Patent Publication Number: US-6213829-B1

Title: Component layout for outboard motor

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an outboard motor and more particularly to an improved construction and component layout for a four cycle outboard motor. 
     In outboard motors, it is a common practice to employ a two cycle internal combustion engine as a power unit. Such engines have considerable advantages for this particular type of application. Because of their relatively compact nature, simple construction and high relative output for their displacement, they are well suited for this purpose. However, because of emission concerns, two cycle engines are being replaced by four cycle engines in these applications. 
     There are, however, not only space problems in connection with substituting four cycle engines for two cycle engines, but there is also a problem in that the engine has more complexity and the layout of the engine and its components presents considerable problems for the designer. To further complicate the problem, frequently the engine is provided also with an alternator so as to charge a storage battery or electrical system in the associated watercraft. The alternator must be driven off of the engine and this further complicates the positioning of components in the power head and the driving of those components which must be driven from the engine. Furthermore, there is a strong desire to maintain the outboard motor power head in such a nature that it can be easily serviced, particularly while still attached to the transom of the associated watercraft. 
     It is, therefore, a principle object of this invention to provide an improved outboard motor construction particularly employing a four cycle internal combustion engine. 
     It is a further object of this invention to provide an improved four cycle engine powered outboard motor having accessories driven by the engine and positioned in a compact and yet serviceable manner. 
     A further difficulty with the use of four cycle engines is caused by the fact that the crankshaft of the engine is normally at the front of the power head to facilitate connection to the drive shaft. The drive shaft is normally placed forwardly in the drive shaft housing. Because of the fact that the engine generally uses overhead valves and at least one overhead camshaft the center of gravity of the outboard motor and/or the power head is displaced rearwardly. This can cause vibration problems. 
     It is, therefore, a further object of this invention to provide an improved outboard motor construction particularly employing a four cycle internal combustion engine with a forwardly located center of gravity. 
     SUMMARY OF THE INVENTION 
     This invention is adapted to be embodied on an outboard motor that is comprised of a power head consisting of a multi-cylinder internal combustion engine and a surrounding protective cowling. The outboard motor also includes a drive shaft housing and lower unit, the latter of which contains a propulsion device for propelling an associated watercraft. The engine is mounted within the protective cowling so that its crankshaft rotates about a vertically extending axis. The crankshaft is coupled to a drive shaft that depends into the drive shaft housing and lower unit for driving the propulsion device. A flywheel is affixed to the upper end of the crankshaft. A first accessory drive is affixed to the crankshaft below the flywheel for driving at least one engine accessory. The engine accessory is mounted at an upper end of the engine and at least in part within the outer peripheral surface of the flywheel in top plan view. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of an outboard motor having a construction that is typical for all embodiments of the invention, but which shows specifically a first embodiment of the invention as attached to the transom of a watercraft, that is shown partially and in cross-section. 
     FIG. 2 is a top plan view of the power head of this embodiment with the protective cowling being shown in phantom. 
     FIG. 3 is a left side elevational view of the power head construction as shown in FIG. 1 with the protective cowling being shown in outline. 
     FIG. 4 is a side elevational view of the right hand side of this embodiment. 
     FIG. 5 is a front elevational of this embodiment, again showing the power head components only. 
     FIG. 6 is a top plan view, in part similar to FIG. 2, of a second embodiment of the invention showing the same components in the same fashion. 
     FIG. 7 is a left hand side elevational view of this embodiment and is in part similar to FIG.  3 . 
     FIG. 8 is a right side elevational view of this embodiment and is in part similar to FIG.  4 . 
     FIG. 9 is a front elevational view of this embodiment and is in part similar to FIG.  5 . 
     FIG. 10 is a top plan view, in part similar to FIGS. 2 and 6, and shows a third embodiment of the invention. 
     FIG. 11 is a left hand side view of this embodiment and is in part similar to FIGS. 3 and 7. 
     FIG. 12 is a right side elevational view of this embodiment and is in part similar to FIGS. 4 and 9. 
     FIG. 13 is a front elevational view of this embodiment and is in part similar to FIGS. 5 and 9. 
     FIG. 14 is a top plan view, in part similar to FIGS. 2,  6  and  10 , and shows a fourth embodiment of the invention. 
     FIG. 15 is a left side elevational view of this embodiment and is in part similar to FIGS.  3 , 7  and  11 . 
     FIG. 16 is a right side elevational view of this embodiment and is in part similar to FIGS. 4,  8  and  12 . 
     FIG. 17 is a front elevational view of this embodiment and is in part similar to FIGS. 5,  9  and  13 . 
     FIG. 18 is a top plan view, in part similar to FIGS. 2,  6 ,  10  and  14 , and shows a fifth embodiment of the invention. 
     FIG. 19 is a left side elevational view of this embodiment and is in part similar to FIGS.  3 , 7 ,  11  and l 5 . 
     FIG. 20 is a front elevational view of this embodiment and is in part similar to FIGS. 5,  9 ,  13  and  17 . 
     FIG. 21 is a top plan view, in part similar to FIGS. 2,  6 ,  10 ,  14  and  18 , and shows a sixth embodiment of this invention. 
     FIG. 22 right side elevational view of this embodiment and is in part similar to FIGS. 4,  8 ,  12  and  16 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     General Construction and Embodiment of FIGS.  1 - 5   
     Referring now in detail to the drawings and initially to FIG. 1, an outboard motor having a general construction that is typical of all of the embodiments is illustrated generally by the reference numeral  51  and is shown attached to the transom  52  of a hull  53  of a watercraft, indicated generally by the reference numeral  54 . 
     The outboard motor  51  is comprised of a power head, indicated generally by the reference numeral  55 , which is comprised of a powering internal combustion engine, indicated generally at  56 , and a surrounding protective cowling that is comprised of a lower tray portion  57  and an upper, main cowling portion  58 . The main cowling portion  58  is detachably connected to the tray portion  57  in a suitable manner, including a latch mechanism  59 . 
     A drive shaft housing and lower unit  61  depends from the power head  55  and carries a propulsion device in the form of a propeller  62  for propelling the associated watercraft  54 . 
     As is typical with outboard motor practice, the engine  56  is supported in the power head  55  so that its crankshaft  63  rotates about a vertically disposed axis. This facilitates connection to a drive shaft  64  that is journaled in the drive shaft housing and lower unit  61  in an appropriate manner. The drive shaft  64  drives a propeller shaft  65  to which the propeller  62  is affixed through a conventional, forward, neutral, reverse transmission, shown schematically at  66 . 
     A steering shaft  67  is affixed to the drive shaft housing  61  by means that include a lower bracket  68 . This steering shaft  67  is journaled in a swivel bracket  69  for steering of the outboard motor  51  and the associated watercraft  54  in a known manner. A tiller  71  is affixed to the upper end of the steering shaft  67  so as to control this steering movement. 
     The swivel bracket  69  is connected to a clamping bracket  72  by means of a pivot pin  73  for tilt and trim movement of the outboard motor  51  in a well known manner. The clamping bracket  72  has a suitable means to provide a detachable connection to the watercraft transom  52 . 
     Referring now in more detail specifically to FIG. 2, the internal combustion engine  56  and certain of its auxiliaries will now be described in more detail. The engine  56  in this embodiment, as well as several of the other embodiments, is of the four cylinder, inline type. As will become readily apparent from the following description, it will be understood that the invention can be employed with engines having other cylinder arrangements such as V-type engines. Also, the invention may be practiced with engines having different cylinder numbers than the specific four cylinder construction which is utilized in all illustrated embodiments. 
     The engine  56  is also in all embodiments herein described as operating on a four stroke principle. Although some features of the invention can be employed with two stroke engines, the invention has particular utility with four stroke engines because of their greater complexity and the fact that they normally have a number of auxiliaries that are driven from the engine crankshaft, such as the crankshaft  63 . 
     The engine  56  is comprised of a cylinder block  74  which, as already noted, is formed with four aligned, vertically spaced cylinder bores  75 . Pistons  76  are supported for reciprocation with each of the cylinder bores  75 . The pistons  76  are coupled by means of connecting rods  77  to the throws  78  of the crankshaft  63 . The crankshaft  63  is rotatably journaled in a crankcase chamber that is formed by a skirt of the cylinder block  74  and a crankcase member  79  that is affixed thereto. 
     It should be understood that although certain details of the internal construction of the engine  56  are illustrated and will be described, the invention deals more with the manner of driving certain auxiliaries for the engine and the location of these auxiliaries and the drives for them within the power head  55 . For that reason, the following description of the internal components of the engine  56  should be considered as only exemplary of those constructions with which the invention may be utilized. 
     A cylinder head assembly, indicated generally by the reference numeral  81 , is affixed to the cylinder block  74  in a suitable manner. This cylinder head assembly  81  includes a main cylinder head member that has individual recesses  82  that close the ends of the cylinder bores  75  above the pistons  76  and form with these elements the combustion chambers of the engine. 
     An induction system, indicated generally by the reference numeral  80 , supplies an air charge to the engine combustion chambers. This induction system draws air from within the protective cowling. This air is admitted to the interior of the protective cowling through an air inlet opening  83  (FIG. 1) that is formed at the rear of the main cowling member  58  and is defined in major part by a cover piece that is affixed to the main cowling member  58  in a known manner. 
     This inlet opening  82  cooperates with a baffle arrangement so as to assist in the separation of water that is present in the air due to the marine environment. This air inlet arrangement appears in FIGS. 3-5 and includes a pair of upwardly extending inlet openings  84  that are formed in the upper surface of the main cowling member  58  beneath the aforenoted cover plate. These openings are disposed generally in the area where the cylinder head assembly  81  meets the cylinder block  74  as shown in FIG.  2 . 
     Referring now further to the engine air inlet system  80  by specific reference to FIGS. 2-4, an air inlet silencer device  85  is provided at the front of the power head  55  and extends vertically along a leading edge of the crankcase member  79  in this particular embodiment. This air inlet and silencer device  85  has a sidewardly positioned inlet tube  86  that defines an air inlet opening  87  into which air is drawn. 
     This air is then delivered from the silencer, inlet device  85  through a plurality of manifold runner sections  88  to an intake manifold  89  that is formed at least in part by the cylinder head assembly  81 . It also may be comprised of a separate member that is attached to the cylinder head assembly  81  and which terminates in intake passages  91  that are formed in the main cylinder head assembly  81 . 
     These intake passages  91  terminate at intake valve seats formed in the cylinder head recesses  82 . Poppet type intake valves  92  cooperate with these valve seats to control the opening and closing and the entry of the air charge into the combustion chambers. These intake valves  92  are urged to a closed position by means of a suitable spring arrangement and are opened by an intake camshaft  93  that is suitably journaled in the cylinder head assembly  81  and which has cam lobes  94  for this purpose. The manner in which the intake camshaft  93  is operated will be described later. 
     Mounted in the cylinder head assembly  81  are a plurality of spark plugs  95 , one for each cylinder in a preferred form. The spark plugs  95  have their gaps extending into the cylinder head recesses  82  and fire a charge which is formed in the cylinder head intake passages  91 . 
     This charge is formed by fuel injectors  96  that are mounted in the cylinder head manifold portion  89  and which spray into the intake passages  91  toward the valve seats. The fuel injectors  96  are supplied with high pressure fuel through a suitable fuel supply system, certain components of which will be described later. The fuel injectors  96  and spark plugs  95  are controlled by an ECU, which will also be mentioned later. 
     The charge which has been ignited in the combustion chambers will expand and drive the pistons  76  downwardly in the cylinder bores so as to drive the crankshaft  63  in a manner well known in the art. 
     The burnt charge is discharged from the combustion chambers through exhaust passages  97  formed in the cylinder head assembly  81  on the side opposite the intake passages  91 . These exhaust passages  97  begin at exhaust valve seats that are formed in the cylinder head recesses  82 . Poppet type exhaust valves  98  cooperate with these exhaust valve seats to control the flow of exhaust gases from the combustion chamber. 
     These poppet type exhaust valves  98  are urged to their closed positions by means of suitable spring arrangements. The exhaust valves  98  are opened by the cam lobes  99  of an exhaust camshaft  101  that is journaled in the cylinder head assembly  81  for rotation about an axis that is parallel to the axis of rotation of the intake camshaft  93  and also of the crankshaft  63 . The drive mechanism for the exhaust camshaft  101 , like that of the intake camshaft  93 , will be described later. 
     It should also be noted that the intake and exhaust camshafts  93  and  101  are journaled in cam chambers formed at the outer end of the cylinder head assembly  81  which are covered by means of a cam cover  102  that is affixed to the remainder of the cylinder head assembly in any known manner. 
     The exhaust gases from the cylinder head exhaust passages  79  are delivered to an exhaust manifold, indicated generally by the reference numeral  103 , and which is formed in main part in the cylinder block assembly  74 . This exhaust manifold  103  terminates in a downwardly directed discharge opening  104 . 
     As is fairly conventional in outboard motor practice, the engine  56  is mounted on an exhaust guide plate  105  that is provided at the upper end of the drive shaft housing and lower unit assembly  81 . Suitable exhaust gas passages are formed in the exhaust guide  105  and discharge the exhaust gases downwardly as shown by the arrow  106  in FIG. 1 to an expansion chamber  107  formed within the drive shaft housing  61 . These exhaust gasses are then discharged to the atmosphere through an underwater through the hub exhaust gas discharge  108  formed in the hub of the propeller  62 . 
     This underwater exhaust gas discharge is useful in silencing the exhaust gases when traveling at high speeds and when the propeller  62  is only shallowly submerged. When traveling at lower speeds or when idling, the underwater through the hub discharge  108  will be deeply submerged and there will be a high water pressure across its opening. At this same time, the exhaust gas pressure is relatively low, and hence there is provided an above the water idle exhaust gas discharge where the exhaust gases may exit under this running condition. Since these arrangements are well known in the art and form no particular part of the invention, further description of them is not believed to be necessary to permit those skilled in the art to practice the invention. 
     As has been noted, the important features of the invention deal with the various drives for the engine accessories and, therefore, the foregoing description as to the construction of the basic engine  56  should be considered as only typical of those which with the invention can be utilized. These accessory drives will now be described dealing first with the drive for the intake and exhaust camshafts  93  and  101 . 
     As best seen probably in FIG. 2, the crankshaft  63  extends upwardly beyond the upper surface of the cylinder block  74  and crankcase member  79 . A drive sprocket  111  is affixed to the crankshaft immediately adjacent the upper face of these two members. This drive sprocket  111  drives a timing belt  112  which is, in turn, that is entrained with driven sprockets  113  and  114  that are affixed to upwardly extending portions of the intake and exhaust camshafts  93  and  101 , respectively. The diameters of the driving sprocket  111  and driven sprockets  113  and  114  is set so as to provide the 2 to 1 speed reduction in the drive of the intake and exhaust camshafts  93  and  101  from the crankshaft  63 . A smaller idler sprocket  115  (FIG. 2) is mounted on the upper portion of the cylinder block  74  so as to assist in maintaining belt tension for the drive belt  112 . 
     Immediately above the camshaft drive sprocket  111 , a further accessory drive pulley  116  is affixed to the upwardly extending portion of the crankshaft  63 . This drive pulley  116  drives a further drive belt  117  which, in turn, drives an alternator driving pulley  118 . The alternator driving pulley  118  is affixed to the shaft of an electrical generating alternator  119  that is mounted on the crankcase member  79  on the side of the crank case member opposite to that where the air inlet device  85  is provided in this embodiment. A mounting bracket  120  is provided for this purpose. 
     Immediately above the drive pulley  106 , a flywheel magneto  121  is affixed to the uppermost end of the crankshaft  63 . This flywheel magneto has a ring gear  122  formed integrally thereon that is adapted to be engaged by a pinion gear  123  of a starter motor  124 . The starter motor  124  is mounted on the cylinder block  74  in proximity to the alternator  119  and in a generally otherwise open area. 
     As may be best seen in FIG. 2, the starter motor  124  and alternator  119  are positioned in major part below the flywheel magneto  121  and lie in substantial part radially inwardly of its outer periphery so as to provide a very compact assembly. 
     A shroud cover  128  may be mounted on the upper side of the engine  56  to overlie these various drives including the flywheel magneto  121 , alternator drive belt  117  and camshaft drive belt  112 . However, the air flow from the air inlet openings  84 , indicated by the arrows C to the induction system air inlet opening  87  will flow across this cover and cool these various accessory drives. 
     In addition to those components already described, certain other components associated with the engine are also mounted in locations that provide significant advantages. For example, it has been mentioned that the fuel injectors  96  and spark plugs  95  are controlled by an electronic control unit (ECU). This unit, as indicated by the -reference numeral  125 , is mounted in this embodiment on the crankcase member  79  in close proximity to the air inlet device inlet opening  87  as seen in FIGS. 2 and 5. As a result, this unit will be protected and cooled by the induction system air flow, but also will be isolated from water vapor which will have been separated by the time it reaches this area through the air flow path C. 
     The fuel injection system also includes a fuel pump  126  and vapor separator  127  which are mounted as shown in FIGS. 2 and 3 beneath the intake manifold runners  88 , but in an area where they are otherwise easily accessible for servicing and occupy space that would normally be void space. Thus, quite a compact assembly is provided with this arrangement and nevertheless, the components are mounted where they are easily serviceable and do not increase into any significant extent the size of the motor assembly. 
     An electrical circuit box  128  also appears in FIG.  4 . This may contain various electrical components for engine operation. This is also mounted in a location to receive the cooling air flow. 
     The forward location of the relatively heavy alternator coupled with its forward mounting also reduces vibrations by moving the center of gravity closer to the forward connection of the drive unit to the steering shaft. As seen in FIG. 1 the actual center of gravity G 1  is located well forward of where the center of gravity G 2  would be if there were no alternator. 
     Embodiment of FIGS.  6 - 9   
     FIGS. 6-9 show a further embodiment of the invention which is generally similar to the embodiment of FIGS. 2-5 and is adapted to be incorporated in an outboard motor having the same general construction as shown in FIG.  1 . This embodiment differs from the previously described embodiment only in the relocation of certain components. Therefore, where the components are of the same construction as that previously described, they have been identified by the same reference numerals and will be described again only insofar as it is necessary to understand the construction and operation of this embodiment. 
     In this embodiment, the intake system, indicated generally by the reference numeral  151 , is different in that the air inlet device and silencer  85  is positioned to the rear of the protective cowling and on the side of the cylinder head assembly  81  opposite to the intake manifold  89 . Thus, its intake portion  86  and inlet opening  87  extends upwardly rather than sidewardly. 
     With this positioning of the intake opening  87 , some of the intake air from one of the cowling inlet openings  84  can flow directly into the opening  87  as seen by the arrow C 1 . The remainder of the air will flow in a more circuitous path as indicated by the arrow C 2  in FIG.  6 . 
     The intake manifold thus is provided with runners  152  that extend across the rear end of the engine and above the cam cover  102  so as to enter the intake manifold section  89  from the rear. 
     Because the inlet silencer device  85  is removed from the forward portion of the power head  55 , the alternator  119  and its pulley  108 , as well as the starter motor  124  and its pinion gear  123 , may be rotated in a counter-clockwise direction as seen from above so as to place these elements on opposite sides of a longitudinally extending plane that contains the axis of rotation of the crankshaft  63 . Thus the center of gravity in this embodiment is moved further in a forward direction from the previous embodiment to further reduce vibrations. 
     This also permits the ECU  125  to be positioned in the space occupied by the starter motor  124  in the previous embodiment and thus still keep it in the path of intake air flow for cooling purposes, while removing it from other heated components of the engine. 
     This embodiment also shows another component of the fuel supply system for the fuel injector  96 . This is comprised of a fuel filter  153  which is mounted in proximity to the vapor separator  127  and fuel pump  126 . This shortens the length of the fuel lines connecting these components. This configuration of the intake manifold  152  also opens up the access to the vapor separator  127  and fuel pump  126 , as well as placing the fuel filter  153  in an easily accessed position. 
     In all other regards, this embodiment is the same as that previously described. Therefore, further description of this embodiment is not believed to be necessary to permit those skilled in the art to practice the invention thereof. 
     FIG. 7 also shows an alternative location for the ECU  125 . This being basically the same as the location of the previously described embodiment. 
     Embodiment of FIGS.  10 - 13   
     FIGS. 10-13 show another embodiment which is different from those embodiments previously described in the location of certain of the components and again in utilizing a slightly different shape for the induction system, which is indicated generally by the reference numeral  201  in this embodiment. In this arrangement, the air inlet and silencer device  85  is positioned adjacent the crankcase member  79  but, in this case, it is positioned to the side of the crankcase member rather than forward of it. Also, this embodiment uses the upwardly facing air inlet section  86  so that the inlet opening  87  faces upwardly. 
     In this embodiment, the alternator  119  and starter motor  124  are located in the same orientation as in FIGS. 2-5. Thus, a large space is opened on the forward side of the crankcase member  79 . The vapor separator  127  is, therefore, located in this area. 
     With this orientation, the manifold runners  88  are as previously described but are shorter in length because the inlet device and silencer  85  is positioned closer to the cylinder head  81  than in the first embodiment. 
     In all other regards, this embodiment is the same as those previously described and thus, further description of the components of this embodiment are not believed to be necessary to permit those skilled in the art to practice this embodiment of the invention. 
     Embodiment of FIGS.  14 - 17   
     This embodiment utilizes an induction system of the type shown in the embodiment of FIGS. 10-13 and it has, therefore, been identified by the same reference numeral. In this embodiment, however, the alternator  119  is moved to the area immediately forwardly of the forward edge of the crankcase member  79  so as to open up the space on the side of the engine opposite the induction system  201 . 
     With this embodiment, the starter motor  124  is positioned behind the intake manifold runners  88  which is not a particular problem because this is not a component that requires frequent servicing. Thus, the vapor separator  127  can be positioned on the opposite side of the engine so as to provide more ready access to this component. 
     In all other regards, this embodiment is the same as those previously described and therefore further description of it is not believed to be necessary to permit those skilled in the art to practice the invention. 
     Embodiment of FIGS.  18 - 20   
     This embodiment is quite similar to the embodiment of FIGS. 2-5 and thus, the components of this embodiment are identified by the same reference numerals as those applied in earlier figures where the components are the same. In this embodiment, the vapor separator  127  is moved from the area behind the manifold runners  81  to the rear of the engine so that it will be positioned adjacent the cam cover  102 . This places it in closer proximity to the fuel injectors  96 . In all other regards, this embodiment is the same as those previously described and, therefore, a further description of this embodiment is not believed to be necessary to permit those skilled in the art to practice it. 
     Embodiment of FIGS.  21  and  22   
     In all of the embodiments as thus far described, the flywheel magneto  121  has been mounted on the upper end of the crankshaft. This embodiment is quite similar to the embodiment of FIGS. 10-13 in the configuration of the induction system and the location of some of the components. With this embodiment, however, the flywheel magneto  121  and the associated ring gear  122  are mounted on the lower portion of the engine at a point above the exhaust guide  105 . Thus, the starter motor  124  is mounted at the lower end of the engine and its starter gear  123  extends downwardly rather than upwardly. 
     This opens up the upper area of the engine for the cam drive that includes the belt  112  and the alternator drive which includes the drive belt  117 . In this embodiment, the starter motor extends to the front of the engine while the alternator lies above it rather than below it. This further assists in a forward location of the center of gravity. Again, however, the alternator and starter motor lie have major portions that lie within the outer periphery of the ring gear  122  in top plan view. 
     With this embodiment, the positioning of the vapor separator  127  is the same as in the embodiment of FIGS. 2-6 as are the other components of the fuel injection system. 
     SUMMARY 
     From the foregoing description, it should be readily apparent that the described embodiments of the invention provide a very compact arrangement for a four-cycle, multi-cylinder internal combustion engine. The arrangements shown provide adequate area for all of the accessories and permits the use of a cam drive and alternator drive off of the crankshaft without interference with each other and while permitting the various accessories to be located in convenient and well-accessed locations. Also the center of gravity is forwardly located to reduce vibrations. 
     Of course, the foregoing description is that of preferred embodiments of the invention. Various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claim.