Information
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Patent Grant
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6186122
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Patent Number
6,186,122
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Date Filed
Wednesday, June 30, 199925 years ago
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Date Issued
Tuesday, February 13, 200123 years ago
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Inventors
-
Original Assignees
-
Examiners
-
CPC
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US Classifications
Field of Search
US
- 123 468
- 123 469
- 123 470
- 123 456
- 123 472
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International Classifications
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Abstract
A fuel injector assembly comprises a fuel injector having an inlet end and an outlet end, and further having an associated fuel rail assembly. An o-ring seal is located approximately at the inlet end to prevent fluid from leaking out of the fuel injector and the fuel rail assembly. A groove in the inlet end is located above the o-ring seal, and a retainer member is constructed to be received into the groove to provide positional constraint to the o-ring seal.
Description
FIELD OF THE INVENTION
This invention relates generally to fuel injectors of the type that are used to inject liquid fuel into the induction system of an internal combustion engine, and particularly to a means for restricting movement of the o-ring on an injector.
BACKGROUND OF THE INVENTION
An objective of a fuel injector is to accurately deliver fuel to an associated engine or combustion chamber. A control valve controls the injection start and finish by controlling the intake channel of an injection pump. The control valve is provided with a valve body which is in the form of a piston valve and is provided with a valve seat, with a high pressure chamber and a low pressure chamber, respectively, being provided on the two sides of the valve seat. To deliver the predetermined correct quantity of fuel for each combustion event, it is expected that the valve will open and then close precisely.
It is desirable to restrict the movement of the top external o-ring to prevent the o-ring from falling out of the injector during later stages of injector assembly, test, packaging and shipping, as well as during engine assembly and engine servicing. In some current injectors, a retainer is molded simultaneously with the injector body mold. The retainer is used to restrict the movement of the top external o-ring in providing a static seal between the injector and the fuel rail assembly. The retainer is molded around the inlet tube at the top of the injector. Unfortunately, various problems with production mold flash have created a need for a design alternative for the retainer. Once such alternative is to use a metal retainer which is crimped after installation. However, the design and assembly processes of certain injectors types do not readily allow such crimping operation.
It is seen then that there exists a need for a retainer for a fuel injector which is flexible for installation and robust for injector application.
SUMMARY OF THE INVENTION
This need is met by the snap-lock retainer according to the present invention, wherein the retainer is injection molded as a separate component to eliminate the problem of uncontrollable mold flash.
In accordance with one embodiment of the present invention, a fuel injector assembly comprises a fuel injector having an inlet end and an outlet end, and further having an associated fuel rail assembly. An o-ring seal is located approximately at the inlet end to prevent fluid from leaking out of the fuel injector and the fuel rail assembly. A groove in the inlet end is located above the o-ring seal, and a retainer member is constructed to be received into the groove to provide positional constraint to the o-ring seal.
The present invention also provides a method for fabricating a fuel injector assembly. First, a fuel injector body is provided, housed in a fuel injector housing, the fuel injector body having an inlet end and an outlet end. An o-ring seal is located approximately at the inlet end to prevent fluid from leaking out of the fuel injector. A mating component is formed in the inlet end of the fuel injector housing, above the o-ring seal. Finally, a retainer member is received into the mating component to provide positional constraint to the o-ring seal.
For a full understanding of the nature and objects of the present invention, reference may be had to the following detailed description taken in conjunction with the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
In the Drawings:
FIG. 1
is a longitudinal cross sectional view through a fuel injector containing the snap-lock retainer in accordance with principles of the present invention;
FIG. 2
is a cross sectional view of the snap-lock retainer mechanism of the present invention; and
FIG. 3
is an enlarged view of the snap-lock retainer of
FIG. 2
, as installed in the fuel injector of FIG.
1
.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to
FIG. 1
there is illustrated in cross section, a typical molded electrically operated fuel injector
10
. Fuel injector
10
, shown closed, has a main longitudinal axis
14
and is a top-feed type device comprising an inlet
16
and a nozzle
18
at its opposite axial ends. The passage of liquid fuel through the fuel injector between inlet
16
and nozzle
18
is controlled by the seating and unseating of the rounded tip end of a metal needle
20
on and from a valve seat
22
located just interior of nozzle
18
. Needle
20
is resiliently biased by a spring
24
to seat on seat
22
, thereby closing the passage to flow. When the valve is electrically energized by the delivery of electric energizing current to its solenoid coil
26
, the needle unseats to allow fuel flow. The fuel injector comprises a generally tubular metal housing
28
, and axially spaced apart o-rings
30
on the outside of the housing
28
provide for sealing of the fuel injector. In accordance with the present invention, movement of a top external o-ring
36
is restricted by a snap-lock retainer
38
.
The construction of the retainer member
38
is shown in greater detail in
FIGS. 2 and 3
. The snap-lock retainer is preferably injection molded as a separate component part, rather than integral with the injector body, to eliminate the currently existing problem of uncontrollable mold flash. The material of the snap-lock retainer
38
is preferably a hard plastic such as commercially available Nylon 6—6, to ensure an appropriate retention force while maintaining the structural integrity desired for installation. The retainer
38
is approximately circular and designed to be received at inlet end
16
of the fuel injector
10
.
The retainer or washer-type device
38
is used to provide the positional constraint to an o-ring seal on a multiport fuel injector. The retainer is installed by snapping onto the mating component comprised of the groove
42
formed in the inlet tube
28
. A self-locking feature prevents the retainer
38
from unintended disassembly, after installation of the retainer
38
in the groove
42
.
The snap-lock retainer
38
, shown in
FIG. 2
, achieves the snapping or gripping feature with a lead-in chamfer
40
which, during installation, forces the retainer to stretch over the inlet tube
28
. In a preferred embodiment of the present invention, the snapping feature is achieved with a 47° lead-in chamfer. During installation of the retainer
38
, when the retainer reaches groove
42
of the tube
28
, shown in
FIG. 3
, the retainer
38
will spring back to its original diameter, assuming its natural state diameter and shape.
FIG. 3
illustrates the installed position of the retainer
38
on the injector
10
of FIG.
1
. The retainer restricts movement of the top external o-ring
36
and provides a static seal between the injector
10
and the fuel rail assembly. When the retainer is molded simultaneously with the injector body, production mold flash problems can occur. The snap-lock retainer
38
of the present invention is molded as a separate component to eliminate the issue of mold flash, and subsequently installed on the injector, as shown in FIG.
3
.
Continuing with
FIGS. 2 and 3
, located at the top of chamfer
40
is a protruded step
44
. The protrusion
44
grabs or urges the retainer into the groove
42
, thereby providing the retention force required to restrict movement of the retainer
38
and also the o-ring
36
.
In accordance with the present invention, and referring to
FIGS. 1-3
, a fuel injector assembly can be fabricated for restricting movement of the o-ring
36
on the injector
10
. The fuel injector
10
body is housed in fuel injector housing
28
, and o-ring seal
36
is located approximately at the inlet end to prevent fluid from leaking out of the fuel injector. Mating component
42
is formed in the inlet end
16
of the fuel injector housing, above the o-ring seal
36
. The mating component or groove
42
receives retainer member
38
, usually by snapping the retainer member onto the groove, to provide positional constraint to the o-ring seal. In a preferred embodiment, the retainer member is molded as a separate component part, separate from the molding of the fuel injector body.
Having described the invention in detail and by reference to the preferred embodiment thereof, it will be apparent that other modifications and variations are possible without departing from the scope of the invention defined in the appended claims.
Claims
- 1. A fuel injector assembly comprising:a fuel injector having a fuel injector housing and further having an inlet end and an outlet end associated with the fuel injector housing; an o-ring seal located approximately at the inlet end to prevent fluid from leaking out of the fuel injector; a mating component comprising a groove formed in the inlet end of the fuel injector housing, between the inlet end and the o-ring seal; and a retainer member cooperatively engaging the mating component to provide positional constraint to the o-ring seal.
- 2. A fuel injector assembly as claimed in claim 1 wherein the retainer member comprises an approximately circular retainer member.
- 3. A fuel injector assembly comprising:a fuel injector having a fuel injector housing and further having an inlet end and an outlet end associated with the fuel injector housing; an o-ring seal located approximately at the inlet end to prevent fluid from leaking out of the fuel injector; a mating component formed in the inlet end of the fuel injector housing, between the inlet end and the o-ring seal; a retainer member cooperatively engaging the mating component to provide positional constraint to the o-ring seal; and a lead-in chamfer that forces the retainer member to stretch over the inlet end during installation of the retainer in the mating component.
- 4. A fuel injector assembly as claimed in claim 3 wherein the lead-in chamfer comprises a protrusion for urging the retainer member to mate with the mating component.
- 5. A method for fabricating a fuel injector assembly comprising the steps of:providing a fuel injector body housed in a fuel injector housing, the fuel injector body having an inlet end and an outlet end; locating an o-ring seal approximately at the inlet end to prevent fluid from leaking out of the fuel injector; forming a groove in the inlet end of the fuel injector housing, between the inlet end and the o-ring seal; and receiving a retainer member into the groove to provide positional constraint to the o-ring seal.
- 6. A method as claimed in claim 5 further comprising the steps of:molding the fuel injector body; molding the retainer member as a separate component part.
- 7. A method as claimed in claim 6 wherein the step of molding the retainer member comprises using a resilient material.
- 8. A method as claimed in claim 5 further comprising the step of snapping the retainer member onto the groove.
US Referenced Citations (4)