GB2414412A

GB2414412A - Dual bore gas supply pipe

Info

Publication number: GB2414412A
Application number: GB0412038A
Authority: GB
Inventors: Joseph Anthony Griffiths
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-05-28
Filing date: 2004-05-28
Publication date: 2005-11-30
Also published as: GB0412038D0

Abstract

A gas supply pipe 10 connectable to a facemask 2 for use by aircrew, comprising an outer hose 11 and an inner hose 20 disposed within the bore of said outer hose 11. The outer and inner hoses 11, 20 are operable to separately supply breathable gas to different parts of a facemask 2, respectively. One of the gas supplies can be used to demist the visor 3 of a facemask 2. The outer hose 11 may be surrounded by a reinforcing means 12, the reinforcing means 12 may comprise a helical rib around the outer surface of the hose 11.

Description

-1- 2414412 Dual Bore Gas Supply Tube

Description

'thus invention relates to a gas supply tube for use with breathing masks used by pilots who are subjected to high G-forces.

Breathing equipment for aircrew nonnally comprises a flexible facemask having an inspratory valve supplied with oxygen or some other breathable gas, and an expiratory valve to allow the pilot to expel air from the facemask on exhalation. The breathable gas Is supplied to the mask through a supply hose from a breathing gas regulator connected to a source of pressured breathable gas, and the gas can either be supplied under a constant pressure, or the breathing gas regulator can be responsive to the G-forces that it Is subjected to. In other words, wl1en the G-force mcreascs, the pressure of the gas supplied to the mask Is correspondmly increased.

It Is known In the art for the facemask to be made of a flexible oronasal mask attached to a rigid shell, and to Include a transparent visor attached to the shell and extending therefrom m front of the weater's eyes. Such a facemask Is disclosed In our earlier UI: l'atent application no. GB 0401G50.4. The visor is used in conjunction with helmet-mounted clectro-optcal sighting and mformaton devices such as, for example, night vision goggles (NVGs). '[these devices project their images onto the surface of the visor located in front of the wearer's eyes. The act of flying a modern fighter aircraft can be strenuous and so when the device is m use by a fighter pilot, there Is the possibility that the heat generated by the pilots face could cause the mask to mist up, which is obviously detrimental to the plot's ability to see through the visor and is thereby dangerous. This problem Is particularly prevalent m certain versions of such facemasks that arc adapted to include a protective rubber hood (known as an 'N13C hood' - 'Nuclear - Biological - (chemical' protection) which can be attached to the top and stiles of the visor as well as the periphery cuff the rigid shell to enclose the wearer's head. It Is therefore known m the art to provide the facemask with a ventilation hose which supplies a flow of air to the mode face of the visor to ensure it Is kept mst-free. The air is typically supplied - 2 through this vcntllanon hose from an alr-pump or 'blower' which IS typically scatmountcd or cockpit-mounted, and which takes air from the plane's cabin.

Both the supply hose and the ventilation hose are acquired to have smooth bores so that there is minimal resistance to the supply of gas thercthrough, as undulations or ridges on the msldc surface of the pipe cause disruption to the air flow which IS detrimental to the performance of the mask. However, the hoses arc also rcqured to be crush-rests/ant so that the supply of gas to the pilot's mask cannot be stopped by a kink in the plpC or by it being squashed. The hoses are also required to be non 9 extendable, or at least to not extend beyond a prc-dctermlncd limit.

It will be appreciated from the above that facemask systems In modern fighter planes can include two separate gas hoses, namely the supply hose and the vcntlanon hose. These hoses arc connected from the facemask to an attachment point where they arc held against the plot's chest. (Indcr normal flymg conclitlons, the two separate hoses rcstrct movement of the pilot's head which has been tolerated in conventional aircraft. l-Iowever, modern fighter aircraft are now capable of gencratng forces of up to 9C, during a manocuvre, and under such conditions, the force exerted by the two hoses on the facemask becomes much more prominent and places a very undesrablc restriction on the ability of the pilot to move his head.

It is therefore an object of the present invention to provide gas supply hose that substantially alleviates or overcomes the problems mentioned above.

According to the prescot Invention, therefore, there IS provided a gas supply pipe connectable to a facomask for use by aircrew, comprising an outer hose and an mncr hose disposed within the bore of said outer hose, the outer and inocr hoses being operable to separately supply breathable gas to dlffercot parts of a facemask, respectively.

In a preferred embodiment, reinforcing means surround the outer hose to prevent the outer hose from being crushed. The relnforcmg means preferably comprises a - 3 rb attached to and extending In a helical path around the outer surface of said outer hose. The helical rib may be made of PVC or UPVC.

l'referably, the Inner hose Is longer than the outer hose through which it extends such that the Inner hose follows a curved or snake-lke path through the outer hose.

In a preferred embodiment, the outer hose is covered with an outer sleeve and the outer sleeve is preferably made from a webbing of woven timbres and is inextensible beyond a predetermined length. Conveniently, the predetermined limit of extension of said webblog sleeve Is determined by the angle of weave of the fores. I'referably, the webbing sleeve is made of aramld fibres.

The outer and Inner hoses preferably have smooth bores.

Conveniently, the outer hose is made of polyurethane, and the inner hose Is preferably made of a high performance elastomeric material, such as a rubber matctlal.

A preferred embodiment further Incorporates a flow separation means at at least one end of the pipe, operable to separate the flow of gas within the inner hose from the flow of gas outside the Inner hose and within the outer hose.

I'referred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure I shows a pilot wearing a mask and visor with separate breathing gas supply and ventilation hoses as known In the art; Figure 2 shows a pilot wearing a mask and visor with the combined pipe of the present invention; 3u Figure 3 Is cut-away view of the pipe of the present nvcnton; Figure 4 Is a cross-sectional view of the pipe m Figure 1; Figure 5 Is a cross- sectonal view of the pipe of Figures I and 2 when bent; and Figure 6 is a cut-away view of the pipe of the mventon In combination with a flow separator.

Referring now to linguae 1, a pilot 1 Is shown wearing a facemask 2 and visor 3 as s known In the art. lihe periphery of the facemask 2 and visor 3 Is attached to an NBC hood 4 as described above, which covers the Cloths head and seals around his neck. The pilot 1 Is wearing a helmet 5 over the hood 4 and facemask 2/vsor 3 apparatus. It can be seen that two separate hoses are provided to supply gas to the facemask: a first supply hose [-I1 to supply breathable gas Sit from a pressured source via a breathing gas regulator (not shown) to an oro-nasal mask within the facemask 2; and a second ventilation hose H2 to supply air Sv pumped from a cockpit of a plane to inside the NBC hood 4 and visor 3 to ensure that the visor 3 does not mist up. It can be seen that the two hoses H1, H2 pass through a supply manifold 6 located on the pilot's chest. l'hls manifold 6 enables the supplies Su, Sv s of gas to be switched If need be. For example, If the source of pressurlsed breathable gas Sit ran out, the manifold 6 could be switched so that the air Sv pumped from the cockpit of the plane Is also supplied to the Inside of the oro-nasal mask for the pilot to breathe. Conversely, If the pumping unit that supplies the ventilation gas Sv failed, the manifold 6 could be switched to re- drect the pressurised breathable gas Sit to the NBC hood 4 and visor 3 as well as the oro-nasal mask, to ensure that the visor 3 remains mist-free. The two hoses Hi, H2 present the problems mentioned above with regards to restriction of the pilot's head movement, and these problems become significantly more pronounced during hgh- G manoeuvres.

lto overcome these problems, a dual-bore pipe 10 is provided and is shown in f;gures 2 - 6. l'lgure 2 shows the plpC TO being used by a pilot 1 In conjunction with the facemask 2 and visor 3, and an NBC hood 4 and helmet 5 as described above. Figure 3 shows a cutaway view of the pipe 10 and legumes 4 and 5 show cross-sectonal views of the pipe 10.

The pipe 10 of the mveoton comprises a first outer hose 11 and a second Inner hose 20 of a smaller diameter than the first hose l l, disposed within the bore of the - 5 first hose 11. A reinforcing means 12 Is attached to and surrounds the outside 11b of the first hose, and comprises a hard plastic helical rib spralled around the first hose I I. 'lhc helical rib I 1 allows the first hose I I to bend (see Figure 5), but prevents it from kinking during such bending as non-renforced hoses would, and also prevents it from being crushed If subjected to a sideways forces Fir (see}'igure 5). The inside surface 11a of the first hose 11 is smooth to avoid causing turbulence In the flow of gas therethrough. The reinforcement means 12 therefore also protects the second hose 20 within the first hose 11 from being crushed and thereby restricting the flow of gas therethrough.

The second hose 20 has a smooth inner surface 20a to avoid causing turbulence In gas flowing therethrough, and also has a smooth outer surface 20b so that it does not cause turbulence In the gas flowing through the first hose 11. The second hose follows a snake-lke or curved path within the first hose 11 so that a length of second hose L2 within any given length Lo of first hose 11 Is greater than said length Lo of first hose 11 (see figure 4). 'thus ensures that the second hose 20 is never cver-stretched If the first hose 11 Is bent.

The first hose 11 Is covered with a webbing sleeve 30 made from woven fibres. This sleeve 30 can be stretched from a normal un-tensioned state to a fully extended state. However, the sleeve 30 cannot be extended beyond the fully extended state and the sleeve 30 Is therefore operable to prevent the first hose 11 from being stretched beyond said fully extended state. The degree to which the sleeve 30 can extend until it reaches the fully extended state Is dependent upon the weave angle of the fibres making up the sleeve 30, and so a specific weave angle can be chosen to provide a predetermined maximum extension length. Therefore, the fibres comprising the sleeve 30 do not extend themselves, but rather they move relative to one another withy the weave pattern until they reach the predetermined maximum extension length.

In order to separately supply gas from the first and second hoses 11, 20 to different locations, a flow separator 40 can connected to the pipe 10 of the present Invention at a delivery end 1Oa adjacent to the facemask 2 remote from the gas supply source

- G

(see Figure (a). This separator 40 can comprise an outer collar 41 attachable to the top of the first hose 11, and an mner tube 42 supported by arms 43 wthm the outer collar 41, said tube 42 bemg connectable to the top of the second hose 20. The inner tube 42 turns at 90" after the point at which it is connected to the second hose 20 and it extends outside the outer collar 41 so that the gas from the second hose 20 withy the inner tube 42 can be supplied separately to the gas from the first hose 11 whom the outer collar 41. For example, a pressunsed breathable gas supply SO can be connected to the first hose 11, and a pumped visor ventilation supply Sv can be supplied to the second hose 20. A corresponding flow separator 40 could be used at 0 the other end of the pipe 10 from the delivery end 10a m order to direct the two separate gas supplies So, Sv into the first and second hoses 11, 20 respectively.

It will be appreciated from the above description that the hose 10 of the present invention enables two separate gas supplies to be delivered to different parts of a ptlot's facemask, whilst presenting significantly less restriction to the movement of the plot's head than conventional twohose systems. To keep the pilot's head as unrestrained as possible by the pipe 10, especially under hgh-C; conditions, the materials from which the pipe 10 is made should be as light as possible.

Consequently, the first outer hose 11 is preferably made from polyurethane, and the second inner hose is made from rubber, although any suitable strong and lightweight material can be used.

The fibres from which the woven webbing sleeve 30 Is made are preferably aramid fibres. These have the benefit of being fire-retardant, lightweight and high-strength. - 7

Claims

Claims 1. A gas supply pipe connectable to a facemask for use by aircrew,

comprsmg an outer hose and an inner hose disposed wham the bore of said outer hose, the outer and inner hoses being operable to separately supply breathable gas to different parts of a facemask, respectively.
2. A gas supply pipe according to claim 1, comprsmg remforcmg means surrounding the outer hose to prevent the outer hose from bemg crushed.
3. A gas supply pipe according to claim 2 wherein the retnforcmg means comprises a rib attached to and extending m a helical path around the outer surface of said outer hose.
4. A gas supply pipe according to claim 3 wherein the helical rib Is made of I,VC or U1'VC.
5. A gas supply pipe according to any preceding claim wherein the mner hose is longer than the cuter hose through which it extends such that the mner hose follows a curved or snake-lke path through the outer hose.
6. A gas supply pipe according to any preceding claim wherein the outer hose Is coveted with an outer sleeve.
7. A gas supply pipe according to claim 6 wherem the outer sleeve Is made from a webbing of woven fables and Is mextenstble beyond a predctermmed length.
8. A gas supply pipe according to claim 7 wherein the predetermined limit of cxtenson of said webblog sleeve Is determined by the angle of weave of the fibres.
). A gas supply pipe according to claim 7 or claim 8 wherem the webbing sleeve Is made of armed fbres. - 8
10. A gas supply pipe according to any preceding claim wherein the outer and miter hoses have smooth bores.
11. A gas supply pipe according to any preceding claim wherem the outer hose is is made of polyurethane.
12. A gas supply pipe according to any preceding claim wherem the miter hose Is made of rubber.

0
13. A gas supply pipe according to any preceding claim further mcorporatng a flow separation means at at least one end operable to separate the flow of gas wlthm the inner hose from the flow of gas outside the Inner hose and withy the outer hose.