Patent Publication Number: US-6213825-B1

Title: Fuel injection system for small watercraft

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a small watercraft and more particularly to an improved fuel injection arrangement for such watercraft. 
     It is well known that two cycle engines have wide applicability for a number of uses where small size, simple construction and high specific output are desired. A typical example of such applications is as the power plant for a type of water vehicle referred to generally as a “personal watercraft.” 
     Personal watercraft are watercraft that are relatively sporting in nature and that are designed primarily to be operated by a single operator who may carry only a few passengers with him. Frequently, the operator and passenger are seated in straddle fashion and when a plurality of passengers are carried, they sit in tandem. These types of watercraft are quite compact and thus, require compact propulsion systems including the engine. 
     However, because of environmental concerns and some difficulties in obtaining good exhaust emission control, power sources other than two cycle engines are being considered. However, if the efficiency of a two-cycle engine can be improved by an expedient such as fuel injection, and particularly direct fuel injection, then the replacement with four cycle engines may not be necessary. 
     Because of the compact nature of these watercraft and particularly their engine compartment and the access thereto, the provision of fuel injection systems presents some problems. This is particularly true with direct fuel injection systems wherein the fuel injector injects directly into the combustion chamber of the engine. Such arrangements position the fuel injector generally in the area of the cylinder head and thus, place it in an area where it may be exposed to damage or water which could deteriorate its performance, particularly if it is electrically operated. 
     On the other hand, it is desirable if the engine is mounted so that the injector can be easily accessed for service, but this places it is in a position where it may be inadvertently struck or where water may be able to contact it. 
     It is, therefore, a principal object of this invention to provide a direct cylinder fuel injection engine for use in personal watercraft. 
     It is a further object of this invention to provide a personal watercraft having a direct cylinder injection system where the injector is readily accessible for servicing but is protected by other components of the engine from damage and water. 
     SUMMARY OF THE INVENTION 
     This invention is adapted to be embodied in a personal watercraft that is comprised of a hull that defines a rider&#39;s area for accommodating a rider and not more than three passengers. An engine compartment is formed in the hull. An internal combustion engine is supported within the engine compartment and drives a hull watercraft propulsion device for propelling the hull through a body of water. A fuel injector is supported in an upper part of the engine for injecting fuel directly into a combustion chamber thereof. An air induction system is provided for delivering an air charge to combustion chamber. An exhaust system is also provided for discharging a burnt charge from the combustion chamber. At least one portion of one of the induction and exhaust systems is positioned at a point that extends vertically above and in proximity to the fuel injector for protecting the fuel injector without interfering with its serviceability access. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a personal watercraft, with a portion broken away, and showing a first embodiment of the invention. 
     FIG. 2 is an enlarged side elevational view of the watercraft engine, with portions broken away and shown in section, and with certain of the auxiliaries shown schematically. 
     FIG. 3 is a cross-sectional view of the watercraft taken along the line  3 — 3  of FIG.  1 . 
     FIG. 4 is a partial side elevational view, in part similar to FIG. 2, and shows two other alternate embodiments of the invention. 
     FIG. 5 is a partial cross-sectional view, in part similar to FIG. 3, and shows another embodiment of the invention. 
     FIG. 6 is a partial side elevational view, in part similar to FIGS. 2 and 4, and shows yet another embodiment of the invention. 
     FIG. 7 is a cross-sectional, in part similar to FIG. 3 but shows the embodiment of FIG.  6 . 
     FIG. 8 is a cross-sectional, in part similar to FIGS. 3,  5  and  7  and shows a still further embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     Referring now in detail to the drawings and first to the embodiment of FIGS. 1-3, a personal watercraft constructed in accordance with this embodiment of the invention is identified generally by the reference numeral  11 . The personal watercraft  11  is comprised of a hull assembly  12  that is comprised primarily of a lower hull part  13  and an upper, main hull or deck part  14 . These hull parts  13  and deck part  14  may be formed from a suitable material such as a molded fiberglass reinforced resin or the like. These parts are secured together around their outer periphery to form a gunnel  15  in a suitable manner. 
     A control mast  16  is provided at the forward part of the deck  14  in front of a seat assembly, indicated generally at  17 . This seat assembly  17  is mounted on a raised portion  18  of the deck and defines in major part the rider&#39;s area for the watercraft. A pair of depressed foot areas  20  are disposed on opposite sides of the seat  17  so that the rider may place his feet in these foot areas seated in straddled fashion on the seat  17 . The rider operator is disposed immediately behind the mast  16 . He may carry up to the three passengers behind him on the seat, seated in tandem fashion. 
     The inner portion of the hull assembly  12  defines an engine compartment  19  which is formed in major part beneath the seat  17 . An internal combustion engine  21  is mounted in this engine compartment in a suitable manner. This mounting may include a pair of elastic isolators  22  (FIG. 3) that are mounted on pedestals  23  of the hull inner part. The internal construction of the engine  21  will be described in more detail shortly. 
     A hatch area is provided at the forward portion of the deck  14  and may contain a storage compartment having a removable lower wall. A fuel tank  24  that contains fuel for the engine  21  is disposed in this area. Fuel is supplied from the fuel tank  24  to the engine  21  in a manner which will also be described. 
     The engine  21  is mounted in the engine compartment  19  so that its crankshaft  25  rotates about a generally longitudinally extending axis. This crankshaft is coupled by means of a coupling  26  to a propulsion unit, indicated generally by the reference numeral  27  and specifically an impeller shaft  28  of a jet propulsion unit, indicated generally by the reference numeral  29 . 
     The jet propulsion unit  29  is mounted in a tunnel area  31  formed in the under part of the hull portion  13  beneath the rear part of the raised seat portion  18  and rearwardly of a bulkhead  32  that provides a water barrier at the rear end of the engine compartment  19 . 
     Although other types of propulsion systems may be employed, conveniently the jet propulsion unit  29  is comprised of an outer housing that defines a water inlet tract  33  that originates at downwardly facing water inlet opening formed in the undersurface of the hull part  13 . 
     An impeller  34  is affixed to the impeller shaft  28  within this jet propulsion unit  29  and draws the water in through the inlet tract  33  and discharges it rearwardly through a discharge nozzle  35 . A steering nozzle  36  is pivotally supported about a vertically extending axis on the discharge nozzle  35  and is pivoted by the mast  16  so as to change the direction of travel of the watercraft  11  in a manner well known in this art. 
     Referring now primarily to FIGS. 2 and 3, the construction of the engine  21  will be described in more detail. The engine  21  is, in the illustrated embodiment, of the two-cylinder inline type and operates on a two-stroke crankcase compression principle. Although the invention is described in conjunction with an engine having this number of cylinders, it will be readily apparent that the invention can be utilized with engines having a varying number of cylinders and having varying cylinder configurations. Certain facets to the invention may also be employed in conjunction with four-cycle engines, but for the reasons aforenoted the invention has particular utility with two-cycle engines. 
     The engine  21  therefore includes a cylinder block  37  in which, in this embodiment, two vertically extending cylinder bores  38  are formed. The lower ends of the cylinder bores are closed by means of a crankcase member  39  that is detachably connected to the underside of the cylinder block  37  in a suitable manner. The crankshaft  25  is suitably journalled within a crankcase chamber formed primarily by the crankcase member  39 . 
     The opposite ends of the cylinder bores  38  are closed by a cylinder head assembly  41  that is detachably connected to the cylinder block  37  in any suitable manner. 
     The cylinder bores  38  define respective axes  42  that extend vertically in this embodiment and pistons  43  are supported for reciprocation in these cylinder bores  38  along the axes  42 . The pistons  43  are connected by means of piston pins (not shown) to the small ends of connecting rods  44 . The big ends of these connecting rods  44  are, in turn, journaled on the crankshaft  25  in any suitable manner. 
     As is typical with two-cycle, crankcase compression engines, the sections of the crankcase chamber associated with each cylinder bore  38  are sealed from each other. To this end, the crankshaft  25  may be formed with or cooperate with sealing members  45  which, in effect, form a part of this seal. 
     One side of the engine  21  may be considered to be the intake side and an induction system, indicated generally by the reference numeral  46 , supplies an intake air charge to this side of these crankcase chamber sections in a manner which will be described shortly. This induction system includes an air inlet device  47  that is disposed at a relatively high position on one side of the engine, for a reason which will become apparent. 
     This inlet device  47  may include a suitable silencing mechanism and has a downwardly facing air inlet opening  48  that is disposed between one side of the cylinder block  37  and a throttle body  49  which receives the intake air from the intake device  47 . Thus, the air that is drawn into the induction system will be shielded and the likelihood of picking up water from the bilge will be substantially precluded. 
     A throttle valve is positioned within the throttle body  49  and is controlled by means of a throttle control which is, in turn, operated by a remotely located throttle control. This throttle control may be mounted on the steering mast  16 . 
     Air at a volume controlled by the position of the throttle valve in the throttle body  49  will enter into an intake manifold  53  which communicates with intake ports  54  formed in the crankcase member  39 . Each intake port  54  serves a respective one of the crankcase chamber afore referred to. 
     A read-type check valve assembly  55  is provided in each intake port  54 . This read-type check valve  55  permits air to flow into the respective crankcase chambers as the pistons  43  are moving upwardly in their respective cylinder bores. When the pistons  43  move downwardly, this charge will be compressed in the crankcase chambers and the read-type check valves  55  will close to preclude reverse flow through the induction system  46 . 
     The charge which is compressed in the crankcase chambers will be transferred through a scavenging system (not shown) of any type known in this art to combustion chambers that are formed by the piston  43 , the cylinder bores  38  and recesses  56  formed on the underside of the cylinder head assembly  41 . 
     Fuel injectors, of any suitable type and indicated by the reference numeral  57 , are mounted in the cylinder head assembly  41  in a location as will be described and spray a fuel charge directly into the combustion chamber. The timing and duration of fuel injection can be controlled by any suitable control strategy. The manner in which fuel is delivered to the fuel injector  57  from the fuel tank  54  will be described shortly. 
     Thus, a fuel air charge will be formed in the combustion chamber. This charge is then fired by spark plugs  58  that are mounted in the cylinder head assembly at a location which will also be described. The spark plugs are fired by a suitable ignition circuit, which can be provided with electrical power from a magneto generator  59  fixed to the forward end of the crankshaft  25  and covered by a cover  61 . This is the end opposite that which the coupling  26  couples the crankshaft  25  to the impeller shaft  28 . 
     The ignited charge will bum and expand so as to drive the pistons  43  downwardly in the cylinder bores  38  and effect rotation of the crankshaft  25 . 
     Exhaust ports  59  are formed in the cylinder block  37  on the opposite side from the induction system  46 . These exhaust ports  59  communicate with an exhaust system, indicated generally by the reference numeral  61 , for discharging the exhaust gases to the atmosphere through a path which will now be described. 
     First, the exhaust system includes an exhaust manifold assembly, indicated generally by the reference numeral  62 , which has a collector portion  63  having a collector section  64  that receives exhaust gases from the exhaust ports  59 . This exhaust manifold  62  is affixed to an exhaust side  65  of the cylinder block  37  in a suitable manner. 
     The exhaust gases collected by the manifold  63  are passed forwardly through an upwardly curved section, as best seen in FIG. 1, to an expansion chamber device, indicated by the reference numeral  64 , and which extends on a relatively high location on the opposite side of the cylinder head from the intake device  47 . As a result of this and as clearly seen in FIGS. 2 and 3, the fuel injectors  55  are shrouded at both sides by the induction system  46  and the exhaust system  62 . Specifically, it is shrouded by the air inlet device  47  and the expansion chamber device  64  both of which are located in proximity to the fuel injectors  55 . 
     At this point, it should be noted that the raised portion  18  of the hull is formed with an upwardly extending flange  62  which surrounds an access opening  63  that affords access to not only the fuel injectors  57  and spark plugs  58 , but also other components of the engine for servicing. The seat  17  has a removable portion that overlies and closes this opening  63 . However, it can be easily accessed for servicing by removing the seat portion  17  as should be readily apparent. 
     It should also be noted that the fuel injector  58  are positioned well above the waterline WL that exists when the watercraft is floating in a body of the water. Under planing conditions, this waterline falls even lower as indicated in FIG. 2 as WLp. Thus, the fuel injectors  57  will be well protected under all conditions. 
     From the expansion chamber device  64 , the exhaust gases are passed rearwardly through an exhaust pipe  65  to a suitable discharge. A water trap device (not shown) may be provided in this discharge to protect the engine from water being drawn into the exhaust ports  59  through the exhaust system  62 . 
     The fuel supply system for supplying fuel to the fuel injector  57  will now be described by primary reference to FIGS. 2 and 3 wherein it is shown in part schematically and certain of the components are shown in locations other than their actual physical location so as to permit understanding of the system. 
     Specifically, the fuel tank  24  supplies fuel through a conduit to a low-pressure pump  65 . This low-pressure pump  65  may be driven by pulsations in the induction system or mechanically from a component of the engine. It, in turn, delivers fuel through a conduit  66  to a fuel filter  67  which is mounted either on the forward side of the bulkhead  32 , as seen in FIG. 1; or at the rear of the engine in the void area  68   b  over the coupling  26  between the crankshaft  25  and the impeller shaft  28  or at a void area  68   a  at the front of the engine  21  over the flywheel cover  61 , as shown in FIG. 2; or at a side of the raised area  18 , as seen in FIG.  3 . The fuel filter is mounted in either location by means of threaded fasteners  69 . 
     Fuel flows from the fuel filter  67  to a high pressure pump  71  where it is delivered to a fuel rail  72  that extends along and is attached to the fuel injector  57  in a known manner. The high pressure pump  71  may be of any known type that will deliver fuel at the desired pressure. 
     A fuel pressure regulator  73  is positioned at the rearward end of the fuel manifold  72  and regulates the pressure of fuel delivered to the injector  57  by dumping excess fuel back to the fuel tank through a return line  74 . Thus, it will be seen that not only are the fuel injectors  57  protected by the exhaust expansion chamber device  64  and the intake device  47 , but so also are the fuel rails  72 . 
     Because of the operation in the marine environment, a water sensor  74  may be provided in the fuel filter  67 . This communicates with a control unit  75  so as to activate a warning  76  in the event water is present in the fuel to too great an extent. 
     In the embodiment as thus far described, the fuel injectors  57  have been disposed so as to spray along the bore axis  42  and the spark plugs  58  have been inclined forwardly toward the front of the engine while still being positioned in the plane that contains the cylinder bore axis  42 . As seen in the solid line view of FIG. 4, it is possible to incline the fuel injector  57  in a rearward direction along the same plane as they lie in the embodiment of FIGS. 1-3. This will still place them in an arrangement where they will be protected by both the induction system  46  and the exhaust system  61 . Alternatively with such an arrangement, the spark plugs  58  may be mounted vertically as shown in phantom lines in FIG.  4 . 
     Instead of mounting the spark plugs  58  and fuel injector  57  so that they lie on the longitudinal plane that contains the cylinder bore axis  42  with one being spaced forwardly of the other, these components may be mounted in transverse, side by side relationship. The following embodiments shows such an arrangement. 
     Referring first to FIG. 5, this shows a slightly different manifold arrangement wherein the cylinder block  37  is positioned in the engine compartment so that it is inclined to one side of a vertically extending plane. With this arrangement, therefore, the induction system is moved downwardly and the expansion chamber device  64  is positioned on the same side of the engine. Thus, the expansion chamber device of the exhaust system and the air inlet device  47  are on the same side but again both are positioned vertically above the fuel injector  57  to protect them. The spark plug  58  may be mounted at one side or the other of the fuel injector  57  as shown in the solid and phantom line views of this Figure. 
     FIGS. 6 and 7 show another embodiment where the injectors and the spark plugs are located in side by side relationship. In this embodiment, the over all engine is disposed like the embodiments of FIGS. 1-3 and  4  in that the cylinder bore axes  42  extend vertically and lie within the common longitudinal plane of the watercraft. 
     In FIGS. 6 and 7, the fuel injectors  57  are essentially vertically disposed. The spark plugs  58  are inclined toward one side, in this embodiment, the exhaust side. 
     FIG. 8 shows a similar embodiment, but both the fuel injectors  57  and the spark plug  58  are inclined but in this case on opposite sides to the plane containing the cylinder bore axis  42 . 
     Thus, from the foregoing description, it should be readily apparent that the described embodiments provide a direct injected personal watercraft engine and hull arrangement wherein the fuel injectors are positioned in location where they may be easily accessed but are protected from damage and from water. Of course, the foregoing description is that of preferred embodiments of the invention and various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.