Information
-
Patent Grant
-
6799734
-
Patent Number
6,799,734
-
Date Filed
Monday, September 24, 200122 years ago
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Date Issued
Tuesday, October 5, 200419 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 239 5851
- 239 5855
- 277 916
- 251 12915
- 251 12919
- 251 12921
- 335 257
- 335 277
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International Classifications
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Abstract
A fuel injector for fuel injection systems of internal combustion engines, having a valve needle which works together with a valve seat face to form a sealing seat, has an armature acting on the valve needle. The armature is movably guided on the valve needle and is damped by an elastomer ring made of an elastomer. The armature has at least one fuel channel for supplying fuel to the sealing seat. A flat supporting ring which axially supports the elastomer ring in the area of the outlet end of the fuel channel is arranged between the elastomer ring and the armature.
Description
FIELD OF THE INVENTION
The present invention relates to a fuel injector.
BACKGROUND INFORMATION
U.S. Pat. No. 4,766,405 describes a fuel injector having a valve closing body connected to a valve needle and working together with a valve seat face designed on a valve seat body to form a sealing seat. For electromagnetic operation of the fuel injector, a solenoid works together with an armature connected in a friction-locked manner to the valve needle. An additional mass is provided in the form of a cylinder around the armature and the valve needle and is connected to the armature by an elastomer layer. One disadvantage is the complicated design featuring an additional component. The large-area elastomer ring is also a disadvantage for the variation of the magnetic field and makes it difficult for the field lines to close and thus interferes with achieving high attraction forces in the opening movement of the fuel injector.
U.S. Pat. No. 4,766,405 also describes an embodiment of a fuel injector; a cylindrical mass which is movably held and secured in position by two elastomer rings is provided around the armature and the valve needle for damping and reducing rebound. When the valve needle strikes the valve seat, this second mass can move relative to the armature and the valve needle and prevent rebounding of the valve needle. One disadvantage of the embodiment described there is the additional complexity and space required. The armature itself is not isolated and its momentum thus increases the tendency of the valve needle to rebound.
U.S. Pat. No. 5,299,776 describes a fuel injector having a valve needle and an armature which is movably guided on the valve needle and whose movement is limited by a first stop in the stroke direction of the valve needle and by a second stop against the stroke direction. Within certain limits, the axial movement play of the armature defined by the two stops results in isolation of the inert mass of the valve needle from the inert mass of the armature. This counteracts within certain limits the rebound of the valve needle from the valve seat face in closing of the fuel injector. However, since the axial position of the armature with respect to the valve needle is completely undefined due to the free mobility of the armature with respect to the valve needle, rebound pulses are prevented only to a limited extent. In particular, the design of the fuel injector known from U.S. Pat. No. 5,299,776 does not prevent the armature from striking the stop facing the valve closing body in the closing movement of the fuel injector and transmitting its momentum abruptly to the valve needle. This abrupt transfer of momentum can cause additional rebound pulses of the valve closing body.
It is also known from practice that the armature guided on the valve needle can be movably secured in its position by an elastomer ring. To do so, the armature is held between two stops, with an elastomer ring located between the armature and the bottom stop. However, then the problem arises that a bore through the armature is necessary to supply fuel to the valve seat face. The bore through the armature is provided close to the valve needle, and the valve seat side end of the bore is partially covered by the elastomer ring. This results in irregular pressure on the elastomer ring and finally the bore edges result in the destruction of the elastomer ring due to edge pressure. Furthermore, the vibrations are induced in the unsupported elastomer ring, which also contributes to destruction by the bore edges. This occurs especially at low temperatures, when the elastomer enters a rigid vitreous state.
SUMMARY OF THE INVENTION
The fuel injector according to the present invention has the advantage over the related art that the elastomer ring is supported axially over its full surface. Thus, there cannot be any edge pressure on the elastomer ring. This improves the long-term stability of the elastomer ring.
This is achieved in that the fuel injector has a flat supporting ring between the elastomer ring and the armature, supporting the elastomer ring axially over its entire surface and thus also in the area of the fuel channel.
This is achieved in that the longitudinal axis of the fuel channel is inclined to the longitudinal axis of the armnature so that the fuel channel opens radially outside the elastomer ring. In this way, the elastomer ring is also supported over its entire surface on an end face of the armature. In this embodiment, no vibration is induced in the elastomer ring by fuel flowing past it.
The supporting ring may advantageously have an integrally molded shoulder. Therefore, the elastomer ring is also supported radially and is protected from vibration induced by the fuel flowing past it. Accordingly, the end face of the armature may have a projection which provides radial protection.
A conventional inexpensive O ring may be used to advantage as the elastomer ring.
The elastomer ring may be made of an elastomer having a high internal damping and a great low-temperature elasticity.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
shows an axial section through a generic fuel injector.
FIG. 2
shows a detail of a first embodiment of a fuel injector according to the present invention.
FIG. 3
shows a detail of a second embodiment of a fuel injector according to the present invention in a partially cutaway diagram.
FIG. 4
shows a detail IV from
FIG. 2
on an enlarged scale.
FIG. 5
shows a detail V from
FIG. 2
on an enlarged scale in a modified form.
FIG. 6
shows a detail VI from
FIG. 3
on an enlarged scale.
DETAILED DESCRIPTION
FIG. 1
shows a detail of a generic fuel injector
1
in a sectional diagram to better explain the present invention. Fuel injector
1
injects fuel into an internal combustion engine having fuel mixture compression and spark ignition. The embodiment illustrated here is a high pressure fuel injector opening inward for direct injection of fuel into the combustion chamber of the internal combustion engine.
Fuel injector
1
has a valve closing body
3
which is connected in one piece to a valve needle
2
in this embodiment and works together with a valve seat face designed on a valve seat body
4
to form a sealing seat. Valve seat body
4
is connected to a tubular valve seat carrier
5
which can be inserted into a receiving bore of a cylinder head of the internal combustion engine and is sealed with respect to the receiving bore by a gasket
6
. On its inlet end
7
, valve seat carrier
5
is inserted into a longitudinal bore
8
of a housing body
9
and is sealed with respect to the housing body
9
by a sealing ring
10
. Inlet end
7
of valve seat carrier
5
is under pre-tension by a threaded ring
11
, with a lift adjusting disk
14
clamped between a step
12
of housing body
9
and an end face
13
of inlet end
7
of valve seat carrier
5
.
A solenoid
15
wound onto a coil frame
16
is used for electromagnetic actuation of fuel injector
1
. When solenoid
15
is electrically energized, an armature
17
is pulled upward until its end face
19
on the inlet end is in contact with a step
18
of housing body
9
. The gap width between the upstream end face
19
of armature
17
and step
18
of housing body
9
determines the valve lift of fuel injector
1
. In its stroke movement, armature
17
entrains valve needle
2
which is connected to first stop body
20
and valve closing body
3
which is connected to valve needle
2
because of the contact of its upstream end face
19
with a first stop
21
provided on a first stop body
20
. Valve needle
2
is welded to first stop body
20
by a weld
22
. Valve needle
2
moves against a restoring spring
23
which is secured between an adjusting sleeve
24
and first stop body
20
.
Fuel flows through an axial bore
30
of housing body
9
and at least one fuel channel
31
, which is provided in armature
17
and is designed here as an axial bore, as well as through axial bores
33
provided in a guide disk
32
, into an axial bore
34
of valve seat carrier
5
and from there to the sealing seat (not shown) of fuel injector
1
.
Armature
17
is movable between first stop
21
of first stop body
20
and a second stop
26
designed on a second stop body
25
, with armature
17
in this embodiment being held in contact with first stop
21
by a bearing spring
27
in the resting position, so that a gap is formed between armature
17
and second stop
26
, thus permitting a certain movement play of armature
17
. Second stop body
25
is secured on valve needle
2
by a weld
28
.
Due to the movement play of armature
17
between stops
21
and
26
, isolation between the inert masses of armature
17
and valve needle
2
with valve closing body
3
is achieved. Therefore, in the closing movement of fuel injector
1
, only the inert mass of valve closing body
3
and valve needle
2
strikes against the valve seat face, in which case armature
17
is not decelerated abruptly when valve closing body
3
strikes the valve seat face, but instead it moves further in the direction of second stop
26
. The isolation of armature
17
from valve needle
2
improves the dynamics of fuel injector
1
. However, end face
29
of armature
17
on the spray end striking second stop
26
does not cause any valve rebound. This is achieved through an elastomer ring
35
shown in
FIG. 2
between second stop body
25
and armature
17
. Bearing spring
27
may optionally also be eliminated because of the damping by elastomer ring
35
.
FIG. 2
shows a detail of armature
17
with valve needle
2
of a fuel injector according to the present invention; elements that have already been described are shown with the same reference numbers to facilitate a correlation.
The drawing shows armature
17
of fuel injector
1
according to the present invention having fuel channel
31
, valve needle
2
, second stop body
25
welded onto valve needle
2
by weld
28
and second stop
26
, as well as end face
29
opposite second stop
26
. Valve needle
2
is welded to first stop body
20
by weld
22
.
FIG. 4
shows an embodiment according to the present invention as illustrated in detail IV from
FIG. 2
on an enlarged scale. Between end face
19
of armature
17
and second stop
26
there is an elastomer ring
35
, a flat supporting ring
36
between elastomer ring
35
and armature
17
supporting elastomer ring
35
over its entire area, i.e., in particular also in the area of fuel channel
31
, and thus preventing edge pressure at the edge of fuel channel
31
.
FIG. 5
shows an alternative embodiment according to the present invention as illustrated in detail V from
FIG. 2
on an enlarged scale. Between end face
19
of armature
17
and second stop
26
there is an elastomer ring
35
, designed as an O ring
37
in this embodiment. This O ring
37
is supported by flat supporting ring
36
over its entire area, i.e., also in the area of fuel channel
31
in particular, flat supporting ring
36
also supporting O ring
37
radially by an integrally molded, axially angled shoulder
39
. Thus a commercially available component such as O ring
37
can be inexpensively used. Inducement of vibration in O ring
37
by fuel passing by it is prevented by the larger coverage of O ring
37
, which also extends laterally. This counteracts destruction of elastomer ring
35
due to the edge pressure on fuel channel
31
and due to inducement of vibration.
In particular due to the radial support of O ring
37
, use of an elastomer with a greater internal damping is possible. High damping by an elastomer is usually also associated with a low elasticity modulus. Since O ring
37
is protected against the forces mentioned above which shorten the lifetime of an O ring
37
, such an elastomer may be used for O ring
37
without having a negative effect on the service life of O ring
37
.
A low elasticity modulus of an elastomer at low temperatures usually results in an even greater sensitivity to edge pressure and inducement of vibration at the operating temperature. Therefore, in the embodiment described here as an example, it is also possible to achieve a great low-temperature elasticity of O ring
37
and thus favorable operating performance of fuel injector
1
at low temperatures, e.g., after a cold start of the engine.
FIG. 3
shows an enlarged detail of armature
17
and valve needle
2
of a fuel injector
1
according to another embodiment of the present invention.
FIG. 3
shows armature
17
of fuel injector
1
according to the present invention, valve needle
2
, second stop body
25
welded by weld
28
onto valve needle
2
and having a second stop
26
, and end face
29
of armature
17
opposite second stop
26
. Valve needle
2
is welded by weld
22
to first stop body
20
. The at least one fuel channel
31
opens radially outside of elastomer ring
35
because it is inclined with respect to the axis of valve needle
2
.
Elastomer ring
35
which is designed as O ring
37
is shown in
FIG. 6
with its area facing the environment according to detail VI from
FIG. 3
in an enlarged view. In the embodiment illustrated here, fuel channel
31
opens into a tangential groove
36
which accommodates bearing spring
27
. This embodiment is especially advantageous because there is no inducement of vibration of O ring
37
by fuel flowing past it, and no enlargement of the diameter of armature
17
is necessary due to the inclination of fuel channel
31
to the axis of valve needle
2
.
In the embodiment illustrated in
FIG. 6
, end face
29
of armature
17
has a projection
40
. Due to the fact that O ring
37
is also covered laterally, it is possible to use an elastomer having a high internal damping and therefore a relatively low elastic modulus without any negative effect on its service life. The fact that O ring
37
is also supported radially prevents it from swelling forward and thus prevents the destruction of O ring
37
by compressive forces.
It is thus also possible to achieve a great low-temperature elasticity of O ring
37
without causing a shortened service life at the operating temperature of fuel injector
1
.
Claims
- 1. A fuel injector, comprising:a valve seat face; a valve needle working together with the valve seat face to form a sealing seat; an elastomer ring made of an elastomer; an armature including at least one fuel channel and acting on the valve needle, the armature being movably guided on the valve needle and being damped by the elastomer ring; and a supporting ring arranged between the elastomer ring and the armature, the supporting ring axially supporting the elastomer ring in an outlet end area of the at least one fuel channel.
- 2. The fuel injector according to claim 1, wherein:the fuel injector is for a fuel injection system of an internal combustion engine.
- 3. The fuel injector according to claim 1, wherein:the supporting ring includes a circumferential shoulder that also supports the elastomer ring radially.
- 4. The fuel injector according to claim 1, wherein:the elastomer ring is an O ring.
- 5. The fuel injector according to claim 1, wherein:the elastomer ring includes an elastomer having a high degree of internal damping and a high low-temperature elasticity.
Priority Claims (1)
Number |
Date |
Country |
Kind |
199 50 761 |
Oct 1999 |
DE |
|
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/DE00/03700 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO01/29402 |
4/26/2001 |
WO |
A |
US Referenced Citations (9)
Foreign Referenced Citations (4)
Number |
Date |
Country |
33 32 858 |
Mar 1985 |
DE |
198 16 315 |
Oct 1999 |
DE |
198 49 210 |
Apr 2000 |
DE |
0 404 336 |
Dec 1990 |
EP |