Abstract:
A watercraft has a throttle position sensor, an engine speed sensor, and a start switch. The sensors communicate with a controller. The controller can regulate engine speed. The controller regulates or limits the engine to a low speed when the throttle angle is above a predetermined value during startup, and/or when the engine temperature is too low.

Description:
PRIORITY INFORMATION  
         [0001]    This application is based on and claims priority to Japanese Patent Application No. 2001-027045, filed Feb. 2, 2001, the entire contents of which are hereby expressly incorporated by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present application generally relates to an engine control unit, and more particularly, an engine management system that prevents excessive engine speed for a predetermined period of time after the engine has been started.  
           [0004]    2. Description of the Related Art  
           [0005]    Personal watercraft, like other applications that use internal combustion engines as power sources, are experiencing considerable public and governmental pressure to improve not only their performance, but also their exhaust emissions levels. For example, due to the emissions generated by two-stroke powered watercraft, certain recreational areas have banned the operation of such watercrafts. These bans have decreased the popularity of personal watercraft, and have caused manufacturers of these types of watercraft to consider fuel injected engines to power their watercraft and/or other means to reduce emissions levels.  
           [0006]    Fuel injected engines are known to provide significantly enhanced performance, power output, and emission control as compared to carbureted engines. Watercraft, however, normally do not have a neutral setting where the engine is allowed to operate without driving the propulsion device.  
         SUMMARY OF THE INVENTION  
         [0007]    One aspect of the present invention includes the realization that often times the operator of a watercraft opens the throttle when starting the engine, even though the engine does not need the throttle to be opened. For example, certain known fuel injected engines can be programmed to start quickly and reliably without any manipulation of the throttle by the user. Excessive opening of the throttle during commencement can be both harmful to the various engine bearing surfaces due to low initial oil pressure and high oil viscosity. Additionally, an abrupt thrust from the propulsion unit caused by unnecessarily opening the throttle can make docking maneuvers more difficult.  
           [0008]    Another aspect of the present invention is directed to a method of controlling engine operation during start-up in a watercraft. The method includes sensing a throttle valve angle, and determining if said throttle valve angle is larger than a predetermined throttle valve angle associated with normal engine start-up.  
           [0009]    A further aspect of the invention is directed to a method of controlling operation of a watercraft engine during a predetermined engine speed range. The method includes sensing a throttle valve angle, and determining if the throttle valve angle is larger than a predetermined throttle valve angle associated with the predetermined engine speed range  
           [0010]    Yet another aspect of the present invention is directed to a watercraft having a hull and an engine supported by the hull. The watercraft also includes, a fuel delivery system, an ignition system, a throttle valve, and a controller configured to control operation of the fuel delivery and ignition systems. The controller is configured to at least partially disable at least one of the fuel injection system, ignition systems, and starter motor if the throttle valve is open more than a predetermined amount.  
           [0011]    Another aspect of the invention is directed to a method of controlling operation of a watercraft engine. The method includes detecting a temperature of the engine, detecting a speed of the engine, and at least partially disabling at least one of the fuel delivery and ignition systems if the engine speed is above a predetermined speed and the temperature is below a predetermined temperature.  
           [0012]    Yet another aspect of the invention is directed to a watercraft having a hull and an engine supported by the hull. The watercraft also includes a fuel delivery system, an ignition system, an engine speed sensor, an engine temperature sensor, and a controller configured to control operation of the fuel delivery and ignition systems. The controller is also configured to at least partially disable at least one of the fuel injection and ignition systems if a speed of the engine is higher than a predetermined speed and if a temperature of the engine is below a predetermined temperature. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The foregoing features, aspects, and advantages of the present invention will now be described with reference to the drawings of a preferred embodiment that is intended to illustrate and not to limit the invention. The drawings comprise six figures in which:  
         [0014]    [0014]FIG. 1 is a side elevational view of a watercraft configured in accordance with a preferred embodiment of the present invention, with certain internal components including an engine shown in phantom;  
         [0015]    [0015]FIG. 2 is a top view of a watercraft shown in FIG. 1;  
         [0016]    [0016]FIG. 3 is a port side elevational and partial sectional view of the engine shown in FIG. 1;  
         [0017]    [0017]FIG. 4 is a schematic view of an engine control system including an electronic control unit, an ignition system, a starting system, configured to control the engine shown in FIG. 1;  
         [0018]    [0018]FIG. 5 is a block diagram showing a first control routine performed by the electronic control unit shown in FIG. 4; and  
         [0019]    [0019]FIG. 6 is a block diagram showing a modification of the control routine shown in FIG. 5. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]    With reference to FIGS.  1  to  3 , an overall configuration of a personal watercraft  10  is described below. The watercraft  10  employs an internal combustion engine  12  configured in accordance with a preferred embodiment of the present invention. The described engine configuration has particular utility with personal watercraft, and thus, is described in the context of the personal watercraft. The engine configuration, however, can be applied to other types of vehicles as well, such as, for example, small jet boats, other vehicles used with marine drives, automobiles, and other off-road vehicles.  
         [0021]    With reference initially to FIG. 1, the personal watercraft  10  includes a hull  14  formed with a lower hull section  16  and an upper hull section or deck  18 . Both the hull sections  16 ,  18  are made of, for example, a molded fiberglass reinforced resin or a sheet molding compound. An internal cavity  20  or “engine compartment,” is defined between the lower hull section  16  and the upper hull section  18 .  
         [0022]    With reference to FIGS. 1 and 2, the upper hull section  14  preferably includes a hatch cover  24 , a control mast  26  and a seat  28  arranged from fore to aft.  
         [0023]    In the illustrated arrangement, a bow portion  30  of the upper hull section  18  slopes upwardly. An opening can be provided through the bow portion  30  so a rider can access the internal cavity  20 . The hatch cover  24  can be detachably affixed (e.g., hinged) to the bow portion  30  to cover the opening.  
         [0024]    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 . Grips are formed at both ends of the handle bar  32  so that the rider can hold them for that purpose. The handle bar  32  also carries other control units such as, for example, a throttle lever  34  that is used for control of the engine  12 .  
         [0025]    The seat  28  extends rearwardly from a portion just rearward of the bow portion  30 . The seat  28  also generally defines a rider&#39;s area. The seat  28  has a saddle shape and hence a rider can sit on the seat  28  in a straddle-type fashion. Foot areas  35  are defined on both sides of the seat  28  along a portion of the top surface of the upper hull section  18 . The foot areas  35  are formed generally flat, but may be inclined toward a suitable drain configuration. A cushion supported by the upper hull section  18 , at least in principal part, forms the seat  28 . The seat  28  is detachably attached to the upper hull section  18 . In the illustrated embodiment, the upper hull section  18  encloses a storage box  38  that is disposed under the seat  28 .  
         [0026]    A fuel tank  40  is positioned in the cavity  20  under the bow portion  30  of the upper hull section  18 . A duct (not shown) couples the fuel tank  40  with a fuel inlet port positioned at a top surface of the upper hull section  18 . A closure cap (not shown) closes the fuel inlet port. The opening disposed under the hatch cover  24  is available for accessing the fuel tank  40 .  
         [0027]    The engine  12  is disposed in an engine compartment preferably located under the seat  28 , but other locations are also possible (e.g., beneath the control mast or in the bow). The rider thus can access the engine  12  in the illustrated arrangement by detaching the seat  28 .  
         [0028]    A pair of air ducts or ventilation ducts  44  are provided on both sides of the bow portion  30  so that the air within the internal cavity  20  can be readily replenished or exchanged. Optionally, the watercraft  10  can include several more ventialtion ducts (not shown). Except for the ventilation ducts  44 , the engine compartment  20  is substantially sealed to protect the engine  12  and other internal components from water.  
         [0029]    A jet pump unit  46  propels the illustrated watercraft  10 . Other types of marine drives can be used depending upon the application. The jet pump unit  46  preferably includes a tunnel  48  formed on the underside of the lower hull section  16 . The tunnel  48  has a downward facing inlet port  50  opening toward the body of water. A jet pump housing  52  is disposed within a portion of the tunnel  48  and communicates with the inlet port  50 . An impeller (not shown) is supported within the housing  52 .  
         [0030]    An impeller shaft  54  extends forwardly from the impeller and is coupled to an intermediate shaft  53  by a suitable coupling member  58 . Although the impeller shaft is illustrated as one shaft, it is o be understood that the impeller shaft can be formed of several shafts (not shown).  
         [0031]    A crankshaft  56  of the engine  12  drives a reduction gear  55  in connection with an intermediate shaft gear  59 . The rear end of the housing  52  defines a discharge nozzle  57 . A steering nozzle  60  is affixed to the discharge nozzle  57  for pivotal movement about a steering axis that extends generally vertically. 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.  
         [0032]    As the engine  12  drives the impeller shaft  54  and hence rotates the impeller, water is drawn from the surrounding body of water through the inlet port  50 . The pressure generated in the housing  52  by the impeller produces a jet of water that is discharged through the steering nozzle  60 . This water jet propels the watercraft  10 . The rider can move the steering nozzle  60  with the handle bar  32  when he or she desires to turn the watercraft  10  in either direction.  
         [0033]    The engine  12  in the illustrated arrangement operates on a four-stroke cycle combustion principal. With reference to FIG. 3, the engine  12  includes an upper cylinder block  62  portion with four cylinder bores  72  formed side by side along a single plane. The engine  12 , thus, is an L4 (in-line four cylinder) type. The illustrated engine, however, merely exemplifies 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.  
         [0034]    The engine  12  has pistons  64  that reciprocate in the cylinder bores  72  formed within the cylinder block  62 . A valve cover  65  is affixed on top of a cylinder head member  66 , which is connected to the upper end of the cylinder block  62  to close respective upper ends of the cylinder bores  72 .  
         [0035]    A lower cylinder block member  70  is affixed to the lower end of the cylinder block  62  to close the respective lower ends of the cylinder bores  72  and to define, in part a crankshaft chamber or “crankcase”. The crankshaft  56  is journaled between bearings  68  in the cylinder block  62  and the lower cylinder block member  70 . The crankshaft  56  is rotatably connected to the pistons  64  through connecting rods  74 .  
         [0036]    The cylinder block  62 , the cylinder head member  66 , and the crankcase member  70  together define an engine body of the engine  12 . The engine  12  preferably is made of an aluminum based alloy. In the illustrated embodiment, the engine  12  is oriented in the engine compartment to position the crankshaft  56  generally in the longitudinal direction. Other orientations of the engine body, of course, are also possible (e.g., with a transversely or vertically oriented crankshaft).  
         [0037]    Engine mounts  76  extend from both sides of the engine body  12 . The engine mounts  76  preferably 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  76  so that vibration of the engine  12  is greatly inhibited from conducting vibration energy to the hull section  16 .  
         [0038]    An air induction system includes an air intake box  82  for smoothing intake air and acting as an intake silencer. The intake box  82  in the illustrated embodiment is generally rectangular. Other shapes of the intake box of course are possible, but it is desired to make the plenum chamber as large as possible within the space provided in the engine compartment.  
         [0039]    The engine  12  further includes a exhaust pipe  84 , which extends forwardly along a side surface of the engine  12  on the starboard side, then extends around a forward end of the engine  12  and then extends rearwardly along the port side of the engine  12 . The exhaust pipe  84  is then connected to a water-lock  86  at a forward surface of the water-lock  86 . With reference to FIG. 2, a discharge pipe  88  extends from a top surface of the water-lock  86  and transversely across the center plane of the watercraft  10 . The discharge pipe  88  then extends rearwardly and opens at a stern of the lower hull section  16  preferably in a submerged position. Optionally, the discharge pipe  88  can terminate in a side wall of the tunnel  48 . The water-lock  86  inhibits the water in the discharge pipe  88  from entering the exhaust pipe  84 .  
         [0040]    The engine  12  further includes a cooling system configured to circulate coolant into thermal communication with at least one component within the watercraft  10 . Preferably, the cooling system is an open type cooling system, circulating water from the body of water in which the watercraft  10  is operating into thermal communication with heat generating components within the watercraft  10 . However, other types of cooling systems can be used, such as, for example, but without limitation, closed-type liquid cooling systems using lubricated coolants and air-cooling types.  
         [0041]    The engine  12  preferably includes a lubrication system that delivers lubricant oil to engine portions for inhibiting frictional wear of such portions. In the illustrated embodiment, a dry-sump lubrication system is employed. This system is a closed-loop type and includes an oil reservoir  90 .  
         [0042]    An oil delivery pump is provided within a circulation loop to deliver the oil in the reservoir  90  to the engine portions that are to be lubricated, for example, but without limitation, the pistons  64  and the crankshaft bearings  68 . The crankshaft  56  or one of the camshafts (not shown) preferably drives the delivery pump. The crankshaft  56  or one of the camshafts also preferably drives the return pump.  
         [0043]    The engine  12  also includes a fuel delivery system, having carburators or fuel injectors, in order to efficiently mix the correct amount of fuel and air for combustion. The main fuel supply tank  40  is part of the fuel system and is placed in the lower hull section  16  of the associated watercraft  10 .  
         [0044]    The engine  12  further includes an ignition system. Spark plugs  92  are fixed on the cylinder head assembly  66  and exposed into respective combustion chambers (not shown). The spark plugs  92  ignite an air/fuel charge during every combustion stroke, preferably under the control of an ECU  94  to ignite the air/fuel charge therein.  
         [0045]    An electrical system of the watercraft  10  is shown schematically in FIG. 4. A battery  98  is mounted in the watercraft  10 , wherein the battery  98  is connected to a regulator  100  through a main switch  102 . The regulator  100  is arranged to rectify an output of a battery charging coil  104  of a flywheel magneto  116  to charge the battery  98  by maintaining a predetermined voltage.  
         [0046]    A starter relay  106  and a starter motor  108  are connected to the regulator  100  in a parallel circuit. When the main switch  102  and a starter switch  110  are closed, a relay coil  112  within the starter relay  106  is activated and a relay contact  114  is closed thereby activating the starter motor  108 . When the starter motor  108  is activated the crankshaft  56  turns and the engine  12  commences.  
         [0047]    The ECU  94  preferably is a microcomputer that includes a micro-controller having a CPU, a timer, RAM, and ROM. The ECU  94  controls engine operations including fuel injection, firing of the spark plugs  92 , and operation of a fuel pump  96  according to various control maps stored in memory. In order to determine appropriate engine operation control scenarios, the ECU  94  preferably uses these control maps and/or indices stored within the ECU  94  in combination with the data collected from various input sensors. The ECU&#39;s various input sensors can include, but are not limited to, the manifold pressure sensor (not shown), a throttle position sensor  95 , an engine coolant temperature sensor (not shown), an oxygen (O2) sensor (not shown), and a crankshaft speed sensor  97 . The ECU  94  may refer to data collected from various sensors, for example the throttle valve position sensor  95  and other sensors provided for sensing engine running conditions, ambient conditions or other conditions of the engine  12 .  
         [0048]    As shown in FIG. 4, the ECU  94  communicates with the crankshaft speed sensor  97 , the throttle position sensor  95 , and the ignition system. In one arrangement, when the crankshaft speed sensor  97  measures crankshaft angle versus time, it outputs a crankshaft rotational speed signal or engine speed signal to the ECU  94 . The crankshaft speed sensor  97  defines a pulse generator that produces pulses, which are, in turn, converted to an engine speed within the ECU  94  or another separate converter (not shown).  
         [0049]    A signal from the throttle position sensor  95  measuring the angle of a throttle valve  93  is sent to the ECU  94  via a throttle position data line. The signal can be used to control various aspects of engine operation, such as for example, but without limitation, fuel injection and ignition timing. The signal from the throttle valve position sensor  95  generally corresponds to the engine load as indicated by the degree of throttle opening.  
         [0050]    The above noted sensors correspond to merely some of the conditions which may be sensed for purposes of engine control and it is, of course, practicable to provide other sensors such as an intake air pressure sensor, intake air temperature sensor, an engine height sensor, a trim angle sensor, a knock sensor, a neutral sensor, a watercraft pitch sensor, a shift position sensor and an atmospheric temperature sensor in accordance with various control strategies. Moreover, other suitable sensors can also be used.  
         [0051]    The electrical system also includes magnets on the flywheel magneto  116  which generate an alternating induced current in an ignition-charging coil  120 . A magneto cover  117  provides protection of the flywheel magneto  116 . A capacitor discharge ignition unit  118  receives the alternating induced current from the ignition charging coil  120 , which is rectified by a diode  126  and charges a capacitor  128 . The charged capacitor  128  is rapidly discharged through the thyristor  130  when the thyristor  130  is triggered by a ignition trigger coil  122  causing the charging capacitor  128  to complete the capacitor primary winding circuit of the ignition coil  124 . The capacitor  128  then discharges through the primary winding of the ignition coil  124  causing a high voltage to be induced in the secondary winding of the ignition coil  124  which causes the spark plugs  92  to fire, igniting the mixture in the combustion chamber.  
         [0052]    Preferably, the gate of the thyristor  130  is grounded through the trigger capacitor  132 . The trigger coil  122  is connected between the trigger capacitor  132  and the gate of the thyristor  130  and a resistor  134  is connected in parallel to the trigger capacitor  132 . An alarm  136  is also provided to warn the operator if the watercraft is started while the throttle valve is open more than a predetermined angle Θ.  
         [0053]    With reference to FIG. 5, a control routine  138  is configured to control operation of the fuel injection and/or ignition systems based on the throttle valve opening and whether or not the engine is being started. As shown in FIG. 5, the routine  138  starts and then moves to decision block P 1 . In the illustrated embodiment, the routine  138  can start as soon as a rider attempts to start the engine  12 , for example, as soon as a start button is activated. However, it is to be understood that the routine  138  can start at any time.  
         [0054]    In the decision block P 1 , the throttle valve angle value Θ is compared to a predetermined throttle valve angle of 2 degrees. In the illustrated embodiment, the throttle valve is designed to allow a small amount of air to pass therethrough, so as to allow the engine  12  to operate at an idle engine speed. However, the throttle valve could be configured to be closed at idle, e.g., 0 degrees, where the induction system of the engine includes an idle air passage bypassing the throttle valve  93 . Thus, the routine  138  uses 2 degrees as a predetermined throttle opening because, for the illustrated engine  12 , 2 degrees encompasses an opening corresponding to idle speed operation of the engine  12 , as well as a small amount to allow for normal wear of the throttle valve  93 . For example, after prolonged use of the engine  12 , the throttle valve  93  can become soiled. Additionally, a spring used to hold the throttle valve  93  in the closed or idle position can become worn and thus fail to fully return the throttle valve to the closed or idle position. If the throttle valve angle Θ is greater than 2 degrees, the program moves to the decision block P 2 .  
         [0055]    In the decision block P 2 , it is determined if the engine is being started. For example, but without limitation, the ECU  94  can determine the engine speed via the engine speed sensor  97 . If the engine speed is less than about 300-400 rpm, then the engine is being started. Engine speeds less than about 300-400 rpm typically corresponds to the speed attained by an engine when its crankshaft is being turned by a starter motor. Thus, when an engine speed is less than about 300-400 rpm, it can be assumed that the engine is being started. Optionally, the ECU  94  can be connected to the starter switch  110 . If the starter switch  110  is being activated, then the engine is being started. If the engine is being started, then the routine  138  moves to the operation block P 3 .  
         [0056]    In the operation block P 3 , the ignition and/or fuel system is partially or entirely stopped. For example, the ECU  94  can partially disable at least one of the fuel injection system, ignition system, or the starter motor  108 . As such, the ECU  94  can limit engine speed, or completely prevent the engine  12  from starting. Preferably, the routine  138  returns to the beginning and repeats as long as the engine is running.  
         [0057]    If, however at the decision block P 1  the throttle valve angle Θ is determined to be less than 2 degrees, the program moves to operation block P 4  where the ECU  94  allows for normal ignition and fuel system operation. The program then returns to the start of the control routine and repeats the forgoing steps.  
         [0058]    Similarly, if it is determined that the engine is not being started at the decision block P 2 , then the routine  138  moves to operation block P 4  where the ECU allows for normal ignition and fuel system operation. The program then returns to the start of the control routine and repeats the forgoing steps.  
         [0059]    It is to be noted that the routine  138  describer above prevents a surge in engine speed, not only when a user is improperly holding the throttle open during starting, but also when the throttle valve is excessively opened due to a worn throttle return spring, or corrosion or a foreign particle preventing the throttle valve to return to the fully closed or idle speed position.  
         [0060]    [0060]FIG. 6 illustrates a control routine  140  which is a modification of the routine  138  illustrated in FIG. 5. As shown in FIG. 6 the control routine  140  starts and then moves to decision block P 10  where it determines if the throttle angle Θ is greater than one degree. If the throttle angle Θ is not greater than one degree, the routine  140  moves to operation block P 18 .  
         [0061]    In operation block P 18 , the ignition and fuel systems are operated normally. For example, the ECU  94  controls the ignition and fuel systems according to any known strategy for normal operation. The program then ends returns to the start of the control routine and repeats the forgoing steps.  
         [0062]    If in decision block P 10  the throttle angle is greater than one degree, the program moves to the decision block P 14 , where it determines if the engine speed is above a predetermined engine speed “A”. For example, the ECU  94  can sample the output of the engine speed sensor  97  and compare the sampled value to the predetermined value A. In the illustrated embodiment, the engine speed A corresponds to about 2000-3000 rpm, i.e., an appropriate upper limit engine speed for an engine that has not yet warmed to a normal operation temperature. If the engine speed is above a predetermined speed “A” then the program moves to operation block P 16 .  
         [0063]    In the operation block P 16 , the ignition and/or fuel system is partially or entirely stopped. For example, the ECU  97  can at least partially disable the operation of the fuel injection and/or ignition systems. Preferably, the ECU  97  disables the fuel injection and/or ignition systems so as to limit the speed of the engine to approximately 2000-3000 rpm. The program returns to the start of the control routine and continues the program as long as the engine is running.  
         [0064]    If, at the decision block P 14  the engine speed is determined to be less than a predetermined engine speed “A”, the routine  140  moves to operation block P 18  normal ignition and fuel system operation is allowed. For example, the ECU  97  can control the ignition and fuel systems according to any known strategy for normal operation. The routine  140  then ends. Optionally, the routine  140  can return to the beginning and repeat after the control block P 18 . Additionally, the routine  140  can be configured to operate only when the temperature of the engine  12  is below a normal operating temperature. For example, the ECU  97  can be configured to sample an engine temperature sensor and run the routine  140  only when the engine temperature is below a normal operating temperature. Preferably, the normal operating temperature is the minimum temperature at which the engine  12  should be allowed to operate over its entire rpm range.  
         [0065]    Thus, from the forgoing description, it should be readily apparent that the described embodiments very effectively control engine speed during a rapid deceleration state in order to prevent engine stalling. Comparing throttle angle and engine speeds in order to determine the operating condition of the watercraft accomplishes this.  
         [0066]    Of course the forgoing 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.