US2935985A - Airtight helmet - Google Patents

Description

May 16, 1960 F. w. ANDREWS ETAL 2,935,985

AIRTIGHT HELMET Filed Nov. 19, 195i 6 Sheets-Sheet 1 NVENTOR FRED WAfvorezw WILBUE A.

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A TTOK/VEYS.

May 10, 1960 F. w. ANDREWS ET AL 2,935,985

AIRTIGHT HELMET 6 Sheets-Sheet 2 Filed Nov. 19. 1951 JNVENTORS o W. Awmazws.

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ATTOKNEVi F. w. ANDREWS ET AL 2,935,985

AIRTIGHT HELMET May 10, 1960 Filed Nov. 19, 1951 6 Sheets-Sheet 3 INVENTOK FRED WANDREWS. Wu LBUR A.MILL.ER. BYWALT'ER L.Luowl i.

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F. w. ANDREWS ET AL 2,935,985

AIRTIGHT HELMET May 10, 1960 Filed Nov. 19, 1951 6 Sheets-Sheet 4 INVENTORS. FRED WANDREWS. Wu euR A.Mu.| 'R.

BYWALT ER L.LuDw|G.

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A TI'ORNEYS.

y 1956 F. w. ANDREWS ETAL 2,935,985

AIRTIGHT HELMET 6 Sheets-Sheet 5 Fiied Nov. 19, 1951 I Face WA fionzws;

Wu.aun A .MILLER.

BY WAm-en L.Luow|a.

7111* W flu ATTURNEKS.

y 9 F. w. ANDREWS ETAL 35, 5

AIRTIGHT HELMET Filed Nov. 19, 1951 6 Sheets-Sheet 6 INVENTORS. FRED \MAuonaws. WILBUR A.Mu.| E.R. BY W LTER L.LUDW\G.

ATTORNEYS.

, 2,935,985 f 'AIRTlGHT HELMET Frederick WJldndrwsbnd Wilbur A. Miller, Dover, Del.,

,5 Application November 19, 1951, No. 57,002

' 15 c aims.- cl. 128 -141) This invention relates to an'airtight helmet or head d w e Qfi e piece adapted to enclose the head'of-the wearer. Since the intended purpose of the invention is to provide a Y helmet which will permit a relative internal pressure to be attained and maintained. at desired periods of use it A will be designated a pressure helmet for convenience.

The internal pressure being relativetoand greater than the 'external pressure, the degreeof Iessure will vary as to 'the environment in which the helmet; is used.

fTheparticular embodiment to rbe" described hereinafter, as illustrative of the invention, is intended particularly for the use of aviators and aircraft personnel subjected to high altitude operations-where the atmospheric pressure is drastically reduced. However, the invention is believed to be well adapted for other uses, such as for l divers. In' fact, in its broadest aspects the invention" is useful wherever it is desirable to encase the human head in an airtight chamber or a chamber which-is-c apable of rnaintai'ning a positive internal pressure to preventing gress'from the external, suchas poisonous gases. -"Ifhe' invention may either be'usedseparatel'y' as a-"helmetj-or may be attached'to' a 'suit of any of-the wellknown forms for enca-siug the body, either an inflatable (pressure) suit or a tightly fitting suit, both of which types are known to those skilled in the art. 1

" It is well knownfthat at high altltudes the human body must be encased in such a m-anner as to-protect it from the extremely low pressure of *the atmosphere and order: tofacilitate breathing the oxygen supplied must be under pressure greater than the external air pressure and to relieve the head of the wearer from dangerous abnormal low pressure. It is advantageous also to have'the head of the wearer subjected to a pressure greater than the external pressure and to supply the oxygen into the pressurized enclosure. For this reason it has been proposed to provide helmets to entirely encase the human head; but many difiiculties have been-encountered. P

acter described'clo'sely conforrmng to the contour-of the if wearers head'and-adapted for closefittingcontiguous thereto, throughout the major portion thereof, while permitting freedom of'move'ment ofthe Another object is to provide a pressurelhelmettriei mitting ready movement of the encased head when the helmet is pressurized. i

m A further object is to provldea helmet having means to relieve the head of the wearer of uplift pressure when' the helmet is pressurized. Another object is to provide a combined crash 'and pressure helmet.

Another object is withstand high velocity air flow. r 1

Further objects,- advantages andfeatures of the invention will be understood from the. following detailed description taken in connection with-the accompanying drawings hereinafter referred to .and in whichf Fig. l is a side elevational view, partly in'sectiom'and with certain parts omitted, for simplicity, I showing a present embodiment of the invention in position for use; Fig. 2 is a similar view of the front portion of the device of Fig. 1 with its face piece and outer shell removed; Fig. 3 is a similar view of the face piece detached from the remainder of the device of Fig. l; I #Fig. 4 is an enlarged (approximately full size) side elevationalview ofthe front-rportion of the device of Fig. 1, showing certain parts in section to better illustrate'cere tain details and certain parts'omitted forsimplicityj Fig.:5 is a-frontJelevationalview of thedevice on-the same scale as shown in. Fig. 1', showing'means through which oxygen may be introduced and spent exhalation emitted, microphone mount and plug-in means which were omitted from Figs. 1-4; Fig. 6 is a cross-sectional view taken on the line 6-6 of Fig. 5 showing further details of the' face panel seal; I Fig: 6a is across=sectional viewtak'enbnlineia-f-fifl of Fig. 5 showing 'flirtherydetails Of-.the5P B' n j microphone mount; 7

:Fig. 7 is an enlarged cross-sectional viewtaken on' line 7-7 of Fig. 1 showing 'and-outershell joint; anenlarged cross-sectional view takenon I line 8-8 of Fig. 1 w1th:certa-in;parts omittedto' more Cne of the chief difficulties has been to providea I .pressurehelmetwhich meets the several requirements of aviators Such a helmet must effect a sure seal-around the neck, in order toprovide a relatively small chamberv into which oxygenmay be su'pplied fo'r inhalation and also. to permit ofpressurization to the desired extent. Additionally; there must bea transparent front panel 'or face pieceand this should be readily removable and replaceab-le with alacrity andcertainty cine-establishing sealed "relationship. Further, comfortand freedom of head movement of the wearer are of. extreme imporJ- tance. From the standpoint of storage and handlingas well as for comfort, the helmet hood preferably should be collapsible and flexible to a large extent.

An object of this invention .is pressure helmet;

' Another object is ,fct-ihg a quiek and sure seal between said panel and to provide improved H topro 'de a helmethaving alquick- .ly and readily removable face panel and means "for efclearly show the collar structure ofthe bladder;

' Fig. 9 is a segment, elevation, of the -parts' illustratedin'Fig. 8;

Fig. 10 is a side elevational viewof the device l 1own in' Figs 15-9, ona somewhat reduced scale, withcert-ain ph rgts hrokennaway;to showafurther detaileofthe erior structure, more particularly the'shock pads; f}- I Fig. 11 is a plan view showing the-arrangement f the pads of Fig. 10', 1 A

Fig. 12 is a diagrammatic side elevational view mllus trat-ing pressure distribution in the use of the devi 9 shown in Figs. 1-11 and the resultant uplift pressure *Figs. 13-14 are side and front elevational view .sp'ectively, of-the device shown in Figsr 1-;1,1 (with c r.- tain'paIts-omitted for simplicity) showing further details of the meansfor resisting the upliftfpressurm. 'Fig. 15 is a' diagrammatic side elevational- 'ew,-similar to Fig. 12, illustrating the pressureqdistributionirra modified deviceinwhich provision is made-.to equalize the. uplift pressure in the helmet, instead of externally resistingit as inFigs.'1-.14;

Fig.- 16 isia side elevational view, partly in section, showing. amodified form. of helmet embodyingtheprin- .ciples diagrammaticallyillustrated in Fig. 15;

to provide a crash helmet which ean details of thezippen closure 3 F g 1 is a c ss-sectio al ie sho ng t in. mo fied features of construction of the device shown in Fig. 16; .Fig. l8 is a plan viewof the modified structure shown in Fig. 17; and

Figs. 19-20 are cross-sectional views taken on lines 12-19 and 20720 respectively of Fig. 16 showing fur, ther particulars as to the manner of attaching earphones.

Referring to the, drawings and more particularly. to Figs. 1, 2 and 3; the helmet comprises in general a relatively flexible. hood or body portion designated in its entirety as T1 to which is. secured a relatively rigid frame 2, defining a face opening, and a face piece or panel 3 of transpagent material removably secured to said frame in sealed relationship with said hood. Preferably, the hood is provided with interior padding and an exterior crash shell.

Hood

The main portion or body of the hood 1 comprises an outer cover 4 (Fig. 4) and an inner layer or lining 5. The. outer cover will be described first. The outer cover his made of relatively non-elastic material, such as nylon fabric, of a thickness and weave to resist stretching and is made to conform substantially to the contour of the average size head. In order to provide a smooth contour the outer cover is composed of a plurality of pieces connected together as at seams such as S. To insure a close fit, cooperating lacing strips 6 and 7 extend in spaced apart parallel relationship from the lower edge binding strip 8 upwardly on one side behind the ear position and thence forwardly and upwardly across the top to the rear of the forehead and downwardly on the other side along a corresponding path, the strips 6 and 7 being secured to the fabric cover, and a lace 9, preferably madeof nylon, is. passed alternately through loops provided on the respective strips 6 and 7. This permits the hood cover to sufiiciently stretchable and elastic that it may be readily expanded to a diameter large enough to pass over the head of the wearer and when in position around the Wearers neck return to a size to lie closely adjacent the Wearers neck. For this reason we prefer to make the neck portion of a thickness of the order of .Ol".015". From an operational standpoint it may be much thinner, but if too thin it will'be subject to tearing in service. Likewise a thickness greater than approximately ..02()" will make. it exceedingly difiicult to stretch over the Wearers head. Therefore, it is important to keep the neck portion within the limits of .005 ".020" thickness. The thickness ofthe flap c and the remainder of the bladder, other than the neck portion 5b, is not so critibe: adjusted to snugly fit a given head. The cover at the rear is provided with a centrally disposed slit extending from about the crown point designated 10 downwardly through the lower hood edge 8 and suitable slide fasteners, such as 11 (Fig. 7), are secured to the edges of the hood at the slit and are cooperatively engaged by a slide 12 for closing or opening the hood at the rear. Toprotect-the inner lining or bladder 5 a flap 13 is provided.

It will be seen from Figs. 1 and 5 that the outer cover 4' closely conforms to the head contour from the front zone, which follows a path across the forehead doe wardly' on opposite sides across the temples and thence beneath the chin, so as to enclose the remainder of the head and neck down to the binding strip 8 at the juncture of the neck'with the shoulders.- The portion of the cover .4 corresponding to the chin area is designated 4a and the tubular neck portion is designated 4b. At the face opening the cover 4 is provided with a reinforced and beaded edge 40- (Figs. 4 and 6) formed such for example as by securing a wire member 40? within a turned over edge of the cover fabric.

The inner layer or lining 5 conforms to the shape of the outer fabric cover 4 and is preferably made of highly elastic material, such as latex rubber, in the form of a bladder whose entire area is impervious to air under pressure. The preferred manner of making this bladder is by dipping. The chin portion of the bladder 5 (Fig. 4) is designated 5a, and the tubular neck portion is designated 5b and is sufiiciently long to provide an inturned 'collar portion 5b for purposes to be hereinafter described. The face opening of the bladder is outlined'by a continuous marginal flap portion 50 which extends beyond the beaded edge 40 of the cover 4 and is provided with a beaded edge. The marginal flap 5c serves'as-a sealing flap to effect a'seal between the bladder 5 andthe face piece 3in the manner to be describedhereinafter. It is especiallyimportant that the neck-portion 55 be cal. We have found that entirely satisfactory results have been obtained with a neck thickness of .010"- .015", a thickness of flap 5c of the order of .020" and the remainder of-the bladder varying from .020 thickness to .04 V at the top of the head: the greater thicknms at the top being due to the fact that this point corresponds to thelower end of the dipping form. 7

Face frame With the bladder 5 disposed within the fabric outer cover 4 and the flap 5c of the bladder extending beyond the beaded edge of the. cover 4, the frame 2 is secured to the hood in the manner now to be described. The frame 2 is concave in side elevation (Figs. 1 and 4) and is oval in front elevation (Fig. 5) and is so shaped and proportional as to pass across the forehead and rearwardly down along the temples, forwardly and downwardly across the checks and thence below and slightly forwardly of the chin.

The frame 2 is Of rigid construction, the present embodiment being made of sheet metal suitably formed in the shape to be more particularly described below. The frame comprises an inner section 15 which in the present embodiment is made in one piece and an outer section 16 between which and the inner section 15 the outer and; inner members 4 and 5 of the hood 1 are adaptedto be securely clamped. To facilitate clamping, the outer section 16 comprises an upper part 16' and a lower part 16"which are adapted to be clamped together by suitable fastening means, such as machine screws 17 and 1 8. The, juncture between the outer frame parts 16 and 16 is preferably along a transverse plane intersecting the; frame at its maximum width. The outer section 16 (Big. 6) at its lower end isprovided with a concave recess 16a and a rearwardly extending portion 16b joined by a curved section to a rearwardly extending lip portion 160 offset inwardly of the frame from the portion 16b. The inner frame section 15 is provided with respectively corresponding and cooperating portions 15a, 15b and 150. The upper. portion of the frame (Fig. 4) is similarly shaped except that the portions 15b and 16b and and 16c are directed upwardly as well as 'rearwardly. These portions gradually change direction from the top ofv the frame to the bottom of the frame; .the important characteristic being that in the upper part of the frame, say down tothe point of juncture of the outer frame part 16' and'16", theportions 15b and 16b and the adjacent portions 15a and 16a provide an overhanging downwardly extending flange for receiving the upper part of theface piece 3, While in the lower portion of the frame below said juncture the corresponding flange extends more nearly in a fore and aft direction. In assembling the frame andhood the beaded edge 4 c and corresponding adjacentportion of the inner lining of bladder 5 are disposed-withinthe groove provided by the recessed portion 15a and the outer sections 16' and.16" are placed 'in position as shownb'est in Figs. 4 and 6, with the outer and inner hood members 4- and 5 intimately'disposed betweentheframesectionslS and 16, and the parts are securely assembled by means of the machine. screws 16 and;17. In assembled position the; sealing flap, 5c exposition is anchored to the bracket tends an appreciable distancebeyond-the recessed portions of the frame, it being noted that the flap c is additionally.-' l 'ocked in position and is given a predetermined 'dir'ec'tionmore .or less in the plate of the frame by means of a lip 16d formed on the outer edge of the frame section 16 and serving to intimately clamp the sealing lip the upper portion corresponding to the portion 16' of the outer frame section is placed against the sealing strip 5c and is then pushed upwardly behind the downwardly and forwardly projecting flange of the frame, above referred to, and the lower end of the face piece is then pushed inwardly within the flange at the lower portion of the frame (Fig. 4) until the sealing strip assumes the shown in Fig. 4, from which it will be seen that the strip passes over the marginal front face of the panel 3, around its peripheral edge and downwardly to the rear of its inner face. In this position the interior of the frame surface coinciding with the portion 5a closely confines the strip against the front surface of the face piece 3;. To assist in centering the face piece with re- "spect to the vertical axis of the frame a guide plate 20 (Figs. 4 and 5) ,is secured to the frame section 16 at its'upper portion and is provided with a centrally disposed slot 21 for receiving the centering pin 22 rigidly secured to the face piece 3-. A quick actuating catch is provided for locking the lower portion of the face piece in position, which mechanism comprises a lug 23 (Fig. 4) rigidly secured to the outer frame section 16 and extending downwardly therefrom; and a U-shaped catch member 24 having a rear cross barZS and side arms, such as 26, whose free ends are pivotally attached as at 27 to a mounting bracket 28 suitably rigidly secured to the face piece 3, the member 24 beingurgedto closed posi- 29, the upper end of'which' 28 and the lowerfree'end' tion by a suitable spring of which engages the member 24-. To facilitate quick release ofthe catch a latch string 30 secured to the cross bar member 25 is provided at its lower end with a small weight 3 1. To assure quick register of the catch member 24 with the lug 23 a pair of laterally spaced pins 32 are rigidly secured to and extend downwardly from the outer frame section 16, the catch member 24 being slightly tapered to guide it into latching position.

I I Breathing and audible means Suitable ingress and egress to the space within the helmet is provided in the following manner.' An elbow tube 33 (Fig. 5) is secured to the panel 3 in register with a hole provided therein and a suitable inhaling valve (not shown) is employed for controlling the ingress and preventing egress from the tube. The free end of the tube may be suitably attached, as by a flexible hose, to a source of oxygen under controlled pressure. An exhalation valve 33a, located to the left of tube 3-3, is likewise secured to theface panel 3 in register with a hole provided therein. A compensating tube 33b connects the two valves.

, Suitable ear phones, designated in general as 34 and 35' (Figs. 4 and 5), and a suitable microphone, such as 36, may be disposed within the helmet. Since these devices per se are not a part of the present invention they are merely referred to in general to indicate their use andpreferred location and mounting. Preferably the earphones are supported from the crash pads'to be, more particularly described hereinafter with reference to Figs. 1 0 and, 1,1 The microphone 36 (Fig. 6a) is carried on-the outer end of "an arm 36aiwhose inner end is pivotally connected toa supporting bracket 36b, rigidly fas- 15c, onthe lower right hand side as viewed Fig. 5.; This mounting is so arranged that the parts do not inter fere with' the sealing flap 5c of the bladder 5. The swinging arm 36a is resiliently held in speaking position by spring 360 which is fastened to the bracket 36b and has a free end which presses against a fiat spot on the'center hinge of arm 36a. In this manner the sw'mging microphone may be adjusted in the correct position close to the mouth but is movable in both directions against the pressure of spring 360; thus protecting the face, of'the wearer against damage in case of bumps or shocks. This.

mounting further perrmts the microphone 36 to be swung outwardly, as indicated by broken lines in Fig. 6a,- sotas to'clear the mouth when p I To facilitate service connections with the ear phones 34 and 35 and with the microphine 36 a. jack designated gener-ally as 37 is provided. The jack comprises a body portion 37a havinga flange at its inner and secured to the inner frame member 15c inter-iorly of ;the bladder 5. The neck of the body 37a, extends outwardly through a tight fitting opening 5d provided in the bladder 5 and through a corresponding opening provided by a. grommet" 4g secured in the flexible cowering 4. The body i s held in sealing engagement by means of a clamp collar 37b. The jack 37 is suitably connected to theear phones and microphone and is adapted to receive the input conductors, all in the usual manner. also be used for other electrical connections where desired, such as an electrical heating element (not shown When the device is in operative position, the lower end of the collar portion 5b (Fig. 4) is disposed inwardly and the inwardly and upwardly turned end is designated 5b. When disposed in this. position the inturnedportion 5b is of such size and character-to closely and in timately seal against the neck of the wearer.

i pressure is introduced into the closed andjsealed, helmet the,,pressure is exerted between the collar portion Sb and the inwardly disposed and upwardly turned end thereof '5b-'-.- The outer neck portion 4b of the fabric cov er 4 restrains the outward expansion of the bladder neck portion 5b and the resultant force is exerted on the inturned tubular neck portion 5b to urge it into positive sealin engagement with the neck of the wearer. Under pressure there is a tendency for the inturned portion 5b! to be urged downwardly into alignment with the outer portion 5b. To maintain the parts in the desired position strips, such as 5d (Figs. 8 and-9), are'dispos'ed at spaced intervals peripherally of the collar, having their upper and lower ends secured respectively. The lower ends of the strips 5d are, fastened to the inturned portion 5b somewhat below the sealing edge to avoid interference with a dependable seal. Additionally, after. the helmet is in position on the wearer (=Fig. 4) a restraining collar 40 of unyielding material, such. as nylon, prefer-ably is placed in position exteriorly of the outermost part of the tubular neck 5b. In this way it is not necessary to have the outer cover at the neck portion 4b to make such an accurate and perfect fit with the neck of the wearer and the outer portion 5b of the bladder neck is restrained by the collar 40.

In the device described the panel 3-is subjected'to substantial external pressure at times and for this reason the flange 15c is disposed and positioned as shown best in Fig. 4 to reinforce the frame 2. A resilient pad 41, preferably made of latex foam, sponge rubber or the like, is disposed at the rear face of flange 15c and extends downwardly on opposite sides of the temple zones so as to-rest across the forehead downwardly along the temples.

: Crash protection structure In helmets of this character the wearer is often jected to buffeting and some times to crash landings. In

.tened to an integral extension of the inner frame member 1g order to relieve the wearer from resulting discomfort and the face panel 3is removed.

This jack connection may When to prevent serious damage the following provisions are made.

Supplementing the cushion 41, there is provided within the bladder (Figs. 10, 11 and 4) a grid-like cushion comprising a central strip 42 which extends from adjacent the strip 41 rearwardly across the head and downwardly to a point approximately behind the wearers cars, a strip 43 extending laterally from the rear end of strip 42 on respectively opposite sides around the rear of the wearers head and terminating closely adjacent the Wearers ears, and a transversely disposed strip 44 extending crosswise over the head and downwardly on respectively opposite'sides in substantial alignment and terminating slightly above the ears. These strips are preferably integrally formed one with the other and are relatively narrow. The grid-like cushion thus disposed is made of soft flexible material, such as foam or sponge rubber, covered with leather. For the reasons to be pointed out following, this cushion grid is built up around a metal frame or spider 38 which is embedded in the core nearer the outer surface than the inner surface so that the major thickness of the padding is located on the underside of the spider towards the head. The spider serves to conform the grid padding to the head and serves the following additional functions. The forward end of the spider 38 is pivotally connected, as by a hinge 38a to the inner frame member 15 to thereby permit freedom of movement of the paddling grid assembly so as to allow adjustment thereof to conform to the shape of the Wearers head without undue pressure or strain on the head. The lower ends of the spider arms embedded in the strip 44 carry adjustably secured thereto a pair of ear phone brackets, such as 38b, which provide a convenient means of supporting the ear phones 34 and 35 so as to permit the desired vertical adjustment of the ear phones- It is advantageous to have these pads within the bladder so as to avoid interference with the hood lacing and zipper. These pads are further useful in holding the bladder 5 away from the head when the bladder is not inflated, which is usually a large part of the time.

In order to more completely protect the head of the wearer the fabric outer cover 4 is preferably encased in an outer shell designated in its entirety as 39 (Figs. 1 and 7) preferably made of light stiff material, such as reinforced molded or pressed plastic. The shell 39 is preferably made in separable halves, such as 35a and 3%, provided with complementary interlocking ribs by which the halves may be locked together by a curved channel strip 390. The locking channel 39c has at its forward "end a finger 39d adapted to engage an undercut cooperating portion of the ribs of the sections 39a and 39b and at its rear end carries a latch 39a for releasably engaging a cooperating slot formed in the adjacent end of the rib portions of the sections 39a and 39b. The forward margin of the shell carries a plurality of fingers, such as 3? secured thereto for locking engagement in slots, such as 35g, provided in the rear frame section 15. The separate halves 39a and 3% are first locked at their forward margin to the frame member 15 and are thereafter brought together in a lateral direction into interfitting engagement and are locked in this position by the channel 390.

In Fig. 12 there is diagrammatically illustrated the pressure distribution Within a pressurized head enclosure of the general character described. From this it will be seen that the pressure acting outwardly is equalized in all directions except with respect to the area NA of the neck and the corresponding area UP on the top of the head. The differential in pressure between these areas results in an uplift which is appreciable. For example, assuming the average area of the neck to be 18 square inches and assuming a pressure of 3 pounds per square inch, the resultant uplight pressure will be 54 pounds. If this force is carried to the suit through the neck of the helmet secured thereto, the free movement of the wearers head will be considerably interfered with.

8 Pressure restraining means In Figs. 13 and 14 there is shown a novel means of securing the helmet to the wearers suit to accommodate this uplift pressure while at the same time providing for freedom of movement of the wearers head. The helmet has secured to its opposite sides at limited areas fastening means designated in general as 50 and 50'. These fastening means may be attached to either the outer crash shell 39 or the fabric hood cover 4, as desired. In the present embodiment they are shown attached to the fabric hood 4. Since these are identical it will only be necessary to describe one. The fastening means 50 (Fig. 4) comprises a bracket 50a whose upper end is securely fastened to the fabric and whose lower end is provided with a ball socket 5% into which is swiveled a ball 500 from which depends a shank having a yoke 50d in which is journaled a pulley 50e. Harness cords, preferably in the form of a bridle having a pair of downward extending front portions 51-51 and a pair of rearwardly extending portions 52-52 pass over the pulleys of fasteners 50-50. The portions 51-51 are interconnected at the lower ends so as to provide a loop which passes over laterally spaced pulleys provided by fastening means 53-53 suitably secured to the suit designated S and constructed and arranged as above described with respect to the fastener 50. Similarly the rear cords 52-52 are provided in the form of a loop which passes through a similar pulley provided in the fastening means 54 secured to the rear of the suit. The fasteners 50-53 are disposed in vertical and lateral alignment with the pivot point of the wearers head. This pivot point is provided by the articulated engagement of the occipital bone of the skull with the first cervical vertebrae or atlas of the spine. For convenience, the portions of the helmet in lateral and vertical alignment with said pivot point will be referred to as the helmet pivotal points. It will thus be seen that by arranging the holddown harness in the manner above described, it will permit freedom of forward and rearward movement and will facilitate other movements about said pivot point. It will also be appreciated that when the head is moved from side to side, in a rotary motion, the cords of the harness are permitted to freely slip through the pulleys of the fastening means to relieve any restriction of movement by the cords, and the same is true when the head is rocked from side to side.

Modification (pressure equalized helmet) In the modification now to be described, the device is so constructed and arranged that the pressure within the helmet is equalized to thereby eliminate the uplift force. This is diagrammatically illustrated in Fig. 15 from which it will be noted that the neck area defined as NA is equalized by corresponding and preferably identical area EA at the top of the helmet, which is free of upward pressure. In general, this is accomplished by providing a supplemental or inner bladder, designated in general as 60, which is connected to a bladder disposed within the helmet hood, generally designated as 61, in such a way as to eliminate uplift pressure in the area EA. In this modification the holddown harness is not necessary; the grid padding described more particularly with reference to Figs. 10 and 11 is omitted; and the ear phone mounting is different: otherwise the structure has much in common with the embodiment of Figs. 1-9.

Referring more particularly to Fig. 16, it will be seen that the hood 61 is secured to a rigid frame 62 defining a face opening to which is detachably secured a face panel 63 and the hood comprises an outer cover 64 and an inner layer or bladder 65, all constructed and arranged as previously described with respect to the corresponding parts 1-5, inclusive of the embodiment disclosed in Figs. 1-9. The details of construction and arrangement of parts previously disclosed in full will not here be repeated since they are identical except in the particulars noted. On the top of the hood opposite area of the neck, the outer cover 64 and bladder 65 are provided with an opening to which inneror-secondary bladder comprises a body member 70 which fits completely over the head and down the neck has a snugly fitting collar portion 71 extending below the seal' effected by the collar portion 65b thereof and the front of the bladder 70 is provided with a face opening defined by a sealing edge 72 following more or less a line extending across the forehead below the hairline and, thence rearwardly and downwardly on opposite sides of the face forward of the ears and-thence downwardly and forwardly beneath the chin. A rubber sleeve 73 of generaljcylindrical shape is provided with a lower flange .74 which is cemented or otherwise securely sealed to the upper part, of the bladder body 70 so as to bein airtight engagement therewith. The sleeve73 is of anarea substantiallyequal to the neck area. The upper end ofthe sleeve 73 is provided with a flange 75 which is adapted to beheld in' seal ed engagement with the. hood bladder 65 by suitable means, such as a ring 76, and a plate 77 which is detachably' secured to the ring 76 as by screws 78. The

area of the bladder body 70 within the sleeve 73 is provided with a plurality of holes 79 or other vented opening to" place the interior of the bladder 70 in communication with the interior of the sleeve 73 and vent slight leaks sleeve73 in'communication with the atmosphere. To

facilitate assembly, the flange 75 is cemented to the upper end ofthe sleeve 73 and the peripheral margin of the plate 77 cemented to the corresponding margin of the outer .cover 64, which in turn is cemented to the outer bladder 65. It will thus be seen that with the sleeve 73 clamped into air-tight engagement. around the. periphery of the sponge rubber or latex foampadding 70b iscemented to the plate 70a and has an extending periphery cemented to. the interior of the bladder 70. The'plate 70a and pad 70b conform to'the shape of the skull and support the low pressure area (EA) of the skull, thereby eliminating the painful uplift of the scalp from the suction due to pressure differential. The plate 70a is supported by mechanical compressive action of the pads 81 and 82 and by pressure on the rim of the plate 7 0a extending into the pressurized zone. i i V iIn Figs. 17 and 18 we have shown an alternative means of readily detachable securing means to be used in place of thesring 76, plate 77 and screws'78. In this modification :a plate member 83, provided with vent holes such as 84,'.has an outer flange85," and an upwardly extending threaded sleeve 86. The sleeve 86 is provided at suitable intervals around its periphery with slots 87 for receiving registering lugs 88 carried on the inner surface of a clamp ring 89'which slidingly fits over the sleeve 86. A locking ring 90 threadinglyengages the sleeve 86 to hold the ring 89 Eand flange 85 toward each other and to clamp therebetween theadjacent portions of-the hood and inner To facilitate" assembly, the flange 85 is cemented to the upper end of the sleeve 73and the 'clamp ring 8 9is cemented to the outer cover 64, which in turn is. cemented to theadjacent margin of the outer bladder 65.

The inner bladder body 70 is provided with openings for theears of the-wearer so that the ears of the wearer may und face seal 72; and the plate 77 is likewise provided with vent openings, such as 80, to place the interior of the be positioned between the inner bladder body 70 and the outer bladder 65 of the hood 61. Ear phones are preferably formed as an integral partof the inner bladder body 91m e r n t d mam -in 9f Part wi li s' tr thin marginal edges which seal around the root of the,

ear. A sponge cushion 101 surrounds these openings and is spaced outwardly from the periphery of the thin edge;

100, so as to leave the edge relatively free forsealing purposes. A metal shell 102 is securely fastened to. the sponge cushion 101 and is soundproofed by anfinner layer of sponge rubber 103 extending over its entireinner surface and by an outer layer 104 of similar sponge'rubber material extending over its outer surface co-extensive with the flange 105 of an ear phone 106. To prevent soundboard eflect and to permit free passage of air into the sound chamber the metal shell 102 is provided with a multiplicity of holes, such as 107, and with the relatively, large opening 108 disposed centrally of the ear phone.

In applying the modified device (Figs. 16-20) the fol-- lowing procedure is desirable. The inner bladder 70,:with: the ear phones attached, is first stripped over the head and adjusted for good fit to the ears and face and with the; neck portion 71 extending downwardly in the positiom indicated in Fig. 16. The outer bladder 65 fastened in the: position shown in Fig. 16, but with the fastening means: loosened to relieve entrapped air, is next stripped over the: outer bladder and head of the wearer and during this step the zipper on the rear of the outer hood casing 64 is open. The neck 65b of the hood bladder is placed in sealing position in the manner indicated in Fig. 4. The fastening means, such as 7577, are tightened to effect intimate: 'sealing and the hood is now ready to have the face piece be pressurized and an airtight seal is provided around the,

ears in order to subject the ears to the same pressure which the mouth and nose are subjected to.

Having thus described our invention with particularity,

with reference to a presently preferred embodiment of. the same and to certain modifications thereof, it will be obvious to those skilled in the art, after understanding our invention, that other changes and modifications may be made therein without departing from the spirit orscope 1 of the invention and We aim in the appended claims to, cover such changes andmodifications as are within the scope of the invention. W ,What we claim is: 1 v a i 1. A fluid-tight helmet comprising a flexible hood adapted to enclose the head and adjacent neck portion' of the wearer, said hood having an outer; relatively non velastic fabric casing and a thin rubber latex inner lining said lining being attached to said casing along a periph--I, eral zone disposed around the face portion of the hood i, and having a peripherally continuous neck portion unat-- tached to the casing, said casing being provided with a;

slit opening extending from the upper part thereof down wardly through the neck at the rear and having fastening means for closing the opening, and said casing being provided with size adjusting means comprising lacing extending across the upper forward zone of the top there of theme on respectively opposite sides! thereof rearwardly and downwardly along the rear half of the neck l portion on opposite sides of said slit opening.

.2. In a helmet of the character described the combinertion of a hood having a face opening defined by a sealing flap of resilient material; a rigid inner frame member of such shape and size as to provide the desire face opening and adapted to be disposed interiorly of said flap, a twopiece outer frame member shaped for cooperative interfitting engagement with said inner frame and adapted to be disposed exteriorly of said flap, said outer frame comf prising an we; st q n a sw s s men ngesill a generally horizontal plane disposed substantially at the maximum width of said frame, means for clamping said sections together over said inner section to firmly secure said flap therebetween and provide a free marginal edge of said flap extending around the inner periphery of said frames for sealing engagement with a face panel.

3. In a helmet of the character described the combination of a hood having a face opening defined by a sealing flap of resilient material, a rigid inner frame member of such shape and size as to provide the desired face opening and adapted to be disposed interiorly of said flap, a two-piece outer frame member shaped for cooperative interfitting engagement with said inner frame and adapted to be disposed exteriorly of said flap, said outer frame comprising an upper section and a lower section meeting on a generally horizontal plane disposed substantially at the maximum width of said frame, means for clamping said sections together over said inner section to firmly secure said flap therebetween and provide a free marginal edge of said flap extending around the inner periphery of said frames, a transparent face panel having a marginal edge disposed to lit within said inner frame into sealing engagement with the free marginal edge of said flap, and means for detachably securing said panel in said sealing engagement.

4. In a helmet of the character described the combinationof a hood having a face opening surrounded by a relatively rigid frame comprising an upper zone and a lower zone interconnected by side portions, said frame providing a flange extending downwardly at an upper zone and forwardly at a lower zone, and a rigid face panel having a peripheral edge whose upper marginal zone extends upwardly for insertion behind the upper zone of said frame and whose lower marginal zone extends rearwardly for insertion over the lower zone of said frame, whereby said face piece may be readily insorted in said frame by first inserting its upper end upwardly in position and then inserting its lower end rearwardly into position, said lower flange serving to keep the top of said face panel in engagement with said upper zone flange, and fastening means for securing said panel in saidframe.

'5. In a helmet of the character described the combination of a hood having a face opening surrounded by a relatively rigid frame comprising an upper zone and a lower zone interconnected by side portions, said frame providing a flange extending downwardly at an upper zone and forwardly at a lower zone, and a rigid face panel having a peripheral edge whose upper marginal zone extends upwardly for insertion behind the upper zone of said frame and whose lower marginal zone extends rearwardly for insertion over the lower zone of said frame, whereby said face piece may be readily inserted in said frame by first inserting its upper end upwardly in position and then inserting its lower end rearwardly into position, means for centering said panel comprising a slotted plate secured to the upper zone of said frame and a cooperating pin secured to the upper zone of said plate in registration with said slot, and means for fastening said plate to said frame including readily releasable latching mechanism positioned on the respectively corresponding portions of the lower zones of said frame and panel.

6. A fluid-tight helmet comprising a flexible hood adapted to enclose the head and adjacent neck portion of the wearer and having a face opening in the front thereof, said hood having an outer cover composed of relatively non-elastic material and an elastic inner layer provided with a neck encircling portion, a relatively rigid frame member surrounding said opening and a rigid transparent face panel member for closing said opening, one of said members having a notched plate secured thereto centrally of the forehead zone and the other of said members having a centering stud disposed for registering engagement in said notched plate, said members adjacent a chin 12 zone having quick releasable cooperating latching means provided 'with'readily .engageable releasing means, said latching means serving as the sole means for fastening said face panel member to said frame member.

7. In a device of the character described the combination of a hood comprising an outer restricting casing and an inner sealing bladder, and holddown harness attached to said casing on respectively oppositely disposed sides thereof at limited areas located on a horizontal axis passing substantially through the pivot point of the wearers head, said harness providing two loops each extending downwardly from the oppositely disposed attachment areas of said casing, said loops being of suflicient length to movably pass through pairs of spaced apart anchor attachments on a body covering of the wearer, whereby one of said loops may be disposed on the front and one on the back of the wearers body.

8. A pressure helmet comprising a highly resilient inner bladder for closely engaging wearers head and having face, ear and neck openings formed to closely engage the wearer around his face, ears and neck, an outer bladder having a face opening seal and a neck opening seal, a flexible tubular sleeve having a cross-sectional area substantially equal to the neck area of said inner bladder when in use, said sleeve being secured at its lower end to the top of said inner bladder and at its upper end to the outer bladder in general vertical alignment with the neck opening of said inner bladder, the upper end of said sleeve being in communication with the atmosphere at its upper end, whereby the area defined by said sleeve will be relieved of pressure present between inner and outer bladders, to-thereby eliminate a diflerential uplift pressure othcrwise present.

9. A pressure helmet comprising a highly resilient inner bladder for closely engaging wearers head and having face, ear and neck openings formed to closely engage the wearer around his face, ears and neck, an outer bladder having a face opening seal and a neck opening seal, a restricting cover for said outer bladder, a flexible tubular sleeve having a cross-sectional area substantially equal to the neck area of said inner bladder when in use, the lower end of said sleeve being secured in airtight engagement with said inner bladder in general vertical alignment with its neck opening, releasable fastening means for securing the upper end of said sleeve in airtight engagement with said outer bladder and to said restrictive casing, the upper end of said sleeve being in communication with the atmosphere at its upper end, whereby the area defined by said sleeve will be relieved of pressure present between inner and outer bladders, to thereby eliminate a differential uplift pressure otherwise present.

10. A pressure helmet comprising a highly resilient inner bladder for closely engaging wearers head and having face, ear and neck openings formed to closelyengage the wearer around his face, ears and neck, an outer bladder having a face opening seal and a neck opening seal, a restricting cover for said outer bladder,,a flexible tubular sleeve having a cross-sectional area substantially equal to the neck area of said inner bladder when in use, the lower end of said sleeve being secured in airtight engagement with said inner bladder in general vertical alignment with its neck opening, said inner bladder and restrictive casing having registering top openings in general vertical alignment with their neck openings, releasable fastening means securing the upper end of said sleeve in airtight engagement with said outer bladder and to said restrictive casing, said fastening means comprising a relatively rigid inner flange attached to the upper end of said sleeve, a relatively rigid cooperating flange attached to said outer bladder peripherally of its top opening and means for urging said flanges together to clamp said sleeve to said outer bladder in air-sealing relationship,

whereby the area defined by said sleeve will be relieved of pressure present between inner and outer bladders, to

thereby eliminate a difierential upliftpressure otherwise present. 1

11. A fiuid-tig'hthelmet comprising a flexible hood adapted to enclose the head and adjacent neck portion of the .wearer, said hood having an outer relatively nonelastic fabric casing and a thin rubber latex inner lining, said lining being attached to said casing along a peripheral zone disposed around the face portion of the hood and] I having a peripherally continuous neck portion unattached H toith'ecasing, 'said casing being provided with a slit open- 1 ing' extending from the upper part thereof downwardly through the neck at the rear and having fastening means with size adjusting means comprising lacing extending on respectively opposite sides thereof rearwardly and down- I I wardly along the rear half of the neck portion on opposite 7 sides of said slit opening.

12. A fluid-tight helmet comprising a flexible hood adapted to enclose the head and adjacent neck portion of the wearer and having a face opening in the front 7 thereof, said hood having an outer cover composed of relatively non-elastic material and an elastic inner layer provided with a neck encircling portion, a relatively rigid frame secured to the marginal edge of the outer cover of said hood and a contiguous portion of said inner lining around said face opening, said inner lining extending inwardly of said frame and presenting a continuous peri-.

pheral flap providing a flexible seal for airtight engage:

' ment with a face panel, a resilient pad supported against the inner face of said frame and'disposed for snug engagement by the forehead of the user, and a grid-like cushion disposed within said elastic inner layer and comprising a median strip extending r'earwardly from adjacent said forehead pad to the rear of said helmet, a transversely extending strip at said rearfor engagement by the rear of the Wearers head and a transversely extending strip intermediate said forehead and rear strips.

13. A fluid-tight helmet comprising a flexible hood adapted to enclose the head and adjacent neck portion of V the'wearer and having a face opening in the front thereof,

said hood having an outer cover composed of relatively non-elastic material and an elastic inner layer provided with a neck encircling portion, a relatively rigid frame secured to the marginal edge of the outer cover of. said hood and a contiguous portion of said inner lining around said face opening, said inner lining extending inwardly of said frame and presenting a continuous peripheral flap providing a flexible-seal for airtight engagement with a face panel, said face frame being provided on its inner face with padding disposed to engage the forehead of the wearer, a grid-like cushion disposed within said elastic inner layer and comprising strip-like portions which tofor closing the opening, and said casing being provided gether with said forehead padding are disposed to gene, I erally encompass the cranium of a wearer, said grid-likeji; cushion being provided a skeleton supporting frame, pivotally securedto said face frame and including arms";v extending downwardly in the region of the wearers ears,

and earphone brackets adjust-ably mounted on the lower ends of said arms for supporting earphones in the deslred position,

. 14. A helmet of the character described comprising .a

relatively non-elastic flexible cover having a face panel opening, an elastic inner layer provided with a neck sealing portion and a face. panel sealing flap deflninga face opening, a relatively rigid frameasecured to said cover and elastic inner layer around said face opening; crash padding interiorly of said elastic inner layer and disposed generally to cushion the cranium of a wearer against shock, a relatively rigid outer shell encasing said flexiblecover rearwardly of said frame and downwardlyto the jaw region,

gagement, releasable fastening means provided jointly by said two shell parts and said frame for securing said shell parts to said frame and a locking channel for securing said two shell parts together. ,7

15. In combination with a pressure helmet having an inner sealing bladder and an enclosure therefor, hold.- down harness comprising anchor brackets secured to said enclosure on respectively oppositely disposed sides thereof at limited areas located on a horizontal axis passing substantially through the pivot point'of the wearers head, said harness providing two loops each extending downwardly from the oppositely disposed attachmentareas of said casing,said loops being of sufficient length to movably pass through pairs of spaced apart anchor attachments on a body covering of the wearer, whereby one of said loops may be disposed on the front and one on the back of the wearers body.

References Cited in the file of this patent UNITED STATES PATENTS said outer shell comprising two parts 'having Y" complementary median'ribs adapted for interfitting en:

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