Nozzle of a fuel injector and fuel injector having such a nozzle

Abstract

The present invention relates to a nozzle of a fuel injector that comprises a pivotably symmetrical nozzle body having a hollow space for introducing a nozzle needle, a nozzle tip that is provided at one longitudinal end of the nozzle body and has openings for discharging fuel, a housing contact surface that is provided at the other longitudinal end of the nozzle body and serves the pressing at a housing of a fuel injector, and an overhang surface that is provided in the longitudinal extent of the nozzle body between the nozzle tip and the housing contact service and that serves the placement of a nozzle clamping nut. The nozzle is characterized in that the minimal distance of the pivot axis of the nozzle body from the overhang surface is smaller than the minimal distance of the pivot axis of the nozzle body from the housing contact surface.

Claims

1. A nozzle of a fuel injector comprising: a pivotably symmetrical nozzle body having a hollow space for introducing a nozzle needle; a nozzle tip that is provided at one longitudinal end of the nozzle body and has openings for discharging fuel: a housing contact surface that is provided at the other longitudinal end of the nozzle body and serves to press at a housing of a fuel injector; and an overhang surface that is provided in the longitudinal extent of the nozzle body between the nozzle tip and the housing contact surface and that serves the placement of a nozzle clamping nut, wherein the nozzle clamping nut is in face-sharing contact with radial and axial surfaces of the overhang surface, characterized in that the minimal distance (D.sub.1) of the pivot axis of the nozzle body from the overhang surface is smaller than the minimal distance of the pivot axis of the nozzle body from the housing contact surface.

2. The nozzle of claim 1, wherein a maximum distance (D.sub.3) perpendicular to the pivot axis of the nozzle body from an outer margin of the overhang surface is smaller than a maximum distance (D.sub.4) perpendicular to the pivot axis of the nozzle body from an outer margin of the housing contact surface.

3. The nozzle of claim 1, wherein an inner line of the overhang surface that defines the respective radial minimal distance of the projection surface from the pivot axis along the periphery of the nozzle has a smaller surface than an inner line of the housing contact surface that defines the respective radial minimum distance of the housing contact surface along the periphery of the nozzle.

4. The nozzle of claim 3, wherein the inner line of the housing contact surface completely surrounds the inner line of the overhang surface on a projection along the pivot axis.

5. The nozzle of claim 3, wherein an outer line of the overhang surface that defines the respective radial distance of the pivot axis from an outer margin of the overhang surface along the circumference of the nozzle has a smaller surface than an outer line of the housing contact surface that defines the respective radial distance of the pivot axis from an outer margin of the housing contact surface along the periphery of the nozzle.

6. The nozzle of claim 5, wherein the outer line of the housing contact surface completely surrounds the outer line of the overhang surface on a projection along the pivot axis.

7. The nozzle of claim 3, wherein a center line of the overhang surface that centrally divides the distance of the inner line from the outer line of the overhang surface along the periphery of the nozzle defines a smaller surface than a center line of the housing contact surface that centrally divides the distance of the inner line from the outer line of the housing contact surface along the periphery of the nozzle.

8. The nozzle of claim 7, wherein the center line of the housing contact surface completely surrounds the center line of the overhang surface on a projection along the pivot axis.

9. The nozzle of claim 1, wherein one or more of the housing contact surface and the overhang surface is arranged perpendicular to the pivot axis of the nozzle body.

10. The nozzle of claim 1, wherein one or more of the housing contact surface and the overhang surface has the form of a circular ring.

11. The nozzle of claim 1, wherein the nozzle is formed in one piece.

12. The nozzle of claim 1, wherein the nozzle is rotationally symmetrical.

13. The nozzle of claim 1, wherein one or more of an outer diameter and an inner diameter of the nozzle continually increases transversely to the pivot axis from a tip to the housing contact surface.

14. The nozzle of claim 1, wherein the nozzle clamping nut is in threaded connection with the housing such that the nozzle presses the housing contact surface toward the housing via a force effect of the nozzle clamping nut on the overhang surface.

Description

(1) Further details, features, and advantages of the invention will be explained with reference to the following description of the Figures. There are shown:

(2) FIG. 1: a sectional view of a part of an injector for fuel injection in accordance with the prior art;

(3) FIG. 2: an enlarged detail around the shoulder region of the nozzle shown in FIG. 1 at which the nozzle clamping nut engages; and

(4) FIG. 3: an enlarged detail around the seat plate of an injector in accordance with the invention from different view sides;

(5) FIG. 1 shows a sectional view of a part of an injector for injecting fuel.

(6) The injector here comprises a housing 5 in which the nozzle needle 8 is inter alia received. The latter projects from the housing 5 and is received by the nozzle 1 in a mount 2 provided for this purpose. At its distal end, the nozzle 1 has its nozzle tip 3 that is provided with openings for discharging fuel.

(7) To establish a sealing connection of the housing 5 and the nozzle 1, a nozzle clamping nut 7 is placed onto the nozzle 1 and is brought into engagement with a thread provided at the housing 5. The housing contact surface 4 of the nozzle 1 directed toward the housing 5 is pressed toward a corresponding surface of the housing by the threaded connection the nozzle clamping nut 7 and the housing 5 so that a sealing connection results. In this process, the nozzle clamping nut 7 presses toward the overhang surface 6 of the nozzle 1 and so presses the nozzle 1 toward the housing 5. In the drawing, the pivot axis 8 is also present or, with a rotationally symmetrical design, the axis of rotation 8.

(8) The dotted rectangle shows the region shown enlarged in FIG. 2.

(9) Already introduced elements are provided with the same reference numerals in FIG. 2 as in FIG. 1. The force flow originating from an application of the nozzle clamping nut is here shown by an angled arrow that extends from a more remote region of the pivot axis 8 to a closer region of the pivot axis 8. This is due to the inner margin of the housing contact surface 4 arranged closer to the pivot axis 8 with respect to the overhang surface 6 that enables the force flow shown. Such an arrangement as a result produces a large tensile stress in the transition region to the flange-like overhang or the overhang surface 6 as is symbolized by the thick arrow directly obliquely downwardly to the left in the drawing. The presence of such a high tensile stress promotes the occurrence of cracks in the shoulder region of the nozzle.

(10) FIG. 3 now shows a nozzle 1 in accordance with the invention, with the already known elements of the nozzle 1 being provided with the same reference numerals having been used as in the preceding Figures. They will also no longer be discussed separately in the following.

(11) Unlike the prior art, a different force flow from the nozzle clamping nut 7 via the nozzle 1 and the housing 5 is adapted due to the changed design of the housing contact surface 4. This force flow is shown by the angled arrow in FIG. 3 that extends from the overhang surface 6 to the housing contact surface 4. It can be recognized that it is now outwardly directed, on a direction of gaze from bottom to top (that is from the overhang surface 6 toward the housing contact surface 4) which has the result that the tensile stress in the transition region to the flange-like overhang or overhang surface 6 is much smaller. This is illustrated by an arrow that is narrower in comparison with FIG. 2.

(12) The minimal distance D.sub.1 of the pivot axis 8 of the nozzle body 1 from the overhang surface 6 is furthermore shown that is smaller than the minimal distance D.sub.2 of the pivot axis 8 of the nozzle body 1 from the housing contact surface 4.

(13) It can additionally also be recognized in the present embodiment that the maximum distance D.sub.3 perpendicular to the pivot axis 6 of the nozzle body 1 from an outer margin of the overhang surface 6 is smaller than the maximum distance D.sub.4 perpendicular to the pivot axis 8 of the nozzle body 1 from an outer margin of the housing contact surface 4. This also contributes to the desired reduction of the tensile stress in the transition region of the shoulder of the nozzle 1.