Shoe sole for leg apparatus

A leg apparatus shoe sole has an upper sole member and a lower sole member interconnected by expanders so as to be movable towards and away from each other wherein the expanders are connected with a remote actuator by a drive wire. The actuator is operated to reduce the thickness of the shoe sole when the associated leg is the free leg and to increase its thickness when the associated leg is the supporting leg.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a shoe sole for a leg apparatus that serves as an 
ambulatory apparatus for persons paralyzed in both legs. 
2. Description of the Prior Art 
Injuries to the cervical or spinal vertebrae caused by automobile 
accidents, falls and the like can paralyze the upper and lower limbs. Many 
persons handicapped by such injuries are instantaneously committed to life 
in a wheel chair. Although wheelchairs provide the handicapped with good 
mobility, they have numerous drawbacks from medical and psychological 
viewpoints. Among the ambulatory apparatuses devised for overcoming these 
disadvantages of the wheelchair is the parawalker developed in the U.K. 
The user of,this apparatus has all of his or her lower body aside from the 
hip joints immobilized and moves forward by twisting the upper body. Since 
ambulation by twisting requires clearance between the free leg and the 
floor, the user has to tilt his or her body by a large angle. Walking 
therefore becomes a very strenuous activity. It is possible to eliminate 
the need for large body tilting and reduce the burden on the user by 
shortening the length of the free leg from the time it leaves the floor 
and lengthening it again when it comes in contact with the floor to once 
more serve as the supporting leg. As a mechanism for achieving alternate 
lengthening and shortening of the legs there has been developed a leg 
apparatus able to vary the thickness of a shoe sole. (See Japanese Patent 
Public Disclosure Hei 4(1992)-352961, for example.) 
FIG. 7 shows such a sole developed earlier for enabling thickness 
adjustment. As illustrated, the sole 100 has a two-tier sole structure 
consisting of an upper sole member 101 and a lower sole member 102 
connected by a pair of linkages 106 each constituted of a pair of links 
103 and 104 and a pivot 105. The thickness of the sole 100 can be changed 
by bending land straightening the linkages 106 to move the upper sole 
member 101 and the lower sole member 102 toward and away from each other. 
As indicated by reference numerals 107 in FIG. 7, pneumatic cylinders or 
the like can be used as the actuators for bending and straightening the 
linkages 106. Since the actuators 107 are mounted between the upper and 
lower sole members 101, 102 of the sole 100, however, they increase the 
weight of the sole 100 and place a greater burden on the user. In 
addition, the presence of the actuators 107 between the upper and lower 
sole members 101, 102 limits the degree to which the thickness of the sole 
100 can be reduced. 
The present invention was accomplished in view of the foregoing 
circumstances and has as its object to provide a leg apparatus shoe sole 
which enables the thickness of the sole to be changed with ease, does not 
place a heavy load on the feet of the user, is simple in structure and 
allows great reduction of the thickness of the shoe sole on the free foot. 
SUMMARY OF THE INVENTION 
For achieving the aforesaid object, the present invention provides a leg 
apparatus shoe sole with a two-tier structure having vertically spaced 
upper and lower sole members movable toward and away from each other, the 
shoe sole comprising: expanders for expandably connecting the upper and 
lower sole members and drive means for driving the expanders, the 
expanders including at least a pair of linkages each constituted of an 
upper link and a lower link swingably joined by a first pivot, the upper 
end of the upper link being connected with the upper sole by a second 
pivot, and the lower end of the lower link being connected with the lower 
sole by a third link, and the drive means including at least one actuator 
located at a position remote from the linkages, at least one drive wire 
means driven by the actuator for synchronously driving the pair of 
linkages between a basic attitude in which the linkages are bent outward 
and an expanded attitude in which the linkages are straightened 
vertically, and restoring means for restoring the expanded linkages to 
their basic attitude. 
Various other objects, features and attendant advantages of the present 
invention will be more fully appreciated as the same becomes better 
understood from the following detailed description when considered in 
connection with the accompanying drawings in which like reference 
characters designate like or corresponding parts throughout the several 
views and wherein:

DESCRIPTION OF THE PREFERRED EMBODIMENT 
An embodiment of the leg apparatus shoe sole according to this invention 
will now be explained in detail with reference to the drawings. The shoe 
sole, designated by reference numeral 1 in FIGS. 1 to 3, constitutes the 
lower end of a leg apparatus 2 to be worn by a person (the user) who is 
paralyzed from the waist down. The shoe sole 1 has a two-tier structure 
comprising an upper sole member 3 and a lower sole member 4 spaced from 
each other vertically. As shown in FIGS. 4(b) and 4(c), the upper sole 
member 3 and the lower sole member 4 are rectangular in plan view. The 
upper surface of the upper sole member 3 is made of, for example, a metal 
such as aluminum and the bottom surface of the lower sole member 4, which 
makes contact with the ground, is made of rubber, synthetic resin or the 
like. 
The four corners of the upper sole member 3 are formed with rectangular 
notches 51 and an upright connecting arm 52 is fastened in each notch. 
As shown in FIGS. 2 and 3, the upper sole member 3 and the lower sole 
member 4 are connected at opposite ends by pairs of expanders 5 so as to 
be vertically movable toward and away from each other. When the separation 
between the upper and lower sole members 3 and 4 is large, the thickness 
of the sole is large, and when it is small, the thickness of the sole is 
small. The expanders 5 comprise a pair of first linkages 6a connecting the 
forward ends of the upper and lower sole members 3 and 4 and a pair of 
second linkages 6b connecting the rearward ends of the upper and lower 
sole members 3. Each of the first and second linkages 6a, 6b comprises an 
upper link 7 and a lower link 8 and a first pivot 11a or 11b swingably 
connecting the lower end of the upper link 7 with the upper end of lower 
link 8. 
The upper end of each upper link 7 is swingably connected to near the upper 
end of one of the connecting arms 52 standing upright on the upper sole 
member 3 by a second pivot shaft 12, while the lower end of each lower 
link 8 is swingably connected to the lower sole member 4 by a third pivot 
shaft 13. The linkages 6a and 6b are in their most expanded state when the 
upper and lower links 7 and 8 lie along a vertical line. When the linkages 
6a, 6b are in this expanded attitude, the vertical distance between the 
upper and lower sole members 3 and 4 is greatest, which is to say that the 
thickness of the shoe sole 1 is maximum (see broken lines in FIG. 2) 
A stop 42b is provided to extend upward from the side edge of the lower 
sole member 4 at a position just inward of the point of connection of each 
lower link 8 (four stops in total). In addition, a stop 42a is provided to 
extend upward from the upper surface of the upper sole member 3 at a 
position just inward of the point of connection of each upper link 7 (four 
stops in total). The stops 42a, 42b prevent the linkages 6a, 6b from 
bending farther inward than the expanded attitude 14 indicated in FIG. 2. 
The height of the connecting arms 52 which swingably support the upper 
links 7 is selected such that the angle .theta. between the upper link 7 
and the lower link 8 (see FIG. 3) will be greater than zero when the shoe 
sole 1 is thinnest and the upper and lower sole members 3 and 4 are almost 
in contact with each other. This is to reduce the amount of force required 
to expand the sole from its thinnest state. 
The linkages 6a, 6b of the expanders 5 on each side of the shoe sole 1 are 
bent and straightened by a drive mechanism 20. As shown in FIGS. 5 and 6, 
each drive mechanism 20 is equipped with an actuator 21 and a drive wire 
22. The actuator 21 comprises a stationary member 23 and a moving member 
24. It can be constituted as a pneumatic cylinder, for example. The 
actuator 21 is attached to the leg apparatus 2 in the vicinity of the 
waist of the user. The drive wire 22 consists of a tubular outer cable 26 
and an inner wire 27 that passes through the interior of the outer cable 
26 so as to be movable in the longitudinal direction with respect to it. 
In other words, the inner wire 27 is enclosed by the outer cable 26 but is 
free to move longitudinally inside the outer cable 26. The lower end of 
the inner wire 27 is connected to the point of connection between the 
upper and lower links 7 of the linkage 6a. Although the end of the inner 
wire 27 is connected to the first pivot 11a in the illustrated embodiment, 
it can instead be connected to near the lower end of the upper link 7 or 
near the upper end of the lower link 8. In the illustrated embodiment, the 
inner wire 27 passes back through the first pivot 11b of the second 
linkage 6b and the outer cable 26 to have its base end connected to the 
moving member 24 of the actuator 21. The inner wire 27 does not have to 
pass through the second linkage 6b at the first pivot 11b, however, and 
can instead pass through it in the vicinity of the lower end of the upper 
link 7 or in the vicinity of the upper end of the lower link 8. In any 
case, preferably it passes at a point corresponding to the place where, as 
explained later, the tip of the outer cable 26 abuts linkage 6b as shown 
in FIG. 5. In the illustrated embodiment, the inner wire 27 passes through 
a through-hole 28 formed to pass diametrically through the first pivot 
11b. The leading end 33 of the outer cable 26 is fastened to the first 
pivot 11b of the second linkage 6b by a fastener 35. The fastener 35 is 
formed with a through-hole 36 which is aligned with the through-hole 28 of 
the first pivot 11b and the inner wire 27 passes through the aligned 
holes. The base end 37 of the outer cable 26 is fixed to the stationary 
member 23 of the actuator 21. 
A shape restoring mechanism 40 is provided between each upper link 7 and 
the upper sole member 3. In the illustrated embodiment, each of the shape 
restoring mechanisms 40 is constituted by a spring 41 having one end fixed 
to the associated connecting arm 52 and the other end fixed to the upper 
link 7 so as to urge the upper link 7 upward and thus urge the linkage 6a 
or 6b to bend outward. The invention is not limited to this arrangement, 
however, and any spring means providing a similar action can be used 
instead. 
As shown in FIG. 3, when the drive mechanism 20 is not acting on the 
linkages 6a and 6b, the springs 41 urge the upper and lower sole members 
3, 4 almost into contact with each other (the basic attitude), as is 
possible since the stops 42a, 42b do not interfere with each other or with 
the upper and lower sole members 3, 4. 
The operation of the shoe sole of the foregoing configuration will now be 
explained. 
When a leg of the user 10 becomes the free leg, i.e., when it begins to 
move forward after completing a rearward kick, it is necessary to reduce 
the thickness of the shoe sole 1. This is achieved not by the actuators 21 
but by the action of the springs 41 pushing the upper links 7 outward when 
the linkages 6a, 6b are free of the action of the actuators 21, with the 
result that the linkages 6a , 6b are bent outward so that the upper and 
lower sole members 3, 4 approach each other and enable the shoe sole 1 to 
assume minimum thickness. Then when the same leg of the user 10 becomes 
the supporting leg, i.e., when it begins a rearward kick after reaching 
the limit of its forward swing, it is necessary to increase the thickness 
of the shoe sole 1. For this, the actuators 21 are operated to pull the 
inner wires 27. As will be understood from FIG. 3, the force of each inner 
wire 27 acts to pull in the first pivot 11a of the associated linkage 6a 
inward by a distance , thus causing the linkage 6a to straighten, while 
the reactive force of the outer cable 26 acts to push in the first pivot 
11b by the same distance , thus causing the second linkage 6b to 
straighten. As a result, the shoe sole 1 expands to a prescribed 
thickness. When the force of the actuator 21 is released, the leaf or coil 
springs 41 attached to the upper portions of the respective upper links 7 
apply a moment of force to the linkages 6a, 6b so as to bend them outward, 
whereby the shoe sole 1 is made thin again. When the thickness of the shoe 
sole 1 is minimum, the upper and lower sole members 3, 4 are almost in 
contact with each other. The movement of the upper sole members 3, 4 
toward each other is not hindered since the upper links 7 and the stops 
42a, 42b are located so as not to interfere with each other or with the 
upper and lower sole members 3, 4. Since the height of the connecting arms 
52 is determined such that an angle .theta. (.theta.&gt;0) is maintained 
between the upper links 7 and the lower links 8 when the distance between 
the upper sole members 3, 4 is minimum, the linkages are not allowed to 
move to their dead points and can be readily expanded again in the next 
walking phase. 
When a load is applied from above to the linkages 6a, 6b at the time they 
are in their expanded attitude 14, they are subject to a force acting to 
bend them inward or outward. This is not a problem, however, since outward 
bending of the linkages 6a, 6b is prevented by the pulling force of the 
inner wire 27 and the pushing force of the outer cable 26, while inward 
bending thereof is prevented by their collision with the stops 42a, 42b. 
As a result, the expanded state of the shoe sole 1 can be maintained. 
Since the shoe sole 1 configured in the manner described in the foregoing 
does not require the actuators 21 to be located between the upper and 
lower sole members 3, 4 but only the inner wires 27 and the stops 42a, 42b 
to be located therebetween, the weight of the shoe sole is not 
substantially increased. In addition, the fact that the actuators 21 are 
not present inside the shoe sole means that they do not hinder the folding 
of the linkages 6a, 6b when the thickness of the shoe sole 1 is reduced. 
The degree to which the thickness of the shoe sole can be reduced is thus 
proportionally greater and, as a result, the range over which its 
thickness can be varied is also proportionally greater. Since these 
features of the shoe sole make it possible to avoid increasing the burden 
on the user, the user is able to walk with greater ease. In addition, the 
elimination of linkage dead points ensures smooth linkage bending and 
straightening. 
In the shoe sole 1 constituted as described in the foregoing, the sole 
thickness can easily be varied over a range of 30-40 mm by operation of 
the actuators and linkages. Further, since the actuators are located at a 
position remote from the linkages and not between the upper and lower 
soles, a heavy load does not act on the user's feet. The invention thus 
provides a shoe sole for a leg apparatus that is simple in structure and 
allows great reduction of the thickness of the shoe sole on the free foot.