Information
-
Patent Grant
-
6742727
-
Patent Number
6,742,727
-
Date Filed
Wednesday, May 10, 200024 years ago
-
Date Issued
Tuesday, June 1, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
-
CPC
-
US Classifications
Field of Search
US
- 239 5332
- 239 5333
- 239 53312
- 239 583
- 239 584
- 239 5854
- 239 5855
- 239 499
- 239 518
- 239 524
- 239 596
- 239 53311
-
International Classifications
- F02M3900
- F02M4100
- F02M4300
- F02M4700
- F02M5500
-
Abstract
A fuel injector for an internal combustion engine is disclosed. The fuel injector includes a housing, a valve seat, a metering orifice disc, and a needle. The housing has an inlet, an outlet, and a longitudinal axis extending therethrough. The valve seat is disposed proximate the outlet and includes a passage having a sealing surface and an orifice. The metering orifice disc is located at the outlet and has a plurality of metering openings extending therethrough. The needle is reciprocally located within the housing 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. A generally annular channel is formed between the valve seat and the metering orifice disc. The channel tapers outwardly from a large height to a smaller height toward the orifice openings. A method of generating turbulence in a fuel flow through a fuel injector is also disclosed.
Description
FIELD OF THE INVENTION
This invention relates to fuel injectors, and more particularly, to fuel injectors having a single disc which generates turbulence at the metering orifices.
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 electro-magnetic 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, when the needle is seated in a valve seat along a sealing diameter to prevent fuel from escaping through a metering orifice disc 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, the metering orifice disc includes a plurality of metering orifice openings which are directly below the needle and inward of the sealing diameter. This approach relies on a precise control of the distance between the end of the needle and the upstream surface of the metering orifice disc. Variations in needle geometry, sealing diameter, and lift of the needle can cause this critical dimension to change. Another approach to maintaining precise control of this dimension uses a multi-disc concept. However, this approach has the added complexity of orientation, delamination, and part handling.
It would be beneficial to develop a fuel injector in which a controlled precise geometry is created at the downstream surface of the valve seat to generate desired turbulence at the metering orifice openings.
SUMMARY OF THE INVENTION
Briefly, the present invention is a fuel injector comprising a housing, a valve seat, a metering orifice disc and a needle. The housing has an inlet, an outlet and a longitudinal axis extending therethrough. The valve seat is disposed proximate the outlet. The valve seat includes a passage having a sealing surface and an orifice. The metering orifice disc is located at the outlet and includes a plurality of metering openings extending therethrough. The needle is reciprocally located within the housing 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. A controlled velocity channel is formed between the valve seat and the metering orifice disc. The controlled velocity channel extends outwardly from the orifice to the plurality of metering openings.
Additionally, the present invention is a method of generating turbulence in a fuel flow through a fuel injector. The method includes providing a fuel flow under pressure to the fuel injector. A valve in the fuel injector is opened and the pressurized fuel flows past the valve and into a fuel chamber. The fuel flow is directed at an initial velocity from the fuel chamber into a controlled velocity channel formed by a valve seat and a metering orifice disc. The controlled velocity channel tapers from a first height at an upstream end of the controlled velocity channel to a second height at a downstream end of the controlled velocity channel. The second height is smaller than the first height. The fuel maintains a generally controlled velocity through the controlled velocity channel. The final velocity is higher than the initial velocity and generates turbulence within the fuel flow. The fuel flow is then directed through at least one orifice opening downstream of the controlled velocity channel and out of the fuel injector.
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 drawings:
FIG. 1
is a side view, in section, of a discharge end of an injector according to a first embodiment of the present invention, with the needle in the closed position;
FIG. 2
is an enlarged side view, in section, of the discharge end of the injector of
FIG. 1
with the needle in the open position;
FIG. 3
is a top plan view of a metering orifice disc used in the injector shown in
FIG. 1
;
FIG. 4
is a side view, in section, of a discharge end of an injector according to a second preferred embodiment of the present invention;
FIG. 5
is a top plan view of a metering orifice disc used in the injector shown in
FIG. 4
; and
FIG. 6
is a side view, in section, of a discharge end of an injector according to a third preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the drawings, like numerals are used to indicate like elements throughout. A first preferred embodiment, shown in
FIGS. 1 and 2
, is a fuel injector
10
for use in a fuel injection system of an internal combustion engine. The injector
10
includes a housing
20
, a valve seat
30
, a needle
40
, and a generally planar fuel metering orifice disc
50
. 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 preferred embodiments. Although the preferred embodiments are generally directed to injectors for internal combustion engines, those skilled in the art will recognize from present disclosure that the preferred embodiments can be adapted for other applications in which precise metering of fluids is desired or required.
The valve housing
20
has an upstream or inlet end
210
and a downstream or outlet end
220
. The housing
20
further includes a valve body
260
, which includes a housing chamber
262
. 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 housing chamber
262
extends through a central longitudinal portion of the valve housing
20
along a longitudinal axis
270
extending therethrough and is formed by an interior housing wall
264
. A needle guide
280
having a central needle guide opening
284
and a plurality of radially spaced fuel flow openings
282
is located within the housing chamber
262
proximate to the downstream end
220
of the housing
20
. The needle guide 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 valve body
260
. An o-ring
12
is located around the outer circumference of the valve body
260
to seat the injector
10
in the internal combustion engine (not shown).
The valve seat
30
is located within the housing chamber
262
proximate to the outlet end
220
between the needle guide
280
and the discharge ends
220
. The valve seat
30
includes a passage orifice
320
which extends generally along the longitudinal axis
270
of the housing
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
. The words “inward” and “outward” refer to directions towards and away from, respectively, the longitudinal axis
270
.
The needle
40
is reciprocally located within the housing chamber
262
generally along the longitudinal axis
270
of the housing
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.
2
), 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
FIG. 1
) by a biasing element (not shown), preferably a spring, precluding fuel flow past the needle
40
.
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 valve 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 valve contact face
422
engages the beveled valve sealing surface
330
to provide a generally line contact therebetween. The line contact provides a solid seal between the needle
40
and the valve seat
30
and reduces the possibility of fuel leakage past the needle
40
. The contact face
422
, shown in enlarged
FIG. 2
, connects 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 housing
20
.
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 also provides a larger guide surface relative to the mean needle diameter, thereby improving the wear resistance of the internal surface of the central needle guide opening
284
. The improved wear resistance of the internal surface of the central needle guide opening
284
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
.
The needle
40
is reciprocable between the closed position (shown in
FIG. 1
) and the open position (shown in FIG.
2
). 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 disc
50
is located within the housing chamber
262
and is connected to the housing
20
, downstream of the valve seat
30
. The metering orifice disc
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 disc
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 disc
50
, shown in
FIG. 2
, so as to intercept the interior face
510
of the metering orifice disc
50
at a point “A”, to define a first virtual circle, as shown in FIG.
3
. Referring again to
FIG. 3
, although eight metering openings
530
are shown as being tangential to a second virtual circle
400
, the metering orifice disc
50
preferably includes between four and twelve generally circular metering openings
530
, although those skilled in the art will recognize that the metering orifice disc
50
can include less than four or more than twelve metering openings
530
, and that the metering openings
530
can be other shapes, such as oval or any other suitable shape. Preferably, a distance “D” between adjacent metering openings
530
is at least approximately two and a half times as great as a diameter “d” 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.
The metering orifice disc
50
includes a raised portion
540
located within a perimeter determined by the metering openings
530
. Preferably, in the closed position, the raised portion
540
of the metering orifice disc
50
and the end face
426
are spaced from each other by between 50 microns and 250 microns, and, more preferably, by between 50 and 100 microns, although those skilled in the art will recognize that the distance can be less than 50 microns or greater than 100 microns. The raised portion
540
is preferably circular and reduces the sac volume
60
between the metering orifice disc
50
and the planar end face
426
of the needle
40
. However, those skilled in the art will recognize that the raised portion
540
can be other shapes, such as oval. A continuous annular gap
542
is formed between the raised portion
540
and the orifice opening
330
in the valve seat
30
. The gap
542
allows fuel flow between the metering orifice disc
50
and the valve seat
30
when the needle
40
is in the open position.
Downstream of the circular wall
322
, the valve seat
30
tapers along a tapered portion
350
downward and outward in an oblique manner away from the orifice
320
to a point radially past the metering openings
530
, where the valve seat
30
flattens to a bottom surface
550
preferably perpendicular to the longitudinal axis
270
. The valve seat orifice
320
is preferably located wholly within the perimeter determined by the metering openings
530
. The interior face
510
of the metering orifice disc
50
proximate to the outer perimeter of the metering orifice disc
50
engages the bottom surface
550
along a generally annular contact area.
Referring to
FIG. 2
, a generally annular controlled velocity channel
560
is formed between the tapered portion
350
of the valve seat
30
and interior face
510
of the metering orifice disc
50
. Preferably, the controlled velocity channel
560
provides a generally constant velocity, although those skilled in the art will recognize that the controlled velocity can vary throughout the length of the channel
560
. The channel
560
tapers outwardly from a larger height A
3
at the orifice
320
to a smaller height A
4
toward the metering openings
530
. The reduction in the height toward the metering openings
530
maintains the fuel at a generally controlled velocity, as will be discussed in more detail below, forcing the fuel to travel in a transverse direction across the metering openings
530
, where the fuel is atomized as it passes through the metering openings
530
into the combustion chamber (not shown). A generally annular space
570
is formed between the interior face
510
of the metering orifice disc
50
radially outward of the metering openings
530
and the tapered portion
350
of the valve seat
30
.
In operation, pressurized fuel is provided to the injector
10
by a fuel pump (not shown). The pressurized fuel enters the injector
10
and passes through a fuel filter (not shown) to the housing chamber
262
. The fuel flows through the housing 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, 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 disc
50
.
In the open position, a solenoid or other actuating device, (not shown) reciprocates the needle
40
to an open position, removing the spherical contact face
422
of the needle
40
from the sealing surface
330
of the valve seat
30
and forming the generally annular channel
430
. Pressurized fuel within the housing chamber
262
flows past the generally annular channel
430
formed by the needle
40
and the valve seat
30
and impinges on the raised portion
540
of the metering orifice disc
50
. The fuel then flows generally radially outward along the raised portion
540
of the metering orifice disc
50
from the longitudinal axis
270
, where the flow is redirected generally downward between the raised portion
540
and the valve seat orifice walls
322
. The fuel is then directed generally radially outward from the longitudinal axis
270
through the generally annular channel
560
between the tapered portion
350
of the valve seat
30
and the metering orifice disc
50
. The fuel attains a generally high velocity at the beginning of the generally annular channel
560
. As the fuel flows outward from the longitudinal axis
270
, the perimeter of the fuel flow increases in a direct linear relationship to the distance from the longitudinal axis
270
. To maintain a generally constant area of fuel flow, the height between the metering orifice disc
50
and the tapered portion
350
of the valve seat
30
must decrease (as shown in the decreased height A
4
as compared to height A
3
in
FIG. 2
) according to the formula:
2
πr
1
h
1
=2
πr
2
h
2
Equation 1
where:
r
1
is a radius of the fuel flow between the longitudinal axis
270
and location A
3
;
h
1
is a height between the metering orifice disc
50
and the tapered portion
350
at location A
3
;
r
2
is a radius of the fuel flow between the longitudinal axis
270
and location A
4
; and
h
2
is a height between the metering orifice disc
50
and the tapered portion
350
at location A
4
.
Although a generally constant flow velocity is desired, those skilled in the art will recognize that the generally annular channel
560
can be used to accelerate or decelerate the velocity of the fuel if desired.
As the fuel flows across the metering openings
530
, turbulence is generated within the fuel flow which reduces the spray particle size, atomizing the fuel as it flows through the metering openings
530
into the combustion chamber (not shown).
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
.
A second embodiment
100
is shown in FIG.
4
. In the second embodiment, the valve seat
130
includes a valve sealing surface
132
and a valve orifice
134
. The valve seat
130
is generally the same shape as the valve seat
30
, with a tapered portion
136
which extends downward and outward in an oblique manner from the longitudinal axis
270
downstream from the valve orifice
134
. The tapered portion
136
terminates at a location radially outward of the metering orifice disc openings
152
. A generally annular controlled velocity channel
154
is formed between the metering orifice disc
150
radially outward of the metering openings
152
and the tapered portion
136
of the valve seat
130
.
The needle
140
differs from the needle
40
in the first embodiment in that the needle tip
142
does not include a flat end face. However, those skilled in the art will recognize that either of the needles
40
,
140
can have a spherical, conical, tapered, flat, or other, suitable tip. When the needle
140
is in the closed position, the needle tip
142
engages the valve seat
130
in a generally circular point contact. When the needle
140
is in the open position, a generally annular channel
144
is formed between the needle
140
and the valve seat
130
.
The metering orifice disc
150
, shown in a top plan view in
FIG. 5
, is generally planar and extends in a plane generally perpendicular to the longitudinal axis
270
. The metering orifice disc
150
differs from the metering orifice disc
50
in that the metering orifice disc
150
does not include a raised portion
540
.
In operation, when the needle
140
is lifted from the valve seat
130
, pressurized fuel flows through the channel
144
formed between the needle
140
and the valve seat
130
. The fuel is directed into the valve seat orifice
134
and to the metering orifice disc
150
. The fuel then is directed outward from the longitudinal axis
270
into the controlled velocity channel
154
where the fuel attains a high velocity at the entrance of the controlled velocity channel
154
. The high fuel velocity directs the fuel across the metering orifice disc
150
and the orifice openings
152
in a transverse direction to the orifice openings
152
, generating turbulence within the fuel which atomizes the fuel as the fuel travels through the orifice openings
152
.
The third embodiment, shown in
FIG. 6
, is similar to the second embodiment with the exception that, in the third embodiment, a metering orifice disc
600
between orifice openings
610
is generally rounded such that a concave surface
620
faces the needle
140
. The valve seat
700
, instead of tapering downward and outward in an oblique manner away from the longitudinal axis
270
below a valve seat orifice
710
along a bottom portion
720
, preferably extends away from the longitudinal axis
270
generally perpendicular to the longitudinal axis
270
. A generally annular channel
630
is formed between the bottom portion
720
of the valve seat
700
and the metering orifice disc
600
. The channel
630
tapers outwardly from a larger height to a smaller height toward the orifice openings
610
. A generally annular space
640
is formed between the metering orifice disc
600
radially outward of the metering openings
610
and the bottom portion
720
of the valve seat
700
.
The operation of the third embodiment is similar to the operation of the second embodiment described above.
Although the three preferred embodiments described above disclose generally annular channels formed between the valve seat and the metering orifice disc in which the channel tapers outwardly from a larger height to a smaller height toward the orifice openings to maintain a generally constant cross-sectional area, those skilled in the art will recognize that generally annular channels which taper outwardly from a larger height to a smaller height toward the orifice openings can be formed in other manners.
Preferably, in each of the embodiments described above, the valve seat
30
, the needle
40
, and the metering orifice disc
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 disc
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 comprising:a housing having an inlet, an outlet and a longitudinal axis extending therethrough; a valve seat disposed proximate the outlet, the valve seat including a sealing surface, an orifice, and a first channel surface, the orifice having a first diameter; a metering orifice disc located at the outlet, the metering orifice disc having a plurality of metering openings extending therethrough, a second channel surface confronting the first channel surface, the metering openings tangential to a virtual circle, the virtual circle having a diameter greater than the first diameter; a needle being reciprocally located within the housing 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; and a controlled velocity channel disposed between the first channel surface of the valve seat and the second channel surface of the metering orifice disc, the controlled velocity channel extending outwardly from the orifice to the plurality of metering openings, such that fuel flow is at a generally constant velocity between the first orifice and the plurality of metering openings to maintain a constant flow velocity of fuel between the valve seat and the metering orifice, wherein the metering orifice disc is generally planar and perpendicular to the longitudinal axis and includes a raised portion between the metering openings.
- 2. The fuel injector according to claim 1 wherein the needle includes a generally planar end face generally perpendicular to the longitudinal axis.
- 3. The fuel injector according to claim 2 wherein, when the needle is in the second position, the end face is spaced from the raised portion by a distance of between 50 microns and 100 microns.
- 4. A fuel injector comprising:a housing having an inlet, an outlet and a longitudinal axis extending therethrough; a seat disposed proximate the outlet, the seat including a sealing surface, an orifice, and a first channel surface; a metering orifice disc located at the outlet, the metering orifice disc including a second channel surface confronting the first channel surface, the metering orifice disc having a plurality of metering openings extending therethrough, the metering openings defining a first virtual circle greater than a second virtual circle defined by a virtual extension of the sealing surface of the seat onto a metering orifice disc prior to an intersection of the virtual extension with the longitudinal axis, the metering disc having a solid imperforate portion within the entirety of second virtual circle so that all of the metering openings disposed are outside the second virtual circle; a closure member being reciprocally located within the housing along the longitudinal axis between a first position wherein the closure member is displaced from the valve seat, allowing fuel flow past the closure member, and a second position wherein the closure member is biased against the valve seat, precluding fuel flow past the closure member; and a controlled velocity channel formed between the first and second channel surfaces, the controlled velocity channel having a changing cross-sectional area as the channel extends outwardly from the orifice of the seat to the plurality of metering openings such that fuel flow is at a generally constant velocity between the orifice and the plurality of metering openings, wherein the channel extends between a first end and a second end, the first end disposed at a first radius from the longitudinal axis with the first and second channel surfaces spaced apart along the longitudinal axis at a first distance, the second end disposed at a second radius proximate the plurality of metering openings with respect to the longitudinal axis with the first and second channel surfaces spaced apart along the longitudinal axis at a second distance such that a product of two times the trigonometric constant pi (π) times the first radius and the first distance is equal to a product of two times the trigonometric constant pi (π) of the second radius and the second distance.
- 5. The fuel injector according to claim 4, wherein fuel flow across the metering orifice disc is generally transverse to each of the plurality of metering openings.
- 6. The fuel injector according to claim 4, wherein a distance between adjacent metering openings is at least approximately two and a half times a diameter of each of the metering openings.
- 7. The fuel injector according to claim 4, wherein the controlled velocity channel is a generally annular channel tapering outwardly from a larger height to a smaller height towards the metering openings.
- 8. The fuel injector of claim 7, wherein the larger height of the controlled velocity channel being located at a first radius with respect to the longitudinal axis, the smaller height of the controlled velocity channel being located at a second radius proximate the plurality of metering openings with respect to the longitudinal axis such that a product of the larger height and the first radius is substantially equal to a product of the smaller height and the second radius.
- 9. The fuel injector according to claim 4, wherein the metering orifice disc is generally planar and perpendicular to the longitudinal axis.
- 10. The fuel injector according to claim 9 wherein the closure member includes a needle having generally rounded end face.
- 11. The fuel injector according to claim 10 wherein the metering orifice disc is generally rounded.
- 12. The fuel injector according to claim 4, wherein the closure member has a generally planar end face generally perpendicular to the longitudinal axis.
- 13. The fuel injector according to claim 12 wherein, when the closure member is in the second position, the end face is spaced from the metering orifice by a distance of approximately between 50 microns and 100 microns.
US Referenced Citations (15)
Foreign Referenced Citations (2)
Number |
Date |
Country |
1 092 865 |
Apr 2001 |
EP |
2000-97129 |
Sep 2000 |
JP |