Abstract:
A snorkel is designed for swimming is shaped to offer a minimum of drag to permit the user to expend less energy while moving with greater speed through the water. The lower portion of the snorkel is constructed from a flexible internal skeleton/external shell which enables the breathing tube to closely conform to the head of the swimmer, eliminating gaps that give rise to turbulence and drag. The snorkel also features a cross-sectional profile that minimizes water resistance. The lower portion of the snorkel is in the shape of a half circle, with the straight edge facing the user and the circular edge facing outward and offering a streamlined profile to the water. The upper half of the snorkel is in the shape of an airfoil, with the tips pointing into and away from the direction of motion, thereby facilitating movement of the snorkel through the water.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This non-provisional patent application claims priority from provisional patent application No. 60/071,338, filed Jan. 14, 1998 and entitled “HYDRODYNAMIC AND ERGONOMIC SNORKEL”. This provisional patent application is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to a water snorkel for swimming that has enhanced hydrodynamic and ergonomic properties. More specifically, the invention relates to a breathing tube having a flexible lower portion and a cross-sectional profile that allows it to conform to the face of the user and offer a minimum of resistance to the water. 
     2. Description of the Related Art 
     The use of a breathing tube to allow a swimmer to maintain facial position below the surface of the water is well known. Snorkels are useful in clear water to allow observation of underwater plant and animal life. Snorkels can also be used to allow movement with greater speed and efficiency through the water. 
     A swimmer will stroke with ideal efficiency when his or her face is in the water, but the back of the head remains out of the water. Many swimmers find breathing difficult while maintaining ideal stroke form, as pushing the chin forward to lift the back of the head out of the water creates a strain in the trachea. 
     Moreover, when a swimmer raises his or her head to breathe, the hips and legs sink into the water. A two-inch vertical lift of the head can result in a four- to six-inch drop of the hips, and a corresponding eight- to twelve-inch drop of the feet. This departure from ideal stroke form can double the frontal surface area offered to the water, thereby doubling the water resistance encountered by the swimmer. 
     Because a snorkel allows the swimmer to breathe without raising his or her head, snorkels have been used to assist athletes train for competition. One example of a snorkel designed for swimmers is the “Finis Center Mount Swimmer&#39;s Snorkel” (hereafter “the Finis snorkel”) manufactured by Finis, Inc. of Tracy, Calif. 
     FIG. 1 illustrates a profile view of the Finis snorkel. The Finis snorkel  100  includes a breathing tube  102  that extends out from the mouth and includes an upper portion  104  which extends upward at the center of the face between the eyes of the user, with open end  106  ultimately projecting above the surface of the water. Breathing tube  102  also includes a downward portion  108  housing a water reservoir  110  and a purge valve  112 . 
     While the Finis snorkel is useful for training, it suffers from a number of disadvantages. 
     First, purge valve  112  is a traditional design used for diving. In order to activate conventional diving purge valve  112 , reservoir  110  must be filled with water above the mouth area. When the user sharply exhales, water in the snorkel is forced upward, and provides sufficient back pressure to offset external water pressure and activate the purge valve. Accumulated air and water are expunged, and the swimmer can breathe again. 
     When a snorkel is used by a scuba diver, water normally fills the entire snorkel and the conventional purge valve works adequately. However, when a snorkel is used primarily for surface activities such as swimming and snorkeling, the snorkel will contain some water but will not ordinarily become filled. 
     The conventional diving-type purge valve of the Finis snorkel is thus unsuited for swimming and snorkeling, as a relatively large volume of water must accumulate in the snorkel before it can be purged. This accumulated water consumes valuable air space, decreasing the flow of air available to the swimmer. Accumulated water can also splash into the swimmer&#39;s airway, making breathing uncomfortable. 
     A second disadvantage of the Finis snorkel is that the cross-section of breathing tube  102  is designed to be as narrow as possible. The narrowness of breathing tube  102  is intended to offer minimum resistance while the user&#39;s face is underwater, and also to force the user to breathe harder and thereby enhance aerobic activity during training. 
     However, in applications such as open water swimming or snorkeling, safety rather than fitness is of paramount concern and a narrow breathing tube could interfere with necessary and proper breathing. Moreover, use of a narrow breathing tube does not necessarily ensure that water resistance will be kept to a minimum. 
     A third disadvantage of the Finis snorkel is the manner in which it is worn. The Finis snorkel is held to the forehead by thick plastic headband  114 . Headband  114  must be worn tight around the head, and is made of solid plastic to ensure secure attachment. Headband  114  may exert an uncomfortable pressure upon the swimmer&#39;s brow. 
     Moreover, in order to don the snorkel, the user must turn mouthpiece  116  to one side and then slide headband  114  down over the forehead, finally turning mouthpiece  116  back to fit within the mouth. Furthermore, headband  114  does not have a release clip, making it difficult to remove the snorkel. 
     A fourth disadvantage of the Finis snorkel is that open end  106  of breathing tube  102  projects substantially vertically above the water surface. This shape permits water to enter the snorkel via splashing from the swimmer or those nearby. 
     A fifth disadvantage of the Finis snorkel is that upper portion  104  of breathing tube  102  is located in front of the face and between the eyes of the user. This positioning interferes with the swimmer&#39;s line of vision of the swimmer, conveying the unpleasant sensation of being cross-eyed. 
     A sixth disadvantage of the Finis snorkel is that breathing tube  102  is fixed by headband  114  at a distance from the face of the user. Gap  118  between the swimmer&#39;s head and the breathing tube contributes turbulence and drag to movement of the snorkel through the water, and also permits the snorkel to move from side-to-side in response to resistance offered by the water. This “wavering” of the snorkel is distracting to the user, and also creates additional water resistance to impede movement of the swimmer through the water. 
     Given the above-listed disadvantages, there is a need in the art for a snorkel design that permits a swimmer to efficiently move through the water with a minimum of drag and a maximum of comfort. 
     SUMMARY OF THE INVENTION 
     The present application relates to a snorkel which includes a number of features that reduce the frictional resistance as the snorkel passes through the water. The lower portion of the snorkel in accordance with the present invention is flexible and may be shaped to conform to the face of the swimmer, thereby eliminating drag attributable to the gap between the snorkel and swimmer&#39;s head. 
     The snorkel design in accordance with the present invention also includes a cross-sectional profile specifically intended to reduce water resistance. Specifically, the cross-section of the lower portion of the snorkel is in the shape of a half-circle, such that the flat edge faces the swimmer and the round edge faces the water. The lower half of the snorkel thus offers less resistance to water displaced by the swimmer, which flows easily around the rounded facing edge of the snorkel. 
     The cross-section of the upper half of the snorkel is in the shape of an airfoil. The tips of this airfoil face into and away from the direction of movement, offering less resistance as the snorkel moves through the water. 
     A snorkel in accordance with one embodiment of the present invention comprises a lower breathing tube portion having a half-circular cross-section including a straight edge and a curved edge, the lower portion including a mouthpiece positioned in front of the straight edge and open to a breathing chamber and a purge valve permitting one-way flow of air and water out of the airway, and an upper breathing tube portion joined to a lower portion at a junction, the upper portion having an airfoil cross-section including a leading corner and a trailing corner, the upper portion including a check valve operable from an inactivated state permitting free movement of air to an activated state preventing movement of air into and out of the check valve, the upper portion also including an upper opening. 
     The features and advantages of the present invention will be better understood upon consideration of the following detailed description of the invention and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view of the Finis snorkel. 
     FIG. 2 shows a perspective view of a snorkel in accordance with a first embodiment of the present invention. 
     FIGS. 3A and 3B show cross-sectional views of the lower and upper portions of the snorkel shown in FIG.  2 . 
     FIGS. 4A and 4B show cut-away views of the lower portion of the snorkel shown in FIG.  2 . 
     FIG. 5 shows a cut-away view of the upper portion of the snorkel shown in FIG.  2 . 
     FIG. 6 shows a perspective view of the snorkel in use. 
     FIGS. 7A and 7B show perspective views of a second embodiment of the snorkel in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION 
     The present invention is a hydrodynamic and ergonomic snorkel design that facilitates swimming with the body in ideal stroke position, without requiring the swimmer to rotate his or her head out of the water in order to breathe. The snorkel is especially designed to be used at the water&#39;s surface, for activities such as swimming and snorkeling. As with a conventional snorkel, a hollow tube allows the head to reside in the water while it transports air from above the surface of the water to the mouth below. 
     FIG. 2 shows a perspective view of a snorkel in accordance with a first embodiment of the present invention. Snorkel  200  includes a breathing tube  202  that includes an upper portion  204  and a lower portion  206  which meet at junction  208 . 
     Upper portion  204  has an “airfoil” cross-sectional shape. Upper portion  204  is constructed from hard and stiff injection-molded plastic. 
     Upper portion  204  includes an internal check valve having adjustment screw  212  positioned at the end of straight segment  204   a  prior to arc segment  204   b.  Arc segment  204   b  changes direction 180° from straight segment  204   a,  such that the upper opening  210  positioned at the end of upper portion  204  faces lower portion  206 . Opening  210  faces downward over the top of the swimmer&#39;s head. This orientation of upper opening  210  prevents water splashing over the top of the snorkel from entering through upper opening  210 . However, upper opening  210  remains positioned far enough above the surface of the water to prevent the user from accidentally inhaling water. 
     Lower portion  206  of breathing tube  202  has a “half-circular” cross-sectional shape. Lower portion  206  includes a mouthpiece  214  positioned in front of a breathing chamber  216 , and a recessed purge valve  218 . 
     Lower portion  206  of breathing tube  202  is constructed from a soft plastic shell  221  of lightweight and flexible material such as polyurethane. Support wire  222  runs along the inside corners of shell  221  at opposite corners  228 , lending additional support to lower portion  206 . When necessary, a flexible mesh or a series of internal ribs may provide additional support for lower portion  206 . 
     Because shell  221  and wire  222  are all composed of flexible materials, the shape of lower portion  206  can readily be adjusted to conform to the contour of the face of a particular user. Moreover, shell  221  can be fabricated utilizing a mold in the general shape of a face. Molds of various sizes can be utilized to model the faces of children, adolescents, and adults. 
     Snorkel  200  is secured to the head of a user by thin, adjustable rubber strap  230 . Strap  230  includes a loop  232  enclosing junction  208 . The ends of strap  230  are fitted to simple clasp  234 , so that the user can release clasp  234  at the back of the head and pull the snorkel quickly and easily away from the face. 
     The strap, the hydrodynamic shape of the lower portion, and the conformity of the snorkel to the face each secure lower portion  206  in place against the head of the swimmer. This frees the swimmer from having to clamp his or her teeth down upon mouthpiece  214  in order to hold snorkel  200  in place. Instead, snorkel  200  rests comfortably in the mouth. 
     FIGS. 3A and 3B show cross-sectional views of the upper and lower portions of the snorkel. FIGS. 3A and 3B underscore that the snorkel possesses two distinct cross-sectional shapes. As shown in FIG. 3A, below junction  208  breathing tube  202  assumes a “half-circle” shape, having a straight edge  224  and rounded edge  226 . Support wire  222  is runs along opposite corners  228  of this half-circle. 
     As shown in FIG. 3B, above junction  208  breathing tube  202  assumes an “airfoil” shape having leading and trailing corners  230 . Upper portion  204  is formed from lightweight and hard injection molded plastic, and therefore does not require a support wire. 
     FIGS. 4A and 4B show different cut-away views of lower portion  206  of snorkel  200 . Breathing tube  202  is capped by recessed purge valve  218 . FIG. 4A shows recessed purge valve  218  as an umbrella valve, where center  236   a  of flap  236  is fixed to cross-member  238 . Peripheral edges  236   b  of flap  236  are flexible away from center  236   a  and cross-member  238 . When the user exhales with sufficient force to overcome the external pressure, recessed purge valve  218  permits the flow of air and water out of the snorkel. However, recessed purge valve  218  precludes the reverse flow of water or air back into the snorkel. 
     FIG. 4B shows the position of purge valve  218  within lower portion  206 . Purge valve  218  is recessed within lower portion  206 , such that interior walls  206   a  shield flap  236  from being displaced by outside water movement. Purge valve  218  may also be removable from lower portion  206  to allow maintenance or replacement. 
     Returning to back to FIG. 2, upper portion  204  of breathing tube  202  includes a straight segment  204   a  located above junction  208 . At the end of straight segment  204   a , arc segment  204   b  turns approximately 180° and curves downward over the top of the swimmer&#39;s head. FIG. 5 shows a cut-away view of upper portion  204 . 
     Internal check valve  240  is positioned at the top of straight segment  204   a , before upper portion  204  makes its downward arc. Internal check valve  240  is a tension-controlled flap valve that allows the user to purge the air chamber at will. Flap  242  of internal check valve  240  is attached to the underside of valve lip  244  within the breathing tube. Check valve  240  is adapted from a design previously utilized for irrigation, specifically, the 1″ King Swing Check, manufactured by King Brothers Industries of Valencia, Calif. 
     When check valve  240  is in an inactivated state, flap  242  hangs down freely, allowing air to pass in and out of valve  240  to the user&#39;s mouth below. When the user wishes to clear accumulated water, the swimmer rolls to the side in the normal course of swimming and sharply exhales. 
     This sharp exhalation causes flap  242  to swing upwards into its activated position against lip  244 . This closes check valve  240 , preventing the passage of air in either direction. Closing check valve  240  in turn creates an internal pressure within the snorkel that is greater than the external water pressure, allowing air and accumulated water to pass out of recessed purge valve  218 . 
     Unlike the 1″ King Swing Check valve, check valve  240  also includes an adjustable screw  212 . Flap  242  is extended out into the airway of breathing tube  202  by adjustable screw  212 . Screw  212  allows the user to control how far out into the airway flap  242  extends in the inactivated position, and thus the amount of pressure needed to close internal check valve  240 . 
     For example, a swimmer moving at a fast speed in open water splashes a great deal more than a slower swimmer doing relaxed laps in a pool. The faster swimmer&#39;s movements cause larger amounts of water to enter the snorkel, and require that the snorkel be purged more frequently and easily. The faster swimmer will therefore adjust screw  212  to extend flap  242  out further into the airway, so that flap  242  is activated by less pressure. Conversely, the slower swimmer will adjust screw  218  to extend less further into the airway, so that occasional exhalation with greater force is necessary to activate check valve  240  and purge snorkel  200 . 
     FIG. 6 shows a perspective view of snorkel  200  during the act of purging. Swimmer  246  has rolled such that the recessed purge valve occupies the lowest point of the snorkel. Accumulated water therefore flows to purge valve and is expelled from the snorkel by sharp exhalation. Moreover, in this position arc segment  204   b  of upper portion  204  lies above the upper opening, so that water trapped above the closed check valve may simply drain out of the upper opening. 
     FIG. 6 also reveals that strap  230  marks a line across the forehead that corresponds to “perfect head position” in the water. FIG. 6 further reveals the closeness with which snorkel  200  fits against the swimmer&#39;s face without interfering with his or her vision. 
     The present invention offers a number of important advantages over existing snorkel designs. In particular, a snorkel in accordance with the present invention offers a minimum of resistance to the water. This is because the lower portion of the snorkel is flexible, and can be shaped to conform to the curvature of the face of the user. Moreover, the half-circular cross-sectional profile of the lower portion of the snorkel allows it to lie flush against the face of the swimmer. Both of these features significantly reduce drag associated with turbulence generated by the gap between the face and the snorkel. 
     The snorkel in accordance with the present invention also offers the advantage of inhibiting the unwanted entry of water into the breathing tube. This is accomplished by orienting the upper opening of the snorkel to face the top of the swimmer&#39;s head. 
     The snorkel in accordance with the present invention further offers the advantage of convenience, as the clasp permits easy fitting or removal of the snorkel. 
     The snorkel in accordance with the present invention is also advantageous in that the upper portion of the snorkel is disposed to the side of the face of the swimmer. This preserves the line of sight of the user, and prevents the “cross-eyed” sensation that users may find distracting. 
     Although the invention has been described in connection with one specific preferred embodiment, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Various other modifications and alterations in the structure and method of operation of the invention will be apparent to those skilled in the art, without departing from the scope of the present invention. 
     For example, a second embodiment of the snorkel in accordance with the present invention is illustrated in FIG.  7 A. FIG. 7A shows a rear view of snorkel  700 , which includes two breathing tubes  720   a  and  720   b  positioned on either side of mouthpiece  704 . Each breathing tube  720   a  and  720   b  has the cross-sectional profile of the breathing tube  202  described above in accordance with the first embodiment of the present invention, except that a waterproof radio  706   a  is positioned in a housing located immediately above junction  708   a  of breathing tube,  720   a.    
     Breathing tubes  720   a  and  720   b  are joined at the top of the head to define upper opening  710 . Upper opening  710  is oriented to the rear and opens downward over the head of the swimmer. Utilization of a snorkel design in accordance with this second embodiment allows greater air flow to the swimmer and enhanced structural stability for the snorkel. 
     Snorkel  700  also includes two drainage chambers  712   a  and  712   b , each chamber including a separate purge valve  714   a  and  714   b , respectively. This feature increases the volume of the drain chamber available to the swimmer, allowing the swimmer to swim for longer periods before having to purge collected water. This feature also directs excess water away from the swimmer&#39;s mouth as the swimmer inhales through the mouthpiece. 
     FIG. 7B shows a side view of snorkel  700 , wherein waterproof radio  706   a  is positioned immediately above junction  708   a . Waterproof radio  706   a  can include an AM/FM receiver and/or a receiver enabling the swimmer to receive communications from an instructor or coach via earpieces  716   a  and  716   b . Housing  706   b  on the second breathing tube  702   b  (corresponding to the location of radio  706   a  on first breathing tube  702   a ) could store additional batteries for radio  706   a , allowing for longer periods of use. 
     In conclusion, the various embodiments of the present invention should generally be viewed as being complementary rather than exclusive. Thus, a snorkel in accordance with the present invention could be fabricated combining some or all of the features described. 
     For example, a snorkel in accordance with the present invention that includes a half-circle and airfoil cross-sections could, but would not be required to also include the curved upper breathing tube portion disposing the upper opening toward the lower portion. 
     Similarly, a snorkel having a single breathing tube could be adapted to contain a waterproof radio including a single earpiece, or a snorkel having a single breathing tube could be equipped with a dual chamber drainage area. 
     Therefore, it is intended that the following claims define the scope of the present invention, and that the methods and structures within the scope of these claims and their equivalents be covered hereby.