotor <NUM> fixed relative to the rim <NUM>, and at least one radial bearing <NUM> supporting the rotor <NUM> and thus the rim <NUM> on the wheel hub <NUM> in a rotary manner around the axis H relative to the wheel hub <NUM> and consequently to the stator <NUM>.

The wheel hub <NUM> is arranged around the axis H inside the rim <NUM>. In other words, the wheel hub <NUM> is coaxial to the rim. The wheel hub <NUM> is coupled to one of the suspensions of the motor vehicle <NUM>. Consequently, the body <NUM> is suspended relative to the wheel hub <NUM> by means of the latter suspension.

The stator <NUM> is coaxial or arranged coaxially to the wheel hub <NUM>. In particular, the stator <NUM> is radially outer than the wheel hub <NUM>. More specifically, the stator <NUM> is fitted directly on the wheel hub <NUM>.

Thus, the wheel hub <NUM> is or defines a stator support. In practice, the term wheel hub is exchangeable with stator support in this description.

The rotor <NUM> is configured to interact magnetically with the stator <NUM>, as is normally the case according to the prior art. In fact, the magnetic interaction between the rotor <NUM> and the stator <NUM> allows the rotor <NUM> to rotate relative to the stator <NUM> around the axis H.

The electric motor <NUM> in this particular case is an AC motor, more specifically an, in particular brushless, permanent magnet synchronous motor.

More specifically, the rotor <NUM> comprises a portion <NUM> coaxial or arranged coaxially to the stator <NUM> and arranged in a radially outer position relative to the stator <NUM>.

In particular, the stator <NUM> is at least partially arranged inside the portion <NUM>. In fact, the portion <NUM> has an annular shape and thus defines a rotor ring around the axis H. The stator <NUM> is at least partially inside the ring or covered by the ring radially.

The portion <NUM> or possibly another portion of the rotor <NUM> comprises one or more permanent magnets or polar pairs configured to generate a magnetic flux, specifically directed radially towards the stator <NUM> or the axis H.

The stator <NUM> comprises electric windings <NUM> configured to generate a magnetic field in response to a flow of electric current through the windings <NUM>. In other words, the electric windings <NUM> can be connected to an electric power source, such as a car battery of the motor vehicle <NUM>, in order to be supplied with electric current. The supply of electric current causes the generation of the magnetic field.

The magnetic field interacts with the magnetic flux generated by the permanent magnets of the rotor. The magnetic interaction between the magnetic flux and the magnetic field triggers the relative rotation of the rotor <NUM> relative to the stator <NUM>.

Conversely, as is well known in the technical field of electric motors, should the rotor <NUM> be brought into rotation by other causes than magnetic interaction, the electric motor <NUM> could act as an electric generator.

Conveniently, the power supply of the electric windings <NUM> can be actively controlled by means of a designated control unit of the motor vehicle <NUM> or of the wheel <NUM>. The behaviour of the electric motor <NUM> as a motor or generator is thus fully controllable by means of the control unit.

The wheel <NUM> comprises a flange 5a fixed relative to the rim <NUM> and arranged inside the rim <NUM> in a radially projecting manner relative to the rim <NUM> towards said axis H,.

In other words, as can be derived directly and unequivocally from the figures, the flange 5a protrudes radially from the rim <NUM> towards the axis H.

Moreover, as can be derived directly and unequivocally from the figures, the rim <NUM> is preferably a single piece, i.e. it does not consist of a plurality of interconnected pieces. This is advantageous in that it renders possible a potential replacement or handling or balancing of the pressurized tyre <NUM> even after a removal of the rim <NUM> from the motor <NUM>.

According to the invention, the wheel <NUM> comprises fixing members <NUM> to fix the rotor <NUM> to the flange 5a, so that the flange 5a is fixed to the rotor <NUM> by means of the fixing members <NUM>. Consequently, the rim <NUM> is fixed relative to the rotor <NUM>. A rotation of the rotor <NUM> around the axis H is thus directly transmitted to the rim <NUM>.

In other words, the fixing members <NUM> fix the flange 5a to the rotor <NUM>, in particular directly.

The fixing members <NUM> are releasable or detachable, in the sense that the flange 5a can be separated from the rotor <NUM> by releasing the fixing members <NUM>, without the flange 5a or the rotor <NUM> suffering any damage that could potentially compromise their operability.

More specifically, the fixing members <NUM> comprise a plurality of threaded elements <NUM>, such as screws or pins, and corresponding holes on the flange 5a and on the rotor <NUM> that allow a fixation between the flange 5a and the rotor <NUM> by means of the threaded elements <NUM>.

In particular the threaded elements <NUM> and the holes extend parallel to the axis H through the flange 5a and the rotor <NUM>.

The threaded elements <NUM> and the holes are distributed circumferentially around the axis H.

More specifically, the holes on the flange 5a are through-holes while the corresponding holes on the rotor <NUM> are, for example, blind.

Moreover, for example, the holes on the flange 5a are plain holes, while the corresponding holes on the rotor <NUM> are specifically threaded to allow screwing of the threaded elements <NUM>. The screwing into the holes on the rotor <NUM> through the holes on the flange 5a in turn causes the fixation of the flange 5a to the rotor <NUM>, for example by means of specific heads <NUM> of the threaded elements <NUM>.

Preferably, the flange 5a protrudes directly from the rim <NUM>. In particular, the flange 5a is made of one piece with the rim <NUM>.

In the illustrated embodiment, the rotor <NUM> comprises a portion or casing <NUM> defining a housing accommodating the stator <NUM> and in particular also the portion <NUM>; the latter is fixed relative to the portion <NUM> and arranged radially inside the portion <NUM>.

Specifically, the portion <NUM> has a bell shape.

The portion <NUM> comprises an outer surface 15a extending around the axis H. The outer surface 15a directly faces an inner surface <NUM> of the rim <NUM>.

The inner surface <NUM> faces radially towards the axis H.

Preferably, the outer surface 15a is spaced apart or separated from the inner surface <NUM>. However, this is not strictly necessary; the outer surface 15a could also be in contact with the inner surface <NUM>.

In other words, the rotor <NUM> or the portion <NUM> might be in mutual contact with the rim <NUM>.

The rim <NUM> might comprise a portion arranged in contact with the rotor <NUM>, provided that the latter portion comprises a polymer or elastomer, for example a rubber, in particular a vulcanized rubber, instead of being, for example, entirely made of metal.

In other words, the portion of the rim <NUM> comprising the polymer or the elastomer would include the inner surface <NUM>.

Thus, the interference or the mutual contact between the rotor <NUM> and the rim <NUM> can occur between two respective metal materials (metal-to-metal contact) or between a metal material and a polymer or elastomer (metal-polymer/elastomer contact), or even between materials not entirely made of metal, without losing generality.

The rim <NUM>, as well as the rotor <NUM>, could be made of a single piece or comprise a plurality of portions fixed or attached to one another, without losing generality.

Moreover, in particular, the portion <NUM> comprises a radial wall <NUM> extending transversely or more precisely orthogonally to the axis H.

More specifically, the radial wall <NUM> has a radially inner end 16a arranged in a radially inner position relative to the stator <NUM>.

The end 16a defines an axial hole <NUM> around the axis H.

Moreover, the radial wall <NUM> has two faces 16b, 16c transversal or more precisely orthogonal to the axis H and opposite one another according to the axis H.

The face 16b faces the housing defined by the portion <NUM> or contributes to the definition of said housing, while the face 16c faces the flange 5a. In particular, the face 16c directly faces the flange 5a and is more specifically in contact with it.

The fixing members <NUM> fix the flange 5a to the rotor <NUM> at the radial wall <NUM>. Thus, the holes on the rotor <NUM> of the fixing members <NUM> are more precisely obtained on the radial wall <NUM>.

The wheel hub <NUM> comprises a portion <NUM> arranged inside the housing defined by the portion <NUM>, as well as a portion <NUM> extending through the axial hole <NUM> along the axis H.

The stator <NUM> is carried by the wheel hub <NUM> at the portion <NUM>. The portion <NUM> is coaxial to the ring defined by the portion <NUM> and is arranged radially inside the same ring.

The portion <NUM> is arranged in an inner radial position relative to the fixing members <NUM>.

Moreover, in particular, the stator <NUM> is arranged in an inner radial position relative to the fixing members <NUM>.

The radial bearing <NUM> comprises an inner ring <NUM>, an outer ring <NUM>, and rolling bodies <NUM> arranged radially between the inner ring <NUM> and the outer ring <NUM>.

In particular, the rolling bodies <NUM> are defined by balls, more specifically by two crowns of balls.

Specifically, the radial bearing <NUM> is an angular contact bearing, so that it supports axial and radial loads. The type of fitting of the radial bearing <NUM> is not described in detail but can be a fitting with the axes of the balls being incident inside the radial bearing <NUM> (X fitting) or outside the radial bearing <NUM> (O fitting).

The outer ring <NUM> is arranged around the axis H and is fixed relative to the rotor <NUM>. More precisely, the outer ring <NUM> is fixed to the rotor <NUM> at the end 16a or at the radial wall <NUM> inside the axial hole <NUM>.

Thus, the radial bearing <NUM> supports the radial wall <NUM> of the rotor <NUM>.

The inner ring <NUM> is arranged around the axis H and is fixed relative to the wheel hub <NUM>. More precisely, the inner ring <NUM> is fixed to the wheel hub <NUM> at the portion <NUM> inside the axial hole <NUM>.

The inner ring <NUM> is radially more outward relative to the portion <NUM>, while the outer ring <NUM> is radially more inward relative to the end 16a or the radial wall <NUM>.

Thus, the outer ring <NUM> rotates around the axis H relative to the inner ring <NUM>, which is fixed relative to the wheel hub <NUM>.

Here, the wheel hub <NUM>, which is understood as the central or radially innermost element of the wheel <NUM>, is not rotatable about the axis H and is rather more specifically fixed relative to the axis H.

It is thus evident that the wheel hub <NUM> is the stator support.

The wheel <NUM> comprises a brake disc <NUM> carried by the rotor <NUM>, in particular at the radial wall <NUM>, in a fixed position relative to the rotor <NUM>.

The brake disc <NUM> is fixed to the rotor <NUM>, specifically at the radial wall <NUM>, via the fixing members <NUM>.

The brake disc <NUM> is arranged outside the housing defined by the portion <NUM>.

Moreover, the brake disc <NUM> is arranged in a radially inner position relative to the fixing members <NUM>.

The flange 5a is arranged between the rotor <NUM> and the brake disc <NUM> according to the axis H.

In other words, the brake disc <NUM> and the rotor <NUM> are arranged on opposite sides of the flange 5a according to the axis H.

In still other words, the brake disc <NUM> is axially outer than the flange 5a and to the rotor <NUM>. The term axially outer is understood with reference to the motor vehicle <NUM> and to the axis H.

Thus, the brake disc <NUM> faces towards the outside of the motor vehicle <NUM> according to the axis H and is arranged in front of the flange 5a and the rotor <NUM> or downstream of the flange 5a and the rotor <NUM>, moving from the interior towards the exterior of the motor vehicle <NUM> according to the axis H.

Thus, to summarize, the fixing members <NUM> fix both the brake disc <NUM> and the rotor <NUM> to the flange 5a in respective positions so that the flange 5a is arranged axially (i.e. according to the axis H) between the rotor <NUM> and the brake disc <NUM>, i.e. so that the brake disc <NUM> is axially outer than the flange 5a and to the rotor <NUM>, with the flange 5a axially outer than the rotor <NUM>.

Specifically, the wheel <NUM> comprises a spacer plate <NUM> arranged axially between the rotor <NUM> and the brake disc <NUM>. The spacer plate <NUM> is fixed to both the rotor <NUM> and the brake disc <NUM>.

Clearly, as can be derived from the figures, the spacer plate <NUM> keeps the brake disc <NUM> axially at a distance from the flange 5a and from the rotor <NUM>.

In particular, the fixing members <NUM> fix the spacer plate <NUM> to the flange 5a, more specifically directly. In fact, the fixing members <NUM> comprise corresponding holes on the spacer plate <NUM> which the fixing members <NUM> pass through.

In other words, the flange 5a is sandwiched between the spacer plate <NUM> and the radial wall <NUM> or the rotor <NUM>.

Thus, in particular, the brake disc <NUM> is fixed relative to the rotor <NUM>, also axially.

As can also be derived from the figures, the fixing members <NUM> fix together, in a releasable manner, the brake disc <NUM>, the rotor <NUM>, and the flange 5a belonging to a portion of the rim <NUM>, where the portion is made of a single piece, so that the fixing members <NUM> pass through a single piece of the rim <NUM> and, at the same time, the spacer plate <NUM> or directly the brake disc <NUM>, in cases where the spacer plate <NUM> is absent, or more generally a support fixed relative to the brake disc <NUM> and supporting the brake disc <NUM>.

The fixing elements <NUM> only pass through the single piece, i.e. they do not pass through separate, interconnected portions of the rim <NUM>.

Moreover, preferably, the wheel <NUM> comprises a brake calliper device <NUM>. The device <NUM> is configured to co-operate in contact with the brake disc <NUM> in a selective manner. In other words, the device <NUM> can be controlled to grasp the brake disc <NUM>, thus exerting a braking action on the rotor <NUM> by sliding friction, and to release the brake disc <NUM>, thus ceasing to exert the braking action.

Thus, the device <NUM> and the brake disc <NUM> form part of a braking device of the wheel <NUM>. Here, in this particular case, the braking device is suitable for emergency use or to provide a parking brake or for use as an auxiliary braking device.

In fact, the electric motor <NUM> can be employed as a brake when it operates as an electric generator.

The device <NUM> is carried by the wheel hub <NUM>. In other words, the device <NUM> has at least one element <NUM> that is fixed relative to the wheel hub <NUM>.

In particular, the device <NUM> comprises at least one portion <NUM> (<FIG>) extending inside the inner ring <NUM>.

Conveniently, the wheel <NUM> comprises a cover <NUM> fixed to the front of the rim <NUM>, for example by means of a form-fit coupling or via threaded means.

The cover <NUM> is fixed to the rim <NUM> in a releasable or detachable manner, in the sense that the separation of the cover <NUM> from the rim <NUM> can occur without causing damage to the cover <NUM> or to the rim <NUM>.

In other words, the cover <NUM> is optional and removable.

The flange 5a is arranged between the rotor <NUM> or the radial wall <NUM> and the cover <NUM>.

An empty volume or chamber is provided between the cover <NUM> and the flange 5a or more precisely the fixing members <NUM>, so that the fixing members <NUM> are accessible to an operator from outside the rim once the cover <NUM> has been removed.

Thus, the cover <NUM> covers an opening <NUM> (<FIG>) of the rim <NUM>; the opening <NUM> is defined by the rim <NUM> transversely or more precisely orthogonally to the axis H.

The fixing members <NUM> are accessible by an operator via the opening <NUM> through the empty volume or chamber. In other words, the fixing members <NUM> are in communication with the opening <NUM>.

Implicitly, also the brake disc <NUM> is in communication with the opening <NUM>. Moreover, the brake disc <NUM> is accessible by the operator via the opening <NUM> and is located in the empty volume or chamber.

Preferably, the wheel <NUM> comprises one or more sensors coupled to the rotor <NUM> or more precisely to the portion <NUM> and configured to detect one or more quantities indicative of a force and/or a moment acting on the rim <NUM> and consequently on the rotor <NUM>.

The force or the moment can have a plurality of force or moment components in three-dimensional space, so that the quantities can be respectively indicative of force or moment components.

For example, the sensors can be strain gauges fixed, in particular directly fixed, to the rotor <NUM> or more precisely to the portion <NUM>.

The advantages of the wheel <NUM> according to the invention are evident from the foregoing.

The wheel <NUM> integrates an electric motor <NUM> in a simple, effective and efficient manner.

The rotor <NUM> is integral with the rim <NUM> via the fixation of the flange 5a to the rotor <NUM>; this type of fixation makes it possible not to use gearmotors.

The wheel <NUM> is thus readily manufacturable and reliable.

Moreover, the fixation is readily releasable without involving the removal of the electric motor <NUM>. It is thus possible to separate the electric motor <NUM> from the rim <NUM>. This makes it possible to change the tyre <NUM>, for example, in a very simple manner.

The flange 5a is located outside the housing defined by the portion <NUM>, so that access to the fixing members <NUM> is convenient for the operator.

Moreover, the sensors would allow the direct acquisition of information directly indicative of the force and/or moment acting on the rim <NUM> and useful for controlling the dynamics of the motor vehicle <NUM>. These sensors are more accurate and sensitive than estimates based on indirect measurements of the force and/or moment acting on the rim <NUM>.

Finally, it is clear that the wheel <NUM> according to the invention can be modified and varied without, however, departing from the scope of protection defined by the claims.

In particular, each of the details included in the figures is independent of the other details and is specifically conceived to resolve specific technical issues in isolation from the other details.

In particular, the details mentioned include each of the arrangements of the various components illustrated in relation to the other components.

Claim 1:
A wheel device (<NUM>) for a motor vehicle (<NUM>), the device (<NUM>) comprising:
- a rim (<NUM>) having an axis (H) and an outer surface (<NUM>) defining a seat (<NUM>) for fitting a tyre (<NUM>),
- a wheel hub (<NUM>) arranged around the axis (H) inside the rim (<NUM>) and suited to be coupled to a suspension of the motor vehicle (<NUM>),
- an electric motor (<NUM>) comprising a stator (<NUM>) arranged coaxially to the wheel hub (<NUM>) in a fixed position relative to the wheel hub (<NUM>) and a rotor (<NUM>) configured to magnetically interact with the stator (<NUM>),
- a radial bearing (<NUM>) supporting the rotor (<NUM>) in a rotary manner around said axis (H) relative to the wheel hub (<NUM>) and to the stator (<NUM>), and
- a flange (5a) fixed relative to the rim (<NUM>) and arranged inside the rim (<NUM>) in a radially projecting manner relative to the rim (<NUM>) towards said axis (H),
the device further comprising releasable fixing means to fix the rotor (<NUM>) to the flange (5a), so that the flange (5a) is fixed to the rotor (<NUM>) by means of said releasable fixing means, and a brake disc (<NUM>) fixed to the rotor (<NUM>) by means of said releasable fixing means, characterized in that the flange (5a) is arranged between the rotor (<NUM>) and the brake disc (<NUM>) according to said axis (H).