JPH04232375A - Fuel injection nozzle for internal combustion engine - Google Patents

Abstract

PURPOSE: To reduce the difficulty in holding the concentricity of a valve seat (and a sealing seat) to two valve needles and a split sleeve and hold a machining cost low by establishing a valve seat for the two valve needles and a seal seat for the split sleeve positioned between the two valve needles as a single valve seat in a fuel injection nozzle. CONSTITUTION: A seal seat for a split sleeve 30 and a seal seat for both valve needles 15 and 16 are arranged in a single conical valve seat 29 of a nozzle body 10, and the sealing face of the split sleeve 30 is positioned between both valve needles 15 and 16.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a fuel injection nozzle for an internal combustion engine, which is provided with a nozzle body that protrudes into a combustion chamber, and the nozzle body is provided with a fuel injection nozzle that extends around the entire circumference at the end of the nozzle body on the combustion chamber side. It has two rows of injection holes distributed across the nozzle body and is provided with two coaxial, spring-loaded valve needles which direct the flow of fuel to the rows of injection holes in the nozzle body. A spring-loaded separating sleeve is provided, cooperating with the valve seat for supply and further arranged between the outer valve needle and the inner valve needle, the conical end face of the separating sleeve However, it relates to a type in which both injection hole rows are separated from each other by contacting a seal seat in a nozzle body.

0002

[Prior Art] For example, West German Patent Publication No. 2740
In a fuel injection nozzle of this type known from US Pat. No. 880, the valve seat for the valve needle and the sealing seat for the split sleeve are constructed separately from each other, with a portion of the nozzle A part is arranged in the main body, and a part in a split sleeve. This makes the processing of the nozzle body and nozzle needle expensive. Furthermore, with the valve seats machined independently of each other, problems arise with regard to sealing, since it is difficult to achieve a coaxial and precise position of the valve seats relative to each other.

0003

SUMMARY OF THE INVENTION It is therefore an object of the invention to eliminate the above-mentioned disadvantages in fuel injection nozzles of the type mentioned at the outset.

0004

[Means for Solving the Problem] In order to solve this problem, in the configuration of the present invention, the seal seat for the split sleeve and the seal seat for both valve needles are both formed in a single conical shape of the nozzle body. is arranged on the valve seat of the valve, the sealing surface of the split sleeve being located between the two valve needles.

[0005]

[Effects of the Invention] The fuel injection nozzle configured as described above can reduce the manufacturing cost of the common valve seat of the two valve needles and the manufacturing cost of the seal seat for the divided sleeve of the nozzle body, and reduce the cost of manufacturing the common valve seat of the two valve needles and the manufacturing cost of the seal seat for the divided sleeve of the nozzle body. It has the advantage of achieving good concentricity.

A further advantageous embodiment of the fuel injection nozzle according to claim 1 is made possible by the measures described in the following claims.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

The nozzle body 10, which can be firmly connected to a nozzle holder (not shown), has a round tip 11 on the side of the combustion chamber.
It has injection holes 12, 13 for pre-injection and main injection directed into the combustion chamber of the internal combustion engine in two hole circles axially offset from each other. In the nozzle body 10,
Coaxial 2 loaded by closing springs 17, 18
Two valve needles 15, 16 are slidable. One of the valve needles 15 controls the upper hole circle of both valve needles.
is constructed as a hollow needle, and the other valve needle 16, which controls the lower bore circle, is constructed as an inner needle. The hollow valve needle 15 is slidably mounted in the upper part of the nozzle body 10 with its feed-side guide section 20 and extends its diameter in the area of the pressure chamber 22 in the nozzle body 10 via a pressure shoulder 21 . and is provided with a conical sealing surface 23 at its end. The other valve needle 16 is slidably mounted with its feed-side guide section 25 in the axial bore 14 of the nozzle needle 15 and is connected via a pressure shoulder 26 and a shoulder 27 to the 2nd valve needle 16 . The turning diameter has been reduced, and the end has a conical sealing surface 2.
It is equipped with 8.

Seal surfaces 23 of both valve needles 15, 16,
28 cooperates with the seat surface of a common conical valve seat 29 provided on the round tip 11 of the nozzle body 10. The angle of inclination of the conical valve seat 29 is constant. The sealing surface 23 of the hollow valve needle 15 that controls the main injection is connected to the injection hole 1 of the upper hole circle.
Upstream of the openings of the two valve needles 16, the sealing surfaces 28 of the inner valve needles 16 rest in each case on a common valve seat 29, upstream of the openings of the injection holes 13 of the lower bore circle. A cylindrical split sleeve 30 is arranged in the annular gap between the shoulder 27 and the sealing surface 28 of the inner valve needle 16 . This split sleeve 30 is in sliding contact with the wall of the axial bore 14 of the hollow valve needle 15 . Furthermore, the split sleeve 30 is compressed by means of a compression spring 31, which is supported on the shoulder 27 of the internal valve needle 16 via a ring 32 with a transverse groove 33, at the corner of the conical sealing surface 34. It is applied to the valve seat 29 of the nozzle body in an area between two hole circles with holes 12 and 13. Since the dividing sleeve 30 is loaded with injection pressure, a plurality of radially inwardly directed ribs 35 are arranged on the valve-side end section in order to eliminate the risk of compression. rib 35
The play between the inner valve needle 16 and the inner valve needle 16 is slightly greater than the play between the outer side of the split sleeve 30 and the axial bore 14 of the hollow valve needle 15.

The first supply hole 37 of the nozzle body 10 is connected to a first injection pump for main injection.
7 opens into a pressure chamber 22 from which an annular gap 38 between the nozzle body 10 and the hollow valve needle 15 extends downstream. The second feed hole 39 opens into an eccentric pressure chamber 40 of the nozzle body 10 , in the area of which an annular groove 41 is arranged in the guide section 20 of the hollow valve needle 15 . There is. An oblique bore 42 in the valve needle 15 connects the annular groove 41 to an annular gap 43 between the hollow valve needle 15 and the inner valve needle 16 downstream of the pressure shoulder 26 .

The injection nozzle described above is mainly suitable for large diesel engines, and functions as follows.

First, fuel is supplied from the second injection pump to the pressure chamber 40 through the second supply hole 39, and further to the annular gap 43 through the inclined hole 42, and at this time, the pressure load causes the internal The valve needle 16 is lifted from the valve seat 29 so that fuel is injected through the injection hole 13 of the hole circle below, ie close to the tip of the rounded tip 11 . After this pre-injection, fuel from the first injection pump is pumped through the first feed hole 37 into the pressure chamber 22 and into the annular gap 38, the pressure load causing the hollow valve needle 15
the sealing surface 23 of the valve seat 29 is lifted from the valve seat 29, so that the fuel flows into the circular injection hole 1 far from the tip of the round tip 11.
It is injected through 2. During the opening movement of both valve needles 15, 16, the sealing surface 34 of the split sleeve 30 closes against the valve seat 29.
, so that the pre-injection and the main injection do not interfere with each other.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a fuel injection nozzle.

2 is an enlarged view of detail II of the fuel injection nozzle shown in FIG. 1; FIG.

FIG. 3 is a cross-sectional view of the fuel injection nozzle taken along line III-III in FIG. 2;

[Explanation of symbols]

10 Nozzle body 11 Round tip 12, 13 Injection hole 14 Axial hole 15, 16 Valve needle 17, 18 Closing spring 20, 25 Guide classification 21, 26 Pressure shoulder 22,40 Pressure chamber 23, 28, 34 Seal surface 27 Shoulder 29 Valve seat 30 Split sleeve 31 Compression spring 32 ring 33 Lateral groove 35 Ribs 37, 39 Supply hole 38, 43 Annular gap 41 Annular groove 42 Inclined hole

Claims (4)

[Claims] Claim 1: A fuel injection nozzle for an internal combustion engine, comprising a nozzle body that protrudes into a combustion chamber, and the nozzle body is distributed over the entire circumference at an end on the combustion chamber side. two coaxial, spring-loaded valve needles are provided, the valve needles having valve seats in the nozzle body for separate supply of fuel to said rows of injection holes. A spring-loaded separating sleeve is provided which cooperates with the valve needle and is further arranged between the outer valve needle and the inner valve needle, the conical end face of the separating sleeve being in contact with the nozzle body. In the type in which the two injection hole rows are separated from each other by contacting the seal seats for the split sleeve (30) and the seal seats for both valve needles (15, 16), Both nozzle bodies (1
0) in a single conical valve seat (29);
characterized in that the sealing surface of the split sleeve (30) is located between the two valve needles (15, 16);
Fuel injection nozzle for internal combustion engines. 2. Fuel injection nozzle according to claim 1, characterized in that the inclination of the conical valve seat (29) is constant. 3. Slidingly supported in the axial bore (14) of the hollow valve needle (15) and spaced apart to leave an annular groove relative to the outer circumferential surface of the inner valve needle (16). It is noted that the split sleeve (30) that is located in the annular section near the valve seat has a support rib (35) on the inside of the split sleeve that projects towards the internal valve needle (16). The fuel injection nozzle according to claim 2, characterized in that: 4. The split sleeve (30) has a shoulder portion (27
4. The fuel injection nozzle according to claim 3, characterized in that it is pressed towards the valve seat (29) by a compression spring (31) which is supported on the internal valve needle (16) at the angle .).