Information
-
Patent Grant
-
6298826
-
Patent Number
6,298,826
-
Date Filed
Friday, December 17, 199924 years ago
-
Date Issued
Tuesday, October 9, 200122 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Dolinar; Andrew M.
- Castro; Arnold
Agents
-
CPC
-
US Classifications
Field of Search
US
- 123 446
- 137 62569
- 239 88
- 239 89
- 239 90
- 239 95
-
International Classifications
-
Abstract
A control valve comprises a valve body that defines a high pressure passage, a low pressure passage and a flow passage. A valve member that is positioned in the valve body and defines an internal passage that opens through an end, and a closing hydraulic surface that is exposed to fluid pressure in the flow passage. The valve member is movable between a first position at which said high pressure passage is open to the flow passage via the internal passage and a second position at which the low pressure passage is open to the flow passage. The closing hydraulic surface is oriented such that pressure applied to the closing hydraulic surface produces a force on the valve member in a direction toward the second position.
Description
TECHNICAL FIELD
The present invention relates generally to control valves, and more particularly to use of center feed control valves in hydraulically actuated devices, such as fuel injectors.
BACKGROUND ART
A number of hydraulically actuated fuel injectors have been developed in recent years. While these injectors have performed well, engineers are always looking for ways to improve upon their design. For instance, because it is desirable to have an abrupt end to injection events with a lessened possibility of secondary injections, methods to more quickly relieve internal pressure after an injection event are often being sought. Additionally, a reduction in the overall size of the hydraulically actuated fuel injector is desirable to allow for incorporation of hydraulically actuated fuel injectors in ever smaller engine designs. Finally, it is almost always desirable to reduce the number of components in a hydraulically actuated fuel injector.
The present invention is directed to overcoming one or more of the problems set forth above.
SUMMARY OF THE INVENTION
A control valve comprises a valve body that defines a high pressure passage, a low pressure passage and a flow passage. A valve member is positioned in the valve body, has an end, and defines an internal passage that opens through the end. The valve member also defines a closing hydraulic surface that is exposed to fluid pressure in the flow passage. The valve member is movable between a first position at which the high pressure passage is open to the flow passage via the internal passage and a second position at which the low pressure passage is open to the flow passage. The closing hydraulic surface is oriented such that pressure applied to the closing hydraulic surface produces a force on the valve member in a direction toward the second position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic illustration of a hydraulic system that includes a hydraulically-actuated device according to the present invention.
FIG. 2
is a diagrammatic front sectioned view of a hydraulically actuated fuel injector according to the present invention.
BEST MODE OF CARRYING OUT THE INVENTION
Referring now to
FIG. 1
, hydraulic system
10
includes a hydraulically-actuated device
11
, such as a fuel injector or an engine valve. A control valve
12
alternately opens hydraulically-actuated device
11
to a source of high pressure fluid
13
or a low pressure fluid reservoir
14
. The state of control valve
12
is controlled by energizing and de-energizing an electrical actuating device
16
, which is preferably a solenoid but could also be another suitable device such as a piezoelectric actuator. Electrical actuating device
16
is controlled in its operation by a conventional electronic control module
15
via communication line
29
.
Control valve
12
includes a valve body
19
that defines a high pressure inlet
20
that is connected to the source of high pressure fluid
13
via a high pressure supply line
26
. In this embodiment, valve body
19
also defines a low pressure vent
21
and a low pressure drain
22
. These two low pressure openings communicate with low pressure fluid reservoir
14
via a low pressure passage
27
. An armature cavity vent
23
is also included to channel actuating fluid that finds its way into electrical activating device
16
back to reservoir
14
.
Referring now to
FIG. 2
there is shown a diagrammatic representation of a hydraulically actuated fuel injector
30
according to the present invention. Fuel injector
30
includes an injector body
31
made up of various components that are attached to one another in a manner well known in the art and positioned as they would be just prior to an injection event. Actuation fluid can flow into a high pressure actuation fluid passage
52
that is defined by injector body
31
via an actuation fluid inlet
20
and high pressure supply line
26
from the source of high pressure fluid
13
. At the end of an injection event, actuation fluid can flow out of a low pressure passage
50
that is defined by injector body
31
via an actuation fluid drain
22
into low pressure fluid reservoir
14
. Injector body
31
also defines a low pressure passage
51
that is in constant fluid communication with low pressure vent
21
. While a number of different fluids could be used as actuation fluid, the present invention preferably utilizes engine lubricating oil.
Fuel injector
30
is controlled in operation by a control valve
12
that includes an electrical actuator
16
which is preferably a solenoid
40
, but could also be another suitable device such as a piezoelectric actuator. Control valve
12
is positioned in injector body
31
and attached by fasteners
35
, which are preferably bolts but could be another suitable attachment device. Solenoid
40
includes a coil
42
and an armature
43
that is attached to a pilot valve member
45
. Pilot valve member
45
is moveable within injector body
31
between a first position in which it closes a high pressure seat
47
and a second position in which it closes a low pressure seat
46
. Injector body
31
also defines a variable pressure passage
56
that opens into the space between low pressure seat
46
and high pressure seat
47
. Prior to an injection event, when solenoid
40
is de-energized, pilot valve member
45
is biased by a spring
48
to close low pressure seat
46
which opens variable pressure passage
56
to fluid communication with high pressure actuation fluid passage
52
via high pressure passage
57
. When solenoid
40
is energized, armature
43
moves pilot valve member
45
upward to close high pressure seat
47
, which closes variable pressure passage
56
to high pressure actuation fluid passage
52
and fluidly connects it to low pressure passage
51
.
A center feed valve member
60
is positioned within fuel injector
30
and includes a number of surfaces that are exposed to fluid pressure in variable pressure passage
56
, high pressure actuation fluid passage
57
and low pressure passage
51
. While valve member
60
has been illustrated as a spool valve member, it should be appreciated that another valve member, such as a poppet valve, could be substituted. Valve member
60
is movable between a first, retracted position and a second, advanced position, and is biased to the second, upward position by a biasing spring
70
that is positioned within a spring chamber
75
, which is in fluid communication with variable pressure passage
56
via branch passage
58
. Spring chamber
75
is defined by valve member
60
and injector body
31
. Valve member
60
includes a control pressure surface
66
that is exposed to fluid pressure in spring chamber
75
. Valve member
60
also includes a low pressure surface
61
that is continuously exposed to low pressure from low pressure vent
21
via low pressure passage
51
. Valve member
60
also includes a high pressure surface
62
that is continuously exposed to high pressure in high pressure passage
53
via high pressure passage
57
, high pressure actuation fluid passage
52
and actuation fluid inlet
20
. An internal passage
63
is defined by valve member
60
and opens through an end
67
into an actuation fluid cavity
72
. End
67
is a portion of a closing hydraulic surface
68
exposed to fluid pressure within actuation fluid cavity
72
. Closing hydraulic surface
68
is preferably oriented such that a pressure applied to this surface will produce a force on valve member
60
toward the upward, biased position. Therefore, at the end of an injection event, when pressure in actuation fluid cavity
72
is high, the fluid pressure within actuation fluid cavity
72
creates a hydraulic boost that helps move valve member
60
toward its upward position.
This feature of the present invention helps to eliminate secondary injections without the need for an additional valve member and/or additional plumbing. As an illustration, there are situations when needle valve member
105
closes nozzle outlet
112
while piston
80
and plunger
83
are still moving downward. This abrupt closure of nozzle outlet
112
can lead to an abrupt pressure increase in actuation fluid cavity
72
, termed a pressure spike in the art. One previous injector, the subject of U.S. Pat. No. 5,682,858 to Chen et al., included a pressure spike valve and a pressure relief passage that would open the actuation fluid cavity to an additional drain at the end of an injection event. This introduction of an additional drain would help prevent the pressure acting on the opening hydraulic surface of the needle valve member from once again achieving a valve opening pressure and lifting the needle valve member for a secondary injection. However, by creating a hydraulic boost to quickly move valve member
60
to open actuation fluid cavity
72
to low pressure passage
50
, the present invention can relieve the pressure on a needle valve member
105
more quickly by reducing pressure in actuation fluid cavity
72
without the need for additional components. In this manner, the present invention can increase the efficiency of fuel injector
30
while decreasing the number of components included in injector body
31
.
Returning now to valve member
60
, it also defines at least one radial passage
64
that fluidly connects internal passage
63
to an annulus
65
that is included on valve member
60
. When valve member
60
is in the upward, biased position, annulus
65
opens internal passage
63
to low pressure passage
50
. In this position, actuation fluid in actuation fluid cavity
72
can drain into low pressure reservoir
14
via actuation fluid drain
22
. When valve member
60
is in the downward position, annulus
65
opens internal passage
63
to high pressure actuation passage
52
, thereby allowing high pressure actuation fluid to flow through flow passage
54
and enter actuation fluid cavity
72
via internal passage
63
. It should be appreciated that because valve member
60
preferably moves such a small distance, on the order of microns, annulus
65
should be sized just slightly larger than the distance between high pressure actuation passage
52
and low pressure passage
50
to allow one or the other to be opened to flow passage
54
during the positioning of valve member
60
.
As illustrated in
FIG. 2
, the various surfaces of valve member
60
are sized and positioned to allow valve member
60
to be hydraulically balanced when solenoid
40
is de-energized. For instance, low pressure surface
61
has an effective area that is about equal in size to oppositely oriented closing hydraulic surface
68
. Similarly, high pressure surface
62
is oriented opposite control pressure surface
66
and has an effective area that is about equal to that of control pressure surface
66
. Because of this symmetry and orientation, when high pressure is acting on both control pressure surface
66
and high pressure surface
62
, as when solenoid
40
is de-energized, valve member
60
is hydraulically balanced and biased to its first retracted upward position only by biasing spring
70
. While it is preferable to size the various surfaces of valve
60
such that it is hydraulically balanced, it should be appreciated that these surface areas could be unequal and valve member
60
would still perform adequately.
For instance, a change in the areas of the various surfaces of valve member
60
might be desirable in order to eliminate the need for biasing spring
70
. If the effective area of control pressure surface
66
was increased to much greater than that of high pressure surface
62
, valve member
60
would no longer be hydraulically balanced when solenoid
40
is de-energized. Given these geometric characteristics, prior to an injection event, high pressure in spring chamber
75
would prevail and valve member
60
would be hydraulically biased toward the upward position, thus creating a hydraulic biasing force and eliminating the need for biasing spring
70
. Thus, the present invention contemplates both hydraulic and mechanical biasers.
Returning now to valve member
60
, it is guided in a lower guide bore
77
defined by a sleeve
79
. An upper clearance area
73
is located between valve member
60
and injector body
31
above annulus
65
. It should be appreciated that upper clearance area
73
should be relatively tight to allow valve member
60
to perform as desired and to ensure continuous fluid isolation of low pressure surface
61
and high pressure surface
62
.
Returning now to fuel injector
30
, injector body
31
also includes a reciprocating pumping element, piston
80
, which can move between an upward position, as shown, and a downward advanced position. Piston
80
is biased toward its upward position by a return spring
82
. Connected to piston
80
is a plunger
83
. While piston
80
, plunger
83
and valve member
60
have been shown sharing a common centerline
33
, it should be appreciated that this is not necessary. As with piston
80
, plunger
83
is biased toward its upward position by return spring
82
. Piston
80
advances due to the hydraulic pressure force exerted on a hydraulic surface
81
which is exposed to fluid pressure in actuation fluid cavity
72
. When piston
80
begins to advance, plunger
83
advances in a corresponding fashion and acts as the hydraulic means for pressurizing fuel within a fuel pressurization chamber
85
that is connected to a fuel inlet
90
past a ball check valve
95
. Fuel inlet
90
is connected to a source of fuel
92
via a fuel supply passage
91
. When plunger
83
is returning to its upward position, fuel is drawn into fuel pressurization chamber
85
past check valve
95
. During an injection event as plunger
83
moves toward its downward position, check valve
95
is closed and plunger
83
can act to compress fuel within fuel pressurization chamber
85
. Fuel pressurization chamber
85
is fluidly connected to a nozzle outlet
112
via a nozzle supply passage
108
.
A direct control needle valve
100
is positioned in injector body
31
and includes a needle valve member
105
that is movable between a first position, in which nozzle outlet
112
is open, and a downward second position in which nozzle outlet
112
is blocked. Needle valve member
105
is mechanically biased toward its downward closed position by a biasing spring
98
. Needle valve member
105
includes opening hydraulic surfaces
102
that are exposed to fluid pressure within a nozzle chamber
110
and a closing hydraulic surface
104
that is exposed to fluid pressure within a needle control chamber
101
. As illustrated in
FIG. 2
, needle control chamber
101
is in fluid communication with variable pressure passage
56
. Therefore, closing hydraulic surface
104
is exposed to high pressure passage
52
when solenoid
40
is de-energized and pilot valve member
45
is positioned to close low pressure seat
46
. Similarly, closing hydraulic surface
104
is exposed to low pressure passage
51
when solenoid
40
is energized and pilot valve member
45
is closing high pressure seat
47
.
Closing hydraulic surface
104
and opening hydraulic surfaces
102
are sized such that even when a valve opening pressure is attained in nozzle chamber
110
, needle valve member
105
will not move against the action of biasing spring
98
when needle control chamber
101
is exposed to high pressure in variable pressure passage
56
. In a similar manner, once solenoid
40
is de-energized at the end of an injection event, the high pressure in needle control chamber
101
will act to quickly move needle valve member
105
to close nozzle outlet
112
and end the injection event. Additionally, because closing hydraulic surface
104
has a larger effective area than opening hydraulic surfaces
102
, once solenoid
40
is de-energized, the high pressure acting on closing hydraulic surface
104
will prevent needle valve member
105
from re-opening nozzle outlet
112
and injecting additional fuel into the combustion space. However, it should be appreciated that the relative sizes of closing hydraulic surface
104
and opening hydraulic surfaces
102
and the strength of biasing spring
98
should be such that when closing hydraulic surface
104
is exposed to low pressure in variable pressure passage
56
, the high pressure acting on opening hydraulic surfaces
102
should be sufficient to move needle valve member upward against the force of biasing spring
98
to open nozzle outlet
112
.
INDUSTRIAL APPLICABILITY
Prior to the start of an injection event, low pressure in fuel pressurization chamber
85
prevails, plunger
83
is in its retracted position, pilot valve member
45
is positioned to close low pressure seat
46
and needle valve member
105
is in its biased position closing nozzle outlet
112
. Spring chamber
75
is in fluid communication with high pressure actuation fluid passage
52
via variable pressure passage
56
and actuation fluid cavity
72
is in fluid communication with low pressure passage
50
via internal passage
63
and radial passages
64
. Valve member
60
is hydraulically balanced and biased toward its upward position by biasing spring
70
. Recall that when valve member
60
is in this position, closing hydraulic surface
67
is exposed to low pressure in low pressure passage
51
via internal passage
63
, radial passages
64
and annulus
65
. The injection event is initiated by activation of solenoid
40
, which causes armature
43
to lift pilot valve member
45
to close high pressure seat
47
.
When pilot valve member
45
closes high pressure seat
47
, variable pressure passage
56
becomes fluidly connected to low pressure passage
50
. This causes a dramatic drop in pressure in both spring chamber
75
and in needle control chamber
101
. The drop in pressure in spring chamber
75
results in a hydraulic imbalance of the pressures acting on valve member
60
. Because low pressure is now acting on low pressure surface
61
, control pressure surface
66
, and closing hydraulic surface
67
, the high pressure acting on high pressure surface
62
is sufficient to move valve member
60
downward against the action of biasing spring
70
. As valve member
60
advances, annulus
65
moves out of contact with low pressure passage
50
and into contact with high pressure actuation fluid passage
52
. This movement allows high pressure actuation fluid to flow into flow passage
54
through radial passages
64
and internal passage
63
and into actuation fluid cavity
72
.
When actuation fluid cavity
72
becomes fluidly connected to high pressure actuation fluid passage
52
, the high pressure acting on hydraulic surface
81
causes piston
80
to move downward against the action of biasing spring
82
. This downward movement of piston
81
results in a corresponding downward movement of plunger
83
. The downward movement of plunger
83
closes check valve
95
and raises the pressure of the fuel within fuel pressurization chamber
85
, nozzle supply passage
108
and nozzle chamber
110
. Recall that low pressure is acting on closing hydraulic surface
104
because needle control chamber
101
is fluidly connected to low pressure passage
51
via variable pressure passage
56
. The increasing pressure of the fuel within nozzle chamber
110
acts on opening hydraulic surfaces
102
of needle valve member
105
. When the pressure exerted on opening hydraulic surfaces
102
exceeds a valve opening pressure, needle valve member
105
is lifted against the action of biasing spring
98
, and fuel is allowed to spray into the combustion chamber from nozzle outlet
112
.
In addition to these singular injections, the present invention can be used to create split injections without the need for additional components. The mass properties and other engineering factors, such as the strength of spring
70
, of valve member
60
cause it to react to the de-activation of solenoid
40
much slower than pilot valve member
45
or needle valve member
105
. If a split injection is desired, this sluggish nature can be exploited to produce such an injection. For instance, at the end of the first portion of the split injection, solenoid
40
would be de-energized, causing pilot valve member
45
to quickly open high pressure seat
47
under the force of high pressure liquid in high pressure passage
52
. Once high pressure seat
47
is opened, variable pressure passage
56
would be fluidly connected to high pressure inlet
20
, and would begin to deliver high pressure fluid to needle control chamber
101
. This high pressure acting on closing hydraulic surface
104
would abruptly close needle valve member
105
to end the first portion of the injection. In the meantime, valve member
60
would begin it's sluggish movement toward its biased position under the action of biasing spring
70
. However, before valve member
60
could advance far enough to close actuation fluid cavity
72
to high pressure passage
52
via internal passage
63
, solenoid
40
could again be energized causing pilot valve member
45
to open variable pressure passage
56
to low pressure passage
50
. Because valve member
60
reacted slower than pilot valve member
45
and needle valve member
105
, pressure in actuation fluid cavity
72
was never relieved, and needle valve member
105
could open with fuel pressure at a substantially higher pressure than valve opening pressure to create an abrupt beginning, or square injection or the second portion of the split injection. Thus, the present invention allows for more versatile use of fuel injector
30
without the need for additional components and passageways.
Returning to the injection event, shortly before the desired amount of fuel has been injected into the combustion space, current to solenoid
40
is ended to end the injection event. Solenoid
40
is de-energized and pilot valve member
45
moves under the action of spring
48
to close low pressure seat
46
which in turn closes variable pressure passage
56
from fluid communication with low pressure passage
51
, and fluidly connects it to high pressure passage
52
. Variable pressure passage
56
now delivers high pressure actuation fluid to both spring chamber
75
and needle control chamber
101
. The high pressure within needle control chamber
101
acts on closing hydraulic surface
104
and causes needle valve member
105
to move to its downward, closed position to close nozzle outlet
112
. Also, because high pressure is now acting on control pressure surface
66
and end surface
68
, valve member
60
starts moving toward its biased, upward position under the action of biasing spring
70
and the hydraulic pressure acting on end surface
68
. Recall that because of the high pressure in actuation fluid cavity
72
, valve member
60
is given a hydraulic boost toward the upward, biased position.
As valve member
60
moves toward its upward position, but prior to the opening of low pressure passage
50
by annulus
65
, piston
80
and plunger
83
stop their downward decent. Once annulus
65
moves out of contact with high pressure actuation fluid passage
52
and opens radial passages
64
to low pressure passage
50
, flow passage
54
and actuation fluid cavity
72
are open to low pressure passage
50
and low pressure drain
22
via internal passage
63
. Because hydraulic surface
81
is now exposed to low pressure in actuation fluid cavity
72
, piston
80
and plunger
83
are allowed to move toward their upward, biased positions under the action of biasing spring
82
. This upward movement of plunger
83
relieves the pressure on fuel within fuel pressurization chamber
85
and causes a corresponding drop in pressure nozzle supply passage
108
and nozzle chamber
110
.
Between injection events various components of injector body
31
begin to reset themselves in preparation for the next injection event. Because the pressure acting on piston
80
and plunger
83
has dropped, return spring
82
moves piston
80
and plunger
83
back to their retracted positions. The retracting movement of plunger
83
causes fuel from fuel inlet
90
to be pulled into fuel pressurization chamber
85
via fuel supply passage
91
.
The present invention reorganizes the various passageways in a fuel injector to allow the injector package to be reduced in both length and diameter. This is accomplished both by the movement of certain passageways toward the center of the injector and by the elimination of various valve components such as the pressure relief valve of the Chen injector. This elimination of components not only allows the injector to be reduced in size, but also reduces that number of parts that inherently increase complexity and reduce reliability of the fuel injector. The present invention also reduces the likelihood of secondary injections by creating a hydraulic boost that acts to hasten the closure of the valve member at the end of the injection event. Finally, because the high pressure passage is much closer to the center of the fuel injector, there is more room available for assembling hydraulically actuated fuel injectors with conventional fasteners, such as bolts.
It should be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present invention in any way. For instance, while the pilot valve, spool valve and reciprocating piston have all been illustrated as having a common centerline, this need not be the case. Further, while the present invention has been described utilizing a hydraulically balanced spool valve, it should be appreciated that the spool valve does not need to be hydraulically balanced. Additionally, it should be appreciated that while the valve member of the present invention has been illustrated using a top hat, the present invention could perform adequately without this feature. Thus, those skilled in the art will appreciate the various modifications could be made to the disclosed embodiments without departing from the intended scope of the present invention, which is defined in terms of the claims set forth below.
Claims
- 1. A control valve comprising:a valve body defining a high pressure passage, a low pressure passage and a flow passage; a valve member positioned in said valve body and having an end and defining an internal passage that opens through said end, and including a closing hydraulic surface exposed to fluid pressure in said flow passage, and being movable between a first position at which said high pressure passage is open to said flow passage via said internal passage, and a second position at which said low pressure passage is open to said flow passage; and said closing hydraulic surface being oriented such that pressure applied to said closing hydraulic surface produces a force on said valve member in a direction toward said second position.
- 2. The control valve of claim 1 further comprising a biaser operably positioned in said valve body to bias said valve member toward said second position.
- 3. The control valve of claim 1 wherein said valve member includes a control pressure surface; anda pilot member positioned in said valve body and being movable between a first position at which said control pressure surface is exposed to pressure in said low pressure passage, and a second position at which said control pressure surface is exposed to pressure in said high pressure passage.
- 4. The control valve of claim 1 wherein said valve member is a spool valve member.
- 5. The control valve of claim 1 wherein said valve member includes a control pressure surface in opposition to a high pressure surface that is exposed to fluid pressure in said high pressure passage; anda spring compressed between said control pressure surface and said valve body.
- 6. The control valve of claim 5 further comprising a pilot member positioned in said valve body and being movable between a first position at which said control pressure surface is exposed to pressure in said low pressure passage, and a second position at which said control pressure surface is exposed to pressure in said high pressure passage.
- 7. A hydraulically actuated device comprising:a valve body defining a high pressure passage, a low pressure passage and a flow passage; a source of high pressure fluid connected to said high pressure passage; a low pressure reservoir connected to said low pressure passage; a reciprocating piston with a hydraulic surface exposed to fluid pressure in said flow passage; a valve member positioned in said valve body and having an end and defining an internal passage that opens through said end, and including a closing hydraulic surface exposed to fluid pressure in said flow passage, and being movable between a first position at which said high pressure passage is open to said flow passage via said internal passage, and a second position at which said low pressure passage is open to said flow passage; and said closing hydraulic surface being oriented such that pressure applied to said closing hydraulic surface produces a force on said valve member in a direction toward said second position.
- 8. The hydraulically actuated device of claim 7 wherein said valve member includes a control pressure surface; anda pilot member positioned in said valve body and being movable between a first position at which said control pressure surface is exposed to pressure in said low pressure passage, and a second position at which said control pressure surface is exposed to pressure in said high pressure passage.
- 9. The hydraulically actuated device of claim 8 wherein said valve member includes a high pressure surface that is exposed to fluid pressure in said high pressure passage; anda biaser operably positioned in said valve body to bias said valve member toward one of said first position and said second position.
- 10. The hydraulically actuated device of claim 9 wherein said biaser includes a spring compressed between said valve member and said valve body; andsaid valve member is a spool valve member.
- 11. The hydraulically actuated device of claim 10 wherein said high pressure surface is oriented in opposition to said closing hydraulic surface and said control pressure surface.
- 12. The hydraulically actuated device of claim 11 wherein said high pressure surface has a first effective area; andsaid control pressure surface has a second effective area that is about equal to said first effective area.
- 13. The hydraulically actuated device of claim 12 wherein said valve member defines an annulus and at least one radial passage extending between said annulus and said internal passage.
- 14. The hydraulically actuated device of claim 13 wherein said valve member includes a low pressure surface exposed to fluid pressure in said low pressure passage.
- 15. A hydraulically actuated fuel injector comprising:an injector body defining an actuation fluid inlet, an actuation fluid drain, an actuation fluid cavity and a nozzle outlet; a valve member positioned in said injector body and having an end and defining an internal passage that opens through said end, and including a closing hydraulic surface exposed to fluid pressure in said actuation fluid cavity and a control pressure surface, and being movable between a first position at which said actuation fluid inlet is open to said actuation fluid cavity via said internal passage, and a second position at which said actuation fluid drain is open to said actuation fluid cavity; said closing hydraulic surface being oriented such that pressure applied to said closing hydraulic surface produces a force on said valve member in a direction toward said second position a reciprocating pumping element positioned in said injector body and including a pumping hydraulic surface exposed to pressure in said actuation fluid cavity; a pilot member positioned in said injector body and being movable between a first position at which said control pressure surface is exposed to pressure in actuation fluid drain, and a second position at which said control pressure surface is exposed to pressure in said actuation fluid inlet.
- 16. The hydraulically actuated fuel injector of claim 15 further comprising a direct control needle valve positioned in said injector body.
- 17. The hydraulically actuated fuel injector of claim 16 wherein said injector body defines a fuel inlet connected to a source of low pressure fuel; andsaid actuation fluid inlet is connected to a source of high pressure actuation fluid.
- 18. The hydraulically actuated fuel injector of claim 17 further comprising a spring compressed between said valve member and said injector body; andsaid valve member is a spool valve member.
- 19. The hydraulically actuated fuel injector of claim 18 wherein said valve member includes a high pressure surface exposed to fluid pressure in said actuation fluid inlet, and a low pressure surface exposed to fluid pressure in said actuation fluid drain;said high pressure surface having a first effective area about equal in size, but oriented in opposition to said control pressure surface; and said low pressure surface having a second effective area about equal in size, but oriented in opposition to said closing hydraulic surface.
- 20. The hydraulically actuated fuel injector of claim 19 wherein said internal passage and said pumping element share a common centerline.
US Referenced Citations (25)
Foreign Referenced Citations (2)
Number |
Date |
Country |
26 02 844 |
Aug 1977 |
DE |
1 328 959 |
Sep 1973 |
GB |