U.S. patent number RE36,451 [Application Number 08/644,404] was granted by the patent office on 1999-12-21 for two-stroke internal combustion engine with improved air intake system.
This patent grant is currently assigned to Outboard Marine Corporation. Invention is credited to Fletcher C. Belt, George T. Gillespie, H. Norman Peterson.
United States Patent |
RE36,451 |
Gillespie , et al. |
December 21, 1999 |
Two-stroke internal combustion engine with improved air intake
system
Abstract
A two-stroke internal combustion engine comprising an engine
block, a plurality of crankcases and including a mounting surface
having therein a plurality of inlet openings each communicating
with a respective one of the crankcases, a throttle housing
defining a throttle passage and including a plenum mounting
surface, a throttle valve in the throttle passage, and a plenum
member which is separable from both the engine block and the
throttle housing and which defines a plurality of intake passages
each having an outlet end communicating with a respective one of
the inlet openings and each having an inlet end communicating with
the throttle passage such that the intake of the engine can be
tuned solely by modifying the configuration of the plenum
member.
Inventors: |
Gillespie; George T.
(Littlehampton, GB), Belt; Fletcher C. (Woodstock,
IL), Peterson; H. Norman (Kenosha, WI) |
Assignee: |
Outboard Marine Corporation
(Waukegan, IL)
|
Family
ID: |
26726071 |
Appl.
No.: |
08/644,404 |
Filed: |
May 1, 1996 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
954492 |
Sep 30, 1992 |
5273016 |
|
|
Reissue of: |
048380 |
Apr 15, 1993 |
05410999 |
May 2, 1995 |
|
|
Current U.S.
Class: |
123/403;
123/73A |
Current CPC
Class: |
F02M
35/10085 (20130101); F02M 35/167 (20130101); F02M
35/1019 (20130101); F02B 61/045 (20130101); F02M
35/116 (20130101); F02B 75/22 (20130101); F02M
35/10275 (20130101); F02M 35/10249 (20130101); F02F
2200/06 (20130101); F02B 2075/025 (20130101); Y02T
10/14 (20130101); Y02T 10/12 (20130101); F05C
2225/08 (20130101); F02B 2075/1824 (20130101) |
Current International
Class: |
F02B
75/00 (20060101); F02B 75/22 (20060101); F02M
35/116 (20060101); F02B 61/04 (20060101); F02B
61/00 (20060101); F02M 35/00 (20060101); F02M
35/16 (20060101); F02M 35/104 (20060101); F02M
35/10 (20060101); F02B 75/02 (20060101); F02B
75/18 (20060101); F02M 035/10 () |
Field of
Search: |
;123/403,73A,73R,41.31,59B,184.47,184.51,184.53,184.41 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McMahon; Marguerite
Attorney, Agent or Firm: Armstrong Teasdale LLP
Parent Case Text
RELATED APPLICATION
This is a continuation-in-part of U.S. Ser. No. 07/954,492, filed
Sep. 30, 1992, now U.S. Pat. No. 5,273,016 (Atty. Docket No.
72012/1040).
Claims
We claim:
1. A two-stroke internal combustion engine comprising a cylinder
block including a generally planar crankcase mounting surface
having therein a crankcase recess, a crankcase cover including a
generally planar cylinder block mounting surface mating with said
crankcase mounting surface and having therein a crankcase recess
aligned with said crankcase recess in said cylinder block and
defining therewith a crankcase, and air intake means for supplying
a flow of air to said crankcase, said air intake means defining a
U-shaped.Iadd., generally horizontal, .Iaddend.air intake path
having a downstream leg directed toward and generally perpendicular
to said crankcase mounting surface .Iadd.and affording air flow in
the rearward direction toward said crankcase .Iaddend.and having an
upstream leg .Iadd.extending .Iaddend.generally parallel to and
directed opposite said downstream leg .Iadd.and affording air flow
in the forward direction.Iaddend..
2. An engine as set forth in claim 1 wherein said intake path has a
plurality of downstream legs. .[.3. An engine as set forth in claim
1 wherein said upstream and downstream legs define a generally
horizontal
plane..].4. An engine as set forth in claim 1 wherein said
crankcase mounting surface and said cylinder block mounting surface
lie in a
generally vertically extending plane. 5. An engine as set forth in
claim 1 wherein said crankcase cover includes an intake manifold
mounting surface
having therein an inlet opening communicating with said crankcase.
6. An engine as set forth in claim 5 wherein said air intake means
includes an intake manifold including a crankcase cover mounting
surface mating with
said intake manifold mounting surface. 7. An engine as set forth in
claim 6 wherein said intake manifold includes a plenum mounting
surface opposed to said crankcase cover mounting surface and an
intake passage extending from said plenum mounting surface to said
crankcase cover mounting surface
and communicating with said inlet opening. 8. An engine as set
forth in claim 7 wherein said intake manifold includes a throttle
passage extending from said plenum mounting surface parallel to
said intake passage, said throttle passage being laterally offset
from said intake manifold mounting
surface. 9. An engine as set forth in claim 8 wherein said intake
means further includes a plenum cover including an inner surface
mating with said plenum mounting surface, said plenum cover
cooperating with said intake manifold to define an intake chamber
communicating with said
throttle passage. 10. An engine as set forth in claim 9 wherein
said plenum cover also cooperates with said intake manifold to
define an intake runner passage communicating between said intake
chamber and said intake
passage. 11. A two-stroke internal combustion engine comprising an
engine block defining a crankcase including an intake manifold
mounting surface having therein an inlet opening communicating with
said crankcase, an intake manifold having a crankcase cover
mounting surface mating with said intake manifold mounting surface,
a plenum mounting surface spaced from and extending in parallel
relation to said crankcase cover mounting surface, and an intake
passage extending from said plenum mounting surface to said inlet
opening and generally perpendicularly to said plenum mounting
surface, and a plenum cover including an inner surface mating with
said plenum mounting surface, and an intake runner passage
communicating with said intake passage and extending from said
intake
passage in lateral relation to said plenum mounting surface. 12. An
engine as set forth in claim 11 wherein said plenum cover also
cooperates with said intake manifold to define an intake chamber,
and wherein said intake runner passage communicates between said
intake chamber and said intake
passage. 13. An engine as set forth in claim 11 wherein said engine
block means includes a cylinder block including a crankcase
mounting surface having therein a crankcase recess, and a crankcase
cover including a cylinder block mounting surface mating with said
crankcase mounting surface and having therein a crankcase recess
aligned with said crankcase recess in said cylinder block to define
said crankcase, and wherein said
crankcase cover includes said intake manifold mounting surface. 14.
An engine as set forth in claim 11 wherein said engine block means
defines a plurality of crankcases, wherein said intake manifold
mounting surface has therein a plurality of inlet openings each of
which respectively communicates with a respective crankcase, and
wherein said plenum cover and said intake manifold cooperate to
define a plurality of intake runner passages each of which
respectively communicates with a respective inlet
opening. 15. An engine as set forth in claim 14 wherein said engine
block means includes a V-type cylinder block, and wherein all of
said inlet
openings are in-line. 16. A two-stroke internal combustion engine
comprising a cylinder block including a generally planar crankcase
cover mounting surface having therein a crankcase recess, a
crankcase cover including a generally planar cylinder block
mounting surface mating with said crankcase cover mounting surface
and having therein a crankcase recess aligned with said crankcase
recess in said cylinder block to define a crankcase, air intake
means for supplying air to said crankcase and including a throttle
housing and a wall located intermediate said throttle housing and
said crankcase and partially defining an air passageway
communicating between said throttle housing and said crankcase,
said wall having therein an opening communicating with said
passageway, an electronic control unit mounted on said wall, and
means for cooling said electronic control unit including a
plurality of cooling fins extending from said electronic control
unit and through said opening and into said
passageway. 17. A two-stroke internal combustion engine comprising
an engine block means defining a crankcase and including an intake
manifold mounting surface having therein an inlet opening
communicating with said crankcase, an intake manifold including a
crankcase cover mounting surface mating with said intake manifold
mounting surface, a plenum mounting surface opposed to said
crankcase cover mounting surface, an intake passage extending from
said plenum mounting surface to said crankcase cover mounting
surface and communicating with said inlet opening, and a throttle
passage extending from said plenum mounting surface and parallel to
said intake passage, said throttle passage being laterally offset
from said intake manifold mounting surface, and means for
conducting air from
said throttle passage to said intake passage. 18. An engine as set
forth in claim 17 wherein said intake manifold supports at least
one of any of an electronic control unit, a plurality of reed
boxes, a throttle linkage which is connected to a throttle plate, a
cable mount which supports a
throttle control cable, a timing pointer, and an alternator. 19. An
outboard motor having forward and rearward ends and comprising a
propulsion unit adapted to be mounted on the transom of a boat,
said propulsion unit including a propeller shaft with a rearward
end adapted to have mounted thereon a propeller, and said
propulsion unit also including a two-stroke internal combustion
engine drivingly connected to said propeller shaft, said engine
including engine block means defining a crankcase and air intake
means for supplying air to said crankcase, said air intake means
defining a U-shaped.Iadd., generally horizontal, .Iaddend.air
intake path having a rearwardly directed downstream leg
.Iadd.affording air flow in the rearward direction toward said
crankcase .Iaddend.and having a forwardly directed upstream leg
.Iadd.extending .Iaddend.generally parallel to said downstream leg
.Iadd.and affording air
flow in the forward direction.Iaddend.. 20. A two-stroke internal
combustion engine comprising an engine block including a cylinder
block including a crankcase cover mounting surface having therein a
crankcase recess, and a crankcase cover including a cylinder block
mounting surface mating with said crankcase cover mounting surface
and having therein a crankcase recess aligned with said crankcase
recess in said cylinder block to define a plurality of crankcases,
said crankcase cover also including an intake manifold mounting
surface having therein a like plurality of inlet openings
respectively communicating with said crankcases, a throttle housing
defining a throttle passage and including a plenum mounting
surface, a throttle valve in said throttle passage, an intake
manifold including a crankcase cover mounting surface mating with
said intake manifold mounting surface, a plenum mounting surface
opposed to said crankcase cover mounting surface, and a like
plurality of inlet passages respectively communicating between said
plenum mounting surface and said inlet openings of said crankcase
cover, and a plenum member which is mounted on said plenum mounting
surfaces of said throttle housing and said intake manifold, which
is separable from both said intake manifold and said throttle
housing and which defines a like plurality of intake passages
having respective outlet ends communicating respectively with said
inlet passages of said intake manifold and having respective inlet
ends communicating with said throttle passage such that the intake
of said engine can be tuned solely by modifying the configuration
of said plenum member.
Description
BACKGROUND OF THE INVENTION
The invention relates to internal combustion engines, and more
particularly to intake systems for two-stroke engines. Still more
particularly, the invention relates to air intake systems for
two-stroke engines in which fuel is injected directly into the
cylinders.
SUMMARY OF THE INVENTION
The invention provides a two-stroke internal combustion engine
comprising a cylinder block including a generally planar crankcase
mounting surface having therein a crankcase recess, a crankcase
cover including a generally planar cylinder block mounting surface
mating with the crankcase mounting surface and having therein a
crankcase recess aligned with the crankcase recess in the cylinder
block and defining therewith a crankcase, and air intake means for
supplying a flow of air to the crankcase, the air intake means
defining a U-shaped air intake path having a downstream leg
directed toward and generally perpendicular to the crankcase
mounting surface and having an upstream leg generally parallel to
and directed opposite the downstream leg.
The invention also provides a two-stroke internal combustion engine
comprising engine block means defining a crankcase and including an
intake manifold mounting surface having therein an inlet opening
communicating with the crankcase, an intake manifold having a
crankcase cover mounting surface mating with the intake manifold
mounting surface, a plenum mounting surface opposed to the
crankcase cover mounting surface, and an intake passage extending
from the plenum mounting surface to the crankcase cover mounting
surface, and a plenum cover including an inner surface mating with
the plenum mounting surface, the plenum cover cooperating with the
intake manifold to define, between the plenum cover and the intake
manifold, an intake runner passage communicating with the intake
passage and extending laterally from the intake passage.
The invention also provides a two-stroke internal combustion engine
comprising a cylinder block including a generally planar crankcase
mounting surface having therein a crankcase recess, a crankcase
cover including a generally planar cylinder block mounting surface
mating with the crankcase mounting surface and having therein a
crankcase recess aligned with the crankcase recess in the cylinder
block to define a crankcase, air intake means for supplying air to
the crankcase, the intake means including a wall partially defining
an air passageway communicating with the crankcase, the wall having
therein an opening communicating with the passageway, and an
electronic control unit mounted on the wall and overlying the
opening.
The invention also provides a two-stroke internal combustion engine
comprising an engine block means defining a crankcase and including
an intake manifold mounting surface having therein an inlet opening
communicating with the crankcase, an intake manifold including a
crankcase cover mounting surface mating with the intake manifold
mounting surface, a plenum mounting surface opposed to the
crankcase cover mounting surface, an intake passage extending from
the plenum mounting surface to the crankcase cover mounting surface
and communicating with the inlet opening, and a throttle passage
extending from the plenum mounting surface and parallel to the
intake passage, the throttle passage being laterally offset from
the intake manifold mounting surface, and means for conducting air
from the throttle passage to the intake passage.
The invention also provides an outboard motor having forward and
rearward ends and comprising a propulsion unit adapted to be
mounted on the transom of a boat, the propulsion unit including a
propeller shaft with a rearward end adapted to have mounted thereon
a propeller, and the propulsion unit also including a two-stroke
internal combustion engine drivingly connected to the propeller
shaft, the engine including engine block means defining a crankcase
and air intake means for supplying air to the crankcase, the air
intake means defining a U-shaped air intake path having a
rearwardly directed downstream leg and having a forwardly directed
upstream leg generally parallel to the downstream leg.
The invention also provides a two-stroke internal combustion engine
comprising engine block means defining a plurality of crankcases
and including a mounting surface having therein a plurality of
inlet openings each communicating with a respective one of the
crankcases, a throttle housing defining a throttle passage and
including a plenum mounting surface, a throttle valve in the
throttle passage, and a plenum member which is separable from both
the engine block means and the throttle housing and which defines a
plurality of intake passages each having an outlet end
communicating with a respective one of the inlet openings and each
having an inlet end communicating with the throttle passage such
that the intake of the engine can be tuned solely by modifying the
configuration of the plenum member.
One of the features of the invention is the provision of an
outboard motor including a two-stroke engine having relatively few
parts. This simplifies the manufacture and assembly of the engine.
The engine also has a tuned air intake and is configured to fit
within existing outboard motor cowlings.
Another feature of the invention is the provision of a two-stroke
engine having an air intake that can be tuned for optimum
performance over a range of engine speeds. The range of engine
speeds for which the engine is tuned can be easily changed by
modifying the configuration of a single engine component.
Another feature of the invention is the provision of a two-stroke
engine having an air intake and an electronic control unit that is
supported by the air intake. The electronic control unit is cooled
by air flowing through the air intake. The provision of an
air-cooled electronic control unit eliminates the need for a water
jacket for cooling the electronic control unit.
Other features and advantages of the invention will become apparent
to those skilled in the art upon review of the following detailed
description, claims and drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a left side elevational view of an outboard motor
embodying the invention.
FIG. 2 is a top view of the engine that is illustrated by FIG. 1
and that is a first alternative embodiment of the invention.
FIG. 3 is an enlarged right side elevational view of a portion of
the engine shown in FIG. 1.
FIG. 4 is a cross-sectional view taken along line 4--4 in FIG.
3.
FIG. 5 is an exploded top view of the engine shown in FIG. 2.
FIG. 6 is a cross-sectional view taken along line 6--6 in FIG.
2.
FIG. 7 is a partial cross-sectional view of the engine taken along
line 7--7 in FIG. 4.
FIG. 8 is a view taken along line 8--8 in FIG. 5.
FIG. 9 is a view taken along line 9=9 in FIG. 5.
FIG. 10 is a view taken along line 10--10 in FIG. 5.
FIG. 11 is a view taken along line 11--11 in FIG. 5.
FIG. 12 is a view taken along line 12--12 in FIG. 5.
FIG. 13 is a view taken along line 13--13 in FIG. 5.
FIG. 14 is an exploded, perspective view of a portion of the engine
shown in FIG. 2.
FIG. 15 is a view similar to FIG. 2 illustrating an engine that is
an alternative embodiment of the invention.
FIG. 16 is a view similar to FIG. 3 illustrating the engine shown
in FIG. 15.
FIG. 17 is a view similar to FIG. 8 illustrating a portion of the
engine shown in FIG. 15.
Before one embodiment of the invention is explained in detail, it
is to be understood that the invention is not limited in its
application to the details of the construction and the arrangements
of components set forth in the following description or illustrated
in the drawings. The invention is capable of other embodiments and
of being practiced or being carried out in various ways. Also, it
is to be understood that the phraseology and terminology used
herein is for the purpose of description and should not be regarded
as limiting.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An outboard motor 10 that is a first embodiment of the invention is
illustrated in FIGS. 1-14. As shown in FIG. 1, the outboard motor
10 includes a propulsion unit 14 mounted on the transom 16 of a
boat 18 for pivotal movement relative thereto about a generally
horizontal tilt axis 22 and about a generally vertical steering
axis 26. The propulsion unit 14 includes a propeller shaft 30
having a rearward end 34 having mounted thereon a propeller 38, and
an internal combustion engine 42 drivingly connected to the
propeller shaft 30 via a conventional drive train 46.
The internal combustion engine 42 is preferably a two-stroke, V-6
engine. The engine 42 comprises (FIGS. 2 and 5) a V-type cylinder
block 50 having forward and rearward ends 54, 58. The rearward end
58 includes first and second or port and starboard cylinder banks
62, 66 having respective port and starboard cylinder head mounting
surfaces 70, 74. Each cylinder bank 62, 66 includes (FIG. 4) three
vertically aligned cylinders 78 (only one of which is shown). The
forward end 54 of the cylinder block 50 defines (FIGS. 5 and 12) a
forwardly facing, generally planar crankcase mounting surface 82
having therein (FIG. 12) six crankcase recesses 86. Each of the
crankcase recesses 86 communicates with a respective one of the
cylinders 78 via (FIG. 4) one or more transfer passages 90, as is
known in the art. Such a cylinder block construction is
conventional and will not be described in greater detail.
The engine 42 also comprises six pistons 94 (only one shown in FIG.
4) slidably housed in respective cylinders 78, three of the pistons
94 being housed by cylinders 78 in the starboard cylinder bank 66
and three pistons 94 being housed in the port cylinder bank 62.
The engine 42 also comprises (FIGS. 2 and 5) first and second or
port and starboard cylinder heads 98, 102 respectively mounted on
the port and starboard cylinder head mounting surfaces 70, 74 of
the cylinder block 50. The starboard cylinder head 102 closes the
three starboard cylinders 78 and thus cooperates with the cylinder
block 50 and with the pistons 94 housed in the starboard cylinders
78 to define (FIG. 4) three combustion chambers 106 (only one
shown). Similarly, though not shown in the drawings, the port
cylinder head 98 closes the port cylinders 78 and thus cooperates
with the cylinder block 50 and with the pistons 94 housed in the
port cylinders 78 to define three combustion chambers 106. Each
combustion chamber 106 communicates with a respective one of the
crankcase recesses 86 in the forward end 54 of the cylinder block
50 via a respective one of the transfer passages 90.
The engine 42 also comprises (FIGS. 2 and 5) means 110 for
injecting fuel directly into each of the combustion chambers 106
during engine operation. While various suitable direct fuel
injecting means 110 can be employed, in the illustrated embodiment,
the engine 42 includes three fuel injectors 114 which are supported
by the port cylinder head 98 (one shown in FIGS. 2 and 5), and
three fuel injectors 114 which are supported by the starboard
cylinder head 102 (one shown in FIGS. 2 and 5). Each fuel injector
114 is operable for injecting fuel directly into a respective one
of the combustion chambers 106 (shown in FIG. 4). Suitable means
(not shown) are provided for supplying fuel under pressure to the
fuel injectors 114.
The engine 42 also comprises (FIGS. 2, 5, 6, 10 and 13) a crankcase
cover 118 mounted on the forward end 54 of the cylinder block 50.
The crankcase cover 118 includes (FIGS. 4, 5 and 13) a rearwardly
facing, generally planar cylinder block mounting surface 122 mating
with the crankcase mounting surface 82 so that the cylinder block
mounting surface 122 and the crankcase mounting surface 82 lie in a
substantially vertical plane. The cylinder block mounting surface
122 has therein (FIGS. 6 and 13) six rearwardly opening crankcase
recesses 126. Each of the crankcase recesses 126 aligns with a
respective one of the crankcase recesses 86 in the cylinder block
50 to define therewith a crankcase 130 (FIGS. 4 and 6).
The crankcase cover 118 also includes (FIGS. 5, 6 and 10) a
generally planar intake manifold mounting surface 134 facing
forwardly or opposite the cylinder block mounting surface 122. The
intake manifold mounting surface 134 has therein (see FIG. 10) six
vertically aligned crankcase inlet openings 138. In other words,
all of the inlet openings 138 are in-line, i.e., are centered on a
single vertical line 140 (FIG. 10). As shown in FIG. 6, each of the
crankcase inlet openings 138 communicates with a respective
crankcase 130 by means of a crankcase cover passage portion 142
extending between the crankcase inlet opening 138 and a respective
crankcase recess 126 in the crankcase cover 118. Any suitable means
(not shown) can be employed for securing the crankcase cover 118 to
the cylinder block 50.
The engine 42 also comprises (FIGS. 4 and 6) a crankshaft 150
supported by the cylinder block 50 and the crankcase cover 118 for
rotation about a vertical axis lying the in the plane defined by
the crankcase mounting surface 82 and cylinder block mounting
surface 122. As is known in the art, the crankshaft 150 includes
(see FIG. 6) disc-like portions 154 separating the adjacent
crankcases 130. As is known in the art, the crankshaft 150 is
connected to each of the pistons 94 by a respective piston rod 162
(one shown in FIG. 4).
It should be understood that the cylinder block 50 and the
crankcase cover 118 can be considered to be a single engine block
means supporting the crankshaft 150 and defining the crankcases
130.
The engine 42 also comprises air intake means 170 for supplying air
to each of the crankcases 130. While various suitable constructions
for the air intake means 170 can be used, in the illustrated
embodiment, the air intake means 170 defines (see FIG. 4) a
U-shaped air intake path 174 having a downstream leg 178 directed
rearwardly or toward and generally perpendicular to the crankcase
mounting surface 82 and an upstream leg 182 extending generally
parallel to and directed forwardly or opposite the downstream leg
178.
More particularly, and as shown in FIGS. 4, 5, 8 and 11, the air
intake means 170 includes an intake manifold 190 mounted on the
forward end of the crankcase cover 118. The intake manifold 190
includes integrally cast port and starboard portions 194, 198. The
port and starboard portions 194, 198 both include (FIG. 8) a
forwardly facing, generally planar plenum mounting surface 202. The
plenum mounting surface 202 has therein a series of six in-line,
vertically aligned intake manifold inlets 206 located in the
forward face of the port portion 194.
The port portion 194 also includes (FIGS. 5 and 11) a rearwardly
facing, generally planar crankcase cover mounting surface 210 that
mates with the intake manifold mounting surface 134. The crankcase
cover mounting surface 210 extends generally parallel to the plenum
mounting surface 202 and has therein a series of six in-line,
vertically aligned intake manifold outlets 214. As shown in FIGS. 6
and 7, each of the intake manifold outlets 214 aligns and
communicates with a respective one of the inlet openings 138 in the
crankcase cover 118. As shown in FIGS. 4 and 6, an intake passage
218 extends between each of the intake manifold inlets and outlets
206, 214.
The air intake means 170 also includes (FIG. 6) six reed boxes 222
supported by the intake manifold 190 in the intake passages 218. As
shown in FIG. 4, each reed box 222 is fixed to the port portion 194
of the air intake manifold 190 and (FIGS. 6 and 7) extends
rearwardly from a respective intake manifold outlet 214 through a
crankcase cover inlet opening 138 and into an associated crankcase
passage portion 142. The reed boxes 222 operate conventionally to
afford passage of intake air into the crankcases 130 from the
intake manifold 190 and to prevent air flow out of the crankcases
130.
The starboard portion 198 of the intake manifold 190 includes
(FIGS. 5, 8 and 11) a generally vertically extending wall or web
230. The starboard portion 198 also includes (FIGS. 4 and 11) a
generally tubular throttle housing 234 extending rearwardly from
the web 230. As best shown in FIG. 4, the throttle housing 234 is
laterally offset (toward starboard) from the intake manifold
mounting surface 134 of the crankcase cover 118. The throttle
housing 234 partially defines a throttle passage 238 extending
through the web 230 between a rearwardly opening inlet end 242 and
a forwardly opening outlet end 246 adjacent the plenum mounting
surface 202. A throttle plate 250 (FIGS. 3 and 4) is supported
within the throttle passage 238 for pivotal movement about a
generally horizontal axis. The starboard portion 198 of the intake
manifold 190 also includes (FIGS. 8 and 11) an idle air passage 254
adjacent the throttle housing 234. The idle air passage 254 extends
through the starboard portion web 230 to afford air flow into the
engine 42 when the throttle passage 238 is closed by the throttle
plate 250 during engine idling.
As shown in FIG. 2, the intake manifold 190 has an upper surface
258 extending laterally across the starboard and port portions 198,
194. For reasons discussed below, the upper surface 258 has thereon
(FIGS. 8 and 11) adjacent its most starboard end an alternator
mounting boss 262. Located toward port from the alternator mounting
boss 262 is a pair of spaced-apart electronic control unit mounting
bosses 266.
The starboard portion 198 of the intake manifold 190 also includes
(FIGS. 8 and 11) a lower portion 270 having extending vertically
downwardly therefrom a throttle cable mount 274. For reasons
discussed below, the throttle cable mount 274 has therethrough a
pair of bolt holes 278.
The air intake means 170 also includes (FIGS. 2-6 and 9) a plenum
cover 282 mounted on the intake manifold 190. The plenum cover 282
is preferably made of plastic and includes (FIG. 9) a rearwardly
facing intake manifold mounting surface 286 mating with the plenum
mounting surface 202 of the intake manifold 190. As best shown in
FIG. 4, the plenum cover 282 cooperates with the intake manifold
190 to define therebetween a common intake chamber 290 located
forwardly of the starboard portion 198 of the intake manifold 190.
The intake chamber 290 extends substantially the entire vertical
extent of the plenum cover 282 and communicates with the outlet end
246 of the throttle passage 238 and with the idle air passage
254.
As best shown in FIGS. 6 and 9, the plenum cover 282 also
cooperates with the intake manifold 190 to define six intake runner
passages 294 located forwardly of the port portion 194 of the
intake manifold 190. More particularly, the plenum cover 282
includes six pairs of vertically spaced-apart, opposed walls 298
that extend generally rearwardly from the forward end of the plenum
cover 282. Each pair of walls 298 defines therebetween a respective
runner passage 294 such that the runner passage 294 extends
laterally and generally horizontally between the intake chamber 290
and a respective one of the intake manifold inlets 206. Preferably,
the runner passages 294 are substantially equal in height and
length, and extend uniformly between the intake chamber 290 and the
intake manifold inlets 206.
As best shown in FIGS. 6 and 14, the uppermost of the walls 298
defines a top wall 302 that extends horizontally and is
substantially flush to the respective upper surfaces of the intake
manifold 190 and the crankcase cover 118. For reasons discussed
below, the top wall 302 has therein (see FIG. 14) an opening 306
communicating with the intake chamber 290 and with the uppermost
runner passage 294.
As mentioned above, and as best shown in FIG. 4, the air intake
means 170, including the plenum cover 282 and intake manifold 190,
provides a U-shaped path 174 for providing a flow of intake air to
the crankcases 130. More particularly, air flowing into the engine
42 flows forwardly through the throttle and idle air passages 238,
254, forwardly and through the intake chamber 290, rearwardly and
through the runner passages 294, and rearwardly through the intake
passages 218 and the reed boxes 222. Air flowing rearwardly through
the reed boxes 222 passes into the associated crankcase passages
142, and into the crankcases 130. From the crankcases 130, air
flows through the transfer passages 90 to the combustion chambers
106. As shown in FIG. 4, at least one of the runner passages 294
lies in a horizontal plane including the throttle passage 254 such
that the U-shaped path 174 lies in a horizontal plane. Also, each
of the runner passages 294 extends horizontally from the common
intake chamber 290 which is part of the upstream leg 182 of the air
flow path 174. Accordingly, each of the runner passages 294 defines
a horizontal plane in which portions of the upstream and downstream
legs 182, 178 lie.
The air intake means 170 can be tuned to optimize the rate of mass
air flow to the crankcases 130 for a particular range of engine
speeds. Because the runner passages 294 and intake chamber 290 have
respective configurations defined in part by the inner surface of
the plenum cover 282, which is preferably made of plastic, the
configuration of the runner passages 294 and the intake chamber 290
can be readily modified to tune the air intake means for various
ranges of engine speeds by modifying a single component of the
engine, i.e. by modifying the configuration of the plenum cover
282.
The engine 42 also comprises (FIG. 14) an electronic control unit
310 mounted on the top wall 302 of the plenum cover 282 and on the
upper surface 258 of the intake manifold 190 in a position
overlying and closing the opening 306 in the top wall 302 of the
plenum cover 282. The electronic control unit 310 is fastened to
the electronic control unit mounting bosses 266 and to a mounting
boss 311 (FIG. 14) in the top wall 302 of the plenum cover 282. In
order to protect the electronic control unit 310 from heat
developed primarily by the electronic control unit 310 itself, the
engine 42 also includes means 312 for cooling the electronic
control unit 310. While various suitable constructions for the
cooling means 312 can be used, in the illustrated embodiment, the
cooling means 312 includes, on the electronic control unit 310, a
plurality of cooling fins 313 extending through the opening 306 in
the top wall 302 and into the intake chamber 290 and the uppermost
runner passage 294. Intake air flowing into the intake chamber 290
passes the cooling fins 313 and acts as a heat sink. For reasons
discussed below, the electronic control unit 310 also includes
(FIGS. 2 and 3) a vertically extending timing pointer mount 314
located adjacent the interface of the plenum cover 282 and the
intake manifold 190. While not shown, the timing pointer mount 314
has therethrough a laterally extending slot adapted to receive a
timing pointer mounting bolt 315 (FIG. 3).
The engine 42 also comprises (FIG. 3) means 316 supported by the
intake manifold 190 for controlling air flow to the engine 42 in
response to operator input. While various suitable air flow
controlling means 316 can be employed, in the illustrated
embodiment, such means includes the above-described throttle plate
250, and a throttle linkage 318 supported by the intake manifold
190 and operably connected to the throttle plate 250. A suitable
arrangement for the throttle linkage 318 is described in greater
detail in the above-mentioned U.S. Ser. No. 07/954,492, which was
filed Sep. 30, 1992, which is assigned to the assignee hereof, and
which is incorporated herein by reference. A throttle control cable
322 for transmitting operator input is operably connected to the
throttle linkage 318 and is supported by a throttle and shift cable
mounting assembly 326 fixed by bolts (not shown) extending through
the holes 278 in the throttle cable mount 274. A suitable throttle
and shift cable mounting assembly 326 is described in greater
detail in U.S. Pat. No. 5,080,618 which issued Jan. 14, 1992 and
which is incorporated herein by reference.
The engine 42 further comprises (FIG. 3) a timing pointer 330 fixed
by the timing pointer mounting bolt 315 along the slot in the
timing pointer mount 314. The timing pointer 330 is thus indirectly
supported by the plenum cover 282 and by the intake manifold 190.
The engine also comprises a flywheel 334, and the timing pointer
330 is used in conjunction with markings on the flywheel 334 to
determine the spark timing of the engine 42.
The engine 42 further comprises an alternator 338 (shown in FIG. 3
and in phantom in FIG. 2) mounted on the intake manifold 190 and on
the cylinder block 50. The alternator 338 is mounted, in part, on
the alternator mounting boss 262 and on a clevis-like fixture 342
(FIG. 3) bolted to the forward end 54 of the cylinder block 50.
When so mounted, the alternator 338 extends generally vertically
and is located above the throttle housing 234 and starboard of the
crankcase cover 118.
One of the advantages of the engine 42 is that it includes
relatively few components, thereby simplifying its manufacture and
assembly. The engine 42 is further simplified by the mounting of
several engine components both directly and indirectly on a single
supporting component, i.e., the intake manifold 190, which also
reduces the number of engine parts that are required.
Another advantage of the engine 42 is that the air intake provides
an air intake flow path that, by virtue of its relatively smooth
and simple configuration, provides increased efficiency in
supplying air to the crankcases 130. In addition, the air intake of
the engine 42 can be easily tuned for a variety of engine speeds
yet can also be sized to fit within the envelope dictated by
conventional engine cowls.
Another advantage of the engine 42 is the provision of an
air-cooled electronic control unit 312 mounted on the air intake
manifold 190. The provision of an air-cooled electronic control
unit eliminates the need for a water jacket surrounding and cooling
the electronic control unit, and eliminates the need for a coolant
line connected to such a water jacket.
FIGS. 15-17 illustrate an engine 542 that is an alternative
embodiment of the invention. The engine 542 is identical in
construction to the engine 42 except for the below described
differences. Accordingly, common reference numerals are used to
identify features that are common to the engines 42 and 542.
The engine 542 includes a cylinder block 50 and a crankcase cover
118 fixed to the cylinder block 50. The cylinder block 50 and the
crankcase cover 118 define therebetween a plurality of crankcases
and support a crankshaft (the crankcases and crankshaft are not
shown in FIGS. 15-17). The engine 542 also includes an intake
manifold 590 that is mounted on the forward end of the crankcase
cover 118. The intake manifold 590 includes integrally cast port
and starboard portions 594, 598 and (see FIG. 17) a plurality of
intake manifold inlets 606 located in the port portion 594.
The engine 542 also includes (see FIGS. 15 and 16) a plenum cover
682 mounted on the forward end of the intake manifold 590. The
plenum cover 682 is made of plastic and provides an inner surface
that cooperates with the intake manifold 590 to define therebetween
a common intake chamber (not shown) located forwardly of the intake
manifold 590 and a plurality of intake runner passages 694 that
each extend from the common intake chamber and a respective one of
the intake manifold inlets 606. As best shown in FIGS. 15 and 16,
and unlike the top wall 302 of the plenum cover 282, the uppermost
or top wall 702 of the plenum cover 682 provides an imperforate
surface, i.e. the wall 702 does not have therein any openings or
other means providing access to the interior of the plenum cover
682.
The engine 542 also includes (FIGS. 15 and 17) an electronic
control unit 710 mounted on the port portion 594 of the intake
manifold 590. More particularly, and as best shown in FIG. 17, the
port portion 594 of the intake manifold 590 includes a mounting
boss 714 that faces laterally outwardly. The electronic control
unit 710 includes (see FIG. 15) a base 718 that is fixed to the
mounting boss 714 by a bolt 722. The base 718 provides means 726
for cooling the electronic control unit 710. While various suitable
cooling means 726 could be employed, in the illustrated embodiment,
the cooling means 726 includes a water jacket 730 (shown
schematically in FIG. 15) located within the base 718. The cooling
means 726 also includes a pair of water hoses 734 (only one shown
in FIG. 15) that are connected to a suitable source of coolant (not
shown), such as a water jacket in the cylinder block, and that
provide a flow of coolant to and from the water jacket 730.
The engine 542 also includes (See FIG. 16) a timing pointer 750
that is mounted directly on the intake manifold 590. In particular,
and as illustrated in FIG. 16, the intake manifold 590 provides a
timing pointer mount 758 extending upwardly from the upper portion
of the intake manifold 590. The timing pointer 750 is fixed to the
timing pointer mount 758 by suitable means such as a bolt 762.
Like the engine 42, the engine 542 also includes an alternator 638,
a throttle linkage 318 and a throttle and shift cable mounting
assembly 326, each of which is mounted on the intake manifold 590.
While the engines 42 and 542 include respective intake manifolds
190 and 590 respectively supporting various specifically disclosed
engine components, it should be readily understood that the intake
manifolds 190 and 590 can be readily modified support additional
various engine components. For example, the intake manifolds. 190
and 590 can be readily modified by providing appropriately located
mounting bosses in a variety of positions, including on the lower
portions of the intake manifolds 190 and 590, to provide support
for fuel pumps and fuel flow regulators.
Various features of the invention are set forth in the following
claims.
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