Abstract
The invention relates to a bearing arrangement having a radial spherical plain bearing with an inner ring (10), which is arranged on a bolt (15) or pin and has a spherical outer contour (12), and with an outer ring (20), which has a hollow spherical inner geometry (22) for receiving the inner ring (10) and an outer geometry (21) for mounting in a bearing seat (30), wherein the inner ring (10) and the outer ring (20) are preloaded against one another in an axial direction via at least one preloading device (41, 42).
Claims
1. A bearing arrangement having a radial spherical joint comprising: a bolt or pin; an inner ring arranged on the bolt or pin, wherein the inner ring has a spherical outer contour; an outer ring, which has a hollow-spherical inner geometry for receiving the inner ring, and an outer geometry for mounting in a bearing seat; and at least one pretensioning device, wherein the inner ring and the outer ring are pretensioned against each other in an axial direction via the at least one pretensioning device.
2. The bearing arrangement as claimed in claim 1, wherein the at least one pretensioning device comprises a first pretensioning device which exerts a first axial force on the outer ring or the inner ring.
3. The bearing arrangement as claimed in claim 2, wherein the at least one pretensioning device comprises a second pretensioning device which exerts a second axial force directed counter to the first axial force of the first pretensioning device, and wherein the second axial force is exerted on either the inner ring or the outer ring whichever is not acted upon by the first axial force.
4. The bearing arrangement as claimed in claim 1 wherein the at least one pretensioning device is designed as an elastic element, a magnetic element, a hydraulic system, a pneumatic system, and/or has an actuator.
5. The bearing arrangement as claimed in claim 4, wherein the at least one pretensioning device is designed with the elastic element, and wherein the elastic element has a spring characteristic with a slight gradient.
6. The bearing arrangement as claimed in claim 1 further comprising an adjusting device via which the at least one pretensioning device is adjustable.
7. The bearing arrangement as claimed in claim 1 wherein the at least one pretensioning device is supported on the bearing seat, the inner ring, the outer ring, or a component mounted in a bore of the inner ring.
8. The bearing arrangement as claimed in claim 1 wherein the at least one pretensioning device bears directly on the inner ring and/or the outer ring or is coupled to the inner ring and/or the outer ring via a coupling element.
9. The bearing arrangement as claimed in claim 1 wherein the inner ring has a bore for receiving the bolt or pin, or wherein the inner ring is formed in one piece with the bolt or pin.
10. An orthopedic device having a bearing arrangement as claimed in claim 1.
11. The orthopedic device as claimed in claim 10, wherein the bearing arrangement is arranged on a linear actuator.
Description
[0027] FIG. 1 shows a detailed view of a bearing arrangement in section;
[0028] FIG. 2 shows a variant of the bearing arrangement according to FIG. 1;
[0029] FIG. 3 shows a perspective view of a prosthetic joint device;
[0030] FIG. 4 shows a variant of FIG. 1;
[0031] FIG. 5 shows a variant of FIG. 2;
[0032] FIG. 6 shows a variant of FIG. 5;
[0033] FIG. 6a shows a variant of FIG. 6;
[0034] FIG. 6b shows a variant of FIGS. 6a, and
[0035] FIG. 7 shows a perspective view of an orthotic joint device.
[0036] FIG. 1 shows a partial sectional view of a bearing arrangement of a radial spherical joint with an inner ring 10 which is mounted on a bolt 15. The bolt 15, which is part of a hydraulic actuator for example, is inserted in a bore 11 of the inner ring 10 and secured against axial displacement along the longitudinal extent of the bolt 15 by securing elements 31, 32. The inner ring 10 is clamped between the two securing elements 31, 32 and clamped on the bolt 15 or on the axle accommodated within the bore 11. The securing elements 31, 32 can be screwed together or coupled to each other in some other way. The inner ring 10 also has an outer contour 12, which is spherical.
[0037] Furthermore, the bearing arrangement has an outer ring with a likewise spherical inner geometry 22. The inner geometry 22 is shaped corresponding to the outer contour 12 of the inner ring 10, with necessary bearing play being present between the outer ring 20 and the inner ring 10, so that the inner ring 10 can be moved relative to the outer ring 20. On account of the spherical configuration of both the outer contour 12 and the inner geometry 22, with the center points of the spherical inner geometry 22 and of the spherical outer contour 12 advantageously coinciding, it is possible for the bolt to be able to rotate relative to the outer ring 20 in three rotational degrees of freedom.
[0038] The outer ring 20 is mounted in a bearing seat 30 with a sliding fit there, such that the outer ring is movable in the axial direction. By contrast, the inner ring 10 is advantageously in an interference fit on the bolt 15 and cannot be moved axially on the bolt 15.
[0039] In the illustrative embodiment shown, an elastic element bears on the outer ring 20, as a pretensioning device 41 for providing a single axial pretensioning force in the direction of the outer ring 20, and is supported on a securing element 32 via a coupling element 43. The elastic element 41 is interposed between the outer ring and a component of the joint device other than the inner ring 10 or the outer ring 20. The pretensioning force does not act between two parts of a split outer ring which are braced against each other in order to adjust the bearing clearance, but is supported on a component outside the bearing rings. As an alternative to the arrangement of the coupling element 43 on the securing element 32, the coupling element 43 can also be arranged between the outer ring 20 and the elastic element 41. The coupling element 43 can facilitate a relative movement between the elastic element 41 and the securing element 32, for example by providing a favorable friction pairing. The coupling element 43 can also be used to fix the elastic element 41 to the securing element 32 or, in the case of a reverse arrangement, to the outer ring 20. Any play that may be present is caused by the pretensioned, elastic element 41 which exerts on the outer ring 20 a force acting in the axial direction. Play is thus compensated for by shifting of the outer ring 20 relative to the inner ring 10. The outer ring 20 is that part of the bearing arrangement which is or can be axially displaced by the elastic element 41 on account of the pretensioning force and thus compensates for play between the inner ring 10 and the outer ring 20.
[0040] FIG. 1 shows the pretensioning force F.sub.v acting in the axial direction, which force is directed to the left in the illustrative embodiment shown. As a result, the outer ring 20 is shifted relative to the inner ring 10, such that in FIG. 1 a right-hand subregion of the outer contour 12 is pressed against a correspondingly configured subregion of the inner geometry 22. On the left-hand side, the bearing gap thus increases, which cannot be seen on account of the small dimension of the bearing play. The pretensioning force F.sub.v ensures that a radial play is eliminated solely by compensating for the bearing play in the axial direction, without the bearing clearance between the inner ring 10 and the outer ring having to be reduced or changed. The application of an axial force is easily possible in design terms and does not require any complex components for expanding or reducing the circumference of the outer ring 20.
[0041] The sliding fit present between the outer ring 20 and the bearing seat 30 in the illustrative embodiment shown is merely one of several possibilities for eliminating radial play by compensating for axial play. An alternative set-up is one in which an enlarged gap is formed between at least one of the securing elements 31, 32 and the bearing seat 30, and the outer ring 20 is fixed axially in the bearing seat 30. The elastic element 41 can then act directly on the outer ring 20 or the bearing seat 30.
[0042] Alternatively, an elastic element can also be attached to the outer ring 20 or the inner ring 10 and be supported on the other ring, thus generating an axial force and a pretensioning between the two bearing rings.
[0043] FIG. 2 shows a structural set-up comparable to the bearing arrangement in FIG. 1. In addition to the first pretensioning device 41 in the form of a first elastic element, a second pretensioning device 42 is provided which exerts a compressive force F.sub.v on the inner ring 10, this pretensioning force likewise acting as a compressive force in the axial direction, but directed counter to the pretensioning force of the first elastic element 41. This has the effect that the right-hand side, as shown in the figure, of the inner ring 10 bears on the right-hand inner contour of the outer ring 20. The second elastic element 42 is also supported on a securing element 31, such that both forces are supported on components outside of the bearing rings 10, 20 on an abutment.
[0044] In principle, there is also the possibility that the pretensioning device 41, 42 is arranged on the outer ring and is supported on the inner ring 10 in order to bring about bracing and pretensioning in the axial direction. The introduction of the pretensioning force thus takes place on a component that is different from the inner ring or outer ring, respectively. When the axial pretensioning force is applied, the inner ring only ever bears on a surface region of the outer ring that is offset in the axial direction from the middle of the outer ring 20.
[0045] FIG. 3 shows a perspective view of an orthopedic joint device 1 in the form of a prosthetic knee joint. The orthopedic joint device 1 has an upper part 2 and a lower part 3 which are mounted on each other so as to be pivotable about a joint axis 4. The lower part 3 is designed as a three-dimensional hollow body which has an actuator or a damping device 5 with a piston rod 16. At its proximal end, the upper part 2 has a device 7 for fastening a proximal component, for example a thigh tube or a thigh socket. In the illustrative embodiment shown, the fastening device 7 is designed as a pyramid adapter; other designs are likewise possible. Moreover, a head as a bearing point or bearing seat 30, which is arranged on or attached to a proximal end of the piston rod 16, is mounted on the upper part 2 so as to be pivotable about an axle or pin 15, which will be explained in more detail later. Furthermore, the distal end of the damping device is mounted pivotably about an axis 35 at a distal bearing point or a distal bearing seat 36. The fixing of the damping device 5 both at the distal bearing point 36 and on the head or the proximal bearing seat 30 can be releasable, in particular via a screw connection or snap-fit connection.
[0046] In particular, the distal bearing point allows the damping device 5 to pivot exclusively about the pivot axis 35, which is oriented substantially parallel to the joint axis 4. Alternatively, a spherical joint with outer ring 20 and inner ring 10, as described with reference to FIG. 1 or 2, is arranged in the distal bearing seat 36. The head on the piston rod 16 serves in particular as a bearing seat 30 for a spherical joint with outer ring 20 and inner ring 10. The inner ring 10 is mounted on the bolt 15 and, on account of the spherical outer contour and the bearing in the corresponding spherical receptacle in the outer ring 20, the piston rod 16 performs a pivoting movement about the longitudinal extent of the bolt 15 and about the other two rotational degrees of freedom. As a result, the piston rod 16 is decoupled from bending moments when the upper part 2 pivots about the pivot axis 4. The same applies when the distal bearing seat 36 is mounted in a radial spherical joint.
[0047] The damping device 5, as shown in FIG. 3, can be in the form of a hydraulic damping device; a pneumatic damping device is also provided as an alternative. Damping devices which work on the basis of magnetorheological effects can also be used. As an alternative to a passive configuration, the damping device 5 can also be designed as an actuator, for example as an electric drive, which enables and permits a displacement of the upper part 2 relative to the lower part 3 through a corresponding connection and opposes this displacement with a resistance.
[0048] In addition to an embodiment of the orthopedic joint device 1 as a prosthetic knee joint, it can also be designed as an orthotic knee joint or another joint device.
[0049] FIG. 4 shows a variant of the embodiment according to FIG. 1 in a sectional view. Between the securing elements 31, 32 and the bearing seat 30, gaps 50 are arranged or formed on both sides, said gaps being larger compared to the embodiment according to FIG. 1. The bearing seat 30 is supported on the outer ring 20 and can move about a pivot axis 170 which is oriented perpendicularly to the plane of the drawing and runs through the center point of the radius of the outer contour 12 or of the inner geometry 22. In addition, by means of the gaps 50, the bearing seat 30 can pivot about a second pivot axis 160, which runs perpendicular to the longitudinal extent and longitudinal axis 150 of the bolt and lies in the plane of the drawing. Along with the pivotability about the longitudinal axis 150, movements of the bearing seat 30 relative to the bolt 15 or the securing elements 31, 32 about three rotational degrees of freedom or pivoting about the three axes 150, 160, 170 are thus possible. As in FIG. 1, the pretensioning element 41 acts in the axial direction along the longitudinal axis 150.
[0050] An adjusting device 60 in the form of an adjusting screw, which acts on the coupling element 43 and via which the pretensioning force of the pretensioning device 41 can be changed, is shown schematically in the right-hand securing element 32. If the adjusting screw 60 is screwed in in the direction of the outer ring 20, the pretensioning increases, and if it is turned in the opposite direction, the pretensioning decreases. The adjusting device 60 can be operated in a controlled manner via at least one sensor and can have an actuator (not shown). If magnetic components are used, the adjusting device 60 can also be designed as a device for changing the magnetic field strength.
[0051] FIG. 5 shows a variant of FIG. 2, in which there are also larger gaps 50 between the securing elements 31, 32 and the bearing seat 30. The two pretensioning elements 41, 42 are supported on opposing securing elements 31, 32 via the respective coupling elements 43, 44 and press the outer ring 20 or the inner ring 10 in opposite directions. As a result, the two bearing rings 10, 20 are braced against each other in the axial direction along the longitudinal axis 150 of the bolt 15. On account of the elasticity of the pretensioning elements 41, 42, rotation about all three pivot axes 150, 160, 170 is also possible.
[0052] FIG. 6 shows a variant of the embodiment according to FIG. 5. The basic set-up with the gaps 50 between the securing elements 31, 32 and the bearing seat 30 is retained. However, the cross-sectional shape of the pretensioning element 42 differs from the embodiment according to FIG. 5. A groove is worked on the one side in the inner ring 10, into which groove an annular projection of the pretensioning element 42 engages. The cross section of the pretensioning element 42 has an approximate inverted U-shape with a shortened right-hand limb which protrudes into the groove of the inner ring 10. The end of the other limb bears on the bolt 15. At the base, which is located at the top in the depiction in FIG. 6 and thus forms the outer circumference of the annular pretensioning element 42, a lateral thickening is formed which bears on the coupling element 44, such that a corresponding pretensioning force can build up away from the coupling element 44 in the direction of the other pretensioning element 41.
[0053] A variant of the embodiment according to FIG. 6 is shown in FIG. 6a. The basic set-up with the gaps 50 between the securing elements 31, 32 and the bearing seat is retained. However, the cross-sectional shape and the arrangement of the pretensioning element 42 differ from the embodiment according to FIG. 6. A groove is worked on the left-hand side in the inner ring 10, into which groove there engage(s) an annular projection or a plurality of radially inwardly pointing projections or tabs of the pretensioning element 41. The pretensioning element 41 is supported in the groove and bears, with a portion located outside of the groove or with a plurality of portions, on the coupling element 43. The pretensioning element 41 presses or pulls against the outer ring 20 and generates an axial pretensioning between inner ring 10 and outer ring 20. A groove can also be provided on both sides of the inner ring 10, such that one side is pressed and the other side is pulled. The advantage of this variant is that the system is designed in one assembly. The pretensioning element 41 can also be fixed on the outer ring 20 in a groove or another fastening device, for example hooked in, clipped in or held in a form-fitting or clamping manner with fastening elements such as clamps, clips, wedges or the like. It can also be fixed by force-fit engagement via magnets. The radially inner region of the pretensioning element 41 is supported, for example, in a groove in the inner ring or on a projection on the inner ring 10, such that a corresponding compressive or tensile force is applied in the axial direction. Here too, it is possible to use a plurality of pretensioning elements, which are arranged on both sides of the outer ring 20 in order to apply corresponding axial forces.
[0054] FIG. 6b shows a variant of FIG. 6a, in which variant, instead of a separate inner ring 10 which is placed on an axle or a bolt 15 and shrunk on, soldered on or welded on or in some other way fastened, the bolt 15 is designed in one piece with the inner ring 10. Such a one-piece design can also be used and formed in all the other embodiments of the bearing arrangement according to the figures and variants described above.
[0055] FIG. 7 shows, in a perspective view, an alternative use of both the bearing arrangement and the orthopedic device 1, namely as an orthosis component. An upper part 2 in the form of a housing for accommodating a linear actuator is arranged pivotably about a joint axis 4 on a lower part 3, which can be fastened to an orthosis rail, for example via a plate 8 articulated thereto. The upper part 2 is also fixed to an orthosis rail. The two orthosis rails (not shown) are then attached to a limb. The orthopedic device 1 thus forms a joint between the two orthosis rails, with the linear actuator 5 being able to be designed as a passive damping device or as an active drive with a motor. The linear actuator 5 has a piston rod 16 on which the bolt 15 is mounted. The inner ring is mounted on the bolt 15 and is supported on the bearing seat 30 via an outer ring 20. Conversely, the upper end of the linear actuator 5 is supported on the upper part 2 via a proximal bearing seat 36.
[0056] The pretensioning element or the pretensioning elements can also be designed as magnetic elements. Magnetic forces that repel or attract each other can be built up between the respective pretensioning element and the associated bearing ring. The pretensioning elements or the bearing rings can be designed as permanent magnets or can have permanent magnets. The respective other component can have oppositely oriented magnetic components or ferromagnetic elements. There is also the possibility of using a combination of elastic elements and magnetic elements, either as oppositely acting pretensioning devices or as mutually complementary and supporting elements of a pretensioning device. Magnetic components make it possible to transmit forces without mechanical wear, which means that maintenance is no longer necessary or that the maintenance intervals can be extended. If electromagnetic components are used, the respective axial pretensioning force can be set and adjusted through appropriate excitation. Wear can be compensated, for example, by increasing the excitation voltage or the current flow in the excitation coil.
