Rotation damper with a magnetorheological fluid and damping method

Abstract

A rotation damper has a housing, a magnetic field source and a damper shaft designed as a hollow shaft, and a coupling rod arranged inside the damper shaft. The hollow shaft and the coupling rod form interacting transmission units and convert a relative axial movement of the coupling rod into a rotational movement of the hollow shaft. A displacer unit is arranged in the housing. The displacer unit includes the damper shaft and meshing displacer components that are rotatable in relation to each other. The displacer unit contains a magnetorheological fluid as the working fluid and can be operated thereby. The magnetic field source is configured for applying a magnetic field to the displacer components in order to dampen a rotational movement of the damper shaft.

Claims

1. A rotary damper, comprising: a housing; a damper shaft being a hollow shaft, and a coupling rod received in said damper shaft; said hollow shaft and said coupling rod being configured to interact with one another to convert a relative axial movement of said coupling rod into a rotational movement of said hollow shaft; a displacer apparatus disposed in said housing, said displacer apparatus including displacer components that mesh with one another and are rotatable relative to one another, said displacer components being disposed to form at least one damping duct extending substantially parallel with said damper shaft and a face-side axial gap with said housing, and said displacer apparatus containing a magnetorheological fluid in said at least one damping duct and in said face-side axial gap, said magnetorheological fluid forming a working fluid; and a magnetic field source configured to generate a magnetic field to act upon said displacer components and said magnetorheological fluid in order to damp a rotational movement of said damper shaft, said magnetic field source including two electric coils each configured to generate a magnetic field with a substantial portion of field lines thereof traversing said at least one damping duct and said axial gap between said housing and said displacer components and to seal said axial gap against leakage of the magnetorheological fluid; said displacer components including a first displacer component having an outer toothing and a second displacer component having an internal toothing, and wherein said second displacer component is rotatably received in said housing; at least one damping gap forms said at least one damping duct radially between said second displacer component and said housing; said second displacer component is rotatably guided in said housing via a multiplicity of guide units in order to form said damping gap between said second displacer unit and said housing; and said displacer apparatus being configured as a pump; said magnetorheological fluid being conveyed by rotational movement of said displacer components from an inlet of said displacer apparatus adjacent to one of the face-side axial gaps to an outlet of said displacer apparatus adjacent on to the other one of the face-side axial gaps, and said magnetorheological fluid being conveyed via the damping gap back to the inlet of the displacer apparatus.

2. The rotary damper according to claim 1, wherein said coupling rod is formed with a notch and said hollow shaft is formed with a notch profile adapted to mesh with said notch profile of said coupling rod.

3. The rotary damper according to claim 1, wherein said coupling rod comprises a threaded spindle and wherein a threaded nut is disposed to mesh with said treaded spindle to convert the relative axial movement of said coupling rod into the rotational movement of said hollow shaft.

4. The rotary damper according to claim 3, wherein said threaded nut is formed with an axial stop and is rotatably and axially fixed in said housing.

5. The rotary damper according to claim 1, wherein said magnetic field source is configured to subject said displacer components which engage in one another and are rotatable relative to one another to a magnetic field in order to damp a rotational movement of said damper shaft.

6. The rotary damper according to claim 1, wherein said face-side axial gap includes a face-side axial gap formed between said housing and said displacer apparatus at each of the two axial ends of said displacer components and wherein a substantial part of the magnetic field of said magnetic field source penetrates through each of said axial gaps between said housing and said displacer components and brings about a sealing of the face-side axial gaps.

7. The rotary damper according to claim 1, wherein said displacer components comprise a first displacer component fixedly connected to said damper shaft and a second displacer component rotatably mounted in said housing, wherein said first displacer component is in engagement with said second displacer component and is arranged eccentrically with respect to said second displacer component.

8. The rotary damper according to claim 1, wherein said housing comprises a first end region and a second end region and a central region therebetween, and wherein said electric coils are respectively received in each of said first and second end regions, and wherein an axis of at least of one of said coils is aligned substantially parallel to said damper shaft.

9. The rotary damper according to claim 8, further comprising a compensating apparatus coupled to the central region.

10. The rotary damper according to claim 1, wherein said housing is composed of magnetically conducting material having a relative permeability of greater than 100, and further comprising a ring composed of a material with a relative permeability of less than 10 arranged axially adjacent said electric coils in said housing and axially between said electric coils and said displacer components.

11. The rotary damper according to claim 1, wherein said inlet and said outlet are arranged on different axial sides of said displacer apparatus and the magnetic field is formed to be weaker in a region of said inlet than in a region of said outlet.

12. The rotary damper according to claim 1, further comprising at least one sensor for detecting a measure for an angular position of said damper shaft.

13. A transport vehicle selected from the group consisting of troop transporters, tanks, and helicopters and comprising: a rotary damper according to claim 1 in order to protect transported persons from sudden impacts or sudden momentum changes.

14. A method for damping a linear movement, the method comprising: providing a rotary damper having a coupling rod and a hollow shaft; converting a relative axial movement of the coupling rod of the rotary damper into a rotational movement of the hollow shaft of the rotary damper; providing the rotary damper with at least one displacer apparatus in a housing, the displacer apparatus including displacer components which engage in one another and are rotatable relative to one another and the damper shaft and contains a magnetorheological fluid as the working fluid; and said displacer components including a first displacer component having an outer toothing and a second displacer component having an internal toothing, and said second displacer component is rotatably received in said housing, at least one damping gap forms said at least one damping duct radially between said second displacer component and said housing, and said second displacer component is rotatably guided in said housing via a multiplicity of guide units in order to form said damping gap between said second displacer unit and said housing; said displacer apparatus being configured as a pump; said magnetorheological fluid being conveyed by rotational movement of said displacer components from an inlet of said displacer apparatus adjacent to one of the face-side axial gaps to an outlet of said displacer apparatus adjacent on to the other one of the face-side axial gaps, and said magnetorheological fluid being conveyed via the damping gap back to the inlet of the displacer apparatus; and generating a magnetic field by energizing two electric coils to act upon the displacer components and the magnetorheological fluid in order to damp a rotational movement of the damper shaft and to seal an axial gap against a leakage of the magnetorheological fluid out of the housing, the two electric coils being disposed to cause the magnetic field to traverse a damping duct formed between the displacer components and to traverse the axial gap.

15. A rotary damper, comprising: a housing composed of magnetically conducting material having a relative permeability of greater than 100; a damper shaft being a hollow shaft, and a coupling rod received in said damper shaft; said hollow shaft and said coupling rod include transmission units configured to interact with one another and to convert a relative axial movement of said coupling rod into a rotational movement of said hollow shaft; a displacer apparatus disposed in said housing, said displacer apparatus including displacer components that mesh with one another and are rotatable relative to one another and said displacer apparatus containing a magneto-rheological fluid forming a working fluid, and said displacer components including a first displacer component having an outer toothing and a second displacer component having an internal toothing, and said second displacer component is rotatably received in said housing, at least one damping gap forms said at least one damping duct radially between said second displacer component and said housing, and said second displacer component is rotatably guided in said housing via a multiplicity of guide units in order to form said damping gap between said second displacer unit and said housing; a magnetic field source configured to generate a magnetic field to act upon said displacer components in order to damp a rotational movement of said damper shaft; and a ring composed of a material with a relative permeability of less than 10 arranged axially adjacent said magnetic field source in said housing and axially between said magnetic field source and said displacer components; and said displacer apparatus being configured as a pump; said magnetorheological fluid being conveyed by rotational movement of said displacer components from an inlet of said displacer apparatus adjacent to one of the face-side axial gaps to an outlet of said displacer apparatus adjacent on to the other one of the face-side axial gaps, and said magnetorheological fluid being conveyed via the damping gap back to the inlet of the displacer apparatus.

16. The rotary damper according to claim 1, wherein the damping gap is formed as an annular gap divided by the guide units into several gap segments.

Description

(1) Further advantages and features of the present invention are apparent from the exemplary embodiments which are explained below with reference to the enclosed figures.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(2) In the figures:

(3) FIG. 1 shows a schematic cross-section through an apparatus with a rotary damper;

(4) FIG. 2 shows an exploded representation of the apparatus according to FIG. 1;

(5) FIG. 3 shows a highly schematic cross-section through a rotary damper;

(6) FIG. 3b shows a schematic top view of an end region of the housing of the rotary damper according to FIG. 2 or 3; and

(7) FIG. 4 shows a highly schematic top view of a use of the rotary damper in a seat.

DESCRIPTION OF THE INVENTION

(8) Exemplary embodiments of the invention are explained below with reference to the enclosed figures.

(9) FIG. 1 shows a cross-section through an apparatus 100 with a rotary damper 1. Connecting unit 151 is connected to coupling rod 60. First transmission unit 61 with first notch profile 62 is formed on coupling rod 60. Here, first transmission unit 61 is embodied as threaded spindle 65. First transmission unit 61 interacts with second transmission unit 71 which has an adapted second notch profile 72. Here, the second transmission unit is formed as an internal thread on threaded nut 75 which is applied onto threaded spindle 65.

(10) Threaded nut 75 has a flange 77 which stands radially further to the outside and which makes available stop surfaces 76 at its two axial ends. Here, the threaded nut is composed overall of a plastic, as a result of which self-lubrication of the contact surfaces with threaded spindle 65 and axial stops 54 and 55 of housing 12 is performed.

(11) Threaded nut 75 has on a longitudinal portion a non-round outer contour which is coupled to a correspondingly adapted non-round inner contour of drive shaft 3 embodied as hollow shaft 3a. As a result of this, a rotational movement of threaded nut 75 is converted into a rotational movement of hollow shaft 3a.

(12) As a result of the axial fixing of threaded nut 75 by stop surfaces 76 of flange 77 between axial stops 54 and 55 which are coupled to housing 12, threaded nut 75 remains in the same axial position relative to housing 12 even if threaded spindle 65 is moved relative to threaded nut 75.

(13) Housing 12 is composed substantially of a first end region or end segment 22, a second end region or end segment 24 and a central region or central segment 23 arranged therebetween.

(14) Segments 22 and 24 are screwed to one another via screws and nuts 52 and 53, wherein central region 23 is clamped between end regions 22 and 24. Seals 42 are provided between the individual segments.

(15) Displacer apparatus 2 which comprises displacer components 4 and 5 is arranged in the interior of housing 12. Here, displacer component 4 is formed as external toothing 11 in a central region of hollow shaft 3a. Displacer component 5 is formed to be annular and has on the inside an internal toothing 13 which engages in external toothing 11 of displacer component 4.

(16) The number of teeth of internal toothing 13 and external toothing 11 is preferably different. In particular, the number of teeth differs by the value 1. The rotational axes of displacer components 4 and 5 are furthermore arranged in particular parallel to one another.

(17) Hollow shaft 3a is mounted via bearings 44 embodied in particular as plain bearings in end regions 22 and 24 of housing 12. There are arranged axially on the inside of the plain bearings seals 28 which seal off hollow shaft 3 with respect to housing 12 in order to prevent the escape of magnetorheological fluid from the inside of rotary damper 1.

(18) The inner space of the displacer apparatus is filled with magnetorheological fluid 6 so that displacer components 4 and 5 displace the magnetorheological fluid in the event of a rotational movement of hollow shaft 3a.

(19) A magnetic field can be generated via magnetic field sources 8 equipped with electric coils 9, which magnetic field substantially penetrates through displacer components 4 and 5. As a result, a magnetic field acts on the interior of displacer apparatus 2, as a result of which the active torque can be set.

(20) Compensating apparatus 29a is connected to damping gap 18 in central region 23 and makes available a compensating volume 29 in order to compensate for different temperatures and leakage losses. For example, a separating piston or a membrane can be arranged in compensating apparatus 29s in order to reliably separate compensating volume 29 filled with air (can also be nitrogen) from the magnetorheological fluid. If during operation compensating apparatus 29a always remains arranged above the remaining magnetorheological fluid, a separating piston or a membrane can optionally also be omitted since the lighter gas of the compensating volume then collects above the magnetorheological fluid.

(21) FIG. 1 represents yet another variant with a dotted line, in which variant the hollow shaft is formed to be lengthened at the right end here. The hollow shaft can also be lengthened at the other end. A gear wheel 57 which is coupled via a toothed belt as coupling means 56 to a gear wheel of an electric motor 35 is fitted on the hollow shaft. The drive pinion of electric motor 35 is provided with a smaller number of teeth than gear wheel 57 (step-up). Moreover, a further step-down is achieved via the coupling from the threaded nut to the threaded spindle so that electric motor 35 can operate with a higher rotational speed in order to actively move a component or support operation. A chain, V belt, flat belt, V-ribbed belt, friction wheel or a directly meshing toothing can also be used instead of the gear wheel/toothed belt.

(22) On one hand, a high braking torque (e.g. 20 Nm) can be applied by magnetorheological rotary damper 1 via such a configuration, while on the other hand an active movement of components is possible via electric motor 35. The torque to be applied by electric motor 35 does not have to be large (e.g. <1 Nm, preferably <0.1 Nm) so that a small/low-cost motor with a low capacity is sufficient.

(23) FIG. 2 shows an exploded representation of the device according to FIG. 1.

(24) Axial stop 55 serves to fix threaded nut 75 and is pressed on first end region 22 of housing 12 in order to axially fix threaded nut 75 on housing 12. On the other hand, an axial stop 54 acts against other stop surface 76 of flange 77 of threaded nut 75. Threaded nut 75 rotates during a linear movement of threaded spindle 65. Threaded spindle 65 is connected to first connecting unit 151.

(25) Bearings 44 serve to bear damper shaft 3 formed as hollow shaft 3a. In the mounted state, rings 20 are positioned next to electric coils 9 and prevent a magnetic short circuit.

(26) Housing parts 22, 23 and 24 are screwed to one another via screws 52 and nuts 53. In this case, hollow shaft 3a with external toothing 11 (displacer component 4) and displacer component 5 with internal toothing 13 are received inside housing 12. Displacer component 5 is arranged rotatably in housing 12. Guide units 21 on the outside ensure that a defined radial gap 18 remains between the outer wall of displacer component 5 and the inner wall of housing 12.

(27) Radial gap 18 serves as a damping gap. The magnetorheological fluid displaced from the inlet side to the outlet side by displacer apparatus 2 is returned via radial gap 18 to the inlet side.

(28) FIG. 3 shows a variant of rotary damper 1. Coupling rod 60 is again embodied as a threaded spindle 65 in order to convert an axial movement into a radial movement. Here, in turn, a threaded nut 75 is coupled to hollow shaft 3a.

(29) Rotary damper 1 is extremely compact and can be produced at very low cost and can be used in high pressure ranges. Sealing mechanisms are called on to generate high maximum pressures. Expedient mechanical gap dimensions are used. Moreover, regions of the displacer apparatus and of housing 12 are, where necessary, magnetized in a targeted manner. Critical regions such as the region between the inflow and outflow ducts as well as axial gaps 25 exhibit less leakage and thus higher maximum pressures can be reached. In this case, the intermediate regions of inlet and outlet as well as the axial gaps can be magnetized so that the iron particles of the MRF are specially aligned at these points and take on a significant additional sealing action.

(30) Several magnetic field lines of magnetic field 10 are plotted by way of example in FIG. 3. The magnetic field lines run in each case through an end region 22 or 24 and central region 23 of housing 12 and penetrate approximately radially through damping gap 18 between housing 12 and second displacer component 5 and then pass from second displacer component 5 into first displacer component 4. From there, the magnetic field lines run through axial gap 25 between first or second displacer components 4, 5 and respective end region 22, 24 so that closed magnetic field lines are produced. Here, magnetic fields which overall seal off both radial gap 18 between the displacer components and also the two axial face-side axial gaps 25 are produced by in each case an electric coil 9 in each case in an end region 22, 24.

(31) Due to the fact that an electric coil 9 is provided in each end region of housing 12 and that electric coils 9 extend over the circumference of the respective end region, magnetic field 10 of magnetic field source 8 acts upon practically every gap between displacer components 4, 5 and between displacer components 4, 5 and housing 12. As a result, the magnetorheological particles of magnetorheological fluid 6 present in inner space 16 of rotational damper 1 or of housing 12 interlink, wherein the strength of the interlinking depends on the strength of active magnetic field 10.

(32) A magnetic short circuit in respective end regions 22, 24 is reliably prevented by magnetically non-conducting rings 20 which overall have a relative permeability lower than ten. It is also possible that an end region (or both) is composed of two or more parts or portions. The portion adjoining displacer components 4, 5 preferably offers better magnetic conduction than the magnetically non-conducting ring. The adjoining portion (or the entire end region) preferably has a relative permeability greater than ten and in particular greater than 100 and preferably greater than 1000.

(33) Distances and gaps 18, 25 are represented in an enlarged form in FIG. 3 in order to be able to be made visible in the first place on the represented scale.

(34) Axial gap 25 and radial gap 18 between displacer components 4, 5 and end regions 22, 24 or between second component 5 and housing 12 in the radial direction are clearly visible. In reality, radial gap 18 is preferably approximately 2 to 4 times and in particular approximately three times as large as axial gap 25. In concrete configurations, axial gap 25 of approximately 0.03 mm and a radial gap of approximately up to 0.3 mm have been shown to be expedient.

(35) At axial gaps 25 next to the suction kidney and the pressure kidney, the magnetic field leads to a face-side sealing off by an interlinking and alignment of the iron particles. Face-side axial gaps 25 are also reliably sealed off from high pressures. The leakage between pressure and suction side is small.

(36) FIG. 3b shows a highly schematic top view of an end region 22 or 24 of a housing 12 of a rotary damper 1 from FIG. 1 or 2, wherein the inner structure of rotary damper 1 and flow guidance become clearer. The drawing shows e.g. end region 22 in a top view from the inside, but without displacer component 4. Inner contour 13 of outer displacer component 5 is plotted by dashed lines and can have more or fewer teeth in various configurations. Here, there is provided outside the radially outermost tooth contour of displacer components 4 and 5 a circumferential groove 50 in end region 22 (and 24) which extends in end region 22 (and 24) fully around the axis. Said circumferential groove 50 serves as a collecting (50) or distribution duct (51) for the MRF. The circumferential groove can, however, also extend only over partial regions of the circumference.

(37) A suction kidney 26a through which the MRF can be taken in into intermediate space 43 between internal toothing 13 and external toothing 11 is formed on suction side 26 or at the inlet on the left side here in the drawing. The MRF taken in by suction kidney 26a flows for this purpose from pressure side 27 through damping duct 17 or its partial segments to suction side 26. Damping duct 17 extends in this case across (almost) the entire outer circumference of outer displacer component 5. For example, the narrow segments of guide units 21 can be absent on the entire circumference.

(38) Intake kidney 26a and pressure kidney 27a formed in the other end region on the other face side extend in each case approximately in a kidney-shaped manner over an angle range <180°, as is normal in the case of toothed ring pumps or gerotor pumps. Circumferential groove 50 and intake kidney 26a jointly form a supply duct, while circumferential groove 51 and pressure kidney 27a jointly form a discharge duct.

(39) Collecting groove 50 on the suction side and collecting groove 51 collect the MRF on the suction side and discharge it on the pressure side across the entire circumference. “Cross-talk” or a fluid short circuit is ruled out in that collecting grooves 50 and 51 are arranged on different face sides so that suction and pressure side are axially separated from one another here. The MRF is respectively collected and distributed in the region respectively of the suction kidney and the pressure kidney, the representation of which can be obtained by horizontal mirroring of FIG. 3b. Collecting groove 51 can also be referred to as a distribution groove 51.

(40) The suction kidney and the pressure kidney can also be provided on the same face side, wherein collecting grooves 50 and 51 (over the full circumference) must be dispensed with since otherwise a fluid short circuit would arise. The collecting grooves do not have to extend over the entire circumference. This also applies to damping duct 17.

(41) FIG. 4 shows a seat 300 such as a driver, passenger or crew seat such as is used e.g. in the case of armored vehicles 400 with wheels 401 or chains or the like and is supposed to protect occupants 200 in the event of an explosion of mine 500. Seat 300 is connected to rotary damper 1 here in a vertically displaceable manner and via a coupling rod. Rotary damper 1 corresponds to a rotary damper 1 as described above.

(42) Coupling rod 60 is again embodied as threaded spindle 65 in order to convert an axial movement into a radial movement. Here, in turn, a threaded nut 75 is coupled to hollow shaft 3a. Rotary damper 1 or its electric coil 9 is energized as a function of various parameters so that the occupant is injured to as small a degree as possible or not at all in the event of an explosion of a mine 500. Parameters can be sensor signals. Sensors detect the type and magnitude of the explosion.

(43) The invention also relates in this regard to an assembly for energy absorption in the case of an overload event. The assembly can be part of the seat or comprise such or be formed as such. The assembly comprises in each case at least one rotary damper. The assembly serves in the case of one-off overload events to avoid or reduce damage to objects such as people or items. In this case, the assembly reduces the load resulting from a one-off energy input on an object arranged on the assembly and coupled thereto (such as a person or an item). Such a one-off overload event with an energy input occurs e.g. in particular in the event of a helicopter crashing or e.g. in the event of an emergency landing with an aircraft or an explosion of a mine.

(44) In particular, the assembly according to the invention is used on transport means, such as troop transporters, tanks, helicopters or the like in order to protect in particular transported people from health-endangering or even life-threatening impacts if, for example, a mine is exploded under the transport means.

(45) In the case of the rotary damper in this configuration, no preloading into an end position is in principle present. The rotary damper is not pretensioned in any direction. Identical characteristics in both rotational directions can in principle be set as result of this. The smoothness or the stiffness of a damped linear movement can be set independently of the direction of movement. The rotary damper can thus in the event of deployment be used as an energy absorption element in the event of overload (e.g. explosion of a mine) and also as a (permanent) comfort damper (shock absorber) during travel.

LIST OF REFERENCE NUMBERS

(46) 1 Rotary damper

(47) 2 Displacer apparatus

(48) 3 Damper shaft

(49) 3a Hollow shaft

(50) 4 Displacer component

(51) 5 Displacer component

(52) 6 Magnetorheological fluid

(53) 7 Control apparatus

(54) 8 Magnetic field source

(55) 9 Electric coil

(56) 10 Magnetic field

(57) 11 External toothing of 4

(58) 12 Housing of 2

(59) 13 Internal toothing of 5

(60) 14 Rotational axis of 4

(61) 15 Rotational axis of 5

(62) 16 Inner space of 2

(63) 17 Damping duct

(64) 18 Damping gap (radial)

(65) 19 Axis of 9

(66) 20 Ring in 12

(67) 21 Guide unit

(68) 22 First end region

(69) 23 Central region

(70) 24 Second end region

(71) 25 Axial gap

(72) 26 Inlet, suction side

(73) 26a Suction kidney

(74) 27 Outlet, pressure side

(75) 27a Pressure kidney

(76) 28 Seal at 3

(77) 29 Compensating volume

(78) 29a Compensating apparatus

(79) 29b Filling valve

(80) 32 Sensor

(81) 35 Electric motor

(82) 38 Coil holder

(83) 42 Seal of 23

(84) 43 Intermediate space

(85) 44 Bearing

(86) 50 Collecting groove

(87) 51 Collecting groove

(88) 52 Screw

(89) 53 Nut

(90) 54 Axial stop

(91) 55 Axial stop

(92) 56 Coupling means

(93) 57 Gear wheel

(94) 60 Coupling rod

(95) 61 First transmission unit

(96) 62 First notch profile

(97) 65 Threaded spindle

(98) 70 Gear wheel

(99) 71 Second transmission unit

(100) 72 Second notch profile

(101) 75 Threaded nut

(102) 76 Stop surface

(103) 77 Flange

(104) 100 Apparatus

(105) 151 Connecting unit

(106) 152 Connecting unit

(107) 200 Person

(108) 300 Seat

(109) 400 Transport means

(110) 401 Wheel