Steering wheel actuator with magnetorheological brake for steer-by-wire steering systems

Abstract

The present disclosure provides a steering wheel actuator system (100) for a vehicle, comprising a steering wheel (10) intended to be operated by a driver of the vehicle; a magnetorheological brake (30) designed to provide a reactive torque to the steering wheel (10) and comprising a preferably cylindrical outer shell (32) and an inner central shaft (36) arranged inside the outer shell (32); and an electric motor (20) designed to provide an active torque to the steering wheel (10) and comprising a rotor (21) and a stator (22). Both the magnetorheological brake (30) and a rotor (22) of the electric motor (20) are attached to the steering wheel (10).

Description

DESCRIPTION TITLE: STEERING WHEEL ACTUATOR WITH MAGNETO-RHEOLOGICAL BRAKE FOR WIRE STEERING SYSTEMS Technical field of the invention

[0001] This disclosure relates to vehicle steering systems, and more specifically to a steering wheel actuator system for providing feedback and control in vehicle steer-by-wire or electric steering applications using a magnetorheological brake and an electric motor, and a method involving such a steering wheel actuator system. State of the art

[0002] Vehicle steering systems have traditionally relied on mechanical linkages to transmit driver inputs from the steering wheel to the wheels. However, with advancements in automotive technology, wire-driven steering systems (or electric power steering) have emerged as an innovative approach. In wire-driven steering systems, the mechanical connection between the steering wheel and the wheels is replaced by electrical and / or electronic controls and actuators. This allows for greater flexibility in vehicle design and potential improvements in safety, performance, and vehicle layout.

[0003] A key component of wire-steering systems is the steering wheel actuator, which provides feedback to the driver through the steering wheel. This feedback is essential for maintaining a natural driving feel and communicating road conditions to the driver. Conventional steering wheel actuators typically use electric motors to generate both the reactive torque that opposes the input action of the driver or driver input and the active torque used to reposition the steering wheel.

[0004] However, current steering wheel actuator designs face several challenges. Using electric motors alone to provide both reactive and active torque can be energy-intensive and may not always offer the most realistic steering feel. Furthermore, integrating these actuators into the vehicle's steering column can be complex, often requiring compromises in terms of space efficiency (integration within the vehicle) and structural integrity.

[0005] Furthermore, the reliability and fail-safe operation of wired steering systems are of paramount importance for vehicle safety. Current designs may not always provide sufficient redundancy and / or operational capability in the event of a component failure.

[0006] Finally, integrating electrical components into the steering system often requires the use of specialized parts such as swivel connectors for electrical connections, adding to the complexity and cost of the system.

[0007] It has been recognized that a steering wheel actuator system is necessary to overcome one or more of these problems. Description of the invention

[0008] In the first aspect, a steering wheel actuator system for a vehicle is proposed. The steering wheel actuator system is arranged to receive a steering wheel intended to be operated by a driver of the vehicle, and includes a magnetorheological brake (hereafter referred to as an MR brake) arranged to provide reactive torque to the steering wheel and comprising an outer shell, preferably cylindrical, and an internal central shaft disposed within the outer shell, and an electric motor arranged to provide active torque to the steering wheel and comprising a rotor and a stator, where both the brake MR and an electric motor rotor are arranged to be attached to the steering wheel. Alternatively, the steering wheel actuator system may include the steering wheel itself, intended to be operated by a vehicle driver.

[0009] This configuration offers a more compact design where the MR brake contributes to the steering wheel actuator's torque while ensuring structural integrity and allowing longitudinal positioning by sliding or translating within a reference guide element. The MR brake effectively becomes the steering column, resulting in a space-saving design. The mounting of both the MR brake and the electric motor rotor provides greater design flexibility and allows one device to compensate for a failure of the other.

[0010] The steering wheel actuator system can further be defined by the following characteristics, taken individually or in combination.

[0011] According to one embodiment of the steering wheel actuator system, the stator of the electric motor can be fixed to the outer shell of the MR brake.

[0012] This arrangement allows for a more integrated and compact design, reducing the overall size of the steering wheel actuator system. Furthermore, the electric motor stator can be directly attached to the outer shell of the MR brake. Additionally, the electric motor rotor can surround the stator and / or have a larger diameter than the outer shell of the MR brake.

[0013] The MR brake, and preferably its outer shell, may have a Length / Diameter ratio greater than 2, preferably greater than 3, preferably greater than 4.

[0014] This elongated design of the MR brake allows it to effectively serve as a steering column, providing both the necessary structural support and reactive torque functionality in a single component. This elongated form factor facilitates the integration of a mounting bracket sliding to the vehicle, to provide an adjustable or even retractable steering column, for example reversible.

[0015] The MR brake and the electric motor rotor can be arranged to be fixed independently and / or directly to the steering wheel, and / or the MR brake and the electric motor rotor can be arranged to be fixed to separate parts of the steering wheel; in other words, any rotation of the steering wheel causes an identical rotation of the moving parts of the MR brake and the electric motor rotor.

[0016] This configuration offers safe operation with inherent safety features, as the motor and the MR brake are completely independent, ensuring continued operation in the event of a failure. If one component fails, the other can still provide some level of steering functionality. In other words, the MR brake and the electric motor rotor are mounted to the steering wheel in parallel (and not in a series of actuators, with one attached to or following the other, the latter being attached to the steering wheel). In this embodiment, each of the MR brake and the electric motor rotor has its own direct mounting or connection to the steering wheel.

[0017] The steering wheel actuator system may include an outer housing that preferably at least partially encloses the outer shell, and may include a slide located between the outer shell and the outer housing. A length-to-diameter ratio greater than 2, preferably greater than 3, and preferably greater than 4, of the outer housing simplifies the integration of the slide. The MR brake becomes a structural element of the steering column.

[0018] This sliding mechanism facilitates the longitudinal positioning of the steering wheel, allowing for adjustment to suit different driver preferences, ergonomics, and driving styles. This sliding mechanism also provides a safety feature, with for example, a sliding mechanism during an accident to minimize injuries to occupants.

[0019] The steering wheel actuator system may include at least one axial bearing, such as a tapered roller bearing, disposed between the steering wheel and the outer shell.

[0020] The axial bearing helps reduce friction and wear between the (rotating) flywheel and the stationary outer shell, ensuring smooth operation and system longevity. Such a tapered roller bearing is also well-suited to withstand axial loads applied, for example, during an accident (airbag deployment, occupant restraint, etc.). It should be noted that the tapered roller bearing directs the load or force path to the outer shell of the MR brake (as opposed to the internal parts of the MR brake or the motor).

[0021] The internal center shaft can be a single shaft from the steering wheel actuator, and / or the internal center shaft can be disposed or arranged through the electric motor.

[0022] This design simplifies the overall structure of the flywheel actuator system, reducing the number of components and potential points of failure. In particular, the internal central shaft can pass through the electric motor and through the middle of the stator, which is itself surrounded by the rotor.

[0023] The internal center shaft may be hollow, so as to provide a continuous path (or harness path) for a wiring harness linking an electrical device on the steering wheel to an electrical network in the vehicle.

[0024] The hollow internal center shaft can eliminate the need for a separate rotating connector, reducing costs and simplifying electrical connections between the steering wheel and the vehicle's electrical systems.

[0025] The steering wheel actuator system may have specific dimensional characteristics, including: the outer shell having an external diameter of 20 mm to 60 mm and / or a length of 200 mm to 450 mm, preferably a length of 270 mm to 320 mm, the internal central shaft having a length of 200 mm to 500 mm, preferably a length of 330 mm to 380 mm, and the electric motor having an external diameter of 80 mm to 110 mm.

[0026] These specific dimensions contribute to the overall compactness of the system while ensuring sufficient space for all necessary components and functionalities.

[0027] The MR brake may comprise a magnetorheological (MR) fluid (and / or a dry magnetorheological (MR) powder which comprises dry iron / ferrite particles) and at least five coils, preferably at least 10 coils, preferably at least 14 coils.

[0028] The use of multiple coils in the MR brake allows for precise control of the magnetic field strength, enabling fine-tuning of the reactive torque. This configuration also contributes to the cost and energy efficiency of the MR brake in producing torque compared to conventional electric motors. While individual coils have a limited diameter, thus restricting the maximum achievable torque, and a single coil has a limited number of turns and a limited surface area for copper wire, limiting the electromagnetic force and torque of a single coil, the arrangement of multiple coils in line or in series provides an elongated outer casing and allows for the torque required for a realistic steering experience. Multiple coils can also contribute to redundancy for the built-in fail-safe capability.The winding direction of adjacent coils can be reversed to increase the magnetic flux in the ring and create an additive effect between the adjacent coils. For example, if a coil is... wound clockwise, the adjacent coil can be wound counterclockwise.

[0029] The MR brake may include a frame with teeth or rings in which the spools are wound.

[0030] In addition to the features described above, the steering wheel actuator system can incorporate several other aspects that improve its functionality and design:

[0031] The electric motor stator can be in direct contact with, or fixed directly to, the outer shell of the MR brake. This configuration can contribute to a more integrated and compact design, potentially improving heat dissipation and structural integrity.

[0032] The steering wheel actuator can be telescopic, allowing for adjustability to suit different driver preferences and vehicle configurations. In some cases, the outer shell can slide or translate within the outer casing, facilitating this telescopic functionality to provide adjustability or minimize the risk of injury in the event of an accident.

[0033] To ensure safe operation, the steering wheel actuator may include a mechanical stop to limit rotation to ±165°, ±170°, or ±175°. This feature can help prevent over-rotation of the steering wheel, improving safety and control.

[0034] The steering wheel actuator system can be designed without a rotating connector. This approach can simplify electrical connections and potentially reduce maintenance requirements.

[0035] For accurate position detection, the steering wheel actuator can incorporate at least one angular encoder. The angular encoder can be an absolute encoder. This component can provide precise feedback on the steering wheel position, which may be important for the operation of the wire steering system.

[0036] The internal central shaft can be fixed to a central hole or hub of the steering wheel or steering wheel frame. Alternatively, the electric motor rotor can be fixed to a peripheral area of ​​the steering wheel or steering wheel frame, positioned around this central hole or hub. This configuration allows for efficient torque transfer and a compact design. Specifically, the electric motor rotor can be fixed to an area around this central hole or hub—that is, an area with a larger diameter or further from the axis of rotation—than if the electric motor rotor were fixed to the internal central shaft. Consequently, the electric motor is more efficient: the torque actually delivered to the steering wheel is greater. If the diameter of the mounting area is smaller, achieving equivalent torque would require a longer or larger motor.In other words, the external rotor according to the present implementation is more advantageous because it provides a higher torque density.

[0037] An adapter plate can be positioned at least between the electric motor rotor and the steering wheel or steering wheel armature. This component can facilitate motor integration with the steering wheel and potentially allow for easier customization or replacement. The adapter plate can also compensate for play, particularly radial play, between the electric motor rotor and the internal center shaft. The adapter plate may include tolerance or backlash compensation elements or devices.

[0038] As seen above, the MR brake is attached to the flywheel by the internal central shaft, and the electric motor is attached to the flywheel via its rotor. Thus, the MR brake and the electric motor are attached to distinct portions of the flywheel; in particular, the electric motor rotor is attached to the flywheel in a radial area further away than the MR brake attachment point. to be able to impose a significant active torque on the flywheel, even with a small axial and / or radial electric motor. Typically, the active torque can reach up to + / - 5 Nm. For example, the mounting area of ​​the electric motor rotor on the flywheel is at least 30 mm, preferably at least 35 mm, preferably at least 40 mm, preferably at least 50 mm, preferably at least 60 mm, preferably at least 70 mm from the flywheel's axis of rotation.

[0039] The outer casing of the MR brake may include a sealed internal space to receive the MR fluid. This sealed internal space for the MR fluid may be one millimeter or less. This sealed design can help ensure the longevity and consistent performance of the MR brake by protecting the MR fluid from contamination.

[0040] These additional features can contribute to the overall efficiency, reliability, and versatility of the steering wheel actuator system in wire-steering applications. Description of the figures

[0041] Other features and advantages of the present invention will become more apparent upon reading the following detailed description of embodiment(s) of the invention given by way of non-limiting example(s) and illustrated by the accompanying drawings, in which:

[0042] [fig. 1] illustrates a perspective view of a steering wheel actuator for a wire-steering system, according to aspects of this disclosure;

[0043] [fig. 2] illustrates an exploded view of the steering wheel actuator of figure 1, according to one embodiment;

[0044] [fig. 3] illustrates a cross-sectional view of the steering wheel actuator of figure 1, according to aspects of this disclosure.

[0045] Detailed description of implementation method(s)

[0046] A 100 steering wheel actuator system for a vehicle is shown and illustrated in Figure 1 in a perspective view.

[0047] The steering wheel actuator system 100 includes a steering wheel 10 intended to be operated by a driver of the vehicle.

[0048] The flywheel actuator system 100 further includes a magnetorheological brake (hereafter referred to as the MR brake) 30 arranged to provide reactive torque to the flywheel 10. The MR brake 30 has an elongated cylindrical shape with a diameter between 30 and 60 mm.

[0049] The steering wheel actuator system 100 also includes an electric motor 20 arranged to provide active torque to the steering wheel 10. The electric motor 20 comprises a rotor and a stator. Both the brake MR 30 and one rotor of the electric motor 20 are fixed, connected, or attached to the steering wheel 10. In other words, the electric motor 20 and the brake MR 30 are connected in parallel to the steering wheel 10, each on its own side.

[0050] The steering wheel actuator system 100 also includes a reference part 40 comprising a mounting plate 41 and an outer housing 42 partially surrounding the MR brake 30. As will be explained in detail, the assembly of the steering wheel 10, the MR brake 30 and the electric motor 20 has the ability to slide, glide or translate within the outer housing 42.

[0051] The steering wheel actuator system 100 is designed to operate in a wire-steering system, providing both active and reactive torque feedback to the driver through the steering wheel 10. The combination of the MR brake 30 and the electric motor 20 enables precise control and simulation of steering forces in the absence of a mechanical connection to the vehicle's wheels.

[0052] Figure 2 illustrates an exploded view of a steering wheel actuator 100 for a wire steering system. The steering wheel actuator 100 comprises several components arranged in an elongated configuration.

[0053] The flywheel 10 is positioned at one end of the flywheel actuator 100. Adjacent to the flywheel 10 is a mechanical interface 50, which connects the flywheel 10 to the other components of the system.

[0054] The electric motor 20 is positioned next to the mechanical interface 50. The electric motor 20 includes a stator which is fixed to the outer shell 32 of the MR brake 30. This arrangement provides a stable mounting for the electric motor 20 inside the flywheel actuator 100.

[0055] The MR 30 brake is located adjacent to the electric motor 20. The MR 30 brake and the rotor of the electric motor 20 are fixed independently and directly to the flywheel 10. In addition, the MR 30 brake and the rotor of the electric motor 20 are fixed to separate parts of the flywheel 10, allowing separate control of reactive and active torque.

[0056] A reference part 40 is positioned at the opposite end of the steering wheel 10. The reference part 40 includes a mounting plate 41 to be fixed to the vehicle, and an outer housing 42, which serve as structural support and housing for the other components of the steering wheel actuator 100.

[0057] This exploded view demonstrates how these components are designed to assemble in a compact and rather elongated arrangement. The configuration allows for the integration of active torque generation (via the electric motor 20) and reactive torque (via the MR brake 30) into a single steering column assembly.

[0058] Figure 3 illustrates a cross-sectional view of the steering wheel actuator 100, providing a detailed overview of the internal components and their arrangement. The steering wheel actuator 100 comprises several components arranged in a compact cylindrical design.

[0059] The flywheel 10 is positioned at one end of the flywheel actuator 100. Adjacent to the flywheel 10 is the electric motor 20, which comprises a rotor 21 and a stator 22. The electric motor 20 has a diameter The external diameter can range from 80 mm to 110 mm (for example, 85 mm, 90 mm, 95 mm, 100 mm, 105 mm). The electric motor 20 is designed to provide active torque to reposition the flywheel 10. The electric motor 20 is positioned at the end near the armature of the flywheel 10.

[0060] The MR 30 brake comprises an outer shell 32, which may be cylindrical, and an internal central shaft 36 disposed in the outer shell 32.

[0061] The outer shell 32 of the MR 30 brake can be made of metal, for example steel, and provides structural integrity to the steering column. The outer shell 32 facilitates the longitudinal positioning of the steering wheel 10 by sliding in a reference guide element fixed to the reference part 40.

[0062] The steering wheel actuator 100 includes the outer housing 42 which at least partially encloses the outer shell 32 of the MR brake 30. A slide is arranged between the outer shell 32 and the outer housing 42, facilitating precise longitudinal movement of the steering column.

[0063] The mechanical interface 50 includes the interface plate 51 and a tapered roller bearing 52, disposed between the flywheel 10 and the outer shell 32 of the MR brake 30. This bearing allows precise rotation of the flywheel 10 while maintaining a secure connection to the MR brake 30 and ensuring robust transmission of axial load from the flywheel 10 to the outer shell 32 in the event of an accident.

[0064] The steering wheel actuator 100 includes an internal central shaft 36, which is a single shaft extending through the entire assembly. This internal central shaft 36 is positioned through the electric motor 20, providing a continuous axis for the steering column.

[0065] The central part of the steering wheel actuator 100 is occupied by the MR brake 30, which consists of several components. The MR brake 30 includes a guide rack 31, the outer shell 32, a A plurality of coils 33, an armature 34 having teeth or rings around which the coils 33 are wound, a fluid MR 35, and the internal central shaft 36. The brake MR 30 comprises at least five coils 33, preferably at least 10 coils, preferably at least 14 coils. These components work together to provide a responsive torque to the steering wheel 10 based on road conditions and / or driver input on the steering wheel 10.

[0066] The outer shell 32 of the MR 30 brake has an external diameter of 20 mm to 60 mm (e.g., 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm) and a length of 200 mm to 450 mm (e.g., 225 mm, 250 mm, 275 mm, 300 mm, 325 mm, 350 mm, 375 mm, 400 mm, 425 mm), preferably a length of 270 mm to 320 mm. The MR 30 brake, and preferably its outer shell 32, has a length-to-diameter ratio greater than 2, preferably greater than 3, and preferably greater than 4.

[0067] The internal center shaft 36 has a length of 200 mm to 500 mm (e.g., 225 mm, 250 mm, 275 mm, 300 mm, 325 mm, 350 mm, 375 mm, 400 mm, 425 mm, 450 mm, 475 mm), preferably a length of 330 mm to 380 mm. The internal center shaft 36 is hollow, providing a cable path for a wiring harness connecting an electrical device on the steering wheel 10 to a vehicle electrical system.

[0068] The MR 30 brake consists of a series of concentric cylindrical discs (or teeth or rings) around the internal central shaft 36. The discs / teeth, the internal central shaft 36, and the outer shell 32 of the MR 30 brake comprise or are made of ferromagnetic material such as iron or steel. Coils 33 are wound around the internal central shaft 36 between each disc / tooth, with alternating winding directions for adjacent coils 33. The gap between the discs and the cylindrical outer shell 32 is typically less than 1 mm and is filled with the MR 35 fluid.

[0069] At the opposite end to the flywheel 10, the reference part 40 is positioned, which includes the mounting plate 41 and the outer housing 42. These components provide structural support and housing for the 100 steering wheel actuator.

[0070] The interface between the flywheel 10 and the rest of the assembly is facilitated by the interface plate 51 and the tapered roller bearing 52. These components allow precise, smooth and reliable rotation of the flywheel 10 while maintaining a secure connection to the flywheel actuator 100.

[0071] The design integrates the MR 30 brake into the steering column, with the outer shell 32 serving as both part of the braking mechanism and a structural element of the column. This arrangement allows for a compact design that combines the functions of providing return torque and structural support. The elongated outer housing 42 guides the outer shell 32, and the guide rack 31 attached to the outer shell 32 provides anti-rotation to ensure translation of the outer shell 32 through the outer housing 42.

[0072] The arrangement of the components of the MR 30 brake allows the production of a variable torque based on the magnetic field applied to the MR 35 fluid. The combination of the MR 30 brake and the electric motor 20 allows precise control and simulation of steering forces in the absence of mechanical connection to the vehicle wheels.

[0073] The electric motor 20, comprising the rotor 21 and the stator 22, is responsible for supplying active torque to the flywheel 10. This active torque is typically in the range of + / -1 to 5 Nm and is used to reposition the flywheel 10 to a desired position. The electric motor 20 can apply torque in both directions, allowing clockwise and counterclockwise rotation of the flywheel 10.

[0074] The MR 30 brake provides a reactive torque to the steering wheel, simulating the resistance and feedback a driver would feel from road conditions in a traditional mechanical steering system. The MR 30 brake can apply a reactive torque as high as -30 Nm or -15 Nm, always in the opposite direction to the manual steering input. driver direction. The amount of torque supplied by the MR 30 brake depends on the current supplied to the coils 33.

[0075] When a driver applies a force to the flywheel 10, the force is transmitted through the interface plate 51 to the internal central shaft 36 of the MR brake 30. The MR brake 30 then generates a reactive torque by energizing the coils 33, which creates a magnetic field. This magnetic field changes the viscosity of the MR fluid 35 in the space between the armature 34 and the outer shell 32, creating a shear stress resistance of the MR fluid 35 and thus a resistance to rotation.

[0076] The steering wheel actuator 100 can be included in a control system comprising a control unit. The control system and the control unit together control the steering wheel actuator 100 to adjust the current supplied to the brake coils 33 of the MR 30 based on various inputs, such as vehicle speed, steering angle, steering speed, and road conditions. This allows for dynamic adjustment of the steering feel, providing more resistance at higher speeds or during tight turns, and less resistance during low-speed maneuvers.

[0077] Simultaneously, the electric motor 20 can apply active torque to assist steering or to provide additional feedback. For example, the electric motor 20 can apply a small amount of torque to help return the steering wheel 10 to the center or neutral position after a turn.

[0078] In certain aspects, the steering wheel actuator 100 can incorporate a telescopic function, allowing the steering wheel 10 to be adjusted closer to or further from the driver. This telescopic feature can be implemented by allowing the outer shell 32 to slide inside the outer housing 42, potentially using the guide rack 31 located on the outer shell 32 of the MR brake 30 to control the range of movement. The telescopic adjustment can improve driver comfort and ergonomics by adapting to the drivers of different heights and arm lengths or with different driving styles.

[0079] The hollow internal center shaft 36 of the MR brake 30 passes through the electric motor 20, providing a continuous path for a wiring harness. This design can eliminate the need for a separate swivel connector, simplifying electrical connections between the flywheel 10 and the vehicle's electrical systems. In some cases, telescopic functionality can be facilitated by a flexible wiring harness or cable wound inside the hollow internal center shaft 36, allowing extension and retraction without compromising electrical connectivity. This simplification reduces potential points of failure and can lower manufacturing costs.

[0080] The design of the steering wheel actuator 100 offers several advantages over conventional steering systems. The compact nature of the steering wheel actuator 100 is achieved by integrating the MR brake 30 into the steering column structure. The outer shell 32 of the MR brake 30 serves both as part of the braking mechanism and as a structural element of the column, reducing the overall size and complexity of the system.

[0081] The operational capability in the event of failure of the steering wheel actuator 100 is improved by the independent operation of the electric motor 20 and the MR brake 30. In the event of failure of one component, the other can continue to provide a certain level of steering functionality, improving the overall safety and reliability of the system.

[0082] The modular nature of the steering wheel actuator 100, with its separate components such as the electric motor 20, the MR brake 30, and the reference part 40, allows for easier maintenance and potential future upgrades. This modularity could be particularly advantageous for fleet operators or automakers seeking to streamline their maintenance processes or to offer customizable steering options.

[0083] The features of all the examples or embodiments described above can be combined to create additional examples or embodiments without losing the desired effect. It should be understood that the description of any embodiment or example provided above is given by way of illustration only, and that various modifications could be made by a person competent in the field. Furthermore, a person competent in the field will recognize that many other modifications and combinations of various aspects are possible. Accordingly, the aspects described are intended to encompass all such alterations, modifications, and variations that fall within the scope of the invention. Industrial application

[0084] A steering wheel actuator according to the present invention, and its manufacture, are capable of industrial application.

[0085] It will be understood that various modifications and / or improvements obvious to a person skilled in the art can be made to the different embodiments of the invention described in this description without departing from the scope of the invention.

Claims

DEMANDS

1. Steering wheel actuator (100) for a vehicle, arranged to receive a steering wheel (10) intended to be operated by a driver of the vehicle, and comprising: - a magnetorheological (MR) brake (30) arranged to provide a reactive torque to the flywheel (10) and comprising an outer shell (32), preferably cylindrical, and an internal central shaft (36) disposed in the outer shell (32); - an electric motor (20) arranged to provide active torque to the flywheel (10) and comprising a rotor (21) and a stator (22); in which both the MR brake (30) and the rotor (21) of the electric motor (20) are arranged to be fixed to the flywheel (10).

2. Steering wheel actuator (100) according to claim 1, wherein the stator (22) of the electric motor (20) is fixed to the outer shell (32) of the MR brake (30).

3. Steering wheel actuator (100) according to any one of claims 1 to 2, wherein the MR brake (30), and preferably its outer shell (32), has a Length / Diameter ratio greater than 2, preferably greater than 3, preferably greater than 4.

4. Steering wheel actuator (100) according to any one of claims 1 to 3, wherein: - the MR brake (30) and the rotor (21) of the electric motor (20) are arranged to be fixed independently and / or directly to the flywheel (10), and / or - the MR brake (30) and the rotor (21) of the electric motor (20) are arranged to be fixed to separate parts of the flywheel (10).

5. A steering wheel actuator (100) according to any one of claims 1 to 4, comprising an outer housing (42) preferably at least partially enveloping the outer shell (32), the actuator of steering wheel (100) comprising a slide disposed between the outer shell (32) and the outer housing (42).

6. Flywheel actuator (100) according to any one of claims 1 to 5, comprising at least one axial bearing (52), such as a tapered roller bearing, disposed between the flywheel (10) and the outer shell (32).

7. Steering wheel actuator (100) according to any one of claims 1 to 6, wherein the internal center shaft (36) is a single shaft of the steering wheel actuator (100), and / or wherein the internal center shaft (36) is arranged through the electric motor (20).

8. Steering wheel actuator (100) according to any one of claims 1 to 7, wherein the internal center shaft (36) is hollow, so as to provide a continuous path for a wiring harness connecting an electrical device of the steering wheel (10) to an electrical network of the vehicle.

9. Steering wheel actuator (100) according to any one of claims 1 to 8, wherein: - the outer shell (32) has an external diameter of 20 mm to 60 mm and / or a length of 200 mm to 450 mm, preferably a length of 270 mm to 320 mm, and / or - the internal central shaft (36) has a length of 200 mm to 500 mm, preferably a length of 330 mm to 380 mm, and / or - the electric motor (20) has an external diameter of 80 mm to 110 mm.

10. Steering wheel actuator (100) according to any one of claims 1 to 9, wherein the MR brake (30) comprises an MR fluid (35) and at least five coils (33), preferably at least 10 coils, preferably at least 14 coils.

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