Note: Descriptions are shown in the official language in which they were submitted.
CA 02564160 2006-11-06
70488-264(D)
WATER-COOLED VERTICAL ENGINE
AND
OUTBOARD MOTOR EQUIPPED THEREWITH
This is a divisional of Canadian Patent Application 2,444,409 filed October 6,
2003.
BACKGROUND OF THE iNVENTION
Field of the Invention
The present invention relates to a water-cooled vertical engine having a
crankshaft disposed substantially vertically, and to an outboard motor
equipped with the
water-cooled vertical engine.
Description of the Related Art
As a vertical engine for an outboard motor, a water-cooled engine is generally
used. In an outboard motor water-cooled engine disclosed in Japanese Patent
Application Laid-open No. 10-212948, a thermostat for controlling the flow of
cooling
water within a water jacket in accordance with the temperature of the cooling
water is
disposed in an upper part of an engine block, and a timing belt, via which a
camshaft is
driven by a crankshaft, is disposed in the upper part of the engine block.
The thermostat thus disposed in the upper part of the engine block can detect
the temperature of cooling water that has been supplied from the lower end of
the water
jacket and has carried out heat exchange, thus enabling the flow of cooling
water to be
controlled appropriately. Furthermore, since the timing belt is disposed in
the upper
part of the engine block, assembly and maintenance thereof can be made easy.
However, in the above-mentioned arrangement, since the thermostat is
disposed within a cover for covering an upper part of the timing belt, there
is the
problem that it is necessary to remove the cover for maintenance of the
thermostat, and
the workability is therefore poor. In order to facilitate the maintenance of
the
thermostat, providing the thermostat on an upper face of the cover for
covering the
upper part of the timing belt can be considered, but this requires a cooling
water pipe for
providing a connection between the thermostat and a water jacket provided in
the
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CA 02564160 2006-11-06
engine block, resulting in increases in the number of components and the
number of
assembly steps.
Moreover, when a thermostat for controlling the flow of cooling water in a
cylinder block cooling water jacket and a second thermostat for controlling
the flow of
cooling water in a cylinder head cooling water jacket are provided separately,
it is
necessary to arrange the two thermostats compactly in a confined space of an
upper
part of the engine.
SUMMARY OF THE INVENTION
The present invention has been achieved in view of the above-mentioned
circumstances, and it is a first object thereof to provide a water-cooled
vertical engine
and an outboard motor equipped therewith, wherein maintenance of a thermostat
provided in an engine block water jacket can be carried out easily.
Furthermore, it is a second object of the present invention to provide a water-
cooled vertical engine and an outboard motor equipped therewith, wherein
cooling
water can easily be supplied to a thermostat while ensuring the ease of
maintenance of
the thermostat.
Moreover, it is a third object of the present invention to compactly arrange
two
thermostats in a water-cooled vertical engine or an outboard motor equipped
with the
water-cooled vertical engine.
In order to accomplish the first object, a first aspect of the present
invention
provides a water-cooled vertical engine that includes a crankshaft disposed
substantially vertically and an endless transmission member for transmitting a
driving
force of the crankshaft to a camshaft, the endless transmission member being
disposed
in an upper part of an engine, wherein a thermostat for controlling the flow
of cooling
water in a water jacket formed in the engine is provided in the upper part of
the engine
above the endless transmission member.
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CA 02564160 2006-11-06
In accordance with this arrangement, since the thermostat for controlling the
flow
of cooling water in the water jacket of the engine is provided in the upper
part of the
engine above the endless transmission member for transmitting the driving
force of the
crankshaft to the camshaft, the thermostat can easily be accessed from the top
of the
engine for maintenance without being obstructed by the endless transmission
member,
and moreover it is easy to manipulate a cooling water pipe for discharging
cooling water
from the thermostat.
In order to accomplish the first object, in accordance with a second aspect of
the
present invention, in addition to the first aspect, there is provided a water-
cooled
vertical engine wherein the endless transmission member is a timing chain, and
the
upper part of the engine is formed from a chain cover for covering the timing
chain in
cooperation with a cylinder head and a cylinder block.
In accordance with this arrangement, since the timing chain, via which the
camshaft is driven by the crankshaft, is covered by the chain cover in
cooperation with
the cylinder head and the cylinder block, the timing chain can advantageously
be
maintained in a lubricating oil atmosphere.
In order to accomplish the first object, a third aspect of the present
invention
provides an outboard motor equipped with a water-cooled vertical engine that
includes
a crankshaft disposed substantially vertically and an endless transmission
member for
transmitting a driving force of the crankshaft to a camshaft, the endless
transmission
member being disposed in an upper part of an engine, wherein a thermostat for
controlling the flow of cooling water in a water jacket formed in the engine
is provided in
an upper wall of the engine above the endless transmission member.
In accordance with this arrangement, since the thermostat for controlling the
flow
of cooling water in the water jacket of the engine is provided in the upper
wall of the
engine above the endless transmission member for transmitting the driving
force of the
crankshaft to the camshaft, the thermostat can easily be accessed from the top
of the
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CA 02564160 2006-11-06
engine for maintenance without being obstructed by the endless transmission
member,
and moreover it is easy to manipulate a cooling water pipe for discharging
cooling water
from the thermostat.
I n order to accomplish the second object, a fourth aspect of the present
invention
provides a water-cooled vertical engine that includes a crankshaft disposed
substantially vertically and an endless transmission member for transmitting a
driving
force of the crankshaft to a camshaft, the endless transmission member being
disposed
within an endless transmission member housing chamber formed by joining a
cover to
an upper face of an engine block, wherein a thermostat for controlling the
flow of
cooling water in a water jacket formed in the engine block is provided in the
cover, and
a cooling water passage for providing communication between the water jacket
and the
thermostat is integrally formed with the cover.
In accordance with this arrangement, since the thermostat for controlling the
flow
of cooling water in the water jacket of the engine block is provided in the
cover forming
the endless transmission member housing chamber in cooperation with the engine
block, and the water jacket and the thermostat are made to communicate with
each
other via the cooling water passage formed in the cover, not only it is easy
to carry out
maintenance of the thermostat from the top of the engine, but also a special
cooling
water pipe for providing communication between the water jacket and the
thermostat
can be omitted, thereby reducing the number of components and the number of
assembly steps.
In order to accomplish the second object, in accordance with a fifth aspect of
the
present invention, in addition to the fourth aspect, there is provided a water-
cooled
vertical engine wherein a drain pipe for discharging cooling water from the
thermostat is
formed from a member that is separate from the cover.
In accordance with this arrangement, since the drain pipe for discharging
cooling
water from the thermostat is formed from a member that is separate from the
cover, it is
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CA 02564160 2006-11-06
easy to manipulate the cooling water pipe.
In order to accomplish the second object, a sixth aspect of the present
invention
provides an outboard motor equipped with a water-cooled vertical engine that
includes
a crankshaft disposed substantially vertically and an endless transmission
member for
transmitting a driving force of the crankshaft to a camshaft, the endless
transmission
member being disposed within an endless transmission member housing chamber
formed by joining a cover to an upper face of an engine block, wherein a
thermostat for
controlling the flow of cooling water in a water jacket formed in the engine
block is
provided in the cover, and a cooling water passage for providing communication
between the water jacket and the thermostat is integrally formed with the
cover.
In accordance with this arrangement, since the thermostat for controlling the
flow
of cooling water in the water jacket of the engine block is provided in the
cover forming
the endless transmission member housing chamber in cooperation with the engine
block, and the water jacket and the thermostat are made to communicate with
each
other via the cooling water passage formed in the cover, not only it is easy
to carry out
maintenance of the thermostat from the top of the engine, but also a special
cooling
water pipe for providing communication between the water jacket and the
thermostat
can be omitted, thereby reducing the number of components and the number of
assembly steps.
In order to accomplish the third object, a seventh aspect of the present
invention
provides a water-cooled vertical engine that includes a crankshaft disposed
substantially vertically, a first thermostat for controlling the flow of
cooling water in a
cylinder block cooling water jacket formed in a cylinder block, and a second
thermostat
for controlling the flow of cooling water in a cylinder head cooling water
jacket formed in
a cylinder head, wherein a cylinder block cooling water jacket cooling water
outlet
connected to the first thermostat and a cylinder head cooling water jacket
cooling water
outlet connected to the second thermostat are in proximity to each other, and
a member
CA 02564160 2006-11-06
for forming a thermostat chamber housing the first and second thermostats
therewithin
is joined to the cylinder block and the cylinder head which have the two
cooling water
outlets.
In accordance with this arrangement, since the member for forming the
thermostat chamber housing the first thermostat for controlling the flow of
cooling water
in the cylinder block cooling water jacket and the second thermostat for
controlling the
flow of cooling water in the cylinder head cooling water jacket is joined to
the cylinder
block and the cylinder head so as to cover the cylinder block cooling water
jacket
cooling water outlet and the cylinder head cooling water jacket cooling water
outlet,
which are disposed in proximity to each other, the first and second
thermostats can be
arranged compactly, thereby reducing the mounting space.
In order to accomplish the third object, in accordance with an eighth aspect
of
the present invention, in addition to the seventh aspect, there is provided a
water-
cooled vertical engine wherein an endless transmission member for transmitting
a
driving force of the crankshaft to a camshaft is provided in an upper part of
an engine
block, and the first and second thermostats are arranged on the inside of the
endless
transmission member.
In accordance with this arrangement, since the thermostats are arranged on the
inside of the endless transmission member for transmitting the driving force
of the
crankshaft to the camshaft in the upper part of the engine block, the space on
the inside
of the endless transmission member can be utilized effectively for arranging
the first
and second thermostats compactly.
In order to accomplish the third object, in accordance with a ninth aspect of
the
present invention, in addition to the seventh aspect, there is provided a
water-cooled
vertical engine wherein the first and second thermostats have a common cooling
water
drain part.
In accordance with this arrangement, since the common cooling water drain part
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CA 02564160 2006-11-06
is provided for the first and second thermostats, the number of pipes for
draining
cooling water can be reduced to one, thereby decreasing the number of
components.
In order to accomplish the third object, a tenth aspect of the present
invention
provides an outboard motor equipped with a water-cooled vertical engine that
includes
a crankshaft disposed substantially vertically, a first thermostat for
controlling the flow of
cooling water in a cylinder block cooling water jacket formed in a cylinder
block, and a
second thermostat for controlling the flow of cooling water in a cylinder head
cooling
water jacket formed in a cylinder head, wherein a cylinder block cooling water
jacket
cooling water outlet connected to the first thermostat and a cylinder head
cooling water
jacket cooling water outlet connected to the second thermostat are in
proximity to each
other, and a member for forming. a thermostat chamber housing the first and
second
thermostats therewithin is joined to the cylinder block and the cylinder head
which have
the two cooling water outlets.
In accordance with this arrangement, since the member for forming the
thermostat chamber housing the first thermostat for controlling the flow of
cooling water
in the cylinder block cooling water jacket and the second thermostat for
controlling the
flow of cooling water in the cylinder head cooling water jacket is joined to
the cylinder
block and the cylinder head so as to cover the cylinder block coolirig water
jacket
cooling water outlet and the cylinder head cooling water jacket cooling water
outlet
which are disposed in proximity to each other, the first and second
thermostats can be
arranged compactly, thereby reducing the mounting space.
A cylinder block and a cylinder head of an embodiment correspond to the
engine block of the present invention, cooling water passages and of the
embodiment coirespond to the cooling water outlets of the present invention, a
timing
chain of the embodiment corresponds to the endless transmission member of the
present invention, a chain cover of the embodiment corresponds to the cover or
the
member for forming the thermostat chamber of the present invention, first and
second
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70488-264D
thermostats and of the embodiment correspond to the
thermostat of the present invention, a cylinder block
cooling water jacket and a cylirider head cooling water
jacket of the embodiment correspond to the water jacket of
the present invention, and a coupling of the embodiment
corresponds to the cooling water drain part of the present
invention. Further, the chain cover of the embodiment forms
a part of the engine.
Thus, in a broad aspect, the invention provides a
water-cooled vertical engine comprising: a crankshaft
disposed substantially vertically; a cylinder block; a
cylinder block cooling water jacket formed in the cylinder
block; a first thermostat for controlling the flow of
cooling water in the cylinder block cooling water jacket; a
cylinder head; a cylinder head cooling water jacket formed
in the cylinder head; and a second thermostat for
controlling the flow of cooling water in the cylinder head
cooling water jacket; wherein the cylinder block cooling
water jacket has a cooling water outlet connected to the
first thermostat, the cylinder head cooling water jacket has
a cooling water outlet connected to the second thermostat,
the cooling water outlets being in proximity to each other;
and wherein the engine further comprises: a thermostat
chamber housing the first and second thermostats
therewithin; and a member for forming the thermostat
chamber, the member being joined to the cylinder block and
the cylinder head which have the two cooling water outlets;
and a common drain pipe for the first and second thermostats
is connected to the thermostat member at a position outside
of the cylinder head and the cylinder block.
In another aspect, the invention provides an
outboard motor equipped with a water-cooled vertical engine
comprising: a crankshaft disposed substantially vertically;
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CA 02564160 2009-03-24
70488-264D
a cylinder block; a cylinder block cooling water jacket
formed in the cylinder block; a first thermostat for
controlling the flow of cooling water in the cylinder block
cooling water jacket; a cylinder head; a cylinder head
cooling water jacket formed in the cylinder head; and a
second thermostat for controlling the flow of cooling water
in the cylinder head cooling water jacket; wherein the
cylinder block cooling water jacket has a cooling water
outlet connected to the first thermostat, the cylinder head
cooling water jacket has a cooling water outlet connected to
the second thermostat, the cooling water outlets being in
proximity to each other; and wherein the engine further
comprises: a thermostat chamber housing the first and second
thermostats therewithin; and a member for forming the
thermostat chamber, the member being joined to the cylinder
block and the cylinder head which have the two cooling water
outlets; and a common drain pipe for the first and second
thermostats is connected to the thermostat member at a
position outside of the cylinder head and the cylinder
block.
The above-mentioned object, other objects,
characteristics, and advantages of the present invention
will become apparent from an explanation of a preferred
embodiment, which will be described in detail below by
reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 to FIG. 19 illustrate one embodiment of the
present invention.
FIG. 1 is an overall side view of an outboard
motor.
8a
CA 02564160 2009-03-24
70488-264D
FIG. 2 is an enlarged cross-sectional view at
line 2-2 in FIG. 1.
FIG. 3 is an enlarged cross-sectional view at
line 3-3 in FIG. 2.
FIG. 4 is an enlarged view from arrow 4 in FIG. 2.
FIG. 5 is a view from arrow 5 in FIG. 4.
FIG. 6 is an enlarged cross-sectional view of an
essential part in FIG. 1.
FIG. 7 is an enlarged view from an arrowed
line 7-7 in FIG. 1 (top view of a mount case).
FIG. 8 is an enlarged view from an arrowed
line 8-8 in FIG. 1 (bottom view of a pump body).
FIG. 9 is an enlarged view from an arrowed
line 9-9 in FIG. 1 (bottom view of a subassembly of a block,
etc.).
FIG. 10 is an enlarged view of an exhaust
manifold.
FIG. 11 is an enlarged view of a connection
between the exhaust manifold and
8b
CA 02564160 2006-11-06
an exhaust guide.
FIG. 12 is a view from an arrowed line 12-12 in FIG. 11 (plan view of the
exhaust
guide).
FIG. 13 is a cross-sectional view at line 13-13 in FIG. 11.
FIG. 14 is an enlarged view from an arrowed line 14-14 in FIG. 1.
FIG. 15 is an enlarged view from an arrowed line 15-15 in FIG. 1.
FIG. 16 is an enlarged cross-sectional view at line 16-16 in FIG. 15.
FIG. 17 is a cross-sectional view at line 17-17 in FIG. 16.
FIG. 18 is a cross-sectional view at line 18-18 in FIG. 16.
FIG. 19 is a circuit diagram of an engine cooling system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIGS. 1 to 3, an outboard motor 0 is mounted on a hull so that a
steering movement can be carried out in the left and right directions around a
steering
shaft 96, and a tilting movement can be carried out in the vertical direction
around a tilt
shaft 97. An inline four-cylinder four-stroke water-cooled vertical engine E
mounted in
an upper part of the outboard motor 0 includes a cylinder block 11, a lower
block 12
joined to a front face of the cylinder block 11, a crankshaft 13 disposed in a
substantially
vertical direction and supported so that journals 13a are held between the
cylinder
block 11 and the lower block 12, a crankcase 14 joined to a front face of the
lower block
12, a cylinder head 15 joined to a rear face of the cylinder block 11, and a
head cover
16 joined to a rear face of the cylinder head 15. Four sleeve-form cylinders
17 are
surround-cast in the cylinder block 11, and pistons 18 are slidably fitted
within the
cylinders 17 and connected to crankpins 13b of the crankshaft 13 via
connecting rods
19.
Combustion chambers 20 are formed in the cylinder head 15 so as to face the
top faces of the pistons 18, and are connected to an intake manifold 22 via
intake ports
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21 and to an engine compartment exhaust passage 24 via exhaust ports 23, the
intake
ports 21 opening on a left-hand face of the cylinder head 15, that is, on the
left side of
the vessel when facing the direction of travel, and the exhaust ports 23
opening on a
right-hand face of the cylinder head 15. Intake valves 25 for opening and
closing the
downstream ends of the intake ports 21 and exhaust valves 26 for opening and
closing
the upstream ends of the exhaust ports 23 are made to open and close by a DOHC
type
valve operating mechanism 27 housed within the head cover 16. The upstream
side
of the intake manifold 22 is connected to a throttle valve 29 disposed in
front of the
crankcase 14 and fixed to a front face thereof, and intake air is supplied to
the intake
manifold 22 via a silencer 28. An injector base 57 is held between the
cylinder head
15 and the intake manifold 22, and injectors 58 for injecting fuel into the
intake ports 21
are provided in the injector base 57.
Joined to upper faces of the cylinder block 11, the lower block 12, the
crankcase
14, and the cylinder head 15 of the engine E is a chain cover 31 (see FIG. 15)
housing a
timing chain 30 (see FIG. 14) for transmitting a driving force of the
crankshaft 13 to the
valve-operating mechanism 27. Joined to the lower faces of the cylinder block
11, the
lower block 12, and the crankcase 14 is an oil pump body 34. Joined to the
lower face
of the oil pump body 34 are, in sequence, a mount case 35, an oil case 36, an
extension case 37, and a gear case 38.
The oil pump body 34 has an oil pump 33 housed between the lower face thereof
and the upper face of the mount case 35 and has, on the opposite side, a
flywheel 32
disposed between itself and the lower face of the cylinder block 11, etc. The
oil pump
body 34 defines a flywheel chamber and an oil pump chamber. The oil case 36,
the
mount case 35, and the surroundings of a part of the lower side of the engine
E are
covered with a synthetic resin under cover 39, and an upper part of the engine
E is
covered with a synthetic resin engine cover 40, which is joined to the upper
face of the
under cover 39.
CA 02564160 2006-11-06
A drive shaft 41 is connected to the lower end of the crankshaft 13, runs
through
the pump body 34, the mount case 35, and the oil case 36, extends downward
within
the extension case 37, and is connected via a forward/reverse travel switching
mechanism 45 to the front end of a propeller shaft 44 having a propeller 43
provided at
its rear end and being supported by the gear case 38 in the fore-and-aft
direction, the
forward/reverse travel switching mechanism 45 being operated by a shift rod
52. A
cooling water pump 46 is provided on the drive shaft 41 and is connected to a
lower
water supply passage 48 extending upward from a strainer 47 provided in the
gear case
38. An upper water supply pipe 49 extends upward from the cooling water pump
46
and is connected to a cooling water passage 36b (see FIG. 6) provided in the
oil case
36.
As shown in FIG. 6, a cooling water supply hole 36a is formed in a lower face
36L of the oil case 36 and is connected to the upper end of the upper water
supply pipe
49. The cooling water passage 36b, which communicates with the cooling water
supply hole 36a, is formed in an upper face 36U of the oil case 36 so as to
surround
part of an exhaust pipe section 36c formed integrally with the oil case 36. A
cooling
water passage 35a is formed so as to surround part of an exhaust passage 35b
running
through the mount case 35, the cooling water passage 35a having the same shape
as
that of the cooling water passage 36b in the upper face 36U of the oil case
36, which is
joined to a lower face 35L of the mount case 35.
FIG. 7 is a view of the mount case 35 from above. The oil case 36 is joined to
the lower face of the mount case 35. The outer periphery of the exhaust
passage 35b
is surrounded by cooling water supply passages 35c and a cooling water drain
passage
35d. In detail, the cooling water passage 35a is formed so as to open downward
on
the lower face 35L of the mount case 35, and the cooling water supply passages
35c
(see FIG. 6), which communicate with the cooling water passage 35a, are formed
so as
to open upward on the upper face 35U of the mount case 35 in an area outside a
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cylinder block mounting face and run along the outer periphery of the
cylindrical
exhaust passage 35b. In the embodiment, there are three of the cooling water
supply
passages 35c, which are arc-shaped and separated from each other by walls 35h
that
are connected to the outer wall of the exhaust passage 35b. Furthermore, the
one
cooling water drain passage 35d, which is arc-shaped, is formed around the
outer
periphery of the cylindrical exhaust passage 35b in a region outside the
region where
the cooling water supply passages 35c are provided, the cooling water drain
passage
35d being defined by walls 35i that form outer walls of the cooling water
supply
passages 35c.
A cooling water supply passage 35e is formed in the upper face 35U of the
mount case 35 in a channel shape having a U-shaped cross-section, the cooling
water
supply passage 35e opening upward on the upper face 35U and extending in the
left
and right directions of the outboard motor 0 so as to bridge the center of the
cylinder 17
in plan view (see FIG. 6), the upper face 35U of the mount case 35 being
joined to a
cylinder block subassembly containing the oil pump body 34, which will be
described
later. The above-mentioned cooling water passage 35a extends upward and
communicates with the cooling water passage 35e. Provided on the upper face
35U
of the mount case 35 is a relief valve 51 that opens to release cooling water
when the
pressure of the cooling water passage 35a reaches a predetermined value or
above
(see FIGS. 4 and 7).
The cooling water drain passage 35d communicates, via an opening 36e formed
over the entire area of the upper face 36U of the oil case 36 (see FIG. 7),
with an
exhaust chamber 63 formed within the oil case 36, the extension case 37, and
the gear
case 38. A gasket 55 is clamped between the lower face 35L of the mount case
35
and the upper face 36U of the oil case 36. Punched holes 55a and punched holes
55b
are provided in the gasket 55, the cooling water that has dropped from the
cooling
water drain passage 35d (see FIG. 7) of the mount case 35 passing through the
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punched holes 55a, and the punched holes 55b defining part of the exhaust
chamber
63 and exhibiting a silencing effect (see FIGS. 6 and 7).
The structure of the engine compartment exhaust passage 24 is now explained
by reference to FIGS. 4 to 6 and FIGS. 10 to 13.
Exhaust passage means is broadly divided into an engine compartment exhaust
passage 24 portion and an exhaust chamber portion separated from the engine
compartment. The engine compartment exhaust passage 24 is joined to a right
side
face of the cylinder head 15 as described below and includes an exhaust
manifold 61
and an exhaust guide 62 connected to the exhaust manifold 61 and guiding
exhaust
fumes outside the engine compartment. The exhaust manifold 61 comprises single
pipe sections 61 a for introducing exhaust fumes from each of the combustion
chambers
20 and a combined section 61 b in the downstream region of these single pipe
sections
61a.
As is clear from FIG. 6, the exhaust guide 62 is joined to the upper face 35U
of
the mount case 35, which forms an engine compartment partition, and
communicates
with the exhaust passage 35b running through the mount case 35. The exhaust
passage 35b communicates with the exhaust pipe section 36c formed integrally
with
the oil case 36 and communicates with the exhaust chamber 63. In the
embodiment,
the oil case 36 forms an outer wall section of the exhaust chamber 63 and also
forms
the exhaust pipe section 36c but, as another arrangement, the exhaust pipe
section 36c
may be formed as a separate passage. The exhaust passage means may be
arranged so that parts thereof are integrally connected, but it is also
possible to
separately form the engine compartment exhaust passage 24 and its external
passage,
thereby improving the ease of assembly of each section and maintaining the
sealing
properties of the exhaust chamber 63.
An upper part of the exhaust chamber 63 communicates with the outside of the
under cover 39 via an exhaust outlet pipe 64 provided in the oil case 36 so
that, when
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the engine E runs with a low load, the exhaust gas is discharged into the
atmosphere
via the exhaust outlet pipe 64 without being discharged into water.
The exhaust manifold 61 has four single pipe sections 61 a communicating with
the four exhaust ports 23, and the combined section 61 b where the single pipe
sections
61 a are integrally combined. The majority of the combined section 61b is in
intimate
contact with a side face of the cylinder head 15, but the vicinity of a lower
end part of the
combined section 61b is bent so that its center line is separated from the
side face of
the cylinder head 15 by only a distance a(see FIG. 10). The exhaust guide 62
is
curved into an S-shape, and the outer periphery of the lower end of the
exhaust
manifold 61 is fitted into the inner periphery of a large diameter joining
section 62a at
the upper end of the exhaust guide 62 via a pair of 0 rings 53 and 54.
In this way, only the vicinity of the lower end part of the exhaust manifold
61 is
bent away from the side face of the cylinder head 15, the other, remaining
upper half of
the intake manifold 61 is connected so as to follow the side face of the
cylinder head 15.
Therefore, it is possible to prevent the large diameter joining section 62a
from
interfering with the cylinder head 15 while minimizing the space for arranging
the engine
compartment exhaust passage 24. In particular, since the bent section of the
exhaust
manifold 61 is lower than the lowest combustion chamber 20, it is possible to
prevent
an imbalanced effect on the flows of exhaust gas from the plurality of
combustion
chambers 20, which are arranged in the vertical direction, thereby minimizing
any
reduction in exhaust efficiency.
Furthermore, since the exhaust manifold 61 and the joining section 62a of the
exhaust guide 62 have a structure in which they are fitted together via the 0
rings 53
and 54, not only is the operation of joining the exhaust manifold 61 and the
exhaust
guide 62 simple, but also dimensional errors in the vertical direction of the
engine
compartment exhaust passage 24 can be, absorbed by the joining section 62a,
thereby
improving the ease of assembly. Moreover, since an upper end part of a first
exhaust
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guide cooling water jacket JM1 and a lower end part of an exhaust manifold
cooling
water jacket JM2 are positioned in the vicinity of the 0 rings 53 and 54, it
is possible to
prevent the 0 rings 53 and 54 from deteriorating due to heat.
The exhaust guide 62 has a flange 62b formed at the lower end thereof. Three
bolt holes 62c, three cooling water inlets 62e, and one cooling water outlet
62f are
formed in the flange 62b, the three cooling water inlets 62e being arc-shaped
and
surrounding the exhaust passage 62d. When the flange 62b of the exhaust guide
62
is bolted to a mounting seat 35f (see FIG. 7) on the upper face 35U of the
mount case
35, the cooling water inlets 62e of the exhaust guide 62 communicate with the
cooling
water supply passages 35c of the mount case 35, and the cooling water outlet
62f
communicates with the cooling water drain passage 35d of the mount case 35.
With
regard to the lower face 35L side of the mount case 35 of the mounting seat
35f, among
the outer walls forming the cooling water drain passage 35d, the side opposite
the
exhaust passage 35b remains at a slightly higher position than the gasket
face, and
cooling water drains onto the gasket 55 through a gap between the lower face
of the
outer wall and the gasket face.
Formed in the exhaust guide 62 are the first exhaust guide cooling water
jacket
JM1 and a second exhaust guide cooling water jacket JM3, which surround the
exhaust
passage 62d. The first exhaust guide cooling water jacket JMI covers half of
the
periphery on the upper face side, and the second exhaust guide cooling water
jacket
JM3 covers half of the periphery on the lower face side. A part of the first
exhaust
guide cooling water jacket JM1 in the circumferential direction protrudes
radially at an
upper end part of the exhaust guide 62 to form a protruding portion 62g.
The exhaust manifold cooling water jacket JM2 is formed so as to surround the
exhaust manifold 61, and a through hole 61c extending in the circumferential
direction
is formed at the lower end of the exhaust manifold cooling water jacket JM2.
Therefore, when the lower end of the exhaust manifold 61 is fitted into the
inner
CA 02564160 2006-11-06
periphery of the joining section 62a of the exhaust guide 62, the exhaust
manifold
cooling water jacket JM2 of the exhaust manifold 61 and the first exhaust
guide cooling
water jacket JM1 of the exhaust guide 62 communicate with each other via the
through
hole 61 c of the exhaust manifold 61 and the protruding portion 62g of the
exhaust guide
62 (see FIG. 13).
As is clear from FIGS. 4 and 5, provided in an upper part of the exhaust
manifold
cooling water jacket JM2 of the exhaust manifold 61 are a coupling 61 d for
distributing
part of the cooling water to the cylinder block 11, a coupling 61 e for
supplying part of the
cooling water to a water check outlet 66 (see FIG. 2) via a hose 65, and a
cooling water
temperature sensor 67 for detecting the temperature of the cooling water.
The structure of the cooling system of the cylinder block 11 is now explained
by
reference to FIGS. 3 to 5.
The cooling water whose temperature has increased after cooling the engine
compartment exhaust passage 24 while passing through the first exhaust guide
cooling
water jacket JM1 of the exhaust guide 62 and the exhaust manifold cooling
water jacket
JM2 of the exhaust manifold 61 is supplied via a water supply pipe 68 to a T-
shaped
three-way joint, or a branching member 69, from the coupling 61 d provided at
the upper
end of the exhaust manifold cooling water jacket JM2 of the exhaust manifold
61, and
branches into two water supply pipes 70 and 71. A cylinder block cooling water
jacket
JB surrounding the four cylinders 17 is formed in the cylinder block 11.
Couplings 11 a
and 11 b are provided at positions close to the upper end of the cylinder
block cooling
water jacket JB (at the side of the second from highest combustion chamber 20)
and
close to the lower end of the cylinder block cooling water jacket JB (at the
side of the
lowest combustion chamber 20). The water supply pipe 70 on the upper side is
connected to the coupling 11 a on the upper side, and the water supply pipe 71
on the
lower side is connected to the coupling 11 b on the lower side. In this way,
since the
exhaust manifold cooling water jacket JM2 and the cylinder block cooling water
jacket
16
CA 02564160 2006-11-06
JB are connected via the water supply piles 68, 70, and 71, machining is
easier than a
case where cooling water supply passages are formed within the cylinder block
11 and
the cylinder head 15.
A slit-shaped cooling water passage 34a (see FIG. 8) formed so as to run
though
the pump body 34 communicates with the slit-shaped cooling water passage 35e
(see
FIG. 7) formed so as to run through the mount case 35 and also communicates
with a
cooling water passage 11 c (see FIG. 9) formed in the lower face of the
cylinder block 11,
the cooling water passage 11 c having the same mating surface shape as that of
the
cooling water passage 35e and extending in the left and right directions so as
to bridge
the middle in the left and right width direction of the cylinders 17. As shown
in FIGS. 3
and 9, the cooling water passage 11 c of the cylinder block 11 has a channel
shape
opening downward and communicates with the lower end of the cylinder. block
cooling
water jacket JB of the cylinder block 11 via two through holes 11 d and 11 e
running
through the upper wall of the channel.
As is clear from FIG. 3, after flowing through the cylinder block cooling
water
jacket JB of the cylinder block 11 the cooling water is supplied to a
thermostat, which
will be described later, through a cooling water passage 11f formed in an
upper left part
of the cylinder block 11.
The structure of the cooling system of the cylinder head 15 is now explained
by
reference to FIGS. 3, 6, and 9.
Two short cooling water passages 11 g and 11 h branch toward the cylinder head
15 from the side wall of the slit-shaped cooling water passage 11 c formed in
the lower
face of the cylinder block 11. These cooling water passages 11 g and 91 h
communicate with a cylinder head cooling water jacket JH of the cylinder head
15
through a gasket 56 provided between the cylinder block 11 and the cylinder
head 15.
The cylinder block cooling water jacket JB surrounding the cylinders 17 of the
cylinder
block 11 is isolated from the cylinder head cooling water jacket JH of the
cylinder head
17
CA 02564160 2006-11-06
15 via the gasket 56 disposed between the mating surfaces of the cylinder
block 11 and
the cylinder head 15 (see FIGS. 2 and 6).
The thermostat provided in the cooling water circulation system is now
explained.
As shown in FIG. 14, the timing chain 30 is wound around a cam drive sprocket
72 provided at the upper end of the crankshaft 13 and cam driven sprockets 75
provided on a pair of camshafts 73 and 74 positioned to the rear of the
cylinder head 15.
A hydraulic chain tensioner 76a abuts against the loose side of the timing
chain 30, and
a chain guide 76b abuts against the opposite side of the timing chain 30. The
number
of teeth of the cam drive sprocket 72 is half the number of teeth of the cam
driven
sprockets 75, and the camshafts 73 and 74 therefore rotate at a rotational
speed that is
half the rotational speed of the crankshaft 13.
A balancer 77 is housed within the crankcase 14. An endless chain 82 is
wound around a balancer drive sprocket 81 provided on the crankshaft 13 and a
balancer driven sprocket 80 provided on one of two balancer shafts 78 and 79
of the
balancer 77. A chain tensioner 83a abuts against the loose side of the endless
chain
82, and a chain guide 83b abuts against the opposite side of the endless chain
82.
The number of teeth of the balancer drive sprocket 81 is twice the number of
teeth of
the balancer driven sprocket 80, and the balancer shafts 78 and 79 therefore
rotate at a
rotational speed that is twice the rotational speed of the crankshaft 13.
As is clear from FIGS. 15 to 18, upper faces of the cylinder block 11 and the
cylinder head 15 are covered with the chain cover 31, and the timing chain 30
is housed
within the chain cover 31. In order to lubricate the timing chain 30, an oil
atmosphere
is maintained inside the chain cover 31. A thermostat mounting seat 31a is
formed on
the chain cover 31 so as to bridge the mating surfaces of the cylinder block
11 and the
cylinder head 15. The lower face of the thermostat mounting seat 31 a abuts
against
the upper faces of the cylinder block 11 and the cylinder head 15, and the
upper face is
18
CA 02564160 2006-11-06
stepped higher than the upper face of a main body portion of the chain cover
31. An
engine rotational speed sensor 59 for detecting the rotational speed of the
crankshaft
13 is provided on the chain cover 31 (see FIG. 15).
Formed in the thermostat mounting seat 31a of the chain cover 31 are cooling
water passages 31 b and 31 c and cooling water passages 31 d and 31 e, the
cooling
water passages 31b and 31c communicating with a cooling water passage 11 f
branching upward from the cylinder block cooling water jacket JB of the
cylinder block
11, and the cooling water passages 31d and 31 e communicating with a cooling
water
passage 15a branching from the cylinder head cooling water jacket JH of the
cylinder
head 15. A first thermostat 84 on the cylinder block 11 side is mounted in the
cooling
water passage 31c, and a second thermostat 85 on the cylinder head 15 side is
mounted in the cooling water passage 31e. The first thermostat 84 having a
valve
body 84a, and the second thermostat 85 having a valve body 85a, are housed
within
thermostat chambers 94 and 95 respectively and covered with a common
thermostat
cover 87 fixed to the upper face of the thermostat mounting seat 31 a by three
bolts 86.
A coupling 87a provided on the thermostat cover 87 is connected to the second
exhaust
guide cooling water jacket JM3 via a drain pipe 88 and a coupling 62h provided
on the
exhaust guide 62.
A cooling water temperature sensor 89 is provided in the cooling water passage
31 e of the chain cover 31, the cooling water passage 31 e facing the second
thermostat
85 on the cylinder head cooling water jacket JH side.
As explained above, combustion gas within the combustion chambers 20 shut off
by the intake valves 25 and the exhaust valves 26 is a first heat source,
exhaust gas
flowing to the outside through the engine compartment exhaust passage 24 is a
second
heat source, the cylinder head cooling water jacket JH and the cylinder block
cooling
water jacket JB correspond to first cooling means for cooling the first heat
source, and
the first exhaust guide cooling water jacket JM1 and the exhaust manifold
cooling water
19
CA 02564160 2006-11-06
jacket JM2 correspond to second cooling means, which cools the second heat
source
after exchanging heat with the first cooling means.
The structure of the lubrication system of the engine E is now explained by
reference to FIGS. 3, 4, and 6 to 9.
The oil case 36 is integrally provided with an oil pan 36d, and a suction pipe
92
having an oil strainer 91 is housed within the oil pan 36d. Provided in the
oil pump 33
are an oil intake passage 33a, an oil discharge passage 33b, and an oil relief
passage
33c. The oil intake passage 33a is connected to the suction pipe 92. The oil
discharge passage 33b is connected, via an oil supply hole 11 m(see FIG. 9)
formed in
the lower face of the cylinder block 11, to each section of the engine E that
is to be
lubricated. The oil relief passage 33c discharges return oil from the oil pump
33 into
the oil pan 36d.
Part of the return oil from the valve operating mechanism 27 provided within
the
cylinder head 15 and the head cover 16 is returned to the oil pan 36d via a
coupling 16a
provided on the head cover 16, an oil hose 93, and an oil return passage 35g
(see FIG.
7) running through the mount case 35. Another part of the return oil from the
valve
operating mechanism 27 is returned to the oil pan 36d via an oil return
passage 15b
(see FIG. 9) formed in the cylinder head 15, an oil return passage 11 j(see
FIG. 9)
opening on gasket faces of the cylinder block 11 and the cylinder head 15, an
oil return
passage 11 k(see FIG. 9) running through the cylinder block 11, an oil return
passage
34b (see FIG. 8) running through the pump body 34, and the oil return passage
35g
(see FIG. 7) running through the mount case 35. The oil return passage llj
opening
on the gasket 56 between the cylinder block 11 and the cylinder head 15 is
disposed
between the two cooling water passages 11 g and 11 h opening on the gasket 56
(see
FIG. 3).
Return oil from the crankcase 14 is returned to the oil pan 36d via an oil
return
passage (not illustrated) running through the pump body 34 and the oil return
passage
CA 02564160 2006-11-06
35g (see FIG. 7) running through the mount case 35.
The operation of the embodiment of the present invention having the above-
mentioned arrangement is now explained mainly by reference to the cooling
water
circuit shown in FIG. 19.
When the drive shaft 41 connected to the crankshaft 13 rotates in response to
operation of the engine E, the cooling water pump 46 provided on the drive
shaft 41
operates to supply cooling water, which is drawn up via the strainer 47, to
the cooling
water supply hole 36a on the lower face of the oil case 36 via the lower water
supply
passage 48 and the upper water supply pipe 49. The cooling water that has
passed
through the cooling water supply hole 36a flows into both the cooling water
passage
36b in the upper face 36U of the oil case 36 and the cooling water passage 35a
in the
lower face 35L of the mount case 35. Part of the cooling water branching
therefrom is
supplied to both the first exhaust guide cooling water jacket JM1 formed in
the exhaust
guide 62 of the engine compartment exhaust passage 24 and the exhaust manifold
cooling water jacket JM2 formed in the exhaust manifold 61. The exhaust gas
discharged from the combustion chambers 20 of the cylinder head 15 is
discharged into
the exhaust chamber 63 via the single pipe sections 61 a and the combined
section 61 b
of the exhaust manifold 61, the exhaust passage 62d of the exhaust guide 62,
the
exhaust passage 35b of the mount case 35, and the exhaust pipe section 36c of
the oil
case 36. The engine compartment exhaust passage 24, which is heated by the
exhaust gas during this process, is cooled by the cooling water flowing
through the first
exhaust guide cooling water jacket JM1 and the exhaust manifold cooling water
jacket
JM2.
The cooling water having a slightly increased temperature after flowing upward
through the first exhaust guide cooling water jacket JM1 and the exhaust
manifold
cooling water jacket JM2 branches from the coupling 61d provided at the upper
end of
the exhaust manifold 61 into the two water supply pipes 70 and 71 via the
water supply
21
CA 02564160 2006-11-06
pipe 68 and the branching member 69, and flows into the lower part and the
upper part
of the side face of the cylinder block cooling water jacket JB via the
couplings 11 a and
11 b provided on the cylinder block 11. During this process, part of the low
temperature
cooling water of the cooling water passages 36b and 35a flows into the lower
end of the
cylinder block cooling water jacket JB via the two through holes 11d and 11e
that open
in the cooling water passage 11c at the lower end of the cylinder block 11.
Furthermore, part of the low temperature cooling water of the cooling water
passages
36b and 35a flows from the cooling water passage 11 c at the lower end of the
cylinder
block 11 into the lower end of the cylinder head cooling water jacket JH via
the two
cooling water passages 11 g and 11 h.
While the engine E is warming up, both the first thermostat 84 connected to
the
upper end of the cylinder block cooling water jacket JB and the second
thermostat 85
connected to the upper end of the cylinder head cooling water jacket JH are
closed, and
the cooling water within the first exhaust guide cooling water jacket JM1, the
exhaust
manifold cooling water jacket JM2, the cylinder block cooling water jacket JB,
and the
cylinder head cooling water jacket JH is retained and does not flow, thereby
promoting
the warming up of the engine E. At this time, the cooling water pump 46
continues to
rotate, but since cooling water leaks from around a rubber impeller of the
cooling water
pump 46, the cooling water pump 46 is substantially at idle.
When the temperature of cooling water increases after the warming up of the
engine E is completed, the first and second thermostats 84 and 85 open, and
the
cooling water in the cylinder block cooling water jacket JB and the cooling
water in the
cylinder head cooling water jacket JH flow from the common coupling 87a of the
thermostat cover 87 into the second exhaust guide cooling water jacket JM3 via
the
drain pipe 88 and the coupling 62h of the exhaust guide 62. The cooling water
that
has cooled the exhaust guide 62 while flowing through the second exhaust guide
cooling water jacket JM3 is discharged into the exhaust chamber 63 after
passing
22
CA 02564160 2006-11-06
through the mount case 35 and the oil case 36 from top to bottom. When the
rotational speed of the engine E increases and the internal pressure of the
cooling
water passages 36b and 35a reaches a predetermined value or above, the relief
valve
51 opens and excess cooling water is discharged into the exhaust chamber 63.
The coupling 61 e provided at the upper end of the exhaust manifold cooling
water jacket JM2 of the exhaust manifold 61 is connected to the water check
outlet 66
via the hose 65, and circulation of cooling water can be confirmed by the
ejection of
water from the water check outlet 66. Since the coupling 61 e connected to the
water
check outlet 66 is provided at the upper end of the exhaust manifold cooling
water
jacket JM2, air that resides within the exhaust manifold cooling water jacket
JM2 can be
discharged from the water check outlet 66 together with the cooling water. In
this way,
since the air within the exhaust manifold cooling water jacket JM2 is
discharged by
utilizing the water check outlet 66, it is unnecessary to provide a special
pipe for
discharging air or a special air outlet, thereby contributing to reduction in
the number of
components and in the number of assembly steps.
Moreover, since the exhaust. manifold 61 and the water check outlet 66 are
provided on left and right sides of the outboard motor 0, even when the water
check
outlet 66 is positioned lower than the exhaust manifold 61, enlarging the
distance
between the exhaust manifold 61 and the water check outlet 66 reduces the
downward
slope, thereby smoothly pushing air within the exhaust manifold 61 toward the
water
check outlet 66.
In the present embodiment, the exhaust manifold cooling water jacket JM2
communicates with the cylinder block cooling water jacket JB, and the flow
rates of the
cooling water flowing through the first exhaust guide cooling water jacket
JMI, the
exhaust manifold cooling water jacket JM2, and the cylinder block cooling
water jacket
JB are controlled by the first thermostat 84. If the first exhaust guide
cooling water
jacket JMI and the exhaust manifold cooling water jacket JM2 did not
communicate
23
CA 02564160 2006-11-06
with the cylinder block cooling water jacket JB but were dead ends, it would
be
necessary to increase the diameter of the water check outlet 66 so as to
discharge the
entire amount of cooling water coming from the exhaust manifold cooling water
jacket
JM2, or to provide a cooling water outlet in addition to the water check
outlet 66 so as to
discharge the cooling water, and this would give rise to the problem that the
flow rate of
the cooling water would increase and the load of the cooling water pump 46
would
increase. However, in accordance with the present embodiment, since the first
exhaust guide cooling water jacket JM1 and the exhaust manifold cooling water
jacket
JM2 communicate with the cylinder block cooling water jacket JB, there is no
need to
wastefully discharge the cooling water that has passed through the first
exhaust guide
cooling water jacket JM1 and the exhaust manifold cooling water jacket JM2,
thereby
reducing the load of the cooling water pump 46.
Furthermore, the cylinder block cooling water jacket JB and the cylinder head
cooling water jacket JH are independent from each other; low temperature
cooling
water is supplied directly to. the cylinder head cooling water jacket JH which
easily
overheats during operation of the engine E; and the cooling water having an
increased
temperature after passing through the first exhaust guide cooling water jacket
JM1 and
the exhaust manifold cooling water jacket JM2 is supplied to the cylinder
block cooling
water jacket JB which is easily overcooled during operation of the engine E.
Therefore,
it is possible to cool the cylinder head 15 and the cylinder block 11 down to
their
appropriate temperatures, to maximizing the performance of the engine E.
Moreover,
since the thermostats 84 and 85 are provided in the cylinder block cooling
water jacket
JB and the cylinder head cooling water jacket JH respectively, changing
individually the
settings of the thermostats 84 and 85 enables the temperatures of the cooling
water in
the cylinder block cooling water jacket JB and the cylinder head cooling water
jacket JH
to be controlled independently and as desired.
If cooling water were supplied from the lower end of the cylinder block
cooling
24
CA 02564160 2006-11-06
water jacket JB, which extends vertically, and discharged from the upper end
thereof,
the temperature of the cooling water would become low in a lower part and high
in an
upper part, leading to a possibility that the cooling performance of the
cylinder block
cooling water jacket JB might be nonuniform in the vertical direction.
However, in
accordance with the present embodiment, the cooling water from the exhaust
manifold
cooling water jacket JM2 is supplied to the cylinder block cooling water
jacket JB at two
positions that are separated from each other in the vertical direction, and
the cooling
performance of the cylinder block cooling water jacket JB can therefore be
made
uniform in the vertical direction.
Even when fresh cooling water is supplied in response to a rapid increase in
the
rotational speed of the engine, the cooling water is supplied to the cylinder
block cooling
water jacket JB after the cooling water obtains a temperature increased while
passing
through the first exhaust guide cooling water jacket JM1 and the exhaust
manifold
cooling water jacket JM2. Therefore, any rapid change in the temperature
around the
combustion chambers 20 can be moderated.
Furthermore, supplying supplementary cooling water via the two through holes
11 d and 11 e to the lower end of the cylinder block cooling water jacket JB
prevents the
cooling water from residing within the cylinder block cooling water jacket JB,
and further
promotes the uniformity of the cooling performance. Moreover, since the
through
holes 11 d and 11 e are provided at the lower end of the cylinder block
cooling water
jacket JB, it is easy to deal with water remaining when the engine is stopped.
Furthermore, since supply of the cooling water from the cooling water passages
36b and 35a to the cylinder head cooling water jacket JH is not carried out
via an
external pipe but is carried out via the cooling water passages 11g and 11h
formed in
the cylinder block 11 and the gasket 56 between the cylinder head 11 and the
cylinder
head 15, not only is it unnecessary to specially assemble the cooling water
passages
11 g and 11 h, but also the number of components can be reduced by omitting
the
CA 02564160 2006-11-06
external pipe. Moreover, since the cooling water passages 11 g and 11 h can be
seaied
by utilizing the gasket 56 clamped between the cylinder block 11 and the
cylinder head
15, no special seal is needed, thus reducing the number of components.
Moreover,
since the cooling water passages 11 g and 11 h are provided at the lower end
of the
cylinder head cooling water jacket JH, it is easy to deal with water remaining
when the
engine is stopped.
In particular, since the two cooling water passages 11 g and 11 h for
delivering
cooling water from the cylinder block cooling water jacket JB to the cylinder
head
cooling water jacket JH are provided so as to be separated in the left and
right
directions, cooling water can be supplied evenly to the left and right sides
of the cylinder
head cooling water jacket JH, thereby improving the cooling effect. Moreover,
since
the oil return passage 11 j for guiding oil returning from the cylinder head
15 is provided
between the two cooling water passages 11 g and 11 h, the cooling water
passages 11 g
and llh and the oil return passage 11 j provided in the lowest part of a cam
chamber
can be arranged compactly in a confined space, while preventing the flow rates
of the
cooling water flowing through the two cooling water passages 11 g and 11 h
from
becoming imbalanced.
Furthermore, since the through holes 11 d and 11 e communicating with the
cylinder block cooling water jacket JB and the cooling water passages 11 g and
l1 h
communicating with the cylinder head cooling water jacket JH are branched in
the
cooling water passage 11 c which is a branching part formed within the
cylinder block 11,
it is unnecessary to provide a special seal in the branching part, thereby
reducing the
number of components.
When the temperature of the cooling water increases abnormally during
operation of the engine E, an alarm is raised for the possibility that the
engine E might
overheat. In the present embodiment, the cooling water temperature sensor 67
for the
cooling system comprising the first exhaust guide cooling water jacket JM1,
the exhaust
26
CA 02564160 2006-11-06
manifold cooling water jacket JM2, and the cylinder block cooling water jacket
JB is
provided at the upper end of the exhaust manifold cooling water jacket JM2,
and the
cooling water temperature sensor 89 for the cooling system comprising the
cylinder
head cooling water jacket JH is provided in the vicinity of the second
thermostat 85.
In this way, a total of four water jackets, that is, the first exhaust guide
cooling
water jacket JM1, the exhaust manifold cooling water jacket JM2, the cylinder
block
cooling water jacket JB, and the cylinder head cooling water jacket JH, are
divided into
two systems. Therefore, it is only necessary to provide one cooling water
temperature
sensor 67 for the first exhaust guide cooling water jacket JM1, the exhaust
manifold
cooling water jacket JM2, and the cylinder block cooling water jacket JB.
Thus, the
number of components can be reduced in comparison with a case in which each of
the
four water jackets is provided with a cooling water temperature sensor.
In particular, since, among the first exhaust guide cooling water jacket JM1,
the
exhaust manifold cooling water jacket JM2, and the cylinder block cooling
water jacket
JB, the cooling water temperature sensor 67 is provided in the exhaust
manifold cooling
water jacket JM2 in upstream of the cylinder block cooling water jacket JB, an
abnormal
increase in the temperature of the cooling water can be detected promptly.
Furthermore, since the cooling water temperature sensor 67 of the exhaust
manifold
cooling water jacket JM2 is provided in the vicinity of the coupling 61e
connected to the
water check outlet 66, the flow of cooling water toward the water check outlet
66 can
prevent the cooling water from residing in the vicinity of the cooling water
temperature
sensor 67, thereby improving the accuracy with which the temperature of the
cooling
water is detected.
The first thermostat 84 for controlling the discharge of cooling water from
the
cylinder block cooling water jacket JB and the second thermostat 85 for
controlling the
discharge of cooling water from the cylinder head cooling water jacket JH are
provided
on the upper wall of the chain cover 31 that covers the timing chain 30 which
provides
27
CA 02564160 2006-11-06
connections between the crankshaft 13 and the camshafts 73 and 74 on the upper
face
of the engine E. Therefore, the first and second thermostats 84 and 85 can
easily be
serviced from above by removing only the engine cover 40 without being
obstructed by
the chain cover 31 or the timing chain 30.
Furthermore, since the cooling water passages 31b and 31c providing a
connection between the cylinder block cooling water jacket JB and the first
thermostat
84 and the cooling water passages 31d and 31 e providing a connection between
the
cylinder head cooling water jacket JH and the second thermostat 85 are formed
in the
chain cover 31, the number of components can be reduced in comparison with a
case
in which connection is carried out via external pipes. Moreover, since the
outlet sides
of the first and second thermostats 84 and 85 are connected to the second
exhaust
guide cooling water jacket JM3 via the common drain pipe 88, not only is it
unnecessary
to form in the interior of the engine E a passage through which cooling water
is
discharged, thus making machining easy, but also only one drain pipe 88 is
required,
thereby reducing the number of components.
Furthermore, since the first thermostat 84 on the cylinder block 11 side and
the
second thermostat 85 on the cylinder head 15 side are arranged in proximity to
each
other, and the first and second thermostats 84 and 85 are mounted on the chain
cover
31, which is joined to the cylinder block 11 and the cylinder head 15 via the
common
gasket face, it is possible to mount the first and second thermostats 84 and
85
compactly in a confined space. In particular, since the thermostat chambers 94
and 95
housing the first and second thermostats 84 and 85 are positioned above the
plane in
which the timing chain 30 rotates, it is possible to avoid any mutual
interference,
thereby preventing any increase in the dimensions and achieving a compact
arrangement. Moreover, the cooling water passages 31b and 31d communicating
with
the thermostat chambers 94 and 95 are disposed within the loop of the timing
chain 30,
so that dead space can be utilized effectively, and it is possible to prevent
any increase
28
CA 02564160 2006-11-06
in the dimensions to achieve a compact arrangement while avoiding any mutual
interference.
Furthermore, since cooling water is discharged from the highest part of the
cylinder block cooling water jacket JB and the highest part of the cylinder
head cooling
water jacket JH, the discharge of cooling water is easy.
Moreover, since the upper side coupling 11 a for supplying cooling water to
the
cylinder block cooling water jacket JB is provided not at the side of the
highest
combustion chamber 20 but at the side of the second from highest combustion
chamber 20, it is possible to prevent the first thermostat 84 from operating
inappropriately due to low temperature cooling water supplied from the
coupling 11 a
acting on the first thermostat 84. In addition, in order to make the first
thermostat 84
operate appropriately, the coupling 11 a should be positioned at least lower
than the
vertically middle position of the highest combustion chamber 20.
An embodiment of the present invention is explained above, but the present
invention is not limited to the above-mentioned embodiment and can be modified
in a
variety of ways without departing from the subject matter of the present
invention.
For example, in the embodiment, the multicylinder water-cooled vertical engine
E is illustrated, but the present invention can also be applied to a single
cylinder water-
cooled vertical engine.
Furthermore, in the embodiment, the timing chain 30 is illustrated as the
endless
transmission member, but a timing belt can be used instead of the timing chain
30.
Moreover, in the embodiment, the chain cover 31 is illustrated as the cover,
but it
acts as a belt cover when the timing belt is employed as the endless
transmission
member.
Furthermore, the engine block of the embodiment is formed from the cylinder
block 11 and the cylinder head 15, but it may include a lower block, a
crankcase, a
head cover, etc.
29
CA 02564160 2006-11-06
Moreover, in the embodiment, the upper wall of the engine block is formed from
the chain cover 31 which is joined to the cylinder block and the cylinder
head, but the
upper wall is not limited to the chain cover 31; it may be the upper wall of
any member
joined to an upper face of the engine block, or it may be the upper wall of
the engine
block itself.
