Internal-combustion engines – Charge forming device – Charge-mixing device in intake
Reexamination Certificate
2000-08-17
2002-03-12
Kwon, John (Department: 3747)
Internal-combustion engines
Charge forming device
Charge-mixing device in intake
C123S336000
Reexamination Certificate
active
06354284
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an intake device for a multi-cylinder engine.
2. Description of Prior Art
A conventional intake device for a multi-cylinder engine has a slow port formed in a ceiling wall of a mixing passage of a carburetor. According to this intake device, there is a likelihood that liquid fuel overflowed on a ceiling wall surface of the mixing passage from the slow port is blown downstream along an inner wall surface of the mixing passage. However, the conventional intake device lacks a means which accelerates atomization of the liquid fuel to be blown downstream from the slow port of the ceiling wall. This entails a case where the liquid fuel flows, as it remains liquid, into each of intake ports formed within a cylinder head. In this case, the fuel is distributed to respective cylinders non-uniformly to result in excessive or insufficient fuel supply. This causes mis-ignition or increases CO concentration in the exhaust gas.
Further, most of conventional intake devices each attaches a carburetor to a cylinder head through an intake manifold. Thus the carburetor projects from the cylinder head largely, which causes an engine to become large.
SUMMARY OF THE INVENTION
The present invention has an object to provide an intake device for a multi-cylinder engine, which can solve the foregoing problems.
An invention of claim
1
, as exemplified in FIG.
1
(B) or FIG.
3
(B), forms a slow port
6
in a ceiling wall
4
b
of a mixing passage
4
so as to face downwards and has a peripheral wall of a fuel-air mixture passage portion
7
a
positioned downstream of the slow port
6
and upstream of a fuel-air mixture inlet
10
, which peripheral wall is provided with a liquid fuel receiver
31
. Therefore, it has the following advantage.
Fuel oil drops which fall down from the slow port
6
are involved in a current of a fuel-air mixture passing through the mixing passage
4
to accelerate their atomization. The liquid fuel overflowed on a ceiling wall surface of the mixing passage
4
from the slow port
6
is atomized to a certain degree while it is blown downstream along an inner wall surface of the mixing passage
4
. The remaining liquid fuel not atomized while it is blown downstream is received by the liquid fuel receiver
31
to accelerate its atomization owing to the action of the mixture current. As such, the liquid fuel which has flowed out of the slow port
6
of the ceiling wall
4
b
of the mixing passage
4
accelerates its atomization before it reaches the mixture inlet
10
of a cylinder head
23
illustrated in FIG.
1
(A) or FIG.
3
(A). This can uniformly distribute the fuel from the mixture inlet
10
to respective intake ports
12
,
12
through branched passages
11
,
11
, thereby inhibiting occurrence of the disadvantages caused by the non-uniform distribution of the fuel to respective cylinders, such as mis-ignition and increase of CO concentration in the exhaust gas.
The invention of claim
1
, as exemplified in FIG.
1
(A) or FIG.
3
(A), has the branched passages
11
,
11
provided within the cylinder head
23
. This dispenses with the intake manifold to result in the possibility of decreasing the projection of the carburetor
1
from the cylinder head
23
in an attempt to downsize the engine.
According to an invention of claim
2
, as exemplified in FIG.
1
(B) or FIG.
3
(B), the liquid fuel receiver
31
comprises a groove
8
formed by concaving a ceiling wall
7
b
of the mixture passage portion
7
a
. Therefore, it has the following advantage.
In the case where the mixture current flows at a relatively high speed, most of the liquid fuel overflowed on a ceiling wall surface of the mixing passage
4
from the slow port
6
is blown downstream along the ceiling wall surface of the mixing passage
4
. The liquid fuel not atomized while it is blown downstream flows into the groove
8
provided in the ceiling wall
7
b
of the mixture passage portion
7
a
and is received here to accelerate its atomization with the action of a negative pressure produced by the mixture current passing by the vicinity of an opening of the groove
8
.
According to an invention of claim
3
, as exemplified in FIG.
1
(A) or FIG.
3
(A), the liquid fuel receiver
31
further includes grooves
8
,
8
formed by concaving left and right both side walls
7
c
,
7
c
of the mixture passage portion
7
a
. Therefore, it has the following advantage.
In the case where the mixture current flows at a relatively low speed, most of the liquid fuel overflowed on the ceiling wall surface of the mixing passage
4
from the slow port
6
is blown downstream first along the ceiling wall surface of the mixing passage
4
and then along left and right both side wall surfaces of the mixing passage
4
while it is gradually falling down by its own weight. The liquid fuel not atomized while it is blown downstream flows into the grooves
8
,
8
formed in the left and right both side walls
7
c
,
7
c
of the mixture passage portion
7
a
and is received here to accelerate its atomization with the action of a negative pressure produced by the mixture current passing by the vicinity of an opening of each of the grooves
8
,
8
.
According to an invention of claim
4
, as exemplified in FIG.
1
(B) or FIG.
3
(B), the liquid fuel receiver
31
comprises a wall
9
a
projecting from the ceiling wall
7
b
of the mixture passage portion
7
a
. This wall
9
a
forms a throttle hole
9
for the mixture. Therefore, it has the following advantage.
The liquid fuel not atomized while it is blown downstream along the ceiling wall surface of the mixing passage
4
is received by the wall
9
a
projecting from the ceiling wall
7
b
of the mixture passage portion
7
a
to accelerate its atomization with the action of a negative pressure produced by the mixture current passing through the throttle hole
9
.
According to an invention of claim
5
, as exemplified in FIG.
1
(A) or FIG.
3
(A), the liquid fuel receiver
31
further includes walls
9
a
,
9
a
projecting from the left and right both side walls
7
c
,
7
c
of the mixture passage portion
7
a
. These walls
9
a
,
9
a
form a throttle hole
9
for the mixture. Therefore, it has the following advantage.
The liquid fuel not atomized while it is blown downstream along left and right both side wall surfaces of the mixing passage
4
is received by the walls
9
a
,
9
a
projecting from the left and right both side walls
7
c
,
7
c
of the mixture passage portion
7
a
to accelerate its atomization with the action of a negative pressure produced by the mixture current passing through the throttle hole
9
.
According to an invention of claim
6
, as exemplified in FIG.
1
(B) or FIG.
3
(B), the liquid fuel receiver
31
comprises a groove
8
formed by concaving the ceiling wall
7
b
of the mixture passage portion
7
a
and a wall
9
a
projecting from the ceiling wall
7
b
of the mixture passage portion
7
a
. This wall
9
a
forms a throttle hole
9
for the mixture. Therefore, it has the following advantage.
The liquid fuel not atomized while it is blown downstream along the ceiling wall surface of the mixing passage
4
flows into the groove
8
formed in the ceiling wall
7
b
of the mixture passage portion
7
a
. Although, in some cases, the liquid fuel which has flowed into the groove
8
may tend to flow downstream out of the groove
8
as it remains liquid, with the action of a negative pressure produced by the mixture current passing by the vicinity of an opening of the groove
8
, it is assuredly received by the wall
9
a
to accelerate its atomization with the action of a negative pressure produced by each of the mixture current passing by the vicinity of the opening of the groove
8
and the mixture current passing through the throttle hole
9
.
Even if the wall
9
a
has a height increased so as to receive the liquid fuel reliably, its projection can be decreased by an amount corresponding to the existence of the groove
8
. This inhibits a throttling resistance of the throttle hol
Kimoto Kiyoharu
Nakano Keiichi
Okano Syunji
Oohashi Tamotu
Bacon & Thomas PLLC
Kubota Corporation
Kwon John
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