Internal-combustion engines – Combustion chamber means combined with air-fuel mixture... – Air or combustible mixture entering the combustion chamber...
Reexamination Certificate
2000-02-16
2001-10-30
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Combustion chamber means combined with air-fuel mixture...
Air or combustible mixture entering the combustion chamber...
C239S533120
Reexamination Certificate
active
06308684
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority of Japanese Patent Application No. H.11-36614 filed on Feb. 16, 1999, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel injection valve provided with a plate having a plurality of injection holes at an injection port of a valve body thereof.
2. Description of Related Art
Recently, many high performance engines have been proposed that have a plurality of intake ports (a plurality of intake valves) in each of the cylinders. For example, as disclosed in JP-U-H.3-63763(refer to FIGS.
4
and
5
), a fuel injection valve to be installed in an intake manifold of the engine is provided with a plate
13
having a plurality of injection holes
12
a
and
12
b
at an injection port of a valve body
11
. Inclination angles (injection direction) of the respective holes
12
a
and
12
b
are so formed that fuel from the holes
12
a
and
12
b
may be injected toward the intake ports
14
a
and
14
b
on target, respectively. a group A of the injection holes
12
a
through which fuel is injected toward the intake port
14
a
and a group B of the injection holes
12
b
through which fuel is injected toward the intake port
14
b
. As the respective hole diameters of the injection holes
12
a
and
12
b
are same, a fuel flow amount distribution rate of the group A to the group B is considered adjustable by respective piece numbers of the injection holes
12
a
and
12
b
to be classified into the respective groups A and B.
In the fuel injection valve
10
mentioned above, the three group A injection holes
12
a
are arranged on a straight line. In the case of such a straight-line arrangement, the fuel flow amounts in the respective injection holes
12
a
are not identical, even if the hole diameters are the same. The reason is that, as highly pressurized fuel flows onto the plate
13
so as to swirl in a circular direction from an outer circumference gap of a needle valve (not shown), a flow speed of the fuel becomes variable along a radial direction on the plate
13
.
Further, in a region of the plate
13
near the outer circumference thereof, the fuel flows downward obliquely from the outer circumference gap of the needle valve. An inflow angle of the fuel downward obliquely flowed to the plate
13
becomes smaller at a position nearer to the inside thereof. Therefore, respective flow amounts of the three injection holes
12
a
arranged on a straight line are different from each other, as the flow speeds and the inflow angles of the fuel to be flowed into the respective three injection holes
12
a
are different. As a result, it is very difficult to accurately adjust the fuel flow amount distribution rate of the group A injection holes to the group B injection holes only by the numbers of injection holes
12
a
and
12
b.
Further, an injection valve is known, as shown in
FIG. 6
, in which a plate
15
is provided with same hole diameter injection holes
1
to
5
arranged on a circumference of a circle. The respective injection holes
1
to
5
are formed obliquely at an inclination angle (in an injection direction) so that the fuel from the respective injection holes
1
to
5
may be injected toward the respective intake ports on target. By arranging the injection holes
1
to
5
on the circumference of the circle, the respective flow speeds and the respective inflow angles of the fuel flowed into the respective injection holes
1
to
5
becomes identical. However, as shown in
FIG. 7
, the fuel flow amounts in the respective injection holes
1
to
5
are different from each other as the inclination angles of the respective injection holes
1
to
5
are different even if the hole diameters thereof are the same.
Next, with reference to
FIG. 8
, a reason why the respective different inclination angles of the injection holes
1
to
5
cause different fuel flow amounts is described. When the fuel, flowed onto the plate
15
from a gap between a needle valve and a valve body, flows in the respective injection holes
1
to
5
, a contraction of the fuel flow takes place. As the contraction takes place based on an inertial force due to a fuel flow direction conversion, the contraction becomes larger in the injection holes
1
to
5
having the larger inclination angle. Therefore, as shown in
FIG. 7
, the fuel injection amount is smaller in the injection holes
1
to
5
having the larger inclination angle. As mentioned above, even if the same diameter injection holes
1
to
5
are arranged on the circumference of the circle, the fuel flow amounts in the respective injection holes
1
to
5
differ due to the difference of the respective inclination angles of the injection holes
1
to
5
. As a result, the fuel flow amount distribution rate on target of one injection hole to another injection hole among the injection holes
1
to
5
or of the group A injection holes to the group B injection holes is hardly secured.
FIG. 7
shows a relationship between an inclination angle of the injection hole and a flow amount rate, when the flow amount of the injection hole
5
having the inclination angle of 30° is referenced as 100.
Though the fuel flow amount distribution rate may be adjusted by changing the respective hole diameters of the infection holes
1
to
5
, such a change causes a higher manufacturing cost for fabricating the injection holes
1
to
5
.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above mentioned problem, and an object of the present invention is to provide a fuel injection valve having a construction that the fuel flow amount distribution rate of one group to the other group may be easily adjusted with a less manufacturing cost.
To achieve the object mentioned above, the fuel injection valve has a plate provided with a plurality of injection holes classified to at least first and second groups. The first group injection holes are so arranged on a circumference of a first circle that fuel from the respective injection holes may be injected toward a first intake port and the second injection holes are so arranged on a circumference of a second circle that fuel from the respective injection holes may be injected toward a second intake port. Diameters of the first and second circles are different so that the fuel flow amount distribution rate of the first group injection holes to the second group injection holes may be adjusted to a predetermined value on target.
As the respective injection holes in the first or second group are arranged on the same circumference of a circle, flow speed and inflow angle of fuel flowed into the respective injection holes in the first or second group are same.
However, as inclination angles of the respective injection holes in the first or second group are not same, the respective fuel flow amounts of the injection holes in the first or second group are not same because of different largeness of the contraction decisive by the inflow angle of fuel and the inclination angle of the injection hole.
Under the circumstances mentioned above, for example, if the diameter of the first circle becomes larger, the respective fuel flow amounts of the injection holes becomes larger at the same rate with each other so that the fuel flow amount distribution rate of the first group to the second group may be easily adjusted. This is because more outwardly shifted positions of the injection holes cause the larger inflow angle of fuel, which results in the smaller contraction, and the more increased flow speed of fuel.
An another aspect of the present invention, instead of changing the diameter of the first or second circle for adjusting the fuel flow amount distribution rate, the respective injection holes in the first and second groups are so arranged respectively at positions radially independently away from a center axis of the valve body that the fuel flow amounts of the respective injection holes are identical to each
Denso Corporation
Dolinar Andrew M.
Nixon & Vanderhye PC
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