Abstract:
A personal watercraft can be rotated in a correct direction of rotation when the personal watercraft has been overturned, and can thereby be restored to a normal, upright position. The personal watercraft includes a vessel body, an engine, and an exhaust system. The exhaust system includes a muffler, disposed on a first side of the vessel body, and an exhaust pipe connected to the muffler and formed in an inverted U-shape. During operation of the engine, exhaust gas passes through the inverted-U-shaped exhaust pipe and is subsequently discharged to the outside environment via an exhaust port. The exhaust port is disposed on a second side of the vessel body opposite the first side. The vessel body has a hollow water-receiving portion formed therein, on the second side thereof. The water-receiving portion is adapted to be submerged under water when the personal watercraft is overturned in a body of water.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present invention claims priority under 35 USC 119 based on Japanese patent application No. 2004-272201, filed on Sep. 17, 2004. The subject matter of this priority document is incorporated by reference herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a personal watercraft incorporating structure for facilitating capsize recovery, and to a method of restoring an overturned watercraft to a normal, upright position. More particularly, the present invention relates to a personal watercraft and to a method of use thereof, in which the watercraft includes an inverted-U-shaped exhaust pipe disposed midway within an engine exhaust system, and further wherein the watercraft body includes specialized structure to assist a user in righting the watercraft, in the event that it overturns during operation.  
         [0004]     2. Description of the Background Art  
         [0005]     It is well known to provide a personal watercraft, or small planing boat, with an exhaust system for the driving engine thereof. It is also well known to incorporate a muffler in such an exhaust system, to which a substantially inverted-U-shaped exhaust pipe is connected. A personal watercraft having this configuration discharges exhaust gas in the muffler out through the exhaust pipe via an exhaust port. Such an exhaust system is disposed, for example, in Japanese Laid-Open Patent publication No. 2002-2593.  
         [0006]     The art disclosed in Japanese Laid-Open Patent publication No. 2002-2593 will be described below with reference to  FIG. 6 .  FIG. 6  illustrates the basic construction of a conventional prior art personal watercraft exhaust system.  
         [0007]     As shown in  FIG. 6 , a prior art personal watercraft  100  includes an engine  101  that rotates a drive shaft  102  for driving a jet propeller  103 . The personal watercraft  100  is propelled as the boat  100  expels water drawn in from a front end portion  103   a  of the jet propeller  103  rearwardly from a rear end portion  103   b  as a jet of water.  
         [0008]     The personal watercraft  100  includes a substantially inverted-U-shaped exhaust hose  105  disposed midway within an exhaust system of the engine  101 . The substantially inverted-U-shaped exhaust hose  105  functions to prevent water that has entered the exhaust hose  105  from entering into the engine  101  through a side thereof.  
         [0009]     For example, if the personal watercraft  100  overturns in the water, an exhaust port of the exhaust hose  105  opens upwardly, making it likely that water will enter the exhaust hose  105  via the exhaust port. The water that has entered the exhaust hose  105  stays at a vertex portion  105 a of the exhaust hose  105  formed into the substantially inverted-U shape, and does not enter the engine  101 .  
         [0010]     When the overturned personal watercraft  100  is to be restored to a normal, upright position, it is necessary to discharge the water remaining in the vertex portion  105   a  from the exhaust port. This is accomplished by turning the personal watercraft  100  such that the exhaust port is located downwardly.  
         [0011]     To ensure that the water remaining in the vertex portion  105   a  is discharged properly, the personal watercraft  100  is marked, at a rear end portion thereof, with the proper direction of rotation of the overturned personal watercraft  100  when the overturned personal watercraft  100  is to be restored to a normal, upright position. Restoring the overturned personal watercraft  100  to the normal, upright position is, however, performed in a submerged condition. Therefore, it is difficult and time-consuming for an operator to determine the proper direction of rotation that is given at the rear end portion of a vessel body  100 .  
         [0012]     It is therefore an object of the present invention to provide a personal watercraft that can be swiftly rotated in a correct direction of rotation when the personal watercraft, that has been overturned, is to be restored to a normal, upright position.  
       SUMMARY  
       [0013]     In accordance with one aspect of the present invention, there is provided a personal watercraft, including an exhaust system for an engine mounted in a vessel body. The exhaust system includes a muffler and an exhaust pipe connected to the muffler. The exhaust pipe extends upwardly a short distance, and then curves to extend downwardly to be formed into a substantially inverted U-shape. The exhaust gas in the muffler is discharged to the outside of the personal watercraft by way of the inverted-U-shaped exhaust pipe from an exhaust port of the exhaust pipe. The personal watercraft according to the first aspect of the present invention is characterized in the following points. Specifically, the muffler is disposed on one side (a first side) of the vessel body, and the exhaust port is disposed on the other side (a second, opposed side) of the vessel body, relative to the muffler. Further, the other side of the vessel body includes a water-receiving space capable of taking in water, the water-receiving space being submerged under water when the personal watercraft is in an overturned state.  
         [0014]     When the personal watercraft is in an overturned state, the water-receiving space is submerged under water and water flows into the water-receiving space. Water collects in the water-receiving space and buoyancy on the second side of the vessel body becomes smaller than that on the first side thereof. Accordingly, the personal watercraft is inclined so that the second side of the vessel body is lowered.  
         [0015]     Consider herein an attempt to restore the overturned personal watercraft to a normal, upright position. It is readily understood that restoration of the overturned personal watercraft to the normal, upright position is more easily accomplished if the lowered side is further lowered downwardly. It is therefore considered that an operator who makes the aforementioned attempt will normally rotate the personal watercraft in the direction of further lowering the second side, which has been previously in a lowered position, in his or her attempt to restore the personal watercraft to the normal, upright position.  
         [0016]     Accordingly, in the first aspect of the present invention, the direction in which the second side, which has been previously lowered, is further lowered, is regarded as the correct direction of rotation. This allows the operator to swiftly rotate the personal watercraft in the correct direction without having to check the direction of rotation marked on the vessel body. Moreover, the rotation in the correct direction causes the muffler, disposed on the first side of the vessel body, to be raised and the exhaust port to be lowered. The water collected at a vertex portion of the substantially inverted-U-shaped exhaust pipe flows toward the side of the exhaust port, and is drained out of the personal watercraft from the exhaust port.  
         [0017]     Pursuant to another aspect of the present invention, the water-receiving space is arranged so as to be located above the water, and to discharge water that has been taken therein when the personal watercraft is in a normal, upright position.  
         [0018]     When the personal watercraft is in the normal, upright position, the water-receiving space is located above the water, and taken-in water discharges from the space. This allows a weight balance in a width direction of the personal watercraft to be maintained in equilibrium when the personal watercraft is normally operated.  
         [0019]     According to the first aspect of the present invention, the correct direction of rotation of the personal watercraft is defined to be the direction of further lowering the other, second side that has been previously lowered. This provides the advantage that the operator can restore the personal watercraft to the normal, upright position by swiftly rotating the personal watercraft in the correct direction.  
         [0020]     According to the second aspect of the present invention, when the personal watercraft is in the normal, upright position, the water-receiving space discharges water that has been taken therein. This provides the advantage that the personal watercraft can be propelled in a preferable condition by maintaining the weight balance in the width direction of the personal watercraft in equilibrium.  
         [0021]     Modes for carrying out the present invention are explained below by reference to an embodiment of the present invention shown in the attached drawings. The above-mentioned object, other objects, characteristics and advantages of the present invention will become apparent form the detailed description of the embodiment of the invention presented below in conjunction with the attached drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  is a side elevational view of a personal watercraft according to a preferred embodiment of the present invention, showing an exhausting system mounted within the vessel body rearward of an engine.  
         [0023]      FIG. 2  is a cross-sectional view of the personal watercraft of  FIG. 1  as viewed from the rear, showing the muffler mounted on a left side of the vessel body, the inverted U-shape of the exhaust pipe, and the exhaust port opening into an upper surface of the pump chamber.  
         [0024]      FIG. 3 ( a ) is a cross-sectional view of the personal watercraft of  FIG. 1  as viewed from the rear, showing the personal watercraft in an overturned state and showing water flowing into the water-receiving space formed on the right side of the vessel body, via two openings formed in the deck.  
         [0025]      FIG. 3 ( b ) is a cross-sectional view of the personal watercraft of  FIG. 3   a  as viewed from the rear, showing personal water craft in an inclined orientation wherein the water-filled and less buoyant right side of the vessel is lower in the water than the left side of the vessel.  
         [0026]      FIG. 4 ( a ) is a rear perspective view of an operator applying force to one side of the exterior of the vessel body of the personal watercraft of  FIG. 3   a  to cause a rotation of the vessel body in the direction of the arrow c.  
         [0027]      FIG. 4 ( b ) is a cross-sectional view of the personal watercraft of  FIG. 3   a  as viewed from the rear, showing the personal watercraft in a partially-righted orientation in which the water accumulated within the U-shaped exhaust pipe flows toward the exhaust port rather than the muffler as a result of rotation of the vessel body in the direction of arrow c.  
         [0028]      FIG. 5  is a cross-sectional view of the personal watercraft of  FIG. 3   a  as viewed from the rear, showing the personal watercraft restored to the normal, upright position, and showing water flowing outward from the water-receiving space via a lower opening formed in the deck.  
         [0029]      FIG. 6  is an isolated view of a prior art exhaust system for a personal watercraft. 
     
    
     DETAILED DESCRIPTION  
       [0030]     A selected illustrative embodiment of the invention will now be described in some detail, with reference to the drawings. It should be understood that only structures considered necessary for clarifying the present invention are described herein. Other conventional structures, and those of ancillary and auxiliary components of the system, are assumed to be known and understood by those skilled in the art. For the purpose of this specification, “front,” “rear,” “left,” and “right” denote corresponding directions as viewed from an operator of a personal watercraft. In addition, “Fr” denotes forward, “Rr” denotes rearward, “L” denotes leftward, and “R” denotes rightward.  
         [0031]      FIG. 1  is a side elevational view of a personal watercraft  10  according to a preferred embodiment of the present invention. The personal watercraft  10  according to the preferred embodiment of the present invention includes a vessel body  11 , a fuel tank  13 , an engine  14 , a pump chamber  16 , and a water jet propeller  17 . The fuel tank  13  is disposed at a front portion  12  of the vessel body  11 . The engine  14  is disposed rearward of the fuel tank  13 . The pump chamber  16  is disposed at the stem (the rear portion of the vessel body)  15  located rearward of the engine  14 . The water jet propeller  17  is disposed inside the pump chamber  16 . An impeller  17   a  of the water jet propeller  17  is connected to the engine  14  via a drive shaft  18 .  
         [0032]     The personal watercraft  10  further includes a steering nozzle  21 , a steering handlebar  22 , and a seat  23 . The steering nozzle  21  is disposed rearward of the water jet propeller  17  and is mounted swingably to the right and left via upper and lower pins  19 ,  19 . The steering handlebar  22  swingably operates the steering nozzle  21  and is disposed above the fuel tank  13 . The seat  23  is disposed rearward of the steering handlebar  22 .  
         [0033]     According to the personal watercraft  10 , the engine  14  rotates the drive shaft  18 , which, in turn, rotates the impeller  17   a.  As the impeller  17   a  rotates, water is drawn in to a water flow duct  26  through an intake port  25  in a hull bottom  24 . The drawn-in water is further taken in to the water jet propeller  17  via the water flow duct  26 . The water thus taken in the water jet propeller  17  is expelled rearwardly from the steering nozzle  21 . The personal watercraft  10  is thereby propelled.  
         [0034]      FIG. 2  is a cross-sectional view of the personal watercraft  10  according to the preferred embodiment of the present invention. The personal watercraft  10  includes an exhaust system  31  for the engine mounted in the vessel body  11 . The exhaust system  31  includes a muffler  32 . An exhaust pipe  33  connected to the muffler  32  is formed into a substantially inverted U-shape. Specifically, the exhaust pipe  33  extends from the muffler  32  upwardly a short distance, and then curves to extend downwardly. The exhaust gas in the muffler  32  is discharged to the outside of the vessel body  11  by way of the exhaust pipe  33 , through an exhaust port  34  of the exhaust pipe  33 .  
         [0035]     In accordance with the personal watercraft  10  according to the preferred embodiment of the present invention, the muffler  32  is disposed in a left-hand side space (one side of the vessel body)  36  of the vessel body  11 . The exhaust port  34 , on the other hand, is disposed on a right side portion (the other side of the vessel body)  38  of the vessel body  11  relative to the muffler  32 . Specifically, the exhaust port  34  is disposed generally at a center  37  of the vessel body  11 . There is provided a water-receiving portion  40  capable of taking in water at the right side portion  38  of the vessel body  11 . The water-receiving portion  40  is submerged under water when the personal watercraft  10  is in an overturned state.  
         [0036]     The exhaust system  31  is constructed as follows. Specifically, the muffler  32  is connected to the engine  14  (see  FIG. 1 ) via an exhaust pipe (not shown) or the like. The substantially inverted-U-shaped exhaust pipe  33  is then connected to the muffler  32 . A discharge side end portion  41  of the exhaust pipe  33  is passed through a ceiling wall  42  of the pump chamber  16 . The exhaust port  34  at the discharge side end portion  41  is then made to face an inside of the pump chamber  16 .  
         [0037]     The vessel body  11  includes a hull  46  and a deck  47 . The hull  46  forms a lower half section of the vessel body  11 . The deck  47  forms an upper half section of the vessel body  11 . A peripheral edge  47   a  of the deck  47  is bonded to a peripheral edge  46 a of the hull  46 . The deck  47  includes left and right foot portions  48 ,  49 . A partition wall  51  extends substantially horizontally between the hull  46  and the deck  47  at a point near the right foot portion  49 . The partition wall  51  includes a bent tab  52  at an outer end portion thereof.  
         [0038]     The bent tab  52  is bonded to a right side wall  53  of the hull  46 . A water-receiving space  55  is thereby defined by the right side wall  53  of the hull  46 , a right side wall  54  of the deck  47 , and the partition wall  51  of the deck  47 . The right side wall  54  of the deck  47  is provided with an upper through hole  57  at an upper portion of the water-receiving space  55 . The right side wall  54  of the deck  47  is also provided with a lower through hole  58  at a lower portion of the water-receiving space  55 . Specifically, the right side wall  53  of the hull  46 , the right side wall  54  of the deck  47 , and the partition wall  51  of the deck  47  form the water-receiving portion  40 .  
         [0039]     The water-receiving portion  40  is submerged under water in an overturned state. The water-receiving portion  40  is thus designed to take water in the water-receiving space  55  in the overturned state through both the upper and lower through holes  57 ,  58 . In addition, the water-receiving portion  40  is arranged so as to be located above a water level (above the water) when the personal watercraft  10  is placed into a body of water and is oriented in a normal, upright position. The water-receiving portion  40  is further arranged such that water taken in the water-receiving space  55  is discharged from the lower through hole  58  to the outside when the personal watercraft  10  is in the normal position.  
         [0040]     A plate  61  is mounted on an interior surface of the hull  46 . Five floating bodies  62 , formed, for example, of a foam material, are disposed in a space between the hull  46  and the plate  61 . In addition, there is disposed a left floating body  65  in a space defined by a left end portion  61   a  of the plate  61 , a left side wall  63  of the hull  46 , and a left side wall  64  of the deck  47 . Further, a right floating body  66  is disposed in a space defined by a right end portion  61   b  of the plate  61 , a lower portion of the right side wall  53  of the hull  46 , the right foot portion  49  of the deck  47 , and the partition wall  51  of the deck  47 .  
         [0041]     In operation, the personal watercraft  10  will be described with reference to FIGS.  3 ( a ),  3 ( b ),  4 ( a ),  4 ( b ), and  5 . FIGS.  3 ( a ) and  3 ( b ) are views illustrating an exemplary case, in which the personal watercraft  10  according to the preferred embodiment of the present invention is overturned. Referring to  FIG. 3 ( a ), when the personal watercraft  10  is in an overturned state, the water-receiving portion  40  is located below the surface  68  of the water, or more specifically, is submerged under water. Since the water-receiving portion  40  is submerged under water, water flows into the water-receiving space  55  through the upper and lower through holes  57 ,  58  as shown by arrows a. It is to be noted herein that water  69  can enter the exhaust pipe  33  through the exhaust port  34 , since in the overturned orientation, the exhaust port opens upwardly. The water  69  that has entered the exhaust pipe  33  collects at a vertex portion  33   a  of the exhaust pipe  33 .  
         [0042]     Referring to  FIG. 3 ( b ), water  71  collects in the water-receiving space  55 . This makes the buoyancy at a right side portion  1  a of the vessel body  11  less than the buoyancy at a left side portion  11   b  of the vessel body  11 . Consequently, the personal watercraft  10  is inclined as shown by an arrow b to a condition, in which the right side portion  11   a  is lowered relative to the left side portion  11   b.    
         [0043]     FIGS.  4 ( a ) and  4 ( b ) are views illustrating an exemplary case, in which the personal watercraft according to the preferred embodiment of the present invention is to be restored to a normal, upright position. Referring to  FIG. 4 ( a ), a sign plate  73  is disposed at a portion  11   c  in the rear on the left of the vessel body  11 . The sign plate  73  indicates the correct direction of rotation to restore an overturned personal watercraft  10  to a normal, upright position. The correct direction of rotation is indicated, for example, by an arrow  74 . The arrow  74  indicates a rotation through which the right side portion  11   a  is to be lowered relative to the left side portion  11   b.    
         [0044]     Disposing the sign plate  73  at the portion  11   c  in the rear on the left of the vessel body  11  allows the marking plate  73  to be located above the water surface  68 , even when the personal watercraft  10  is inclined to a position in which the right side portion  11   a  of the personal watercraft  10  is lowered.  
         [0045]     When attempting to restore the overturned personal watercraft  10  to a normal, upright position, an operator  76  verifies the direction of rotation by checking the sign plate  73 . As instructed by the marking plate  73 , the operator  76  rotates the personal watercraft  10  as shown by an arrow c in the direction of further lowering the right side portion  11   a,  which has been previously been lowered as a result of taking in water within the water-receiving space  55 .  
         [0046]     As described above, the operator  76  brings the overturned personal watercraft  10  to a normal, upright position by swiftly rotating the personal watercraft  10  in the correct direction which is the direction of further lowering the right side portion  11   a,  which has been previously been lowered as a result of taking in water within the water-receiving space  55 .  
         [0047]     It is to be noted herein that, since the right side portion  11   a  of the personal watercraft  10  has been in the lowered position when the overturned personal watercraft  10  is to be restored to the normal, upright position, it is more likely that the personal watercraft  10  will be brought to the normal position easily by further lowering the right side portion  11   a  than rotating the personal watercraft  10  in the other direction. Accordingly, it is considered that the operator  76  will normally rotate the personal watercraft  10  in the direction of further lowering the right side portion  11   a  in his or her attempt to restore the personal watercraft  10  to the normal, upright position.  
         [0048]     Accordingly, even if the operator  76  is not aware of the correct direction of rotation, the operator  76  will rotate the personal watercraft  10  in the direction of further lowering the right side portion  11   a.  As a result, the operator  76  can restore the personal watercraft  10  to the normal, upright position by swiftly rotating the personal watercraft  10  in the correct direction.  
         [0049]     Referring to  FIG. 4 ( b ), rotating the personal watercraft  10  in the direction of the arrow c such that the right side portion  11   a  is lowered causes the left side portion  11   b  of the vessel body  11  to be raised. As the muffler  32  moves upwardly, the exhaust port  34  moves downwardly. Consequently, the water  69  that has collected at the vertex portion  33   a  of the substantially inverted-U-shaped exhaust pipe  33  moves toward the side of the exhaust port  34 .  
         [0050]      FIG. 5  is a view illustrating an exemplary case, in which the personal watercraft according to the preferred embodiment of the present invention has been restored to the normal, upright position. Bringing the personal watercraft  10  to the normal, upright position causes the exhaust port  34  to face downwardly, thus allowing the water  69  (see  FIG. 4 ( b )) in the exhaust pipe  33  to be discharged to the pump chamber  16  from the exhaust port  34  as shown by an arrow d.  
         [0051]     Further, with the personal watercraft  10  in the normal, upright position, the water-receiving portion  40  is located above the water surface  68 . Accordingly, the water  71  that had been taken in the water-receiving space  55  is drained naturally by its own weight to the outside by way of the lower through hole  58 , as shown by an arrow e. This permits a weight balance in a width direction of the personal watercraft  10  to be maintained in equilibrium when the personal watercraft  10  is operated. The personal watercraft  10  can thus be propelled in a favorable condition.  
         [0052]     While the present invention has been described in the preferred embodiment, in which the muffler  32  is disposed in the left-hand side space  36  of the vessel body  11  and the water-receiving portion  40  is disposed at the right side portion  38  of the vessel body  11 , it should be apparent to those skilled in the art that the arrangement is not limited thereto. The same effect can still be achieved by disposing the muffler  32  in a right-hand side space of the vessel body  11  and the water-receiving portion  40  at a left side portion of the vessel body  11 .  
         [0053]     Further, while the present invention has been described in the preferred embodiment, in which the water  71  taken in the water-receiving space  55  is subjected to natural drain of water through the lower through hole  58  with the personal watercraft  10  in the normal, upright position. It should be apparent to those skilled in the art that the arrangement is not so limited. It is perfectly possible to use discharge means, such as, for example, a bilge pump or the like for discharge the water. The bilge pump herein mentioned is a pump for drawing and discharging bilge (bilge water that collects at a hull bottom).  
         [0054]     The present invention can be preferably applied to a personal watercraft having an inverted-U-shaped exhaust pipe in midway in an engine exhaust system, through which an exhaust gas is discharged out by way of an exhaust port.  
         [0055]     While a working example of the present invention has been described above, the present invention is not limited to the working example described above, but various design alterations may be carried out without departing from the present invention as set forth in the claims.