Abstract:
A drive mechanism for a high pressure fuel pump on a vertically oriented engine present a compact arrangement while driving the pump at a desired speed tailored to the engine&#39;s size and fuel supply needs. The drive mechanism includes a small diameter drive pulley mounted above a rotor (e.g., a flywheel or a cam drive pulley). This position permits easily access to the drive pulley for repair, replacement and belt positioning. The small diameter drive pulley drives a larger diameter driven pulley coupled to the fuel pump. The size of the drive and driven pulleys are selected to achieve a reduction ratio suited to drive the high pressure fuel pump at a speed tailored to supply an appropriate amount of fuel to the fuel injectors at an effective pressure for injection. In addition, the smaller diameter of drive pulley, and consequently the smaller diameter of the driven pulley, reduces the size of the engine.

Description:
RELATED APPLICATIONS 
     This application claims priority to Japanese Application No. 10-244545, which was filed on Aug. 31, 1998. Also, this application is a continuation-in-part of U.S. Ser. No. 09/145,912, filed Sep. 2, 1998, now U.S. Pat. No. 6,112,726, issued Sep. 5, 2000, which claims priority to Japanese Application Nos. 9-238118, 9-238508, and 9-238509, all of which were filed on Sep. 3, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a vertical engine of the type employed in outboard motors and more particularly to an improved fuel injection system for such vertical engines. 
     2. Description of the Related Art 
     The use of fuel injection for internal combustion engines in order to improve performance, particularly fuel economy and exhaust emission control, is well known. A wide variety of types of fuel injection systems have been proposed for this purpose. Many of these systems inject the fuel into the induction system rather than into the combustion chamber. Such so-called “manifold injected” engines have advantages over carbureted engines. However, there are a number of additional advantages that can be obtained by utilizing direct cylinder injection. 
     By using direct cylinder injection, it is possible to more accurately control the actual fuel-air ratio in the combustion chamber on each cycle of operation. In addition, by utilizing direct cylinder injection, it is possible to obtain stratification in the combustion chamber and thus operate with a lean mixture under some or most running conditions. That is, by stratifying the charge in the combustion chamber, it is not necessary to have a homogeneous stoichiometric charge in the entire combustion chamber. All that is required is to have a stoichiometric charge present in the vicinity of the spark plug at the time that it is fired in order for combustion to be initiated. 
     There are, however, a number of reasons why direct cylinder injection is not utilized more widely. Not the least of these is cost. Not only are the injectors more costly and more critical with direct injected engines, but the supply system for supplying fuel to the injectors also becomes more complicated and expensive. 
     When direct cylinder injection is employed, the injection pressures must not only be higher, but they also must be more accurately controlled. As a result of this, it has been the practice to normally employ reciprocating plunger-type pumps for direct injected engines. Such pumps have a number of components, are complex, and in fact, can become quite bulky. 
     Although these problems may be overcome in some applications, there is a desire to employ direct cylinder or high pressure fuel injection systems for outboard motors. Like other vehicle applications, outboard motors are subject to concern over environmental control and also fuel economy. In addition, outboard motors frequently utilize two-cycle engines as their power plants. These engines can benefit as much or more from direct cylinder fuel injection as four-cycle engines. 
     In addition to the cost factor, the complexity of high pressure injection systems makes it more difficult to integrate them into outboard motors. One reason for this is that the outboard motor is a very compact type of device, and it may be difficult to locate the necessary components for a high pressure fuel injection system. In addition, the injection pump normally is driven off of the engine crankshaft and is frequently in timed relationship thereto. This further complicates the placement and driving of such high pressure fuel injection pumps in outboard motors. 
     In addition to these problems, an outboard motor has another problem which is somewhat unique and different from automotive or other vehicle applications. That is, it is normally the practice to mount an outboard motor engine so that its crankshaft rotates about a vertically extending axis. As a result, the orientation of the engine is quite different than automotive and other applications. This further complicates the location and driving of accessories, such as high pressure fuel injection pumps. 
     SUMMARY OF THE INVENTION 
     A need therefore exists for an improved drive arrangement for a high pressure fuel injection pump for an internal combustion engine of an outboard motor. 
     An aspect of the present invention involves an outboard motor comprising a power head. The power head contains an internal combustion engine including a crankshaft that is disposed generally vertically. A rotor (e.g., a flywheel and/or cam drive pulley) is affixed to the crankshaft. A drive pulley is affixed to the crankshaft above the rotor and has a first diameter. A driven pulley has a second diameter which is larger than the first diameter. A drive belt connects the drive pulley to the driven pulley, which in turn is coupled to and drives a high pressure fuel pump. 
     In a one mode, the driven pulley is connected to a pump drive unit which drives the pump. The size of the drive pulley and driven pulley also are selected to achieve a reduction ratio suited to drive the high pressure fuel pump at a speed tailored to supply an appropriate amount of fuel to the fuel injectors at an effective pressure for injection. 
     Further aspects, features and advantages of the present invention will become apparent from the detailed description of the preferred embodiment which follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above mentioned and other features and aspects of the invention will now be described with reference to the drawings of a preferred embodiment of the present engine construction. The illustrated embodiment, however, is intended to illustrate and not to limit the invent. The drawings contain the following figures: 
     FIG. 1 illustrates an outboard motor and components thereof, including a rear elevational view of the upper portion of the outboard motor with the protective cowling removed and with the engine shown partially in cross-section and a side elevational view of the outboard motor; 
     FIG. 2 is a top plan view of the engine of the power head illustrating the protective cowling in outline and with portions of the engine broken away so as to more clearly show the internal construction; 
     FIG. 3 is an exploded view of the a portion of the engine and fuel system of FIG. 1; 
     FIG. 4 is a side plan cut-away view of the top portion of the cowling of FIG. 1; 
     FIG. 5 a  is a top plan view of the pulley system and belt tensioner according to the present invention; 
     FIG. 5 b  is a cross-sectional view of the belt tensioner of FIG. 5 a;    
     FIG. 6 a  is a top plan view of the engine of FIG. 1 showing the rotor cover; 
     FIG. 6 b  is a side plan cut-away view of the top portion of the engine of FIG. 6 a  according to one embodiment of the present invention; and 
     FIG. 6 c  is a side plan cut-away view of the top portion of the engine of FIG. 6 a  according to an additional embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference now in detail to the drawings and initially to FIGS. 1-3, an outboard motor constructed in accordance with an embodiment of the invention is identified generally by the reference numeral  11 . The general overall construction of the outboard motor  11  may be of any conventional type and, as should be apparent from the foregoing description, the invention deals primarily with an internal combustion engine  12 , which forms a portion of the power head, indicated generally by the reference numeral  13 , of the outboard motor. More specifically, the invention deals with the manner in which certain accessories for the engine  12  are driven. However, in order to permit those skilled in the art to understand the environment in which the invention is practiced, the overall construction of the outboard motor  11  will be described generally. 
     The power head  13  includes, in addition to the engine  12 , a protective cowling  11   a  that is comprised of a lower tray portion  14  to which a removable upper, main cowling portion  15  is detachably connected in a manner known in the art. The outboard motor  11  further includes a driveshaft housing  18  positioned beneath the power head  13 . A lower unit  19  contains a transmission for driving a propeller  23 . This provides a propulsion force for the watercraft with which the outboard motor  11  is associated. 
     In the illustrated embodiment, the engine  12  is depicted as being of a two-cycle, crankcase compression type having six cylinders arranged in a V orientation. It should be apparent, however, that the invention can be utilized with a wide variety of engine types and engines having other numbers of cylinders and other cylinder configurations. Also, the invention can be utilized with four cycle engines. However, the invention has particular utility with multiple cylinder engines for the reasons aforenoted. 
     The engine  12  is comprised of a cylinder block  25  which has a pair of cylinder banks that are disposed at a V angle which diverges rearwardly in the power head  13 . Cylinder bores  26  are formed in each cylinder bank of the cylinder block  25  and receive respective pistons  27  that reciprocate therein. The pistons  27  are connected by means of connecting rods  28  to the throws of the crankshaft  16  in a manner that is well known in this art. The pistons  27 , cylinder bores  26  and cylinder head assemblies  29 , that are affixed to each of the cylinder banks in a known manner, form the combustion chambers of the engine. 
     The crankshaft  16  rotates within a crankcase chamber that is formed by the skirt of the cylinder block  25  and a crankcase chamber  31  that is detachably connected thereto. This crankcase chamber  31  is divided into individual sealed compartments each of which is associated with a respective one of the cylinder bores  26  in a manner well known in the two cycle engine art. 
     An intake charge is delivered to these crankcase chambers  31  by an induction system which is shown schematically in FIG.  1  and which appears partially in FIGS. 2 and 3. This induction system includes an air inlet device  32  which may be configured to provide silencing for the inducted air. This air is drawn from within the protective cowling  11   a  in a manner well known in the outboard motor art and flows out of the air slots  11   b . The main cowling member  11   a  and/or tray  14  may be formed with a suitable air inlet so that atmospheric air can enter into the interior of the protective cowling. Preferably, this inlet is designed in such a way so as to minimize the possible ingestion of water particles into the interior of the protective cowling of the power head  13 . 
     The air inlet device  32  supplies the inducted air to throttle bodies  33  which are disposed on the crankcase chamber  31  at the front of the power head  13 . Throttle valves  34  mounted in the throttle bodies  33  are controlled by a suitable linkage system for controlling the speed at which the engine  12  operates. 
     The throttle bodies  33  communicate with the manifold runners  35  of an intake manifold so as to supply the air charge to the crankcase chamber sections. Reed-type check valves  36  are disposed at the ends of the manifold runners  35  where they communicate with intake ports  37  for delivering the air charge to these crankcase chamber sections. 
     The reed type check valves  36  operate, in a manner well known in the art, so as to permit the air charge to flow into the crankcase chamber sections when the pistons  27  are moving upwardly in the cylinder bores  26 . As the pistons begin their downward stroke, however, the reed type check valves  36  will close so as to permit the charge to be compressed in the crankcase chamber sections without escape therefrom. 
     Upon continued downward movement of the pistons  27 , scavenge ports (not shown) will open to communicate the crankcase chamber sections with the combustion chambers in a manner well known in this art. The charge is then transferred to the combustion chambers for further compression therein. 
     Fuel is mixed with this compressed air charge for providing the motive power for the engine  12 . This fuel is sprayed directly into the combustion chambers by fuel injectors  38  that are mounted in the cylinder head assemblies  29  and discharge directly into the combustion chambers. These fuel injectors  38  are supplied with fuel under pressure by a fuel supply system. After the fuel is burned in the cylinder bores  26 , any remaining fuel or exhaust is expelled through the exhaust ports  20 . The exhaust ports  20  communicate with the left exhaust manifold  21  and the right exhaust manifold  22  to expel the exhaust from the cylinder bores  26 . 
     The fuel supply system includes a remotely positioned fuel tank  39  which generally is located in the hull of the associated watercraft. A priming pump  41  delivers fuel to a conduit  42  which has a quick disconnect connection to the power head  13 , and specifically to a fuel filter  43  positioned therein. 
     The fuel filter  43  filters fuel that is drawn by a low-pressure pump or pumps  44 . These pumps  44  may be driven by the pressure variation in the crankcase chamber sections, or in some other manner, from the engine. The pumped fuel is then delivered to a vapor separator assembly  45  that is mounted within the power head  13  and enclosed by the protective cowling portion  11   a.    
     A uniform level of fuel is maintained in the vapor separator  45  by a float-operated valve  46  that controls the admission of fuel to the vapor separator  45 . A low-pressure, electrically driven fuel pump  47  is mounted in this vapor separator and collects the fuel and delivers it to a pressure feed line  48 . The pressure feed line  48 , in turn, communicates with the inlet side of a high-pressure pump  49 . The high-pressure pump  49  is preferably of the plunger or piston type, and is driven from the engine crankshaft  16  via a belt  50 , as will be described below. The high-pressure pump  49 , in turn, delivers fuel under pressure to a main fuel manifold  51 , which preferably is located in the valley between the cylinder banks. The main fuel manifold  51 , in turn, communicates with fuel rails  52  via fuel lines  51   a . The fuel rails  52  are each associated with the fuel injectors  38 , which are in turn associated with a respective cylinder of the cylinder banks. The fuel rails  52  are mounted to the cylinder head assemblies  29  using bolts  120  into mounting apertures  130 ,  132 . 
     The high-pressure pump  49  is provided in communication with the main fuel manifold  51 . This regulates the pressure delivered to the injectors  38  by dumping fuel back to the vapor separator through a return line  54 . A heat exchanger  55 , or fuel cooler, is provided in this return line for controlling the temperature of the fuel and maintaining it at the desired temperature, to further ensure against vapor being present in the fuel system. A fuel pressure sensor  72  is provided in the return line  54  to detect the pressure of the fuel at the high-pressure pump  49 . 
     The fuel is injected directly into the combustion chambers, as discussed above, by the injectors  38 . The specific fuel control system and strategy therefore may be of any known type. This fuel mixes with the compressed air and then is ignited by spark plugs  56  that are mounted in the cylinder head assemblies  29 . These spark plugs  56  are fired by a suitable ignition system in accordance with any desired timing program. 
     The engine  12  is provided with a lubricating system that includes a lubricant pump  57  that supplies fuel to lubricant injectors  58  in a controlled manner. These injectors  58  spray into the intake manifold runners  35  or, alternatively, deliver lubricant to the moving components of the engine for direct lubrication. Any type of lubricating system may be employed, and this is controlled, like the fuel injectors  38  and spark plugs  56 , by a suitable control in accordance with any desired strategy. 
     The overall operation of the fuel system is controlled by an electronic control unit (ECU)  60 . The ECU  60  receives input signals from an air-fuel ratio sensor  62 , a coolant temperature sensor  66 , an intake temperature sensor  68 , and an engine speed sensor  70 . The ECU  60  processes this information and, based upon the results, provides control signals to the fuel pump  47 , the fuel injectors  38 , the spark plugs  56 , and the lubricant pump  57 . Therefore, the ECU  60  can adjust the amount of fuel flow and the timing of the engine  12 . The use of an ECU  60  to control the fuel system of an engine  12  is well known to one of skill in the art. 
     FIG. 2 shows that the crankshaft  16  rotates about a vertically extending axis. A flywheel assembly  59  is fixed for rotation with the crankshaft  16  at a point above the upper end of the cylinder block  25  and crankcase chamber  31 . This flywheel assembly  59  may also include a flywheel magneto which generates electricity for the ignition system and provides certain timing pulses associated therewith. A starter motor  102  is connected to the flywheel assembly for electronic starting of the engine  12 . 
     The fuel supply and drain unit  115  interconnects with the crankshaft  16 . A pump drive pulley  86  is mounted above the flywheel  59  and connected for rotation with the crankshaft  16 . The pump drive pulley  86  also drives a toothed drive belt  50 . The drive belt  50  in turn drives a high-pressure fuel pump driven pulley  88 . A belt tensioner  90  maintains a proper amount of tension on the drive belt  50 . The driven pulley  88  is connected to an input shaft  92  of a pump drive unit  61  that contains an appropriate transmission for driving the high-pressure pump  49  of the fuel injection system. The relative sizes of the drive pulley  86  and the driven pulley  88  may be adjusted as engine size and reduction requirements dictate. 
     The pump drive unit  61  is secured to the engine with bolts  94 ,  95 , and  96 . The high-pressure pump  49  is secured to the cylinder head assemblies  29  through a mounting bracket  97  using bolts  98 ,  99 . The mounting bracket  97  includes bolt holes  97   a  and  97   b . The bolts  95 ,  96 , and  99  secure into the cylinder head assemblies  29  in a plurality of mounting apertures  135 ,  136 , and  137 . The entire flywheel assembly  59  is protected by a rotor cover  118 . 
     The fuel rails  52  are connected to the high-pressure fuel pump  49  through the fuel lines  51   a . The fuel lines  51  a are secured to the engine  12  with connectors  110 ,  112 . 
     FIG. 4 illustrates a side plan cut-away view of the top portion of the cowling  11   a  containing the engine  12 . Air enters the cowling  11   a  through an air opening  11   c  and flows over the fuel system and out the air slots  11   b  as indicated. The air provides for cooling of the fuel system. 
     The pump drive pulley  86  is powered from the crank shaft  16 . As the pump drive pulley rotates, the belt  50  transfers the rotational energy to drive the driven pulley  88 . The driven pulley  88  rotates the input shaft to the pump drive unit  61 , providing power to the high-pressure fuel system. The belt tensioner  90  ensures that the belt  50  maintains proper tensioning with the pulleys  86 ,  88 . A spring  151  is used to maintain a tension pulley  90   f  tight against the belt  50 . The belt tensioner  90  is secured to the cylinder block  25  with a bracket  145 . The bracket  145  mounts using a bolt  147  in a mounting hole  149 . 
     As best seen in FIG. 2, the position of the drive pulley  86  above the flywheel  59  enables the drive pulley  86  to be easily serviced without removing the flywheel  59 . In addition, this location permits a smaller diameter drive pulley  86  than if the pulley  86  were located beneath the flywheel  86  because of the large mass flywheel located on the outer end of the crankshaft  16 . 
     A diameter of the driven pulley  88  is larger than a diameter of the drive pulley  86 . The respective diameters sizes desirably are selected to achieve a reduction ratio suited to drive the high pressure fuel pump at a speed tailored to supply an appropriate amount of fuel to the fuel injectors at an effective pressure for injection. That is, in order to supply an appropriate amount of fuel to the fuel injectors at a desired pressure, the diameters of the drive and driven pulleys should be properly set so that a suitable reduction ratio is attained from the crankshaft  16  to the input shaft  92  of the pump drive unit  61 . In addition, by varying the diameter size of the drive pulley, the same fuel pump and pump drive unit can be used with various size engines, thereby amortizing the manufacturing and developments costs associated with the high pressure fuel supply system over a greater number of units. 
     The size of the pulleys  86 ,  88  also are selected to minimize the space occupied by the pump drive mechanism on the top end of the engine to maintain a compact engine layout. For this purpose, the drive pulley  86  is also sized smaller than the flywheel  59  (or another rotor disposed below the drive pulley  86 ), and only a little larger than the diameter of the crankshaft  16 . In the illustrated embodiment, the diameter of the drive pulley is at least three times smaller than a diameter of the flywheel, and is generally about three times larger than the upper end of the crankshaft  16  to which it is affixed. The relative size variations between the drive pulley and driven pulley and their respective shafts produces the desired reduction ratio as well as contributes to a compact engine arrangement. Thus, in the illustrated embodiment, a ratio of the diameter size of the drive pulley relative to a diameter size of the upper end of the crankshaft is smaller than a ratio of diameter sizes of the diameter of the driven pulley relative to a diameter size of a rotational shaft  92  of the pump drive unit  61 . Thus, the diameter of the drive pulley is reduced while maintaining the desired reduction ratio to decrease the size of the engine. 
     As best understood from FIG. 2, the pump  49  and the pump drive unit  61  are disposed within a valley between the two banks of cylinders. In this position, the driven pulley  88  is located in the vicinity of the crankshaft  16 , the drive pulley  88 , as well as the pump drive unit  66 , are less likely to be affected by vibrations thereby improving the durability of these components. This arrangement also locates the high pressure fuel pump  49  near the crankshaft  16  to minimize vibrations experienced by this heavy component. 
     FIGS. 5 a  and  5   b  provide a detailed view of the belt tensioner  90 . A bracket  153  extends away from the belt tensioner  90 , and a spring receiver  153   a  is at the end of the bracket  153 . The bracket is secured with bolts  155 ,  157 . A second bracket  90   b  extends approximately perpendicular to the first bracket  153  and is mounted to a support bracket  162 . The second bracket rotates around a shaft  160  and includes a bolt  156  to limit the bracket  90   b  movement away from the belt  50 . The second bracket  90   b  also has a spring receiver  90   c  at the far end. The spring  151  is attached between the two brackets  153 ,  90   b  using the spring receivers  153   a ,  90   c . The spring  151  urges the tension pulley  90   f  into the belt  50  to maintain the proper tension. The tension pulley  90   f  is moveably mounted using a bolt  158  in an elongated aperture  90   g . As the bracket  90   b  moves because of the force of the spring  151 , the bolt  158  moves within the elongated aperture  90   g  to either increase or decrease the tension on the belt  50 . Ball bearings  90   e  are used to ease the movement of the bolt  158 . 
     FIGS. 6 a  and  6   b  show the rotor cover  118  having an opening  118   a . The opening  118   a  has a large diameter and allows for access to the flywheel assembly  59  for maintenance. When the engine is in use, the opening  118   a  is covered with a cap  170  to protect the engine  12  against the environment. As seen in FIG. 6 c , the cap  170  may be replace with a hanger  172  if desired. As understood from FIG. 2, the cover extends over the drive and driven pulleys  86 ,  88 . 
     Numerous variations and modifications of the invention will become readily apparent to those skilled in the art. For instance, the rotor above which the drive pulley  86  is disposed can be a cam drive pulley which forms a portion of a camshaft drive system used in conjunction with the four cycle engine. Accordingly, the invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The detailed embodiment is to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.