Information
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Patent Grant
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6394073
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Patent Number
6,394,073
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Date Filed
Thursday, August 26, 199924 years ago
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Date Issued
Tuesday, May 28, 200222 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
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CPC
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US Classifications
Field of Search
US
- 123 506
- 123 446
- 123 458
- 123 467
- 251 12907
- 251 12916
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International Classifications
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Abstract
A hydraulic valve with hydraulically assisted opening comprises a valve body that defines a fluid passage which includes an upstream segment and a downstream segment. Contained within the valve body is a moveable valve member which includes a hydraulic surface. The hydraulic surface is exposed to fluid pressure within the downstream segment of the fluid passage. When the valve member is in a closed position, the upstream segment of the fluid passage is closed to the downstream segment. The upstream segment is fluidly connected to the downstream segment when the valve member is away from the closed position.
Description
TECHNICAL FIELD
This invention relates generally to hydraulic valves, and more particularly to fuel injectors having spill valves with hydraulically assisted opening.
BACKGROUND ART
In many fuel injectors which utilize a spill valve to relieve fluid pressure in the fuel pressurization chamber, a swift opening of the spill valve is desirable. This is beneficial because the longer the spill valve remains in the closed position after an injection event, the longer various components, such as cam and rocker arm assemblies, spend pressurizing fuel as opposed to merely displacing it. In order to prevent excess consumption of engine energy by unnecessarily pressurizing fuel after injection has ended, engineers are always searching for a means to more quickly open the spill valve. A number of fuel injectors currently employ a spill valve to relieve pressure within the fuel pressurization chamber. In these previous fuel injectors, the spill valve must be capable of opening against the action of the hydraulic forces present in the fuel injector which tend to slow this movement to the open position. In these previous injectors, the spill valve spring preload was often low, which is generally not beneficial for spill valve opening. While these foregoing fuel injectors have performed impressively, there is room for improving the speed with which the spill valve opens.
The present invention is directed to overcoming one or more of the problems described above and to exploiting hydraulic forces for a more abrupt opening of the spill valve.
SUMMARY OF THE INVENTION
A hydraulic valve with hydraulically assisted opening comprises a valve body that defines a fluid passage which includes an upstream segment and a downstream segment. Contained within the valve body is a moveable valve member which includes a hydraulic surface. The hydraulic surface is exposed to fluid pressure within the downstream segment of the fluid passage. When the valve member is in a closed position, the upstream segment of the fluid passage is closed to the downstream segment. The upstream segment is fluidly connected to the downstream segment when the valve member is away from the closed position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a diagrammatic sectioned front view of a fuel injector according to the present invention.
FIG. 2
is a diagrammatic partial sectioned front view of the fuel injector of FIG.
1
.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to
FIGS. 1 and 2
, a fuel injector
10
includes an injector body
11
which includes a barrel
18
and a plurality of components attached to one another in a manner well known in the art. Barrel
18
defines a plunger bore
12
within which a plunger
13
is driven to reciprocate by some suitable means, such as hydraulic pressure or a cam driven tappet assembly, etc. A portion of plunger bore
12
and plunger
13
define a fuel pressurization chamber
14
that communicates with a nozzle outlet
70
via a nozzle supply passage
60
and a nozzle chamber
61
. Fuel pressurization chamber
14
can therefore act to inject liquid distillate diesel fuel into a designated combustion space. Injector body
11
defines a fuel inlet
16
and a low pressure drain
17
. Fuel can flow into injector body
11
from a fuel source
48
via a fuel supply line
43
, through fuel inlet
16
. Low pressure fuel exiting injector body
11
can flow through a low pressure passage
41
, via low pressure drain
17
, into a low pressure reservoir
46
.
When plunger
13
is undergoing its downward pumping stroke, pressure is unable to build in fuel pressurization chamber
14
while a spill valve assembly
30
is open. Spill valve assembly
20
, which is contained within injector body
11
, includes an electrical actuator
21
which is preferably a three position solenoid
22
, as shown in
FIGS. 1 and 2
, but could be another suitable device such as a piezoelectric actuator. Solenoid
22
includes an armature
23
which is operably connected to a spill valve member
30
. While spill valve member
30
has been shown as a poppet valve member, it should be appreciated by those skilled in the art that a different valve member, such as a spool valve member, could be substituted to accomplish similar results. Spill valve assembly
30
also includes a spill passage
36
that is defined by injector body
11
. Spill passage
36
is composed of two segments, an upstream segment
37
and a downstream segment
38
. A portion of downstream segment
38
is a turbulence chamber
39
. Spill valve member
30
includes a hydraulic surface
28
which is exposed to fluid pressure within turbulence chamber
39
. Also included on spill valve member
30
is a conical valve surface
26
which can contact a conical valve seat
25
of injector body
11
to close upstream segment
37
from downstream segment
38
. Thus, upstream segment
37
is separated from downstream segment
38
by conical valve seat
25
. Spill valve member
30
is moveable between a closed position, in which conical valve surface
26
and conical valve seat
25
are in contact, and an open position, in which conical valve surface
26
and conical valve seat
25
are out of contact.
Spill valve member
30
is normally biased away from its closed position by a biasing spring
35
, resulting in open fluid communication between upstream segment
37
and downstream segment
38
. Therefore, when solenoid
22
is de-energized, the force of biasing spring
35
prevails and fuel pressurization chamber
14
is open to low pressure reservoir
46
via low pressure passage
41
, upstream segment
37
and downstream segment
38
. Thus, when upstream segment
37
is open to downstream segment
38
, the fuel displaced from fuel pressurization chamber
14
is recirculated for later use, and pressure within fuel injector
10
is unable to build to the relatively high injection pressures. Conversely, when solenoid
22
is energized, armature
23
and spill valve member
30
are lifted against the action of biasing spring
35
to close conical valve seat
25
and fuel pressure in fuel pressurization chamber
14
, nozzle supply passage
60
and nozzle chamber
61
can rise rapidly. Thus, in order to raise fuel pressure to initiate an injection event, solenoid
22
must be energized to lift spill valve member
30
to close upstream segment
37
from downstream segment
38
.
When solenoid
22
is first energized, armature
23
begins to move spill valve member
30
upward against the action of biasing spring
35
. As spill valve member
30
moves upward toward the closed position, a small amount of fuel within turbulence chamber
39
can be evacuated via a vent passage
45
. Fuel exiting vent passage
45
is channeled into downstream segment
38
and can then flow into low pressure reservoir
46
. Vent passage
45
should be large enough to allow a sufficient amount of fuel to be removed from turbulence chamber
39
to allow solenoid
22
to move spill valve member
30
upward against the action of biasing spring
35
. The movement of spill valve member
30
is also dependent upon the dimensions of a spill valve clearance
34
located between spill valve member
30
and barrel
18
. Spill valve clearance
34
should be tight enough to prevent spill valve member
30
from opening too quickly after solenoid
22
is de-energized. This undesirable effect could result in spill valve member
30
rebounding upward under the action of spring
52
and possibly reclosing. However, spill valve clearance
34
should not be so tight that a sufficient flow of fuel around spill valve member
30
is not possible.
Returning to fuel injector
10
, a direct control needle valve member
55
is movably mounted in injector body
11
between a first position, in which nozzle outlet
70
is open, and a downward second position in which nozzle outlet
70
is blocked. A needle biasing spring
65
normally biases needle valve member
55
toward a downward position to close nozzle outlet
70
. Needle valve member
55
includes an opening hydraulic surface
57
that is exposed to fluid pressure in nozzle chamber
61
. Needle valve member
55
also includes a closing hydraulic surface
54
which is exposed to fluid pressure in a needle control chamber
53
that is alternately connected to a high pressure passage
64
or a low pressure passage
63
.
When solenoid
22
is de-energized, or energized to its low current level there is insufficient force for a needle control valve member
50
to overcome the force of biasing spring
52
and move to a closed position. Therefore, when solenoid
22
is in one of these two settings, valve seat
51
remains open and needle control chamber
53
is in fluid communication with fuel pressurization chamber
14
via a high pressure passage
64
, past valve seat
51
. However, when solenoid
22
is energized to its high current level, needle control valve member
50
can lift to close valve seat
51
, thus fluidly connecting needle control chamber
53
to a low pressure area via a low pressure passage
63
and a leakage clearance
62
which exists between the outer surface of needle valve member
55
and an inner bore. Thus, when solenoid
22
is energized to its high current level, closing hydraulic surface
54
is exposed to low fluid pressure, which causes needle valve member
55
to behave as an ordinary spring biased check valve. However, closing hydraulic surface
54
should be preferably sized to hold needle valve member
55
in its closed position, even in the presence of high fuel pressures, when solenoid
22
is de-energized or energized to its lower level.
INDUSTRIAL APPLICABILITY
Prior to the start of an injection event, low pressure in fuel pressurization chamber
14
prevails and plunger
13
is in its retracted position, spill valve member
30
is biased toward its open position by the action of biasing spring
35
, upstream segment
37
is fluidly connected to downstream segment
38
, needle control valve member
50
is positioned to open valve seat
51
, and needle valve member
55
is in its seated position closing nozzle outlet
70
. The injection event is initiated by activation of solenoid
22
to its low current level. When solenoid
22
is activated to this low setting, armature
23
lifts spill valve member
30
to compress biasing spring
35
. At this current level, biasing spring
52
remains uncompressed beyond its preload, thus maintaining needle control valve member
50
in the open position. As armature
23
lifts spill valve member
30
toward the closed position, an amount of fuel in turbulence chamber
39
is evacuated through vent passage
45
to allow the force of solenoid
22
to overcome the pressure force of the fuel moving through spill valve clearance
34
. This evacuated fuel flows into low pressure reservoir
46
for recirculation. Armature
23
lifts spill valve member
30
to close conical valve seat
25
, which in turn closes upstream segment
37
from downstream segment
38
. Once upstream segment
37
is no longer in fluid communication with downstream segment
38
there is a resulting rapid rise in fuel pressure in fuel pressurization chamber
14
, nozzle supply passage
60
, high pressure passage
64
, and nozzle chamber
61
. However, because solenoid
22
remains energized at its lower setting, the building high pressure in high pressure passage
64
acts upon closing hydraulic surface
54
to hold needle valve member
55
in its downward closed position.
When fuel spray into the combustion chamber is to commence, a signal is sent to solenoid
22
, which is then energized to its higher setting. Once this occurs, spill valve member
30
remains in its closed position, but needle control valve member
50
moves from its open position to close valve seat
51
to relieve the high pressure in needle control chamber
53
. Relatively high fuel pressure in nozzle chamber
61
then lifts needle valve member
55
upward to its open position to commence the spraying of fuel out of nozzle outlet
70
. Shortly before the desired amount of fuel has been injected, a signal is sent to solenoid
22
to end the injection event. Solenoid
22
is de-energized and spill valve member
30
returns downward to the open position under the action of biasing spring
35
and the hydraulic assist force acting on surface
28
, and needle control valve member
50
returns to its downward position to open valve seat
51
.
Between injection events various components of injector body
11
begin to reset themselves in preparation for the next injection event. Because the pressure acting on plunger
13
has dropped, a return spring moves plunger
13
back to its retracted position. The retracting movement of plunger
13
causes fuel from fuel inlet
16
to be pulled into fuel pressurization chamber
14
through fuel supply line
43
.
The present invention exploits the hydraulic pressure within turbulence chamber
39
to aid the downward movement of spill valve member
30
to open spill passage
36
. When solenoid
22
is first de-energized and upstream segment
37
is still closed to downstream segment
38
, spill valve member
30
is hydraulically balanced, having low pressure both above and below it. In this condition, the spring force of biasing spring
35
is sufficient to move spill valve member
30
away from its closed position, seated at conical valve seat
25
. High pressure fuel traveling from fuel pressurization chamber
14
through upstream segment
37
possesses a certain amount of dynamic pressure. Turbulence chamber
39
should be shaped and positioned such that an amount of this dynamic pressure is converted into stagnation pressure. The stagnation pressure of the fuel within turbulence chamber
39
can then aid in moving spill valve member
30
away from the closed position, thus creating a relatively quick relief of pressure to low pressure drain
17
. In this manner, the present invention can help to relieve pressure on spill valve member
30
which will reduce the amount of engine energy consumed unnecessarily pressurizing fuel after an injection event by exploiting the hydraulic forces within the fuel injector to provide quick spill of residual pressure.
It should be understood that the above description is intended only to illustrate the concepts of the present invention, and is not intended to in any way limit the potential scope of the present invention. For instance, while the spill valve member has been shown as a poppet valve, a spool valve member could also be used. Further, while the present invention utilizes a biasing spring to bias the spill valve member toward the open position and an electrical actuator to move the spill valve member toward the closed position, it should be appreciated that the functions of these two components could be reversed. Additionally, while the spill valve member in the present invention is hydraulically balanced, the invention could still perform if the spill valve were not hydraulically balanced. Thus, various modifications could be made without departing from the intended spirit and scope of the invention as defined by the claims below.
Claims
- 1. A hydraulic valve with hydraulically assisted opening comprising:a valve body defining a fluid passage, said fluid passage having an upstream segment and a downstream segment; a moveable valve member at least partially positioned within said valve body, an end of said valve member including a hydraulic surface that defines a portion of said downstream segment; said upstream segment of said fluid passage being closed to said downstream segment when said valve member is in a closed position; said upstream segment of said fluid passage being fluidly connected to said downstream segment when said valve member is away from said closed position; an electrical actuator attached to said valve body and being operable in an energized state to move said valve member toward said closed position; a spring operably positioned to bias said valve member toward a fully open position; said upstream segment of said fluid passage is fluidly connected to a source of high pressure fluid; said downstream segment of said fluid passage is fluidly connected to a low pressure reservoir; a portion of said downstream segment is a turbulence chamber; said hydraulic surface is exposed to fluid pressure in said turbulence chamber; and an amount of fuel flowing from said upstream segment to said downstream segment having a dynamic pressure, said turbulence chamber being shaped and positioned to convert a portion of said dynamic pressure into a stagnation pressure.
- 2. The hydraulic valve of claim 1 wherein said valve member is a poppet valve member;said upstream segment is separated from said downstream segment by a conical valve seat; and said upstream segment is closed to said downstream segment when said poppet valve member is seated in said conical valve seat.
- 3. A fuel injector comprising:an injector body defining a spill passage, said spill passage having an upstream segment and a downstream segment; a moveable valve member at least partially positioned within said injector body, an end of said valve member including a hydraulic surface that defines a portion of said downstream segment; said upstream segment of said spill passage being closed to said downstream segment when said valve member is in a closed position; said upstream segment of said spill passage being fluidly connected to said downstream segment when said valve member is away from said closed position; an electrical actuator attached to said injector body and being operable in an energized state to move said valve member toward said closed position; a spring operably positioned to bias said valve member toward a fully open position; said upstream segment of said spill passage is fluidly connected to a source of high pressure fuel; said downstream segment of said spill passage is fluidly connected to a low pressure reservoir; a portion of said downstream segment is a turbulence chamber; said hydraulic surface is exposed to fluid pressure in said turbulence chamber; and an amount of fluid flowing from said upstream segment to said downstream segment having a dynamic pressure, said turbulence chamber being shaped and positioned to convert a portion of said dynamic pressure into a stagnation pressure.
- 4. The fuel injector of claim 3 wherein said valve member is a poppet valve member;said upstream segment is separated from said downstream segment by a conical valve seat; and said upstream segment is closed to said downstream segment when said poppet valve member is seated in said conical valve seat.
- 5. The fuel injector of claim 4 wherein said amount of fluid is an amount of fuel.
- 6. The fuel injector of claim 5 including a direct control needle valve.
- 7. A method of operating a spill valve, comprising the steps of:opening an upstream segment of a fluid passage to a downstream segment of said fluid passage, at least in part by moving a valve member from a closed position toward a fully open position; assisting movement of said valve member to said fully open position, at least in part by exposing an opening hydraulic surface of said valve member to fluid pressure in a turbulence chamber that is a portion of said downstream segment; said assisting step includes a step of converting dynamic pressure of fluid in said downstream segment to stagnation pressure in said turbulence chamber; said opening step includes the steps of mechanically biasing said valve member away from said closed position, and de-energizing an electrical actuator operably coupled to said valve member; and closing said upstream segment to said downstream segment, at least in part by energizing said electrical actuator.
- 8. The method of claim 7 including a step of connecting said upstream segment to a source of high pressure fluid and connecting said downstream segment to a low pressure reservoir.
US Referenced Citations (23)