Air induction system for engine

Information

  • Patent Grant
  • 6543429
  • Patent Number
    6,543,429
  • Date Filed
    Monday, July 16, 2001
    23 years ago
  • Date Issued
    Tuesday, April 8, 2003
    21 years ago
Abstract
An engine includes an engine body and an air induction system. The engine body includes a cylinder block defining a cylinder bore in which a piston reciprocates. A cylinder head member closes an end of the cylinder bore to define a combustion chamber together with the cylinder bore and the piston. The air induction system is arranged to introduce air into the combustion chamber. The induction system includes a first intake conduit through which the air flows to the combustion chamber. A first plenum chamber unit is disposed upstream of the first intake conduit. A control mechanism is arranged to control an amount of the air flowing through the first intake conduit. The induction system also includes a second intake conduit through which the air flows to the combustion chamber. A second plenum chamber unit is disposed upstream of the second intake conduit. The second intake conduit is coupled with the first intake conduit downstream of the control mechanism.
Description




PRIORITY INFORMATION




This application is based on and claims priority to Japanese Patent Application No. 2000-215162, filed Jul. 14, 2001, the entire contents of which is hereby expressly incorporated by reference.




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates generally to an air induction system for an engine, and more particularly to an improved induction system for an engine that has an auxiliary air intake device.




2. Description of Related Art




An internal combustion engine typically comprises an air induction system with which air is introduced into a combustion chamber of the engine. Typically, the induction system includes an air intake conduit, a plenum chamber unit disposed upstream of the air intake conduit and a throttle valve. The plenum chamber unit is used to reduce pulsation in the airflow to the combustion chamber and/or to reduces noise in the intake system. The throttle valve measures an amount of the air (i.e., controls the airflow rate) and is operable by the operator through an appropriate throttle linkage. The induction system thus can supply a desired amount of air to the combustion chamber in response to a throttle opening degree corresponding to operator demand.




In most engine technologies, the engine maintains a certain preset engine speed although substantially no engine load is being applied; this is an idle condition. Typically, the throttle valve is held in an almost closed position under the idle condition. In some engine configurations, an auxiliary intake conduit is provided to bypass the throttle valve so that a certain preset amount of air can be supplied to the combustion chamber even through the throttle valve is substantially closed under the idle condition. For example, U.S. Pat. No. 6,015,319 discloses an improved arrangement of an air induction system that includes such a bypass intake conduit.




Although the idle air is delivered to the combustion chamber through the auxiliary intake conduit, the throttle valve desirably is slightly opened to allow a light air flow through the primary intake conduit to prevent sticking of the throttle valve when higher engine speed operation is desired. Under these circumstances, a problem can arise; the idle speed can exceed a desired objective idle speed or the engine can stall. These two conditions result because the amount of idle air that the engine requires is extremely small because only a low rate of airflow is necessary to maintain a desired objective idle speed. The low rate of airflow is quite sensitive and is likely to be out of tune by external forces such as a negative pressure exerted upon the air. The negative pressure can be produced by the light air flow through the primary intake conduit.




A need therefore exists for an improved air induction system for an engine that can provide an accurate amount of idle air to a combustion chamber thereof.




In some configurations, outboard motors can employ an air induction system that includes an auxiliary intake conduit. Outboard motors also often have a certain decibel of noise associated with their operation. Because the outboard motor typically is used adjacent to the operator (i.e., mounted to the transom of the watercraft), intake noise preferably is isolated from the operator as much as possible.




Another need thus exists for an improved engine for an outboard motor that can isolate the intake noise from the operator as much as possible when the outboard motor is in use.




SUMMARY OF THE INVENTION




In accordance with one aspect of the present invention, an internal combustion engine comprises an engine body and an air induction system. The engine body comprises a cylinder block defining a cylinder bore in which a piston reciprocates. A cylinder head member closes an end of the cylinder bore to define a combustion chamber together with the cylinder bore and the piston. The air induction system is arranged to introduce air into the combustion chamber. The induction system includes a first intake conduit through which the air flows to the combustion chamber. A first plenum chamber unit is disposed upstream the first intake conduit. A control mechanism is arranged to control an amount of the air flowing through the first intake conduit. The induction system includes a second intake conduit through which the air flows to the combustion chamber. A second plenum chamber unit is disposed upstream the second intake conduit. The second intake conduit is coupled with the first intake conduit downstream the control mechanism.




In accordance with another aspect of the present invention, an internal combustion engine comprises an engine body. A moveable member is moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. An air induction system is arranged to introduce air into the combustion chamber. The induction system includes a primary intake conduit through which the air flows to the combustion chamber. A first voluminous unit is disposed upstream the primary intake conduit. A throttle valve is arranged to control an amount of the air flowing through the primary intake conduit. The throttle valve generally allows the majority of the air to flow through the primary intake conduit at engine speed above idle. The induction system includes an auxiliary intake conduit through which at least the air at idle speed flows to the combustion chamber. A second voluminous unit disposed upstream the auxiliary intake conduit. The auxiliary intake conduit is coupled with the primary intake conduit downstream the throttle valve.




In accordance with a further aspect of the present invention, an internal combustion engine comprises an engine body. A moveable member is moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. An air induction system is arranged to introduce air into the combustion chamber. The induction system includes an intake conduit through which the air flows. A first member is provided. A second member is provided. The second member, together with the first member, defines a plenum chamber disposed upstream the intake conduit. Both the first and second members are mounted on the engine body. The first and second members are coupled with one another to form a gap therebetween through which the air enters the plenum chamber.




In accordance with a still further aspect of the present invention, an outboard motor comprises a drive unit. A bracket assembly is adapted to be mounted on an associated watercraft to support the drive unit. The drive unit includes an internal combustion engine. The engine comprises an engine body. A moveable member is moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. An air induction system is arranged to introduce air into the combustion chamber. The induction system includes a first intake conduit through which the air flows to the combustion chamber. A first plenum chamber unit is disposed upstream the first intake conduit. A control mechanism is configured to control an amount of the air flowing through the first intake conduit. The induction system includes a second intake conduit through which the air flows to the combustion chamber. A second plenum chamber unit is disposed upstream the second intake conduit. The second intake conduit is coupled with the first intake conduit downstream the control mechanism. The second plenum chamber unit is disposed opposite to the bracket assembly relative to the engine body.











BRIEF DESCRIPTION OF THE DRAWINGS




These and other features, aspects and advantages of the present invention will now be described with reference to the drawings of preferred embodiments, which embodiments are intended to illustrate and not to limit the present invention. The drawings comprise nine figures.





FIG. 1

is a side elevation view of an outboard motor configured in accordance with a preferred embodiment of the present invention. An associated watercraft is partially shown in section.





FIG. 2

is a top plan view of an engine of the outboard motor. A protective cowling is shown in phantom line.





FIG. 3

is a front elevation view of the engine, which is disposed above an exhaust guide member. The exhaust guide member is partially shown in phantom line.





FIG. 4

is a rear elevation view of the engine and the exhaust guide member. The exhaust guide member is partially shown in phantom line.





FIG. 5

is an enlarged, partially sectioned, top plan view of the engine. A bracket and a cover member are shown in section.





FIG. 6

is an enlarged, partially sectioned, top plan view of an engine configured in accordance with another embodiment of the present invention. A bracket and a cover member are shown in section in this figure. In order to simplify the drawing, the cylinder head assemblies associated with the engine are omitted in this figure.





FIG. 7

is an enlarged partial rear view of the engine.





FIG. 8

is an enlarged, partially sectioned, top plan view of an engine configured in accordance with a further embodiment of the present invention. A bracket and a cover member are shown in section.





FIG. 9

is an enlarged partial rear view of the engine.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION




With reference to

FIGS. 1-4

, an overall construction of an outboard motor


30


that employs an internal combustion engine


32


configured in accordance with certain features, aspects and advantages of the present invention will be described. The engine


32


has particular utility in the context of a marine drive, such as the outboard motor


30


for instance, and thus is described in the context of an outboard motor. The engine


32


, however, can be used with other types of marine drives (i.e., inboard motors, inboard/outboard motors, etc.) and also certain land vehicles, which includes lawnmowers, motorcycles, go carts, all terrain vehicles and the like. Furthermore, the engine


32


can be used as a stationary engine for some applications that will become apparent to those of ordinary skill in the art.




In the illustrated arrangement, the outboard motor


30


generally comprises a drive unit


34


and a bracket assembly


36


. The bracket assembly


36


supports the drive unit


34


on a transom


38


of an associated watercraft


40


and places a marine propulsion device in a submerged position with the watercraft


40


resting relative to a surface


42


of a body of water. The bracket assembly


36


preferably comprises a swivel bracket


44


, a clamping bracket


46


, a steering shaft


48


and a pivot pin


50


.




The steering shaft


48


typically extends through the swivel bracket


44


and is affixed to the drive unit


34


by top and bottom mount assemblies


52


. The steering shaft


48


is pivotally journaled for steering movement about a generally vertically extending steering axis defined within the swivel bracket


44


. The clamping bracket


46


comprises a pair of bracket arms that preferably are laterally spaced apart from each other and that are attached to the watercraft transom


38


.




The pivot pin


50


completes a hinge coupling between the swivel bracket


44


and the clamping bracket


46


. The pivot pin


50


preferably extends through the bracket arms so that the clamping bracket


46


supports the swivel bracket


44


for pivotal movement about a generally horizontally extending tilt axis defined by the pivot pin


50


. The drive unit


34


thus can be tilted or trimmed about the pivot pin


50


.




As used through this description, the terms “forward,” “forwardly” and “front” mean at or to the side where the bracket assembly


36


is located, unless indicated otherwise or otherwise readily apparent from the context use. The arrows Fw of

FIGS. 1

,


2


,


5


,


6


and


8


indicate the forward direction. The terms “rear,” “reverse,” “backwardly” and “rearwardly” mean at or to the opposite side of the front side.




A hydraulic tilt and trim adjustment system


56


preferably is provided between the swivel bracket


44


and the clamping bracket


46


for tilt movement (raising or lowering) of the swivel bracket


44


and the drive unit


34


relative to the clamping bracket


46


. Otherwise, the outboard motor


30


can have a manually operated system for tilting the drive unit


34


. Typically, the term “tilt movement”, when used in a broad sense, comprises both a tilt movement and a trim adjustment movement.




The illustrated drive unit


34


comprises a power head


58


and a housing unit


60


, which includes a driveshaft housing


62


and a lower unit


64


. The power head


58


is disposed atop the housing unit


60


and includes an internal combustion engine


32


that is positioned within a protective cowling assembly


66


, which preferably is made of plastic. In most arrangements, the protective cowling assembly


66


defines a generally closed cavity


68


in which the engine


32


is disposed. The engine, thus, is generally protected from environmental elements within the enclosure defined by the cowling assembly


66


.




The protective cowling assembly


66


preferably comprises a top cowling member


70


and a bottom cowling member


72


. The top cowling member


70


preferably is detachably affixed to the bottom cowling member


72


by a coupling mechanism so that a user, operator, mechanic or repairperson can access the engine


32


for maintenance or for other purposes. In some arrangements, the top cowling member


70


is hingedly attached to the bottom member such that the top cowling member


70


can be pivoted away from the bottom cowling member for access to the engine. Preferably, such a pivoting allows the top cowling member to be pivoted about the rear end of the outboard motor, which facilitates access to the engine from within the associated watercraft


40


.




The top cowling member


64


preferably has a rear intake opening


76


defined through an upper rear portion. A rear intake member with one or more air ducts is unitarily formed with or is affixed to the top cowling member


70


. The rear intake member, together with the upper rear portion of the top cowling member


70


, generally defines a rear air intake space. Ambient air is drawn into the closed cavity


68


via the rear intake opening


76


and the air ducts of the rear intake member as indicated by the arrow


78


of FIG.


1


. Typically, the top cowling member


70


tapers in girth toward its top surface, which is in the general proximity of the air intake opening


76


. The taper helps to reduce the lateral dimension of the outboard motor, which helps to reduce the air drag on the watercraft during movement.




The bottom cowling member


72


preferably has an opening through which an upper portion of an exhaust guide member


80


extends. The exhaust guide member


80


preferably is made of aluminum alloy and is affixed atop the driveshaft housing


62


. The bottom cowling member


72


and the exhaust guide member


80


together generally form a tray. The engine


32


is placed onto this tray and can be affixed to the exhaust guide member


80


. The exhaust guide member


80


also defines an exhaust discharge passage through which burnt charges (e.g., exhaust gases) from the engine


32


pass.




The engine


32


in the illustrated embodiment preferably operates on a four-cycle combustion principle. With reference now to

FIG. 2

, the presently preferred engine


32


has a cylinder block


84


configured as a V shape. The cylinder block


84


thus defines two cylinder banks B


1


, B


2


which extend side by side with each other. In the illustrated arrangement, the cylinder bank B


1


is disposed on the port side, while the cylinder bank B


2


is disposed on the starboard side. In the illustrated arrangement, each cylinder bank B


1


, B


2


has three cylinder bores


86


such that the cylinder block


84


has six cylinder bores


86


in total. The cylinder bores


86


of each bank B


1


, B


2


extend generally horizontally and are generally vertically spaced from one another. As used in this description, the term “horizontally” means that the subject portions, members or components extend generally in parallel to the water surface


42


(i.e., generally normal to the direction of gravity) when the associated watercraft


40


is substantially stationary with respect to the water surface


42


and when the drive unit


34


is not tilted (i.e., is placed in the position shown in FIG.


1


). The term “vertically” in turn means that portions, members or components extend generally normal to those that extend horizontally.




The illustrated engine


32


generally is symmetrical about a longitudinal center plane


88


that extends generally vertically and fore to aft of the outboard motor


30


. This type of engine, however, merely exemplifies one type of engine on which various aspects and features of the present invention can be suitably used. Engines having other numbers of cylinders, having other cylinder arrangements (in-line, opposing, etc.), and operating on other combustion principles (e.g., crankcase compression two-stroke or rotary) also can employ various features, aspects and advantages of the present invention. In addition, the engine can be formed with separate cylinder bodies rather than a number of cylinder bores formed in a cylinder block. Regardless of the particular construction, the engine preferably comprises an engine body that includes at least one cylinder bore.




A moveable member, such as a reciprocating piston


90


, moves relative to the cylinder block


84


in a suitable manner. In the illustrated arrangement, a piston


90


reciprocates within each cylinder bore


86


.




Because the cylinder block


84


is split into the two cylinder banks B


1


, B


2


, each cylinder bank B


1


, B


2


extends outward at an angle to an independent first end in the illustrated arrangement. While a cylinder head assembly


92


is affixed to the first end of the cylinder bank B


1


to close that end of the cylinder bores


86


on this bank B


1


, another cylinder head assembly


94


is affixed to the first end of the cylinder bank B


2


to close that end of the cylinder bores


86


on this bank B


2


. The cylinder head assemblies


92


,


94


, together with the associated pistons


90


and cylinder bores


86


, preferably define six combustion chambers


96


. Of course, the number of combustion chambers can vary, as indicated above.




A crankcase member


100


closes the other end of the cylinder bores


86


and, together with the cylinder block


84


, defines a crankcase chamber


102


. A crankshaft


104


extends generally vertically through the crankcase chamber


102


and can be journaled for rotation about a rotational axis


106


by several bearing blocks. The rotational axis


106


of the crankshaft


104


preferably is on the longitudinal center plane


88


. Connecting rods


108


couple the crankshaft


104


with the respective pistons


90


in any suitable manner. Thus, the reciprocal movement of the pistons


90


rotates the crankshaft


104


.




Preferably, the crankcase member


100


is located at the forwardmost position of the engine


32


, with the cylinder block


84


and the cylinder head assemblies


92


,


94


being disposed rearward from the crankcase member


100


, one after another. Generally, the cylinder block


84


(or individual cylinder bodies), the cylinder head assemblies


92


,


94


and the crankcase member


100


together define an engine body


110


. Preferably, at least these major engine portions


84


,


92


,


94


,


100


are made of aluminum alloy. The aluminum alloy advantageously increases strength over cast iron while decreasing the weight of the engine body


110


.




The engine


32


also comprises an air induction system


114


. The air induction system


114


draws air from within the cavity


68


to the combustion chambers


96


. The air induction system


114


preferably comprises six intake passages


116


and a pair of plenum chambers


118


. In the illustrated arrangement, each cylinder bank B


1


, B


2


is allotted with three intake passages


116


and one plenum chamber


118


.




The most-downstream portions of the intake passages


116


are defined within the cylinder head assemblies


92


,


94


as inner intake passages


120


. The inner intake passages


120


communicate with the combustion chambers


96


through intake ports


122


, which are formed at inner surfaces of the cylinder head assemblies


92


,


94


. Typically, each of the combustion chambers


96


has one or more intake ports


122


. Intake valves


124


are slidably disposed at each cylinder head assembly


92


,


94


to move between an open position and a closed position. As such, the valves


124


act to open and close the ports


122


to control the flow of air into the combustion chamber


96


. Biasing members, such as springs, are used to urge the intake valves


124


toward the respective closed positions by acting between a mounting boss formed on each cylinder head assembly


92


,


94


and a corresponding retainer that is affixed to each of the valves


124


. When each intake valve


124


is in the open position, the inner intake passage


120


that is associated with the intake port


122


communicates with the associated combustion chamber


96


.




Outer portions of the intake passages


116


, which are disposed outside of the cylinder head assemblies


92


,


94


, preferably are defined with intake conduits


128


. Each intake conduit


128


includes a control mechanism or throttle valve assembly


130


. In the illustrated arrangement, the intake conduit


128


is formed with two pieces with the throttle valve assembly


130


being positioned therebetween. While the intake conduits


128


allotted to the cylinder bank B


1


extend forwardly along a side surface of the engine body


110


on the port side from the cylinder head assembly


92


to the front of the crankcase member


100


, the intake conduits


128


allotted to the cylinder bank B


2


extend forwardly along a side surface of the engine body


110


on the starboard side from the cylinder head assembly


94


to the front of the crankcase member


100


.




Each throttle valve assembly


130


preferably includes a throttle body


131


and a throttle valve


132


disposed within the throttle body


131


. The intake conduits


128


and the throttle bodies


131


preferably are made of aluminum alloy. In some arrangements, these components can be made of plastic. Preferably, the throttle valves


132


are butterfly valves that have valve shafts


133


journaled for pivotal movement about a generally vertical axis. In some arrangements, the valve shafts


133


are linked together and are connected to a control linkage. The control linkage would be connected to an operational member, such as a throttle lever, that is provided on the watercraft or otherwise proximate the operator of the watercraft. The operator can control the opening degree of the throttle valves


132


in accordance with operator demand through the control linkage. That is, the throttle valve assemblies


130


can measure or regulate amounts of air that flow through the intake passages


116


to the combustion chambers


96


in response to the operation of the operational member by the operator. Normally, the greater the opening degree, the higher the rate of airflow and the higher the engine speed.




The respective plenum chambers


118


preferably are defined with plenum chamber units or voluminous units


134


which are disposed side by side in front of the crankcase member


100


. Preferably, the plenum chambers


134


are arranged substantially symmetrically relative to the longitudinal center plane


88


. In the illustrated arrangement, each forward end portion


136


of the intake conduits


128


is housed within each plenum chamber unit


134


. As illustrated in

FIG. 3

, each plenum chamber unit


134


preferably has two air inlets


138


, which extend generally rearwardly between the respective intake conduits


128


. That is, two of the intake conduits


128


are formed with one inlet


138


extending therebetween. The respective air inlets


138


define inlet openings


140


through which air is drawn into the plenum chambers


118


. The plenum chamber units


134


also have other two openings


142


which are defined on another side and which are spaced apart vertically from one another. The openings


142


of one plenum chamber unit


134


preferably are formed opposite to the openings


142


of the other plenum chamber unit


134


and are coupled with each other by balancer pipes


144


. Advantageously, this construction provides a manner of roughly equalizing the pressures within each chamber unit


134


. The plenum chambers


118


coordinate air delivered to each intake passage


116


and also act as silencers to reduce intake noise. In other words, the chambers


118


act to reduce the pulsation energy within the intake system and to smooth the airflow being introduced to the engine. The air in both of the chambers


118


also is coordinated with one another through the balancer pipes


144


. The plenum chamber units


134


and the balancer pipes


144


preferably are made of plastic, although they can of course be made of metal material such as, for example, aluminum alloy.




The air within the closed cavity


68


is drawn into the plenum chambers


118


through the inlet openings


140


as indicated by the arrows


148


of

FIGS. 2 and 3

. The air expands within the plenum chambers


118


to reduce pulsations and then enters the outer intake passages


116


through the end portions


136


, as indicated by the arrows


150


of FIG.


2


. The air passes through the outer intake passages


116


and flows into the inner intake passages


120


as indicated by the arrows


152


,


154


of FIG.


2


. As described, the level of airflow is measured by the throttle valve assemblies


130


before the air enters the inner intake passages


120


.




In the illustrated embodiment, the throttle valves


132


are substantially closed to bring the engine


32


to idle speed and to maintain this speed. Preferably, the valves


132


are not fully closed such that the likelihood of throttle valve sticking can be reduced. As used throughout the description, the term “idle speed” generally means a low engine speed that is achieved when the throttle valves


132


are closed but also includes a state in which the valves


132


are slightly opened to allow a small level of airflow through the intake passages


116


. Also, the outboard motor


30


is often used for trolling, which is a very low speed, generally forward movement of the watercraft. Thus, when trolling, a shift mechanism, which will be described later, is in a forward position and the engine


32


operates in the idle speed.




The illustrated air induction system


114


preferably includes an idle or auxiliary air delivery mechanism


158


that can deliver idle air to the combustion chambers


96


when the throttle valves


132


are substantially closed. The downstream portion of the mechanism


158


is connected to the air intake passages


116


downstream of the throttle valve assemblies


130


. Because the illustrated idle air delivery mechanism


158


acts as an idle speed control (ISC) mechanism, the mechanism will be called an as ISC mechanism for short within this description unless otherwise indicated. The ISC mechanism


158


will be described in greater detail later, primarily with reference to

FIGS. 4 and 5

.




The engine


32


also includes an exhaust system that routes burnt charges, i.e., exhaust gases, to a location outside of the outboard motor


30


. Each cylinder head assembly


92


,


94


defines a set of inner exhaust passages


162


that communicate with the combustion chambers


96


through one or more exhaust ports


164


, which may be defined at the inner surfaces of the respective cylinder head assemblies


92


,


94


. The exhaust ports


164


can be selectively opened and closed by exhaust valves


166


. The construction of each exhaust valve and the arrangement of the exhaust valves are substantially the same as the intake valve and the arrangement thereof, respectively. Thus, further description of these components is deemed unnecessary.




Exhaust manifolds preferably are defined generally vertically within the cylinder block


84


between the cylinder bores


86


of both the cylinder banks B


1


, B


2


. The exhaust manifolds communicate with the combustion chambers


96


through the inner exhaust passages


162


and the exhaust ports


164


to collect exhaust gases therefrom. The exhaust manifolds are coupled with the exhaust discharge passage of the exhaust guide member


80


. When the exhaust ports


164


are opened, the combustion chambers


96


communicate with the exhaust discharge passage through the exhaust manifolds.




A valve cam mechanism preferably is provided for actuating the intake and exhaust valves


124


,


166


in each cylinder bank B


1


, B


2


. Preferably, the valve cam mechanism includes one or more camshafts per cylinder bank, which camshafts extend generally vertically and are journaled for rotation relative to the cylinder head assemblies


92


,


94


. The camshafts have cam lobes to push valve lifters that are affixed to the respective ends of the intake and exhaust valves


124


,


166


in any suitable manner. The cam lobes repeatedly push the valve lifters in a timed manner, which is in proportion to the engine speed. The movement of the lifters generally is timed by rotation of the camshafts to appropriately actuate the intake and exhaust valves


124


,


166


.




A camshaft drive mechanism (not shown) preferably is provided for driving the valve cam mechanism. Thus, the intake and exhaust camshafts comprise intake and exhaust driven sprockets positioned atop the intake and exhaust camshafts, respectively, while the crankshaft


104


has a drive sprocket positioned atop thereof. A timing chain or belt is wound around the driven sprockets and the drive sprocket. The crankshaft


104


thus drives the respective camshafts through the timing chain in the timed relationship. Because the camshafts must rotate at half of the speed of the rotation of the crankshaft


104


in a four-cycle engine, a diameter of the driven sprockets is twice as large as a diameter of the drive sprocket.




The engine


32


preferably has indirect, port or intake passage fuel injection. The fuel injection system preferably comprises six fuel injectors


170


with one fuel injector allotted for each one of the respective combustion chambers


96


. The fuel injectors


170


preferably are mounted on the throttle bodies


131


and a pair of fuel rails connects the respective fuel injectors


170


with each other on each cylinder bank B


1


, B


2


. The fuel rails also define portions of the fuel conduits to deliver fuel to the injectors


170


.




Each fuel injector


170


preferably has an injection nozzle directed downstream within the associated intake passage


116


, which is downstream of the throttle valve assembly


130


. The fuel injectors


170


spray fuel into the intake passages


130


, as indicated by the arrows


171


of

FIG. 2

, under control of an electronic control unit (ECU)


172


. Control signals of the fuel injectors


170


are transmitted to the fuel injectors


170


from the ECU


172


through control lines


174


. The ECU


172


controls both the initiation timing and the duration of the fuel injection cycle of the fuel injectors


170


so that the nozzles spray a proper amount of fuel each combustion cycle.




The ECU


172


preferably is disposed between a forward surface of the crankcase member


100


and the plenum chamber unit


134


on the port side, and preferably is mounted on the forward surface of the crankcase member


100


. Air is drawn over the ECU


172


to help cool the ECU during operation of the engine.




Typically, a fuel supply tank disposed on a hull of the associated watercraft


40


contains the fuel. The fuel is delivered to the fuel rails through the fuel conduits and at least one fuel pump, which is arranged along the conduits. The fuel pump pressurizes the fuel to the fuel rails and finally to the fuel injectors


170


. A vapor separator


176


preferably is disposed along the conduits to separate vapor from the fuel and can be mounted on the engine body


110


at the side surface on the port side. In the illustrated embodiment, a vapor delivery conduit


174


couples the vapor separator


176


with at least one of the plenum chambers


118


. The vapor thus can be delivered to the plenum chamber


118


for delivery to the combustion chambers


96


together with the air for combustion. In other applications, the engine


32


can be provided with a ventilation system arranged to send lubricant vapor to the plenum chambers. In such applications, the fuel vapor also can be sent to the plenum chambers via the ventilation system. The fuel injection system and the vapor separator are disclosed, for example, in U.S. Pat. Nos. 5,873,347, 5,915,363 and 5,924,409, the disclosures of which are hereby incorporated by reference. It should be noted that a direct fuel injection system that sprays fuel directly into the combustion chambers can replace the indirect fuel injection system described above. Moreover, other charge forming devices, such as carburetors, can be used instead of the fuel injection systems.




The engine


32


further comprises an ignition or firing system. Each combustion chamber


96


is provided with a spark plug which preferably is disposed between the intake and exhaust valves


124


,


166


. Each spark plug has electrodes that are exposed into the associated combustion chamber


96


and that are spaced apart from each other with a small gap. The spark plugs are connected to the ECU


172


through appropriate control lines and an ignition device


177


(see FIG.


4


), such as ignition coils


178


, are provided such that ignition timing is controlled by the ECU


172


. In the illustrated embodiment, three ignition coils


178


are provided with one coil


178


allotted to two of the spark plugs. The ignition coils


178


preferably are disposed in line to be spaced apart vertically with each other and are affixed to a bracket


180


by appropriate fasteners such as bolts


181


.




The spark plugs generate a spark between the electrodes to ignite an air/fuel charge in the combustion chamber


96


at selected ignition timing under control of the ECU


172


. The bracket


180


preferably is mounted on a rear surface of the cylinder head assemblies


92


,


94


and can be detachably affixed thereto by appropriate fasteners such as bolts


182


. A cover member


183


also can be detachably affixed to the cylinder head assemblies


92


,


94


by appropriate fasteners, such as bolts


184


, to extend over the entire bracket


180


including the ignition coils


178


. Water thus is effectively inhibited from splashing onto the ignition coils


178


. The bracket


180


and the cover member


183


will be described in greater detail later.




For use by the ECU


172


, the engine


32


may have various sensors. In the illustrated embodiment, a crankshaft angle position sensor


185


preferably is provided to monitor the crankshaft


104


. The angle position sensor


185


, when measuring crankshaft angle versus time, outputs a crankshaft rotational speed signal or an engine speed signal that is sent to the ECU


172


through a sensor signal line


186


. The sensor


185


preferably comprises a pulsar coil positioned adjacent to the crankshaft


104


and a projection or cut formed on the crankshaft


104


. The pulsar coil generates a pulse when the projection or cut passes proximate the pulsar coil. In some arrangements, the number of pulses can be counted. The sensor


185


thus can sense not only a specific crankshaft angle but also a rotational speed of the crankshaft


104


, i.e., engine speed. Of course, other types of speed sensors also can be used.




An air intake pressure sensor


188


preferably is positioned atop the uppermost throttle assembly


130


for the intake passage


116


of the cylinder bank B


1


on the port side. The intake pressure sensor


188


senses the intake pressure in this passage


116


during engine operation. The sensed signal is sent to the ECU


172


through a sensor signal line


190


. This signal can be used for determining engine load. Of course, other suitable placements of the sensor also can be used and other sensors that can determine engine load can be used.




A throttle valve position sensor


192


preferably is provided atop and proximate the valve shaft assembly


133


of the throttle assembly


130


for the intake passage


116


of the cylinder bank B


2


on the starboard side. The throttle valve position sensor


192


senses an opening degree or opening position of the throttle valves


132


on this side. A sensed signal is sent to the ECU


172


through a sensor signal line


194


. Of course, other sensors and placements also can be used.




While the illustrated arrangement features hard-wired sensors and components, the signals can be sent through emitter and detector pairs, infrared radiation, radio waves or the like. The type of signal and the type of connection can be varied between sensors or the same type can be used with all sensors.




In the illustrated engine


32


, the pistons


90


reciprocate between top dead center and bottom dead center. When the crankshaft


104


makes two rotations, the pistons


90


generally move from the top dead center position to the bottom dead center position (the intake stroke), from the bottom dead center position to the top dead center position (the compression stroke), from the top dead center position to the bottom dead center position (the power stroke) and from the bottom dead center position to the top dead center position (the exhaust stroke). During the four strokes of the pistons


90


, the camshafts make one rotation and actuate the intake and exhaust valves


124


,


166


to open the intake and exhaust ports


122


,


164


during the intake stroke and the exhaust stroke, respectively.




Generally, during the intake stroke, air is drawn into the combustion chambers


96


through the air intake passages


116


and fuel is injected into the intake passages


116


by the fuel injectors


170


. The air and the fuel thus are mixed to form the air/fuel charge in the combustion chambers


96


. Slightly before or during the power stroke, the respective spark plugs ignite the compressed air/fuel charge in the respective combustion chambers


96


. The air/fuel charge thus rapidly burns during the power stroke to move the pistons


90


. The burnt charge, i.e., exhaust gases, then are discharged from the combustion chambers


96


during the exhaust stroke.




The engine


32


may comprise a cooling system, a lubrication system and other systems, mechanisms or devices other than the systems described above.




A flywheel assembly


198


preferably is positioned above atop the crankshaft


104


and is mounted for rotation with the crankshaft


104


. The flywheel assembly


198


comprises a flywheel magneto or AC generator that supplies electric power to various electrical components, such as the fuel injection system, the ignition system and the ECU


172


.




With reference again to

FIG. 1

, the driveshaft housing


62


depends from the power head


58


to support a driveshaft


200


which is coupled with the crankshaft


104


and which extends generally vertically through the driveshaft housing


62


. The driveshaft


200


is journaled for rotation and is driven by the crankshaft


104


. The driveshaft housing


62


preferably defines an internal section


202


of the exhaust system that leads the majority of exhaust gases to the lower unit


64


. The internal section


202


includes an idle discharge portion that is branched off from a main portion of the internal section


202


to discharge idle exhaust gases directly out to the atmosphere through a discharge port that is formed on a rear surface of the driveshaft housing


62


in idle speed of the engine


32


. The exhaust internal section


202


is schematically shown in

FIG. 1

to include a portion of the exhaust manifolds and the exhaust discharge passage.




The lower unit


64


depends from the driveshaft housing


62


and supports a propulsion shaft


206


that is driven by the driveshaft


200


. The propulsion shaft


206


extends generally horizontally through the lower unit


64


and is journaled for rotation. A propulsion device is attached to the propulsion shaft


206


. In the illustrated arrangement, the propulsion device is a propeller


208


that is affixed to an outer end of the propulsion shaft


206


. The propulsion device, however, can take the form of a dual counter-rotating system, a hydrodynamic jet, or any of a number of other suitable propulsion devices.




A transmission


210


preferably is provided between the driveshaft


200


and the propulsion shaft


206


, which lie generally normal to each other (i.e., at a 90° shaft angle) to couple together the two shafts


200


,


206


by bevel gears. The outboard motor


30


has a clutch mechanism that allows the transmission


210


to change the rotational direction of the propeller


208


among forward, neutral or reverse.




The lower unit


64


also defines an internal section of the exhaust system that is connected with the internal exhaust section


202


of the driveshaft housing


62


. At engine speeds above idle, the exhaust gases generally are discharged to the body of water surrounding the outboard motor


30


through the internal sections and then a discharge section defined within the hub of the propeller


208


. Incidentally, the exhaust system can include a catalytic device at any location in the exhaust system to purify the exhaust gases.




With primary reference to

FIGS. 2

,


4


and


5


, the ISC mechanism


158


will now be described in greater detail. The ISC mechanism


158


preferably comprises an idle air or auxiliary plenum chamber


220


, an idle air or auxiliary intake passage


222


and an ISC device


224


. Preferably, the idle plenum chamber


220


is defined separately from the primary plenum chambers


118


and is generally disposed in a rear space of the cavity


68


opposite to the plenum chambers


220


. In the illustrated embodiment, the bracket


180


and the cover member


183


together define the idle plenum chamber


220


.




The bracket


180


preferably is made of plastic. As illustrated in

FIG. 5

, the plastic material is shaped, for example, in an injection molding process, to have a generally planar body portion


226


and a chamber portion


228


. The ignition coils


180


are mounted on the body portion


226


that is affixed to the cylinder head assemblies


92


,


94


. The chamber portion


228


preferably is disposed in a recessed space


230


that is formed between the cylinder head assemblies


92


,


94


as seen in FIG.


5


. Advantageously, such a construction provides a compact construction that can reduce the overall size of the engine. In the illustrated arrangement, the recessed space


230


is positioned above the uppermost ignition coil


178


as seen in FIG.


4


. The chamber portion


228


defines a recess


232


, which is disposed within the recessed space


230


, that is generally configured as a triangular shape in a rear view and opens toward the cover member


183


in the illustrated arrangement. Any other configuration, such as a circular shape, also can be used instead of the triangular shape. A rim or flange


234


extends toward the cover member


183


generally in parallel to the longitudinal center plane


88


.




The cover member


183


, which preferably is made of plastic also, is shaped, for example, in an injection process to have a cover portion


236


and a counter-chamber portion


238


. Preferably, the cover portion


236


almost entirely covers not only the bracket


180


but also a large area of the cylinder head assemblies


92


,


94


. A sub-chamber


237


thus is formed therebetween that can act as an air coordinator and/or a silencer. Air within the cavity


68


can enter the sub-chamber


237


through gaps defined between the cover portion


236


and the cylinder head assemblies


92


,


94


.




The counter-chamber portion


238


in turn is disposed at a location corresponding to the location of the bracket


180


where the chamber portion


228


of the bracket


180


is positioned. The chamber portion


238


includes a rim or flange


240


extending toward the bracket


180


generally in parallel to the longitudinal center plane


88


. A recess


242


also is formed therein as a triangular shape that is analogous to the triangular shape of the recess


232


. Any other configurations such as a circular shape can of course be used instead of the triangular shape. Preferably, the shape of the recess


242


and the shape of the recess


232


are complementary.




In the illustrated embodiment, the rim


240


of the cover member


183


is slightly larger than the rim


234


of the bracket


180


, and is slightly overlapped with the rim


234


. It should be noted, however, the size of each rim


234


,


240


is interchangeable. Air, thus, is drawn through a gap defined between the rim


240


and the corresponding rim


234


.




As thus constructed and arranged, the idle plenum chamber


220


coordinates air therein and/or acts as a silencer. The idle plenum chamber


220


is defined with both of the recesses


232


,


242


. That is, an idle or auxiliary plenum chamber unit or voluminous unit


244


is formed with both the chamber portion


228


of the bracket


180


and the chamber portion


238


of the cover member


183


. The idle plenum chamber


220


is disposed opposite to the bracket assembly


36


relative to the engine body


110


, while the primary plenum chambers


118


are disposed between the bracket assembly


36


and the engine body


110


. The bracket


180


and the cover member


183


can be made of sheet metal in some arrangements. In such arrangements, they can be shaped in a press process, for example.




Because the respective size of the rims


234


,


240


are different from one another, a triangular opening or gap


248


is made between the rims


234


,


240


. The opening


248


can be an inlet port of the plenum chamber


220


. The chamber portion


228


of the bracket


180


defines a projection


252


through which an aperture


254


is formed. The aperture


254


can be an outlet port of the plenum chamber


220


.




A housing of the ISC device


224


preferably is disposed atop a portion of the upper-most intake conduit


128


of the cylinder bank B


1


on the port side downstream of the throttle valve assembly


130


and can be affixed thereto by appropriate fasteners, such as bolts. The idle air intake passage


222


connects the control device


224


with the idle plenum chamber


220


and with the respective intake passages


116


. The illustrated ISC device


224


is an ISC valve that preferably is formed with, for example, a needle valve or solenoid valve to measure or regulate an amount of idle air flowing therethrough under control of the ECU


172


. A control line for the ISC valve is omitted in the figures. That is, the needle valve or solenoid valve can move between an open position and a closed position, which disables communication between the idle plenum chamber


220


and the intake passages


116


.




The ECU


172


preferably opens the ISC valve


224


when the throttle valves


132


of the primary intake passages


116


are almost closed. Desirably, the opening degree of the ISC valve


224


can be changed to selectively maintain the foregoing trolling condition.




In some occasions, such as when the operator suddenly operates the throttle valves


132


to increase the air amount, i.e., to abruptly accelerate the engine speed, a huge amount of air, which is more than accommodated by the maximum airflow through the intake conduits


116


, can be required. The ECU


172


preferably senses sudden acceleration if the signal of the intake pressure sensor


188


and/or the signal of the throttle position sensor


192


indicates that the air flow in the intake passages


116


increases and a change rate of at least one of the signals is greater than a preset ratio. The ECU


172


, when sudden acceleration is sensed, can control the ISC valve


224


via the device


224


to allow additional air to flow to the engine


32


. The ISC device or valve


224


, in some occasions, can be omitted. The device, however, is advantageously provided for accurate control of the idle or trolling engine speeds and/or to better facilitate sudden acceleration.




The idle air intake passage


222


preferably comprises three flexible intake conduits


260


,


262


,


264


made of a flexible material such as, for example, rubber material. The first conduit


260


extends generally horizontally over at least a portion of the cylinder head assembly


92


to couple the idle plenum chamber unit


244


with the idle air control device


224


. The second conduit


262


extends generally vertically aside the respective intake conduits


128


of the cylinder bank B


1


on the port side and downstream of the throttle valve assemblies


130


to couple the ISC device


224


with the respective intake conduits


128


of the cylinder bank B


1


. The third conduit


264


extends generally horizontally over both of the cylinder head assemblies


92


or the cylinder block


84


to couple the ISC device


224


with the respective conduits


128


of the cylinder bank B


2


on the starboard side.




The second and third conduits


262


,


264


also can have branched off portions that define three outlet ports


266


(see FIG.


5


), while the downstream portions of the respective intake conduits


128


have inlet ports


268


. The respective outlet ports


266


of the conduits


266


,


266


can be connected to the inlet ports


268


of the respective intake conduits


128


. As illustrated in

FIG. 5

, the respective downstream portions of the intake conduits


128


have side passages


270


that connect the inlet ports


268


to the intake passages


116


.




The air within the closed cavity


68


is drawn into the sub-chamber


237


defined by the cover portion


236


of the cover member


183


. In this sub-chamber


237


, the air is coordinated and/or the intake noise is reduced to the certain extent. The air then goes into the idle plenum chamber


220


through the triangular opening


248


as indicated by the arrows


274


of FIG.


5


. The air is relatively completely coordinated in this plenum chamber


220


. The intake noise also is substantially completely reduced in the chamber


220


. The air flows into the first flexible conduit


260


through the aperture


254


as indicated by the arrow


276


of FIG.


5


and goes to the ISC valve


224


. The ECU


172


controls the opening degree of the ISC valve


224


in response to the situations such that the throttle valves


132


are almost closed or the sudden acceleration is required. Only the regulated amount of the air thus can pass through the ISC valve


224


. While one portion of the air goes to the downstream portions of the intake passages


116


of the cylinder bank B


1


through the flexible conduit


262


as indicated by the arrow


278


of

FIG. 5

, the other portion of the air goes to the downstream portions of the intake passages


116


of the cylinder bank B


2


through the flexible conduit


264


as indicated by the arrow


280


of FIG.


5


. The air then separately flows into the respective side passages


270


of the intake conduits


128


to go to the respective combustion chambers


96


as indicated by the arrow


281


of FIG.


5


.




As thus described, the illustrated ISC mechanism is connected to the primary intake passages downstream the throttle valve assemblies. Because of this arrangement, no negative pressure that can be produced by the light air flow through the primary intake passages can exert any influence upon the air supply through the ISC mechanism. The idle speed thus can be held in a proper range as initially set. The set idle speed in this embodiment is approximately 700 rpm. Also, under sudden acceleration, if a control is applied, an accurate amount of air can be added to the amount of the air that is supplied through the primary passages. Undesired acceleration speed thus can be avoided accordingly.




Also, the illustrated idle plenum chamber is disposed opposite to the bracket assembly. In other words, the idle plenum chamber is placed at the farthest location from the operator. In addition, the engine body lies between the idle plenum chamber and the operator. Any noise generated within the chamber, even if it occurs, can be isolated from the operator as much as possible accordingly.




The illustrated idle plenum chamber also is separated from the primary plenum chambers. Even if the vapor from the vapor separator is delivered to the intake system, the vapor will not enter the ISC mechanism in the illustrated arrangement. Thus, the air/fuel ratio in the idle speed operation of the engine is not influenced by the vapor because the vapor is not introduced into the ISC mechanism.




The illustrated idle plenum chamber is formed with the bracket and the cover member, which are provided for the ignition coils. Accordingly, no additional members are necessary. The construction thus is simple, neat and inexpensive in comparison with a construction in which particular members are employed.




In the illustrated arrangement, the cover member can form the sub-chamber around the idle plenum chamber. The sub-chamber can enhance the air coordinating effect and/or the silencing effect of the idle plenum chamber further. In addition, the major portion of the idle plenum chamber in the illustrated embodiment is positioned in the space defined between the cylinder head assemblies. The relatively narrow space thus is efficiently used. Further, the chamber portions of the bracket and the cover members including rims are useful for reinforcing the structures.




It should be noted that the idle plenum chamber can be formed with a combination of another bracket and cover member that are provided for electric components or engine components other than the ignition coils. Any other bracket members and/or cover members can replace the bracket and the cover member, respectively. Also, the plenum chamber can be formed with a member other than a cover member. Moreover, the plenum chamber can be formed with a single piece. In some applications, the ISC valve


224


can be disposed within the subchamber


237


or idle plenum chamber


220


such that the conduit


260


can be removed.





FIGS. 6 and 7

illustrate another exemplary construction and arrangement of the idle plenum chamber. The same members and components as those which are already described will be assigned with the same reference numerals and will not be described repeatedly.




An idle plenum chamber


288


, i.e., an idle plenum chamber unit


290


, in this construction is formed with the bracket


180


and a plate


292


which acts as a lid for the recess


232


of the chamber portion


228


. The plate


292


preferably is configured generally as a triangular shape that is generally consistent with the triangular shape of the chamber portion


228


and is affixed to the chamber portion


228


by appropriate fasteners such as bolts


294


. Preferably, three bolts


294


are used so that each corner of the triangular configuration has the bolt


294


. Boss portions


296


where the bolts


294


are positioned protrude more rearwardly than other portions. In other words, the rear edges


298


extending between the boss portions


296


are positioned slightly forwardly of the rear ends of the boss portions


296


. Thus, slots


300


are formed between the respective boss portions


296


. Air can enter the idle plenum chamber


288


through the slots


300


as indicated by the arrow


302


of

FIGS. 6 and 7

. The air goes to the idle intake passage


222


through the opening


254


as indicated by the arrow


276


of

FIGS. 6 and 7

.





FIGS. 8 and 9

illustrate a further exemplary construction and arrangement of the idle plenum chamber. Again, the same members and components as those which are already described will be assigned with the same reference numerals and will not be described repeatedly.




An idle plenum chamber


310


, i.e., an idle plenum chamber unit


312


, in this construction is formed solely with the bracket


180


. The plenum chamber unit


312


has a projection


314


extending generally forwardly in parallel to the projection


252


. The projection


314


defines an inlet port


316


of the plenum chamber


310


. Air can enter the idle plenum chamber


310


through the inlet port


316


as indicated by the arrow


318


of

FIGS. 8 and 9

. The air goes to the idle intake passage


222


through the opening


254


as indicated by the arrow


276


of

FIGS. 8 and 9

. The chamber portion


238


, i.e., the rim


240


, of the cover member


183


can be omitted in this arrangement.




Of course, the foregoing description is that of a preferred construction having certain features, aspects and advantages in accordance with the present invention. Various changes and modifications may be made to the above-described arrangements without departing from the spirit and scope of the invention, as defined by the appended claims. For instance, the inlets to the idle plenum chambers of the various configurations can be mixed together such that more than one inlet variation is used in a single construction. Accordingly, the scope of the present invention should not be limited to the illustrated configurations, but should only be limited to a fair construction of the claims that follow and any equivalents of the claims.



Claims
  • 1. An internal combustion engine comprising an engine body and an air induction system, the engine body comprising a cylinder block defining a cylinder bore, a piston reciprocally mounted in the cylinder bore, and a cylinder head assembly closing an end of the cylinder bore to define a combustion chamber together with the cylinder bore and the piston, the air induction system arranged to introduce air into the combustion chamber, the induction system including a first intake conduit through which the air flows to the combustion chamber, a first plenum chamber unit being disposed upstream of the first intake conduit and communicating with the first intake conduit, a control mechanism arranged to control an amount of the air flowing through the first intake conduit, a second intake conduit through which the air flows to the combustion chamber, and a second plenum chamber unit being disposed upstream of the second intake conduit and communicating with the second intake conduit, the second intake conduit being coupled with the first intake conduit downstream of the control mechanism and the second plenum chamber unit having an air supply separate from the first intake conduit.
  • 2. The engine as set forth in claim 1, wherein the second plenum chamber unit includes a first member and a second member which define a chamber.
  • 3. The engine as set forth in claim 2, wherein the first member defines a first recess, the second member defines a second recess, the first and second members meet together so that the first and second recesses form the chamber with each other.
  • 4. The engine as set forth in claim 3, wherein one of the first and second members defines a port communicating with the second intake conduit.
  • 5. The engine as set forth in claim 3, wherein the first member has a first rim portion defining the first recess, the second member has a second rim portion defining the second recess, one of the first and second rim portions is formed larger than the other one of the first and second rim portions, and the larger rim portion encases the other rim portion at least in part.
  • 6. The engine as set forth in claim 5, wherein the first and second rim portions together define an opening therebetween through which the air is introduced into the plenum chamber.
  • 7. The engine as set forth in claim 2, wherein at least one of the first and second members is affixed to the engine body.
  • 8. The engine as set forth in claim 7, wherein at least one of the first and second members is affixed to the cylinder head assembly.
  • 9. The engine as set forth in claim 7, wherein the other one of the first and second members is affixed to the engine body at a location other than a location where the first member is affixed.
  • 10. The engine as set forth in claim 7 additionally comprising an engine component relating to an operation of the engine, wherein one of the first and second members defines a mount portion at which the engine component is mounted.
  • 11. The engine as set forth in claim 10, wherein the other one of the first and second members defines a cover portion to cover the engine component.
  • 12. The engine as set forth in claim 10 additionally comprising an ignition system arranged to ignite the combustion chamber, wherein the engine component includes a component relating to the ignition system.
  • 13. The engine as set forth in claim 2, wherein the first and second members together define an opening therebetween through which the air is introduced into the chamber.
  • 14. The engine as set forth in claim 2, wherein the first member defines a recess, the second member defines a lid generally covering the recess, and the recess and the lid together form the chamber.
  • 15. The engine as set forth in claim 14, wherein the first and second members together define an opening therebetween through which the air is introduced into the chamber.
  • 16. The engine as set forth in claim 14, wherein the first member defines a port communicating with the second intake conduit.
  • 17. The engine as set forth in claim 14, wherein the first member is affixed to the engine body.
  • 18. The engine as set forth in claim 14, wherein the second member is affixed to the first member.
  • 19. The engine as set forth in claim 1 additionally comprising a space forming member affixed to the engine body to form a space together with the engine body, wherein the second plenum chamber unit is disposed within the space.
  • 20. The engine as set forth in claim 19, wherein the second plenum chamber unit defines an opening communicating with the space.
  • 21. The engine as set forth in claim 19, wherein the second plenum chamber unit is affixed to the engine body.
  • 22. The engine as set forth in claim 21, wherein both the space forming member and the second plenum chamber unit are affixed to the cylinder head member.
  • 23. The engine as set forth in claim 1, wherein the cylinder block defines at least two cylinder bores forming a V configuration with one another, two of the cylinder head assemblies close the respective cylinder bores, and the second plenum chamber unit, at least in part, is disposed between the cylinder head assemblies.
  • 24. The engine as set forth in claim 1 additionally comprising a fuel injection system arranged to spray fuel for combustion toward the combustion chamber, the fuel injection system including a vapor separator and a vapor delivery conduit coupling the vapor separator with the first plenum chamber unit.
  • 25. The engine as set forth in claim 1, wherein the first plenum chamber unit includes a silencer.
  • 26. The engine as set forth in claim 1, wherein the second plenum chamber unit includes a silencer.
  • 27. An internal combustion engine for powering a marine propulsion device comprising an engine body and an air induction system, the engine body comprising a cylinder block defining a cylinder bore, a piston reciprocally mounted in the cylinder bore, and a cylinder head assembly closing an end of the cylinder bore to define a combustion chamber together with the cylinder bore and the piston, the air induction system arranged to introduce air into the combustion chamber, the induction system including a first intake conduit through which the air flows to the combustion chamber, a first plenum chamber unit being disposed upstream of the first intake conduit, a control mechanism arranged to control an amount of the air flowing through the first intake conduit, a second intake conduit through which the air flows to the combustion chamber, and a second plenum chamber unit being disposed upstream of the second intake conduit, the second intake conduit being coupled with the first intake conduit downstream of the control mechanism.
  • 28. The engine as set forth in claim 27, wherein the air flows through the second intake conduit to the combustion chamber when the control mechanism generally inhibits the air from flowing through the first intake conduit to the combustion chamber.
  • 29. The engine as set forth in claim 27 additionally comprising a second control mechanism arranged to control an amount of the air flowing through the second intake conduit.
  • 30. The engine as set forth in claim 29, wherein the second control mechanism allows the air to flow through the second intake conduit to the combustion chamber when further air is necessary in addition to the air flowing through the first intake conduit to the combustion chamber.
  • 31. The engine as set forth in claim 27, wherein the first and second plenum chamber units are disposed opposite to each other relative to the engine body.
  • 32. The engine as set forth in claim 27, wherein the cylinder block defines a plurality of cylinder bores extending generally horizontally and spaced apart vertically from each other, and the second intake conduit at least in part extends above the engine body.
  • 33. The engine as set forth in claim 27, wherein the engine operates on a four-cycle combustion principle.
  • 34. An internal combustion engine comprising an engine body, a moveable member moveable relative to the engine body, movement of the moveable member being transferred to a marine propulsion device, the engine body and the moveable member together at least partially defining a combustion chamber, an air induction system arranged to introduce air into the combustion chamber, the induction system including a primary intake conduit through which the air flows to the combustion chamber, a first voluminous unit disposed upstream of and communicating with the primary intake conduit, a throttle valve arranged to control an amount of the air flowing through the primary intake conduit, the throttle valve generally allowing the majority of the air to flow through the primary intake conduit at an engine speed above an idle speed, an auxiliary intake conduit through which air at the idle speed flows to the combustion chamber, and a second voluminous unit disposed upstream of the auxiliary intake conduit, the auxiliary intake conduit communicating with the primary intake conduit downstream of the throttle valve.
  • 35. The engine as set forth in claim 34, wherein the second voluminous unit includes a first member and a second member that together at least partially define a voluminous chamber therein.
  • 36. The engine as set forth in claim 35, wherein the first member defines a first recess, the second member defines a second recess, the first and second members meet together so that the first and second recesses form the voluminous chamber with each other.
  • 37. The engine as set forth in claim 35, wherein at least one of the first and second members is affixed to the engine body.
  • 38. The engine as set forth in claim 35, wherein the first and second members together define an opening therebetween through which the air is introduced into the voluminous chamber.
  • 39. The engine as set forth in claim 35, wherein the first member defines a recess, the second member defines a lid generally covering the recess, and the recess and the lid together form the voluminous chamber.
  • 40. The engine as set forth in claim 34 additionally comprising a space forming member affixed to the engine body to form a space together with the engine body, wherein the second voluminous unit is disposed within the space.
  • 41. The engine as set forth in claim 34 additionally comprising a control valve arranged to control an amount of the air flowing through the auxiliary intake conduit, the control valve allowing air to flow through the auxiliary intake conduit at the idle engine speed.
  • 42. The engine as set forth in claim 34 additionally comprising a control valve arranged to control an amount of the air flowing through the auxiliary intake conduit, a sensor to sense a condition of the air flow within the primary intake conduit, and a control device configured to control the control valve based upon a signal of the sensor, wherein the control valve allows air to flow through the auxiliary intake conduit when the signal indicates that the air flow in the primary intake conduit has increased and a change ratio of the signal is greater than a preset ratio.
  • 43. The engine as set forth in claim 34 additionally comprising a fuel injection system arranged to spray fuel for combustion in the combustion chamber, the fuel injection system including a vapor separator that is in communication with the first voluminous chamber.
  • 44. An internal combustion engine comprising an engine body, a moveable member moveable relative to the engine body, the engine body and the moveable member together defining a combustion chamber, an air induction system arranged to introduce air into the combustion chamber, the induction system including an intake conduit through which the air flows, a first member, and a second member together with the first member defining a plenum chamber disposed upstream the intake conduit, both the first and second members being mounted on the engine body, and the first and second members being coupled with one another to form a gap therebetween through which the air enters the plenum chamber.
  • 45. The internal combustion engine as set forth in claim 44, wherein one of the first and second members is a bracket on which an engine component is mounted.
  • 46. The internal combustion engine as set forth in claim 45, wherein the other one of the first and second members is a cover member arranged to cover the engine component.
  • 47. An outboard motor comprising a drive unit, and a bracket assembly adapted to be mounted on an associated watercraft to support the drive unit, the drive unit including an internal combustion engine, the engine comprising an engine body, a moveable member moveable relative to the engine body, the engine body and the moveable member together defining a combustion chamber, an air induction system arranged to introduce air into the combustion chamber, the induction system including a first intake conduit through which the air flows to the combustion chamber, a first plenum chamber unit disposed upstream of the first intake conduit, a control mechanism configured to control an amount of the air flowing through the first intake conduit, a second intake conduit through which the air flows to the combustion chamber, and a second plenum chamber unit disposed upstream of the second intake conduit, the second intake conduit being coupled with the first intake conduit downstream of the control mechanism, and the second plenum chamber unit being disposed opposite to the bracket assembly relative to the engine body.
  • 48. The outboard motor as set forth in claim 47, wherein the first plenum chamber unit is disposed between the bracket assembly and the engine body.
  • 49. The outboard motor as set forth in claim 47, wherein the engine additionally comprises a fuel injection system arranged to spray fuel for combustion in the combustion chamber, the fuel injection system includes a vapor separator, and a vapor delivery conduit couples the vapor separator with the first plenum chamber unit.
  • 50. The outboard motor as set forth in claim 47, wherein the second plenum chamber is only connected to a portion of the first intake conduit located downstream of the control mechanism through the second intake conduit.
  • 51. An internal combustion engine comprising an engine body, a moveable member moveable relative to the engine body, the engine body and the moveable member together at least partially defining a combustion chamber, an air induction system arranged to introduce air into the combustion chamber, the induction system including a primary intake conduit through which the air flows to the combustion chamber, a first voluminous unit disposed upstream of the primary intake conduit, a throttle valve arranged to control an amount of the air flowing through the primary intake conduit, the throttle valve generally allowing the majority of the air to flow through the primary intake conduit at an engine speed above an idle speed, an auxiliary intake conduit through which air at the idle speed flows to the combustion chamber, and a second voluminous unit disposed upstream of the auxiliary intake conduit, the second voluminous unit being only connected to a portion of the primary intake conduit located downstream of the throttle valve through the auxiliary intake conduit.
Priority Claims (1)
Number Date Country Kind
2000-215162 Jul 2000 JP
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Entry
Co-pending patent application: Ser. No. 09/878,323, filed Jun. 11, 2001, entitled Four-Cycle Engine For Marine Drive, in the name of Isao Kanno, and assigned to Sanshin Kogyo Kabushiki Kaisha.
Co-pending patent application: Ser. No. 09/742,777, filed Dec. 20, 2000, entitled Component Mounting Arrangement For Engine, in the name of Hitoshi Watanabe, Akihiro Onoue, and assigned to Sanshin Kogyo Kabushiki Kaisha.
Co-pending patent application: Ser. No. 09/694,080, filed Oct. 19, 2000, entitled Electrical System For Marine Outboard Drive, in the name of Yasuo Suganuma, and assigned to Sanshin Kogyo Kabushiki Kaisha.
Co-pending patent application: Ser. No. 09/626,868, filed Jul. 27, 2000, entitled Engine Control System, in the name of Isao Kanno, and assigned to Sanshin Kogyo Kabushiki Kaisha.
Co-pending patent application: Ser. No. 09/494,395, filed Jan. 31, 2000, entitled Engine Idle Control System, in the name of Isao Kanno, Yoshikazu Nakayasu and assigned to Sanshin Kogyo Kabushiki Kaisha.
Co-pending patent application: Ser. No. 09/497,570, filed Feb. 3, 2000, entitled Fuel Injection For Engine, in the name of Isao Kanno, and assigned to Sanshin Kogyo Kabushiki Kaisha.
Co-pending patent application: Ser. No. 09/422,305, filed Oct. 21, 1999, entitled Idle Speed Control For Engines, in the name of yoshikazu Nakayasu, and assigned to Sanshin Kogyo Kabushiki Kaisha.