Steering device with a magnetorheological braking device and method for operating a steering device
A vehicle Steering device with a movable steering unit that is braked by a braking device. The braking device has a stationary holder and two brake components. One brake component is rotated by the steering unit. One brake component is rotatably fixed to the holder. The brake component are continuously rotatable relative to one another about a rotational axis. A first brake component extends along the rotational axis and has a magnetically conductive core. The second brake component has a hollow casing part extending around the first brake component. A peripheral gap, filled with a magnetorheological medium, is arranged between the two brake components. The gap has two different braking gap portions. In a first braking gap portion, a disk contour is formed between the casing part and the core. In a second braking gap portion, a plurality of roller bodies are arranged around the circumference of the core.
1 . A steering device for steering a vehicle by, comprising:
a movable steering unit;
at least one magnetorheological braking device configured to brake a movement of said steering unit;
said braking device having a stationary holder and at least two brake components, at least one of said at least two brake components is rotatable by said steering unit and at least one other of said at least two brake components is non-rotatably connected to said holder;
said at least two brake components being continuously rotatable relative to one another about an axis of rotation;
a first brake component of said at least two brake components extending along said axis of rotation and having a core made of a magnetically conductive material, and a second brake component of said at least two brake components having a hollow casing part extending around said first brake component;
at least one circumferential gap formed between said first brake component and said second brake component, said at least one circumferential gap being filled at least partially with a magnetorheological medium; and
said gap having at least a first braking gap section and a second braking gap section, said first braking gap section having a disk contour formed between said casing part and said core, and said second braking gap section having a plurality of rolling elements arranged on a circumference of said core.
2 . The steering device according to claim 1 , further comprising an actuator device configured for converting a movement of said steering unit into a vehicle movement, wherein said steering unit and said actuator device are only electrically and/or electromagnetically operatively connected.
3 . The steering device according to claim 1 , wherein said braking device has a braking torque when said magnetorheological medium is actively influenced and a basic torque when said magnetorheological medium is influenced in an inactive manner, and said basic torque increases by at least a factor 50 less than a maximum braking torque.
4 . The steering device according to claim 1 , wherein said braking device has an inactive influence on said magnetorheological medium of a basic torque of at most 0.5 Nm.
5 . The steering device according to claim 1 , wherein a maximum braking torque of at least 25 Nm is generated with said braking device by actively influencing said magnetorheological medium.
6 . The steering device according to claim 1 , wherein a braking torque generated with said second braking gap section is at least twice as high as with said first braking gap section.
7 . The steering device according to claim 1 , wherein only part of a maximum braking torque is configured to be generated with said first braking gap section.
8 . The steering device according to claim 1 , wherein a majority of a maximum braking torque is configured to be generated with said second braking gap section.
9 . The steering device according to claim 1 , wherein a braking torque can be set with said first braking gap section with a higher resolution than with said second braking gap section.
10 . The steering device according to claim 1 , wherein a braking torque with a resolution of at least 0.5 Nm is configured to be generated with said first braking gap section.
11 . The steering device according to claim 1 , wherein said first braking gap section is assigned a first electrical coil and said second braking gap section is assigned a separately controllable second electrical coil.
12 . The steering device according to claim 1 , further comprising at least one steering control unit configured for controlling said braking device based on at least one of a position of said steering unit, a movement parameter of said steering unit, and an operating state of the vehicle, and wherein said at least two braking gap sections can be controlled separately by said steering control unit.
13 . The steering device according to claim 12 , wherein said steering control unit is configured to select at least one braking gap section of said at least two braking gap sections as a function of said level of a braking torque to be set and brake said movement of said steering unit.
14 . The steering device according to claim 12 , wherein said steering control unit is configured to generate a braking torque for braking said movement of said steering unit at least predominantly with said first braking gap section when the vehicle speed is above a limit value.
15 . The steering device according to claim 12 , wherein said steering control unit is configured to block mobility of said steering unit and to generate a necessary braking torque predominantly with said second braking gap section.
16 . The steering device according to claim 12 , wherein said steering control unit is configured to generate an end stop for said mobility of said steering unit at least predominantly with said second braking gap section.
17 . The steering device according to claim 12 , wherein said steering control unit is configured to brake or block mobility of said steering unit as a function of a driver assistance system, wherein critical steering movements are prevented, and said steering control unit selects at least one braking gap section of said at least two braking gap sections and to brake or block mobility of said steering unit.
18 . The steering device according to claim 12 , wherein said steering control unit is configured to set said braking torque based at least in part on a user property.
19 . The steering device according to claim 12 , wherein said steering control unit is configured to generate a haptically perceptible feedback on said steering unit with a defined sequence of braking torques.
20 . The steering device according to claim 1 , wherein said magnetorheological medium has at least one metallic powder and said metallic powder has a volume fraction of at least 50%.
21 . The steering device according to claim 20 , wherein said metallic powder has a coating.
22 . The steering device according to claim 1 , further comprising at least one retentivity device and/or at least one permanent magnet unit which is configured to maintain a braking torque with at least one of said at least two braking gap sections even without a supply of electric current.
23 . The steering device according to claim 1 , further comprising at least one safety device configured to at least partially remove said magnetorheological medium from said gap.
24 . The steering device according to claim 1 , wherein said gap has a maximum diameter of less than 100 mm.
25 . The steering device according to claim 1 , further comprising at least one drive device configured to generate a drive torque for actively moving said steering unit.
26 . The steering device according to claim 25 , wherein said maximum braking torque of said second braking gap section is at least twice said maximum drive torque of said drive device.
27 . The steering device according to claim 25 , wherein said braking device, in an event of a failure of said drive device, is configured to provide a braking torque which is at least as high as its drive torque.
28 . The steering device according to claim 25 , wherein said steering control unit is configured to approximately compensate for fluctuations in said drive torque of said drive device by adjusting said braking torque.
29 . The steering device according to claim 1 , wherein said disk contour has at least one star contour, in an area of said star contour there is a variable gap height over a circumference of said braking gap section, and magnetic field concentrators are arranged on said star contour and protrude radially into said braking gap section.
30 . The steering device according to claim 1 , further comprising a third braking gap sections axially between said first braking gap section and said second braking gap section, and said first braking gap section having at least one first electric coil and said second braking gap section having at least one separately controllable second electric coil.
31 . The steering device according to claim 30 , wherein said first electrical coil and said second electrical coil are each received between said casing part and said core and are each wound around the axis of rotation.
32 . The steering device according to claim 30 , wherein said first electric coil and said second electric coil are configured differently based on at least on parameter selected from the group of parameters consisting of wire diameter and wire cross-section, number of windings, winding window, type of winding, coil width, coil diameter, and material.
33 . The steering device according to claim 30 , wherein said third braking gap section is formed by at least one annular contour arranged between said casing part and said core.
34 . The steering device according to claim 33 , wherein said first electrical coil is arranged axially between said first braking gap section and said annular contour and said second electrical coil is arranged axially between said annular contour and said second braking gap section.
35 . The steering device according to claim 33 , wherein said ring contour is configured as a separate part and magnetic fields of said first electric coil and said second electric coil run through said ring contour.
36 . The steering device according to claim 1 , further comprising a sensor configured for detecting a relative angle of rotation between said core and said casing part and/or for detecting a relative axial position of said casing part to said brake component.
37 . The steering device according to claim 1 , wherein said magnetorheological medium has a multiplicity of individual magnetically polarizable particles, and a magnetic field strength between individual magnetically polarizable particles of said magnetorheological medium is greater than 300 kA/m.
38 . The steering device according to claim 1 , wherein a magnetic field strength which can be generated in said gap is greater than 500 kA/m.
39 . A method for operating a steering device, the method comprising:
providing a steering device with a magnetorheological braking device and two braking components, the two braking components being continuously rotatable about an axis of rotation relative to one another, wherein a first braking component extends along the axis of rotation and comprises a core made of a magnetically conductive material and wherein the second brake component comprises a hollow casing part extending around the first brake component, wherein at least three circumferential braking gap sections which are at least partially filled with a magnetorheological medium are formed between the first and the second brake component;
generating with a first electrical coil a controlled magnetic field in a first and a third braking gap section; and
generating with a second electric coil an individually controlled magnetic field in a second and the third braking gap section to generate braking effects of different strength depending on a speed.
40 . The method according to claim 39 , wherein different fast braking effects are generated with the first electric coil and the second electric coil.
41 . The method according to claim 39 , wherein braking effects of different energy efficiency are generated with the first electric coil and the second electric coil.