Patent Application
20100162776
The present invention relates to a locking device or a valve, a door lock device or a control lever containing such a locking device, respectively with a field-controllable fluid (magnetorheological and/or electrorheological fluid). Furthermore, the invention relates to a locking method in which such a locking device is used and also to the use of such a locking device.
Magnetorheological fluids (MRF) are suspensions of magnetically polarisable particles in a carrier fluid, the viscosity and other rheological properties of which can be changed rapidly and reversibly in a magnetic field. Analogously thereto, electrorheological fluids (ERF) are suspensions of electrically polarisable particles in a non-conductive carrier fluid, the rheological properties of which can be changed rapidly and reversibly in an electrical field. Both classes of fluids (subsequently also: field-controllable fluids) hence offer an ideal basis for locking devices, the locking state of which is controlled by the magnetic field or the electrical field.
Magnetorheological fluids, as can be used in the present invention, are described in the German patent specification DE 10 2004 041 650 B4 which is herewith introduced in its entire scope as a component of the present application.
It is the object of the present invention to make available a locking device (and a corresponding locking method) with which a field-controllable locking can be produced in a mechanically simple, reliable manner.
This object is achieved by a locking device according to claim 1, a locking device according to claim 14 and also a locking method according to claim 41. Advantageous embodiments of the locking device according to the invention are revealed in the respectively dependent patent claims. Uses according to the invention are revealed in claims 38 to 40 and also 42.
Subsequently, the subsequent invention is now firstly described in general, individual embodiments then following this general description. Individual features according to the invention, as are described subsequently, can hereby occur not only in combinations as shown in the special advantageous embodiments but they can also be configured or used within the scope of the present invention in any other combinations.
The basis of the solution according to the invention is the fundamental construction of a locking device comprising two units, a control unit and a locking unit, the latter subsequently termed alternatively also operating unit. On the basis of this separation into the two mentioned units, a field-controllable fluid (e.g. MRF) is then used in the control unit. The use can hereby take place in squeezing mode, in shear mode or in flow mode. The locking unit can be operated optionally hydraulically (using a non-field-controllable, hydraulic fluid which is prevented from flowing through a throughflow opening) or mechanically (the non-field-controllable, hydraulic fluid is replaced here by a mechanical element).
According to the invention, as also described subsequently in more detail, a piston unit and also a locking system (alternatively also termed locking unit or locking part) is provided.
The locking system can hereby be formed from an element, e.g. a locking pin, but it can also comprise a plurality of elements. There is understood by piston unit in the following a mechanical unit (possibly comprising a plurality of elements) of any shape, which is disposed advantageously at least partially within a housing. The piston unit need not therefore have a rotationally symmetrical configuration but can also be configured for example in a cuboid shape.
The locking device has two fundamental states: the locked state and the unlocked state. These two states of the locking device or of the locking system and the piston unit can be converted one into the other in that the relative position of the piston unit to the locking system is changed or in that these two units are moved relative to each other. The state “locked” is used here in a general context: locked can for example mean that the locking system locks the piston unit, i.e. restricts or prevents movement thereof within a surrounding housing. Likewise, “locked” can however mean that the locking system closes a throughflow opening configured in the piston unit. Equally, the state “unlocked” is understood in general: for example the relative moveablity of the piston unit in a housing (or also with respect to the locking system) can be permitted here. Likewise, there is hereby understood however for example the state in which the above-mentioned throughflow opening is opened within the piston unit, i.e. not closed by the locking unit.
In a particularly advantageous solution according to the invention, two surfaces are provided in the control unit which can be moved relative to each other (either moved laterally one past the other or towards or away from each other) so that the field-controllable fluid is sheared and/or squeezed in an intermediate space between these two surfaces in the control unit. A magnetic field or an electrical field is hereby produced in this intermediate space by a field producer (magnet or electrodes), as a result of which the field strength in the field-controllable fluid can be changed in this intermediate space. In the case of using a magnetorheological fluid and a magnet (electromagnet), the intermediate space filled with the MRF is hence situated in the magnetic circuit system of the locking device. The same applies in the case of using electrodes, an electrical field and an electrorheological fluid. As is described subsequently in even more detail, a corresponding change in the mechanical coupling of two control elements of the control unit can be effected by changing the magnetic or electrical field strength, said control elements having the above-described surfaces. As a result, as described subsequently even more precisely, a relative movement (for example between a piston unit and a closing part or a closing unit or also between a closing unit and a housing element) can be controlled in the locking unit, as a result of which a throughflow opening, which connects two chambers within one housing which are separated by a piston unit (subsequently also: piston), can be closed. As a result of such a closure, the flow of a non-field-controllable fluid between the two chambers within the housing can be prevented, as a result of which the movement of the piston unit within the housing can be correspondingly prevented.
However, it is likewise possible, in a particularly advantageous solution according to the invention, to restrict or entirely to prevent the throughflow of a field-controllable fluid through a gap or a throughflow opening between the control unit and the locking unit by applying an external magnetic or electrical field in order to build up a pressure and hence to initiate locking. This embodiment variant is also described subsequently even more precisely.
The locking device according to the invention, relative to locking devices known from the state of the art, has a series of significant advantages:
One particular advantage of the present invention resides quite generally in the separation into a control- and into an operating or locking unit. The essential advantage of this hybrid operating principle, relative to a purely magnetorheological or electrorheological locking, resides in the virtually unlimited locking force which can be achieved in this way. As a result, the relatively heavy unit containing the MRF or the ERF need not in particular be designed to be so large, which involves a lower energy requirement.
A simple, mechanically non-complex system is achieved by the locking device according to the invention.
When using two mutually moveable surfaces, these two surfaces can be securely coupled to each other mechanically in a simple manner by means of the fluids (MRF or ERF) stiffened in the magnetic field or in the electrical field. As a result, locking or the solution of locking is possible in a simple and reliable manner in the locking device.
When using the field-controllable fluid, in particular the magnetorheological fluid MRF, in the squeezing or shearing operation, significantly lesser demands are made upon the properties of the field-controllable fluid and a significantly more reliable operation of the locking device is possible. For example, in the basic state, an MRF without a magnetic field can be very viscous, even magnetorheological gels for example which are not intrinsically free-flowing can be used instead of an MRF. Hence problems which occur in the MRF because of sedimentation of the magnetic particles are avoided. The same applies for electrorheological fluids.
The advantage of the variant in the flow mode resides in the fact that no parts which are moveable relative to each other and require to be guided at a defined spacing relative to each other need be used.
Fields of application of the locking device according to the invention are in particular mechanical and/or electrical locks (e.g. electrical contact) or locking mechanisms or temporary fixings. Possible applications of the locking device according to the invention are in particular electrically controllable locking of moveable parts which are to be fixed temporarily. Examples of this are doors, windows, shutters or operating elements, such as e.g. control levers, push buttons or knobs which are to be made safe against faulty operation.
The present invention hence describes a locking device which can be divided essentially into two units, a control unit and a locking unit. In the control unit which contains the magnetorheological or the electrorheological fluid, advantageously two mutually moveable surfaces, between which the MRF or the electrorheological fluid is situated in the intermediate space, are advantageously coupled securely to each other mechanically by applying a magnetic or electrical field (which then covers the intermediate space). With sufficiently high field strength, the two surfaces can no longer be moved relative to each other. After switching off the field, both surfaces can again be moved relative to each other entirely without a field-produced resistance, a shear movement and/or a squeezing movement being effected with respect to the magnetorheological or electrorheological fluid.
In the second unit, the locking unit which contains a non-field-controllable fluid (or also a gas), a piston unit or a piston is locked by the above-described coupling.
Advantageously, the locking unit or the operating unit has a piston with a throughflow opening, a locking system (closing part) and also a non-field-controllable fluid. However the locking system can also be provided alternatively as part of the control unit. During the movement of the piston, advantageously the non-field-controllable fluid is transported through a throughflow opening between two chambers which are separated from each other by the piston as long as the throughflow opening is not closed by the locking system. Advantageously, the movement of the piston is locked by closing the opening.
Advantageously, as described subsequently in even more detail, the locking system and a switch element (with which the piston unit can be moved, in particular a switch rod) are hereby connected mechanically rigidly to the two surfaces in the control unit, between which surfaces the magnetorheological or the electrorheological fluid is situated. However it is also possible that merely the switch element is connected mechanically rigidly to one of the two surfaces in the control unit.
Advantageously, the two mutually moveable surfaces of the control unit or the corresponding control elements are formed by two cylinder elements (tubes) which are inserted one in the other concentrically or by two plane-parallel plates which are disposed parallel to each other and can be mutually displaced laterally or can be moved towards each other and away from each other. The piston unit can be configured advantageously such that the piston performs a linear movement in the locking unit. The magnetic or electrical field hereby extends advantageously perpendicular to the two surfaces of the control elements and penetrates the gap between the surfaces or the intermediate space. If a magnetorheological fluid is used, then the mutually moveable surfaces are situated advantageously in a magnetic circuit with a coil, the current flowing in the foil producing the magnetic field. In the case an electrorheological fluid, the two mutually moveable surfaces advantageously also form the electrodes between which the electrical field is configured. As a result of the magnetic or electrical field, the mutually moveable surfaces are connected securely to each other frictionally via the stiffened magnetorheological or electrorheological fluid (frictional connection) so that, with sufficiently high field strength, the moveability of the two surfaces relative to each other is removed. If a sufficiently strong field is applied, stiffening of the field-controllable fluid and a secure coupling of the two control elements or surfaces is hence effected, i.e. the above-described locking.
Another advantageous possibility resides in restricting or preventing the throughflow of a magnetorheological or an electrorheological fluid through a throughflow opening by means of the magnetic or electrical field and hence building up a pressure which initiates the locking.
In an advantageous embodiment variant, the locking device hence comprises a control unit which contains a magnetorheological or electrorheological material and also a locking unit (locking unit) which contains mutually moveable parts and also a non-field-controllable fluid and/or mechanical locking elements. The control unit hereby has at least two mutually moveable surfaces, between which the magnetorheological or electrorheological material can be subjected to a shear movement and/or a squeezing movement, or a gap (throughflow opening) through which the magnetorheological or electrorheological material can be pressed through. The control unit hereby contains the magnetic field production (or the production for the electrical field) which stiffens the field-controllable material between the surfaces or in the mentioned gap. The locking unit contains either a closing piston which separates two chambers from each other which are filled with a non-field-controllable fluid and are connected to each other by a valve which is formed from at least two mutually moveable parts and is hence closeable, or the locking unit contains one or more locking elements, as a result of which the movement at least of one moveable part is locked. The locking device can hereby be configured such that the piston in the locking unit performs a linear movement or such that it performs a rotary movement (see subsequent paragraph). Advantageously, the mutually moveable parts, in particular those in the locking unit (closing piston or locking elements), can be retained in an equilibrium position by at least one spring element.
However, in another advantageous embodiment, it is also possible to construct the locking device according to the invention on the basis of a rotary piston unit instead of on the basis of a linear piston unit. A movement of the rotary piston is then locked. Likewise a control- and a locking unit are produced hereby in the locking device. As in the case of the linear locker, the movement of the rotary piston is correspondingly prevented in the locking unit by preventing the throughflow of the non-field-controllable fluid which is displaced by the rotary piston through a gap (throughflow opening or valve gap). The closure of the throughflow opening hence locks the device. At least one of the mutually moveable parts forming the throughflow opening is advantageously connected mechanically rigidly to one of the mutually moveable surfaces in the control unit. The two surfaces in the control unit, between which the magnetorheological or electrorheological fluid is situated in an intermediate space, are integrated just as with the linear locker in a magnetic circuit or serve as electrodes for producing the electrical field. Therefore both the locking of a translatory movement and the locking of a rotational movement is possible according to the invention.
A further possibility resides in those moveable parts which ultimately change or control the locking state of locking system and piston unit in the locking unit, in the control unit or between the locking unit and control unit, being retained in an equilibrium position relative to each other, connected amongst each other or to each other by at least one spring element. Hence a pre-adjustment of the locking state is predetermined without applying a field.
In a further advantageous embodiment variant, it is possible to provide at least one permanent magnet in addition to an electromagnet in the magnetic circuit of the control unit and/or between control- and locking unit. As a result of such integration of an additional permanent magnet which likewise affects the magnetic field for the magnetorheological fluid in the intermediate space or in the throughflow opening, a locking state of the device can be produced without energy expenditure (adjustment of the operating point of the locking device; mechanical coupling of the two surfaces without current flow in the coil of the electromagnet is possible).
Further advantageous embodiment variants reside in the fact that, instead of an MRF, there is used as field-controllable material a magnetorheological gel (MRG), a magnetorheological elastomer (MRE) or a magnetorheological foam (MRS) or a combination of such materials. An MRG is hereby a material which is in fact soft in contrast to an MRF but is not fluid. Analogously to MRF, it can be deformed irreversibly in any manner and can be stiffened in the magnetic field analogously to an MRF. An MRE is a cross-linked material which therefore has a prescribed shape from which it can be deformed reversibly only in a limited manner. An MRS is an elastomer foam, the pores of which are filled with an MRF. Like the MRE, an MRS also has a prescribed shape from which it can be deformed reversibly only in a limited manner. In the case of MRE or MRS, a restoring force can be produced between the mutually moveable surfaces at the same time due to the elasticity of the material, which restores said surfaces back into their respective starting position after switching off the magnetic field.
In a further advantageous embodiment variant, there can be used as field-controllable material, instead of an electrorheological fluid (ERF), an electrorheological gel (ERG), an electrorheological elastomer (ERE) or an electrorheological foam (ERS). These materials are defined entirely analogously to the corresponding magnetorheological materials or have the properties of the corresponding magnetorheological materials.
A particularly advantageous selection of the non-field-controllable fluid resides in using the same fluid which is also used as carrier fluid in the magnetorheological or electrorheological fluid also as non-field-controllable fluid.
Instead of using a non-field-controllable fluid, a gas can also be used.
The subsequent invention is described subsequently with reference to individual embodiments. In the individual Figures which are associated with the embodiments, the same or corresponding elements of the damping device are hereby designated with identical reference numbers.
There are shown:
The locking unit 3 is disposed concentrically within the actual piston 2b, within which, again concentrically, the lower portion of the switch rod 7 to which the coil 4 of the electromagnet is securely connected mechanically is disposed. The closing unit 3 is displaceable along the axis A relative to the piston 2b and to the housing 1 so that, according to the position of the locking unit 3, the throughflow opening D is either closed or opened relative to the actual piston 2b.
Between the inner wall of the closing unit 3 and the lower portion of the switch rod 7, the magnetorheological fluid M is disposed in the intermediate space Z. The outer circumference of the lower portion of the switch rod 7 with the coil 4 of the electromagnet forms the first surface O1 of the first control element. The inner wall of the locking system 3 situated opposite this outer circumference forms the second surface O2 of the second control element. The lower portion of the switch rod 7 is connected via a restoring spring 6a to the inner wall of the base portion of the locking system 3. The outer wall (orientated towards the element 2c) of the base portion of the locking system 3 is connected by a closing spring 6b to the upper portion of the lower piston rod unit 2c.
The illustrated locking device is configured as a valve. Locking is effected hereby in the form of a mechanical closing of the throughflow opening D of the piston unit 2b by the closing element 3. The mode of operation of the device is now described in the following,
Firstly, the locking device is completely closed by the locking system 3 (closure of channel D). If the locking device is to be unlocked (opening of channel D), then the closing unit 3 must be moved relative to the piston 2b (downwards). This takes place with the switch rod 7 which is moveable relative to the piston 2: if no magnetic field is acting on the MRF M in the intermediate space Z, then the closing part 3 (see
The closing spring 6b is provided here as compression spring which ensures, in the relaxed state, that the closing element 3 closes the throughflow opening D. The closing element 3 must hence be moved by means of the switch rod 7, as described above, in opposition to this spring force in order to open the valve. In the inoperative state (without field), the restoring spring 6a ensures that the switch rod 7 adopts the position shown in
In the presented example, there are associated with the control unit the restoring spring 6a, the closing element 3, the switch rod 7 and also the electromagnet or the coil 4. There are associated with the locking unit the piston unit 2, the housing 1 and also the closing spring 6b.
This embodiment hence shows a locking device with magnetorheological fluid with a shear movement in the intermediate space Z, the first surface O1 being configured as part of the switch rod 7 and of the coil 4 and the second surface O2 as part of the locking system 3.
Within the housing 1, the following elements of the locking device are disposed, inserted respectively one in the other concentrically (and observed from outside towards the inside to the axis A): firstly the piston 2, then the opening unit 5 inserted concentrically in the latter and at a spacing therefrom. The upper portion of the switch rod 7 is inserted concentrically into the upper portion of the piston 2; the lower, thickened portion of the switch rod 7 (on which the coil 4 is mounted) is inserted concentrically into the opening unit 5. All these above-mentioned elements 1, 2, 5 and 7 (with 4) are moveable relative to each other, as long as no fixing is effected, along the axis A.
The outer circumference of the lower portion of the switch rod 7 (with the coil 4) forms the first surface O1 of the first control element. The inner wall surface of the opening unit 5 which is situated opposite this outer circumference forms the second surface O2 of the second control element. The magnetorheological fluid M is disposed in the intermediate space Z between the two surfaces O1 and O2. The opening unit 5 here represents a hollow cylinder which is sealed at the bottom by the wall element W and also by the chamfered surface E1, described subsequently in more detail, and which is sealed at the top by the fluid-tight leadthrough of the switch rod 7 through the upper cover surface (of the opening unit 5). Leakage of the magnetorheological fluid M is prevented in this way.
Within the housing 1 and below the units 2, 7 (with 4) and 5, the locking system 3 is disposed. This comprises two approximately semicircular cylindrical hollow wall elements which are pressed laterally by a spacing spring 6 in the inoperative state against the inner wall surfaces of the housing 1. Since the lower portion of the piston 2 stands in this position directly on a ring R which is disposed on the outer circumference of the locking system 3 (said ring itself being part of the unit 3), no movement of the piston 2 within the housing is possible 1 in this state (locked state), as shown in
The lower portion of the opening unit 5 now has, on the outer circumference, with respect to the axis A and with respect to a plane perpendicular to the axis A, a lower end surface E1 which is at an angle greater than 0° and less than 90° (preferably: respectively 45°) and is therefore chamfered. Likewise, the upper portion of the locking system has, on the outer circumference, chamfered upper end surfaces E2. The end surfaces E1 and E2 extend parallel to each other and engage laterally offset one in the other since the surface A1, observed radially, has a somewhat smaller spacing from the axis A.
The mode of operation of the illustrated locking device is now as follows: if the switch rod 7 is pushed mechanically downwards, two different states are possible: when current is switched off in the coil 4 (
If now however current is switched on in the coil 4, then the MRF M in the intermediate space Z stiffens: as a result of this stiffening, the opening unit 5 is coupled securely to the switch rod 7 so that, upon moving the rod 7 downwards, now the opening unit 5 (which has not moved relative to the housing when the field is switched off) is also jointly moved downwards. Due to the meshing of the lower portion of the opening unit 5 with the upper portion of the closing unit 3 (engagement of both parallel surfaces E1 and E2 one in the other), the two semicircular parts of the locking system 3 are pressed inwards (i.e. towards the central axis A) in opposition to the tensioning force of the compression spring 6 by the downwards movement of the opening unit 5. Hence, because of the movement of the contact ring R inwards towards the axis A, the locking device 3 frees the movement of the piston 2 downwards (on the right,
Here also, the magnetorheological fluid M is used according to the invention in shear mode.
There are associated with the control unit, in the illustrated case, the opening unit 5, the switch rod 7 and also the coil 4 connected securely to this unit 7. There are associated with the operating unit (locking unit) the piston 2, the housing 1, the closing element 3 and also the spacer (spring) 6 which, in the case shown in
In the interior of the opening unit 5 (the lower outer portion of which is constructed as in
The illustrated device now functions corresponding to the principle presented in
There are associated with the control unit in the present case the opening unit 5, the switch rod 7 and also the coil or the electromagnet 4. There are associated with the locking unit the piston 2, the housing 1, the closing element 3 and also the spring element 6.
The actual piston 2b, radially at a spacing from the central axis A has from inside to outside firstly a cavity H, then a throughflow opening D between the two chambers K1 and K2. In the upper region of the cavity H, the switch rod 7 is disposed inserted concentrically within the actual piston 2b (and also with its upper portion also within the upper piston rod element 2a). The lower portion of the switch rod 7 is hereby thickened relative to the upper portion and carries the coil 4 of the electromagnet. The cavity H is filled with the magnetorheological fluid M. Between the outer circumference of the thickened portion of the lower switch rod part and that inner wall of the actual piston 2a which delimits the cavity H to the outside (observed from the axis A), a throughflow opening S is configured. In alternative variants, the opening S can however also be configured within one of these elements (switch rod 7 or piston 2). These and also the thickened lower end of the switch rod 7 (including coil 4) divide the cavity H into two chambers H1 and H2 (with a constant total volume). By means of a movement of the switch rod 7 relative to the piston 2b along the axis A, the chamber volumes H1 and H2 can be changed (with a constant total volume), the magnetorheological fluid being displaced between these two chamber parts (through the gap S).
In the lower portion of the piston 2b, the closing element 3 of the control unit is disposed in the cavity H. This comprises here two flat, semicircular hollow cylindrical portions which are retained via a tension-compression spring 6 in an equilibrium position in which the throughflow opening D is opened. If the two parts of the closing unit 3 (observed from the axis A) are moved radially outwards in opposition to the spring force of the spring 6, then the throughflow opening D is closed by this movement.
The mode of operation is hereby as follows: with this principle, the magnetorheological fluid is used in flow mode. In the basic sate (equilibrium position of the closing unit 3), the valve of the locking unit is open, as shown in
In the illustrated case, there are associated with the control unit the closing parts of the closing unit 3, the switch rod 7 together with the coil 4 and also the restoring spring 6. There are associated with the locking unit the piston unit 2 and also the housing 1.
a hereby shows a section through a plane in which the central axis A (at the same time axis of rotation here) of the rotary piston unit 2 is situated.
The rotary piston 2 is secured rigidly here on the input shaft of the axis of rotation A and has a shaft portion 2b which is disposed rotationally symmetrically about the axis A and also a wing element 2a which protrudes therefrom radially symmetrically. According to the position of the wing element (see
The first control element (or the first surface O1) is hereby configured as the inner wall portion of the closing unit 3 which is orientated towards the axis A. The second control element (or the second surface O2) is hereby configured as the outer wall portion of the input shaft element 2b which is orientated away from the axis A. As
With sufficient magnetic field strength in the intermediate space Z, a frictional, secure, mechanical coupling of closing unit 3 and input shaft portion 2b of the rotary piston unit 2 can hence be achieved. By suitable adjustment of the position of the rotary piston unit 2 relative to the housing, the restoring force of the springs 6a1 and 6a2 and also the field strength in the intermediate space Z, the relative position of the closing unit 3 relative to the ribbed portion of the housing 1 can hence be changed or adjusted. By influencing the arrangement of the closing unit 3 relative to the portion 1a of the housing 1, the relative movement of unit 2 and unit 1, according to the chosen field strength, hence has the effect of opening or closing the throughflow opening D of the valve gap between the two chambers K1 and K2. According to the position of the closing unit 3 relative to the housing 1, the rotary piston 2 within the housing 1 is hence blocked (locked) or released (unlocked).
In the illustrated example, the rotary piston 2a, 2b is hence mounted rigidly on the input shaft. Parallel thereto, the coil 4 for field production is mounted on the input shaft element 2b. By means of the rotary movement of the wing portion 2a in the locking unit, the non-field-controllable fluid F is pressed through the valve gap D when the field is switched off. The closing unit 3 can be moved relative to the housing 1 and to the input shaft or to the rotary piston 2. The closing element is retained by the two springs 6a1 and 6a2 in its starting position (equilibrium position). By moving the closing part portion 3 of the valve in its guide within the ribbed housing portion 1a, the valve gap D can be closed. Since the coil 4 is situated on the same shaft as the rotary piston, said coil is likewise moved during a rotary movement of the piston.
The relative movement of the closing element and housing 1 is caused by a magnetic field-dependent shearing (rotary shearing) of the MRF which is situated in the intermediate space Z between the two surfaces O1 and O2. If no magnetic field is acting in the intermediate space Z, the closing element 3 is moved by the springs 6 into its starting position or retained there, the gap D is open.
There are associated with the control unit in the present case the shaft portion 2b (including coil 4) and also the portion of the closing unit 3 in the region B-B (shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2007 017 588.6 | Apr 2007 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2008/002900 | 4/11/2008 | WO | 00 | 2/24/2010 |
