JP2779029B2 - Fuel injection nozzle used for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The invention starts with a fuel injection nozzle according to the preamble of claim 1. In known fuel injection nozzles of this type (FIGS. 1 and 2), the filter bore opens directly into the fuel passage, the transition between the two bores having a sharp angle sensitive to fatigue failure. Is formed. This edge must be removed electrolytically in an additional working step. In addition, due to the small distance of the fuel passage to the outer peripheral wall of the nozzle holder, there are places in the transition area between the two holes with reduced wall thickness and pressure-resistant expansion.

Advantages of the Invention The fuel injection pump according to the present invention has the following advantages over the conventional one. That is, since the shape of the sharp edge is avoided at the transition portion of the connection hole to the fuel passage, an additional operation step that is difficult to master in manufacturing technology for removing such an edge is unnecessary. Furthermore, the wall thickness in the transition region between the two holes is reduced only slightly compared to the known configuration, so that the fuel injection nozzle can also be designed for extremely high fuel pressures exceeding 800 bar.

If the diameter of the connection hole is set so that the hole wall of the connection hole does not intersect the cut shape of the filter hole only in the range of the W-shaped leg located on the outside, even at the transition from the filter hole to the connection hole. The same advantageous configuration is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS In the following, embodiments of the invention will be described in detail with reference to the drawings. FIG. 1 shows a known fuel injection nozzle of the type mentioned at the outset in a partial longitudinal section and in a partial side view, and FIG. 2 shows an enlarged view of the area Z in FIG. FIG. 3 shows an embodiment of the fuel injection nozzle according to the invention in a partial sectional view corresponding to FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel injection nozzle of the type described at the outset shown in FIG. 1 has a nozzle body 10 which, together with an intermediate plate 12, is fixed to a nozzle holder 16 by a clamping nut 14. This intermediate plate 12 serves as a stroke stop for the valve needle 18. The valve needle is pressed by a closing spring 20 against a valve seat provided on the nozzle body 10 via a pressing member. The closing spring 20 is arranged in a chamber 22 provided in the nozzle holder 16 and is supported by a bottom 24 of the chamber 22. The chamber 22 is connected via a leak oil passage 26 to a leak oil connection (not shown) provided in the nozzle holder 16.

A pressure chamber (not shown) surrounding the valve needle 18 is formed in the nozzle body 10, in which the valve needle 18 has a pressure receiving shoulder. Further, the pressure chamber is connected to a fuel passage 32 provided in the nozzle holder 16 through holes 28 and 30 provided in the nozzle body 10 and the intermediate plate 12. The fuel passage extends along the chamber 22 and parallel to the chamber through the nozzle holder 16 to a filter hole 34 having a larger diameter, which has a rod-shaped filter body 36. Connecting piece for the fuel supply conduit, oriented obliquely to the nozzle axis
Through 38.

The filter hole 34 is formed using a deep hole punch.
The only cutting lip of this deep hole punch is W
Form a cut shape in the shape of a letter. This cutting shape is shown in detail in FIG. The cut configuration has two inner W-shaped legs 40, followed by two outer W-shaped legs 42. The transition between the outer W-shaped leg 42 and the hole wall 44 of the filter hole 34 is separated by a corresponding grinding in a deep hole punch into another section 4 which is obliquely installed.
It may have 6,48.

Due to the inclined position of the filter hole 34 with respect to the fuel passage 32 and the difference in diameter between the two holes, a sharp edge 50 that extends over part of the circumference of the fuel passage 32 at the transition between the two holes is often created. That cannot be avoided. Such edges can cause fatigue failure. This edge 50 is electrolytically removed in an additional operation step, which results in a hole shape, for example as shown in broken lines in FIG.

In the embodiment of the fuel injection nozzle according to the present invention shown in FIG. . The diameter of the connection hole is set smaller than the diameter of the filter hole 34 and larger than the diameter of the fuel passage 32. The connecting hole 52 is likewise formed by a deep hole punch and thus has a W-shaped cutting shape also with two outer W-shaped legs 56. The diameter or cutting shape of the connection hole 52 is matched to the diameter of the fuel passage 32, the passage wall 58 of this fuel passage only intersects the region of the outer W-shaped leg 56. The inner W-leg is eliminated and the perimeter 60 formed at the transition of the two holes has an edge angle of more than 90 ° over the entire circumference of this perimeter, so that the risk of fatigue failure is clearly reduced. This eliminates the need for additional working steps for post-processing the periphery.

Further, the diameter of the connection hole 52 is set such that the hole wall 62 crosses the filter hole 34 only in the range of the outer W-shaped leg 42. Therefore, also in this place, post-processing of the formed peripheral portion 64 becomes unnecessary. Another advantage of the fuel injection nozzle according to the invention is that the fuel injection nozzle has a high pressure-resistant expansion, since the minimum wall thickness s caused in the transition region of the holes is made larger than in the prior art. Is also to get.

The connection hole 52 may be formed in one working step together with the filter hole 34 by a suitably shaped deep hole punch.

────────────────────────────────────────────────── (7) Continuation of the front page (72) Inventor Fleischmann, Helmut D-8608 Memelsdorf Tuchshutter Straße 2 (56) References JP-A-59-87270 (JP, A) 58-124063 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02M 61/10 F02M 61/16

Claims (2)

(57) [Claims] 1. A fuel injection nozzle for use in an internal combustion engine, comprising a nozzle holder (16) provided with a chamber (22) for receiving a closing spring (20). At one end there is a connecting piece (38) for a fuel supply conduit, from which a filter hole (34) containing a filter body (36) is inserted into the nozzle holder. A fuel passage (32) passing laterally along said chamber
Wherein the filter holes are arranged obliquely with respect to the nozzle axis, are formed by a deep hole drilling method, wherein the fuel passage has a smaller diameter than the filter holes, A connection hole (52) is provided between the hole (34) and the fuel passage (32), which is disposed coaxially with the filter hole (34) and formed by a deep hole drilling method. And wherein the diameter of the connection hole is smaller than the diameter of the filter hole (34) and larger than the diameter of the fuel passage (32). The bottom of the connection hole (52) has a W-shaped cutting shape, and the passage wall (58) of the fuel passage (32) has an outer W-shaped leg (5).
The diameter or cut shape of the connection hole (52) is matched to the diameter of the fuel passage (32) so that the cut shape of the connection hole (52) does not intersect with the cut shape of the connection hole (52) only in the range of 6). , A fuel injection nozzle used for an internal combustion engine. 2. A filter hole (34) in which the hole wall (62) of the connection hole (52) is located only in the range of the W-shaped leg (42) located outside.
The fuel injection nozzle according to claim 1, wherein the diameter of the connection hole is set so as not to intersect with the cutting shape of the fuel injection nozzle.