Information
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Patent Grant
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6168098
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Patent Number
6,168,098
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Date Filed
Wednesday, June 9, 199925 years ago
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Date Issued
Tuesday, January 2, 200123 years ago
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Inventors
-
Original Assignees
-
Examiners
-
CPC
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US Classifications
Field of Search
US
- 239 583
- 251 12921
- 251 127
- 251 318
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International Classifications
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Abstract
A solenoid actuated fuel injector comprises a valve body having a longitudinal axis. A valve seat subassembly is mounted in one end of the valve body. The valve seat subassembly includes a valve seat having a seating surface and a circumferential sealing surface surrounding the seating surface. The valve seat subassembly also includes a lower needle guide and swirl disk welded to the valve seat. The lower guide includes a flange portion and a tube portion having an axially disposed tubular bore for guiding the needle in a tight tolerance relationship. The tubular bore provides a longer length interface with the needle and a smoother wear surface than a conventional pierced hole thin lower guide.
Description
FIELD OF THE INVENTION
This invention relates to needle type solenoid operated fuel injectors for controlling the injection of fuel into an internal combustion engine and more particularly to a fuel injector for direct injection of fuel into the engine.
BACKGROUND OF THE INVENTION
It is known in the fuel injection art to utilize a needle within a solenoid operated fuel injector to close a fuel passageway in a valve seat. In such injectors, a pierced hole thin lower guide aligns and supports the needle during movement. The pierced hole typically has a breakout which leaves a very small (thin) guide surface. Also, the needle has occasion to wear due to the sharp thin punched hole. This wear reduces alignment, allows fuel flow around the needle and may, initiate or contribute to fuel leakage. Misalignment results in the needle striking the cone of the sealing surface and sliding along the cone edge before being guided into the seal position and closing the flow port. Friction between the needle and the cone delays closing and disrupts the uniform spray pattern prior to complete shut off. A similar delay in developing a uniform spray pattern occurs as the needle is lifted out of the seal position.
SUMMARY OF THE INVENTION
The present invention provides a solenoid actuated fuel injector having improved axial alignment of a needle with a valve seat, reducing initial and long term leakage, resulting in improved manufacturing yield and extended life durability.
According to the invention, the solenoid actuated fuel injector comprises a valve body having a longitudinal axis. A valve seat subassembly is mounted in one end of the valve body. The valve seat subassembly includes a valve seat having a seating surface and a circumferential sealing surface surrounding the seating surface. The sealing and seating surfaces face the interior of the valve body. The seating surface includes a fuel outlet opening centered on the axis and in communication with means for conducting pressurized fuel into the valve body against the seating surface.
A needle having an end is moveable between a seated position, wherein the end is urged against the seating surface to close the outlet opening against fuel flow, and an open position, wherein the end is spaced from the seating surface to allow fuel flow through the outlet opening. Biasing means in the valve body is provided for biasing the needle toward the seated position.
The valve seat subassembly also includes a lover needle guide. The lower needle guide includes a flange portion and a tube portion having an axially disposed tubular bore for guiding the needle. The tubular bore provides a longer length interface with the needle and a smoother wear surface than a conventional pierced hole thin lower guide.
The lower guide also includes a plurality of fuel flow holes in the flange spaced around the tubular bore. The tube portion extends from the flange toward the inside of the valve body.
In an exemplary embodiment, a swirl disk is sandwiched between the valve seat sealing surface and the lower guide flange. The swirl disk receives fuel from the plurality of fuel flow holes in the lower guide flange and distributes the fuel to the valve seat fuel outlet opening.
The valve seat subassembly can be assembled on a weld guide that aligns the valve seat, swirl disk, and lower guide against a shoulder in the end of the valve body, and the nose of the valve body is crimped to hold the seat subassembly in the valve body and the valve seat is laser welded in the end of the valve body mounting the subassembly therein.
These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1
is a sectional view of a solenoid actuated fuel injector constructed in accordance with the present invention;
FIG. 2
is a sectional view of a valve body assembly of the fuel injector of
FIG. 1
illustrating a valve seat subassembly mounted at one end of the valve body;
FIG. 3
is an enlarged sectional view of the valve seat subassembly illustrating the assembly of a valve seat, swirl disk and lower needle guide; and
FIG. 4
is an exploded perspective view of the valve seat subassembly illustrating sealing and seating surfaces and a fuel outlet opening, the lower guide having a tubular bore and annular apertures and the swirl disk having a plurality of flow passages.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings in detail, numeral
10
generally indicates a solenoid actuated fuel injector of the top feed type for use with an internal combustion engine. The fuel injector
10
includes a housing
12
having a longitudinal axis A and a valve body
14
fixed to the housing. The valve body
14
has a cylindrical sidewall
16
coaxial with the longitudinal axis A that laterally bounds the interior of the valve body
14
.
A valve seat subassembly
20
mounted on one end, or nose,
22
of the valve body
14
includes a valve seat
24
having a seating surface
26
and a sealing surface
27
surrounding the seating surface and a peripheral sidewall
28
having a tapered end
29
. The seating and sealing surfaces
26
,
27
face the interior of the valve body
14
. The seating surface
26
is of a frustoconical or concave shape and includes a fuel outlet opening
30
centered on the axis A and is in communication with an inlet connector or fuel tube
32
for conducting pressurized fuel into the valve body
14
against the seating surface
26
.
Fuel tube
32
includes a mounting end
34
for mounting the injector in a fuel rail (not shown) as is known. An O-ring
36
is used to seal the mounting end
34
in the fuel rail.
An elongated needle
38
having an end
40
, of an arcuate or tapered shape, is disposed along the axis A and movable between a seated position, wherein the end is urged against the seating surface
26
to close the outlet opening against fuel flow, and an open position wherein the end is spaced from the seating surface to allow fuel flow through the outlet opening
30
. A spring
42
is provided in valve body
14
for biasing the end
40
toward the seated position.
The valve seat subassembly
20
also includes a lower needle guide
44
of a diameter smaller than the diameter of the valve seat
24
having an axially disposed tubular bore
46
for guiding the needle
38
. In the illustrated embodiment, lower needle guide
44
includes a flange portion
47
and a tube portion
48
which includes the tubular bore
46
. The tubular bore
46
has a length at least 1.5 times the diameter of the needle and preferably is in the range of 1.5 to 2.0 times the diameter of the needle.
Tubular bore
46
offers a long length interface with the needle
38
and a smooth wear surface. The internal diameter of the tubular bore
46
is controlled to a tight tolerance in relation to the precision ground needle
38
diameter. The increased contact length of the needle
38
and bore
46
combined with the tight tolerance relationship provides improved axial alignment which places the end
40
precisely in the cone of the seating surface
26
. This alignment reduces leakage vis-a-vis conventional injectors, allows a desired spray pattern to develop quickly and allows the injector to be closed quickly.
Lower needle guide
44
also includes a plurality of apertures
49
annularly disposed for communicating fuel through the guide.
Preferably valve seat subassembly
20
also includes a swirl disk
50
of a diameter smaller than the diameter of the valve seat
24
and sandwiched between the valve seat sealing surface
27
and the lower guide
44
. The valve seat subassembly
20
, which includes the valve seat
24
, lower guide
44
and swirl disk
50
, may have its components laser welded together before assembly into the pocket
51
in the end
22
of the valve body
14
.
Swirl disk
50
includes a like plurality of flow passages
52
in communication with the plurality of apertures
49
in lower guide
44
for communicating fuel toward fuel outlet opening
30
. The thickness of the flange portion
47
of the lower needle guide
44
is at least as thick as the swirl disk
50
and generally in the range of 1.0 to 2.0 times the thickness of the swirl disk.
An armature
54
connected to needle
38
is ax ally movable in the valve body
14
. A solenoid coil
56
is operable to draw the armature
54
away from the valve seat subassembly
20
, thereby moving the needle end
40
off the seating surface
26
, and allowing fuel to pass through the fuel outlet opening
30
.
The valve seat subassembly
20
is assembled in the valve body
14
as follows. The lower guide
44
, swirl disk
50
and valve seat
24
are stacked in the pocket
51
against shoulder
57
in the end
22
of the valve body
14
. The nose
22
of the valve body is crimped to hold the subassembly therein. The seat
24
is laser welded around its tapered end
29
to fasten the seat subassembly
20
in the end
22
of the valve body
14
.
Although the invention has been described by reference to a specific embodiment, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiment, but that it have the full scope defined by the language of the following claims.
REFERENCE NUMERALS
10
. fuel injector
12
. housing
14
. valve body
16
. sidewall
18
.
20
. valve seat subassy
22
. end (nose)
24
. valve seat
26
. seating surface
27
. sealing surface
28
. circum. sidewall
29
. tapered end
30
. fuel outlet opening
32
. inlet connector/fuel tube
34
. mounting end
36
. O-ring
38
. elongated needle
40
. distal end
42
. spring
44
. lower guide
46
. tubular bore
47
. flange portion
48
. tube portion
49
. apertures
50
. swirl disk
51
. pocket
52
. flow passages
54
. armature
56
. solenoid coil
57
. shoulder
58
. guide pin
60
. guide pin
62
. weld fixture
64
. interior wall
66
.
68
.
70
.
72
.
74
.
76
.
78
.
80
.
82
.
84
.
86
.
88
.
90
.
92
.
94
.
96
.
98
.
Claims
- 1. A solenoid actuated fuel injector for use with an internal combustion engine comprising:a valve body having a longitudinal axis; said valve body having an end for mounting a valve seat subassembly; said end including a pocket and a shoulder therein; a valve seat subassembly mounted on one end of said valve body; said valve seat subassembly including a valve seat having a seating surface and an annular sealing surface surrounding said seating surface and facing an interior of said valve body; said seating surface including a fuel outlet opening centered on said axis and in communication with means for conducting pressurized fuel into said valve body against said seating surface; a needle having a distal end movable between a seated position, wherein the distal end is urged against said seating surface to close the outlet opening and stop fuel flow, and an open position, wherein said distal end is spaced from said seating surface to allow fuel flow through said outlet opening; and biasing means in said valve body and biasing said needle distal end against said seating surface; said valve seat subassembly also including a lower needle guide having a flange portion and a tube portion; said tube portion including an axially disposed tubular bore for guiding said needle in a tight tolerance relationship; said flange portion having a plurality of apertures annularly disposed for communicating fuel through said lower guide.
- 2. A solenoid actuated fuel injector for use with an internal combustion engine comprising:a valve body having a longitudinal axis; said valve body having an end for mounting a valve seat subassembly; said end including a pocket and a shoulder therein; a valve seat subassembly mounted on one end of said valve body; said valve seat subassembly including a valve seat having a seating surface and an annular sealing surface surrounding said seating surface and facing an interior of said valve body; said seating surface including a fuel outlet opening centered on said axis and in communication with means for conducting pressurized fuel into said valve body against said seating surface; a needle having an axial diameter and a distal end movable between a seated position, wherein the distal end is urged against said seating surface to close the cutlet opening and stop fuel flow, and an open position, wherein said distal end is spaced from said seating surface to allow fuel flow through said outlet opening; and biasing means in said valve body and biasing said needle distal end against said seating surface; said valve seat subassembly also including a lower needle guide having a flange portion and a tube portion; said tube portion including an axially disposed tubular bore for guiding said needle in a tight tolerance relationship, said tubular bore having a length greater than 1.5 times the diameter of said needle; and said flange portion having a plurality of apertures annularly disposed for communicating fuel through said lower guide.
- 3. The fuel injector of claim 2 wherein said valve seat subassembly further includes a swirl disk sandwiched between said valve seat sealing surface and said lower guide flange portion;said swirl disk including a plurality of flow passages in communication with said apertures in said flange portion for communicating fuel toward said fuel outlet opening.
- 4. The fuel injector of claim 3 wherein said needle guide flange portion has a thickness at least as thick as said swirl disk.
- 5. The fuel injector of claim 3 wherein said tube portion has a length 1.5 to 2.0 times the diameter of said needle.
- 6. The fuel injector of claim 1 wherein said valve seat has a peripheral sidewall having a tapered end spaced from said seating surface.
- 7. The fuel injector of claim 1 wherein said valve seat subassembly includes a laser weld connecting said valve seat and said lower guide.
US Referenced Citations (8)