Information
-
Patent Grant
-
6199776
-
Patent Number
6,199,776
-
Date Filed
Tuesday, December 14, 199924 years ago
-
Date Issued
Tuesday, March 13, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 239 5851
- 239 5854
- 239 5855
- 239 900
- 251 12921
- 029 890124
- 029 890126
- 029 89013
- 029 890132
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International Classifications
-
Abstract
A fuel injection valve that possesses an axially movable valve needle which includes at least one armature and one spherical valve closure element. The armature forms a closure element support which is joined at its downstream end to the valve closure element. The end of the closure element support facing toward the valve closure element is deformed in such a way that a polygonal profile is present. In accordance with the number of profile edges, at least two flowthrough openings, communicating with an inner longitudinal bore, are formed between the closure element support and the surface of the valve closure element, through which openings fuel can easily flow.
Description
BACKGROUND INFORMATION
The present invention is based on a fuel injection valve, and on a method for manufacturing a valve needle of a fuel injection valve.
A fuel injection valve in which a valve needle is constituted from an armature, a tubular joining part, and a spherical valve closure element is already known from German Published Patent Application 38 31 196 or German Published Application Patent no. 40 08 675. The armature and the valve closure element are joined to one another via the tubular joining element, the joining part, to which the valve closure element is immovably joined via a weld bead, serving as the immediate closure element support. The joining part has a plurality of transversely extending flow openings through which fuel can emerge from an internal passthrough opening and flow, outside the joining part, to the valve closure element and to a valve seat surface coacting with the valve closure element. In addition, the joining tube has a longitudinal slit, extending over the entire length, through which, because of its large hydraulic flow cross section, fuel arriving from the inner passthrough opening can flow very quickly. Most of the fuel to be discharged already flows out of the joining part over its length. The remaining quantity emerges directly from the joining part only upon reaching the spherical surface, so that when viewed over the joining region between joining part and valve closure element, which extends over 360 degrees, there is a definite inhomogeneity in fuel distribution.
SUMMARY OF THE INVENTION
The fuel injection valve according to the present invention, has the advantage that opportunities for fuel flow at the valve needle can be created in economical, reliable, and particularly simple fashion. The valve needle includes at least one closure element support and one valve closure element. The closure element support is shaped, at its end facing the valve closure element, in a manner which deviates from an annular profile such that at least two flowthrough openings are formed between the closure element support and the surface of the valve closure element, through which fuel arriving from an inner longitudinal bore can flow unimpeded toward a valve seat surface. In particularly simple fashion, the downstream end of the closure element support is plastically deformed by deformation tools from an annular profile into a polygonal profile. Optimum flow to the metering region of the valve is thus achieved with little production outlay.
Advantageously, the fuel flows to the surface of the valve closure element in the interior of the closure element support. As compared with known valves, this eliminates transverse openings and slits in the closure element support, which are otherwise needed for the fuel to emerge from the internal sleeve opening of the closure element support. Also eliminated are the machining problems (e.g. deburring) associated with such transverse openings.
In particularly advantageous fashion, the valve closure element is of spherical configuration, so that centering of the valve closure element on the closure element support is particularly easy.
The polygonal profile of the closure element support has an equal number of angle regions and edge regions, corresponding to the number of flowthrough openings. A triangular profile results in the best compromise between the greatest possible open cross section for the sum of the flowthrough openings and good centering of the valve closure element on the closure element support. Great variability in the individual profiles of the closure element support can be created by using different deformation tools.
In particularly advantageous fashion, the armature can itself serve directly as the closure element support, so that together with the valve closure element a two-part valve needle is present. A valve needle of this kind is particularly easy and economical to manufacture, and because of the reduced parts count has only the join to be made between the valve closure element and closure element support.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
shows a fuel injection valve according to the present invention.
FIG. 2
shows an armature, serving as closure element support, with a deformation tool.
FIG. 3
shows a two-part valve needle.
FIG. 4
shows a section through a closure element support with a triangular profile, along line IV—IV in FIG.
3
.
FIG. 5
shows a section through a closure element support with a pentagonal profile.
FIG. 6
shows a tripartite valve needle.
FIG. 7
shows a first illustration of a valve closure element that deviates from a spherical shape and can be mounted on a closure element support.
FIG. 8
shows a second illustration of a valve closure element that deviates from a spherical shape and can be mounted on a closure element support.
FIG. 9
shows a third illustration of a valve closure element that deviates from a spherical shape and can be mounted on a closure element support
DETAILED DESCRIPTION
The valve according to the present invention depicted in the form of an electromagnetically actuable fuel injection valve for fuel injection systems of mixture-compressing, spark-ignited internal combustion engines, has a largely tubular core
2
which is surrounded by a magnet coil
1
and serves as internal pole and partly as a fuel passage. Together with an upper disk-shaped cover element
3
, core
2
makes possible a particularly compact configuration of the injection valve in the region of magnet coil
1
. Magnet coil
1
is surrounded by an external ferromagnetic valve shell
5
constituting the external pole, which completely surrounds magnet coil
1
in the circumferential direction and is immovably joined at its upper end to cover element
3
, e.g. by a weld bead
6
. To close the magnetic circuit, valve shell
5
is embodied in stepped fashion at its lower end, thus forming a guide segment
8
which, similarly to cover element
3
, axially encloses magnet coil
1
and represents the boundary of magnet coil region
1
toward the bottom or in the downstream direction.
Guide segment
8
of valve shell
5
, magnet coil
1
, and cover element
3
form an internal opening
11
and
58
, running concentrically with a longitudinal valve axis
10
, in which an elongated sleeve
12
extends. An inner longitudinal opening
9
of ferritic sleeve
12
serve partly as guide opening for a valve needle
13
that is axially movable along longitudinal valve axis
10
. Sleeve
12
is therefore produced in dimensionally accurate fashion with respect to the inside diameter of internal opening
9
. Viewed in the downstream direction, sleeve
12
ends, for example, in the region of guide segment
8
of valve shell
5
, to which it is immovably joined, for example, with a weld bead
54
. The stationary core
2
is also arranged in longitudinal opening
9
of sleeve
12
outside the axially movable valve needle
13
. In addition to receiving core
2
, sleeve
12
also performs a sealing function, so that magnet coil
1
present in the injection valve is dry. This is also achieved by the fact that the disk-shaped cover element
3
completely covers magnet coil
1
on its upper side. Inner opening
58
in cover element
3
makes it possible to configure sleeve
12
and thus also core
2
in elongated fashion, so that both components pass through opening
58
and project beyond cover element
3
.
Adjoining the lower guide segment
8
of valve shell
5
is a valve seat element
14
which has a fixed valve seat surface
15
constituting a valve seat. Valve seat element
14
is immovably joined to valve shell
5
, by way of a second weld bead
16
produced, for example, with a laser. Valve needle
13
is constituted by a tubular armature
17
and a, for example, spherical valve closure element
18
joined immovably thereto, armature
17
serving directly as the closure element support. Valve closure element
18
has on its circumference, for example, five flattened areas
23
which allow fuel to flow past valve closure element
18
to valve seat surface
15
. Arranged at the downstream end face of valve seat element
14
, for example in a depression
19
, is a flat perforated spray disk
20
, the immovable joining between valve seat element
14
and perforated spray disk
20
being attained, for example, using a peripheral sealed weld bead
21
.
Actuation of the injection valve is accomplished, in known fashion, electromagnetically. The electromagnetic circuit having magnet coil
1
, inner core
2
, outer valve shell
5
, and armature
17
serves to move valve needle
13
axially, and thus to open the injection valve against the spring force of a return spring
25
and to close it. Armature
17
faces toward core
2
with its end which faces away from valve closure element
18
.
The spherical valve closure element
18
coacts with valve seat surface
15
of valve seat element
14
, that surface tapering in truncated conical form in the flow direction and being configured in valve seat element
14
axially downstream of a guide opening
26
. Perforated spray disk
20
possesses at least one, for example four spray openings
27
shaped by electrodischarge machining or punching.
The depth to which core
2
is inserted in the injection valve governs, inter alia, the linear stroke of valve needle
13
. The one end position of valve needle
13
, when magnet coil
1
is not energized, is defined by contact of valve closure element
18
against valve seat surface
15
of valve seat element
14
, while the other end position of valve needle
13
, when magnet coil
1
is energized, results from contact of armature
17
against the downstream end of core
2
. Linear stroke adjustment is performed by axial displacement of core
2
in sleeve
12
, which, in accordance with the desired position, is then immovably joined to sleeve
12
, a laser weld being useful for producing a weld bead
22
.
In addition to return spring
25
, an adjusting sleeve
29
is inserted into a flow bore
38
of core
2
which runs concentrically with longitudinal valve axis
10
and serves to convey fuel toward valve seat surface
15
. Adjusting sleeve
29
serves to adjust the spring preload of return spring
25
, which rests against adjusting sleeve
29
and in turn is braced at its opposite end against a shoulder
28
of armature
17
; the dynamic spray discharge volume is also adjusted using adjusting sleeve
29
.
An injection valve of this kind is characterized by its particularly compact configuration, resulting in a very small, manageable injection valve whose valve shell
5
has, for example, an outside diameter of only approximately 11 mm. The components so far described form a preassembled independent assembly which can be referred to as functional part
30
. The completely adjusted and assembled functional part
30
has, for example, an upper end surface
32
beyond which, for example, two contact pins
33
project. By way of electrical contact pins
33
, which serve as electrical connecting element, electrical contact is made to magnet coil
1
and it is thereby energized.
A functional part
30
of this kind can be joined to a connector part (not depicted), which is characterized principally in that it comprises the electrical and hydraulic connection to the injection valve. A hydraulic connection between the connector part (not depicted) and functional part
30
is achieved, when the injection valve is completely assembled, by the fact that flow bores of the two assemblies are brought together so as to ensure that fuel can flow through unimpeded. In this context, for example, end surface
32
of functional part
30
rests directly against a lower end surface of the connector part, and is immovably joined thereto. When the connector part is mounted onto functional part
30
, the portion of core
2
and of sleeve
12
projecting beyond end surface
32
can, in order to increase connection stability, project into a flow bore of the connector part. For secure sealing, a sealing ring
36
, for example, is provided in the joining region, resting on end surface
32
of cover element
3
and surrounding sleeve
12
. In the completely assembled valve, contact pins
33
serving as electrical connection elements participate in a secure electrical connection with corresponding electrical connection elements of the connector part.
FIG. 2
shows armature and closure element support
17
, at a larger scale than in
FIG. 1
, with a deformation tool
40
and
41
. The tubular armature serving as closure element support
17
is embodied, for example, as a turned part which possesses, in addition to an inner longitudinal bore
45
that is stepped thanks to shoulder
28
, a stepped outer contour as well. Closure element support
17
, made for example from a ferritic material (e.g. 13% chromium steel), has an upper stop surface
42
, facing core
2
, which is equipped with a wear protection layer, i.e. is chrome-plated. Shaped out of the external periphery of closure element support
17
, in a larger-diameter first segment
47
, is, for example, an annular guide surface
43
which serves to guide the axially movable valve needle
13
in sleeve
12
. Analogously to shoulder
28
in inner longitudinal bore
45
, a step
46
is provided on the outer contour, resulting in a reduction in cross section in a second segment
48
when viewed in the downstream direction. Larger- and smaller-diameter segments
47
and
48
each initially possess a circular cross section.
According to the present invention, the annular cross section of the end of closure element support
17
facing the spherical valve closure element
18
, i.e. in the exemplary embodiment that of segment
48
shown in
FIG. 2
, is changed into a cross section which has at least two corners
60
and edges
61
(FIG.
4
). Corners
60
and edges
61
do not by any means, however, need to be sharp-edged or straight. Instead, corners
60
can be rounded and edges
61
can be curved, i.e. bulging. In order to obtain a profile of this kind which deviates from a hollow cylindrical shape, a plastic deformation of the joining region, at which valve closure element
18
that is to be mounted is later attached, is performed in segment
48
. As already indicated in
FIG. 2
with the two deformation tools
40
and
41
, there are two possibilities for deforming closure element support
17
at its lower segment
48
facing toward valve closure element
18
. The first deformation possibility lies in introducing a deformation tool
40
into the inner longitudinal bore
45
in segment
48
and performing a desired deformation of segment
48
from the inside. The second deformation possibility provides for allowing a deformation tool
41
to act on the outer periphery of segment
48
in order to achieve a desired deformation of segment
48
. In addition, for example, it is possible also to introduce a shaping punch into the inner longitudinal bore
45
and apply to the outer periphery a deformation tool
41
with which the contour of the shaping punch is reproduced in segment
48
.
After the deformation of segment
48
of closure element support
17
, spherical valve closure element
18
is immovably attached to this deformed segment
48
, thus completing the axially movable valve needle
13
, as is evident from FIG.
3
. Valve closure element
18
is joined to the respective edge regions
61
′ of the deformed profile; as is desired, immovable joins cannot be made in corner regions
60
′. The immovable joins between closure element support
17
and valve closure element
18
are created, for example, by way of weld beads
63
produced with a laser, the number of weld beads
63
corresponding exactly to the number of edge regions
61
′.
The formation of corner regions
60
′ results in the creation of regions at the downstream end of segment
48
which do not rest against the surface of valve closure element
18
. The result of the plastic deformation of segment
48
has thus been to create at corner regions
60
′ flowthrough openings
65
through which, in particularly favorable fashion, fuel arriving from longitudinal bore
45
flows toward valve seat surface
15
. This embodiment of valve needle
13
allows fuel to flow in very simple fashion to the metering region of the injection valve.
FIG. 4
is a sectioned depiction of a section along line IV—IV in
FIG. 3
which illustrates in particularly descriptive fashion corner s
60
and edges
61
of closure element support
17
, and flowthrough openings
65
, after the attachment of valve closure element
18
. It is particularly advantageous to use deformation tools
40
,
41
with shaping punches with which a triangular profile can be produced. The three corner regions
60
′ and three edge regions
61
′ in the profile of segment
48
result in three flowthrough openings
65
. Valve closure element
18
is attached to edge regions
61
′ with three weld beads
63
. A triangular profile yields the best compromise between the greatest possible open cross section for the sum of flowthrough openings
65
, and good centering of valve closure element
18
on closure element support
17
. In addition to a triangular profile, however, profiles with two, four, five (FIG.
5
), or possibly even more corners
60
and edges
61
are also conceivable for closure element support
17
.
FIG. 6
depicts a second exemplary embodiment of a valve needle
13
in which parts which remain the same as or operate identically to those in the exemplary embodiment depicted in
FIG. 3
are identified by the same reference characters. Valve needle
13
as shown in
FIG. 6
is distinguished from valve needle
13
shown in
FIG. 3
by its tripartite nature. In this exemplary embodiment of valve needle
13
, armature
17
and valve closure element
18
are joined to one another by a sleeve-like joining part
50
.
Valve closure element
18
is again provided immovably on valve needle
13
, by way of weld be ads
63
in the manner described above, but in this case not to armature
17
but rather to joining part
50
which now serves as the closure element support. All statements regarding the deformation of segment
48
on closure element support
17
in the example according to
FIG. 2
are entirely transferrable to joining part
50
according to
FIG. 6
, since the geometry and function are comparable.
In addition to the configuration of closure element support
17
,
50
as a turned part or cold-pressed part, embodiments as a sintered part or metal injection-molded (MIM) part are also possible.
It should be mentioned that while the spherical shape of valve closure element
18
is particularly preferred because of its ease of centering, it is nevertheless not exclusive. Indeed, valve closure elements
18
having a cylindrical shape with a spherical polished portion (FIG.
7
), a cylindrical shape with a conical tip (FIG.
8
), a cylindrical shape with two opposing conical tips (FIG.
9
), a semi-spherical shape, and so forth, can also be attached to closure element support
17
,
50
.
Claims
- 1. A fuel injection valve, comprising:a magnet coil; a core at least partially surrounded by the magnet coil and having a longitudinal valve axis; a fixed valve seat; and an axially movable valve needle at least partially surrounded by the core and including at least one closure element support and a valve closure element, the valve closure element being immovably joined to the at least one closure element support and coacting with the fixed valve seat, and the at least one closure element support having an inner longitudinal bore extending to a surface of the valve closure element, wherein: an end of the at least one closure element support facing the valve closure element includes a contour that deviates from an annular profile such that at least two flowthrough openings in communication with the inner longitudinal bore are formed between the at least one closure element support and the surface of the valve closure element.
- 2. The valve according to claim 1, wherein the contour of the end of the at least one closure element support facing the valve closure element has a triangular profile.
- 3. The valve according to claim 1, wherein the contour of the end of the at least one closure element support facing the valve closure element has a pentagonal profile.
- 4. The valve according to claim 1, wherein a downstream end of the at least one closure element support includes corner regions and edge regions in an equal number, the number of corner regions and edge regions corresponding to a number of the at least two flowthrough openings.
- 5. The valve according to claim 4, wherein each edge region is an attachment region for the valve closure element on the at least one closure element support.
- 6. The valve according to claim 5, wherein the valve closure element is immovably joined to the edge regions by way of weld beads.
- 7. The valve according to claim 1, wherein an outer periphery of the valve closure element includes a plurality of flattened areas.
- 8. The valve according to claim 1, wherein the at least one closure element support is formed as an armature.
- 9. The valve according to claim 1, further comprising:an armature; a joining part serving as the at least one closure element support and joining the armature and the valve closure element.
- 10. The valve according to claim 1, wherein the at least one closure element support corresponds to one of a turned part and a cold-pressed part.
- 11. The valve according to claim 1, wherein a configuration of the valve closure element is spherical.
- 12. A method for manufacturing a valve needle of a fuel injection valve, comprising the steps of:providing a metal closure element support having: an inner longitudinal bore, a circular cross section, and a circular outer contour; providing a valve closure element; using at least one deformation tool to plastically deform an end of the metal closure element support that is to face toward the valve closure element such that the metal closure element support includes at the end that is to face toward the valve closure element a contour that deviates from an annular profile, the metal closure element including a plurality of corner regions and a plurality of edge regions; and subsequent to the step of using the at least one deformation tool, attaching the valve closure element to the deformed end of the metal closure element support.
- 13. The method according to claim 12, further comprising the step of:attaching an armature on a side of the metal closure element support located opposite to the valve closure element.
- 14. The method according to claim 12, further comprising the step of performing one of the steps of:engaging the at least one deformation tool in the inner longitudinal bore, and engaging the at least one deformation tool on an outer periphery of the metal closure element support.
Priority Claims (1)
Number |
Date |
Country |
Kind |
197 84 847 |
Nov 1997 |
DE |
|
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
102e Date |
371c Date |
PCT/DE98/02434 |
|
WO |
00 |
12/14/1999 |
12/14/1999 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO99/27246 |
6/3/1999 |
WO |
A |
US Referenced Citations (8)
Foreign Referenced Citations (3)
Number |
Date |
Country |
38 31 196 |
Mar 1990 |
DE |
40 08 675 |
Sep 1991 |
DE |
62-087661 |
Sep 1987 |
JP |