JOINT

Description

[0001] The invention relates to a joint for an orthopaedic device, wherein the joint comprises a first joint part, a second joint part which is pivotably arranged about a pivot axis on the first joint part, and a hydraulic system comprising a first hydraulic chamber with a first fluid line and a second hydraulic chamber with a second fluid line, wherein the two fluid lines are connected to each other, wherein when the first joint part is pivoted relative to the second joint part, hydraulic fluid is directed from one hydraulic chamber to the other hydraulic chamber.

[0002] Such joints have long been known in the art and are used, for example, in orthoses or prostheses. When the two joint components are pivoted relative to each other around the pivot axis, hydraulic fluid is transferred from one hydraulic chamber to the other. This can be done actively by pumping the fluid back and forth between the chambers. InIn this case, the fluid is used to move the joint, i.e., to pivot the two joint components relative to each other. Alternatively or additionally, the pivoting of the two joint components relative to each other can also be achieved in other ways. Regardless of the method, the fluid lines present a flow resistance to the flowing fluid. The magnitude of this flow resistance determines, among other things, how quickly the fluid flows from one chamber to the other and thus how quickly the two joint components are articulated relative to each other for a given force. The flow resistance is therefore a measure of the damping of the joint's movement.

[0003] In many designs, the two hydraulic chambers are located in a single housing, for example, a cylinder, and are separated from each other by a piston that spatially defines the two hydraulic chambers. When the joint is moved, i.e., when the first joint part pivots relative to the second joint part, the piston moves within the cylinder, thus forcing hydraulic fluid out of one of the hydraulic chambers. This fluid then travels through the fluid lines to the other hydraulic chamber.

[0004] If, in this configuration, the piston is guided by a piston rod that extends, for example, only through one of the two hydraulic chambers, the volume available for the hydraulic fluid in the two hydraulic chambers increases or decreases with the movement of the piston and the piston rod attached to it. The volume decreases when the hydraulic chamber in which the piston rod does not extend is reduced in size, and the volume increases when this hydraulic chamber is enlarged by the movement of the piston.

[0005] Since hydraulic fluid is generally incompressible, the volume change associated with joint movement cannot be accommodated by compression or expansion of the fluid. Therefore, a compensating volume is present to absorb excess fluid or supply any missing fluid. Such a compensating volume is also useful in cases where thermal expansion causes the volume of the hydraulic fluid in the system to increase or decrease, and is thus regularly required when the piston rod extends through both hydraulic chambers.

[0006] Such a system is known, for example, from US 11,213,407 B2. It is important that, during joint movement, the compensating volume is connected to the hydraulic chamber and the fluid line with the lower pressure. This prevents the joint movement from causing excessive hydraulic fluid to enter the compensating volume. In the prior art, this is achieved by a rather complex and elaborate arrangement of at least four check valves. Due to its complex design, such a joint is expensive to manufacture and also requires a relatively large amount of space. Other designs use two controllable valves, one of which connects the compensating volume to each of the two fluid lines.However, this requires a relatively high level of control effort, and the number and complexity of the parts required are also high, as, for example, check valves are often needed in addition to the complex controllable valves.

[0007] Another design of a joint for an orthopaedic device, in particular for a knee joint, is known from WO 2018 / 065615 A1. This joint also has a hydraulic system used to adjust resistances opposing movement of the joint. This can be adjusted differently for different directions of movement.

[0008] The invention is therefore based on the objective of further developing a joint according to the preamble of claim one in such a way that it can be manufactured cost-effectively and in a small size.

[0009] The invention solves the stated problem by means of a joint of the type described above, which is characterized in that the fluid lines are connected by a throttle valve and a 3-way valve which act in parallel to each other, wherein the third outlet of the 3-way valve is connected to a compensating volume and the 3-way valve is designed in such a way that it is switched so that hydraulic fluid can flow from the fluid line with the lower pressure into the compensating volume and vice versa.

[0010] Compared to prior art designs, the joint according to the invention requires only a few components to achieve the desired hydraulic effects. The separation of functions makes this design possible. The flow resistance encountered by the hydraulic elements against the flowing fluid is essentially generated by the throttle valve in the joint according to the invention. The connection of the respective fluid line to the compensating volume, on the other hand, is established by a 3-way valve acting in parallel with the throttle valve. By using a single 3-way valve, which is a preferred embodiment, the required number of valves and, in particular, the number of moving or movable parts is significantly reduced.

[0011] The fact that the 3-way valve and the throttle valve act in parallel to each other does not necessarily mean that they are geometrically parallel to each other, or that the flow paths the fluid can take when flowing through the respective valve, or actually takes, must be geometrically parallel to each other. Rather, it is a parallel effect similar to that caused, for example, by parallel circuits known from electrical circuit technology.

[0012] In In a preferred embodiment, the 3-way valve is designed such that it is switched solely by the pressure difference between the two fluid lines. InIn this particularly preferred embodiment, therefore, no electrical control, and in particular no electronic data processing device or electronic sensor, is required to measure the pressure in at least one of the two fluid lines, preferably in both fluid lines, or the pressure difference between the two fluid lines. Rather, the pressure difference itself causes the 3-way valve to switch accordingly.

[0013] Preferably, the 3-way valve has a switching element that is moved by the pressure difference between the two fluid lines such that the connection between the fluid line with the higher pressure and the equalization volume is closed and the connection between the fluid line with the lower pressure and the equalization volume is opened. The switching element particularly preferably comprises a plunger, a ball, or a pin.

[0014] Advantageously, the joint has at least one sensor configured to measure a pressure difference between the two fluid lines, and the joint includes an electrical control unit configured to switch the three-way valve depending on the pressure difference measured by the sensor. This design is more complex in production and construction compared to the previously described design where the switching is performed by the pressure difference itself. However, it has the advantage that even small and minute pressure differences between the two fluid lines can be sufficient to switch the three-way valve. In this design, it is not necessary for the energy and force required to switch the three-way valve to be derived from or supplied by the pressure difference. The electrical control unit preferably includes at least one electronic data processing device.

[0015] Preferably, the joint has two sensors, one of which is configured to measure the pressure in each of the two fluid lines. Each sensor sends its measurement data to the electronic control unit, which is configured to control the 3-way valve based on this data. This can be done, for example, using a table of values ​​stored in an electronic data storage device accessible to the electronic control unit. The electronic control unit is then configured to compare the measurement data from a sensor that measures the pressure difference between the two fluid lines with the stored data and control the 3-way valve accordingly.Alternatively or additionally, the electrical control is set up to calculate a pressure difference from measurement data of two sensors, each containing information about the pressure in one of the two fluid lines, and then to control the 3-way valve on the basis of the pressure difference thus determined.

[0016] Alternatively or additionally, the joint has at least one sensor configured to determine a force and / or a moment acting on at least one of the joint parts and / or a relative angle between the two joint parts. Alternatively or additionally, the joint has at least one inertial sensor configured to determine an absolute angle, position, and / or orientation of one of the joint parts in space. Particularly preferably, the joint has at least two such inertial sensors, at least one of which is configured to determine the corresponding size of the first joint part and at least one of which is configured to determine the corresponding size of the second joint part. Preferably, measurement data from at least one sensor, which is also used to control the at least one throttle valve, is used to control the 3-way valve.

[0017] Preferably, the electrical control system is configured to recognize the current gait phase in which the joint is located from the measurement data of at least one sensor. This is particularly advantageous when the joint is part of an orthotic device for the lower extremity. The joint is then especially preferably used as the knee joint of an orthosis or prosthesis.

[0018] Preferably, the compensation volume is used as an energy storage device. For this purpose, it is advantageous if the 3-way valve is adjustable. Particularly preferably, a mechanical energy storage device, for example an elastic element such as a spring, is tensioned and charged with potential energy when filling the compensation volume.

[0019] Preferably, the joint has an electrical control unit configured to adjust the flow resistance caused by the throttle valve. Particularly preferably, this electrical control unit is also configured to switch the 3-way valve.

[0020] Preferably, the electrical control is configured to adjust the flow resistance through the throttle valve to different levels for different flow directions. This makes it possible to oppose a movement of the joint in a first direction with a different flow resistance and thus dampen this movement differently than the movement of the joint in a second direction, which is opposite to the first.

[0021] Preferably, the throttle valve is arranged such that, when the first joint part is pivoted relative to the second joint part in different pivot directions, it is approached by flow from different directions.

[0022] Preferably, the 3-way valve has a preload element, for example a spring, that preloads the valve into a switching position. InIn the switching position, the connection between the first fluid line and the compensation volume, or between the second fluid line and the compensation volume, is preferably open. Such a preload means that switching the 3-way valve into the switching position requires less force than switching it out of the switching position. This is particularly advantageous when the switching process is triggered by the pressure difference between the two fluid lines, because the preload means that a smaller pressure difference is sufficient to switch the 3-way valve into the switching position than to switch it out of the switching position.

[0023] Alternatively, the 3-way valve is pre-tensioned into a neutral position by at least one pre-tensioning element, in which neither of the two fluid lines is completely closed. Only a pressure difference between the two fluid lines moves the 3-way valve into a switching position. If no pressure difference is present, or if the existing pressure difference is less than a predetermined limit, the 3-way valve remains in the neutral position, and fluid from both hydraulic chambers can flow into or out of the compensation volume through the partially open outlets of the 3-way valve. This is particularly advantageous when volume fluctuations occur in both hydraulic chambers, for example, due to temperature changes.

[0024] With the aid of the accompanying drawings, some exemplary embodiments of the present invention are explained in more detail below. They show: Figure 1 - a schematic representation of a hydraulic system in a first situation, Figure 2 - a representation of the hydraulic system in a second situation, Figure 3 - a schematic representation of a 3-way valve and Figure 4 - a schematic representation of a 3-way valve in a further embodiment.

[0025] Figure 1Figure 1 shows a hydraulic system 2 for an orthotic device according to an embodiment of the present invention. It has a first hydraulic chamber 4 and a second hydraulic chamber 6, which in the illustrated embodiment are arranged in a common housing 8 and separated by a piston 10. The piston 10 is movably arranged within the housing 8. A sealing element 12 is located on the piston, which can, for example, be in the form of a ring made of an elastic material, such as rubber, and seals the first hydraulic chamber 4 and the second hydraulic chamber 6. Two piston rods 14 are located on the piston 10, the first of which, in the illustration, protrudes upwards and the second downwards from the housing 8.If a first joint part (not shown) is moved against a second joint part (also not shown), the piston 10 is also moved relative to the housing 8, thereby increasing the size of one of the two hydraulic chambers 4, 6 and decreasing the size of the other hydraulic chamber 6, 4.

[0026] The first hydraulic chamber 4 has a first fluid line 16. The second hydraulic chamber 6 has a second fluid line 18. The first fluid line 16 and the second fluid line 18 are connected to each other via a throttle valve 20. Additionally, the first fluid line 16 and the second fluid line 18 are connected to each other via a 3-way valve 22. A first outlet 24 of the 3-way valve 22 is connected to the first fluid line 16, and a second outlet 26 is connected to the second fluid line 18. A third outlet 28 of the 3-way valve 22 is connected to a compensating volume 30.

[0027] In Figure 1The figure shows how a force, indicated by the red arrow within the upper piston rod 14, acts on the piston rod 14 and thus on the piston 10. This causes the piston to move downwards, thereby reducing the size of the second hydraulic chamber 6 and enlarging the first hydraulic chamber 4. The hydraulic fluid within the hydraulic system 2 is thus directed from the second hydraulic chamber 6 into the second fluid line 18 and from there through the throttle valve 20 into the first fluid line 16 and the first hydraulic chamber 4. The flow resistance, which is opposed by the throttle valve 20, is adjustable via the throttle valve 20.

[0028] Inside the 3-way valve 22 is a switching element 32, which in the illustrated embodiment is designed as a pin extending from top to bottom with a disc-shaped end at each end. As the piston 10 moves downwards, the pressure increases in the second hydraulic chamber 6 and the second fluid line 18. This pressure also acts on the lower disc-shaped end of the switching element 32, causing it to move upwards. In The movement of the piston 10 creates a vacuum in the first fluid line 16, so that the switching element 32 is moved by the pressure difference between the first fluid line 16 and the second fluid line 18. In Figure 1This closes the second outlet 26 through the lower, disc-shaped end of the switching element 32. Simultaneously, the first outlet 24 opens. Consequently, the hydraulic fluid can flow from the first fluid line 16 through the first outlet 24 of the 3-way valve 22 into the compensation volume 30.

[0029] The compensating volume 30 preferably has an elastic element, for example a spring element, which ensures that fluid from the compensating volume 30 flows through the open first outlet 24 if the pressure in the first fluid line 16 and the first hydraulic chamber 4 is lower than the pressure in the compensating volume 30. In this way, volume fluctuations, for example due to fluid loss or temperature fluctuations, can be compensated for. If the switching element 32 is also pre-tensioned so that it moves to a neutral position in a load-free situation, i.e., without any external force acting on the piston 10, in which neither the first outlet 24 nor the second outlet 26 is completely closed, this volume compensation can also take place through both outlets 24 and 26.

[0030] In Figure 2The reverse situation is shown. The piston 10 is moved upwards by the force now shown by the arrow in the lower piston rod 14. This increases the pressure in the first hydraulic chamber 4 and the adjoining first fluid line 16, and decreases the vacuum in the second hydraulic chamber 6 and the second fluid line 18. Consequently, the hydraulic fluid is directed from the first hydraulic chamber to the second hydraulic chamber through the throttle valve 20. Due to the pressure difference between the first fluid line 16 and the second fluid line 18, the switching element 32 of the 3-way valve 22 is opened. Figure 2 moved downwards. This closes the first outlet 24 of the 3-way valve 22 and opens the second outlet 26. Consequently, in this situation as well, the fluid line with the compensation volume 30, which has the lower pressure, is connected.

[0031] Figure 3This shows a more detailed view of a section of a hydraulic system. The first fluid line 16 and the second fluid line 18 are visible. The 3-way valve 22 is arranged in a recess in a base body. In the lower left of the Figure 3 A sectional view along section line 34 is shown. The switching element 32, which is visible in the main view of the Figure 3 The first output 24 of the 3-way valve 22 closes and the second output 26 opens. In the small-scale view at the bottom left, it can be seen that the switching element 32 is arranged between channels 36, through which a hydraulic fluid entering the 3-way valve 22 via the first output 24 or the second output 26 can flow.

[0032] Figure 4Figure 1 shows another embodiment of the 3-way valve 22. The switching element 32 comprises a switching body 38, which is positioned between two switching levers 40. The pressure difference between the first fluid line 16 and the second fluid line 18 ensures that different forces act on the two switching levers 40, which move the switching body 38. This causes the switching levers 40 to open and close one outlet of the 3-way valve 22 at a time. Reference symbol list

[0033] 2 Hydraulic system 4 First hydraulic chamber 6 Second hydraulic chamber 8 Housing 10 Piston 12 Sealing element 14 Piston rod 16 First fluid line 18 Second fluid line 20 Throttle valve 22 3-way valve 24 First outlet 26 Second outlet 28 Third outlet 30 Compensation volume 32 Switching element 34 Section line 36 Channel 38 Switching body 40 Switching lever

Claims

1. A joint for an orthopedic device, the joint comprising - a first joint part, - a second joint part, which is arranged on the first joint part such that it can be swivelled about a swivel axis, and - a hydraulic system which comprises ∘ a first hydraulic chamber (4) with a first fluid line (16) and ∘ a second hydraulic chamber (6) with a second fluid line (18), the two fluid lines (16,18) being connected to each other, wherein hydraulic fluid is conducted from one hydraulic chamber (4,6) into the other hydraulic chamber (6,4) when the first joint part is swivelled relative to the second joint part, characterized in that the fluid lines (16,18) are connected by a throttle valve (20) and a 3-way valve (22) that act parallel to each other, wherein the third outlet (28) of the 3-way valve (22) is connected to a compensation volume (30) and the 3-way valve (22) is designed in such a way that it is switched so that hydraulic fluid can flow from the fluid line (16,18) with the lower pressure into the compensation volume (30) and vice-versa.

2. The joint according to claim 1, characterized in that the 3-way valve (22) is designed in such a way that it is switched simply by the pressure difference between the two fluid lines (16,18).

3. The joint according to claim 1 or 2, characterized in that the 3-way valve (22) has a switching element (32) that is displaced due to the pressure difference between the two fluid lines (16,18) in such a way that the connection between the fluid line (16,18) with the higher pressure and the compensation volume (30) is closed and the connection between the fluid line (18,16) with the lower pressure and the compensation volume (30) is opened.

4. The joint according to claim 3, characterized in that the switching element (32) comprises a tappet, a ball or a pin.

5. The joint according to one of the preceding claims, characterized in that the joint has at least one sensor that is configured to measure a pressure difference between the two fluid lines (16,18), wherein the joint comprises an electrical control unit that is configured to switch the 3-way valve (22) depending on the pressure difference measured by the sensor.

6. The joint according to one of the preceding claims, characterized in that the joint comprises an electrical control unit that is configured to adjust the flow resistance caused by the throttle valve (20).

7. The joint according to claim 6, characterized in that the electrical control unit is configured to adjust the flow resistance differently for different flow directions through the throttle valve (20).

8. The joint according to claim 6 or 7, characterized in that the throttle valve (20) is arranged in such a way that when the first joint part swivels relative to the second joint part in different directions, the flow is directed towards it from different flow directions.

9. The joint according to one of the preceding claims, characterized in that the 3-way valve (22) comprises a pre-tensioning element, such as a spring, particularly preferably at least one leaf spring and / or at least one spiral spring, which pre-loads the 3-way valve into a switching position.

10. The joint according to one of the preceding claims, characterized (22) in that the 3-way valve (22) comprises a pre-tensioning element, such as a spring, particularly preferably at least one leaf spring and / or at least one spiral spring, which pre-loads the 3-way valve (22) into a neutral position in which neither the first outlet (24) nor the second outlet (26) is completely closed.