Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02352848 2003-11-03
WH-11 267CA
TITLE: TWO-CYCLE INTERNAL COMBUSTION ENGINE
FIELD OF THE INVENTION
The present invention relates to an improvement of
the injection direction of an air-fuel mixture into a
cylinder of a two-cycle internal combustion engine which
is configured to prevent blow-by of the air-fuel mixture
in a combustion engine and hence to enhance a fuel
consumption and an exhaust gas purifying performance.
BACKGROUND OF THE INVENTION
In conventional two-cycle internal combustion
engines, the supply of an air-fuel mixture has been
performed by mixing fuel supplied from a carburetor or
the like with intake air, and sucking the air-fuel
mixture in a crank chamber and then supplying the air-
fuel mixture in a combustion chamber via scavenging
openings. The supply of an air-fuel mixture in the
conventional engine, however, has a problem that since
the opening timing of an exhaust opening is set to be
earlier than the opening timing of the scavenging
openings, there may often occur a so-called blow-by
phenomenon in which the air-fuel mixture supplied in the
combustion chamber is discharged in the exhaust passage.
To solve the above problem, the present applicant
has disclosed a two-cycle internal combustion engine in
Japanese Patent Laid-open No. Hei 10-325323. FIG. 14 is
a longitudinal sectional view of the internal combustion
engine disclosed in the above document, and FIG. 15 is a
horizontal sectional view taken on a plane passing
through of a rotary valve shown in FIG. 14. In these
figures, an exhaust passage 017, which has an exhaust
- 1 -
CA 02352848 2003-11-03
WH-11 267CA
opening 018 on one side in the peripheral direction of a
cylinder 005, is provided in a cylinder block 003. A
chamber portion 021 is provided in the cylinder block 003
in such a manner as to be located on the side far from
the exhaust passage 017. Two kinds of communication
passages for communicating an upper portion of the
cylinder 005 to the chamber portion 021 are provided in
the cylinder block 003. The two kinds of communication
passages are two first communication passages 030 for
allowing a high compression gas to flow from a combustion
chamber 019 to the chamber portion 021, and one second
communication passage 031 for allowing an air-fuel
mixture to flow from the chamber portion 021 to the
combustion chamber 019. A cylinder side opening 034 of
the second communication passage 031 is located at a
position opposite to that of the exhaust opening 018 with
respect to the center line of the cylinder 005.
Two pairs of right and left scavenging passages
013 for supplying air are provided. Each pair of the
scavenging passages 013 have openings at positions being
laterally symmetric with respect to the plane containing
the exhaust opening 018 and the center line of the
cylinder 005. A scavenging passage 015 for supplying air
is also provided. The scavenging passage 015 has an
opening 016 at a position opposite to that of the exhaust
opening 018 formed in the cylinder 005. Schnurle
scavenging (reverse scavenging) is performed by air blown
from these scavenging openings.
A rotary valve 042 is provided in such a manner
as to cross mid portions of the communication passages
030 and 031. A control valve is provided around the
rotary valve 042. The control valve is composed of two
first control valves 056 provided in the first
- 2 -
CA 02352848 2003-11-03
WH-11 267CA
communication passages 030 and one second control valve
057 provided in the second communication passage 031.
The first control valves 056 are operative for opening
the first communication passages 030 nearly at a point of
time when the exhaust opening is closed and close the
first communication passages 030 at a mid point in the
compression stroke. The second control valve 057 is
operative for opening the second control valve 031 nearly
at a point of time when the scavenging openings are
closed and closes the second communication passage 031 at
a mid point before the first communication passages 030
are closed in the compression stroke.
Right and left fuel injectors 048 are laterally
symmetrically mounted on both sides of the cylinder block
003. Immediately before the second control valve 057
opens the second communication passage 031, fuel injected
from the fuel injectors 048 is blown obliquely from below
in an air-fuel mixture forming space facing to the cutout
functioning as the second control valve 057. To be more
specific, fuel injected from the right fuel injector 048
is blown obliquely leftwardly toward an approximately
central portion of the second communication passage 031,
and similarly, the fuel injected from the left fuel
injector 048 is blown obliquely rightwardly toward the
approximately central portion of the second communication
passage 031 (see FIG. 15).
When the second control valve 057 opens the
second communication passage 031 along with the rotation
of the rotary valve 042, a high compression gas charged
in the chamber portion 021 flows in the second
communication passage 031 from the chamber portion side
opening of the second communication passage 031, to be
mixed with standby fuel, and the air-fuel mixture thus
- 3 -
CA 02352848 2003-11-03
WH-11 267CA
formed is press-fed by a high pressure in the chamber
portion 021, to be injected in the combustion chamber 019
from the cylinder side opening 034 of the second
communication passage 031.
In the internal combustion engine of this type,
as shown by arrows in FIGS. 14 and 15, a rich air-fuel
mixture 060 is injected toward an ignition plug 020
mounted to an upper portion of the combustion chamber 019
while being in parallel to a vertical plane containing
the cylinder side opening 034 of the second communication
passage, the center line of the cylinder, and the exhaust
opening 018. Of the mist of the rich air-fuel mixture
depicted by the arrows 060, a portion of the mist
depicted by the solid arrows, whose forward traveling
force given by injection is large, travels along
approximately straight lines, and a portion of the mist
depicted by the broken lines, whose forward traveling
force given by injection is weakened, travels along
curved lines. The mist of the fuel directed upwardly is
reversed in the vicinity of the semi-spherical ceiling of
the combustion chamber and is directed downwardly, to
form longitudinal eddies in the combustion chamber in
cooperation with existent scavenging eddies 061. The
scavenging eddies 061 are longitudinal eddies generated
as follows: namely, air flows of schniirle scavenging
(reverse scavenging) performed by scavenging air supplied
from the scavenging passages 013 and 015 and an exhaust
gas discharged from the exhaust passage 017 form swirl
flows within a vertical plane containing the exhaust
opening 018 and the center line of the cylinder.
In the internal combustion engine of this type,
scavenging only by air is performed in the initial state
of scavenging, and fuel (rich air-fuel mixture) injected
- 4 -
CA 02352848 2003-11-03
WH-11 267CA
to the combustion chamber as described above flows in the
combustion chamber which has been sufficiently scavenged
with the above-described air, to be mixed with air in the
combustion chamber. The air-fuel mixture thus adjusted
at a suitable air-fuel ratio is then burned in the
combustion chamber.
In the above-described prior art internal
combustion engine, the mist of fuel is injected toward
the ignition plug 020 within the vertical plane
containing the exhaust opening 018 and the center line of
the cylinder 005, and the mist of fuel forms longitudinal
eddies in cooperation with the existent scavenging eddies
in the combustion chamber 019. The eddy currents within
the vertical plane are kept until the eddies are
destroyed to be finely dispersed at the final stage in
the compression stroke.
It is required to sufficiently uniformly and
speedily mix intake air by scavenging with a large amount
of a rich air-fuel mixture over the entire region of the
inside of the combustion chamber, particularly, at the
time of full load operation; however, since the above-
described longitudinal eddies are not destroyed until the
final stage in the compression stroke, the mixture in the
combustion chamber tends to become insufficient.
Further, at the time of full load operation,
since a rich air-fuel mixture is blown toward the
ignition plug, the ignition plug is liable to be fogged
with the rich air-fuel mixture, with a result that it
becomes difficult to realize desirable combustion.
_ 5 _
CA 02352848 2003-11-03
WH-11 267CA
SUMMARY OF THE INVENTION
An object of the present invention is to solve the
problems of the above-described prior art internal
combustion engine, and to provide a two-cycle internal
combustion engine capable of sufficiently, speedily
mixing intake air (air) with a rich air-fuel mixture
before a piston is moved up, and preventing an ignition
plug from being fogged with a rich air-fuel mixture.
To solve the above-described problems, according
to the present invention, there is provided a two-cycle
internal combustion engine including: a cylinder; an
exhaust opening provided in a portion, on one side in the
peripheral direction, of the cylinder; a plurality of
scavenging openings for performing schnurle scavenging,
the scavenging openings being located at positions which
are laterally symmetric with respect to a cylinder
symmetric plane containing the exhaust opening and the
center line of the cylinder while excluding the position
of the exhaust opening; a chamber portion adjacent to the
cylinder; a communication passage for communicating the
cylinder to the chamber portion, the communication
passage having a cylinder side opening located opposite
to the exhaust opening with respect to the center line of
the cylinder; and a control valve for openably/closably
controlling the communication passage so as to blow a
rich air-fuel mixture into a combustion chamber from the
cylinder side opening of the communication passage by a
high compression gas stored in the chamber portion. The
above two-cycle internal combustion engine is
characterized as follows:
(1) Side walls of a cylinder side passage portion
of the communication passage are tilted with respect to
the cylinder symmetric plane (containing the exhaust
- 6 -
CA 02352848 2003-11-03
WH-11 267CA
opening and the center line of the cylinder) in order to
deflect mist of the rich air-fuel mixture at least on
either the right side or the left side with respect to
the cylinder symmetric plane. With this configuration,
since the flow of mist of the deflected rich air-fuel
mixture obliquely crosses the scavenging eddies, it is
possible to destroy the scavenging eddies and hence to
accelerate the mixture of the rich air-fuel mixture with
air.
(2) In the two-cycle internal combustion engine
described in the item (1), one or a plurality of guide
vanes for assisting deflection of the flow of the rich
air-fuel mixture are provided in the cylinder side
passage portion of the communication passage. With this
configuration, it is possible to positively deflect the
rich air-fuel mixture.
(3) In the two-cycle internal combustion engine
described in the item (1), wherein a wedge-shaped
partitioning member for branching the flow of mist of the
rich air-fuel mixture and side walls of each of the
branched passages thus formed are tilted with respect to
the cylinder symmetric plane in order to deflect the flow
of mist of the rich air-fuel mixture on both sides of the
cylinder symmetric plane. With this configuration, since
the flow of the rich air-fuel mixture destroys the
scavenging eddies from the right and left sides, it is
possible to positively destroy the scavenging eddies.
(4) In the two-cycle internal combustion engine
described in the item (1), a wedge-shaped partitioning
member for branching the flow of mist of the rich air-
fuel mixture is provided in the cylinder side passage
portion of the communication passage while being offset
-
CA 02352848 2003-11-03
WH-11 267CA
to either the right side or the left side and side walls
of each of the branched passages thus formed are tilted
with respect to the cylinder symmetric plane, in order to
deflect the flow of mist of the rich air-fuel mixture on
both sides of the cylinder symmetric plane with flow
quantities of the branched flows of the rich air-fuel
mixture being made different from each other. With this
configuration, it is possible to obtain the same effect
as that described in the item (3).
(5) In the two-cycle internal combustion engine
described in the item (1), side walls of a passage formed
in the control valve are tilted in such a direction as to
assist the deflection of the injecting direction of the
rich air-fuel mixture. With this configuration, it is
possible to prevent an ignition plug from being fogged
with the rich air-fuel mixture.
(6) In the two-cycle internal combustion engine
described in the item (1), a wall of the cylinder side
passage portion of the communication passage is tilted so
as to ensure the height of the injecting direction of the
rich air-fuel mixture allowing the injected rich air-fuel
mixture to be directed to a connecting portion between
the cylinder and the cylinder head. With this
configuration, it is possible to prevent the ignition
plug from being fogged with the rich air-fuel mixture and
to prevent the inner wall of the cylinder from being
excessively made wet with the rich air-fuel mixture.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown
in the drawings, wherein:
FIG. 1 is a longitudinal sectional view of a
g _
CA 02352848 2003-11-03
WH-11 267CA
first embodiment of a two-cycle internal combustion
engine according to the present invention.
FIG. 2 is an enlarged longitudinal sectional view
of an essential portion of the first embodiment.
FIG. 3 is an enlarged horizontal sectional view
of an essential portion of the first embodiment.
FIGS. 4(a) to 4(c) are views illustrating the
flow of gas in a combustion chamber of the first
embodiment.
FIG. 5 is a diagram illustrating an operational
cycle of the first embodiment.
FIG. 6 is a horizontal sectional view of an
essential portion of a second embodiment of the two-cycle
internal combustion engine according to the present
invention.
FIG. 7 is a horizontal sectional view of an
essential portion of a third embodiment of the two-cycle
internal combustion engine according to the present
invention.
FIG. 8 is a horizontal sectional view of an
essential portion of a fourth embodiment of the two-cycle
internal combustion engine according to the present
invention.
FIG. 9 is a horizontal sectional view of an
essential portion of a fifth embodiment of the two-cycle
internal combustion engine according to the present
invention.
FIG. 10 is a longitudinal sectional view of a
two-cycle internal combustion engine according to a sixth
embodiment of the present invention.
FIG. 11 is a horizontal sectional view of the
internal combustion engine shown in FIG. 10.
FIGS. 12(a) and 12(b) are sectional views of a
rotary valve used in the internal combustion engine shown
in FIG. 10, wherein FIG. 12(a) is a longitudinal
_ g
CA 02352848 2003-11-03
WH-11 267CA
sectional view of the rotary valve, and FIG. 12(b) is a
sectional view taken on line B-B of FIG. 12(a).
FIG. 13 is a diagram illustrating an operational
cycle of the internal combustion engine shown in FIG. 10.
FIG. 14 is an enlarged longitudinal sectional
view of an essential portion of a prior art two-cycle
internal combustion engine.
FIG. 15 is an enlarged horizontal sectional view
of an essential portion of the prior art internal
combustion engine.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a longitudinal sectional view of a
first embodiment of a two-cycle internal combustion
engine of the present invention; FIG. 2 is an enlarged
longitudinal sectional view of an essential portion of
the engine shown in FIG. 1; and FIG. 3 is an enlarged
horizontal sectional view of an essential portion of the
engine shown in FIG. 1.
Referring to FIG. 1, a two-cycle internal
combustion engine 1 is mounted to a motorcycle (not
shown), wherein a cylinder block 3 and a cylinder head 4
are sequentially stacked on a crankcase 2 and are
integrally jointed to each other.
A piston 6 is vertically slidably fitted in a
cylinder 5 formed in the cylinder block 3. The piston 6
is connected to a crankshaft 8 via a connecting rod 7,
whereby the crankshaft 8 is rotated along with upward/
downward movement of the piston 6.
An intake passage 10 extending from the rear side
to the front side of the vehicular body is connected to
- 10 -
CA 02352848 2003-11-03
WH-11 267CA
an intake passage 11 of the crankcase 2. A throttle
valve (not shown) and a reed valve 12 are interposed in
series in the intake passage 11. The throttle valve is
connected to a throttle grip (not shown) via a connecting
means (not shown). The opening degree of the throttle
valve is increased by twisting the throttle grip in one
direction.
An exhaust passage 17 having an exhaust opening
18 is provided in a portion, on one side in the
peripheral direction, of the cylinder block 3. A chamber
portion 21 is provided in a portion, on the side far from
the exhaust passage 17, of the cylinder block 3.
Referring to FIGS. 1 and 3, two pairs of right
and left scavenging passages 13 for communicating an
upper portion of the cylinder 5 to a crank chamber 9 are
formed in the crankcase 2 and the cylinder block 3. Each
pair of the scavenging passages 13 for supplying air have
scavenging openings 14 which are opened at positions
being laterally symmetric with respect to a plane
containing the exhaust opening 18 and the center line of
the cylinder 5. A scavenging passage 15 for supplying
air is also formed in the crankcase 2 and the cylinder
block 3. The scavenging passage 15 has a scavenging
opening 16 which is opened at a position opposite to the
exhaust opening 18 of the cylinder 5. That is to say,
five pieces of the scavenging passages for supplying air
are formed in the crankcase 2 and the cylinder block 3.
The scavenging passage 15 for supplying air is directly
connected to a portion, on the downstream side from the
reed valve 12, of the intake passage 11 of the crankcase
2. Schnurle scavenging is performed by air blown from
these scavenging passages. As shown in FIG. 1, the
scavenging opening 18 extends to a position higher than
- 11 -
CA 02352848 2003-11-03
WH-11 267CA
the scavenging openings 14 and 16. An approximately
semi-spherical combustion chamber 19 disposed over the
cylinder 5 is offset to the exhaust opening 18. An
ignition plug 20 is mounted to the combustion chamber 19.
Referring to FIGS. 2 and 3, a communication
passage 40 for communicating an upper portion of the
cylinder 5 to the chamber portion 21 is provided in the
cylinder block 3. A valve housing hole 41 is provided in
such a manner as to cross a mid portion of the
communication passage 40. A rotary valve 42 is rotatably
mounted in the valve housing hole 41. The rotary valve
42 is rotated at the same rotational speed as that of the
crankshaft 8 in the rotational direction (clockwise in
FIG. 1) reversed to the rotational direction of the
crankshaft 8 by a transmission mechanism (not shown).
Reference numeral 43 designates a pulley mounted to one
end of the rotary valve 42. The transmission mechanism
(not shown) is wound around the pulley 43.
The communication passage 40 is commonly used for
allowing a high compression gas to flow from the
combustion chamber 19 into the chamber portion 21
therethrough and for allowing an air-fuel mixture and the
high compression gas to flow from the chamber portion 21
into the combustion chamber 19 therethrough. The
communication passage 40 is composed of a cylinder side
passage portion 45 and a chamber portion side passage
portion 46, which are disposed with a control portion of
the rotary valve 40 put therebetween. Reference numeral
51 designates a cylinder side opening of the
communication passage 40, and 52 is a chamber portion
side opening of the communication passage 40. A fuel
injector 48 is connected to the chamber portion side
portion 46 of the communication passage 40 via a
- 12 -
CA 02352848 2003-11-03
WH-11 267CA
connecting passage 47 extending obliquely rearwardly from
the chamber portion side passage portion 46.
Referring to FIG. 2, a control valve 55 is formed
in the rotary valve 42. The control valve 55 has a
portion forming a second control valve 57 and a portion
forming a first control valve 56, which are continuously
disposed in this order from the front side in the
rotational direction. The second control valve 57 is
operative for controlling the injection of an air-fuel
mixture in the direction from the chamber portion 21 to
the combustion chamber 19, and the first control valve 56
is operative for controlling the flow of a high
compression gas in the direction from the combustion
chamber 19 to the chamber portion 21.
The switching from the flow of an air-fuel
mixture to the flow of a high compression gas by the
rotary valve 42 is dependent on a balancing relationship
between a pressure in the combustion chamber 19 and a
pressure in the chamber portion 21 because the
communication passage 40 is taken as the common
communication passage. To be more specific, when the
pressure in the combustion chamber 19 becomes higher than
the pressure in the chamber portion 21, the flow in the
communication passage 40 is switched from the flow of the
air-fuel mixture into the flow of the high compression
gas. Nearly at this time, the flow control of the air-
fuel mixture by the second control valve 57 is shifted to
the flow control of the high compression gas by the first
control valve 56.
Referring to FIG. 2, a portion formed into a
crescent shape in cross-section, designated by reference
numeral 49, is a fuel sump recess provided in the
- 13 -
CA 02352848 2003-11-03
WH-11 267CA
cylinder block 3 at a boundary between the inner wall of
the communication 40 and the outer peripheral surface of
the rotary valve 42. Fuel, which has been impinged on
the inner wall of the chamber portion side passage
portion 46 of the communication passage 40 and reached
the second control valve 57, is captured in the fuel sump
recess 49 until the second control valve 42 is opened.
Accordingly, it is possible to positively supply fuel in
the combustion chamber at the time of starting the
opening of the control valve without occurrence of
counterflow of the fuel to the chamber portion 21 side.
An air-fuel mixture is formed as follows: namely,
fuel is injected from the fuel injector 48 onto an inner
wall surface of the chamber portion side passage portion
46 of the communication passage 40 before the second
control valve 57 opens the communication passage 40, and
when the second control valve 57 opens the communication
passage 40, a high compression gas charged in the chamber
portion 21 flows from the chamber portion side opening 52
of the communication passage 40, to be mixed with the
standby fuel. A rich air-fuel mixture thus formed is
then press-fed by the high compression gas in the chamber
portion 21, to be injected from the cylinder side opening
51 of the communication passage 40 into the combustion
chamber 19. Thereafter, at a point of time when the
rotation of the rotary valve 42 advances and the first
control valve 56 opens the communication passage 40, a
high compression gas is charged from the combustion
chamber 19 into the chamber portion 21, to be used for
the next press-feeding of fuel.
According to this embodiment, in order to deflect
the injecting direction of the rich air-fuel mixture 60
to either the rightward direction or the leftward
- 14 -
CA 02352848 2003-11-03
WH-11 267CA
direction, side walls of the cylinder side passage
portion of the communication passage are tilted with
respect to a cylinder symmetric plane (containing the
exhaust opening and the center line of the cylinder).
FIG. 3 shows a state in which side walls 70 of the
cylinder side passage portion 45 of the communication
passage are tilted leftwardly with respect to a center
line C-C representing the above cylinder symmetric plane
in order to deflect the injecting direction of the rich
air-fuel mixture to the leftward direction. The
injecting direction of the rich air-fuel mixture may be
deflected to the rightward direction. In addition, the
height of the injecting direction of the rich air-fuel
mixture is set such that the injected rich air-fuel
mixture is directed toward a connecting portion between
the cylinder and the cylinder head.
FIGS. 4(a) to 4(c) are illustrative views showing
a positional relationship between the flow of the rich
air-fuel mixture 60 and the flow of the scavenging eddies
61, wherein FIG. 4(a) is a perspective view of the
internal combustion engine as seen from a point offset
obliquely rearwardly, slightly upwardly from the engine;
FIG. 4(b) is a perspective rear view of the engine; and
FIG. 4(c) is a perspective side view of the engine. As
is apparent from these views, the flow of the injected
rich air-fuel mixture 60 obliquely crosses the flow of
the scavenging eddies 61 which travel in the direction
reversed to the traveling direction of the flow of the
injected rich air-fuel mixture 60. Accordingly, the
scavenging eddies 61 are destroyed before the piston 6 is
moved up and thereby the flow of the scavenging eddies 61
is disturbed. As a result, it is possible to accelerate
the uniform mixture of the rich air-fuel mixture with air
over the entire region of the inside of the combustion
- 15 -
CA 02352848 2003-11-03
WH-11 267CA
chamber, and hence to realize desirable combustion.
Further, since the flow of the rich air-fuel mixture 60
is not directly impinged on the ignition plug 20, it is
possible to prevent the ignition plug 20 from being
fogged with the rich air-fuel mixture.
In addition, if the height of the injecting
direction of the rich air-fuel mixture is set such that
the injected rich air-fuel mixture is directed to the
ceiling of the combustion chamber, the ignition plug is
fogged with the rich air-fuel mixture. On the other
hand, if the height of the injecting direction of the
rich air-fuel mixture is set to be excessively lower, the
inner wall of the cylinder becomes wet with the rich air-
fuel mixture, with a result that there may occur
inconveniences that desirable combustion cannot be
performed and that lubricating oil is carried away
therewith. For this reason, the height of the injecting
direction of the rich air-fuel mixture is preferably set
such that the injected rich air-fuel mixture is directed
to a connecting portion between the cylinder and the
cylinder head.
The two-cycle internal combustion engine 1
configured as described above is operated in accordance
with an operational cycle shown in FIG. 5. As the
crankshaft 8 is rotated counterclockwise in FIG. 1 by a
starter motor (not shown), the piston 6 is moved up in
the cylinder 5. At a point of time of about 58°past the
bottom dead center, the scavenging openings 14 and 16 for
supplying air are closed by upwardly movement of the
piston 6, to stop the scavenging by the flow-in of air
through the scavenging passages 13 and 15, and nearly
from this point of time, the second control valve 57
opens the communication passage 40 to inject an air-fuel
- 16 -
CA 02352848 2003-11-03
WH-11 267CA
mixture from the opening 51 into the combustion chamber
19, thereby scavenging the residual burnt gas, and at the
same time, air is sucked from the intake passages 10 and
11 into the crank chamber 9 via the reed valve 12 by
expansion of the crank chamber 9 due to upward movement
of the piston 6.
At a point of time of 90°before the top dead
center, the exhaust opening 18 is closed with the piston
6, so that the operational cycle enters a compression
stroke. Nearly at this point of time, the control valve
is switched from the second control valve 57 into the
first control valve 56, whereby the supply of the air-
fuel mixture in the combustion chamber 19 is ended and a
high compression gas in the combustion chamber 19 is
charged into the chamber portion 21 via the communication
passage 40.
At a point of time of 75° before the top dead
center, the first control valve 56 is closed to close the
communication passage 40, and further, the opening 51 is
closed with the piston 6, to thereby end the charging of
the high compression gas into the chamber portion 21.
The combustion chamber 19 is further compressed,
and at a specific timing before the top dead center, the
ignition plug 20 is ignited. Meanwhile, the crank
chamber 9 is continued to be expanded by upward movement
of the piston 6, to continue air suction until the piston
6 reaches the top dead center.
After the piston 6 reaches the top dead center,
the air-fuel mixture in the combustion chamber 19 is
burnt to be expanded, and also the crank chamber 9 is
compressed by downward movement of the piston 6, to
- 17 -
CA 02352848 2003-11-03
WH-11 267CA
compress the air in the crank chamber 9.
At a point of time of 90°past the top dead
center, the exhaust opening 18 is opened, whereby the
burnt gas is discharged from the exhaust passage 17.
At a point of time of about 122°past the top dead
center, the scavenging openings 14 and 16 are opened by
downward movement of the piston 6, whereby the compressed
air (containing no fuel) in the crank chamber 9 flows in
the combustion chamber 19 via the scavenging passages 13
and 15 for supplying air, to push the burnt gas in the
combustion chamber 19 toward the exhaust opening 18,
thereby performing the scavenging only by air, and at the
same time, fuel is injected from the fuel injector 48
onto the inner wall surface of the chamber portion side
passage portion 46 of the communication passage 40.
At a point of time of about 58°past the bottom
dead center, the scavenging by the flow-in of air from
the scavenging passages 13 and 15 is stopped, and the
second control valves 57 opens the communication passage
40, to inject the air-fuel mixture into the combustion
chamber 19, thereby scavenging the residual burnt gas.
At the same time, air is sucked into the crank chamber 9
via the intake passages 10 and 11. The operational cycle
is thus ended.
FIG. 6 is a horizontal sectional view of a second
embodiment of the two-cycle internal combustion engine of
the present invention. According to this embodiment,
like the first embodiment, it is intended to deflect mist
of a rich air-fuel mixture on either the right side or
the left side in the cylinder. According to this
embodiment, side walls 70 of a cylinder side passage
- 18 -
CA 02352848 2003-11-03
WH-11 267CA
portion 45 of a communication passage are tilted with
respect to the cylinder symmetric plane (containing an
exhaust opening, the center line of a cylinder, and the
cylinder side opening of the communication passage), and
further, a guide vane 71 as a baffle wall for deflecting
the flow of the rich air-fuel mixture is provided in the
cylinder side passage portion 45 of the communication
passage. With this configuration, it is possible to
positively deflect the flow of the rich air-fuel mixture,
and hence to accelerate the mixture of the rich air-fuel
mixture with air and prevent the fogging of an ignition
plug with the rich air-fuel mixture. While the injecting
direction of the rich air-fuel mixture is set to the
leftward direction in FIG. 6, it may be set to the
rightward direction. Although only one guide vane is
shown in the figure, a plurality of guide vanes may be
provided. The configurations and functions of parts
other than those described above are the same as those of
the corresponding parts in the first embodiment.
FIG. 7 is a horizontal sectional view of a third
embodiment of the two-cycle internal combustion engine of
the present invention. According to this embodiment, it
is intended to deflect mist of a rich air-fuel mixture on
the rightward and leftward directions in a cylinder with
the flow quantities of the deflected parts of the rich
air-fuel mixture being nearly equal to each other. To
achieve such an object, a wedge-shaped partitioning
member 72 for branching the flow of the rich air-fuel
mixture into two parts is provided in a central portion
of a cylinder side passage portion 45 of a communication
passage. The cylinder side passage portion 45 is divided
into two passages 45a and 45b by the partitioning member
72. Side walls 70a of the passage 45a are leftwardly
tilted with respect to the cylinder symmetric plane and
- 19 -
CA 02352848 2003-11-03
WH-11 267CA
side walls 70b of the passage 45b are rightwardly tilted
with respect to the cylinder symmetric plane in order to
deflect a flow 60a of the rich air-fuel mixture injected
from the passage 45a leftwardly and deflect a flow 60b of
the rich air-fuel mixture injected from the passage 45b
rightwardly. According to this embodiment, since the
injected flow 60 of the rich air-fuel mixture is not
directly impinged on an ignition plug, it is possible to
prevent the fogging of the ignition plug with the rich
air-fuel mixture. Further, since the injected flow of
the rich air-fuel mixture exerts, from the right and left
sides, an effect on scavenging eddies to destroy the
scavenging eddies, it is possible to accelerate the
mixture of the rich air-fuel mixture with air. The
configurations and functions of parts other than those
described above are the same as those of the
corresponding parts in the first embodiment.
FIG. 8 is a horizontal sectional view of a fourth
embodiment of the two-cycle internal combustion engine of
the present invention. According to this embodiment, it
is intended to deflect mist of a rich air-fuel mixture on
the right and left sides in a cylinder in such a manner
that the flow quantity of the deflected part on one of
the right and left sides is set to be larger than that of
the deflected part on the other side. To achieve such an
object, a wedge-shaped partitioning member 72 for
branching the flow of the rich air-fuel mixture into two
parts is provided in a cylinder side passage portion 45
of a communication passage in such a manner as to be
offset to one of the right and left sides. As a result,
the cylinder side passage portion 45 of the communication
passage is divided into two passages 45a and 45b
different in volume from each other. Further, side walls
70a of the passage 45a are leftwardly tilted with respect
- 20 -
CA 02352848 2003-11-03
WH-11 267CA
to the cylinder symmetric plane and side walls 70b of the
passage 45b are rightwardly tilted with respect to the
cylinder symmetric plane. With this configuration, a
large quantity of a flow 60a of the rich air-fuel mixture
and a small quantity of a flow 60b of the rich air-fuel
mixture are formed. According to this embodiment, since
the injected flow 60 of the rich air-fuel mixture is not
directly impinged on an ignition plug, it is possible to
prevent the fogging of the ignition plug with the rich
air-fuel mixture. Further, since the injected flow of
the rich air-fuel mixture exerts, from the right and left
sides, an effect on scavenging eddies to destroy the
scavenging eddies like the third embodiment, it is
possible to accelerate the mixture of the rich air-fuel
mixture with air. In addition, although the flow
deflected on the left side is set as the flow of a large
quantity in FIG. 8, the flow deflected on the right side
may be set as the flow of a large quantity. The
configurations and functions of parts other than those
described above are the same as those of the
corresponding parts in the first embodiment.
FIG. 9 is a horizontal sectional view of a fifth
embodiment of the two-cycle internal combustion engine of
the present invention. According to this embodiment,
like the first embodiment, it is intended to deflect mist
of a rich air-fuel mixture on either the right side or
the left side in a cylinder. In general, to deflect a
fluid, a tilted passage on the outlet side is required to
be made as longer as possible. In the above-described
first to fourth embodiments, the length of the tilted
passage is set to be long enough to deflect the flow of
the rich air-fuel mixture. However, it may often fail to
ensure a sufficient length of the tilted passage on the
basis of, for example, the structural reason of the
- 21 -
CA 02352848 2003-11-03
WH-11 267CA
engine. This embodiment is intended to provide a
suitable means to cope with such an inconvenience. Like
the first embodiment, side walls 70 of a cylinder side
passage portion 45 of a communication passage are tilted
with respect to the cylinder symmetric plane. In
addition to this configuration, side walls 73 of a
passage of a control valve 55 are tilted in the same
direction as the tilt direction of the side walls 70 of
the cylinder side passage portion 45 of the communication
passage. Since the control valve 55 shown in FIG. 9 is
formed as a groove in the surface of a cylindrical rotary
valve, the passage of the control valve 55 is formed into
a spiral shape from the three-dimensional view.
According to this embodiment, it is possible to
positively deflect the flow of the rich air-fuel mixture,
and hence to accelerate the mixture of the rich air-fuel
mixture with air and prevent the fogging of an ignition
plug with the rich air-fuel mixture. While the injecting
direction of the rich air-fuel mixture is set to the
leftward direction in FIG. 9, it may be set to the
rightward direction.
A sixth embodiment of the present invention will
be described below. FIG. 10 is a longitudinal sectional
view of an essential portion of a spark ignition type
two-cycle internal combustion engine according to the
sixth embodiment of the present invention; FIG. 11 is a
horizontal sectional view taken on a cross-sectional
plane passing through a rotary valve shown in FIG. 10;
and FIGS. 12(a) and 12(b) are views showing the rotary
valve according to this embodiment.
In the first to fifth embodiments, a high
compression gas is supplied from the combustion chamber
into the chamber portion via the first control valve 56
- 22 -
CA 02352848 2003-11-03
WH-21 267CA
of the control valve; however, in this embodiment, the
first control valve 56 is omitted and a high compression
gas is supplied into the chamber portion by a pump (not
shown) separately provided. Accordingly, in this
embodiment, only the second control valve 57 is left as
the control valve, and therefore, the adjective "second"
is omitted and the valve having a function of the second
control valve 57 is referred to simply as "control valve
57a".
Referring to FIGS. 10 and 11, a chamber portion
21a is provided in a portion, offset to the rear side of
the vehicular body, of a cylinder block 3. Reference
numeral 80 designates a pump connection port provided in
one end surface of the chamber portion 21a. A pump (not
shown) for injecting a high compression gas is connected
to the pump connection port. A communication passage 40
for communicating the chamber portion 21a to a cylinder
bore 5 is provided in the cylinder block 3.
A valve housing hole 41 is provided in such a
manner as to cross a mid portion of the communication
passage 40. A rotary valve 42 is rotatably fitted in the
valve housing hole 41. The rotary valve 42 is rotated
via a pulley 43 mounted to an end portion of the rotary
valve 42 by a transmission mechanism (not shown).
FIGS. 12(a) and 12(b) show the rotary valve 42.
As shown in these figures, a control valve 57a is formed
as a cutout having a specific length in the peripheral
direction and also having a specific depth. The control
valve 57a has no portion equivalent to the first control
valve 56 described in the first embodiment (see FIG. 2)
and is configured only by a portion equivalent to the
second control valve 57 in the first embodiment. Like
- 23
CA 02352848 2003-11-03
WH-11 267CA
the first embodiment, the edges of the cutout functioning
as the control valve 57a are formed so as not to be
stepped for allowing an air-fuel mixture to be linearly,
smoothly sprayed. Fuel is injected from a fuel injector
48 (see FIG. lo) immediately before the control valve 57a
opens the communication passage.
FIG. 13 is a diagram illustrating an operational
cycle of this embodiment. The operational cycle of this
embodiment is different from the operational cycle of
each of the first to fifth embodiments in that a high
compression gas is charged in the chamber portion not
from the combustion chamber but from another gas source
by means of a pump (not shown). Accordingly, in this
embodiment, the process "Charging of High Compression Gas
in Chamber Portion Via First Communication Passage" shown
by the arrow in FIG. 5 is omitted. The control valve 57a
opens the communication passage 40 nearly at a point of
time when the scavenging opening is closed, and closes
the communication passage 40 when the compression stroke
begins. The other processes are carried out in the same
manner as those described in the first embodiment. In
the internal combustion engine of this embodiment, since
a high compression gas is charged not from the combustion
chamber but from another gas source, it is possible to
suitably adjust the air-fuel mixture blowing pressure.
According to this embodiment, as shown in FIG.
11, in order to deflect the injecting direction of a rich
air-fuel mixture 60 to either the rightward direction or
the leftward direction, side walls of a cylinder side
passage portion 45 of the communication passage 40 are
tilted with respect to the cylinder symmetric plane
(containing the exhaust opening and the center line of
the cylinder). FIG. 11 shows a state in which the side
- 24
CA 02352848 2003-11-03
WH-11 267CA
walls 70 of the cylinder side passage portion 45 of the
communication passage are leftwardly tilted with respect
to the cylinder symmetric plane in order to deflect the
injecting direction of the rich air-fuel mixture to the
leftward direction. The injecting direction of the rich
air-fuel mixture may be deflected to the rightward
direction. The height of the injecting direction of the
rich air-fuel mixture may be set such that the injected
rich air-fuel mixture is directed, as shown in Fig. 10,
to a connecting portion between the cylinder block 3 and
a cylinder head 4. As described in the first embodiment
with reference to FIG. 4, such injection of the rich air-
fuel mixture is advantageous in that the scavenging
eddies 61 are destroyed by the flow of the rich air-fuel
mixture 60, to accelerate the uniform mixture of the rich
air-fuel mixture with air and prevent the fogging of an
ignition plug with the rich air-fuel mixture.
According to the sixth embodiment, the tilt
injection of an air-fuel mixture described in the first
embodiment becomes effective for an internal combustion
engine which is different from that described in the
first embodiment in terms of the type of charging a high
compression gas into a chamber portion, the shape of a
control valve, and the operational cycle. The
configurations and functions of parts other than those
described above are the same as those of the
corresponding parts in the first embodiment, and
therefore, the parts other than those described above are
designated in the figures by the same reference numerals
of the corresponding parts in the first embodiment and
the overlapped description thereof is omitted.
The shape of the rich air-fuel mixture blowing
port described in each of the second to fifth embodiments
- 25 -
CA 02352848 2003-11-03
WH-11 267CA
can be applied to an internal combustion engine which is
identical to that described in the sixth embodiment in
terms of the type of charging a high compression gas into
a chamber portion, the shape of a control valve, and the
operational cycle. That is to say, like the second
embodiment (see FTG. 6), the side walls 70 of the
cylinder side passage portion 45 of the communication
passage may be tilted rightwardly or leftwardly with
respect to the cylinder symmetric plane in order to
deflect mist of a rich air-fuel mixture on either the
right side or the left side, and further, one or a
plurality of the guide vanes 71 as baffle walls for
deflecting the flow of the rich air-fuel mixture may be
provided in the cylinder side passage portion 45 of the
communication passage. With this configuration, it is
possible to positively deflect the flow 60 of the rich
air-fuel mixture, and hence to accelerate the mixture of
the rich air-fuel mixture with air and prevent the
fogging of the ignition plug with the rich air-fuel
mixture.
Like the third embodiment (see FIG. 7), in order
to deflect mist of the rich air-fuel mixture in the
cylinder with the flow qualities of the deflected parts
on the right and left sides being made nearly equal to
each other, the wedge-shaped partitioning member 72 for
branching the flow of the rich air-fuel mixture may be
provided in a central portion of the cylinder side
passage portion of the communication passage. With this
configuration, since the injected flow 60 of the rich
air-fuel mixture is not directly impinged on the ignition
plug and the injected flow of the rich air-fuel mixture
exerts, from the right and left sides, an effect on the
scavenging eddies, it is possible to accelerate the
mixture of the rich air-fuel mixture with air.
- 26 -
CA 02352848 2003-11-03
WH-11 267CA
Like the fourth embodiment (see FIG. 8), in order
to deflect mist of the rich air-fuel mixture in the
cylinder with the flow quantity of the deflected part on
one of the right and left sides being made larger than
that of the deflected part on the other side, the wedge-
shaped partitioning member 72 for branching the flow of
the rich air-fuel mixture into two parts may be provided
in the cylinder side passage portion 45 of the
communication passage in such a manner as to be offset to
one of the right and left sides, and further, the side
walls 70a and 70b of the left and right passages of the
cylinder side passage portion 45 of a communication
passage may be tilted leftwardly and rightwardly with
respect to the cylinder symmetric plane. with this
configuration, it is possible to accelerate the mixture
of the rich air-fuel mixture with air.
Like the fifth embodiment (see FIG. 9), in order
to deflect mist of the rich air-fuel mixture on either
the right side or the left side in the cylinder, the side
walls 70 of the cylinder side passage portion 45 of the
communication passage may be tilted with respect to the
cylinder symmetric plane, and further the side walls 73
of the passage of the control valve 57a may be tilted in
the same direction as the tilt direction of the side
walls 70 of the cylinder side passage portion 45 of the
communication passage. In this case, the control valve
may be formed into a spiral shape. With this
configuration, it is possible to positively deflect the
flow 60 of the rich air-fuel mixture and hence to
accelerate the mixture of the rich air-fuel mixture with
air. This is effective for the case where the length of
the cylinder side passage portion 45 of the communication
passage cannot be sufficiently ensured.
- 27 -
CA 02352848 2003-11-03
WH-11 267CA
According to the present invention, mist of a
rich air-fuel mixture is injected into the cylinder while
being deflected on either on the right side or the left
side of the cylinder, being deflected on both the right
and left sides of the cylinder with flow quantities of
the branched flows being made equal to each other, or
being deflected on both the right and left sides of the
cylinder with flow quantities of the branched flows being
made different from each other by tilting the side walls
of the cylinder side passage portion of the communication
passage, providing a wedge-shaped partitioning member, or
forming a passage of the control valve into a spiral
shape. Accordingly, since the injected flow 60 of the
rich air-fuel mixture exerts, from both the sides, an
effect on the existent scavenging eddies 61, to destroy
the scavenging eddies and disturb the flow of the
scavenging eddies, with a result that it is possible to
accelerate the mixture of the rich air-fuel mixture with
air over the entire region of the inside of the
combustion chamber before upward movement of the piston,
thereby achieving desirable combustion, particularly, at
full load operation of the vehicle.
Since the injecting direction of the rich air
fuel mixture is deflected to either the rightward
direction or the leftward direction while avoiding the
direction toward the ignition plug, it is possible to
reduce the fogging of the ignition plug with the rich
air-fuel mixture.
Since the rich air-fuel mixture is injected
toward a connecting portion between the cylinder and the
cylinder head, it is possible to suppress the ignition
plug from being fogged with the rich air-fuel mixture as
- 28 -
CA 02352848 2003-11-03
WH-11 267CA
described, and also prevent the inner wall of the
cylinder from being excessively made wet with the rich
air-fuel mixture, that is, gasoline, and hence to achieve
desirable combustion and to suppress lubricating oil from
being carried away with the gasoline.
Although various preferred embodiments of the
present invention have been described herein in detail,
it will be appreciated by those skilled in the art, that
variations may be made thereto without departing from the
spirit of the invention or the scope of the appended
claims.
- 29 -
