Information
-
Patent Grant
-
6360960
-
Patent Number
6,360,960
-
Date Filed
Wednesday, May 17, 200024 years ago
-
Date Issued
Tuesday, March 26, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Scherbel; David A.
- Hwu; Davis
-
CPC
-
US Classifications
Field of Search
US
- 239 5
- 239 5851
- 239 5854
- 239 5855
- 239 5333
- 239 53311
- 239 53312
- 239 596
- 251 333
- 251 12921
-
International Classifications
-
Abstract
A fuel injector for use in a fuel injection system of an internal combustion engine is disclosed. The fuel injector includes a body, a needle, and a metering orifice. The body has a longitudinal axis and a valve seat. The valve seat has a beveled annular surface and a central opening therethrough. The central opening is formed by a generally cylindrical wall. The needle includes a first portion having a first cross sectional area and a second portion having a second cross-sectional area. The second portion includes a needle end face which extends generally perpendicular to the longitudinal axis. The needle is reciprocally located within the body along the longitudinal axis and is biased against the valve seat. The metering orifice is connected to a downstream end of the valve body. A fuel sac is generally formed by the metering orifice, the needle end face, and the cylindrical wall. A projection extends into the fuel sac, reducing a volume of the fuel sac. The projection extends from at least one of the needle end face and the metering orifice. A method of reducing unmetered fuel in a fuel injector by reducing sac volume is also disclosed.
Description
FIELD OF THE INVENTION
This invention relates to fuel injectors, and more particularly, to fuel injectors having a sac volume that minimizes residual fuel after metering.
BACKGROUND OF THE INVENTION
Fuel injectors are commonly employed in internal combustion engines to provide precise metering of fuel for introduction into each combustion chamber. Additionally, the fuel injector atomizes the fuel during injection, breaking the fuel into a large number of very small particles, increasing the surface area of the fuel being injected, and allowing the oxidizer, typically ambient air, to more thoroughly mix with the fuel prior to combustion. The precise metering and atomization of the fuel reduces combustion emissions and increases the fuel efficiency of the engine.
An electromagnetic fuel injector typically utilizes a solenoid assembly to supply an actuating force to a fuel metering valve. Typically, the fuel metering valve is a plunger style needle valve which reciprocates between a closed position, where the needle is seated in a valve seat to prevent fuel from escaping through a metering orifice into the combustion chamber, and an open position, where the needle is lifted from the valve seat, allowing fuel to discharge through the metering orifice for introduction into the combustion chamber.
Typically, a volumetric chamber or sac exists between the discharge tip of the needle and the metering orifice. Upon seating of the needle on the valve seat, a volume of fuel remains within the sac and tends to drain through openings in the metering orifice after the metered fuel has already been discharged through the metering orifice, typically during low manifold pressure, high injector tip temperature operating conditions. This discharge produces rich combustion which generates unwanted exhaust emissions and reduces the fuel efficiency of the engine. Some of the fuel, however, remains in the sac which vaporizes and causes rich/lean shifts and hot start issues which are undesirable.
It would be beneficial to develop a fuel injector in which the sac volume is minimized, reducing the amount of unmetered fuel in the sac after metering.
SUMMARY OF THE INVENTION
Briefly, the present invention provides a fuel injector for use in a fuel injection system of an internal combustion engine. The fuel injector includes a valve body, a valve seat, a metering orifice, a needle and a volume. The body has an inlet, an outlet and a longitudinal axis extending therethrough. The valve seat is located within the body and disposed proximate the outlet. The valve seat includes a valve seat orifice and a sealing surface surrounding the orifice. The metering orifice is connected to the body downstream of the valve seat. The needle is reciprocally located within the body along the longitudinal axis between a first position wherein the needle is displaced from the valve seat, allowing fuel flow past the needle, and a second position wherein the needle is biased against the valve seat, precluding fuel flow past the needle. The needle includes a first portion having a first cross-sectional area and a second portion having a second cross-sectional area. The second cross-sectional area is larger than the first cross-sectional area. The second portion includes an end face extending generally perpendicular to the longitudinal axis. The end face is located upstream of the valve seat orifice. The volume is generally defined by the metering orifice, the end face and the valve seat orifice when the needle is in the second position.
The present invention also provides a fuel injector for use in a fuel injection system of an internal combustion engine. The fuel injector comprises a valve body, a valve seat, a metering orifice, a needle, and a volume. The body has an inlet, an outlet and a longitudinal axis extending therethrough. The valve seat is located within the body and disposed proximate the outlet. The valve seat includes a valve seat orifice and a sealing surface surrounding the valve seat orifice. The metering orifice is connected to the body downstream of the valve seat. The needle is reciprocally located within the body along the longitudinal axis between a first position wherein the needle is displaced from the valve seat, allowing fuel flow past the needle, and a second position wherein the needle is biased against the valve seat, precluding fuel flow past the needle. The needle includes a first portion having a first cross-sectional area and a second portion having a second cross-sectional area. The second portion includes an end face extending generally perpendicular to the longitudinal axis. The volume is generally defined by the metering orifice, the end face and the valve seat orifice when the needle is in the second position. The metering orifice is spaced from the end face by a distance of between 100 microns and 250 microns.
The present invention also provides a method of reducing unmetered fuel in a fuel injector. The fuel injector including a valve seat, a needle, a volume, and a metering orifice. The method comprises the steps of providing a fuel injector; providing pressurized fuel to the fuel injector; opening the fuel injector by moving the needle off of the valve seat, thereby allowing the pressurized fuel to flow past the needle and the valve seat and through the volume and the metering orifice for ejection from the fuel injector; and closing the fuel injector by seating the needle against the valve seat, reducing the volume and fuel within the volume.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention. In the drawing:
FIG. 1
is a side view, in section, of a discharge end of a fuel injector according to a first embodiment of the present invention with a needle in a closed position;
FIG. 2
is a side view, in section, of a discharge end of a fuel injector according to a second embodiment of the present invention with a needle in a closed position;
FIG. 2A
is an enlarged view of the discharge end of the fuel injector of
FIG. 2
;
FIG. 3
is a side view, in section, of the discharge end of the fuel injector according to the second embodiment of the present invention with the needle in an open position;
FIG. 4
is a top plan view of a metering orifice used in the second embodiment; and
FIG. 5
is a side view, in section, of a discharge end of a fuel injector according to a third embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the drawings, like numerals are used to indicate like elements throughout.
FIG. 1
shows a sectional view of a first embodiment of a fuel injector
100
having a body
120
and a needle
140
. The body
120
includes a valve seat
127
having a central valve seat orifice
132
. The valve seat
127
includes a beveled seat surface
134
which slopes radially inwardly and downwardly toward the central orifice
132
oblique to a longitudinal axis
126
of the body
120
. The words “inwardly” and “outwardly” refer to directions towards and away from, respectively, the longitudinal axis of each embodiment of the injector in accordance with the present invention, and designated parts thereof.
The needle
140
reciprocates between an open position and a closed position along the longitudinal axis
126
of the body
120
. The needle
140
includes a generally spherical tip
142
which includes a generally planar end face
144
. However, those skilled in the art will recognize that the end face
144
need not be planar. The end face
144
is preferably generally perpendicular to the longitudinal axis
126
. In both the open and closed position, the end face
144
is located upstream of the valve seat orifice
132
. The spherical tip
142
matches the beveled seat surface
134
of the valve seat
130
when the needle
140
is in a closed position, as shown in
FIG. 1
, such that a valve contact face
146
of the spherical tip
142
engages the beveled valve seat surface
134
, forming a generally line contact seal between the spherical tip
142
and the beveled seat surface
134
. A metering orifice
150
is located at a downstream location of the body
120
, approximate to, but spaced from, the end face
144
. The words “upstream” and “downstream” designate flow directions in the drawings to which reference is made. The upstream side is toward the top of each drawing and the downstream side is toward the bottom of each drawing. The metering orifice
150
includes at least one, and preferably several, metering openings
152
which are radially spaced from the longitudinal axis
126
of the body
120
. Preferably, in the closed position, the top of the metering orifice
150
and the end face
144
are spaced from each other by between approximately 50 microns and 250 microns.
When the needle
140
is in an open position, the valve contact face
146
is raised above and separated from the beveled seat surface
134
, forming an annular opening therebetween, allowing pressurized fuel to flow therethrough and through the openings
152
in the metering orifice
150
to a combustion chamber (not shown) for combustion. Upon closing of the needle
140
so that the valve contact face
146
engages the beveled seat surface
134
, the flow of fuel through the injector
100
is cut off.
When the needle
140
is in a closed position, cutting off the flow of metered fuel, a volume or sac
160
is formed between the end face
144
, the metering orifice
150
, and the sides of the valve seat
130
. The sac
160
tends to retain a volume of fuel in the sac which vaporizes and causes rich/lean shifts and hot start issues which are undesirable.
A second embodiment of the present invention, shown in
FIGS. 2-4
, is a fuel injector
10
for use in a fuel injection system of an internal combustion engine. The injector
10
includes a body
20
, a valve seat
30
, a needle
40
having a projection
428
, a generally planar fuel metering orifice
50
, and a volume or sac
60
. Details of the operation of the fuel injector
10
in relation to the operation of the internal combustion engine (not shown) are well known and will not be described in detail herein, except as the operation relates to the present invention. Although the present invention is generally directed to injector valves for internal combustion engines, those skilled in the art will recognize from present disclosure that the present invention can be adapted for other applications in which precise metering of fluids is desired or required.
The body
20
has an upstream or inlet end
210
and a downstream or outlet end
220
. The body
20
includes an armature
240
as shown in
FIGS. 2
,
2
A. The needle
40
is connected to the armature
240
. An electromagnetic coil (not shown) located within the body
20
is selectively energized and deenergized to reciprocate the armature
240
and the needle
40
within the body
20
. The body
20
further includes a body shell
250
which is constructed from ferromagnetic material and which forms part of a magnetic circuit which operates the magnetic coil. The body shell
250
partially surrounds a valve body
260
which includes a valve body chamber
262
. The valve body chamber
262
extends through a central longitudinal portion of the body
20
along a longitudinal axis
270
extending therethrough and is formed by an interior valve body wall
264
. A needle guide
280
having a central needle guide opening
282
and a plurality of radially spaced fuel flow openings
284
is located within the valve body chamber
262
proximate to the downstream end
220
of the body
20
. The needle guide
280
assists in maintaining reciprocation of the needle
40
along the longitudinal axis
270
. An overmold
290
constructed of a dielectric material, preferably a plastic or other suitable material, encompasses the body shell
250
. An o-ring
12
is located around the outer circumference of the valve body
260
to seat the injector
10
in an internal combustion engine (not shown).
The valve seat
30
is located within the valve body chamber
262
proximate to the outlet end
220
between the needle guide
280
and the discharge end
220
. The valve seat
30
includes a passage or orifice
320
which extends generally along the longitudinal axis
270
of the body
20
and is formed by a generally cylindrical wall
322
. Preferably a center
321
of the orifice
320
is on the longitudinal axis
270
. The valve seat
30
also includes a beveled sealing surface
330
which surrounds the orifice
320
and tapers radially downward and inward toward the orifice
320
such that the sealing surface
330
is oblique to the longitudinal axis
270
.
Although not shown, those skilled in the art will recognize that an o-ring can seal the interface between the valve seat
30
and the valve body
260
. Although this is a preferred method of sealing the interface, those skilled in the art will also recognize that the o-ring may be omitted, and a hermetic weld (not shown) can be used to seal the interface.
The needle
40
is reciprocally located within the valve body chamber
262
generally along the longitudinal axis
270
of the body
20
. The needle
40
is reciprocable between a first, or open, position wherein the needle
40
is displaced from the valve seat
30
(as shown in FIG.
3
), allowing pressurized fuel to flow downstream past the needle
40
, and a second, or closed, position wherein the needle
40
is biased against the valve seat
30
(as shown in
FIGS. 2
,
2
A) by a biasing element (not shown), preferably a spring, precluding fuel flow past the needle
40
.
Referring now to
FIGS. 2
,
2
A, the needle
40
includes a first portion
410
which has a first cross-sectional area A
1
and a second portion
420
which has a second cross-sectional area A
2
. The second portion
420
includes a generally spherical contact face
422
which is sized to sealingly engage the beveled valve sealing surface
330
when the needle
40
is in the closed position. The spherical contact face
422
engages the beveled valve sealing surface
330
to provide a generally line contact therebetween. A rounded surface
424
, shown in enlarged
FIG. 2A
, connects the contact face
422
with a planar end face
426
located at a downstream tip of the needle
40
. The end face
426
is preferably generally perpendicular to the longitudinal axis
270
of the body
20
. A projection
428
extends from the end face
426
toward the discharge end
220
of the body
20
. Preferably, the projection
428
is generally a circular cylinder in shape and has a mid-point on the longitudinal axis
270
of the body
20
, although those skilled in the art will recognize that the projection
428
can be other shapes as well. The projection
428
includes a generally planar end surface
429
which is preferably generally perpendicular to the longitudinal axis
270
. The projection
428
is located inward of the interface between the rounded surface
424
and the end face
426
, forming the end face
426
in a generally annular shape around the projection
428
. Preferably, the projection
428
encompasses approximately between 50% and 75% of the surface of the end face
426
.
Preferably, both the first and second cross-sectional areas A
1
, A
2
are circular, although those skilled in the art will recognize that the first and second cross-sectional areas A
1
, A
2
can be other shapes as well. This configuration reduces the mass of the needle
40
while retaining a relatively large sealing diameter of the valve contact face
422
so as to provide a relatively generous sealing area of the needle
40
for engagement of the valve contact face
422
when the needle
40
is in the closed position. The increased cross-sectional area A
2
of the needle
40
acts as a larger bearing surface during operation of the needle
40
, thereby improving the wear resistance of the internal surface of the central needle guide opening
282
. The improved wear resistance of the internal surface of the central needle guide opening
282
is due to reduced loading compared to that of a conventional base valve guide diameter which was used with prior art needles of a generally constant cross-sectional area. For example, a typical prior art needle will have a substantially continuous cylindrically shaped shaft which terminates at an end portion wherein the cross-sectional area at the upper portion of the needle may be twice as much as the cross-sectional area A
2
of the needle
40
shown in
FIG. 2. A
drawback to the larger cross-sectional area A
2
is that a larger sealing diameter between the valve seat
30
and the needle
40
is required, forming a larger sac
60
.
The needle
40
is reciprocable between the closed position (shown in
FIGS. 2
,
2
A) and the open position (shown in FIG.
3
). When the needle
40
is in the open position, a generally annular channel
430
is formed between the valve contact face
422
and the valve sealing surface
330
.
The metering orifice
50
is located within the valve body chamber
262
and is connected to the body
20
, downstream of the valve seat
30
. The metering orifice
50
has an interior face
510
facing the valve seat
30
and the needle
40
, and an exterior face
520
facing the combustion chamber (not shown). A plane of the metering orifice
50
is generally parallel to the plane of the planar end face
426
. A virtual extension
340
of the valve seat
30
can be projected onto the metering orifice
50
so as to intercept the interior face
510
of the metering orifice
50
at a point “A”, shown in FIG.
2
A.
Still referring to
FIG. 2A
, the metering orifice
50
has a plurality of metering openings
530
radially spaced from the longitudinal axis
270
. Preferably, the metering orifice
50
includes between four and twelve metering openings
530
which are symmetrically spaced around the longitudinal axis
270
. More preferably, the metering orifice
50
includes eight metering openings
530
as shown in FIG.
4
. Preferably, each metering opening
530
is generally circular and is approximately 200 microns in diameter. Preferably, a distance between adjacent metering openings
530
is at least two and a half times as great as a diameter of the metering openings
530
, although those skilled in the art will recognize that the distance between adjacent metering openings
530
can be less than that amount. An advantage to the larger cross-sectional area A
2
of the needle
40
is that the interior face
510
has a larger surface area which can contain a relatively large number of metering openings
530
, and yet maintain a desired separation distance between adjacent metering openings
530
.
Preferably, the metering openings
530
each have a longitudinal opening axis
532
which extends generally oblique to the longitudinal axis
270
of the body
20
, preferably downward and outward from the longitudinal axis
270
. However, those skilled in the art will recognize that the longitudinal opening axes
532
can extend at other angles relative to the longitudinal axis
270
. As illustrated in
FIG. 4
, the metering openings
530
are sufficiently far from the longitudinal axis
270
such that a virtual circle formed by the virtual extension
340
of the valve seat
30
onto the interior face
510
of the metering orifice
50
at “A” has a smaller diameter than a virtual circle
534
drawn around an outer perimeter of the metering openings
530
. This ensures that the flow of fuel between the valve seat
30
and the needle
40
when the needle
40
is in the open position directs the fuel onto the metering orifice
50
to provide a transverse flow of the fuel across the metering orifice
50
to the metering openings
530
prior to the fuel entering the metering openings
530
. Preferably, the outer perimeter of the projection
428
lies within the virtual circle
534
of the metering openings
530
, although those skilled in the art will recognize that the outer perimeter of the projection
428
can lie partially or totally outside of the virtual circle
534
of the orifice openings
530
as well.
With the needle
40
in a closed position, as shown in
FIGS. 2
,
2
A, the end face
426
, the interior face
510
of the metering orifice
50
and the valve seat orifice
320
between the downstream side of the needle contact face
422
and the metering orifice
50
form the sac
60
. The projection
428
extends from the end face
426
into the sac
60
, reducing the volume of the sac
60
. Preferably, the projection
428
reduces the volume of the sac
60
between approximately 25% and 75% as compared to a needle
40
without the projection
428
.
Still referring to
FIGS. 2
,
2
A, when the needle
40
is in the closed position, the end face
42
extends proximate to the interior face
510
of the metering orifice
50
, but allows a gap therebetween. Preferably, the gap is between approximately 50 microns and 250 microns, and more preferably, approximately 50 and 100 microns, although those skilled in the art will recognize that the gap can be other sizes as well. Further, the projection
428
extends proximate to the interior face
510
of the metering orifice
50
, but allows a minimum of a 50 micron gap therebetween.
The operation of the injector
10
is as follows. Pressurized fuel flow into the injector
10
is provided by a fuel pump (not shown). The pressurized fuel enters the injector
10
and passes through a fuel filter (not shown) to the armature
240
, and to the valve body chamber
262
. The fuel flows through the valve body chamber
262
, the fuel flow openings
284
in the guide
280
to the interface between the valve contact face
422
and the valve sealing surface
330
. In the closed position (shown in
FIGS. 2
,
2
A), the needle
40
is biased against the valve seat
30
so that the valve contact face
422
sealingly engages the valve sealing surface
330
, preventing flow of fuel through the metering orifice
50
.
In the open position (shown in FIG.
3
), a solenoid or other actuating device, (not shown) reciprocates the needle
40
to an open position, removing the valve contact face
422
of the needle
40
from the sealing surface
330
of the valve seat
30
and forming the generally annular channel
430
. Movement of the valve contact face
422
of the needle
40
from the sealing surface
330
of the valve seat
30
also enlarges the volume of the sac
60
. Pressurized fuel within the valve body chamber
262
flows past the generally annular channel
430
formed by the needle
40
and the valve seat
30
, and into the sac
60
where the fuel impacts on the interior face
510
of the metering orifice
50
. The end of the channel
430
and the metering orifice
50
are relatively close together to maintain fuel flow velocity. Since, as shown in
FIG. 2A
, the relative angle between the sealing surface
330
and the interior face
510
of the metering orifice is relatively slight, the fuel flow is only slightly affected and the fuel maintains a relatively high velocity without generating unwanted turbulence.
The fuel then flows across the interior face
510
of the metering orifice
50
generally transverse to the fuel metering openings
530
. The fuel turns into the fuel metering openings
530
where the fuel is atomized as it passes through the fuel metering openings
530
to the combustion chamber (not shown) for combustion, allowing for better combustion within the combustion chamber.
When a pre-determined amount of fuel has been injected into the combustion chamber, the solenoid or other actuating device disengages, allowing the spring (not shown) to bias the needle
40
to the closed position, closing the generally annular channel
430
and seating the valve contact face
422
of the needle
40
onto the sealing surface
330
of the valve seat
30
. The projection
428
extends toward the end face
426
, reducing the volume of the sac
60
and hence, the amount of unmetered fuel within the sac
60
.
In a third embodiment, shown in
FIG. 5
instead of a projection
428
extending downward from the end face
426
into the sac
60
, an orifice projection
540
can extend upward from the interior face
510
of the metering orifice
50
toward the end face
426
. Preferably, the orifice projection
540
encompasses approximately between 50% and 75% of the surface area of the planar end face
426
. The orifice projection
540
reduces the volume of the sac
60
in a similar manner as the projection
428
as discussed above. Preferably, the gap between orifice projection
540
and the end face
426
when the needle
40
is in a closed position is the same gap (a minimum of 50 microns) as the gap between the projection
428
and the interior face
510
of the metering orifice
50
of the first embodiment when the needle
40
is in the closed position.
Alternatively, although not shown, those skilled in the art will recognize that both the end face
426
and the interior face
510
of the metering orifice
50
can include projections such that each projection reduces the volume of the sac
60
while leaving a gap of preferably a minimum of 50 microns between the projections when the needle
40
is in the closed position.
By reducing the volume of the sac
60
through any of the above described embodiments, the amount of unmetered fuel which is released during low manifold pressure, high injector tip temperature operating conditions will be reduced. Additionally, the reduction in unmetered fuel in the sac
60
will provide improved entry conditions to the metering orifice
50
, resulting in improved spray atomization of the fuel through the fuel metering openings
530
and into the combustion chamber (not shown). The reduced amount of unmetered fuel in the sac
60
and the improved spray atomization of the fuel into the fuel chamber will also increase the fuel efficiency of the internal combustion engine.
Preferably, in each of the embodiments described above, the valve seat
30
, the needle
40
and the metering orifice
50
are each constructed from stainless steel. However, those skilled in the art will recognize that the valve seat
30
, the needle
40
and the metering orifice
50
can be constructed of other, suitable materials.
It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined in the appended claims.
Claims
- 1. A fuel injector for use in a fuel injection system of an internal combustion engine, the fuel injector comprising:a body having an inlet, an outlet and a longitudinal axis extending therethrough; a valve seat located within the body and disposed proximate the outlet, the valve seat including a valve seat orifice and a sealing surface surrounding the orifice; a metering orifice connected to the body downstream of the valve seat, the metering orifice includes a plurality of metering openings; a needle being reciprocally located within the body along the longitudinal axis between a first position wherein the needle is displaced from the valve seat, allowing fuel flow past the needle, and a second position wherein the needle is biased against the valve seat, precluding fuel flow past the needle, the needle including a first portion having a first cross-sectional area and a second portion having a second cross-sectional area, the second cross-sectional area being larger than the first cross-sectional area, the second portion including an end face extending generally perpendicular to the longitudinal axis, the end face being located upstream of the valve seat orifice; and a volume generally defined by the metering orifice, the end face and the valve seat orifice when the needle is in the second position, wherein a first virtual circle defined by a virtual extension of the valve seat onto the metering orifice has a smaller diameter than a second virtual circle defined by the plurality of metering openings.
- 2. The fuel injector according to claim 1, wherein, when the needle is in the second position, the end face is spaced from the metering orifice by a distance of between 50 microns and 250 microns.
- 3. The fuel injector according to claim 2, wherein, when the needle is in the second position, the end face is spaced from the metering orifice by a distance of between 50 microns and 100 microns.
- 4. The fuel injector according to claim 2, wherein the end face is generally planar.
- 5. The fuel injector according to claim 4, wherein metering orifice is generally planar.
- 6. The fuel injector according to claim 5, wherein the plane of the metering orifice is generally parallel to the plane of the end face.
- 7. The fuel injector according to claim 6, further including a projection extending from one of the end face and the metering orifice toward the other of the end face and the metering orifice.
- 8. The fuel injector according to claim 7, wherein, when the needle is in the second position, the projection is spaced from the other of the end face and the metering orifice by a distance of at least 50 microns.
- 9. The fuel injector according to claim 1, wherein the sealing surface is oblique to the longitudinal axis.
- 10. The fuel injector according to claim 1, wherein the valve seat orifice is formed by a generally cylindrical wall.
- 11. The fuel injector according to claim 1, wherein the projection encompasses approximately between 50% and 75% of a surface area of the one of the planar end face and the metering orifice.
- 12. The fuel injector according to claim 1, wherein the second portion of the needle engages the valve seat in a generally annular area of contact when the needle is in the second position.
- 13. The fuel injector according to claim 1, wherein a distance between adjacent metering holes is at least two and a half times a diameter of each of the metering holes.
- 14. A fuel injector for use in a fuel injection system of an internal combustion engine, the fuel injector comprising:a body having an inlet, an outlet and a longitudinal axis extending therethrough; a valve seat located within the body and disposed proximate the outlet, the valve seat including a valve seat orifice and a sealing surface surrounding the valve seat orifice; a metering orifice connected to the body downstream of the valve seat; a needle being reciprocally located within the body along the longitudinal axis between a first position wherein the needle is displaced from the valve seat, allowing fuel flow past the needle, and a second position wherein the needle is biased against the valve seat, precluding fuel flow past the needle, the needle including a first portion having a first cross-sectional area and a second portion having a second cross-sectional area, the second portion including an end face extending generally perpendicular to the longitudinal axis; and a volume generally defined by the metering orifice, the end face and the valve seat orifice when the needle is in the second position, the metering orifice being spaced from the end face by a distance of between 100 microns and 250 microns.
- 15. The fuel injector according to claim 14, wherein the second cross-sectional area is larger than the first cross-sectional area.
- 16. The fuel injector according to claim 14, wherein the metering orifice includes a plurality of metering openings.
- 17. The fuel injector according to claim 16, wherein each of the plurality of metering openings has a longitudinal opening axis extending generally oblique to the longitudinal axis of the valve body.
- 18. The fuel injector according to claim 16, wherein fuel flow across the metering plate is generally transverse to each of the plurality of metering openings.
- 19. The fuel injector according to claim 14, further including a projection extending from one of the end face and the metering orifice toward the other of the end face and the metering orifice.
- 20. The fuel injector according to claim 19, wherein the projection is located between the metering openings.
- 21. The fuel injector according to claim 14, wherein a distance between adjacent metering holes is at least two and a half times a diameter of each of the metering holes.
- 22. A fuel injector for use in a fuel injection system of an internal combustion engine, the fuel injector comprising:a body having an inlet, an outlet and a longitudinal axis extending therethrough; a valve seat located within the body and disposed proximate the outlet, the valve seat including a valve seat orifice and a sealing surface surrounding the valve seat orifice; a metering orifice connected to the body downstream of the valve seat, the metering orifice includes a plurality of metering openings; a needle being reciprocally located within the body along the longitudinal axis between a first position wherein the needle is displaced from the valve seat, allowing fuel flow past the needle, and a second position wherein the needle is biased against the valve seat, precluding fuel flow past the needle, the needle including a first portion having a first cross-sectional area and a second portion having a second cross-sectional area, the second portion including an end face extending generally perpendicular to the longitudinal axis; and a volume generally defined by the metering orifice, the end face and the valve seat orifice when the needle is in the second position, the metering orifice being spaced from the end face by a distance of between 100 microns and 250 microns, wherein a first virtual circle defined by a virtual extension of the valve seat onto the metering orifice has a smaller diameter than a second virtual circle defined by the plurality of metering openings.
- 23. A method of reducing a sac volume in a fuel injector, the fuel injector including a valve seat having an orifice, a needle having an end face, a metering orifice having a plurality of metering openings, and a sac volume located between the end face and the metering orifice, the method comprising:providing a fuel injector; providing pressurized fuel to the fuel injector; opening the fuel injector by removing the needle from the valve seat and enlarging the sac volume, thereby allowing the pressurized fuel to flow past the needle and the valve seat and through the sac volume and the metering orifice for ejection from the fuel injector; and closing the fuel injector by seating the needle against the valve seat, the end face being located upstream of the metering orifice, reducing the sac volume and an amount of fuel within the sac volume, wherein a first virtual circle defined by a virtual extension of the valve seat onto the metering orifice has a smaller diameter that a second virtual circle defined by the plurality of metering openings.
- 24. A method of reducing a sac volume in a fuel injector, the fuel injector including a valve seat having an orifice, a needle having an end face, a metering orifice, and a sac volume located between the end face and the metering orifice, the method comprising:providing a fuel injector; providing pressurized fuel to the fuel injector; opening the fuel injector by removing the needle from the valve seat and enlarging the sac volume, thereby allowing the pressurized fuel to flow past the needle and the valve seat and through the sac volume and the metering orifice for ejection from the fuel injector; and closing the fuel injector by seating the needle against the valve seat, the end face being located upstream of the metering orifice, reducing the sac volume and an amount of fuel within the sac volume, wherein, after completing the step of closing the fuel injector, a distance between the needle and the metering orifice is between 50 microns and 250 microns.
- 25. The method according to claim 24, wherein the needle further includes a projection extending therefrom toward the metering orifice, the projection extending into the volume during the step of closing the fuel injector.
US Referenced Citations (16)
Foreign Referenced Citations (2)
Number |
Date |
Country |
2 198 785 |
Jun 1988 |
GB |
WO 9219859 |
Nov 1992 |
WO |