Abstract:
A watercraft has a compact construction and a water tight engine compartment. The air inside the engine compartment becomes warm due the radiating engine heat. This warming of the induction air reduces combustion efficiency, lower engine performance. An induction air cooling arrangement is provided to cool the air inside the engine compartment without using excess engine compartment space and not restricting induction airflow. The cooler provides the engine with cooler, denser air in order to improve combustion, therefore raising engine performance.

Description:
PRIORITY INFORMATION  
         [0001]    This application is based on and claims priority to Japanese Patent Application No. 2000-390254, filed Dec. 22, 2000, the entire contents of which is hereby expressly incorporated by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention generally relates to induction air cooling for watercraft. More particularly, the present invention relates to coolers, which use water to dissipate heat from induction air entering the engines of personal watercraft.  
           [0004]    2. Description of the Related Art  
           [0005]    Personal watercraft are a sporting type of watercraft. These watercraft are fairly compact in construction and have substantially water tight engine compartments in order to slow or prevent the ingress of water when capsized. Accordingly, the engine heats air inside the engine compartment, which is used by the engine for combustion. Such heating of the induction air reduces combustion efficiency, lowering engine performance.  
           [0006]    Conventionally the air inside such engine compartments has been cooled by means of an intercooler directly cooling the induction air or by a fan directly cooling the engine itself. The disadvantage of using an intercooler is that it restricts the airflow into the engine, lowering engine performance. The large amount of space required to mount a fan causes this cooling approach to likewise be a disadvantage.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention is a watercraft including a hull defining an engine compartment, an engine positioned within the engine compartment, and an induction system configured to guide air into the engine. The watercraft also includes a cooling system configured to cool at least one component within the engine compartment with water in which the watercraft can operate, and an induction air cooler configured to receive water from the cooling system to cool air flowing in the induction system.  
           [0008]    In accordance with another aspect of the invention a watercraft includes a hull defining an engine compartment, and an engine positioned within the engine compartment. An induction system is configured to guide air into the engine. The watercraft also includes a means for cooling air flowing in the induction system with water from a body of water in which the watercraft can operate.  
           [0009]    In accordance with yet another aspect of the present invention, a watercraft includes a hull defining an engine compartment. An engine is positioned within the engine compartment. An induction system is configured to guide air into the engine, and at least one induction air cooler is configured to use water as a cooling medium flowing inside the housing of the cooler and to thereby cool induction air coming into thermal communication with the outer surface of the cooler housing. The induction air cooler is placed adjacent to an inlet of the induction system. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    These and other features, aspects and advantages of the present invention will now be described with reference to the drawings of a preferred embodiment, which embodiment is intended to illustrate and not to limit the invention. The drawings comprise 7 figures.  
         [0011]    [0011]FIG. 1 is a partially sectioned, side elevational view of a personal watercraft arranged and configured in accordance with certain features, aspects and advantages of the present invention. Certain components have been illustrated with hidden lines and other components are not illustrated for clarity.  
         [0012]    [0012]FIG. 2 is a top plan view of the watercraft of FIG. 1. Certain components are illustrated with hidden lines, other components are illustrated with phantom lines and yet other components are not illustrated for clarity.  
         [0013]    [0013]FIG. 3 is a port side elevational view of an engine of the watercraft of FIG. 1 illustrating an induction air cooler.  
         [0014]    [0014]FIG. 4 is a top plan view of the engine shown in FIG. 3.  
         [0015]    [0015]FIG. 5 is a front elevational of the engine shown in FIG. 3.  
         [0016]    [0016]FIG. 6 is a simplified sectional view of the induction air cooler shown in FIG. 3.  
         [0017]    [0017]FIG. 7 is a partial cross-sectional rear elevational view of a modification of the watercraft shown in FIGS.  1 - 6 . A profile of a hull of the watercraft is shown schematically. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]    With reference to FIGS. 1 and 2, an overall configuration of a personal watercraft  10  and its engine  12  is described below. The watercraft  10  employs the internal combustion engine  12 , which is configured in accordance with a preferred embodiment of the present invention. The described engine configuration has particular utility for use within the watercraft, and thus, is described in the context of watercraft. The engine configuration also can be applied to other types of watercraft, such as, for example, small jet boats and other vehicles that can benefit from cooled induction air.  
         [0019]    With reference initially to FIG. 1, the watercraft  10  includes a hull  14  formed with a lower hull section  16  and an upper hull section or deck  18 . The lower hull section  16  and the upper hull section  18  preferably are coupled together to define an internal cavity  20 . A bond flange  22  defines an intersection of both of the hull sections  16 ,  18 . The illustrated upper hull section  14  preferably comprises a hatch cover  24 , a control mast  26  and a seat  28 , which are arranged generally in series from fore to aft.  
         [0020]    In the illustrated arrangement, a forward portion of the upper hull section  18  defines a bow portion  30  that slopes upwardly. An opening not shown can be provided through the bow portion  30  so the rider can access the internal cavity  20 . The hatch cover  24  can be detachably affixed (e.g., hinged) to the bow portion  30  to resealably cover the opening.  
         [0021]    The control mast  26  extends upwardly to support a handle bar  32 . The handle bar  32  is provided primarily for controlling the direction of the watercraft  10 . The handle bar  32  preferably carries other mechanisms, such as, for example, a throttle lever (not shown) that is used to control the engine output (i.e., to vary the engine speed).  
         [0022]    Foot areas  34  are defined on both sides of the seat  28  along a portion of the upper hull section  18 . The foot areas  34  are formed generally flat but may be inclined to provide a suitable drain configuration.  
         [0023]    A fuel tank  40  is positioned in the cavity  20  under the bow portion  30  of the upper hull section  18 . A duct preferably couples the fuel tank  40  with a fuel inlet port positioned at a top surface of the bow  30  of the upper hull section  18 . A closure cap  42  (see FIG. 1) closes the fuel inlet port to inhibit water infiltration.  
         [0024]    The engine  12  is disposed in an engine compartment defined, for instance, within the cavity  20 . The engine compartment preferably is located under the seat  28 , but other locations are also possible (e.g., beneath the control mast or in the bow). In general, the engine compartment can be defined within the cavity  20  by forward and/or rearward bulkheads. Other configurations, however, are possible.  
         [0025]    A pair of air ducts  43 ,  44  with respective duct openings  45 ,  47  are provided in the illustrated arrangement such that the air within the internal cavity  20  can be readily replenished or exchanged. The engine compartment, however, is substantially sealed to protect the engine  12  and other internal components from water.  
         [0026]    A jet pump unit  46  propels the watercraft  10 . Other types of marine drives can be used depending upon the application. The jet pump unit  46  preferably is disposed within a tunnel  48  formed on the underside of the lower hull section  16 . The tunnel  48  has a downward facing inlet  50  opening toward the body of water. A jet pump housing  52  is disposed within a portion of the tunnel  48 . Preferably, an impeller  53  is supported within the housing  52 .  
         [0027]    An impeller shaft  54  comprising one or more segments extends forwardly from the impeller and is coupled with a crankshaft  56  of the engine  12  by a suitable coupling member  58 . The crankshaft  56  of the engine  12  thus drives the impeller shaft  54 . The rear end of the housing  52  defines a discharge nozzle  57 . A steering nozzle  60  is affixed proximate the discharge nozzle  57 . The nozzle can be pivotally moved about a generally vertical steering axis. The steering nozzle  60  is connected to the handle bar  32  by a cable or other suitable arrangement so that the rider can pivot the nozzle  60  for steering the watercraft.  
         [0028]    With reference to FIGS. 3, 4, and  5 , the engine  12  in the illustrated arrangement operates on a two-stroke cycle combustion principal. The engine  12  includes a cylinder head member  62  to close respective upper ends of cylinder bores (not shown). The cylinder head member  62 , the cylinder bores and pistons (not shown) define combustion chambers (not shown). A lower cylinder block member or crankcase member  66  is attached to the lower end of a cylinder block  64  to close the respective lower ends of the cylinder bores. A crankshaft (not shown) is rotatably connected to the pistons through connecting rods (not shown).  
         [0029]    Engine mounts  68  preferably extend from both sides of the engine  12 . The engine mounts  68  can include resilient portions made of, for example, a rubber material. The engine  12  preferably is mounted on the lower hull section  16 , specifically, a hull liner, by the engine mounts  68  so that the engine  12  is inhibited from conducting vibration energy to the hull section  16 .  
         [0030]    An exhaust system delivers exhaust gases from the engine into an exhaust manifold  70  through three manifold channels  72 . The exhaust gases further travel through two exhaust expansion pipes,  74 , 76 , and through a water lock  78 . The water lock  78  is preferably located on the left side of the jet pump unit  46  and is designed to prevent the reverse flow of water from entering the engine  12 . The exhaust system includes a catalyst  80  for aiding in cleaning the discharged exhaust gases and a heat shield  82  to keep the exhaust generated heat from radiating into the internal cavity  20  of the engine compartment. The exhaust system continues through a rear exhaust pipe  84 , which communicates with the propulsion tunnel  48  and discharges the exhaust gases to the rear of the watercraft  10 .  
         [0031]    Water supplied under pressure through a coolant conduit  86  form the jet pump unit  46  is used to cool the exhaust as well as the engine itself A distribution conduit  88  disperses coolant to the exhaust manifold  70  through various ports  90  and further to the cylinder block  64  and cylinder head  62 . A bypass valve  92  allows the coolant to finally cool expansion pipes  74 ,  76  before being discharged out the back of the watercraft  10  along with the exhaust gas.  
         [0032]    An intake system comprising primary and secondary intake air boxes  94 ,  96  connected by an intake hose  98 , is preferably located in the available space between the two exhaust expansion pipes  74 ,  76 . The secondary air box  96  is directly connected to a series of carburetors  100  mounted with intake manifolds  110  to the engine block  64 . A resonator acting as an intake silencer  102  is attached to the intake hose  98  and assists as a reservoir for water in the intake system during capsizing. The water collected in the resonator  102  drains into the primary air box  94  and is further drained through a one-way valve  104  located in the primary air box  94  when the watercraft is returned to its original position.  
         [0033]    In order to further prevent water invasion into the engine  12 , a lower rim  106  of the primary air box outlet port is positioned higher than an upper rim  108  of a secondary air box inlet port. This arrangement aids in preventing water from entering the secondary air box  96  from the primary air box  94  when the watercraft  10  is returned to its upright position from a capsized position.  
         [0034]    With reference to FIG. 6, an induction air cooler  116  preferably is mounted in close vicinity to an inlet  114  located in the primary air box  94 . Preferably, the induction air cooler  116  is positioned such that at least some of the air entering the inlet  114  passes into thermal communication with the induction air cooler  116 , before flowing through the inlet  114 .  
         [0035]    The induction air cooler  116  is preferably made of an aluminum material and comprises a cooler housing  118  surrounding an internal coolant passage  120 . A coolant inlet port  122  communicating with the coolant passage  120  is located on the bottom of the cooler housing  118  and a coolant outlet  124  is located on top of the cooler housing  118 . Coolant is supplied to the inlet port  122  of the induction air cooler  116  through a coolant supply line  126 . A coolant drain line  128  drains the coolant from the induction air cooler  116  into the exhaust system or to the outside of the watercraft  10 .  
         [0036]    The induction air cooler  116  preferably includes a plurality of cooling fins  130 . The cooling fins  130  are constructed and fastened to the induction air cooler  116  in order to increase the surface area of the induction air cooler  116 , which increases the thermal conduction efficiency of the induction air cooler  116 . The cooling fins  130  preferably are placed in parallel with the flow of induction air entering the engine  10  which provides the additional benefit of not restricting the flow of the induction air and provides better thermal communication between the induction air and the cooling fins  130 .  
         [0037]    In operation, the induction air surrounding and passing by the induction air cooler  116  is cooled by the cooler  116 , thus providing the engine  10  with cooler, denser air improving engine performance. Where the air flows into thermal communication with the cooling fins  130 , the air is further cooled due to the increased surface area offered by the cooling fins  130 .  
         [0038]    The induction air cooler  116  can also be used to cool the entire engine compartment by mounting one or more induction air coolers  116  within the internal cavity  20  to dissipate the heat radiated from the engine  10  during operation creating cooler, denser air improving engine performance.  
         [0039]    With reference to FIG. 7, a four-stroke engine body  136  incorporating the air induction cooler  116  is described below. The engine body  136  in the illustrated arrangement operates on a four-stroke cycle combustion principal. With reference to FIG. 5, the engine body  136  includes a cylinder block  138  with four cylinder bores (not shown) formed side by side along a single inclined plane. The engine body  136 , thus, is an inclined L4 (in-line four cylinder) type.  
         [0040]    A cylinder head member  140  is affixed to the upper end of a cylinder block  138 . A crankshaft  142  is journaled inside the cylinder block  138 . The crankshaft  142  is rotatably connected to the pistons  144  through connecting rods  146 .  
         [0041]    The cylinder block  138  and the cylinder head member  140  together generally define the engine body  136 . The engine body  136  preferably is made of an aluminum-based alloy. In the illustrated embodiment, the engine body  136  is oriented in an engine compartment  134  to position the crankshaft  142  generally parallel to a central plane. Other orientations of the engine, of course, are also possible (e.g., with a transversely or vertically oriented crankshaft).  
         [0042]    The engine body  136  further includes an exhaust system  148  to discharge burnt charges, i.e., exhaust gases, from combustion chambers  150 . In the illustrated arrangement, the exhaust system  148  includes four exhaust ports  152  that generally correspond to, and communicate with, the combustion chambers  150 . The exhaust ports  152  preferably are defined in the cylinder head member  140 . Exhaust valves  154  preferably are provided to selectively open and close the exhaust ports  152 . An exhaust camshaft  156  can be provided to operate the exhaust valves  154 .  
         [0043]    The engine body  136  preferably includes an air induction system to introduce air to the combustion chambers  150 . In the illustrated embodiment, an air induction system  158  includes four air intake ports  160  defined within the cylinder head member  140 , which ports  160  generally correspond to and communicate with the four combustion chambers  150 . Other numbers of ports can be used depending upon the application. Intake valves  162  are provided to open and close the intake ports  160  such that flow through the ports  160  can be controlled. An intake camshaft  164  can be used to control the intake valves  162 .  
         [0044]    The air induction system  158  also includes an air intake box  164  for smoothing intake airflow and acting as an intake silencer. The intake box  164  in the illustrated embodiment is generally rectangular and, along with an intake box cover  166 , defines a plenum chamber  168 . The intake box cover  166  can be attached to the intake box  164  with a number of intake box cover clips  170  or any other suitable fastener. Other shapes of the intake box of course are possible, however the plenum chamber preferably is as large as possible while still allowing for positioning within the space provided in the engine compartment. Air is introduced into the plenum chamber  168  through a pair of air inlet ports  172  and a filter  174 .  
         [0045]    With continued reference to FIG. 7, in the illustrated arrangement, the throttle bodies  176  slant toward the port side relative to a center axis of the engine body  136 . Respective top ends  178  of the throttle bodies  176 , in turn, open upwardly within the plenum chamber  168 . Air in the plenum chamber  168  thus is drawn through the throttle bodies  176  and the intake ports  160  into the combustion chambers  150  when negative pressure is generated in the combustion chambers  150 . The negative pressure is generated when the pistons  144  move toward the bottom dead center position from the top dead center position during the intake stroke.  
         [0046]    The induction air cooler  116  is preferably mounted directly in front of the air inlet ports  172  such that air flowing into the inlet ports  172  first pass into thermal communication with the induction air cooler  116 . Alternatively, or in addition, an induction air cooler  116  can be positioned within the air box  164  itself. Additionally, only one or a plurality of induction air coolers  116  can be provided in the engine compartment  134  in order to cool the induction air entering the engine improving engine performance. A plurality of air induction coolers  116  may also be used in conjunction with one another in order to more efficiently cool the air in the entire engine compartment  134  allowing for cooler induction air improving engine performance.  
         [0047]    The illustrated engines merely exemplify one type of engine on which various aspects and features of the present invention can be used. Engines having a different number of cylinders, other cylinder arrangements, other cylinder orientations (e.g., upright cylinder banks, V-type, and W-type), and operating on other combustion principles (e.g., crankcase compression two-stroke, diesel, and rotary) are all practicable.  
         [0048]    Of course, the foregoing description is that of certain features, aspects and advantages of the present invention to which various changes and modifications may be made without departing from the spirit and scope of the present invention. A watercraft need not feature all objects of the present invention to use certain features, aspects and advantages of the present invention. The present invention, therefore, should only be defined by the appended claims.