Steering device

Abstract

Steering device (1) comprising - a rotatably mounted steering shaft (2) which can be coupled to a steering means (3), and - an electromotive force feedback actuator (4) with a stator (5) and a rotor (6) which is rotatable relative to the stator (5) and which is connected to the steering shaft (2) in a torque-transmitting manner, wherein the stator (5) has a plurality of stator teeth (9) protruding from a stator yoke (8) and each of the stator teeth (9) is wound by at least one energizable stator winding (7), and - a magneto-rheological brake (10) with an electromagnet (36) that can be energized via a magnet coil (11) and a magneto-rheological material (13) on which the magnetic field of the electromagnet (36) can act, wherein the magneto-rheological brake (10) is connected to the steering shaft (2) in a torque-transmitting manner, the magnet coil (11) of the magneto-rheological brake (10) is arranged in and / or on the stator yoke (8) of the electromotive force-feedback actuator (4), and the stator teeth (9) protrude radially from the stator yoke (8), characterized in that the stator yoke (8) has a cylindrical ring-like groove (18) formed radially below the stator teeth (9) and in which the magnet coil (11) is received, and the rotor (6) has a radially inner hollow cylinder (19) and a radially outer hollow cylinder (20) extending coaxially thereto,wherein the radially inner hollow cylinder (19) is connected to the radially outer hollow cylinder (20) via an annular disc (21) and the inner hollow cylinder (19) and the outer hollow cylinder (20) axially cover the stator (5).

Description

[0001] The present invention relates to a steering device comprising a rotatably mounted steering shaft which can be coupled to a steering means, and an electromotive force feedback actuator with a stator and a rotor which can be rotated relative to the stator and which is connected to the steering shaft in a torque-transmitting manner, wherein the stator has a plurality of stator teeth protruding from a stator yoke and each of the stator teeth is wound by at least one energizable stator winding, and a magnetorheological brake with an electromagnet which can be energized via a magnetic coil and a magnetorheological material on which the magnetic field of the electromagnet can act, wherein the magnetorheological brake is connected to the steering shaft in a torque-transmitting manner.

[0002] Electric steering systems are used - among other things in motor vehicles - to receive a driver's directional command and translate it into corresponding movements of one or more wheels. In contrast to purely mechanical steering systems, electric steering systems are divided into electrically assisted steering systems and fully electric steering systems, so-called "steer-by-wire" steering systems. These steer-by-wire steering systems in particular have the advantage that the control unit can be positioned relatively freely within the vehicle, independent of mechanical connecting components. This not only saves costs when distinguishing between, for example, right- and left-hand drive vehicles, but also improves accident behavior due to the absence of a steering column. Furthermore, the control unit can be moved into a stowed position, which is also used, for example, in fully automatic steering.

[0003] A steer-by-wire steering system, as defined in the present invention, is a steering system that essentially consists of a so-called handwheel actuator (HWA), for example, the actuator system around the commanding vehicle steering wheel, and a roadwheel actuator (RWA), i.e., the actuator system acting on the steering mechanism connected to the vehicle wheels. The steering signal is transmitted from the HWA to the RWA via a cable ("by wire").

[0004] To create a realistic driving experience, it is also known in the prior art to record parameters such as vehicle speed, steering angle, lateral acceleration, tie rod force, and the like from an actual, current driving situation or to calculate them in a simulation, and to use these to generate a feedback signal that is fed into a force feedback actuator. The force feedback actuator is integrated into the input unit and has an actuator unit that includes an actuator that serves as a manual torque or steering wheel actuator and, depending on the feedback signal, couples a feedback torque (feedback torque) that at least partially corresponds to the actual reaction torque via the steering shaft into the steering wheel. A partial feedback torque is particularly suitable when other, possibly controllable, components such as springs or brakes provide supplementary feedback torque.Feedback torque refers to both directions of action, meaning that the feedback actuator can be rotated by the driver as an adjustable load. Such "force feedback" systems give the driver the impression of a real driving situation, similar to a conventional steering system, facilitating intuitive response.

[0005] DE 102008036730 A1 discloses a steer-by-wire steering system with an input unit that includes an actuator unit driven by an electric motor. The electric motor can be controlled by an electronic control unit, which adjusts the motor current depending on measured values that characterize the respective driving situation. The motor shaft is directly coupled to the steering shaft, thus the motor torque is identical to the manual torque coupled to the steering shaft. The electric motor is flanged axially to the casing unit with respect to its longitudinal axis, and the motor shaft is connected via a coupling to the steering shaft mounted in the casing unit. An actuator unit of a similar design is described in EP 2414211 B1. In the embodiment described therein, the steering shaft itself forms the motor shaft of the electric motor, allowing for a more compact design.

[0006] In this context, it is also known to equip electric motor-driven force feedback actuators with a gear for improved adjustment of speeds and torques. For example, electric motors with a worm drive at the end of the steering column, which are connected to the steering wheel by a shaft, are known. An example of this embodiment can be found in DE102018101528B4. With these gears, comparatively high gear ratios and thus high torques can be achieved or maintained; however, the relatively large installation space requirement and the angled design are often disadvantageous. Furthermore, such force feedback actuators coupled with a worm drive usually have to be optimized with great effort in terms of precision and material selection with regard to friction (usually too high) and uniformity of friction (usually too uneven).

[0007] In addition to worm gears, it is also known to connect an electric motor of a force-feedback actuator to a planetary gear at the end of the steering column, as described, for example, in CN215706606U. However, planetary gears typically only achieve moderate gear ratios and thus torques in one stage. Utilizing friction or lost torque for force feedback requires additional effort and friction devices.

[0008] Direct-drive force feedback actuators, sometimes also referred to as "direct drive," are also known. Examples of such designs can be found, for example, in CN112644580B or DE102018101528B4. Such direct-drive force feedback actuators generally require a telescopic steering shaft at the far end of the steering column, which is associated with increased costs and space requirements. Steering columns with a direct-drive force feedback actuator near the steering wheel are shown, for example, in EP3960583A1 and EP3476692B1.

[0009] To achieve the most realistic steering feel possible in such steer-by-wire systems, it is also known to place a magnetorheological brake in the torque flow of a steering device to increase the resistance torque. In combination, this allows for a higher total restoring torque with lower energy consumption in the same installation space. However, such combinations are still comparatively large and expensive to manufacture.

[0010] DE 102 21 241 A1 discloses a steering device that can be coupled to a rotatably mounted steering shaft. Furthermore, the steering device comprises an electromotive force feedback actuator with a stator and a rotor rotatable relative to the stator, and a magneto-rheological brake (cf.

[0021] ) with an electromagnet that can be energized via a magnet coil. The magnet coil of the magneto-rheological brake is arranged within the stator of the electromotive force feedback actuator.

[0011] From DE 10 2015 226 099 A1 a steering device with an electronically commutated electric machine is known, which comprises a stator yoke with protruding stator teeth.

[0012] In light of this prior art, it is now the object of the invention to provide a steering device for a motor vehicle which at least reduces the problems and disadvantages known from the prior art.

[0013] This object is achieved by a steering device comprising a rotatably mounted steering shaft which can be coupled to a steering means, and an electromotive force feedback actuator with a stator and a rotor which can be rotated relative to the stator and which is connected to the steering shaft in a torque-transmitting manner, wherein the stator has a plurality of stator teeth protruding from a stator yoke and each of the stator teeth is wound by at least one energizable stator winding, and a magnetorheological brake with an electromagnet which can be energized via a magnet coil and a magnetorheological material on which the magnetic field of the electromagnet can act, wherein the magnetorheological brake is connected to the steering shaft in a torque-transmitting manner, wherein the magnetorheological brake of the magnetorheological brake is arranged in and / or on the stator yoke of the electromotive force feedback actuator.

[0014] This provides the advantage that the stator is used both for the stator winding and to accommodate the magnetic coil, thus reducing both weight and assembly effort. The stator of the electromotive force-feedback actuator and the winding support of the magnetic coil are thus constructed as a single piece. Furthermore, the elimination of assembly interfaces allows for increased rigidity by using a single-piece component for the stator winding and the magnetic coil.

[0015] This also allows the stator to be designed more compactly, because part of its material, particularly in the so-called "back connection," carries the field of both winding systems—that of the stator winding and that of the magnetic coil. Therefore, less overall material can be used, which can contribute to a corresponding weight reduction.

[0016] The compact steering device can be used both away from the steering wheel and close to the steering wheel due to its low weight.

[0017] The magnetorheological brake can be designed as a powder brake, which is based on the well-known effect that, for example, iron powder clumps together under the influence of a magnetic field, or forms threads along the field lines. These threads or clumps generate a braking force or braking torque through magnetic adhesion between a moving and a stationary iron part. When the magnetic field is deactivated, the braking effect decreases as desired, which is due on the one hand to the subsequent isolation of the typically 10-100 µm small particles, and on the other hand to the particle displacement from the shear zones to neighboring rest zones. A magnetic field gradient exists in the rest zones, so that when the brake is activated, the particles migrate back from the rest zones to the shear zones. The magnetorheological powder is therefore surrounded by air or a gas, which is easily compactable and has a low viscosity.

[0018] Alternatively, the medium can be a liquid, particularly preferably a magnetorheological fluid. Magnetorheological fluids have the property of being able to change their viscosity by several orders of magnitude depending on the magnetic field passing through them. The term "magnetorheological fluid" (MRF) thus refers to fluids that react to a magnetic field similarly to ferrofluids, but unlike ferrofluids, solidify. Magnetorheological fluids, for example, consist of a suspension of micrometer-sized magnetic particles that are one to three orders of magnitude larger than the particles of ferrofluids. The relatively large particles of magnetorheological fluids form chains when a magnetic field is applied. This increases the viscosity of the MRF and can even solidify it if the applied compressive force is not large enough to break the chains.

[0019] According to an advantageous embodiment of the invention, the electromotive force-feedback actuator can be configured as an axial flux machine, with the stator teeth protruding axially from the stator yoke. The advantage of this embodiment is that the axial flux machine enables particularly compact steering devices.

[0020] In this context, it is particularly preferred that the magnetic coil of the magneto-rheological brake is arranged in the axial direction on the side of the stator yoke facing away from the stator teeth, which enables a particularly compact design and a magnetically particularly efficient construction of the stator.

[0021] According to a further preferred development of the invention, the rotor can also be disk-shaped and rotationally fixedly connected to a cup-shaped outer sleeve, with the stator housed within the cup-shaped outer sleeve. This creates an encapsulation, which holds the active components and magnetorheological medium in place and also protects them from dirt ingress. Modern steering wheels with a multitude of control elements in the center thus already incorporate the "base" of the cup-shaped design, making it advisable to simply add the side wall of the cup.

[0022] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that a first circumferential seal is arranged between the stator and the rotor and / or between the stator and the outer sleeve, and a second circumferential seal is arranged between the outer sleeve and a cylinder section extending axially from the stator yoke, so that a receiving space for the magnetorheological material is defined within the outer sleeve. The advantageous effect of this embodiment is based on the fact that a comparatively high degree of system integration of the magnetorheological brake and force feedback actuator can be achieved, which leads to a particularly compact design of the steering device.

[0023] According to another particularly preferred embodiment of the invention, an annular disc-shaped closure component can be arranged axially between the second seal and the magnetic coil, said closure component abutting the magnetic coil. This allows, in particular, a directed and advantageous guidance of the magnetic flux through the electromagnet to be achieved. The annular disc-shaped closure component is accordingly formed from a magnetic field-conducting material.

[0024] According to the invention, the stator teeth can protrude radially from the stator yoke. This allows the electromotive force feedback actuator to be configured as both a radial flux machine and a transverse flux machine.

[0025] Furthermore, the invention can also be further developed such that the electromotive force-feedback actuator is configured as a radial flux machine or transverse flux machine, with the stator teeth protruding radially from the stator yoke. Thus, the radial flux machine or transverse flux machine can generally be designed as an internal rotor or external rotor.

[0026] In a likewise preferred embodiment of the invention, the electromotive force-feedback actuator can also be configured as an external rotor, in which the stator teeth protrude radially outward from the stator yoke, which can offer particular manufacturing advantages. An external rotor motor designed in this way allows for a shear gap located far outward radially with high torque development and is well suited to the cup-shaped design of a steering wheel rotor. Furthermore, this design allows for simple winding techniques, since the teeth are accessible from the outside.

[0027] According to the invention, the stator yoke has a cylindrical ring-like groove which is formed radially below the stator teeth and in which the magnetic coil is accommodated, which can lead to a particularly compact design of the stator.

[0028] According to the invention, the rotor comprises a radially inner hollow cylinder and a radially outer hollow cylinder extending coaxially therewith. The radially inner hollow cylinder is connected to the radially outer hollow cylinder via an annular disk, and the inner hollow cylinder and the outer hollow cylinder axially cover the stator. This ensures good support for the rotor and protects the components located within the rotor from external mechanical influences.

[0029] Finally, the invention can also be advantageously implemented in such a way that the stator is formed from a solid material without any laminate. This provides the advantage that the use of a stator made of laminated electrical steel sheets can be dispensed with, which can significantly reduce the cost of stator production. This can also be helped by the fact that, compared to conventional stators made of laminated electrical steel sheets, additional components on winding heads or edge protection can be eliminated.

[0030] Particularly in the field of steering systems, the electromotive force-feedback actuator exhibits virtually identical power density and low losses compared to conventional stators made of stacked electrical steel sheets. Furthermore, the stator has a more compact, one-piece design than conventional stators made of stacked electrical steel sheets. The monolithic stator also allows for increased cooling of the winding compared to conventional stators made of stacked electrical steel sheets, which can contribute to improved efficiency and higher thermal reliability. Furthermore, the magnetic properties of the stator are improved compared to electrical steel sheets because there are no sheet joints or non-magnetic sheet laminations to impair the magnetic properties.

[0031] The stator can particularly preferably be made of pure iron. Pure iron, as defined in this application, is an iron material with a purity content of more than 75 wt% Fe, preferably more than 85 wt% Fe, most preferably more than 95 wt% Fe. Due to the pure iron construction, instead of, for example, a powder-metallurgical construction, i.e., a construction with residual pores and suboptimal magnetic properties, the stator has a high saturation flux density (= power density) and can be manufactured inexpensively.

[0032] Particularly preferred is the use of the steering assembly in a handwheel actuator (HWA) of a steer-by-wire system. Highest preferred is the use of the steering assembly in a handwheel actuator (HWA) of a steer-by-wire system, wherein the electromotive force feedback actuator is arranged in the HWA as an electromotive force feedback actuator close to the steering wheel.

[0033] The steering shaft can be connected to a steering mechanism in a rotationally fixed manner. The steering mechanism is preferably designed as a steering wheel. In principle, it would also be possible to design the steering mechanism as a steering bracket.

[0034] In connection with the steering device, it is particularly advantageous if the electromotive force feedback actuator has operating speeds of less than 300 rpm. It has also proven advantageous if the number of stator teeth is selected between 10 and 50, whereby the electromotive force feedback actuator can provide the torques preferred for a steering device.

[0035] It is further preferred that the electromotive force feedback actuator acts on the steering shaft without the interposition of a transmission. However, the steering system can also comprise a transmission. In particular, the transmission comprises an input shaft and an output shaft, with the electromotive force feedback actuator arranged on the input side and the steering shaft arranged on the output side. In particular, a power transmission path for transmitting the motor torque runs between the rotor via the transmission and the steering shaft. The rotor is preferably arranged coaxially with the steering shaft.

[0036] The electromotive force-feedback actuator and the gear unit can advantageously form a structural unit that can also be used as an electromotive drive or load unit. The electromotive force-feedback actuator can be designed as an axial flux motor or a radial flux motor. Furthermore, it is possible to design a motor configured, for example, as a radial flux motor with an internal rotor or an external rotor. If the electric motor is designed as an axial flux motor, it can be provided as a simple disc rotor, in an I-configuration, or in an H-configuration. Due to its axially compact design, an axial flux motor may be preferred in connection with the invention.

[0037] The electromotive force feedback actuator can be housed in a motor housing. It is also possible for the transmission to be housed in a transmission housing. Preferably, the motor housing and the transmission housing are formed integrally, at least in sections, and preferably completely, thus forming a structural unit.

[0038] According to an advantageous embodiment of the invention, the transmission can be provided with a ratio of 3-40. This also allows the electric motor to be designed smaller, which also has advantages in terms of reduced crash mass in the event of an accident. Furthermore, the eddy current losses of the electric force-feedback motor can be kept to a minimum.

[0039] According to an advantageous embodiment of the invention, the electromotive force-feedback actuator can be configured as an electric radial flux motor with a cylindrical ring-shaped stator yoke and stator teeth protruding in the radial direction. According to a further preferred development of the invention, the electromotive force-feedback actuator can alternatively be configured as an electric axial flux motor with a disk-shaped stator yoke and stator teeth protruding in the axial direction.

[0040] It is preferred that the stator teeth of the electromotive force-feedback actuator configured as an electric radial flux motor have rounded portions at their axial ends, which enables simplified and reliable winding of a stator winding around the stator teeth, since the risk of damage to the stator winding, in particular to the insulation of the stator winding, can be reduced by avoiding sharp edges during the winding process. The rounded portion is convexly directed outward and extends from one longitudinal side of a stator tooth to the other longitudinal side of the same stator tooth. The rounded portion is preferably semicircular.

[0041] Particularly with radial flux motors, it can be advantageous to take design measures on the stator to combat torque ripple that occurs during operation. Due to the magnetic forces acting on it, for example, in a permanent magnet synchronous motor with no current applied, a noticeable cogging occurs when the rotor is manually rotated. However, a similar effect that occurs when the motor is energized and under load is more problematic for the running characteristics of such a synchronous motor and is referred to in this context as load pulsation, torque fluctuation, torque ripple or "ripple torque". The load pulsation is hardly noticeable when the motor is idling (when no or only low torque is being tapped) if the number of poles is sufficiently high.However, if the motor is operated with a high torque reduction, the load pulsation can be clearly noticeable as a periodic torque fluctuation. The torque fluctuation typically follows a sine wave, corresponding to a higher harmonic of the torque change occurring at a pole pair.

[0042] A preferred approach is to reduce load pulsation by angling the rotor poles relative to the stator poles. In permanent-magnet synchronous motors, the magnetic poles formed on the stator can be tilted relative to the rotor's rotational axis. This angular position ensures that the entire cross-sectional area of the poles never faces each other, which, on the one hand, reduces the maximum torque but, on the other, also has a leveling effect on load pulsation.

[0043] It is therefore particularly preferred that the stator teeth have an interlacing along their axial extent, i.e., they are arranged tilted at an angle to the rotor's rotational axis. This interlacing can be linear or V-shaped along the axial extent of a stator tooth.

[0044] Furthermore, according to a likewise advantageous embodiment of the invention, the electromotive force-feedback actuator configured as an electric radial flux motor can be designed as an external rotor, with a cylindrical stator yoke and stator teeth projecting outward in the radial direction. The advantageous effect of this embodiment is that an external rotor can be wound particularly easily and thus cost-effectively. Furthermore, machining, for example by milling, is significantly easier, faster, and therefore more cost-effective for a stator with an external rotor than for an internal rotor.

[0045] According to another particularly preferred embodiment of the invention, the stator teeth can each have, at their free distal end, a tooth projection extending at least partially, preferably completely, around the stator winding. This can also contribute to simple and secure winding of a stator tooth, since the tooth projection can prevent the winding from slipping off the stator tooth. This benefit is already present with a partially circumferential projection.

[0046] It is further preferred that a stator tooth has radii formed at the transitions between tooth walls against which the winding rests, which can also contribute to optimized winding or protection of the winding and wire insulation from damage by edges.

[0047] Furthermore, the invention can also be further developed such that at least one bearing seat for a rolling bearing or a raceway for a rolling bearing is provided on the stator, with the rotor being rotatably mounted relative to the stator via the rolling bearing. The advantage of this design is that the increased degree of system integration allows for a particularly compact, low-tolerance, and cost-effective steering assembly to be provided.

[0048] In a likewise preferred embodiment of the invention, the stator can also be provided with at least one opening for passing the at least one stator winding through the stator yoke. This allows the electrical contacting of the windings or the winding interconnection to be carried out mechanically in the radially inner installation space or an axially adjacent installation space.

[0049] The manufacturing of the stator of the electromotive force feedback actuator of the steering device may include the following steps: - Provision of a blank formed from pure iron, - Formation of a stator from the blank by machining

[0050] Milling and drilling have proven particularly suitable machining methods in connection with the invention. In particular, the stator teeth and / or the receptacles for the magnetic coil can be formed by milling, preferably with profile cutters for the winding area with the overhang.

[0051] Alternatively, a casting process can be used to manufacture a stator of an electromotive force feedback actuator of a steering device, which then comprises, for example, the following steps: - Provision of a mold to form a stator - Filling the mold with a pure iron - Removing the mold and removing the stator

[0052] Preferably, pure iron in a flowable form is filled into the casting mold and subsequently solidifies in it.

[0053] In principle, it would also be possible to use an additive manufacturing process to produce the stator, which could then include, for example, the following steps: - Provision of an additive manufacturing device, - Provision of a data set representing the geometry of the stator, - Reading the data set into the production device, - Adaptive manufacturing of the stator by means of a layer-by-layer application of pure iron according to the data set representing the geometry of the stator by the manufacturing device

[0054] Such an additive manufacturing process differs significantly from conventional, abrasive manufacturing methods. Instead of milling a workpiece from a solid block, as is common with abrasive processes, for example, components in additive manufacturing are built up layer by layer from materials or raw materials, which are available as a starting material, particularly in the form of a fine powder. A laser, such as a CO2 laser, an Nd:YAG laser, or a fiber laser, or even an electron beam source, is typically used for processing, such as melting the raw material, which is usually in powder form.

[0055] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept.

[0056] It shows: Fig. 1 a motor vehicle with a steer-by-wire system in a schematic block diagram, Fig. 2 a steering device with a steering shaft and an electromotive force feedback actuator in a schematic representation, Fig. 3 a first embodiment of a steering device in a perspective axial section, Fig. 4 the stator of the steering device from the Fig. 4 in a cut-out, perspective axial section view, Fig. 5 a second embodiment of a steering device in a perspective axial section, Fig. 6 the stator of the steering device from the Fig. 5 in a cut-out, perspective axial section view.

[0057] The Fig. 1 shows a steering device 1 in a steer-by-wire system 34 for a motor vehicle 35. The electrical steering signals generated by the steering device 1 are transmitted to an RWA 33 (road wheel actuator), which then converts the steering signals into a corresponding position of the vehicle wheels.

[0058] As from the Fig. As can be seen in Figure 2, the steering device 1 comprises a rotatably mounted steering shaft 2, which can be coupled to a steering means 3, and an electromotive force feedback actuator 4 with a stator 5 and a rotor 6 that is rotatable relative to the stator 5 and connected to the steering shaft 2 in a torque-transmitting manner. A magnetorheological brake 10 is also arranged in the torque flow, by means of which an increase in the resistance torque against a steering movement of the user can be achieved. This is explained in more detail with reference to the following figures.

[0059] The Fig. Figure 3 shows a first embodiment of the steering device 1, comprising a rotatably mounted steering shaft 2, which can be coupled to a steering means 3, and an electromotive force feedback actuator 4 with a stator 5 and a rotor 6 rotatable relative to the stator 5, which is connected to the steering shaft 2 in a torque-transmitting manner. The stator 5 has a plurality of stator teeth 9 protruding from a stator yoke 8, and each of the stator teeth 9 is wound by at least one energizable stator winding 7.

[0060] Furthermore, the steering device 1 has a magneto-rheological brake 10 with an electromagnet 36 that can be energized via a magnetic coil 11 and a magneto-rheological material 13, which can be acted upon by the magnetic field of the electromagnet 36. By changing the magnetic field generated by the electromagnet 36, for example, the viscosity of the magneto-rheological material and thus the braking effect of the brake 10 can be adjusted. Like the rotor 6, the magneto-rheological brake 10 is also connected to the steering shaft 2 in a torque-transmitting manner.

[0061] The magnetic coil 11 of the magneto-rheological brake 10 is arranged in or on the stator yoke 8 of the electromotive force feedback actuator 4. For this purpose, a coil receptacle 32, formed as an annular groove, is provided in the stator yoke 8. The magnetic coil 11 is arranged as far radially inward as possible, which can contribute to low magnetic resistance.

[0062] The electromotive force feedback actuator 4 of the Fig. 3 is configured as an axial flux machine, with the stator teeth 9 protruding axially from the stator yoke 8. The rotor 6 is disk-shaped and rotationally fixedly connected to a pot-shaped outer sleeve 12, with the stator 5 being accommodated within the pot-shaped outer sleeve 12. The rotor magnets 28 are arranged in the disk-shaped rotor 6. The connection between the rotor 6 and the outer sleeve 12 is achieved by screw connections in the example shown. The rotor 6 is mounted relative to the stator 5 by the rolling bearing 23.

[0063] A first circumferential seal 14 is arranged between the stator 5 and the outer sleeve 12, and a second circumferential seal 16 is arranged between the outer sleeve 12 and a cylinder section 15 extending axially from the stator yoke 8, so that a receiving space for the magneto-rheological material 13 is defined within the outer sleeve 12. An annular disk-shaped closure component 17 is arranged axially between the second seal 16 and the magnetic coil 11 and rests against the magnetic coil 11. The closure component 17 can have a surface structure 27 in its radially outer region directed towards the outer sleeve 12, whereby a particularly good braking effect can be achieved in the gap between the surface structure 27 and the outer sleeve 12 extending radially in this region, in cooperation with the magneto-rheological material 13.

[0064] For filling or draining the magnetorheological material, a filling opening 29 is provided in the outer sleeve 12, which can be closed, for example, by a screw.

[0065] Furthermore, a roller bearing 22 is arranged on the cylinder section 15, which supports the rotationally fixed cylinder section 15 relative to the rotatable outer sleeve 12. Axial threaded bores 26 are provided on the end face of the cylinder section 15, by means of which the steering device can be attached, for example, to a telescopic extension.

[0066] Both the winding ends 24 of the stator winding 7 and the coil ends 25 of the magnetic coil 11 are guided radially inwards into the hollow cylindrical stator 5. For this purpose, corresponding lead-through openings 30, 31 are provided in the stator, which also fit well in the Fig. 4 can be seen. Further cable connections can also be routed through the hollow cylindrical stator 5, for example for connection to the steering device 3.

[0067] In the Fig. Figure 5 shows a further embodiment of the steering device 1, in which the electromotive force feedback actuator 4 is configured as a radial flux machine, with the stator teeth 9 protruding radially from the stator yoke 8. In the embodiment shown, the electromotive force feedback actuator 4 is configured as an external rotor, with the stator teeth 9 protruding radially outward from the stator yoke 8.

[0068] The stator yoke 8 has a cylindrical ring-like groove 18, which is formed radially below the stator teeth 9 and into which the magnetic coil 11 is accommodated. In the illustrated embodiment, the magnetic coil 11 is thus laterally offset, so that the enclosing stator 5 provides an effective outer cylindrical surface for the gap accommodating the magnetorheological material 13, where a high braking torque is generated.

[0069] The rotor 6 has a radially inner hollow cylinder 19 and a radially outer hollow cylinder 20 running coaxially thereto, wherein the radially inner hollow cylinder 19 is connected to the radially outer hollow cylinder 20 via an annular disc 21 and the inner hollow cylinder 19 and the outer hollow cylinder 20 axially cover the stator 5.

[0070] All stators 5 shown in the figures have in common that they are formed from a solid material without any laminate.

[0071] The invention is not limited to the embodiments illustrated in the figures. The above description is therefore not to be considered restrictive, but rather explanatory. The following claims are to be understood in such a way that a stated feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. Where the claims and the above description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing a priority. List of reference symbols 1 steering device 2 steering shaft 3 steering devices 4 Force feedback actuator 5 Stator 6 Rotor 7 Stator winding 8 Stator yoke 9 stator teeth 10 magnetorheological brake 11 Solenoid coil 12 Outer sleeve 13 magnetorheological material 14 Seal 15 Cylinder section 16 Seal 17 Closure component 18 grooves 19 hollow cylinders 20 hollow cylinders 21 Ring disc 22 rolling bearings 23 rolling bearings 24 winding ends 25 coil ends 26 threaded hole 27 Surface structure 28 rotor magnets 29 Filling opening 30 Feed-through opening 31 Feed-through opening 32 spool holder 33 smoke and heat extraction systems 34 Steer-by-Wire System 35 motor vehicle 36 electromagnets

Claims

[1] Steering device (1) comprising - a rotatably mounted steering shaft (2) which can be coupled to a steering means (3), and - an electromotive force feedback actuator (4) with a stator (5) and a rotor (6) which is rotatable relative to the stator (5) and which is connected to the steering shaft (2) in a torque-transmitting manner, wherein the stator (5) has a plurality of stator teeth (9) protruding from a stator yoke (8) and each of the stator teeth (9) is wound by at least one energizable stator winding (7), and - a magneto-rheological brake (10) with an electromagnet (36) that can be energized via a magnet coil (11) and a magneto-rheological material (13) on which the magnetic field of the electromagnet (36) can act, wherein the magneto-rheological brake (10) is connected to the steering shaft (2) in a torque-transmitting manner, the magnet coil (11) of the magneto-rheological brake (10) is arranged in and / or on the stator yoke (8) of the electromotive force feedback actuator (4), and the stator teeth (9) protrude radially from the stator yoke (8), characterized bythat the stator yoke (8) has a cylindrical ring-like groove (18) which is formed radially below the stator teeth (9) and in which the magnetic coil (11) is accommodated and the rotor (6) has a radially inner hollow cylinder (19) and a radially outer hollow cylinder (20) running coaxially thereto, wherein the radially inner hollow cylinder (19) is connected to the radially outer hollow cylinder (20) via an annular disc (21) and the inner hollow cylinder (19) and the outer hollow cylinder (20) axially cover the stator (5). [2] Steering device (1) according to claim 1, characterized by that the electromotive force feedback actuator (4) is configured as an axial flux machine, wherein the stator teeth (9) protrude in the axial direction from the stator yoke (8). [3] Steering device (1) according to claim 1 or 2, characterized bythat the rotor (6) is disc-shaped and is connected in a rotationally fixed manner to a pot-like outer sleeve (12), wherein the stator (5) is accommodated within the pot-like outer sleeve (12). [4] Steering device (1) according to claim 3, characterized by that a first circumferential seal (14) is arranged between the stator (5) and the rotor (6) and / or between the stator (5) and the outer sleeve (12), and a second circumferential seal (16) is arranged between the outer sleeve (12) and a cylinder section (15) extending axially from the stator yoke (8), so that a receiving space for the magneto-rheological material (13) is defined within the outer sleeve (12). [5] Steering device (1) according to claim 4, characterized by that an annular disc-shaped closure component (17) is arranged axially between the second seal (16) and the magnetic coil (11), which closure component rests against the magnetic coil (11). [6] Steering device (1) according to claim 1, characterized bythat the electromotive force feedback actuator (4) is configured as an external rotor in which the stator teeth (9) protrude radially outwards from the stator yoke (8). [7] Steering device (1) according to one of the preceding claims, characterized by that the stator (5) is formed from a solid material without any laminate.

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