Abstract:
A duct structure for a watercraft includes a flexible tube for providing an air intake for the watercraft and a flexible member for being disposed on an inner perimeter of a hole in a hull of the watercraft for holding the flexible tube. A convex portion of the flexible tube engages at least one concave portion of the flexible member around substantially the entire circumference of the flexible member, allowing for easy insertion and removal of the flexible tube from the flexible member.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a duct structure for watercraft. More specifically, the present invention relates to a duct structure for an air intake duct for watercraft. 
   2. Description of the Related Art 
   Personal watercraft have become very popular in recent years. This type of watercraft is quite sporting in nature and carries a rider and possibly one, two, three, or four passengers. A relatively small hull of the personal watercraft commonly defines a rider&#39;s-area above an engine compartment. An internal combustion engine-frequently powers a jet propulsion unit which propels the watercraft. The engine is disposed within the engine compartment in front of a tunnel provided on the underside of the watercraft hull. The jet propulsion unit is located within the tunnel and is driven by the engine. 
   Air ducts typically communicate air into the engine compartment for induction by the engine and to ventilate the engine compartment. 
     FIG. 8  illustrates a known air duct structure. Each air intake duct  78  includes a rigid pipe  70 , made of hard plastic, extending through the deck  16  of hull  12  and terminating at a first end  72 . A flange  74  disposed around the pipe  70  abuts a portion of the deck  16 . Fasteners, such as rivets  76 , for example, extend through the flange  74  and the deck  16  to secure the pipe  70  to the deck  16 . 
   An elbow  78  of the pipe  70  directs the pipe  70  downwardly and slightly forwardly into the engine compartment. A flexible pipe  80  is attached to a second end  82  of the rigid pipe  70  and can be configured so as to communicate with any desired location within the hull  12 . 
   The air duct structure shown in  FIG. 8  is quite complicated as seen by the number of parts required to form the duct stricture. Further, this duct structure has a high production cost and is difficult to assemble. More specifically, the flange  74  must be secured to the deck  16  by rivets  76  to secure the air duct structure, and the air duct structure includes two separate pipes  70 ,  80  that must be joined to each other. 
   SUMMARY OF THE INVENTION 
   To overcome the problems described above, preferred embodiments of the present invention provide a duct structure having fewer parts, being less complicated to assemble, and having a reduced production cost as compared to known duct structures. 
   According to the preferred embodiment of the present invention, a duct structure for a watercraft includes a flexible tube for providing an air intake for the watercraft, and a flexible member for being disposed on an inner perimeter of a hole in a hull of the watercraft for holding the flexible tube. 
   The flexible member is preferably removably attached to a deck portion of a hull of the watercraft at an inner surface and outer surface of the deck portion. 
   The flexible tube is preferably a single integral tube member extending through the hull of the watercraft and to an engine area of the watercraft, and is preferably formed of a flexible material such as rubber. 
   The flexible member preferably includes an exterior concave portion for engaging the hull of the watercraft. The exterior concave portion engages an interior surface and an exterior surface of the hull and fixes the flexible member to the hull. The flexible member does not require additional attaching devices such as rivets to be fixed to the hull of the watercraft as with conventional duct structures. 
   The flexible member also preferably includes at least one interior concave portion for engaging an exterior convex portion of the flexible tube to reliably hold the flexible tube in place relative to the hull of the watercraft. The at least one interior concave portion of the flexible member extends around an entire circumference of the flexible member and has a substantially semicircular cross section. The at least one concave member of the flexible member is arranged such that the exterior convex portion of the flexible tube engages the at least one concave portion of the flexible member around substantially the entire circumference of the flexible member. 
   According to another preferred embodiment of the present invention, a duct structure for a watercraft includes a hull of the watercraft having a hole provided therein, a flexible tube providing an air intake for the watercraft, and a flexible member disposed in the hole of the hull for holding the flexible tube. 
   As with the other preferred embodiment described above, the flexible tube is preferably a single integral tube member extending through the hull of the watercraft and to an engine area of the watercraft. 
   The flexible tube also includes a convex portion formed by a spring member provided along the flexible tube and the convex portion preferably has a spiral shape. The spring member is preferably made of a wire or a resin or both. The flexible member includes at least one concave portion for engaging the convex portion of the flexible tube. 
   The at least one concave portion of the flexible member extends around the circumference of the flexible member and has a substantially semicircular cross section. The convex portion of the flexible tube engages the at least one concave portion of the flexible member around substantially the entire circumference of the flexible member. The semicircular cross section of the at least one concave portion of the flexible member has substantially the same radius as the convex portion of the flexible tube. 
   According to another preferred embodiment of the present invention, a duct structure for a watercraft includes a hull having with a hole provided therein, a flexible tube for providing an air intake for the watercraft, and a holding member disposed in the hole of the hull for fixing the flexible tube to the hull. 
   The flexible tube preferably includes a convex portion defined by a spring member and the convex portion preferably has a spiral shape. The spring member is preferably made of either a wire or a resin or both. 
   The flexible tube is preferably of a flexible elastic material. 
   The flexible tube is preferably a single integral tube member extending through the hull of the watercraft and to an engine area of the watercraft. 
   The holding member includes a flexible member disposed on an inner perimeter of a hole in a hull of the watercraft for holding the flexible tube. The flexible member includes an exterior concave portion for engaging the hull of the watercraft, the exterior concave portion engages an interior surface and an exterior surface of the hull and fixes the flexible member to the hull. 
   Any of the preferred embodiments described above can be modified by providing the flexible member with at least one lip extending around the circumference thereof such that the at least one lip contacts the flexible tube between exterior convex portions of the flexible tube. As a result, the lip and the flexible tube form a seal. More preferably, the at least one lip is arranged such that, when the at least one lip contacts the flexible tube, a seal is formed between the flexible member and the deck. Also, it is preferred that the flexible member is symmetric about a plane defined by the inner perimeter of the hole in the hull of the watercraft when the flexible member is disposed in the inner perimeter of the hole in the hull of the watercraft. It should be noted that a plurality of lips could also be provided on the flexible member. 
   Other features, elements, characteristics, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiment of the present invention with reference to the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is side view of a personal watercraft including a duct structure according to a preferred embodiment of the present invention. 
       FIG. 2  is top view of the personal watercraft shown in  FIG. 1 . 
       FIG. 3  is a sectional view of the duct structure according to the preferred embodiment of the present invention. 
       FIG. 4  is sectional view of the hull of a watercraft having the duct structure according to a preferred embodiment of the present invention. 
       FIG. 5  is close-up sectional view of the duct structure according to the preferred embodiment of the present invention. 
       FIG. 6  is sectional view of the flexible tube of the duct structure according to a preferred embodiment of the present invention. 
       FIG. 7A  is a view of the gasket of the duct structure according to a preferred embodiment of the present invention. 
       FIG. 7B  is sectional view of the gasket of the duct structure according to a preferred embodiment of the present invention. 
       FIG. 8  is sectional view of the hull of a watercraft having a prior art duct structure. 
       FIG. 9  is sectional view of a modification of the duct structure according to another preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIGS. 1 and 2  illustrate a personal watercraft  10  that includes a duct structure configured in accordance with a preferred embodiment of the present invention. Although these features are illustrated in connection with a personal watercraft, the features can be used with other types of watercraft as well, such as, for example, but without limitation, small jet boats and other suitable watercraft. 
   The following describes the illustrated watercraft in reference to a coordinate system in order to ease the description of the watercraft  10 . A longitudinal axis extends from bow to stem and a lateral axis extends from port side to starboard side perpendicular to the longitudinal axis. A vertical axis extends perpendicular to both the longitudinal axis and the lateral axis. And in  FIGS. 1 and 2 , a label “Fr” has been included which designates a forward direction for reference purposes. 
   With reference to  FIGS. 1 and 2 , the watercraft  10  includes a hull  12  having a lower hull  14  and a deck  16 . The lower hull  14  and the deck  16  are formed from a suitable material such as, for example, a molded fiberglass reinforced resin or a sheet molding compound (SMC). The lower hull  14  and the deck  16  are fixed to each other around peripheral edges thereof in any suitable manner. 
   A bond flange  18  is defined as the overlapping mating section where the lower hull  14  and the deck  16  are joined together. The bond flange  18  also identifies the location of a bond line, which is an imaginary line around the watercraft  10  where the lower hull  14  and the deck  16  are joined together. Accordingly, the deck  16  generally comprises the upper structural body of the watercraft  10 , which includes the upper bond flange  18 . 
   The lower hull  14  is designed such that the watercraft  10  planes or rides on a relatively small surface area at the aft end of the lower hull  14  in order to optimize the speed and handling of the watercraft  10  when on plane. For this purpose, the lower hull  14  generally has a V-shaped configuration having a pair of inclined sections that extend outwardly from a keel line of the hull to the hull&#39;s side walls at a dead rise angle. The inclined sections also extend longitudinally from the bow toward the transom of the lower hull  14 . The side walls are generally flat and straight near the stern of the lower hull and smoothly blend towards the longitudinal center of the watercraft at the bow. The lines of intersection between the inclined section and the corresponding side wall form the outer chines of the lower hull  14 . 
   Toward the transom of the watercraft  10 , a recessed channel or tunnel  20  is formed and extends generally upward toward the deck  16  and opens through the rear of the transom of the watercraft  10 . 
   With more specific reference to  FIG. 1 , the deck  16  includes a bow portion  22 , a control mast  24 , and a rider&#39;s area  26 , as viewed in the direction from the bow to the stern of the watercraft  10 . The bow portion  22  slopes upwardly toward the control mast  24 . A hatch cover  28  desirably extends above a storage compartment provided in the lower hull  14 . Air ducts  30  are formed through the deck  16  and allow air to enter and/or exit compartments within the interior of the lower hull  14 . The structure and operation of the air ducts  30  will be described in more detail below. 
   With reference to  FIGS. 1 and 2 , a fuel tank  32  is located within a forward portion of the hull  12  beneath the hatch cover  28 . Conventional members, such as, for example, straps, secure the fuel tank  32  to the lower hull  14 . A fuel filler hose (not shown) extends between a fuel cap  34  and the fuel tank  32 . The fuel cap  34  is secured to the bow portion  22  of the deck  16  to the side and in front of the control mast  24 . A storage box  140  is formed within the hull  12  and under the seat assembly  42 . The storage box  140  opens upwardly and is accessible by moving or removing the seat  42 . 
   With reference again to  FIGS. 1 and 2 , the control mast  24  extends from the bow portion  22  and supports a handlebar assembly  36 . The handlebar assembly  36  controls the steering of the watercraft  10  in a conventional manner. The handlebar assembly  36  also carries a variety of controls for the watercraft  10 , such as, for example, a throttle control, a start switch, and a lanyard switch. A cowling  40  covers a portion of the deck  16 . The deck  16  supports a steering column to which the handlebar assembly  36  is attached, at a point beneath the cowling  40 . 
   A display panel (not shown) desirably is located in front of the control mast  24  on the bow portion  22  and is orientated to be visible by the rider. The display panel desirably displays a number of performance characteristics of the watercraft, such as, for example, watercraft speed (via a speedometer), engine speed (via a tachometer), fuel level, oil level, engine temperature, battery charge level, and other suitable performance characteristics. 
   The rider&#39;s area  26  lies behind the control mast  24  and includes a seat assembly  42 . The seat assembly  42  has a longitudinally extending straddle-type shape that may be straddled by an operator and by at least one, two, or three passengers. 
   At least a portion of the hull defines an engine compartment  44  that is located primarily below the seat  42  and encloses an internal combustion engine  46 , which supplies propulsive force to the watercraft  10 . The engine  46  preferably is a four cycle, three cylinder, inline engine and is disposed so that its cylinder bores are inclined slightly to one side of vertical. While the illustrated engine is preferably of the four-cycle variety, the engine also can be of the two-cycle or rotary variety as well. Moreover, the engine can have one, two, or more than three cylinders and can be formed with two banks of cylinders. 
   The engine  46  drives an output shaft  48  that is coupled to an impeller shaft  50 . The impeller shaft  50  drives an impeller within an impeller housing assembly  52  of a jet propulsion unit  54 , which is mounted within the tunnel  20 . The impeller housing assembly  52  also acts as a pressurization chamber and delivers the water flow from the impeller housing to a discharge nozzle  56 . 
   A steering nozzle  58  is supported at the downstream end of the discharge nozzle  56  by a pair of vertically extending pivot pins. The steering nozzle  58  has an integral lever on one side that is coupled to the handlebar assembly  36  through, for example, a bowden-wire actuator, as known in the art. In this manner, the operator of the watercraft  10  can move the steering nozzle  58  to effect directional changes of the watercraft  10 . 
   An exhaust system  60  discharges exhaust byproducts from the engine  46  to the atmosphere and/or to the body of water in which the watercraft  10  is operated. The exhaust system  60  includes an exhaust manifold  62  that is affixed to the side of the engine cylinder block and which receives exhaust gases from the combustion chambers through exhaust ports in a well-known manner. For this purpose, the exhaust manifold  62  desirably includes a number of runners  64  equal in number to the number of cylinders. Each runner communicates with the exhaust port(s) of the respective cylinder. The runners of the exhaust manifold merge at a merge point to form a common exhaust path that terminates at an outlet end of the manifold  62 . 
   An outlet end of the exhaust manifold communicates with an exhaust expansion chamber  66 , which wraps around the front side of the engine  46  and extends along an opposite side of the engine  46  to a point just beyond the rear side of the engine  46 . The expansion chamber  66  then turns downward and communicates with a water trap (not shown). A discharge conduit (not shown) extends from the water trap in a known manner to an exhaust discharge port formed through the hull in the tunnel. 
   While not illustrated, the engine also includes an induction system that provides air to each combustion chamber for combustion. The induction system can be configured in any suitable manner and may provide either an air charge (i.e., for direct injection engines or for engines having fuel injected into scavenge passages) or a mixed air-fuel charge (i.e., for indirect injection engines or carbureted engines). Thus, the induction system draws air from the compartments defined within the hull into the engine. 
     FIGS. 3 and 4  illustrate a structure of the air ducts  30  shown in  FIGS. 1 and 2  according to a preferred embodiment of the present invention. The air duct shown in  FIGS. 3 and 4  includes a flexible tube  110  attached to the deck  16  of the hull  12  by a gasket  100 . As can be seen in  FIGS. 3 and 4 , the flexible tube  110  is preferably a single, unitary member the is continuously formed and is not made up of two or more separate tubes as with the prior art described above. 
   The gasket  100  is disposed on the inner circumference of a hole in the deck  16 . As shown in  FIGS. 7A and 7B , the gasket  100  includes exterior groove  103  that includes an exterior flange portion  104  and an interior flange portion  105 . Exterior groove  103  engages the deck  16  of the hull  12 . Exterior flange portion  104  is in contact with the exterior surface of the deck  16 , and interior flange portion  105  is in contact with the interior surface of the deck  16 . 
   The gasket  100  further includes a top interior groove  101  and a bottom interior groove  102  which engage the flexible tube  110  to fix it to the hull  12 . Gasket  100  is flexible so that is can easily be inserted into the hole of deck  16  and is preferably made of rubber. However, any other suitable flexible material can be used. 
   With this unique structure including the exterior groove and flange and interior grooves of the gasket  100 , it is not necessary to use rivets or other such devices to fix or secure the gasket  100  and tube  110  to the deck  16  of the hull  12 , the air duct  30  can be easily and removably fixed to the deck  16  of the hull  12  so assembly is greatly simplified, and the gasket  100  reliably holds the flexible tube  110  in place so the flexible tube  110  is not unexpectedly or undesirably removed. 
   The flexible tube  110  is preferably made of a flexible material such as rubber and is a single integral continuously formed member. Although rubber is preferred, any other suitable flexible material can be used to form the flexible tube  110 . The flexible tube  110  preferably includes a spring member  112  for forming a convex portion  111  between adjacent spring members  112 , as shown in  FIG. 6 . The spring member  112  is preferably completely surrounded by the material of the flexible tube  110 . Preferably the spring member  112  is formed of metal. However, the spring member  112  could also be formed of a resin, and preferably a nylon resin, or other suitable material, or formed of a metal wire that is covered with a resin. 
   The exact manner in which the top interior groove  101  and bottom interior groove  102  engage the flexible tube  110  will now be described. As seen in  FIGS. 5 and 7B , the top interior groove  101  and the bottom interior groove  102  each have a recessed or concave configuration, respectively. The recess or concave portions formed by each of the top interior groove  101  and the bottom interior groove  102  preferably extend around the entire circumference of the gasket  100 . Preferably, the recess or concave portion formed by each of the top interior groove  101  and the bottom interior groove  102  has a semicircular cross section. 
   As shown in  FIG. 5 , the convex portion  111  formed by the spring member  112  of the flexible tube  110  engages the recesses or concave portions formed by the top interior groove  101  and the bottom interior groove  102  of the gasket  100 . Preferably, the convex portion  111  of the flexible tube  110  engages the concave portions of gasket  100  around substantially the entire circumference of the gasket  100 . 
   Preferably, the radius of the semicircular cross section of the recesses or concave portions formed by the top interior groove  101  and bottom interior groove  102  of the gasket  100  is slightly greater than the radius of the spring member  112  such that the convex portion  111  of the flexible tube  110  is held firmly and reliably in the concave portion of the gasket  100 . Even though the convex portion  111  of the flexible tube  110  is disposed firmly in the concave portion of the gasket  100 , the flexible tube  110  can easily be disengaged from the gasket  100  because of the flexible nature of the spring member  112 . 
   The flexible tube  110  can be made to engage the gasket  100  by pulling the tube from the exterior side of the hull  12  through the hole in the deck  16 . The flexible tube  110  can be disengaged from the gasket  100  by pulling the tube from interior side of the deck  16 . 
     FIG. 9  is sectional view that illustrates a modification to the duct structure according to another preferred embodiment of the present invention. The modification includes at least one lip and more preferably two lips  115  and  116  extending from the top and the bottom of the gasket  100 . Lips  115  and  116  extend along the entire circumference of the gasket  100 . The lips  115  and  116  extend away from the top and the bottom of the gasket  100  such that the lip ends  119  and  120  of each of the lips  115  and  116  contact the flexible tube  110  between spring members  112 . Preferably, the lip  115  and the flexible tube  110  form a seal, and the lip  116  and the flexible tube  110  form another seal. 
   Preferably, the lips  115  and  116  are arranged such that, when the lip ends  119  and  120  contact the flexible tube  110 , pressure is applied to the deck  116  through a contact point  117  on the exterior flange portion  104  and through a contact point  118  on the interior flange portion  105 . Preferably, the pressure is sufficient to form a seal between the contact point  117  and the deck  16  and to form another seal between the contact point  118  and the deck  16 . 
   As seen in  FIG. 9 , the unique structure of the gasket  100  having the lips  115 ,  116  enables the gasket  100  to be installed in any direction since the gasket  100  is symmetric relative to about a plane defined by the inner perimeter of the hole in the hull of the watercraft when the flexible member is disposed in the inner perimeter of the hole in the hull of the watercraft. 
   As described above, the unique structure of the air duct according to preferred embodiments of the present invention makes the assembly process much easier and less expensive than conventional devices, and reliably holds the flexible tube in place while also making it easy to assemble and disassemble, as desired. 
   It should be understood that the foregoing description is only illustrative of the present invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the present invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.