U.S. patent application number 09/285843 was filed with the patent office on 2002-01-24 for fuel injection nozzle.
Invention is credited to AOKI, TSUNEAKI, FUKAYA, KANEHIRO, HIRATA, MASAMI, ODA, HIROSHI, TSUZUKI, NORIO.
Application Number | 20020008166 09/285843 |
Document ID | / |
Family ID | 27308915 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020008166 |
Kind Code |
A1 |
FUKAYA, KANEHIRO ; et
al. |
January 24, 2002 |
FUEL INJECTION NOZZLE
Abstract
A fuel injection nozzle is provided with a valve seat having a
valve opening in which a valve is slidably provided, and a seat
portion on which the valve is seated, and a nozzle tip having a
sack portion and an injection opening 36a formed on the sack
portion. The valve seat is formed of metal, and at the same time,
the nozzle tip is molded by metal injection molding, wherein the
valve seat and nozzle tip are joined by welding, or after the
injection opening of the nozzle tip is formed from the upstream
side in the fuel injection direction by laser machining, the valve
seat and nozzle tip are joined by welding.
Inventors: |
FUKAYA, KANEHIRO; (OBU-SHI,
JP) ; HIRATA, MASAMI; (OBU-SHI, JP) ; TSUZUKI,
NORIO; (OBU-SHI, JP) ; ODA, HIROSHI; (OBU-SHI,
JP) ; AOKI, TSUNEAKI; (OBU-SHI, JP) |
Correspondence
Address: |
DENNISON MESEROLE SCHEINER
& SCHULTZ
1745 JEFFERSON DAVIS HIGHWAY SUITE 612
ARLINGTON
VA
22202
|
Family ID: |
27308915 |
Appl. No.: |
09/285843 |
Filed: |
April 5, 1999 |
Current U.S.
Class: |
239/533.12 ;
239/533.2; 239/533.9; 239/585.1 |
Current CPC
Class: |
F02M 61/168 20130101;
F02M 61/18 20130101; B23K 2103/04 20180801; B23K 26/389 20151001;
B23K 26/40 20130101; F02M 61/1806 20130101; B23K 2103/50
20180801 |
Class at
Publication: |
239/533.12 ;
239/533.2; 239/533.9; 239/585.1 |
International
Class: |
F02M 051/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 10, 1998 |
JP |
10-099300 |
Apr 20, 1998 |
JP |
10-109423 |
Apr 22, 1998 |
JP |
10-112293 |
Claims
1. A fuel injection nozzle comprising: a valve needle; a valve seat
having a valve opening in which the valve needle slidably contacts
and a seat portion on which the valve needle is seated, the valve
seat comprising metal; and a metal injection molded nozzle tip
welded to the valve seat and having a rounded portion with a
generally spherical inner surface and an injection opening formed
within the rounded portion.
2. A fuel injection nozzle as set forth in claim 1, wherein an
engaging member consisting of a projection portion and a concave
portion that can engaged together are disposed between joining
surfaces of the valve seat and the nozzle tip.
3. A fuel injection nozzle as set forth in claim 1, wherein the
injection opening is a fan shaped slit having a predetermined
angle, and the center of the injection opening angle is positioned
upstream from the center of the generally spherical inner surface
of the rounded portion.
4. A fuel injection nozzle as set forth in claim 3, wherein Pb
defines a length from the center of the generally spherical inner
surface of the rounded portion to the center of the opening angle
of the injection opening, Rs defines the radius of the generally
spherical inner surface of the rounded portion and Pb satisfies the
relation:0.ltoreq.Pb.ltoreq.0- .75Rs.
5. A fuel injection nozzle comprising: a valve needle; a valve seat
having a valve opening in which the valve needle slidably contacts
and a seat portion on which the valve needle is seated, the valve
seat comprising metal; and a laser machined nozzle tip joined to
the valve seat and having a rounded portion with a generally
spherical inner surface and an injection opening formed within the
rounded portion.
6. A fuel injection nozzle as set forth in claim 5, wherein the
injection opening of the nozzle tip is formed from an inner surface
of the rounded portion.
7. A fuel injection nozzle as set forth in claim 5, wherein the
injection opening of the nozzle tip is formed from an outer surface
of the rounded portion.
8. A fuel injection nozzle as set forth in claim 5, wherein an
engaging member consisting of a projection portion and a concave
portion that can engaged together are disposed between joining
surfaces of the valve seat and the nozzle tip.
9. A fuel injection nozzle as set forth in claim 5, wherein the
valve seat and the nozzle tip are both made of metal and are joined
by welding.
10. A fuel injection nozzle as set forth in claim 5, wherein the
injection opening is a fan shaped slit having a predetermined
angle, and the center of the injection opening angle is positioned
upstream from the center of the generally spherical inner surface
of the rounded portion.
11. A fuel injection nozzle as set forth in claim 5, wherein Pb
defines a length from the center of the generally spherical inner
surface of the rounded portion to the center of the opening angle
of the injection opening, Rs defines the radius of the generally
spherical inner surface of the rounded portion and Pb satisfies the
relation:0.ltoreq.Pb<0.75R- s.
12. A method of manufacturing a fuel injection nozzle, comprising
the steps of: metal injection molding a metal valve opening and a
metal valve seat having a seat portion; metal injection molding a
sack portion and a nozzle tip having an injection opening; and
welding the valve seat and the nozzle tip.
13. A method of manufacturing a fuel injection nozzle, comprising
the steps of: metal injection molding a valve opening and a valve
seat having a seat portion; forming a sack portion on a metal
nozzle tip; forming an injection opening in the sack portion by
laser machining; and welding the valve seat and the nozzle tip.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a fuel injection nozzle for
use in a fuel injection valve in an internal combustion engine,
etc.
DESCRIPTION OF THE RELATED ART
[0002] A known integral type fuel injection nozzle described in
Japanese Laid-Open Patent Publications Nos. 9-66381 and 9-126095 is
shown in partial front sectional view in FIG. 1. The fuel injection
nozzle 10 is molded from steel material and has a valve opening 13
in which a fuel injection valve 12 is slidably provided, a valve
seat or seat portion 14, and a rounded or "sack" portion 16, which
has a generally semi-spherical inner circumferential surface 16a.
An injection opening 17 is formed in the sack portion 16 and fuel
is injected into the engine through this injection opening 17. The
injection opening 17 is formed in the nozzle 10 by laser machining
from the downstream side or the upstream side in the fuel injection
direction.
[0003] However, if the injection opening 17 is formed from the
downstream side using a laser machining process, dross accumulates
in the fuel injection nozzle 10, and the measuring accuracy of
injection fuel may be diminished. Dross is metal burrs that are
formed when the metal melts during the laser machining process and
adheres to the nozzle 10.
[0004] On the other hand, if the injection opening 17 is formed
from the upstream side using a laser machining process, an optical
fiber must be connected to a laser beam emitting apparatus and the
laser machining process is indirectly performed by inserting the
optical fiber into the valve opening 13. In this case, because the
laser beam emitted by the optical fiber scatters, a special beam
condensing device must be utilized to condense the laser beam.
Furthermore, because the valve opening 13 is generally small
(approximately 6 mm) in diameter, the machining accuracy of the
opening profile is limited.
[0005] An electric spark machining process also can form an
injection port. However, because the time required to fabricate the
injection port using an electric spark machining port is
substantially longer than the time required for laser machining,
manufacturing efficiency is reduced.
[0006] A known two-piece type fuel injection nozzle described in
Japanese Laid-Open Patent Publication No. 6-249105 is shown by
partial sectional view in FIG. 2. This fuel injection nozzle 20
comprises a valve seat 21 made from steel material and a nozzle tip
25 molded from ceramic. A valve opening 23, in which a fuel
injection valve 22 is slidably secured, and a seat portion 24, on
which the valve 22 contacts, are formed on the valve seat 21. The
nozzle tip 25 includes a sack portion 26 having a generally
semi-spherical inner circumferential surface 26a and an injection
opening 27. The valve seat 21 and nozzle tip 25 are joined by a
brazing material 29 using a brazing process. However, because
brazing these two parts is difficult, manufacturing costs are
relatively high.
SUMMARY OF THE INVENTION
[0007] It is, accordingly, an object of the invention to provide
improved fuel injection nozzles that can be manufactured
efficiently.
[0008] In one aspect of the present teachings, improved
manufacturing processes are described that facilitate the joining
of the valve seat and the nozzle tip of a fuel injection
nozzle.
[0009] In another aspect of the present teachings, improved methods
for forming an injection opening in the nozzle tip are
described.
[0010] In a further aspect of the present teachings, improved
methods for manufacturing a fuel injection nozzle are described in
which an optionally shaped injection opening having excellent
measuring accuracy can be easily formed on the nozzle tip in a
short time.
[0011] Other objects, features and advantages of the present
invention will be readily understood after reading the following
detailed description together with the accompanying drawings and
the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a partial front sectional view of a known integral
type fuel injection nozzle;
[0013] FIG. 2 is a partial front sectional view of a known
two-piece type fuel injection nozzle;
[0014] FIG. 3 is a partial front sectional view of a fuel injection
nozzle according to a first representative example;
[0015] FIG. 4 is a cross-sectional view taken along the line IV-IV
in FIG. 3;
[0016] FIG. 5 is a partial front sectional view of a valve seat
used in the first representative example;
[0017] FIG. 6 is a front sectional view of a valve tip used in the
first representative example;
[0018] FIG. 7 is a partial front sectional view of a fuel injection
valve according to a second representative example;
[0019] FIG. 8 is a partial front sectional view of a valve seat
used in the second representative example;
[0020] FIG. 9 is a front sectional view of a nozzle tip used in the
second representative example;
[0021] FIG. 10 is a plan view of a nozzle tip used in the second
representative example;
[0022] FIG. 11 is a cross-sectional view taken along the line XI-XI
in FIG.9;
[0023] FIG. 12 is view showing a representative nozzle tip
manufacturing process;
[0024] FIG. 13 is a cross-sectional view taken along the line
XIII-XIII in FIG. 12;
[0025] FIG. 14 is a view showing a representative nozzle tip
manufacturing process;
[0026] FIG. 15 is a cross-sectional view taken along the line XV-XV
in FIG. 14;
[0027] FIG. 16 is a view showing a representative nozzle tip
manufacturing process;
[0028] FIG. 17 is a cross-sectional view taken along the line
XVII-XVII in FIG. 16;
[0029] FIG. 18 is a view showing a method for forming an injection
opening in the nozzle tip;
[0030] FIG. 19 is a cross-sectional view taken along the line
XIX-XIX in FIG. 18;
[0031] FIG. 20 is a view showing a method for forming an injection
opening in the nozzle tip;
[0032] FIG. 21 is a cross-sectional view taken along the line
XXI-XXI in FIG. 20;
[0033] FIG. 22 is a view showing a method for forming an injection
opening in the nozzle tip;
[0034] FIG. 23 is a cross-sectional view taken along the line
XXIII-XXIII in FIG. 22;
[0035] FIG. 24 is a partial front sectional view of a fuel
injection nozzle according to a third representative example;
[0036] FIG. 25 is a partial front sectional view of a fuel
injection nozzle according to a fourth representative example;
[0037] FIG. 26 is a partial front sectional view of a fuel
injection nozzle according to a fifth representative example;
[0038] FIG. 27 is a partial front sectional view of a fuel
injection nozzle according to a sixth representative example;
[0039] FIG. 28 is a front elevational view of a fuel injection
nozzle according to a seventh representative example;
[0040] FIG. 29 is a partial front sectional view of a fuel
injection nozzle according to the seventh representative
example;
[0041] FIG. 30 is a front sectional view showing significant
aspects of the fuel injection nozzle according to the seventh
representative example;
[0042] FIG. 31 is a characteristic view showing a relationship
between the dimension Pb and the angle ratio .theta.2/.theta.1;
[0043] FIG. 32 is a characteristic view showing a relationship
between the dimension Pb and the injection distribution ratio Dp;
and
[0044] FIG. 33 is a view showing a method of measuring the
injection distribution ratio Dp.
DETAILED DESCRIPTION OF THE INVENTION
[0045] In one aspect of the present teachings, a fuel injection
nozzle is taught that has a valve needle and a valve seat having a
valve opening in which the valve needle slidably contacts and a
seat portion on which the valve needle is seated. Preferably, the
valve seat is made of metal. The fuel injection nozzle further
includes a metal injection molded nozzle tip welded to the valve
seat and having a rounded portion with a generally spherical inner
surface and an injection opening formed within the rounded
portion,
[0046] In another aspect, a fuel injection nozzle is taught in
which the nozzle tip is laser machined. The injection opening of
the nozzle tip can be formed wither from the inner (upstream)
surface or the outer (downstream) surface of the rounded
portion.
[0047] In either fuel injection nozzle, an engaging member may be
provided that consists of a projection portion and a concave
portion that can join the surfaces of the valve seat and the nozzle
tip. Preferably, the valve seat and the nozzle tip are both made of
metal and are joined by welding.
[0048] The injection opening is preferably a fan shaped slit having
a predetermined angle. In addition, the center of the injection
opening angle may be positioned upstream from the center of the
generally spherical inner surface of the rounded portion. In
addition, Pb may define a length from the center of the generally
spherical inner surface of the rounded portion to the center of the
opening angle of the injection opening, Rs may define the radius of
the generally spherical inner surface of the rounded portion and Pb
preferably satisfies the relation:
0.ltoreq.Pb.ltoreq.0.75Rs.
[0049] Method of manufacturing such fuel injection nozzles also are
taught. In one method, a metal valve opening and a metal valve seat
having a seat portion are formed by metal injection molding. A
rounded or sack portion and a nozzle tip having an injection
opening are separately formed by metal injection molding. Finally,
the valve seat and the nozzle tip are welded together.
[0050] Alternatively, a fuel injection nozzle may be manufactured
by first metal injection molding a valve opening and a valve seat
having a seat portion. A sack portion can then be formed on a metal
nozzle tip by a variety of methods, and an injection opening may
preferably be formed in the sack portion by laser machining.
Finally, the valve seat and the nozzle tip may be welded
together.
[0051] Each of the additional features and method steps disclosed
above and below may be utilized separately or in conjunction with
other features and method steps to provide improved fuel injector
nozzles and methods for making such nozzles. Representative
examples of the present invention, which examples utilize many of
these additional features and method steps in conjunction, will now
be described in detail with reference to the drawings. This
detailed description is merely intended to teach a person of skill
in the art further details for practicing preferred aspects of the
present teachings and is not intended to limit the scope of the
invention. Only the claims define the scope of the claimed
invention. Therefore, combinations of features and steps disclosed
in the following detail description may not be necessary to
practice the invention in the broadest sense, and are instead
taught merely to particularly describe representative and
representative examples of the invention.
[0052] First Representative Example
[0053] The first representative example of an improved fuel
injection nozzle will be described with reference to FIGS. 3
through 6. Such a fuel injection nozzle 30 includes a cylindrical
valve seat 31 disposed adjacent to a generally cup-shaped nozzle
tip 35.
[0054] A needle-like valve 32 is provided inside the valve seat 31
and can slide in the axial direction (the vertical direction in the
drawings). A seat portion 34 is formed in the valve seat 31 and the
valve 32 contacts the seat portion 34 during the operation of the
nozzle 30. The valve seat 31 may formed from a steel bar by a
forging process (for example, cold-forging). The steel bar may be,
for example, SUS440C (stainless steel). The valve seat 31 also can
be machined from a steel bar. The valve seat 31 is preferably
hardened in order to improve the wear resistance properties of the
seat portion 34.
[0055] A rounded or "sack" portion 36, which has a generally
semi-spherical inner circumferential surface 36a, and an injection
opening 37, which injects fuel from the valve opening 33 into the
engine (not shown), are formed in the nozzle tip 35. For an
in-cylinder injection type fuel injection valve, the injection
opening 37 is slit-shaped with a section that opens in a fan shape
at a predetermined angle. The opening angle of the injection
opening 37 is preferably between about 30.degree. and
160.degree..
[0056] The sack portion 36 and injection opening 37 of the nozzle
tip 35 are preferably simultaneously molded by metal injection
molding (known as MIM molding). MIM molding is well known in the
art and includes the steps of blending, molding, liquid de-oiling
and sintering. In the blending step, minute grains of metal powder
are blended with a binder. In the molding step, the blended
material is molded by an injection molding machine. In the liquid
de-oiling step, the binder is removed from a molded article, using
a solvent in a de-oiling hearth. In the sintering step, the
de-oiled molded article is sintered in a sintering hearth. If the
nozzle tip 35 is molded by metal injection molding, for example,
powdered SUS316 (stainless steel) is preferably used as the metal
material. By molding the nozzle tip 35 using MIM process, drilling
work on the nozzle tip 35 is not longer required in order to form
the injection opening 37.
[0057] Preferably, the nozzle tip 35 is joined to the valve seat
31. Because both the valve seat 31 and the nozzle tip 35 are
preferably made of metal, the valve seat 31 with the nozzle tip 35
may be joined by welding. Specifically, the upper end face 35a of
the nozzle tip 35 is positioned to face the lower end face 33a of
the valve seat 31, and the valve seat 31 is joined to the nozzle
tip 35 by welding 39, for example, laser welding, the
circumferential portion of the two facing parts. After the valve
seat 31 and the nozzle tip 35 are joined, the fuel injection nozzle
30 preferably is finished by polishing the seat portion 34.
[0058] In FIGS. 3 through 5, the upper half portion of the valve
seat 31 has been omitted, because those skilled in the art will
recognize that the upper end part of the valve seat 31 is attached
to the body of a fuel injection valve.
[0059] As described above, if the valve seat 31 and nozzle tip 35
are made of metal and are join by welding, brazing the valve seat
31 and nozzle tip 35 is no longer required. Furthermore, if the
injection opening 37 is formed by molding the nozzle tip 35 using
an MIM process, no drilling work on the nozzle tip 35 is required
to form the injection opening 37. Therefore, the manufacturing
process for a fuel injection nozzle is simplified and the accuracy
of the nozzle is substantially improved.
[0060] In addition, an integral type fuel injection nozzle, as
shown in FIG. 1, can be formed by metal injection molding. But if
an integral type fuel injection nozzle is molded by metal injection
molding, metal powder must be used. Therefore, it may be difficult
to obtain a precise surface roughness of the seat portion, even if
polishing is performed on the seat portion after molding.
Furthermore, in order to obtain a precise surface roughness, metal
powder having a small grain size must be used, thereby increasing
manufacturing costs.
[0061] On the other hand, in the first representative example,
because only the nozzle tip 35 is molded by metal injection
molding, only a small amount of metal powder is necessary, and a
larger grain size. The valve seat 31 also can be formed by forging
or machining. Therefore, even though the valve seat 31 and nozzle
tip 35 are joined by welding, a fuel injection nozzle according to
the first representative example can be produced at a cheaper cost
than that of an integral type fuel injection nozzle that is molded
by metal injection molding.
[0062] Second Representative Example
[0063] The second representative example of an improved fuel
injection nozzle will be described with reference to FIGS. 7
through 11. The fuel injection nozzle 40 comprises a cylindrical
valve seat 41 and a flat plate type nozzle tip 45.
[0064] A needle-like valve 42 is provided inside the valve seat 41
and can slide in the axial direction (the vertical direction in the
drawings). A seat portion 44 is formed in the valve seat 41 and the
valve 42 contacts the seat portion 44 during the operation of the
nozzle 40. The valve seat 41 may formed from a steel bar by a
forging process (for example, cold-forging). The steel bar may be,
for example, SUS440C (stainless steel). The valve seat 41 also can
be machined from a steel bar. The valve seat 41 is preferably
hardened in order to improve the wear resistance properties of the
seat portion 44.
[0065] A sack portion 46, which has a generally semi-spherical
inner circumferential surface 46a, and a flange portion 45a are
formed at the nozzle tip 45. The upper side 45b of the flange
portion 45a is formed so as to have substantially the same inner
and outer diameters as the diameters of the lower side 41a of the
valve seat 41. An injection opening 47 is formed in the sack
portion 46 and passes through a wall portion to inject fuel flowing
through the valve opening 43. For an in-cylinder injection type
fuel injection valve, the injection opening 47 is slit-shaped with
a section that opens in a fan shape at a predetermined angle. The
opening angle of the injection opening 47 is preferably between
about 30.degree. and 160.degree.. The nozzle tip 45 is preferably
made of metal and formed in a plate shape.
[0066] The nozzle tip 45 is joined to the valve seat 41. As
described in the first representative embodiment, if both the valve
seat 41 and the nozzle tip 45 are made of metal, the valve seat 41
and nozzle tip 45 can be joined by welding. However, because the
circumferential length of the joined portions of the valve seat 41
and the nozzle tip 45 in the second representative example is
longer than that of the first representative example, the welding
energy must be larger than in the first representative example.
After the valve seat 41 and the nozzle tip 45 are joined, a fuel
injection nozzle 40 is again finished by polishing the seat portion
44.
[0067] As in the first representative example, the upper half
portion of the valve seat 41 has been omitted in FIGS. 7 and 8,
because a person of skill in the art would recognize that the upper
end portion of the valve seat 41 is attached to the body of the
fuel injection valve.
[0068] Preferably, nozzle tip 45 is preferably manufactured
according to the following steps shown in FIGS. 12-23. Metal
material W formed into a generally flat rectangular shape by
forging (for example, cold-forging), for example, a plate-like
material of SUS316 (stainless steel), as shown in FIGS. 12 and 13.
Positioning holes W1 are formed at both the left and right ends of
material W.
[0069] A sack portion 46 having a generally semi-spherical inner
circumferential surface 46a at the central portion of the material
W is first formed by forging (for example, cold-forging), as shown
in FIGS. 14 and 15. An injection opening 47 is then formed in the
sack portion 46 of material W by laser machining, as shown in FIGS.
16 and 17. If dross accumulates inside (i.e., the inner
circumferential surface 46a side) the nozzle tip 45, the
measurement accuracy of injected fuel may be diminished. Therefore,
the laser machining is preferably performed from the upstream side
of the injection opening 47 (with respect to the fuel injection
direction). In this representative example, because the nozzle tip
45 is a separate from the valve seat 41, the laser machining can be
performed while accurately and directly supplying an assisting gas
and without the use of an optical fiber or any special light
condensing device.
[0070] The nozzle tip 45 can be completed by punching out the
circular portion (the portion shown with a double-dashed line 48 in
FIG. 16), including the sack portion 46, from the material W.
According to this method, the injection opening 47 may be formed
either before or after punching out the nozzle tip 45 from the
material W.
[0071] Preferably, the injection opening 47 is formed by laser
machining process shown in FIGS. 18 and 19. Specifically, a laser
beam is emitted from a laser beam emitting device and irradiates
the inner circumferential surface 46a of the sack portion 46 from
the upstream side to form the injection opening 47. A fixture (not
shown) preferably fixes the nozzle tip 45 (or the material W)
during this step. The optical axis B1 of the laser beam is then
turned in the direction of the arrow A1 shown in FIG. 19 to center
around the vicinity of the center C of the inner circumferential
surface 46a of the sack portion 46. Thus, a slit-like injection
opening 47 is formed with fan shaped section having a predetermined
angle.
[0072] In the fuel injection nozzle according to the second
representative example, it is not necessary to use any optical
fiber or any special light condensing device, and the injection
opening 47 can be formed by laser machining while directly and
accurately supplying an assisting gas from the upstream side of the
injection opening 47. Further, a laser beam can be directed onto
the surface of a nozzle tip at any desired position and at any
desired angle. Therefore, the injection opening 47 can be quickly
manufactured with improved measurement accuracy at any profile. As
was the case with the first representative example, because both
the valve seat 41 and the nozzle tip 45 are made of metal, the
valve seat 41 and the nozzle tip 45 can be joined by welding 49,
thereby eliminating the need for a brazing step. Consequently, the
ease of manufacturing accurate fuel injection nozzles can be
further improved.
[0073] In the above-describe method, although an injection opening
47 was formed by irradiating only one side of the injection opening
47, the injection opening 47 can be formed by irradiating both
sides of the injection opening 47.
[0074] For example, the injection opening 47 can be formed by the
alternative method shown in FIGS. 20 and 21. That is, the upstream
side of injection opening is irradiated by a first laser beam
toward the inner circumferential surface 46a of the sack portion
46. At the same time, the downstream side of the injection opening
47 is irradiated by a second laser beam toward the outer
circumferential side of the sack portion 46. The optical axes B1
and B2 of both laser beams are then turned in the directions of the
arrows A1 and A2 shown in FIG. 21 centering around the vicinity of
the center C of the inner circumferential surface 46a of the sack
portion 46. In this case, the dimensional accuracy at the
downstream side of the injection opening 47 can be improved.
[0075] Alternatively, the upstream side of the injection opening 47
can be irradiated before the downstream side of the injection
opening 47 to form the injection opening 47. In this case,
substantially no spatters and dross will adhere to the inside of
the nozzle tip 45. Thus, the dimensional accuracy of both the
upstream and downstream sides of the injection opening 47 can be
improved.
[0076] In addition, an injection opening 47 can be formed by the
method shown in FIGS. 22 and 23. In particular, the upstream side
of the injection opening 47 is irradiated by a laser beam toward
the inner circumferential surface 46a of the sack portion 46. The
laser beam then irradiates the downstream side of the injection
opening 47 toward the outer circumferential surface of the sack
portion 46. Preferably, the optical axis B1 of the upstream side
laser beam is moved in the direction of arrow A3 shown in FIG. 23,
i.e., is moved in parallel to the width direction of the slit. At
the same time, the optical axis B2 of the downstream laser beam is
turned in the direction of arrow A2, is centered around the
vicinity of the center C of the inner circumferential surface 46a
of the sack portion 46. If this method is used, after the laser
beam irradiates the upstream side of the injection opening 47, the
laser beam irradiates the downstream side of the injection opening
47. As a result, the injection opening 47 can be formed using a
single laser beam.
[0077] Third Representative Example
[0078] The third representative example of an improved fuel
injection nozzle will be described with reference to FIG. 24. In
this representative example only the portions that have been
changed from the first and second representative examples will be
described.
[0079] As shown in FIG. 24, a generally cylindrical projection
portion 51a is formed on the outer circumferential side of the
lower end of the valve seat 51, thereby forming a stepped surface
51c along the inner circumferential side of the lower end of the
valve seat 51. The inner circumferential surface 51b of the
projection portion 51a has a cylindrical surface and is slidably
connected to the outer circumferential surface of the nozzle tip
55. A concave portion, which can be joined to the upper end 55a of
the nozzle tip 55, is formed by the interface of the inner
circumferential surface 51b and stepped surface 51c of the
projection portion 51a. In this representative example, an engaging
member consisting of a projection portion and a concave portion,
which can engaged with each other, comprises the upper end portion
55a of the nozzle tip 55 and a concave portion of the valve seat
that can be engaged with the upper end portion 55a of the nozzle
tip 55.
[0080] If the valve seat 51 and nozzle tip 55 are joined, the
concave portion of the valve seat 51 is joined to the upper end
portion 55a of the nozzle tip 55. The inner circumferential portion
at the lower end of the projection portion 51a of the valve seat 51
can be joined to the outer circumferential surface of the nozzle
tip 55, for example, by laser welding 59. Consequently, if the
concave portion of the valve seat 51 and projection portion 55a of
the nozzle tip 55 are joined, the valve seat 51 and nozzle tip 55
can be co-axially joined.
[0081] Fourth Representative Example
[0082] The fourth representative example of an improved fuel
injection nozzle will be described with reference to FIG. 25. In
this example, a generally cylindrical projection portion 61a is
formed along the outer circumferential side at the lower end of the
valve seat 61, thereby forming a stepped surface 61c at the inner
circumferential side of the lower end of the valve seat 61. The
inner circumferential surface 61b of the projection portion 61a is
formed along a cylindrical surface that is slidably connected to
the outer circumferential surface of the flange portion 65a of the
nozzle tip 65. A concave portion, which can be engaged with the
flange portion 65a of the nozzle tip 55 is formed by the interface
of the inner circumferential surface 61b and stepped surface 61c of
the projection portion 61a. In this representative example, an
engaging member consisting of a projection portion and a concave
portion, which can be joined together, comprises the flange portion
65a of the nozzle tip 65 and the concave portion of the valve seat
61 that can be engaged with the flange portion 65a of the nozzle
tip 65.
[0083] If the valve seat 65 and nozzle tip 65 are joined, the
concave portion of the valve seat 61 is engaged to the flange
portion 65a of the nozzle tip 65. The inner circumferential portion
of the lower end of the projection portion 61a of the valve seat 61
and the outer circumferential surface of the flange portion 65a of
the nozzle tip 65 can be joined, for example, by laser welding 69.
As was the case with the third representative example, if the
concave portion of the valve seat 61 and flange portion 65a of the
nozzle tip 65 are joined, the valve seat 61 and nozzle tip 65 can
be co-axially joined.
[0084] Fifth Representative Example
[0085] The fifth representative example of an improved fuel
injection nozzle will be described with reference to FIG. 26. In
this example, a generally cylindrical projection portion 71a is
formed along the inner circumferential side of the lower end of the
valve seat 71, thereby forming a stepped surface 71d along the
outer circumferential side of the lower end of the valve seat 71.
Further, a generally cylindrical projection portion 75a is formed
along the outer circumferential side of the upper end of the nozzle
tip 75. Thus, a stepped surface 75c is formed along the inner
circumferential side of the upper end of the nozzle tip 75. The
inner circumferential surface 75b of the projection portion 75a is
formed of a cylindrical surface that is slidably connected to the
outer circumferential surface 71b of the projection portion 71a of
the valve seat 71. A concave portion that can be engaged with the
projection portion 75a of the nozzle tip 75 is formed by the
interface of the outer circumferential surface 71b and the stepped
surface 71c of the projection portion 71a. In this representative
example, an engaging member consisting of a projection portion and
a concave portion that can be engaged with each other, comprises
the projection portion 75a of the nozzle tip 75 and a concave
portion of the valve seat 71 that can be engaged with the
projection portion 75a of the nozzle tip 75.
[0086] If the valve seat 71 and the nozzle tip 75 are joined, the
concave portion of the valve seat 71 and the projection portion 75a
of the nozzle tip 75 are engaged with each other. Then, the upper
end portion of the projection portion 75a of the nozzle tip 75 and
the outer circumferential portion of the stepped portion 71d of the
valve seat 71 can be joined by laser welding 79 or a similar
operation.
[0087] In the fuel injection nozzle 70 according to the fifth
representative example, because the concave portion of the valve
seat 71 and the projection portion 75a of the nozzle tip 75 are
joined with both engaged with each other, it is possible to easily
secure the coaxiality of the valve seat 61 and the nozzle tip 65
when they are joined.
[0088] Sixth Representative Example
[0089] The sixth representative example of an improved fuel
injection nozzle will be described with reference to FIG. 27. In
this example, a tapered surface 81b is formed along the outer
circumferential side of the lower end of the valve seat 81, thereby
forming a projection portion 81a along the lower end portion of the
valve seat 81. Further, a generally conically inverse cylindrical
projection portion 85a is formed along the outer circumferential
side of the upper end of the nozzle tip 85, thereby forming a
stepped surface 85c along the inner circumferential side of the
upper end of the nozzle tip 85. The inner circumferential surface
85b of the projection portion 85a is formed into a tapered surface
that is brought into facial contact with the tapered surface 81b of
the valve seat 81. A concave portion that can be engaged with the
projection portion 81a of the valve seat 81 is formed by the
interface of the inner circumferential surface 85b and stepped
surface 85c of the projection portion 85a. In this representative
example, an engaging member consisting of a projection and a
concave portion that can be engaged with each other comprises the
projection portion 81a of the valve seat 81 and the concave portion
of the nozzle tip 85 that can be engaged with the projection 81a of
the valve seat 81.
[0090] This embodiment can be joined in the same manner as the
previous examples to yield the same advantages.
[0091] Seventh Representative Example
[0092] In the fuel injection nozzle used with an in-cylinder
injection type fuel injection valve that directly injects fuel into
a cylinder of an internal combustion engine, the injection opening
has been formed so that fuel is injected in a cylinder
substantially in the form of a fan (also known as fan-like
injection). For example, a slit-like injection opening having a fan
shape with a predetermined angle is formed in the sack portion
having a semi-spherical inner circumferential surface. In a known
fuel injection nozzle, because the relationship between the center
of the semi-spherical inner circumferential surface of the sack
portion and the center of the opening angle of the injection
opening is not specified, the injection angle of fan-like injection
was not stable. Therefore, an object of this representative example
is to stabilize the injection angle of fan-like injection.
[0093] Thus, a seventh representative example of an improved fuel
injection nozzle will be described with reference to FIGS. 28
through 30. A fuel injection nozzle 90 according to this
representative example comprises a valve opening 93 in which a
generally needle-like valve 92 of the fuel injection valve is
slidably provided in the axial direction (the horizontal direction
in FIGS. 29 and 30), a seat portion 94 on which the valve 92 is
seated, and a sack portion 96 attached to the downstream side of
the seat portion 94. A slit-like injection opening 97 that passes
through the inner circumferential surface 96a and the wall portion
of the sack portion 94 is formed in the sack portion 94.
[0094] The fuel injection pressure is, for example, 120 kg/cm.sup.2
and the fuel injection nozzle 90 may be formed as an integral type
fuel injection nozzle or may be formed as a two-piece fuel
injection nozzle. If a two-piece fuel injection nozzle design is
utilized as described in the above-mentioned embodiments, a fuel
injection nozzle can be constructed with both the features of this
representative example and features of the above-mentioned
representative examples.
[0095] As shown in FIG. 30, the inner circumferential surface 96a
of the sack portion 96 has a semi-spherical inner circumferential
surface 96a with a center Ps and a radius Rs. The radius Rs of the
semi-spherical inner circumferential surface 96a is, for example,
about 0.4 mm. Furthermore, the thickness T of the wall portion of
the sack portion 96 is, for example, between about 0.2 and 1.2 mm.
The semi-spherical inner circumferential surface 96a of the sack
portion 96 is connected to the seat portion 94 via a cylindrical
inner circumferential surface 96b of a predetermined length, the
radius of which is Rs.
[0096] The injection opening 97 opens in a fan shape with a
predetermined angle .theta.1, as shown in FIG. 30. The opening
angle .theta.1 of the injection opening 97 is, for example, between
about 30.degree. through 160.degree.. The injection opening 97
preferably has a center that is symmetrical around the axis line Ax
of the fuel injection nozzle 90. Furthermore, the width W of the
injection opening 97 shown in FIG. 28 is, for example, about 0.2
mm.
[0097] In this representative example, the center Ph of the opening
angle of the injection opening 97 is positioned at a further
upstream side in the fuel injection direction than the center Ps of
the semi-spherical inner circumferential surface 96a of the sack
portion 96. Furthermore, the distance Pb from the center Ps of the
semi-spherical inner circumferential surface 96a of the sack
portion 96 to the center Ph of the opening angle of the injection
opening 97 is set according to the following relation:
0.ltoreq.Pb.ltoreq.0.75Rs.
[0098] In this example, because the radius Rs of the semi-spherical
inner circumferential surface 96a is preferably 0.4 mm, the
dimension Pb is set according to the following relation:
0.ltoreq.Pb.ltoreq.0.3 mm.
[0099] These two relations have been determined based on the
following analysis. The graph shown in FIG. 3 characterizes the
measurement of the spread angle of the fan-like injection opening
with respect to the opening angle .theta.1 of the injection opening
97. Specifically, the ratio (.theta.2/.theta.1) of the injection
(spraying) angle .theta.2 was measured while sliding the center Ph
of the opening angle of the injection opening 97 step by step along
the axial line Ax of the fuel injection nozzle 90.
[0100] In FIG. 30, the injection (spraying) angle .theta.2 is shown
in terms of a hypothetical broadly spread angle. In FIG. 31, the
abscissa indicates the dimension Pb (which is shown by a ratio of
the semi-spherical inner circumferential surface 96a to the radius
Rs), and the ordinate indicates the angle ratio
(.theta.2/.theta.1). The distance Pb is zero when the center Ph of
the opening angle of the injection opening 97 is at the same
position as the center Ps of the semi-spherical inner
circumferential surface 96a. Further, the distance Pb is assigned a
negative value when it deviates in the downstream side from the
center Ps of the semi-spherical inner circumferential surface 96a
and is assigned a positive value when it deviates in the upstream
side from the center Ps of the semi-spherical inner circumferential
surface 96a.
[0101] According to the characteristic diagram of FIG. 31, if the
dimension Pb is less than zero, the angle ratio (.theta.2/.theta.1)
becomes remarkably small. Therefore, the opening angle .theta.1
does not correspond to the injection angle .theta.2. On the other
hand, if the dimension Pb is zero or greater, the angle ratio
(.theta.2/.theta.1) becomes approximately 1. Therefore, the opening
angle .theta.1 substantially corresponds to the injection angle
.theta.2.
[0102] By positioning the center Ph of the opening angle of the
injection opening 97 at a further upstream side than the center Ps
of the semi-spherical inner circumferential surface 96a, a fan-like
injection of an injection angle .theta.2 that is almost equal to
the opening angle .theta.1 of the injection opening 97 can be
obtained. Thus, it is possible to stabilize the injection angle
.theta.2 of the fan-like injection.
[0103] Furthermore, the characteristic diagram shown in FIG. 32 was
obtained by measuring the injection distribution ratio of a
fan-like injection while sliding the center Ph of the opening angle
of the injection opening 97 step by step along the axial line Ax of
the fuel injection nozzle 1. In FIG. 32, the abscissa shows the
dimension Pb as in FIG. 31, and the ordinate shows the injection
distribution ratio Dp(%). Further, the injection distribution ratio
Dp was measured using four equally divided both-end distribution
ratios. As shown in FIG. 33, the spread width of the injection
distribution of the injection angle .theta.2 was divided into four
equal parts (1), (2), (3) and (4). If the quantity of fuel
distributed in the respective parts (1), (2), (3) and (4) are D1,
D2, D3 and D4, the injection distribution ratio Dp is calculated
using the following expression:
Dp={ (D1+D4)/(D1+D2+D3+D4)} .times.100.
[0104] According to the graph of FIG. 32, because the injection
distribution ratio Dp is remarkably increased if the dimension Pb
is 0.75Rs or greater, the injection distribution does not become
uniform. On the other hand, because the injection distribution
ratio Dp is approximately 50 through 60%, if the dimension Pb is
0.75Rs or less, the injection distribution is uniform. Therefore,
by positioning the center Ph of the opening angle of the injection
opening 97 further upstream than the center Ps of the
semi-spherical inner circumferential surface 96a, e.g. at a
position in which Pb.ltoreq.0.75Rs, it is possible to make the
injection distribution of the fan-like injection uniform.
[0105] Therefore, by setting the distance Pb according to the
relation:
0.ltoreq.=Pb.ltoreq.0.75Rs,
[0106] the injection angle .theta.2 of the fan-like injection can
be stabilized, and at the same the injection distribution of the
fan-like injection can be made uniform.
[0107] These examples can be modified in a variety of ways without
departing from the spirit of the invention. For example, the
profile of the injection opening is not limited to a slit, and it
may be changed to circular, elliptical, polygonal or like profiles
in compliance with the injection characteristics of the fuel. In
addition, the number of injection openings and positions in which
the opening are formed can be variously changed in compliance with
the injection characteristics of the fuel. Further, the profile,
number, and forming positions of the projection portions and
concave portions of the engaging member may be variously changed in
a range in which the coaxiality between the valve seat and the
nozzle tip can be maintained. Although the above description has
been given of a fuel injection nozzle used in a fuel injection
valve that supplies fuel to an internal combustion engine, the fuel
injection nozzle according to the invention may naturally be used
with fluids other than fuel.
* * * * *