US2885687A - Artificial legs - Google Patents

Description

May 12, 1959 J. E. KELSEY ARTIFICIAL LEGS 3 Sheets-Sheet 1 Filed March 6, 1956 INVENTOR. v

jAMfjil fz fy BY y 2, 1959 Jz-E. KELSEY 2,885,687

ARTIFICIAL. LEGS s Sheets-Sheet 2 Filed March 6, 1956 INVENTOR. .f/I/i/[SLTKfLSE/ By y 1959 J. E. KELSEY 2,885,687

ARTIFICIAL LEGS Filed March 6, 1956 3 Sheets-Sheet 3 IN VEN TOR. J/M/[SE KELSEV Uni States Patent ARTIFICIAL LEGS James E. Kelsey, Unionville, Ohio Application March 6, 1956, Serial No. 569,823

3 Claims. (Cl. 3-26) This invention relates to subject matter classified as artificial body members; and relates particularly to artificial legs of the type that comprises a hinging knee joint between a lower leg portion and a thigh portion.

Such artificial legs are, in general, well known; and certain essentials in the construction thereof have long been known.

Among these are, that the knee joint must hinge freely and allow the knee of the leg to bend at times, for example, when the wearer sits down; but at times when the wearer is walking, or even standing still, bending of the knee by hinging at the knee joint must be prevented, because, being out of control of the will of the wearer, if the knee is free to bend, the leg may collapse under the weight of wearer, and he will fall.

In the attempt to provide an artificial leg that will not fail in this manner, many constructions have been proposed to automatically lock the knee against bending when the leg is straightened out and when the weight of the wearer is put on the leg.

Such prior constructions of leg, of which I am aware, include an artificial foot, comprising a heel and toe; with a hinging connection between the foot and the lower end of the leg, at a point on the foot between the heel and toe, thus simulating movement of the human foot at the ankle. A lock mechanism is provided at the knee joint and is operated to lock and unlock the knee, by hinging movements of the foot, transmitted from the foot to the lock mechanism by a mechanical transmission built into the lower leg and extending upwardly therethrough.

The primary objection to such prior constructions is that hinging movement of the foot is utilized to operate the lock mechanism; and therefore hinging movement of the foot must be coordinated by the wearer with the hinging movement of the lower leg at the knee, to lock and unlock the knee joint at times when the lower leg is in the hinged position at which locking is wanted.

In prior constructions, this coordination is best effected by a construction which constrains the foot to take up a normal hinged position at which the transmission maintains the knee joint unlocked, and which causes the transmission to operate the lock mechanism to locked condition when the foot is rocked out of said position by the wearer, by pressure on the heel effected by the wearer upon putting his weight upon the leg.

Butwith such constructions there are times when the weight of the wearer is put upon the toe or upon the whole foot, both heel and toe, and the foot is not rocked to lock the knee, and the leg collapses under the wearers weight.

Another objection to such prior legs is the complication of construction introduced by the provision of the transmission between the foot and the knee lock; and the consequent excessive cost of manufacture, and maintenance.

The artificial leg of the present invention comprises, in general, the following features of construction and mode of operation; the actual invention being set forth in the appended claims.

The leg has a foot on its lower end; and has a knee joint on which the lower leg bends or hinges on a transverse hinging axis.

A lock mechanism is incorporated in the hinging knee joint, self-contained therein. The lower leg also has a slight lost motion movement at the joint, in the longitudinal direction of the leg, when the lower leg is in the straightened out or unbent position. With the lower leg in this position if the wearer puts weight on the leg and thereby presses the foot on the ground, the lower leg moves upwardly, relatively, to take up said lost motion. The lock mechanism is operated by this upward lost motion movement of the lower leg to lock the kneejoint against bending or hinging movement. When the wearers weight is taken off, the lower leg returns downwardly by gravity, to the extent of the lost motion, and this restores the lock mechanism to unlocked condition.

The foot is, preferably, hingedly connected to the lower leg; but it may be rigid therewith, if desired, in the interest of low cost.

The lock mechanism is constructed to be operated from unlocked to locked condition, and vice versa, by a very small extent of said lost motion, so that the lost motion is not perceptible by the wearer; and so that it emits no impact or other sound when being operated.

The principle of the lock mechanism is that of a brake band, expanded outwardly to frictionally engage and grip a surrounding wall of a housing that encloses the mechamsm.

A lever device in the housing, is operated by said lost motion to expand the brake band, with great leverage ratio.

The brake band also rotates in the surrounding housing wall and provides the bearing on which the lower leg pivots at the knee joint.

While as mentioned, the lock is actuated when the lower leg is in straight leg position, provision is also made by which, when desired, it will lock the knee joint against bending in a preselected range of bent knee angles, for example 15 degrees, from straight position, and prevent locking beyond that position.

The objects of the invention are to provide:

An artificial leg with a locking knee joint construction, having the structural features and mode of operation briefly described above;

A locking mechanism, per se, for artificial legs, as briefly described above.

An embodiment of the invention is fully disclosed in the following description taken in conection with the accompanying drawing in which:

Fig. 1 is a side elevational view of an artificial leg showing the visible parts of an improved locking joint construction;

Fig. 2 is a view of the joint construction of Fig. 1, drawn to a larger scale, approximately full size;

Fig. 3 is an elevational view taken in the direction of the arrow 3 of Fig. 1, and drawn to larger scale, approximately full size;

Fig. 4 is an elevational view of the locking mechanism, per se, as a self contained unit, the view being taken in the direction of the arrow 4 of Fig. 2;

Fig. 5 is a cross sectional view taken from the plane 5-5 of Fig. 4;

Fig. 6 and Fig. 7 are longitudinal sectional views taken from the planes 6-6 and 7-7 of Fig. 5;

Fig. 8 is a cross sectional view, somewhat diagrammatic, taken with respect to the plane 8-8 of Fig. 4;

Fig. 9 is a view similar to Fig. 8, with parts in different positions;

Fig. 10 is a somewhat diagrammatic view illustrating a modification.

Referring to the drawing, Fig. 1 there is shown an arti- 3 ficial leg havinga' thigh portion 1 and a lower leg portion 2, hereinafter referred tosimply asthigh and. lower leg.

A foot 3 on the lower leg identifies the front and back of the leg.

The lower leg 2 and thigh 1 are conuectedat a hinging kneejoint indicated generally at 4 on which the lower leg 2 may swing rearwardly to bent knee positions orforwardly to the straight leg position of: Fig. 1.

An important part of the inventionresides in the knee joint construction 4 and a description of it in detailfollows.

A barrel form housing, comprising a generally cylindrical' tubular side wall 5,. squared off at its ends, and opposite circular end heads or plates 6-7, is supported in a transverse bore-8 of the thigh, and extends out ofthe. bore at both ends, see Fig. 3.

'The tubular side wall has outer axially extending keys 9-10 on diametrically opposite sides, .in key" ways 12-12 opening laterally-from the. bore, which predetermine a rotated position of the housing in the bore, and lock it against rotation therein. A screw 11A extends through the thigh from its front side and is screwed into a threaded hole 12A in the housing key 9 to predetermine an axial position of the housing in the bore and lock it against axial shifting.

Stop lugs 13-13 mounted on the ends of the key 9 by screws 14-14, overlap the end plates 6-7 for a purpose to be described.

The housing as thus far described may be made as a self-contained unit, as shown in Fig. 4 and may be mounted on or removed from the leg by sliding it axially in or out of the bore 8.

The inside of the housing wall 5 is made cylindrical, and is lined with a thin tubular metal liner 15", preferably of brass or bronze, retained therein against shifting in any suitable manner, preferably by tightly fitting the same in the housing wall 5.

The inside surface of the liner 15 is. cylindrical.

Within the liner 15 is a mechanism element, in the form of a thin metal band 16 preferably of steel, having an outer cylindrical surface fitting on the inside cylindrical surface of the liner 15 with a sliding fit.

As will appear later, this band 16, normally has rotary or oscillatory sliding movement in the liner; and the liner and band then constitute the stationary and movable parts of a sleeve type bearing supporting the lower leg 2 for bending movements; and the band 16 is also operable to be pressure-engaged with the liner 15 to lock the lower leg 2 against bending movement.

Two through bolts 17-18, spaced apart, and approximately diametrically opposite, extend axially through the housing wall 5; and comprise threaded ends 19 of reduced diameter, providing shoulders 20 at the inner terminations of the threads. The bolts 17-18 extend through holes in the end plates 6-7 with the shoulders 20 approximately coplanar with outer surfaces of the end plate 5. Nuts 21-21 are screwed ontothe threaded ends 19 and into tight engagement with the shoulders 20.

The nuts 21 thus hold the'plates 6-7 toward and upon the ends of the housing wall 5 with a sliding. fit therewith.

A metal tube. 22, see Figs. 5 and 6, is welded as at 23 to the inside of the band 16, and. the bolt 17 goes through this tube with a sliding fit. The band 16 and tube 22 are co-extensive axially, but shorter axially than the housing wall 5 and bushings 24-24 are provided on the bolt 17 between the: end plates6 and! and the ends of the tube 22, to center the band 16 axially in the housing liner 15'.

A mechanism lever 25, to be more fully described, has a tubular eye 26 at one-end, normally resting upon a bracket 27 welded to the inside of the band 16 so as to dispose the eye approximately diametrically opposite to the tube 22.

The other bolt 18, see Fig. 7, goes through the en plates 6-7 and through the lever eye 26,. and has shoulders and nuts as described for the bolt 17.

The band 16 is not completely circular in cross section, having confronting ends at 28-29 Fig. 5, adjacent to each other, and parallel to each other and to its axis, providing an axially extending space 30 therebetween.

In the position of the parts, in Fig. 5 in which the bolts 17-18, in the tube 22 and lever eye 26, are approximately in horizontal alignment, the space 30 between the band ends is above the tube 22 and the ends of the band may be referred to as the upper end 28 and lower end 29.

A pair of axially spaced hangers 31-32 are welded to the inside of the band 16, inwardly of the upper band end 28, and a pivot pin 33 parallel to the axis is secured at its ends in the hangers.

The said lever 25 has another lever eye 34 spaced from the said lever eye 26, pivoted on the pin 33 between thehangers 31-32, see'Figs. 5 and 6.

The lever 25' extends substantially diametrically across the band 16 between the bolt 18 and the pin 33, and radially outwardly beyond the pin, has ashort finger 35 projecting through the said space 30 between the band ends 28-29 and lying upon the lower band end 29.

The lever eye 26 normally rests upon the bracket 27 welded to the inside of the band 16, and is held thereon by a spring 36 connected between spring eyes 37-38 on. the lever 25 and on the inside of the band 16.

The parts above described comprising the band 16,- tube 22, brackets 27, lever 25, hangers 31-32, pin 33 and spring 36, are assembled as a self contained unit, that can be slid into or out of the housing liner 15 by virtue of the normal sliding fit of the band in the liner.

The lower leg 2 has metal straps 39-39, Figs. 2 and.3., secured at one end to the lower leg 2 in any suitable manner, for example by laying them in grooves 40 in the inner wall of the lower leg 2 and by screws 41-41. The straps 39 extend upwardly out of the lower leg and overlap the end plates 6-7, and are rigidly secured thereto by screws 42-43.

In operation, the weight of the lower leg 2 when hanging from the knee joint, is transmitted by the straps 39-39 to the end plates 6-7, and from the end plates to the mechanism band 16, partly by way of the bolt 17 and tube, 22; and partly by way of the bolt 18 and lever eye 26 on the bracket 27.

The band 16 within the liner 15 is rotatably supported on the liner, or on the lower partthereof, as viewed in Fig- 5'.

The lowerv leg 2 can therefore swing rearwardly. from its normal straight leg position of Figs. 1 and 2 to bent knee positions, the band 16 in the liner 15 being rotated therein and the band and liner constituting a sleeve type bearing.

When the lower leg 2 isin the normal straight leg position of Figs. 1 and 2 and the heel of the foot is pressed upon the ground; there will occur an upward thrust through the lower leg.

This upward thrust is communicated to the end plates 6-7 and thence through the bolts 17-18 to the bolt tube 22' andv lever eye 26.

The lever eye 26 resting by spring pressure on the bracket 27, will yield to this upward thrust, and willrise from the bracket 27 and rock the lever 25 around its pivot pin 33, clockwise as viewed in Fig. 5, causing the lever finger 35 to be pressed upon the lower band end 29' and rock thereon as on a fulcrum.

This will raise the pivot pin 33, carryingwith-it' the upper end 28' of'the band.

The upper and lower ends 28-29 of the band are thus forced apart with great leverage force, in efiect expanding the band 16 into tight gripping engagement with the housing liner 15 within which it fits; and thereby locking the band to the liner and housing, and correspondingly locking the end plates 6-7 and straps 39 and lower leg 2 against rotary or oscillatory movement.

Upon removing the foot heel from pressure with the ground, terminating the said upward thrust, the weight of the lower leg 2 will release the lock by relieving the thrust on the lever eye 26, aided by the spring 36.

When the lower leg 2 is unlocked as described it has unlimited hinging movement rearwardly; but forwardly is stopped in the straight leg position of Figs. 1 and 2 by abutting engagement of two of the nuts 21 with the ends of the lugs 13 as shown in Figs. 2 and 3.

The lower leg 2 and the end plates 6-7 may thus be said to have up and down lost motion; but of very small extent, only enough to produce and relieve the pressure between the band 16 and the liner 15. The only parts that engage and disengage during locking and unlocking, are the eye 26 of the lever and the bracket 27, and their relative movement is so slight that they emit no clicking or other sound; and the movement is not perceptible by the wearer of the leg.

In the foregoing the locking of the knee joint against bending is described as a positive rigid lock, effected by expansion of the band 16 into tight gripping engagement with the housing liner 15.

Since this locking action results from upward thrust on the joint mechanism, through the lower leg, caused by the wearers weight on the leg and consequent pressure on the foot, it follows that the said gripping action may be lessened and the engagement of the band with the liner may be made a frictional slipping or braking action by less pressure on the foot.

The wearer by practice can learn to use this braking action to advantage, for example in the act of sitting down.

It is one of the advantages of the joint construction and a part of its improved operation that it may be operated as a positive lock or as a variably slipping brake.

In some cases it is desirable for the joint mechanism to be operable as described, to lock or exert braking action, not only when the lower leg is in the straight leg portion, but also when it is in a bent knee angular position in a selected range of angles from the straight leg position; but to be inoperable at greater angles, outside that range.

This is accomplished as follows, with reference to Fig. 2 and particularly Figs. 8 and 9.

As described, operation of the mechanism occurs upon movement of the lower leg 2 and its straps 39-39 toward the housing wall 5.

On the inner sides of the straps 39 are mounted stops 44-44, by screws 45 and pins 46, the stops having upper surfaces 47.

Immediately above the stops 44-44, the housing wall 5, on its lower side is cut away for a short distance from its ends as at 48-48 see Fig. 4, leaving confronting forward and rearward edges 49-50 of the side wall, and leaving a portion 51 of the liner 15 exposed, see Figs. 4-8-9.

The stops 44-44 are located on the straps 39 so that when the lower leg 2 is in the suspended or down position, there is a space 52 between the upper surface 47 of each stop and the exposed portion 51 of the liner, shown in Fig. 8 and indicated in Fig. 2.

This space 52 provides for the said upward thrust lost motion movement of the lower leg and the straps to operate the mechanism.

When the lower leg 2 is swung rearwardly and the straps 39 and stops 44 swing with it, the parts go from the position of Fig. 8, to the solid line positions of Fig. 9, swinging through an angle a.

The said housing edge 50 is located so that in this position of the parts, the exposed portion 51 of the liner 15 is still opposite the surface 47, and spaced therefrom by the space 52, so that the mechanism can be operated by upward movement of the lower leg, at any angle up to the maximum angle a.

When the lower leg is swung through an angle greater than the angle a, say the angle b of Fig. 9, the pertinent parts go to positions represented in broken lines in Fig. 9 in which the stop surface 47 is beyond the housing edge 50 and then the space 52 is absent and the lost motion movement of the lower leg cannot occur and the mechanism cannot be operated.

The foot 3 may be mounted on the lower leg 2 in any well known manner, with a pivot therefor indicated at 53, or it may be rigid with the lower leg, it being apparent that upward thrust on the lower leg for the described purposes will occur in either case.

As described, the end plates 6-7 transmit upward thrust from the lower leg 2 to the bolt 18, and the bolt 18 transmits this thrust to the eye 26 of the lever 25 to rock it to cause the band 16 to grip the liner 15.

The lower leg 2 is described as having upward lost motion movement in exerting upward thrust.

This is for convenience of description. Actually the lost motion is very slight as mentioned; because a very small upward and downward movement of the bolt 18 is enough to effect said gripping, and release thereof; and concurrent upward and downward movement of the bolt 17 which is also moved by the end plates, is permissible.

The invention however can be practiced with considerable lost motion; and in such case it is preferrable to cause the end plates and the bolt 18 to move in unison, but for the end plates to have some movement relative to the bolt 17.

To this end, as indicated diagramatically in Fig. 10, the holes 54 in the end plates for the bolt 18 are made circular and fit the bolt, while the holes 55 for the bolt 17 are made with clearance at the under side of the bolt as at 56 to permit the end plates to move upwardly without moving the bolt 17.

In the foregoing description and in some of the appended claims, the gripping of the band 16 on the liner 15 is sometimes conveniently described as caused by expansion of the band, but it should be clear that since the band is always in actual sliding contact with the liner, the band is frictionally gripped upon the liner to effect braking but that no actual expansion occurs, and the word expand and the like is to be read with that meaning.

I claim:

1. In an artificial leg, thigh and lower leg portions; a housing on the thigh portion having an inner cylindrical wall; a cylindrical band element fitting within the cylindrical wall, having end portions and having terminal ends on the end portions with a space therebetween; an elongated lever having a pivot support intermediate its ends on one end portion of the band, and an end of the lever projecting beyond the pivot into said space; whereby rocking of the other end of the lever in one direction will force the band end portions apart and cause the band to grip the housing wall; means connecting the lower leg portion to the said other end of the lever whereby upwardl thrust on the lower leg portion will rock the lever in said direction.

2. An artificial leg as described in claim 1 and in which the lower leg portion is also connected to the other end portion of the band, and the band is rotatably supported on the cylindrical housing wall in the absence of said thrust; and the band and cylindrical Wall then constitute a supporting bearing for the lower leg portion for hinging movements thereof relative to the housing and thigh.

3. An artificial leg comprising a thigh portion and a lower leg portion and a knee joint construction connecting them; the lower leg portion being hingedly movable on the joint construction from an unbent straight leg position to bent knee positions at an angle to the thigh portion; the joint construction providing lost mo- References Cited in the file of this patent tion thefeimlie'tweemthe lower leg and thigh portion it 7 H when the lower leg is in said straight'l'eg position; a lock UNITED STATES PATENTS mechanism incorporated in the knee joint construction 1,0 ;012 Stage Oct. 28, 1913 comprising means operable to lock the lower leg por- 5 02 'Flsch'er et a1. 1951 tion to the thigh portion and unlock it therefrom upon 5 3 McKendrlck 311116 1953 alternate longitudinal lost' motion movements of the lower leg portion-when in said straight legposition; and FOREIGN PATENTS means blocking lost motion movement of the lower leg "481,236 France Aug. 22, 1916 portion when in bent knee positions at greater than a 10 predetermined angle.

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