Abstract:
A swim and skin-dive snorkel is presented which uniquely provides positive end-expiratory pressure for pressure-balanced exhalation. The inventions include both devices and methods for providing positive end-expiratory pressure to the respiratory passages of a user of underwater breathing equipment. The inventive snorkel includes inhalation and exhalation conduits. Air can be exhaled by a user into a chamber from which exhaled air is released when exhalation pressure within the chamber exceeds a threshold pressure. In this manner the device provides positive end-expiratory pressure during exhalation. In an embodiment of the invention, upon receiving adequate exhalation pressure from the swimmer&#39;s airways, a sealing member is outwardly displaced against the ambient water pressure, thereby opening the exhalation conduit to receive exhaled air. The pressure maintained within the snorkel is adequate to keep the inhalation valve closed, except when the swimmer is actively inhaling. Furthermore, the pressure which must be overcome to achieve exhalation is balanced against the otherwise-compressive forces of the ambient water pressure acting against the user&#39;s chest and lungs, thereby greatly reducing the resting expiratory flow rate, the minute respiratory rate, and therefore the overall work of breathing. This exhalation pressure is linearly matched to the ambient water pressure as a function of dive depth, thereby also discouraging exhalation while diving. A purge valve may also be placed at the lower aspect of the snorkel covering rapid purge channels in the rigid sealing disk. This purge valve is designed to require a somewhat greater opening pressure than is required to open the exhalation valve, thereby preferentially directing exhaled air up the exhalation conduit, rather than into ambient water.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS AND PRIORITY CLAIM  
       [0001]    This application claims the benefit of the following provisional patent application: U.S. Provisional Application No. 60/385,327, filed Jun. 3, 2002. This provisional patent application and its disclosures and drawings are incorporated by reference herein. 
     
    
     
       FIELD OF THE INVENTIONS  
         [0002]    The present inventions relate to devices for underwater breathing equipment (including snorkels, scuba regulators, and snuba equipment) and to related methods, in particular to devices and methods intended to increase performance, enhance comfort and/or improve breathing while immersed or submersed in water.  
         BACKGROUND AND INTRODUCTION  
         [0003]    The basic snorkel, which facilitates breathing atmospheric air while the face is submersed in a body of water, has been present for centuries of time. In a common and simple form, the snorkel includes a breathing conduit. The breathing conduit typically has a mouthpiece connected to one end of the conduit. The other end of the conduit is positioned in the air above the water and the user&#39;s head to allow inhalation of air while the user&#39;s face or mouth is underwater.  
           [0004]    The basic snorkel has been improved, enhanced and built upon over the years. Many designs, structures and modifications to snorkels have been created to improve or enhance the experience of the user while swimming and/or diving. Some of the more relevant patents and published patent applications include:  
                                             U.S. PATENTS                                    3,860,0421/1975   Green           3,993,06011/1976   Mitchell           4,066,0771/1978   Shamlian           4,071,0241/1978   Blanc           4,278,0807/1981   Schuch           4,344,4278/1982   Marvin           4,610,2469/1986   Delphia           4,655,2124/1987   Delphia           4,708,13511/1987   Arkema           4,782,83011/1988   Forman           4,793,34112/1988   Arasmith           4,805,6102/1989   Hunt           4,832,0135/1989   Hartdorn           4,834,0845/1989   Walsh           4,884,56412/1989   Lamont           4,896,6641/1990   Harayama           4,860,7398/1989   Vandepol           4,862,9039/1989   Campbell           4,872,45310/1989   Christianson           4,877,02210/1989   Christianson           4,878,49111/1989   McGilvray, III           4,879,99511/1989   Christianson           5,101,8184/1992   Chace, et al           5,117,8176/1992   Lin           5,143,0599/1992   Delphia           5,199,4224/1993   Rasocha           5,239,9908/1993   Delphia           5,261,39611/1993   Faulconer et al           5,265,59111/1993   Ferguson           5,267,55612/1993   Feng           5,280,7851/1994   Fujima           5,297,5453/1994   Infante           5,327,8497/1994   Miller           5,357,65410/1994   Hsing-Chi           5,404,8724/1995   Choi           5,487,3791/1996   Koshiishi           5,529,0576/1996   Ferrero et al           5,606,9673/1997   Wang           5,622,1654/1997   Huang           5,638,8116/1997   David           5,657,7468/1997   Christianson           5,664,5589/1997   Wagner           5,671,7289/1997   Winefordner et al           5,697,36212/1997   Albrecht           5,865,1692/1999   Lan et al           5,868,1292/1999   Christianson           5,893,3624/1999   Evans           5,924,4167/1999   Miller           5,937,8508/1999   Kawashima et al           5,947,1169/1999   Gamow et al           5,960,79110/1999   Winefordner et al           6,119,6859/2000   Kawashima et al           6,129,08110/2000   Wu           6,202,644 B1  3/2001   Takeuchi et al           6,276,362 B1  8/2001   Chen-Lieh           6,302,102 B1  10/2001   Giroux et al           6,318,363 B1  11/2001   Monnich           6,352,075 B1  3/2002   Wang           6,363,929 B1  4/2002   Winefordner et al           6,371,108 B1  4/2002   Christianson           6,401,711 B1  6/2002   Tibbs et al           6,435,178 B1  8/2002   Lin           6,478,024 B1  11/2002   White, Jr           2002/0088460 A1   7/2002  Monnich           2002/0170558 A1   11/2002  Vinokur et al           2003/0029448 A1   2/2003  Swetish           2003/0037783 A1   2/2003  Feng                      
 
           [0005]    As is evident from the above patents, numerous problems have been addressed by various snorkel designs. However, to the best of this inventor&#39;s knowledge, no attention has been given to the physiologic impact of the compressive forces of ambient water on the respiration, specifically in exhalation, of the user of a surface-breathing, or near-surface breathing, snorkel.  
           [0006]    Scuba regulators, scuba equipment, snuba tubes and other snuba equipment are well known to persons of ordinary skill in the art. Embodiments of my invention can be adapted for use with the foregoing as well as new innovations in these areas.  
           [0007]    Several devices in the related field of “snuba” have confirmed that pressure-assistance is necessary to facilitate inhalation at the modest depths achieved with snuba. But once again, to the best of this inventor&#39;s knowledge, no attention has been given to the expiratory flow rate at such depths. Even scuba regulators, which facilitate inhalation at much greater depths, have not, to the best of this inventor&#39;s knowledge, specifically addressed the greatly increased expiratory flow rates that naturally occur at these even greater depths.  
           [0008]    In the case of the snorkel the user is typically in either a state of immersion (meaning that the body is within the water, while the airways communicate at atmospheric pressure) or in a state of submersion (meaning that both the body and the airways are exposed to ambient water pressure). From a practical standpoint for a snorkel user, most respiration necessarily occurs while surface swimming in the state of immersion. In this state, the conventional snorkel exchanges air at atmospheric pressure with the lungs, which lungs are acted upon by the greater compressive pressures of ambient water. Hence, compared to being completely out of the water, a greater effort is required to expand the lungs in inspiration and a lesser effort is required for exhalation, i.e., the expiratory flow rate is faster than the inhalation flow rate. Inasmuch as inhalation occupies only a small temporal component of the complete respiratory cycle, this faster exhalation component also results in a substantially shorter respiratory cycle and more inhalations per minute. In addition, as the user is exposed to the compressive effects of the ambient water pressure, during inhalation, a greater work of breathing is incurred and, over time, his or her inspiratory muscles progressively fatigue, resulting in smaller functional lung capacity, a relatively greater adverse contribution of the snorkel and bronchial dead spaces with each breath, and the possibility of atelectasis (collapse of the alveolar/gas exchange sacs).  
           [0009]    Embodiments of the snorkel presented herein can serve to substantially reduce the overall work of breathing by balancing the expiratory forces, slowing the respiratory cycle, reducing the repetitive work of inhalation against compressive ambient water pressures, and/or minimizing the risk of developing atelectasis.  
           [0010]    Furthermore, several other benefits may be realized by embodiments of my invention. By increasing the pressure within the snorkel&#39;s main (inhalation) tube, the inhalation valve at the top end of tube can be maintained in a closed position, except during active inhalation, thereby significantly reducing the internal exposure to splash water, and even reducing the internal exposure to flood water upon submersion; however, the inhalation valve does not absolutely close while submersed, beneficially allowing the user to voluntarily draw on a small amount of residual air. The pressure amounts to positive end-expiratory pressure (“PEEP”) which may result in physiologic benefit to some users, particularly those with obstructive lung diseases, such as asthma and emphysema.  
           [0011]    Many aspects of human physiology become involved here, but in a simplistic overview, PEEP slows respiratory rate and tends to increase functional lung volumes, but also tends to slow venous blood return to the heart. In the water, however, venous blood return to the heart is already greatly improved simply by the compressive forces of ambient water. A slowed respiratory rate is preferred as each inhalation must displace water, significantly increasing the work of breathing, inspiratory muscle fatigue, and the associated anxiety that accompanies many skin divers. Furthermore, the increase in lung volume, time-averaged over the complete respiratory cycle, enhances the buoyancy of the user.  
         OBJECTS OF THE INVENTIONS  
         [0012]    It is an object of the present inventions to provide devices that effect an improved balance between the intrinsic airway pressures of physiologic exhalation and the competing extrinsic pressures of ambient water acting on the chest wall. Embodiments of these inventions can be incorporated in or used in conjunction with underwater breathing equipment such as snorkels, scuba regulators and snuba equipment.  
           [0013]    It is a further object of the present inventions to provide devices that minimize the re-breathing of exhaled air. Unidirectional air flowing into the snorkel via one conduit and exiting the snorkel via a separate conduit can be employed for this purpose. Unique to the present invention is the use of ambient water pressure and/or other counter pressure to maintain a pressure and to retain exhaled air until the airway exhalation forces are adequate to overcome the compressive forces of ambient water pressure on the user.  
           [0014]    It is yet another object of the present inventions to provide snorkel devices that maintain internal dryness while swimming in turbulent water and while diving. Splash water is blocked from entering the snorkel, except during inhalation; and any water that accumulates in the purge reservoir is purged from the snorkel during normal, relaxed exhalation, even before any exhaled air is positioned to leave the snorkel.  
           [0015]    Through embodiments of my invention many tangible benefits are provided to the user including a reduction in resting respiratory rate with a resultant reduction in the work of breathing, reduction in anxiety, improvement in the sense of safety and well-being, longer dive times, and a drier snorkel.  
           [0016]    It is also another object of certain embodiments of my invention to similarly balance the exhalation rate of the underwater scuba diver by attaching a device patterned after the exhalation valve of this snorkel to the exhalation port of the scuba regulator to similarly regulate the natural exhalation rate of the scuba diver or snuba diver.  
           [0017]    These objects and other objects, purposes and advantages of my invention are apparent from the descriptions and drawings herein. My inventions are not limited to or by these objects and not every embodiment of my invention necessarily incorporates or provides every such object, purpose or advantage.  
         SUMMARY  
         [0018]    This summary provides a general description of different aspects of my invention, including certain embodiments or elements of my invention. This summary is not intended to limit the scope of my invention, nor is there any implication that my invention requires all of the described or identified aspects or elements. Various options and alternatives are described and are not intended to limit the scope of my invention or claims.  
           [0019]    The invention provides positive end-expiratory pressure to the respiratory passages of a user of underwater breathing equipment. The underwater breathing equipment can be, for example, a snorkel, a scuba regulator or snuba equipment. My invention can be adapted for use with, or to be incorporate in, these and similar underwater breathing equipment.  
           [0020]    The invention includes a chamber into which air is exhaled by the user and a means for releasing the exhaled air from the chamber and away from the user when exhalation pressure within the chamber exceeds a counter pressure exerted on the exhalation pressure. The chamber can be any conduit, vessel, container or other space where exhaled air can be received and contained, at least temporarily. An exhalation pressure within the chamber is created, i.e., exhalation pressure is the pressure in the chamber into which the air is exhaled. This inventive device can provide positive end-expiratory pressure to the respiratory passages of the user during exhalation.  
           [0021]    The means for releasing the exhaled air can include a valve adapted to open when the exhalation pressure exceeds the counter pressure. The valve can be any valve, nozzle or other device for regulating or controlling the release of exhaled air from the chamber. This valve may include a pressure member against which the counter pressure acts; whereby exhaled air is released from the chamber when the exhalation pressure acting against the pressure member exceeds the counter pressure. The counter pressure is (or defines) the resistance which the exhalation pressure must overcome in order to provide or allow a release of exhaled air from the chamber.  
           [0022]    The counter pressure can be a pressure (predetermined or not) created or dictated by mechanical means, such as a spring, a biased structure, or other physical structure adapted to provide the resistance which the exhalation pressure must overcome for a release of exhaled air from the chamber. Although not preferred, pneumatic, hydraulic or other forces or devices for applying or creating this counter pressure against the exhalation pressure can be used. Most preferably the counter pressure is created or provided in whole or in part by ambient water pressure. Ambient water pressure can act directly or indirectly against a pressure member to provide a counter pressure against the exhalation pressure in the chamber. The pressure member can be a disk, plate, ring, or other physical structure exposed directly or indirectly to the ambient water pressure and/or other counter pressure. The pressure member applies the counter pressure against the exhalation pressure in the chamber.  
           [0023]    In an alternative embodiment of this invention, the exhaled air is not released until the exhalation pressure in the chamber exceeds a threshold pressure. The threshold pressure may be pre-determined or may vary depending on conditions such as ambient water pressure. When the exhalation pressure in the chamber exceeds the threshold pressure, the exhaled air is released. Although not preferred, a sensor or other device can determine if or when the threshold pressure has been exceeded by the exhalation pressure, and when exceeded the exhaled air is released from the chamber.  
           [0024]    The release of exhaled air from the chamber can be prevented or inhibited until the counter pressure or threshold pressure is exceeded or overcome by the exhalation pressure. Although it is preferred that the release be prevented, the invention retains some of its advantages and benefits even if the release is just substantially inhibited, i.e., release of exhaled air from the chamber is substantially inhibited, but not totally prevented. This inhibited release may occur when the valve is in the form of a nozzle or other device that allows for a very limited release of exhaled air from the chamber when the exhalation pressure does not exceed or overcome the counter pressure or threshold pressure, but the inhibition is sufficient to provide additional pressure and PEEP.  
           [0025]    The invention may include a pressure system that provides additional pressure or the counter pressure. The pressure system may include the pressure member described above and further described below. The pressure system is the means by which the counter pressure is applied to the exhalation pressure in the conduit. It may also be the means by which a threshold pressure may be established.  
           [0026]    Preferably, the pressure member moves in response to a difference in pressure between the exhalation pressure in the chamber and the counter pressure. A counter pressure such as pressure from ambient water may act directly or indirectly on the pressure member.  
           [0027]    Preferably, a sealing member may be connected to or be part of the pressure member or may through other means be controlled by or responsive to the pressure member or movement of the pressure member. The sealing member acts to regulate the release of exhaled air from the chamber by closing or sealing an exit from the chamber. When the chamber is connected to an exhalation conduit (see description below), the sealing member can act to close or seal the entrance to the exhalation conduit when the exhalation pressure does not exceed the counter pressure or threshold pressure. When the counter pressure or threshold pressure is exceeded, the sealing member can open the entrance to the exhalation conduit allowing exhaled air to enter the exhalation conduit. The sealing member can be any shape suited for the closing or sealing purpose. Preferably, the sealing member is dome shaped or similarly shaped to provide for a gradual, rather than sudden, release of exhaled air until the sealing member is sufficiently separated from the exhalation conduit&#39;s entrance, thereby preventing or reducing vibration or buzz that would otherwise occur.  
           [0028]    My invention can be applied to snorkels. The snorkels of my invention can include (a) an inhalation conduit adapted to receive inhaled air upon inhalation by a user of the snorkel, and (b) an exhalation conduit adapted to receive exhaled air from the user and to direct the exhaled air under additional pressure out of the snorkel, and (c) a pressure system to apply the additional pressure. This can achieve PEEP for the user.  
           [0029]    Preferably the inhalation conduit has an inhalation valve (diaphragm, butterfly, umbrella, or otherwise). The inhalation valve is adapted to open to allow inhalation of air, but at other times is closed to maintain pressure within the snorkel. This inhalation valve and the associated inhalation conduit should be adequately sized to minimize inhalation resistance and the valve should close tightly during exhalation to maintain pressure within the snorkel and directional airflow through the snorkel.  
           [0030]    The snorkel may also have an exhalation valve which is adapted to be acted upon by a counter pressure to regulate the receipt of exhaled air by the exhalation conduit. The exhalation valve may be adapted to provide exhaled air into the exhalation conduit when the pressure of the exhaled air exceeds the counter pressure. Preferably this counter pressure is generated in whole or in part by ambient water pressure.  
           [0031]    The snorkel may include the pressure system or pressure member described above. The counter pressure acts against this pressure member to provide the additional pressure. Alternatively, the counter pressure can act as the pressure member to provide the additional pressure.  
           [0032]    Preferably, the exhalation conduit is within the inhalation conduit, but alternatively may be outside of or external to the inhalation conduit. The exhalation conduit preferably originates near the lower end of the snorkel, in sealing proximity to a sealing member of the exhalation valve.  
           [0033]    The inhalation and exhalation conduits are preferably tubes of plastic, rubber or other material. Plastics or other materials commercially used in snorkels can be used. The conduit may be any conduit, tube, passageway or other means of conveyance through which inhaled air or exhaled air can flow. Conventional tubes used for snorkels are generally suitable.  
           [0034]    A preferred exhalation valve useful in the practice of this invention includes the following:  
           [0035]    1. A sealing member, which facilitates a physical closure or seal against the release of exhaled air from the chamber. This closure or seal may be applied directly against the exhalation conduit or against some connection or intermediary between the chamber and exhalation conduit. For example, the seal may be applied to a mount to which the exhalation conduit is attached. This sealing member has a preferred dome shape which gradually increases the escape of the pressurized air within the snorkel at the opening pressure of the valve, thereby minimizing or eliminating the vibratory buzz that would otherwise be experienced. Alternative shapes for the sealing member include that of a teardrop, a cone, or similar shape such that elimination of the vibratory buzz is accomplished.  
           [0036]    2. A rigid support disk, which provides structural support to the softer sealing member and provides a rigid surface upon which ambient water pressure can act to generate a counter pressure.  
           [0037]    3. A convoluted membrane, which is generally annular in shape and serves to flexibly attach the rigid support disk/sealing member assembly to the rigid and stationary lower housing an example of which is described below. The convoluted cross-section of this membrane allows sufficient non-impeded axial travel of the sealing member such that the sealing member can both tightly seal against the exhalation conduit mount and can also move outwardly sufficient to non-obstructively open the valve at the mount.  
           [0038]    A purge valve is preferably included for purging water from the snorkel. The purge valve can be used with or can be incorporated into the exhalation valve apparatus. The purge valve provides for the purging of water from the snorkel. To accomplish this, an excessive exhalation pressure is required. For example, normal exhalation may result in an exhalation pressure that exceeds the counter pressure or threshold pressure, but is insufficient to exceed or overcome the pressure required for a purge. To purge, the user must exert an excessive exhalation pressure sufficient to exceed or overcome the pressure required for purging of water through the purge valve. In other words, the purge pressure is greater than the counter pressure such that the exhalation pressure required to purge water from the snorkel is greater than the exhalation pressure required to exceed the counter pressure for a release of exhaled air from the chamber into the exhalation conduit.  
           [0039]    A preferred purge valve includes:  
           [0040]    1. Rapid purge channels in the exhalation valve&#39;s rigid support disk.  
           [0041]    2. A purge membrane, which is materially contiguous with the exhalation valve&#39;s sealing member and which covers the underside of the rapid purge channels of the rigid support disk, thereby preventing ambient water entry into the snorkel. This purge membrane also has a molded bias for closure to remain closed at normal exhalation pressures, but to open with the greater pressures of rapid purging operations. To purge, the user must exert an excessive exhalation pressure sufficient to exceed or overcome the pressure required for purging of water through the rapid purge channels.  
           [0042]    3. Purge membrane ribs which orient radially and which provide circumferentially non-uniform pressure release across the Rapid Purge Channels, thereby minimizing the buzz or vibration that otherwise would be experienced  
           [0043]    In another exemplary embodiment of my invention, the exhalation valve apparatus and the purge valve are molded together into a single piece of flexible rubber or plastic, comprising a cylindrical wall shaped as an accordion, which allows compressible axial movement, and a circular diaphragm, which is molded to be contiguous with the cylindrical accordion wall that it closes. A central dome is molded into the upper surface of the circular diaphragm area, which serves as the sealing member of the exhalation valve. The outer folds on the cylindrical accordion wall have several small slits, which effectively function as small duck valves for rapid purging when the accordion wall is extended, as in higher pressure purge operations.  
           [0044]    Portions of the above described snorkel (e.g., exhalation valve) can be applied or adapted to a scuba regulator or snuba equipment (e.g., snuba tube), i.e., used in conjunction with the scuba regulator or snuba equipment. The user breathes air from the scuba regulator or snuba tube (inhalation), but exhalation of air by the user encounters a counter pressure to create PEEP in the respiratory system of the user. The exhaled air from the user enters a chamber and there is an exhalation pressure. A pressure system provides a counter pressure. The exhaled air is released from the chamber when the exhalation pressure exceeds the counter pressure (or a threshold pressure). The exhalation valve with sealing member and pressure member can be adapted and used for this purpose. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0045]    [0045]FIG. 1A is a front view of the assembled snorkel  
         [0046]    [0046]FIG. 1B is a front exploded view of the snorkel  
         [0047]    [0047]FIG. 2A is a top perspective view of the inhalation cap and the inhalation valve diaphragm member, which together form the inhalation valve.  
         [0048]    [0048]FIG. 2B is a transverse sectional view of the inhalation cap showing the inhalation valve in open position such as occurs during inhalation  
         [0049]    [0049]FIG. 2C is a transverse sectional view of the inhalation cap showing the inhalation valve in the closed position such as occurs during breath holding or exhalation  
         [0050]    [0050]FIG. 3A is a transverse sectional view of the main tube and its associated structures  
         [0051]    [0051]FIG. 3B shows the transverse sectional view of FIG. 3A with the exhalation tube coursing within the main tube and mounting to the main tube&#39;s exhalation tube upper mount  
         [0052]    [0052]FIG. 4A is a side view of the ribbed flexible connecting tube  
         [0053]    [0053]FIG. 4B is a sectional view of the connecting tube shown in FIG. 4A.  
         [0054]    [0054]FIG. 5A is an exploded side view of the junction with the mouthpiece, the exploded exhalation valve/purge valve assembly, and the purge cap.  
         [0055]    [0055]FIG. 5B is an exploded perspective view of the exhalation valve/purge valve assembly.  
         [0056]    [0056]FIG. 5C is an exploded transverse sectional view of the exhalation valve/purge valve assembly  
         [0057]    [0057]FIG. 5D shows the top view of this exhalation valve/purge valve assembly  
         [0058]    [0058]FIG. 5E shows a collapsed transverse sectional view of the exhalation valve/purge valve assembly  
         [0059]    [0059]FIG. 6A is a transverse sectional view of the junction with the exhalation valve in closed position.  
         [0060]    [0060]FIG. 6B is a transverse sectional view of the junction with the exhalation valve in open position as occurs in normal exhalation  
         [0061]    [0061]FIG. 6C is a sectional view of the junction with the rapid purge ports open as occurs during purging levels of exhalation  
         [0062]    [0062]FIG. 7A is a sectional view of an alternative exhalation valve/purge valve apparatus showing a compressible accordion-style wall. This wall has slits in the lower, outer accordion walls that are closed, unless the walls are fully distended as in a purge operation.  
         [0063]    [0063]FIG. 7B is a sectional view similar to FIG. 7A showing the exhalation valve in open position with the purge valve in the closed position.  
         [0064]    [0064]FIG. 7C is a sectional view similar to FIG. 7A showing both the exhalation valve and the purge valve open.  
         [0065]    [0065]FIG. 8 is another cross-sectional view of an alternative exhalation valve/purge valve apparatus showing a dome that travels vertically and an externally positioned exhalation tube.  
         [0066]    [0066]FIG. 9 is a transverse sectional view of the junction which houses the exhalation valve, as it is adapted to mount to a connecting tube, which in turn mounts to the exhalation vents or equivalent of a scuba regulator.  
     
    
     DETAILED DESCRIPTION  
       [0067]    To facilitate understanding of the flow through the snorkel, inhalation goes through an inhalation conduit  1  to the mouthpiece of the user, and exhalation goes from the mouthpiece to an exhalation conduit from which exhaled air exits the snorkel. The inhalation valve  3  includes all parts necessary to make a functioning valve; and the exhalation valve  4 , which is a complex structure, refers to the valvular action of these parts as they functionally come together. The Purge Valve  5  is also shares structures of the Exhalation Valve  4  and is best thought of as a functional aspect of the snorkel that allows rapid purging. Although these items are best thought of in terms of their function, rather than graphically on paper, the individual components of these various structures are supplied in the drawings.  
         [0068]    [0068]FIG. 1A shows the assembled snorkel in front view perspective. Several major structural elements are identified including the Inhalation Cap  7 , the Main Tube  13 , the Connecting Tube  19 , the Mouthpiece  54 , the Junction  22  which houses a Chamber  23  which communicates with the Inhalation Conduit  1 , the Exhalation Conduit  48 , and the Purge Reservoir  27 . At the lower end of the snorkel is the Purge Cap  50 . And near the upper end of the Main Tube  13  is the Exhalation Conduit Exit Port  16  where the exhaled air normally exits the snorkel.  
         [0069]    [0069]FIG. 1B shows an exploded front view of the major structural components of the entire snorkel with the Inhalation Cap  7 , the Inhalation Valve Diaphragm Member  10 , the Main Tube  13 , the Connecting Tube  19 , and the Junction  22 . The Combined Sealing Assembly  6  comprises the Combined Sealing Member  30 , the Rigid Support Disk  36 , and the Convoluted Membrane  40 , which serves to flexibly mount the active components of the Exhalation Valve  4  which is a functional component of the Combined Sealing Assembly acting against the Sealing Ring  47  of the Exhalation Tube Lower Mount  44 . The Exhalation Tube  48  mounts to the upper aspect of this structure as shown. The Exhalation Tube then courses up the central chambers of the snorkel until it mounts at its upper end by sandwiching between the Main Tube  13  and the hollow Exhalation Tube Mounting Plug  49 . The Exhalation Tube Lower Mount  44  is connected to the Junction  22  by a Supporting Structure  46  which on a top down view resembles spokes extending out to an outer rim. Therefore, this Supporting Structure  46  does not impede fluid/air movement across it, e.g., from top to bottom. The Purge Cap  50  screws onto the Junction  22  and thereby secures the Combined Sealing Assembly  6  where its Convoluted Membrane  40  attaches between these two structures. Importantly, the Junction  22  houses the Chamber  23  where exhalation pressure is maintained by the combination of the Inhalation Valve  1  and the Exhalation Valve  2 . The lower most portion of the Chamber  23  within the Junction  22  is referred to as the Purge Reservoir  27  as this is where splash/flood water would first accumulate.  
         [0070]    [0070]FIG. 2A shows the Inhalation Cap  7 , the Thru-Passages  8 , and the Inhalation Valve Diaphragm Member  10 , which taken together form the Inhalation Valve  3 . The Inhalation Valve Diaphragm Member  10  has an optional partial thickness Groove  12  across its diameter and is centrally anchored at its Central Hole  11  by the Inhalation Valve Anchor  9  that is shown in FIG. 2B and FIG. 2C.  
         [0071]    [0071]FIG. 2B shows a transverse sectional view of the Inhalation Cap  7  and the deformed shape of the Inhalation Valve Diaphragm Member  10 , representative of the valve in its open position as occurs during inhalation. All inhaled air passes through the Thru-Passages  8  of the Inhalation Cap  7  to enter the snorkel. Therefore the Inhalation Cap can be considered the first member of the Inhalation Conduit  1 . The Inhalation Valve Diaphragm Member  10  is very flexible and easily deforms to minimize any contribution to airway resistance in the Inhalation Conduit  1 . The optional partial thickness Groove  12  across its diameter allows this valve to function as a more efficient butterfly-style valve. Additionally, the Inhalation Cap  7  is sized such that the Thru-passages  8  combine in area to similarly minimize their contribution to airway resistance even at rapid inhalation flow rates. The Internal Threads  55  of the Inhalation Cap  7  are shown and mate with corresponding threads on the Main Tube  13  as described in FIG. 3A.  
         [0072]    [0072]FIG. 2C is similar to FIG. 2B, but shows the Inhalation Valve Diaphragm Member  10  in its flattened shape as occurs while not inhaling. The Inhalation Valve Diaphragm Member  10  naturally, but gently, assumes this flat shape when no pressure gradient exists across the valve in order to minimize the closing sounds that would be experienced if the valve did not flatten until forcefully closed. Then, as exhalation occurs, the valve remains tightly closed as the pressure acting on the Exhalation Valve  4  (described in FIGS. 6A, 6B, and  6 C) at the bottom of the snorkel propagates within the snorkel to provide the closing pressure for this Inhalation Valve  3 . As long as the snorkel is generally oriented in the normal use position (i.e., with the Inhalation Valve  3  higher than the Exhalation Valve  4 ), and the user is not actively inhaling, this pressure will be adequate to prevent water from entering the snorkel via the Inhalation Cap  7 .  
         [0073]    [0073]FIG. 3A shows a transverse sectional view of the Main Tube  13  and its related structures. The Inhalation Cap  7  mounts to the top end of the Main Tube  13  with a mating set of Internal Threads  55  and External Threads  56  on their respective components. The represented structures of the Inhalation Valve  3  are as described above for FIG. 2B and FIG. 2C. The Main Tube&#39;s Central Channel  14  directly receives inhaled air from the Inhalation Valve  3  and therefore becomes the second functional member of the Inhalation Conduit  1 , wherein the Inhalation Conduit  1  is defined to be the network of tubes and other hollow structures through which inhaled air sequentially passes. The Exhalation Tube Upper Mount  15  is integral with the Main Tube  13  and provides a circular outer wall against which the upper end of the Exhalation Tube  48  is sandwiched by the hollow Exhalation Tube Mounting Plug  49 . This design effectively eliminates a potential air leak between the Exhalation Conduit  48  and the Inhalation Conduit  1  of the snorkel that could otherwise be problematic as the Exhalation Conduit  48  passes through this wall of the Inhalation Conduit  1 . The Exhalation Conduit Exit Port  16  is an opening in the Inhalation Conduit  1  through which the Exhalation Conduit  48  exits the snorkel. The Main Tube  13  has an Ellipsoid Cross-Section  17  at its lower end to reduce hydrodynamic drag while swimming and it transitions to a Circular Cross-Section  18  at its upper end to allow the Inhalation Cap  7  to screw-mount. The lower end of the Main Tube  13  mounts to the flexible Connecting Tube  19  with the Ribs on Main Tube  57  mating with the Grooves in Connecting Tube  58 .  
         [0074]    [0074]FIG. 3B shows the Circular Cross-Section  18  of the upper end of the Main Tube  13 .  
         [0075]    [0075]FIG. 3C shows the Ellipsoid Cross-Section [ 17 ] of the lower end of the Main Tube [ 13 ].  
         [0076]    [0076]FIG. 3D is identical to FIG. 3A except that it also shows the Exhalation Tube  48  as it courses through the Main Tube  13 .  
         [0077]    [0077]FIG. 4A is a side view of the ribbed flexible Connecting Tube  19 . The Outer Ribs  21  provide radial support for the tube, while still allowing it to be flexible and bend. This bending provides improved comfort while the snorkel is being worn, particularly if other diving gear is also concurrently being used.  
         [0078]    [0078]FIG. 4B is a transverse sectional view of the ribbed flexible Connecting Tube  19  that is also described in FIG. 4A. Now shown is the Central Channel  20  of this tube, which is the third functional member of the Inhalation Conduit  1 . Further revealed herein are the Upper Grooves  58  of the Connecting Tube  19  that mate with corresponding Ribs  57  on the Main Tube  13  (shown in FIG. 3A) and the Lower Grooves  59  of the Connecting Tube  19  that mate with Ribs  60  on the Junction  22  (shown in FIG. 5A)  
         [0079]    [0079]FIG. 5A is an exploded side view of the Junction  22  and its related structures:  
         [0080]    Three mounts are integral to the Junction  22  including the Connecting Tube Mount  24  with its attachment Ribs  60 , the Mouthpiece Mount  25  with its attachment Ribs  61 , and the Purge Cap Mount  29  with its External Threads  64 .  
         [0081]    The Junction  22  houses a small volume Chamber  23 , which receives inhaled air from the Central Channel  20  of the Connecting Tube  19  (shown in FIG. 4B), thereby becoming the fourth functional member of the Inhalation Conduit  1 . In other embodiments, the chamber might not be a functional member of the inhalation conduit. This Chamber  23  receives exhaled air from the Mouthpiece  54 . This Chamber  23  is pressurized during exhalation and functionally provides the counter pressure to the user&#39;s airways. The lower region of the Chamber  23  is more specifically referred to as the Purge Reservoir  27 , as any captured water accumulates here first.  
         [0082]    Importantly, the Junction  22  also houses the functional Exhalation Valve  4  and Purge Valve  5 . In the preferred embodiment, these two valves share three structural elements which, taken together, are simply referred to as the Combined Sealing Assembly  6 . The structures of this assembly are depicted for the preferred embodiment in FIGS. 6A through 6C, while examples of alternative embodiments of the Exhalation Valve  4  and the Purge Valve  5  are shown separately in FIGS. 7 and 8.  
         [0083]    The Exhalation Tube Lower Mount  44  is statically attached, via its spoke and rim-like Supporting Structure  46 , to the Junction  22  at said junction&#39;s Snap Mount for Exhalation Tube Lower Mount  26  (which is shown in FIGS. 6A, 6B, and  6 C). The Exhalation Tube Lower Mount  44  additionally provides the Sealing Ring  47  for the Exhalation Valve  4 . Inasmuch as this Exhalation Tube Lower Mount  44  directs exhaled air from the Chamber  23  to the Exhalation Tube  48  (also referred to as exhalation conduit  48 ).  
         [0084]    The Exhalation Valve  4  is comprised of elements of the Combined Sealing Assembly  6  and the Sealing Ring  47 , which items are described in more detail in FIGS. 6A, 6B, and  6 C.  
         [0085]    [0085]FIG. 5A also shows the Purge Cap  50  which screws onto the Junction  22  at the corresponding mount. The Pure Cap  50  also is shown with the Purge Cap Perforations  52  which allow water pressure to act on the Exhalation Valve  4  and provides an exit for water that is purged across the Purge Valve  5 .  
         [0086]    [0086]FIG. 5B is an exploded perspective view of the Combined Sealing Assembly  6 . This assembly comprises the silicon rubber Combined Sealing Member  30 , the Rigid Support Disk  36 , and the flexible Convoluted Membrane  40 .  
         [0087]    The Combined Sealing Member  30 , which is a one-part structure, provides the Exhalation Valve Sealing Member  31  and the Purge Valve Sealing Member  32 . In the preferred embodiment, the Exhalation Valve Sealing Member  31  is dome-shaped in order to very gradually open exit flow and reduce vibration as exhaled air escapes across the Exhalation Valve  4  when just minimally open. Other shapes that could similarly result in dampening include teardrop or cone. The contiguous Purge Valve Sealing Member  32  notably has Dampening Ribs  33  that project out radially in various lengths from the underside of the Purge Valve Sealing Member  32  and serve to reduce or eliminate the buzz that would otherwise occur while purging. The Combined Sealing Member  30  also has an Attachment Groove  34  around its midsection that provides secure attachment to the Rigid Support Disk  36 . The Hollow Region  35  allows the Combined Sealing Member  30  to be compressed for assembly purposes, and provides a recess mount for an optional Spring  68  (FIG. 6A) that could further refine the exhalation Airway Pressure  65  if modification is desired in the future.  
         [0088]    The Rigid Support Disk  36  provides several functions: It supports the Combined Sealing Member  30  that allows the Exhalation Valve Sealing Member  31  to form a stable seal with the Sealing Ring  47  (shown in FIG. 6A, FIG. 6B, and FIG. 6C); it provides a broad surface against which the Ambient Water Pressure  66  (depicted in FIG. 6A, FIG. 6B, and FIG. 6C) acts to balance the desired exhalation Airway Pressure  65  (depicted in FIG. 6A, FIG. 6B, and FIG. 6C) within the snorkel; it supports the Purge Valve Sealing Member  32  to maintain proximity with the sealing surface of same disk; and it provides a smooth, rigid surface against which the Purge Valve Sealing Member  32  can seal. The Rapid Purge Channels  39  in the Rigid Support Disk  36  are closed by the Purge Valve Sealing Member  32 , except during active purging operations when Airway Pressure  65  reaches a sufficient threshold for them to open for very rapid purge, taking full advantage of the higher exhalation Airway Pressures  65  which are maintained within the snorkel. The Central Hole  37  in the Rigid Support Disk  36  supports the Combined Sealing Member  30  at said member&#39;s Attachment Groove  34 . The Outer Groove  38  of the Rigid Support Disk  36  provides mounting attachment to the Central Anchor  41  of the flexible Convoluted Membrane  40 .  
         [0089]    The Convoluted Membrane  40  is a flexible, annular structure that has transverse sectional convolutions to allow axial travel of the Rigid Support Disk  36  and the Combined Sealing Member  30 . This functionally allows the Exhalation Valve Sealing Member  31  to appropriately open and close its seal against the Sealing Ring  47  (shown in FIG. 6A, FIG. 6B, and FIG. 6C), thereby utilizing the Ambient Water Pressure  66  to modulate the user&#39;s immersed and submersed exhalation rates. The Convoluted Membrane  40  has a Central Anchor  41  for secure attachment to the Rigid Support Disk  36  and a Peripheral Anchor  42  for secure mounting in the space defined by the Convoluted Membrane Junction Groove  28  (of the Junction  22  described separately in FIG. 6A) and the corresponding Convoluted Membrane Purge Cap Groove  51  (of the Purge Cap  50  described separately in FIG. 6A). The screw mount of the Purge Cap  50  onto the Junction  22  slightly compresses this Peripheral Anchor  42 , which beneficially creates a seal to prevent water from entering the snorkel, and helps to lock the threads of the Purge Cap Mount  29 .  
         [0090]    [0090]FIG. 5C is a transverse sectional view of the parts shown in FIG. 5B.  
         [0091]    [0091]FIG. 5D is top view of the Combined Sealing Assembly  6  as comprised by the parts of FIG. 5B.  
         [0092]    [0092]FIG. 5E is a transverse sectional view of the Combined Sealing Assembly  6  as comprised by the parts of FIG. 5C.  
         [0093]    [0093]FIG. 6A is a transverse sectional view of the Junction  22  with the Exhalation Valve  4  in closed position. Numerous items identified in this figure are described in detail in FIG. 5A and FIG. 5B. Of note, the User&#39;s Airway Pressure  65 , which acts on the Combined Sealing Assembly  6  from above, is inadequate to overcome the inward compressing force that the Ambient Water Pressure  66  produces from below. Therefore, the Exhalation Valve Sealing Member  31  assumes tight closure against the Sealing Ring  47  and exhalation flow is prevented. The Convoluted Membrane  40  assumes a transverse sectional shape that is compatible with the Rigid Support Disk  36  being at its upper end of axial travel. Also shown is an the optional mechanical Spring  68  which could be used to further refine the counter pressure upon exhalation that is achieved.  
         [0094]    [0094]FIG. 6B is a transverse sectional view of the Junction  22  with the Exhalation Valve  4  in open position. This figure is very similar to that of FIG. 5C, except that FIG. 5D depicts the condition of normal exhalation in which the user&#39;s Airway Pressure  65  exceeds Ambient Water Pressure  66 , thereby exerting a net downward force on the Combined Sealing Assembly  6 , removing the Exhalation Valve Sealing Member  31  from its sealing position against the Sealing Ring  47 . Flow Arrows  67  depict the direction of airflow through the Chamber  23 , across the Exhalation Valve  4 , and into the Exhalation Tube  48 , from whence it is channeled to exit the snorkel. The Convoluted Membrane  40  assumes a transverse sectional shape that is compatible with the Rigid Support Disk  36  being near its lower end of axial travel.  
         [0095]    [0095]FIG. 6C is a transverse sectional view of the Junction  22  with the Purge Valve  5  in open position. Note that the Exhalation Valve  4  is also in open position, because the Airway Pressure  65  required for purging is excessive for normal exhalation. As per FIG. 6A and FIG. 6B, the description of many items shown in this figure is deferred to their descriptions in FIG. 5A and FIG. 5B. Note that the Purge Valve Sealing Member  32  is separated from the Rigid Support Disk  36 , thereby allowing the contents of the snorkel to be expelled through the Rapid Purge Channels  39 . The Purge Valve Sealing Member  32  has a bias for closure molded into its shape such that the Airway Pressure  65  must be distinctly greater than the Ambient Water Pressure  66  in order for the Purge Valve Sealing Member  32  to become displaced form the Rigid Support Disk  36 . The Convoluted Membrane  40  assumes a transverse sectional shape that is compatible with the Rigid Support Disk  36  being at its lowest end of travel.  
         [0096]    [0096]FIG. 7A is a sectional view of an alternative embodiment of the snorkel that replaces the three parts of the Combined Sealing Assembly  6  with one single molded flexible rubber part, the Flexible Sealing Member  69 . In doing so, the Junction  75 , the Purge Cap  76 , and the Exhalation Tube Lower Mount  77  are all modified for this alternative embodiment. This Flexible Sealing Member  69  has a Sealing Member Anchor  70  along it circumference that secures this member to the Juntion  75  and the Purge Cap  76  in similar fashion to the Peripheral Anchor  42  previously described for the preferred embodiment. The Flexible Sealing Member  69  also has a Sealing Dome  73  component that provides the functionality of the Exhalation Valve Sealing Member  31  previously described for the preferred embodiment. The Rigid Support Disk  36  of the preferred embodiment has been eliminated. An optinal Rigid Ring  74  may be placed within the deeper folds of the Accordion Wall  71  for additional mechanical support. Purge operations are facilitated by a series of small Purge Slits  72  in the outer folds of Accordion Wall  71  which remain closed due to the molded shape of the wall and the compressive forces of ambient water, until the Airway Pressure  65  is adequate to fully distend the Accordion Wall  71 , thereby opening these Purge Slits  72  in a fashion similar to duck bill valves.  
         [0097]    [0097]FIG. 7B is the alternative embodiment of FIG. 7A in a condition of normal exhalation as is the condition of the preferred embodiment in FIG. 6B, in which the Airway Pressure  65  is adequate for exhalation, but inadequate for rapid purge operation. The Sealing Dome  73  has separated from the Exhalation Tube Sealing Ring  47  allowing exhaled air to exit the snorkel as shown by the Flow Arrows  75   
         [0098]    [0098]FIG. 7C is the alternative embodiment of FIG. 7A in a condition of purge operation as is the condition of the preferred embodiment in FIG. 6C, in which the Airway Pressure  65  is exceeds the threshold pressure for purging. Purge Slits  72  are now evident in the lower, outer silicon rubber (or otherwise flexible) Accordion Wall  71 . These Purge Slits  72  open with sufficient pressure to provide excellent purge capability, but otherwise generally remain closed for normal exhalation activities.  
         [0099]    [0099]FIG. 8 reveals another embodiment of the snorkel that now features a significantly modified design of the Junction  78  that similarly contains a Chamber  80  for counter pressure, but has an Exhalation Exit Port  83  near the bottom of the snorkel, an External Exhalation Tube Mount  84 , and an External Exhalation Tube. The moving element which provides counter pressure for our desired PEEP is the Sealing Cup  80  which travels coaxially and is supported laterally by the a Sealing Cup Rigid Support  81 . As the forces of Airway Pressure  65  in the Chamber overcome the forces of Ambient Water Pressure  66 , the Sealing Cup  81  separates from the O-Ring Seal  82 , allowing air to escape into the space above the perimeter of the Sealing Cup  81 , which is then vented to the External Exhalation Tube  86  via the External Exhalation Tube Mount  85 . A Sliding Seal  87  helps maintain dryness within the snorkel and deflects downward with the greater FIG. 8 is another cross sectional pressures accomplished during purge operations  
         [0100]    [0100]FIG. 9 is a transverse sectional view of the enclosing structures of the Exhalation Valve [ 4 ] as is modified to attach, via a non-collapsible air tube, to the exhalation vent on a typical scuba regulator. This invention, in effect, becomes an “exhalation regulator” for scuba diving purposes, as it functions to regulate the exhalation rate of the scuba diver. The device may be worn at mouth or chest level, depending on the comfort of the user. The Junction  88  has been shortened from the preferred embodiment (described in FIGS. 5A thru  5 D and FIGS. 6A thru  6 C) for this alternative embodiment as it may be adapted for scuba or snuba purposes. Furthermore, the Mouthpiece Mount  25  of the preferred snorkel embodiment has been eliminated as this is not necessary for scuba The exhalation vent from the separate scuba regulator attaches via a Connecting Tube  94  to the Ribbed  90  Connecting Tube Mount  89 . The Exhalation Tube  92  has been significantly shortened and the Exhalation Conduit Exit Port  95  has been moved to the Junction  88 . The Chamber  93  importantly continues to serve as a counter pressure chamber to accomplish the improved exhalation pressures as described herein.  
         [0101]    [0101]FIG. 9 is transverse sectional view of the Exhalation Valve  4  and related structures as described in FIG. 6B and as adapted to mount to the exhalation vent on a scuba regulator or snuba equipment. Note that the Exhalation Tube  48  is significantly shortened and exits from the Junction  22  through a sidewall in the Junction  22 ].  
         [0102]    While the present inventions have been described and illustrated in conjunction with a number of specific embodiments, those skilled in the art will appreciate that variations and modifications may be made without departing from the principles of the inventions as herein illustrated, described and claimed.  
         [0103]    The present inventions may be embodied in other specific forms without departing from their spirit or characteristics. The described embodiments are to be considered in all respects as only illustrative, and not restrictive. The scope of the inventions is, therefore, indicated by the appended claims, rather than the foregoing descriptions. All changes and variations that come within the meaning and range of equivalency of the claims and their elements or limitations are to be embraced within their scope.