JPH0626421A - Fuel injection nozzle for internal combustion engine - Google Patents

Abstract

PURPOSE: To avoid excessive heat transfer to a nozzle body by covering the nozzle body over a large surface with a heat protection plate of a fuel injection nozzle even when a built-in position is upside-down. CONSTITUTION: A radial inner sidewall 50 has an angle less than 40 degrees with respect to a central axis, and an outer edge area 54 following a radial outer sinuous crest 44 tilts towards a central plane. A circumferential edge of the outer edge area 54 is fit with a positioning clearance to an inner diameter of an additional part 26 of a fastening nut 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection nozzle for an internal combustion engine of the type described in the preamble of claim 1.

[0002]

In this type of fuel injection nozzle, known from DE-OS 30 00 061, for example, the heat protection plate has the shape of a grooved ring or a corrugated ring, the latter corrugated ring of which The shape has two corrugated peaks, one corrugated valley and radially inward and outwardly projecting edges. This heat protection plate is in a predetermined position in terms of configuration, that is, the corrugated peaks of the heat protection plate are on the end face of the nozzle body.
When the corrugated troughs are assembled in such a position that they come into contact with the engaging flanges from below, this heat protection plate covers most of the combustion chamber side end face of the nozzle body against combustion gas and radiant heat. . In the above-mentioned assembly, the thermal protection plate, even if it is correctly installed in position, tilts when it is fitted in the tightening nut or in the sleeve-like addition of this tightening nut. As a result, the corrugated peaks abut on the flange, and the corrugated valleys abut on the end surface of the nozzle body as corrugated peaks. Due to this upside-down assembly position condition, the uncoated inner circular surface of the end face of the nozzle body is set by the larger diameter of the corrugated valleys shown as corrugated peaks and Greater heat transfer than in the correct assembled position.

This results in a significant heating of the nozzle body during high-load operation of the internal combustion engine, which tightens the nozzle needle guided in the nozzle body and / or shortens the service life of the injection nozzle.

In order to obviate this drawback, in the injection nozzle described in DE-OS 38 36 413 the collar is arranged in the inner area of the heat protection plate, which collar is the flange of the tightening nut. Into the through hole and extends axially from the through hole to the end surface of the nozzle body. However, according to such a construction, in the case of this type of heat protection plate, the assembling can be performed only at the one assembling position, and the assembling position state must be always accurately controlled and protected during assembling. .

[0005]

According to the fuel injection nozzle of the present invention having the characteristics described in claim 1, even when the heat protection plate is in the upside down assembled position, that is, the peaks of the corrugations and the valleys of the corrugations are formed. Even when shown as peaks, it has the advantage that the heat protection plate covers the nozzle body over a large surface, so that excessive heat transfer to the nozzle body is avoided. Therefore, there is no control of the exact mounting position of the heat protection plate, in particular of the post-assembly control. Further, the heat protection plate of the present invention is DE-OS 3000
It has the advantage over the heat protection plate known from 061 that no greater axial clamping force is required. Furthermore, the heat protection plate is very accurately centered in the sleeve-like addition of the tightening nut.

[0006] According to the features of the dependent claims, further advantageous configurations of the invention are possible.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The injection nozzle has a nozzle body 10, which together with an intermediate disc 12 has a tightening nut 14.
Is fixed to a nozzle holder not shown in the drawing. For this purpose, the tightening nut 14 is provided with an inner annular shoulder 16, which engages an outer annular shoulder 18 of the nozzle body 10. Furthermore, the tightening nut 14 has an external thread 20 in the region of the annular shoulder 16, which external thread is the cylinder head 24 of the internal combustion engine.
It is engaged with an internal thread in the assembly hole 22 therein. A cylindrical shoulder 26 of the tightening nut 14, which surrounds the nozzle body 10 below the annular shoulder 18, is formed with a support shoulder 28 on the outside, on which the injection nozzle is mounted. Assembly hole 22 through the seal ring 30
It is pressed against the inner support shoulder 32. The injection nozzle shown is a so-called pintle nozzle, in which case the valve needle that opens inward is provided with a pin 34, which penetrates into the nozzle hole opening towards the combustion chamber and Forming a narrow annular gap with the wall of the hole. In this type of injection nozzle, the nozzle bottom 36 of the nozzle body 10 must be cooled particularly well in order to keep the carbonization in the injection-annular gap within certain limits. For this purpose, a flange 38 directed towards the end face of the nozzle bottom 36 and the inside of the additional part 26 of the tightening nut 14.
The heat protection plate 40 is elastically deformed and is tightened in the axial direction in the gap between and. This heat protection plate 40 protects the annular partial area of the nozzle bottom 36 from convection due to heat radiation and combustion gas of high heat, and discharges the heat to the tightening nut 14, from which heat is shortened by the cylinder head. It is transmitted within 24.

The heat protection plate 40 is shown in an ideal mounting position in FIG. 1 and in one possible mounting position in FIG. 2, and the heat protection plate 40 is stamped from a thin metal plate. , And two wavy peaks 42, 44,
A corrugated trough 46 between these corrugated peaks and two sidewalls 50 connecting the corrugated peaks 42, 46 to the corrugated trough 46,
It has the shape of a corrugated ring with 52 and a radially protruding outer edge region 54. The outer edge region 54, which follows the radially outer corrugated crest 44, has an inclined side wall 56 beginning at the corrugated crest 44 and a ring-shaped portion 58 which follows the side wall 56 at the center plane of the heat protection plate 40. And consists of. The outer edge area 54 is the wavy peak 4
4 may descend to the central plane with a slight inclination. The outer peripheral edge 60 of the heat protection plate 40 is designed so that the heat protection plate 40 fits into the hole of the additional portion 26 of the tightening nut 14 near the end of the nozzle body 10 on the side of the combustion chamber. The peripheral edge 60 is concentrically and accurately arranged in the hole of the addition portion 26. The inner peripheral edge 62 of the heat protection plate 40 coincides with the opening 64 of the flange 38. Towards this opening 64, the inner corrugated crest 42 extends as a narrow ring 66.

Further, the structure of the corrugated ring of the heat protection plate 40 is
The inclination of the side wall 50 on the radially inner side is 40 with respect to the central axis.
It is designed to have an angle a which is less than degrees, preferably 25 degrees. On the other hand, the radially outer side wall 52
Is more gentle and the side wall 52 has an inclination angle b of 45 to 60 degrees, preferably 50 degrees. Therefore, the angle a formed by both sidewalls 50, 52
+ B is in the range 60 ° to 100 °, preferably 75 °.

Note that the expressions of wave-shaped peaks and wave-shaped valleys are, as described above, the thermal protection plate 40 shown in FIG.
Although this expression no longer applies to the mounting position state of FIG. 2, the above expression is used even in this mounting position state.

[Brief description of drawings]

FIG. 1 is an enlarged vertical cross-sectional view of a combustion chamber side portion of a fuel injection nozzle.

FIG. 2 is an enlarged vertical cross-sectional view of a combustion chamber side portion of a fuel injection nozzle.

FIG. 3 is an enlarged vertical sectional view of a heat protection plate of the fuel injection nozzle of FIG.

[Explanation of symbols]

 10 Nozzle Body 12 Intermediate Disc 14 Tightening Nut 16 Annular Shoulder 18 Annular Shoulder 20 Male Thread 22 Assembly Hole 24 Cylinder Head 26 Addition Part 28 Supporting Shoulder 30 Seal Ring 32 Supporting Shoulder 34 Pin 36 Nozzle Bottom 38 Flange 40 Thermal Protection Plate 42 Corrugated Mountain 44 Corrugated crests 46 Corrugated troughs 50 Side walls 52 Side walls 54 Outer edge range 56 Side walls 58 Ring portion 60 Outer peripheral edge 62 Inner peripheral edge 64 Opening 66 Ring

Claims (4)

[Claims] 1. A fuel injection nozzle for an internal combustion engine, comprising a tightening nut for tightening a nozzle body with respect to a nozzle holder, the tightening nut including a sleeve-shaped additional portion surrounding the nozzle body, and a nozzle. An annular flange covering the end surface of the body from below with a gap, and the fuel injection nozzle has an annular heat which is axially tightened in the gap between the nozzle body and the annular flange. A heat shield having the shape of a corrugated ring of material of equal thickness with two corrugations and one corrugation trough between the corrugations. The heat protection plate is tightened in the axial direction by the two corrugation peaks and one corrugation trough, and is brought into contact with the end surface of the nozzle body or the axially opposite surfaces of the flange of the additional portion. In this case, the peaks of the corrugations are separated from the side walls by the valleys of the corrugations. In the combined type, the radially inner side wall (50) has a tilt angle of less than 40 degrees with respect to the central axis and is followed by the radially outer corrugated crest (44). The outer edge region (54) is inclined towards the central plane, the outer peripheral edge (60) of the outer edge region (54) fitting with the inner diameter of the additional portion (26) of the tightening nut (14) with positioning play. A fuel injection nozzle for an internal combustion engine, comprising: 2. A fuel injection nozzle according to claim 1, characterized in that the radially inner side wall (50) has an inclination angle of 25 degrees with respect to the central axis. 3. Side walls (5) forming corrugated valleys (46).
The fuel injection nozzle according to claim 1 or 2, characterized in that the angle (a + b) of 0,52) is in the range of 60 to 100 degrees. 4. An outer edge region (54) following the radially outer corrugated crest (44) has a beveled side wall (56) following the corrugated crest (44) and a radially extending ring-shaped portion (58). ) And a fuel injection nozzle according to any one of claims 1 to 3.