Information
-
Patent Grant
-
6513463
-
Patent Number
6,513,463
-
Date Filed
Friday, March 16, 200123 years ago
-
Date Issued
Tuesday, February 4, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Mancene; Gene
- Castro; Arnold
Agents
- Knobbe, Martens Olson & Bear LLP
-
CPC
-
US Classifications
Field of Search
US
- 123 4129
- 123 4131
- 123 4133
- 123 540
- 123 456
- 440 88
-
International Classifications
-
Abstract
An engine for an outboard motor includes engine components disposed around the engine body. A cooling system includes a first water passage cooling the engine body and a second water passage branching off from the first water passage upstream the engine body and extending through the engine components. One engine component is generally positioned above the engine body. Two engine components are positioned on different sides of the engine body. The first and second water passages have separate discharge ports. The engine components are made of a metal material. The second water passage is defined by tubular members made of a corrosion-resistant material and the respective tubular members are embedded in the respective bodies of the engine components.
Description
PRIORITY INFORMATION
This application is based on and claims priority to Japanese Patent Application No. 2000-074225, filed Mar. 16, 2000, the entire contents of which is hereby expressly incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a cooling system for an outboard motor. More particularly, the present invention relates to a cooling system for an engine and a plurality of engine components of an outboard motor.
2. Description of Related Art
Typically, an outboard motor comprises an engine disposed atop a drive unit of the motor. To propel the associated watercraft, the engine drives a propulsion device placed in a submerged position through a proper drive mechanism. The engine usually has an engine body and a plurality of components. The engine body normally comprises a cylinder block, a cylinder head assembly and a crankcase assembly. At least one combustion chamber, and often more than one combustion chamber, is provided within the engine. Occasionally, part of an exhaust passage is unitarily formed with the engine body. Other engine components can include, for example, air intake conduits, fuel supply conduits, lubricant delivery conduits and a power generator, which all relate to the operation of the engine.
The engine body comprising the exhaust part and the foregoing engine components usually build much heat during the engine operations. The heat can accumulate therein unless properly removed and excessive heat can jeopardize normal engine operations. Typical engines thus have a cooling system that can cool the heated portions of the engine body and engine components. Various cooling systems are practicable.
One type of cooling system introduces water from outside of the motor and cools the engine body first because the engine body is subjected to greater temperature levels when compared to peripheral engine components. The water that has cooled the engine body then flows to the respective peripheral engine components. Another type of cooling system has a direct conduit branching off upstream of the engine body to supply fresh water to a peripheral engine component.
For instance, U.S. Pat. Nos. 5,975,032 and 5,980,340 disclose the former type of cooling system, while U.S. Pat. No. 5,438,962 discloses the latter type of cooling system. Japanese Laid-Open Patent Publication No. Hei 6-42345, published on Feb. 15, 1994, also discloses a rectifier-regulator cooling structure using fuel or water flowing through a cooling passage. Furthermore, Japanese Laid-Open Patent Publication No. Hei 11-324696, published on Nov. 26, 1999, discloses a cooling system that can cool a power generator and a high pressure fuel pump. An auxiliary water supply passage branches off from a main water supply passage to the generator and then to the fuel pump. The water that has cooled these two components then is discharged through a submerged discharge port.
In engine design for outboard motors, there is an increasing emphasis on obtaining high performance in output and more effective emission control. This trend has resulted in employing, for example, a multi-cylinder, fuel injected, four-cycle engine. This type of engine must have a greater number of engine components or larger sizes thereof than those of conventional engines. The engine body and the engine components of this new type of engine also produce greater heat levels than two-stroke engines. Particularly, if the components are one-sided or if the components are disposed such that only one side is cooled, the engine can develop disadvantageous hot zones. The hot zones can result in distortion of the engine body or engine components, or disruption of proper engine operations. The forgoing conventional cooling systems are not enough to resolve this problem.
A need therefore exists for an improved cooling system for an outboard motor that can cool an engine body and engine components efficiently and that can maintain a relatively good heat balance in connection with the respective sides.
In addition, if a cooling system malfunctions such that water can no longer be supplied to the portions that need the water for cooling, the engine can overheat. Engine overheat can result in, for example, seizure of pistons and malfunction of engine components. A pilot water discharge is useful to let the operator know of cooling system abnormalities, such as plugging. U.S. Pat. No. 5,823,835 discloses such a pilot water discharge. In this arrangement, a pilot discharge port is positioned above the water line and a small amount of cooling water that has passed through cooling jackets disposed in the engine body is expelled through this pilot discharge port as visual confirmation to the operator that cooling water is being properly supplied to the engine body.
As noted above, the engine body produces heat greater than the engine components, and in addition, the heat of the recent multiple cylinder engine is higher than before. The elevated temperature of the pilot water can discolor the coating that covers a surface of the housing or cowling of the outboard motor. For instance, in the region of the port, the high temperature water can discolor the outward appearance of the motor or cause scaling and the like.
Another need thus exists for an improved cooling system that has a pilot water discharge that does not adversely affect to a large degree the outward appearance of the outboard motor.
Further, the foregoing engine components are generally formed with metal material, such as, for example, aluminum based alloy cast material as well as the engine body. Otherwise, at least part of the engine components is formed with metal material for the heat exchange purpose although the rest part of the components is made of other material such as plastic. When the motor is used on the sea, seawater, i.e., salt water, is supplied to the engine components. The salt water, however, is likely to corrode bodies of the engine components that are made of metal material and hence can damage their primary functions.
A further need therefore exists for an improved cooling system for an outboard motor that can inhibit corrosion from encroaching engine components.
SUMMARY OF THE INVENTION
Accordingly, one aspect of the present invention involves an internal combustion engine for an outboard motor comprising an engine body, at least three engine components disposed around the engine body, and a water cooling system for cooling both the engine body and the engine components. The cooling system comprises a first water passage arranged to cool the engine body and a second water passage branching off from the first water passage upstream of the engine body and extending through the at least three engine components. A first of the at least three engine components is generally positioned above the engine body while a second and a third of the at least three engine components is generally positioned on a different side of the engine body relative to one another.
Another aspect of the present invention involves an internal combustion engine comprising an engine body, a plurality of engine components disposed around the engine body, and a water cooling system for cooling both the engine body and the engine components. The cooling system comprises a first water passage arranged to cool the engine body and a second water passage branching off from the first water passage upstream of the engine body and extending through the plurality of engine components in series. The first and second water passages have separate discharge ports that are located remotely from each another and the water discharge port of the second water passage is positioned next to the engine body.
A further aspect of the present invention involves an internal combustion engine comprising an engine body, a plurality of engine components being disposed around the engine body, and a water cooling system arranged to cool both the engine body and the plurality of engine components. The cooling system comprises a first water passage arranged to cool the engine body and a second water passage branching off from the first water passage upstream of the engine body and extending through the plurality of engine components. The plurality of engine components are made of a metal material with the second water passage in part being defined by tubular members made of a corrosion-resistant material. The respective tubular members are at least partially embedded in respective bodies of the engine components.
Another aspect of the present invention involves an internal combustion engine comprising an engine body, a plurality of engine components disposed around the engine body, and a cooling system for cooling both the engine body and the plurality of engine components. The cooling system comprises a first coolant passage arranged to cool the engine body and a second coolant passage branching off from the first coolant passage upstream of the engine body and extending through at least three of the plurality of engine components. The at least three engine components comprising a first engine component positioned at least above the engine body and a two engine components each positioned on two sides of the engine body so as to be spaced apart from each other.
An additional aspect of the present invention involves an outboard motor comprising an engine body, a plurality of engine components disposed around the engine body, and a water cooling system comprising a water inlet disposed lower than the engine body so as to introduce the water into the cooling system. A first water passage is arranged to cool the engine body and a second water passage is arranged to cool the plurality of engine components. The first water passage has a first water discharge port positioned closer to the water inlet than to the engine body and the second water passage has a second water discharge port positioned closer to the engine body than to the water inlet.
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 14 figures.
FIG. 1
is a side elevational view of an outboard motor comprising a cooling system arranged in accordance with a preferred embodiment of the present invention. The cooling system is illustrated schematically in the figure and actual positioning of respective engine components and a pilot discharge port can differ from those illustrated. A watercraft associated with the outboard motor also is partially shown in section.
FIG. 2
is a top plan view showing a power head of the outboard motor. A top cowling member is detached. A portion of the engine is shown in section.
FIG. 3
is an enlarged port side view of the engine with a portion of the power head illustrated in section and with a portion of the engine being shown in section.
FIG. 4
is another enlarged starboard side view of the engine with a portion of the power head illustrated in section and with a portion of the engine being shown in section.
FIG. 5
is a cross-sectional view of an exemplary air intake conduit provided with water passages.
FIG. 6
is a schematic view of a heat exchanger and fuel rail construction.
FIG. 7
is a schematic view of a heat exchanger and fuel conduit assembly construction.
FIG. 8
is a schematic top plan view showing a stator of a flywheel magnet. For clarity, a portion of the stator is omitted in this figure.
FIG. 9
is a schematic side view of the stator of FIG.
8
.
FIG. 10
is a schematic cross-sectional view of a heat exchanger and stator bracket construction.
FIG. 11
is a top plan view showing a rectifier-regulator assembly with a heat exchange construction.
FIG. 12
is a side view of the heat exchange construction for a rectifier-regulator assembly.
FIG. 13
is a cross-sectional view of an oil filter assembly with a heat exchange construction generally taken along the line
13
—
13
of FIG.
4
.
FIG. 14
is a cross-sectional view of the oil filter assembly taken along the line
14
—
14
of FIG.
13
.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
With reference to
FIGS. 1-4
, an overall construction of an outboard motor
30
, which employs a cooling system
31
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 a 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
34
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 preferablyis provided between the swivel bracket
40
and the clamping bracket
42
to tilt (raide or lower) the weivel 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 “tile 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
. Preferably, the protective cowling
56
defines a generally closed cavity
58
in which the engine
54
is disposed. The protective cowling
56
preferably 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
63
(see
FIGS. 3 and 4
) so that a user, operator, mechanic or repair person can access the engine
54
for maintenance or for other purposes.
With continued reference to
FIGS. 3 and 4
, the top cowling
60
preferably has at least one air intake opening
64
and at least one air duct
65
disposed on its rear and top portion. Ambient air is drawn into the closed cavity
58
from within the opening
64
through the duct
65
. Typically, the top cowling member
60
tapers in girth toward its top surface, which is in the general proximity of the air intake opening
64
.
With reference again to
FIG. 1
, 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 as described below.
The engine
54
in the illustrated embodiment operates on a four-cycle combustion principle. With reference now to
FIG. 2
, the engine
54
has a cylinder block
72
. The presently preferred cylinder block
72
defines four cylinder bores
73
which 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 line where 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. 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 number of cylinders, having other cylinder arrangements, 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.
A piston (not shown) reciprocates in each cylinder bore
73
in a well-known manner. A cylinder head assembly
74
, such as that illustrated in
FIG. 2
, for instance, is affixed to one end of the cylinder block
72
for closing the cylinder bores
73
. The cylinder head assembly
74
preferably defines four combustion chambers together with the associated pistons and cylinder bores
73
. Of course, the number of combustion chambers can vary, as indicated above. A crankcase assembly
76
closes the other end of the cylinder bores
73
and defines a crankcase chamber together with the cylinder block
72
. A crankshaft
80
extends generally vertically through the crankcase chamber and is journaled for rotation by several bearing blocks (not shown) in a suitable arrangement. Connecting rods (not shown) couple the crankshaft
80
in a well-known manner with the respective pistons. Thus, the crankshaft
80
can be rotated by the reciprocal movement of the pistons.
Preferably, the crankcase assembly
76
is located at the most forward position, with the cylinder block
72
and the cylinder head member
74
extending rearward from the crankcase assembly
76
, one after another. Generally, the cylinder block
72
, the cylinder head member
74
and the crankcase assembly
76
together define an engine body
82
. Preferably, at least these major engine portions
72
,
74
,
76
are made of aluminum based alloy. The aluminum alloy advantageously increases strength over cast iron while decreasing the weight of the engine body
72
.
The engine
54
comprises an air induction system. The air induction system draws air to the combustion chambers from the cavity
58
of the protective cowling assembly
56
. The air induction system preferably comprises intake ports, four intake passages
84
and a plenum chamber
86
. The intake ports can be defined in the respective cylinder head members
74
. In one configuration, intake valves repeatedly open and close the respective intake ports. When each intake port is opened, the corresponding intake passage
84
communicates with the associated combustion chamber.
In the illustrated arrangement, the air intake passages
84
are defined by a pair of intake manifolds
90
, a set of throttle bodies
92
and a set of intake runners
94
, while the plenum chamber
86
is defined by a plenum chamber member
96
. The plenum chamber member
96
has an inlet port
100
opening to the closed cavity
58
to draw the air in the cavity
58
into the plenum chamber
86
. Each intake manifold
90
has a flange portion that is affixed to the cylinder head member
74
. The throttle bodies
92
are interposed between the intake manifolds
90
and the intake runners
94
. The plenum chamber
86
defined by the plenum chamber member
96
is thus coupled with the associated intake ports through the intake passages
84
defined by the intake runners
94
, the throttle bodies
92
and the intake manifolds
90
.
The intake manifolds
90
and the throttle bodies
92
preferably are made of aluminum based alloy. The intake runners
94
preferably are unitarily formed with the plenum chamber member
96
and this unitary component preferably is made of a plastic or resin-based material. In some configurations, an aluminum based alloy can be used. In either case, i.e., aluminum based alloy or plastic material, the intake manifolds
90
, the throttle bodies
92
and the combined intake runner and plenum chamber member can be produced by, for example, a conventional casting method. Of course, these intake components can be made of other materials and by other conventional manufacturing processes.
The respective throttle bodies
92
preferably have throttle valves journaled therein for pivotal movement about an axis of a valve shaft that extends generally vertically. While not shown, in the illustrated arrangement, the throttle valves advantageously are butterfly valves. The throttle valves are operable by the operator through an appropriate conventional throttle valve linkage
102
(see FIG.
3
). The throttle valves measure or regulate an amount of air flowing through the respective air intake passages
84
. In other words, the air amount is variable by changing the positions or opening degrees of the throttle valves. Normally, the greater the opening degree, the higher the rate of airflow and the higher the engine speed.
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
. Each cylinder bore
73
preferably has exhaust ports defined in the cylinder head assembly
74
. The exhaust ports are repeatedly opened and closed by exhaust valves.
An exhaust manifold
106
(see
FIG. 2
) is defined next to the cylinder bores
73
in the cylinder block
72
and preferably extends generally vertically. The exhaust manifold
106
communicates with the exhaust ports to collect exhaust gases from the combustion chambers through the respective exhaust ports. The exhaust manifolds
106
are coupled with the exhaust passage in the exhaust guide member
66
. When the exhaust ports are opened, the combustion chambers communicate with this exhaust passage through the exhaust manifold
106
.
A valve cam mechanism is preferably provided for actuating the intake and exhaust valves. In the illustrated embodiment, the cylinder head assembly
74
journals an intake camshaft
110
and an exhaust camshaft
112
. The camshafts
110
,
112
extend generally vertically and in parallel to each other. The intake camshaft
110
actuates the intake valves, while the exhaust camshaft
112
actuates the exhaust valves. The respective camshafts
110
,
112
have cam lobes to push the intake and exhaust valves in a controlled timing to open and close the intake and exhaust ports. A single camshaft can replace the intake and exhaust camshafts
110
,
112
in a manner that is well known. Other conventional valve drive mechanisms can be of course employed instead of such a mechanism using one or more camshafts.
A camshaft drive mechanism is provided for driving the valve cam mechanism. As seen in
FIG. 2
, intake and exhaust camshafts
110
,
112
have driven sprockets
114
positioned atop thereof and the crankshaft
80
has a drive sprocket
116
positioned almost atop thereof. A timing chain or belt
118
is wound around the drive and driven sprockets
116
,
114
. The crankshaft
80
thus drives both the camshafts
110
,
112
through the timing chain
118
in timed relationship. A tensioner
120
preferably abuts on a side of the timing chain
118
so as to give proper tension to the chain
118
. A diameter of the driven sprockets
114
preferably is twice as large as a diameter of the drive sprocket
116
. The intake and exhaust camshafts
110
,
112
thus rotate at half of the speed of the rotation of the crankshaft
80
.
The engine
54
preferably has a port or manifold fuel injection system. The fuel injection system preferably comprises four fuel injectors
124
with one fuel injector allotted for each of the respective combustion chambers. Each fuel injector
124
preferably has an injection nozzle directed toward the associated intake passage
84
adjacent to the intake ports. The fuel injector
124
also preferably has a plunger that normally closes the nozzle and solenoid coil that moves the plunger from the closed position to an open position when energized with electric power. Of course, in some arrangements, the fuel injectors can be disposed for direct cylinder injection and, in other arrangements, carburetors can replace or accompany the fuel injectors.
The fuel injectors
124
spray fuel into the intake passages
84
under control of an ECU (electronic control unit). The ECU controls energizing timing and duration of the solenoid coils so that the plungers open the nozzles to spray a proper amount of the fuel into the engine
54
during each combustion cycle. A fuel rail
126
supports the fuel injectors
124
and also defines a fuel passage to the injectors
124
. The fuel rail
126
preferably extends generally vertically along a side surface of the cylinder head assembly
74
on the port side. The fuel rail
126
preferably is made of metal material such as, for example, an aluminum-based alloy, similar to the engine body
82
.
The fuel injection system further comprises a fuel supply tank that preferably is placed in the hull of the associated watercraft
38
. Fuel is drawn from the fuel tank by a first low pressure fuel pump (not shown) and a second low pressure pump
128
(see
FIG. 3
) through a fuel supply conduit. The first low pressure pump preferably is a manually operated pump. The second low pressure pump
128
preferably is a diaphragm-type pump that can be operated by, for example, the intake or exhaust camshaft
110
,
112
. In this instance, the second low pressure pump
128
is mounted on the cylinder head assembly
74
. A quick disconnect coupling can be provided in the supply conduit. Also, a fuel filter
130
can be positioned in the supply conduit at an appropriate location. The fuel filter
130
is preferably mounted on the cylinder head assembly
74
.
From the second low pressure pump
128
, the fuel enters a vapor separator
134
from the fuel supply conduit. In the illustrated arrangement, the vapor separator
134
is disposed in a space defined between the port side surface of the engine body
82
and the intake manifolds
90
and the vapor separator is advantageously mounted on the cylinder block
72
. At the vapor separator end of the supply conduit, a float valve can be provided that is operated by a float to maintain a substantially uniform level of the fuel within the vapor separator
134
.
A high pressure fuel pump preferably is provided in the vapor separator
134
. The high pressure fuel pump pressurizes fuel that is delivered through a delivery conduit to the fuel injectors
124
on the fuel rail
126
. The high pressure fuel pump in the illustrated arrangement preferably comprises a positive displacement pump. The construction of the pump thus generally inhibits fuel flow from its upstream side back into the vapor separator
134
when the pump is not running. A back-flow prevention device (e.g., a check valve) also can be used to prevent a flow of fuel from the delivery conduit back into the vapor separator
134
when the pump is off. This later approach can be used with a fuel pump that employs a rotary impeller to inhibit a drop in pressure within the delivery conduit when the pump is intermittently stopped. An electric motor preferably drives the high pressure fuel pump. The electric motor is preferably unified with the high pressure pump at its bottom portion and hence is disposed in the vapor separator
134
.
Excess fuel that is not injected by the injector
124
returns to the vapor separator
134
through a return conduit. A pressure regulator
138
preferably is positioned at the most upstream portion of the return conduit, i.e., atop the fuel rail
126
. The pressure regulator
138
limits fuel pressure to keep it at a fairly constant level at all times.
A desired amount of the fuel is sprayed into the intake passages
84
through the injection nozzles at a selected timing for a selected duration. The timing and duration preferably are controlled by the ECU. Because the pressure regulator
138
controls and stabilizes the fuel pressure, the duration can be used to determine a selected amount of fuel that will be supplied to the combustion chambers. Various control strategies for the injection timing and injection duration can be applied so that the optimum engine operation or an operation near to the optimum operation will be realized.
The fuel injection system will be described further in connection with the cooling system
31
later.
The engine
54
further comprises an ignition or firing system. Each combustion chamber is provided with a spark plug connected to the ECU so that ignition timing is also controlled by the ECU. 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 which are disposed between the spark plugs and 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 ignition coil preferably is a combination of a primary coil element and a secondary coil element that are wound around a common core. Desirably, the secondary coil element is connected to the spark plugs, while the primary coil element is connected to the igniter. Also, the primary coil element is coupled with a power source so that electrical current flows therethrough. The igniter abruptly cuts off the current flow in response to an ignition timing control signal from the ECU and then a high voltage current flow occurs in the secondary coil element. The high voltage current flow forms a spark at each spark plug.
In the illustrated engine
54
, the pistons reciprocate between top dead center and bottom dead center. When the crankshaft
80
makes two rotations, the pistons generally move from top dead center to bottom dead center (the intake stroke), from bottom dead center to top dead center (the compression stroke), from top dead center to bottom dead center (the power stroke) and from bottom dead center to top dead center (the exhaust stroke). During the four strokes of the pistons, the respective camshafts
110
,
112
make one rotation. The intake camshaft
110
actuates the intake valves to open the intake ports during the intake stroke, while the exhaust camshaft
112
actuates the exhaust valves to open the exhaust ports during the exhaust stroke.
Generally, at the beginning of the intake stroke, air preferably is drawn through the air intake passages
84
and fuel preferably is injected into the intake passage
84
by the fuel injectors
124
. The air and the fuel thus are mixed to form the air/fuel charge in the combustion chambers. Just before or during the power stroke, the respective spark plugs ignite the compressed air/fuel charge in the respective combustion chambers. The engine
54
thus continuously repeats the foregoing four strokes during its operation.
As discussed above, during engine operation, heat builds in the engine body
82
, i.e., the cylinder block
72
, the cylinder head assembly
74
, the exhaust manifold
106
and various peripheral engine components disposed around the engine body
82
. The cooling system
31
thus is provided to help cool such engine portions and engine components.
With regard to the engine body
82
, one or more water jackets preferably are provided that extend through or alongside portions of the engine body so that circulating cooling water can remove at least some of the heat accumulating in the engine portions. In the illustrated open loop cooling system, the cooling water is drawn into the cooling system
31
through a water inlet
143
from the body of water surrounding the outboard motor
30
by a water pump
144
. The water inlet
143
is disposed in a portion of the lower unit
52
that preferably is positioned under the water line at a level that will generally remain submerged when the drive unit
32
is fully or almost fully tilted down. The water pump
144
, in turn, is disposed in the driveshaft housing
50
.
The water is pressurized toward the water jackets provided to the engine body
82
through a water supply conduit
146
and then travels through the respective water jacket or water jackets. The water that has cooled the engine portions then goes through a discharge conduit
148
(see
FIG. 2
) before being discharged through one or more internal portions of the driveshaft housing
50
. A thermostat
150
preferably is placed along a portion of the cooling system and, more preferably, is placed at the most upstream end of the discharge conduit
148
. In this location, the thermostat
150
advantageously reduces or stops a cooling water flow that passes through the discharge conduit
148
until the engine body
54
is warmed up to a preset temperature. Such an arrangement advantageously increases engine warm-up even under cold conditions.
The engine
54
also comprises a closed-loop type lubrication system. The lubrication system comprises a lubricant oil reservoir
154
preferably positioned within the driveshaft housing
50
. An oil pump
156
is provided at a desired location, such as atop the driveshaft housing
50
, to pressurize the oil in the reservoir
154
and to pass the oil toward engine portions, which are desirably lubricated, through lubricant delivery passages. The 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
154
for re-circulation. Preferably, the lubrication system further comprises a filter assembly
182
that is mounted on a starboard side surface of the cylinder block
72
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
160
preferably is positioned above the engine body
82
. The illustrated flywheel assembly
160
comprises a flywheel magneto or AC generator
162
that supplies electric power to various electrical components, comprising the fuel injection system, the ignition system and the ECU. The flywheel magneto
162
generally comprises a rotor
164
and a stator
166
and can be constructed in any suitable manner.
In the illustrated arrangement, the rotor
164
is positioned atop the crankshaft
80
and is mounted for rotation with the crankshaft
80
. Preferably, the rotor
164
is configured as an overturned cup shape and is made of cast iron or another suitable material such that it has a relatively large mass. The large mass is desired, eventhough it is positioned at the top end of the outboard motor, because the rotor
164
concurrently acts as a flywheel to smooth rotation of the engine. A plurality of magnets
168
is affixed to the inner side surface of the rotor
164
. The magnets
168
are juxtaposed with each other but are spaced apart from one another to form gaps between the magnets
168
.
The stator
166
is affixed to a ring-shaped bracket
172
that is mounted on the engine body
82
. The stator
166
comprises a plurality of electrical coils
174
facing the magnets
168
on the rotor
164
. When the rotor
164
rotates around the stator
166
, the magnets
168
intermittently pass the electrical coils
174
. Electric power is induced in the coils to generate electric power (i.e., AC power) by a well-known electromagnetic induction effect. The generated AC power preferably is rectified and is regulated by a rectifier-regulator and then is accumulated in a battery so that the electrical components comprising the fuel injection system, ignition system and ECU can use DC power. The battery is preferably placed in the hull of the watercraft
38
.
The flywheel assembly
160
also comprises a ring gear
178
that extends around an outer surface of the illustrated flywheel assembly
160
. A starter motor (not shown) preferably drives the crankshaft
80
to start the engine
54
. The starter motor has a gear portion that meshes with the ring gear
178
. To start the engine
54
, the starter motor drives the crankshaft
80
through the gear connection. Once the engine
54
starts, the starter motor immediately preferably is disengaged to reduce the likelihood that the starter mechanism will be damaged.
A protective cover
180
is detachably mounted atop the engine body
82
to extend over at least a portion of the flywheel assembly
160
and the camshaft drive mechanism. The protective cover
180
is useful to protect the flywheel assembly
160
and the drive mechanism which include the moving parts described above when the top cowling
60
is detached.
As seen in
FIG. 1
, the driveshaft housing
50
depends from the power head
48
and supports a driveshaft
184
which is driven by the crankshaft
80
. The driveshaft
184
extends generally vertically through the driveshaft housing
50
. The driveshaft
184
preferably drives the water pump
144
and the oil pump
156
. The driveshaft housing
50
also defines internal passages which form portions of the exhaust system. An apron
185
covers an upper portion of the driveshaft housing
50
and improves the overall appearance of the outboard motor.
The lower unit
52
depends from the driveshaft housing
50
and supports a propulsion shaft
186
, which is driven by the driveshaft
184
. The propulsion shaft
186
extends generally horizontally through the lower unit
52
. A propulsion device is attached to the propulsion shaft
186
and is powered through the propulsion shaft
186
. In the illustrated arrangement, the propulsion device is a propeller
188
that is affixed to an outer end of the propulsion shaft
186
. The propulsion device, however, can take the form of a dual counterrotating system, a hydrodynamic jet, or any of a number of other suitable propulsion devices.
A transmission
192
preferably is provided between the driveshaft
184
and the propulsion shaft
186
. The transmission
192
couples together the two shafts
184
,
186
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
192
to change the rotational direction of the propeller
180
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
180
. Of course, an above-the-water discharge can be provided for lower speed engine operation. The difference in the locations of the discharges accounts for the differences in pressure at locations above the waterline and below the waterline. Because the opening above the line is smaller, pressure develops within the lower unit
52
. When the pressure exceeds the higher pressure found below the waterline, the exhaust gases exit through the hub of the propeller. If the pressure remains below the pressure found below the waterline, the exhaust gases exit through the smaller opening above the waterline.
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 (not shown) or through the hub of the propeller
180
along with the exhaust gases.
With continued reference to
FIGS. 1-4
and with additionally reference to
FIGS. 5-14
, the cooling system
31
will now be described in greater detail below. As described above, the cooling system
31
generally comprises the water inlet
143
through which cooling water is introduced into the water supply conduit
146
, the water pump
144
pressurizing the water to the supply conduit
146
, a set of one or more water jackets extending alongside or through the engine body
82
and the discharge conduit
148
discharging the water after it has passed through the water jackets. In the illustrated arrangement, the cooling system
31
comprises another route through which the water is provided for cooling the peripheral engine components.
As used through this description, the term “peripheral engine components” or simply “engine component(s)” means all systems, apparatus, devices, accessories, conduits, components, members, elements and other things that are disposed externally around the engine body in connection with engine operations. The definition will be clearer in the context of the following descriptions regarding exemplary configurations.
As schematically shown in
FIG. 1
, the water supply conduit
146
branches off in two directions at a water pool
210
disposed within the engine body
82
. A first branch passage
212
is directed to the water jackets of the engine body
82
, while a second branch passage
214
is directed to the engine components. As best seen in
FIGS. 2 and 4
, the water pool
210
preferably is disposed next to the exhaust manifold
106
at a lower portion of the cylinder block
72
on the starboard side. In the illustrated arrangement, the water pool
210
is formed within a recess defined at an outer surface of the cylinder block
72
and another recess defined at an inner surface of a cover member
216
which is affixed to the outer surface of the cylinder block
72
. Of course, other configurations also are possible. The first branch passage
212
desirably is one of the water jackets formed through the cylinder block
72
while the second branch passage
214
preferably comprises several external conduits
218
a,
218
b,
218
c,
218
d,
218
e,
218
f
and a number of internal conduits defined within the respective engine components.
As best seen in
FIG. 2
, in the illustrated arrangement, the external conduit
218
a
is coupled with the water pool
210
at an outlet port
222
thereof and then extends generally along a lower profile of the cylinder head assembly
74
, i.e., extends rearwardly, transversely and then forwardly to the port side of the engine body
82
. As seen in
FIG. 3
, the illustrated conduit
218
a
then bifurcates at the lowermost portion of the cylinder head assembly
74
on the port side to form the external conduit
218
b
and the conduit
218
c.
The external conduit
218
b
then goes up toward the intake manifolds
90
, which define a first group of the engine components that need cooling. Advantageously, cooling the intake manifolds can increase engine efficiency. The external conduit
218
b
is coupled with a passage portion
224
defined in a body of the lowermost manifold
90
and extending generally vertically therethrough. The other manifolds
90
also have similar passage portions
224
. Conduit portion
226
, which has through-holes, couples with the respective passage portions
224
. Preferably, the conduit portions
226
are unitarily formed with the manifolds
90
during casting of the manifolds
90
.
Both the passage portions
224
and the conduit portions
226
thus are basically made of an unlined aluminum based alloy as well as the manifolds
90
themselves. However, it is anticipated that the illustrated outboard motor
30
is often used on the ocean and seawater, i.e., salt water, therefore will frequently flow through the passage portions
224
and the conduit portions
226
. Because salt water can corrode the aluminum alloy, an inner pipe member or tubular member made of brass preferably is embedded in the mold at desired locations before the manifolds are cast to form an protective internal water passage
230
that extends along at least a portion of, and preferably the entire, length of the passage portions
224
and the conduit portions
226
. This construction of the passage portions
224
and the conduit portions
226
, lined or unlined, forms a heat exchange construction or arrangement
232
that is formed in connection with the intake manifolds
90
.
In this beat exchange construction
232
, the water coming from the water pool
210
flows upwardly through the internal water passage
230
to remove at least some of the heat accumulating in the intake manifolds
90
. This heat exchange construction
232
is advantageous because the air cooled by this construction
232
increases the charging efficiency. In other words, higher temperature are is less dense than lower temperature air. Accordingly, the decreasing the temperature of the intake air, more air can be drawn into the combustion chambers to provide a better air to fuel ratio for more complete combustion or to provide more air, which can be mixed with more fuel to increase the power generated during combustion.
FIG. 5
illustrates another exemplary heat exchange construction for the intake manifolds
90
. In this arrangement, each intake manifold
90
comprises the intake passage
84
through which air passes. Each manifold
90
also has a flange portion
235
at which the manifold
90
is affixed to the cylinder head assembly
74
. In the illustrated construction, the intake manifolds
90
have a pair of internal water passages
230
. The external conduit
218
b
branches off toward the respective water passages
230
under the lowermost manifold
90
and then merges together above the uppermost manifold
90
. A pair of inner pipe members
232
is embedded is a manner similar to that described above. It should be noted that the number of pipe members can vary and three or more internal water passages are, of course, practicable.
In another arrangement, the fuel rail
126
is another engine component that can be cooled. Cooling the fuel rail is advantageous because, except under very cold conditions, the fuel passing through the fuel rail
126
generally should not be heated or warmed by engine heat. Such heating can cause the fuel to vaporize or can otherwise decrease the density of the fuel. Thus, in the illustrated arrangement, the other external conduit
218
c
extends upward and is coupled to the fuel rail
126
, as best seen in FIG.
6
. The fuel rail
126
preferably has a heat exchange construction or arrangement
236
in which an internal fuel passage
238
and an internal water passage
240
extend generally parallel to each other. The fuel passage
238
has four branches connected to the respective fuel injectors
124
that are supported by the fuel rail
126
. The external conduit
218
c
is coupled with the bottom end of the internal water passage
240
. In some arrangements, the fuel rail
126
could be completely or substantially completely jacketed.
Because the fuel rail
126
is formed with aluminum based alloy as noted above, an inner pipe member
242
made of brass preferably is embedded in the fuel rail body in a casting process of the fuel rail
126
to define a protected internal water passage
240
. In the illustrated arrangement, the fuel passage
238
also is defined by an inner pipe member
244
which is made of brass and embedded in the same manner. It should be noted that the inner pipe member
244
can be made of other metal material than the brass because no seawater passes therethrough. However, to reduce differential thermal expansion concerns, it is currently preferred that the two pipe members
242
,
244
be formed of similar materials.
This heat exchange construction
236
is advantageous because possible vapor lock and/or deposit that may be formed at the nozzle portions of the fuel injectors
124
can be obviated. In addition, the accuracy of the fuel injection amount can be improved by cooling the fuel to a preset temperature range and maintaining the fuel temperature in this general range. It is anticipated that heat exchange constructions also can be disposed along the fuel supply system at other locations, i.e., components other than the fuel rail
126
such as a fuel supply conduit and/or a delivery conduit.
With reference now to
FIG. 7
, another engine component that can have a exchange construction
250
is illustrated. In this arrangement, a cast block
252
made of aluminum based alloy replaces the fuel rail
126
. Inner pipe members
254
,
256
are embedded in the block
252
and extend generally parallel to each another to form the water passage
236
and the fuel passage
240
. Each pipe member
254
,
256
preferably has a main portion and inlet and outlet portions. A diameter of the main portion desirably is greater than each diameter of the inlet and outlet portions. The inlet and outlet portions extend beyond both ends of the block
252
. Outer pipes
258
,
260
,
262
,
264
, which are preferably made of elastic material such as, for example, plastic or rubber, are fitted to the respective ends of the inlet and outlet portions so as to form each part of the cooling water conduit and the fuel supply or delivery conduit. This arrangement also is effective in controlling the temperature of the fuel supply.
With reference again to
FIG. 3
, the external conduits
218
b,
218
c
merge together above the uppermost intake manifold
90
to form a single external conduit
218
d.
The external conduit
218
d
then extends forwardly along a top end of the cylinder block
72
toward the stator
166
of the flywheel magneto
162
defined in the flywheel assembly
160
. The stator
166
is a third engine component that can be cooled. The electrical coils
174
build heat that can be removed through a suitable heat exchange construction. Because the stator
166
is compactly arranged, a heat exchange construction
268
for the stator
166
preferably is provided at the ring-shaped bracket
172
.
As noted above and best seen in
FIGS. 8-10
, the stator
166
preferably is affixed to the ring-shaped bracket
172
by bolts or other fasteners and the electrical coils
174
are placed radially and side by side around the stator
166
. The stator
166
and the ring-shaped bracket
172
desirably are made of metal such as, for example, aluminum based alloy. The heat produced by the coils
174
thus is conducted to the ring-shaped bracket
172
through the stator body. The ring-shaped bracket
172
has a flange
270
projecting from a bottom periphery of the bracket
172
. The ring-shaped bracket
172
preferably is affixed to a top surface of the cylinder block
72
at this flange
270
by bolts or other fasteners. Four bolt or fastener holes
274
are provided in this arrangement, but other fastening arrangements also can be used.
A pipe member
276
, preferably made of brass, desirably is embedded within the bracket
172
in a casting process of the bracket
172
to define an internal water passage
272
extending circularly along the outer periphery of the flange
270
and under the coils
174
. Both ends of the pipe member
274
extend outwardly beyond an end surface of the bracket
172
and the foregoing external conduit
218
d
is coupled to one of the ends of the pipe member
274
placed on the port side as best seen in FIG.
2
. Of course, the pipe member
274
can be attached to the cooling system in other manners, such as internally extending fittings and the like. An inlet port of the pipe member
274
is defined at the end coupled to the external conduit
218
d.
The other end of the pipe member
274
, which defines an outlet port, is placed on the starboard side as seen FIG.
2
. Of course, other configurations also can be used.
The cooling water which enters the internal water passage
272
through the inlet port from the external conduit
218
d
passes all the way through the passage
272
and then goes to the outlet port. During this movement, the water absorbs some of the heat accumulated in the bracket
172
that has been conducted from the coils
174
through the stator
166
. In this arrangement, because the heat exchange construction
268
is formed with such a simple water passage
272
defined in the ring-shaped bracket
172
, the cooling water advantageously continues flow and generally will not stagnate along any portion of the passage
272
, In other words, the rapid movement of the cooling water helps reduce the heat build up that may occur within the stator bracket
182
. Similar to the engine components described above, the water, even if it is seawater, advantageously does not easily corrode the ring-shaped bracket
172
because the pipe member
276
is formed of brass and the pipe member
276
covers the internal water passage
272
so as to protect the bracket body from the seawater.
With reference now to
FIGS. 11 and 12
, a further engine component that has another heat exchange construction
280
is illustrated therein. The component in this alternative is a rectifier-regulator
282
. The rectifier-regulator
282
rectifies the AC power which is generated by the flywheel magneto
162
to DC power and also regulates the power under a preset voltage. The rectification and regulation is accompanied with production of heat and thus should be cooled in an appropriate manner.
The rectifier-regulator
282
typically is confined within a metallic container
284
and spaces remaining around electric circuit elements are preferably filled with resin or plastic material. A heat exchange block
286
made of aluminum based alloy is preferably attached to a surface of the container
284
. In the illustrated arrangement, a U-configured pipe member
288
which is made of brass is embedded within the block
286
, preferably when the block is form in a casting process, to define an internal water passage
290
. Like the inlet and outlet ports of the ring-shaped bracket
172
, one of the external conduits extending around the engine body
82
can be coupled to these ports to let the cooling water flow through the water passage
290
. The brass pipe member
288
also protects the block
286
from the corrosion of the seawater. A bolt or other fastener connection, such as adhesives, can be used to couple the block
286
with the container
284
of the rectifier-regulator
282
.
With reference again to the stator
166
and the ring-shaped bracket
172
, the external conduit
218
e
is connected to the outlet port of the bracket
172
, which is formed with the end portion of the pipe member
276
. As best seen in
FIG. 4
, the external conduit
218
e
then extends downwardly along a side surface of the cylinder block on the starboard side to the oil filter assembly
182
. The filter assembly
182
is yet another engine component that can be cooled by the cooling system
31
. This is because, if the oil accumulates heat, its viscosity decreases and hence lubrication performance can deteriorate. Another heat exchange construction
292
thus is provided for the oil filter assembly
182
.
With reference to
FIG. 13
, the filter assembly
182
comprises a base member
294
and a filter member
296
. The base member
294
preferably is made of a cast aluminum-based alloy like the foregoing engine components. The base member
294
thus defines a downstream portion
298
that is disposed generally on the center axis of the base member
294
and a plurality of upstream portions
300
disposed around the downstream portion
298
. The respective portions
298
,
300
preferably extend generally horizontally. Each upstream portion
300
advantageously is configured to have a tapered or narrow part
302
, which increases the flow rate in that region.
The filter member
296
also defines a downstream portion
304
that communicates with the downstream portion
298
of the base member
294
and a plurality of upstream portions
306
that communicate with the upstream portions
306
. The respective portions
304
,
306
preferably also extend generally horizontally. The downstream portions
298
,
304
together define a downstream oil passage
308
while the upstream portions
302
,
306
together define an upstream oil passages
310
. The downstream and upstream oil passages
308
,
310
communicate with one another. A single filter element
309
can be disposed in the communicating portion. That is, both the passages
308
,
310
are coupled with each other through the filter element
309
.
The upstream oil passages
300
communicate with oil supply galleries
314
defined within the cylinder block
72
and merge with each other further upstream to form a single oil supply gallery
316
. The downstream oil passage
308
is connected to a delivery oil gallery
318
defined also within the cylinder block
72
. The oil supply gallery
316
thus communicates with the oil delivery gallery
318
through the upstream and downstream oil passages
310
,
308
via the oil filter element
309
.
A coupling member
322
couples the cylinder block
72
, the base member
294
and the filter member
296
together. The illustrated coupling member
322
is generally cylindrically configured and has a flange
324
. Both outer ends of the illustrated coupling member
322
are threaded. Because the end of the delivery gallery
318
where the downstream passage
308
is connected and the end of the downstream portion
304
of the filter member
296
are also threaded, and in addition, an outer diameter of the coupling member
322
generally equal to an inner diameter of the downstream oil passage
308
, the coupling member
322
connects itself to both the cylinder block
72
and to the filter member
296
. Of course, other methods of coupling also can be used. However, the illustrated arrangement is advantageously simple and secure.
In a preferred arrangement, the coupling member
322
is first coupled to the cylinder block
72
by connecting the base member
294
with the flange
324
and then the filter member
296
is coupled to the coupling member
322
. Because of this coupling construction, the filter assembly
182
is detachable as a unit from the cylinder block
72
. Of course, in some configurations, the filter member
296
can be formed for removal separate from the filter assembly
182
. In order to inhibit oil flowing through the passages from leaking out, an O-ring or seal member
328
is preferably inserted between the cylinder block
72
and the base member
294
, and another O-ring or seal member
328
is also preferably inserted between the base member
294
and the filter member
296
.
Oil is thus provided to the engine portions that need lubrication through the supply gallery
316
, the upstream passage
310
, the filter element
309
, the downstream passage
30
and the delivery gallery
318
. As noted above, heat accumulated in the oil is removed at the filter assembly
182
in this embodiment. Thus, the illustrated filter assembly arrangement can improve the life of the lubricant used in the illustrated engine and can improve performance of the lubrication system.
An inner pipe member
334
, which advantageously can be made of brass, preferably is embedded within the base member
294
in a casting process thereof to define an internal water passage
336
. The pipe member
334
in this construction preferably is configured spirally around the upstream portions
300
of the oil passages
310
. Both ends of the pipe member
334
extend outwardly beyond an end surface of the base member
334
and the foregoing external conduit
218
e
is coupled to one of the ends of the pipe member
334
placed next to a side surface of the cylinder block
72
. Of course, other coupling arrangements also can be used. In the illustrated arrangement, however, one end is thus an inlet port of the pipe member
334
. The other end of the pipe member
334
, which defines an outlet port, is placed outside of the inlet port relative to the cylinder block
72
.
Cooling water comes in through the inlet port and flows all the way through the internal water passage
336
defined by the spiral pipe member
334
. While traversing the passage
336
, the water removes some of the heat accumulating in the base member
294
and also in the oil passing through the upstream portions
300
of the upstream oil passages. This is advantageous because the viscosity of the oil can be held under an appropriate condition. Like the foregoing engine components, the water, even if it is seawater, does not substantially corrode the base member
294
because the brass pipe member
334
protects the base member
294
from the seawater.
If the base member
294
does not accumulate heat immediately after the engine
54
has started up, the cooling water is preferably inhibited from flowing therethrough because oil should be warmed up rather than cooled down.
FIG. 14
illustrates in phantom an additional arrangement that allows the oil to be suitably heated prior to cooling and maintaining a desired temperature range. Specifically, a three-direction thermo-valve
342
is preferably provided upstream the inlet port with a bypass water passage
344
branching off from the valve
342
and being directly connected to the outlet port in this arrangement. If the temperature of the water is lower than a preset temperature, the valve
342
allows the water to flow through the bypass passage
344
such that the internal water passage
336
is bypassed. If the temperature has reached a preset temperature, the valve allows the water to flow the internal water passage
336
and the temperature of the oil can be controlled.
As best seen in
FIGS. 2 and 4
, the external conduit
218
f
preferably is connected to the outlet port of the pipe member
334
and desirably extends generally along a lower profile of the cylinder head assembly
74
together with, and generally parallel to, the external conduit
218
a.
The bottom cowling member
62
preferably has a pilot discharge port
346
at a comer on the rear starboard side. A nipple preferably extends toward the internal cavity
58
of the cowling assembly
56
from the discharge port
346
and the end of the external conduit
218
f
is fitted onto the nipple. The pilot discharge port
346
thus is positioned closer to the engine body
82
than to the water inlet port
143
. To the contrary, the propeller hub, through which the water that has cooled the engine body
82
flows, desirably is positioned closer to the water inlet port
143
than to the engine body
82
.
In the illustrated arrangement, all the water that has traveled around the engine components will be discharged through the pilot discharge port
346
. The pilot discharge port can be defined in an upper area of the driveshaft housing. The water discharge thus is visible by the watercraft operator. This is advantageous because the operator can recognize that at least this portion of the cooling system
31
is functioning as expected because of the visual confirmation of the water discharge. The water passing through the engine components is not as hot as the water passing through the engine body
82
itself because the engine components themselves do not produce the same level of heat and most only absorb heat conducted from the engine body
82
. Thus, this pilot discharge has a reduced temperature that is less likely to deteriorate coatings on the drive unit
32
and hence the neat appearance of the outboard motor
30
can be kept accordingly.
As described above, in the illustrated embodiment, the first water passage supplies water cooling the engine body, while the second water passage branches off from the first water passage upstream the engine body and supplies water cooling the engine components in series. One of the engine components, i.e., the stator, is positioned above the engine body and two other components, i.e., the intake manifolds (or the fuel rail) and the oil filter assembly, preferably are positioned on different sides of the engine body, i. e., on the port side and the starboard side, respectively. The cooling system thus can cool the engine body and the engine components efficiently and can hold good heat balance in connection with the respective sides.
In addition, the water is unlikely to stagnate because of the arrangement connecting the respective component in series. However, it is anticipated that the arrangement also can employ either entire or partial parallel connections. For instance, if two or more components extend in parallel or these components have generally the same heat level, then the cooling system can have connections arranged in parallel. Preferably, an engine component that can produce or accumulate heat causing an operating temperature greater than the operating temperature of another component is placed downstream of the other component. Thus, the cooler components should be cooled first. Of course, this is a mere guideline and other arrangements or layouts can be practicable if arrangements complying with the guideline are too complicated or the lengthy.
The engine components described above preferably have bodies made of aluminum-based alloy and the pipe members, which preferably are made of brass, are embedded within the bodies because the aluminum alloy has the excellent heat transfer rate and the brass has the good anti-corrosion nature. Other metal materials, however, also can be used. For example, a copper-based alloy, which has also a good heat transfer rate, can replace the aluminum-based alloy. In addition, stainless pipe members can replace the brass pipe members because stainless steel is less likely to be corroded by seawater. In fact, particular types of stainless steel can be selected based upon their projected durability.
Of course, the foregoing description is that of a several preferred construction having certain features, aspects and advantages in accordance with the present invention. In addition, not all of the above-described components must be used in a single cooling system and a cooling system can employ various components without employing other components. Thus, various changes and modifications may be made to the abovedescribed arrangements without departing from the spirit and scope of the invention, as defined by the appended claims.
Claims
- 1. An internal combustion engine comprising an engine body, a plurality of engine components disposed around the engine body, and a water cooling system for cooling both the engine body and the engine components, the cooling system comprising a first water passage arranged to cool the engine body, and a second water passage branching off from the first water passage upstream of the engine body and extending through the plurality of engine components in series, the first and second water passages comprising separate discharge ports that are located remotely from each other, and the discharge port of the second water passage being positioned next to the engine body.
- 2. The engine as set forth in claim 1, wherein the plurality of engine components are made of a metal material, the second water passage being at least partially defined by tubular members made of a corrosion-resistant material, and the respective tubular members being embedded in respective bodies of the plurality of engine components.
- 3. The engine as set forth in claim 1, wherein the second water passage terminates at a discharge port that extends through an outer surface of an upper portion of the outboard motor.
- 4. An internal combustion engine comprising an engine body, a plurality of engine components being disposed around the engine body, and a water cooling system arranged to cool both the engine body and the plurality of engine components, the cooling system comprising a first water passage arranged to cool the engine body and a second water passage branching off from the first water passage upstream of the engine body and extending through the plurality of engine components, the plurality of engine components being made of a metal material, the second water passage in part being defined by tubular members made of a corrosion-resistant material and the respective tubular members being at least partially embedded in respective bodies of the engine components.
- 5. The engine as set forth in claim 4, wherein the second water passage terminates at a discharge port that extends through an outer surface of an upper portion of the outboard motor.
- 6. An internal combustion engine comprising an engine body, a plurality of engine components disposed around the engine body, and a cooling system for cooling both the engine body and the plurality of engine components, the cooling system comprising a first coolant passage arranged to cool the engine body, and a second coolant passage branching off from the first coolant passage upstream of the engine body and extending through at least three of the plurality of engine components, the three engine components comprising a first engine component positioned at least above the engine body, and a second engine component and a third engine component each positioned on a different side of the engine body so as to be spaced apart from each other.
- 7. The internal combustion engine as set forth in claim 6, wherein the second coolant passage is coupled with the first, second and third engine components in a heat exchange relationship.
- 8. The engine as set forth in claim 6, wherein the second water passage terminates at a discharge port that extends through an outer surface of an upper portion of the outboard motor.
- 9. An outboard motor comprising an engine body, a plurality of engine components disposed around the engine body, and a water cooling system comprising a water inlet disposed lower than the engine body so as to introduce the water into the cooling system, a first water passage arranged to cool the engine body and a second water passage arranged to cool the plurality of engine components, the first water passage comprising a first water discharge port positioned closer to the water inlet than to the engine body and the second water passage comprising a second water discharge port positioned closer to the engine body than to the water inlet.
- 10. The outboard motor as set forth in claim 9 additionally comprising a protective cowling surrounding the engine body and the engine components, wherein the second water discharge port is defined at the protective cowling.
- 11. The outboard motor as set forth in claim 9, wherein at least two of the plurality of engine components through which the second water passage extends are disposed on opposing sides of the engine body relative to each another.
- 12. The internal combustion engine as set forth in claim 9, wherein the plurality of engine components are made of a metal material, the second water passage at least in part is defined by tubular members made of a corrosion-resistant material, and the respective tubular members are at least partially embedded in respective bodies of the engine components.
- 13. The outboard motor as set forth in claim 9, wherein the second water passage branches off from the first water passage upstream the engine body.
- 14. The engine as set forth in claim 9, wherein the second water passage terminates at said second water discharge port and said second water discharge port extends through an outer surface of an upper portion of the outboard motor.
- 15. An internal combustion engine for an outboard motor comprising an engine body, at least three engine components disposed around the engine body, and a water cooling system for cooling both the engine body and the engine components, the cooling system comprising a first water passage arranged to cool the engine body, and a second water passage branching off from the first water passage upstream of the engine body and extending through the at least three engine components, a first of the at least three engine components being generally positioned above the engine body, and a second and a third of the at least three engine components being generally positioned on a different side of the engine body relative to one another.
- 16. The engine as set forth in claim 15, wherein the second water passage terminates at a discharge port that extends through an outer surface of an upper portion of the outboard motor.
- 17. The engine as set forth in claim 15, wherein the second water passage extends through the engine components in series.
- 18. The engine as set forth in claim 15, wherein at least one of the second engine component and the third engine component is disposed upstream of the first engine component.
- 19. The engine as set forth in claim 15, wherein at least one of the second engine component and the third engine component is disposed downstream of the first engine component.
- 20. The engine as set forth in claim 15, wherein the first engine component is made of metal material, the second water passage in part is defined by a tubular member made of corrosion-resistant material, and the tubular member is at least partially embedded in a body of the first engine component.
- 21. The engine as set forth in claim 15, wherein the first engine component comprises a power generator.
- 22. The engine as set forth in claim 15, wherein at least one of the second engine component and the third engine component is made of metal material, the second water passage at least in part is defined by a tubular member made of corrosion-resistant material, and the tubular member is at least partially embedded in a body of the engine component.
- 23. The engine as set forth in claim 15, wherein both the sides of the engine body are lateral sides thereof located opposite to one another.
- 24. The engine as set forth in claim 15, wherein each one of the first and second water passages comprises a separate water discharge port relative to each other.
- 25. The engine as set forth in claim 15 additionally comprising at least one combustion chamber defined within the engine body, and an air intake system arranged to introduce air to the combustion chamber, wherein one of the second engine component and the third engine component comprises an air intake conduit, and the second coolant passage extends through a body of the air intake conduit.
- 26. The engine as set forth in claim 25, wherein the air intake conduit is made of a metal material, the second water passage at least in part is defined by a tubular member made of a corrosion-resistant material, and the tubular member is at least partially embedded in the body of the air intake conduit.
- 27. The engine as set forth in claim 15 additionally comprising at least one combustion chamber defined within the engine body, and a fuel supply system arranged to supply fuel to the combustion chamber, wherein at least one of the second engine component and the third engine component comprises a fuel delivery conduit, and the second coolant passage extends through a body of the fuel delivery conduit.
- 28. The engine as set forth in claim 27, wherein the fuel delivery conduit is made of a metal material, the second water passage at least in part is defined by a tubular member made of a corrosion-resistant material, and the tubular member is at least partially embedded in the body of the fuel delivery conduit.
- 29. The engine as set forth in claim 27, wherein the fuel delivery conduit defines a fuel passage extending therethrough, and the second water passage extends along at least a portion of the fuel passage.
- 30. The engine as set forth in claim 27, wherein the fuel supply system comprises a fuel injector arranged to spray the fuel toward the combustion chamber, a fuel rail arranged to support the fuel injector, and the fuel delivery conduit is defined in the fuel rail.
- 31. The engine as set forth in claim 15 additionally comprising a lubrication system arranged to lubricate at least one inner portion of the engine body, wherein one of the first engine component and the second engine component comprises a lubricant delivery conduit, and the second water passage extends through a body of the lubricant delivery conduit.
- 32. The engine as set forth in claim 31, wherein the lubricant delivery conduit is made of a metal material, the second water passage at least in part is defined by a tubular member made of a corrosion-resistant material, and the tubular member is at least partially embedded in the body of the lubricant delivery conduit.
- 33. The engine as set forth in claim 31, wherein the lubrication system comprises a filter assembly, and the lubricant delivery conduit is defined in the filter assembly.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-074225 |
Mar 2000 |
JP |
|
US Referenced Citations (7)
Foreign Referenced Citations (2)
Number |
Date |
Country |
6-42345 |
Feb 1994 |
JP |
11-324696 |
Nov 1999 |
JP |