Magnetorheological brake with damping means, rotor for a magnetorheological brake and method for producing a rotor

Abstract

The invention relates to a magnetorheological brake (1), comprising: a rotor (3) which is provided so as to be rotatable about an axis (18); a mechanical interface (6) which is provided so as to be rotatable about the axis (18); and a securing portion (7) via which the rotor (3) is rotationally fixed to the mechanical interface (6), wherein the rotor (3) has a first rotor part (3.1) and a second rotor part (3.2), wherein the first rotor part (3.1) is designed to receive a braking effect and the second rotor part (3.2) is designed to damp the braking effect before transmission via the securing portion (7) to the mechanical interface (6). The invention also relates to a force feedback actuator (50), a steering device (100), a rotor (3), and a method.

Description

[0001] P240626

[0002] - 1 -

[0003] Mechanical brake with damping

[0004] The present invention relates to a magnetorheological brake, a force feedback actuator, a steering device, a rotor and a method.

[0005] State of the art

[0006] Magnetorheological brakes are known today. These brakes feature a rotor that is rotatable around an axis and is designed to absorb a braking effect and transmit this braking effect to a mechanical interface, such as a rotatable shaft. The braking effect on the rotor is generated by the friction of a magnetorheological powder (hereinafter also referred to as powder). This powder is designed to change its shear or friction properties in the direction of rotation of the rotor when a corresponding magnetic field is applied, thereby initiating the braking effect on the rotor. The shear or friction properties are essentially determined by chains of powder particles that are formed in response to the magnetic field, as the powder particles adhere to one another.

[0007] These types of brakes can generate frictional vibrations, oscillations, and noise emissions. Consequently, they may exhibit poor noise, vibration, and harshness (NVH) characteristics. In haptic applications (human-machine interfaces such as steering, joysticks, or rotary knobs), this can be uncomfortable or irritating.

[0008] The reason for poor NVH behavior may be that frictional vibrations occur due to a stick-slip effect between the powder and the rotor.

[0009] Based on this, there is a need to improve such a magnetorheological brake.

[0010] Against this background, it is an object of the present invention to provide a magnetorheological brake which in particular has improved NVH behavior.

[0011] Disclosure of the invention

[0012] These and other problems, which may be mentioned in the following description or which may be recognized by a person skilled in the art, are solved by the subject matter of the independent claims. Advantageous embodiments and further developments are P240626

[0013] - 2 - can be seen in the dependent claims, the following description and the drawings.

[0014] The magnetorheological brake according to the invention comprises a rotor rotatably arranged about an axis, a mechanical interface rotatably arranged about the axis, and a mounting section by which the rotor is non-rotatably connected to the mechanical interface. The rotor has a first rotor part and a second rotor part, wherein the first rotor part is configured to receive a braking effect and the second rotor part is configured to dampen the braking effect before it is transmitted via the mounting section to the mechanical interface. The damping allows a reduction or elimination of noise or frictional vibrations that may act on the mechanical interface.

[0015] The braking effect can be achieved through magnetorheological powder as a frictional action in response to a magnetic field that permeates the powder and the first rotor section. Due to the magnetic field, the powder particles essentially bind together radially with respect to the axis, forming chains that adhere to the first rotor section. Shearing of these chains in the rotational or circumferential direction leads to a relative movement of the powder particles with respect to each other and thus to a friction-induced braking effect on the rotor. This method of generating the braking effect allows for simple and rapid control of the braking force by appropriately adjusting the magnetic field, for example, with a controlled electromagnet.

[0016] The mechanical interface can be a shaft. Other elements, such as a haptic input element (e.g., a steering element, especially a steering wheel, a rotary knob, or a joystick), can be connected to the mechanical interface. This allows a braking effect, particularly a braking torque, to be applied to the element connected to the mechanical interface. In this way, the haptic feedback during operation of the element can be influenced accordingly.

[0017] The second rotor section can be designed as a damping element. The damping effect can be achieved through the material damping of the damping element itself, meaning that the energy of the vibration to be damped, particularly friction-induced vibration, is converted into heat through deformation of the material of the second rotor section. This deformation can be elastic. Due to the material damping property, no complex or additional damping devices are required.

[0018] Instead, for example with an essentially disc-shaped rotor, a disc- P240626 can be used.

[0019] - 3 - or a ring-shaped damping element may be provided as the second rotor part. This allows for a compact design of the rotor or brake.

[0020] In particular, to achieve a compact design, the rotor can be constructed such that the first rotor section is arranged as a closed section circumferentially around the axis, and the second rotor section is also arranged as a closed section circumferentially around the axis. The second rotor section can be arranged radially inside the first rotor section with respect to the axis and the first rotor section. In other words, the first rotor section can surround the second rotor section. In this way, the first rotor section can come into contact with the powder to generate the braking effect, while the radially inside second rotor section provides vibration decoupling or a damped connection between the first rotor section and the mechanical interface.

[0021] The damping effect of the second rotor section creates a wear-free damping system, as no parts need to slide against each other for damping purposes. Instead, the damping takes place within the rotor itself, namely in the second rotor section.

[0022] The first rotor part can be made of a metallic material to be resistant to the powder.

[0023] The first rotor part can be made of a ferromagnetic material (e.g. low-carbon steel) to guide the magnetic field accordingly.

[0024] The first rotor part can be manufactured by machining and / or forming a tubular raw material.

[0025] According to one embodiment, the second rotor section can be designed with a loss factor greater than or equal to a minimum loss factor of 0.01 to achieve the damping effect. The larger the loss factor, the more of the supplied energy is absorbed by the second rotor section. In tests, a loss factor of 0.01 to 1.0 proved suitable. This means that between 1% and 100% of the energy is absorbed. In particular, a loss factor of 0.1 proved suitable.

[0026] According to one embodiment, the second rotor part has an elasticity of 150 to 1500 N / mm². 2 due to the upper limit of 1500 N / mm 2 This ensures that the second rotor section does not become too stiff and can perform the necessary deformation. The lower limit of 150 N / mm² ensures this. 2 is ensured to ensure a minimum stiffness for transmission P240626

[0027] - 4 - the braking effect from the first rotor part via the second rotor part to the mechanical interface is possible without causing excessive deformation that could affect haptic perception at the mechanical interface. Alternatively or additionally, the lower limit of 150 N / mm 2 to ensure that the second rotor part can be designed to be sufficiently durable and is not pushed to its load limit by deformation, so that it can ultimately be damaged by excessive deformation.

[0028] According to one embodiment, the second rotor part has an elastomer or consists of an elastomer. The second rotor part can act as an elastomer decoupler. The elastomer decoupler introduces elasticity during direction reversal, which simplifies the detection of the change in direction. When the brake is activated, the mechanical interface relative to the first rotor part can be designed to be detectably rotatable as a result of the torsional elasticity of the second rotor part. This relative rotation allows the system to detect that an operator intends to change the direction of operation. This can trigger the release of the brake as necessary. To detect the corresponding rotation of the mechanical interface relative to the first rotor part, the brake can have appropriately designed sensing means, such as angle sensors, which, for example, detect the angle of rotation of the first rotor part and the mechanical interface, which then, for example,The brake control unit allows for comparison between the different responses. This is particularly advantageous in haptic applications, such as those described above, as changes in direction should not result in any differing or irritating sensations for the user.

[0029] During manufacturing, such a second rotor part can be vulcanized to connect it to the first rotor part and / or other rotor parts or the mechanical interface. This has the advantage of creating a durable bond between the second rotor part and the first and / or other rotor parts. Alternatively, it can be pressed into the first rotor part and / or other rotor parts. In this case, a vulcanization step, which requires monitoring, is unnecessary. Preferably, the second rotor part or the elastomer is positively connected. For this purpose, fastening elements, such as dedicated grooves, can be provided, for example, on the first rotor part and / or other rotor parts to which the second rotor part is to be connected.The second rotor part can have corresponding engagement elements, such as projections, for engaging with the fastening means; these projections can be made of elastomer. The second rotor part can thus be manufactured simply, for example, by a casting process. (See P240626.)

[0030] - 5 - A positive-locking connection allows for a secure connection of the corresponding rotor parts. The grooves can be designed as interlocking grooves.

[0031] To achieve sufficient damping, a plastic, especially one with low elasticity, e.g. an elastomer, with a tensile strength of 150 to 1500 N / mm², has proven suitable. 2 or polyethylene (PE), e.g. with 150 to 1500 N / mm² 2 The degree of cross-linking of the PE is highlighted. Alternatively or additionally, rubber materials are suitable, as they possess similar properties. These can also achieve an elasticity of 150 to 1500 N / mm². 2exhibiting the following characteristics. The second rotor part is preferably designed as a ring that is inserted into the first rotor part.

[0032] For PE, elastomers and rubber materials, for example, a loss factor of 0.10 has proven effective.

[0033] According to one embodiment, the brake has a stator that is fixed relative to the rotor. The rotor and the stator are spaced apart radially with respect to the axis about which the rotor is rotatable. A gap is provided between the rotor and the stator, in which a magnetorheological powder, as described above, is placed. The brake is designed to generate a magnetic field that penetrates the gap and the magnetorheological powder contained therein in order to produce the braking effect on the first rotor section. The generation of the magnetic field can be achieved by means of a magnetic field generator in the brake, such as a coil. In this way, the magnetic field, and thus ultimately the generated braking effect, can be controlled by appropriately adjusting the electric current flowing through the magnetic field generator or by appropriately adjusting the electric voltage applied to the magnetic field generator.

[0034] The rotor can be located within the stator, i.e., radially with respect to the axis about which the rotor is rotatable. Alternatively, the stator can be arranged coaxially with respect to the rotor, also with respect to the axis about which the rotor is rotatable. Thus, the rotor and stator can define the gap radially through mutually facing surfaces. The rotor surface that defines the gap in this way can be a circumferential surface. The rotor can have several such circumferential surfaces. Alternatively or additionally, the rotor can have other surface shapes that define the gap. The corresponding stator surface can be designed such that the gap always has the same width along its path. In this way, the rotor and stator can be adapted to achieve a desired P240626

[0035] - 6 -

[0036] The guidance of the magnetic flux through the rotor material and through the stator material can be achieved.

[0037] The magnetic field, which penetrates the gap and the powder within it to achieve the braking effect, can be directed by appropriately selecting the materials of the stator and rotor. Essentially, the magnetic field can be directed by selecting suitable materials for the stator and the first rotor section. These materials can have low magnetic resistance, such as iron or steel, particularly low-carbon and / or low-alloy steel. In this way, the magnetic field can be directed through the corresponding areas of the rotor and stator that radially flank or define the gap. The second rotor section can be made of a material that provides a corresponding damping effect, such as the aforementioned elastomer, like polyethylene.However, the material of the second rotor part may be non-magnetic or have a magnetic conductivity so significantly lower than that of the first rotor part that the second rotor part has no influence on the magnetic field guidance. Therefore, the geometric design of the first rotor part influences the magnetic field guidance, while the geometric design of the second rotor part has less or no influence.

[0038] The stator can be made of a ferromagnetic material to guide the magnetic field accordingly.

[0039] According to one embodiment, the radial extent of the first rotor part essentially corresponds to the radial extent of the stator. Radial extent refers to the material thickness of the first rotor part and the stator, respectively. It can be provided, in particular, that the radial extents are identical. This means that the first rotor part and the second rotor part, especially in the area where they radially define the gap, have the same material thickness in the radial direction. The magnetic field that penetrates the gap and the powder also penetrates the stator and the first rotor part. An identical radial extent or material thickness of the areas of the stator and the first rotor part penetrated by the magnetic field results in a uniform magnetic flux through these components and thus in a uniform propagation of the magnetic field.

[0040] To prevent saturation of the magnetic field lines, the material thickness in the radial direction must be the same in the rotor and stator. The material thickness in the radial direction can thus be P240626

[0041] - 7 - should be defined so that the best compromise between damping and saturation is found. The material thickness in the radial direction should be chosen to be as small as possible to achieve the greatest possible damping and as large as possible to achieve the lowest possible flux density. The magnetic field develops around the coil, and only very weak field lines form below the circle. Therefore, the second rotor part, in particular the elastomer, can be placed directly below the circle but cannot be integrated into the magnetic circuit.

[0042] Particularly if space constraints prevent the design from making the first and second rotor sections with the same material thickness, it may be possible to design the material thicknesses to differ by a maximum of 10% in the radial direction, meaning that the greater material thickness is a maximum of 10% greater than the smaller one. However, this must be accepted as a consequence of a deterioration of the magnetic field, a deterioration of the magnetic field propagation, or a change in the magnetic flux along the field lines.

[0043] According to one embodiment, the radial material thickness of the first rotor section is no greater than the corresponding material thickness of the stator. This serves to limit the rotational moment of inertia of the rotor. In general, the radial extent of the first rotor section influences the rotational moment of inertia of the rotor. Particularly in embodiments where the first rotor section is positioned radially outward and the second rotor section radially inward, the radial extent of the first rotor section has a significant impact on the rotational moment of inertia of the rotor, due to the comparatively large distance between the first rotor section and the rotor's axis of rotation.

[0044] The second rotor section can exhibit a significantly higher magnetic resistance compared to the first. This is particularly true in embodiments where the second rotor section is made of or comprises an elastomer, as described above. This means that the magnetic field can be guided exclusively or at least predominantly by the first rotor section, while the second rotor section remains unaffected or at least almost unaffected, i.e., it is not penetrated by the magnetic field or only to a small extent. Therefore, the material thickness of the first rotor section must be adapted to the radial material thickness of the stator, ensuring that the first rotor section does not unnecessarily increase the rotational inertia of the rotor.

[0045] The higher magnetic resistance of the second rotor part can lead to a scattering of magnetic field lines from the first rotor part into the second rotor part P240626

[0046] - 8 - is inhibited or completely blocked. In this way, a more direct and better guidance of the magnetic field within the rotor or the rotor material is possible. If, for example, an elastomer as described above is used as the material for the second rotor part, the magnetic field, or its path, is almost unaffected.

[0047] Alternatively or additionally, the radial extent of the second rotor section is less than or equal to the radial extent of the first rotor section. This results in the thinnest possible second rotor section, which is, for example, designed as a ring. Such a second rotor section is therefore radially as rigid as possible, thus improving the coaxial position of the rotor relative to the mechanical interface and / or the stator. This allows the gap between the first rotor section and the stator to be as thin as possible without increasing the risk of contact between the rotor and stator. A minimal gap enables the brake to achieve maximum braking effect.

[0048] According to one embodiment, the brake has an interior space in which the magnetorheological powder is contained. The rotor, in particular the second rotor part, has at least one sealing element that seals the interior space radially with respect to the axis. In this way, the powder can be retained in the interior space. The rotor can extend at least partially radially into the interior space. The at least one sealing element can be substantially axially extended, thereby achieving a radial seal of the interior space by having its free end make axial contact with a surface bounding the interior space, e.g., an inner surface of a brake housing. In this way, separate sealing elements for sealing the interior space can be eliminated.Preferably, the at least one sealing element is designed such that the interior is sealed solely by the at least one sealing element, so that separate sealing elements can be completely dispensed with.

[0049] The at least one sealing element can seal the interior as a sliding sealing element. This means that the at least one sealing element is connected to the rotor and follows its rotational movement, sliding along a surface such as the aforementioned housing wall. Additional sliding sealing elements are therefore unnecessary.

[0050] The gap can be identical to the interior space or be designed as a section of the interior space within the interior space. This can be achieved through the appropriate placement of the P240626.

[0051] - 9 - at least one sealing element can thus ensure that the powder remains in the interior and, if necessary, in the gap.

[0052] The at least one sealing element can comprise two or more sealing elements. These two sealing elements can extend axially and preferably in opposite directions from the rotor. This means that the interior space into which the rotor extends is bounded by these sealing elements in the radial direction, preferably inwards. Thus, no further sealing element is required on either axial side of the rotor.

[0053] The at least one sealing element, and in particular the two sealing elements, can be positioned radially inward with respect to the axis about which the rotor is rotatable, while the interior extends radially outward, i.e., at a greater distance from the axis about which the rotor is rotatable. This arrangement ensures that the gap, and thus the braking effect of the powder, acts radially outward on the rotor to provide the largest possible lever arm.

[0054] The at least one sealing element can be part of the second rotor part and, in particular, can be formed integrally with the second rotor part. If the second rotor part consists of an elastomer, as described above, or incorporates an elastomer, the at least one sealing element can be designed as a sealing element extending from the second rotor part, made of this elastomer, which extends substantially axially and, for example, contacts an inner housing wall of the interior that delimits the interior. Such a sealing element can be manufactured together with the second rotor part, for example, by a casting process. By using an elastomer to manufacture the at least one sealing element, a sealing effect of the interior is ensured. The elastomer can, for example, adapt to the contour of the inner housing wall of the interior by deforming accordingly in order to achieve the sealing effect. The manufacture of the brake or...Its design is simplified by this design of the at least one seal, as no additional sealing elements are required. Furthermore, the one-piece design allows for improved sealing, since there is only one contact point between the seal and a corresponding counter surface, such as the inner wall of the housing, which is a potential leakage point. There is no contact point between the rotor and the at least one sealing element, as the at least one sealing element is integrally and therefore tightly connected to the rotor or the second rotor part. P240626.

[0055] - 10 -

[0056] If the sealing element contacts an inner wall of the housing, a further damping element can be formed integrally with the sealing element or at least with the second rotor part, which forms a sliding surface pairing with an inner wall of the brake housing and which, when the rotor rotates, experiences damping due to a frictional force as the sliding surface pairing slides, which acts in addition to the material damping of the second rotor part.

[0057] According to one embodiment, the rotor has a third rotor part designed to connect the rotor to the mounting section. This third rotor part can be located radially further inward than the second rotor part with respect to the axis around which the rotor is positioned. In other words, the second rotor part can at least partially surround the third rotor part. The third rotor part can be attached to the mechanical interface by means of fasteners such as screws. This creates a rotor that can be detachably connected to the mechanical interface. Maintenance and disassembly of the brake, specifically of the rotor and the mechanical interface, are thus possible.

[0058] According to one embodiment, the second rotor part can be connected to the mounting section. This eliminates the need for a third rotor part, thus simplifying the rotor's design. The mechanical interface can include a corresponding section for connecting the second rotor part. Particularly if the second rotor part is made of or incorporates an elastomer, the connection between the second rotor part and the mechanical interface can be achieved by vulcanization, by pressing the second rotor part onto the mechanical interface, and / or by pressing the second rotor part into corresponding engagement elements.

[0059] The third rotor section can be made of a metallic material such as steel to achieve the required strength or stiffness. In particular, it can be alloyed and / or hardened. Alternatively, the third rotor section can be designed to reduce the rotor's weight and, for example, be made of a lighter material than the first and / or second rotor sections. For instance, the third rotor section can be made of aluminum or have an aluminum content.

[0060] The third rotor part can alternatively or additionally be manufactured from a semi-finished product using stamping and / or forming processes. This allows for simple production of the third rotor part. P240626

[0061] - 11 -

[0062] According to one aspect, a force feedback actuator is provided. The force feedback actuator comprises a drive unit, a magnetorheological brake as described above, and a mechanical interface. The force feedback actuator is designed to apply a force or torque to the mechanical interface in order to provide feedback to a user via the mechanical interface. The mechanical interface can be designed as a rotatable shaft, so that a rotary or pivoting movement can be subjected to the corresponding torque feedback by the force feedback actuator. The rotatable shaft can, in particular, be arranged coaxially to the axis about which the brake rotor is rotatable, in order to achieve a compact design for the force feedback actuator. The drive unit can be an electric motor with a rotary axis.The axis of rotation of the drive unit can be arranged, in particular, coaxially with the axis of the rotatable shaft of the force feedback actuator and preferably also coaxially with the axis about which the brake rotor is rotatable, in order to achieve a compact design for the force feedback actuator. Using an electric motor as the drive unit allows for a fast response time of the force feedback actuator. The mechanical interface of the force feedback actuator can be connected to an input element through which a user has haptic contact with the mechanical interface and can make manual inputs. The input element can be designed, in particular, as a steering element, such as a steering wheel, as a rotary knob, and / or as a pivoting element, such as a joystick. In this way, the force feedback actuator can be configured according to the specific application.The force feedback actuator is designed to imprint haptic feedback onto its mechanical interface, and thus onto the input element, via the brake and / or the drive unit. This allows for different types of haptic feedback to be provided to the rider. Specifically, supportive feedback can be generated when the drive unit actuates the mechanical interface of the force feedback actuator in response to the user's input. Conversely, braking feedback can be generated by controlling the brake and / or the drive unit in such a way that it decelerates the mechanical interface of the force feedback actuator in response to the user's input. Therefore, a variety of haptic feedback options can be presented to the rider.

[0063] According to one aspect of the invention, a steering device for a vehicle is provided.

[0064] The steering device has an input element designed as a steering element, a Force- P240626

[0065] - 12 -

[0066] The steering system uses a feedback actuator as described above or a magnetorheological brake as described above. The input element is coupled to the mechanical interface of the force feedback actuator or to the mechanical interface of the brake. The steering element can be, for example, a steering wheel or joystick, allowing the driver to input steering commands into the steering system. The steering system is designed to provide haptic feedback to the driver via the coupling of the steering element to the mechanical interface of the brake or the force feedback actuator. This is particularly advantageous when the steering system is a steer-by-wire system, which lacks a mechanical connection to the steered wheels and therefore cannot directly transmit haptic feedback from the steered axle or wheels to the steering element.However, even with a steering system that has a mechanical drive, a desired steering feel can be generated by means of the brake and / or the force feedback actuator, which the driver can then experience haptically via the steering element.

[0067] According to a further aspect of the invention, a rotor for a magnetorheological brake is provided. The rotor can be designed as described above, and in particular may include the first rotor part and the second rotor part described above.

[0068] According to another aspect, a method for manufacturing a rotor for a magnetorheological brake is provided. The method comprises the following steps:

[0069] Providing a first rotor part and a second rotor part, connecting the first rotor part to the second rotor part.

[0070] The rotor can be designed like the rotor described above.

[0071] Additionally, this method can be part of a process for manufacturing a magnetorheological brake. In this case, a mechanical interface, as described above (e.g., a rotatable shaft), is provided, and the rotor is connected to the mechanical interface via a mounting section to prevent rotation.

[0072] For a person skilled in the art, further steps of this process become clear from the above description of the rotor and brake. In particular, joining the first rotor part to the second rotor part can be achieved by pressing and / or pressing into appropriate elements, such as grooves, or by vulcanization. P240626

[0073] - 13 -

[0074] Detailed description based on drawing

[0075] Further embodiments of the invention are described in more detail below, along with a description of exemplary embodiments of the invention, with reference to the figures. The figures show:

[0076] Fig. 1 shows a schematic sectional view of a magnetorheological brake according to an embodiment of the invention,

[0077] Fig. 2 shows a schematic sectional view of a brake according to a further embodiment of the invention,

[0078] Fig. 3 shows a schematic sectional view of a brake according to a further embodiment of the invention,

[0079] Fig. 4 is a diagram showing the operating ranges of a state-of-the-art magnetorheological brake.

[0080] Fig. 5 is a diagram showing operating ranges of a magnetorheological brake according to the invention,

[0081] Fig. 6 shows a schematic representation of a force feedback actuator, and

[0082] Fig. 7 shows a schematic representation of a steering device for a vehicle.

[0083] The figures are purely schematic and serve only to illustrate the invention. The same elements are identified by the same reference symbols.

[0084] Fig. 1 shows a schematic and exemplary sectional view of a magnetorheological brake according to an embodiment of the invention.

[0085] A magnetorheological brake 1 is shown, comprising a rotor 3 and a mechanical interface 6. The rotor 3 and the mechanical interface 6 are rotatably arranged about an axis 18. The mechanical interface 6 is designed here as a rotatable shaft extending horizontally. The rotor 3 and the mechanical interface 6 are arranged coaxially with the axis 18. The rotor 3 is non-rotatably connected to the mechanical interface 6 via a fastening section 7.

[0086] The rotor 3 has a first rotor part 3.1 and a second rotor part 3.2, wherein the first rotor part 3.1 is configured to receive a braking effect and the second rotor part 3.2 is configured to dampen the braking effect before it is transmitted via the mounting section 7 to the mechanical interface 6. P240626

[0087] - 14 -

[0088] To dampen the braking effect, the second rotor part 3.2 is designed to be deformable, i.e., it can deform circumferentially with respect to the axis 18 and relative to the first rotor part 3.1, whereby vibrations of the first rotor part 3.1 can be dampened by a damping effect caused by the material of the second rotor part 3.2. For this purpose, the second rotor part 3.2 consists of an elastomer or incorporates an elastomer that, through deformation work, dampens vibrations of the first rotor part 3.1 and transmits them not, or only in a damped form, to the mechanical interface 6.

[0089] The brake 1 shown has an interior space 8 that extends annularly around the axis 18 and is axially bounded by the housing sections 9 and 10. Furthermore, the interior space 8 is internally bounded radially by the sliding sealing elements 11 and 12. The left sealing element 11 is located on the housing section 9, and the right sealing element 12 is located on the housing section 10. Both sealing elements 11 and 12 extend axially with respect to the axis 18 and contact the rotor 3, or more precisely, a third rotor part 3.3 of the rotor 3, from both sides. Externally, the interior space 8 is bounded radially by a stator 2, with the interior space 8 being sealed by a sealing element 13 located between the housing section 9 and the stator 2, and by a sealing element 14 located between the housing section 10 and the stator 2. A magnetorheological powder is provided in the interior space 8, which is thus sealed off from the environment.The housing section 10 also serves to support the mechanical interface 6 by providing a bearing 15.

[0090] The first rotor part 3.1 and the stator 2 are spaced apart radially with respect to the axis 18, forming a gap 4 that is bounded radially on the inside by the first rotor part 3.1 and radially on the outside by the stator 2. The gap 4 extends rotationally symmetrically around the axis 18. The rotor 3 can therefore rotate within the stator 2 around the axis 18. In other words, the stator 2 surrounds the rotor 3 circumferentially with respect to the axis 18.

[0091] Within the gap 4, a magnetic field generator 5, such as a coil, is provided. The magnetic field generator 5 is designed to produce a magnetic field to generate the braking effect on the first rotor part 3.1. This field propagates through the gap 4 and the magnetorheological powder contained therein, and its field lines propagate further through the first rotor part 3.1 and the stator 2, resulting in a closed field line pattern. Chains are formed within the powder, which extend radially with respect to axis 18 as a result of the magnetic field and are described in P240626.

[0092] - 15 -

[0093] The powder particles are held together by the magnetic field. When the rotor 3 rotates around the axis 18, these chains, which ultimately also adhere at their ends to the surfaces of stator 2 and first rotor part 3.1 that define the radial gap 4, are sheared off circumferentially. This creates a friction point in the circumferential direction between the sheared chains or between the powder and the corresponding surfaces of stator 2 or first rotor part 3.1. This friction results in a braking effect on the first rotor part 3.1. Due to this mechanism for forming the friction point and adjusting the braking effect, the friction point can shift radially within the powder or spontaneously form at a specific radial location within the powder. This can lead to stick-slip effects and frictional vibrations, which impair the brake's NVH (noise, vibration, and harshness) performance.Due to the damping effect of the second rotor part 3.2, the impact of such effects is not transmitted from the first rotor part 3.1 via the second rotor part 3.2 to the mechanical interface 6. Therefore, for example, a user connected to the mechanical interface 6 will not experience any such effects, or at least will only experience a dampened effect. This damping is achieved through the material damping of the second rotor part 3.2, as described above.

[0094] It can also be seen that the radial extent 17 of the first rotor part 3.1 essentially corresponds to, or is even identical to, the radial extent 16 of the stator 2. This means that the material thickness of the first rotor part 3.1 and the stator 2 is the same in the radial direction. The magnetic field, which penetrates the gap and the powder, also penetrates the stator 2 and the first rotor part 3.1, as described above. The second rotor part 3.2, which adjoins the first radial part, prevents further propagation of the magnetic field in the rotor 3, since the second rotor part 3.2 has a comparatively high magnetic resistance due to its elastomer content. This means that the magnetic field lines are essentially contained within the first rotor part 3.1 before re-entering the gap 4 and then the stator 2. Undesired straying of the magnetic field in the rotor 3 is prevented by the second rotor part 3.2, which is made, for example, of an elastomer.In order to achieve a uniform propagation of the magnetic field and in particular a uniform and identical magnetic flux in the first rotor part 3.1 and in the stator 2, the material thickness shown here, of the first rotor part 3.1 and stator 2, i.e. the radial extent 17 and the radial extent 16, is decisive.

[0095] In this embodiment, the rotor 3 has a third rotor part 3.3, which lies radially inside the second rotor part 3.2. This third rotor part 3.3 serves to attach the P240626.

[0096] - 16 -

[0097] Rotor 3 is attached to the mechanical interface 6, specifically to the mounting section 7. The third rotor part 3.3 is fastened to the mounting section 7 by means of a fastener 7.1, in this case a screw. This is therefore a detachable fastening of rotor 3 to the mechanical interface 6. This allows for the disassembly of mechanical interface 6 and rotor 3 by loosening the fastener 7.1, for example, for repair or maintenance.

[0098] The rotor 3 shown here has three parts. The first rotor part 3.1 is arranged radially on the outside and serves to interact the rotor 3 with the magnetic field generated by the magnetic field generator 5 and with the powder located in the gap 4. To keep the rotational moment of inertia as low as possible and to simultaneously enable the propagation of the magnetic field to be as uniform as possible, the first rotor part 3.1 has the same material thickness in the radial direction as the stator 2, i.e., that the radial extensions 16, 17 are as equal as possible. Extending radially from the first rotor part 3.1, the second rotor part 3.2 is arranged radially on the inside. It absorbs the braking effect acting on the first rotor part 3.1 and transmits it to the third rotor part 3.3, which is located further radially inwards. This transmission is damped due to the material damping of the second rotor part 3.2. The third rotor part 3.3 serves to attach the rotor 3 to the mounting section 7, so that the braking effect can be dampened and transferred to the mechanical interface 6.

[0099] According to the embodiment shown here, the rotor parts 3.1, 3.2, 3.3 are ring-shaped, so that the braking effect is always transmitted from the first rotor part 3.1 via the other two rotor parts 3.2, 3.3 to the mechanical interface 6. Because there is no direct, rigid connection between the first rotor part 3.1 and the mechanical interface 6, but rather the braking effect must always be transmitted via the damping second rotor part 3.2, the first rotor part 3.1 is vibration-damped or even vibration-isolated from the mechanical interface 6. This improves the operating characteristics of the brake 1 compared to a rigid connection.

[0100] The second rotor part 3.2 can be connected to the first rotor part 3.1, for example, by press-fitting or vulcanization. It is also conceivable that the first rotor part 3.1 and / or the second rotor part 3.2 have fastening elements that engage with each other when the two rotor parts 3.1, 3.2 are joined, such as interlocking grooves into which corresponding extensions of the other rotor part 3.2, 3.1 engage. In this way, the connection of the respective rotor parts 3.1, 3.2 can be ensured. P240626

[0101] - 17 -

[0102] The second rotor part 3.2 can be connected to the third rotor part 3.3, for example, by press-fitting or vulcanization. It is also conceivable that the third rotor part 3.3 and / or the second rotor part 3.2 have fastening elements that engage with each other when the two rotor parts 3.2 and 3.3 are joined, such as interlocking grooves into which corresponding extensions of the other rotor part 3.3 and 3.2 engage. In this way, the connection of the respective rotor parts 3.2 and 3.3 can be ensured.

[0103] Fig. 2 shows a schematic and exemplary sectional view of a magnetorheological brake according to a further embodiment of the invention.

[0104] The design and function of the magnetorheological brake 1 shown largely correspond to the design and function of the brake 1 shown in Fig. 1. Therefore, only the differences will be discussed below, and reference is otherwise made to the preceding description of Fig. 1. Identical elements are, moreover, designated with the same reference numerals.

[0105] In contrast to the embodiment in Fig. 1, the rotor 3 here does not have a third rotor part. Instead, the second rotor part 3.2 is directly connected to the mechanical interface 6. For this purpose, the mechanical interface 6 has a corresponding mounting section 7, which is implemented as a radially extended disk-like section of the shaft-shaped mechanical interface 6.

[0106] This embodiment results in a less complex rotor 3, which here only has the first rotor part 3.1 and the second rotor part 3.2.

[0107] To attach the rotor 3 to the mechanical interface 6, the second rotor part 3.2 can be connected to the mounting section 7 by press-fitting or vulcanization. It is also conceivable that the mounting section 7 and / or the second rotor part 3.2 have fastening elements that engage with each other when the mounting section 7 and the second rotor part 3.2 are joined, such as interlocking grooves into which corresponding extensions of the respective elements 3.2 and 7 engage. In this way, the connection between the mounting section 7 and the second rotor part 3.2 can be ensured.

[0108] Fig. 3 shows a schematic and exemplary sectional view of a brake according to a further embodiment of the invention. P240626

[0109] - 18 -

[0110] The design and function of the magnetorheological brake 1 shown largely correspond to the design and function of the brake 1 shown in Fig. 1. Therefore, only the differences will be discussed below, and reference is otherwise made to the preceding description of Fig. 1. Identical elements are, moreover, designated with the same reference numerals.

[0111] The brake 1 shown here has a rotor 3, the second rotor part 3.2 of which has axially extending sealing elements 3.4. A first sealing element 3.4 extends to the left and a second sealing element 3.4 extends to the right. The first sealing element 3.4 contacts an inner wall of the housing section 9 on the left. The left sealing element 3.4 contacts an inner wall of the housing section 10 on the right. Both sealing elements 3.4 are integrally formed with the second rotor part 3.2 and are also made of the same elastomer as the second rotor part 3.2.

[0112] The two sealing elements 3.4 close or seal the interior 8 radially. Powder can then no longer escape radially from the interior. The sealing elements 3.4 are designed here as sliding sealing elements 3.4, which slide along the inner wall of the housing section 9 or the housing section 10 when the rotor 3 rotates about the axis 18.

[0113] In this way the interior 8 can be sealed, eliminating the need for separate sealing elements 11, 12 as shown in Figures 1 and 2.

[0114] Due to the one-piece formation of the second rotor part 3.2 and sealing elements 3.4, it is possible to manufacture the second rotor part 3.2 and the sealing elements 3.4 in one manufacturing step, e.g. a casting process.

[0115] The second rotor part 3.2 shown here is described in connection with the embodiment shown in Fig. 1, but it is equally conceivable to design the second rotor part 3.2 shown in Fig. 2 in such a way that it has corresponding sealing elements.

[0116] Fig. 4 shows a diagram illustrating the operating ranges of a prior art magnetorheological brake, and Fig. 5 shows a diagram illustrating the operating ranges of a magnetorheological brake according to the invention. A prior art brake is understood here as a brake without a corresponding second rotor section designed for damping. P240626

[0117] - 19 -

[0118] The structure of both diagrams is the same. That is, the horizontal axis represents the rotational speed of rotor 3, as shown in Figures 1 to 3, while the vertical axis represents the braking torque acting on rotor 3.

[0119] Two operating ranges 30, 31 are shown. The first operating range 30 is the operating range that allows safe or reliable operation of the brake, i.e., operation in which no stick-slip effects occur that would then be negatively noticeable at the mechanical interface 6.

[0120] As can be seen in Fig. 4, this area is pronounced for high rotational speeds over the entire possible braking torque, so that the brake can be operated here without a stick-slip effect at the mechanical interface 6.

[0121] However, if the rotational speed is lower, the first area 30 decreases and the second area 31 increases, where corresponding stick-slip effects are to be expected at the mechanical interface 6. These occur particularly at high braking torques, with area 31 becoming larger at lower rotational speeds.

[0122] By switching to a rotor 3 according to the present invention, i.e., a rotor 3 with a damping-acting second rotor part 3.2, as shown in Figures 1 to 3, the area 30 in which no stick-slip effects are transmitted to the mechanical interface 6 can now be greatly enlarged. Figure 5 clearly shows that the area 30 now extends almost over the entire rotational speed and that the area 31 is only pronounced at low rotational speeds and high braking torques. Thus, the invention represents an improvement in the NVH behavior of a magnetorheological brake.

[0123] Fig. 6 shows a schematic representation of a force feedback actuator, according to a further aspect of the invention.

[0124] The force feedback actuator 50 shown has a magnetorheological brake 1, which can be designed like the brake 1 from Figures 1 to 3. The force feedback actuator 50 also has a drive unit 51. The drive unit 51 can be designed as an electric motor or include an electric motor. P240626

[0125] - 20 -

[0126] The force feedback actuator 50 has a mechanical interface 52 that extends vertically in the drawing and is designed as a shaft. The shaft is rotatable about the vertically extending axis 53 and is oriented coaxially with the axis 53. The mechanical interface 52 is designed to be connected to an input element. This can be, for example, a joystick, a rotary knob, or a steering element such as a steering wheel. The input element can be connected to the mechanical interface 52, for example, at its upper free end.

[0127] Brake 1 and drive unit 51 are connected to the mechanical interface 52. For example, the mechanical interface 52 can be connected to the mechanical interface 6 of one of the brakes 1 from Figures 1 to 3, so that the rotor 3 can apply a braking torque generated by the brake 1 to the mechanical interface 52. In this case, the mechanical interface 52 represents an extension of the shaft-shaped mechanical interface 6 from Figures 1 to 3, wherein the mechanical interface 52 is, for example, connected to or identical with the mechanical interface 6. The drive unit 51 is configured to apply a drive torque to the mechanical interface 52. The drive unit 51 can preferably be configured to apply the drive torque to the mechanical interface 52 in both directions of rotation.

[0128] By appropriately controlling the brake 1 and the drive unit 51, e.g. by a control unit (not shown) of the force feedback actuator 50, haptic feedback can be generated which is perceptible to a user at the mechanical interface 52 or at an input element coupled to it in a torque-transmitting manner.

[0129] Fig. 7 shows a schematic representation of a steering device for a vehicle, according to a further aspect of the invention.

[0130] As part of the steering system 100, the force feedback actuator 50 shown above in Fig. 6 is shown here, which is enclosed by a dashed box. For its description, please refer to the description of Fig. 6.

[0131] A torque-transmitting input element 101, designed here as a steering element, e.g., a steering wheel, is coupled to the mechanical interface 53. A user can thus receive haptic feedback directly via the steering element, in the form of a braking torque from the brake 1 and / or in the form of a drive torque from the P240626.

[0132] - 21 -

[0133] The drive unit 51 of the force feedback actuator 50 is applied to the mechanical interface 52.

[0134] The steering device 100 shown can be configured as a steer-by-wire steering device. In this configuration, the mechanical interface 52 is not connected to, or designed for, the steered wheels of a vehicle. Haptic feedback about the current driving state of the steered wheels, e.g., through a return torque at the input element 101, is not possible here due to the lack of a mechanical connection between the wheels and the steering element. This feedback can instead be provided by the integrated force-feedback actuator 50, by controlling the drive unit 51 and / or the brake 1 accordingly, e.g., by a control unit (not shown) of the force-feedback actuator 50 or the steering device 100. In this way, eliminating the mechanical connection to the wheels results in a space-saving advantage for the steering device 100 and / or the vehicle.

[0135] However, it is also conceivable that the steering device 100 is designed for mechanical coupling with the steered wheels of a vehicle. In this case, it is possible to supplement the haptic feedback, which is perceptible via the mechanical coupling with the steered wheels, by the drive torque of the drive unit 51 and / or by the braking torque of the brake 1, by controlling the drive unit 51 and / or the brake 1 accordingly, e.g. by a control unit (not shown) of the force feedback actuator 50 or the steering device 100, in order to set a desired steering feel.

[0136] The embodiments of the invention described here in connection with the figures and the embodiments described above in the general part of the description can be combined with each other as desired.

[0137] P240626

[0138] - 22 -

[0139] Reference symbol list

[0140] 1 magnetorheological brake

[0141] 2 Stator

[0142] 3 Rotor

[0143] 3.1 First rotor part

[0144] 3.2 Second rotor part

[0145] 3.3 Third rotor part

[0146] 3.4 Sealing element

[0147] 4 columns

[0148] 5 coil

[0149] 6 mechanical interface

[0150] 7 Mounting section

[0151] 7.1 Fastening element

[0152] 8 Interior

[0153] 9 Housing section

[0154] 10 Housing section

[0155] 11 Sealing element

[0156] 12 Sealing element

[0157] 13 Sealing element

[0158] 14 Sealing element

[0159] 15 warehouses

[0160] 16 radial extension

[0161] 17 radial extension

[0162] 18 axle

[0163] 30 first operating area

[0164] 31 second operating area

[0165] 50 Force feedback actuator

[0166] 51 Drive unit

[0167] 52 mechanical interface

[0168] 53 axle

[0169] 100 Steering device

[0170] 101 Input element

Claims

P240626 - 23 - Claims 1. Magnetorheological brake (1) comprising: a rotor (3) rotatably arranged about an axis (18), a mechanical interface (6) rotatably arranged about the axis (18), and a fastening section (7) via which the rotor (3) is non-rotatably connected to the mechanical interface (6), wherein the rotor (3) comprises a first rotor part (3.1) and a second rotor part (3.2), wherein the first rotor part (3.1) is configured to receive a braking effect and the second rotor part (3.2) is configured to dampen the braking effect before transmission via the fastening section (7) to the mechanical interface (6).

2. Brake (1) according to claim 1, wherein the second rotor part (3.2) has an elasticity of 150 to 1500 N / mm² 2and / or has a loss factor of at least 0.01, and / or wherein the second rotor part (3.2) comprises a rubber material and / or a plastic, such as an elastomer or polyethylene, or consists of a rubber material and / or a plastic, such as an elastomer or polyethylene.

3. Brake (1) according to one of the preceding claims, comprising a stator (2) which is fixed relative to the rotor (3), wherein the rotor (3) and the stator (2) are spaced apart from each other in the radial direction with respect to the axis (18) and a gap (4) is provided between the rotor (3) and the stator (2) in which a magnetorheological powder is provided, wherein the brake (1) is configured to generate a magnetic field which penetrates the gap (4) and the magnetorheological powder contained therein in order to generate the braking effect on the first rotor part (3.1).

4. Brake (1) according to claim 3, wherein the radial extent (17) of the first rotor part (3.1) substantially corresponds to the radial extent (16) of the stator (2), and / or wherein the radial extent of the second rotor part (3.2) is less than or equal to the radial extent (17) of the first rotor part (3.1).

5. Brake (1) according to claim 3 or 4, P240626 - 24 - wherein the brake (1) has an interior space (8) in which the magnetorheological powder is received, wherein the rotor (3) has at least one sealing element (3.4) which seals the interior space (8) in the radial direction with respect to the axis (18), wherein the at least one sealing element (3.4) is in particular formed integrally with the second rotor part (3.2).

6. Brake (1) according to one of the preceding claims, comprising a third rotor part (3.3) configured to connect the rotor (3) to the mounting section (7), or wherein the second rotor part (3.2) is connected to the mounting section (7).

7. Force feedback actuator (50) comprising: a drive unit, a magnetorheological brake (1) according to any one of claims 1 to 6, and a mechanical interface.

8. Steering device (100) for a vehicle, comprising: an input element designed as a steering element, a force feedback actuator according to claim 7 or a magnetorheological brake (1) according to any one of claims 1 to 6, wherein the input element is rotationally fixed to the mechanical interface of the force feedback actuator or rotationally fixed to the mechanical interface (6) of the brake (1).

9. Rotor (3) for a magnetorheological brake (1) according to one of claims 1 to 6.

10. Method for manufacturing a rotor (3) for a magnetorheological brake (1) comprising the steps: Providing a first rotor part (3.1) and a second rotor part (3.2), connecting the first rotor part (3.1) to the second rotor part (3.2).

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