Information
-
Patent Grant
-
6328232
-
Patent Number
6,328,232
-
Date Filed
Wednesday, January 19, 200024 years ago
-
Date Issued
Tuesday, December 11, 200122 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Scherbel; David A.
- Evans; Robin O.
Agents
-
CPC
-
US Classifications
Field of Search
US
- 239 575
- 239 5332
- 239 5333
- 239 5334
- 239 5336
- 239 5337
- 239 5339
- 239 53311
- 239 53312
- 239 5851
- 239 5852
- 239 5853
- 239 5854
- 239 5855
- 239 DIG 23
- 239 584
- 251 12921
-
International Classifications
-
Abstract
An engine fuel injector (10) having a fuel inlet tube (12) and a biasing spring (56) loading a solenoid actuated injection valve (50) within the injector (10) is provided with a calibration assembly (58) combining the calibration member (74) or tube with an internally mounted fuel inlet filter (76). The calibration member (74) may include a body (78) with an enlarged end (88) that is interference fitted within the fuel inlet tube (12) and an opposite stepped in end (80) forming a seat (82) which is engaged by the biasing spring (56). The fuel filter (76) has an enlarged annular base (92) fixed within the enlarged end (88) of the calibration member (74) and having an associated filter screen (98) or element through which fuel passing through the calibration member is filtered for passage through the injector (10). The filter screen (98) may extend completely within the calibration member (74), or alternatively, can project outward from the enlarged end (86) of the calibration member (74) into the inlet end (86) of the fuel inlet tube (12). Advantages in the ease of calibration, reduced assembly costs and improved filtration of fuel are provided.
Description
TECHNICAL FIELD
This invention relates to engine fuel injectors, particularly of the solenoid actuated top feed type, and more particularly to an injector having an inlet fuel filter mounted within a frictionally retained valve spring calibration tube.
BACKGROUND OF THE INVENTION
It is known in the art to provide an engine top feed fuel injector with a fuel inlet filter mounted within the fuel inlet tube. It is further known to provide a calibration tube which is slidable within the inlet tube for adjusting the force on a solenoid actuated fuel inlet valve and to propose a fuel filter mounted on the outer end of the calibration tube.
In this proposal, the calibration tube is adjusted by a tool which engages the closed outer end of the filter and forces it down with the tube until the desired valve spring force is achieved. The calibration tube is then fixed to the inlet tube by any suitable means to hold the calibration tube in place. The friction force of the tube by itself is inadequate to maintain the set calibration tube position since adjustment of the tube by applying a force to the filter body requires that the sliding force of the calibration tube be limited to an amount which the plastic body of the filter is able to withstand, preferably not more than about two pounds. Also, the low force sliding fit of the calibration tube in the fuel inlet tube allows fuel carrying contaminant particles up to 100 microns in diameter to bypass the filter by passing through clearance spaces between the tubes. It is accordingly desired to provide a calibration tube mounted inlet filter which overcomes the problems of the prior art.
SUMMARY OF THE INVENTION
The present invention provides a fuel injector having a fuel tube at the inlet end and an injection valve at the discharge end of the injector, the valve including a valve element reciprocable against and away from a valve seat. A biasing spring operatively engages the valve element, optionally through a solenoid-actuated armature, and a calibration member or tube is adjustable within the injector to establish a set force of the valve biasing spring.
A fuel filter is mounted within the calibration member, preferably in a manner to allow direct engagement of a calibration tool with the outer end of the calibration member for adjusting the spring force. The fuel filter is preferably mounted in the calibration tube with an interference fit that is adequate to maintain the set position by friction between the members without requiring an additional securing step. Optionally, the calibrating tool may engage a base or mounting portion of the filter body snap fitted or otherwise mounted in a calibration tube. In any case, a force adequate to provide the desired interference fit may be applied to the calibration tube without passing through the complete filter body. Preferably, the interference fit is also sufficient to prevent the bypassing of fuel past the calibration tube and around the filter so as to prevent particles larger than the filter is designed to remove from remaining in the fuel stream. Thus, the filter and the interference fit may be selected to capture particles greater than about 30 microns in diameter.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1
is a cross-sectional view through an engine fuel injector of the top feed type shown as mounted within an engine cylinder head and connected within the cup of an engine fuel supply system;
FIG. 2
is a cross-sectional view of a preferred embodiment of valve spring calibration tube having an internally mounted fuel filter according to the invention, as shown in
FIG. 1
;
FIG. 3
, is a cross-sectional view of an alternative embodiment of calibration tube with an internally mounted fuel filter wherein the body of the filter extends out through the inlet end of the calibration tube;
FIG. 4
is still another embodiment of calibration tube with an internally mounted fuel filter, wherein the filter body is insert molded within the tube and the body also extends out through the inlet end of the calibration tube; and
FIG. 5
is a cross-sectional view of yet another embodiment of calibration tube with an internally mounted filter, wherein the filter body has a base that is snap fitted into the inlet of the tube and the body extends outward from the inlet end of the tube which is shown as mounted within an injector assembly.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to
FIG. 1
of the drawings in detail, numeral
10
generally indicates a solenoid actuated fuel injector which is similar to that disclosed in copending U.S. patent application Ser. No. 09/320,501, filed May 26, 1999, but includes modifications in accordance with the present invention.
Injector
10
includes a continuous fuel tube
12
which is centered on a central axis
14
and encloses a continuous fuel passage
15
through the injector from an inlet end
16
of the tube to a discharge end
18
. Preferably, the fuel tube
12
has no openings except at the inlet and outlet ends and defines a continuous imperforate passage in which fuel is conducted and kept separate from all the components of the injector that are mounted externally of the fuel tube. These include a coil assembly
20
having a solenoid coil
22
extending around and closely adjacent to the fuel tube
12
. A magnetic coil body or strap
24
surrounds the coil
22
and has upper and lower portions
26
,
28
fixed to the outer surface of the tube
12
.
A support member or cover
30
is formed as a two-piece tubular member that is assembled over the tube and surrounds the body
24
. The cover includes a slot
32
for receiving a retainer clip, not shown, that holds the injector inlet end within a cup
34
of an associated fuel rail, not shown. The cover also provides a backup surface for constraining a seal ring
36
of a conventional O-ring type. A push-on seal retainer
38
is frictionally or otherwise retained on the inlet end
16
of the fuel tube
12
to form with the other parts an annular groove in which the seal ring
36
is retained. A lower end of the cover
30
also backs up an O-ring seal
40
retained by a lower seal retainer
42
on an expanded diameter portion
44
at the lower end of the fuel tube
12
.
Within the fuel tube
12
, a tubular magnetic pole
46
is fixed in engagement with the interior surface of the fuel tube
12
. The pole
46
extends from adjacent the upper end
26
of the magnetic body
24
to a position within the axial extent of the coil
22
. An injection valve
50
is reciprocable within the tube
12
and includes a ball end
52
connected with a hollow armature
54
that slides within the tube
12
. A biasing spring
56
engages an upper end of the armature
54
and is compressed with a predetermined force by a calibration assembly
58
best shown in FIG.
2
and to be subsequently further described.
Within the expanded portion
44
of the fuel tube
12
, a valve seat
60
and a lower guide
62
are retained by crimped over portions of the tube outlet end
18
which engage a seat washer
64
. The lower guide
62
is a disc which guides the ball end
52
of the injection valve and includes openings
66
that allow fuel flow through the guide to a conical surface
68
of the valve seat against which the ball end
52
seats in the valve closed position. A central discharge opening of the valve seat
60
connects with a multi-hole spray director
70
held in a recess of the valve seat by a retainer
72
.
To properly control the speed and efficiency of valve action in the injector, it is important that the valve stroke be set a desired predetermined value. This may be accomplished by providing for adjusting the position of the valve seat. However, in the present embodiment, the valve stroke is preferably set by making the magnetic pole
46
axially adjustable within the fuel tube
12
to establish the desired clearance between the pole
46
and the valve armature
54
in the valve closed position. This is done by sliding the pole inside the tube to obtain the proper clearance, after which the pole may be fixed within the tube by the friction developed from an interference fit or by crimping or otherwise securing the tube to the pole in the adjusted position.
In accordance with the invention, the calibration assembly
58
shown in
FIGS. 1 and 2
is substantially modified from the generally straight calibration tube disclosed in the previously mentioned U.S. patent application Ser. No. 09/320,501 and which is known in injectors of this type. In the present invention, the calibration tube and separately mounted filter of the previously mentioned U.S. patent application Ser. No. 09/320,501 are replaced by the calibration assembly
58
which includes a preferably metal calibration tube or member
74
in which a fuel intake filter
76
is mounted. The calibration member
74
includes a generally tubular body
78
sized to be telescopically received within the magnetic pole
46
of the injector. At its lower end
80
, body
78
is stepped into a smaller diameter forming an annular seat
82
against which the biasing valve spring
56
is seated and an annular extending spring guide
84
which extends into spring
56
for guiding the upper end thereof.
At its upper end
86
, the calibration member body
78
has a diametrically enlarged or expanded portion
88
which is sized to be an interference fit within the injector fuel tube
12
where it is received toward the inlet end of the injector. Fuel filter
76
includes a plastic frame
90
having an enlarged annular base
92
connected by two or more longitudinal ribs
94
with a solid cap
96
, forming a plurality of spaced windows through which fuel may pass. A tubular filter screen
98
is molded into the plastic frame
90
and extends between the base
92
and cap
96
alongside the ribs
94
. The screen
98
covers all the windows and requires fuel passing therethrough to pass through the filter screen to screen out solid particles of a desired size. In the present instance, particles carried in the fuel that are greater than 30 microns are separated out by the filter screen
98
.
In this preferred embodiment, the filter
76
has its base
92
fitted tightly within the enlarged portion
88
of the calibration member body
78
, the upper end
86
of which is crimped or rolled over at
100
to mount the filter tightly within the calibration member
74
. The filter is mounted so that the filter screen
98
and end cap
96
extend downward within the body
78
of the calibration member
74
. The design allows sufficient clearance around the outside diameter of the filter to allow the free flow of fuel into the upper end
86
of the calibration member and through the filter screen
98
and the interior of the body
78
, passing out through the lower end
80
of the calibration member
74
.
As shown in
FIG. 1
, the calibration assembly
58
is inserted into the fuel tube
12
with the enlarged portion
88
at its upper end forced into the inlet end of the fuel tube
12
. The parts are sized for an interference fit forming a sufficient restriction to prevent any significant bypassing of fuel around the fuel filter within the calibration tube. The interference fit is also adequate to prevent the passage of particles around the filter which are greater than 30 microns which the filter is designed to remove from the fuel passing therethrough. The lower end
80
of the calibration member
74
is positioned with its annular seat
82
against the biasing spring
56
and with the spring guide
84
extending inside the upper end of the spring.
In order to calibrate the biasing spring to obtain the proper spring force against the injection valve
50
, a calibrating tool
102
is used as shown in phantom in FIG.
1
. During assembly of the injector, before insertion into the fuel rail cup
34
, the tool
102
is inserted through the inlet end of the fuel tube
12
into engagement with the crimped over portion
100
of the calibration assembly
58
and a force, which can be as much as 40 to 80 pounds, is exerted which is adequate to slide the calibration tube downward against the spring until the desired spring force or fuel flow for the injector is reached. The calibrating tool
102
is then removed and the calibration assembly
58
is retained in fixed position within the injector by the substantial interference fit between the enlarged portion
88
of the calibration member
74
and the interior of the fuel tube
12
. If desired, the body
78
of the calibration member could also be fitted with sufficient force into the tubular magnetic pole
46
to supplement the securing force applied to the calibration member within the fuel tube
12
.
The improved assembly
58
of the calibration member
74
and fuel filter
76
and its interference mounting within the fuel tube
12
provides significant advantages in simplification and cost during the assembly of the fuel injector
10
. Because the calibration assembly
58
is designed to allow calibration of the valve spring force with the filter in place, the fuel filter may be installed in the injector in an earlier stage of assembly of the injector than in injectors wherein the fuel filter is mounted separately at the inlet of the fuel tube. This allows the fuel filter to prevent contamination of the interior of the calibration tube and the valve member ball end
52
and armature within the fuel passage during assembly steps of the injector after insertion of the calibration assembly and during the calibration process itself.
In addition, the interference fit of the calibration assembly
58
within the fuel tube
12
prevents substantial bypassing of fuel around the fuel filter and positively precludes particles larger than that removed by the fuel filter from entering the fuel stream below the fuel filter within the injector tube. The interference fit also is sufficient to hold the calibration member
74
in position after calibration without requiring an additional step, such as crimping or welding, to hold the tube in place after the calibration process is completed. These advantages simplify the process of assembly and provide a significant reduction of cost in the assembly process.
FIGS. 3-5
illustrate some alternative embodiments of calibration assemblies which are exemplary of various additional forms that may be utilized within the scope of the invention. In
FIG. 3
, calibration assembly
104
includes a calibration member
74
and a fuel filter
76
, as in FIG.
2
. However, the fuel filter is reversed in position so that, while its hollow base
92
is still crimped into the enlarged portion
88
of the calibration member body
78
, the filter screen
98
and the supporting ribs
94
and cap
96
extend out through the inlet end or upper end
86
of the calibration member so that fuel flow passes through the filter screen in the opposite direction from the embodiment of FIG.
2
.
In spite of the protruding fuel filter, calibration of the force on the biasing spring
56
within the injector may be accomplished in the same manner by a tubular calibration tool, not shown, which extends into engagement with the crimped over portions
100
at the upper end of the calibration member body
78
. In this way, sufficient force can be applied to the calibration assembly
104
as to the previous assembly embodiment
58
to permit the assembly
104
to be retained in the fuel tube by an interference fit. The required force, which may be in the neighborhood of 40-80 pounds would be excessive if it was intended to calibrate the assembly by applying force to the plastic filter cap, or the filter frame would have to be made much stronger at additional cost in order to accept forces of this magnitude.
Referring now to
FIG. 4
, an alternative embodiment of calibration assembly
106
is illustrated. The calibration member
108
is formed with a straight cylindrical lower end but could optionally be formed with the stepped in smaller diameter of the previously described embodiments, if desired. The upper end includes an enlarged portion
110
into which a filter
112
is insert molded. In this process, the calibration member
108
and filter screen
114
are positioned in their proper relationship within plastic molding dies and the plastic frame
116
is molded in place. The frame
116
includes an integral base, spaced ribs and cap, all of which secure the filter screen
114
in place and the insert molding process fixes the frame
116
within the enlarged portion
110
of the calibration member
108
. The resulting assembly
106
is installed in the injector fuel tube
12
and calibrated in the same manner as with the previously described embodiments.
Referring now to
FIG. 5
, a calibration assembly
118
is illustrated having a calibration member
120
and a fuel filter
122
. Member
120
is formed at its lower end with the same configuration as in the embodiments of
FIGS. 2 and 3
, whereas the upper end
124
is enlarged with a generally cylindrical end portion having an internally raised bead
138
intermediate the ends of the enlarged portion. The accompanying fuel filter
122
includes an outwardly extending annular plastic base
128
connecting at its lower end with wraparound ribs
130
that extend around the lower end of a filter screen
132
and longitudinally upward to a closed outer end cap
134
while providing intermediate support to the filter screen between its ends. The base
128
includes an intermediate annular recess
136
which allows the filter assembly to be snapped into engagement with the upper end
124
of the calibration member
120
. There it is held in place by the inwardly raised bead
138
engaging the annular recess
136
of the filter base
128
.
Installation of the assembly
118
into the fuel tube
12
of an associated injector can be accomplished in the same manner as before except that the tubular calibration tool, not shown, is positioned to engage the upper edge
139
of the plastic fuel filter base
128
rather than crimped over metal portions of the calibration member as in the previous embodiments. While calibration member
118
is shown with the fuel filter
122
extending outward from its mounting within the calibration member or tube
120
, as is the case with the embodiments of
FIGS. 3 and 4
, it should be recognized that the embodiment of
FIG. 5
could be designed for installation in the reverse direction with the filter extending into the lower body portion of the calibration member, as in the embodiment of FIG.
2
. The base
128
of the filter frame would still, if properly designed, snap into the enlarged upper end
124
of the calibration member. The filter would then operate in the same manner as described for the embodiment of
FIG. 2
except, again, the calibration tool would engage the outer end of the base
128
instead of the calibration member itself. In both instances, however, the inwardly extending filter member has the advantage, if needed, that the injector may be made shorter, where the associated engine application would permit, than would be the case with outwardly extending filter mounting arrangements, such as in
FIGS. 3 and 4
.
The various embodiments of calibration members described herein have been shown with a fuel injector having a continuous fuel tube defining the fuel passing through the injector. However, the invention is also applicable to other forms of top feed fuel injectors which include a fuel inlet tube through which a calibration tube assembly may be inserted.
While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Accordingly it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.
Claims
- 1. A fuel injector having inlet and discharge ends and comprising:a fuel tube at the inlet end through which fuel is admitted to a fuel passage extending to the discharge end; a valve at the discharge end and having a valve element reciprocable against and away from a valve seat to prevent or allow fuel discharge through the valve seat; a biasing spring having a first end operatively engaging the valve element; a calibration member having first and second ends and defining a portion of the fuel passage through which fuel must pass to the injector discharge end, the calibration member having adjacent the first end an enlarged portion engaging the fuel tube with an interference fit, the second end defining a spring seat operatively engaging the spring and biasing the spring against the valve element with a set force for controlling fuel discharge from the injector, the calibration member being adjustable within the injector for calibrating the spring to establish the set force; and a fuel filter mounted within the calibration member and effective to filter all the fuel passing through the calibration member defin portion of the fuel passage, said filter having an enlarged hollow base received within the enlarged portion of the calibration member and mounting the filter in the calibration member.
- 2. A fuel injector as in claim 1 wherein the calibration member is adjustable by sliding within the injector and the interference fit of the enlarged portion with the fuel inlet tube is adequate to maintain a set position of the calibration member after calibration adjustment and prevent a substantial bypass of fuel around the filter.
- 3. A fuel injector as in claim 2 wherein the calibration member is a metal tube.
- 4. A fuel injector as in claim 3 wherein said enlarged portion of the tube is engagable by a tool for slidably adjusting the calibration member with a force adequate to overcome resistance of the interference fit.
- 5. A fuel injector as in claim 3 wherein the filter has a plastic frame including the enlarged hollow base connected by a plurality of annularly spaced ribs with a closed end and a tubular filter screen between the base and the closed end and supported by the ribs for filtering out particles above about 30 microns.
- 6. A fuel injector as in claim 3 wherein the calibration member second end is stepped to a smaller diameter to form the spring seat and an internally adjacent spring guide.
- 7. A fuel injector as in claim 5 wherein the filter screen extends within the metal tube toward the spring seat.
- 8. A fuel injector as in claim 5 wherein the filter screen extends out through the first end of the calibration member into the inlet end of the fuel tube.
- 9. A fuel injector as in claim 8 wherein the filter frame base is insert molded into the enlarged portion of the tube while the filter screen is molded into the frame.
- 10. A fuel injector as in claim 5 wherein the filter frame base is secured within the enlarged portion of the tube by snap fitting.
- 11. A fuel injector as in claim 1 wherein said calibration member and said fuel filter comprise a calibration assembly formed prior to installation in the fuel injector fuel inlet tube.
- 12. A calibration assembly for insertion in a fuel tube of a fuel injector for setting a valve spring seating force in the injector, said assembly comprising:a calibration member having first and second ends and capable of defining a portion of a fuel passage, the calibration member having adjacent the first end an enlarged portion engagable with the fuel tube with an interference fit, the second end defining a spring seat operatively engagable with the spring to establish a set force; and a fuel filter mounted within calibration member for filtering all the fuel passing through the calibration member, said filter having an enlarged hollow base received within the enlarged portion of the calibration member for mounting the filter in the calibration member.
- 13. A calibration assembly as in claim 12 wherein the calibration member is a metal tube.
- 14. A calibration assembly as in claim 12 wherein said enlarged portion of the calibration member is engagable by a tool for slidably adjusting the calibration member with a force adequate to overcome resistance of the interference fit.
- 15. A calibration assembly as in claim 12 wherein the filter has a plastic frame including the enlarged hollow base connected by a plurality of annularly spaced ribs with a closed end and a tubular filter screen between the base and the closed end and supported by the ribs for filtering out particles above about 30 microns.
- 16. A calibration assembly as in claim 12 wherein the calibration member second end is stepped to a smaller diameter to form the spring seat and an internally adjacent spring guide.
- 17. A calibration assembly as in claim 16 wherein the filter screen extends within the metal tube toward the spring seat.
- 18. A calibration assembly as in claim 16 wherein the filter screen extends out beyond the first end of the calibration member.
- 19. A calibration assembly as in claim 18 wherein the filter frame base is insert molded into the enlarged portion of the tube while the filter screen is molded into frame.
- 20. A calibration assembly as in claim 15 wherein the filter frame base is secured within the enlarged portion of the tube by snap fitting.
US Referenced Citations (7)