JP5184928B2 - Prosthetic knee joint structure - Google Patents

Description

  The present invention relates to a knee joint structure used for a prosthetic limb, and more particularly to a knee joint structure in which a rotation suppression force is controlled by a rotation position.

  When walking with a knee joint structure having a thigh, a lower leg, and a joint that flexibly connects them, the relative rotation between the thigh and the lower leg is the relative rotation position (the knee flexion angle). ), It will be difficult to walk smoothly if not properly controlled. For example, if the thigh is moved forward by the user's remaining limb while the lower leg (joint foot) of the knee joint structure is in contact with the ground, the lower leg is rearward due to inertial force. May be bent abnormally deep (large angle). In this case, it takes a considerable amount of time for the lower leg part to swing forward in the reverse direction and be placed on the ground located in front of the body, and a smooth walking motion cannot be performed.

  As such a knee joint structure with few problems, for example, it has a piston cylinder device (damper) in which one end of a piston is locked to a thigh and a cylinder is locked to a crus, and a rotation suppression force is passively provided. The knee joint structure to be controlled is known.

  In addition, a technique for actively controlling the rotation suppression force has been developed. For example, in Patent Document 1, a magnetic field is applied to a magnetic fluid that functions as a working fluid of a piston cylinder device in which one end of a piston is locked to a thigh and a cylinder is locked to a crus. A swing phase control for controlling the driving resistance of the piston cylinder device by controlling the length is disclosed.

Further, in Patent Document 2, the working space of the cylinder divided by the piston head is defined as two extension chambers and a bending chamber, and the movement of the valve piston due to extension or bending accompanying the swinging of the thigh and crus. Oscillation phase control is disclosed that is performed by opening and closing a pressurized fluid conduit that controls the movement of the working fluid from the extension chamber to the bending chamber or vice versa.
Special table 2001-511052 gazette JP-A-9-551

  For a smooth walking motion, it is desirable that the bending resistance is low at the initial stage of bending (the rotation restraining force is small), and an appropriate bending resistance is obtained when the bending angle is around 60 °. There are individual differences in the bending angle range in which this bending resistance can be obtained.

  In the above-described conventional knee joint structure that passively controls the rotation suppression, the bending resistance increases because the lowering speed of the piston is high at the beginning of bending. Thereafter, even if the bending angle increases, the lowering speed of the piston is not high, so the bending resistance is low. As a result, a smooth walking motion cannot be performed.

  In any of the above-described swing phase control, the movement of the piston head is controlled by controlling the movement resistance of the working fluid from the extension chamber formed on both sides of the piston head of the piston cylinder device to the bending chamber or vice versa. Resistance is controlled and swinging of the thigh and crus is controlled. In such a device, in order to control the movement resistance of the working fluid, there is a problem that the device becomes complicated, requires electrical control, or becomes expensive.

  The present inventor has aimed at a knee joint structure that can more easily control the swing phase of the thigh and lower leg, and has been researched, and can control the free leg phase with a mechanical configuration without requiring electrical control. The invention of a perfect knee joint structure has been completed.

  The present inventor has found that the sliding resistance of the piston of the piston cylinder device is large when the sliding speed is fast, and the sliding resistance is small when the sliding speed is slow, and the magnitude of the sliding resistance is controlled by the sliding speed. I thought I could do it. Further, the sliding speed is proportional to the amount of sliding distance (sliding stroke) per unit swing angle when the swing speed of the thigh and the lower leg is constant. Accordingly, the sliding resistance is proportional to the amount of sliding distance (sliding stroke) per unit swing angle between the thigh and the lower leg. From these facts, the present invention has been completed with the intention of controlling the sliding speed of the piston in accordance with the swinging phase of the thigh and crus.

The knee joint structure of the present invention is a knee joint structure of a prosthesis comprising a thigh member, a crus member that rotates relative to the thigh member, and suppression means for suppressing swinging of the crus member, The restraining means includes a restraining force generating member having one end engaged with the crus member, a relative rotation by engaging the thigh member, and an end engaging the other end of the restraining force generating member. a cam for controlling the driving speed of the suppression force generating member, was closed, the suppressing force generating member, wherein one end portion pivotally supported on the lower leg member and a second end wherein the femoral member at one end Is held by a holding member that is pivotally supported, and the other end of the holding member is pivotally supported by the crus member via a compression spring, and the cam is the restraining force generating member. small above a driving speed flexion early, characterized Rukoto to be increased to a non-linear until further predetermined bending angle To.

  A plurality of suppression means can be provided.

The knee joint structure according to the present invention is a four-axis link structure including an upper link and a lower link, and the thigh member forms an upper link and the crus member forms a lower link.

  In addition, the restraining force generating member includes a spring in which the resistance force linearly changes by extension or compression, a piston cylinder device in which the sliding resistance changes by the sliding speed of the piston, and a friction in which the sliding resistance changes by the relative sliding speed. A sliding device can be employed.

  In the knee joint structure of the present invention, the cam controls the sliding speed of the restraining force generating member, that is, the driving speed, and also the amount of sliding distance (sliding stroke) per unit swing angle, A sliding resistance having a magnitude matching the oscillation phase is generated. As a result, the swinging of the thigh member and the crus member can be controlled to enable smooth walking.

  Further, by providing a plurality of suppression means, the bending resistance during bending can be increased. Furthermore, by using at least one restraining means that generates sliding resistance during extension, it is possible to walk more smoothly because there is no extension.

  In addition, by adopting the four-axis link structure, the rotation axis of the knee joint structure is virtually moved to the remaining limb side (upward), and it becomes easy to extend and bend.

  When the other end of the holding member is pivotally supported by the lower link via the compression spring, the joint can be extended by the reaction force of the spring compressed by bending.

The best-form knee joint structure will be described with reference to the drawings.
(Embodiment 1)
1 shows the knee joint structure in the extended state, FIG. 1 (a) is a side view, FIG. 1 (b) is a partial sectional view of FIG. 1 (a), and FIG. 1 (c) is a rear view. FIG. FIG. 2 is a partial cross-sectional view showing the knee joint structure in a bent state. The top and bottom, front and back are as shown in the figure.

  As shown in FIG. 1, the knee joint structure of the present invention includes a thigh member 1, a crus member 2 that rotates relative to the thigh member 1, and suppression means 3 that suppresses swinging of the crus member 2. The suppressing means 3 includes a piston cylinder device (suppressing force generating member) 31 with one end engaged with the crus member 2 and a relative rotation while engaging with the thigh member 1 and an end at the other end of the piston cylinder device 31. And a cam 32 that engages with the portion and controls the drive speed of the piston cylinder device 31.

  The thigh member 1 has an adjustable connector 1a for coupling to a thigh socket at the upper part, and a joint shaft 1b is fixed to the lower part.

  Near the center of the joint shaft 1b, the vicinity of the center of the cam 32 is fixed, and the upper end of the crus member 2 is engaged with both ends.

  The crus member 2 is a beam structure member having a substantially U-shaped cross section having an adjustable connector 2a for coupling to a foot part at the lower part. 2b is a side beam.

  The piston cylinder device 31 includes a cylinder 311 having an outer peripheral wall fixed to the side beam 2b of the crus member 2 and a piston rod 312 having a piston head 312a sliding on the inner peripheral wall of the cylinder 311 at the lower end. A working fluid (oil) (not shown) is sealed in the cylinder 311, and an orifice (not shown) through which the working fluid enters and exits is formed in the piston head 312 a. A commercially available damper device can be used as the piston cylinder device 31.

  A cam follower 314 is attached to the upper end of the piston rod 312 via a U-shaped connecting member 313 so as to be engageable with the cam 32.

  Note that the knee joint structure of the present embodiment includes a suppression means 3 ′ having the same configuration as the suppression means 3 as shown in FIG. The restraining means 3 restrains and controls the bending of the knee joint, whereas the restraining means 3 'restrains and controls the extension of the knee joint. Therefore, the cam 32 'has the same shape as the cam 32, but has a different attachment angle to the joint shaft 1b.

  Next, the operation of the knee joint structure of this embodiment will be described. In the extended state of FIG. 1, the portion of the cam 32 having the smallest distance from the center of the joint shaft 1b is in contact with the cam follower 314, and the piston head 312a is positioned at the uppermost position (see FIG. 1B). ). When the crus member 2 bends (turns around the joint shaft 1b in the direction of the arrow) from this state, the position of the cam 32 with which the cam follower 314 comes into contact with the position where the distance from the center of the joint shaft 1b increases nonlinearly, Move like a-> i-> u-> d .... FIG. 2 shows a state in which the cam follower 314 is in contact with the cam 32 at the position c. FIG. 3 shows the relationship between the displacement (sliding stroke) of the piston head 312a and the bending angle when the knee joint is bent and the cam follower 314 comes in contact with the cam 32 in the order of a, b, c, and so on. (Cam A curve) is shown. From FIG. 3, the sliding stroke is zero during a (0 °) → a (25 °), and the sliding stroke is proportional to the bending angle during a (25 °) → d (60 °). It can be seen that the saturation starts and decreases after (60 °). That is, in the case of the knee joint structure of the present embodiment, there is no sliding resistance (bending resistance) when the bending angle is in the range of 0 ° to 25 °, and appropriate sliding resistance (bending resistance) is within the range of 25 ° to 60 °. It turns out that occurs. Accordingly, there is no bending resistance at the beginning of bending, and thereafter there is bending resistance up to a bending angle of 60 °, so that smooth walking is possible without bending greatly.

  When rotating from the bent state in FIG. 2 in the opposite direction to the arrow and returning to the extended state in FIG. 1, the cam 32 ′ and the piston cylinder device 31 ′ generate an extension resistance during the extension process, and more smooth walking is possible. become.

  FIG. 3 also shows the relationship between the sliding stroke and the bending angle when the cam 32 is changed to another cam (cam B). In the case of this cam B, it can be seen that a constant bending resistance occurs up to about 75 °. Therefore, even if there are individual differences in the range of bending angles at which bending resistance occurs, it can be solved by changing the shape of the cam (instead of a cam having a different shape).

In the knee joint structure of the present embodiment, the piston cylinder device is employed as the restraining force generating member, but a spring or a friction sliding device may be employed.
(Embodiment 2)
4 shows the knee joint structure in the extended state, FIG. 4 (a) is a side view, FIG. 4 (b) is a cross-sectional view of FIG. 4 (a), and FIG. 4 (c) is a rear view. It is. FIG. 5 is a partial cross-sectional view showing the knee joint structure in a bent state. In addition, the same code | symbol is attached | subjected to the element same as Embodiment 1, and description is partially omitted.

  As shown in FIG. 4, the knee joint structure of the present embodiment is a four-axis link structure including an upper link 1, a lower link 2, a front link 5, and a rear link 6. Each member forms a lower link 2, and a piston cylinder device (suppressing force generating member) 31 is pivotally supported at one end so as to be able to swing on the lower link 2 and supported at one end on the upper link 1. The holding member 4 is held.

  The upper link (thigh member) 1 has an adjustable connector 1a for coupling to a thigh socket at the upper portion, and a joint shaft 1b is fixed near the center.

  Near the center of the joint shaft 1b, two cams 32 are fixed at one end with an interval, and the upper end of the front link 5 is slidably engaged with both ends.

  The upper end of the rear link 6 is pivotally supported by a pin P1 at the other end of the cam 32, and the upper end of the holding member 4 is pivotally supported by a pin P2 near the center.

  The lower link (crut member) 2 has an adjustable connector 2a for coupling to the foot portion at the lower portion, and the lower end portion of the front link 5 is pivotally supported by a pin P3 in the vicinity of the center portion. The lower end portion of the rear link 6 is pivotally supported by the portion by a pin P4.

  In the piston cylinder device 31, the lower end of the cylinder 311 is pivotally supported by a pin P5 near the center of the lower link 2, and the upper end of the cylinder 311 is slidable by the sleeve 4a of the holding member 4. Is held in.

  The holding member 4 has a sleeve 4 a for holding the cylinder 311 at the lower part and a guide member 4 b for guiding the cam follower 314 fixed to the piston rod 312 at the upper part, and the upper end of the guide member 4 b is the central part of the cam 32. It is pivotally supported by a pin P2 in the vicinity. The lower end of the sleeve 4a is biased upward by a spring 7 mounted on the outer periphery of the cylinder 311.

  The knee joint structure of the present embodiment is a four-axis link structure, and the rotation center O is a point where a line connecting the joint axis 1b and the pin P3 intersects with a line connecting the pin P1 and the pin P4. . As shown in FIG. 4 (a), the point O virtually moves to the remaining limb side (upward), and extension and bending are possible even if the muscular strength is weak.

Next, the operation of the knee joint structure of this embodiment will be described. In the extended state of FIG. 4 , the cam follower 314 is located at the front lower side of the cam 32, and the piston head 312 a is positioned at the uppermost position (see FIG. 1B). When bent in the direction of the arrow (rearward) from this state, the lower link 2 rotates about O by the four-axis link structure. Since the cam follower 314 and the cam 32 are separated from each other by a predetermined distance, the cam follower 314 is not engaged with the cam 32 at the beginning of bending, and no bending resistance is generated from the piston cylinder device 31. On the other hand, even in the initial stage of bending, the spring 7 is compressed by the rotation of the lower link 2 in the direction of the arrow, and the reaction force acts on the upper link 1 via the holding member 4. When the rotation in the direction of the arrow further proceeds, as shown in FIG. 5, the cam follower 312 engages with the cam 32, the piston head 312a slides downward, and bending resistance is generated. At the same time, since the spring 7 is also compressed, the reaction force from the compression spring 7 is also added to the bending resistance. Thereafter, when the predetermined bending angle is reached, the extension is completed by the reaction force of the compressed compression spring 7.

It is a figure which shows the extension state of the knee joint structure of Embodiment 1. FIG. It is a figure which shows the bending state of the knee joint structure of Embodiment 1. FIG. It is a graph which shows the relationship between the knee bending angle of the suppression means of Embodiment 1, and a sliding stroke. It is a figure which shows the extension state of the knee joint structure of Embodiment 2. FIG. It is a figure which shows the bending state of the knee joint structure of Embodiment 2. FIG.

Explanation of symbols

1. Thigh member (upper link)
2 ... Lower leg member (lower link)
3... Suppressing means 31... Suppressing force generating means (piston cylinder device)
32 ... Cam 4 ... Holding member 7 ... Compression spring

Claims (3)

A knee joint structure of a prosthesis comprising a thigh member, a crus member that rotates relative to the thigh member, and suppression means for suppressing swinging of the crus member,
The restraining means includes a restraining force generating member having one end engaged with the crus member, a relative rotation by engaging with the thigh member, and an end engaged with the other end of the restraining force generating member. It possesses a cam for controlling the driving speed of the suppressive force generating member and the,
The restraining force generating member is held by a holding member whose one end is pivotally supported by the crus member and whose other end is pivotally supported by the thigh member.
The other end of the holding member is pivotally supported by the crus member via a compression spring so as to be swingable.
The cam is small the drive speed of the suppressing force generating member in the bending initial knee joint structure of the prosthesis, characterized in Rukoto was then increased to a non-linear up to a predetermined bending angle. The knee joint structure is a four-axis link structure including an upper link and a lower link,
The knee joint structure of a prosthetic limb according to claim 1, wherein the thigh member forms the upper link and the crus member forms the lower link. The suppressing force generating member, a spring, a piston cylinder device, the knee joint structure of the prosthesis according to a kind of claim 1 or 2 of the friction sliding device.

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