Artificial foot

S. R. FOGG

ARTIFICIAL FOOT

May 17, 1949.

Filed April 23, 1946 '

2,470,480

Sheets-Sheet 1

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S. R. FOGG

ARTIFICIAL FOOT

May 17, 1949.

Filed April 23, 1946

2,470,480

Sheets-Sheet 2

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<img file="US2470480A_D0003.tif" />

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Attorneys

Patented May 17, 1949

2,470,480

UNITED STATES PATENT OFFICE

2,470,480

ARTIFICIAL FOOT Stanley R. Fogg, Terre Haute, Ind. Application April 23, 1946, Serial No. 664,298

Claims.

This invention relates to an artificial foot and ankle construction by which is made available to the wearer, when pressure is exerted upon the foot portion thereof, all of the various actions, and particularly rectilinear actions, which is possible in a natural foot.

An object of the invention is to provide a novel relatively simple and light weight artificial foot, for permitting the natural action thereof, as in a natural foot, and which is provided with an ankle plate connected and supported relative to the sole portion, in such a manner as to give a spring cushioning and retarding effect similar to the movement of the foot at the ankle joint in a natural foot, and to compensate for the rectilinear action of the foot and angularly with respect to the leg at the ankle joint, which will raise the sole and toe of the foot or lower the same, in the progressive steps as in walking, and also to provide a novel joint and spring connection at the toe which will clear the toe of the ground, the same as in a human foot, as a step is completed and the weight of the body is removed from the back of the foot.

A further object of the invention is to provide a novel pivot joint at the ankle and hydraulic spring cushioning means therefor in conjunction with an ankle plate to which the leg proper is connected, and also a novel ball and socket joint associated with a spring for connecting the pivoted toe section of the foot to the sole thereof at the back thereof, where it joins with the ball of the sole.

Other objects and advantages reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure 1 is a perspective view of an artificial foot constructed in accordance with the invention.

Figure 2 is a side elevation partly in section at the ankle joint and cushioning means at the heel of the foot.

Figure 3 is a view similar to Figure 2 but with the leg portion abbreviated and showing the action of the parts when taking a step.

Figure 4 is an enlarged detail sectional elevation of the ankle joint pivot.

Figure 5 is a detail sectional plan view of the hydraulic cushioning control means, and

Figure 6 is a detail sectional elevation of the resilient connection between the sole and toe.

Referring to the drawings in detail, in which (CI. 3—6) like reference characters designate corresponding parts throughout the several views, the improved artificial foot is shown as comprising a sole plate ί 0 having a heel portion 11, an arch fi portion 12 and a toe portion 13. The toe portion 13 is hinged or pivoted transversely across the sole at its juncture with the ball portion of the latter by means of pivots 14 engaging apertured ears 15 extending upwardly from opposite 10 edges of the ball portion of the sole at the transverse pivot connection by means of a flange IS extending transversely the full width of the toe portion at its rear edge and formed at the outer ends thereof, with the pivot pins 14, or vice versa, is The toe portion is provided with a raised tapered convex frame designed to fit the toe of a shoe, as indicated at 17, and comprising a plurality of spaced longitudinal frame members or wires i 8 of any suitable number, extending from 20 the tip or rounded toe edge at the front and curved upwardly and rearwardly to join at their rear ends, as indicated at 19, to a transverse arched member 20 having its extremities curved downwardly and suitably anchored to the toe por25 tion 13 as indicated at 21 as by riveting, welding, brazing, soldering or otherwise. The members 18 are spaced around the convex front edge of the toe portion 13 and correspondingly anchored at their front lower ends thereto in the 30 same manner as the ends of the arch portion 20, as indicated at 22 and progressively shorter from the center to the outside members. At the rear ends of the outside members 18, which are similarly connected to the arched member 20, a trans35 verse rectilinear frame member 23 is provided with its ends anchored thereto at such points as indicated at 24 and forming the chord of an arc of the arch portion 20 beneath the latter, between said points.

An expansible coil spring or other resilient means 25 is interposed in an inclined position rearwardly from the center of the arched portion, 20 and connecting member 23 to the sole 10 in spaced relation rearwardly at the back of the 45 toe frame 17, and may have its rear extremity suitably anchored in an apertured ear or lug 27 secured centrally of the width of the sole on the ball portion thereof. The upper forward end of the expansible means or spring 25 is pro50 vided with a ball and socket connection with the toe frame permitting universal movement, and for this purpose, a hemi-spherical cup 28 is fitted or set in the forward end of the spring 25 at the end coils thereof, and has a flanged top edge 55 _or rim 29 turned over the outside of the top coil

2,470,480 or convolution of the spring to grip and retain the cup in position. The flanged edge of the cup extends beyond the point of the largest diameter thereof, to receive and retain a ball member 30 therein for angular movement, and has a two point connection with the toe frame 17 by a multiple or pair of arms 31 rigid with the ball member and attached to the arched portion 20 and brace member 23 centrally of the lengths thereof and width of the toe at this point. The purpose of this, arrangement is to give a round firm bearing surface for the collar supporting spring in order that the spring will remain in line at all times. At the same time, the toe portion 13 will be retained in rectilinear alignment with the sole portion and will be, allowed the necessary angular movement with respect there-, to, in walking, and permitting the rear portion of the artificial foot to move upwardly and; downwardly relative thereto, as well as to cause the hinged toe portion to align with, the sole proper by. reason of the. joint and-.resilient means or spring,which.controls,the same,, so, that the natural. recoil of the toe as, the. foot- is lifted from, the ground or at the, completion of a step, is attained..

A .suitable leg portion ,32..is shown: connected or pivoted for angular movement with respect to the foot portion at the· ankle,joint. 33, and may comprise a; suitable, outer shell, or wall as shown, with interior reinforcing, and. frame members or wires 34 bracing the same, in connection with an ovate or lenticular longitudinally extending ankle.plate. 35 at the bottom, of the leg portion. For ithis purpose, the, lower end- of&gt; the leg portion at, the .shell,.and· interior reinforcing frame 34, is rigidly. attached,, to · the top, of, the ankle plate, in any suitable way,, as by riveting, welding, bracing, or otherwise..

Mounted, between the ankle plate, 35 and. the heel of the sole is a. hydraulic ally controlled ankle, joint or pivot 36 including a. cylindrical wrist pin. 37 -mounted , in. a hinge or, sleeve· comprising a central section 38 welded or- otherwise fixed· to the ankle plate· 35·.transversely,, at a point intermediate the length-thereof as-shown at 39 and, a pair of end sections. 4,0 'abutting the ends of the central section. 38 around the wrist pin. or hinge 37. with an interposed fibre -or sound silencing and cushioning bushing .41 between the. sections and· the pin if desired. The sections, 40· are supported at an elevated, position spaced above the heel portion of the sole and, held rigidly' against turning, by-a, suitable-frame structure· including spaced parallel 'vertical rods 42, forwardly inclined and· divergent rods 43 extending to the side edges and front end of the sole plate,in rear, of the toe portion 13? and anchored-thereto, with a transverse upwardly arched intermediate brace-rod .44' and downwardly divergent and slightly, rearwardly inclined brace rods 45 at the-back of the heel, all- rigid with, or fixed to the end· sections 40,

A base plate 46 is. mounted on the heel portion 11 of the foot plate or sole 1'0 and mounts a pair of front and rear vertical cylinders 47 spaced apart longitudinally and located centrally of the width of the heel and base plate with their upper ends positioned beneath the ends- of- the ankle plate, 35. Pistons or plungers 48 operate vertically in the cylinders 47 and have connecting rods 49. pivotally connected at 56 by suitable, bearing brackets or, otherwise, to the bottomface of the ankle plate 35. The plungers are normally, held.raised.by central, compression springs 5i disposed between the pistons and the closed lower’ ends of the cylinders to give a desired degree of resistence and cushioning effect as well as upward movement of the cylinders in 5 walking, during the angular movement of the foot and leg portions relative to each other and under the weight of the person equipped with an artificial leg and foot. This resistence and cushioning effect is increased by springs 52 concen10 trically encircling the springs 5Γ below the upper portions of the latter and· also resting on the closed lower ends of the cylinders, so that under the extreme weight of the body or pressure in walking, greater resistance is offered to the 15 downward movement outwardly of the pistons or plungers 48.. A suitable hydraulic fluid, such as oil, or air, within the cylinders and the flow thereof from one cylinder to the other at the bottom may be effected through the medium of 20 a by-Pass or duct 53 in the base plate 46 or other form of conduit connecting the lower ends- of the cylinder- chambers and controlled; by a needle valve or, the like 54 operating in a. threaded· bore formed as. a continuation of the longitudinal por25 tion of the passage 53 at one end of-the base plate or other interiorly threaded·;: extension, thereof and adapted to be turned by a T-head or pin 55 or other form of knob, or handle, so as to control the flow of the fluid, through, the passage 53 at 30 its vertical connection with the chamber of one of the'cylinders 47,. preferably,· the forward one at the tapered end of the valve.

By the construction described, the ankle joint or pivot is. hydraulically controlled but, preferably. 35 allowed a full 90° arc of swing, while the toe portion at its hinged.connection'.and. resiliently or· spring controlled as. described·; is· allowed-a maximum swing in an arc of 60°. Thus, in walking proper angular, movements, .are - allowed.· relatively.. &lt;0 between, the leg portion.· 32 and the foot at the, ankle joint; and also between-the toe plate and the sole. The two compensating hydraulic cylinders or cushioning means between the- leg. and thus the ankle plate · and· the foot plate or sole, 45 automatically, adjusts the· position-,of the· ankle plate with respect, to, the foot.plate at the,ankle-.joint and to the position, which.-is,natural· to-the. function- it is performing during·, the walking:; movement, so that at each step, as pressure is. 50 exerted,upon the pistons, either the front,, or rear, pistons or plunger is.depressed! withimits cylinder·;;, causing compression on its., respective · springs·,: first of the weaker springs 51, and· then of; the: surrounding springs 52 until.the maximum of the 55 arc: of swing .-is attained, and, the.'entire. weight of· a body applied to the artificial, foot While· one piston, is; depressed, the, other, is, raised, on, their outward and· inward,- strokes-,respectively;·, .with,, the springs expanding or pressing against the,-.· CO pistons to maintain constant, pressure, between them, and the foot plate or sole so that the. ankle movement is accomplished in a smooth and noise.less manner. Also,,,by.having,.:the coil springs rest at. all times in, rubber:·, cushioning·; discs? 56, 65 between the springs and the lower, ends of· the·: pistons, to. seal, the.hydraulic, fluid, within? the. cylinders and from escaping,uro.und,.the-latter,and?; between the same and,theinner..walls,of.the,cylr, inders, is. prevented:..by , a. simple,,and,., efficient 70 form of packing. Thus,.as,the .ankle plate, tilts.· · downwardly, in, front,, the., weight ..of; the,,.body transmitted.by. means of, the. f rame.work to the, toe,, causes the,,spring 25..,to,. be ^compressed or, coil, elevating; the, plane, of,the, rear,of..the. sole·,at., 7ft; the ankle, or hinged Joint 33,. as,shown,in,Figure

2,470,480 of the drawings. As the weight is lifted, the spring 25 recoils, lifting the foot clear and permitting it to be swung forward to complete the step. On raising the foot from the ground, the spring 25 maintains the toe portion of the sole or foot plate ί 0 in alignment therewith as shown in Figures 1 and 2 of the drawings. Then, as the heel is set down, the action in the other cylinder by reason of the hydraulic cushion and spring action on the pistons, cushions the downward and rearward movement of the leg and foot at the heel, duplicating that of the forward piston in the first or initial stage of the step. This compresses the springs 5i and 52, until the foot is level on the ground, when the springs act uniformly tending to level the ankle plate 35 when the leg portion is vertical. This movement is cushioned by the resistance to the downward movement of the pistons by the fluid contained in the cylinder at the back, while pressing against the forward pistons, assisted by the action of the expansible springs therein. Adjustment of the needle valve controlling the passage of the fluid through the feeder tube or passageway produced by the duct 53, controls the volume of fluid passing into the respective cylinders on the opposite movement of the pistons therein, so that the walking action can be suited to the particular person and regulated to a nicety. This will also permit adjustment to compensate for the variations in the weight of different wearers.

Particular attention is called to the fact that the hinge flange which extends the full width of the toe plate or frame, swinging on the pin formed by the frame or ball portion of the sole plate IΘ, of the body of the foot, insures positive alignment of the plate portions at their pivoted edges, the purpose of the hinged flange being to make possible the same spring reaction which clears the toe of a human foot as a step is completed and the weight of the body is removed from the back foot. It should also be noted that all mechanical parts are located below the ankle plate and are therefore arranged compactly to facilitate the movements as well as the construction and assembly of the device and all parts may be of steel tubular construction, including the framework, if desired, assuring maximum strength and minimum weight.

In view of the foregoing description taken in conjunction with the accompanying drawings it is believed that a clear understanding of the construction, operation and advantages of the device will be quite apparent to those skilled in this art. A more detailed description is accordingly deemed unnecessary.

It is to be understood, however, that even though there is herein shown and described a preferred embodiment of the invention the same is susceptible to certain changes fully comprehended by the spirit of the invention as herein described and the scope of the appended claims.