US2652570A - Artificial hand - Google Patents

Description

Sept. 22, 1953 "iled Nov. 28, 1951 J. sARGEsoN 2,652,570

\ ARTIFICIAL HAND 4 Sheets-Sheet l INVENTDR SQP- 22, 1953 J. sARGEsoN 2,652,570

ARTIFICIAL HAND Filed NOV. 28, 1951 Sheets sheet 2 Illllf INVENTUR JOHN /RGESON i9 4 Sheets-Sheet 3 N E NTD R ./oH/v SRGEsc/v EYMM M J. SARGESON ARTIFICIAL HAND Sept. 22, 1953 Filed Nov. 28, 1951 SePt- 22, 1953 J. sARGEsoN 2,652,`570

\ ARTIFICIAL HAND `Filed Nov. 28, y1951 4 sheets-sheet 4 Patented Sept. 22, 1953 UNITED STATES FATENT OFFICE 7 Claims.

grasp an object when the opening pressure is discontinued.

A further object of the invention is to provide a gripping device for an artificial hand comprising relatively movable jaws and an actuator for one of the jaws. The actuator includes a flexible element connecting the one jaw to a limb of the wearer, such as a leg, by means of a reel or like device which is adapted to accommodate natural movement of the leg, and which is controlled in a manner that movement of the leg exerts a pull on the flexible element for operating the one jaw. The reel is controlled by a ratchet mechanism which is devised to lock it by foot movement.

A still further object is to provide in an articial hand a pair of co-acting jaws in which one of the jaws is pressed towards the other by a spring, and in which the actuator overcomes the spring pressure in order to open the jaws for gripping an object.

Still another object is to provide a highly serviceable and efficient articial hand comprising jaws which are relatively movable and controlled by an unbending movement of a leg of the wearer without hampering ordinary use of the legs as in walking.

Still another object of the invention is to furnish an artificial hand incorporating a mechanical gripping appliance which is easy to manipulate and which assures of a uniform gripping pressure being applied in each operative movement.

Having recounted the major objects and advantages of the invention subsidiary objects and advantages will be apparent from the ensuing speciiication of which the accompanying drawings form a part.

In the drawings,

Fig. l is a side view of the artificial hand showing how it is worn and connected to a leg of the wearer for operation of the gripping device;

Fig. 2 is a similar view, but depicting how the gripping device takes hold of an object;

Fig. 3 is a side view, partly in section, of the artificial hand in which the movable jaw is depicted in its second position in dash lines;

Fig. 4 is a further side View of the artificial hand, but taken at right angles to Fig. 3;

Fig. 5 is a side view of the actuator which is mounted on the leg of the wearer to control the movable jaw;

Fig. 6 is a side view partly in section of the ratchet controlled reel;

Fig. 7 is a section on line 1-1 of Fig. 6 depicting the winding spring for the reel;

Fig. 8 is a view in perspective of the reel support which is applied to a foot of the wearer. In this View the attachment strap is shown detached from the stirrup element;

Fig. 9 is a section on line 9-9 of Fig. 3;

Fig. 10 is a side view of the jaws showing more clearly the arrangement of the iiexible elements by which the movable jaw is controlled; and

Fig. 11 is a diagrammatic detail showing the means for adjusting the tension of the spring for closing the jaws.

In carrying out my invention there is provided a socket as usual for attachment to the amputated limb. The socket may be of conventional construction according to the nature of the amputation, but desirably I construct the socket with a major part of a rigid material, and with the remaining part of a iexible material. Said major part forms the body portion I4 of the socket and comprises a rigid wall which substantially surrounds the amputated limb but leaves an opening at one side thereof which is closed by the flexible element, denoted at l5. The flexible element is secured along one of its longitudinal edges to the body portion I4. Adjustable fastening means are provided at the other longitudinal edge to enable the socket to be bound firmly on the amputated limb. Suitable fastening means may consist of the tags I6 and the lace Il, but other fastening means may be substituted if so desired.

To assist in the secure attachment of the appliance and to prevent it from becoming askew, the upper end of the socket is supplied with a strap i8 which is adapted to encircle the arm of the wearer at a point slightly above the elbow. The strap is adjustable by means of the buckle I9 and is joined to the body portion lli by the lateral connecting parts 20.

The hand or grasping portion of the appliance is carried as usual by the socket and comprises a gripping device. Said gripping device is of a novel construction and comprises a pair of coacting jaws supported for opening and closing movements. Jaw 2| is iiXed on a support 22 to extend outwardly of the bottom end 23 of the socket. The other jaw, indicated at 2li, is movable on the support 22 as by the pivotal connection 25 and normally is held in a closed position alongside of the jaw 2| by spring pressure.

Preferably the closing pressure is applied to the movable jaw by a helical tension spring 26 having an end connected to the body |4 of the socket, the other end being attached to a flexible element 21 in the form of a nylon cord which is arranged to exert a closing force on the movable jaw under tension of the spring 26. Said cord extends from plate 28 on the free end of this spring and is engaged with a grooved roller 29 in the movable jaw 24 and is similarly engaged with a grooved roller 30 in the xed jaw 2| from where it extends to the support 22 and is anchored thereto by its end part 3|. 'With this arrangement the cord 21 translates the spring tension into a smooth and strong closing force on the movable jaw.

The closing force on the movable jaw can be adjusted by any suitable expedient. One way of achieving this is to provide a plurality of spaced knobs or nodules 32 on the end 3| of the cord 21 and to selectively engage one of these with a bifurcated anchor plate 33 on the support 22. The arrangement enables the tension of the spring 26 to be increased or decreased according to requirements in the use of the appliance. The adjustment is comparatively coarse, therefore a liner adjustment may be incorporated in the structure if so desired. This may comprise a headed screw 34 carried by the socket and threadedly engaged in an internally threaded plug 35 secured to the fixed end of the spring 26. The screw 34 is rotatably mounted on the socket by means of the bracket 36 and is shouldered thereon by its head so that it can turn freely. It will be understood that a ne adjustment of the spring tension can be had by turning the screw relative to the plug, The tensioning means for the movable jaw along with the adjustment means therefor will be best understood from an inspection of Figs, l and 11.

The gripping faces 31 and 38 of the jaws may be made of hard or soft material to best suit the objects to be held. Rubber can be used as a soft facing material Where there is a likelihood of defacing articles to be grasped. Furthermore, one of the jaws may be equipped with a self-aligning jaw-piece 39 which is pivoted at 49. Modification in this respect may be resorted to within the scope of the invention. It may also be desirable to mount the jaws on the socket in a manner to permit them to be turned to different angular positions. This can be accomplished by pivoting the support 22 at as 4| (Fig. 3) and providing a latching device for retaining it in a set position. Such a latching device may consist of a circular series of holes 42 in the end wall 23 of the socket and a latching bar 43 on the support 22. The latching bar is spring pressed in order to be selectively engaged in one or another of the holes 42.

It will be understood from the preceding description that the movable jaw is normally retained in closed position by the pressure of the tension spring 26 and that in order to open the jaws it is necessary to relieve the movable jaw of the pressure of the spring. The actuating `device serves this purpose and comprises a flexible cable 44 freely extending through a flexible tube 45, which are similar to the well-known Bowden wire. One end of the cable 44 is secured to a nylon cord 46 which is engaged with a grooved roller 41 on the support 22 and connected to the spring 26 so that when pulled it will act to stretch the spring. It is preferable to increase the purchase by providing a grooved roller 48 on the plate 28 and engaging the cord 46 with this roller and securing the free end 49 of the cord to the support 22.

The cable 44 and the tube 45 are extended over the near shoulder of the wearer and down the back in order to reach to the leg of the wearer remote from the arm on which the artificial hand is used. On this leg there is `applied the pulling device by which a pull can be exerted on the -cable by means of a straightening movement of the leg after it has been bent. The pulling device comprises a Winding reel 50 fastened on the leg below the knee. The reel is mounted on a support in the form of a case 5| which is secured to a pliant band 52. Said band is a split member of soft leather or other suitable material adapted vto encircle the leg and be fastened thereon by conventional means, such as an adjustable fastener indicated at 53. A shoulder pad 54 is attached to the iiexible tube 45.

The cable has an end 55 secured to the reel 50 and wound thereon under the influence of a coil spring 56. The major part of the cable may be made of readily flexible wire, whereas the end part 55 may consist of a nylon cord which is capable of more readily winding on the reel. The spring 56 is suitably tensioned to exert a Winding force on the reel, which spring is a spiral member having its outer end secured to the reel and having its inner end secured to a stationary shaft 51.

The reel is tensioned sufliciently to take up slack in the cable and to pay it out as required in any movement of the leg, such as in walking. From the preceding description it will be manifest that a fairly strong pull must be exerted to stretch the spring 26 in order to open the movable jaw 24. The reel spring 56 is not of sumcient strength for this purpose, but merely functions to keep the cable taut at all times. The reel, by paying out the cable and reeling it in, permits unhampered movement of the leg to which it is attached. Also it does not restrict movement of the arm to which the appliance is attached.

When it is desired to open the jaws the reel is prevented from turning in an unwinding movement so that the leg to which it is attached may be ilexed and then straightened to exert a pull on the cable. In the flexing movement of the leg the reel turns under the spring pressure to Wind up the slack of the cable incidental to the flexing action. The reel is then stopped against unwinding by a ratchet device hereinafter described. In this way a pull of considerable force can easily be applied to the cable by the unbending of the leg at the knee, which opens the 'movable jaw to the desired extent. The straightening of the leg enables the spring 26 to vclose the jaw.

The ratchet device comprises the provision oi one way teeth 51 on a flange portion of the reel. A peripheral series of the teeth are used and the structure constitutes a ratchet wheel embodied in the reel. A pawl 58 co-acts with the ratchet teeth 51 and is pivoted at 58' on the support 5| intermediate of its length. One end of the pawl is arranged to swing into engagement with a ratchet tooth when the other end is pulled downwardly. The ratchet teeth and the pawl operate to prevent the reel from turning in an unwinding direction. The pawl is normally retained in a disengaged position (Fig. 6) as by the coil spring 59.

A flexible element, such as a cord 60 is employed to actuate the pawl for causing it to engage the ratchet wheel. This cord is connected to the forepart of the foot and is of such a length that the foot can exert a pulling force by merely bending the foot downwardly at the ankle, as clearly represented in dash lines in Fig. 5. The cord is detachably connected to the shoe on the foot in any convenient manner.

In order to prevent displacement of the reel in an operational movement, it is desirable to employ a stirrup 6I by which the pulling force of the cable is taken on the foot portion of the leg on which the actuating device is worn. The stirrup is shown as a U-shaped member, which may be made up of wire rod material and has its bight portion disposed under the arch of the foot, the end parts '62 being pivoted or otherwise attached to the band 52. Said stirrup is shown as fastened to the foot by a flexible strap E3 of an adjustable character, which extends over the instep and has its end parts hooked onto the stirrup near the bight portion thereof.

From the preceding description it will be manifest that my invention supplies an eflicient and easily manipulated artificial hand of which the jaws are capable of firmly grasping various kinds of objects. In the use of the appliance the spring 26 retains the movable jaw 24 in closed position. To open this jaw the wearer bends at the knee the leg to which the actuating device is applied-see Fig. l. In the bending movement the cable winds on the reel and is maintained in a taut condition. He then bends the foot of this leg downwardly at the ankle to cause the pawl 58 to engage a ratchet tooth 55 to lock the reel against unwinding. The leg is then straightened, which pulls on the cable and relieves the movable jaw of the pressure of the spring 26. A comparatively light spring 63 (Fig. 3) is used to open the movable jaw. To close this jaw the foot is bent upwardly at the ankle to its former position to slacken the cord 60 and allow the spring 59 to disengage the pawl 58. This permits the reel to turn in an unwinding direction so as to permit the spring 26 to apply closing pressure on the movable jaw for grasping an object.

It is of course evident that when the wearer puts the apparatus on the body (each day, presumably) there will be an initial operation of adjusting the cable and reel to preset the amount of slack or tension in the cable to a predetermined desirable condition: this may require several kick-like movements of the limb to wind the reel until the spring tension 26 comes into its normal rest valve. Thereafter it is necessary to operate the actuating limb through only one cycle as above described in order to operate the grasping jaws. The nodules 32 and adjusting means shown in Fig. 11 ensure that the presetting operation is confined within conveniently narrow limits, at the same time providing some allowance for changes which may occur from time to time in body dimensions, or to ageing of tensed parts of the apparatus.

What I claim is:

l. In an articial hand, a socket, a gripping device carried thereby including a jaw pivoted to swing from closed to open position, a roller on said jaw remote from the pivotal axis thereof, a helical tension spring anchored at an end on said socket, a cord connected to the other end of said spring and engaged on said roller and fastened to said socket with said spring under tension, the tension of said spring retaining said jaw in closed position, a flexible element connected to said jaw for effecting an opening movement thereof when pulled, a tensioned reel for attachment to a limb of the wearer and connected to said flexible element for winding and unwinding movements, means for locking said reel against turning in an unwinding direction and in which the cord is provided with a plurality of spaced nodules at an end thereof for selective engagement with a bifurcated member on the socket whereby to fasten the cord in an adjustable manner to vary the tension of the spring.

2. In an artificial hand, a socket, a gripping device carried thereby including a movable jaw spring pressed to closed position, and means for opening said jaw, said means comprising a flexible element having a connection with said jaw for overcoming the pressure thereon when pulled, a spring tensioned reel operative to wind said iiexible element to maintain it in a taut condition, means for strapping said reel on a, limb of the wearer, and a ratchet device for holding the reel against unwinding.

3. In an artificial hand, a socket, a gripping device carried thereby including a movable jaw spring pressed to closed position, and means for opening said jaw, said means comprising a flexible element having a connection with said jaw for overcoming the pressure thereon when pulled, a spring tensioned reel operative to wind said flexible element to maintain it in a taut condition, a band supporting said reel and adapted for attachment to a limb of the wearer, ratchet teeth on said reel, a pawl supported on said band for engaging said ratchet teeth, and means for operating said pawl.

4. A structure as set forth in claim 3, in which the means for operating said pawl comprises a spring pressing said pawl away from said ratchet teeth, and a cord connected to said pawl for attachment to a relatively bendable part of said limb.

5. In an artificial hand having a movable jaw. a mechanism for actuating said jaw comprising a ilexible element connected to said jaw, a spring tensioned reel connected to said flexible element for taking up slack therein, a case housing said reel, a pliant band on which said case is mounted, said band being constructed for attachment to a limb of the wearer, means providing ratchet teeth on said reel, a pawl for engaging said ratchet teeth, a spring acting to press said pawl away from said ratchet teeth, and a cord attached to said pawl for moving it into engagement with said ratchet teeth.

6. A limb simulating apparatus comprising a socket, a gripping device carried thereby and including a movable jaw and a spring urging said jaw toward a predetermined position with respect to a mating jaw, and means for altering the said predetermined position against the urge of said spring, said means being characterized by a ilexi'ble element having a connection with said movable jaw for overcoming the pressure thereon when pulled, a spring tensioned reel operative to wind said flexible element to maintain it in a taut condition, a ratchet device capable of holding the reel against unwinding and means associated with a selected limb member for latching and unlatching the said reel.

7. In an articial hand, a jaw supporting 7 socket, fa jam/'mounted thereon for movement be- References Cited lin the me of this tween closed and :open positions, resilient means UNITED STATES P normaihf retaining said jaw i-n -a closed position,

a. spring supported to act on 'said jaw to press it Number. 4 Naim@ Dm,

2532 732 Sansbur Dec 5 1950 to 0. n, t n, exlbl elem nt tt ched to I f y i De posi 1 a e e a a 2,537,551 sansbury -..v,-. Jan. 9, 1951 and extend-ing from s'a/id jaw, ra, tensioned reel for attachment to a, 111mb of 'the wearer and connected to said flexible element for winding vand unwinding movements, a means for locking said reel against turning in an unwindng direction. 10

JOHN SARGESON.

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