EP1672212B1 - Fuel injector for an internal combustion engine - Google Patents

Description

The present invention relates to a fuel injector for an internal combustion engine and a method for manufacturing (assembling) a fuel injector.

Such fuel injectors are used for supplying fuel to internal combustion engines and usually comprise an electric actuator arranged in a sleeve-like housing and a fuel injection valve which can be actuated by means of this actuator and, for this purpose, is in operative communication with the actuator. The control of the opening and closing of the injection valve can, depending on the type of actuator, electromagnetically or electrically. To control the injector with very high dynamics z. For example, the use of a piezoelectric actuator is often preferred. In such a piezoelectric actuator, a change in length is caused by applying an electrical voltage to a piezoceramic, which is transferable to an actuator of the injection valve. Especially with actuators that allow only a relatively small displacement ("Aktorhub"), as z. B. for the mentioned piezoelectric actuators is the case, the use of a servo injection valve has been found to be favorable. With the latter type of injectors, an actuator stroke independent stroke of a valve body (eg., Valve needle) of the injection valve can be achieved.

To a fuel injector to a drive device, for. B. to connect an engine control unit must contact pins of the actuator by means of a connecting device are electrically connected to a connection device (eg plug connector) accessible from the outside of the injector housing.

From the DE 197 15 487 A1 is a connection device in the form of a plugged onto two contact pins of a piezoelectric actuator contact plate known. The known contact plate is made of insulating plastic and provided with passage openings for the passage of almost parallel to the longitudinal direction of the actuator projecting pins. In the interior of the contact plate, starting from a contacting at a passage opening, electrical leads are respectively led to connection pins which protrude laterally out of the contact plate. By an encapsulation of an upper part of an actuator housing and the contact pins with the patch and contacted contact plate, a plug housing is formed in which the laterally projecting pins protrude into a connection chamber, so that at this point a connector is formed by means of which the piezoelectric actuator with a external line arrangement is connectable.

From the DE 198 44 743 C1 is also known a connection device in the form of a contact tongue carrier. The known contact tongue carrier is used for sealing and positioning of contact pins of a piezoelectric actuator for the injection valve of an internal combustion engine and has a device body made of plastic with passage openings for the passage of the contact pins. After placing the contact tongue carrier on the contact pins of the piezoelectric actuator, the contact pin ends protruding from the passage openings come into contact with welding lugs formed in the plastic body and can be used can be welded to them. The welding straps are electrically connected to laterally projecting contact tongues, which serve as connecting pins of a connector formed by a plastic extrusion.

The preparation of an electrical connection by means of the above-mentioned, known connecting devices is problematic in that these devices often are not in a precisely defined position after assembly and thus often have to be additionally adjusted manually. Without such an adjustment of the position and orientation of the connecting device, the electrical contacting of the contact pins is difficult. In addition, for a subsequent encapsulation of the connecting device in the case of insufficient positional accuracy there is the risk that encapsulation material undesirably passes through gaps which would be substantially smaller and thus sealing at a precisely defined position of the connecting device. Finally, it is problematic in the known connection devices that they are to be fixed during the overmolding with a tool-side hold-down in the desired position. This fixation complicates the encapsulation process and thus increases the effort in the manufacture of the fuel injector.

A fuel injector according to the preamble of claim 1 is known from DE 100 25 043 A1 and comprises an electric actuator arranged in a sleeve-like housing for actuating a fuel valve. The actuator has electrical contact pins (plug pins), which protrude from an axial opening of the injector. A mounted on the housing fuel return part simultaneously forms a connection device for electrically connecting the contact pins with pins one of the connecting device formed plug connection (for a correspondingly formed mating connector of an engine control unit). In one embodiment, it is provided that the contact pins are formed on the fuel return part and are contacted by the attachment of the fuel return part to the housing with the actuator. In this case, the contact pins formed on the connecting device engage axially in the housing opening. The problem with this known fuel injector positioning accuracy with which the contact pins are introduced for contacting in the axial opening.

It is an object of the present invention to simplify the electrical connection between the electric actuator and the electrical connection device of the fuel injector in a fuel injector of the type described above.

This object is achieved by a fuel injector according to claim 1 and a method for producing (assembling) a fuel injector according to claim 8. The dependent claims relate to advantageous developments of the invention.

The fuel injector for an internal combustion engine according to the invention comprises an electric actuator disposed in a sleeve-like housing and a connection device for electrically connecting contact pins of the actuator, which protrude from an axial opening of the housing, with connection pins of a connecting device formed by the connecting device, wherein the connecting device a An insertion portion which is adapted for axial engagement in the opening and is provided with passage openings for the passage of the contact pins, and wherein the peripheral portion of the insertion and an axial opening defining the inner peripheral surface of the housing cooperating locking means for axially fixing the insertion in the opening.

The basic idea of the invention is the implementation of a lock, z. B. a contact tongue carrier for defined positioning with respect to the injector.

The axial engagement of an insertion portion of the connecting device in the axial opening of the housing advantageously already causes a certain "coarse adjustment" of the position of the connecting device during assembly and allows in a simple manner the provision of comparatively narrow gaps between the connecting device and the housing.

For the more precise definition of the position of the connecting device with respect to the housing is essential according to the invention that the peripheral portion of the insertion is locked by (releasable or non-detachable) locking means with the axial opening bounding inner peripheral surface for axially fixing the insertion in the opening.

This additional measures for axial fixation of the connecting device are unnecessary. When the connecting device is injection molded onto the injector housing after its mounting, in the design according to the invention, in particular, no tool-side hold-down device (eg in an injection molding tool) is required.

Although the latching means may in principle be adapted in addition to an axial fixation for providing a radial centering and / or a rotational angular position fixation, so this is by no means mandatory to provide more accurate means of the inventive design and the latter positioning. Namely, if the radial positioning and / or the rotational angle position, regardless of the locking means z. B. accomplished by cooperation of corresponding portions on the one hand on the connecting device and on the other hand on the housing, it can in many cases improve the already more accurate axial positioning and fixing this interaction in their result. The invention therefore also allows in these cases an improvement in the radial positioning or angular position of the connecting device, wherein a readjustment of the connecting device by hand can be omitted depending on the specific design. The assembly the connection device can then be automated in particular.

The latching means preferably comprise at least one radial projection and a corresponding radial recess. In a preferred embodiment, for example, it is provided that an inner circumferential surface of the axial opening has at least one radial latching recess which is latched with a corresponding latching projection on the peripheral region of the insertion section.

For each locking projection, a separate locking recess may be provided. This can be z. B. realize in a simple manner, a locking with respect to the angular position of the connecting device. However, it can also be provided a latching recess for several, in particular all locking projections. In particular, in this case, independent of the latching definition of the radial position and / or angular position of the connecting device is appropriate. One possibility for this is described below (interaction of corresponding contact sections on the one hand on the connecting device and on the other hand on the housing).

A particularly simple design of the housing-side locking means results, for example, when this is designed as a ring on the inner surface of the axial opening circumferentially provided locking recess (annular groove). In such a groove can then engage one or more insertion arranged on the side locking projections for locking.

In a preferred embodiment, an inner peripheral surface of the axial opening has at least one radial locking recess, which is locked with a corresponding latching projection on the peripheral region of the insertion. In this case, it can be provided that the peripheral region of the insertion section has a plurality of circumferentially distributed, in particular evenly distributed, arranged and radially elastically resilient latching projections. Such resilient locking projections have the additional advantage that thus a radial centering effect for the insertion can be achieved.

In general, there are many possibilities for the design of elastically resilient latching projections. So these projections z. B. be provided as a separate, formed from relatively elastic material components (eg, in a two-component injection molding process together with the remaining material of the insertion section). Preferably, however, the latching projections are integrally formed on the remaining material of the insertion section. If this material is relatively inelastic, so the desired radial spring action can be accomplished by appropriate design of the locking projection. For example, the latching projection may be provided at the free end of a substantially axially extending material tongue.

In a particular embodiment, it is provided that the peripheral region of the insertion section is formed by a plurality of distributed in the circumferential direction, in particular evenly distributed, arranged and radially elastically resilient latching pin is formed. Such locking pegs can be designed, for example, as essentially projecting axially from a plastic body of the connecting device.

In the embodiment variants of the insertion section explained above, provision may also be made for this insertion section to have an annularly closed lateral surface over at least part of its axial extent, in particular at its proximal end, ie. H. at the end opposite to the free (distal) end of the insertion section. If only a more or less small annular gap remains between such a lateral surface and the inner circumferential surface of the axial opening in this region, there is the advantage that a sealing effect with respect to the encapsulation material used is achieved in a subsequent encapsulation of the assembled connecting device. Material penetrating into a comparatively small annular gap can solidify there and prevent further liquid material from moving on. An engagement pin or material tongues extending substantially axially towards the distal end of the insertion section can follow an annularly closed lateral surface of the insertion section.

In a preferred embodiment, the distal end of the insertion section is provided with one or more insertion bevels for facilitating the insertion process and / or the latching. For example, the mentioned locking projections or locking pin such insertion bevels (with a surface oblique to the axial direction) have.

In a preferred embodiment it is provided that the connecting device has a relative to the insertion section laterally offset and substantially tangentially extending abutment portion, which upon insertion of the insertion in the opening with a corresponding contact portion of the housing rotatably cooperates. This makes it possible to ensure that the connecting device is fixed in a defined radial position and rotational position relative to the housing. This is particularly advantageous if the insertion section can be inserted in any rotational position in the axial opening and also provide the locking means no rotation.

In this case, the positional accuracy achieved by the interaction of the abutment sections can be improved if the insertion section and the abutment section are integrally formed, for example as a device body, which is manufactured as a plastic molding.

• Einführen eines zum axialen Eingriff in die axiale Öffnung geeignet ausgebildeten und mit Durchtrittsöffnungen zum Durchtritt der Kontaktstifte versehenen Einführabschnitts der Verbindungsvorrichtung in die axiale Öffnung, und
• miteinander Verrasten von Rastmitteln, die einerseits am Umfangsbereich des Einführabschnitts und andererseits an einer die axiale Öffnung begrenzenden Innenumfangsfläche des Gehäuses vorgesehen sind, zur axialen Fixierung (Verrastung) des Einführabschnitts in der Öffnung.

The method according to the invention for producing a fuel injector is characterized by the following steps:

• Inserting a suitable for axial engagement in the axial opening and provided with passage openings for the passage of the contact pins insertion section of the connecting device in the axial opening, and
• Locking of locking means, which are provided on the one hand on the peripheral region of the insertion and on the other hand on an axial opening bounding the inner peripheral surface of the housing, for axially fixing (locking) of the insertion in the opening.

In this method, designs may be provided for the fuel injector to be manufactured, as already explained above.

Fig. 1

ist ein Axiallängsschnitt im oberen Bereich eines piezobetätigten Kraftstoffinjektors,

Fig. 2

ist eine perspektivische Ansicht des Kraftstoffinjektors,

Fig. 3

ist eine Draufsicht des Kraftstoffinjektors, und

Fig. 4

ist eine perspektivische Ansicht eines Kontaktzungenträgers, der bei dem Kraftstoffinjektor zur Kontaktierung des Piezoaktors verwendet ist.

The invention will be described in more detail below with reference to an embodiment with reference to the accompanying drawings. They show:

Fig. 1

is an axial longitudinal section in the upper region of a piezo-actuated fuel injector,

Fig. 2

is a perspective view of the fuel injector,

Fig. 3

is a plan view of the fuel injector, and

Fig. 4

is a perspective view of a contact tongue carrier, which is used in the fuel injector for contacting the piezoelectric actuator.

1 to 3 show a generally designated 1 fuel injector for an internal combustion engine, comprising a sleeve-like injector housing 10, in the upper region of a fuel supply port 12 and a fuel drain port 14 are provided. These connections 12, 14 are used in a conventional manner for high pressure supply or leakage of fuel in the trained as piezobetätigtes servo injector fuel injector 1. In the elongated in an axial direction A Injektorgehäuse 10 is a fuel injection valve and an operatively connected thereto piezo drive for actuating the Fuel injection valve housed. With regard to the basic structure of the fuel injector 1 is merely exemplary of the DE 199 56 256 B4 and the DE 100 07 175 A1 directed.

Furthermore, in FIGS. 1 to 3, a so-called contact tongue carrier 16, which constitutes a connecting device for the electrical connection of contact pins 18 of the actuator with contact tongues 20, can be seen. The contact tongue carrier 16 is formed as a plastic molded part with a device body in which an electrical line arrangement has been formed, the ends of which form on the one hand the contact tongues 20 and on the other hand welding lugs 22. The thus formed by the contact tongue carrier 16 contact tongues 20 (pins) are completed by a not shown in the figures, final plastic extrusion of the upper end portion of the injector 10 to a connector, by means of which the injector 1 connected to the installation of an internal combustion engine with an external line arrangement is, which leads to a drive unit for driving the injector 1. A portion of this final plastic extrusion surrounding the contact tongues 20 forms the housing of the connector.

The welding tabs 22 are platelet-shaped and come after mounting (placing) of the contact tongue carrier 16 on the housing 10 for contact with the contact pins 18 of the actuator, which protrude from an axial opening 24 of the housing 10. In this situation, which is illustrated in FIGS. 1 to 3, the upper ends of the contact pins 18 abutting the welding tabs 22 are welded to the welding tabs 22 or alternatively crimped to contact the actuator (to be electrically connected to the contact tongues 20). , Then, the final plastic extrusion takes place in the upper region of the housing 10, which encapsulates the manufactured contact and provides the connector housing for the contact tongues 20.

The contact tongue carrier 16 has an insertion section 26 which, when placed on the housing 10, comes into axial engagement with the axial opening 24 and is provided with passage openings for the passage of the contact pins 18. Due to a corresponding design of the peripheral region of the insertion section 26 and an axial circumferential opening 24 delimiting the inner peripheral surface of the housing 10 results after insertion of the insertion section 26 in the opening 24 a latch, which the insertion section 26 and thus the entire contact tongue carrier 16 with respect to the housing 10th fixed. As a result of this latching, the contact tongue carrier 16 moves into a well-defined position with respect to the housing 10, so that a complex readjustment of the position of the contact tongue carrier is not required with a suitable design of the contact tongue carrier and / or the latching means, which considerably simplifies the manufacture of the injector.

Fig. 4 shows again in detail the contact tongue carrier 16 produced in a plastic injection molding process. The contact tongue carrier 16 consists of a one-piece carrier body 28, of which a section forms the insertion section 26, as well as the line arrangement formed therein, from the perspective view of FIG. 4 only the contact tongues 20 are visible. The other (not visible) end of this line arrangement is formed by the welding tabs 22, which are arranged adjacent to passage openings 30 for the passage of the contact pins 18 of the piezoelectric actuator. These passage openings 30 extend through two sleeve extensions 32 provided for the insulation of the contact pins 18 of the insertion section 26.

In the illustrated embodiment, the peripheral portion of the insertion portion 26 is formed by two diametrically oppositely disposed and radially elastically resilient locking pin 34, which are like the sleeve extensions 32 of the material of the support body 28 and formed integrally therewith. The distal (free) ends of the locking pins 34 are formed as radially outwardly projecting projections 36 which are latched with a recognizable in Fig. 1, corresponding annular groove which extends on an inner circumferential surface of the axial opening 24. Due to the comparatively thin-walled configuration of the latching pins 34, the latching projections 36 can thus be elastically radially inwardly spring-loaded, which allows the insertion of the insertion section 26 into the axial opening 24 of the housing 10. In addition, the latching projections 36 are provided in the distal region with an inclined surface, which facilitates the insertion of the insertion section 26 as a run-on slope.

The carrier body 28 also forms an abutment section (abutment surface), designated 38, which is laterally offset with respect to the insertion section 26 and extends substantially tangentially at a distance from the insertion section 26. The abutment portion 38 or the abutment surface formed therefrom cooperates with a corresponding abutment surface of this injector housing 10 in the assembly of the contact tongue carrier 16, in which the insertion section 26 is inserted axially into the opening 24 of the injector housing 10. This design of the contact tongue carrier 16 with the contact portion 38, which cooperates with a corresponding contact portion of the housing 10, forces the contact tongue carrier 16 during its installation to some extent in the desired angular position, which, for example Ensuring reliable installation of the contact pins 18 on the welding lugs 22 is advantageous. The detent means formed in the example shown as latching projections 36 and annular groove on the housing lead to an axial fixation of the insertion section 26 and thus of the contact tongue support 16 on the housing 10, which in turn promotes the reliable interaction of the anti-rotation abutment sections. In addition, due to the radially elastically resilient design of the latching projections, advantageously a "fine adjustment" with respect to the radial position of the insertion section 26 in the opening 24 (centering). Finally, in the situation illustrated with FIGS. 1 to 3, the axial fixation of the contact tongue carrier 16 dispenses with the use of a hold-down device in the injection molding tool for the formation of the final plastic extrusion coating.

• Axialer Formschluss zur genauen Positionierung des Kontaktzungenträgers auf dem Injektorgehäuse.
• Entfall des Niederhalters im Spritzgusswerkzeug bei anschließendem Steckeranspritzen.
• Minimierung des radialen Spiels des Kontaktzungenträgers auf dem Injektorgehäuse.
• Vermeidung einer aufwändigen, zusätzlichen Positionierung des Kontaktzungenträgers von Hand vor dem Umspritzen des steckerseitigen Gehäuseendes.
• Optimierung des Toleranzausgleiches der Anlageabschnitte bei einer Verdrehung des Kontaktzungenträgers auf dem Injektorgehäuse.
• Falls eine (z. B. finale) Kunststoffumspritzung des steckerseitigen Endes vorgesehen ist, spielt eine etwaige Relaxierung von Abschnitten des Kontaktzungenträgers über die Lebensdauer des Injektors keine Rolle, da die Lage der mit Kunststoff umgebenen Komponenten, also insbesondere auch des Kontaktzungenträgers, beim Anspritzen des Kunststoffmaterials ohnehin in ihrer Lage "eingefroren" werden.

The basic idea of the described embodiment is to form a contact tongue carrier, which is used for electrical contacting of the injector to the rest of the injection system, with regard to achieving a well-defined position and its fixation. The implementation according to the invention of a latching in a connecting device (eg contact tongue carrier) for the axial fixation on an injector housing makes this possible in a simple and production-favorable manner. This results in z. B. the following advantages:

• Axial positive locking for accurate positioning of the contact tongue carrier on the injector housing.
• Removal of the hold-down in the injection mold with subsequent Steckeranspritzen.
• Minimizing the radial clearance of the contact tongue carrier on the injector housing.
• Avoiding a costly, additional positioning of the contact tongue carrier by hand before the encapsulation of the plug-side housing end.
• Optimization of the tolerance compensation of the abutment sections with a rotation of the contact tongue carrier on the injector housing.
• If a (for example, final) plastic extrusion coating of the plug-side end is provided, any relaxation of sections of the contact tongue carrier over the life of the injector is irrelevant, since the position of the components surrounded by plastic, in particular also of the contact tongue carrier, during injection molding of the Plastic material in any case be "frozen" in their position.

Claims (8)

1. Fuel injector (1) for an internal combustion engine, comprising an electrical actuator arranged in a sleeve-like housing (10) and a connecting device (16) for electrically connecting contact pins (18) of the actuator, which protrude from an axial opening (24) of the housing (10), having connecting pins (20) of a connection facility embodied by the connecting device (16),
   with the connecting device (16) comprising an insertion segment (26), which is suitably configured for axial engagement into the opening (24) and is provided with openings (30) for the passage of the contact pins (18),
   characterized in that the peripheral area of the insertion segment (26) as well as an inner peripheral surface of the housing (10) which delimits the axial opening (24) comprise interactive locking means for axially fixing the insertion segment (26) in the opening (24).
2. Fuel injector as claimed in claim 1, with an inner peripheral surface of the axial opening (24) comprising at least one radial snap-in recess, which is snapped into a corresponding catch projecting part on the peripheral area of the insertion segment.
3. Fuel injector (1) as claimed in claim 2, with the peripheral area of the insertion segment (26) comprising a number of catch projecting parts (36) which are arranged in a distributed fashion in the peripheral direction and are radially elastically resilient.
4. Fuel injector (1) as claimed in one of the preceding claims, with the peripheral area of the insertion segment (26) being formed by a plurality of locking pins (34) which are arranged in a distributed fashion in the peripheral direction and are radially elastically resilient.
5. Fuel injector (1) as claimed in one of the preceding claims, with the connecting device (16) comprising a locating section (38) which extends essentially tangentially and is arranged laterally offset in respect of the insertion segment (26), said locating section exhibiting an anti-twist effect with a corresponding locating section of the housing (10) when the insertion segment (26) is inserted into the opening (24).
6. Fuel injector (1) as claimed in claim 5, with the insertion segment (26) and the locating section (38) being designed continuously in one piece.
7. Fuel injector (1) as claimed in one of the preceding claims, with welding or crimping plates (22) preferably being disk-shaped and being connected to the contact pins (18) of the actuator following assembly and/or positioning of the contact lug bracket (16) on the housing, said contact pins protruding from an axial opening (24) of the housing (10), with the upper end of the contact pins (18) which rests on the welding or crimping plates (22) being welded or crimped to the welding or crimping plates in order to contact the actuator, i.e. to be electrically connected to the contact lugs (20).
8. Method for producing a fuel injector (1) as claimed in one of claims 1 to 7, with the method comprising:

   - inserting the insertion section (26) of the connecting device (16) into the axial opening (24) of the housing (10), and

   - mutual locking of the locking means for axially fixing the insertion section (26) into the opening (24).

Images