Cooling system for marine drive

Information

  • Patent Grant
  • 6675749
  • Patent Number
    6,675,749
  • Date Filed
    Tuesday, March 26, 2002
    22 years ago
  • Date Issued
    Tuesday, January 13, 2004
    21 years ago
Abstract
A marine drive has an open loop cooling system for cooling various engine components using water drawn from the body of water in which an associated watercraft is operating. A water inlet of the cooling system has a filter cover which includes a series of apertures through which water can flow. The apertures have a maximum cross-sectional width. After passing through the water inlet, cooling water is pressurized and directed to an engine coolant passage to cool engine components. A pilot water passage branches off of the engine coolant passage and delivers cooling water through peripheral engine components to cool the components. The pilot cooling water is discharged from the marine drive in a pilot water stream that is visible to the operator of the watercraft. No portion of the pilot water passage has a diameter that is less than the maximum dimension of the water inlet filter cover openings.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




This invention relates to a cooling system for a marine drive.




2. Description of the Related Art




Power driven watercraft typically include a marine drive to propel the watercraft. Marine drives typically include an engine configured to drive a propulsion device. One common type of marine drive is an outboard motor, which comprises an internal combustion engine disposed atop a drive unit. A propulsion device of the drive unit is driven by the engine. The propulsion device is positioned so that it will be at least partially submerged when the associated watercraft is disposed on a body of water. The engine includes a crankcase, a cylinder block, a cylinder head assembly, and at least several other components.




Engine operation generates significant heat. This heat can accumulate in the engine body unless properly removed. Excessive heat can jeopardize normal engine operations. Typical engines thus have a cooling system to remove heat from portions of the engine body and engine components. Various types of cooling systems are employed.




In one type of cooling system, water from the body of water in which the watercraft is being operated is drawn through a water inlet in the drive unit and is pumped through various cooling jackets in order to cool the crankcase, cylinder block, cylinder head assembly, and other engine components, as well as the exhaust system. However, in some applications, different cooling water may be used to cool portions of the engine and portions of the exhaust system. After cooling the engine and/or the exhaust system, the cooling water is returned to the body of water.




If the cooling system malfunctions such that water is no longer supplied at a desired flow rate to certain portions of the engine, the engine can overheat. This can result in serious engine failure such as seizure of the pistons and malfunction of engine components. A pilot water discharge, or “telltale,” is often employed with outboard motors in order to indicate to an operator of the watercraft whether the cooling system is functioning properly. A pilot water discharge assembly generally includes a pilot water passage that branches off the cooling system and delivers a portion of the cooling water to a discharge disposed generally above the body of water. As such, the stream of discharged pilot water is easily visible or audible to the operator.




During normal operation of the cooling system, the stream of discharged pilot water will flow continuously through the pilot discharge. When the flow is continuous, steady and strong, the operator can be confident that the cooling system is working correctly. If the stream of pilot water displays abnormal behavior such as, for example, if the pilot water stream stops or is appreciably diminished, the operator will understand that there is a problem with the cooling system.




The pilot water passage generally has a small inner diameter compared to the water jackets in the engine body and exhaust system. As such, foreign objects that flow freely through the water jackets could become lodged in the relatively small pilot water passage, blocking flow therethrough. A filter is often provided at the point where the pilot water passage branches from the coolant jackets. The filter prevents foreign objects from entering and clogging the pilot water passage. Such a filter must be cleaned periodically to remove foreign debris. Cleaning of the filter takes time and effort and must be done regularly or else the efficacy of the pilot water discharge will be diminished. Also, if any components are to be cooled via the pilot water passage, cooling of such components may be diminished if the filter is not regularly cleaned.




SUMMARY OF THE INVENTION




In accordance with one aspect, the present invention provides an outboard motor comprising a power head having an engine, a driveshaft housing, a lower unit comprising a propulsion device, and an open loop cooling system. The engine drives the propulsion device and has an engine body. The cooling system has a water inlet formed through the lower unit and has at least one opening. An engine coolant passage is formed in the engine body. A pilot water passage receives a flow of water from the water inlet and directs the flow of water through at least one engine component. A minimum cross-sectional dimension of the pilot water passage along its length is never less than a maximum cross-sectional dimension of the at least one water inlet opening.




In accordance with another aspect, a marine drive is provided having an engine, a propulsion device, and an open loop cooling system. The engine is coupled to the propulsion device and has an engine body. The cooling system has a water inlet having at least one opening. An engine coolant passage is formed in the engine body and has an engine coolant discharge. The cooling system also comprises a pilot water passage. A water pump is configured to deliver water from the water inlet to the engine coolant passage and pilot water passage. The pilot water passage directs a flow of water through a pilot water discharge that is spaced from the engine coolant discharge. A cross-sectional dimension of the pilot water passage along its length is no less than a maximum cross-sectional dimension of the at least one water inlet opening.




Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiment which follows.











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 a preferred embodiment, which is intended to illustrate and not to limit the invention. The drawings comprise 10 figures.





FIG. 1

is a side elevational view of an outboard motor comprising a cooling system arranged in accordance with an embodiment of the present invention. A number of cooling system and engine components are shown in phantom. A watercraft associated with the outboard motor is partially shown in section.





FIG. 2

is a side elevational view of a power head of the outboard motor of

FIG. 1

, which includes an engine disposed within a cowling (shown in phantom). A pilot water passage of the cooling system is also shown.





FIG. 3

is a top plan view of the power head of FIG.


2


.





FIG. 4

is an enlarged plan view of a water inlet cover for use with the outboard motor of FIG.


1


.





FIG. 5

is a cross-sectional view of the water inlet cover taken along line


5





5


of FIG.


4


.





FIG. 6

is a partial sectional view of a portion of the engine body, and shows an upstream end of the pilot water passage of

FIG. 2

branching off of a coolant passage of an engine.





FIG. 7

shows a cooling jacket associated with a rectifier-regulator of an electrical system of the outboard motor. The cooling jacket is disposed within the pilot water passage of FIG.


2


.





FIG. 8

is a cross-sectional view of the rectifier-regulator of

FIG. 7

taken along line


8





8


of FIG.


7


.





FIG. 9

shows a cross-sectional view of a fuel cooler system having features in accordance with the present invention and disposed within the pilot water passage of FIG.


2


.





FIG. 10

is a sectional view of a discharge nozzle of the pilot water passage of FIG.


2


.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT




With reference first to

FIGS. 1-3

, an overall construction of an outboard motor


30


, which employs a cooling system arranged in accordance with certain features, aspects and advantages of the present invention, will be described. In the illustrated arrangement, the outboard motor


30


comprises a drive unit


32


and a bracket assembly


34


. The bracket assembly


34


supports the drive unit


32


on a transom


36


of an associated watercraft


38


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


38


resting on the surface of a body of water. The bracket assembly


34


preferably comprises a swivel bracket


40


, a clamping bracket


42


, a steering shaft


44


and a pivot pin


46


.




The steering shaft


44


typically extends through the swivel bracket


40


and is affixed to the drive unit


32


. The steering shaft


44


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


40


. The clamping bracket


42


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


36


. The pivot pin


46


completes a hinge coupling between the swivel bracket


40


and the clamping bracket


42


. The pivot pin


46


extends through the bracket arms so that the clamping bracket


42


supports the swivel bracket


40


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


46


. The drive unit


32


thus can be tilted or trimmed about the pivot pin


46


.




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


36


is located, and the terms “rear,” “reverse,” “backwardly” and “rearwardly” mean at or to the opposite side of the front side, unless indicated otherwise or otherwise readily apparent from the context use.




A hydraulic tilt and trim adjustment system preferably is provided between the swivel bracket


40


and the clamping bracket


42


to tilt (raise or lower) the swivel bracket


40


and the drive unit


32


relative to the clamping bracket


42


. Otherwise, the outboard motor


30


can have a manually operated system for tilting the drive unit


32


. 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


32


comprises a power head


48


, a driveshaft housing


50


and a lower unit


52


. The power head


48


is disposed atop the drive unit


32


and comprises an internal combustion engine


54


that is positioned within a protective cowling


56


. The protective cowling


56


preferably defines a generally closed cavity


58


in which the engine


54


is disposed. In the illustrated embodiment, the protective cowling


56


comprises a top cowling member


60


and a bottom cowling member


62


. The top cowling member


60


is preferably detachably affixed to the bottom cowling


62


by a coupling mechanism


64


so that a user, operator, mechanic or repair person can access the engine


54


for maintenance or for other purposes.




The top cowling


60


preferably has at least one air intake opening (not shown) and at least one air duct disposed on its rear and top portion. Ambient air is drawn into the closed cavity


58


from within the opening through the duct.




The bottom cowling member


62


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


66


extends. The exhaust guide member


66


is affixed atop the driveshaft housing


50


. The bottom cowling member


62


and the exhaust guide member


66


together generally form a tray. The engine


54


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


66


. The exhaust guide member


66


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


54


are discharged.




The engine


54


in the illustrated embodiment operates on a four-stroke combustion principle. With particular reference to

FIGS. 2 and 3

, the engine


54


has a cylinder block


68


which defines six cylinder bores disposed in two banks


70


L,


70


R of three cylinders each. Each bore extends generally horizontally and is generally vertically spaced from the other bores in the bank. The cylinder banks


70


L,


70


R extend generally vertically and are oriented generally in a “V” shape relative to one another. The term “horizontally” means that the subject portions, members or components extend generally in parallel to the surface of the body of water in which the associated watercraft is resting when the drive unit


32


is not tilted and 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 “V-6” engine merely exemplifies one type of engine on which various aspects and features of the present invention can be suitably used. Engines having other number of cylinders, having other cylinder arrangements (e.g., in line), 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 the illustrated embodiment, each cylinder bore has a piston reciprocatedly disposed therein. A cylinder head assembly


72


L,


72


R is attached to each cylinder bank


70


L,


70


R and closes the end of each bore in the respective cylinder bank. Combustion chambers are defined between each associated cylinder head assembly


72


L,


72


R, cylinder bore and piston. A crankcase cover


74


closes the other end of the cylinder block and defines a crankcase chamber


76


together with the cylinder block. A crankshaft


78


extends generally vertically through the crankcase chamber


76


. Connecting rods couple the crankshaft


78


with the respective pistons so that reciprocating movement of the pistons drives the crankshaft


78


.




Generally, the cylinder block


68


, the cylinder head members


72


L,


72


R and the crankcase chamber


76


together define an engine body


80


. The crankcase


76


is preferably located at the most forward position of the engine body


80


, with the cylinder block


68


and the cylinder head member


72


extending rearward from the crankcase, one after another. Preferably, at least these major engine portions


68


,


72


,


76


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


80


.




With continued reference to

FIGS. 1-3

, an air induction system


82


of the engine draws air from within the cavity


58


of the cowling and delivers it to the combustion chambers. The air induction system


82


preferably comprises a plenum chamber


84


and two intake manifolds


86


L,


86


R, one manifold on each side of the engine. Each manifold


86


L,


86


R comprises three intake runners. Air enters the plenum chamber


84


and is delivered by the runners to respective combustion chambers. In one configuration, intake valves open and close respective intake ports in the cylinder head assemblies


72


L,


72


R in order to regulate delivery of air to the combustion chambers.




The engine


54


also comprises an exhaust system that discharges the burnt charges or exhaust gases to a location outside of the outboard motor


30


. Exhaust ports are defined in each cylinder head assembly


72


L,


72


R to provide access to each combustion chamber. The exhaust ports are repeatedly opened and closed by exhaust valves to regulate flow through the exhaust ports.




An exhaust manifold communicates with the exhaust ports to collect exhaust gases from the combustion chambers through the ports. The exhaust manifold preferably extends generally vertically downwardly to deliver exhaust products to exhaust passages located in the driveshaft housing and lower unit. Exhaust gases preferably are eventually discharged from the motor through exhaust discharge ports.




A valve cam mechanism preferably is provided for actuating the intake and exhaust valves. In the illustrated embodiment, the cylinder head assemblies


72


L,


72


R each journal an intake camshaft (not shown) and an exhaust camshaft


90


. The camshafts extend generally vertically and in parallel to each other. The intake camshaft actuates the intake valves, while the exhaust camshaft


90


actuates the exhaust valves. The respective camshafts have cam lobes to push the intake and exhaust valves in a controlled timing to open and close the intake and exhaust ports. In other embodiments, a single camshaft can replace the intake and exhaust camshafts in a manner that is well known. Of course, other valve drive mechanisms can be employed instead of such a mechanism using one or more camshafts.




A camshaft drive mechanism


92


is provided for driving the valve cam mechanism. As seen in

FIG. 3

, the exhaust camshafts


90


have driven sprockets


94


positioned atop thereof and the crankshaft


78


has a drive sprocket


96


positioned almost atop thereof. A timing chain or belt


98


is wound around the drive and driven sprockets


96


,


94


. The crankshaft


78


thus drives the camshafts


90


through the timing chain


98


in a timed relationship. A tensioner


99


preferably abuts a side of the timing chain


98


so as to give proper tension to the chain


98


. A diameter of the driven sprockets


94


preferably is twice as large as a diameter of the drive sprocket


96


. The exhaust camshafts


90


thus rotate at half of the rotation speed of the crankshaft


78


. The exhaust camshafts


90


, in turn, drive the intake camshafts.




The engine preferably has a fuel injection system (not shown) for delivering fuel to the combustion chambers. The fuel injection system preferably comprises a series of fuel injectors arranged so that one fuel injector is allotted for each of the respective combustion chambers. Any desired type of fuel injection system such as, for example, a port, manifold or direct injection system, can be suitably employed. Of course in other arrangements, carburetors can replace or accompany the fuel injectors.




The fuel injectors deliver fuel under control of an electronic control unit (ECU). The ECU electronically controls the fuel injectors so that a desired amount of fuel is delivered at a selected timing for a selected duration. As such, a proper amount of fuel is delivered to the engine for each combustion cycle. A fuel rail supports and delivers fuel to the fuel injectors.




The fuel injection system further comprises a fuel supply tank that preferably is placed in the hull of the associated watercraft. Fuel is drawn from the fuel tank by a low pressure fuel pump, through a fuel supply conduit, and is delivered to a vapor separator. A high pressure fuel pump preferably is provided in the vapor separator. The high pressure fuel pump pressurizes fuel for delivery to the fuel injectors through delivery conduits and the fuel rails. The fuel injection system can also include a fuel cooler


100


, which will be discussed in more detail below in connection with the cooling system.




The engine


54


also has an ignition or firing system (not shown). Each combustion chamber is provided with a spark plug. The spark plugs have electrodes that are exposed into the associated combustion chamber and that ignite an air/fuel charge in the combustion chamber at selected ignition timing. The ignition system preferably has an ignition coil and an igniter. Ignition timing is controlled by the ECU. In order to enhance or maintain engine performance, the ignition timing can be advanced or delayed in response to various engine running conditions.




The engine


54


also comprises a closed-loop type lubrication system (not shown). The lubrication system comprises a lubricant oil reservoir preferably positioned within the driveshaft housing


50


. An oil pump is provided at a desired location, such as atop the driveshaft housing


50


, to pressurize the oil in the reservoir and to pass the oil through lubricant delivery passages toward engine portions. Engine portions that should be lubricated include, for instance, the crankshaft bearings, the connecting rods and the pistons. Lubricant return passages also are provided to return the oil to the oil reservoir for re-circulation. Preferably, the lubrication system further comprises a filter assembly to remove foreign matter from the oil (e.g., metal shavings, dirt, dust and water) before the oil is recirculated or delivered to the various engine portions.




A flywheel assembly


102


preferably is positioned above the engine body


80


. The flywheel assembly


102


preferably comprises a flywheel magneto or generator that generates electric power (i.e., AC power). A rectifier-regulator assembly


105


is provided to rectify and regulate the AC power generated by the flywheel


102


, and the power is accumulated in a battery so that various electrical components, such as the fuel injection system, the ignition system, and the ECU, can use DC power. The flywheel magneto


162


generally comprises a rotor and a stator and can be constructed in any suitable manner. The battery preferably is placed in the hull of the watercraft.




A protective cover


108


is detachably mounted atop the engine body


80


to extend over at least a portion of the flywheel assembly


102


and the camshaft drive mechanism


92


. The protective cover


108


is useful to protect the flywheel assembly


102


and the drive mechanism


92


, which include moving parts, when the top cowling


60


is detached.




As discussed above, during engine operation, heat builds in the engine body


80


, the exhaust manifold, and in various peripheral engine components disposed around the engine body


80


. The cooling system is provided to help cool such engine portions and engine components.




As used through this description, the term “peripheral engine components” means all systems, apparatus, devices, accessories, conduits, components, members, elements and the other things that are disposed externally around the engine body


80


in connection with engine operations.




With regard to the engine body


80


, an engine coolant passage


110


(see

FIG. 6

) comprises one or more water jackets that preferably extend through or alongside portions of the engine body so that flowing cooling water can remove at least some of the heat accumulating in the engine portions. In a preferred open loop cooling system, cooling water is drawn into the cooling system from the body of water surrounding the outboard motor through a water inlet


112


and is pressurized by a water pump


114


. In other embodiments, the water inlet can operate to scoop water into the cooling system without using a pump when the watercraft is moving forwardly. The water inlet


112


comprises apertures formed through the lower unit


52


at a level that will generally remain submerged when the drive unit


32


is fully or almost fully tilted down. The water pump


114


, in turn, is disposed in the driveshaft housing


50


.




Water drawn through the water inlet


112


is pressurized and delivered to a water supply conduit


118


, which in turn directs the water to the engine coolant passage


110


so that the water flows through the water jackets disposed adjacent portions of the engine. At least some of the water that has cooled the engine portions is discharged from the engine coolant passage


110


into one or more internal portions of the driveshaft housing


50


. The cooling system will be described in more detail below.




As seen in

FIG. 1

, the driveshaft housing


50


depends from the power head


48


and supports a driveshaft


120


which is driven by the crankshaft


78


. The driveshaft


120


extends generally vertically through the driveshaft housing


50


. The driveshaft


120


preferably drives the water pump


114


and the oil pump. The driveshaft housing


50


also defines internal passages which form portions of the exhaust system.




The lower unit


52


depends from the driveshaft housing


50


and supports a propulsion shaft, which is driven by the driveshaft


120


. The propulsion shaft extends generally horizontally through the lower unit


52


. A propulsion device is attached to the propulsion shaft and is powered through the propulsion shaft. In the illustrated arrangement, the propulsion device is a propeller


122


that is affixed to an outer end of the propulsion shaft. 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 preferably is provided between the driveshaft


120


and the propulsion shaft. The transmission couples together the two shafts, which lie generally normal to each other (i.e., at a 90° shaft angle) with bevel gears. The outboard motor


30


has a switchover or clutch mechanism that allows the transmission to change the rotational direction of the propeller


122


among forward, neutral or reverse.




The lower unit


52


also defines an internal passage that forms a discharge section of the exhaust system. At engine speeds above idle, the exhaust gases generally are discharged to the body of water surrounding the outboard motor


30


through the internal passage and finally through an outlet passage defined through the hub of the propeller


122


. Of course, an above-the-water discharge can be provided for lower speed engine operation.




The water that is discharged into the driveshaft housing


50


after cooling the engine preferably is used to cool the internal passages of the driveshaft housing


50


and the lower unit


52


. In one configuration, the water is collected in a portion of the lower unit


52


and then is discharged to the body of water through a discharge port or through the hub of the propeller


122


along with the exhaust gases.




The cooling system will now be described in greater detail. As described above, cooling water is introduced into the motor through the water inlet


112


. With specific reference to

FIGS. 1

,


4


and


5


, the water inlet


112


comprises apertures formed through each side of the lower unit


52


. An inlet cover


125


is positioned over each aperture and is secured in place with a bolt


128


. It is to be understood that another embodiment can employ an aperture on only one side of the lower unit.





FIGS. 4 and 5

more clearly illustrate the water inlet cover


125


. As shown, the cover


125


comprises a plurality of openings


130


which permit water to pass through the cover, but which collectively function as a filter to prevent large debris from entering and fouling the cooling system. In the illustrated embodiment, the openings


130


generally have a rectangular cross-sectional shape, and are arranged in a rectangular grid-like pattern.




Although the water inlet cover openings


130


are small enough to prevent most debris from entering the cooling system, some foreign matter, such as very small rocks, sand and other debris may pass through the openings. In the illustrated embodiment, a diagonal corner-to-corner measurement indicates a maximum dimension D of the openings


130


. Debris larger than the maximum dimension D will be blocked from passing through the openings. Debris small enough to pass through the openings


130


will be small enough to flow through the water jackets of the engine coolant passage


110


without fouling or plugging the passage.




With continued reference to

FIG. 6

, the illustrated openings


130


do not all have the same size and configuration. As such, the maximum cross-sectional dimension of one opening may be greater or less than that of another opening. It is to be understood that D is measured in the opening having the greatest cross-sectional dimension of all of the openings


130


in the cover


125


. Additionally, although the illustrated cover


125


includes many openings


130


, it is to be understood that another embodiment may employ just a few openings or even only one opening.




As shown most clearly in

FIG. 5

, most of the openings


130


are slanted generally forwardly. As such, when the watercraft is moving forwardly through a body of water, water will flow freely into and through the openings


130


and through the water inlet


112


. A radius of curvature of the cover


125


generally matches that of the outer surface of the lower unit


52


about the location of the inlet


112


. As such, each cover


125


fits generally flush with the outer surface of the lower unit. As shown in

FIG. 1

, a series of depressions or channels


132


are formed in the outer surface of the lower unit


52


adjacent and forwardly of the water inlet


112


. The channels


132


help direct water flow into the cover openings


130






Although the illustrated embodiment employs rectangular openings, it is to be understood that openings having other cross-sectional shapes such as, for example, circular or elliptical shapes, can be used. In such embodiments, the maximum dimension D can be the diameter or major axis of the opening.




Water that enters the water inlet


112


is delivered via a conduit


134


to the water pump


114


, which pressurizes the water and delivers the water through the delivery conduit


118


to the engine coolant passage


110


. The engine coolant passage generally comprises a series of water jackets and conduits configured in a generally conventional manner so as to cool various engine components such as the exhaust manifold, cylinder block and cylinder head. In the illustrated embodiment, an upstream end


136


of the engine coolant passage is disposed at the bottom of the engine


54


. The engine coolant passage


110


receives water from the delivery conduit


118


and delivers the cooling water to an exhaust manifold water jacket, further to a cylinder bore water jacket, and then to water jackets in the cylinder head assemblies


72


L,


72


R. Cooling water then drains to an exhaust passage of the exhaust guide to mingle with and cool engine exhaust or to other coolant passages formed in the driveshaft housing


50


.




With particular reference to

FIGS. 2

,


3


and


6


, a pilot water passage


140


branches off of the engine coolant passage


110


at a location near or at the bottom of the engine


54


. More precisely, an upstream end


142


of the pilot water passage


140


is connected to the upstream end


136


of the engine coolant passage


110


.

FIG. 6

shows a portion of a cross section of the engine body


80


taken at the bottom portion of the engine body. At this point, an exhaust passage


144


of the exhaust manifold is formed through the engine body


80


, and a water jacket


146


is formed around and adjacent the exhaust passage


144


. The water jacket


146


comprises the upstream portion


136


of the coolant passage


110


, to which pressurized water from the water pump


114


is delivered via the water delivery conduit


118


.




With continued reference to

FIGS. 2

,


3


and


6


, the upstream end


142


of the pilot water passage


140


connects to the upstream end


136


of the engine coolant passage


110


through a wall


148


of the right cylinder bank


70


R. A hole


150


is formed through the wall


148


and into the coolant passage. A portion of the hole


150


is further removed so as to form a seat


152


. The seat


152


is configured to complementarily accept an elongate tubular connector


160


. The connector


160


fits securely in the seat


152


and extends outwardly from the engine body


80


. In the illustrated embodiment, there is no filter between the pilot water passage


140


and the engine coolant passage


110


.




An inner diameter d


1


of the connector


160


preferably is the same as or greater than the maximum dimension D of the water inlet cover openings


130


. As such, any debris that passes through the water inlet cover


125


will also be able to flow through the connector


160


without obstructing or plugging the connector


160


. The connector


160


has a bump or ridge


162


formed along an outer surface thereof.




In the illustrated embodiment, the pilot water passage


140


comprises rubber tubing


164


that fits over the connector


160


. The inner diameter of the tubing


164


is generally greater than the inner diameter d


1


of the connector


160


, and the hose


164


fits securely over the connector


160


. The rubber tubing


164


preferably has a consistent quality so that the inner diameter remains generally consistent throughout the length of the passage


140


, including bent portions of the passage. Additionally, since the rubber hose


164


is flexible, it is relatively simple to direct the hose to any desired location about the engine


54


in order to deliver pilot cooling water to various engine components, as will be discussed below.




It is to be understood that, in other embodiments, the pilot water passage can comprise other materials such as, for example, flexible or rigid plastic hose and/or metal tubing. Also, hose or tubing of various cross-sectional shapes can be employed, including circular, rectangular, elliptical, and the like.




With reference again to

FIGS. 2 and 3

, the rectifier-regulator assembly


105


is mounted on the crankcase cover


74


of the engine


54


between the engine body


80


and the plenum chamber


84


. As discussed above, the rectifier-regulator


105


rectifies AC power that is generated by the flywheel magneto


102


to DC power, and also regulates the power under a pre-set voltage. The rectification and regulation is accompanied with production of heat; thus, it is desirable to cool the rectifier-regulator. Additionally, heat from the engine body


80


may be transferred to the rectifier-regulator assembly


105


.




With reference also to

FIGS. 7 and 8

, the rectifier-regulator


105


typically is confined within a metallic case


170


. A heat exchange block


172


is attached to a surface of the case


170


. Bolts or other fastening connections, such as adhesives, can be used to couple the block with the case and to attach the rectifier-regulator assembly


105


to the crankcase cover


74


.




A water jacket


174


is defined within the rectifier-regulator block


172


. An inlet hole


176


and an outlet hole


178


are formed through a bottom end


180


of the block


172


. Seat portions


182


are formed in the holes


176


,


178


, and connectors


184


,


186


are securely fit within the seats


182


after the manner discussed above with reference to the upstream end


142


of the pilot water passage


140


. The pilot water hose


164


is connected to the inlet connector


184


so that pilot water that has been drawn from the engine coolant passage


110


is directed into the block water jacket


174


. A second pilot water hose


188


(see

FIG. 2

) is connected to the outlet connector


186


.




A divider wall


190


is disposed within the water jacket


174


between the inlet


184


and outlet


186


. The divider


190


extends upwardly from the bottom


192


of the jacket


174


, stopping short of the top


194


of the jacket. As such, a flow path is defined within the water jacket


174


so that water delivered through the inlet connector


184


flows upwardly toward the top of the water jacket, around an upper end


196


of the divider


190


, and then downwardly to the outlet connector


186


.




The inlet and outlet connectors


184


,


186


preferably are formed similar to the upstream connector


160


discussed above, and have inner diameters d


2


that are the same as or greater than the maximum dimension D of the water inlet cover openings


130


. Also, no part of the block water jacket


174


has a width less than D. As such, any debris that is small enough to pass through the openings


130


will also be able to pass through the connectors


184


,


186


and the block water jacket


174


.




In the illustrated embodiment, the block


172


is made of an aluminum-based alloy. In additional embodiments, other materials, such as stainless steel and brass, can be used to construct the block or can be used as liners within the block in order to better protect the block from corrosion by sea water.




With reference next to

FIGS. 2

,


3


and


9


, the second pilot water hose


188


communicates water from the outlet


186


of the rectifier-regulator assembly


105


to a water inlet


200


of a fuel cooler


100


. As best shown in

FIG. 9

, the fuel cooler


100


comprises a fuel passage


202


and a coolant passage


204


enclosed within a heat exchange block


206


and disposed adjacent one another. The fuel and coolant passages


202


,


204


each have inlets


210


,


200


and outlets


212


,


214


of reduced cross-sectional size relative to the respective passages


202


,


204


. Pilot cooling water that has passed through the rectifier-regulator assembly


105


is delivered to the water inlet connector


200


of the fuel cooler


100


. The fuel passage


202


receives fuel that has been pressurized by the high pressure fuel pump. The pilot cooling water flowing through the coolant passage


204


absorbs heat from the fuel passing through the fuel passage


202


.




The block


206


preferably comprises a material having advantageous heat transfer characteristics, such as an aluminum-based alloy or a copper-based alloy. The fuel passage


202


and cooling passage


204


preferably comprise material having advantageous corrosion resistance properties, such as brass or stainless steel.




Pilot cooling water exits the fuel cooler coolant passage


204


through the water outlet connector


214


, to which a third section


218


of rubber pilot water hose is connected. As with the connectors


160


,


184


,


186


discussed above with reference to the upstream end


142


of the pilot water passage


140


and the rectifier-regulator


105


, the fuel cooler


100


water connectors


200


,


214


have inner diameters d


3


, d


4


that are greater than or equal to the maximum dimension D of the water inlet cover openings


130


. Since the connectors have the smallest diameter of the pilot water passage through the fuel cooler assembly


100


, any debris or foreign matter within the pilot water cooling passage


140


will pass through the fuel cooler assembly without plugging or blocking the passage


204


therethrough.




Cooling the fuel is advantageous because, except under very cold conditions, the fuel generally should not be heated or warmed by engine heat. Excessive heating can cause the fuel to vaporize or can otherwise decrease fuel density. By cooling the fuel, the likelihood of vapor lock and/or deposit in the fuel injectors can be decreased. In addition, the accuracy of the fuel injection amount can be improved by cooling the fuel to a pre-set temperature range and maintaining the fuel temperature in this general range. It is to be understood that a fuel cooler


100


having any suitable manner of heat exchanger construction can also be disposed along the fuel system at other locations. For example, one or more fuel coolers can be disposed directly on one or more fuel rails.




With reference again to

FIGS. 2 and 3

, the pilot water passage


140


terminates at a pilot water discharge nozzle


220


, through which water is discharged from the passage.

FIG. 10

shows a cross-sectional view of the nozzle


220


. An upstream end


222


of the nozzle


220


includes a ridge portion


224


and is configured so that the third pilot water hose


218


can be securely held thereon. A downstream end


226


of the nozzle includes a flange


228


configured to hold the nozzle


220


adjacent an outer surface of the cowling


60


. An elongate inner passage


230


communicates coolant water from the pilot water passage


140


out of the motor


30


. The inner passage


230


preferably is tapered so that the inner diameter decreases from the upstream end


222


to the downstream end


226


. This helps to increase the velocity of the pilot water flow so that the stream of discharged pilot water is easily visible to the watercraft operator. However, the smallest diameter d


5


of the inner passage


230


is still greater than or equal to the maximum dimension D of the water inlet cover openings


130


. It is to be understood that, in additional embodiments, the nozzle's inner passage can have a generally uniform diameter.




In the illustrated embodiment, the connectors


160


,


184


,


186


,


200


,


214


and discharge nozzle


220


have the smallest diameter of any portion of the pilot water passage


140


, including the sections of rubber tubing


164


,


188


,


218


and the heat exchange blocks


172


,


206


. However, each of the connectors and the nozzle still has an inner diameter greater than or equal to the maximum dimension D of the water inlet cover openings


130


. As such, no portion of the pilot water passage


140


, which extends from the hole


150


that accesses the engine coolant passage


110


to the downtream end


226


of the nozzle


200


, has a diameter less than the maximum dimension D. Any debris or foreign matter that is small enough to be drawn through the openings


130


is also small enough to pass completely through the pilot water passage


140


without blocking or otherwise impeding the flow of water therethrough. Additionally, since the coolant is pressurized, there is further impetus to force such debris through the pilot water passage


140


. Accordingly, no filter is required at the junction where the pilot water passage


140


branches off of the engine coolant passage


110


.




In an additional embodiment, portions of the pilot water passage may have an inner diameter less than the inner diameter of the connectors; however, the inner diameter of the pilot water passage preferably is never less than the maximum dimension D of the water inlet cover openings


130


.




In the illustrated embodiment, and as shown in

FIGS. 2 and 3

, the pilot water passage


140


directs relatively cool water through a rectifier-regulator assembly


105


and through a fuel cooler before directing the water out of the discharge nozzle


220


and back to the body of water from which the water was obtained. It is to be understood, however, that additional embodiments can use the pilot water passage to cool any number of engine components. For example, components of the flywheel, lubrication system, induction system, and even the ECU can advantageously be cooled by pilot water.




Since the pilot water passage


140


connects to the upstream portion of the engine coolant passage, the coolant has not yet absorbed much heat from the engine, and is relatively cool. Accordingly, this coolant can cool engine components more effectively than coolant taken from a point further downstream in the engine coolant passage, which will have absorbed significant heat from the cylinder bores and the like.




In the illustrated embodiment, the pilot water passage


140


branches off of the engine coolant passage from an exhaust manifold water jacket. It is to be understood, however, that a pilot water passage can be branched off of the engine coolant passage at any point along the passage such as, for example, from a water jacket in the cylinder bore or cylinder head of the passage. Additionally, in another embodiment, a pilot water passage branches off of the water delivery conduit


118


before the conduit delivers water to the engine coolant passage. Still further, the pilot water passage can have its own delivery conduit separate from the conduit


118


that delivers water to the engine coolant passage.




The rectifier-regulator


105


and fuel cooler


100


discussed above each comprise heat exchanger blocks


172


,


206


through which pilot cooling water flows in order to absorb heat. It is to be understood that these blocks represent examples of heat exchangers, and that any suitable type or style of heat exchanger can advantageously be used.




Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other additional embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.



Claims
  • 1. An outboard motor comprising a power head having an engine, a driveshaft housing, a lower unit comprising a propulsion device, and an open loop cooling system, the engine driving the propulsion device and having an engine body, the cooling system comprising a water inlet formed through the lower unit and having at least one opening, an engine coolant passage formed in the engine body, and a pilot water passage, the pilot water passage receiving a flow of water from the water inlet and directing the flow of water through at least one engine component, and a minimum cross-sectional dimension of the pilot water passage along its length is never less than a maximum cross-sectional dimension of the at least one water inlet opening.
  • 2. The outboard motor of claim 1, wherein the pilot water passage branches off of the engine coolant passage.
  • 3. The outboard motor of claim 2, wherein there is no filter adjacent an upstream end of the pilot water passage.
  • 4. The outboard motor of claim 2, wherein the engine coolant passage comprises an exhaust cooling jacket and an engine body cooling jacket, and the pilot water passage branches off of the exhaust cooling jacket.
  • 5. The outboard motor of claim 2, wherein the pilot water passage branches off of the engine coolant passage before water in the engine coolant passage absorbs significant heat from engine components.
  • 6. The outboard motor of claim 1, wherein a water pump pressurizes water from the water inlet and delivers pressurized cooling water through a water delivery conduit, and the pilot water passage branches off the water delivery conduit upstream of the engine coolant passage.
  • 7. The outboard motor of claim 1, wherein the pilot water passage delivers cooling water adjacent at least one peripheral engine component before being discharged from the drive.
  • 8. The outboard motor of claim 7, wherein the peripheral component comprises a rectifier-regulator assembly having a heat exchanger portion.
  • 9. The outboard motor of claim 7, wherein the peripheral component comprises a fuel cooler.
  • 10. The outboard motor of claim 7, wherein the pilot water passage comprises tubing, and the peripheral engine component comprises a connector configured to engage the tubing, and a minimum dimension of the connector no less than the maximum dimension of the at least one water inlet cover opening.
  • 11. The outboard motor of claim 7, wherein the water inlet comprises at least one aperture formed through the lower unit, and a cover is disposed in the aperture, the cover having a curvature generally matching a curvature of the lower unit adjacent the aperture, and the at least one opening is formed through the cover.
  • 12. A marine drive comprising an engine, a propulsion device, and an open loop cooling system, the engine coupled to the propulsion device and having an engine body, the cooling system comprising a water inlet having at least one opening, an engine coolant passage formed in the engine body and having an engine coolant discharge, a pilot water passage, a water pump configured to deliver water from the water inlet to the engine coolant passage and pilot water passage, the pilot water passage directing a flow of water through a pilot water discharge that is spaced from the engine coolant discharge, and a cross-sectional dimension of the pilot water passage along its length is no less than a maximum cross-sectional dimension of the at least one water inlet opening.
  • 13. The marine drive of claim 12, wherein a water delivery conduit delivers cooling water to the engine coolant passage and the pilot water passage, and the pilot water passage receives cooling water from the delivery conduit at a point upstream of the engine coolant passage.
  • 14. The marine drive of claim 12, wherein the pilot water passage has a generally circular cross-section through its length, and a minimum diameter of the pilot water passage along its length is no less than the maximum cross-sectional dimension of the at least one water inlet opening.
  • 15. The marine drive of claim 12, wherein the pilot water passage branches off of the engine coolant passage before the cooling water absorbs substantial heat from the engine body.
  • 16. The marine drive of claim 12, wherein the marine drive comprises an outboard motor, and the engine is disposed generally within a cowling of the outboard motor.
  • 17. The marine drive of claim 16, wherein the pilot water discharge is formed through the cowling.
  • 18. The marine drive of claim 16, wherein at least one peripheral engine component is disposed along the pilot water passage so that the pilot water passage delivers cooling water adjacent or through the engine component.
  • 19. The marine drive of claim 18, wherein the at least one peripheral engine component is arranged within a space between the engine body and the cowling.
  • 20. The marine drive of claim 18, wherein the at least one peripheral engine component comprises a heat exchanger having an inlet connector and an outlet connector.
  • 21. The marine drive of claim 20, wherein the pilot water passage comprises at least two sections of flexible hose configured to securely engage the connectors, and the connectors each have an inner diameter greater than the maximum dimension of the at least one water inlet cover opening.
  • 22. The marine drive of claim 21, wherein the peripheral engine component comprises an electrical component.
  • 23. The marine drive of claim 22, wherein the peripheral engine component comprises a rectifier-regulator assembly.
  • 24. The marine drive of claim 22, wherein the peripheral engine component comprises an ECU.
  • 25. The marine drive of claim 21, wherein the peripheral engine component comprises a fuel cooler.
  • 26. The marine drive of claim 18, wherein the pilot water passage delivers cooling water through a plurality of peripheral engine components.
Priority Claims (1)
Number Date Country Kind
2001-087213 Mar 2001 JP
PRIORITY INFORMATION

This application is based on and claims priority to (1) Japanese Patent Application No. 2001-087213, filed Mar. 26, 2001, and (2) U.S. Provisional Patent Application No. 60/322,229, filed Sep. 13, 2001, the entire contents of these prior applications are hereby expressly incorporated by reference.

US Referenced Citations (24)
Number Name Date Kind
4953525 Sakurai et al. Sep 1990 A
4955837 Yoshimura Sep 1990 A
4991546 Yoshimura Feb 1991 A
5036804 Shibata Aug 1991 A
5380228 Kawai et al. Jan 1995 A
5438962 Iwata et al. Aug 1995 A
5669358 Osakabe Sep 1997 A
5797378 Kato Aug 1998 A
5803050 Osakabe et al. Sep 1998 A
5823835 Takahashi et al. Oct 1998 A
5873330 Takahashi et al. Feb 1999 A
5885121 Nanami et al. Mar 1999 A
5890472 Saito Apr 1999 A
5921829 Iwata Jul 1999 A
5975032 Iwata Nov 1999 A
6022251 Ogino Feb 2000 A
6053784 Takahashi Apr 2000 A
6109987 Watanabe et al. Aug 2000 A
6155895 Sato et al. Dec 2000 A
6171158 Henmi et al. Jan 2001 B1
6263839 Hoshiba et al. Jul 2001 B1
6295955 Kato et al. Oct 2001 B1
6454622 Mashiko et al. Sep 2002 B2
6513463 Katayama Feb 2003 B2
Foreign Referenced Citations (2)
Number Date Country
6-42345 Feb 1999 JP
11-324696 Nov 1999 JP
Non-Patent Literature Citations (8)
Entry
Parts Catalogue Model Yar 2001, F80TLRZ (67G), F100TLRZ (67F) in 3 Pages.
Parts Catalogue Model Year 2001 150TRZ (64C), in 7 Pages.
Parts Catalogue Model Year 2001, 25 MHZ3 (6K9), 30MHZ (6J8), 30EHZ (6J8), 30ERZ (6J8). in 3 Pages.
Parts Catalogue Model Year 2002, F15MHZ (66M0), F15EHZ (66M0), in 3 Pages.
Parts Catalogue Model Year 2001, DX150TLRZ (67N), in 3 Pages.
Salwater Series, Parts Catalogue Model Year 1995, 225TRT (62J), in 3 Pages.
Parts Catalogue Model Year 2001, VX200TLRZ (66X), VX225TLRZ (66K), in 2 Pages.
Clymer Suzuki Outboard Shop Manual, 75-225 HP Two-Stroke 1992-1999, in 3 Pages.
Provisional Applications (1)
Number Date Country
60/322229 Sep 2001 US