US 3404406 A
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Description (OCR text may contain errors)
K. E. BALLIET Oct. 8, 1968 DIVING SUIT BALLAET.
Filed Sept. l5, 1966 1&3@
m MQQU gw ATTQRNEYS United States Patent O 3,404,406 DIVING SUIT Karl E. Balliet, Lynchburg, Va., assignor to Rubatex Corporation, Bedford, Va., a corporation of Delaware Filed Sept. 13, 1966, Ser. No. 579,094 Claims. (Cl. 2-2.1)
ABSTRACT 0F THE DISCLOSURE A thermally insulated underwater garment having a continuous liexible outer skin within which is a cellular core material possessing low thermal conductivity and which is substantially incompressible at great depths. The core material is so arranged within the skin to thereby maintain tiexibility and high thermal insulation in the garment for the comfort and protection of a wearer,
This invention relates generally to underwater garments. More particularly, the present invention relates to underwater garments or diving suits which are flexible and stretchable and substantially incompressible so that they possess a low thermal conductivity enabling the diver to operate at deep water levels.
In skin diving or scuba diving, where the diver is not protected by a mechanical vessel such as small sub marine lor a diving cylinder, the diver is directly exposed to the surrounding pressure and temperature of the water. The human body can adjust to relatively high water pressures, but must be protected against the relatively low temperatures that occur frequently in water, particularly at lower depths. At relatively mild depths in the range down to 100 feet the diver can be protected against cold by insulating diving suits consisting solely or primarily of a relatively soft, flexible cellular material which has good insulation value such as expanded neoprene.
As the diver enters the water, however, the water pressure causes a compression of the soft diving suit material that reduces its thickness and consequently reduces its thermal vinsulation value. As the diver proceeds into deeper and therefore colder water, the soft insulating material increasingly fails to protect him against the cold and in fact progressively conducts more heat from his body when it is most needed. Obviously, this is a very serious problem to practical diving operations, since it severely limits the comfort of the diver to the shallower depths.
In order to effectively insulate a diver against cold water at considerable depth (up to 600 feet) the suit material must retain its thermal insulation value under pressure. Therefore, a soft material which can compressed cannot entirely be used to form the suit. At the same time, the suit must retain its flexibility and stretchability to allow for comfort and easy bodily movements of the diver. Specifically, the suit material should have a thermal conductivity or k factor of less than 0.6 and preferably less than 0.5 B.t.u. per hour `per square foot per inch thickness per F. temperature difference. It should be resistant to pressures of up to 270 lb. per sq. in. or more, and it should have an elongation of at least 100% and preferably over 400%. The modulus should be less than p.s.i. at 100% elongation and preferably less than 20 p.s.1.
The problem inherent in these requirements is that `any material which is soft enough to be comfortable and ilexible will also be compressible and will lose its insulation value. On the other hand, any material which is sutiiciently rigid to be substantially incompressible in deep water and not lose its insulation value will not be suiciently flexible for practical use.
In the past some diving suits have been constructed with integral electrical heating apparatus while others "ice have been made with both electrical heating and air pressurizing to avoid loss of insulation value due to compression. These air pressurized suits, however, are fairly delicate in that any tear on the outside surface will release the air and cancel the value of the suit. Also, they are somewhat dangerous in that any over-expansion of the suit due to increase in internal air pressure could cause the diver to rise to the surface quite lrapidly, which might result in his death.
It is therefore the principal object of the present invention to provide an underwater garment which is flexible and stretchable and yet provides good thermal insulation.
Another object of the present invention is the provision of an underwater garment which is substantially incompressible in thickness even in deep water.
The present invention also has as its object the provision of an underwater garment which is flexible and stretchable in length and width, but is substantially incompressible in thickness to retain a relatively low thermal conductivity.
Another object of the present invention is the provision of means for supporting compressible core material for use as an incompressible low thermal conductivity underwater garment.
These and other objects will be apparent on careful consideration of the following speciiications and claims when read along with the accompanying drawing in which:
FIGURE l is a view partly broken away, showing the underwater garment of the present invention assembled on a diver.
FIGURE 2 is a partly exploded perspective view of the garment material including the outer skins and the core material in the form of sections.
FIGURE 3 is a cross sectional partly `broken away side view of the underwater garment of FIGURE 2.
FIGURE 4 is a crosssectional view similar to FIG- URE 3 showing the flexibility of the garment material.
FIGURE 5 is a cross-sectional side view similar to that of FIGURE 3 showing the garment material under tension.
FIGURE 6 is a plan view partly broken away showing alternate shapes for the sections of core material between the outer skins.
FIGURE 7 is a cross sectional side elevation view of a modification of the present invention showing alternate form of connecting sections to the outer skin.
FIGURE 7a is a cross-sectional side elevational view of another modification of the present invention depicting- Stringing as the means of securing the sections together.
FIGURE 8 is a cross sectional side elevation view of another embodiment of the present invention showing the use of an open cellular material which has received means for preventing the compression of the garment material along the thickness.
FIGURE 9 is an enlarged view of a portion of FIG- URE 8.
Briefly, the present invention includes the discovery that the problem of maintaining the flexibility and stretchability and at the same time providing the necessary incompressifbility along a thickness dimension for a material to be used as an underwater garment may be overcome through the use of at least one outer skin layer which is iiexible and stretchable in two directions onto or between which is secured at least one individual and distinct secction of a core material including cells which are substantially incompressible.
FIGURES 2 and 3 of the drawing clearly disclose the construction of the underwear garment G of FIGURE l. The garment G is made from a composite structure 10 which is for-med into the shape of the human body, as shown in FIGURE l. The composite structure 10 may be composed of upper and lower outer skins 12 and 14, or only a single skin which would be on the side of the garment in contact with the Water. The skin is formed lfrom a flexible and stretchable material which should have characteristics of ease of elongation, good tensile strength, and resistance to tearing. Any one of many elastomeric materials would be usable, among which may be included natural rubber, styrene-butadiene synthetic rubber (SBR), nitrile-butadiene synthetic rubber (NBR), chloroprene synthetic rubber (CR), ethylene propylene synthetic rubber (EPDM), urethane elastomer, or any combination of these materials with any other elastomeric materials. Two-way stretch fabrics such as knitted .stretch nylon can also be used.
Neoprene is particularly useful as the material for the outer skins 12 and 14, since it is stretchable and flexible and may be expanded to a closed cellular structure with a density in the range of to 30 lbs. per cu. ft., usually about 15 to 20 lbs, per cu. ft. This expanded neop-rene has a thermal conductivity (a measure of its insulation value, lower figures indicating better insulation) of around .30 to .40, usually about .35 B.t.u. per hr. per sq. ft. per in. thickness per F. temperature difference. This material has a softness (or hardness) of 2 to 5 p.s.i., as measured by the standard ASTM test method. Because of the material being very easily flexible and stretchable, it characteristically possesses comfort and does not restrict the movement of the diver. This :stretchability may be measured in terms of modulus, which is in the range of 5 to 30 p.s.i. at 100% elongation and 10 to 50 p.s.i. at 200% elongation.
While it has been found that neoprene rubber is particularly suitable for the outer skin materials, since it has the necessary qualities of stretchability in length and width and is flexible and does provide a measure of thermal insulation, it must ybe understood that other elastomeric materials can be similarly used, including those that have been expanded into a foam structure, as well as those that do not have a cellular structure. The foam material, however, could not be usable alone, since, in order to be suitable as an outer skin material, it must be quite soft and is, therefore, easily compressible in deep water.
The core material 16 is the part of the composite structure 10 that prevents the compression of the garment under the pressure conditions experienced in deep water. In one embodiment of the p-resent invention a rigid material 16 is formed into a plurality of adjoining sections 18, which may take any particular shape such as the square or the rectangular shape of FIGURE 2, or the hexagonal shape as shown in FIGURE 6, the shape of the section not being important.
It is important when a rigid core material is used that the sections be individual and distinct and rfree to move relative to each other Within the contines of the outer skin, as shown in FIGURE 4.
The rigid core material in the form of sections 18 is secured to the outer skins 12 and 14 by any suitable adhesive, 4as shown at 20. The sections may be placed closely adjacent or abutting each other or somewhat spaced; however, they should not be spaced so far apart so as to permit an intrusion of the upper and lower skins between the sections and thereby permit contact ybetween the outer skins as might occur under high pressure. Accordingly, the space between the sections should not be greater than about 1A in.
The core material 16 of this embodiment may be made of any of a great variety of materials, both natural and synthetic, among which may ibe expanded or foamed urethane, polystyrene, polypropylene, balsa wood, cork, mixtures of cork and neoprene, and mixtures of these or other materials which have a cellular structure, including cells 22, incompressibly formed from rigid cell walls 24, forming an incompressible matrix 26 between these walls, as shown in FIGURE 3.
To perform in a satisfactory manner, the core niaterial should be able to resist compression under pressures as high as 270 p.s.i., and if the material is so resistant to the compression, it will retain a substantially high thermal insulation value. The core material should also have a thermal conductivity (k factor) of less than approximately 0.6 and preferably less than 0.5 B.t.u. per hr. per sq. ft. per in. thickness per F. temperature difference. The insulation value as measured by the thermal conductivity of the core material should be maintained within about 20% to less than a 50% loss for each p.s.i. pressure. Preferably the change in k factor should be not greater than approximately 10% per 100 p.s.i. For ideal material, the thermal conductivity should be reduced less than 10% at pressures of 270 p.s.i.
As a criterion `of the compressibility permitted in the core material, it may be stated that the loss in volume at 100 p.s.i. should not be more than 10%.
The core materials that have been found to have both good insulation and the quality of substantial incompressibility are the expanded or foam products having a gas, such as, air enclosed or trapped in small cells. It follows usually that these materials have low densities and low thermal conductivity, both desirable characteristics for core material, in accordance with this embodiment of the present invention.
A desirable-but not essentialnquality of the core material is that it have a high resistance to water absorption. Since any absorption of water would be expectcd to increase the thermal conductivity and therefore result in a decrease in the insulation value of the garment, the greater the resistance to Water absorption, the more effective is the garment for `deep Water usage. The foam materials previously mentioned, which are of the closed cell type, inherently are resistant to water absorption, and therefore are particularly desirable. It is desirable that these materials also be provided with a smooth, closed surface which is in itself impervious or leak-tight to water. The use of the closed cell foam material is preferable, though not essential, however, over any other rigid core material which may have a leakatight coating, since the closed cells of the foam provide the water resistance Without any dependence upon the integrity of the Vouter surface.
The desirable Water resistance may be measured as not greater than 20% absorption by Weight in any 24- hour period at 100 p.s.i. Preferably, the absorption should be less than 10% water.
A hard expanded natural or synthetic rubber foam having a density of approximately 12 lbs. per cu. ft. and compressive strength of approximately 250 p.s.i. and a water absorption at 100 p.s.i. `of less than 5% by Weight is found to be a satisfactory material. A rigid polypropylene foam with similar properties would also be satisfactory. Other material, such as balsa wood or cork have desira-ble low density and very substantial compressive strength, however have a fairly high water absorptivity compared to the rigid rubber or synthetic rubber foams.
Accordingly, it has been found that if it is desired to have high water resistance for the core material that cork and balsa wood or other materials may be coated with a leak-tight material, such as shellac, varnish, or coating of other water proof nlm-forming material.
In FIGURES 4 and 5, the flexibility and stretchability, respectively, of the composite material is clearly shown. In FIGURE 4, it can be seen that the sections of core material may freely pivot or are movable relative to each other, while in FIGURE 5 it is to be noted that the stretching of the material is possible even under high pressure.
FIGURE 7 shows an alternate embodiment to the adhesive securing means for maintaining the sections 18 within the outer skins 12 and 14. As shown, the sections 18 are held in position by rivets 28 which pass through openings 30 in the sections 18 and are received in openings 32 in both the outer skins 12 and 14. The construction of FIGURE 7 may not be waterproof at deep water pressures, but would be elective at the medium depths. It should also be noted that any other means of fastening the core material to the skin, such as stitching, may be used. Also, it is possible, as shown in FIGURE 7a, to connect the individual pieces or sections of core material together, as by Stringing as a bead, with each section having oppositely directed transverse bores 33 to receive the string or cord 33a material therethrough. In this case only selected sections need be secured to the skin, the remaining sections `being held together by the cross Stringing.
FIGURES 8 and 9 depict the further embodiment of the present invention in the utilization of a different core material 34. This core material may be of the open cellular foam type, such as neoprene or urethane or any other soft, flexible material which possesses voids or compartments 36, but would not be satisfactory alone to meet the requirements Iof the present invention, due to the normally high compressibility. In this aspect of the present invention, it is contemplated to utilize any of the soft exible materials which have open interconnecting voids or compartments 36 which are formed by sides 38. To add incompressibility to these voids 36, incompressible means in the form of 1rigid microballoons or cells 40 having rigid walls 42 may be sifted into the open cellular structure to substantially till up the voids 36, as best shown in FIGURE 9. These microballoons are commercially available and are generally formed from any rigid material, such as glass, polystyrene, polyurethane, ceramic, etc., and should be considerably less than 1A@ in. in diameter and may even be less than approximately 1 millimeter in diameter. These microballoons are generally hollow and may contain air or -other gas, acting as a thermal insulator, and importantly the rigid walls 42 act as a supporting means to the microballoons or Vcells 40 to provide incompressibility to the void or compartment 36 of the core material. Of course, sufficient num- =ber of these microballoons must -be placed into the voids 36 so as to substantially iill the volume of these voids.
It is to be understood that the means for supporting the cells 22 and voids or compartments 36 of the respective core materials 16 and 34 which provides the substantial incompressibility includes for the cells 22, (a) the rigid cell walls 24, and (b) the core material 2-6 integral with and forming a matrix between the cell walls 24 and cells 22, while the means for supporting the microballoons or cells 40, positioned with the voids 36 includes the rigid walls 42 of the microballoons or voids which maintain the necessary rigidity and incompressibility.
The core material 34 may be in sections, as 44 of the same size as the core material 16, previously described. The sections have a shape as shown in FIGURES 4 and 6. These sections 36 may be positioned as shown in FIG- URES 2 to 6, and adhesively secured to one or more outer skins 12 and 14 in the same manner as previously described. The presence of the microballoons 40, which roll over one another to provide an inherent flexibility, permit the core material to be formed in a single section, if desired. In order to prevent the removal of these microballoons from the core material 34 and also to prevent water absorption, the individual section may be coated on its raw or exposed edges 46 with any leak-tight coating material, such as previously mentioned.
After the sections are secured within the skin, the
microballoons may be sifted into the open cellular foam material, such as the neoprene, as shown in FIGURES 8 and 9. When the voids 36 are lled with the microballoons 40, any compressive stress applied across the thickness of the composite material 10 will result in substantially no compression of the core material 34, since the microballoons are incompressible and will resist any compression.
In manufacturing the underwater garment, including any of the embodiments described, the pieces of skin material are rst cut into patterns of appropriate size and shape for manufacture of a completed suit. The individuall sections 18 or 44 `are cemented or otherwise axed, as by rivets 28, to the outer skin material 12 and 14. Preferably about 1/2 in. of the skin material is allowed to extend on alternate edges to form flaps which can be cemented to the skin of the next piece during assembly of the suit.
It should be clear that the composite construction of the present invention provides a exible, stretchable material which is substantially incompressible and meets each of the requirements for a deep water garment.
From the foregoing detailed description, it will be evident that there are a number of changes, adaptations, and modifications of the present invention which come within the province of those skilled in the art; however, it is intended that all such variations not departing from the spirit of the invention be considered as within the scope thereof as limited solely by the appended claims.
I claim: 1. An underwater garment thermally insulating the wearer against cold water comprising:
an outer skin formed from a continuous liexible, stretch- -able sheet material;
at least one individual separate and distinct section of a cellular core material secured to said skin;
said section having a plurality of cells;
means within said section forming a part of said cells maintaining said section substantially incompressible,
whereby said garment is stretchable in only length and width and substantially incompressible in thickness under deep water pressure to retain a substantially low thermal conductivity.
2. The garment of claim 1, wherein said skin consists of upper 'and lower outer skin containing therebetween said core material.
3. The garment of claim 2, wherein the core material has a compressibility of not more than 10% loss in volume at p.s.i.
4. The garment of claim 2, wherein the core material has a compressibility resulting in not more than a 50% loss in k factor at 100 p.s.i.
5. The garment of claim 2, wherein said means are rigid cell walls of core material forming said cells, and said cells are closed and formed integrally within said core material.
6. The garment of claim 2, wherein the core material is an expanded elastomer.
7. The garment of claim 2, wherein said core material contains voids and said cells are a plurality of rigid microballoons positioned within said sections substantially lling said voids.
8. The garment of claim 7, wherein said means is the rigid wall of said microballoon.
9. The garment of claim 7, wherein said microballoons are hollow and less than .l inch in diameter.
10. The garment of claim 2, wherein one of the outer continuous skins extends beyond said core material to form an overlap to form a leak-tight seal with an adjacent skin.
11. The garment of claim 2, wherein each section of said core material is covered by a leak-tight film-forming material.
12. The garment of claim 5, wherein the core material has a compressibility of not more than 10% loss in volume at l0() p.s.i.
13. The garment of claim 6, wherein the core material has a compressibility of not more than 10% loss in volume at 100 p.s.i.
14. The garment of claim 4, including an 'adhesive securing said sections of core material to said skins.
15. The garment of claim 4, including rivets securing said section of core material to said skins.
16. The garment of claim 7, wherein said microhalloons are loosely positioned between said upper and lower outer skins, substantially filling space between said skins.
17. The garment of claim 7, wherein said core material is an open-cell flexible foam adhered to and between said skins and loosely positioned said microballoons between said skins.
18. The garment of claim S, including said core being made of a plurality of sections.
19. The garment of claim 18, wherein the sections are strung together.
20. The garment 0f claim 2 wherein said upper and lower outer skins are separated without mutual Contact.
References Cited UNITED STATES PATENTS 267,799 1l/l882 Plant 9-341 1,106,728 8/1914 Roberts 2*2.1 X 1,831,472 11/1931 Abramowitz 9--340 2,802,222 8/1957 Chapman 9-340 2,981,954 5/1961 Garbellano 2-82 X 3,337,876 8/1967 Armstrong 2-2.l
RICHARD I. SCANLAN, JR., Primary Examiner.