Alignment element for an injector, and method for manufacturing an injector

A method for manufacturing an injector having an extrusion coating, including the following steps: providing an injection module, pushing a disk-shaped alignment element onto a part of the injection module, the alignment element having a slot in order to have sufficient flexibility, welding the alignment element onto the part of the injection module, at least part of the slot also being welded shut at the same time during the welding-on step in order to stiffen the alignment element, and molding the extrusion coating onto the injection module.

FIELD OF THE INVENTION

The present invention relates to an alignment element for an injector and a method for manufacturing an injector having a plug molding.

BACKGROUND INFORMATION

Injectors are known from the related art in various embodiments. Frequently, the installation situations for injectors are different for various types of engines, in particular with regard to their alignment. However, the alignment of the injectors is important, since a different spray pattern of the injector is obtained, depending on the alignment. However, since the spray pattern has effects on the fuel consumption and exhaust gas emissions, the injector in recent engines must be very precisely aligned. One alignment option, for example, would be to provide flat polished surfaces on the injection module. However, this results in an undesirable cost increase. In addition, it may be necessary to provide a specific polished surface for each type of engine. Alternatively, an additional component having alignment surfaces could be situated on the injector. This would also have the same disadvantages as the flat polished surfaces described above, and the level of effort for the alignment is shifted to the alignment operation during installation of the additional component. In addition, recent injectors have a partial plastic extrusion coating for forming a plug-in connection. The plug-in connection could also be used here as an alignment element for the injector, but the large number of injection molds required due to the variety of engine types is likewise disadvantageous.

SUMMARY

The method according to the present invention for manufacturing an injector has the advantage that an alignment element is provided which may be easily pushed onto a part of a preassembled injection module, so that the injection module together with the alignment element may be inserted into an injection mold in an aligned manner, and the extrusion coating may be molded on in a subsequent step. The alignment element is flexible during the pushing-on operation, and is welded to the injection module with the aid of a welding step. At the same time as the welding-on operation, a stiffening of the alignment element is carried out so that the alignment element in particular withstands the subsequent injection process. For this purpose, the alignment element is essentially disk-shaped and has at least one slot. The slot provides the flexibility during the pushing-on operation. In the subsequent welding step the slot is welded shut at the same time as the alignment element is welded onto the injection module, so that the rigidity of the alignment element which is then necessary for the injection process is present. Thus, the present invention elegantly achieves the aim that on the one hand it should be easy to push on the alignment element, which requires a reduced rigidity, and on the other hand the alignment element should be as rigid as possible for the injection process in order to avoid deformation due to a high injection pressure, and thus a misalignment in the injection mold. The alignment element which is stiffened by the welding operation in particular prevents a deformation from occurring during the injection process in such a way that the alignment element comes into contact with a wall area of the injection mold, so that it would be externally visible in the finished injector. As a result, however, the injector would no longer be leak-tight against spray water. However, according to the present invention a stiffening of the alignment element is carried out at the same time as the welding-on process of the alignment element to the preferably tubular part of the injection module, so that the alignment element may be simultaneously fastened to the injection module and stiffened in one step.

For the welding-on step, the injection module together with the alignment element which is pushed onto same are particularly preferably rotated. A particularly simple welding step may be carried out in this way.

According to another preferred embodiment of the present invention, a welding plane in which the alignment element is welded to the injection module does not coincide with a welding plane in which the slot is welded shut. This allows greater freedom of design of the alignment element without thus impairing the quality of the weld seam for fixing the alignment element to the injection module.

The alignment element particularly preferably has a tongue, which for the stiffening is at least partially welded to a base area of the alignment element in the welding-on step. The tongue may be easily produced by a punching step, for example, in which the slot is also provided in the alignment element at the same time.

The alignment element also preferably has a first and/or second tab, the first and/or second tab being situated adjacent to the tongue. The tongue is then welded to the first and/or second tab in the welding-on step. As a result of this measure, welding and thus stiffening of the alignment element in a different plane may be easily provided.

The welding is particularly preferably carried out with the aid of a laser, or alternatively, with the aid of two lasers oppositely situated from one another at an angle of 180°. When two lasers are used, it is necessary to rotate the injection module by only 180°.

Moreover, the present invention relates to an alignment element for an injector, which is fastenable to a preassembled injection module and is designed for alignment in an injection mold in order to apply an extrusion coating, in particular a plug molding, to the injection module. The alignment element includes a collar extending in the axial direction, a base area radially adjoining the collar, and an edge area radially adjoining the base area. In addition, a central through opening and a first slot, which is oriented in the radial direction and has a continuous design in the axial direction of the alignment element, are provided. The first slot extends radially outwardly, starting from the through opening. This results in flexibility of the alignment element, in particular in the area of the inner collar. Thus, this allows the alignment element to be very easily pushed onto a part of the injection module, which in particular is tubular. The collar is then welded to the injection component in the subsequent fastening step, and the alignment element is thus stiffened. An extrusion coating, in particular a plug receptacle, may be subsequently molded on, preferably in the area of the alignment element. The through opening is preferably elliptical.

The alignment element also preferably includes at least one second curved slot which is oriented in the peripheral direction and which likewise has a continuous design in the axial direction. Providing a slot which is oriented in the radial direction and a slot which is oriented in the peripheral direction results in flexibility in the radial and axial directions as well as in the peripheral direction, so that the alignment element may be pushed on in a particularly easy manner.

The first and second slots of the alignment element preferably intersect. This results in a further increase in the flexibility of the alignment element, thus making it even easier to push on the alignment element.

According to another preferred embodiment of the present invention, the alignment element also includes a tongue which protrudes into one of the slots. As a result of the tongue, particularly simple stiffening of the alignment element via a welding operation may be achieved by welding the tongue to a part of the alignment element. At the same time, at least one of the slots, preferably all slots, is/are preferably shut by the welding.

The alignment element also preferably includes a first and/or second tab which is/are situated at the base area, and the first and/or second tab is/are preferably situated adjacent to the tongue, and the tabs may thus be welded to the tongue during the welding step.

For even greater flexibility of the alignment element, the alignment element also includes a third slot which is oriented in the radial direction and is axially continuous, and/or a fourth slot which is oriented in the peripheral direction and is axially continuous, and the first and third slot and the second and fourth slot are particularly preferably formed symmetrically with respect to a center plane through the alignment element.

The alignment element also preferably includes a second slot which is oriented in the radial direction, at least one of the radial slots, as the continuous slot in the radial direction, extending from the through opening to the edge of the alignment element. As a result, the alignment element has a C shape and is no longer closed at at least one area in the peripheral direction. The alignment element may thus be spread apart in the peripheral direction, so that even greater ease of installation is achieved.

In addition, at least one of the slots preferably has an expanded area. The expanded area may be curved, for example. In particular after completion of an injection pass in which the slots are filled by the injection molding material, this results in improved rigidity and reliable filling of the relatively narrow slots with injection molding material.

The alignment element also preferably includes a base area which is inclined with respect to a base plane.

To obtain even better permeability of the injection molding material, the alignment element preferably has a plurality of through openings, in particular circular through openings, at the base area. To also allow simple and reliable alignment of the alignment element in the injection molding die, the alignment element preferably has at least one feature at the edge area for the alignment. The feature for alignment is preferably a recess, for example a V-shaped indentation or a linear contact surface at the edge area of the alignment element. Two alignment features are particularly preferably oppositely situated from one another at an angle of 180°.

To ensure that a high degree of fluid-tightness is obtained between the alignment element and the injection molding material after the injection operation, the alignment element preferably has a labyrinth configuration having at least one groove. Multiple grooves, which in particular are situated coaxially with respect to one another and extend in the peripheral direction, are preferably provided. A secure seal between the injection molding material and the alignment element may be achieved due to this labyrinth configuration. The labyrinth configuration is preferably provided on both flat sides of the alignment element. The alignment element is therefore suited in particular for applications in vehicles, in which contact with spray water or the like cannot be ruled out.

Moreover, the present invention relates to an injector having an alignment element according to the present invention on which an extrusion coating, in particular for a plug, is molded on. The alignment element is preferably completely enclosed by the extrusion coating. One or multiple alignment surface(s) or the like for the alignment is/are preferably provided on the extrusion coating for an installation in an internal combustion engine. The alignment element allows alignment surfaces to be molded onto the extrusion coating in a very precise manner.

DETAILED DESCRIPTION

An injector having a first alignment element3according to the present invention as well as a method for manufacturing the injector are described in greater detail below, with reference toFIGS. 1 through 8.

As is apparent fromFIG. 1, injector1includes an injection module2, shown in greater detail inFIG. 2, which in the present exemplary embodiment includes a solenoid actuator23in order to move a valve needle21. The valve needle opens up or closes a valve seat22at one end of the injector. Injector1also includes a plug molding4(extrusion coating) which is molded onto injection module2shown inFIG. 2. Injection module2is a preassembled module. A disk-shaped alignment element3is preassembled on a tubular part20of injection module2. Injection module2is inserted into an injection mold with the aid of alignment element3, and plug molding4is then molded on. Plug molding4has an alignment surface8which, the same as for the actual plug-in connection, must be individually fabricated for the particular customer and his requirements. Alignment surface8is subsequently used for aligning the injector during the step of installing the injector in the internal combustion engine, so that the spray pattern provided by the injector corresponds to the customer's requirements. Therefore, even during the process of molding on the plug molding, injection module2must be correctly aligned in the injection mold so that the spray alignment of the injector subsequently matches alignment surface8, which is provided on the extrusion coating via the injection process.

Alignment element3is illustrated in greater detail inFIGS. 3 through 8. Alignment element3is an essentially disk-shaped element, and has a central through opening40. Through opening40is delimited by a circumferential collar35which protrudes in axial direction X-X of the alignment element. Collar35is adjoined by a base area36which is inclined with respect to a base plane E of alignment element3, the base area being adjoined by a terminating edge area37. Edge area37is situated in base plane E of alignment element3. Alignment element3also includes a first slot31, a second slot32, a third slot33, and a fourth slot34. First slot31and third slot33extend in the radial direction, starting from a center axis of alignment element3, and are oppositely situated from one another at an angle of 180° (seeFIG. 3). Second slot32and fourth slot34extend in the peripheral direction over a circular angle of approximately 150° in each case. First slot31intersects second slot32, and third slot33intersects fourth slot34. All slots are continuous in axial direction X-X. This results in a high degree of flexibility of alignment element3. Flexibility results in axial direction X-X of alignment element3, in particular due to second and fourth slots32,34, respectively, as well as in the radial direction with respect to the center axis, in particular due to first and third slots31,33, respectively.

Alignment element3also includes a tongue30which protrudes radially inwardly into first slot31, starting from edge area37. As is apparent in particular fromFIG. 5, tongue30is still slightly bent in axial direction X-X. Alignment element3also includes a first tab38and a second tab39. First and second tabs38,39, respectively, are likewise bent from base area36in axial direction X-X, in the same direction as tongue30(seeFIG. 5). In the process, tongue30contacts the two tabs38,39at the side. As is most clearly apparent fromFIGS. 5, 6, and 7, a contact zone results between tongue30and the two tabs38,39outside base plane E of the alignment element. Alternatively, a small distance which is not critical for the welding operation may be provided between the tongue and the tabs, the distance being bridged by the welding operation.

Due to the high degree of flexibility of alignment element3in axial direction X-X as well as in the radial direction, alignment element3may be quickly and easily pushed onto a tubular part20of injection module2. A position of the alignment element in the pushed-on state onto tubular part20may also still be slightly corrected if necessary. The position of alignment element3is therefore important in order to ensure an alignment of injection module2in an injection molding die in order to mold on plug molding4in the correct alignment with respect to injection module2. In order for alignment element3not to be displaced during the injection process, it is welded to tubular part20via a weld joint, using a laser beam7. This results in a weld seam5between collar35of alignment element3and tubular part20(seeFIG. 8). For the welding operation, tubular part20is rotated together with alignment element3. As shown inFIG. 8, laser beam7no longer comes into contact with collar35or tubular part20in the area of tongue30, but instead comes into contact with tongue30, which protrudes in axial direction X-X, and protruding tabs38,39. Tongue30is thus welded to tabs38and39. As is apparent fromFIG. 8, a welding plane S2in which tongue30is welded to tabs38,39is situated outside normal welding plane S1in which collar35is welded to tubular part20. Alignment element3is stiffened as the result of welding tongue30to tabs38,39. Alignment element3is thus able to withstand the strong pressures during the subsequent injection process for manufacturing plug molding4, without alignment element3being bent or changed in its position.

Thus, due to the shape of alignment element3, laser beam7is interrupted in the area of the tongue during the welding operation, laser beam7being adjusted in such a way that it is possible to weld the tongue to the tabs outside the actual focus of the laser beam. Since first slot31of alignment element3is provided in the area of tongue30anyway, collar35is shielded only in the area of tabs38,39. However, this reduces the weld joint5along collar35only negligibly, by a width of the tabs.

Thus, with the aid of a single welding operation, while rotating tubular part20, alignment element3may be welded to tubular part20, as well as stiffened in the area of tongue30and tabs38,39. It is pointed out that a correspondingly formed tongue and correspondingly formed tabs may also be provided in the area of third slot33in order to automatically provide a second stiffening on the alignment element.

According to the present invention, alignment element3may thus have sufficient flexibility for installation, so that the installation may be carried out quickly and easily, and in particular very precisely. Alignment element3is also subsequently stiffened at the same time as alignment element3is fixed to tubular part20, it being possible for the stiffening and fixing of the alignment element to be carried out in one step due to the tongue and the tabs of alignment element3. According to the present invention, the manufacture of an injector may thus be significantly simplified and reduced in cost, and at the same time the precision of a subsequent necessary alignment of the injector in an internal combustion engine may be even further improved.

Further exemplary embodiments of the present invention are described below in greater detail, identical or functionally equivalent parts being denoted by the same reference numerals as in the first exemplary embodiment.

An alignment element3according to a second exemplary embodiment of the present invention is illustrated in greater detail inFIGS. 9 through 11. As is apparent from the top view inFIG. 9, alignment element3of the second exemplary embodiment includes two alignment features in the form of a first and second V-shaped indentation51,52, respectively, at edge area37. In addition, a plurality of circular through openings53is provided. The alignment element may be reliably aligned in the injection molding die via V-shaped indentations51,52. Furthermore, during the injection process, through openings53ensure that the injection molding material is able to reliably and quickly enter on both sides of alignment element3. As is apparent in particular fromFIGS. 9 and 11, alignment element3of the second exemplary embodiment may be manufactured very easily and cost-effectively, in particular since no tabs and/or tongues are provided. In addition, alignment element3of the second exemplary embodiment has a labyrinth configuration50. In this exemplary embodiment, labyrinth configuration50includes a circumferentially closed groove, a groove being provided on both sides of the alignment element. These two grooves ensure that very good sealing, in particular from the outside toward the inside, is possible after the injection process. Fluid-tightness of an injector in the area of alignment element3may thus be further improved.

FIGS. 12 through 14show an alignment element3according to a third exemplary embodiment of the present invention. Alignment element3of the third exemplary embodiment has no circumferential slots, but instead has two slots61,62extending in the radial direction. Slot62is designed as a radially continuous slot from central through opening40to edge area37. Alignment element3thus has a C shape in a top view (seeFIG. 12). Slot62, which is continuous from collar35to edge area37, in particular provides improved flexibility in the axial direction. In addition, alignment element3may also be spread apart slightly in the peripheral direction, so that a particularly simple and quick installation is possible. In addition, alignment element3of the third exemplary embodiment has expanded areas63,64which are provided at slots61,62, respectively. This ensures that the injection molding material also completely fills slots61,62, since the slots are each relatively narrow. In addition, edge area37and base area36of alignment element3are situated in a shared plane (see the cross section inFIG. 13).

FIGS. 15 through 17show further exemplary embodiments of the present invention. In the fourth exemplary embodiment shown inFIG. 15, a contact surface55protruding in the radial direction and a V-shaped indentation51are provided as an alignment feature at edge area37of alignment element3. Indentation51and contact surface55are oppositely situated from one another at an angle of180°. The fifth exemplary embodiment of alignment element3shown inFIG. 16shows a linear contact surface56resulting from removal of material at edge area37. For further improvement in flexibility, slots34,32extending in the peripheral direction have a first and a second radially inwardly oriented extended slot321and341, respectively. The two extended slots321,341extend in parallel to a recessed indentation57which is likewise used for the alignment. In addition, no through openings are provided in the fifth exemplary embodiment. The sixth exemplary embodiment shown inFIG. 17likewise has a contact surface56resulting from removal of material at outer edge area37of the alignment element. However, in the sixth exemplary embodiment the extended slots of the fifth exemplary embodiment as well as the recessed indentation of the fifth exemplary embodiment are absent. The sixth exemplary embodiment may thus be manufactured very easily and cost-effectively.