The present invention claims priority under 35 U.S.C. § 119 to Japanese Application, 2021-137159, filed on Aug. 25, 2021, the entire contents of which being incorporated herein by reference.
The present invention relates to an artificial knee joint and a prosthetic limb.
JP H7-308332 A discloses an artificial knee joint or a prosthetic limb worn by a person who has lost a leg due to injury or illness, which includes an air cylinder that swings back and forth. In the air cylinder pivotally supported by a lower leg part, air as a working fluid is sealed therein and a piston is movably provided. Also, a piston rod extending from the piston is coupled to a thigh joint part. When the thigh joint part and the lower leg part relatively rotate according to bending and stretching of the artificial knee joint, the piston moves in the air cylinder and the entire air cylinder rotates around the axis of the lower leg part and swings back and forth.
In the structure of JP H7-308332 A, since the air cylinder swings back and forth, the substantial dimension of the artificial knee joint in the front-rear direction becomes long. In addition, since the space on the swing path of the air cylinder becomes a dead space, in particular, in the electronically controlled artificial knee joint, it is necessary to mount many functional components such as a sensor, a motor, a control board, and a battery in other locations, which causes an increase in size of the artificial knee joint.
The present invention addresses the above-described issue and a purpose thereof is to provide an artificial knee joint and a prosthetic limb that can be configured compactly.
In order to solve the above problems, an artificial knee joint according to an aspect of the present invention includes: a thigh joint part provided on a thigh part side; a lower leg part rotatably connected to the thigh joint part via at least one rotation shaft; a cylinder fixed to one of the thigh joint part and the lower leg part and filled with a working fluid; a piston provided movably between the thigh joint part side and the lower leg part side in the cylinder; a cylinder wall provided in the cylinder and defining a motion limit of the other side of the thigh joint part and the lower leg part of the piston; a piston rod extending from the piston toward the other of the thigh joint part and the lower leg part and penetrating the cylinder wall; and a connecting rod that connects the piston rod to the other of the thigh joint part and the lower leg part and is connected to the piston rod at a connecting part that is separated by a predetermined distance or more from the other end of the other of the thigh joint part and the lower leg part on the piston rod toward one end on the piston side. When the piston is at the limit position on one side of the thigh joint part and lower leg part, the connecting part of the connecting rod and the piston rod is located between the cylinder wall and the piston.
In this aspect, since the piston rod is connected to the thigh joint part or lower leg part via the connecting rod, it is possible to suppress the swinging of the piston rod and the cylinder and to reduce the dimension of the artificial knee joint in the front-rear direction. In addition, since the connecting rod is connected to the connecting part separated from the other end of the piston rod, the dimension of the artificial knee joint in the vertical direction can also be reduced. Therefore, the artificial knee joint can be configured compactly.
Another aspect of the present invention also relates to an artificial knee joint. This artificial knee joint includes: a thigh joint part provided on a thigh part side; a lower leg part rotatably connected to the thigh joint part via at least one rotation shaft; a rotational resistance applicator including: a cylinder fixed to one of the thigh joint part and the lower leg part and filled with a working fluid; a piston provided movably between the thigh joint part side and the lower leg part side in the cylinder; a cylinder wall provided in the cylinder and defining a motion limit of the piston; and a rod part connecting the piston and the other of the thigh joint part and the lower leg part, the rotational resistance applicator being structured to apply a resistance by the working fluid according to a position of the piston in the cylinder to relative rotation of the thigh joint part and the lower leg part; and functional components that are stored inside the cylinder wall and control the resistance applied by the rotational resistance applicator according to a phase of walking of a user.
In this aspect, since the functional components that control the resistance applied by the rotational resistance applicator according to the phase of walking of the user of the artificial knee joint are stored inside the cylinder wall, the artificial knee joint can be made compact.
Still another aspect of the present invention is a prosthetic limb. This prosthetic limb includes: a thigh part; a thigh joint part provided on the thigh part side; a lower leg part rotatably connected to the thigh joint part via at least one rotation shaft; a cylinder fixed to one of the thigh joint part and the lower leg part and filled with a working fluid; a piston provided movably between the thigh joint part side and the lower leg part side in the cylinder; a cylinder wall provided in the cylinder and defining a motion limit of the other side of the thigh joint part and the lower leg part of the piston; a piston rod extending from the piston toward the other of the thigh joint part and the lower leg part and penetrating the cylinder wall; and a connecting rod that connects the piston rod to the other of the thigh joint part and the lower leg part and is connected to the piston rod at a connecting part that is separated by a predetermined distance or more from the other end of the other side of the thigh joint part and the lower leg part on the piston rod toward one end on the piston side. When the piston is at the limit position on one side of the thigh joint part and lower leg part, the connecting part of the connecting rod and the piston rod is located between the cylinder wall and the piston.
Another aspect of the present invention also relates to a prosthetic limb. This prosthetic limb includes: a thigh part, a thigh joint part provided on the thigh part side; a lower leg part rotatably connected to the thigh joint part via at least one rotation shaft; a rotational resistance applicator including: a cylinder fixed to one of the thigh joint part and the lower leg part and filled with a working fluid; a piston provided movably between the thigh joint part side and the lower leg part side in the cylinder; a cylinder wall provided in the cylinder and defining a motion limit of the piston; and a rod part connecting the piston and the other of the thigh joint part and the lower leg part, the rotational resistance applicator being structured to apply a resistance by the working fluid according to a position of the piston in the cylinder to relative rotation of the thigh joint part and the lower leg part; and functional components that are stored inside the cylinder wall and control the resistance applied by the rotational resistance applicator according to a phase of walking of a user.
Optional combinations of the aforementioned constituting elements, and implementations of the disclosure in the form of methods, apparatuses, systems, recording mediums, and computer programs may also be practiced as additional modes of the present invention.
FIGS. 10A1, FIG. 10A2, FIG. 10B1, and FIG. 10B2 schematically illustrate a manner in which the cylinder device applies rotational resistance to bending and stretching motions of the multi-articulated link knee joint.
The invention will now be described by reference to the preferred embodiments. This does not intend to limit the scope of the present invention, but to exemplify the invention.
There are various types of artificial knee joints, and they are roughly classified into an active type and a passive type. The passive type is further classified into an electronically controlled type and a mechanical type. In the active type, the knee is actively driven to be bent and stretched by an actuator such as a motor. In the electronically controlled passive type, the rotational resistance of the knee is controlled by an electronically controlled air cylinder, hydraulic cylinder, or the like according to the bending and stretching motion of the user such as walking. In the mechanical passive type, the bending and stretching motion of the user such as walking is assisted by an air cylinder, a hydraulic cylinder, or the like in which the amount and pressure of the working fluid are adjusted in advance. The present invention is applicable to any type of artificial knee joint as long as it is consistent with the description of the present embodiment described below. In particular, among the configurations described regarding the electronically controlled artificial knee joint in the present embodiment, a mechanical configuration not premised on the rotational resistance control according to the phase of walking of the user is also applicable to a mechanical knee joint.
First, an outline of the artificial knee joint will be described.
The multi-articulated link knee joint 100 includes a knee part 10. The knee part 10 is bent by a multi-articulated link mechanism having a plurality of link parts. The multi-articulated link mechanism includes four link parts of an upper link part 50, a lower link part 52, a front link part 54, and a rear link part 56. In the present description, a link and a part that is fixed to the link so as to move together with the link are collectively referred to as a “link part”. The upper link part 50 includes an upper link 16 and a thigh joint part 32. The lower link part 52 includes a lower link 18 and a lower leg part 12. The front link part 54 includes a front link 20, and the rear link part 56 includes a rear link 22.
The upper link 16 is provided with a first shaft 24 and a second shaft 26 as rotation shafts, and the lower link 18 is provided with a third shaft 28 and a fourth shaft 30 as rotation shafts. Each shaft is rotatably provided with the axial direction being parallel to the x axis. The front link 20 is attached to the ends of the first shaft 24 and the third shaft 28. The rear link 22 is attached to the ends of the second shaft 26 and the fourth shaft 30. The upper link 16 is supported by the front link 20 and the rear link 22 and rotates with respect to the lower link 18. In this manner, the upper link 16 to which the thigh joint part 32 is fixed and the lower link 18 to which the lower leg part 12 is fixed are rotatably connected via a plurality of rotation shafts (that is, a pair of the first shaft 24 and the third shaft 28, or a pair of the second shaft 26 and the fourth shaft 30) and a pair of left and right links (that is, two front links 20 or two rear links 22) connecting both ends of the plurality of rotation shafts to each other.
The thigh joint part 32 protruding from the upper link 16 is connected to a socket attached to the thigh part of the user. An angle formed by the direction in which thigh joint part 32 protrudes and the z axis is defined as a bending angle or a knee angle of knee part 10. The bending angle of the knee part 10 can be measured by a knee angle sensor, an inertial sensor, or the like (not illustrated). In
The multi-articulated link knee joint 100 includes a cylinder device 60 as an assisting driver that assists the motion of the knee part 10. The cylinder device 60 includes, for example, an air cylinder or a hydraulic cylinder. The cylinder device 60 includes a cylinder 62, a piston rod 64 movable with respect to the cylinder 62, and a piston 66 to which the piston rod 64 is fixed and that is movably housed inside the cylinder 62. The cylinder device 60 is provided so as to connect the upper link part 50 and the lower link part 52. Specifically, the cylinder 62 is rotatably supported by a lower shaft 68 provided in the lower leg part 12 of the lower link part 52, and the piston rod 64 is rotatably supported by an upper shaft 70 provided in the upper link 16 of the upper link part 50. With this configuration, the cylinder device 60 moves or swings in the front-rear direction about the lower shaft 68 according to the rotation of the upper link part 50.
The multi-articulated link knee joint 100 further includes a control device 14. The control device 14 is housed inside the lower leg part 12 and controls the cylinder device 60 according to the bending angle of the knee part 10 measured by a knee angle sensor, an inertial sensor, or the like.
The control device 14 includes a knee angle acquisition unit 42 and a controller 44. The knee angle acquisition unit 42 acquires the bending angle of the knee part 10 from a knee angle sensor 58 such as a knee angle sensor or an inertial sensor. The controller 44 controls the cylinder device 60 according to the knee angle acquired by the knee angle acquisition unit 42 to assist the motion of the knee part 10. For example, when the bending angle is close to 0 degrees, the controller 44 controls the cylinder device 60 so as to limit the rotation of the third shaft 28, thereby preventing the knee instability in which the knee part 10 is bent against the intention of the user. In addition, the controller 44 controls the cylinder device 60 to allow the rotation of the third shaft 28 according to the change to be taken in the knee angle during the swing period when the bending angle changes, such as when walking. With this configuration, the lower leg part 12 can swing according to the swinging of each foot at the time of walking, so that the user can walk comfortably.
A cylinder device 60 such as an air cylinder or a hydraulic cylinder that assists the motion of the knee part 10 includes a cylinder 62 that is fixed to the lower leg part 12 and in which air or oil as a working fluid is sealed therein, a piston 66 that is provided in the cylinder 62 so as to be movable in the vertical direction or the z-axis direction between a first cylinder wall 61 on the lower leg part 12 side and a second cylinder wall 63 on the thigh joint part 32 side, and a piston rod 64 that extends upward from the piston 66 toward the thigh joint part 32 and penetrates the second cylinder wall 63. On the inner peripheral surface of the second cylinder wall 63 on which the outer peripheral surface of the piston rod 64 slides with the motion of the piston 66 in the vertical direction, a bearing 631 that pivotally supports the piston rod 64 and a seal member 632 such as an O-ring that seals the cylinder 62 so as not to leak the working fluid are provided. Here, the first cylinder wall 61 and the second cylinder wall 63 define each of the upward and downward motion limits of the piston 66.
The piston rod 64 constitutes a rod part connecting the piston 66 and the thigh joint part 32 together with the connecting rod 65. Specifically, the upper end of the connecting rod 65 is rotatably supported by the upper shaft 70 provided on the upper link 16, and the lower end of the connecting rod 65 is rotatably supported by the lower shaft 68 as a connecting part provided at the upper end of the piston rod 64 on the thigh joint part 32 side. With this configuration, the connecting rod 65 moves or swings in the front-rear direction about the lower shaft 68 according to the rotation of the upper link 16 and thigh joint part 32. On the other hand, unlike the multi-articulated link knee joint 100 in the swing cylinder-type in
In addition, as indicated by an arrow from the lower shaft 68, as the connecting part of the piston rod 64 and the connecting rod 65 positioned upward, the angle θ formed by the force F exerted by the connecting rod 65 on the distal end of the piston rod 64 and the vertical direction becomes larger, so that a large force F sin θ in the front-rear direction or the lateral direction is applied to the piston rod 64. As a result, when an excessive load is applied to the bearing member such as the second cylinder wall 63 that axially supports the piston rod 64 from the side, wear of the bearing 631 and the piston rod 64 is promoted, leading to deterioration of durability of the multi-articulated link knee joint 100.
With such a configuration, since the cylinder device 60 does not swing in the front-rear direction as in
In addition, since the connecting part 68 of the piston rod 64 and the connecting rod 65 is located below as compared with
The lower piston rod 67 constituting the rod part together with the piston rod 64 and the connecting rod 65 includes a flange part 670 protruding in the radial direction (the x-axis direction and the y-axis direction) at the tip penetrating the first cylinder wall 61 from the upper side to the lower side. The diameter of the flange part 670 is larger than the diameter of the cross section surrounded by the inner peripheral surface of the first cylinder wall 61, and when the piston 66 moves upward, the upper surface of the flange part 670 abuts against the lower surface of the first cylinder wall 61, so that the piston 66 is stopped. In other words, the flange part 670 defines an upper stroke length, which is a maximum upward motion amount of the piston 66.
An extension assist spring 672 that biases the lower piston rod 67 upward is attached to the lower surface of the flange part 670. The extension assist spring 672 urges the thigh joint part 32 via the lower piston rod 67, the piston 66, the upper piston rod 64, the connecting rod 65, and the upper link 16 in the clockwise direction, that is, the stretching direction of the multi-articulated link knee joint 100. Accordingly, when the multi-articulated link knee joint 100 is slightly bent, it is possible to naturally return to the stretched state by the biasing force of the extension assist spring 672. The lower end of the extension assist spring 672 whose upper end biases the lower surface of the flange part 670 upward biases the bottom surface of a tubular holder 673 that houses the extension assist spring 672 downward. An outer peripheral surface of the holder 673 constitutes the foot joint part 40, and an attachment pipe 674 (shown in broken line) having a foot part (not illustrated) at a lower end is inserted from below, whereby the foot part is attached to lower leg part 12.
The comparative example of
The upper piston 661 forms an upper pressure chamber in which air or oil as a working fluid is sealed with the upper surface of the cylinder wall 69, and the lower piston 662 forms a lower pressure chamber in which air or oil as a working fluid is sealed with the lower surface of the cylinder wall 69. In addition, the lower piston 662 performs a function similar to that of the flange part 670 in
The upper piston rod 64 fixed to the upper surface of the upper piston 661 is a member that is short in the vertical direction, unlike the piston rod 64, which is long in the vertical direction in
In the configuration of
In
The sensor 81 may be, for example, the knee angle sensor 58 that detects a position of a magnet embedded in a piston rod or the like with a Hall element or the like and measures an extension/contraction position of the cylinder device 60 and a knee angle substantially on a one-to-one basis with the extension/contraction position, an inertial sensor that detects the posture and motion of the multi-articulated link knee joint 100 by measuring the speed (angular speed) and/or acceleration (angular acceleration) in the translational direction and/or rotational direction of the three axes defining the motion of the multi-articulated link knee joint 100, or a temperature sensor that measures the temperature of the cylinder device 60. The bumper 82 is a shock absorbing component that alleviates an impact when the cylindrical fourth shaft 30 rotates in a cylindrical fifth shaft 31 having a diameter larger than the cylindrical fourth shaft 30.
Next, the configuration and operation of the cylinder device 60 will be described.
The controller 44 that controls the cylinder device 60 is a pressure drive mechanism that drives the cylinder device 60 to extend and contract by pneumatic pressure or hydraulic pressure. The controller 44 includes a stretching side pressure circuit 91 and a bending side pressure circuit 92 each connected to the cylinder 62. The stretching side pressure circuit 91 and the bending side pressure circuit 92 communicate with the first pressure chamber 621 on one end side and communicate with the second pressure chamber 622 on the other end side, respectively. The stretching side pressure circuit 91 includes a stretching side valve 93 as a valve capable of opening and closing the flow path of the working fluid that generates the rotational resistance of the knee part 10 and a stretching side check valve 94. Opening the stretching side valve 93 allows the working fluid to be distributed in the stretching side pressure circuit 91. The action of the stretching side check valve 94 causes the working fluid to flow only in the direction from the first pressure chamber 621 to the second pressure chamber 622 and not to flow in the opposite direction.
The bending side pressure circuit 92 includes a bending side valve 95 as a valve capable of opening or closing the fluid path of the working fluid for generating the rotational resistance of the knee part 10 and a bending side check valve 96. Opening the bending side valve 95 allows the working fluid to be distributed in the bending side pressure circuit 92. The action of the bending side check valve 96 causes the working fluid to flow only in the direction from the second pressure chamber 622 to the first pressure chamber 621 and not to flow in the opposite direction. The open position of the stretching side valve 93 and the bending side valve 95 can have an arbitrary value between fully opened (the maximum open position) and fully closed (the minimum open position). When each valve is fully closed, the flow of the working fluid is blocked and the rotational resistance of the knee part 10 is maximized, and when each valve is fully opened, the rotational resistance of the knee part 10 is minimized. Specifically, when the stretching side valve 93 is fully closed/fully opened, the rotational resistance to the stretching motion of the knee part 10 is maximized/minimized, and when the bending side valve 95 is fully closed/fully opened, the rotational resistance to the bending motion of the knee part 10 is maximized/minimized.
The stretching side valve 93 and the bending side valve 95 are provided with a stretching side motor 97 and a bending side motor 98 for driving to open and close the stretching side valve and the bending side valve, respectively. The stretching side motor 97 and the bending side motor 98 are controlled by the controller 44, and the open positions of the stretching side valve 93 and the bending side valve 95 are controlled according to the phase of walking of the user of the multi-articulated link knee joint 100. The controller 44 recognizes the phase of walking based on the knee angle measurable by the sensor 81 and the posture and motion of the multi-articulated link knee joint 100. In such walking control or bending and stretching control of the multi-articulated link knee joint 100, it is particularly important to control the bend resistance of the knee part 10 by the bending side valve 95. Specifically, in the Stance phase in which the prosthetic limb is in contact with the ground and is under load, the bend resistance is increased to prevent the knee part 10 from being bent under load (the open position of the bending side valve 95 is minimized). In the Swing phase in which the prosthetic limb leaves the ground and is swung, the bend resistance is decreased (the open position of the bending side valve 95 is maximized) to bend the knee part 10 and prevent the prosthetic limb from touching the ground.
FIGS. 10A1, FIG. 10A2, FIG. 10B1, and FIG. 10B2 schematically illustrate a manner in which the cylinder device 60 applies rotational resistance to bending and stretching motions of the multi-articulated link knee joint 100 in
As shown in FIG. 10B1 and FIG. 10B2, when the piston 66 moves from the second cylinder wall 63 side to the first cylinder wall 61 side, that is, when the transition is made from FIG. 10B1 to FIG. 10B2, the connecting part 68 of the connecting rod 65 and the piston rod 64 moves from the thigh joint part 32 side (upper side) toward the lower leg part 12 side (lower side) so as to penetrate the second cylinder wall 63. When the piston 66 is at the limit position on the first cylinder wall 61 side, that is, at the position of FIG. 10B2, the connecting part 68 of the connecting rod 65 and the piston rod 64 is at a corresponding position in the cylinder 62. Alternatively, when the piston 66 is at the limit position of the lower leg part 12 side, the connecting part 68 of the connecting rod 65 and the piston rod 64 is at the position between the second cylinder wall 63 and the piston 66. For convenience of illustration, the connecting rod 65 and the connecting part 68 are shown as being exposed to the outside of the piston rod 64, but in practice, since the connecting rod 65 and the connecting part 68 are provided inside the piston rod 64 as described with reference to
FIG. 10A1 illustrates a manner in which the knee part 10 of the multi-articulated link knee joint 100 of
As illustrated in
As illustrated in
The lower piston rod 67 in
In
In the stretched state in which the piston 66 is located upward as illustrated in the drawing, the second pressure chamber 622 and the large-diameter part 613 communicate with each other to form one large pressure chamber. The bend resistance applied to the knee part 10 by this large pressure chamber can be controlled by the open position of the first bending side valve 951 and/or the second bending side valve 952. When the knee part 10 bends from the stretched state of
As above, the present invention has been described based on the embodiments. The embodiment is intended to be illustrative only and it will be understood by those skilled in the art that various modifications to constituting elements and processes could be developed and that such modifications are also within the scope of the present invention.
In the multi-articulated link knee joint 100 of the embodiments, the cylinder device 60 is fixed to the lower leg part 12, and the connecting rod 65 that connects the piston rod 64 and the thigh joint part 32 is provided. However, the cylinder device 60 may be fixed to the thigh joint part 32, and the connecting rod 65 that connects the piston rod 64 and the lower leg part 12 may be provided. In this case, the top and bottom are reversed from those in
In the multi-articulated link knee joint 100 of
The technical idea of providing the connecting part 68 of the connecting rod 65 at a position separated by the predetermined distance D from the upper end to the lower end of the piston rod 64 illustrated in
The technical idea illustrated in
In the embodiments, the multi-articulated link knee joint 100 including the plurality of rotation shafts 24, 26, 28, and 29 and the plurality of front and rear links 20 and 22 has been described, but having at least one rotation shaft may be sufficient, and the front and rear links are not necessarily required. Therefore, the present invention is also applicable to an artificial knee joint having a uniaxial configuration in which the thigh joint part 32 and the lower leg part 12 are simply connected by one rotation shaft.
The functional configuration of each device described in the embodiments can be achieved by hardware resources or software resources or a cooperation of hardware resources and software resources. Processors, ROMs, RAMs, and other LSIs can be used as hardware resources. Programs such as operating systems and applications can be used as software resources.
Among the embodiments disclosed in the present specification, a configuration including a plurality of objects may integrate the plurality of objects, and conversely, a configuration including one object can be divided into a plurality of objects. The present invention may be configured to achieve an object of the invention regardless of whether or not the present invention is integrated.
Among the embodiments disclosed in the present specification in which a plurality of functions are distributed, some or all of the plurality of functions may be aggregated. Conversely, an aggregation of a plurality of functions may be distributed in part of in the entirety. Regardless of whether functions are aggregated or distributed, the functions may be configured to achieve the purpose of the invention.
Number | Date | Country | Kind |
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2021-137159 | Aug 2021 | JP | national |