Cord restraint system for pressure suit joint

Baker, M. E.

Hardy, J. C.

Marroni, M. A., Jr.

English

NASA Technical Reports Server

FROMI GP/Office Of siqtapt Cieneral Counsel for 
Patent Matters 
TI Annomceawnt of A-Owned W. 8 .  Patents i n  8 
In accordance w i t h  the gsocedures agreed upon by Code OF 
announcemasnt i n  NASA STAR. 
USI, the attache A-owned 0. 8 .  Patent i s  being 
gor abs tractlng 
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m. fo l lw ing  i omnation i s  
a 8 .  Patent No. 
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Patent Case 8 
https://ntrs.nasa.gov/search.jsp?R=19710015147 2020-03-17T02:56:27+00:00Z
. A. MARRQNI m A L  
QMNIDIRECTIQNAL JOINT 
Filed Oct. 7, 1966 2 Sheets-Sheet 1 
.?me 23, 
- Filed Oot .  
M. A. MARRONI ETAL 3,s 16,09 1 
OMNIDIRECTIONAL JOINT 
2 Sheets-Sheet 2 7. 1966 
ate 
M 
ration, East Hartford, 
Conn., a corporation of Delaware 
U.B. el. 2-22. 3 Claims 
A 
A cord restraint system for pressurized suit includes 
axially spaced circumferential convolute roots spaced 
about the axis of rotation of a limb which carry a plu- 
rality of restraint sets. Each set includes a cord movable 
relative to points of attachment which extend from points 
above and below the bending axis and are in pairs each 
of which are diametrically opposed on the respective 
convolute roots and each pair being circumferentially 
spaced 90” from each other. The mrd is serially laced 
through each point of attachment. 
The invention described herein was made in the per- 
formance of work under a NASA contract and is sub- 
ject to the provisions of Section 305 of the National 
Aeronautics and Space Act of 1958, Public Law 85-568 
(72 Stat. 435; 42 U.S.C. 2457). 
This invention relates to joints for pressure suits and 
particularly to omnidirectional joints which are made 
from “soft” or nonrigid materials. 
Pressurized suits designed for space or high altitude 
aircraft use must have flexible joints corresponding to 
the human joints of the wearer to permit freedom of 
movement of the body and limbs. These joints should be 
relatively easy to move, should allow a sufficient degree 
of freedom, and should conform to the human anatomy 
so as to prevent pressure points from developing when 
the suit is inflated. A pressure point being irritating local 
contact between an inflated pressure garment and the 
subject wearing the suit. 
There are two types of joints currently being developed. 
The so-called hard joint which contains elements which 
are rigid when unpressurized and the so-called soft joint 
which is relatively soft and flexible when unpressurized 
and becomes hard only when pressurized. This invention 
relates to soft joints. 
One of the deficiencies of the soft joints in use prior 
to applicant’s invention ‘was the tendency for the joint to 
be unstable in certain positions. When some prior types 
of joints are bent there is a strong tendency for the joint 
to continue to bend until one side of the joint is com- 
pletely extended and the other side collapsed. These 
joints are stable only in a full bent position in either 
direction and are relatively unstable in any position be- 
tween these two extremes. When held in the flexed or 
straight position there wadd be a strong tendency for the 
joint to move to one of these extremes. Other prior types 
exhibit instability toward neutral, that is a strong tend- 
ency to return to the unflexed position. This is undesira- 
ble since the subject must cantinually exert a force to 
hold the joint in any particular operating position. In 
the case of an elbow joint the subject’s arm would tend 
to go to one of the stable positions while the subject was 
attempting to hold it in a flexed position. Applicant’s joint 
is relatively stable in all normal operating positions. 
Many of the previous joints were not omnidirectional. 
Their movement was limited to a single plane. Our joint 
is truly omnidirectional. 
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eo 
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70 
It is an objectc of this invention to provide an omni- 
directional joint for a pressure suit. 
It is a further object of this invention to provide an 
omnidirectional flexible suit joint which can be moved 
relatively easily in any direction and which will be stable 
in any position. 
It is a further object of this invention to provide an 
omnidirectional joint for a pressure suit which is twist- 
able. 
Another object of this invention is to provide a pres- 
sure suit joint which is completely soft in the unpres- 
surized condition. 
FIG. 1 is a pictorial representation of an elbow joint 
embodying our invention. 
FIG. 2 is a schematic representation of the elbow joint 
shown in FIG. 1 in an unpressurized, unlaced condition. 
FIG. 3 is a cross section taken through section 3-3 
of FIG. 2. 
FIG. 4 is a pictorial representation of the elbow joint 
of FIG. 1 shown in a bent or flexed position. 
FIG. 5 is a schematic showing part of the restraint 
for a single convolute. 
FIG. 6 is a schematic showing this invention embodied 
in a wrist joint. 
FIG. 7 is a pictorial representation of the wrist joint. 
FIGS. 2 and 3 show construction details of an elbow 
joint embodying this invention. FIG. 2 shows the elbow 
joint in an unpressurized, unlaced condition. It includes 
a flexible fabric tubular member 2 and a slightly larger 
gas impervious tubular bladder 4 which retains the gas 
in the suit. The inner bladder 4 is slightly larger than 
the outer fabric 2 so as to prevent stretching of the inner 
bladder when the suit is inflated. Short tubular bladder 
tapes 5 have one end cemented to the bladder and the 
other end sewn to the fabric tube to limit relative move- 
ment between the bladder and the fabric tube. A series 
of axially spaced restraint cords 10, 12, 14, 
circumscribe the tube. These cords are held in their axial 
position by tunnel tapes, of which 22 is representative, 
which is sewn to the outer periphery of the cloth. The end 
of the restraint cords extend through a hole in the tunnel 
tape and can be externally tied so as to locally reduce the 
diameter of the tube, thereby creating a series of con- 
volutes, or bending lines, along the length of the tube as 
shown in FIGS. 1 and 4. The restrained sections along 
the length of the tube are sometimes called convolute 
roots. Four equally spaced cord guide members 24, or 
ferrules, are attached to the circumference of the tube at 
each tunnel tape position. These guide members are low 
friction elastomer ferrules whicb are held in place by 
fabric retaining members ’26 which are sewn directly over 
the tunnel tapes. 
What has been described so far is a tubular member 
which is restrained only in a circumferential direction. 
Without any axial restraint, the tube, when inflated as part 
of a space suit, will become elongated to its maximum 
length and the fabric or cloth will be under high axial 
loads and will resist bending. To limit the axial loading 
of the fabric and to obtain the objects described above, 
the axial restraint system as shown in FIGS. 1 and 4 is 
applied to the joint. It will aid in the Understanding of the 
joint if the reader will keep in mind the fact that the joint 
when inflated is always seeking to expand to the largest 
possible volume and that it must always be restrained 
so as to maintain the desired characteristics and size. 
The axial restraint system consists of a series of six 
cords: 30, 32, 34, 36, 38 and 401 whicb are adjustable in 
length and which control the spacing between the various 
convolute roots which they interconnect. For the sake of 
the following discussion, the convolutes are numbered 
42, 44, 46, 48 and 50 while the root sections are numbered 
3,516,091 
4 
52, 54, 56, 58, 60 and 62. The axial restraint system can fabric. It is important that the material, or fabric, of the 
best be understood by referring to FIGS. 1, 2 and 4. As- tubular member not be stretched at any time due to flexing 
suming root 52 is a fixed reference, it will be apparent since the forces required to stretch the material are ex- 
that the root 58 is restrained by the cords 30 and 36. tremely large compared to the forces necessary to bend 
These cords limit the distance between root 52 and root the joint when it is in a convoluted form. 
58 when the suit is inflated. The distance between root 62 Since this joint is made up of soft flexible materials and 
and root 56 is limited by the restraint cords 34 and 40. twistable cords, the joint can be twisted or rotated about 
When the suit is inflated the length of these cords will con- its axis in either direction. This twisting is limited, how- 
trol and determine the distance between these root sec- ever, by the amount of excess fabric available in the axial 
tions. There is no restraint between root 56 and root 58 direction which must deform when the joint is twisted. 
and when the suit is inflated the tension in cords 30 and This ability to twist is extremely useful in suit joint and 
36 acting opposite to the tension in cords 34 and 40 will particularly in joints such as the elbow and wrist. Prior 
force convolute 46 to become compressed or collapsed as convoluted joints, without bearings, utilizing two cables 
shown in FIG. 1. This partially collapsed convolute pro- down the side as a restraint are capable of almost no 
vides the excess material which is essential for the sharp l5 twisting since the restraint cables are of fixed length and 
bend this joint must make when incorporated in a space it is almost impossible for a human subject to produce 
suit as an elbow. enough rotational torque associated with the foreshorten- 
Cords 32 and 38 control the distances between inter- ing of the joint when the fixed length cables are moved 
mediate roots 54 and 60. These cords help to stabilize the from their purely axial position. In our joints, the joint 
system but do not take a significant part of the combined 20 rotation is limited by the amount of excess fabric avail- 
plug, or axial load, which the joint is subject to. able in the axial direction rather than by the restraint 
Reference is now made to FIGS. 1 and 4. As stated system. As the joint twists the ferrules and cords will 
above, our invention provides a joint which, is stable in move with respect to each other, but they will not Prevent 
most positions and which can be moved easily. A major twisting of the ioint. 
factor in the amount of effort which is necessary to bend 25 FIGS. 6 and 7 show our invention embodied in a 
a joint is the amount of volume decrease which occurs wrist joint. The construction of the wrist joint is similar 
when the joint is bent. This has long been recognized by in many respects to the construction of the elbow joint 
those skilled in the art. The greater the decrease in vel- described above and therefore the description of the wrist 
ume when a joint i s  bent, the greater will be the force will be somewhat less detailed. As with the elbow, a flex- 
necessary to bend the joint. Another factor involved in 30 ible fabric tubular member is formed into a convoluted 
the effort necessary to move a joint is the resistance or configuration by a series of axially spaced circumferen- 
friction of the joint itself. In our invention, this friction tial cords which form the convolutes 72, 74 and 76. Al- 
is primarily friction between the restraint cords and the though a convoluted construction is shown here, it has 
guide members, or ferrules. A joint will remain in a posi- been found that it is not essential to form convolutes 
tion in which it is placed without the necessity to supply 35 along the length of the wrist joint since it is an extremely 
force to hold it in that position only when the internal short joint and the axial restraint cords are a sufficient 
static frictional force necessary to move the joint is greater control for the joint. I t  has been found inconvenient for 
than the pressure forces tending to enlarge the joint and glove donning and doffing to construct the wrist joint with 
increase its volume. The volume change involved in bend- a separate inner bladder and therefore a neoprene blad- 
ing a joint made according to our invention is sufficiently 40 der is cemented to the fabric tubular member to make it 
small when compared with the internal friction of the air tight and to minimize internal excess material. 
joint, so as to cause the joint to be stable in almost any The restraint system for the wrist is identical to the 
position in which it is placed. This means that a subject restraint system between any two of the root portions of 
wearing a suit which includes an elbow embodying our the elbow joint except that twice as many ferrules and 
invention can bend his elbow and place it in one position restraint cords are used to improve omnidirectional torque 
and then relax his arm without having the restoring forces 45 uniformity. 
of the joint cause his arm to spring out to a straight posi- 
tion or to a fully closed position. This is important in re- 
ducing the amount of energy necessary to perform tasks 
while wearing a space suit. Additionally, it gives the sub- 
ject a movement which feels natural when working in a 50 
zero gravity environment. 
When the elbow joint shown is flexed as shown in FIG. 
4 there must be relative movement between the ferrules 
and the restraint cords. Due to the four point restraint 
system which is embodied in this invention, there is very 55 
little cord movement and therefore very IittIe friction in 
moving the joint. Rather than having the cords move 
through the four ferrules, there is a tendency for the 
cords to remain stationary and for ferrules to move along 
the cords. This is shown in FIG. 5. 
Because of the relatively flattened and collapsed posi- 
tion of the middle convolute, there is a strong tendency 
for the joint when flexed to bend around this convolute 
as shown in FIG. 4. When this joint is used as an elbow 
joint, this feature is extremely helpful since the rate of 65 
bending at the center of the elbow joint is great and it is 
important that a sufficient amount of material is available 
along the outside of the elbow to allow for this large ex- 
pansion when the elbow is flexed. 
An examination of FIG. 4 reveals the importance of 70 
having the joint somewhat shortened when it is completely 
laced up. When the joint is ffexed, the distance along the 
mtside edge of the joint increases and unless the initial 
straight length of the joint is decreased, there will not be 
suficient material to flex the joint without stretching any 75 
We claim: 
1. An omnidirectional joint mounted in proximity to 
the axis of rotation of the limb of the wearer for pres- 
surized suits comprising: 
a flexible gas impervious tubular member for enclos- 
ing said limb; 
first and second cord reversing guide members at- 
tached to the opposite outside surfaces of the tubular 
member at one axial position spaced upwardly from 
said axis of rotation and mvable  with the impervious 
tubular member when the joint is flexed; 
third and fourth cord reversing guide members at- 
tached to the opposite outside surfaces of the tube 
at a second axial position spaced downwardly of said 
laxis of rotation, said third and fourth guide mem- 
bers being angularly spaced approximately 90" from 
the first and second guide members and also mov- 
able with the impervious tubular member when the 
joint is flexed; and 
a continuous restraint cord laced between all of said 
guide members to limit the axial expansion of said 
tube, said cord forming a path through said first, 
third, second and fourth cord reversing guide mem- 
bers as it circumscribes the tube. 
2. An omnidirectional joint for a pressure suit com- 
a flexible gas impervious tubular member for enclos- 
ing a human joint; 
a first, second, third and fourth axially spaced circum- 
ferentia1 restraint member for locally limiting the 
60 
prised of: 
3,516,091 
5 
maximum diameter of the tubular member and form- 
ing break lines along the joint when inflated; 
a first cord restraint system limiting the distance be- 
tween the first and third circumferential restraint 
members to less than the unrestrained distance be- 
a second cord restraint system limiting the distance be- 
tween the second and fourth circumferential restraint 
cord whereby the section of the tubular member 
between the second and third circumferential re- 
straint cord will tend to collapse in an axial direc- 
tion when the joint is inflated. 
3. An omnidirectional joint for pressurized suits com- 
tween these members; and 5 
prising: 
a flexible gas impervious tubular member for enclosing 15 
a human joint; 
a first, second, third, and fourth equally spaced cord 
reversing guide members attached to the outer sur- 
face of said tubular member at one axial position 
VERLIN R. PENDEGRASS, Primary Examiner 
along the tube; 20 
6 
a fifth, sixth, seventh, and eighth cord reversing guide 
members equally spaced around the outer surface of 
said tubular member at a second axial position, said 
fifth guide member being aligned with said first guide 
member; 
Q continuous restraint cord laced between said second, 
fifth, fourth and seventh guide members in turn as 
said cord circumscribes the tubular member; 
a second continuous restraint cord laced between said 
first, sixth, third and eighth guide members in turn 
as said second cord circumscribes the tubular 
member. 
References Cited 
FOREIGN PATENTS 
977,172 12/1964 Great Britain. 


Omnidirectional joint Patent

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