Abstract
The invention relates to a joint for an orthopedic device. The joint has a first joint part (38), a second joint part (34), which is pivotally arranged on the first joint part (38) about a pivot axis (36) in a pivoting region, and a hydraulic system with at least one first cylinder (2), which has a first longitudinal axis and is arranged in the second joint part (34), and a first piston (20) which is positioned in the cylinder (2), wherein the first piston (20) is arranged on a first securing point (64) of the first joint part (38) such that the first piston (20) carries out a movement along the first longitudinal axis of the first cylinder (2) and a tilting movement when the first joint part (38) is pivoted relative to the second joint part (34).
Claims
1. A joint for an orthopedic device, comprising: a first joint part; a second joint part arranged on the first joint part such that one or more of the first joint part and the second joint part is swivelable about a swivel axis in a swivel range; a hydraulic system comprising at least a first cylinder which comprises a first longitudinal axis, wherein the at least a first cylinder is arranged in the second joint part, and a first piston is positioned in the at least a first cylinder, wherein the first piston is arranged at a first securing point of the first joint part such that the first piston is configured to perform a movement along the first longitudinal axis of the at least a first cylinder and a tilting movement upon a relative swivelling movement between the first joint part and the second joint part.
2. The joint according to claim 1, wherein the at least a first cylinder is arranged such that a path of the first securing point intersects the first longitudinal axis twice upon a relative swivelling movement between when the first joint part and the second joint part.
3. The joint according to claim 1 wherein the first piston is directly attached at the first securing point of the first joint part.
4. The joint according to claim 1 wherein the hydraulic system further comprises a second cylinder arranged in the second joint part, and a second piston positioned in the second cylinder, wherein the second piston is arranged at a second securing point of the first joint part, wherein the second cylinder comprises a second longitudinal axis, wherein the second cylinder is arranged such that a path of the second securing point intersects the second longitudinal axis twice upon a relative swivelling movement between when the first joint part and the second joint part.
5. The joint according to claim 4 wherein the swivel range is delimited by a first limit angle and a second limit angle, wherein a distance between the first securing point of the first piston or a distance between the second securing point of the second piston and the longitudinal axis of the respective first or second cylinder is the same at both limit angles.
6. The joint according to claim 5, wherein the distance between the first securing point of the first piston or the distance between the second securing point of the second piston and the longitudinal axis of the respective first or second cylinder in a center of the swivel range is exactly the same as at both limit angles.
7. The joint according to claim 4 wherein at least one piston of the first piston and the second piston is arranged on the first joint part such that it is swivelable about a piston axis.
8. The joint according to claim 1 wherein the hydraulic system comprises at least one equalizing volume.
9. The joint according to claim 1 further comprising at least one sealing element is arranged on the first piston and/or the first cylinder, said at least one sealing element sealing a gap between the first piston and the first cylinder.
10. The joint according to claim 9 wherein the at least one sealing element is arranged in a groove.
11. The joint according to claim 9 wherein the at least one sealing element comprises a sealing lip.
12. The joint according to claim 8 wherein the at least one equalizing volume is pre-tensioned.
13. The joint according to claim 8 wherein the at least one equalizing volume is spring loaded.
14. The joint according to claim 10, wherein the at least one sealing element is mounted on an elastic bearing element which is arranged at a base of the groove.
Description
[0055] In the following, embodiment examples of the invention will be explained in more detail with the aid of the accompanying drawings. They show:
[0056] FIG. 1a schematic circuit diagram of a hydraulic system,
[0057] FIGS. 2 to 5schematic representations of joints,
[0058] FIG. 6a schematic representation of a prosthetic foot,
[0059] FIG. 7a schematic top view in a sectional representation,
[0060] FIGS. 8 and 9schematic representations of a prosthetic foot according to a further embodiment example of the present invention in two different positions,
[0061] FIG. 10the prosthetic foot from FIG. 6 in a second position,
[0062] FIG. 11a different schematic circuit diagram,
[0063] FIGS. 12 to 17top views of schematic sectional representations of various embodiments,
[0064] FIG. 18the schematic representation of a prosthetic foot with a rotary hydraulic system,
[0065] FIG. 19a schematic circuit diagram of a further hydraulic system,
[0066] FIG. 20a schematic representation of a prosthetic foot with a joint according to an embodiment example of the present invention,
[0067] FIGS. 21 and 22detailed views of various sealing elements,
[0068] FIG. 23schematic views of a joint in various swivel positions and
[0069] FIG. 24a schematic representation of a further embodiment.
[0070] FIG. 1 shows the schematic representation of a circuit diagram for a hydraulic system of a joint. A main piston 4 is arranged in a cylinder 2, wherein the former can be displaced left and right in the representation shown. It is connected to two piston rods 6 that guide its movement. A first hydraulic chamber 8 and a second hydraulic chamber 10, which are separated from each other by the main piston 4, are located in the cylinder 2. A fluid connection 12 connects the first hydraulic chamber 8 to the second hydraulic chamber 10, a valve 14 being located in the fluid connection 12 that can be opened and closed, meaning that the fluid connection 12 can also be opened and closed. If the fluid connection 12 is opened, hydraulic fluid can flow from the first hydraulic chamber 8 into the second hydraulic chamber 10 and vice versa when the main piston 4 moves. The damping of this movement of the main piston 4 can be adjusted via a potentially adjustable flow resistance caused by the valve 14. If the fluid connection 12 is closed, however, the hydraulic fluid cannot flow through the fluid connection 12.
[0071] In addition, the hydraulic system has a further fluid line 16. It comprises multiple elements. It has a volume 18 in which a piston 20 is moveably arranged. This piston 20 can also be moved left and right in the embodiment example shown. However, in this embodiment it does not have a piston rod, but is designed as a flying piston. This is advantageous, but not essential. The piston 20 may also be configured with a piston rod. The piston 20 divides the volume 18 into a first part, which is to the left of the piston 20 in the embodiment example shown, and a second part, which is to the right of the piston 20 in the embodiment example shown. The first part of the volume is connected to the first hydraulic chamber 8 via a first partial line 24. The second part of the volume is connected to the second hydraulic chamber 10 via a second partial line 26. A valve arrangement 28 is located in the second partial line, said arrangement comprising a combination of throttle valve 30 and non-return valve 32. This allows a flow resistance against the fluid flowing through the valve arrangement 28 to be adjusted in a flow direction.
[0072] FIG. 2 depicts a joint according to an embodiment example of the present invention as part of a schematically illustrated knee prosthesis. The main piston 4 is arranged with its piston rod 6 on the second joint part 34, which is arranged on a first joint part 38 such that it can be swivelled about a swivel axis 36. In the representation shown, the piston 20 is located at the lower end stop 22 and can therefore only be moved in one direction, upwards in FIG. 2. This occurs when the main piston 4 is moved downwards and fluid moves from the first hydraulic chamber 8 through the first partial line 24 and into the volume 18. This enables a flexing of the joint in the stance phase, for example, which makes walking with the prosthesis more gentle for the wearer and the gait pattern more natural.
[0073] FIG. 3 shows a similar embodiment. Here, the piston rod 6 is also coupled with the second joint part 34 of the knee joint, which in turn is connected to the first joint part 38 about the swivel axis 36. However, unlike in FIG. 2 the volume 18 and the entire fluid line 16 is now located within the main piston 4, wherein the fluid line 16 is only schematically depicted for the sake of clarity.
[0074] FIGS. 4 and 5 show the identical embodiment. The main piston 4 is in the cylinder 2 and is fixed with the piston rod 6 to the second joint part 34. Unlike in the embodiments in FIGS. 2 and 3, there is a spring element 40 in the volume 18. Said spring element pushes the piston 20 into the rest position at the end stop 22 shown in FIG. 4. Therefore, if the piston 20 is to be moved into its predetermined rest position, it is sufficient to not apply a torque to the first joint part 38 and/or the second joint part 34. The spring element 40 pushes the piston 20 into the rest position. If the second joint part 34 is now swivelled relative to the first joint part 38 about the swivel axis 36, the main piston 4 in the cylinder 2 is moved downwards and pushes fluid through the first partial line 24 into the volume 18, thus moving the piston 20 upwards against the force applied by the spring element 40. This situation is shown in FIG. 5 and denotes flexing in the stance phase.
[0075] The connection between the hydraulic chamber and the volume 18 can be closed by way of the valve 14. This renders the movement of the piston 20 impossible.
[0076] FIG. 6 depicts a further embodiment example of the present invention as an ankle joint. The first joint part 38 is the prosthetic foot, which is arranged on the second joint part 34 such that it can be swivelled. In the embodiment example shown, the second joint part 34 is configured to be connected to a lower leg element. The piston 4 is designed in the form of two main pistons 4, which form swivel pistons and are each arranged on the second joint part 34 such that they can be swivelled. In each case, the first hydraulic chamber 8 and the second hydraulic chamber 10 are located below the main piston 4. Between the two hydraulic chambers 8, 10 is the fluid line 16, which connects the two hydraulic chambers 8, 10 and in which the volume 18 with the moveable piston 20 is located. In the position depicted in FIG. 6, the moveable piston 20 is positioned at one of its end stops 22, so that a movement of the moveable piston 20 within the volume 18 is only possible in one direction. In FIG. 6 this is a plantar flexion, i.e. a downward movement.
[0077] FIG. 7 shows a schematic sectional representation of a top view of the embodiment in FIG. 6. The first hydraulic chamber 8 and the second hydraulic chamber 10 are connected to each other via the fluid connection 12. The valve 14 is designed as a valve arrangement and has two non-return valves 42, each of which can open or close the connection to one of the two hydraulic chambers 8, 10. The arrangement also has a push button 44, which is designed in such a way that, if it is pressed in, i.e. moved upwards in FIG. 7, it actuates the two levers 46 and thus opens the two non-return valves 42. The first partial line 24 is connected to the first hydraulic chamber 8 by a throttle valve 30. A disk spring 50 is depicted at the upper end stop 22, by means of which the end stop 22 is damped. The preload of said disk spring 50 can be adjusted via the adjustable driver 52. The embodiment example shown also depicts a relief valve 54 as well as an opening mechanism 56, by means of which the fluid connection 12 can be opened.
[0078] The fluid line 16, composed of multiple partial lines and the volume 18 in the embodiment example shown, is also located between the two hydraulic chambers 8, 10. The piston 20 is located in said volume, the former being pre-tensioned upwards by the spring element 40 in FIG. 7. The spring element 40 is configured to move the piston 20 into its rest position when no other external forces beyond the force of gravity are acting. If the fluid connection 12 is closed, as shown in FIG. 7, a movement of the joint can be achieved by slightly opening the adjustment valve 48. As a result, fluid can flow from the second hydraulic chamber 10 into the volume 18, for example during a heel strike, when increased pressure builds up in the second hydraulic chamber 10, causing the piston 20 to move downwards against the spring force of the spring element 40. A corresponding quantity of fluid flows from the partial volume below the piston 20 into the first hydraulic chamber 8, so that the second joint part 34 moves relative to the first joint part 38.
[0079] FIGS. 8 and 9 depict a prosthetic foot similar to the one in FIG. 6. The main difference is that the two hydraulic chambers 8, 10 are separated by a single main piston 4, which is likewise designed as a swivel piston. The two hydraulic chambers 8, 10 are again connected by the fluid line 16 in which the volume 18 with the moveable cylinder 20 is located. As in FIG. 6, the moveable piston 20 is resting against one of its end stops 22 and can therefore only be moved in one direction, downwards in FIG. 8. This position of the moveable piston 30 is preferably assumed when the heel height of the prosthetic foot is determined: in the present embodiment example, essentially the position of the main piston 4 between the hydraulic chambers 8, 10. Once this has happened, the fluid connection 12, which is not shown in FIGS. 6, 8, 9 and 10 and is preferably opened to adjust the heel height, is preferably closed. It is then no longer possible for the fluid to flow from the one hydraulic chamber 8, 10, through the fluid connection 12 and into the respective other hydraulic chamber 10, 8.
[0080] FIG. 9 illustrates this situation. Although the fluid connection 12 is closed, the angle between the first joint part 38 and the second joint part 34 has changed compared to the situation in FIG. 8, wherein the main piston 4 has been displaced. As a result, fluid has been displaced from the second hydraulic chamber 10 into the volume 18. In FIG. 9, said fluid is situated above the moveable piston 20 and has moved it downwards. In addition, fluid situated below the moveable piston 20 in FIG. 8 has moved from the volume into the first hydraulic chamber 8.
[0081] FIG. 10 shows the situation from FIG. 9 with a prosthetic foot from FIG. 6. The moveable piston 20 moved away from its end stop 22 as the angle between the first joint part 38 and the second joint part 34 changed.
[0082] FIG. 11 corresponds to the representation from FIG. 1. The difference, however, is that the first hydraulic chamber 8 and the second hydraulic chamber 10, which are separated from each other by the main piston 4, are no longer connected by one fluid connection 12, but by two fluid connections 12. In both fluid connections 12 there is a valve 14 as well as a throttle valve 30. The valves 14 and/or the throttle valve 30 may be designed differently so as to achieve, for example, different flow resistances for different flow directions of the fluid.
[0083] The representations in FIGS. 12 to 17 correspond to the representation in FIG. 7. To avoid repetitions, only the differences shall discussed. Compared to FIG. 7, in FIG. 12 there is a valve arrangement containing two non-return valves 32 in the first partial line 24, which connects the first hydraulic chamber 8 to the volume 18 via the throttle valve 30. Said non-return valves act in different directions, wherein the upper of the two non-return valves 32 in FIG. 12 is spring-loaded. The fluid that flows through this first partial line 24 must pass through the throttle valve 30 regardless of the flow direction.
[0084] This is different in FIGS. 13 and 14, each of which depicts a section from a corresponding representation. Again, one of the non-return valves 32 is positioned in the first partial line 24. In the embodiment example shown, this is the spring-loaded non-return valve, which allows fluid to flow from the first hydraulic chamber 8, through the throttle valve 30, through the first partial line 24 and into the volume 18 when the pressure is correspondingly high. Fluid cannot pass through this non-return valve 32 in the opposite direction; rather it passes through the non-spring-loaded non-return valve 32. However, the latter is not arranged in a by-pass in the embodiment example shown, such that the fluid does not have to pass through the throttle valve 30 in this direction.
[0085] FIG. 14 illustrates the reversed situation. The non-spring-loaded non-return valve 32, which allows a flow from the volume 18 towards the height of the first hydraulic chamber 8, is positioned in the first partial line 24 in such a way that the fluid flowing through this partial line 24 in this direction passes through the throttle valve 30. The non-return valve 32 acting in the opposite direction, which is spring-loaded, is arranged in the by-pass, so that fluid taking this path does not pass through the throttle valve 30. The skillful selection of the throttle valve and spring of the spring-loaded non-return valve 32 renders it possible to simply and individually adjust the flow resistance for different flow directions.
[0086] FIGS. 15 and 17 depict a different embodiment of the present invention. The volume 18 is no longer divided into the two partial volumes by the piston 20, but by a membrane 58. This does not change how it works. Fluid from the first hydraulic chamber 8 can still get into volume 18 below the membrane 58 through the first partial line 24. Fluid from the second hydraulic chamber 10 can get into the second partial volume above the membrane 58 via the second partial line 26. The membrane 58 is designed to be elastic and can thus assume different positions, depending on the prevailing pressure conditions.
[0087] FIGS. 16 and 17 show modified embodiments, each of which however is equipped with the membrane 58. While FIG. 16 only differs from FIG. 15 in that the geometric shape of the volume 18 has been modified, FIG. 17 shows additional spring elements 40. The membrane 58 is preferably designed to be flexible and elastic so that it can rest against the wall delimiting the volume 18 on at least one side. Said wall then acts as an end stop 22 and thus delimits the maximum effective range of the membrane 58. While in this case the end stop 22 in FIG. 16 is designed to be undamped, the embodiment in FIG. 17 is damped by way of the spring elements 40. The membrane 58 initially rests against the lower end of the spring elements 40 in FIG. 17. If further fluid is directed into the first partial volume, shown below the membrane 58 in FIG. 17, the pressure in this area increases, causing the membrane to compress the spring elements, thus enabling a further movement.
[0088] FIG. 18 schematically depicts a prosthetic foot with the first joint part 38 and the second joint part 34. The first hydraulic chamber 8 and the second hydraulic chamber 10 are each composed of two parts, which in each case are connected to each other. The prosthetic foot in FIG. 15 has a rotary hydraulic system. The main piston 4 also comprises two parts which are connected to each other in a torque-proof manner. If the joint is moved, the two joint parts 34, 38 are swivelled against each other and the main piston 4 is moved relative to the hydraulic chambers. The parts of the hydraulic chambers 8, 10 upstream of the main piston 4 in the direction of rotation are rendered smaller and the parts of the hydraulic chambers 8, 10 downstream of the main piston 4 in the direction of rotation are enlarged. In FIG. 18, the piston 20 is arranged in the volume 18 between the two parts of the main piston 4 in the area of the axis of rotation of the joint.
[0089] FIG. 19 schematically depicts a diagram of a further hydraulic system for a joint for an orthopedic device according to a further embodiment example of the present invention. The main piston 4, which has two piston rods 6 in the embodiment example shown, separates the first hydraulic chamber 8 from the second hydraulic chamber 10. The two hydraulic chambers 8, 10 are connected by the fluid connection 12 where the valve 14 is located. In the embodiment example shown, the volume 18 is composed of two volumes 18. In the first volume is a first displaceable separating device 60 and in the second volume is a second displaceable separating device 62.
[0090] If the main piston 4 is displaced to the right in the representation shown, the first hydraulic chamber 8 becomes smaller and part of the fluid contained within is directed through the first partial line 24. The first separating device 60 is displaced to the right as a result. Part of the fluid situated to the right of the first separating device 60 within the corresponding volume 18 is displaced through the second partial line 26 into the second hydraulic chamber 10. Conversely, if the main piston 4 is displaced to the left, the second hydraulic chamber 10 becomes smaller and part of the fluid contained within is directed through the second partial line 26. As a result, the second displaceable separating device 62 is displaced to the right and part of the fluid there is pumped through the first partial line 24 into the first hydraulic chamber 8. The respective flow resistance can be set individually for both directions using the combinations of non-return and throttle valve upstream of the two volumes 18 and the spring elements contained in the volumes 18.
[0091] FIG. 20 depicts a prosthetic foot in a schematic sectional view. Spring elements that determine the rolling behavior and elasticity of the foot are depicted schematically only. One recognizes the first joint part 38 in which two cylinders 2 are arranged. The second joint part 34 is arranged thereon such that it can be moved about the swivel axis 36. Two pistons 20 are arranged on the second joint part 34 such that they can be swivelled. If the second joint part 43 is now moved relative to the first joint part 38 about the swivel axis 36, the two pistons 20 in the two cylinders 2 are moved up and down. Given that the securing point 64, at which the respective piston 20 is arranged on the first joint part 38, performs a swivel movement about the swivel axis 36 with the first joint part 38, but the piston 20 can only perform a linear movement in the respective cylinder 2, the pistons 20 are tilted about the securing point 64.
[0092] The two pistons 20, of which FIGS. 21 and 22 each depict an enlarged section, each comprise a sealing element 66 that is arranged in a groove 68 provided for this purpose. In FIG. 21, the groove 68 is depicted without a sealing element 66 within it. Instead, a schematically depicted bearing material 70 is located at the base of the groove 68, wherein said bearing material is elastic, thereby enhancing the elastic properties of a sealing element 66 inserted into the groove 68 that is partially filled with the bearing material 70. In FIG. 22, the sealing element 66 is inserted into the groove 68. It has a sealing lip that projects radially outwards from the piston 20, the former sealing the sealing gap between the piston 20 and the cylinder 2.
[0093] FIG. 23 shows a joint in three different swivel positions. In the upper representation, the second joint part 34 is in a neutral middle position relative to the first joint part 38. The two securing points 64, at each of which one of the pistons 20 is arranged on the second joint part 34, move on a circular path, depicted by the dashed circular line, when the two joint parts 38, 34 swivel relative to each other. This is the path of the securing points 64 when the two joint parts 38, 34 swivel in relation to each other. Conversely, the pistons 20 move in a straight line, which is depicted by the dotted line. This is the longitudinal axis of the cylinder 2. In the upper representation, the securing points 64 lie on both the circular line and the dotted lines, so that the pistons 20 are not tilted. The sealing line, along which the sealing element seals the hydraulic chambers delimited by the respective piston 20, is therefore a circle.
[0094] The middle and lower representations in FIG. 23 depict the second joint part 34 swivelled relative to the first joint part 38. In the middle representation in FIG. 23, the swivelling happens in an anti-clockwise direction. The piston 20 shown on the left has therefore been displaced downwards and the piston 20 on the right upwards. In both representations, the securing points 64 still lie on the dashed circular line as it illustrates the movement of the securing points 64. However, they no longer lie on the vertical dotted lines, which illustrate the movement of the pistons 20. The lower representation in FIG. 23 shows the reverse situation. The two joint parts 38, 34 have been swivelled relative to each other in the clockwise directions so that, in this case, the piston on the left has been displaced upwards and the piston on the right downwards. In these positions of the joint, the sealing line is an ellipsis.
[0095] In the neutral position in the upper representation in FIG. 23, the vertical dashed lines extend through the two securing points 64. If the second joint part 34 is swivelled out of this position, both securing points 64 lie between the two dotted lines, so that the respective piston 20 is tilted towards to swivel axis 36. For the piston 20 shown on the left, this means tilting in the clockwise direction. For the piston 20 shown on the right, this means tilting in the anti-clockwise direction.
[0096] This only constitutes a possible, albeit very advantageous, embodiment. In a different embodiment, the securing points 64 do not lie on the dashed circular line when in a neutral position, but within the circular line. This means that the pistons 20 assume a tilted position in the neutral position of the joint. Tilting then occurs away from the swivel axis 36. In this embodiment, if the second joint part 34 and the first joint part 38 are swivelled relative to each other, the securing points 64 move until they lie on the dashed lines. The pistons 20 are then no longer tilted and the sealing line is a circle. If the joint is swivelled further in the same direction, the securing points move and lie between the two dotted lines. The pistons 20 are then tilted towards the swivel axis 36.
[0097] FIG. 24 shows an embodiment similar to the representation in FIG. 10. The main difference is that the two main pistons 4 are not arranged on the upper joint element, but the lower joint element.
REFERENCE LIST
[0098] 2 cylinder [0099] 4 main piston [0100] 6 piston rod [0101] 8 first hydraulic chamber [0102] 10 second hydraulic chamber [0103] 12 fluid connection [0104] 14 valve [0105] 16 fluid line [0106] 18 volume [0107] 20 piston [0108] 22 end stop [0109] 24 first partial line [0110] 26 second partial line [0111] 28 valve arrangement [0112] 30 throttle valve [0113] 32 non-return valve [0114] 34 second joint part [0115] 36 swivel axis [0116] 38 first joint part [0117] 40 spring element [0118] 42 non-return valve [0119] 44 push button [0120] 46 lever [0121] 48 adjustment valve [0122] 50 disc spring [0123] 52 driver [0124] 54 relief valve [0125] 56 opening mechanism [0126] 58 membrane [0127] 60 first separating device [0128] 62 second separating device [0129] 64 securing point [0130] 66 sealing element [0131] 68 groove [0132] 70 bearing material
