RELATED APPLICATIONS

[0001]The present patent document claims the benefit of and priority to European Pa tent Application 18205701 .8, filed November 12, 2018, the entire contents of which are incorporated herein by reference.

FIELD

[0002]The disclosure relates to a helical fuel conveying element, as well as to a method for manufacturing the same. The disclosure further relates to a fuel pump hav ing a helical fuel conveying element.

BACKGROUND

[0003] It is known from prior art to use helical fuel conveying elements of metal that can be produced with small tolerances. The production costs of such elements are high. Observing small tolerances is important for achieving a good output and for con veying at a sufficiently high pressure.

SUMMARY

[0004]The present disclosure provides a helical fuel conveying element that may be made of plastic material and has small manufacturing tolerances. Further, the disclo sure provides a suitable method for manufacturing such a helical fuel conveying ele ment of plastic material. [0005]This is achieved, according to the disclosure, with the features of claims 1 and 10.

[0006]The fuel conveying element for a fuel pump of the present disclosure comprises a screw driving element accessible from one axial end of the helical fuel conveying element. This screw driving element is an element adapted to be non-rotatably con nected or engaged with a tool, e.g. a screw driver or a wrench, so that turning the tool results in a turning of the helical fuel conveying element around its center axis. Thereby, it is possible e.g. to screw the helical fuel conveying element out from an injection mold so that the helical fuel conveying element may be produced using but one injection mold from which it can be screwed after curing.

[0007] For this purpose, it is preferred that the helical fuel conveying element has no undercuts in the direction in which it is screwed out, so that it may be screwed out from the injection mold by simple rotation.

[0008]According to the disclosure it is possible to manufacture the helical fuel convey ing element from plastic material without the same having a burr.

[0009] It is preferred that the screw driving element is formed integrally with the helical fuel conveying element.

[0010] It is further preferred that the fuel conveying element and the screw driving ele ment are formed integrally as an injection molded part.

[0011] It is further preferred that the helical fuel conveying element has an in particular cylindrical recess at an axial end, at the proximal end of which, i.e. at the bottom of which, the screw driving element is arranged.

[0012] Further, it is preferred that a pin, in particular a metal pin, is inserted in the re cess, one axial end of which protrudes beyond the axial end of the helical fuel convey ing element. [0013] It is further preferred that the metal pin is connected to the helical fuel conveying element by press fitting.

[0014] Moreover, it is preferred that the screw driving element is configured as an inner torx or inner hexagon socket.

[0015] It is further preferred that the axial end of the pin directed towards the fuel con veying element is conical in shape. Thereby, an automatic centering of the pin relative to the fuel conveying element may be effected.

[0016]The disclosure further relates to a fuel pump with a fuel inlet, a fuel outlet and a drive device for driving the helical fuel conveying element. The fuel pump further com prises a helical fuel conveying element as described in the present application. Here, the pin in the recess serves as an axial bearing for the fuel conveying element.

[0017]The disclosure further refers to a method for manufacturing a helical fuel con veying elemen, in particular an element as described in the present application. The method comprises the following steps:

[0018] First, an injection mold with a helical cavity is provided. A thermoplastic material is introduced into this cavity. The cavity is then closed with a cover. After the thermo plastic material has cured, the cover is opened. A tool, e.g. a screwdriver or a wrench, is connected positively with a screw driving element, e.g. a screw head, which is ac cessible from the axial end of the fuel conveying element, so that the fuel conveying element can be screwed out of the cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Preferred embodiments of the disclosure will be explained hereunder with ref erence to Figures.

[0020] Figures 1 a to 1 c show different views of a helical fuel conveying element of the present disclosure. [0021] As can be seen in Figure 1 a, the fuel conveying element 10 is helical in shape. In Figure 1 a four thread pitches are illustrated.

DETAILED DESCRIPTION

[0022] Figure 1 b shows a sectional view of the fuel conveying element 10 of the present disclosure. A cylindrical recess 14 is provided at its upper end, with the screw driving element 12 being arranged at the recess bottom 14a. In the embodiment illustrated the same is configured as an inner torx.

[0023]The metal pin 16 is mounted in the recess 14 by press fitting, the lower end of the pin being conically shaped, whereby the pin is centered relative to the fuel convey ing element 10. If the fuel conveying element 10 is used in a fuel pump, the metal pin 16 serves as an axial bearing. The rotation provided by a non-illustrated drive device can be transmitted via a form-fitting element at the lower end of the fuel conveying element 10. In Figure 1 c, the same fuel conveying element 10 is illustrated in perspec tive view.