JP6406771B1 - Prosthetic leaf spring - Google Patents

Abstract

Provided is a leaf spring for a prosthetic leg that can increase the rotational performance under the knee by reducing the moment of inertia around the knee joint and can improve the ease of swinging the leaf spring during running.
In a leaf spring for an artificial leg having a bending portion, the bending portion includes a heel portion protruding toward the rear side, and the height Hb of the most convex point protruding most rearward in the heel portion is 150 mm. ≦ Hb is satisfied, and the length Lt between the most convex point and the most distal point on the front side of the curved portion satisfies the relationship Lt ≦ 310 mm.
[Selection] Figure 1

Description

  The present invention relates to a prosthetic leg spring to be mounted on a prosthetic leg for competition.

  In the field of prosthetic legs used in sports competitions, there are known prosthetic leg springs for competitions that use leaf spring members molded from fiber-reinforced resin as the legs. For example, Non-Patent Document 1 discloses a prosthetic leg spring having a C-shaped curved portion. A user of such a prosthetic leaf spring deflects the curved region of the leaf spring to generate a repulsive force, and uses this repulsive force to obtain a propulsive force in the traveling direction.

Pacific Supply Co., Ltd. Ozul artificial limb parts general catalog (Japanese version) 2015-2016, page 169

  Conventional prosthetic leg springs are designed with a curved portion mainly focusing on the bending characteristics. However, a prosthetic leg spring that has been designed in consideration of the ease of swinging of the prosthetic leg spring during running in addition to the bending characteristics is not known.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a leaf spring for a prosthetic leg that can improve bending characteristics and can improve the ease of swinging by increasing the rotation property under the knee. .

In order to solve the above problems, artificial leg leaf spring according to the present invention is a prosthetic leaf spring and a curved portion linear portions adapter is attached, the curved portion, the heel portion projecting toward the rear side The height Hb of the most convex point protruding most rearward in the heel portion satisfies 160 mm ≦ Hb in a direction perpendicular to the foot length direction determined with respect to the extending direction of the linear portion as a reference , The length Lt between the most convex point in the foot length direction defined with reference to the stretching direction and the most distal point on the front side of the curved portion satisfies a relationship of Lt ≦ 295 mm.

  According to the present invention, when the prosthetic leg spring is mounted on the prosthetic leg, good bending performance can be obtained and the moment of inertia around the knee joint can be reduced. As a result, it is possible to improve the rotational performance under the knees, and to improve the ease of swinging the leaf spring during traveling.

It is a side view of the leaf | plate spring for artificial legs which concerns on this Embodiment 1. FIG. It is a figure for demonstrating EI distribution of the leaf | plate spring for artificial legs which concerns on this Embodiment 1. FIG. It is a figure which shows the modification of the leaf | plate spring for artificial legs which concerns on this Embodiment 1. FIG. It is a figure for demonstrating the arrangement position of the collar part of this invention. It is a figure for demonstrating the position of the knee joint assumed in this invention. It is a figure for demonstrating the position of the rotating shaft of the knee joint assumed by this invention. It is a side view of the leaf | plate spring for artificial legs which concerns on Example 1 of this invention. It is a side view of the leaf | plate spring for artificial legs which concerns on Example 2 of this invention. 6 is a side view of a prosthetic leaf spring according to Comparative Example 1. FIG. 6 is a side view of a prosthetic leaf spring according to Comparative Example 2. FIG. It is a side view of the leaf | plate spring for artificial legs which concerns on the comparative example 3.

(Embodiment 1)
Hereinafter, the prosthetic leg spring according to the first embodiment will be described with reference to the drawings.

  FIG. 1 is a left side view of a prosthetic leg spring 10 according to the first embodiment. In the following description, the state in which the linear portion 11 of the prosthetic leaf spring 10 is arranged perpendicular to the ground plane G is referred to as a “reference state”, the direction horizontal to the ground plane G is “horizontal direction”, and the ground plane A direction perpendicular to G is defined as a “vertical direction”. In the reference state, the direction in which the toe side is located is called “front side”, and the direction in which the heel side is located is called “rear side”.

In FIG. 1, a prosthetic leaf spring 10 includes a straight portion 11 molded into a plate shape and a curved portion 12 functioning as a leaf spring. The straight portion 11 and the curved portion 12 are integrally molded with a fiber reinforced resin such as a carbon fiber reinforced resin or a glass fiber reinforced resin.
An adapter (not shown) for connecting the socket (not shown) and the prosthetic leg spring 10 is fixed to the straight portion 11. The length of the straight portion 11 in the vertical direction may be a length that can adjust the fixing position of the adapter according to the body shape of the individual, and may be, for example, about 200 mm. By setting the width of the straight portion 11 to about 80 mm, the adapter can be stably fixed. The thickness of the straight portion 11 may be changed according to the weight and material of the user. For example, when the straight portion 11 is molded from carbon fiber reinforced resin, the necessary strength is ensured by setting the thickness to about 5 mm to 10 mm. can do.

The bending portion 12 includes a grounding portion 12a that forms a grounding area with the grounding surface G, an arch portion 12b that provides a clearance between the bending portion 12 in a loaded state and the grounding surface G, and a repulsive force that generates a repulsive force as a bending region. It is comprised from the part 12c. The ground contact portion 12a, the arch portion 12b, and the heel portion 12c are integrally formed. In the first embodiment, each boundary is defined as an inflection point or a change in curvature on the rear side surface of the prosthetic leaf spring 10. Define by points. The thickness of the curved portion 12 may be the same as the thickness of the straight portion 11 or may be gradually decreased from the thickness of the straight portion 11.
Hereinafter, detailed configurations of the ground contact portion 12a, the arch portion 12b, and the flange portion 12c will be described.

  The grounding portion 12a is a grounding area with the grounding surface G, and the shape thereof is preferably an arc shape that curves convexly toward the grounding surface G. The ground contact portion 12a is defined as a range from a tip point Pf positioned at the forefront in the reference state to an inflection point P1 where the downward convex curve direction changes. The horizontal length of the grounding part 12a is preferably about 60 to 100 mm in the reference state. When the ground contact portion 12a has an arc shape, for example, it can be a single curvature arc having a curvature radius of about 200 mm to 250 mm. Moreover, it is good also as a composite circular arc shape which combined the circular arc of multiple curvature.

  The arch portion 12b is a region that provides a clearance between the curved portion 12 and the ground plane G so that the curved portion 12 in a loaded state continues to contact the ground plane G only by the ground portion 12a. The arch part 12b can be a straight line or a curved shape that curves in a convex shape toward the upper side. In this Embodiment 1, it is set as the curve shape which curves in the convex shape toward the upper side, The range is defined as an area | region from the inflection point P1 to the inflection point P2 where the curve direction of an upward convex changes. . When the arch portion 12b has an arc shape, for example, it can be an arc shape with a single curvature having a curvature radius of 150 mm or more. Moreover, it is good also as a compound circular arc which combined the circular arc of multiple curvature. The length of the arch portion 12b in the horizontal direction is preferably 40% to 70% of the total length Lt, and 50% of the total length Lt from the viewpoint of securing a sufficient clearance with the ground contact surface G in a loaded state. A range of ˜60% is more preferable.

The arch portion 12b preferably satisfies the following conditions from the viewpoint of bending rigidity. FIG. 2 is a diagram illustrating measurement points of the bending rigidity EI in the ground contact portion 12a and the arch portion 12b. In FIG. 2, an intermediate point in the horizontal direction of the arch part 12b is P5, an intermediate point between the point P5 and the inflection point P1 is P6, and a central part in the horizontal direction of the grounding part 12a is P7. The P5, P6, P1, bending at P7 stiffness EI, the case of the _{EI 1, EI 2, EI 3} , EI 4 _{respectively,} EI 1 _{~EI 4} satisfies the following (1) to (3).
EI ₁ ≦ EI ₂ (1)
EI ₂ ≦ EI ₃ (2)
EI ₂ ≦ EI ₄ (3)
According to the above conditions (1) to (3), since the bending rigidity of the grounding portion 12a is made higher than the bending rigidity of the arch portion 12b, the grounding state by the grounding portion 12a can be maintained even in a loaded state. it can. Moreover, in the arch part 12b, since the rigidity of the rising surface (between P1 and P6) of the arch is higher than the center P5 of the arch part 12b, it is possible to suppress the entire arch part 12b from being crushed in a loaded state. In addition, a clearance can be secured between the curved portion 12 and the ground plane G. And by making the area | region of the back side rather than the center P5 of the arch part 12b easy to bend, the back side of the curved part 12 containing the collar part 12c can fully be bent, and required repulsive force can be obtained. it can.

Next, referring again to FIG. 1, the heel portion 12 c functions as a bending region that generates a repulsive force of the prosthetic leaf spring 10. The range of the flange portion 12c is defined as a region from the inflection point P2 which is the rear end of the arch portion 12b to the inflection point P4 which is the lower end of the straight portion 11. The flange portion 12c has at least an arc-shaped region 12c ₁ protruding toward the rear side, and the arc-shaped region 12c ₁ includes the most convex point Pb located at the rearmost side in the reference state. Arcuate region 12c ₁ may be, for example, an arc of about a radius of curvature 40Mm～80mm. Moreover, it is good also as a compound circular arc which combined the circular arc of multiple curvature.

Arcuate region 12c ₁ is connected region 12c is connected ₂ to the linear portion 11 via the boundary between the arc-shaped region 12c ₁ and the connecting region 12c ₂ is defined as the inflection point P3. In addition to the quadratic curve shape shown in FIG. 1, the shape of the connection region 12c ₂ may be a curved shape that protrudes forward as shown in FIG. Further, an arcuate region 12c ₁ may be projected directly from the linear portion 11 without passing through the connection region 12c _2.

  Next, a specific arrangement position of the heel portion 12c in the prosthetic leg spring 10 will be described with reference to FIG. FIG. 4 shows the tip point Pf, the most convex point Pb, and the inflection points P1 to P4 in the reference state.

In the reference state, when the horizontal distance between the most advanced point Pf and the most convex point Pb is defined as the total length Lt, and the height from the ground contact surface G to the most convex point Pb is defined as Hb, the flange 12c is 260 mm. ≦ Lt ≦ 310 mm and 150 mm ≦ Hb. The shape of the heel portion 12c, i.e. the shape of the arc-shaped region 12c ₁ and connecting region 12c ₂ is, Lt, and Hb can be any shape as long as satisfying the above range.

  The total length Lt, the height Hb of the most convex point P, and the thickness t of the prosthetic leg spring 10 satisfy the relationship of 0.050 ≦ (Hb / Lt) / t. When the thickness t of the prosthetic leaf spring 10 is not constant, the thickness of the thinnest portion in the bending portion 12 may be set to t.

The reason why the flange portion 12c is in the above range is as follows. The present inventor has focused on the point that the ease of swinging of the prosthetic leg spring can be improved by reducing the moment of inertia around the knee joint of the prosthetic leg spring. As shown in FIG. 5, the moment of inertia around the knee joint includes the distance from the assumed knee joint KJ to the center of gravity CG of the prosthetic leg spring 10 and the mass of the prosthetic leg spring 10 as shown in FIG. 5. It depends on. As shown in FIG. 6, the thigh amputee is determined by the distance from the assumed rotation axis RA of the knee joint to the center of gravity CG of the prosthetic leg spring 10 and the mass of the prosthetic leg spring 10.
In the present invention, the assumed position of the knee joint KJ or the position of the rotation axis RA of the knee joint is the tip on the toe side when the prosthetic leg spring 10 is tilted 13 ° rearward from the reference state. An imaginary axis AX is set perpendicularly to the ground contact surface G at a position 70 mm behind from the ground contact surface G, and is 440 mm above the ground contact surface G of the virtual axis AX.

  In reducing the moment of inertia around the knee joint, in FIG. 4, the shape from the foremost point Pf to the inflection point P2, that is, the shape of the ground contact part 12a and the arch part 12b is made constant, and the horizontal direction of the most convex point Pb. Consider a case where the amount of overhang of the collar portion 12c is changed by changing the position of. When projecting the heel part 12c backward, when the total length Lt is longer than 310 mm, the mass of the prosthetic leg spring 10 increases and the lever arm length becomes longer. Therefore, the required rigidity increases and the plate thickness t also increases. As a result, the moment of inertia around the knee joint increases to the extent that the ease of swinging is affected. On the other hand, when the overhang of the heel part 12c is shortened, if the total length Lt becomes shorter than 260 mm, the amount of bending of the prosthetic leaf spring 10 is reduced and a sufficient repulsive force cannot be obtained. For this reason, it is preferable to arrange the most convex points Pb in the horizontal direction so that the total length Lt is 260 mm to 310 mm.

  Also, consider a case where the shape from the foremost point Pf to the inflection point P2 is a constant shape and the position of the most convex point Pb in the vertical direction is changed. When the height Hb of the most convex point Pb is shorter than 150 mm, the assumed distance between the knee joint KJ and the center of gravity CG of the prosthetic leaf spring 10 increases, and the moment of inertia increases to the extent that the swingability is affected. . For this reason, it is preferable to arrange the most convex point Pb in the vertical direction so that the height Hb of the most convex point Pb is 150 mm or more.

  Furthermore, since the length behind the ground point linearly corresponds to the spring constant of the leaf spring, the required plate thickness increases as the overall length Lt increases when attempting to achieve the target number of springs. The mass becomes heavier. For this reason, it is desirable to increase the ratio of (Hb / Lt) to the plate thickness t together with the ratio (Hb / Lt) of the most convex point height Hb to the total length Lt. As a result of simulation with a spring, it is preferable that 0.050 ≦ (Hb / Lt) / t.

Next, the effect of the prosthetic leaf spring 10 configured as described above will be described.
In order to verify the effects of the present invention, prosthetic leg springs according to the present invention (Examples 1 and 2) and conventional prosthetic leg springs (Comparative Examples 1 to 3) were created by simulation. For the simulation, “SOLID WORKS SIMULATION” manufactured by Solid Works was used. 7 and 8 are views showing the side shapes of the prosthetic leg springs according to the first and second embodiments of the present invention, respectively. Moreover, FIG. 9 thru | or FIG. 11 has each shown the side shape of the leaf | plate spring for artificial legs which concerns on Comparative Examples 1-3. The total length Lt, the height Hb of the most convex point Pb, the plate thickness t, the weight m, the moment of inertia MOI, and (Hb / Lt) of the leaf springs for prosthetic legs according to Examples 1-2 and Comparative Examples 1-3 The value of / t is shown in Table 1.

  In addition, in order to make the number of springs constant in Examples 1 and 2 and Comparative Examples 1 to 3, the thickness t of Comparative Examples 2 to 3 is the same as the thickness t of Examples 1 and 2. It was set as the value corrected based on the length of the rear part from the contact point of ˜3. The moment of inertia MOI was calculated under the following conditions. That is, each prosthetic leaf spring is rotated from the reference state to the toe side, and the horizontal distance between the axis extending vertically from the point 70 mm behind the tip of the reference state and the straight portion of the prosthetic leaf spring is the contact distance. A state where the distance from the ground G was 100 mm at a position 350 mm above was determined as a fixing position of each prosthetic leg spring. At this fixed position, each prosthetic leg spring was rotated about the rotation axis RA shown in FIG.

As shown in Table 1, in Examples 1 and 2, the height Hb of the most convex point Pb is 150 mm or more, and the total length Lt is 310 mm or less. On the other hand, the total length Lt of Comparative Example 1 is the same as that of Examples 1 and 2, but the height Hb of the most convex point Pb is lower than that of Examples 1 and 2. The inertia moment MOI of Comparative Example 1 is slightly higher than that of Examples 1 and 2, and the weight m is slightly heavier than that of Examples 1 and 2.
In Comparative Example 2, the height Hb of the most convex point Pb is higher than those in Examples 1-2, but the total length Lt is longer than those in Examples 1-2. In Comparative Example 3, the height Hb of the most convex point Pb is higher than that in Example 2, but the total length Lt is longer than those in Examples 1-2. The moments of inertia MOI of Comparative Examples 2-3 are higher than those of Examples 1-2, and the weight m is heavier than those of Examples 1-2.

  Next, the ease of swinging the prosthetic leg springs of Examples 1-2 and Comparative Examples 1-3 created as described above was verified. The ease of swinging was verified as follows. First, various actual data obtained when the instep of an athletic athlete who uses a prosthetic leg for a thigh is actually run using the prosthetic leaf spring of Comparative Example 1, and calculated values calculated based on the actual data; Was obtained as master data.

  Specifically, the knee joint extension angle Ang when the prosthetic leg spring is swayed, the average extension angular velocity Vel at the time of swaying, and the time from the maximum bending to the maximum extension of the knee joint (hereinafter referred to as “swing time”). ts was measured. Next, the angular momentum L was calculated based on the obtained average extension angular velocity Vel and the inertia moment MOI of Comparative Example 1.

  Further, from the actual running data of the former, the kicking stride sls of the prosthetic leaf spring and the kicking stride slh on the healthy side are measured, and using both values, the number of steps when running 100 m (hereinafter “ St100 and the number of times of swinging out the prosthetic leg leaf spring during 100 m travel (hereinafter referred to as “100 m leaf spring swing count”) sn100. The data obtained as described above was used as master data. Table 2 shows the values of the master data.

  And when the former uses the prosthetic leg springs of Examples 1 and 2 and Comparative Examples 1 to 3, the knee joint is extended to the same extent as the master data, and the angular momentum of the same degree is exhibited. Assuming that, for each of Examples 1-2 and Comparative Examples 1-3, a swing-out average extension angular velocity Vel was calculated based on the value of the moment of inertia MOI, and a swing-out time ts was calculated based on the determined average extension angular velocity Vel. . Further, from the calculated swing time ts and the 100 m leaf spring swing count sn100 calculated as the master data, the swing time when traveling 100 m (hereinafter referred to as “100 m equivalent ts”) ts100 is shown in Examples 1-2. And it computed about each of Comparative Examples 1-3.

  Table 3 shows the average extension angular velocity Vel, the swing time ts, and the 100 m equivalent ts_ts100 of Examples 1-2 and Comparative Examples 1-3.

  From the swing time ts shown in Table 3, it can be seen that in Examples 1-2, the lower knee part swings faster in one knee extension than in Comparative Examples 1-3. Moreover, in the comparison of 100m conversion ts_ts100 converted into 100m driving | running | working, it turns out that the difference of Examples 1-2 and Comparative Examples 2-3 has appeared notably. Furthermore, in the comparison between Example 2 and Comparative Example 1 where the difference is the smallest in comparison of the swing time ts, there is a significant difference in the value of 100 m equivalent ts_ts100 when assumed to be used in actual competition. A sufficient effect of the present invention can be found.

DESCRIPTION OF SYMBOLS 10 Prosthetic leg spring 11 Linear part 12 Curved part 12a Grounding part 12b Arch part 12c Gutter part 12c ₁ Arc-shaped area | region 12c ₂ Connection area | region

Claims (4)

In a prosthetic leaf spring comprising a straight portion and a curved portion to which the adapter is attached ,
The curved portion includes a collar portion protruding toward the rear side,
In the direction perpendicular to the foot length direction determined with respect to the extending direction of the straight line portion, the height Hb of the most convex point protruding most rearward in the heel portion satisfies 160 mm ≦ Hb,
A length Lt between the most convex point in the foot length direction determined on the basis of the extending direction of the linear portion and the most distal point on the front side of the curved portion satisfies a relationship of Lt ≦ 295 mm.
A prosthetic leaf spring characterized by that. The prosthetic leaf spring according to claim 1,
The assumed moment of inertia around the knee joint is 0.65 × 10 ⁸ g · mm ² or less.
A prosthetic leaf spring characterized by that. The prosthetic leaf spring according to claim 1 or 2,
The height Hb, the length Lt, and the plate thickness t of the prosthetic leg spring are:
Satisfying the relationship of 0.050 ≦ (Hb / Lt) / t,
A prosthetic leaf spring characterized by that. The prosthetic leaf spring according to claim 1,
The curved portion includes an upwardly curved arch portion extending from the collar portion,
A prosthetic leaf spring characterized by that.

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