Information
-
Patent Grant
-
6631853
-
Patent Number
6,631,853
-
Date Filed
Monday, April 9, 200123 years ago
-
Date Issued
Tuesday, October 14, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Mar; Michael
- Nguyen; Dinh Q.
Agents
-
CPC
-
US Classifications
Field of Search
US
- 239 5
- 239 124
- 251 1291
- 137 62565
- 137 62568
- 137 24713
- 091 464
-
International Classifications
-
Abstract
An oil activated fuel injector control valve which substantially eliminates captured air within working fluid of the fuel injector. This eliminates shot by shot variations in the fuel injector as well as increasing the efficiency of the fuel injector. The fuel injector includes a control valve body which has vent holes which prevent air from mixing with the working fluid. In this manner, the working fluid does not have to compress and/or dissolve the air in the working ports prior to acting on the piston and plunger mechanism in an intensifier body of the fuel injector.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to an oil activated fuel injector and, more particularly, to an oil activated electronically or mechanically controlled fuel injector control valve which substantially eliminates captured air within working fluid of the fuel injector.
2. Background Description
There are many types of fuel injectors designed to inject fuel into a combustion chamber of an engine. For example, fuel injectors may be mechanically, electrically or hydraulically controlled in order to inject fuel into the combustion chamber of the engine. In the hydraulically actuated systems, a control valve body may be provided with two, three or four way valve systems, each having grooves or orifices which allow fluid communication between working ports, high pressure ports and venting ports of the control valve body of the fuel injector and the inlet area. The working fluid is typically engine oil or other types of suitable hydraulic fluid which is capable of providing a pressure within the fuel injector in order to begin the process of injecting fuel into the combustion chamber.
It has been found in open systems that air becomes captured and locked within the grooves or orifices of the control valve (and a spool) during the venting of the working fluid during and at an end of a fuel injection cycle. This is mainly due to the fact that vent holes which surround the control valve body allow air to enter the system. This air will mix with the working fluid during the fuel injection process resulting in variations in fuel injection quantities. Of course, this will lead to inefficient shot to shot variations.
Being more specific, a driver will first deliver a current or voltage to an open side of an open coil solenoid. The magnetic force generated in the open coil solenoid will shift a spool into the open position so as to align grooves or orifices (hereinafter referred to as “grooves”) of the control valve body and the spool. The alignment of the grooves permits the working fluid to flow into an intensifier chamber from an inlet portion of the control valve body (via working ports). The high pressure working fluid then acts on an intensifier piston to compress an intensifier spring and hence compress fuel located within a high pressure plunger chamber. As the pressure in the high pressure plunger chamber increases, the fuel pressure will begin to rise above a needle check valve opening pressure. At the prescribed fuel pressure level, the needle check valve will shift against the needle spring and open the injection holes in a nozzle tip. The fuel will then be injected into the combustion chamber of the engine.
To end the injection cycle, the driver will deliver a current or voltage to a closed side of a closed coil solenoid. The magnetic force generated in the closed coil solenoid will then shift the spool into the closed or start position which, in turn, will close the working ports of the control valve body. The working fluid pressure will then drop in the intensifier and high-pressure chamber such that the needle spring will shift the needle to the closed position. The nozzle tip, at this time, will close the injection holes and end the fuel injection process. At this stage, the working fluid is then vented from the fuel injector via vent holes surrounding the control valve body.
Referring now to
FIG. 1A
, in current designs the vent holes
10
surround the control valve body
12
and the spool
14
such that air
16
in the control valve body
12
is below the working fluid level
18
. This causes the grooves
20
of the control valve body
12
and the spool
14
to be filled with air
16
. Now, during the next cycle time (as seen in
FIG. 1B
) when the spool
14
is shifted to the open position, this air
16
becomes locked within the grooves
20
causing air bubbles
22
to be formed within the working fluid
18
of the working ports
23
. In order to inject fuel within the combustion chamber, this captured air will have to be compressed by the working fluid and dissolved partially into a dilution prior to the working fluid acting on the intensifier piston. This causes a shot to shot fuel variation (depending on the quantity of air in the working fluid) thus resulting in decreased fuel efficiency especially for low fuel quantities.
The present invention is directed to overcoming one or more of the problems as set forth above.
SUMMARY OF THE INVENTION
In a first aspect of the present invention, a check valve body has an inlet area and a working port in fluid communication with the inlet area. The working port is adapted to provide working fluid to an intensifier chamber of the fuel injector. At least one communication port is in fluid communication with the inlet area and the working port. At least one vent hole is provided which prevent air from mixing with the working fluid.
In another aspect of the present invention, the check valve body has an oil inlet area and a at least one port in fluid communication with the oil inlet area. The port transport oil between the oil inlet area and an intensifier chamber of the fuel injector. An aperture having at least one communication port provides a flow path for the oil between the ports and the oil inlet area. A spool is positioned within the aperture and includes at least one fluid path which are in alignment with the communication port of the aperture when the spool is in the first position. Vent ports vent the oil from the control valve body and prevent air from entering the at least one fluid path of the spool.
In still another aspect of the present invention, a fuel injector having a control body is provided. The control body has an inlet area, working ports, communication ports and fluid paths, a spool and at least one vent hole. The at least one vent hole is positioned above the working ports to reduce captured air in the working ports during a venting process. The fuel injector also includes an intensifier body and a spring loaded piston and plunger within a centrally located bore of the intensifier body. A high pressure fuel chamber is also formed in the intensifier body. A nozzle having a fuel bore is in fluid communication with the high pressure chamber, and a needle is positioned within the nozzle. A fuel chamber surrounds the needle.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, aspects and advantages will be better understood from the following detailed description of a preferred embodiment of the invention with reference to the drawings, in which:
FIG. 1A
shows a conventional control valve body of an oil activated fuel injector with captured air in vent holes and grooves;
FIG. 1B
shows a conventional control valve body with air bubbles in the working fluid;
FIG. 2
shows an oil activated fuel injector of the present invention;
FIG. 3A
shows a control valve body of the oil activated fuel injector of the present invention with a spool in a closed position;
FIG. 3B
shows the control valve body of the present invention with the spool in the open position;
FIG. 4A
shows a second embodiment of the control valve body of the present invention with the spool in the closed position;
FIG. 4B
shows the second embodiment of the control valve body of the present invention with the spool in the open position;
FIG. 5
shows a third embodiment of the control valve body of the present invention; and
FIGS. 6-10
show performance charts of the oil activated fuel injector of the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
The present invention is directed to an oil activated electronically, mechanically or hydraulically controlled fuel injector which is capable of substantially decreasing and/or preventing captured air from mixing with the working fluid such as, for example, hydraulic oil, during the fuel injection process. The oil activated fuel injector of the present invention will also avoid capturing of air in the control valve body as well as grooves or orifices positioned in either a spool or the control valve body, itself. The present invention is also capable of decreasing shot to shot variations in fuel injection at low fuel quantities thus increasing the predictability of the fuel injector throughout a range of hydraulic oil pressures. This increased predictability also leads to increased fuel efficiency even at lower fuel quantities.
Embodiments of the Oil Activated Fuel Injector of the Present Invention
Referring now to
FIG. 2
, an overview of the fuel injector of the present invention is shown. The fuel injector is generally depicted as reference numeral
100
and includes a control valve body
102
as well as an intensifier body
120
and a nozzle
140
. The control valve body
102
includes an inlet area
104
which is in fluid communication with working ports
106
. At least one groove or orifice (hereinafter referred to as grooves)
108
are positioned between and in fluid communication with the inlet area
104
and the working ports
106
. At least one of vent hole
110
(and preferably two ore more) is located in the control body
102
which are in fluid communication with the working ports
106
. In the embodiments of the present invention, the vent holes
110
are arranged or designed to eliminate or substantially reduce captured air in the working fluid within the working ports
106
.
A spool
112
having at least one groove or orifice (hereinafter referred to as grooves)
114
is slidably mounted within the control valve body
102
. An open coil
116
and a closed coil
118
are positioned on opposing sides of the spool
112
and are energized via a driver (not shown) to drive the spool
112
between a closed position and an open position. In the open position, the grooves
114
of the spool
112
are aligned with the grooves
108
of the valve control body
102
thus allowing the working fluid to flow between the inlet area
104
and the working ports
106
of the valve control body
102
.
Still referring to
FIG. 2
, the intensifier body
120
is mounted to the valve control body
102
via any conventional mounting mechanism. A seal
122
(e.g., o-ring) may be positioned between the mounting surfaces of the intensifier body
120
and the valve control body
102
. A piston
124
is slidably positioned within the intensifier body
120
(e.g. intensifier chamber) and is in contact with an upper end of a plunger
126
. An intensifier spring
128
surrounds a portion (e.g., shaft) of the plunger
126
and is further positioned between the piston
124
and a flange or shoulder
129
formed on an interior portion of the intensifier body
120
. The intensifier spring
128
urges the piston
122
and the plunger
126
in a first position proximate to the valve control body
102
. A plurality of venting and pressure release holes
130
and
132
, respectively, are formed in the body of the intensifier body
120
. The plurality of venting and pressure release holes
130
and
132
are further positioned adjacent the plunger
126
.
A check disk
134
is positioned below the intensifier body
120
remote from the valve control body
102
. The combination of an upper surface
134
a
of the check disk
134
, an end portion
126
a
of the plunger
126
and an interior wall
120
a
of the intensifier body
120
forms a high pressure chamber
136
. A fuel inlet check valve
138
is positioned within the check disk
134
and provides fluid communication between the high pressure chamber
136
and a fuel area (not shown). This fluid communication allows fuel to flow into the high pressure chamber
136
from the fuel area during an up-stroke of the plunger
126
. The pressure release hole
132
is also in fluid communication with the high pressure chamber
136
when the plunger
126
is urged into the first position; however, fluid communication is interrupted when the plunger
126
is urged downwards towards the check disk
134
. The check disk
134
also includes an angled fuel bore
139
in fluid communication with the high pressure chamber
136
.
FIG. 2
further shows the nozzle
140
and a spring cage
142
. The spring cage
142
is positioned between the nozzle
140
and the check disk
134
, and includes a straight fuel bore
144
in fluid communication with the angled fuel bore
139
of the check disk
134
. The spring cage
142
also includes a centrally located bore
148
having a first bore diameter
148
a
and a second smaller bore diameter
148
b.
A spring
150
and a spring seat
152
are positioned within the first bore diameter
148
a
of the spring cage
142
, and a pin
154
is positioned within the second smaller bore diameter
148
b.
The nozzle
140
includes a second angled bore
146
in alignment with the straight bore
139
of the spring cage
142
. A needle
150
is preferably centrally located with the nozzle
140
and is urged downwards by the spring
150
(via the pin
154
). A fuel chamber
152
surrounds the needle
150
and is in fluid communication with the angled bore
146
. In embodiments, a nut
160
is threaded about the intensifier body
120
, the check disk
134
, the nozzle
140
and the spring cage
142
.
FIG. 3A
shows the control valve body
102
of
FIG. 2
with the spool
112
in the closed or start position. In
FIG. 3A
, the lower vent holes
110
a
are plugged or capped to ensure that air
162
remains above the working fluid level
164
during the venting process. Alternatively, the lower vent holes
110
a
may be entirely eliminated from the valve control body
102
. In these embodiments, the working fluid
164
rises to a level of the upper vent holes
110
b
during the venting process. The working fluid
164
also fills the grooves
114
of the spool
112
; however, air
162
may remain in the upper portion of the grooves
108
and the upper vent holes
110
b
of the valve control body
102
. In this configuration, the air in the upper vent holes
110
b
and upper portion of the grooves
108
is above the level of the working fluid
164
. In the closed position of
FIG. 3A
, the working fluid
164
within the inlet area
104
will not flow to the working ports
106
due to the non-alignment of the grooves
108
and
114
.
FIG. 3B
shows the control body
102
with the spool
112
in an open position. In the open position of the spool
112
, the grooves
108
of the valve control body
102
and the grooves
114
of the spool
112
are in alignment with one another thus allowing the working fluid
164
to flow from the inlet area
104
to the working ports
106
. As seen from
FIG. 3B
, during the flow of working fluid
164
only a small amount of air is captured and locked in the grooves
108
. Accordingly, only a small amount of air
162
is then captured in the working fluid
164
. This is because the air
162
remains above the working fluid level
164
when the spool
112
is in the closed position (FIG.
3
A). Thus, only a small amount of captured air will have to be compressed and dissolved by the working fluid thus greatly minimizing shot to shot fuel variations especially for low fuel quantities.
FIG. 4A
shows a second embodiment of the control valve body
102
with the spool
112
in the closed position. In this embodiment, the vent holes
110
include an inlet
111
which is positioned above the grooves
108
of the valve control body
102
and the grooves
114
of the spool
112
. The position of the inlet
111
of the vent holes
110
will not permit air to fill the grooves
108
and
114
. This is because the position of the vent holes
110
is positioned such that the working fluid
164
will remain in the vent holes
110
during and after the venting process, and air
162
will thus be prevented from entering the grooves
108
and
114
. That is, the air
164
will always remains above the grooves
108
and
114
. Now, when the spool
112
is in the closed position and the venting process begins it is not possible for the air
162
to enter the grooves
108
of the valve control body
102
and the grooves
114
of the spool
112
. Thus, as seen in
FIG. 4B
, the working fluid
164
will flow between the inlet
104
and the working ports
106
of the valve control body
102
without any captured air therein.
FIG. 5
shows an embodiment of the control valve body
102
of
FIGS. 4A and 4B
. In this embodiment, the vent holes
110
include a check valve
166
. The check valve
166
includes a spring
168
which biases a ball, plate or cone
170
against a seat
172
. The vent holes may face downward due to the use of the check valve
166
. During the venting process, the working fluid
164
overcomes a spring force of the spring
168
and thus disengages the ball
170
from the seat
172
. This allows the working fluid
164
to vent from the vent holes
110
during the venting process. When the spool
112
is in the open position or venting stops, the ball
170
will be biased against the seat
172
and will prevent air from entering the system. In this manner, when the spool
112
is in the closed position and the venting process begins it is not possible for air
162
to enter or become locked in the grooves
108
or
114
. In this arrangement, air
162
will not be mixed with the working fluid
164
thus ensuring more consistent fuel consumption predictability and efficiency.
FIG. 6
shows a chart depicting several tests of a conventional fuel injector (of known design) and the oil activated fuel injector of
FIGS. 2-3B
at several different testing pressures. The lines
200
depict the results relating to the oil activated fuel injector of the present invention and lines
300
depict the results of the conventional fuel injector. The test parameters included:
1. Engine speed: 1000 RPM
2. Pump speed: 1000 RPM
3. Engine Oil Temperature: approximately 93° Celsius
4. Calibration Fluid Temperature: approximately 40° Celsius.
FIG. 6
clearly shows that the performance of the oil activated fuel injector of the present invention is superior to that of a conventional fuel injector (i.e., a fuel injector which does not prevent air from mixing with the working fluid) throughout a range of testing pressures. The superior performance of the oil activated fuel injector of the present invention is shown to be even greater at higher operating pressures such as, for example, 160 bars. This superior performance is attributed to the fact that the oil activated fuel injector of the present invention substantially prevents and, in embodiments, completely eliminates the mixing of air with the working fluid. This is a direct result of the placement and/or design of the vent holes
110
of the control valve body
102
.
FIGS. 7-10
also show the superior performance of the oil activated fuel injector of the present invention compared to a conventional fuel injector.
FIGS. 7-10
use the same test parameters of FIG.
6
.
Operation of the Oil Activated Fuel Injector of the Present Invention
In operation, a driver (not shown) will first energize the open coil
116
. The energized open coil
116
will then shift the spool
112
from a start position to an open position. In the open position, the grooves
108
of the control valve body
102
will become aligned with the grooves
114
on the spool
112
. The alignment of the grooves
108
and
114
will allow the pressurized working fluid to flow from the inlet area
104
to the working ports
106
of the control valve body
102
. As discussed in greater detail below, the placement and/or design of the vent holes
110
of the control valve body
102
will eliminate the mixing of air with the working fluid.
Once the pressurized working fluid is allowed to flow into the working ports
106
it begins to act on the piston
124
and the plunger
126
. That is, the pressurized working fluid will begin to push the piston
124
and the plunger
126
downwards thus compressing the intensifier spring
128
. As the piston
124
is pushed downward, fuel in the high pressure chamber will begin to be compressed via the end portion
126
a
of the plunger. The compressed fuel will be forced through the bores
139
,
144
and
146
and into the chamber
158
which surrounds the needle
156
. As the plunger
126
is pushed downward, the fuel inlet check valve
138
prevents fuel from flowing into the high pressure chamber
136
from the fuel area. As the pressure working ports
106
increases, the fuel pressure will rise above a needle check valve opening pressure until the needle spring
148
is urged upwards. At this stage, the injection holes are open in the nozzle
140
thus allowing fuel to be injected into the combustion chamber of the engine.
To end the injection cycle, the driver will energize the closed coil
118
. The magnetic force generated in the closed coil
118
will then shift the spool
112
into the closed or start position which, in turn, will close the working ports
106
of the control valve body
102
. That is, the grooves
108
and
114
will no longer be in alignment thus interrupting the flow of working fluid from the inlet area
104
to the working ports
106
. At this stage, the needle spring
150
will urge the needle
156
downward towards the injection holes of the nozzle
140
thereby closing the injection holes. Similarly, the intensifier spring
128
urges the plunger
126
and the piston
124
into the closed or first position adjacent to the valve control body
102
. As the plunger
126
moves upward, the pressure release hole
132
will release pressure in the high pressure chamber
136
thus allowing fuel to flow into the high pressure chamber
136
(via the fuel inlet check valve
138
). Now, in the next cycle the fuel can be compressed in the high pressure chamber
136
.
As the plunger
126
and the piston
124
move towards the valve control body
102
, the working fluid will begin to be vented through the vent holes
110
of the present invention. This is due to the narrowing space between the piston
124
and the valve control body
102
. As now discussed below, the vent holes
110
are arranged or designed to eliminate or substantially reduce captured air in the working fluid within the working ports
106
.
In the embodiment of
FIGS. 3A and 3B
, the lower vent holes
110
a
are plugged or capped to ensure that air remains above the working fluid level during the venting process. Alternatively, the lower vent holes
110
a
may be entirely eliminated from the valve control body
102
. In this embodiment, the working fluid rises to a level of the upper vent holes
110
b
during the venting process. The working fluid also fills the grooves
114
. Any air in the system such as, for example, in the upper vent holes
110
b
and an upper portion of the grooves
108
is above the level of the working fluid. In this arrangement, during the next cycle when the spool
112
is opened, only a small amount of air is locked in the grooves
108
and is captured in the working fluid. This is because the air remains above the working fluid level when the spool
112
is in the closed position. Thus, only a small amount of captured air will have to be compressed and dissolved by the working fluid thus greatly minimizing shot to shot fuel variation.
In the embodiment of
FIGS. 4A and 4B
, the inlet
111
of the vent holes
110
are positioned above the grooves
108
of the valve control body
102
and the grooves
114
of the spool
112
. This position will not permit air to fill the grooves
108
and
114
during the venting process since any air in the vent holes will now always remain above the grooves
108
and
114
. In the configuration of
FIGS. 4A and 4B
, when the spool
112
is again opened the working fluid will flow between the inlet area
104
and the working ports
106
of the valve control body
102
without any captured air therein.
As to the embodiment of
FIG. 5
, the vent holes
110
include a check valve
166
which prevents air from entering the system during the venting process. Thus, when the spool
112
is in the closed position and the venting process begins it is not possible for air to enter or become locked in the grooves
108
or
114
. This ensures that no air will be locked in the grooves
108
and
114
and mix with the working fluid thus providing for more efficient fuel consumption.
While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims.
Claims
- 1. A control valve body adapted for use with a fuel injector, comprising:an inlet area; working ports in fluid communication with the inlet area, the working ports for providing working fluid to an intensifier chamber of the fuel injector; at least one communication port in fluid communication with the inlet area and the working ports; and at least one vent hole in fluid communication with the working ports, the at least one vent hole preventing air from entering the working ports and mixing with the working fluid.
- 2. The control valve body of claim 1, wherein the at least one vent hole includes at least one upper vent hole positioned above the working ports.
- 3. The control valve body of claim 2, wherein the at least one vent hole includes at least one lower vent hole positioned below a level of the working fluid, the at least one lower vent hole being plugged or capped to prevent venting of the working fluid from the at least one lower vent hole.
- 4. The control valve body of claim 1, wherein the at least one vent hole has an inlet which is positioned above the at least one communication port.
- 5. The control valve body of claim 4, wherein the working fluid remains within the at least one vent hole which will prevent air from entering the working ports and mixing with the working fluid therein.
- 6. The control valve body of claim 1, further comprising a check valve positioned within the at least one vent hole, the check valve allowing working fluid to be vented to a drain and preventing air from entering the working ports.
- 7. The control valve body of claim 6, wherein the check valve includes one of a ball, plate and cone, the check valve further including a spring, the spring urges the ball, plate or cone against a seat located within the at least one vent hole.
- 8. The control valve body of claim 6, wherein the at least one vent hole faces downward.
- 9. The control valve body of claim 1, wherein the at least one communication port is two or more communication ports.
- 10. The control valve body of claim 1, wherein the at least one communication port is one of an orifice and a groove.
- 11. The control valve body of claim 1, further comprising a spool having at least one communication port, the spool being slidable between a first position and a second position, the at least one communication port of the spool and the at least one communication port being in alignment when the spool is in the first position, the at least one vent hole preventing air from entering the at least one communication port of the spool.
- 12. The control valve body of claim 11, wherein the at least one communication port of the spool is one of a groove and an orifice and air is prevented from being locked in the groove or orifice of the spool.
- 13. The control valve body of claim 1, wherein the at least one communication port is two or more communication ports.
- 14. A control valve body for use with a fuel injector, comprising:an oil inlet area; at least one port in fluid communication with the oil inlet area, the at least one port transporting oil between the oil inlet area and an intensifier chamber of the fuel injector; an aperture having at least one communication port positioned about a surface of the aperture, the at least one communication port providing a flow path for the oil between the at least one port and the oil inlet area; a spool positioned within the aperture and slideable between a first position and a second position, the spool including at least one communication port which is in alignment with the at least one communication port of the aperture when the spool is in the first position; and at least one vent port for venting the oil from the control valve body when the spool is in the second position, the at least one vent port being positioned above a level of the oil and preventing air from entering the at least one communication port of the spool.
- 15. The control valve body of claim 14, wherein the at least one vent port includes an inlet above the at least one communication port of the spool and the aperture.
- 16. The control valve body of claim 15, further including a check valve positioned at the inlet of the at least one vent port.
- 17. The control valve body of claim 15, wherein the check valve includes one of a ball, plate and cone and a spring mechanism, wherein the spring urges the ball, plate or cone against a seat of the check valve after a venting of the oil.
- 18. The control valve body of claim 14, wherein the at least one vent hole includes an upper set of vent holes and a lower set of vent holes, the upper set of vent holes being positioned above the oil and the lower set of vent holes being capped or plugged.
- 19. The control valve body of claim 14, wherein the at least one communication port of the aperture and the spool is one of a groove and an orifice.
- 20. An oil activated fuel injector, comprising:a control valve body, the control body including: an inlet area; at least one working port in fluid communication with the inlet area; at least one communication port positioned between and in fluid communication with the inlet area and the at least one working port; a spool having at least one fluid path which is alignable with the at least one communication port; at least one vent hole in fluid communication with the at least one working port, the at least one vent hole being positioned above the at least one working port to reduce captured air in the at least one working port; an intensifier body mounted to the control valve body, the intensifier body including a centrally located bore and a shoulder; a piston slidably positioned within centrally located bore of the intensifier body; a plunger contacting the piston, the plunger having a first end, a second end and a shaft; an intensifier spring surrounding the shaft of the plunger and further positioned between the piston and the shoulder of the intensifier body, the intensifier spring urging the piston and the plunger in a first position proximate to the valve control body; a high pressure fuel chamber formed at the second end of the plunger; a nozzle having a fuel bore in fluid communication with the high pressure chamber; a needle positioned within the nozzle; and a fuel chamber surrounding the needle and in fluid communication with the fuel bore.
- 21. The fuel injector of claim 20, wherein the at least one vent hole has an inlet which is positioned above the at least one fluid path of the spool.
- 22. The fuel injector of claim 21, wherein working fluid remains within the at least one vent hole which eliminates air from entering the at least one working port and mixing with the working fluid therein.
- 23. The fuel injector of claim 21, further comprising a check valve positioned within the at least one vent hole, the check valve allowing working fluid to be vented to a drain and preventing air from entering the at least one working port.
- 24. The fuel injector of claim 20, wherein the at least one vent hole includes an upper set of vent holes and a lower set of vent holes, the upper set of vent holes being positioned above working fluid in the at least one working port and the lower set of vent holes being capped or plugged.
- 25. The fuel injector of claim 20, further comprising:a check disk positioned below the intensifier body remote from the valve control body, wherein a combination of an upper surface of the check disk, the second end of the plunger and an interior wall of the intensifier body forms the high pressure chamber; and a fuel bore in fluid communication with the fuel bore of the nozzle.
- 26. The fuel injector of claim 25, further comprising a fuel inlet check valve positioned within the check disk and providing fluid communication between the high pressure chamber and a fuel area during an upstroke of the plunger.
- 27. The fuel injector of claim 26, further comprising a spring cage positioned between the nozzle and the check disk, the spring cage including a spring which is in biasing contact with the needle.
US Referenced Citations (14)