NOZZLE NEEDLE FOR A FUEL INJECTOR, AND INJECTOR HOUSING FOR A NOZZLE NEEDLE

Abstract

A nozzle needle for a fuel injector, the nozzle needle including an elongated nozzle needle main body which has, at one of its two long ends, a nozzle needle tip for selectively closing an injection opening of the fuel injector. The nozzle needle also including a plastic and/or ceramic sleeve for enclosing the nozzle needle main body peripherally along a longitudinal region of the nozzle needle, which longitudinal region is spaced apart from the nozzle needle tip.

Claims

1. A nozzle needle for a fuel injector comprising: an elongate nozzle needle base body, wherein the elongate nozzle needle base body has a nozzle needle tip at one longitudinal end for a selective closing of an ejection opening of the fuel injector, and a plastic and/or ceramic sleeve surrounding the elongate nozzle needle base body at the peripheral side along a longitudinal region of the nozzle needle and spaced apart from the nozzle needle tip.

2. The nozzle needle in accordance with claim 1, wherein the plastic and/or ceramic sleeve is fixedly connected to the elongate nozzle needle base body.

3. The nozzle needle in accordance with claim 1, wherein the elongate nozzle needle base body is rotationally symmetrical to its longitudinal axis and the plastic and/or ceramic sleeve is pivotably symmetrical.

4. The nozzle needle in accordance with claim 1, wherein the elongate nozzle needle base body is composed of an electrically conductive material.

5. The nozzle needle in accordance with claim 1, wherein the plastic and/or ceramic sleeve is arranged in a region between two longitudinal ends of the elongate nozzle needle base body and the nozzle needle tip and/or the other longitudinal end spaced apart therefrom is not surrounded by the plastic and/or ceramic sleeve.

6. An injector housing for a nozzle needle, comprising: a mount for inserting and guiding the nozzle needle so that the nozzle needle can close an ejection opening of the injector housing in dependence on the nozzle needle insertion position, a plastic and/or ceramic sleeve for surrounding a nozzle needle base body at the peripheral side along a longitudinal region of the nozzle needle and spaced apart from the ejection opening.

7. The nozzle needle in accordance with claim 6, wherein the plastic and/or ceramic sleeve is fixedly connected to the injector housing.

8. The nozzle needle in accordance with claim 6, wherein the plastic and/or ceramic sleeve is pivotably symmetrical to a longitudinal axis of the injector housing.

9. The injector housing in accordance with claim 6, wherein the injector housing (H) is composed of an electrically conductive material.

10. The injector housing in accordance with claim 6, wherein the plastic and/or ceramic sleeve is arranged in a region between an arrangement position of a control valve and the ejection opening.

11. A method of manufacturing a nozzle needle comprising an elongate nozzle needle base body wherein the elongate nozzle needle base body has a nozzle needle tip at one longitudinal end for a selective closing of an ejection opening of a fuel injector, a plastic and/or ceramic sleeve surrounding the elongate nozzle needle base body, at the peripheral side along a longitudinal region of the nozzle needle and spaced apart from the nozzle needle tip, wherein the nozzle needle is only ground after attachment of the plastic and/or ceramic sleeve to achieve a maximum coaxial alignment of the sleeve and the elongate nozzle needle base body.

12. The method of manufacturing the nozzle needle in accordance with claim 11, wherein the plastic and/or ceramic sleeve is produced by injection molding or by an additive production process.

13. The method of manufacturing the nozzle needle in accordance with claim 11, wherein an inner diameter of the plastic and/or ceramic sleeve is only ground after a fixed connection to an injector housing to achieve an optimum coaxial guidance through the sleeve of the nozzle needle to be inserted.

14. The method in accordance with claim 13 wherein the plastic and/or ceramic sleeve is produced by injection molding or by an additive production process.

15. A fuel injector having a nozzle needle wherein the nozzle needle comprises an elongate nozzle needle base body; wherein the elongate nozzle needle base body has a nozzle needle tip at one longitudinal end for a selective closing of an election opening of the fuel injector and a plastic and/or ceramic sleeve surrounds the elongate nozzle needle base body, at the peripheral side along a longitudinal region of the nozzle needle and spaced apart from the nozzle needle tip.

16. The nozzle needle in accordance with claim 2, wherein the plastic and/or ceramic sleeve is connected to the elongate nozzle needle base body by a connection with material continuity or shape matching.

17. The nozzle needle in accordance with claim 3, wherein the plastic and/or ceramic sleeve is not rotationally symmetrical to the longitudinal axis of the elongate nozzle needle base body.

18. The nozzle needle in accordance with claim 4, wherein the plastic and/or ceramic sleeve of the nozzle needle is composed of an electrical insulator comprising at least one of Al.sub.2O.sub.3 or Si.sub.3Ni.sub.3.

19. The method in accordance with claim 12, wherein the plastic and/or ceramic sleeve is fastened to the elongate nozzle needle base body after a debinding and/or a sintering.

20. A fuel injector having a nozzle needle with an injector housing, wherein the injector housing comprises: a mount for inserting and guiding the nozzle needle so that the nozzle needle can close an ejection opening of the injector housing in dependence on the nozzle needle insertion position, and a plastic and/or ceramic sleeve within the mount, wherein the plastic and/or ceramic sleeve surrounds a nozzle needle base body at the peripheral side along a longitudinal region of the nozzle needle is spaced apart from the ejection opening.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0038] Further advantages, features, and details of the present invention will become clear on the basis of the following description of the Figures. There are shown:

[0039] FIG. 1: a schematic representation to explain the already known prior art;

[0040] FIG. 2: a schematic representation of a nozzle needle in accordance with the invention together with a sectional view in an injection housing; and

[0041] FIG. 3: an enlarged representation of an embodiment in accordance with the invention of the present invention.

DETAILED DESCRIPTION

[0042] FIG. 1 shows a partial sectional view of an injector 10 from the prior art. The injector 10 can be recognized that has a housing 14 in which a plurality of injector components are arranged. The injector needle 15, the valve formed by the armature 11 and the seat plate 18, and the electromagnet 12, 13 that has a coil winding 16, an inner magnetic pole 12, and an outer magnetic pole 13 are essential to the function of the injector 10 here. A cutout for arranging the spring 17 that urges the armature element 11 in the direction of the valve is furthermore provided in the inner magnetic pole 12 to close the outflow throttle of the valve in a currentless state of the electric magnet 12, 13 in a fluid tight manner.

[0043] If the electromagnet 12, 13 is activated, it pulls the armature element 11 away from the valve with the aid of magnetic force so that highly compressed fuel can flow out of the passage 19 from a control space closable by the valve. Since the pressure in the control space that acts on the injector needle is hereby reduced, the latter can slide out of a closed position and enables the discharge of fuel from the injector 10. If, in contrast, the electromagnet 12, 13, is moved into a currentless state, the magnetic force acting on the armature element 11 is reduced so that the spring element 17 urges the armature element 11 onto the discharge opening of the valve and seals the control space or the passage 6. The pressure acting on the injector needle 15 thereby increases so that the latter is again urged into its closed position. There is accordingly no longer any outflow of fuel from the discharge opening of the injector 10.

[0044] In its upper region, FIG. 2 shows a longitudinal sectional view of a nozzle needle 1 in accordance with the present invention. It can be recognized that the nozzle needle base body 2 has a substantially rod-like basic design and converges to a point at one of its longitudinal ends. The nozzle needle tip 3 that converges to a point serves in an injector 10 to close the at least one fuel discharge opening.

[0045] It can be recognized in a region disposed between the two longitudinal ends that the nozzle needle base body 2 is surrounded by a plastic and/or ceramic sleeve 4 that effects an electrical insulation with respect to an injector housing 14.

[0046] Unlike the nozzle needle base body 2, this sleeve 4 can also be designed not as rotationally symmetrical, but, for example, only pivotably symmetrical to the longitudinal axis 21 of the nozzle needle base body 2.

[0047] The lower section of FIG. 2 is a cross-sectional view of the nozzle needle at the level of the sleeve 4 from the upper section of FIG. 2 in a state inserted into an injector housing 14.

[0048] The injector housing 14 here has a circular inner periphery in which the nozzle needle 1 is received. The nozzle needle 1 is movable in its longitudinal direction, that is in parallel with the longitudinal axis 21, so that it can be moved into an open position from a closure position of the injector 10 in which the discharge opening is closed by the nozzle needle tip 3. For this purpose, it is raised upwardly in the longitudinal direction and an outflow of fuel takes place.

[0049] The sleeve 4 can have a substantially pivotably symmetrical form that does not adjoin the inner periphery of the housing in a continuously flush manner in the peripheral direction. An approximately triangular base shape can thus be selected as in the present case, with each of the corners having a flush area toward the circular segment of the inner periphery of the injector. A space that can be used for the flow of fuel toward a discharge opening can be provided between the outer surfaces 41 of the sleeve 4 and the inner periphery of the injector 14.

[0050] It is clear to the skilled person that the present invention is not restricted to the specific design of the sleeve 4 shown in FIG. 2, but rather comprises a plurality of possible forms.

[0051] FIG. 3 shows a longitudinal sectional view of a lower part of a fuel injector that is equipped with a nozzle needle 1 and an injector housing 14 in accordance with the invention.

[0052] It can be recognized that the injector housing 14 has a plastic and/or ceramic sleeve 5 in a guide region for guiding the nozzle needle 1 so that an electrically conductive contact of the injector housing 14 with the nozzle needle only takes place in the nozzle needle tip with a closed injector.

[0053] The plastic and/or ceramic sleeve 5 arranged at the housing 14 can be fixedly connected there, for example by soldering or adhesive bonding.

[0054] The plastic and/or ceramic sleeve 5 arranged at the housing 14 can thus have a cylinder jacket shape and ensure a flow of fuel through a corresponding adapted shape of the nozzle needle.

[0055] Provision can additionally made for the further reduction of wear that the nozzle needle 1 is also provided with a plastic and/or ceramic sleeve arranged at it so that on a movement of the nozzle needle, there is only a contact of plastic and/or ceramic material. This represents a particularly low-friction contact that results in particularly low wear due to comparable surface hardnesses.