US3533651A

US3533651A - Releasably lockable structure simulating a human joint

Info

Publication number: US3533651A
Application number: US749840A
Authority: US
Inventors: Jan Prahl
Original assignee: Wilhelm Julius Teufel GmbH
Current assignee: Wilhelm Julius Teufel GmbH
Priority date: 1967-08-09
Filing date: 1968-08-02
Publication date: 1970-10-13
Anticipated expiration: 1987-10-13
Also published as: DE1566517A1; FR1588857A

Description

oct. 13, 1910 J, PRAHL j 3,533,651

RELESABLY LOCKABLE STRUCTURE SIMUL'ATING A HUMAN JCINT Filed Aug. 2, 1968 mfVENToR.

I. ,y Jan `Preti#0 1 -BY n United States Patent O Int. cl. Frse 11/00 U.S. Cl. 287-99 6 Claims ABSTRACT F THE DISCLOSURE A structure which simulates a human joint and can be locked in a given position includes a pair of components simulating a pair of human limbs. These components are pivotally connected to each other for turning movement one relative to the other. A swingable lock member is pivotally carried by one of the components and describes part of a given circle during swing movement. The pair of components are formed with lock notches which register when the components are in a given angular position with respect to each other. The lock notches receive, when they register, the swingable lock member so that with the latter in the notches the components are locked in a predetermined position. When the notches register they are situated along a tangent to the circle that is described in part by the swingable lock member, and the inclination of the registering notches is such that they tend to press the lock member toward its locking position in response to any tendency of the components to move from the position they take when the lock notches register.

BACKGROUND OF THE INVENTION The invention relates to structures which simulate human joints.

Thus, it relates to jointed mechanical structures used for orthopedic purposes or used by individuals who have su'iered paralysis of certain limbs as to enable the limbs to be moved with the use of the structure.

In order to maintain the joint structure in a given position it is conventional to provide locking pins and detent structures, or there are swingable lock members which are capable of ybeing swung into projections of the joint components for releasably holding them in a given position.

However, such conventional locking structures, situated at a given distance from the pivot axis between the components which simulate the limbs, are very often subjected to intense stresses and to a large amount of wear. The reliabilityv with which the pivotally interconnected, limb-simulating components are locked is not suicient because of the possibility of a sudden jumping of the locking elements from their locking positions and the manner in which the components are supported for turning movement. With conventional structures there is an undesirable play between the components, placing the reliability of the structure in jeopardy.

SUMMARY OF THE INVENTION It is accordingly a primary object of the invention to provide a structure which will avoid the above mentioned drawbacks.

In particular, it is an object of the invention to provide a joint-simulating structure which can be very reliably held in a given position.

It is a further object of my present invention to provide a structure of the referred to type which is exceedingly simple and easy to operate, without sacricing any Mice of the reliability in the maintenance of the structure in its locked position.

In accordance with the invention, the pivotally interconnected components are respectively formed with lock notches which register when the components are in a given position relative to each other. A swingable lock member is swingably carried by one of the components to enter into the registering lock notches to hold the components locked in a given position. The registering lock notches extend along a tangent to a circle which is described, in part, by the swingable lock member.

An important advantage of the structure of the invention resides in the fact that the lock structure of the invention tends to become locked more tightly under load. This advantage is achieved by situating the registering lock notches along a tangent to a circle described in part by the swingable lock member. Where the components are locked in a generally upright position, the inclination of the registering lock notches may be on the order of 50 with respect to a horizontal plane. The pressure exerted on the lock member with such a situation of the lock notches acts at an angle of with respect to the plane of the tangent along which the lock notches extend. Thus, there is an angular relationship which distributes the forces in such a way that the locking element is pressed further into the locking notches. As a result, slipping of the locking element out of its locking position while loaded is impossible.

A further important feature of the invention resides in the vfact that the center about which the lock member swings is situated at such a location that a straight line drawn through this center and the lock member itself, when the latter is in its locking position, forms with the tangent along which the locked notches extend an angle greater than 90. In this way there is achieved the advantage of additional reliability in maintaining the structure in its locked position because the lock member is situated at a location analogous to the location of a toggle joint beyond its dead-center position, so that added pressure only serves to lock the structure more tightly.

According to the invention, the lock member preferably is in the form of a cylindrical lock pin while the notches pass through the overlapping walls of the pivotally interconnected components, with one of these components having two integrally connected walls defining between themselves a gap receiving a wall of the other component. As a result of this construction the lock member is loaded exclusively in shear and is otherwise relieved of all other loads. The swingable mounting of the lock member remains completely unloaded when the lock member is in its locking position.

BRIEF DESCRIPTION OF THE DRAWING The invention is illustrated by way of example in the accompanying drawing which forms part of this application and in which:

FIG. 1 is a partly sectional side elevation of a structure of the invention which simulates a knee joint and which is shown in its locked position;

FIG. 2 is a side elevation showing the structure of FIG. l, with the lock member displaced to an unlocking position; and i FIG. 3 is a transverse section of the structure of FIG. l, taken along line 3-3 of FIG. 1 in the direction of the arrows.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawing in greater detail, and initially to FIG. 1, there are illustrated therein an upper limb-simulating member or bar 3 which simulates the part of a leg over the knee, while the lower part of the leg 3 which extends downwardly from the knee is simulated by the lower component 4. These parts or components are pivotally interconnected at a joint composed of the overlapping portions 1 and 2 of the components. The lower component 4 has a pair of spaced parallel wall portions 2 integrally connectedto each other and delining between themselves a gap which receives the wall portion 1 of the upper component 3. A pivot member extends through the overlapping wall portions of the

components

3 and 4.

The wall portions 1 and 2 are all formed with lock notches 6 which register with each other when the upper component 3 extends upwardly from and forms an extension of the component 4. In other words, when the limbsimulating components have a substantially straight-line condition with respect to each other, the locking notches 6 register with each other. Of course, the notches 6 of the walls 2 are permanently in register with each other while the component 3 can turn together with the wall 1 to a position in which a notch 6 of the latter registers with the other notches 6. In this position it will be noted from FIG. 1 that the lower inclined edge of the component 3 engages the inclined surface between the wall portions 2 so that counter-clockwise turning of the component 3 with respect to the component 4, and clockwise turning of the component 4 with respect to the component 3, as viewed in FIG. 1, is limited by engagement between the upwardly directed surface between the walls 2 and the downwardly directed edge of the wall 1. In this position the notches 6 register and define a common upper open inlet end and a common closed lower end.

When the notches 6 register they extend along a tangent to a circle, this tangent being shown in dot-dash lines in FIG. 2. The tangent 7 is inclined in the illustrated upright, extended position of the

components

3 and 4 at an angle of 50 with respect to the horizontal, for example.

The lock member includes a pin 8 of cylindrical shape forming the locking element and carried by a lock lever 9 which is swingable about the pivot 10 carried by the component 3. The latter which has the intermediate wall 1 of the joint pivotally carries by way of the pivot pin y10 a lock member 9 which is provided with the locking element 8 that is received in the registering notches. The tangent 7 is tangent to a circle described by the element 8 as it swings about the axis of the pivot 10 during turning of the lock lever 9 which can be manually turned by the operator.

In the position of the parts shown in FIG. 1, the lock member 8 extends transversely through the three registering lock notches 6, and the pivotally interconnected

components

3 and 4 are incapable of moving with respect to each other.

On the other hand, When the parts are in the position of FIG. 2 where the operator has raised the lever 9, the pin 8 is displaced from its locking position so that the parts can now turn relative to each other.

When the parts are in the locked position shown in FIG. l, any tendency of the component 3 to turn clockwise with respect to the component 4, or of the component 4 to turn counter-clockwise with respect to the component 3, as viewed in FIG. 1, causes the developing forces to act on the pin 8 to urge same, as seen in FIG. 1, downwardly toward the left, that is, more tightly toward the closed end of the registering notches 6 so that an extremely reliable lock structure is achieved. rThis result is brought about by providing the angle of more than 90 between the tangent 7 and a straight line drawn through the center of swinging of the lever 9 and the center of the lock member 8 when the latter is in its locking position. If this angle were precisely 90, then it would correspond to the dead-center position of a toggle joint. However, by making the angle somewhat greater than 90, an angle of 95 being shown in FIG. 1, then what corresponds to the location of a toggle joint beyond its dead-center position is achieved, with the forces locking the structure only more tightly. Furthermore, it will be noted that because the pressure of the wall 1 acts on the pin 1 between the pressure provided by the walls 2 the pin 8 is acted upon exclusively by shearing forces and the pivot 10 is completely unloaded.

I claim:

1. In a structure for simulating a human joint, a pair of components respectively simulating a pair of limbs, said components being pivotally connected to each other for turning movement about a predetermined axis one with respect to the other, and a swingable lock member swingably carried by one of said components for describing part of a circle during swinging of said lock member, said pivotally connected components being formed with locking notches which become superimposed so as to register when said components are in a given angular position relative to each other and which, when registering, receive the end of said swingable lock member, one side of each of said registering notches extending along a tangent to the circle described in part by the far end of said swingable lock member, the center of swinging of said swingable lock and the far end of the lock member itself defining the ends of a straight line forming with said tangent, when the lock member is in a locking position within the registering notches, an angle sufficiently greater than to achieve a toggle joint beyond its dead-center position.

2. The combination of claim 1 and wherein said swingable lock member has a locking portion of cylindrical conguration received in the registering notches.

-3. The combination of claim 2 and wherein said components include at the region where they are pivotally interconnected three wall portions two of which are integral and define between themselves a gap receiving the third wall portion, said notches being formed in all three wall portions so that the notches in said two wall portions are permanently in register with each other while the notch in said third wall portion can be displaced angularly with respect to the other notches to and from the registering position.

4. The combination of claim 3 and wherein said swingable lock member is swingably carried by that one of said components which has said third wall portion.

5. The combination of claim 1 and wherein said cornponents simulate a knee joint and are both in an extended substantially straight-line position when said notches register, with one of said components being situated over and extending upwardly from the other of said components, said notches when registering delining a common upper open end for receiving said lock member and a common lower closed end engaged by said lock member when the latter is in a locking position.

6. The combination of claim 5 and wherein the registering notches are inclined at an angle which urges the lock member toward said lower closed end of the notches when one of the components tends to turn with respect to the other of the components in a given direction so that the components are reliably locked in their extended position.

References Cited UNITED STATES PATENTS 1,226,324 5/1917 Gage 287-99 2,433,570 12/ 1947 Markkula 287-99 2,549,194 4/1951 Hale 287-99 DAVID I. WILLIAMOWSKY, Primary Examiner A. V. KUNDRAT, Assistant Examiner