STEERING DEVICE WITH A MAGNETORHEOLOGICAL BRAKE DEVICE AND METHOD FOR OPERATING A STEERING DEVICE

Description

[0001] The invention relates to a steering device for controlling a vehicle by means of a movable steering unit, as well as a method for operating a steering device. The steering device comprises a magnetorheological braking device with a stationary support and at least two braking components that are continuously rotatable relative to one another about a rotation axis.

[0002] Such steering systems must meet stringent requirements. For example, they require precise steering feedback and steering behavior that is free of play or jerks, particularly around the center position, as well as overall smooth, harmonious steering behavior. Furthermore, the braking system must be able to provide high braking torques, for example, for hard end stops when the steering wheel is turning rapidly (i.e., high kinetic energy when the steering wheel is turned rapidly during maneuvering, for example, at 1000° / s). Due to the significant increase in the number of controls on the steering wheel, steering wheels are becoming increasingly heavy, which increases kinetic energy. High braking torques are also required when the driver (or user) holds or supports themselves on the steering wheel when getting in or out of the vehicle (for assistance in getting in or out). Such braking torques can be, for example, 25 Newton meters, 35 Newton meters, or more.

[0003] At the same time, the braking system must also be capable of delivering very low braking torques (less than 1 Newton meter, preferably less than 0.5 Newton meters), for example, when only very slight steering movements are required to maintain lane while driving straight ahead. Likewise, low braking torques are necessary for steering movements around the center position or when changing direction (e.g., 1 to 3 Newton meters) to ensure smooth vehicle control and allow for fast, yet smooth negotiation of winding roads. Overall, sensitive and precise steering is only possible with a very light steering system. For this purpose, braking torques of less than 1 Newton meter are desirable, for example.

[0004] Furthermore, different braking torques should be adjustable, ideally without noticeable transitions, or continuously and with high control quality. Furthermore, the braking torques should be adjustable with the shortest possible response times, for example, in less than 100 ms. However, the space available for the steering system is usually very limited, for example, in the dashboard of modern vehicles with a head-up display.

[0005] The aforementioned requirements are technologically very difficult to achieve. One problem is that high braking torques generally require corresponding friction diameters and sizes, which in turn disadvantageously increases the base torque (also known as the idle torque). However, a high base torque conflicts with the requirement for smooth steering.

[0006] For example, friction clutches are known that offer a high maximum braking torque. However, the friction surfaces required to achieve the braking torque cause unfavorably high base friction when de-energized, for example, one Newton meter of base friction at a maximum braking torque of 20 Newton meters.

[0007] Furthermore, steering systems with an electric motor have become known, which is coupled to the steering wheel either directly or via a reduction gear or (toothed) belt. Such directly mounted electric motors generate, for example, active braking torques (nominal torques) of up to eight newton meters and short-term passive braking torques of up to 25 newton meters. However, due to the correspondingly high braking torque, such electric motors are large and heavy, as well as sluggish (mass moment of inertia), and often expensive. Due to the large operating range, controllability at low braking torques requires improvement.

[0008] Electric motors that are transmitted via belt drives and mounted parallel to the steering train (indirect arrangement) should be designed more advantageously; the additional belt drive, belt wheels and brackets require space and cause compliance, play and additional costs.

[0009] Since electric motors in the steering system must primarily deliver the high braking torque at low speeds, the current or power requirement is also disadvantageously high. At the same time, electric motors have very poor efficiency at low speeds or when stationary (for example, to provide an end stop) and therefore often heat up very quickly. This, in turn, reduces efficiency because the coil resistance increases. This causes it to heat up even faster, causing everything to build up, and the power requirement rises rapidly and dramatically.

[0010] A steer-by-wire steering system for a motor vehicle with an electric motor and a magnetorheological brake is known from DE 10 221 241 A1.

[0011] Magnetorheological brakes with magnetorheological fluids are well-known in the art, for example, the MRF brake from Lord Corporation in various sizes (5 Nm, 12 Nm, 20 Nm): https: / / www.lord.com / products-andsolutions / steer-by-wire-tactile-feedback-device. These are also used, among other things, as "steer-by-wire tactile feedback." These brakes work in principle. However, a disadvantage of these MRF brakes is their relatively high base friction (base torque) in relation to the maximum torque (working range). According to Lord's website / specification, the operating range of the 5 Nm brake is 0.5 to 5 Nm (factor 10). The 12 Nm brake has a working range between 1 Nm and 12 Nm (factor 12), and the 20 Nm brake has a working range between 1 Nm and 20 Nm (factor 20). This relatively narrow working range is insufficient for many applications, which is why these series products are primarily used for coarse motor applications (e.g.Operation usually with gloves, such as in industry, with agricultural machinery, on forklifts...).

[0012] The documents DE 10 2017 111031 A1 and DE 10 2004 009906 B3 may be cited as further prior art.

[0013] For (predominantly) fine-motor applications such as steering a passenger car, a significantly lower base torque combined with a higher maximum torque is advantageous, thus providing a considerably larger operating range. A particularly high base torque, for example, quickly leads to fatigue when steering or is uncomfortable. However, the well-known MRF brakes do not allow for a large operating range because the friction surfaces are too large. Smaller friction surfaces would reduce the base torque, but this would also reduce the maximum torque, which would be particularly disadvantageous for steering systems.

[0014] In contrast, the object of the present invention is to provide an improved steering device. In particular, the steering device should meet the previously discussed requirements as closely as possible and, preferably, simultaneously offer reliable and safe operation and be economically producible.

[0015] This object is achieved by a steering device having the features of claim 1. The method according to the invention is the subject of claim 18. Preferred developments of the invention are the subject of the dependent claims. Further advantages and features of the present invention will become apparent from the general description and the description of the exemplary embodiments.

[0016] The steering device according to the invention serves to control (steer) a vehicle by means of a (at least partially manually) movable steering unit. Movement of the steering unit can be braked (in particular damped) by means of at least one magnetorheological braking device. The braking device comprises a stationary bracket and at least two braking components.

[0017] At least one of the at least two brake components is rotatable by the steering unit. In particular, the brake component is rotatably coupled to the steering unit. At least one other of the at least two brake components is connected to the holder in a rotationally fixed manner. The two brake components are continuously rotatable relative to one another about an axis of rotation. A first brake component extends along the axis of rotation. This means that the first brake component extends at least partially along the axis of rotation. Or that at least a section of the first brake component or preferably a substantial part of the first brake component extends along the axis of rotation. The first brake component comprises a core made of a magnetically conductive material. The second brake component comprises a hollow casing part that extends around the first brake component (in particular in the radial and / or axial direction).At least one circumferential gap, at least partially filled with a magnetorheological medium, is formed between the first and second brake components. The gap comprises at least two different brake gap sections. The brake gap sections are, in particular, radially formed. Additionally or alternatively, the brake gap sections can also be axially formed. A disc contour is formed between the shell part and the core in or on a first brake gap section. A plurality of rolling elements are arranged on the circumference of the core in or on a second brake gap section.

[0018] The steering device according to the invention offers many advantages. A significant advantage is the combination of the two different brake gap sections. The brake gap section with the disc contour can generate low yet particularly precisely controllable braking torques. The brake gap section with the rolling elements can generate particularly high braking torques, for example, for end stops or the entry / exit aid. A particular advantage is that both braking sections have a particularly low base torque. A further advantage is that such a braking device requires very little installation space overall and can be implemented with minimal design complexity and manufactured economically. Furthermore, the steering device according to the invention is particularly reliable because the brake gap sections enable redundancy.

[0019] The steering system can be used in motor vehicles (e.g., cars; on-highway vehicles), aircraft, airplanes, ships, boats, and in agricultural machinery, for example, tractors or combine harvesters, harvesters, and other field machinery for agriculture (off-highway vehicles). It can also be used in construction machinery, for example, forklifts or similar machines, or in simulators for simulating vehicle control (gaming, sim racing, computer peripherals, etc.). The steering system is particularly suitable for at least partially autonomous vehicles.

[0020] The steering unit can be designed, for example, as a steering wheel, a handlebar or handlebar, joystick, control horn, control pedal, control lever, or as a joystick, or even as a control wheel. Other designs of movable steering units for steering vehicles are also possible. The movement of the steering unit is, in particular, a rotational movement. In particular, the steering unit is movable in at least two directions of rotation. The movement of the steering unit can also be another type of movement. The steering device can comprise at least one transmission device which is suitable and designed to convert the movement of the steering unit into a rotational movement of one of the components of the braking device.

[0021] In all embodiments, it is preferred that the braking torque is adjustable in real time.

[0022] In particular, the steering device comprises at least one actuator device for converting a steering movement executed by the steering unit into a vehicle movement. In particular, the steering unit and the actuator device are only electrically and / or only electromagnetically connected. In particular, the steering unit and the actuator device are not mechanically coupled (during normal operation). A mechanical coupling can be provided in emergency operation. In particular, the steering device is a steer-by-wire steering system. This also includes steer-by-wire steering systems which engage the steering line in special situations, such as an emergency or a fail-safe situation, thus in particular providing a mechanical coupling between the steering unit or driver and the wheel. In such an embodiment, the invention offers particularly many advantages.

[0023] However, it is also possible for the steering system to be designed as a mechanical steering system, preferably a power steering system. Even with such a steering system, the two different brake gap sections can be used advantageously.

[0024] When the magnetorheological medium is actively influenced, the braking device has, in particular, a braking torque. When the magnetorheological medium is inactively influenced, the braking device has, in particular, a base torque. The base torque is at least 50 times lower, preferably at least 90 times lower, and particularly preferably at least 100 times lower than the maximum braking torque that can be provided by the braking device. This offers a particularly large operating range. This offers particularly advantageous steering behavior and can be implemented particularly well with the braking device presented here. The movement resistance of the steering unit results, in particular, in a torque that is composed of at least the braking torque and the base torque.

[0025] It is possible and advantageous for the braking device to have a base torque of a maximum of 0.5 Newton metres and preferably a maximum of 0.25 Newton metres and particularly preferably a maximum of 0.1 Newton metres when the magnetorheological medium is inactively influenced.

[0026] In particular, the braking device can generate a maximum braking torque of at least 25 Newton meters and preferably at least 45 Newton meters and particularly preferably at least 50 Newton meters by actively influencing the magnetorheological medium.

[0027] In all embodiments, it is preferred and advantageous that the second brake gap section can generate a braking torque that is at least twice as high as the first brake gap section. In particular, the second brake gap section can generate a braking torque that is at least three times, preferably at least five times, and particularly preferably at least ten times as high as the first brake gap section.

[0028] In particular, only a portion, and preferably less than half, of the maximum braking torque can be generated with the first brake gap section. In particular, less than a quarter, and preferably less than an eighth, of the maximum braking torque can be generated with the first brake gap section. In particular, a braking torque can be generated with the first brake gap section that lies between zero Newton meters and ten Newton meters, preferably between zero Newton meters and eight Newton meters, and particularly preferably between zero Newton meters and five Newton meters. Such braking torques can be adjusted with particularly high control quality using the first brake gap section.

[0029] In particular, a predominant part and preferably at least two-thirds of the maximum braking torque can be generated with the second brake gap section. In particular, at least three-quarters or even at least 90% of the maximum braking torque can be generated with the second brake gap section alone. It is possible for the maximum braking torque to be generated with the second brake gap section alone. It is possible for the first brake gap section to be activated for support at the same time as the second brake gap section. With such braking torques, the second brake gap section can be used particularly advantageously, since its properties with regard to controllability do not represent a disadvantage.

[0030] It is preferred and advantageous that a braking torque can be adjusted with a higher resolution using the first brake gap section than with the second brake gap section. Preferably, the first brake gap section has a resolution at least ten times higher than the second brake gap section.

[0031] In particular, a braking torque with a resolution of at least 0.5 Newton meters and preferably at least 0.25 Newton meters and particularly preferably at least 0.15 Newton meters can be generated with the first brake gap section.

[0032] In all embodiments, it is preferred and advantageous for a first electrical coil to be assigned to the first brake gap section and a second electrical coil to be assigned to the second brake gap section. In particular, the coils can be controlled separately. In particular, the coils serve to generate a (magnetic) field to influence the magnetorheological medium. In particular, the coils can be controlled (in particular intelligently) by the steering control unit (described below). Such a configuration enables particularly sensitive steering behavior and also offers reliable redundancy.

[0033] It is also possible for the at least two brake gap sections to be supplied by a common coil. In this case, for example, at least one electrical coil is provided between the casing part and the core, wound around the rotational axis and surrounding the core.

[0034] In special / borderline cases or emergencies, the electric motor can be switched on, thus further increasing the maximum braking torque.

[0035] The steering device comprises, in particular, at least one steering control unit for controlling the braking device. In particular, the steering control unit allows the braking torques of the at least two brake gap sections to be adjusted independently of one another. In particular, the steering control unit serves to control the braking device depending on a position of the steering unit and / or depending on a movement parameter of the steering unit and / or depending on an operating state of the vehicle and / or depending on "data."

[0036] "Data" can include, for example: vehicle data such as speed, lateral acceleration, spatial position, braking values, GPS position, environment detection, data / position of other vehicles (in the vicinity of the vehicle), trailer yes / no, load, passenger data (height, weight, clothing, seating position, analysis data based on the evaluation of this data with, for example, artificial intelligence and suggestions; sounds, gestures), external data (e.g., the driver's home sends data to the car; parking garage data in a parking garage...).

[0037] A person's steering behavior in winter wearing a thick coat is different than in summer wearing thin clothing. The thick coat restricts freedom of movement, resulting in different steering behavior. If the control electronics detect this based on "data," the behavior can be adjusted. For example, a quick steering maneuver to evade is more difficult (physically heavier) with a thick, tight-fitting coat and, in reality, slower. This can be intelligently counteracted by increasing the ratio of steering angle at the steering wheel to steering angle at the wheel(s), so that the evasive maneuver is still quick. Furthermore, the necessary steering effort (assistance) can be reduced, as the heavy coat acts as a damper.

[0038] If, based on the "data" and / or near-field detection, it is detected, for example, that the driver is fatigued and steering carelessly, this can be intelligently compensated for. The driver can be warned (by ripples or vibrations), or the steering unit can interpret the driver's command (turning the steering wheel) differently using artificial intelligence, for example, so that the steering wheel movement is not directly reflected in the wheel adjustment. On a straight road (highway), this can prevent the vehicle from "weaving" and rocking.

[0039] On the other hand, such intelligent electronics can detect fatigue based on data analysis (steering movements, facial recognition, unusual driver movement patterns, temperature, breathing noises, etc.) and intervene (warning; reducing speed to a standstill; autonomous parking, etc.). This is particularly advantageous in cases of dizziness, heart attack, or similar conditions.

[0040] Steering or moving the vehicle can also be prevented if the data analysis detects that a child is behind the wheel (force, gripping, near-field detection). In cases of doubt, the steering torque can be briefly increased to determine whether the driver has sufficient strength to start the vehicle, which is not the case with children.

[0041] The vehicle (machine learning / artificial intelligence / GPS data, etc.) knows, for example, that a pothole or a deep rut is about to occur, which causes the driver to steer the vehicle erratically or incorrectly (the rut pulls too far toward the edge, etc.) due to this (body movement, pulling on the steering wheel, etc.). The intelligent braking unit counteracts this unnecessary or dynamically poor steering movement so that the destination is reached smoothly, safely, and comfortably.

[0042] The same applies to snow, slippery surfaces, stones, etc. The steering adjusts specifically to this, and the active and passive torque are adjusted accordingly. If a vehicle slides while cornering in winter (e.g., understeering) due to slippery surfaces (snow, ice, etc.), the driver usually oversteers out of panic. As soon as the vehicle regains traction, it turns too sharply due to the steering, which leads to accidents. In these cases, the steering torque should be increased, or the driver should be given haptic feedback (e.g., in the form of a ripple) to encourage them to oversteer.

[0043] The opposite is true when drifting (e.g., in winter, in snow and ice). In this case, the inexperienced driver usually steers too little, causing the vehicle to "lose" control and skid. In this case, the steering can be made very light, which encourages oversteering.

[0044] Some people prefer to hold the steering wheel at the top (between 10 and 2 o'clock). This leads to more steering angle changes when subjected to vibrations, or the steering wheel is harder to hold steady in this position, or it can even swing up (also known as motion sickness). If the interior monitoring system detects this steering wheel position, the torque can be increased slightly, resulting in smoother driving.

[0045] Shorter people also have a very different steering wheel posture than taller people, as well as different lever distances due to their different limb lengths. Shorter arms require more frequent re-gripping for larger steering wheel movements, which leads to more unstable steering maneuvers. If re-gripping or adverse kinematic arm positions are detected ("data," near-field detection; analysis of the angle of rotation, etc.), the control unit or artificial intelligence can "calm" this process, i.e., make it more harmonious.

[0046] This can also be an advantage if the driver has been on the road for a long time.

[0047] Haptic feedback can be provided when changing lanes. When changing lanes, a different type of feedback is provided. This all works in conjunction with the "data" (e.g., navigation system, environment detection, etc.). The steering system, in particular, provides corresponding feedback.

[0048] The invention is also advantageous in the following situations: Parking spaces or parking areas in cities or parking garages are expensive and should be used as efficiently as possible. The parking spaces could be of different sizes and ideally assigned to the vehicle via a data packet (radio, Wi-Fi, 5G, etc.) when entering the parking garage. When parking, the "intelligent parking garage" should support the parking process, i.e., specify the ideal parking position and transmit it to the parked vehicle. The intelligent steering then executes this or makes suggestions, which the driver may or may not accept and execute (e.g., if an object not recognized by the parking garage is in the parking space). The "intelligent parking garage" also knows and communicates whether the neighboring vehicle had a passenger or not, meaning the driver's own vehicle can be parked closer to the passenger door.The user of the neighboring vehicle could also leave a parking space and inform the "parking garage" that they are returning with a passenger. If a vehicle is parked for a long time and this is reported to the smart parking garage or parking area, and the one next door is parked for a shorter time, it could even be parked close to the vehicle door, which would save a lot of parking space. When purchasing tickets online, for example, in airport parking garages, the exact parking duration is already known.

[0049] In advantageous configurations, the parking process using the steering system and thus the distance to the next vehicle could also be adjusted to the required door opening angle so that the driver or passengers can enter and exit smoothly. Based on this "data," the vehicle knows the opening angle and the body dimensions of the passengers. The intelligent parking garage can also detect / recognize these necessary distances and intelligently distribute (or utilize) them.

[0050] If the intelligent steering system detects, based on the "data," that the driver is driving in areas that shouldn't be entered (e.g., pedestrian zones, bike paths, restricted areas, approaching a building, etc.), it can provide haptic feedback, even leading to intervention (countersteering; bringing the vehicle to a standstill). However, preferably, a warning feedback is always provided first, and the driver can override it (so it's not patronizing, but usually just a warning).

[0051] In particular, the position of the steering unit can be described by a rotation angle (relative or absolute). The motion parameter comprises, in particular, at least one parameter from a group of parameters, including: speed, angular velocity, torque, acceleration (negative and positive), and duration. For example, targeted braking can be performed in the event of an excessively rapid steering movement.

[0052] To control the braking device depending on the aforementioned parameters, at least one sensor device is provided for detecting these parameters. In particular, the steering control unit is operatively connected to at least one such sensor device. The position and / or the movement parameter can be detected by sensors on the steering unit and / or on the braking device. For example, the braking device comprises at least one sensor device for detecting a relative position of the first component to the second component.

[0053] The operating state is defined in particular by at least one parameter from a group of parameters, comprising: vehicle speed, vehicle acceleration (negative and positive), wheel position, rudder position, steering angle, load state, user profile, outside temperature, inside temperature, weather conditions, time of year, traffic situation, road condition or terrain condition, control variables of safety systems or assistance systems.

[0054] The steering control unit is preferably suitable and configured to select at least one brake gap section of the at least two brake gap sections depending on the level of a braking torque to be set, and at least thereby to brake the movement of the steering unit. In particular, the steering control unit takes into account the maximum braking torque that can be generated with the respective brake gap section. In particular, at least one value range of the adjustable braking torque is assigned to each of the at least two brake gap sections. Depending on the value range within which the braking torque to be set lies, the appropriate brake gap section can be selected.

[0055] The steering control unit is preferably suitable and configured to generate a braking torque for braking the movement of the steering unit at least predominantly, and preferably only, with the first brake gap section when the vehicle speed is above a limit value (and the vehicle is operating normally). Such a limit value is, for example, 15 km / h or 25 km / h. At these or higher speeds, the braking torques must be set with a particularly high resolution to avoid negatively affecting the steering behavior.

[0056] The steering control unit is particularly suitable and designed to block the mobility of the steering unit and to generate the necessary braking torque predominantly, and preferably only, with the second brake gap section. In particular, the mobility of the steering unit can be blocked by means of the braking device. In particular, this can provide a steering lock. In particular, this can provide a support option on the steering unit. For example, the blocked steering unit can be used for holding on when getting in and / or out of the vehicle.

[0057] In particular, the steering control unit is suitable and designed to generate an end stop for the mobility of the steering unit at least predominantly, and preferably only, with the second brake gap section. Such an end stop is generated, for example, when the wheels or a rudder have reached the end of their intended travel path.

[0058] The steering system can include, for example, a steering wheel. Vehicles usually have various functions built into the steering wheel, such as buttons, knobs, and dials for operating the on-board computer, as well as displays, steering wheel heaters, etc., all of which require power and must receive and transmit signals. The electrical connection can be via friction contacts, inductive, wireless, or a clock spring.

[0059] It is advantageous and preferred that the steering control unit is suitable and configured to brake or even block the mobility of the steering unit depending on a driver assistance system. This can prevent critical steering movements. In particular, the steering control unit selects at least one of the at least two brake gap sections and controls it. For example, the first brake gap section is selected for sensitive braking, and the second brake gap section is selected for locking.

[0060] A lane keeping system, for example, can be provided as a driver assistance system. This can prevent lane departure by braking the steering unit or issue a warning to the driver (e.g., if the driver assistance system detects a critical driving situation, such as a vehicle swerving), and can prevent hectic steering movements and / or oversteering by selectively braking the steering unit.

[0061] The driver assistance system can also include a parking aid. In this case, braking or locking the steering unit can prevent contact of the wheels with an obstacle (e.g., a curb). In particular, the steering control unit and / or the driver assistance system comprise at least one sensor device for detecting such situations (surround view, image recognition, radar, lidar, etc.). Such a sensor device can, for example, comprise an environmental sensor system and / or a GPS system.

[0062] It is possible for the steering control unit to be suitable and configured to take a user characteristic into account when adjusting the braking torque. For example, the user characteristic may include a seating position, user height, user weight, user clothing, and / or the user's ability to drive. The user characteristic may be stored in a user profile and / or be detectable by sensors. For example, near-field detection and / or an internal camera (e.g., with image / face recognition) are provided for this purpose.

[0063] The steering control unit is particularly suitable and designed to adjust the braking torque depending on the position in which the steering unit is held. This allows an unfavorable steering position to be compensated for by a higher braking torque, preventing unwanted steering movements, for example, when driving over potholes.

[0064] In all embodiments, it is preferred and advantageous that the steering control unit is suitable and designed to generate haptically perceptible feedback on the steering unit. The feedback comprises, in particular, a defined sequence of braking torques. For example, such feedback can be perceived as a vibration on the steering unit. Rattling and / or jerking (rippling) can also be perceptible. It is possible for the braking torques to be generated with an adjustable frequency. In particular, such feedback can be generated depending on the position and / or movement parameter of the steering unit and / or an operating state of the vehicle and / or the user characteristic. For example, the feedback can serve as a warning in the event of dangerous maneuvers or to wake up in the event of fatigue. The feedback can also serve as a signal for a lane change.

[0065] In all embodiments, it is preferred that the steering control unit is suitable and designed to determine user behavior by means of at least one machine learning algorithm (also referred to as artificial intelligence) and to take this into account when setting the braking torque. For this purpose, data is continuously recorded and evaluated. For example, the movement of the steering unit can be dampened depending on existing muscle strength, fatigue, or driving behavior. Image recognition can support this. If this detects a distorted face (a certain gesture) when parking, for example, the assistance force can be increased. It is also possible to take age-related changes to the steering device or other parts of the vehicle into account.

[0066] The magnetorheological medium preferably comprises at least one metallic powder. In particular, the metallic powder has a volume fraction of at least 50% and preferably at least 60% or even at least 70%. Using such a medium allows a particularly low base torque to be achieved. At the same time, due to the high volume fraction, a particularly high maximum braking torque can be achieved. Furthermore, such a medium can be used with consistent properties at the temperatures expected for the steering system. The powder is particularly absorbed in a gaseous carrier medium, for example, air.

[0067] The metallic powder is preferably formed as carbonyl iron powder (pure iron) or at least comprises such a powder. Other magnetorheologically responsive powders are also possible.

[0068] Particularly preferably, the metallic powder is provided with a coating.

[0069] The steering device can comprise at least one remanence device and / or at least one permanent magnet unit, which is suitable and configured to maintain a braking torque with at least one of the at least two brake gap sections even without the supply of electrical current. The remanence device is, in particular, operatively connected to the steering control unit. In particular, the remanence device is provided by at least one of the coils.

[0070] The steering device can comprise at least one safety device. The safety device is particularly suitable and designed to at least partially remove the magnetorheological medium from the gap. In particular, the safety device can remove the medium at least to the extent that the steering unit is essentially freely movable. In particular, the safety device can eliminate the braking torque and / or the base torque. For example, the magnetorheological medium is removed from the gap by means of overpressure and / or negative pressure. The safety device can comprise at least one pressure vessel and / or a detonator or the like. Such a safety device serves as an emergency system (so-called fail-safe mechanism) in the event of a malfunction of the braking device.

[0071] In all embodiments, it is particularly preferred that the braking device, in particular the first and / or second component and / or the gap, has a maximum diameter of less than 100 mm (in particular at a maximum braking torque of at least 25 Nm). This allows the braking device to be accommodated in a particularly space-saving manner (e.g., in the dashboard). The braking device presented here is particularly well suited for such a maximum diameter.

[0072] In all embodiments, it is preferred that the steering device comprises at least one drive device for generating a drive torque for the active movement of the steering unit. The drive device serves, in particular, to generate a drive torque against which the steering unit must be manually moved. The drive device can also serve to return the steering unit to a home position. In particular, the drive device comprises at least one electric drive and, for example, an electric motor. The electric motor can also be a disc rotor, traveling wave motor, or axial flux motor. Additionally or alternatively, the drive device can also comprise at least one energy accumulator and, for example, a spring or the like.

[0073] In particular, the maximum braking torque of the second brake gap section is at least twice the maximum drive torque of the drive device. In particular, the drive device can generate a maximum drive torque of less than or equal to twelve newton meters and preferably less than or equal to eight newton meters.

[0074] In the event of a drive device failure, the braking device can preferably provide a braking torque that is at least as high as its drive torque. Such a steering device is particularly safe and reliable because the two brake gap sections, together with the ability to compensate for the drive device, offer triple redundancy.

[0075] The braking system presented here, in combination with the drive system, offers the particular advantage that the drive system and, for example, an electric motor can be significantly smaller. Furthermore, all torques that need to be applied passively can be absorbed by the braking system. This allows for electrical energy savings, which is particularly advantageous for electric vehicles.

[0076] The much smaller (and weaker) electric motor also makes it less likely for the driver to yank the steering wheel out of their hands in the event of a malfunction (e.g., a faulty sensor signal). Furthermore, the magnetorheological braking unit can counteract and overbrake the electric motor if implausible conditions are detected (the electric motor tries to turn sharply even though the vehicle is traveling at high speed on a highway).

[0077] It is preferred and advantageous that the steering control unit is suitable and configured to at least approximately compensate (adjust) fluctuations in the drive torque of the drive device by adjusting the braking torque (in particular with the first braking gap section). In particular, the fluctuations can be compensated to such an extent that they are no longer haptically perceptible on the steering unit. Such fluctuations particularly relate to changes in the drive torque across the angle of rotation. In particular, the steering control unit is suitable and configured to regulate the drive torque essentially constantly across the angle of rotation.

[0078] The disc contour can comprise at least one star contour. In particular, a variable gap height is created in the area of ​​the star contour over the circumference of the brake gap section. In particular, magnetic field concentrators are arranged on the star contour. In particular, the magnetic field concentrators extend radially into the brake gap section. Such a star contour reduces the friction surface between the parts rotating relative to each other, thereby reducing the base torque. At the same time, the star contour creates a so-called cluster formation for the magnetorheological medium, which enables particularly high braking torques.

[0079] In a particularly preferred and advantageous embodiment, at least three brake gap sections are provided. In particular, at least one third brake gap section is arranged axially between a first brake gap section and a second brake gap section. In particular, at least one first electrical coil is assigned to the first brake gap section, and at least one separately controllable second electrical coil is assigned to the second brake gap section. In particular, both the first and the second electrical coil are assigned to the third brake gap section.

[0080] Particularly preferably, at least two differently configured brake gap sections are included. In particular, the first and second brake gap sections are configured differently from one another. The first and second brake gap sections are preferably configured differently in the radial (and / or axial) direction and / or are functionally different.

[0081] Another advantage is the redundancy provided by such a system with two electrical coils. If one coil fails, the second coil can still generate a magnetic field, thus providing a controllable torque across the brake gap, albeit not with the same quality. This is very advantageous for applications where high reliability is required.

[0082] In particular, the first brake gap section and the second brake gap section are configured differently. Preferably, at least two (functionally) different (in particular radially and / or axially) brake gap sections are included. The brake gap sections are preferably configured separately from one another and, in advantageous embodiments, are separated from one another in the axial direction.

[0083] Preferably, the first brake gap section and the second brake gap section are formed with different widths (gap heights) and / or have different cross-sectional profiles.

[0084] It is also particularly preferred that different materials are used at least partially in the first brake gap section and the second brake gap section. In particular, in the regions of the first brake gap section and the second brake gap section, the materials used on the core and / or the casing part can differ at least in some sections. The same or different materials and constructions can be used for the electrical coils.

[0085] The two brake gap sections can have different running clearances and gap dimensions and / or gap contours and gap profiles (of the parts moving relative to each other). A small gap height can result in higher torques, but is often more difficult to control in terms of control technology. A large gap height generally behaves the opposite way (low torque, but overall easier to control). Depending on requirements, one (first) or the other (second) coil can be energized. For example, an end stop (stop, barrier) usually requires very high torques and little control technology, since the actuator is essentially stationary. In this case, a small gap (gap height) or possible rotating bodies / rollers in the brake gap section are efficient. However, braking that is as constant as possible at higher speeds usually requires a high level of control quality; in this case, a larger gap height and / or a disk / star contour on a brake gap section is advantageous.

[0086] The first braking component defines an axial direction. In particular, an axis of symmetry of the first braking component is the axis of rotation. Preferably, the core of the first braking component extends in the axial direction, but can also be at a slight angle to the axial direction.

[0087] The invention makes it possible to generate a high braking torque at different speeds in a small installation space. The magnetic field passes through the two different braking gap sections between the core and the casing part, each essentially radially or at least transversely to the rotation axis.

[0088] The rolling elements at or in the second brake gap section serve primarily as magnetic field concentrators. Due to the rolling elements (which serve as magnetic field concentrators), acute angles can arise between the individual magnetic field lines and the radial alignment, but generally or on average, the magnetic field is essentially radial. The same applies to the other brake gap section with the disc contour, where a three-dimensional alignment of the magnetic field lines can also occur at the radial end of the disc contour, although on average or overall, they are again essentially radially aligned.

[0089] In preferred embodiments, the first electrical coil and the second electrical coil are configured differently. Preferably, the first electrical coil and the second electrical coil differ in at least one parameter from a group of parameters, which group includes the wire diameter and wire cross-section, the number of turns, the winding window, the winding type, the coil width, the coil diameter, and the material.

[0090] In particular, in an axial region (directly) adjacent to the first electrical coil, a disk contour or a disk body is formed between the casing part and the core, and in a (different) axial section (directly) adjacent to the second electrical coil, a plurality of rolling elements (as magnetic field concentrators) are arranged on the circumference of the core. The rolling elements are arranged in particular in a common plane transversely or perpendicularly to the axis of rotation. Preferably, the rolling elements can move completely around the core. An outer surface of the core is preferably cylindrical in the second braking gap section. Preferably, the annular contour is arranged (directly) between the first electrical coil and the second electrical coil.

[0091] Preferably, a radius or (typical or maximum) diameter of the first brake gap section is approximately, and in particular exactly, the same size as a radius or (typical or maximum) diameter of the second brake gap section and / or the third brake gap section. This allows for high torques to be generated even at higher speeds and when starting from a standstill.

[0092] The magnetorheological medium wets in particular the first and the second brake components at least in sections.

[0093] The first electrical coil and the second electrical coil are preferably wound around the rotational axis and essentially generate a magnetic field in the axial direction within the core. The two electrical coils are accommodated radially between the core and the casing part. The electrical coils can be wound around the core or attached to the inside of the casing part.

[0094] The core is made of a magnetically (highly) conductive material. The first brake component comprises the core and, in particular, an axle or shaft, which is, in particular, made at least partially or entirely of a magnetically non-conductive material. Preferably, the axle (shaft) and the core are detachably connected to one another.

[0095] The disc contour consists at least partially or completely of a magnetically (well) conductive material.

[0096] In a preferred embodiment, the disk contour is formed as a separate disk body. It is also possible for the disk contour to be formed integrally with the core and, for example, to be T-shaped, with the long leg of the "T" running along the rotation axis. It is also possible for a portion of the disk contour to be formed integrally with the core and supplemented by a separate disk body. In simple and particularly preferred embodiments, the disk contour is formed by a separate disk body that is attached to or on the core.

[0097] The disk body is preferably applied to the core. For this purpose, the core in particular has a adapted receptacle. It is possible and preferred, for example, for the disk body to be connected to the core or pressed on. However, it is also possible for the disk contour or disk body to be connected to the shell part and, for example, pressed into it. It is also conceivable for two disk bodies adapted to one another to be used, between which a radial braking gap section is formed. In this case, a first hollow cylindrical disk contour can be applied to the core and a second hollow cylindrical disk contour with a correspondingly large inner diameter can be introduced into the shell part so that the two disk contours are aligned with one another, for example in the axial direction, leaving a small (radial) gap between them.A brake gap section, which is essentially radial in shape, then remains between the two disc contours.

[0098] In particularly preferred embodiments, the disk contour comprises at least one disk stack. The disk stack is formed in particular by a plurality of preferably directly adjacent disk sheets. Such a configuration enables, for example, the production of the disk sheets as stamped parts. Stamped parts can be produced particularly easily and cost-effectively in large quantities. If they are stacked one on top of the other and pressed together, for example, a disk stack or disk body with a considerably greater thickness can be easily and cost-effectively provided. This makes disk sheets and disk stacks very cost-effective to manufacture.

[0099] It is preferred that at least some of the disc sheets, or almost all of the disc sheets, or all of the disc sheets are each round and have the same or similar diameters. However, it is also possible to use some or individual non-round disc sheets, on which, for example, a non-round outer contour or a toothed structure or star contour is formed radially outward. If round and non-round disc sheets are stacked to form a disc stack, a complex outer contour can be created, which can lead to a greater local magnetic field concentration.

[0100] It is also possible for a disc pack to comprise several round (or non-round) disc plates with different outer diameters. This allows alternating round disc plates with smaller and larger diameters to be provided.

[0101] Individual discs can also have different properties (e.g., due to different materials). Individual discs can also be made of (sintered) magnetic material (e.g., neodymium).

[0102] In particularly preferred embodiments, the disk contour has a cylindrical outer contour. It is also possible and preferred for the disk contour to comprise a star contour or to be designed as such.

[0103] It is possible and preferred for the disk contour to have an (axially) outwardly projecting outer contour on at least one axial side. The disk contour may be conical, bulbous, rounded, or stepped overall. In particular, the disk contour is rotationally symmetrical in the region of the outer contour. The outwardly projecting outer contour can, for example, be supported on a cover or the like or be guided there. The outwardly projecting outer contour thus enables the provision of a reservoir of magnetorheological particles.

[0104] In all configurations utilizing rolling elements, it is preferred that the radial clearance for a rolling element between the casing portion and the core in the second brake gap section be greater than the gap height in the first brake gap section (in the region of the disk contour). The radial clearance is the difference between the gap height in the second brake gap section minus the diameter of the rolling element. Typically, the radial clearance is divided approximately equally radially outside the rolling element and radially inside the rolling element. In simple cases, the rolling element is arranged radially centrally, and the radial distance between the outer surface of the rolling element and the inner surface of the casing portion and the radial distance between the outer circumferential surface of the core and the radially inner outer surface of the rolling element are approximately the same.

[0105] Preferably, the radial clearance (total) for a rolling element in the second brake gap section is more than twice and in particular at least three times as large as the gap height in the first brake gap section. This means that normally the rolling element has more clearance radially outwards and radially inwards than the gap height on the disk body in the first brake gap section. It is also possible and preferred that the radial clearance for a rolling element in the second brake gap section is four times as large or even greater than the gap height in the first brake gap section. Preferably, a gap height at the brake gap section on the disk contour is less than 0.15 mm and preferably less than 0.1 mm.

[0106] Preferably, the radial clearance in the second brake gap section and the gap height in the first brake gap section at the disk contour, and the gap height in the third brake gap section, are (significantly) smaller than a radial distance in other regions of the gap. The radial distance from the outer diameters of the electrical coils or from the outer diameter of a coating over the electrical coils or an overmolding of the electrical coils to the radial inner wall of the casing part is (axially) preferably (significantly) larger outside the two brake gap sections than in the two brake gap sections. The size difference can reach and far exceed a factor of 2 or 3.

[0107] In specific embodiments, the radial clearance for a rolling element in the second brake gap section is approximately 0.2 mm, while the gap height in the first brake gap section is approximately 0.05 mm. Deviations of + / - 50% are possible in each case. Overall, the radial play on a haptic control button in the area of ​​the rolling elements is then twice the radial clearance, since rolling elements are arranged on opposite sides of the core, a total of 0.4 mm in this example. In the area of ​​the first brake gap section with a gap height of 0.05 mm, this results in a total radial clearance of 2 × 0.05 mm, i.e. 0.1 mm.

[0108] Due to this very small clearance, a separate bearing is often unnecessary, at least at the end with the disc contour. The disc contour, together with the shell part, then guides or supports the shell part relative to the core. This enables an even simpler and more cost-effective design.

[0109] In all configurations, the inner contour and / or preferably the shell part can be non-circular (e.g., elliptical). The core can be mounted eccentrically to the shell part. This results in a changing relative gap at certain points during rotation (of the rotor relative to the stator).

[0110] In particularly preferred embodiments, the electrical coils are arranged axially between the first and second brake gap sections. Particularly preferably, at least one brake gap section axially adjoins one of the electrical coils, directly or indirectly.

[0111] In all embodiments, it is particularly preferred that the magnetic field of the magnetic circuits passes at least partly axially through the core and the casing part and to a considerable extent radially and particularly preferably essentially radially through the third brake gap section. Furthermore, the magnetic field of the first electrical coil passes to a considerable extent radially and particularly preferably essentially radially through the first brake gap section and that of the second electrical coil passes through the second brake gap section. In simple embodiments, the electrical coils are each wound around the core and each generate a magnetic field in the axial direction of the axis of rotation within the core, which magnetic field is directed radially outwards at the respective ends of the electrical coils and at one axial end through the disk contour and the first orsecond brake gap section and at the other axial end through the third brake gap section, respectively, from the core into the shell part and vice versa. Such a design allows for a particularly simple, cost-effective, yet effective construction.

[0112] Preferably, the rolling elements consist at least partially and in particular almost entirely or completely of a magnetically conductive material.

[0113] Magnetically non-conductive bodies or rolling elements can also be present. Non-conductive bodies can serve as spacers or guide elements and can have any shape. For example, magnetically non-conductive bodies can be arranged between the (magnetically conductive) rolling elements. Several non-conductive bodies (e.g., guide elements) can be interconnected, e.g., in the form of a cage. This facilitates assembly.

[0114] Particularly preferably, the disc contour guides the casing part in a rotatable manner and serves as a bearing point.

[0115] Preferably, a closed chamber is formed between the brake components. In particular, the closed chamber is at least substantially filled, and in particular substantially filled, with a magnetorheological medium such as a magnetorheological fluid and / or, for example, (dry or powdered) carbonyl iron powder. In particular, the second brake component is rotatably mounted on the first brake component.

[0116] The first brake component preferably comprises an axle, which is formed at least in part from a non-magnetically conductive material. The core, made of a magnetically conductive material, is attached to the axle or an inner part.

[0117] Preferably, the second brake component is mounted axially displaceably on the first brake component. This can, for example, also serve to enable volume compensation in the event of temperature changes and / or leakage. It is preferred that a radial and / or axial position of the two brake components relative to each other is detected by sensors.

[0118] It is preferred and advantageous that the (in particular absolute) position of the steering device can be detected. In particular, the (in particular relative) position of the brake components can be detected. In particular, not only the relative position of the brake components should be detected, but also the absolute position of the steering device. This is because the steering device can have electrical connections, such as a clock spring, and these must not be torn off. For this purpose, in particular at least one absolute sensor is installed which detects the end of the steering stop. The brake then generates in particular an end stop. The absolute sensor is also particularly necessary when the vehicle is parked and the steering angle is not in the neutral position. When the vehicle is put into operation again, the steering control unit can use this to detect which steering angle the wheels are assuming.

[0119] A torque sensor can also be installed in the steering line or steering shaft.

[0120] In all embodiments, it is preferred that a click element is arranged at one end, in particular at the distal end, of the chamber. Such a click element enables, in particular, two states, wherein, after actuation of the click element, for example, a metal sheet switches audibly and / or tactilely and thereby undergoes a (slight) axial displacement. Such click elements, embodied, for example, as snap-action parts or snap-action disks, are known, for example, from keyboards or other devices and enable cost-effective and effective tactile feedback when a button or the like is actuated.

[0121] Preferably, the click element is arranged at one end of the chamber. Particularly preferably, an elastic membrane separates the chamber from the click element. The click element can be designed as a snap-in part or snap-in disk. This allows volume compensation to be provided in the chamber when the axle dips further into or out of the chamber.

[0122] In particularly preferred developments, the snap-action disc is designed such that a change in the spanned volume of the snap-action disc between the two states of the snap-action disc is adapted to a cross-sectional area of ​​the axis multiplied by an axial offset of the snap-action disc upon actuation. In particular, the two volumes differ by less than 50% or 25%, and preferably by less than 10% or less than 5%. Such a design, in which the snap-action disc is adapted to the axis, ensures that only a small or possibly no volume needs to be provided for volume compensation upon actuation of the snap-action disc.

[0123] The use of a click element or snap part at the distal end of the chamber in conjunction with the formation of the first brake gap section with the disc contour also close to the distal end of the chamber enables particularly simple and effective guidance and mounting of the casing part, since there is only a small radial play and the disc contour can therefore provide (in many cases) sufficient guidance in the radial direction of the casing part.

[0124] In preferred developments, a sensor device or at least one sensor device for detecting a relative angle of rotation between the core and the shell part is included.

[0125] Preferably, a sensor device or at least one sensor device for detecting a relative axial position of the casing part to the core is included. Particularly preferably, the sensor device or at least one sensor device comprises at least one magnetic field sensor designed to detect a rotation angle and an axial position. In particularly advantageous embodiments, the sensor device comprises at least one Hall sensor.

[0126] In simple, preferred embodiments, the magnetic field sensor is mounted on the stationary brake component and exposed to a magnetic field acting in a radial direction. Furthermore, a rotation angle can be determined by the orientation of the magnetic field sensor relative to the magnetic field. An axial displacement of the sensor device relative to the casing part can be derived from the intensity of the magnetic field strength.

[0127] Particularly preferably, at least one shielding device for at least partially shielding the sensor device from a magnetic field of the electrical coil is included. The shielding device preferably comprises at least one shielding body. The shielding body is designed in particular to shield a magnetic ring unit for applying a defined (e.g., radial) magnetic field to the magnetic field sensor from disruptive magnetic influences of the electrical coil. For this purpose, the shielding body preferably surrounds the magnetic ring unit at least in sections. The shielding device preferably surrounds the magnetic ring unit on three sides, namely from both axial sides and radially outwards. The shielding device preferably comprises at least one separating unit arranged between the shielding body and the magnetic ring unit. This decouples the magnetic field of the magnetic ring unit from the shielding body.Furthermore, at least one magnetic decoupling device is preferably arranged between the shielding body and the casing part. Preferably, the separating unit and / or the decoupling device have a magnetic conductivity that is several times lower than that of the shielding body. Preferably, the shielding device and the magnetic ring unit are arranged at a distance from one another.

[0128] A shielding device enables a significant improvement in measurement quality. In particular, it allows for fine angular resolutions and small axial distances.

[0129] The solenoid coil is preferably controlled mostly or predominantly during operation with a voltage of, in particular, 12V. It is (often) a considerable advantage if the braking torque of the magnetorheological braking device reaches the maximum or set value as quickly as possible. This is sometimes only possible with a higher voltage. Maximum braking torque is generally achieved by a maximum magnetic field in the brake gap. Since the magnetic field is generated by the current in the electrical coil (solenoid coil), the current must also be set to the maximum value as quickly as possible. In principle, the voltage can always be set to a high value; in this specific case, for example, 24V instead of 12V. However, this would require all components (electrical coil or solenoid coil, coil wire, etc.) to be designed accordingly (and, for example, a wire with a larger diameter would have to be used).

[0130] Therefore, in preferred embodiments and further developments, a higher voltage is set at least (in particular only) at the beginning of a haptic feedback signal (than would be necessary, for example, in continuous operation). In particular, at the beginning of or almost immediately after a haptic feedback signal, a higher voltage is set (e.g., by a factor of 1.5 or 2 or 3 higher than would be necessary in continuous operation), preferably for a period of between 0.5 ms and 50 ms, preferably in a period of between 1 ms and 20 ms, and particularly preferably between 5 ms and 15 ms. The higher voltage is maintained, in particular, until the current (or the magnetic field) reaches the desired maximum value (almost, for example, 90% or 95%) and / or the period for which the higher voltage can be effective is reached or exceeded. Thereafter, the voltage is regulated back to the lower voltage of, for example, 12 V. The system reacts more quickly, and the desired braking torque is set more quickly.

[0131] Especially in modern electric cars, multiple voltages are present within the vehicle, and high voltages / currents are possible, so that these do not need to be separately generated or transformed. These electric vehicles also have much higher voltages (e.g., up to 800 volts) and such currents are possible that the previously described properties can be used to their advantage.

[0132] In particular, the magnetic field strength between individual magnetically polarizable particles of the magnetorheological medium is greater than 300 kA / m. In particular, the magnetic field strength that can be generated in the gap, preferably in at least one of the braking gap sections, is greater than 500 kA / m.

[0133] The method according to the invention serves to operate a steering device with a magnetorheological braking device with two braking components, wherein the two braking components are continuously rotatable relative to one another about a rotational axis, wherein a first braking component extends along the rotational axis and comprises a core made of a magnetically conductive material, and wherein the second braking component comprises a hollow casing part extending around the first braking component, wherein at least three axially spaced-apart and circumferential braking gap sections are formed between the first and the second braking component and are at least partially filled with a magnetorheological medium. A first electrical coil generates a (first) controlled magnetic field in a first braking gap section.Independently of this, a second electrical coil generates a (second) controlled magnetic field in a second brake gap section to generate braking effects of varying strengths, particularly depending on the speed. In this case, the magnetic fields of the first and second electrical coils are both closed, in particular, across the third brake gap.

[0134] The method according to the invention also solves the aforementioned problem particularly advantageously. The method is particularly designed such that the steering device according to the invention can be operated accordingly. In particular, the steering device can be operated according to the method according to the invention.

[0135] In the context of the present invention, blocking is understood in particular to mean that no movement of the steering unit (in at least one direction of rotation and / or in both (all) operational directions of rotation) can occur with a manual force that is to be applied during operation. In particular, the mobility of the steering unit can also be released by means of the braking device. In the context of the present invention, release is understood in particular to mean that only an operational basic torque (also referred to as idling torque) of the braking device is present, without an additional magnetorheological deceleration being applied, for example by energizing the coil. When mobility is released, the magnetorheological braking device is in particular inactive, so that no field is generated to actively influence the magnetorheological medium.

[0136] Further advantages and features of the present invention will become apparent from the embodiments which are explained below with reference to the accompanying figures.

[0137] Showing: Figures 1 show a purely schematic representation of a steering device according to the invention with a magnetorheological braking device; Figure 2 show a side view of a braking device; Figures 3a-3c show various sections of braking devices; Figures 4a-4b show a highly schematic view of a sensor device and measurement results; Figure 5 show a highly schematic view of a braking device with a snap-action disc in different positions; Figure 6 show two differently designed electrical coils; Figures 7-8 show a further haptic braking device in section and in perspective; Figure 9 show a highly schematic circuit for controlling the electrical coil; Figure 10 show a sketch with braking torque curves to illustrate the functioning of the braking device; and Figure 11 show a further sketch with braking torque curves.

[0138] The Figure 1shows a steering device 100 according to the invention for steering a vehicle not shown in detail here by means of a steering unit 301. The steering unit 101 is designed here as a rotatable steering wheel which is connected in a rotationally fixed manner to a steering shaft 311.

[0139] The steering device 100 is designed here as a steer-by-wire steering system. For this purpose, an actuator device 303 is used to convert the steering movement performed by the steering unit 301 into a vehicle movement. For example, the actuator device 303 steers the vehicle wheel or wheels. The actuator device 303 is only electrically connected to the steering unit 101.

[0140] The rotational movement of the steering unit is detected by a sensor device 70 and, for example, a rotation angle sensor. Depending on the rotation angle, the actuator device 303 then steers, for example, the vehicle wheel(s). This can be used to steer, for example, the front and / or rear wheels, or, in the case of a tricycle, the inclination of the tricycle. It can also be used to steer the wheels of the front and rear axles, or even all axles (so-called crab steering).

[0141] A drive device 307, designed as an electric motor, is connected to the steering shaft 311. The drive device 307 can actively rotate the steering unit 301. This actively moves the steering unit 301, for example, when cornering, as would be the case with a conventional mechanical steering system.

[0142] The movement of the steering unit 101 can be specifically braked using a magnetorheological braking device 1. A steering control unit 302 is provided to control the braking device 1 and also the drive device 307 depending on various parameters, such as the steering angle. For this purpose, the steering control unit 302 is operatively connected to the sensor device 70.

[0143] The steering control unit 302 also takes into account, for example, data from a driver assistance system 304. This allows the movement of the steering unit 301 to be specifically influenced depending on the driving situation. The steering control unit 302 can also be operatively connected to other sensors not shown in detail here in order to specifically influence the steering behavior depending on additional parameters.

[0144] The braking device 1 is equipped with a safety device 306, which removes a magnetorheological medium 6 (not visible here) from a gap 5 (also not visible here). This allows, for example, the braking torque to be removed very quickly and reliably in the event of a malfunction. The gap 5 and the medium 6 are described in more detail with reference to the following figures.

[0145] Figure 2 shows a side view of a braking device 1 with a holder 4, which can be fastened via a nut 51, for example, to a bracket 50. The braking device 1 has two braking components 2, 3, of which the inner braking component 2 in Figure 2 is not visible. The inner brake component 2 is connected to the holder 4. The holder 4 and the inner brake component 2 are stationary here. The other brake component 3 comprises the casing part 13 and is rotatably mounted on the first brake component 2.

[0146] The braking device 1 is of compact construction and has, inside the shielding device 75, which has a two-part shielding body 76 as a shielding housing, a sensor device 70 (not visible here) for detecting the rotational position and the axial position of the casing part 13. The casing part 13 is connected to a left cover 14 and a right cover 15 via pins 16 in order to seal an inner closed chamber 110.

[0147] In the Figures 3a to 3c are possible cross sections of a braking device 1, e.g. Figure 2 The brake component 2, which extends in the axial direction and to which the core 21 is attached, is mounted on the holder 4. The core 21 is radially surrounded by the (magnetically conductive) casing part 13, which serves as the outer or second brake component 3.

[0148] The magnetically conductive core 21 is surrounded by two electrical coils 26 wound around the core 21. The first electrical coil 261 extends over an axial width 26e. At the end of the core 21 facing the holder 4, a disk contour 41 is formed, which is applied to the core here and, for example, pressed on. The disk contour 41 has a hollow-cylindrical disk body 42 for this purpose. The receptacle on the core can also be non-circular.

[0149] The core 21 can be made, in particular, of sintered material (metal). This makes it easier to manufacture the core in the desired shape.

[0150] The disc body 42 here consists of a disc stack 44 formed by a plurality of thin disc sheets 46. Here, the disc sheets 46 are each designed as a stamped part and can be punched, for example, from a magnetically conductive sheet with a thickness of 1 mm, 2 mm, or even 3 mm. This allows the required number of disc sheets to be punched out easily and cost-effectively to produce the desired thickness of the disc body 42.

[0151] The individual disc plates 46 are pressed together and applied to the core 21, for example, by screwing or pressing. A brake gap section 5a remains in the area of ​​the disc body 42 with a small gap height 41b between the outer diameter of the disc contour 41 and the inner circumference of the casing part 13. The axial width 41e of the disc contour 41 or its brake gap section 5a is determined here by the number of disc plates 46 and can be selected to be larger or smaller than shown.

[0152] The disk contour 41 here directly adjoins the first electrical coil 261 axially, which is accommodated in a coil holder 26b and is completely sealed radially on the outside by a potting compound 28.

[0153] The disc body 42 is connected to the core 21 and to the stationary brake component 2 and does not rotate during operation. This allows for the formation of a hole or recess for the passage of the cables 45 for electrically connecting the first and second electric coils 261, 262. The electric coils 261, 262 can thus be connected easily, cost-effectively, and quickly.

[0154] The disc contour 41 is formed here at the proximal end, i.e., at the end of the core 21 facing the holder 4. A second braking gap section 5b is formed at the distal end, i.e., at the other end of the core 21. The second braking gap section 5b extends over an axial width 11e. The rolling elements 11 are distributed there on the circumference of the core 21. The rolling elements 11 locally amplify the magnetic field. The rolling elements 11 can form a type of magnetic field concentrator 80 for locally amplifying the magnetic field as it passes through the second braking gap section 5b.

[0155] Through the second brake gap section 5b, a very high braking torque can be achieved with the second electrical coil 262, particularly at low speeds of the casing part 13. Through the first brake gap section 5a in the area of ​​the disk contour 41, a still strong magnetic field can be transmitted from the core 21 to the casing part 13 at high speeds with the first electrical coil 261, since the gap height 41b is considerably smaller than the radial free space 11c in the area of ​​its brake gap section 5b. This enables a high torque to be generated, which is particularly possible even at higher speeds. This allows a high and finely adjustable torque to be provided across the entire speed range through targeted and separate control of the two electrical coils 261, 262.

[0156] The axial width 11e of the second brake gap section 5b and the width 41e of the first brake gap section 5a are approximately equal (+ / -25%) and each shorter than the axial width of the third brake gap section 5c. Overall, a very compact design is achieved.

[0157] The casing part 13 is in Figure 3a surrounded by a cover 49 as a rotary knob 23. The rotary knob 23 is at least partially transparent so that it can be illuminated by the lighting means 18, for example, LEDs. The lighting can be controlled either depending on the situation or independently of the situation. This design is primarily intended for steering devices in computer games, but can also be used in vehicles.

[0158] At the front end, the closed chamber 110 inside the casing part 13 is closed by a front cover 14, through which the brake component 2 passes. A seal 38 serves for sealing. At the rear or distal end, the chamber 110 is initially delimited by an elastic membrane 31, to which a click element 29, here designed as a snap-action disc, is connected on the outside.

[0159] The second coil 262 or the associated core material is also designed as a remanence device 305. If the remanence device 305 has been previously activated, a magnetic field remains even after the power supply is switched off, which influences the medium 6 and thus maintains a braking torque. This allows, for example, a steering wheel lock to be enabled without additional power consumption. A parked vehicle should consume as little power as possible, ideally no power at all, as otherwise the battery could be drained (both in vehicles with combustion engines and in electrically powered vehicles). The steering wheel lock should therefore apply a high locking torque even without power. This can be provided by a remanence device.

[0160] Figure 3b shows a slightly different representation of a braking device 1, whereby in contrast to Figure 3a the cover 49 or the rotary knob 23 was omitted.

[0161] A key difference between the Figures 3a and 3b is that in Figure 3b the first brake gap section 5a with the disc contour 41 is provided at the distal end of the casing part 13, while the second brake gap section 5b with the rotating bodies 11 is provided at the proximal end of the casing part 13.

[0162] In this embodiment, for example, a bearing for supporting the casing part 13 relative to the brake component 2 can be provided outside the chamber 110 between the seal 38 and the sensor device 70. However, it is also possible here for the bearing to be provided at one end only via the seal 38 and at the other distal end only via the disc contour 41.

[0163] The disc contour 41 can be formed (circumferentially) in one piece with the core, as in the lower part of Fig. 3bis shown schematically. Or the disk contour 41 comprises a (circumferential) disk package with several disk sheets 46, as is shown for example in the upper part of Fig. 3b The disk contour can also be mounted on the core as a solid, separate part, thus consisting essentially of a single disk sheet of correspondingly greater thickness.

[0164] Examples are shown in Figure 3bsome magnetic field lines 8 of the first electrical coil 261 and the second electrical coil 262, which show the largely axial course of the magnetic field lines in the core 21 and in the casing part 13. Furthermore, it can also be seen that an (approximately) radial passage of the magnetic field lines 8 occurs in the brake gap sections 5a and 5b. In the brake gap section 5a, a higher torque is generated at higher speeds, while in the brake gap section 5b, a higher moment is generated at lower speeds. The respective magnetic field is closed in the central region by the (approximately) radial transition at the third brake gap section 5c. In the brake gap section 5c, there is practically a thin gap, similar to the first brake gap section if a cylindrical disk contour 41 is used there.

[0165] The magnetic field sensor 72 is mounted on a sensor board 79 and can be contacted via the contact pins 79a. The electrical coil 26 is also supplied with power via this pin.

[0166] At least in the area of ​​the sensor device 70 and the magnetic field sensor 72, the inner brake component 2 is preferably made of a material with little or no magnetic conductivity to ensure the most undisturbed detection possible of the orientation and intensity of the magnetic field of the magnetic ring unit 71 inside the axle 12 or the first brake component 2. There, the sensor device 70 is housed in a particularly protected manner (protection against water and dust).

[0167] In Figure 3b an O-ring 39 can be seen, which seals the cover 14 against the casing part 13.

[0168] The third brake gap section 5c is formed on the annular contour 61. The annular contour 61 can be pushed or applied onto the core 21 as a separate ring, or the annular contour 61 can be formed integrally with the core 21. In any case, the annular contour 61 is magnetically conductively coupled to the core 21.

[0169] Purely schematically shows Figure 3bIn the upper half, there is another alternative embodiment in which a fourth brake gap section 5d is integrated. The fourth brake gap section 5d can be created, for example, by the ring contour 61 providing two separate brake gap sections 5c and 5d. For example, two magnetically conductive ring parts can be included, which are separated from each other by a less magnetically conductive intermediate part or ring part 61a. Then, two axially separated brake gap sections 5c and 5d are formed. In other embodiments, the electrical coils 261, 262 and the brake gap sections 5c, 5d can also be arranged further apart from each other, so that two further separated magnetic circuits are created.

[0170] A structure with three brake gap sections, wherein the middle brake gap section 5c is provided for both electrical coils 261, 262, enables a particularly compact structure.

[0171] A structure like in Figures 3a or 3b , provides an advantageous embodiment. The second electrical coil 262 enables a particularly strong braking torque in the second brake gap section 5b via the rolling elements 11, particularly at low speeds or when stationary. The first electrical coil 261 enables a high braking torque at higher speeds via the very small gap height in the first brake gap section 5a.

[0172] If a rotary movement is to be braked and a stop is to be provided, the first electrical coil 261 on the first brake gap section 5a enables greater braking at higher speeds than the second electrical coil 262 on the second brake gap section 5b. At a relatively low transitional speed, the braking torque that can be generated with the second electrical coil 262 on the second brake gap section 5b is greater than the braking torque that can be generated at the first brake gap section 5a at this speed. This is because the braking torque that can be generated via the rolling elements 11 is more dependent on the speed and decreases with higher speeds. By combining different brake gap sections 5a, 5b, optimal conditions can be set for different speeds.

[0173] Figure 3cshows schematic cross-sections of the brake gap sections 5a, 5b, and 5c. The second brake gap section 5b is shown on the left, with the core 21 visible inside, around which the rolling elements 11 are schematically arranged. The rolling elements are in turn surrounded by the casing part 13. The rolling elements each have a diameter 11d. A radial gap height 11b is slightly larger than the diameter 11d. This results in a radial clearance 11c as the difference between the gap height 11b and the diameter 11d. The radial clearance 11c is generally divided relatively evenly between the radial inside and radial outside.

[0174] A magnetorheological medium comprising magnetorheological particles 19 is accommodated in the chamber 110. A gap 5 is provided in the chamber between the brake components 2 and 3. The three brake gap sections 5a, 5b, and 5c are formed at the gap 5. The chamber 110 is at least partially filled with a magnetorheological medium 6. The medium is preferably a magnetorheological fluid, which, for example, comprises an oil as the carrier fluid in which ferromagnetic particles 19 are present. Glycol, grease, water, and viscous substances can also be used as the carrier medium, without being limited thereto. The carrier medium can also be gaseous, or the carrier medium can be omitted (vacuum). In this case, only particles 19 that can be influenced by the magnetic field are filled into the chamber 110.

[0175] The ferromagnetic particles 19 are preferably carbonyl iron powder, with the particle size distribution depending on the specific application. Specifically, a particle size distribution between one and ten micrometers is preferred, although larger particles of twenty, thirty, forty, and fifty micrometers are also possible. Depending on the application, the particle size can be significantly larger, even reaching into the millimeter range (particle spheres). The particles can also have a special coating / shell (titanium coating, ceramic, carbon shell, etc.) to better withstand the high compressive loads that may occur depending on the application. For this application, the magnetorheological particles can be made not only from carbonyl iron powder (pure iron), but also, for example, from special iron (harder steel).

[0176] It is possible that only particles that can be influenced by the magnetic field are filled into the gap 5 or the chamber 110, with air or an inert gas being added if necessary. If, for example, only air or another gas is used, various solids can be mixed in to improve certain properties. For example, graphite powder can be added to reduce the friction between the carbonyl iron particles, since graphite has a lubricating effect. The particles can in particular be coated with PTFE. A coating with PTFE or a comparable coating prevents the particles from clumping and forming larger clusters. Such larger clusters do not disintegrate easily or, in some cases, may not disintegrate at all. Alternatively, the disk bodies or roller bodies can also be coated with PTFE to reduce friction.When using MRF without oil or other liquid as a carrier medium, it is important to ensure that no water condenses in the braking chamber (MR chamber or MRF chamber). For example, silica gel or another desiccant can be mixed in to absorb water, thus removing moisture from its surroundings.

[0177] If powder is used without a carrier fluid, up to about 80 volume percent carbonyl iron (iron powder) is possible, which increases the braking torque considerably if the remaining design parameters are adapted accordingly (e.g. the field strength per particle should remain roughly the same as with a magnetorheological fluid (MRF), i.e. the field strength in the braking gap or effective gap should be twice as high when changing from e.g. LORD MRF 140 (40 volume percent carbonyl iron with e.g. oil as a carrier fluid) to 80% carbonyl iron powder (without carrier fluid). We are talking here about magnetic field strengths in the gap of greater than 200 kA / m up to values ​​of up to 1,000 kA / m (1,000,000 A / m) or more.A further advantage of using powder as a medium in the active gap is that it eliminates sedimentation and clumping in the sense that "the iron particles in MR fluids are drawn in the direction of the magnetic field gradient (the force on magnetizable particles always acts in the direction of the stronger magnetic field, displacing the carrier medium)" to achieve high particle concentrations. The maximum particle concentration is already present. This improves the reproducibility of the torques (a similar braking torque is always achieved at the same current).

[0178] In all embodiments, it is particularly preferred that the magnetically polarizable particles (to a significant extent) comprise non-circular particles (non-spherical particles) in which the ratio of the largest diameter to the largest transverse extent perpendicular thereto is greater than 1.25 or 1.5. This ratio can also be formed as a ratio of the largest longitudinal extent to the largest transverse extent, with the longitudinal and transverse extents, in particular, being measured perpendicular to each other.

[0179] The use of non-circular particles is particularly advantageous because they enable an effective canting structure, as different non-circular sections of the particles clamp or wedge together.

[0180] Also possible and preferred are ratios of the largest diameter to the largest transverse extent perpendicular thereto of 1.75 or 2.0 or more.

[0181] Preferably, at least some of the magnetically polarizable particles are designed to clamp or wedge together under the influence of the magnetic field. This is possible, for example, with particles that are partially angular or, for example, entirely triangular or polygonal, or the like. Two (or more) correspondingly designed particles then clamp together and can cause a very effective clumping of the particles and the clamping and deceleration of the two brake or clutch components together.

[0182] Preferably, at least some of the magnetically polarizable particles are designed to clamp or wedge together at two or more spaced-apart locations under the influence of the magnetic field. Such non-circular particles allow for a very effective increase in the braking force or braking torque, since, unlike spherical particles, they do not only touch at one point or within a small angular range, but at several points or even across a large area.

[0183] Preferably, at least some of the magnetically polarizable particles have at least one trough section. Such an inwardly curved trough section allows for particularly effective wedging with parts of other particles.

[0184] Preferably, at least one surface of at least one clutch or brake component adjacent to the brake gap is at least partially unsmooth or (locally) uneven. It is also possible for the particles or a significant portion of the magnetically polarizable particles to have regular or irregular elevations or ridges and / or depressions on the outer surface. This can increase the likelihood of jamming with the particles. For example, at least one surface can have elevations and / or depressions similar to pointed or rounded dimples on golf balls. A surface with a pointed or rounded sawtooth profile is also possible. A relative height (of at least some of) the elevations or depressions is preferably at least 5% or 10% of the minimum diameter of a magnetically polarizable particle.

[0185] It has been found that particularly effective tilting and jamming of individual particles can be achieved using high magnetic field strengths. For this purpose, a magnetic field strength of greater than 150 kiloamperes / meter (kA / m), or 250 kiloamperes / meter, or 500 kA / m or more is preferably generated in the gap. In particular, a magnetic field strength of greater than 500 kiloamperes / meter (kA / m), or 750 kiloamperes / meter, or 1000 kA / m or more can be generated or is generated in the gap, preferably in at least one of the brake gap sections.

[0186] If only powder is used without a liquid carrier medium, a different type of seal can be selected, thereby reducing the basic friction. The seal does not have to be pressed as tightly against the surfaces, since it is not the liquids that need to be sealed, but only the particles. A non-contact shaft seal, such as a labyrinth seal, can also be used. This type of seal only rests on one of the two parts rotating relative to each other. In addition, the temperature dependence is reduced or almost eliminated. Liquid carrier media change their viscosity with changing temperatures, whereas carbonyl iron powder hardly changes its properties over very wide temperature ranges (until the Curie temperature is reached). The temperature-induced volume change is also negligible with powder, since the particles can redistribute themselves among themselves when the volume of the individual particles changes.

[0187] The maximum volume fraction of carbonyl iron particles is also higher in powder form (approx. 74%) than in MRF with, for example, oil as carrier medium.

[0188] The magnetorheological particles 19 interlink when a magnetic field is applied, as in Figure 3c The diagram on the left is very schematic. This creates a wedge effect, which leads to a significant increase in braking torque at low and medium speeds.

[0189] For a more detailed explanation of this effect, please refer to the Figure 4 Reference is made to the applicant's international application WO 2018 / 215350 A1, which is fully incorporated into the scope of disclosure of this application in an adapted manner with regard to the explanation of the effect.

[0190] In Figure 3cShown on the right is a cross-section through the first or third brake gap section 5a, 5c in the region of the disc contour 41. The disc contour 41 provides a disc body 42, which here is applied to the core 21 or is formed integrally thereon as an annular flange. Radially outward between the outer contour of the disc contour 41 and the inner circumference of the casing part 13, a gap height 41b results, which is considerably smaller and can be selected to be considerably smaller than the radial clearance 11c in the second brake gap section 5b. The disc body 42 can be solid or can be formed as a disc pack 44 and comprise a plurality of disc sheets 46. The first and third brake gap sections 5a, 5c can fundamentally have identical or similar cross-sections.

[0191] Only as an example, in the right part of Figure 3cA rolling element 11 is shown in dashed lines to illustrate the differences. It is clearly visible that the disc body 42 allows for a smaller gap height 41b. This allows for a strong braking torque and a high magnetic field strength to be achieved and transmitted there. The desired magnetic field strength and braking effect can be independently adjusted via the other electrical coil in the second braking gap section 5b. Both magnetic fields are closed via the third braking gap section 5c.

[0192] In the middle of Fig. 3cA cross-section of another embodiment of a brake gap section is shown. This brake gap section has a disk contour 41 designed as a star contour 40. The star contour 40 has a non-circular circumferential surface. This creates a brake gap section with a gap height 40c that varies over the circumference. This can also create a type of wedge effect and, particularly at low speeds, allow a high torque to be set. The elements projecting radially outward (or inward) can be referred to as magnetic field concentrators 80, which concentrate the magnetic field locally. A star contour 40 can also be designed as a disk pack 44 and comprise a plurality of (e.g., star-shaped) disk plates 46.

[0193] A star contour can also be formed in the axial direction, meaning that gap heights vary along the axial direction. This allows the magnetic field to be concentrated in the axial direction at locations with smaller gap heights and reduced in the higher gaps. A mixture of "radial" and "axial" and / or oblique star contours is also conceivable.

[0194] In particular, this design is suitable for the second brake gap section 5b as a replacement for a (second) brake gap section (5b) with rolling elements.

[0195] In Figure 4aThe sensor device 70 is shown in detail. The first brake component 2 and the second brake component 3, embodied here as a casing part 13, are only indicated (dashed lines). The sensor device 70 is supported, magnetically decoupled, on the rotatable second brake component via the decoupling device 78. The shielding device 75 here consists of three shielding bodies 76, which reduce the scattering of the magnetic field 8 of the electrical coil 26. The shielding device 75 can also consist only of pot-shaped bodies or a pot-shaped body and a disk-shaped body that are connected to one another.

[0196] In addition, a separating unit 77 for magnetic separation is also provided. The magnetic ring unit 71 is used to measure the orientation or the angle of rotation of the magnetorheological braking device 1. The magnetic field sensor 72 is arranged within the first braking component 2, which is not magnetic in this area. Small relative axial displacements, such as those caused by actuating a snap disk, can be used to detect the actuation of the operating button 101, as Figure 4b The angle of rotation and the orientation of the magnetic field lines indicated by arrows can be detected by the magnetic field sensor 72.

[0197] By an axial displacement, the received signal 68 of the sensor device 70 changes as shown in Figure 4b. Figure 4bshows the curve of the amplitude 69 of the signal 68 detected by the magnetic field sensor 72 as a function of the axial displacement of the brake components 2, 3 relative to one another. An axial displacement of the magnetic field sensor 72 relative to the magnetic ring unit 71 changes the amplitude 69 of the detected signal 68. An axial displacement or pressing of an operating button 101 can thus be detected.

[0198] The same sensor 72 can also be used to detect the angle of rotation, whereby the direction of the magnetic field 8 (arrows shown) is determined to detect the angle of rotation. The intensity determines the axial position. A change in signal 68 can therefore be used to infer that a button or snap-action disc 29 has been actuated. This is advantageous because a single (multidimensional) Hall sensor can be used to determine the angular position and the axial position.

[0199] Figure 6shows purely schematically two differently designed electrical coils 261, 262, whereby the number of windings can differ. The size / type of diameter and shape and material of the wires 263, 264 can also be different. The size and external shape of the electrical coils 261, 262 can be the same (shown with a solid line) or different; for example, the second electrical coil 262 can have a smaller cross-section, as shown with a dashed line. This makes it possible to set different properties on the magnetic circuits. One magnetic circuit can be designed for a faster reaction speed and / or a higher braking torque, while the other can be designed with better and / or more energy-efficient braking properties. A wide variety of combinations of properties can be achieved. The material on the braking gap sections can also be different.

[0200] Figure 7 shows a schematic cross-section of another braking device 1, wherein the first braking component 2 is mounted on a holder 4 formed as an axle 12. This embodiment also provides three braking gap sections 5a, 5b, 5c, wherein a disc contour 41 is formed on the first braking gap section 5a, and rolling elements 11 or rotating elements are mounted on the circumference of the core 21 on the second braking gap section 5b. The rolling elements 11 are guided via holders 11f.

[0201] A reservoir 32 for magnetorheological particles may be provided inside to ensure a sufficient supply of magnetorheological particles to the brake gap sections. In particular, carbonyl iron particles are attracted from the environment and concentrated in the magnetic field transition region.

[0202] In Figure 7A cover 14 is attached to the front (left) end and a cover 15 is attached to the rear end.

[0203] The disk body 41 is formed in one piece with the core 21, but can also be formed as a disk package 44 with several disk sheets 46.

[0204] A cable duct 12a is formed on the hollow shaft 12, through which the cables for supplying the two electrical coils 261 and 261 pass. The (separate) core 21 is accommodated on the inner part. The two electrical coils 261 and 262 are wound on the core 21 on coil holders 26b. The annular contour 61 for the third braking gap section 5c is accommodated or formed between the two electrical coils 261 and 262. In simple embodiments, the annular contour 61 is applied to the core 21 as a separate part and provides a thin gap between the outer side of the annular contour 61 and the inner circumference of the casing part 13. The third braking gap section 5c serves to close the two magnetic fields of the two electrical coils 261 and 262.

[0205] The magnetic field of the first electrical coil 261 extends substantially radially through the first brake gap section 5a and the third brake gap section 5c and axially through the core 21 and the casing part 13. The magnetic field of the second electrical coil 262 extends substantially radially through the second brake gap section 5b and the third brake gap section 5c and axially through the core 21 and the casing part 13. The two electrical coils 261, 262 are wound and energized in such a way that the magnetic fields of the two electrical coils 261, 262 extend in the same direction in the region of the third brake gap section 5c, as also schematically shown in Fig. 3b shown.

[0206] Overall, a very cost-effective braking device 1 is provided, whereby at least one bearing can be eliminated by "bearing" via the disc contour 41, which also reduces the overall height. A significantly lower base friction is achieved. The use of fewer parts makes production simpler and more cost-effective. A smaller number of parts also improves tolerance requirements, as tolerance chains are avoided.

[0207] A braking torque can be set separately using the two electrical coils 261, 262.

[0208] Figure 9 shows a schematic diagram of a circuit for quickly controlling the electric coil 26. The electric coil 26 (magnetic coil) is controlled by an H-circuit. This is shown in the Figure 9only indicated by switches. A voltage source 35a with a lower voltage of, for example, 12V, used during normal operation or continuous operation, supplies the voltage for normal operation. For voltage peaks, a voltage source 35b with a higher voltage of, for example, 18V or 24V is connected in via a switch. The voltage source 35a with the lower voltage is then temporarily disconnected. After the maximum current is reached, the voltage source 35b with the higher voltage is disconnected from the circuit and the electrical coil 26 again, and the voltage source 35a with the lower voltage is reconnected. The switches can be any electrical components that are particularly capable of coupling and decoupling in the millisecond range.

[0209] This allows the current in the electrical coil 26 to reach the desired value more quickly. In one specific case, the desired current is reached within 10 ms instead of 40 ms. The switching between the voltages can be accomplished via an electrical circuit.

[0210] Figure 10shows a schematic representation of two generated braking torque curves, with the generated braking torque (standardized and therefore dimensionless here) plotted against the electrically applied power (standardized and therefore dimensionless here). The curve for a BLDC motor ("brushless direct current motor") is shown on the left, and the curve for a magnetorheological braking device is shown on the right. It can be seen that for the same braking torque, the electric motor requires considerably more power than the magnetorheological braking device. For a braking torque of "14", the electric motor requires more than "130" of standardized power, while the magnetorheological braking device requires (significantly) less than "0.3". The power consumption ratio is greater than 100:1 and is approximately 500:1 here.

[0211] Magnetorheological clutches and brakes have the advantage, among other things, that they require very little power for clutch engagement or damping movements, are quiet, generate little heat, and respond very quickly (~ms), etc. This low power requirement is particularly advantageous for battery-powered components such as electric vehicles, where the power consumption of all components automatically has a significant impact on the vehicle's range. However, power consumption is also an issue for vehicles with combustion engines or electrical devices in general.

[0212] The system requires much less power than a drive system powered solely by an electric motor. Generally speaking, electric vehicles currently travel about 6 km with 1 kWh of battery capacity, while one kWh of battery capacity costs approximately €230, with each kWh adding about 6 kg to the weight. Even if these figures will change in the future, energy consumption will continue to play an important role. Figure 11 shows the resulting braking torque curves of a magnetorheological braking device 1 for two different current curves over time. The dashed curve in the upper half of the figure represents the conventional curve, in which the current is increased directly to the desired current.

[0213] Here, at time 0.1 seconds, the current is increased from 0 amperes to 2 amperes. The resulting braking torque curve, or coupling intensity, is shown in dashed lines in the lower half of Figure 13. The transmittable braking torque increases in the dashed curve from the starting time at 0.1 seconds within approximately 25 milliseconds (time 0.125 seconds) to a read value of approximately 1.25 (normalized to, for example, an average value or a standard unit) and asymptotically (almost) reaches the set limit of approximately 1.5 after approximately 75 milliseconds (time 0.175 seconds).

[0214] However, if the current is tripled at the beginning of the clutch engagement or braking process, for example, to 6 amps, as shown by the solid lines, the braking torque increases significantly, reaching its final value of 1.5 amps after only about 10 milliseconds. The "current boost" with increased current is only activated for about 10 ms. After that, as the upper solid curve shows, the current is reduced to 2 amps. The brief increase in current ("current boost") allows for a significantly faster adjustment of the clutch or braking torque. This is very advantageous in several respects, as it allows for a quick stop and a more direct haptic sensation.

[0215] A major advantage of the design is that no cables, sensors, or electronics are required externally. This allows for a high IP rating for all configurations. Essentially, everything is located behind a mounting panel.

[0216] The electrical coils are preferably completely separated from the space containing the magnetorheological medium, in particular by means of a potting compound.

[0217] In preferred embodiments, axial displacement is possible, with a fluid volume being displaced within the housing. Sufficient space is preferably provided between a cover and a disk contour to prevent compression of the intermediate medium (or fluid) (carbonyl). (This could otherwise lead to high axial displacement forces.) This provides an additional MRF reservoir from which particles can flow into the area of ​​the disk contour or the rolling elements. Magnetic particles always flow in the direction of the stronger field, as magnetic particles are attracted by the magnetic field gradient.

[0218] The seal preferably runs on the shaft. There is a rotational movement (more than 100,000 revolutions are possible), and there may be a linear movement for the probe. To prevent the seal from running in and forming a groove, to keep friction low, and to prevent leakage (drag oil) from becoming excessive over its service life, a suitable material pairing with a hard running surface is preferred.

[0219] Preferably, the first brake gap section 5a is equipped with a disk-shaped design. The second brake gap section 5b is equipped with rolling elements, particularly rollers. Rolling elements, particularly rollers, with a round inner ring enable a high static torque. A disk-shaped design enables good magnetic field transmission and high torque at high speeds.

[0220] The combined solution, also called a hybrid solution, combines both advantages. In contrast, an axial transition of the magnetic field in the prior art had a smaller transition area and thus resulted in lower braking torques. Furthermore, an axial magnetic field transition has a smaller distance (radius) and therefore generates less torque. A brake gap section 5a, which is also radial and has a disk contour, has a larger diameter and thus generates a greater torque for the same force. Furthermore, the surface area is larger because the larger circumference spans a larger area. If the width of the contoured disk is greater than 1 / 6 of the diameter, the transferable braking torque at the (circumferential) radial brake gap section is already greater than the maximum transferable braking torque on the axial surface! Finally, the smaller gap height at the disk contour reduces magnetic losses. All of this results in a higher braking torque, even at higher speeds.

[0221] Volume compensation for the push function can be provided by a membrane at the end of the casing. Behind the membrane is a click element, similar to a snap dome. This provides a tactile pressure point. Additionally, a click is heard when the pressure point is reached, and the snap dome pushes the entire button or casing back to its original position (similar to a mouse button on a computer mouse).

[0222] The diaphragm then seals the MRF chamber. The volume behind the diaphragm acts as a volume compensator when pressed. In its normal position, the snap-action disc is curved. If the button is moved axially, the stator of the braking device presses against the diaphragm and the snap-action disc, flattening the disc.

[0223] The transparent material can be either regular glass or PMMA (acrylic glass). The advantage of PMMA is that you can use opaque glass, which refracts the light within, thus evenly illuminating the entire surface. One or more LEDs can be used for illumination, even in different colors.

[0224] In all configurations, the outer brake component can also be designed to be non-rotatable, while the inner brake component can be the rotatable component. In this case, the electrical contact with the electrical coil must be made via cables through the outer brake component or, for example, via sliding contacts.

[0225] With the invention presented here, the required working range of the steering device 100 can be divided into several sub-ranges. A first sub-range is provided by the drive device 307 and offers an active drive torque, e.g., between 0 and 8 Newton meters. A second sub-range is provided by the first brake gap section 5a and offers a braking torque, e.g., between 0 and 5 Newton meters. A third sub-range is provided by the second brake gap section 5b and offers a braking torque, e.g., between 0 and 25 Newton meters. Due to the disc contour 41 in the first brake gap section 5a, a particularly high control quality can be achieved for the first sub-range. Since this sub-range is particularly crucial for steering precision, the high control quality here has a particularly advantageous effect on the steering behavior.

[0226] The steering device 100 presented here also has the advantage that the required active torque (drive torque) can be achieved by a compact and agile electric motor with high control quality and lower power consumption (better efficiency in the partial load range). The required low passive torque (braking torque, for example, up to 8 Newton meters) is achieved here by the first brake gap section 5a, which features particularly low basic friction and high control quality while simultaneously utilizing low power consumption. The required higher passive torque (braking torque, for example, up to 25 Newton meters) is achieved here by the second brake gap section 5b, which also features particularly low basic friction and normal control quality while simultaneously utilizing low power consumption. This results in triple redundancy.

[0227] At the same time, the steering movement can be controlled silently and smoothly. Furthermore, the braking device 1 can brake the active torque of the drive device 307 in the event of a malfunction. Furthermore, the braking device 1 can smooth or compensate for a motor curve (fluctuating torque over the angle of rotation). Furthermore, the braking device 1 requires considerably less power than an electric motor to generate a comparable braking torque.

[0228] The presented steering system can also be used in combination with the on-board computer, display instrument, or a head-up display as a game console or as a driving or flight simulator. When the vehicle is parked (e.g., in electric vehicles during charging) or the car is in self-driving mode, the user can use the steering system as an input device for a computer game. Haptic feedback is preferably provided when switching from gaming mode to real-world driving.

[0229] Certain steering system parameters can also be customized, configured, or saved via the on-board computer or other input devices (customization), within system limits. Individual settings can be accessed via key recognition, smartphone or smart device communication, driver recognition (image recognition; facial recognition), gesture control, voice control, data analysis, or manual input. List of reference symbols:

[0230] 1 Magnetorheological braking system 39 O-ring 40 Star contour 2, 3 Brake component 40c Gap height 4 holder 41 Disc contour 5 gap 41a integral ring flange 5a Brake gap section for 41 41b Gap height of 5a 5b Brake gap section for 11 41e axial width of 5a 5c Brake gap section for 61 42 Ring body, disc body 5d Brake gap section 42a Recording 6 medium 43 User interface 8 magnetic field, field 44 Disc package 11 Rolling elements 45 Cable 11b Gap height of 5b 46 Disc sheet 11c radial clearance at 5b 47 bulged outer contour 11d Diameter of 11 48 Filling screw 11e axial width of 11 49 coating 11f bracket 50 console 12 axis 51 Mother 12a Cable entry 61 Ring contour 13 Coat part 68 signal 14 end, lid 69 amplitude 15 end, lid 70 Sensor device 16 Pen 71 Magnetic ring unit 18 Light bulbs 72 Magnetic field sensor 19 magnetic particles 75 Shielding device 20 Rotation axis, axial direction 76 Shielding body 77 Separation unit 21 core 78 Decoupling device 22 Hub 79 Sensor board 23 rotary knob 79a Contact pin 26 Sink 80 Magnetic field concentrator 26b spool holder 100 Steering device 26e axial width 101 Control head 28 Potting compound 102 Operating roller 29 Snap dome 110 closed chamber 29a guide 200 Device component 29b volume 261 electric coil 31 membrane 262 electric coil 32 reservoir 263 wire 35a Power supply 12V 264 wire 35b Power supply 18V 301 steering unit 38 seal 302 Steering control unit 303 Actuator device 311 steering shaft 304 Driver assistance system 305 Remanence device 306 Safety device 307 drive device

Claims

1. A steering device (100), in particular a steer-by-wire steering for steering a vehicle by means of a movable steering unit (301), wherein movements of the steering unit (301) can be braked by means of at least one magnetorheological braking device (1), and wherein the braking device (1) comprises a stationary holder (4) and at least two brake components (2, 3), wherein at least one of the two brake components (2, 3) is provided for rotation by the steering unit (310), and wherein at least one other of the two brake components (2, 3) is non-rotatably connected with the holder (4), and wherein the two brake components (2, 3) are provided for continuous rotation relative to one another around a rotational axis (20), wherein a first brake component (2) extends along the rotational axis (20) and comprises a core (21) of a magnetically conductive material, and wherein the second brake component (3) comprises a sheath part (13) configured hollow and extending around the first brake component (2), wherein between the first and second brake components (2, 3) at least one circumferential gap (5) is configured, which is at least partially filled with a magnetorheological medium (6), characterized in that the gap (5) comprises at least two different brake gap sections (5a, 5b), and that in a first brake gap section (5a), a disk contour (41) is configured between the sheath part (13) and the core (21), and that in a second brake gap section (5b), a plurality of rolling members (11) is disposed on the circumference of the core (21).

2. The steering device (100) according to the preceding claim, wherein, in actively influencing the magnetorheological medium (6), the braking device (1) shows a braking momentum, and in inactively influencing the magnetorheological medium (6), shows a base momentum, and wherein the base momentum is lower by the factor of 50 and preferably at least by a factor of 90, than is the maximum braking momentum that can be provided.

3. The steering device (100) according to any of the preceding claims, wherein the braking device (1), in inactively influencing the magnetorheological medium (6), shows a base momentum of maximally 0.5 Nm and preferably maximally 0.25 Nm, and / or wherein the braking device (1) enables to generate, by actively influencing the magnetorheological medium (6), a maximum braking momentum of at least 25 Nm and preferably at least 45 Nm.

4. The steering device (100) according to any of the preceding claims, wherein the second brake gap section (5b) can generate a braking momentum that is at least twice that generated by the first brake gap section (5a).

5. The steering device (100) according to any of the preceding claims, wherein the first brake gap section (5a) can set a braking momentum with a higher resolution than can the second brake gap section (5b), and wherein the first brake gap section (5a) preferably shows a resolution higher at least by a factor of 10 than does the second brake gap section (5b), and wherein the first brake gap section (5a) can generate a braking momentum with a resolution of at least 0.5 Nm and preferably at least 0.25 Nm.

6. The steering device (100) according to any of the preceding claims, wherein a first electric coil (261) is assigned to the first brake gap section (5a), and a second electric coil (262) provided to be actuated separately, to the second brake gap section (5b).

7. The steering device (100) according to any of the preceding claims, comprising at least one steering control device (302) for actuating the braking device (1) in dependence on the position of the steering unit (301) and / or the movement parameter of the steering unit (301) and / or the operating state of the vehicle, wherein the at least two brake gap sections (5a, 5b) can be actuated separately by the steering control device (302), and wherein the steering control device (302) is suitable and configured, in dependence on the strength of a braking momentum provided to be set, to select at least one brake gap section (5a, 5b) of the at least two brake gap sections (5a, 5b), to thereby decelerate the movement of the steering unit (301).

8. The steering device (100) according to the preceding claim, wherein the steering control device (302) is suitable and configured to block the movability of the steering unit (301) and to generate the braking momentum required therefor, predominantly and preferably with the second brake gap section (5b) only.

9. The steering device (100) according to any of the two preceding claims, wherein the steering control device (302) is suitable and configured, in dependence on a driver assistance system (304), to brake or even to block the movability of the steering unit (301), so that for example critical steering movements can be prevented, and to this end, to select and actuate at least one brake gap section (5a, 5b) of the at least two brake gap sections (5a, 5b).

10. The steering device (100) according to any of the three preceding claims, wherein the steering control device (302) is suitable and configured to take into account a user characteristic for setting and adjusting the braking momentum and / or to determine the user's behavior by means of at least one algorithm of machine learning and to take it into account for setting and adjusting the braking momentum.

11. The steering device (100) according to any of the preceding claims, wherein the magnetorheological medium (6) comprises at least one metallic powder, and wherein the metallic powder has a volume fraction of at least 50% and preferably, at least 60 %, and wherein the metallic powder is in particular provided with a coating.

12. The steering device (100) according to any of the preceding claims, comprising at least one remanence device (305) and / or at least one permanent magnet unit, which is suitable and configured, even absent electricity supply, to maintain a braking momentum with at least one of the at least two brake gap sections (5a, 5b, 5c).

13. The steering device (100) according to any of the preceding claims, comprising at least one driving device (307) for generating a driving torque for actively moving the steering unit (301), and wherein the maximum braking momentum of the second brake gap section (5b) is in particular at least twice the maximum driving torque of the driving device (307).

14. The steering device (100) according to any of the preceding claims, wherein the disk contour (41) comprises at least one star contour (40), so that in the region of the star contour (40) a variable gap height (40c) ensues over the circumference of the brake gap section (5a), and wherein magnetic field concentrators (80, 81) are disposed on the star contour (40), which protrude radially into the brake gap section (5a).

15. The steering device (100) according to any of the preceding claims, wherein at least three brake gap sections (5a, 5b, 5c) are provided, and wherein at least one third brake gap section (5c) is disposed axially between a first brake gap section (5a) and a second brake gap section (5b), and wherein at least one first electric coil (261) is assigned to the first brake gap section (5a), and at least one second electric coil (262) provided to be actuated separately, is assigned to the second brake gap section (5b).

16. The steering device (100) according to the preceding claim, wherein the first electric coil (261) and the second electric coil (262) are each accommodated between the sheath part (13) and the core (21) and are each wound around the the rotational axis (20).

17. The steering device (100) according to any of the two preceding claims, wherein the first electric coil (261) and the second electric coil (262) are configured differently, and wherein the first electric coil (261) and the second electric coil (262) differ in at least one parameter from a group of parameters comprising, as a parameter, the wire diameter and the wire cross section, the number of coils, the coil window, the winding type, the coil width, the coil diameter, and the material.

18. A method for operating a steering device (100) with a magnetorheological braking device (1) with two brake components (2, 3), wherein the two brake components (2, 3) are provided for continuous rotation relative to one another around a rotational axis (20), wherein the first brake component (2) extends along the rotational axis (20) and comprises a core (21) of a magnetically conductive material, and wherein the second brake component (3) comprises a sheath part (13) configured hollow and extending around the first brake component (2), wherein between the first and second brake components (2, 3) at least three brake gap sections (5a, 5b, 5c) are configured, which are axially spaced apart and circumferential and at least partially filled with a magnetorheological medium (6), characterized in that a first electric coil (261) generates a controlled magnetic field in a first and a third brake gap section (5a, 5c), and that independently thereof, a second electric coil (262) generates a controlled magnetic field in the second and third brake gap sections (5b, 5c), to generate braking actions of different strengths, dependent on the rotational speed.