Internal-combustion engines – Two-cycle – Rear compression
Reexamination Certificate
2001-07-13
2003-07-08
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Two-cycle
Rear compression
C123S445000, C123S0650PE
Reexamination Certificate
active
06588382
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement in the injection direction of an air-fuel mixture into a cylinder of a two-cycle internal combustion engine, the internal combustion engine being configured to prevent blow-by of the air-fuel mixture. With this construction, fuel consumption of the internal combustion engine is decreased and exhaust gas purifying performance is enhanced.
2. Description of Background Art
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. The air-fuel mixture is then sucked into the crank chamber and supplied to the combustion chamber via scavenging openings. The supply of the air-fuel mixture in the conventional engine; however, has a problem since the opening timing of an exhaust opening is set to be earlier than the opening timing of the scavenging openings. Accordingly, a so-called blow-by phenomenon may often occur, wherein the air-fuel mixture supplied to the combustion chamber is discharged to 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
of the present invention 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 a rotary valve shown in FIG.
14
. In these figures, an exhaust passage
017
, which has an exhaust opening
018
formed 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 remote 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 the 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 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 closing 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 closing 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 toward 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. The air-fuel mixture thus formed is press-fed by high pressure in the chamber portion
021
, to be injected into 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 has a large forward traveling force by injection. The mist identified by the solid arrows travels along approximately straight lines. A portion of the mist depicted by the broken lines has a weakened forward traveling force, and 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 existing scavenging eddies
061
. The scavenging eddies
061
are longitudinal eddies generated as follows: namely, air flows of schnurle 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 into the combustion chamber as described above, flows into 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 background 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. Howeve
Argenbright Tony M.
Harris Katrina B.
Honda Giken Kogyo Kabushiki Kaisha
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