Information
-
Patent Grant
-
6435430
-
Patent Number
6,435,430
-
Date Filed
Friday, April 6, 200123 years ago
-
Date Issued
Tuesday, August 20, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Morris; Lesley D.
- Hwu; Davis
Agents
-
CPC
-
US Classifications
Field of Search
US
- 239 1021
- 239 1022
- 239 5851
- 239 5853
- 239 5854
- 239 5855
- 239 900
- 239 101
- 239 5332
- 239 5339
- 239 53311
- 251 12906
- 251 12921
- 251 12922
- 251 3351
- 251 3353
-
International Classifications
- B05M130
- B05M108
- F02M5100
- F02M6120
-
Abstract
A fuel injector for a fuel injection system of an internal combustion engine is described. The fuel injector, has a fuel inlet connection piece for supplying fuel, a piezoelectric or magnetostrictive actuator, which is sealed off from the fuel by a seal, and a valve closing body actuatable by the actuator via a valve valve closing body working together with a valve seat surface to form a seal seat. The seal includes an inlet-side gasket, which is arranged between the fuel inlet connection piece and the actuator, and an actuator jacket that is elastically deformable in a longitudinal direction and is connected to the inlet-side gasket.
Description
FIELD OF THE INVENTION
The present invention relates to a fuel injector.
BACKGROUND INFORMATION
German Patent No. 195 34 445 describes a fuel injector. The fuel injector described in this document has a valve body in which a valve needle is coaxially guided. The valve body has a connection piece through which fuel is supplied to the fuel injector. The valve needle is provided with a central borehole. On the injection side the valve needle forms a seal seat with the valve body. The fuel is supplied to the seal seat via the central borehole of the valve needle. On the outside the valve needle is sealed with respect to the surrounding valve body. A piezoelectric actuator acts upon the valve needle via a pressure shoulder. The pressure shoulder is permanently connected to the valve needle and is tightly guided on the valve body on the inlet side. This protects the actuator against the effect of the fuel pressure. The conventional fuel injector has the following disadvantages:
Because the valve needle is permanently connected to the pressure shoulder, the valve needle on the injection side and the pressure shoulder on the inlet side are sealingly and movably guided in the valve body, therefore manufacturing is relatively complicated and the valve needle of the fuel injector is subject to bending and stresses and the relative positions of the two sliding surfaces are subject to modification.
Because the pressure shoulder, i.e., the valve needle is movably guided with respect to the valve body, the sealing surface is wetted with fuel and, due to the high fuel pressure, the fuel may flow toward the actuator. Thus the actuator is only protected against the effect of the fuel pressure but not against the effect of the fuel. Due to the seal between the pressure shoulder, i.e., the valve needle and valve body, friction losses occur when the fuel injector is actuated. This negatively affects the shapability of the fuel jet further, the switching times of the injector are increased, the actuator power is less efficiently utilized, and fuel injector wear is increased. In particular, the seal at the sealing surfaces between the pressure shoulder, i.e., the valve needle and the valve body deteriorates during operation.
Since the central borehole in the valve needle is a part of a fuel line extending from the fuel inlet connection piece to the seal seat, the manufacture of the valve needle is complicated and the fuel injector is subject to dirt deposits, in particular on its seal seat-side end.
SUMMARY
The fuel injector according to the present invention has the advantage over conventional fuel injectors of a simple, more cost-effective, low-wear, friction-free and considerably more compact design. Furthermore, the seal is independent of the design of the valve needle and can therefore be integrated into a plurality of fuel injectors.
In addition, the actuator sealed with respect to the fuel in this manner can be integrated using the seal, without major structural changes, both into an inward-opening and an outward-opening fuel injector. In addition, the actuator is protected by the seal both against the effect of the fuel and the effect of the fuel pressure.
The actuator jackets advantageously have an undulated or pleated design. This allows a large actuator stroke in the actuator housing in a compact construction. The actuator is advantageously prestressed by the actuator jacket. Additional components such as, for example, compression springs are not needed. A heat-conducting material, for example a heat-conducting paste, is advantageously provided between the actuator jacket and the actuator. This allows the energy generated by the actuation of the actuator and dissipated in the actuator to be conducted away from the actuator on the heat-conducting material and to the actuator housing. The heat load on the actuator is thus reduced and the service life of the fuel injector is extended.
The seal advantageously has a tubular sleeve that traverses the cutout of the actuator and is at least partially surrounded by the actuator. Thus, the inside of the tubular sleeve is sealed with respect to the actuator and therefore can be traversed by fuel.
The seal advantageously has a seal seat-side gasket that is connected to the actuator jacket and/or to the sleeve. Thus, the actuator can act upon the devices of the fuel injector and/or be supported by them via the seal seat-side gasket. In addition, the seal seat-side gasket can be designed like the inlet-side gasket which facilitates the manufacture of the seal.
The gaskets advantageously have a pot-shaped design whereby devices of the fuel injector can be accommodated within the gaskets. In addition, the gaskets can thereby be more easily guided in a guide.
Each gasket advantageously has a cutout that is traversed by the sleeve. The sleeve is bent back on at least one gasket and widened, and is connected to the gasket at its end facing away from the respective other gasket, allowing a large actuator stroke in the actuator housing.
At least one of the gaskets advantageously has a pot-shaped design and an end zone of the gasket projects over the bent-back zone of the sleeve, protecting the bent-back zone of the sleeve.
The inlet-side gasket advantageously has at least one supply channel through which at least one electrical lead is run to the actuator, allowing the electrical lead to enter the seal in a simple manner.
The supply channel is advantageously sealed with respect to the fuel, thus integrating the seal of the electrical lead with respect to the fuel into the gasket, making an additional seal is unnecessary and resulting in a more compact design.
The sleeve is advantageously part of a fuel line extending from the fuel inlet connection piece to the seal seat. This simplifies the fuel line in particular for an end-mounted fuel connection piece. In addition, no additional fuel line is needed, resulting in fewer components.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
shows a partial axial through section of a first embodiment of a fuel injector that has an inward-opening design according to the present invention.
FIG. 2
shows a partial axial through section of a second embodiment of a fuel injector that has an outward-opening design according to the present invention.
FIG. 3
shows an axial through section of an actuator that has a seal according to the present invention.
FIG. 4
shows an axial through section of a gasket according to the present invention.
DETAILED DESCRIPTION
FIG. 1
shows in a partial axial section a fuel injector
1
according to the present invention. Fuel injector
1
is used for direct injection of fuel, for example gasoline, into a combustion chamber of a compressed mixture, externally ignited internal combustion engine as a “direct gasoline injector.” Fuel injector
1
according to the present invention is also suitable for other applications.
Fuel injector
1
is designed as an inward-opening fuel injector
1
. Fuel injector
1
has a valve housing
3
and a fuel inlet connection piece
4
, representing the fuel inlet, which together form the housing of fuel injector
1
. A valve closing body
6
, which in the embodiment illustrated is designed in one piece with a valve needle and which can be actuated by valve needle
5
, is located in valve housing
3
. Valve closing body
6
has a truncated cone shaped tapering in the direction of injection. Valve closing body
6
works together with a valve seat surface
8
formed on a valve seat body
7
to form a seal seat. Valve needle
5
is guided in its axial movement by valve needle guides
9
,
10
, which are attached to valve housing
3
. In order to allow fuel to flow through, valve needle guides
9
,
10
have slot-shaped cutouts
11
,
12
.
An actuator
13
, which has a piezoelectric or magnetostrictive design, is used to actuate fuel injector
1
. Actuator
13
is actuated by an electrical control signal, supplied to actuator
13
by an electrical lead, which is not shown in this embodiment for the sake of simplicity. When actuator
13
is actuated, it expands and acts upon baseplate
15
, to which valve needle
5
is attached, via an inlet-side gasket
14
. Actuator
13
is supported by valve housing
3
via a seal seat-side gasket
16
. Thus valve needle
5
is moved in the axial direction onto fuel inlet connection piece
4
, whereby valve closing body
6
is lifted from valve seat surface
8
of valve seat body
7
, exposing the seal seat. Due to the gap formed between valve closing body
6
and valve seat body
7
, fuel exits from a fuel chamber
17
of fuel injector
1
into the combustion chamber of the internal combustion engine. Valve needle
5
is reset in this embodiment via a compression spring
18
, supported on one side by baseplate
15
and on the other side by fuel inlet connection piece
4
.
Valve housing
3
, fuel inlet connection piece
4
, baseplate
15
, inlet-side gasket
14
and seal seat-side gasket
16
are attached to one another via welds
19
a
through
19
f.
However, they can also be attached in some other fashion.
An actuator jacket
20
and a sleeve
21
are attached to inlet-side gasket
14
and seal seat-side gasket
16
. Actuator jacket
20
is permanently connected to inlet-side gasket
14
by a peripheral weld
22
and to seal seat-side gasket
16
by a peripheral weld
23
. The joint may, however, also be of a different kind, including a detachable joint. Inlet-side gasket
14
and seal seat-side gasket
16
have internal cutouts
24
,
25
, traversed by sleeve
21
. Sleeve
21
is widened and bent back on inlet-side gasket
14
in a bent-back zone
39
, and is connected to one end face
37
of inlet-side gasket
14
at a peripheral weld
26
and to seal seat-side gasket
16
at a peripheral weld
27
. Inlet-side gasket
14
has an end zone
38
at which inlet-side gasket
14
is connected to baseplate
15
. Edge zone
38
of inlet-side gasket
14
projects over a bent-back zone
39
of sleeve
21
. Sleeve
21
widened and bent back on inlet-side gasket
14
can be moved in the direction of fuel inlet connection piece
4
due to the pot-shaped design of inlet-side gasket
14
as actuator
13
expands, the seal of actuator
13
remaining with respect to the fuel due to seals
14
,
16
,
20
,
21
. For the same reason, actuator jacket
20
has an undulated or pleated design. Actuator
13
can be prestressed by actuator jacket
20
so that compression spring
18
is no longer necessary.
Fuel is supplied into a fuel chamber
17
by fuel inlet connection piece
4
, through boreholes
28
a,
28
b
in baseplate
15
, and through an internal longitudinal opening
31
in sleeve
21
, through which valve needle
5
also extends. Fuel can also be conducted, as an alternative, through internal space
29
of valve housing
3
, in which case appropriate through openings are provided in seal seat-side gasket
16
.
A heat-conducting material, for example a heat-conducting paste, can be introduced in a gap
30
between actuator jacket
20
and actuator
13
, whereby the heat of actuator
13
is conducted to valve housing
3
via heat-conducting paste in gap
30
and via seal seat-side gasket
16
. In a similar manner, the space between actuator
13
and sleeve
21
can also be filled with a heat-conducting paste in order to transmit heat to the fuel.
FIG. 2
shows in a partial axial section of a second embodiment of fuel injector
1
according to the present invention. Elements described previously are provided with the same reference symbols, making repetition of the description unnecessary.
The second embodiment of fuel injector
1
is an outward-opening fuel injector
1
. Pot-shaped, inlet-side gasket
14
is supported by fuel inlet connection piece
4
, so that when actuator
13
is actuated, the latter expands in the direction of the seal seat and acts upon valve needle
5
via seal seat-side gasket
16
and baseplate
15
, whereby truncated cone-shaped valve closing body
6
, widening in the direction of injection and designed in one piece with valve needle
5
, is lifted from valve seat surface
8
of valve seat body
7
exposing the seal seat. Valve closing body
6
is pressed against valve seat surface
8
of valve seat body
7
via compression spring
18
supported on one side by valve housing
3
and on the other side by baseplate
15
. As described with reference to the embodiment illustrated in
FIG. 1
, the function of compression spring
18
can be assumed fully or in part by actuator jacket
20
.
The electrical leads can be run to actuator
13
via supply channels
32
and
33
in fuel inlet connection piece
4
, i.e., in gasket
14
. Supply channels
32
,
33
may also be used for de-aerating seal
14
,
16
,
20
,
21
or to remove leakage fluid from seal
14
,
16
,
20
,
21
. Fuel flows toward the seal seat via longitudinal opening
31
and boreholes
28
a,
28
b
in baseplate
15
. As in the embodiment illustrated in
FIG. 1
, a heat-conducting material, for example a heat-conducting paste, can be introduced in gap
30
between actuator jacket
20
and actuator
13
and/or between sleeve
21
and actuator
13
.
FIG. 3
shows in the sectional view a further embodiment of seal
14
,
16
,
20
of actuator
13
. Actuator jacket
20
is welded to inlet-side gasket
14
and seal seat-side gasket
16
via peripheral welds
22
and
23
, respectively. Actuator
13
is located between the two pot-shaped gaskets
14
,
16
. A supply channel
33
for accommodating an electrical lead leading to actuator
13
is provided in inlet-side gasket
14
. Supply channel
33
may, however, also be provided in seal seat-side gasket
16
. In this embodiment sleeve
21
is not used; therefore actuator
13
is designed without internal longitudinal opening
31
. Fuel is therefore supplied outside actuator jacket
20
.
FIG. 4
shows, in a sectional view, a further embodiment of inlet-side gasket
14
. In this embodiment, supply channel
33
is designed with a bend, with supply channel
33
opening at peripheral surface
35
of inlet-side gasket
14
. Inlet-side gasket
14
can be attached to the internal wall of valve housing
3
via peripheral surface
35
, for example by welding. Thus the electrical lead can be run via a terminal provided in valve housing
3
from the side of fuel injector
1
through supply channel
33
to actuator
13
. The opening of supply channel
33
at peripheral surface
35
must be sealed with respect to the fuel in order to prevent fuel from entering. A weld running around the opening between peripheral surface
35
and valve housing
3
is particularly well-suited for this purpose. Actuator jacket
20
may be attached to lower peripheral surface
36
of inlet-side gasket
14
, which has a smaller diameter than upper peripheral surface
35
. The above-described design of inlet-side gasket
14
is also suitable for seal seat-side gasket
16
without restrictions.
In order to make supply of fuel possible in the embodiment illustrated in
FIG. 4
, gasket
14
has a fuel channel
40
. As an alternative, gasket
14
can be provided with a cutout
24
as shown in FIG.
1
.
The present invention is not restricted to the embodiments described. In particular, a different design of actuator jacket
20
, sleeve
21
, bent-back zone
39
of sleeve
21
, and the two gaskets
14
,
16
is possible. Furthermore, the action of actuator
13
on valve needle
5
in
FIGS. 1 and 2
is illustrated in a simplified manner and should not limit the present invention in this respect. In particular, the present invention is characterized by the possibility of using seal
14
,
16
,
20
,
21
in a plurality of fuel injectors
1
.
Claims
- 1. A fuel injector for a fuel injection system of an internal combustion engine, the fuel injector comprising:a fuel inlet for supplying fuel; an actuator, the actuator being one of a piezoelectric actuator and a magnetorestrictive actuator; a seal for sealing off the actuator from the fuel, the seal including an inlet-side gasket and an actuator jacket connected to the inlet-side gasket, the inlet-side gasket being situated between the fuel inlet and the actuator, the actuator jacket being elastically deformable in a longitudinal direction; a valve closing body cooperating with a valve seat surface to form a seal seat; and a valve needle, the valve closing body being actuable by the actuator via the valve needle.
- 2. The fuel injector according to claim 1, wherein:the inlet-side gasket is pot-shaped.
- 3. The fuel injector according to claim 1, wherein:the actuator jacket is one of undulated and pleated.
- 4. The fuel injector according to claim 1, wherein:the actuator is prestressed by the actuator jacket.
- 5. The fuel injector according to claim 1, wherein:a heat-conducting material is arranged between the actuator jacket and the actuator.
- 6. The fuel injector according to claim 5, wherein:the heat-conducting material includes a heat-conducting paste.
- 7. The fuel injector according to claim 1, wherein:the actuator has an internal longitudinal opening.
- 8. The fuel injector according to claim 7, wherein:the seal further includes a tubular sleeve, the tubular sleeve traversing the longitudinal opening of the actuator and at least partially surrounded by the actuator.
- 9. The fuel injector according to claim 8, wherein:the seal further includes a seal seat-side gasket connected to at least one of the actuator and the tubular sleeve.
- 10. The fuel injector according to claim 9, wherein:the seal seat-side gasket is pot-shaped.
- 11. The fuel injector according to claim 9, wherein:the inlet-side gasket and the seal seat-side gasket each have a cutout traversed by the tubular sleeve, the tubular sleeve is bent back on at least the inlet-side gasket and connected to the inlet-side gasket at an end face of the inlet-side gasket facing way from the seal-seat side gasket.
- 12. The fuel injector according to claim 11, wherein:at least one of the inlet-side gasket and the seal seat-side gasket is pot shaped; and an end area of the at least one of the inlet-side gasket and the seal seat-side gasket projects over the bent-back area of the tubular sleeve.
- 13. The fuel injector according to claim 1, wherein:the actuator acts upon the valve needle via the inlet-side gasket.
- 14. The fuel injector according to claim 8, wherein:some sections of the valve needle are surrounded by the tubular sleeve.
- 15. The fuel injector according to claim 8, wherein:the tubular sleeve is part of a fuel line extending from the fuel inlet to the seal seat.
Priority Claims (1)
Number |
Date |
Country |
Kind |
199 12 666 |
Mar 1999 |
DE |
|
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/DE99/03357 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO00/57049 |
9/28/2000 |
WO |
A |
US Referenced Citations (6)
Foreign Referenced Citations (3)
Number |
Date |
Country |
195 34 445 |
Mar 1997 |
DE |
196 53 555 |
Jun 1998 |
DE |
2 094 940 |
Sep 1982 |
GB |