Wheel device having built-in electric motor for automobile

Abstract

To provide a simplified built-in electric motor on a wheel device.SOLUTION: A wheel device for an automobile includes: a rim 5 having an axis and an outer surface 6 for defining a seat part 7 on which a tire is mounted; a wheel hub 9 which is arranged around the axis inside the rim 5 and is suitable for being coupled to a suspension of the automobile; an electric motor 10 having a stator 11 which is arranged coaxially with the wheel hub 9 at a fixed position relative to the wheel hub 9, and rotors 14 and 15 configured to magnetically interact with the stator 11; and a radial bearing for supporting the rotors 14 and 15 so as to be rotatable around the axis relative to the wheel 9 and the stator 11, wherein the rim 5 is interfered with and mounted on the rotors 14 and 15, thereby the rim 5 is fixed to the rotors 14 and 15.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] [Cross - reference to related patent applications] This patent application claims the priority of Italian Patent Application No. 102022000008270 filed on April 27, 2022, the content of which is incorporated herein by reference.

[0002] The present invention relates particularly to a wheel device for a sports - type motor vehicle, or more simply to a wheel.

Background Art

[0003] In the art, the idea of integrating an electric motor into the wheels of a motor vehicle has been considered several times.

[0004] Integrating an electric motor into the wheel eliminates the use of a transmission and makes the vehicle more efficient.

[0005] Placing an electric motor inside the wheel allows for a significant increase in the interior space of the vehicle, benefiting passengers and cargo. Furthermore, an appropriate suspension system enables better control of pitching and rolling movements during transient phenomena.

[0006] On the other hand, the complexity of the wheel increases with the relative increase in cost and the number of necessary components.

Summary of the Invention

Problems to be Solved by the Invention

[0007] Therefore, there is a recognized need for an alternative to what is already known, and more specifically for a simplified integrated electric motor provided in a wheel device, for example by reducing the number of components and / or mechanical connections, without sacrificing performance, efficiency, or reliability.

[0008] The object of the present invention is to meet the above requirements, preferably in a simple and cost - effective way. [Means for solving the problem]

[0009] This objective is achieved by the wheel device described in claim 1.

[0010] The dependent claims define specific embodiments of the present invention. [Brief explanation of the drawing]

[0011] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings as non-limiting examples for a better understanding thereof. [Figure 1] This is a perspective view of a vehicle equipped with a wheel system according to the present invention. [Figure 2] This is a cross-sectional view of a wheel assembly, with respect to a plane perpendicular to the axle of the wheel assembly. [Figure 3] This is an exploded view of the wheel assembly. [Figure 4] This is a cross-sectional view of a wheel assembly. [Figure 5] This is a cross-sectional view of the wheel assembly relating to the section identified in Figure 2 by the section line VV. [Modes for carrying out the invention]

[0012] In Figure 1, reference numeral 1 is used to indicate the automobile as a whole.

[0013] Automobile 1 comprises a main body 2, which in turn includes a frame (not shown) and a vehicle body 3 supported by the frame and defining the outer surface of automobile 1.

[0014] Furthermore, the automobile 1 is equipped with multiple wheels or wheel sets 4, of which only two are shown in Figure 1. The wheels 4 are connected to the body 2 or more precisely to the frame by suspensions, which are not shown.

[0015] Wheel 4 defines the unsprung mass of motor vehicle 1. The suspension suspends the body 2, more precisely the frame, relative to the wheel 4, whereby the body 2 is part of the sprung mass of motor vehicle 1.

[0016] Since wheels 4 have similar characteristics to one another, except for some exceptions such as dimensions, only one of wheels 4 will be described in more detail. However, it should be noted that the characteristics described for one of wheels 4 are also applicable to the other.

[0017] Wheel 4 comprises a rim 5 having, in particular, a tubular shape. Rim 5 has an axis H around which rim 5 extends and thus defines a solid of revolution.

[0018] Axis H is transverse to the direction of travel of motor vehicle 1.

[0019] Rim 5 further has an outer face 6 extending around axis H and thus defines a surface of revolution.

[0020] Outer face 6 defines a seat or channel 7 configured to receive tire 8 of wheel 4. Tire 8 is attached to rim 5 at seat 7, in particular according to a typical manner.

[0021] In other words, seat 7 enables the attachment of tire 8.

[0022] Furthermore, wheel 4 comprises a wheel hub 9, an electric motor 10 having a stator 11 fixed to wheel hub 9 and a rotor 12 fixed to rim 5, and at least one radial bearing 13 that supports rotor 12, and thus rim 5 on wheel hub 9, rotatably about axis H relative to wheel hub 9, and thus stator 11.

[0023] The wheel hub 9 is arranged around the axis H within the rim 5. In other words, the wheel hub 9 is coaxial with the rim. The wheel hub 9 is coupled to one of the suspensions of the motor vehicle 1. Thus, the body 2 is suspended with respect to the wheel hub 9 by the latter suspension.

[0024] The stator 11 is coaxial with or arranged coaxially with the wheel hub 9. In particular, the stator 11 is radially outside of the wheel hub 9. More specifically, the stator 11 is directly attached to the wheel hub 9.

[0025] Thus, the wheel hub 9 is a stator support or defines a stator support. In fact, the term "wheel hub" is possible anywhere as long as it is a place where the stator support can be replaced.

[0026] The rotor 12 is configured to interact magnetically with the stator 11 as in the normal case according to the prior art. In fact, the magnetic interaction between the rotor 12 and the stator 11 enables the rotor 12 to rotate about the axis H with respect to the stator 11.

[0027] In such a case, the electric motor 10 is an AC motor, more specifically a permanent magnet synchronous motor, particularly brushless.

[0028] More specifically, the rotor 12 is coaxial with or arranged coaxially with the stator 11 and includes a portion that is arranged at a radially outer position with respect to the stator 11.

[0029] In particular, the stator 11 is at least partially arranged within the portion 14. In fact, the portion 14 has an annular shape and thus defines a rotary ring around the axis H. The stator 11 is at least partially inside the ring or is radially covered by the ring.

[0030] A portion 14 of the rotor 12, or optionally another portion, comprises one or more permanent magnets or polarity pairs configured to generate a magnetic flux directed radially toward the stator 11 or axis H.

[0031] The stator 11 includes an electric winding 30, which is configured to generate a magnetic field in response to the flow of current through it. In other words, the electric winding 30 may be connected to a power source to be powered by electric current, for example, the battery of a car 1. The power supply generates a magnetic field.

[0032] The magnetic field interacts with the magnetic flux generated by the permanent magnets of the rotor 12. The magnetic interaction between the magnetic flux and the magnetic field triggers the relative rotation of the rotor 12 with respect to the stator 11.

[0033] Conversely, as is well known in the field of electric motor technology, if the rotor 12 is rotated by a cause other than magnetic interaction, the electric motor 10 can behave as a generator.

[0034] Conveniently, the power supply to the electric winding 30 can be actively controlled by a special control unit in the automobile 1 or wheel 4. In this way, the behavior of the electric motor 10 as a motor generator is fully controllable by the control unit.

[0035] According to the present invention, the rim 5 is attached to the rotor 12 by interference, that is, by bringing the rim 5 and the rotor 12 into contact with each other, so that the rim 5 is fixed to the rotor 12. The rotation of the rotor 12 about the axis H is then directly transmitted to the rim 5.

[0036] Therefore, the rim 5 is in contact with the rotor 12 in the interference zone, and the rotor 12 is coupled to the rim 5 either by interference or through interference.

[0037] Preferably, as can be inferred from the figure, the interference zone between the rim 5 and the rotor 12 is radially aligned with the radial bearing 13.

[0038] In fact, as can be directly and uniquely derived from Figure 2, the rim 5 preferably has a tapered portion toward the H axis in the interference zone. In other words, the tapered portion is coupled to the rotor 12 in the interference zone either with or by interference.

[0039] As is well known, the taper functions precisely to facilitate interference coupling, thereby the presence of the tapered portion clearly indicates the location of the interference zone within the tapered portion.

[0040] More specifically, the rim 5 has an inner surface 20 that faces radially toward the axis H. The rotor 12 is in direct contact with the inner surface 20, particularly in the interference zone.

[0041] The rim 5 may include a portion positioned in contact with the rotor 12, the latter of which, instead of being entirely made of metal, includes a polymer or elastomer, such as rubber, particularly vulcanized rubber.

[0042] In other words, the portion of the rim 5 containing a polymer or elastomer includes the inner surface 20.

[0043] Therefore, interference or contact between the rotor 12 and the rim 5 can occur, without loss of generality, between the two respective metallic materials (metal-metal contact), or between a metallic material and a polymer or elastomer (metal-polymer / elastomer contact), or even between materials that are not entirely metallic.

[0044] In general, interference or contact between the rim 5 and the rotor 12 does not preclude the rotor 12 from being further attached to the rim 5 by additional fastening means, such as screw members. In fact, the wheel 4 may be equipped with additional fastening means for securing the rim 5 to the rotor 12.

[0045] The rim 5 and rotor 12 can be made from a single piece, or they can have several fixed parts, or they can be fixed to each other without loss of generality.

[0046] As already mentioned, the rim 5 is coupled to the rotor 12 by interference, so that the inner diameter of the rim 5 may be smaller than the outer diameter of the rotor 12, but the rotor 12 is positioned radially inward of the rim 5.

[0047] More precisely, the rotor 12 includes a portion 15 that is in direct contact with the rim 5 and is therefore coupled to the rim 5 by interference or mutual contact.

[0048] Section 15 defines a housing that also accommodates the stator 11, particularly section 14. The latter is fixed to section 15 and is positioned radially inward of section 15.

[0049] Specifically, part 15 has a bell-shaped form.

[0050] More specifically, portion 15 has a radially inward end 16 positioned radially inward relative to the stator 11.

[0051] The end portion 16 defines an axial bore 17 around axis H.

[0052] The wheel hub 9 comprises a portion 18 located within a housing defined by portion 15, and a portion 19 extending along the axis H through an axial bore 17.

[0053] The stator 11 is supported by the wheel hub 9 in part 18. Part 18 is coaxial with the ring defined by part 14 and is radially positioned within the same ring.

[0054] The radial bearing 13 comprises an inner ring 21, an outer ring 22, and rolling elements 23 arranged radially between the inner ring 21 and the outer ring 22.

[0055] In particular, the rolling element 23 is defined by a ball, more specifically by the two crowns of the ball.

[0056] Specifically, the radial bearing 13 is a tilt bearing, thereby supporting axial and radial loads. The mounting type of the radial bearing 13 is not described in detail, but it may be a mounting with the axis of the accident ball on the inside of the radial bearing 13 (X mounting) or on the outside of the radial bearing 13 (O mounting).

[0057] The outer ring 22 is positioned around the axis H and fixed to the rotor 12. More precisely, the outer ring 22 is fixed to the rotor 12 at its end 16 within the axial bore 17.

[0058] Therefore, as can be implicitly or alternatively directly and clearly derived from Figure 2, the end 16 is radially aligned with the outer ring 22, more generally with the radial bearing 13.

[0059] In other words, the end portion 16 extends radially from the rim 5, or more precisely, from the interference zone to the outer ring 22.

[0060] The inner ring 21 is positioned around the axle H and fixed to the wheel hub 9. More precisely, the inner ring 21 is fixed to the wheel hub 9 in a portion 19 within the axial bore 17.

[0061] The inner ring 21 is radially outward of the portion 19, and the outer ring 22 is radially inward of the end portion 16.

[0062] Therefore, the outer ring 22 rotates about axis H relative to the inner ring 21, which is fixed to the wheel hub 9.

[0063] Here, the hub 9 is intended to be the central or radially innermost member of the wheel 4, and is not rotatable about the axis H, but more specifically fixed to the axis H.

[0064] From this, it is clear that the wheel hub 9 is a stator support.

[0065] Preferably, as can be directly and clearly derived from Figure 2, the radial bearing 13 supports the rotor 12 from the outside in the axial central zone of the rim 5, i.e., in the center along axis H.

[0066] In other words, the outer ring 22 and the radial end 16 are arranged axially in the axial central region.

[0067] Preferably, the wheel 4 includes a brake disc 24 supported by the rotor 12 in a position fixed to the rotor 12, particularly at the end 16.

[0068] As can be directly derived from the diagram, the brake disc 24 is located axially outward from the rotor 12. The term "axially outward" is intended to refer to the vehicle 1 and axle H.

[0069] The brake disc 24 faces outward from the vehicle 1 along axis H and is positioned in front of or downstream of the rotor 12, extending from the inside to the outside of the vehicle 1 along axis H.

[0070] The brake disc 24 is positioned outside the housing defined by part 15.

[0071] As can be directly derived from the diagram, the housing defined by part 15 faces the interior of the automobile 1. Part 15 is positioned between the brake disc 24 and the housing. In other words, the brake disc 24 is positioned on the opposite side of the housing that faces the interior of the automobile 1.

[0072] More precisely, the radial end 16 is positioned axially, i.e., along axis H, between the brake disc 24 and the housing defined by portion 15.

[0073] Specifically, the wheel 4 includes a spacer plate 25 positioned axially between the rotor 12 and the brake disc 24. The spacer plate 25 is attached to both the rotor 12 and the brake disc 24, for example, by a threaded member (not shown).

[0074] Clearly, as can be deduced from the diagram, the spacer plate 25 separates the brake disc 24 axially from the rotor 12.

[0075] More preferably, the wheel 4 is equipped with a brake caliper device 26. The device 26 is configured to contact and selectively cooperate with the brake disc 24. In other words, the device 26 is controllable to grip the brake disc 24 and thus exert a braking force on the rotor 12 by grinding friction, and to release the brake disc 24 and thus stop exerting the braking force.

[0076] The device 26 and brake disc 24 are part of the wheel braking system 4. In this case, the braking system is suitable for use as an emergency brake, parking brake, or auxiliary brake.

[0077] In fact, the electric motor 10 can be used as a brake when it is operating as a generator.

[0078] The device 26 is supported by the wheel hub 9. In other words, the device 26 has at least one element 27 fixed to the wheel hub 9.

[0079] In particular, the device 26 includes at least one portion 28 that extends within the inner ring 21.

[0080] Conveniently, the wheel 4 includes a rim cover 29 fixed forward to the rim 5, for example, by a shape coupling or by a threaded member.

[0081] The rim cover 29 is attached to the rim 5 in a releasable or removable manner, meaning that separation of the rim cover 29 from the rim 5 can occur without damaging the rim cover 29 or the rim 5.

[0082] In other words, the rim cover 29 is removable at will.

[0083] Therefore, inevitably, removing the rim cover 29 involves opening up the opening in the rim 5. The latter opening is configured to receive the rim cover 29.

[0084] Therefore, as can be directly deduced from the diagram, the opening is in direct communication with the outside of automobile 1.

[0085] More precisely, the opening faces outward in the direction away from the vehicle 1.

[0086] As can be directly inferred from the diagram, the brake disc 24 is positioned between the rotor 12 and the opening, along the axis H.

[0087] Preferably, the wheel 4 includes one or more sensors configured to detect one or more amounts indicating force and / or torque acting on the rotor 12, or more precisely, on the rim 5, and thus on the rotor 12 itself, coupled to the rotor 12, or more precisely, to the portion 15.

[0088] Since a force or torque can have multiple force or torque components in three-dimensional space, its magnitude can represent each of these force or torque components.

[0089] For example, the sensor may be a strain gauge that is directly fixed to the rotor 12, or more precisely, to the part 15.

[0090] From the above, the advantages of the wheel 4 according to the present invention are clear.

[0091] Wheel 4 integrates the electric motor 10 in a simple, effective, and efficient manner.

[0092] The rotor 12 is integrated with the rim 5 by interference coupling. This type of coupling makes it possible to avoid the use of a gear motor.

[0093] The fact that the rotor 12 is fixed to the outer ring 22, that is, that the rotor 12 is supported outward by the radial bearing 13, allows for a more centralized arrangement of the interference zone between the rim 5 and the rotor 12 with respect to axis H, as well as radial alignment of the interference zone with the radial bearing 13.

[0094] In this way, during use of the automobile 1, the load on the rim 5 is typically discharged towards the center along the axis H, so the radial bearing 13 can better support such loads and is less affected by torque resulting from radial misalignment between the interference zone and the center of the radial bearing 13.

[0095] This results in greater robustness and reliability for wheel 4.

[0096] Furthermore, interference coupling minimizes the number of components required for the operation of wheel 4.

[0097] Therefore, wheel 4 is easily manufactured and reliable.

[0098] Furthermore, the sensors enable the direct acquisition of information that directly indicates the forces and / or torques acting on the rim 5, which are useful for controlling the dynamics of the vehicle 1. These sensors are more accurate and sensitive than estimates made based on indirect measurements of the forces and / or torques acting on the rim 5.

[0099] Finally, it is clear that modifications and alterations can be made to the wheel 4 according to the present invention, but these will not fall outside the scope of protection as defined by the claims.

[0100] In particular, each detail included in the drawing is independent of the other details and is specifically designed to solve a particular technical problem, separate from the other details.

[0101] In particular, each detail included in the drawing is independent of the other details and is specifically designed to solve a particular technical problem, separate from the other details.

[0102] In particular, the details mentioned include each of the various component arrangements shown with respect to other components.

[0103] More specifically, the shapes and dimensions shown are merely illustrative and not closely related to the arrangement of the components.

Claims

1. A wheel assembly (4) for an automobile (1), wherein the assembly (4) is - A rim (5) having an axle (H) and an outer surface (6) defining a seat (7) for attaching a tire (8), - A wheel hub (9) is positioned inside the rim (5) around the axle (H) and is suitable for coupling to the suspension of the automobile (1), - An electric motor (10) comprising a stator (11) fixed to the wheel hub (9) and coaxially arranged with the wheel hub (9), and a rotor (12) configured to magnetically interact with the stator (11), - A radial bearing (13) supports the rotor (12) so as to be rotatable about the shaft (H) relative to the wheel hub (9) and stator (11), The apparatus is characterized in that the rim (5) is attached to the rotor (12) in a manner that interferes with it, thereby fixing the rim (5) to the rotor (12).

2. The apparatus according to claim 1, wherein the rotor (12) comprises at least a first rotor portion (14, 15) that is radially outward from the stator (11) and coaxial with the stator (11), and the rim (5) is attached to the first rotor portion (14, 15).

3. The apparatus according to claim 1 or 2, wherein the radial bearing (13) comprises an outer ring (22) arranged around the shaft (H) and fixed to the rotor (12).

4. The wheel device according to claim 1 or 2, further comprising a brake disc (24) supported by the rotor (12) in a fixed position relative to the rotor (12).

5. The wheel device according to claim 1 or 2, wherein the radial bearing (13) comprises an inner ring (21) arranged around the shaft (H) and fixed to the wheel hub (9).

6. The wheel device according to claim 5, further comprising a brake caliper device (26) supported by the wheel hub (9) and having at least one portion (28) extending into the inner ring (21) of the radial bearing (13).

7. The apparatus according to claim 6, wherein the rotor (12) comprises a second rotor portion (14) having one or more permanent magnets configured to generate a magnetic flux, and the stator (11) comprises an electric winding (30), the electric winding (30) configured to generate a magnetic field that interacts with the magnetic flux in response to the flow of current passing through it.

8. The apparatus of claim 7, wherein the magnetic flux is directed radially toward the stator (11).

9. The apparatus according to claim 1 or 2, wherein the rotor (12) comprises a third rotor portion (14) that defines a rotor ring around the shaft (H), and the stator (11) comprises a stator portion (18) that is coaxial with the rotor ring and radially arranged within the rotor ring.

10. The apparatus according to claim 9, wherein the rotor (12) comprises a fourth portion (15) that defines a housing for accommodating the stator (11).

11. The apparatus according to claim 1 or 2, further comprising one or more sensors coupled to the rotor (12) and configured to detect one or more amounts indicating a force or torque acting on the rim (5) or the rotor (12).

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