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Valve needle, metering device, and method of calibrating a metering device
EP1482167A1
European Patent Office
- Other languages
German French - Inventor
Angelo D'arrigo - Current Assignee
- Continental Automotive Italy SpA
Worldwide applications
Application EP03012437A events
2003-05-30
2003-05-30
2004-05-27
2004-12-01
2010-01-06
Application granted
2010-01-06
2023-05-30
Anticipated expiration
Status
Expired - Lifetime
Description
translated from
The present invention relates to a valve needle for a high-pressure
fuel injector, in which axial movement of the valve
needle in a valve cartridge controls opening and closing of a
metering opening of the injector for dosing a fluid, comprising
a valve needle body section that is formed for providing
a fluid passage from an upstream portion of the valve needle
to a downstream portion of the valve needle.
The present invention further relates to a combination of a
valve needle and a calibration means.
The present invention still further relates to a metering device
for dosing pressurized fluids, particularly an injection
valve for a fuel injection system in an internal combustion
engine.
The present invention further relates to a method of calibrating
and metering device.
Prior art valve needles for use in high-pressure direct injection
gasoline engines provide a fluid passage between the
valve needle and the valve cartridge, as can be seen for example
in EP 1 046 809 A2. In order to ensure a proper operation
of the injector, it is necessary to guide the valve needle
during its axial movement inside the cartridge. According
to prior art, this is achieved by defining guide elements
surrounding the valve needle body and providing a close sliding
fit of the valve needle in the cartridge.
Due to the guiding elements the free flow path of the injector
is reduced and the problem of spray asymmetries is a general
issue. Further, since the valve needle is only guided by
the guide elements which provide a limited sliding area that
can contact the cartridge, insufficient guiding can probably
lead to a deteriorating of the performance of the injection
valve.
Another aspect related to high-pressure direct injection
valves concerns calibration of these valves. According to
prior art, the injector calibration operation is usually performed
by adjusting the position of a thermal compensator or
by changing a preload of the valve spring. These calibration
techniques are quite cumbersome, in particular, since a disassembling
and re-assembling of the injection valve might become
necessary.
It is an object of the present invention to provide a valve
needle, equipment associated therewith and a method of calibrating
a metering device so that the problems related to the
guiding of the valve needle and the calibrating of the valve
needle are reduced or overcome.
The above object is achieved by subject matter of the independent
claims.
Advantageous embodiments of the invention are disclosed in
the dependent claims.
The present invention improves the valve needle according to
prior art in that at least a part of the valve needle body
section is hollow so that a fluid passage through the valve
needle is provided, the valve needle body section provides at
least one fluid entrance opening in the upstream portion of
the valve needle for fluid entering the fluid passage through
the valve needle and at least one fluid exit opening in the
downstream portion of the valve needle for fluid leaving the
fluid passage through the valve needle, and an axially extending
opening in the downstream portion of the valve needle
into which a calibration means can be inserted, the calibration
means sealing the axially extending opening and influencing
the fluid passage through the valve needle in dependence
of an insertion depth of the calibration means. Since
the fluid to be dosed can be transported through the hollow
valve needle body section, there are no more restrictions
with respect to the guiding of the valve needle by providing
a close sliding fit to the cartridge. Furthermore, since the
calibration means are inserted into an axially extending
opening that is accessible in a completely assembled state of
the injector, a convenient calibration process can be performed.
Particularly, it is advantageous that the calibration means
comprises a calibration pin with sealing means for sealing
the axially extending opening. The pin can be inserted in
different depths into the axially extending opening, so that
the influence on the flow passage can be adjusted. In order
to seal the axially extending opening during the calibration
process so that no fluid can leave the hollow valve needle
body section through the axially extending opening, a sealing
means is provided. The sealing means can also contribute to
the sealing of the axially extending opening after calibration,
i. e. in the completely assembled state of the injector.
In another preferred embodiment, the calibration means comprises
a calibration screw with sealing means for sealing the
axially extending opening. By using a screw, the calibration
process can be performed in a very convenient and precise
way, since the insertion depth can be varied precisely by
turning the screw.
According to an advantageous embodiment of the valve needle
according to the present invention, the sealing means comprises
an o-ring sitting on the calibration means. An o-ring
is a commercially available component which ensures sufficient
sealing, in particular during the calibration process.
In a further preferred embodiment, the calibration means can
be welded to the valve needle. Due to this welding, a precise
insertion depth of the calibration means into the axially extending
hole is conserved. Further, the welding can seal the
axially extending opening hermetically.
In the valve needle according to the present invention, it is
preferred that the calibration means influences a free flow
path through the at least one fluid exit opening in the downstream
portion of the valve needle. Thus, the flow passage
through the valve needle is only influenced in the exit region,
which is sufficient in order to calibrate the amount of
fluid leaving through the at least one fluid exit opening.
Moreover, in a preferred embodiment of the valve needle according
to the present invention, the valve needle comprises
at least one cylindrical section as a valve needle guide inside
the cartridge. Prior art valve needles are provided with
guiding elements that build only part of the outer surface of
the guiding length of the valve needle, since the rest of the
outer surface has to be in a certain distance to the cartridge
in order to provide a flow passage. According to the
present invention, it is possible to realize the guiding by a
close sliding fit between a cylindrical section and the cartridge.
This improves the guiding, and the valve needle can
be shorter than according to prior art.
According to an advantageous embodiment, a further valve needle
body section is provided that is solid and mounted to an
upstream end of the hollow valve needle body section. Thus,
the part of the valve needle that is not needed for fluid
passage purposes is realized in a solid manner as according
to prior art.
Furthermore, it is advantageous that the at least one fluid
entrance opening and/or the at least one fluid exit opening
comprise one or more holes and/or slots. Such holes and slots
are easy to manufacture, and the fluid path through an axially
extending slot in the wall of the hollow needle can be
ideally influenced by a longitudinal calibration means, e. g.
a pin or a screw.
The present invention is further realized by a combination of
a valve needle according to the present invention and a calibration
means that can be inserted into an axially extending
opening in the downstream portion of the valve needle, the
calibration means sealing the axially extending opening and
influencing the fluid passage through the valve needle in dependence
of an insertion depth of the calibration means. Such
a combination of a valve needle and calibration means exhibits
the same advantages and particularities as stated above
in connection with the valve needle according to the present
invention. This also applies to the preferred embodiments of
the combination as stated below.
In particular, the combination is favorable in that the calibration
means comprises a calibration pin with sealing means
for sealing the axially extending opening.
Furthermore, the combination is particularly advantageous in
that the calibration means comprises a calibration screw with
sealing means for sealing the axially extending opening.
Further, in an advantageous combination of a valve needle and
a calibration means, the sealing means comprises an o-ring
sitting on the calibration means.
Further, according to a preferred embodiment of the combination
of a valve needle and a calibration means, the calibration
means can be welded to the valve needle.
Moreover, the combination of the valve needle and the calibration
means is particularly advantageous in that the calibration
means influences a free flow path through the at
least one fluid exit opening in the downstream portion of the
valve needle.
Further, the present invention is realized by a metering device
for dosing pressurized fluids, particularly an injection
valve for a fuel injection system in an internal combustion
engine, comprising a valve cartridge, and the combination of
a valve needle and a calibration means according to the present
invention. Thus, a metering device is provided that is
advantageous due to the improvements and particularities of
the valve needle according to the present invention and the
combination of a valve needle and a calibration means according
to the present invention.
Another aspect of the present invention is a method of calibrating
a metering device according to the present invention,
the method comprising the steps of inserting the calibration
means into the axially extending opening in the downstream
portion of the valve needle, observing the amount of fluid
that is ejected by the injection valve, when the metering
opening is opened, adjusting the insertion depth of the calibration
means until a desired amount of fluid is ejected,
when the metering opening is opened, and fastening the calibration
means to the valve needle. Due to this calibration
method the injector can be completely and finally mounted before
calibration. Only the calibration means has to be inserted
and no further changes to the injector set up are necessary
in order to ensure a correct calibration.
It is particularly advantageous that fastening the calibration
means to the valve needle comprises welding. Thereby a
hermetically sealing of the axially extending opening in the
valve needle is achieved.
Thus, the present invention provides a solution by which a
new guiding concept of the valve needle inside the cartridge
is realized and that allows a very precise and convenient
calibration process. The tubular valve needle is less expensive
than valve needles according to prior art, and the valve
needle can be shorter than before. The injector can be
flushed through the axially extending opening so that the
seat zone of the valve needle has not to be used for flushing.
The hollow valve needle body section provides the possibility
to insert a screen filter inside the needle and/or to
insert an anti-bounce device inside the needle. As an additional
effect, the fluid path inside the needle provides a
cooling, so that the thermal expansion of the needle is reduced.
The invention, both its construction and its method of operation
together with additional objects and advantages thereof,
will best be understood from the following description of
specific embodiments when read in connection with the accompanying
drawings, wherein
- Figure 1
- is a cross sectional view of a metering device according to the present invention;
- Figure 2
- is an exploded side elevational view of a valve needle according to the present invention;
- Figure 3
- is a cross sectional view of a valve needle according to the present invention and of a calibration means used in a combination of a valve needle and a calibration means according to the present invention;
- Figure 4
- is a cross sectional view of a combination of a valve needle and a calibration means according to the present invention; and
- Figure 5
- is a flow chart illustrating a preferred embodiment of a calibration method according to the present invention.
In the following description of preferred embodiments of the
present invention, the same reference numbers refer to similar
or comparable components.
Figure 1 is a cross sectional view of a metering device according
to the present invention. The injection valve 12 comprises
of a valve cartridge 14 that is mounted to a valve
body 40. Inside the cartridge 14 and the valve body 40, a
valve needle 10 is arranged. The valve needle 10 ends with a
plunger 42 for closing and opening a metering opening 16. A
valve needle body section 18 is hollow so that a fluid passage
24 is provided inside the valve needle 10. Fluid entrance
openings 26 allow fluid to enter into the fluid passage
24, and fluid exit openings 28 allow fluid to leave the
fluid passage 24. The valve needle 10 comprises of an axially
extending opening 30 (cf. Figure 3) that is located at the
plunger end of the valve needle 10. Into this axially extending
opening, a calibration pin 32 is inserted so as to influence
the free fluid path through the fluid exit openings 28.
The valve needle 10 comprises a cylindrical section 36 providing
a close sliding fit of the valve needle 10 in the cartridge
14. It is possible to provide this cylindrical section
36, because the fluid passage 24 is inside in the valve needle
10 and not between the valve needle 10 and the cartridge
14. The valve needle 10 further comprises a solid valve needle
body section 38 that is mounted to an upstream portion of
the hollow valve needle body section 18.
Figure 2 is an exploded side elevational view of a valve needle
according to the present invention and Figure 3 is a
cross sectional view of a valve needle according to the present
invention and of a calibration means used in a combination
of a valve needle and a calibration means according to
the present invention. Figure 2 illustrates how the fluid entrance
openings 26 and the fluid exit openings 28 are provided.
The fluid entrance openings 26 are provided as elongated
slots in an upstream portion 20 of the valve needle 10.
The fluid exit openings 28 are provided as elongated slots in
a downstream portion 22 of the valve needle 10. The calibration
pin 32 comprises of several sections with different diameters,
thereby providing the possibility of pulling an o-ring
34 over the calibration pin 32. This o-ring 34 seals the
fluid passage 24 at least during the calibration procedure.
Figure 4 is a cross sectional view of a combination of a
valve needle and a calibration means according to the present
invention. The valve needle 10 is shown in a similar manner
as in Figure 1 without the further injector components.
Figure 5 is a flow chart illustrating a preferred embodiment
of a calibration method according to the present invention.
After assembling the injector valve with the hollow valve
needle 10 (S01) the calibration pin 32 is inserted into the
axially extending opening 30 of the valve needle 10 (S02).
The valve needle 10 is operated and the amount of fluid that
is ejected through the metering opening 16 is observed (S03) .
On the basis of this amount of fluid observed, the insertion
depth of the calibration pin 32 is adjusted until a desired
amount of fluid is ejected (S04) . Thereafter, the calibration
pin 32 is welded to the valve needle (S05) .
The present invention can be summarized as follows: A hollow
valve needle 10 that provides a fluid passage 24 is provided
for an injection valve 12. The valve needle 10 comprises
fluid entrance openings 26 and fluid exit openings 28. Between
these openings 26, 28 a cylindrical section 36 is located
for providing a close sliding fit of the valve needle
in the valve cartridge 14. At the plunger end of the valve
needle, a calibration means 32, e. g. a pin or a screw, can
be inserted, and the free fluid path through the fluid exit
openings 28 can be influenced in dependence of the insertion
depth of the calibration means 32. Thereby, a calibration of
the injection valve 12 is possible without further manipulation
of the injection valve 12.
The features disclosed in the foregoing description, in the
drawings, and in the claims may alone as well as in any possible
combination be important for the realization of the invention.
Claims (18)
Hide Dependent
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Claims (18)
Hide Dependent
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- A valve needle (10) for a high-pressure fuel injector (12), in which axial movement of the valve needle (10) in a valve cartridge (14) controls opening and closing of a metering opening (16) of the injector (12) for dosing a fluid, comprising a valve needle body section (18) that is formed for providing a fluid passage from an upstream portion (20) of the valve needle (10) to a downstream portion (22) of the valve needle (10)
characterized in thatat least a part of the valve needle body section (18) is hollow so that a fluid passage (24) through the valve needle (10) is provided,the valve needle body section (18) provides at least one fluid entrance opening (26) in the upstream portion (20) of the valve needle (10) for fluid entering the fluid passage (26) through the valve needle (10) and at least one fluid exit opening (28) in the downstream portion (22) of the valve needle (10) for fluid leaving the fluid passage (24) through the valve needle (10), andan axially extending opening (30) in the downstream portion (22) of the valve needle (10) into which a calibration means (32) can be inserted, the calibration means (32) sealing the axially extending opening (30) and influencing the fluid passage through the valve needle (10) in dependence of an insertion depth of the calibration means (32). - The valve needle according to claim 1,
characterized in that
the calibration means (32) comprises a calibration pin with sealing means (34) for sealing the axially extending opening (30). - The valve needle according to claim 1,
characterized in that
the calibration means comprises a calibration screw with sealing means for sealing the axially extending opening. - The valve needle according to claim 2 or 3,
characterized in that
the sealing means (34) comprises an o-ring sitting on the calibration means (32). - The valve needle according to any of the preceding claims,
characterized in that
the calibration means (32) can be welded to the valve needle (10) . - The valve needle according to any of the preceding claims,
characterized in that
the calibration means (32) influences a free flow path through the at least one fluid exit opening (28) in the downstream portion (22) of the valve needle (10). - The valve needle according to any of the preceding claims,
characterized in that
the valve needle comprises at least one cylindrical section (36) as a valve needle guide inside the cartridge (14). - The valve needle according to any of the preceding claims,
characterized in that
a further valve needle body section (38) is provided that is solid and mounted to an upstream end of the hollow valve needle body section (18). - The valve needle according to any of the preceding claims,
characterized in that
the at least one fluid entrance opening (26) and/or the at least one fluid exit opening (28) comprise one or more holes and/or slots. - A combination ofa valve needle (10) according to any of the preceding claims anda calibration means (32) that can be inserted into an axially extending opening (28) in the downstream portion (22) of the valve needle (10), the calibration means (32) sealing the axially extending opening (28) and influencing the fluid passage through the valve needle (10) in dependence of an insertion depth of the calibration means (32).
- The combination according to claim 10,
characterized in that
the calibration means (32) comprises a calibration pin with sealing means (34) for sealing the axially extending opening (30) . - The combination according to claim 10,
characterized in that
the calibration means comprises a calibration screw with sealing means for sealing the axially extending opening. - The combination according to claim 11 or 12,
characterized in that
the sealing means (34) comprises an o-ring sitting on the calibration means (32). - The combination according to any of claims 10 to 13,
characterized in that
the calibration means (32) can be welded to the valve needle (10). - The combination according to any of claims 10 to 14, characterized in that
the calibration means influences a free flow path through the at least one fluid exit opening (28) in the downstream portion (22) of the valve needle (10). - A metering device for dosing pressurized fluids, particularly an injection valve (12) for a fuel injection system in an internal combustion engine, comprisinga valve cartridge (14), andthe combination of a valve needle (10) and a calibration means (32) according to any of claims 10 to 15.
- A method of calibrating a metering device according to claim 16, the method comprising the steps ofinserting the calibration means (32) into the axially extending opening (30) in the downstream portion (22) of the valve needle (10),observing the amount of fluid that is ejected by the injection valve (12), when the metering opening (16) is opened,adjusting the insertion depth of the calibration means until a desired amount of fluid is ejected, when the metering opening (16) is opened, andfastening the calibration means (32) to the valve needle (10) .
- The method according to claim 17
characterized in that
fastening the calibration means to the valve needle (10) comprises welding.