Information
-
Patent Grant
-
6601785
-
Patent Number
6,601,785
-
Date Filed
Friday, June 1, 200123 years ago
-
Date Issued
Tuesday, August 5, 200321 years ago
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Inventors
-
Original Assignees
-
Examiners
-
CPC
-
US Classifications
Field of Search
US
- 239 5851
- 239 5853
- 239 5854
- 239 5855
- 239 5331
- 239 5332
- 239 5333
- 239 5337
- 239 5339
- 239 5
- 239 600
- 239 5338
- 251 127
- 251 12915
- 251 12921
-
International Classifications
- B05B130
- F02M5100
- F02M5900
-
Abstract
A fuel injector has a fuel inlet, a fuel outlet, and a fuel passageway extending along an axis between the fuel inlet and the fuel outlet. The fuel injector comprises a body, an armature, a spring, and a spring stop. The body has an inlet portion, an outlet portion, and a passage disposed between the inlet portion and the outlet portion. The armature is disposed within the passage and is displaceable along the axis relative to the body. The spring is disposed within the passage and applies a biasing force to the armature. The spring has a first end disposed proximate the armature and a second end opposite from the first end. The spring stop is disposed within the passage and has a first and second portion. The first portion includes at least one projection engaging the passage. The at least one projection extends obliquely with respect to the axis and in a direction general toward the inlet portion.
Description
FIELD OF THE INVENTION
This invention relates in general to a fuel injector assembly, and more specifically to a fuel injector assembly having a self-locking calibration member that sets spring bias and provides a seat that allows spring alignment.
BACKGROUND OF THE INVENTION
It is believed that in a conventional fuel injector assembly, a spring is disposed between an end of an adjustment tube and an armature. To allow fuel to flow through the injector, the adjustment tube is usually hollow. It is known to use an adjustment tube to initially set, i.e., calibrate, the dynamic flow of a conventional fuel injector assembly by either altering the amount of metal in the magnetic circuit or by adjusting the spring preload. In the fuel injector industry, adjusting the spring preload is the most common calibration method.
Two types of adjustment tubes are known for adjusting the spring preload: an interference fit adjustment tube and a free sliding adjustment tube. An interference fit adjustment tube requires a large force to position the adjustment tube with respect to its mating part and is considered fixed when the tooling no longer applies the force needed to move the adjustment tube. Interference-type adjustment tubes can be continuous tubes or axially slit tubes, which are commonly referred to as “roll pins.” A roll pin allows the mating hole size to vary significantly, and moving the roll pin requires less force than moving the continuous tube. However, under severe conditions, the roll pin may be displaced, thus altering the previously calibrated dynamic flow of the fuel injector. The continuous tube is less susceptible to unanticipated displacement due to its higher engagement force, but does require precision machining.
Conventional interference-type adjustment tubes have several disadvantages. One disadvantage is that moving the adjustment tube to calibrate a fuel injector requires a relatively large force. Although moving a roll pin requires less force than moving a continuous tube, a roll pin has the disadvantage of being susceptible to displacement under severe conditions. While a continuous tube is less likely to be displaced than a roll pin because of its higher engagement force, a disadvantage of the continuous pin is that it requires precise machining.
In contrast to interference-type adjustment tubes, a free sliding adjustment tube slides freely with respect to its mating part such that spring preload adjustments can be made quickly. Once the desired spring preload is achieved, the adjustment tube is fixed in position by a staking process with respect to the mating part.
SUMMARY OF THE INVENTION
The present invention provides a fuel injector. The fuel injector has a fuel inlet, a fuel outlet, and a fuel passageway extending along an axis between the fuel inlet and the fuel outlet. The fuel injector comprises a body, an armature, a spring, and a spring stop. The body has an inlet portion, an outlet portion, and a passage disposed between the inlet portion and the outlet portion. The armature is disposed within the passage and is displaceable along the axis relative to the body. The spring is disposed within the passage and applies a biasing force to the armature. The spring has a first end disposed proximate the armature and a second end opposite from the first end. The spring stop is disposed within the passage and has a first and second portion. The first portion includes at least one projection engaging the passage. The at least one projection extends obliquely with respect to the axis and in a direction general toward the inlet portion.
The present invention also provides a method of assembling a fuel injector. The fuel injector has a fuel inlet, a fuel outlet, a fuel passageway extending along an axis between the fuel inlet and the fuel outlet. The fuel injector includes an armature and a body that has an inlet portion, an outlet portion, and a passage extending between the inlet portion and the outlet portion. The method comprises disposing within the passage the armature displaceable along the axis relative to the body, disposing within the passage a spring applying a biasing force to the armature, maintaining a seat in a first configuration adapted for applying a first pressure on the passage, positioning the seat in the first configuration at a location along the axis with respect to the body for applying the biasing force, and releasing the seat to a second configuration adapted for applying a second pressure on the passage. The spring has a first end disposed proximate the armature and a second end opposite from the first end. And the second pressure is greater than the first pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention.
FIG. 1
is a cross-sectional view of a fuel injector assembly according to a first embodiment.
FIG. 2
is a cross-sectional view of the fuel injector assembly according to a first embodiment.
FIG. 2A
is a perspective view of the spring stop shown in FIG.
2
.
FIG. 3
is a cross-sectional view, which is similar to
FIG. 2
, of a portion of a fuel injector assembly according to a second embodiment.
FIG. 3A
is a perspective view of the spring stop shown in FIG.
3
.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to
FIGS. 1
,
2
, and
2
A, a fuel injector assembly
1
has a fuel inlet
12
, a fuel outlet
14
, and a fuel passageway
16
extending from the fuel inlet
12
to the fuel outlet
14
along a longitudinal axis
18
. The fuel injector assembly
1
also includes an overmolded plastic member
20
cincturing a metallic support member
22
.
A fuel inlet member
24
with an inlet passage
26
is disposed within the overmolded plastic member
20
. The inlet passage
26
serves as part of the fuel passageway
16
of the fuel injector assembly
1
. A fuel filter (not shown) and an armature bias spring
32
are provided in the inlet passage
26
. The armature bias spring
32
can be a coil spring. In combination with other factors, the length of the spring
32
, and hence the bias force of the spring
32
, affect the quantity of fuel flow through the injector. The overmolded plastic member
20
also supports a socket
20
a
that receives a plug (not shown) to operatively connect the fuel injector assembly
1
to an external source of electrical potential, such as an electronic control unit (not shown). An elastomeric O-ring
34
is provided in a groove on an exterior of the inlet member
24
. The O-ring
34
is supported by a backing ring
38
to sealingly secure the inlet member
24
to a fuel supply member (not shown), such as a fuel rail.
The metallic support member
22
encloses a coil assembly
40
. The coil assembly
40
includes a bobbin
42
that retains a coil
44
. The ends of the coil assembly
40
are electrically connected to pins
40
a
mounted within the socket
20
a
of the overmolded plastic member
20
. An armature
46
is supported for relative movement along the axis
18
with respect to the inlet member
24
. The armature
46
can be supported by an armature guide eyelet
56
that is located on an inlet portion
60
of a valve body
52
for relative axial sliding movement with respect to the valve body
52
. A non-magnetic sleeve
48
positions the coil assembly
40
with respect to the valve body
52
and a shell
50
provides a magnetic path between the metallic support member
22
and the valve body
52
. The armature
46
has an armature passage
54
in fluid communication with the inlet passage
26
.
An axially extending body passage
58
connects the inlet portion
60
of the body
52
with an outlet portion
62
of the body
52
. The armature passage
54
of the armature
46
is in fluid communication with the body passage
58
of the body
52
. A seat
64
is mounted at the outlet portion
62
of the body
52
.
The body
52
includes a neck portion
66
that extends between the inlet portion
60
and the outlet portion
62
. The neck portion
66
can be an annulus that surrounds a substantially cylindrical needle
68
. The needle
68
is operatively connected to the armature
46
, and is centrally located within and spaced from the neck portion
66
so as to define a part of the body passage
58
. The cylindrical needle
68
is substantially axially aligned with the longitudinal axis
18
of the fuel injector assembly
1
.
The fuel injector assembly
1
operates by magnetically coupling the armature
46
to the end of the inlet member
26
that is closest to the inlet portion
60
of the body
52
. Thus, the lower portion of the inlet member
26
that is proximate to the armature
46
serves as part of the magnetic circuit formed with the armature
46
and coil assembly
40
. The armature
46
is guided by the armature guide eyelet
56
and is responsive to an electromagnetic force generated by the coil assembly
40
for axially reciprocating the armature
46
along the longitudinal axis
18
of the fuel injector assembly
1
. The electromagnetic force is generated by current flow from the electronic control unit (not shown) through the coil assembly
40
. Movement of the armature
46
also moves the operatively attached needle
68
to positions that are either separated from or contiguously engaged with the seat
64
. This opens or closes, respectively, the seat passage
70
of the seat
64
, which permits or prevents, respectively, fuel from flowing through the fuel outlet
14
of the fuel injector assembly
1
. The needle
68
includes a curved surface
74
for contiguously engaging with a conical portion
72
of the seat passage
70
.
Fuel that is to be injected into a combustion chamber (not shown) by the fuel injector assembly
1
is communicated from the fuel inlet source (not shown), to the fuel inlet
12
, through the fuel passageway
16
, and exits from the fuel outlet
14
. The fuel passageway
16
includes the inlet passage
26
of the inlet member
24
, the armature passage
54
of the armature
46
, the body passage
58
of the body
52
, and the seat passage
70
of the seat
64
.
In order to ease the assembly of a fuel injector, it is desirable to minimize the force required to position the adjustment member while calibrating the fuel injector. Further, it is desirable to lock the adjustment member following calibration, without requiring a precisely machined adjustment member.
Referring to
FIGS. 2 and 2A
, a first preferred embodiment of an adjustment member includes a spring stop
320
disposed within the inlet passage
26
and adjacent to the spring
32
. The adjustment member
320
is positionable along the axis
18
, thereby varying the length of the spring
32
. The spring stop
320
includes a flared end
322
and a seat
324
that slidably engages the first end of the spring
32
and can include a projection
326
. The length of the spring stop
320
is significantly less than the length of the inlet member
24
in the fuel injector assembly
1
. The spring stop
320
can have an axial slit (not shown).
During installation, an installation tool (not shown) is placed through the spring stop
320
. The installation tool has a shoulder proximate the inner diameter of the flared end
322
compressing the outer diameter of the flared end
322
thus permitting the spring stop
320
to slide substantially freely along the axis
18
.
When the installation tool is released, the flared end
322
will return substantially to its original diameter and exert a pressure on the inlet passage
26
for locking the spring stop
320
substantially proximate the location along the axis
18
at which the installation tool was released. The inlet passage
26
can have a knurled or threaded surface
328
frictionally engaging the flared end
322
thus providing additional locking force.
The seat
324
has a generally concave surface. The projection
326
aligns the first end of the spring
32
substantially along the axis
18
. The projection
326
can be tapered such that only inactive coils of the spring
32
are engaged. The seat
324
and the projection
326
can be annular, thereby permitting fluid communication through the seat
324
.
Referring now to
FIGS. 3 and 3A
, a second preferred embodiment of an adjustment member includes a spring stop
420
disposed within the inlet passage
26
and adjacent to the spring
32
. The spring stop
420
is positionable along the axis
18
, thereby varying the length of the spring
32
. The spring stop
420
includes a flared end
422
, a groove
424
, a body
426
, and a seat
428
that slidably engages the first end of the spring
32
and can include a projection
430
. The length of the spring stop
420
is significantly less than the length of the adjustment tube
30
in the fuel injector assembly
1
. The spring stop
420
can have an axial slit
421
.
During installation, an installation tool (not shown) attaches to the spring stop
420
proximate the inner diameter of the flared end
422
compressing the outer diameter of the flared end
422
thus permitting the spring stop
420
to slide substantially freely along the axis
18
. As the spring stop
420
slides along the axis
18
, material at the interface of the inlet passage
26
and the spring stop
420
that becomes free will be retained within the groove
424
.
When the installation tool is released, the flared end
422
will return substantially to its original diameter and exert a pressure on the inlet passage
26
locking the spring stop
420
substantially proximate the location along the axis
18
at which the installation tool was released. The inlet passage
26
can have a knurled or threaded surface
432
frictionally engaging the flared end
422
thus providing additional locking force.
The seat
428
has a generally concave surface. The projection
430
aligns the first end of the spring
32
substantially along the axis
18
. The projection
430
can be tapered such that only inactive coils of the spring
32
are engaged. The seat
428
and the projection
430
can be annular, thereby permitting fluid communication through the seat
428
.
While the present invention has been disclosed with reference to certain preferred embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims, and equivalents thereof.
Claims
- 1. A fuel injector having a fuel inlet, a fuel outlet, and a fuel passageway extending along an axis between the fuel inlet and the fuel outlet, the fuel injector comprising:a body having an inlet portion, an outlet portion, and a passage disposed between the inlet portion and the outlet portion; an armature disposed within the passage and displaceable along the axis relative to the body; a spring disposed within the passage and applying a biasing force to the armature, the spring having a first end disposed proximate the armature and a second end opposite from the first end, the spring having an outside diameter; and a spring stop disposed within the passage and having a first and second portion, the first portion including at least one projection engaging the passage, the at least one projection extending obliquely with respect to the axis and in a direction generally toward the inlet portion, the spring stop having an open cross-sectional area that permits fuel flow therethrough, the open cross-sectional area defining a distance transverse to and coincident to the axis, the transverse distance being greater than the outside diameter of the spring.
- 2. The fuel injector according to claim 1, wherein the passage comprises a knurled surface frictionally engaging the second portion.
- 3. The fuel injector according to claim 1, wherein the passage comprises screw threads threadably engaging the second portion.
- 4. The fuel injector according to claim 1, wherein the spring stop comprises an axial slit.
- 5. The fuel injector according to claim 1, wherein the spring stop comprises a length no greater than 20 percent of a length of the body.
- 6. The fuel injector according to claim 1, wherein the spring comprises a coil spring.
- 7. The fuel injector according to claim 1, wherein the spring comprises a seat, the spring and seat are substantially aligned along the axis.
- 8. The fuel injector according to claim 1, wherein the seat is annular so as to permit fluid communication through the seat.
- 9. A fuel injector having a fuel inlet, a fuel outlet, and a fuel passageway extending along an axis between the fuel inlet and the fuel outlet, the fuel injector comprising:a body having an inlet portion, an outlet portion, and a passage disposed between the inlet portion and the outlet portion; an armature disposed within the passage and displaceable along the axis relative to the body; a spring disposed within the passage and applying a biasing force to the armature, the spring having a first end disposed proximate the armature and a second end opposite from the first end; and a spring stop disposed within the passage and having a first and second portion, the first portion including at least one projection engaging the passage, the at least one projection extending obliquely with respect to the axis and in a direction generally toward the inlet portion, wherein the second portion comprises a seat slidably engaging one of the first and second ends.
- 10. The fuel injector according to claim 9, wherein the second portion comprises an axially extending body slidably engaging the passage.
- 11. A fuel injector having a fuel inlet, a fuel outlet, and a fuel passageway extending along an axis between the fuel inlet and the fuel outlet, the fuel injector comprising:a body having an inlet portion, an outlet portion, and a passage disposed between the inlet portion and the outlet portion; an armature disposed within the passage and displaceable along the axis relative to the body; a spring disposed within the passage and applying a biasing force to the armature, the spring having a first end disposed proximate the armature and a second end opposite from the first end, the spring comprising a coil spring; and a spring stop disposed within the passage and having a first and second portion, the first portion including at least one projection engaging the passage, the at least one projection extending obliquely with respect to the axis and in a direction generally toward the inlet portion, wherein the seat further comprises a projection slidably engaging the first one of the first and second ends, the projection extending within the coil spring.
- 12. The fuel injector according to claim 11, wherein the projection tapers inwardly as the projection extends from the seat.
- 13. A method of assembling a fuel injector having a fuel inlet, a fuel outlet, a fuel passageway extending along an axis between the fuel inlet and the fuel outlet, a body having an inlet portion, an outlet portion, a passage extending between the inlet portion and the outlet portion, and an armature, the method comprising:disposing within the passage the armature displaceable along the axis relative to the body; disposing within the passage a spring applying a biasing force to the armature, the spring having a first end disposed proximate the armature and a second end opposite from the first end; maintaining a seat in a first configuration adapted for applying a first pressure on the passage; positioning the seat in the first configuration at a location along the axis with respect to the body for applying the biasing force; and releasing the seat to a second configuration adapted for applying a second pressure on the passage, the second pressure being greater than the first pressure.
- 14. A fuel injector having a fuel inlet, a fuel outlet, and a fuel passageway extending along an axis between the fuel inlet and the fuel outlet, the fuel injector comprising:a body having an inlet portion, an outlet portion, and a passage disposed between the inlet portion and the outlet portion, the passage extending therethrough; an armature disposed within the passage and displaceable along the axis relative to the body; a spring disposed within the passage and applying a biasing force to the armature, the spring having a first end disposed proximate the armature and a second end opposite from the first end; and a spring stop disposed within the passage and having a first and second portion, the first portion including at least one projection engaging the passage, the at least one projection extending obliquely with respect to the axis and in a direction generally toward the inlet portion, the projection including a free end, the free end defining a diameter transverse and coincident to the axis, the diameter being greater, prior to installation of the spring stop in the passage, than an engagement diameter at a location along the axis in the passage where the free end engages the passage, and when installed in the passage, a diameter less than the engagement diameter of the passage.
US Referenced Citations (11)