Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-02-26
2004-10-19
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S472000, C239S533200
Reexamination Certificate
active
06805103
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cylinder-injection fuel injection valve mounted in a fuel injection valve insertion port on a cylinder head for injecting fuel through a fuel injection aperture into a cylinder.
2. Description of the Related Art
FIG. 5
is a cross-section showing the complete construction of a conventional cylinder-injection fuel injection valve
1
(hereinafter simply “fuel injection valve”),
FIG. 6
is a partial enlargement of
FIG. 5
, and
FIG. 7
is a plan view of the fork in FIG.
5
.
The fuel injection valve
1
comprises: a housing main body
2
; a valve assembly
3
disposed within the housing main body
2
; a solenoid assembly
4
disposed within the housing main body
2
; and an elastic seal ring
7
with a wave-shaped cross-section in the axial direction disposed between a fuel injection valve insertion port
6
in a cylinder head
5
and the tip of the housing main body
2
.
The valve assembly
3
comprises: a stepped, hollow, cylindrical valve main body
11
having a small-diameter cylinder portion
9
and a large-diameter cylinder portion
10
; a valve seat
13
having a fuel injection aperture
12
secured within an end portion of the valve main body
11
; a needle valve
14
being a valve body moved into and out of contact with the valve seat
13
to close and open the fuel injection aperture
12
; a swirler
15
for guiding the needle valve
14
in the axial direction as well as imparting a swirling motion to the fuel as the fuel flows towards the fuel injection aperture
12
; and a movable armature
16
secured to the other end of the needle valve
14
.
An intermediate portion of the needle valve
14
is formed with: a guide portion
17
for guiding the needle valve
14
as it slides along the inner circumferential surface of the valve main body
11
; and a flange portion
19
for contacting a spacer
18
within the housing main body
2
.
The housing main body
2
comprises: a first housing
21
having a flange for mounting the fuel injection valve
1
on the cylinder head
5
; a second housing
22
connected to one end of the first housing
21
; and a holder
23
connected to the other end of the first housing
21
.
The solenoid assembly
4
comprises: a coil
24
of wound wire; a bobbin on which the coil is mounted; a cylindrical core
26
attached to an inner circumferential portion of the bobbin
25
; a sleeve
27
secured to the inside of the core
26
; a spring
28
compressed and disposed between an end portion of the sleeve
27
and an end portion of the needle valve
14
for pressing the needle valve
14
against the valve seat
13
; and terminals
29
electrically connected to the wire of the coil
24
.
The swirler
15
constituting part of the valve assembly
3
is a hollow, cylindrical member which has a central aperture
30
at its center for supporting the needle valve
14
so that the needle valve
14
can slide in both axial directions, and is provided with: a first end surface
31
in contact with the valve seat
13
; a second end surface
32
at the opposite end from the valve seat
13
; and an outer surface
34
between these two end surfaces
31
,
32
which comes into contact with an inner circumferential surface
33
of the valve main body
11
.
First passages
35
extending radially are formed in the second end surface
32
of the swirler
15
such that fuel flows through the first passages
35
from inner circumferential portions of the second end surface
32
to outer circumferential portions thereof.
Second passages
36
extending longitudinally and connected to the first passages
35
are formed in the outer surface
34
of the swirler
15
.
Swirling grooves
37
are formed in the first end surface
31
of the swirler
15
in connection with the second passages
36
for generating a swirling current.
The tip of a fuel injection valve
1
of the above construction is inserted into the fuel injection valve insertion port
6
in a cylinder head
5
. An insertion port shoulder portion
38
and a countersunk face
39
are formed within the fuel injection valve insertion port
6
.
A metal gasket
40
is disposed between the flange
20
and the countersunk face
39
.
As shown in
FIG. 7
, both sides of the flange
20
are pressed against the cylinder head
5
by a fork
41
secured to the cylinder head
5
by a securing bolt
42
, whereby the gasket
40
is pressed against the countersunk face
39
and the seal ring
7
is compressed. As a result, one side
43
of the seal ring
7
presses against a contact surface
44
of the holder
23
and the other side
45
presses against the surface of the insertion port shoulder portion
38
, preventing the high-temperature, high-pressure combustion gas in the cylinder from leaking into the housing main body
2
by means of a so-called “double seal construction”.
Next, the operation of a fuel injection valve
1
of the above construction will be explained.
When an electric current is supplied to the coil
24
of the solenoid assembly
4
from outside through the terminals
29
, a magnetic flux is generated in the magnetic passage formed by the movable armature
16
, the core
26
, and the housing main body
2
, whereby the movable armature
16
is attracted against the elasticity of the spring
28
towards the core
26
. Thus, the needle valve
14
, which is integrated with the movable armature
16
, is moved upwards as far as the position where the flange portion
19
of the needle valve
14
contacts the spacer
18
. The guide portion
17
is guided in the axial direction by the inner circumferential surface of the valve main body
11
as the needle valve
14
moves upwards.
As the needle valve
14
moves upwards, the tip of the needle valve
14
is separated from the valve seat
13
, forming a gap between the tip thereof and the valve seat
13
. As a result, high-pressure fuel fed from a fuel supply pipe
46
flows in through a fuel filter
8
, through a fuel passage
47
within the sleeve
27
, through the gap formed between the needle valve
14
and the valve main body
11
, through the first passages
35
in the second end surface
32
into the second passages
36
in the outer surface
34
, then the high-pressure fuel flows into the swirling grooves
37
of the first end surface
31
. The fuel forms a swirling current inside the swirling grooves
37
and is sprayed from the fuel injection aperture
12
into the cylinder (not shown).
In a fuel injection valve
1
of the above construction, the valve main body
11
is secured by a crimped portion
50
formed on the tip of the first housing
21
, but a problem is that, since the crimped portion
50
does not have a smooth, flat surface, it is not possible to prevent high-temperature, high-pressure combustion gas from leaking to the housing main body
2
even if one side
43
of the seal ring
7
is in contact therewith, requiring that a holder
23
having a smooth, flat contact surface
44
be purposely prepared and pressed fitted over the tip of the first housing
21
.
SUMMARY OF THE INVENTION
The present invention aims to solve the above problem and an object of the present invention is to provide a cylinder-injection fuel injection valve enabling manufacturing costs to be reduced by eliminating the need for the holder conventionally required as a contact surface for the seal ring, as well as facilitating the assembly process by eliminating the need to press fit the holder.
To this end, according to the present invention, there is provided a cylinder-injection fuel injection valve comprising: a housing main body; a valve assembly disposed within the housing main body and provided with: a valve main body having a large-diameter cylinder portion and a small-diameter cylinder portion; a valve seat having a fuel injection aperture secured within the tip of the valve main body; and a valve body moved into and out of contact with the valve seat to close and open said fuel injection aperture; a seal held between a cylinder head and a shoulder portion between the large-diamete
Aota Masayuki
Fukutomi Norihisa
Hosoyama Keita
Sumida Mamoru
Miller Carl S.
Mitsubishi Denki & Kabushiki Kaisha
Sughrue & Mion, PLLC
LandOfFree
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