Fluid sprinkling – spraying – and diffusing – Fluid pressure responsive discharge modifier* or flow... – Fuel injector or burner
Reexamination Certificate
2001-06-26
2002-05-28
Evans, Robin O. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Fluid pressure responsive discharge modifier* or flow...
Fuel injector or burner
C239S552000, C239S533140, C239S585100, C239S900000, C239S596000
Reexamination Certificate
active
06394367
ABSTRACT:
REFERENCE TO RELATED APPLICATIONS
This application is based on Japanese Patent Application No. 2000-221643, filed in Japan on Jul. 24, 2000, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a fuel injection valve for an internal combustion engine.
2. Description of the Related Art
Fuel injection valves are widely used to supply fuel to internal combustion engines. One example of a known fuel injection valve for use with an internal combustion engine is disclosed in Japanese Published Unexamined Patent Application Hei 9-14090. FIG. 6 is a cross-sectional elevation of a fuel injection valve disclosed in that publication, and FIG. 7 is an enlarged view of the lower end of the fuel injection valve of FIG. 6.
The illustrated fuel injection valve
1
includes an electromagnetic coil
3
, a stationary ferromagnetic core
4
, and metal plates
5
defining a magnetic path, all disposed in a resin housing
2
. The electromagnetic coil assembly
3
includes a resin bobbin
3
a
, a coil
3
b
which is wound around the outer periphery of the bobbin
3
a
, and a terminal
6
which is electrically connected to the coil
3
b
and which enables the coil
3
b
to be electrically connected to an external source of electric power. The resin housing
2
is molded around the electromagnetic coil assembly
3
.
An adjuster
8
for adjusting the load of a compression spring
7
is secured inside the stationary core
4
. Two metal plates
5
(only one of which is visible) which form a magnetic path each have one welded to the stationary core
4
and another end welded to a magnetic pipe
9
which forms a magnetic path. A non-magnetic pipe
11
is disposed between and secured to the fixed core
4
and the magnetic pipe
9
such that a movable ferromagnetic core
10
disposed inside the magnetic pipe
9
can move up and down.
One end of the movable core
10
is welded to a needle
101
, and the other end of the movable core
10
abuts against the compression spring
7
. A valve head
101
a
is formed on the other end of the needle
101
and is guided with respect to a valve seat
102
by a guide portion
101
b.
The valve head
101
a
is moved between an open and a closed position by an electromagnetic drive mechanism disposed at the upper portion. The valve head
101
a
opens and closes the valve by moving out of or into contact with the top surface of the valve seat
102
. When the valve head
101
a
is in an open position, fuel flows past the valve head
101
a
to an orifice plate having discharge orifices
103
formed therein and is sprayed from the discharge orifices
103
to the exterior of the fuel injection valve into an internal combustion engine.
In the conventional fuel injection valve shown in
FIGS. 6 and 7
, the direction of fuel injection is determined by the angle of inclination of the discharge orifices
103
in the orifice plate with respect to the longitudinal axis of the fuel injection valve
1
. Upstream of the orifice plate, fuel flows from the outer peripheral portion to the inner peripheral portion, so it is difficult to obtain a large spray angle for the fuel. Furthermore, when manufacturing a one-spray type having a large spray angle (such as approximately 15 degrees or greater) or a two-spray type having a large spray angle (such as approximately 15 degrees or greater), it is necessary to make the angle of inclination of the discharge orifices
103
large, so it is difficult to form the discharge orifices so as to have a small diameter, and it is difficult and to make the diameter of the discharge orifices
103
small to obtain atomization of the fuel. Even if discharge orifices
103
with a large angle of inclination and a small diameter can be formed, the manufacturing costs for forming such discharge orifices are significant. This is especially the case with respect to an orifice plate having at least six discharge orifices
103
to promote atomization, since with such an orifice plate the diameter of the discharge orifices
103
becomes particularly small, so processing of the orifice plate becomes very difficult.
By increasing the ratio L/&phgr;d of the length L of the discharge orifices
103
to their diameter &phgr;d, the spray direction can be regulated and the spray angle can be increased, but in this case, the atomization of the fuel is worsened. Furthermore, when L/&phgr;d is made large, it becomes difficult to form the discharge orifices
103
in the orifice plate, and increasing the angle of inclination of the discharge orifices
103
increases the difficulty of forming the discharge orifices in the orifice plate, resulting in extreme increases in manufacturing costs.
Japanese Published Unexamined Patent Application Hei 10-122096 discloses a fuel injection valve having a dish-shaped orifice plate in which a fuel cavity is formed. Such an orifice plate is extremely expensive to manufacture.
SUMMARY OF THE INVENTION
The present invention provides a fuel injection valve which can have discharge orifices with a small diameter to promote atomization of fuel without an orifice plate containing the discharge orifices being expensive to manufacture.
According to one form of the present invention, a fuel injection valve includes an orifice plate having a plurality of discharge orifices formed therein. A valve seat is disposed upstream of the discharge orifices and has a cylindrical fuel passage formed therein. A fuel cavity is formed between the cylindrical fuel passage and the orifice plate directly above the discharge orifices. A valve member is supported for reciprocating movement into and out of contact with the valve seat. The fuel injection valve satisfies the inequalities
&phgr;D
1
+&phgr;d<&phgr;P and t<&phgr;d
wherein &phgr;D
1
is the diameter of the cylindrical fuel passage, &phgr;d is the diameter of each discharge orifice, &phgr;P is the diameter of an imaginary circle passing through the center of each discharge orifice, and t is the depth in the axial direction of the fuel cavity.
In a preferred embodiment, the fuel injection valve satisfies the inequality
1<S
2
/S
1
<3
wherein S
1
is the total cross-sectional area of the discharge orifices, and S
2
is the surface area of a cylindrical surface having a diameter equal to the diameter &phgr;D
1
of the cylindrical fuel passage and a height equal to the axial depth t of the fuel cavity.
In a preferred embodiment, the fuel cavity is formed in the valve seat, and the orifice plate is a flat member.
REFERENCES:
patent: 4101074 (1978-07-01), Kiwior
patent: 5762272 (1998-06-01), Tani et al.
patent: 5862991 (1999-01-01), Willke et al.
patent: 5931391 (1999-08-01), Tani et al.
patent: 6070812 (2000-06-01), Tani et al.
patent: 6161780 (2000-12-01), Sugimoto et al.
patent: 6170763 (2001-01-01), Fuchs et al.
patent: 38 08 396 (1989-09-01), None
patent: 197 24 075 A 1 (1998-12-01), None
patent: 197 26 991 A 1 (1999-01-01), None
patent: 0 740 071 (1996-10-01), None
patent: 9-14090 (1997-01-01), None
patent: 10-122096 (1998-05-01), None
patent: 11-200998 (1999-07-01), None
patent: 11-264365 (1999-09-01), None
Munezane Tsuyoshi
Sumida Mamoru
Evans Robin O.
Mitsubishi Denki & Kabushiki Kaisha
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