WO2015058930A1

WO2015058930A1 - Fuel injector

Info

Publication number: WO2015058930A1
Application number: PCT/EP2014/070874
Authority: WO
Inventors: Armin Schuelke; Verena Tritsch
Original assignee: Robert Bosch Gmbh
Priority date: 2013-10-23
Filing date: 2014-09-30
Publication date: 2015-04-30
Also published as: DE102013221484A1

Abstract

The invention relates to a fuel injector for injecting fuel into a combustion chamber of an internal combustion engine, comprising a nozzle needle (14), which is liftably guided in a high-pressure bore (12) of a nozzle body (5) for opening and closing at least one injection opening (13), and a magnetic actuator with a solenoid coil (8) for direct or indirect control of the lift movement of the nozzle needle (14), wherein the solenoid coil (8) interacts with an armature (20) and this armature interacts with an armature needle (21), wherein the armature (20) and/or the armature needle (21) is furthermore guided in a magnet body, and wherein the armature needle (21) interacts directly or indirectly with the nozzle needle (14). According to the invention, a fuel injector is provided which is compactly constructed during a simple assembly optimized for sealing. This is achieved in that the magnet body is inserted into the needle body (5) and is formed as a guide sleeve (15) for the armature needle (21).

Description

Title:

fuel injector

The invention relates to a fuel injector for injecting fuel into a combustion chamber of an internal combustion engine comprising a nozzle needle, which is guided in a high-pressure bore of a nozzle body for releasing and closing at least one injection opening in a liftable manner, and a

Magnetic actuator with a magnetic coil for direct or indirect control of the lifting movement of the nozzle needle, wherein the magnetic coil with an armature and this cooperates with a Ankernadel, further wherein the armature and / or the Ankernadel is guided in a magnetic body, and wherein the Ankernadel directly or indirectly with the nozzle needle cooperates.

State of the art

Such a fuel! Njektor is known from DE 10 2010 028 835 A1. This fuel! Njektor for injecting fuel into a combustion chamber of an internal combustion engine has a magnetic actuator for direct control of the lifting movement of a nozzle needle and a two-stage

Translation device on. In a first stage causes the

Translation device a force translation to the required

To realize nozzle needle opening force. After initial opening of the nozzle needle, the translator switches to a second stage in which path translation can be effected. The magnetic actuator and an armature and a magnetic needle and the translation device are either arranged substantially in a magnetic body which is arranged between an injector holding body and a nozzle body, or at least largely installed in the injector body. The invention is based on the object, a fuel! Specify injector, which builds compact in a simple and sealing technology optimized design.

Disclosure of the Invention Advantages of the Invention

This object is achieved in that the magnetic body is inserted into the nozzle body and formed as a guide sleeve for the anchor needle and / or the anchor. By installing the magnetic body in the nozzle body, the drive for the nozzle needle builds much more compact and it eliminates a critical high-pressure seal against the ambient pressure, in an arrangement of the magnetic body between the nozzle body and the

Injector body is present. The formation of the magnetic body as

Guide sleeve for in particular the anchor needle also contributes to a compact design of the fuel injector.

In a further development of the invention, the guide sleeve is inserted into a cylindrical recess in the nozzle body. Such a cylindrical recess, which is arranged in extension of a high-pressure bore for the nozzle needle, and has a larger diameter than the high-pressure bore, is easy and inexpensive to produce in the manufacture of the nozzle body. In this case, lower requirements are placed on the surface quality of the recess than on the surface of the high-pressure bore.

In a further embodiment of the invention, the guide sleeve is supported on the magnetic coil side to an amagnetic separator in the form of a cutting disc and nozzle needle side directly or indirectly on the nozzle body. The non-magnetic separator ensures a magnetic separation between the injector and the nozzle body and also causes by appropriate choice of material and surface finish at the joints to the injector and the nozzle body a reliable seal these components to each other and the environment. ln development of the invention is between the guide sleeve and the

Nozzle body arranged a spring, which may be formed, for example, as a plate spring. This spring presses a Abstützmantel the

Guide sleeve against the separator and thus ensures a tight fit of the guide sleeve in the recess. The spring can be directly at the

Nozzle body or, as described below, at one

Support coupler disk, wherein the coupler disk is then on the

Supported nozzle body. In a further embodiment of the invention is between the guide sleeve and the

Bottom wall of the recess arranged a coupler disc. In this case, in a preferred embodiment between the coupler plate and the guide sleeve, the spring described above is arranged, which thus ensures the tight fit of both the guide sleeve and the coupler disc. However, the spring can also be saved if the guide sleeve and / or the coupler disc has a clearance-compensating property. For example, in particular the Abstützmantel be resilient and be provided, for example, with the structure of a Bourdon tube. In a further embodiment of the invention is in the coupler disc to the

Inserted end face of the nozzle needle adjacent coupler space. This coupler space surrounds the anchoring needle, which is supported at rest on the front side of the nozzle needle. The anchoring needle has at least in the area of

Coupler space a smaller diameter than the nozzle needle in the region of its front side. If the armature needle is moved away by energizing the magnetic coil by a small amount from the end face of the nozzle needle, takes place through the volume increase in the coupler space thus caused a

Pressure reduction in the coupler space and the nozzle needle is moved from its closed position of the at least one injection opening in the release position of the at least one injection opening.

In a further development of the invention, a nozzle needle-side sleeve recess is embedded in the guide sleeve. In this sleeve recess, in turn in a further embodiment of the invention, a Ankernadelfeder is used, which in turn in another embodiment between a Sleeve recess bottom wall and a supporting disc connected to the anchoring needle is clamped. The anchor needle spring thus presses in

Hibernation of the system the anchor needle against the front of the nozzle needle. The installation of the anchor needle spring and the support disk in the

Sleeve recess also contributes to a reduction of the necessary

Space at.

In a further embodiment of the invention, a fuel channel is embedded in the armature. This fuel channel connects a fuel supply recessed into the injector body to a further fuel channel which is embedded in the guide sleeve. Preferably, the fuel is ka na I arranged in the region of the guide for the armature needle, said fuel ka na I can be divided into several sub-channels. These sub-channels can be inserted, for example, as longitudinal grooves in the guide for the anchor needle in the guide sleeve. But it is also possible to form the fuel ka na I as one or more Längsabflachungen, wherein the flats are arranged on the surface of the anchor needle. The fuel thus obtained in the sleeve recess is guided along the coupler disk and the nozzle needle to a nozzle body space located upstream of the injection opening. At the same time the fuel enters the previously described coupler space.

As a result of the above-described embodiments of the fuel injector, the armature and the anchoring needle are significantly shorter and more compact, which also represents an advantage with respect to the mass to be moved by the magnet coil. The fuel injector can thus be made shorter overall or at an unchanged length of the fuel injector, a Miniraiivolumen, which is preferably arranged in the region surrounding the nozzle needle nozzle body, can be increased. There is also no need to extend the nozzle retaining nut compared to today's injectors. On a

Nozzle needle spring can be dispensed with since the armature needle and the nozzle needle are hydraulically coupled and the armature needle spring keeps the nozzle needle closed by direct contact of the nozzle needle and the armature needle in the idle state. Further advantageous embodiments of the invention are the

See drawing description, in which an embodiment shown in the single figure is described in more detail.

Short description of the drawing

The single FIGURE shows a longitudinal section through an inventively designed fuel! njektor.

Embodiment of the invention

The schematically illustrated in Figure 1 in a longitudinal section

Fuel injector is part of a common rail injection system in particular, wherein the fuel injector fuel, such as diesel fuel, is injected into an associated combustion chamber of an internal combustion engine. It is compressed by a high pressure pump of the common rail injection system fuel up to a pressure of 3,000 and in a bar

Accumulator stored. This accumulator is connected via a high-pressure line with a connecting piece 1 to an injector 2 of the fuel injector. The injector body 2 has a connection piece 1

penetrating and opening on an opposite end face fuel supply line 3. The injector body 2 is further screwed by means of a nozzle lock nut 4 with a nozzle body 5. Here, the nozzle lock nut 4 is supported with a clamping nut neck 6 on an annular shoulder of the nozzle body 5, while the opposite end of the

Nozzle clamping nut 4 has an internal thread 7 which cooperates with an external thread of the injector body 2. In the region of the opposite injector body 2 and nozzle body 5, a magnetic coil 8 is arranged, which is formed for example as an external magnetic coil 8 and is inserted into a recessed into the injector body 2 and the nozzle body 5 outer recess. Between the injector 2 and the nozzle body 5, an amagnetic separator 9 is arranged, which also ensures a liquid-tight seal of the injector body 2 relative to the nozzle body 5 to the environment. In the nozzle body 5 is a cylindrical recess 10 and a reaching to a nozzle body tip 1 1 high-pressure bore 12 is inserted. In the nozzle body tip 1 1 at least one injection port 13 is inserted, while in the high-pressure bore 12, a nozzle needle 14 is guided in a liftable manner. The Hubbeweglichkeit is designed so that the nozzle needle 14 for

Enabling or closing the at least one injection opening 13 can be adjusted axially in the high-pressure bore 12.

In the recess 10, in particular, a magnetic body designed as a guide sleeve 15 is used, which is supported on the separating body 9 with a thin-walled supporting jacket 16. On the opposite side of the

Guide sleeve 15 cooperates with a trained as a plate spring spring 17, which in turn is supported on a coupler plate 18. The

Coupler disc 18 rests on a bottom wall 19 of the recess 10. The guide sleeve 15 and in particular the coupler disc 18 are thus accommodated in a space-saving manner in the recess 10 of the nozzle body 5.

The guide sleeve 15 has a central guide bore 30, in which a cooperating with an armature 20 Ankernadel 21 is guided. When energizing the solenoid 8, the armature 20 is moved together with the armature needle 21 by a small amount upwards. On the opposite side, the anchoring needle 21 is supported by a portion 22 which has a reduced

Diameter, on the end face 23 of the nozzle needle 14 from. In this case, the section 22 of the anchor needle 21 penetrates a hole in the

Coupler 18. In the coupler plate 18 adjacent to the end face 23 of the nozzle needle 14, a coupler space 24 is formed, which is like the entire free space of the fuel injector filled. Now, if the armature 20 and the armature needle 21 moves upward by energizing the solenoid 8, by lifting the portion 22 of the armature needle 21 from the end face 23 of the nozzle needle 14 increases the volume of the coupler space 24, so that in the coupler chamber 24, a pressure drop occurs , This pressure drop causes the nozzle needle 14 moves from its closed position of the injection port 13 in the release position of the injection port 13. In a nozzle body 25 located in the region of the nozzle body tip 1 1 fuel is then through the injection port 13 into the combustion chamber of the Internal combustion engine injected. If the energization of the solenoid 8 is released, the armature needle 21 is moved downwardly by an armature needle spring 26 and presses the nozzle needle 14 into its closed position. The

Anchor needle spring is inserted into a sleeve recess 28 in the guide sleeve 15 and is supported on this and one with the anchoring needle 21st

connected support disk 27 from. The sleeve recess 28 is by means of flattening on the anchor needle 21 in the region of the guide in the

Guide sleeve 15 formed longitudinal channels connected to a fuel channel 29 in the armature 20. The fuel channel 29 is in flow communication with the fuel supply 3, so that in this way the fuel is guided into the sleeve recess 28. From this the fuel gets through

Recesses on the coupler plate 18 and guided along the n-times flat guide of the nozzle needle 14 into the nozzle body space 25.

In summary, therefore, a fuel injector is created, which is very compact builds in a sealing-optimized design.

Claims

claims

1 . A fuel injector for injecting fuel into a combustion chamber of an internal combustion engine, comprising a nozzle needle (14), which in one

High pressure bore (12) of a nozzle body (5) for releasing and

Closing at least one injection opening (13) is guided in a liftable manner, and a magnetic actuator with a magnetic coil (8) for direct or indirect control of the lifting movement of the nozzle needle (14), wherein the magnetic coil (8) with an armature (20) and this with an anchoring needle (21) cooperates, further wherein the armature (20) and / or the armature needle (21) is guided in a magnetic body, and wherein the armature needle (21) directly or indirectly with the nozzle needle (14) cooperates,

characterized in that the magnetic body is inserted into the nozzle body (5) and formed as a guide sleeve (15).

2. Fuel injector according to claim 1,

characterized in that the guide sleeve (15) in a

cylindrical recess (10) in the nozzle body (5) is inserted.

3. Fuel injector according to claim 1 or 2,

characterized in that the guide sleeve (15) on an amagnetic separating body (9) and nozzle needle side is supported directly or indirectly on the nozzle body (5).

4. Fuel injector according to one of the preceding claims,

characterized in that between the guide sleeve (15) and the nozzle body (5) a spring (17) is arranged.

5. Fuel injector according to one of the preceding claims,

characterized in that between the guide sleeve (15) and the bottom wall (19) of the recess (10) a coupler plate (18) is arranged.

6. Fuel injector according to claim 5,

characterized in that in the coupler plate (18) on the front side (23) of the nozzle needle (14) adjacent the coupler space (24) is embedded.

7. Fuel injector according to one of the preceding claims,

characterized in that in the guide sleeve (15) has a

Nozzle needle side sleeve recess (28) is embedded.

8. Fuel injector according to claim 7,

characterized in that in the sleeve recess (28) a Ankernadelfeder (26) is arranged.

9. Fuel injector according to claim 8,

characterized in that the Ankernadelfeder (26) between a Hülsenausnehmungsbodenwand and with the Ankernadel (21) connected support disk (27) is clamped.

10. Fuel injector according to one of the preceding claims,

characterized in that in the armature (20) a fuel ka na I (29) is embedded.