ROTARY DAMPER

Abstract

A rotary damper has a housing, a damper shaft rotatably held on the housing, a damper volume accommodated in the housing and which has a magnetorheological fluid as working fluid, and at least one magnetic field source in order to influence a degree of damping of the rotational movement of the damper shaft relative to the housing. A separating unit connected to the damper shaft divides the damper volume. At least one gap portion, which can be influenced by a magnetic field of the magnetic field source, is formed between the separating unit, which is connected to the damper shaft, and the housing. The housing, the separating unit and the magnetic field source are designed such that a flow cross section for the magnetorheological fluid from one side to the other side of the separating unit changes in dependence on a rotational angle.

Claims

1-27. (canceled)

28. A rotary damper, comprising: a housing, a damper shaft rotatably mounted relative to said housing, magnetorheological fluid accommodated in a damper volume in said housing, and a magnetic field source for influencing a damping of a rotational movement of said damper shaft relative to said housing at least one separating unit connected to said damper shaft and dividing said damper volume, said at least one separating unit and said housing forming at least one gap section therebetween to be exposed to a magnetic field of said at least one magnetic field source; said housing, said separating unit, and said magnetic field source being formed such that a flow cross section for the magnetorheological fluid from one side of said separating unit to an opposite side of said separating unit changes in dependence on an angle of rotation.

29. The rotary damper according to claim 28, wherein said housing is formed with a wall surrounding said damper volume and said wall is formed with a bypass that extends over a limited angle range and/or acts over a limited angle range.

30. The rotary damper according to claim 29, wherein a cross section of said bypass is angle-dependent.

31. The rotary damper according to claim 28, wherein at least one recess is formed in said separating unit.

32. The rotary damper according to claim 31, wherein a cross section of said recess changes in an angle-dependent manner due to a projection.

33. The rotary damper according to claim 31, wherein said recess adjoins a gap section.

34. The rotary damper according to claim 28, wherein the flow cross section is larger in a basic position than in a rotational position that differs substantially from said basic position.

35. The rotary damper according to claim 31, wherein said recess is a passage gap in a separating wall of said separating unit.

36. The rotary damper according to claim 35, wherein a cross section of said passage gap extends farther in an axial direction than in a radial direction.

37. The rotary damper according to claim 35, wherein two or more passage gaps are formed on the separating wall and said passage gaps are separated from one another by a magnetically conductive web.

38. The rotary damper according to claim 35, wherein at least one passage gap is formed on an insert which is accommodated on the separating unit.

39. The rotary damper according to claim 28, wherein said separating wall, axially adjacent to a passage gap, is composed of a material which exhibits poorer magnetic conductivity than a radially adjacent section of said separating wall.

40. The rotary damper according to claim 28, wherein said separating wall, close to or at an axial edge, is composed of a magnetically conductive material or comprises a permanent magnet.

41. The rotary damper according to claim 28, further comprising a one-way valve disposed in a channel section or bypass.

42. The rotary damper according to claim 28, which comprises a displacement device with at least two separating units dividing the damper volume into at least two variable chambers; and wherein at least one of said separating units comprises a separating wall connected to said housing; and at least one of said separating units comprises said separating wall connected to said damper shaft.

43. The rotary damper according to claim 28, wherein: said at least one gap section is one of a plurality of gap sections; one of said gap sections is formed in a radial direction between said damper shaft and a separating unit that is connected to said housing; another one of said gap sections is formed in a radial direction between said separating unit that is connected to said damper shaft and said housing; and at least one further gap section is formed in an axial direction between said separating unit that is connected to said damper shaft and said housing.

44. The rotary damper according to claim 44, wherein said magnetic field source comprises at least one controllable electrical coil configured to influence a strength of the magnetic field and an intensity of a damping action, and wherein at least a major part of the magnetic field of said magnetic field source passes through at least two of said gap sections and influences said at least two gap sections simultaneously in dependence on the strength of the magnetic field.

45. The rotary damper according to claim 44, wherein said separating unit that is connected to said damper shaft has two axial ends and, at each of said axial ends an axial gap section formed between said housing and a separating wall of said separating unit, and wherein a major part of the magnetic field of the magnetic field source passes through both axial gap sections between said housing and said separating wall and effects a seal of said axial gap sections.

46. The rotary damper according to claim 28, wherein said housing comprises a first end part, a second end part, and a middle part between said first and second end parts, wherein said magnetic field source includes an electrical coil accommodated in at least one of said first and second end parts, and wherein an axis of said electrical coil is oriented substantially parallel to said damper shaft.

47. The rotary damper according to claim 28, further comprising a ring arranged axially adjacent to an electrical coil in said housing, and wherein said ring is arranged axially between said electrical coil and said damper volume.

Description

[0123] Further advantages and features of the present invention will emerge from the description of the exemplary embodiments, which will be discussed below with reference to the appended figures, in which:

[0124] FIG. 1a shows a stabilizer with a rotary damper according to the invention;

[0125] FIG. 1b shows an automobile door with a rotary damper according to the invention;

[0126] FIG. 2 shows a fitness appliance with a rotary damper according to the invention;

[0127] FIG. 3 shows a partial section through a rotary damper according to the invention;

[0128] FIG. 4 shows a schematic section through a rotary damper according to the invention;

[0129] FIG. 5 shows a section through another rotary damper according to the invention;

[0130] FIG. 6 shows yet another exemplary embodiment of the rotary damper according to the invention in partial section;

[0131] FIG. 7 shows a section through the rotary damper as per FIG. 6;

[0132] FIG. 8 shows a section through another rotary damper;

[0133] FIG. 9 shows the section B-B from FIG. 8;

[0134] FIG. 10 shows an enlarged detail from FIG. 9;

[0135] FIG. 11 shows a cross section through a rotary damper according to the invention, with a magnetic field profile plotted;

[0136] FIG. 12 shows another cross section through the rotary damper as per FIG. 11, with a magnetic field profile plotted;

[0137] FIG. 13 shows a schematic cross section through a rotary damper according to the invention;

[0138] FIG. 14 shows a damper shaft for a rotary damper in various views;

[0139] FIG. 15 shows a section through yet another rotary damper;

[0140] FIG. 16 shows a schematic cross section through a further rotary damper according to the invention;

[0141] FIG. 17 shows a rotary damper according to the invention with a torsion bar;

[0142] FIG. 18 shows a partial section through a further rotary damper according to the invention;

[0143] FIG. 19 shows a cross section through the rotary damper as per FIG. 18;

[0144] FIG. 20 shows a longitudinal section through the rotary damper as per FIG. 18; and

[0145] FIG. 21 shows an alternative embodiment of the rotary damper as per FIG. 18.

[0146] FIG. 1 shows an exemplary embodiment of an apparatus according to the invention as a chassis component, which is in this case in the form of a stabilizer 100 for a motor vehicle. Various embodiments are basically possible here.

[0147] In a simple embodiment, only one rotary damper 1 is provided, specifically in this case the rotary damper 1. The components denoted by 1a and 1c then serve only for the mounting of the two stabilizer rods 102 and 103 on the body of a vehicle, such as for example a passenger motor vehicle or a heavy goods vehicle or some other vehicle, and possibly have no further function. The use is also possible on special purpose vehicles or tanks or the like.

[0148] In a particularly simple embodiment, the first stabilizer rod 102 is connected by means of its distal end 111 directly or indirectly, and at least indirectly, to a first wheel of the vehicle. Correspondingly, the second stabilizer rod 103 is connected by way of its distal end 112 to a second wheel of the vehicle.

[0149] The two stabilizer rods 102 and 103 are connected to the rotary damper 1, wherein one of the two stabilizer rods 102, 103 is coupled rotationally conjointly to the damper shaft 3 (cf. FIG. 3), and wherein the other of the two stabilizer rods 103, 102 is connected to the housing 12 (cf. FIG. 3).

[0150] The rotary damper 1 is connected not rotationally conjointly to the body. The rotary damper 1 serves for damping a rotational movement of the two stabilizer rods 102, 103 with respect to one another. Such a relative movement occurs during straight-ahead travel of a motor vehicle, for example if only one wheel travels over an obstruction or through a pothole and is accordingly raised or lowered. If the two stabilizer rods 102, 103 are coupled in a rotationally conjoint manner, this leads to a corresponding pivoting movement of the respective other stabilizer rod. During straight-ahead travel, this can lead to unsettled driving behavior, for which reason a decoupling or at least reduced coupling of the two wheels of a wheel axle may be advantageous in such cases. By contrast, during cornering, it is rather the case that coupling is desired.

[0151] The controllable rotary damper 1 as chassis component 100 is advantageous here because, by means thereof, an intensity of coupling of the two stabilizer rods 102, 103 can be controlled (in a sensitive manner). Depending on the intensity of a magnetic field of a magnetic field source 8 of the rotary damper, the magnetorheological fluid in the displacement device 2 of the rotary damper 1 can be influenced in order to set the coupling intensity of the two stabilizer rods 102, 103.

[0152] Here, an (approximately) complete decoupling can be set, in the case of which only a very low base moment acts. It is also possible for an (approximately) rigid connection to be set, in the case of which only the possibly low torsion action of the stabilizer rods 102, 103 acts.

[0153] It is thus possible with the chassis component 100 for the left wheel side to be decoupled from the right wheel side. Multifunctional spring rate switching and/or ride height adjustment can be achieved. A ride height adjustment is also possible by means of the sawtooth principle and the freewheel principle with utilization of the body movement.

[0154] In a first embodiment, torques of up to and greater than 1000 Nm are attained, wherein the maximum pivot angle is greater than 25° and may reach 30° or more.

[0155] One advantage is that a simple construction is realized. The rotary damper practically forms a direct MRF coupling, that is to say two components of the actuator which pivot relative to one another generate the torque, without the use of a transmission. The system is simple, robust and free from play. Here, only a relatively low weight of approximately 2500 to approximately 4000 g is required. The length of the rotary damper is approximately 150 mm in the case of a diameter of (approximately) 85 mm. The operating voltage can be selectable.

[0156] It is highly advantageous that switching times=<10 ms for the switching from a minimum to a maximum are achievable. In this way, it is possible to react to potholes, for example, during travel. The working range may be variable and, in one example, amounts to between approximately 50 Nm and 1000 Nm, and may also be greater or smaller.

[0157] Not only is a maximum coupling or a release possible, but also, any desired number of (intermediate) switching positions is selectable by means of a variation of the electrical current.

[0158] As shown in particular by FIGS. 3, 4 and 5, the base moment of a stabilizer 100 and also of other rotary dampers 1 can be lowered, because, at least in a basic position 80 or else in other predetermined angle positions or angle ranges, an (effective) flow cross section is enlarged. This can be ensured for example by means of a bypass which acts only in the basic position or in a defined angle range about the basic position. Here, the cross section of the bypass can be kept substantially free from a magnetic field in order to attain an intense action of the bypass. Such a refinement is advantageous for example if a motor vehicle travels over cobblestones and small shocks are continuously exerted on each wheel, in the case of which it is advantageous for each shock to be individually dampened. For this purpose, a low base moment is advantageous because, in this way, an intense decoupling of the wheels in the case of small shocks is attained.

[0159] In another embodiment, three rotary dampers 1 may be used on the chassis component 100, specifically at the locations 1, 1a and 1c. Here, the rotary damper 1 operates as described above, and selectively couples the two stabilizer rods 102, 103 to one another in a more or less rotationally conjoint manner.

[0160] If only the rotary damper 1b is active, a classic stabilizer function is realized, wherein, however, an opening (deactivation) of the rotary damper 1b decouples the left-hand wheel side with respect to the right-hand wheel side.

[0161] FIG. 1b shows a further exemplary embodiment of the invention, and in this case a door 101 of a vehicle and in particular motor vehicle, wherein the door 101 is equipped, at the pivot joint, with a rotary damper 1 according to the invention, which can dampen the movement of the door 101 between the open and the closed position. Depending on the refinement, it is possible for the rotary damper 1 to be attached directly on the pivot axis. It is however also possible for the rotary damper 1 to be connected by means of a kinematic mechanism to the parts which pivot relative to one another.

[0162] FIG. 2 shows a training appliance 300 in the form of a leg extension apparatus. During the training process, the person performing the training is situated on a seat 305 and raises an at the lever 309 by extending the legs or the knees. The leg lever 309 serves here as actuating element 301, and is attached pivotably to the seat 305. The pivoting movement can be dampened here by means of a damper device 1. Here, by way of example, the rotary damper 1 already illustrated in FIGS. 1a, 1b and 2, which will be discussed in even more detail with reference to the further figures, serves as damper device 1.

[0163] FIG. 3 shows a partial section of the rotary damper, which is used in principle in the example from FIGS. 1a, 1b and in the example according to FIG. 2. The rotary damper 1 has a housing 12 and a damper shaft 3, which are formed so as to be pivotable relative to one another. The damper shaft 3 is mounted rotatably in the housing 12 by means of plain bearings 44. The housing 12 is composed here of three sections or housing parts, specifically a first end part 22 and a second end part 24 at the other end and a middle part 23 arranged in between. Here, each part or each region constitutes a separate component, which components are connected to one another during the assembly process. It is however also possible for the three housing sections or regions to be part of a single component, or to form two components.

[0164] In the two end parts 22 and 24, there is accommodated in each case one encircling electrical coil 9, which serves for the generation of the magnetic field required for the damping. The interior space of the rotary damper 1 provides a damper volume 60. In the housing, there is formed a displacement device 2 which comprises separating units 4 and 5. The separating units 4 and 5 divide the damper volume 60 into two or more chambers 61 and 62. Here, the separating unit 4 is formed as a separating wall and is fixedly connected to the housing 12. The separating unit 5 is likewise formed as a separating wall or as a pivot vane and is fixedly connected to the damper shaft 3. Preferably, the separating unit 5 is formed in one piece with the damper shaft 3. The damper volume 60 is in this case filled with magnetorheological fluid 6. A seal of the damper volume 60 to the outside is realized by means of a seal 28 in the housing part 22. During a pivoting movement, the separating units 4 and 5, which are rotatable relative to one another, displace the magnetorheological fluid (MRF) contained in the damper volume, such that the MRF partially flows over from one chamber into the other.

[0165] The magnetic field source 8 in the housing part 22 is composed here of electrical coils 9 and may furthermore comprise at least one permanent magnet 39, which are in particular in each case of ring-shaped form and accommodated in the housing part 22. Here, in the exemplary embodiment, electrical coils 9 and possibly also permanent magnets 39 are provided in both end parts. The permanent magnet 39 predefines a particular magnetic field strength which, by means of the electrical coil 9, can be modulated and thus eliminated or intensified.

[0166] Here, two separating units 4 project radially inward into the damper volume 60 from the housing. The separating units 4 form separating walls and thus limit the possible rotational movement of the damper shaft 3, on which likewise two separating units 5 are formed, which project radially outward from the damper shaft. Rotation of the damper shaft 3 causes the separating walls of the separating units 5, which in this case form pivot vanes, to be pivoted.

[0167] The electrical coils 9 are in this case, in the exemplary embodiment, arranged radially relatively far to the outside and, in this case, are delimited axially to the inside in each case by a ring 20 which exhibits no or poor magnetic conductivity and which serves for shaping the magnetic field profile. The ring 20 has a hollow cylindrical form.

[0168] Here, in the separating units 5, it is possible to see connecting channels 63, which will be described in more detail in the explanation of FIGS. 5 and 14.

[0169] Here, in the separating unit 5, there is shown a recess 21b, which practically provides a bypass for the magnetorheological fluid 6. The magnetorheological fluid 6 can, in the presence of low magnetic field strengths, pass over practically without disruption through the wall of the separating unit 5 from a chamber 61 into the chamber 62. The base moment is considerably reduced by means of the recess 21b. If a magnetic field is generated by means of the electrical coils 8, initially only the axial and radial gap sections 25, 27 are charged, because the magnetic resistance in the considerably taller gap at the recess 21b is considerably greater. With increasing magnetic field, saturation occurs in the wall of the separating unit 5, and with yet further increasing magnetic field, the cross section of the recess 21b is finally also charged with an increasingly stronger magnetic field. As a result, the proportion of the cross section of the recess 21b that provides a type of bypass decreases.

[0170] Overall, it is thus possible for a relatively low base moment to be provided at any desired angle positions, whereas a high braking moment can also be generated in the same or other angle ranges.

[0171] Alternatively and/or in addition, passage gaps 21c can be formed on the wall of the separating unit 5, which passage gaps connect the two sides to one another. Here, it is preferably possible for multiple parallel passage gaps 21c to be formed, which are separated from one another by thin magnetically conductive webs 21f. In the case of such a refinement, too, a very low base moment is provided in the absence of a magnetic field. A high braking moment can be generated. Through different actuation of the two electrical coils 8, it is possible for (effective) flow cross sections of different size to be provided.

[0172] It is possible for at least one passage gap 21c and at least one recess 21b to be combined, or else for only in each case one type to be used.

[0173] FIG. 4 shows a cross section through a rotary damper 1 of simple construction. Here, the displacement device comprises only one (single) separating unit 4, which extends radially inward from the housing into the damper volume 60. The damper shaft 3 is accommodated rotatably in the interior of the housing, on which damper shaft in this case also only one separating unit 5 extends radially outward. By means of the separating units 4 and 5, which serve as separating walls, of the displacement device 2, the damper volume 60 is divided in variable fashion into two chambers 61 and 62. In the event of a clockwise rotation of the damper shaft, the volume of the chamber 61 is reduced in size and the volume of the chamber 62 is increased in size, whereas, in the event of an opposite rotational movement, the volume of the chamber 61 is correspondingly increased in size.

[0174] On the separating unit 5, radially at the outside, there are formed multiple fan-like passage gaps 21b which are separated from one another by thin webs 21f.

[0175] It is also possible for a bypass 21a with a one-way valve 51 to additionally be provided in order to configure the flow resistance to differ in the different flow directions.

[0176] In the outer wall, local bypasses 21a can be formed at particular angle positions 38, which bypasses considerably reduce the base moment for example in a basic position 80, because the flow cross section that is available in the absence of a magnetic field is considerably enlarged, and is enlarged for example by 50% or 100% or by a factor of 2, 3 or 4 or more.

[0177] A lug or a projection 12d or the like may project radially inward, which lug or projection limits the available cross section in particular angle positions. This is a possibility for example if one recess 21b is provided and it is the intention for the base moment not to be reduced at a particular angle or in a particular angle range.

[0178] Below FIG. 4, an enlarged detail in an axial cross section is shown, showing the region of the passage gaps 21c. The passage gaps 21c may be part of an insert 50, which is attached as a whole to the separating unit 5. It is possible for multiple webs 21f and holders or spacers 49 to be provided, which collectively form the insert 50 and can be preassembled. Permanent magnets 56 may be arranged laterally, which permanent magnets generate a stray field in order to seal off lateral axial gap sections 25. It is also possible for thin magnetically conductive or magnetically poorly conductive regions, which quickly saturate, to be provided there. Such an insert may for example also be used in FIG. 3.

[0179] Multiple passage gaps separated from one another by webs form a “fan”. The cross-sectional area is increased overall. This reduces the base friction. The passage gaps may however also be closed entirely, because a homogeneous magnetic field is possible. A slight disadvantage is the higher electrical current requirement, which however is not of importance in many apparatuses, also because it is nevertheless the case that altogether only very little energy is required for operation.

[0180] It would also be possible for multiple metal sheets to be stacked one on top of the other and laterally connected and for example welded or adhesively bonded. It is possible for passage gaps or recesses to be produced for example by erosion etc.

[0181] FIG. 5 shows a cross section through another exemplary embodiment, wherein, in this case, in each case two separating units are fastened to the housing and to the damper shaft 3. The in each case symmetrically arranged separating units 4 and 5 thus allow a pivoting movement of the damper shaft 3 through almost 180°. Two chambers 61 and 61a and 62 and 62a are formed between the individual separating units 4 and 5. If the damper shaft 3 is rotated clockwise, the chambers 61 and 61a form the high-pressure chambers, whereas the chambers 62 and 62a are then low-pressure chambers.

[0182] In order to realize a pressure equalization between the two high-pressure chambers 61 and 61a, corresponding connecting channels 63 are provided between the chambers 61 and 61a and 62 and 62a.

[0183] Between the radially outer end of the separating units 5 and the inner circumference of the damper volume 60, which, in principle, is of cylindrical shape, there is formed a radial gap 27, which serves here as damping channel 17. Furthermore, radial gaps 26 are formed between the radially inner end of the separating units 4 and the damper shaft 3. Here, the gaps 26 are dimensioned such that proper rotatability of the damper shaft 3 is made possible and such that jamming of the magnetorheological particles in the magnetorheological fluid within the damper volume 60 at the gaps 26 is reliably avoided. For this purpose, the gap 26 must have at least a gap height greater than the largest diameter of the particles in the magnetorheological fluid.

[0184] A gap 26 of such a size, of the order of approximately 10 μm to 30 μm, would normally have the effect that a considerable leakage flow flows through the gap 26. This would be effective in preventing a high pressure build-up in the chambers 61 and 62. This is prevented according to the invention in that the gap 26 is likewise subjected to a magnetic field, such that a magnetorheological seal of the gap 26 is also realized, at least when it is the intention for a braking moment to be applied. In this way, a reliable seal is realized, such that a pressure loss can be substantially avoided.

[0185] In FIG. 6, too, recesses 21b are shown which cause a reduction of the base moment. A recess 21b can interact, in particular angle ranges, with a projection 12d.

[0186] FIG. 6 shows another exemplary embodiment of a rotary damper 1 according to the invention. The rotary damper 1 has a damper shaft 3, which is mounted rotatably in a housing 12. The damper shaft 3 and the housing are connected to connectors 11 and 13, which are pivotable relative to one another.

[0187] The damper volume 60 is again divided by means of separating units 4 and 5 into chambers 61 and 62, as is the case in the exemplary embodiment as per FIG. 5.

[0188] Here, too, the housing 12 is composed of 3 housing sections or housing parts, wherein in each case one electrical coil 9 for generating the required magnetic field is accommodated in the axially outer housing parts.

[0189] Via an electrical connector 16, the rotary damper 1 is supplied with electrical energy. A sensor device 40 serves for detecting the angular position. It is furthermore possible for a measure for a temperature of the magnetorheological fluid to be detected by means of the sensor device. The signals are transmitted via the sensor line 48.

[0190] The separating unit 4 is accommodated in a positionally fixed manner in the housing 12 and is preferably inserted into the housing, and fixedly connected thereto, during the assembly process. In order to prevent a magnetic short-circuit in the regions of the separating unit 4, an insulator 14 is preferably provided between the separating unit 4 and the housing parts 22 and 24 respectively.

[0191] FIG. 6 shows the compensating device 30, which comprises an air chamber 32 which is closed off to the outside by means of a cover 35. Toward the inside, the air chamber 32 is adjoined by the separating piston 34, which separates the air chamber 32 from the compensating volume 29. The compensating volume 29 is filled with magnetorheological fluid and provides compensation in the case of temperature fluctuations. Furthermore, the compensating volume 29 serves as a reservoir for leakage losses that arise during ongoing operation.

[0192] In the exemplary embodiment as per FIG. 6, in that part of the housing which is not illustrated in section, there is provided a local bypass 21a which reduces the base moment in a basic position 80.

[0193] FIG. 7 shows a cross section through the rotary damper as per FIG. 6, wherein it can be seen here that in each case 2 mutually opposite separating units 4 and 5 are arranged in the housing, and fastened to the damper shaft 3, respectively. Chambers 61 and 61a, and 62 and 62a, are formed in the damper volume 60 between the individual separating units 4 and 5. By virtue of in each case two separating units 4 and 5 being used, the acting torque can be doubled. The compensating volume 29 is connected via a channel 36.

[0194] The channel 36 is led at the edge of the separating unit 4 into the damper volume 60, in order that a connection to the compensating volume 29 is available even in the case of a maximum pivoting movement between the damper shaft 3 and the housing 12. In this refinement, the compensating volume must be preloaded under the maximum operating pressure by virtue of the air chamber 32 being subjected to a corresponding pressure. The preload may also be imparted by means of a mechanical element such as a spiral spring.

[0195] The bypass 21a can be seen in FIG. 7. Furthermore, on the second separating unit 5, a recess 21b can be seen, which may both be provided together.

[0196] FIG. 8 shows a cross section through a further exemplary embodiment of a rotary damper 1 according to the invention, which in turn has in each case two separating units 4 and 5, which are in each case connected to the housing and to the damper shaft 3 respectively. Recesses 21b are formed on the separating units 5. In this case, too, two electrical coils are provided, though these are not visible in the illustration as per FIG. 8 because they are arranged on the one hand in front of and on the other hand behind the section plane.

[0197] Radially at the outside, between the inner housing wall and the radially outer end of the separating elements 5, there is formed a gap 27 which is subjected to a corresponding magnetic field for the purposes of damping. The gap height 21d in the region of the recesses 21b is considerably greater than a gap height of the gap section 27 axially outside the recesses. Radially at the inside, between the inner end of the separating elements 4 and the damper shaft 3, there is formed in each case one gap 26 which is sealed off by means of a magnetic field.

[0198] By contrast to the preceding exemplary embodiment, the compensating volume is in this case connected centrally. The compensating volume 29 is connected via the channel 36 to the interior of a separating unit 4.

[0199] FIG. 9 shows the cross section B-B from FIG. 8, and FIG. 10 shows an enlarged detail from FIG. 10. The channel 36 is shown schematically in FIG. 10 and is connected to a channel in which there is arranged a valve unit 31, which in this case is formed as a double valve unit. The valve unit 31 comprises two valve heads 31a at the opposite ends of the channel. Seals 33 serve for sealing when the respective valve head 31 is arranged in its valve seat. The channel 36 opens out in an intermediate region.

[0200] On the side on which the higher pressure prevails, the valve head 31 of the valve unit 31 is pushed into the corresponding valve seat. On the other side, the valve head 31a thus lifts off from the valve seat and allows a free flow connection to the channel 36 and thus to the compensating volume 29. In this way, temperature fluctuations can be compensated. Furthermore, in the event of the occurrence of leakage losses, magnetorheological fluid is transferred from the compensating volume into the damper volume.

[0201] An advantage of this construction is that the compensating volume only needs to be preloaded under a relatively low preload pressure of 2, 3 or 4 or 5 bar, because the compensating volume is always connected to the low-pressure side and not to the high-pressure side of the rotary damper. Such a refinement reduces the load on the seals and increases the long-term stability. If the compensating volume is connected to the high-pressure side, a preload pressure of 100 or more bar may be expedient.

[0202] FIGS. 11 and 12 show cross sections through the rotary damper 1, wherein different cross sections are illustrated. FIG. 11 shows a cross section in which the separating units 4 connected to the housing are illustrated in section. The magnetic insulator between the housing side parts 22 and 24 and the separating wall 4 results in the plotted profile of the magnetic field line. Here, the magnetic field lines pass through the radially inner gap 26 between the inner end of the separating units 4 and the damper shaft 3, and thus reliably seal off the gap there. If the magnetic field is deactivated, the damping is also reduced, and the result is a low base friction.

[0203] In the section as per FIG. 11, it is also possible to see the plain bearings 44 for the mounting of the pivot shaft and the seals 28 for sealing off the interior space.

[0204] FIG. 12 shows a cross section through the rotary damper 1, wherein, here, the section runs through the damper shaft 3 and a separating unit 5 connected thereto. Here, it is possible to see a recess 21b at the radially outer end of the separating unit 5, which recess provides a bypass in the presence of a weak magnetic field or even in the absence of a magnetic field, and which recess is “closed” in the presence of a strong magnetic field. In addition or instead, a bypass 21a may also be formed over a predefined angle range at an axial gap 25 or in the axial wall 12c of the housing 12, such that a rotational-angle-dependent base moment is provided.

[0205] The other, oppositely situated separating unit 5 which is connected to the damper shaft 3 is not illustrated in section here. The profile of a magnetic field line is also plotted by way of example in FIG. 12. It is clear here that the axial gaps 25 between the separating unit 5 and the housing parts 22 and 24 are sealed off by means of the magnetic field. Furthermore, the radial gap 27 between a radially outer end of the separating unit 5 and the housing is also subjected to the magnetic field such that the magnetorheological particles there interlink and seal off the gap.

[0206] FIG. 13 shows once again a schematic cross section, which is not true to scale, through a damper device 1, wherein, here, a section through the damper shaft 3 and the separating unit 5 connected thereto is illustrated in the upper half, whereas a section through the separating unit 4 connected to the housing is shown in the lower half. Magnetic field lines are plotted in each case by way of example. Between the separating unit 4 and the damper shaft, there is a thin gap 26 which preferably has a gap height between approximately 10 and 50 μm. In an axial direction, the separating unit 4 lies sealingly against the lateral housing parts. There is a radial gap 27 between the separating unit 5 and the housing 12, and there is in each case one axial gap 25 at the two axial end sides.

[0207] In general, the axial gaps 25 are provided with a much smaller gap height than the radial gap 27. The gap width of the axial gaps 25 is preferably similar to the gap width of the radial gaps 26, and is preferably between approximately 10 and 30 μm. The radial gap width 27 is preferably considerably greater, and lies preferably between approximately 200 μm and 2 mm and particularly preferably between approximately 500 μm and 1 mm.

[0208] The recess 21b has a width 21e and a radial gap height 21d. The width 21e is preferably less than half and in particular less than ⅓ of an axial width of the separating unit 5, and preferably more than 1/20 and in particular more than 1/10 of an axial width of the separating unit 5.

[0209] During the pivoting of the damper shaft 3, the volume of a chamber is reduced in size, and that of the other chamber is increased in size. Here, the magnetorheological fluid must pass over from one into the other chamber substantially through the gap 27. The gap 27 serves here as damping channel 17. As can be clearly seen in FIG. 13, the damping channel 17 is passed through by the magnetic field lines, such that a variable flow resistance can be generated there.

[0210] The axial gaps 25 are also sealed off by means of the magnetic field, at any rate if the magnetic field thereof is selected to be of such a strength that it is conducted no longer only through the damper shaft 3. Specifically, it has been found that, with a magnetic field of increasing strength, the entire magnetic field is conducted no longer through the damper shaft 3 but also passes axially through the axial gap 25 and thus, with increasing strength, seals off the entire axial gap 25. Corresponding sealing is realized with a corresponding field strength.

[0211] As already described above, the in this case magnetically non-conductive rings 20 serve in this case for preventing a magnetic short-circuit at the electrical coil 9.

[0212] FIG. 14 shows various views of the damper shafts 3 equipped with two separating units, wherein the separating units 5 and 5a are situated diagonally oppositely, resulting in a symmetrical construction.

[0213] At the top right in FIG. 1, a schematic cross section through an embodiment in which a bypass 21a is formed for example in the manner of a groove into the inner wall of the housing 12 is shown. The groove has a groove depth which varies over the circumference. Toward the lateral region, the radial depth of the groove or of the bypass 21a may decrease to zero. Then, an intense decrease of the base moment is attained in the middle region. With progressive pivoting, the base moment increases.

[0214] At the bottom left in FIG. 14, in the left-hand half, an insert 50 has been inserted at a recess, which insert provides two or more passage gaps 21c. At the right-hand half, in the separating unit 5 shown there, a recess 21b is shown which, in the illustrated angle position, is filled or closed off to a considerable extent by a projection 12d in order to influence the (effective) flow cross section for the base moment in targeted fashion.

[0215] At the bottom right in FIG. 14, an enlarged detail with a cross section of a separating unit 5 and with a channel or bypass 21a on the inner wall 12b of the housing 12 is schematically shown. It can be seen that there is a considerably greater gap height in the angle range 38 of the channel or bypass 21a than in the axially adjacent regions with the radial gap 27. Here, relative constrictions at the circumferential ends of the channel or bypass 21a can also be seen. It is also possible for the channel or bypass 21a to extend over a somewhat greater angle range, such that a relatively large gap height is realized over the full width of the separating unit. The configuration shown is however advantageous because, in the region of the constrictions, the magnetic field can more easily seal off the gap in a reliable manner.

[0216] In FIG. 14, it is possible to see the two connecting channels 63 which connect in each case 2 oppositely situated chambers 61 and 61a, and 62 and 62a, to one another. In order to allow a pressure equalization between the two high-pressure chambers and the two low-pressure chambers, whereas an exchange of pressure or an exchange of fluid from a high-pressure chamber and a low-pressure chamber is possible only via the damping channel 17.

[0217] FIG. 15 shows a cross section through a further rotary damper 1. This rotary damper is of particularly small construction. The rotary damper 1 from FIG. 15 can be used in all exemplary embodiments and is basically identical in terms of construction. In the section, it is possible to see the separating units 4 connected to the housing. The magnetic insulator 14 between the housing side parts 22 and 24 and the separating wall 4 results in a profile of the magnetic field lines similar to FIG. 11. If the magnetic field is deactivated, it is also the case here that the damping is reduced and a low base friction results. The ring 20 is in this case of magnetically conductive form in order to ensure a reliable seal of the lateral axial gaps 26 in the region of the separating element 5. The seal is reliably attained if a sufficient magnetic field strength is present. Here, too, as in FIG. 11, the plain bearings 44 for the mounting of the pivot shaft and the seals 28 for sealing off the interior space can be seen.

[0218] The electrical coils 9 are arranged radially in the region of the damper volume. In the region of the pivot vanes, a reliable seal even of the lateral axial gaps 26 is attained by means of the frustum form, provided with a hollow cylinder, of the rings 20. The rings 20, which are composed here of magnetically conductive material, ensure a reliable seal of the axial sealing gaps 26 in the region of the pivot vanes or separating elements 5.

[0219] FIG. 16 shows a variant similar to FIG. 7, wherein, here, it is again the case that in each case two separating units are fastened to the housing and to the damper shaft 3. As is also the case in FIG. 15, a recess 21b is shown on one separating unit 5 in FIG. 16. The in each case symmetrically arranged separating units 4 and 5 thus allow a pivoting movement of the damper shaft 3 through almost 180°. Between the individual separating units 4 and 5, there are formed in each case two high-pressure chambers and two low-pressure chambers. Here, the separating units 4 and 5 are of rounded and streamlined form in order that no flow separation occurs, and thus undesired deposits from the magnetorheological fluid are avoided. A compensating device 30 with a compensating volume 29 is also provided. Finally, FIG. 17 shows a yet further exemplary embodiment, wherein, here, the rotary damper 1 is additionally equipped with a spring in the form of a torsion bar. The damper shaft is coupled to one side, and the housing is coupled to the other side, such that a relative movement or relative rotation of the components with respect to one another can be dampened in controlled fashion by means of the rotary damper 1. The components may be settable and also completely decouplable. In this way, an active apparatus is provided which can be set for different conditions.

[0220] In FIG. 17, it is furthermore the case that the damper shaft 3 is of hollow design. The spring, for example in the form of a torsion bar, is arranged in the interior of the damper shaft, such that a resetting action is possible by means of the spring force of the spring 47.

[0221] FIG. 18 shows a further rotary damper 1 in a partial section, wherein the rotary damper 1 basically functions in the same way as, for example, the rotary damper as per FIG. 3. Therefore, the same reference designations are also used where possible, and the above description also applies identically to the rotary damper 1 of FIGS. 18-20, unless a contrary or supplementary description is given or corresponding information emerges from the drawings. Local bypasses 21a and/or recesses 21b and/or passage gaps 21c are provided. FIG. 21 shows a variant of the rotary damper 1 as per FIG. 18.

[0222] The rotary damper 1 from FIG. 18 likewise has a housing 12 and a damper shaft 3, which are designed to be pivotable relative to one another. The damper shaft 3 is mounted rotatably in the housing 12 by means of rolling bearings 44. The damper shaft 3 is formed here from a total of three parts, as will be discussed with reference to FIG. 20.

[0223] The housing 12 comprises a first end part 22 and a second end part 24 at the other end, and a middle part 23 arranged in between. At both ends, there are also accommodated outer housing parts 12a, on which screw openings are formed. On the radially outer housing part 12a, a non-circular coupling contour 70 with recesses is formed in the region of the end of the reference designation line. Multiple recesses arranged so as to be distributed over the circumference form the non-circular coupling contour, whereby a rotationally conjoint connection to further components is possible.

[0224] In the two end parts 22 and 24, there is accommodated in each case one encircling electrical coil 9 which serves for generating the magnetic field required for the damping.

[0225] In all exemplary embodiments, the magnetic field is controllable. As in all exemplary embodiments and refinements, more intense damping (braking action) is generated in the presence of a relatively strong magnetic field. At the same time, by means of the relatively strong magnetic field, a better seal of the gaps 25, 26 and 27 (compare the schematic illustration as per FIG. 13) is attained. Conversely, in all exemplary embodiments and refinements, relatively weak damping (braking action) is set by means of a relatively weak magnetic field. At the same time, in the presence of a relatively weak magnetic field, the sealing action at the gaps 25 to 27 is also reduced. This results in a lower base moment which acts in the absence of a magnetic field. The sealing action of the gaps 25 to 27 is low in the absence of a magnetic field. In this way, a broad setting range can be provided, which is not possible in the prior art. The ratio of maximum torque (or maximum braking action) to minimum torque (or minimum braking action) is very large, and greater than in the prior art, within the provided pivot angle or within the working range. The base moment can be reduced in certain angle ranges by mechanical means and through targeted control of the magnetic field.

[0226] By contrast, in the case of conventional rotary dampers, the minimum torque is already large if a high maximum torque is to be generated. This is because the seals of the gaps must be designed such that a reliable or adequate seal is ensured even in the presence of high acting pressures. Conversely, in the case of rotary dampers which are intended to have a low braking moment in operation without load, only a low maximum torque is attained, because the seals are designed such that only little friction is generated. In the presence of high acting pressures, this results in a considerable leakage flow, which greatly limits the maximum possible torque.

[0227] The interior space of the rotary damper 1 provides a damper volume. In the housing, there is formed a displacement device 2 which comprises separating units 4 and 5. The separating units 4 and 5 divide the damper volume 60 into two or more chambers 61 and 62. Here, the separating unit 4 is formed as a separating wall and is fixedly connected to the housing 12. The separating unit 5 is likewise formed as a separating wall or as a pivot vane and is fixedly connected to the damper shaft 3. Preferably, the separating unit 5 is formed in one piece with the damper shaft 3. Here, the damper volume 60 is filled with magnetorheological fluid 6. A seal of the damper volume 60 to the outside is realized by means of a seal 28 in the housing part 22. During a pivoting movement, the separating units 4 and 5 displace the magnetorheological fluid (MRF) contained in the damper volume, such that the MRF flows over partially from one chamber into the other. A connecting channel or compensating channel 63 serves for pressure equalization between the chambers 61 and 61a. A corresponding second connecting channel 63a (cf. FIG. 20) serves for pressure equalization between the chambers 62 and 62a.

[0228] At the rear end, it is also possible in FIG. 18 to see a valve 66, by means of which a compressible fluid is introduced into the compensating device 30. In particular, nitrogen is used. The valve 66 may for example be integrated into a screwed-in enclosure or cover.

[0229] At the front end, it is possible in FIG. 18 to see, outside the housing 12 of the rotary damper 1, a mechanical stop 64 which mechanically limits the possible pivoting range in order to protect the pivot vanes in the interior against damage.

[0230] The magnetic field source 8 in the housing part 22 is composed here of electrical coils 9, which are each of ring-shaped form and accommodated in the housing part 22. Here, in the exemplary embodiment, electrical coils 9 are provided in both end parts. The magnetic field strength can be predefined by means of a controller.

[0231] Here, two separating units 4 project radially inward into the damper volume 60 from the housing. The separating units 4 form separating walls and thus limit the possible rotational movement of the damper shaft 3, on which there are likewise formed two separating units 5 which project radially outward from the damper shaft. Rotation of the damper shaft 3 causes the separating walls 5, which in this case form pivot vanes, to be pivoted. The chambers 61 and 61a are correspondingly reduced in size (cf. FIG. 19) or increased in size again.

[0232] In FIG. 19, it is also possible to see four bleed valves which were used in a prototype in order to achieve faster filling and emptying and which possibly need not (all) be implemented.

[0233] As is also shown in FIG. 20, the electrical coils 9 are in this case, in the exemplary embodiment, arranged radially relatively far radially to the outside and are delimited in an axially inward direction in each case by a magnetically non-conductive or only poorly conductive ring 20, which serves for shaping the magnetic field profile. The ring 20 has in particular a hollow cylindrical shape.

[0234] In the complete longitudinal section as per FIG. 20, it is possible to see the compensating device 30, which in this case is accommodated in the interior of the damper shaft 3. The compensating device 30 comprises a compensating volume 29 which is filled with MRF and which is separated from the air chamber 32 by means of a movably arranged separating piston 34. Both the air chamber 32 and the separating piston 34 and the compensating volume 29 are accommodated, within a hollow cylindrical receiving space 30a, entirely in the interior of the damper shaft 3. The hollow cylinder 30a is closed off at the axially outer end by means of a closure with the valve 66. This refinement allows a particularly compact and space-saving design, in the case of which only very few parts project from the rotary damper 1, which is basically of substantially cylindrical form. This increases the installation and usage possibilities.

[0235] The compensating device 30 is, in FIGS. 18 to 20, connected via channels (not illustrated) to the channel 72, which in this case is closed by means of a closure 71. In this way, it is optionally possible for an external compensating device 30 to be coupled on and for an insert to be inserted in the interior in order to substantially fill the volume of the hollow cylinder 30a. In this way, it is for example possible for a particularly large temperature range to be compensated. It is also possible in this way to ensure a particularly long service life, even if a certain amount of leakage occurs.

[0236] In FIG. 20, it is possible to clearly see the in this case three-part damper shaft 3, which is composed here of the hollow shaft 3a, the attachment shaft 3b and the projection 3c. The three parts are coupled rotationally conjointly to one another. It is also possible for the damper shaft 3 to be of two-part or else only single-part form.

[0237] FIG. 21 shows a variant of the exemplary embodiment as per FIGS. 18 to 20, wherein, here, an external compensating device 30 has been coupled on. The further components may be identical. In practical terms, on the rotary damper 1 as per FIG. 18, the closure 71 can be removed, and the illustrated external compensating device can be screwed on. In the interior, there is formed an air or fluid chamber 32, which is separated from the compensating volume 29, which is filled with MRF, by means of a separating piston 34.

[0238] In the interior, an insert 67 is accommodated in the hollow cylinder 30a in order to fill the volume.

[0239] In the exemplary embodiment as per FIG. 21, two angle sensors 68 and 69 are also attached. Here, one angle sensor 68 measures the absolute angle position with relatively low accuracy, and the angle sensor 69 measures a relative angle position with relatively high accuracy. In this way, a highly accurate sensor system can be provided which operates robustly and reliably and nevertheless with high accuracy.

[0240] Altogether, an advantageous rotary damper 1 is provided. In order to be able to compensate the temperature-induced volume expansion of the MR fluid (MRF) and of the adjacent components, it is expedient for an adequate compensating volume to be provided.

[0241] In one specific case, approximately 50 ml MRF is required per individual actuator or rotary damper, and thus 150 ml is required for the overall system. As a preload element, use is preferably made of a nitrogen volume, which is preloaded in particular with approximately 75 bar.

[0242] In this example, a coil wire with an effective cross section of 0.315 mm.sup.2 was used. The number of windings of 400 yielded a fill factor of approximately 65% with a resistance of 16 ohms. With a larger wire diameter, an even higher coil speed can be achieved.

[0243] An axial play of the separating walls or pivot vanes is preferably set. For proper functioning of the actuator, it is advantageous for the axial position of the pivot vane 5 relative to the housing to be centered and set. For this purpose, use may for example be made of threaded setting rings which are brought into the central position by means of a dial gauge.

[0244] In one specific case, filling with MRF was performed, wherein (almost) 75 ml of MRF was introduced. For the introduction, the MRF may be introduced via the compensating volume. By moving the pivot vane in alternating fashion, the MRF can be distributed within the chambers 61, 62 (pressure chamber), and air inclusions can be conveyed upward. Subsequently, the system can be preloaded with nitrogen (approximately 5 bar). Thereafter, the bleed screws 65 on the outer side of the housing 12 can be opened in order to allow the enclosed air to escape. The nitrogen chamber 32 was subsequently preloaded to 30 bar for initial tests on the test stand.

[0245] As an optimization measure, the actuator can also be placed into a negative-pressure environment in order to be able to better evacuate possible air inclusions.

[0246] High pressures are attained without a mechanical seal. The rotary damper 1 is inexpensive to produce and is robust and durable.

[0247] In this specific example, a braking moment of >210 Nm was attained on the test stand. The unit is of smaller, more lightweight and less expensive construction than in the prior art.

[0248] Switching times of <30 ms are possible and were able to be demonstrated (full-load step change).

[0249] The braking moment can be varied as desired. No mechanical moving parts are required for this purpose. The control is performed easily merely by variation of electrical current or magnetic field.

[0250] A considerable advantage is attained owing to an absence of mechanical seals. In this way, a very low base moment of less than 0.5 Nm is attained. This is attained in that not only the braking moment but simultaneously also the sealing action of the seals is controlled. Altogether, the result is a very low power requirement of for example a few watts.

[0251] The rotary damper 1 can be used in various technical devices. One application is for example also in vehicles and in particular motor vehicles in, for example, stabilizers, steer-by-wire systems or on brake, accelerator or clutch pedals. A corresponding rotary damper 1 can be installed in these systems. Here, the dimensioning can be adapted to the desired forces and moments to be imparted.

LIST OF REFERENCE DESIGNATIONS

[0252] 1 Rotary damper [0253] 2 Displacement device [0254] 3 Damper shaft [0255] 3a Hollow shaft [0256] 3b Attachment shaft [0257] 4 Separating unit, separating wall [0258] 5 Separating unit, separating wall [0259] 6 MRF [0260] 7 Control device [0261] 8 Magnetic field source [0262] 9 Electrical coil [0263] 10 Magnetic field [0264] 11 Connector (on 12) [0265] 12 Housing of 2 [0266] 12a Outer housing part [0267] 12b Wall, inner wall [0268] 12c Axial wall [0269] 12d Projection, lug [0270] 13 Connector (on 3) [0271] 14 Insulator [0272] 15 Hydraulic line [0273] 16 Electrical connector [0274] 17 Damping channel [0275] 19 Axis of 3, 9 [0276] 20 Ring in 12 [0277] 21 Flow cross section [0278] 21a Bypass [0279] 21b Recess in 5 [0280] 21c Passage gap [0281] 21d Gap height [0282] 21e Gap width [0283] 21f Web [0284] 22 First end region [0285] 23 Central region [0286] 24 Second end region [0287] 25 Gap, axial gap [0288] 26 Gap, radial gap [0289] 27 Gap, radial gap [0290] 28 Seal on 3 [0291] 29 Compensation volume [0292] 30 Compensation device [0293] 30a Hollow cylinder [0294] 31 Valve unit [0295] 31a Valve head [0296] 32 Air chamber [0297] 33 Seal [0298] 34 Separating piston [0299] 35 Cover [0300] 36 Channel [0301] 37 Energy store [0302] 38 Angle range [0303] 39 Permanent magnet [0304] 40 Sensor device [0305] 41 Spacing [0306] 42 Seal of 23 [0307] 43 Intermediate space [0308] 44 Bearing [0309] 45 Load sensor [0310] 46 Arm [0311] 47 Spring, torsion bar [0312] 48 Sensor line [0313] 49 Holder, spacer [0314] 50 Insert [0315] 51 One-way valve [0316] 52 Valve unit [0317] 53 Movement direction [0318] 54 Pressure accumulator [0319] 55 Arrow direction [0320] 56 Permanent magnet [0321] 60 Damper volume [0322] 61, 62 Chamber [0323] 63 Connecting channel [0324] 63a Second connecting channel [0325] 64 Mechanical stop [0326] 65 Bleed screw [0327] 66 Nitrogen valve [0328] 67 Insert [0329] 68, 69 Sensor [0330] 70 Non-circular coupling contour [0331] 71 Closure [0332] 72 Channel [0333] 80 Basic position [0334] 100 Apparatus, stabilizer [0335] 101 Door [0336] 102 Stabilizer rod [0337] 103 Stabilizer rod [0338] 111 Distal end [0339] 112 Distal end [0340] 300 Training appliance [0341] 301 Actuating element [0342] 302 Control device [0343] 305 Seat [0344] 309 Lever