Fluid sprinkling – spraying – and diffusing – Including valve means in flow line – Reciprocating
Reexamination Certificate
2003-03-19
2004-06-15
Evans, Robin O. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Including valve means in flow line
Reciprocating
C239S585200, C239S585300, C239S585400, C239S585500, C239S900000, C239S533110
Reexamination Certificate
active
06749137
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic fuel injection valve for use, for example, in an engine for a vehicle.
2. Discussion of Related Art
FIG. 2A
shows a first example of conventional electromagnetic fuel injection valves [see Japanese Patent Application Unexamined Publication (KOKAI) No. Hei 11-200979]. The electromagnetic fuel injection valve has a cylindrical ferromagnetic valve housing
1
at the front end thereof (the lower end in FIG.
2
A). A front half of a ring-shaped, non-magnetic intermediate member
2
is press-fit and welded to the rear end portion of the valve housing
1
(the upper end portion in FIG.
2
A). A front end portion of a hollow shaft-shaped, ferromagnetic core
3
is press-fit and welded to a rear half of the intermediate member
2
. The core
3
has a flange
3
A projecting radially outward from approximately the axial center thereof. A bobbin
4
is molded from a synthetic resin material on the outer periphery of the joint between the intermediate member
2
and the core
3
. The bobbin
4
is wound with a solenoid coil
6
. A terminal mounting portion
4
A is formed on the rear end portion of the bobbin
4
. A connecting end portion
5
A of a terminal
5
is connected to the terminal mounting portion
4
A.
The outer peripheral portion of the solenoid coil
6
is partially surrounded by extending pieces
7
A of a ferromagnetic outer magnetic path forming member
7
. The outer magnetic path forming member
7
has an upper end plate portion with a mounting hole
8
formed in the center thereof. A pair of extending pieces
7
A with an arcuate sectional configuration extend forwardly from the upper end plate portion. The mounting hole
8
of the outer magnetic path forming member
7
is fitted with the core
3
in such a manner that the upper end plate portion is adjacent to the rear surface of the flange
3
A. The front end portions of the extending pieces
7
A of the outer magnetic path forming member
7
are secured to the valve housing
1
by welding. A resin molded portion
12
is formed on the outer periphery of a portion extending from the rear half of the valve housing
1
to the rear end portion of the core
3
. The resin molded portion
12
includes a connector
9
, which is molded simultaneously.
An armature
22
formed by a rear end portion of a moving member
20
is slidably fitted inside the rear portion of the valve housing
1
and the front half of the intermediate member
2
. The moving member
20
is a hollow member having a reduced-diameter cylindrical portion
20
A formed forward of and adjacent to the armature
22
. A ball valve (valving element)
23
is secured to the distal end of the reduced-diameter cylindrical portion
20
A. A lateral hole
20
B is formed in the front end side wall of the reduced-diameter cylindrical portion
20
A. The hollow portion of the moving member
20
and the lateral hole
20
B form in combination a fuel passage
24
. A valve seat
13
in the shape of a cylinder, one end of which is substantially closed, is inserted into and secured to the front end portion of the valve housing
1
. An injection port
15
is formed in the front end wall of the valve seat
13
. An orifice plate
14
is welded to the front end surface of the valve seat
13
. The orifice plate
14
has a plurality of injection holes
14
A formed in the center thereof. The ball valve
23
and the valve seat
13
constitute in combination an injection valve. The injection valve is opened or closed by axial movement of the moving member
20
.
The armature
22
has a stepped surface
25
formed on the inner surface thereof. An adjuster
17
is press-fit in the core
3
. A valve spring
16
is fitted between the front end of the adjuster
17
and the stepped surface
25
of the armature
22
. The valve spring
16
urges the moving member
20
in the valve closing direction. A series of portions of fuel passage
18
(including the fuel passage
24
) is formed by the inside space between the rear end opening of the core
3
and the injection port
15
of the valve seat
13
. A strainer
19
is fitted in the rear end portion of the core
3
. An O-ring
11
is fitted in an annular groove
10
on the outer peripheral surface of the rear end portion of the resin molded core
3
.
Next, the operation of the first conventional example will be described. Pressurized fuel is filtered through the strainer
19
and then supplied to the inside of the valve seat
13
through the fuel passages
18
. An electric signal is input through the terminal
5
and the connecting end portion
5
A to initiate the supply of electric power to the solenoid coil
6
. Consequently, a magnetic flux is created around the solenoid coil
6
. The magnetic flux flows through a magnetic circuit surrounding the solenoid coil
6
. The magnetic circuit is formed by the outer magnetic path forming member
7
, the core
3
, the armature
22
and the valve housing
1
. The intermediate member
2
functions to prevent short-circuiting of the magnetic flux between the core
3
and the valve housing
1
. When the magnetic flux flows through the magnetic circuit, magnetic attractive force is produced between the core
3
and the armature
22
. The magnetic attractive force attracts the armature
22
toward the core
3
, causing the ball valve
23
to open the injection port
15
. Consequently, fuel is injected from the injection port
15
. The injected fuel is sprayed through the injection holes
14
A of the orifice plate
14
. When the supply of electric power to the solenoid coil
6
is cut off and hence the attractive force acting on the armature
22
is canceled, the moving member
20
, together with the ball valve
23
, is advanced by the urging force of the valve spring
16
. Thus, the ball valve
23
closes the injection port
15
to stop the injection of fuel from the injection port
15
.
The electromagnetic fuel injection valve needs to provide a non-magnetic portion in the central pipe part to activate the ball valve. In the first conventional example, the ferromagnetic core
3
, the non-magnetic intermediate member
2
and the ferromagnetic valve housing
1
are welded together to secure the members and to prevent leakage of fuel. However, welding requires a great deal of labor and cost. In addition, welding involves a danger of thermal deformation. To avoid the disadvantages of welding, the following second conventional example was proposed (see Published Japanese Translation of PCT International Publication No. Hei 11-500509).
FIG. 2B
shows an essential part of the second conventional example. In the second conventional example, the central pipe part comprises a single pipe
27
. The pipe
27
is divided into a core
3
, a magnetic restrictor portion
28
and a valve housing
1
, which are different in the wall thickness from each other. When the injection valve opens, the lower end surface
29
of the core
3
abuts against the upper end surface
30
of the armature
22
. When the injection valve is closed, an air gap (e.g. 60 &mgr;m) is produced between the lower end surface
29
and the upper end surface
30
. The magnetic restrictor portion
28
has a very thin wall thickness. For example, the restrictor portion with an axial length of 2 mm has a wall thickness of 0.2 mm. A guide surface
33
is formed on the outer periphery of an upper end portion of the armature
22
at a side thereof facing the restrictor portion
28
. A radial air gap
32
(e.g. 80 &mgr;m) is provided at each of the upper and lower sides of the guide surface
33
, i.e. between the armature
22
and the restrictor portion
28
and between the armature
22
and the valve housing
1
.
The operation of the second conventional example will be described below. When the supply of electric power to the solenoid coil is initiated, a magnetic flux is produced around the solenoid coil. The greater part of the magnetic flux flows through the outer magnetic path forming member (not shown), the core
3
, the armature
22
and the valve ho
Hirata Masami
Kato Yukinori
Kikuta Hikaru
Okubo Tomohiro
Suzuki Motoyuki
Aisan Kogyo Kabushiki Kaisha
Baker & Botts L.L.P.
Evans Robin O.
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