Orthopedic device and energy storage device

Description

[0001] The invention relates to an energy storage device according to claim 1.

[0002] Orthopaedic devices are known in many forms from the prior art. These include, for example, prostheses, in particular knee prostheses, ankle prostheses, foot prostheses, elbow prostheses, and hand prostheses. Orthopaedic devices also include orthoses, in particular knee orthoses, ankle orthoses, foot orthoses, elbow orthoses, and hand orthoses. For example, WO 2018 / 161023 A1 discloses a prosthetic knee joint that incorporates a hydraulic system with a reservoir.

[0003] Exoskeletons that are attached externally to a part or all of the wearer's body and are intended to enable movements and / or activities that the body can no longer perform on its own are also orthopaedic devices within the meaning of this invention. This includes devices that make it easier for the wearer to perform strenuous, demanding, or tiring activities, such as overhead work, more effectively, easily, quickly, and for longer periods.

[0004] Many of these orthotic devices have joints designed to replace, support, or protect the wearer's missing joints. In many cases, it is desirable and advantageous for the orthotic device to absorb energy during movement, for example, of one of its joints, store this energy, and release it later, such as during a gait cycle. This is desirable, for example, in knee prostheses and knee braces, where energy is preferably stored in an energy storage device when the knee is bent and then released again when the knee is straightened.

[0005] Several energy storage devices are known in the art, typically designed as spring elements, for example, hydraulic or mechanical spring elements. When the joint is bent, the spring element is compressed and charged with energy. This energy is then released by the spring element at a later time. A disadvantage, however, is that this energy release occurs immediately after the force responsible for the energy charge ceases and is uncontrolled and instantaneous. Intermediate energy storage or a more controlled release of the stored energy is not possible, or hardly possible, with such simple systems.

[0006] Damping elements or resistances are known in the art that make movement, for example of a joint in an orthotic device, more difficult or slower. This is the case, for example, in hydraulic systems where a fluid is moved between two cylinder chambers as the working medium when the piston of the hydraulic device is moved. If a throttle valve is located in the fluid line between the two cylinder chambers, the flow resistance opposing the flowing fluid can be adjusted with this throttle valve. If the valve is completely closed, no fluid can flow and the joint of the orthotic device is blocked.

[0007] However, a disadvantage is that energy cannot be stored with such systems, so only passive resistance is achieved.

[0008] If both effects—energy storage and controlled release—are to be achieved simultaneously, the two system types are generally combined. For example, corresponding systems are known from US 9,416,838 B2 and WO 2016 / 171548. However, since these are actually combinations of two systems, the energy storage devices are structurally complex and therefore prone to failure and expensive.

[0009] Furthermore, with all these systems it is hardly possible to allow free movement of the joint of the orthotic device.

[0010] The invention is therefore based on the objective of further developing an energy storage device in such a way that it can be used flexibly, saved space and manufactured in a simpler manner.

[0011] The invention solves the stated problem by means of an energy storage device according to the preamble of claim 1, which is characterized in that the energy storage device has at least one compensating volume which is fluidically connected to the fluid line by a fluid connection, and at least one first controllable valve by which the fluid connection can be opened and closed.

[0012] If the fluid connection is closed by the first controllable valve, no fluid exchange can take place between the compensation volume and the other components, in particular the first cylinder chamber or the second cylinder chamber. If the piston is moved in this state, the working fluid is forced from one of the two cylinder chambers through the fluid line into the other cylinder chamber. The flow resistance caused by the fluid line opposes the working fluid, resulting in damping that varies depending on the magnitude of the flow resistance.

[0013] In a preferred embodiment, when the piston is moved within the cylinder with the first controllable valve closed, the total volume available for the working medium, i.e. the liquid, changes.

[0014] Conventionally, for example, the piston is attached to a piston rod and is moved along this rod within the cylinder. This means that the volume of the cylinder chamber containing the piston rod is reduced by the piston rod. Consequently, if the piston moves so that a larger section of the piston rod is located within the respective cylinder chamber, the total volume available for the working fluid is reduced, thus increasing the pressure. Depending on the compressibility of the working fluid, movement can be at least almost, and preferably even completely, prevented in this way, for example, if the fluid constituting the working medium is incompressible. If the working fluid is not completely incompressible, then the resistance to the piston's movement increases with increasing displacement.The working fluid within the cylinder chambers and the fluid line is compressed in this way and thus serves as an energy storage medium. Within the scope of the present invention, a working fluid is preferably considered completely incompressible if the forces occurring during the intended use of the orthopaedic device do not lead to a displacement of the piston when the fluid connection is closed.

[0015] In this configuration, the energy storage device acts as a spring element when the first controllable valve is closed. The spring constant depends primarily on the compression modulus of the working fluid. When the system is loaded, for example, when the piston is subjected to a force acting towards the first cylinder chamber, the piston is displaced in this direction. In this embodiment, this increases the portion of the piston rod located inside the cylinder, thus reducing the volume available for the working fluid, as explained above. This increases the pressure on the working fluid, and the piston's displacement ceases when the pressure of the working fluid compensates for the external force applied to the piston.

[0016] The magnitude of the spring travel, i.e., the displacement of the piston, for a given external force depends on the change in volume relative to the total volume available to the working fluid. This volume change depends on the diameter of the piston rod that causes the change in volume. The smaller the diameter of the piston rod, the lower the spring stiffness and the greater the spring travel. To obtain a soft spring, it is therefore advantageous to use a particularly thin piston rod with a small diameter. However, below a critical diameter, this compromises the mechanical stability of the piston rod. The spring constant preferably also depends on the volume of the first cylinder chamber and the volume of the second cylinder chamber. The spring constant can also be expressed as dependent on the ratio of the two volumes.Therefore, for a given piston rod diameter, the spring constant can be reduced, i.e., the spring travel increased for a given force, by increasing the total volume available to the working fluid. However, this usually results in a larger energy storage device, requiring more installation space.

[0017] In a preferred embodiment, the piston rod therefore extends into, and particularly preferably through, both cylinder chambers, but has different diameters or cross-sectional areas in the two cylinder chambers. Only the difference then contributes to the volume change, so that even small volume changes and thus soft springs can be achieved.

[0018] For example, a piston rod has a diameter of less than 10 mm, preferably less than 7 mm.

[0019] Preferably, one wall of the cylinder is designed to serve as a mechanical energy storage medium. This can be achieved, for example, by a section with a very thin wall that deforms elastically under the influence of appropriate pressures.

[0020] Energy storage can be prevented by using the first controllable valve to open the fluid connection between the compensating volume and the other components of the hydraulic system. In this case, although the total volume of the two cylinder chambers still changes as the piston moves within the cylinder, this change can be compensated for by the compensating volume, so no compression of the working fluid occurs and therefore no energy is stored. Damping of the piston's movement still occurs, as the flow resistance of the fluid line still impedes the transport of the working fluid. If the total volume available within the two cylinder chambers decreases as the piston moves within the cylinder, some of the working fluid is forced through the fluid line and the fluid connection into the compensating volume.During the piston's reverse movement within the cylinder, the working fluid is drawn back out of the compensation volume, restoring the original state. In this way, the energy storage device can be used as a damping energy storage device, or it can allow the piston to move without intermediate energy storage.

[0021] If the first controllable valve is open and the compensation volume is therefore not separated from the rest of the system, temperature compensation can also occur. In this case, changes in the volume of the working medium due to temperature changes are compensated for by the compensation volume. This prevents the spring properties from changing with temperature.

[0022] In a preferred embodiment of the invention, the working medium is a compressible liquid, preferably an oil, and particularly preferably a silicone oil. It is also advantageous that the stored energy, which is stored when the liquid is compressed, is almost completely released again when the pressure is released, and that the oil, due to its fluidity, which allows it to be used in a form-filling manner, can be used in a very space-saving manner and can withstand high forces.

[0023] Such a working medium blurs the lines between a hydraulic system, which uses a liquid as the working medium (generally considered incompressible), and a pneumatic system, which uses a gas as the working medium (which is usually compressible).

[0024] In orthopaedic devices of the prior art, the compressibility of the fluids is not utilized in the hydraulic systems. Instead, working fluids that are considered incompressible are generally used and treated as such. Typically, such hydraulic systems incorporate controllable valves between the two cylinder chambers to dampen and control the movement. Additionally, a permanently engaged compensating volume may be present.

[0025] Particularly when using knee joints, the forces involved generate high pressures of up to 200 bar, which act on the working fluid of the knee joint's hydraulic assembly. With typical volumes of 25 ml of hydraulic oil, a piston diameter of 25 mm, and a piston rod diameter of 10 mm, this means that with conventional hydraulic oil and closed valves, the maximum piston stroke is only approximately 0.4 mm. This is insufficient to produce a noticeable spring effect or to store a relevant amount of energy via a usable piston stroke. For the purposes of the present invention, such hydraulic oil is considered completely incompressible in this hydraulic assembly. Therefore, closing the valves in this case corresponds to a completely locked joint without any energy storage function. Conversely, opening the valves in this case corresponds to a completely free joint without any energy storage function.Damping can be controlled via the valve position; therefore, a controllable valve in front of the compensation volume is neither necessary nor present.

[0026] In contrast, the device according to the invention utilizes the compressibility of the liquid for energy storage. For this purpose, the ratio between the liquid's compression modulus, the piston rod diameter, and the volume of the cylinder chambers is selected such that the desired energy can be stored without generating excessively high pressures or resulting in an insufficient piston stroke.

[0027] One typical requirement for a knee joint is to store enough energy to assist the user when standing up. The compensating volume must therefore have a controllable valve to switch between energy storage and damping functions. When the compensating volume is engaged, the hydraulics behave as described above; locking and damping are possible via at least one controllable valve in the fluid line. When the fluid connection is closed, the compensating volume is fluidically decoupled from the rest of the system. If any valves in the fluid line are opened, or if no such valve is present, energy can be stored in the system, but free movement is no longer possible.

[0028] Preferably, the fluid used as the working medium has a compression modulus of less than 1.5 GPa, particularly preferably less than 1.2 GPa. This makes it possible to select the other parameters, in particular pressure, volume of the respective cylinder chambers, and piston rod diameter, within a technically simpler range and, in particular, to build the device smaller, for example, to sizes acceptable for orthopedic devices. In the knee joint mentioned above as an example, with conventional hydraulics and 25 ml of working medium, a longer piston stroke can be achieved at the same maximum pressure of 200 bar, for example, by using silicone oil with a compression modulus of 1.5 GPa instead of conventional hydraulic oil and reducing the diameter of the piston rod to 6 mm.With the fluid connection closed (i.e., the compensation volume decoupled) and the second controllable valves open, this results in a piston stroke of 7 mm up to the maximum pressure of 200 bar. Using a working fluid with a compression modulus of 1 GPa, a stroke of 10.5 mm is even achievable.

[0029] Different spring constants, and thus stiffnesses, can be set by selecting the piston rod diameter, cylinder chamber volume, and compression modulus. Preferably, a natural knee stiffness is replicated during the stance phase of the gait cycle, which corresponds to a linear spring constant in the range between 0 N / mm and 750 N / mm. A spring constant of less than 600 N / mm, more preferably less than 400 N / mm, and more preferably greater than 100 N / mm, and more preferably greater than 300 N / mm, is preferred. With an exemplary spring constant of 400 N / mm, a force of 4320 N acts at a bending angle of 25°. In this state, a potential energy of approximately 23 joules is stored. Furthermore, a displacement of 10.8 mm is achieved with the compensating volume completely decoupled under this force.

[0030] Preferably, the working medium is a magnetorheological fluid. These fluids have a viscosity or flowability that can be influenced by the action of magnetic fields. In these configurations, throttle valves and / or controllable valves can be designed as magnets, for example, electromagnets. This eliminates the need for expensive and complex mechanical components, such as those required for conventional mechanical valves. A line through which the working medium flows, for example, the fluid line, is arranged so that a magnetic field from a magnet can act upon it. If the magnetic field is increased, the flowability of the working medium, which is designed as a magnetorheological fluid, decreases. This increases the flow resistance. Conversely, the flow resistance is reduced by weakening the magnetic field, as this increases the flowability of such a working medium.

[0031] Preferably, at least one second controllable valve is located in the fluid line connecting the two cylinder chambers, allowing the flow resistance of the fluid connection to be adjusted, preferably continuously. The fluid connection can preferably be completely closed by the second controllable valve. Preferably, the second controllable valve is a throttle valve. Alternatively, an additional throttle valve is provided to adjust the flow resistance. This allows for damping of the piston's movement within the cylinder.

[0032] Particularly preferably, at least two second controllable valves, preferably two throttle valves, are located in the fluid line, with the connection to the fluid supply between them. This ensures that the working medium, i.e., the fluid, is always directed through one of the throttle valves when it enters or exits the compensation volume.

[0033] The two second controllable valves, preferably the two throttle valves, allow different flow resistances and thus different damping characteristics to be set for the two directions of movement of the piston within the cylinder.

[0034] Preferably, at least one, and especially preferably each, of the throttle valves is bypassed by a check valve that allows the working medium to flow into the respective cylinder chamber, but prevents it from flowing out of that cylinder chamber.

[0035] In a preferred embodiment, the energy storage device has at least one additional volume that is fluidically connected to the first cylinder chamber, wherein the energy storage device preferably has a third controllable valve by which the connection can be opened and closed. Particularly preferably, the additional volume is fluidically connected to the at least one fluid line that connects the two cylinder chambers.

[0036] This additional volume opens up further possibilities for using the energy storage device.

[0037] A compensating volume is capable of holding working fluid without increasing the pressure on the working fluid. As already explained, this allows the volume change in the two cylinder chambers, which can occur when the piston moves, to be compensated for. Consequently, pressure equalization takes place. In contrast, such pressure equalization is not possible with an auxiliary volume. This is therefore a closed volume, preferably completely filled with working fluid. In an energy storage device that has at least one of these auxiliary volumes, the pressure of the medium in the auxiliary volume is therefore also increased or decreased when the piston moves within the cylinder, provided the third controllable valve, which regulates the connection to the compensating volume, is closed.For example, if the piston is moved within the cylinder in such a way that the volume of the two cylinder chambers available for the working medium is reduced, and at the same time the first controllable valve that can open and close the fluid connection is in the closed position, the pressure within the working medium increases not only within the cylinder chambers, but also within the additional volume.

[0038] In this state, the third controllable valve, responsible for connecting the auxiliary volume to the hydraulic system, can be closed. This allows the working fluid to be stored within the auxiliary volume at increased pressure, and therefore with greater potential energy. The auxiliary volume thus serves as a lockable energy storage device, in which energy, once absorbed, can be stored by closing the third controllable valve. Regardless of the position and / or movement of the piston within the cylinder, the corresponding third controllable valve can be reopened at any desired time to release the working fluid within the auxiliary volume and discharge the stored potential energy.

[0039] In the case of a knee joint, for example, energy can be stored when sitting down. Subsequently, the third controllable valve can be closed, and at least one second controllable valve in the fluid line, as well as the first controllable valve and thus the fluid connection, can be opened. This results in the loss of the energy stored in the cylinder chambers, but allows the joint to move freely while seated. When standing up, at least one first controllable valve in the fluid connection can then be closed again, and the third controllable valve opened, so that the energy stored in the additional volume can be used to assist with standing.

[0040] Furthermore, the additional volume allows for a change in stiffness by opening or closing the third controllable valve. Opening the third controllable valve increases the total volume of working fluid available, thus reducing stiffness. Closing the third controllable valve reduces the total volume available to the working fluid and increases stiffness. This can be used to adjust stiffness depending on the situation; for example, a knee joint requires greater stiffness during the standing phase than when sitting down. Adjusting the stiffness to the user of the orthotic device can also be beneficial, for example, depending on the user's weight and personal preferences.

[0041] A throttle valve is also preferably included in this connection, allowing the flow resistance to be adjusted. This throttle valve can either be present in addition to the third controllable valve, or the third controllable valve can be designed as a throttle valve. This also allows adjustment of how quickly the pressurized working medium expands and over what period and at what rate the stored potential energy is released.

[0042] In a preferred embodiment, the energy storage device has several additional volumes. These are preferably all connected to the rest of the fluid system, for example, to one of the cylinder chambers. Particularly preferably, the energy storage device also has a plurality of third controllable valves, so that the connections of the individual additional volumes, preferably each individual additional volume, can be opened and closed separately. This preferably occurs independently of one another. In this way, different amounts of potential energy can be stored in different additional volumes and released as needed. The additional volumes can have the same volume or different volumes and can be containers with different pressure resistances. Furthermore, multiple additional volumes allow for a wider range of adjustable stiffnesses.

[0043] Preferably, several of these additional volumes are connected to each other in series via a fluid system. This means that the volumes are "connected in series". Consequently, the portion of the working fluid that is introduced into the last of these additional volumes must first pass through all the other additional volumes that are connected in series with this last additional volume.

[0044] Alternatively or additionally, several of the auxiliary volumes are connected to each other in parallel via fluid technology. This means that the individual volumes are "connected in parallel." This says nothing about the spatial orientation of the volumes. It simply means that a working medium that is to be directed into one of the auxiliary volumes does not have to pass through another of these parallel auxiliary volumes.

[0045] Here too, each additional volume is preferably connectable to or disconnectable from the rest of the fluid system via a third controllable valve. Particularly preferably, a separate throttle valve is provided for each additional volume, allowing the flow resistances in the respective connecting lines to be adjusted.

[0046] Advantageously, the orthotic device has at least one electrical control unit configured to independently control the controllable valves, switching valves, and / or throttle valves. Such an electrical control unit could be, for example, an electronic data processing device configured to send control signals to the corresponding valves, thereby moving the valves from one state to another. This can be done, for example, based on sensor data detected by sensors that may also be part of the orthotic device. These sensors could be force sensors, strain sensors, temperature sensors, speed or acceleration sensors, or other types of sensors.

[0047] Preferably, the first piston is mounted to be displaceable along a circular path, as is known, for example, from rotary hydraulics.

[0048] Ideally, the orthotic device is a knee prosthesis or a knee orthosis.

[0049] The invention also solves the stated problem by providing an energy storage device for one of the orthopaedic devices described here.

[0050] With the aid of the accompanying drawings, some exemplary embodiments of the present invention are explained in more detail below.

[0051] They show: Figures 1 to 5 show different states of an energy storage device according to a first embodiment of the present invention, and Figures 6 to 10 show different states of a second embodiment of an energy storage device.

[0052] Figure 1Figure 1 schematically shows an energy storage device 2 for an orthopaedic device. The energy storage device has a cylinder 4 containing a first cylinder chamber 6 and a second cylinder chamber 8, which are separated by a piston 10 mounted in a piston rod 12.

[0053] The first cylinder chamber 6 is connected to the second cylinder chamber 8 via a fluid line 14. A first throttle valve 16 and a second throttle valve 18 are located in the fluid line 14, each bypassed by a check valve 20. The check valves 20 are arranged such that no working fluid can escape from the first cylinder chamber 6 when the first throttle valve 16 is closed, and no working fluid can escape from the second cylinder chamber 8 when the second throttle valve 18 is closed. In the illustrated embodiment, the first throttle valve 16 and its associated check valve 20 together form a second controllable valve. The second throttle valve 18 and its associated check valve 20 also form a second controllable valve.

[0054] Between the two throttle valves 16, 18, a compensating volume 24 is fluidically connected via a fluid connection 22 to the fluid line 14 and thus to the first cylinder chamber 6 and the second cylinder chamber 8. A first controllable valve 26 is located in the fluid connection 22, which can be opened to a state that is Figure 1 is shown, and can be brought into a closed state by separating the compensation volume 24 from the rest of the fluid system.

[0055] Such an energy storage device 2, as used in the Figures 1 to 5 As shown schematically, it can, for example, be arranged in a prosthetic knee so that a gait cycle, as in the Figures 1 to 5 described, can proceed.

[0056] Figure 1Figure 1 shows the situation at heel strike. The compensation volume 24 is connected to the fluid line 14 via the open switching valve 26. The first throttle valve 16 and the second throttle valve 18 are open, allowing different opening sizes to be achieved through the respective throttle valves 16 and 18, thus adjusting the flow resistance opposing fluid movement.

[0057] When the heel strikes the ground, the prosthetic knee, into which the energy storage device 2 is integrated, flexes. This causes the piston 10 to move downwards within the cylinder 4. This situation is described in Figure 2The piston 10 has been moved downwards, thus reducing the size of the first cylinder chamber 6. Simultaneously, the second cylinder chamber 8 has been enlarged. However, the total volume of both cylinder chambers 6 and 8 has decreased because a larger portion of the piston rod 12 is now located inside the cylinder 4. During the lowering of the piston 10, the following occurred: Figure 1 The situation shown is such that the compensating volume 24 is connected to the rest of the fluid system. Since the total volume of the two cylinder chambers 6, 8 decreased when the piston 10 was lowered, some of the fluid was forced into the compensating volume 24.

[0058] In Figure 2Arrow 28 illustrates that, for example, in the so-called "foot flat" position, where the entire foot rests on the ground, the first controllable valve 26 closes. This disconnects the connection to the compensating volume 24 and the fluid line 14. The portion of the working fluid that was forced into the compensating volume 24 within cylinder 4 when the foot was lowered, and thus when the piston 10 was lowered, can no longer leave this compensating volume 24. Further flexion of the prosthetic knee, into which the energy storage device 2 is integrated, would lead to a further lowering of the piston 10 and thus to a further reduction in the total volume of the two cylinder chambers 6 and 8. This would result in compression of the contained fluid, for example, a silicone oil. This increases the pressure within the silicone oil and thus stores potential energy.Since the working fluid has no way of leaving the system consisting of the first cylinder chamber 6, the second cylinder chamber 8, and the fluid line 14, the energy is stored within this system and released again when the flexion force decreases. In this way, for example, natural stance phase flexion angles of up to 25° can now be achieved with a prosthetic knee without the user having to worry that the stored energy is lost and that they will no longer be able to extend the knee independently from this flexion position.

[0059] The energy storage device 2 stores the supplied potential energy from the moment the switching valve 26 closes and then releases it again. This causes the piston 10 to Figure 2pushed upwards, since although the pressure in the two cylinder chambers 6, 8 is identical, the underside of the piston 10 exposed to pressure is larger than the top side exposed to pressure, so that an overall upward force is achieved.

[0060] This situation is in Figure 3 The piston 10 with the piston rod 12 has been pushed upwards. This occurs until the first controllable valve 26 is closed. If this happens, unlike in Figure 2 As shown, at an earlier point in time, i.e., when the piston 10 with piston rod 12 has not yet been inserted so far into the cylinder 4, the Figure 3 The position shown has been reached. The switching valve 26 remains closed.

[0061] However, if, unlike in the figures shown, the switching valve 26 is closed directly at heel strike, i.e., in the Figure 1In the position shown, there is no fluid within the compensation volume 24, since the switching valve 26 was closed before the first compression of the volume of the two cylinder chambers 6, 8.

[0062] The arrangement shown makes it possible, from the moment the switching valve 26 is closed, to release potential energy absorbed by bending the prosthetic knee or another joint of an orthotic device, thus assisting the wearer of the orthotic device in the reverse movement of the joint. During this process, the fill level of the compensation volume 24 remains unchanged.

[0063] Figure 4Figure 1 shows the situation in which the first controllable valve 26 is open as indicated by arrow 28. This can occur, for example, in a prosthetic knee during the swing phase, where minimal resistance to knee flexion is desired. The two throttle valves 16 and 18 are opened, allowing fluid to flow between the first cylinder chamber 6 and the second cylinder chamber 8 with minimal resistance. As a result of the reduction in the total volume of the first cylinder chamber 6 and the second cylinder chamber 8, the compensating volume 24 is filled, as indicated by the fill level 30.

[0064] In Figure 5Figure 1 shows how, in this state, the first controllable valve 26 is closed according to arrow 28. The fill level 30 of the compensation volume 24 remains unchanged. In this state, a further movement of the piston 10 within the cylinder 4 leads to a change in the total volume of the first cylinder chamber 6 and the second cylinder chamber 8, so that potential energy can be stored within the fluid, for example, the silicone oil, which is released again after the force that supplied it is removed.

[0065] In the Figures 6 to 10Another embodiment of an energy storage device 2 is shown. It also has the cylinder 4 with first cylinder chamber 6, second cylinder chamber 8, piston 10 and piston rod 12. The compensation volume 24 is switchable via the first controllable valve 26 and connected to the fluid line 14 via the fluid connection 22, in which the already known valves are again located. In addition to the design from the Figures 1 to 5 The energy storage device 2 has, in accordance with the Figures 6 to 10 via an additional volume 32, which can be connected to or disconnected from the fluid line 14 via a third controllable valve 34.

[0066] In Figure 6 Both the first controllable valve 26 and the third controllable valve 34 are open, so that both the compensation volume 24 and the additional volume 32 are connected to the fluid line 14 and thus also to the first cylinder chamber 6 and to the second cylinder chamber 8.

[0067] If such an energy storage device 2 is installed, for example, in a prosthetic knee, the design can significantly simplify sitting down and, in particular, the subsequent standing up of the wearer of the orthopaedic device, in this case the prosthetic knee.

[0068] For sitting itself, the in Figure 7 The switching arrangement shown is used. The switching valve 26 is closed according to arrow 28, so that the compensating volume 24 is decoupled from the fluid line 14. The third controllable valve 34 remains open. When the piston 10 is lowered into the first cylinder chamber 6, as already seen in the Figures 1 to 5As explained, the total volume of the first cylinder chamber 6 and the second cylinder chamber 8 is reduced, a fact which is naturally not affected by the additional volume 32 still connected to the fluid line 14. The total volume available to the working medium is reduced, so that the fluid, for example the silicone oil, is compressed. In this state, potential energy is consequently stored in the energy storage device 2.

[0069] After sitting down, we in Figure 8The switching arrangement shown is set. Following the arrows 28, the first controllable valve 26 is opened, so that the compensating volume 24 is connected to the fluid line 14. The third controllable valve 34 is also actuated and closed, so that the auxiliary volume 32 is decoupled from the rest of the system. It is important to ensure that the third controllable valve 34 is preferably actuated before the first controllable valve 26 to prevent complete pressure equalization in the auxiliary volume 32. In the two cylinder chambers 6, 8, the working fluid is under increased pressure after compression during the lowering phase, when the piston 10 is lowered within the cylinder 4. When the first controllable valve 26 is opened, this pressure is released, forcing some of the fluid into the compensating volume 24, as indicated by the fill level 30.If the two throttle valves 16 and 18 are opened as wide as possible, the opposing flow resistance is minimal, thus allowing almost free movement of the knee. This is particularly desirable when sitting.

[0070] To get up again, the in Figure 9The switching arrangement shown is implemented. The two controllable valves 26, 34 are actuated according to arrows 28. First, however, the piston 10 is returned to the position corresponding to a fully flexed knee, as achieved when sitting down. Then, the first controllable valve 26 is actuated, separating the compensating volume 24 from the rest of the fluid system. Subsequently, the third controllable valve 34 can be actuated and opened, so that the additional volume 32 is reconnected to the fluid system. This volume still contains the high-pressure fluid, which now ensures pressure equalization with the two cylinder chambers 6, 8.

[0071] This increased pressure exerts an upward force on piston 10, pushing piston 10 upwards out of the cylinder. This is in Figure 10The working medium contained in the first cylinder chamber 6, the second cylinder chamber 8, and the additional volume 32 expands, releasing its stored potential energy. This pushes the piston 10 upwards, assisting the wearer of the orthotic device, for example, a prosthetic knee, when standing up.

[0072] Naturally, the arrangements can also be incorporated into other orthopaedic devices, so that moving the piston 10 within the cylinder 4 does not correspond to bending a knee, but to the movement of another joint. Reference symbol list

[0073] 2 Energy storage device 4 Cylinders 6 First cylinder chamber 8 Second cylinder chamber 10 Pistons 12 Piston rod 14 Fluid line 16 First throttle valve 18 Second throttle valve 20 Check valve 22 Fluid connection 24 Compensation volume 26 First controllable valve 28 Arrow 30 Fill level 32 Additional volume 34 Third controllable valve

Claims

1. An energy storage device (2) for an orthopaedic device, the energy storage device comprising at least one cylinder (4) in which • a first cylinder chamber (6), • a second cylinder chamber (8), which is fluidically connected to the first cylinder chamber (6) by means of at least one fluid line (14), and • a piston (10) are located, wherein the piston (10) is arranged such that it can be displaced relative to the cylinder (4) in such a way that the displacement of the piston (4) causes a working medium, which is a liquid, to be directed through the at least one fluid line (14) from one cylinder chamber (6, 8) into the other cylinder chamber (8, 6), wherein the energy storage device (2) comprises at least one compensation volume (24), which is fluidically connected to the fluid line (14) by way of a fluid connection (22), and at least one first controllable valve (26), by way of which the fluid connection (22) can be opened and closed, characterised in that no exchange of fluid can occur between the compensation volume and the first or second cylinder chamber when the first controllable valve is closed.

2. An orthopaedic device with an energy storage device (2) according to claim 1.

3. The orthopaedic device according to claim 2, characterised in that the working medium is a compressible liquid, preferably an oil, especially preferably a silicon oil.

4. The orthopaedic device according to claim 2 or 3, characterised in that there is at least one second controllable valve in the fluid line (14), by means of which a flow resistance of the fluidic connection can preferably be infinitely adjusted.

5. The orthopaedic device according to claim 4, characterised in that there are at least two second controllable valves in the fluid line (14), between which the connection with the fluid connection (22) is situated.

6. The orthopaedic device according to one of the claims 2 to 5, characterised in that the energy storage device (2) has at least one additional volume (32) that is fluidically connected to the first cylinder chamber (6) and / or the second cylinder chamber (8), wherein the energy storage device (2) preferably comprises a third controllable valve (34), by means of which the connection can be opened and closed.

7. The orthopaedic device according to claim 6, characterised in that the energy storage device (2) comprises multiple additional volumes (32) and preferably multiple third controllable valves (34), by means of which the connections between the additional volumes (32) and the first cylinder chamber (6) and / or the second cylinder chamber (8) can be opened and closed preferably independently from each other.

8. The orthopaedic device according to claim 7, characterised in that multiple additional volumes (32) are fluidically connected to each other in series and / or that multiple additional volumes (32) are fluidically connected to each other in parallel.

9. The orthopaedic device according to one of the claims 2 to 8, characterised in that the device has an electrical control unit that is configured to control the controllable valves (26, 34, 16, 18, 20) independently from each other.

10. The orthopaedic device according to one of the claims 2 to 9, characterised in that the piston (10) can be displaced along a circular path.

11. The orthopaedic device according to one of the claims 2 to 10, characterised in that the device is a knee prosthesis or knee orthosis.

12. The orthopaedic device according to one of the claims 2 to 11, characterised in that a diameter of a piston rod (12), a volume of the first cylinder chamber (6), a volume of the second cylinder chamber (8) and / or a compression module of the working medium is selected in such a way that a closed fluid connection (22) results in a spring constant of at most 750 N / mm, preferably less than 600 N / mm, particularly preferably less than 400 N / mm and preferably more than 100 N / mm, particularly preferably more than 300 N / mm.