WO2012084515A1

WO2012084515A1 - Nozzle body comprising an injection hole having at least two inlet openings

Info

Publication number: WO2012084515A1
Application number: PCT/EP2011/072051
Authority: WO
Inventors: Uwe Leuteritz; Ferdinand Löbbering; Eberhard Kull
Original assignee: Continental Automotive Gmbh
Priority date: 2010-12-22
Filing date: 2011-12-07
Publication date: 2012-06-28
Also published as: DE102010063844A1; DE112011104547A5

Abstract

The invention relates to a nozzle body for an injection valve of an internal combustion engine and to a method for producing the nozzle body. The nozzle body has a nozzle body opening and at least one injection hole which extends from the nozzle body opening to an outer surface of the nozzle body and which has an outlet opening on the outer surface of the nozzle body. On the inner end facing the nozzle body opening, the at least one injection hole has at least two mutually spaced inlet openings.

Description

description

Nozzle body with one injection hole with at least two inlet openings

The invention relates to a nozzle body for an injection valve of an internal combustion engine having a nozzle body recess and at least one of the nozzle body recess to an outer surface of the nozzle body extending injection hole with an outlet opening on the outer surface of the nozzle body.

Such nozzle bodies are used, for example, in injectors for diesel engines. When installed, the nozzle body forms the tip of a Kraftstoffin ector and protrudes into a combustion chamber of a cylinder head. In known nozzle bodies, a nozzle body recess is arranged symmetrically about a longitudinal axis of the nozzle body, which frequently opens into a blind hole in the direction of the combustion chamber. From the blind hole go out one or more injection holes through which fuel can be injected into the combustion chamber. At its end opposite the combustion chamber, the nozzle body recess is in communication with a pressurized fuel supply line. In the nozzle body recess, a valve member, such as a nozzle needle, movably mounted. The valve member has a sealing edge, which forms a sealing seat with a sealing surface in the nozzle body recess in the closed state of the injection valve. In this state, lying below the sealing seat blind hole and the injection ^¬ holes are separated from the fuel supply, so that no injection of fuel into the combustion chamber takes place.

To open the injector, the nozzle needle is lifted off the sealing seat. Thus, pressurized fuel may flow from the fuel supply line to the injection holes and be injected therethrough into the combustion chamber of the internal combustion engine. In operation affect parameters such as the flow behavior and the flow rate of fuel through the injection holes ^¬, the combustion process in the combustion chamber. Among other things, due to increasingly stringent legal regulations, an ever-optimized control of the combustion process in terms of fuel consumption and emissions becomes necessary. In the case of diesel engines, two effects occur which require counter-measures and thus lead to a conflict of goals.

To reduce emissions, injection holes with a small diameter and the highest possible flow coefficient are advantageous. For a given injection hole diameter, a high conicity of the injection hole and a high degree of rounding at the inlet opening also lead to a high flow coefficient.

On the other hand, the low injection hole diameter and high flow coefficients increase the inclination of the injection holes for coking. Deposits of the fuel lead to a partial clogging of the spray holes.

The formation of cavities of the fuel flowing through reduces the coking tendency. For a good coking ^¬ resistance, therefore, rather larger injection holes with lower flow coefficients (and cavitating fuel) are advantageous.

So far, attempts have been made to counteract the conflict of goals by means of various measures within certain limits. By shortening the spray hole length, a lowering of the

Degree of rounding and an increase in the roughness in the spray hole, which favors the cavitation, the coking tendency of today's series nozzles could be improved.

The invention is therefore based on the object of providing an improved nozzle body and a method for producing such, with which said conflict between an improved coking resistance and a high flow coefficient can be even better solved. The object is achieved by a nozzle body according to the independent device claim and by a method for producing a nozzle body according to the independent method claim. Advantageous developments of the invention are specified in the dependent claims.

An inventive nozzle body for an injection valve comprises a nozzle body recess and at least one injection hole extending from the nozzle body recess to an outer surface of the nozzle body. The injection hole has an outlet opening on the outer surface of the nozzle body and at least two separate inlet ^¬ openings at its pointing to Düsenkörperausnehmung, inner end.

Due to the inventive design of the injection hole with two separate inlet openings, the fuel initially follows two separate injection channels when flowing through the injection hole. These are combined before the fuel exits into the combustion chamber to form a common stream. The flow of the fuel through the injection hole therefore extends in two areas. In a first region, the streams run as separate, coming from the separate inlet openings

Partial streams in separate injection channels. In the second area, the two partial flows are combined and then enter as a stream through the outlet opening into the combustion chamber.

This allows the first region to be optimized in terms of coking tendency and the second region to achieve a high flow coefficient.

In the first region, in the two initially separate injection channels, initially a flow with a relatively low flow coefficient and high cavitation can be accepted. As a result, the coking tendency in the first region is kept low. In the second area, the two streams are discharged before the flow through the outlet opening of the Injection hole united. By combining the two partial flows, a pressure drop close to the outlet opening can be minimized and the total throughput through the injection hole can be increased. Thus, a high flow coefficient can be achieved at the flow at the outlet opening. Since the flow with the high flow coefficient is limited only to the last region of the injection hole just before and at the outlet opening, the coking tendency plays a minor role here. The reduction of the coking tendency in the first region can be achieved for example by a slight rounding at the A ^¬ passage openings, a high roughness in the two separate injection ports or a small conicity of the injection ducts. In the second area, the union of the two partial flows results in an occurrence in the first area

Pressure loss of the fuel balanced again, so that at the outlet through the outlet opening a high flow coefficient can be achieved. According to a preferred development of the invention, separate injection channels each run between the separate inlet openings and the outlet opening of the at least one injection hole and open into each other only in the region of the outlet opening. At the mouth of the two injection ducts while the cross section of the injection hole in the off ^¬ exit opening is minimal. This embodiment has the advantage that the narrowest point of the injection hole in the region in which the two flows are combined, is located at the outlet opening. This achieves a high flow coefficient, which has a favorable effect on the emissions of the combustion process.

According to a further preferred development, the at least one injection hole comprises at least three separate injection openings. In this way, the partial streams of three separate inlet openings and injection channels can be combined and injected through a common outlet opening in the combustion chamber. This allows another increase the pressure build-up in the union area just before the outlet opening. The optimization of the flow in the first region with the three or more separate injection channels can therefore be even more focused on the reduction of coking tendency. By combining three or more partial streams in front of the outlet opening, an even higher flow coefficient can be achieved. A limitation of the number of inlet openings and separate injection channels per injection hole is determined by the existing space in the nozzle body and the requirements of the strength of the nozzle body and the nozzle body material.

In a preferred embodiment, the injection channels extend substantially rectilinearly between the separate inlet openings and the outlet opening. The separate injection channels preferably intersect at an acute angle. For example, the angle between the individual injection channels is less than 20 °, preferably less than 15 ° and, in particular, an angle of less than 10 ° is advantageous. By combining the two partial flows at an acute angle, a pressure loss through a deflection of the partial flows can be largely avoided. Due to the achievable high pressure in the mouth area in front of the outlet opening thus a high flow coefficient can be achieved.

The substantially rectilinear, separate injection channels between the inlet openings and the outlet opening may be configured, for example, cylindrical or conical. Advantageously, a cylindrical or only slightly conical configuration, since thereby favors the cavitation of the fuel and thus the coking tendency is reduced.

In a first embodiment variant, the injection channels extend between two inlet openings and an outlet opening of the same injection hole, each at the same elevation angle relative to a longitudinal axis of the nozzle body. The A- Then, each outlet openings are preferably arranged at the same height relative to the longitudinal axis of the nozzle body.

In another alternative variant, the injection channels extend between two inlet openings and the outlet opening of a spray hole in each case at different elevation angles relative to the longitudinal axis of the nozzle body. In this case, the inlet openings to these separate channels have different height positions with respect to the longitudinal axis of the nozzle body.

In a variant with three or more inlet openings per injection hole both variants mentioned can be combined. This means that, on the one hand, two injection channels can run at the same elevation angle with respect to the longitudinal axis and, on the other hand, one or more injection channels can additionally run at a different elevation angle with respect to the longitudinal axis of the nozzle body.

In a preferred embodiment, the nozzle body has a plurality of injection holes. The plurality of injection holes are preferably arranged distributed radially around the nozzle body axis. Preferably, the injection openings of the one or more injection holes are in the region of a blind hole of the nozzle body recess.

An injector for an internal combustion engine having a nozzle body OF INVENTION ^¬ to the invention is an independent subject of the invention.

A method for producing the nozzle body according to the invention is also an independent subject of the invention. The method according to the invention comprises the steps of: providing a main body for a nozzle body for an injector with a nozzle body recess. At least one injection duct between an off ^¬ opening and an inlet opening at a first angle is then formed with respect to the nozzle body axis in the nozzle body. This first Channel is preferably formed by electrolytic erosion by means of an electrode. After the first channel is formed between the outlet opening and a first inlet opening, the electrode is withdrawn and then tilted at an acute angle with respect to the first angle. Subsequently, the electrode is attached to the first outlet opening and, starting from the same outlet opening, a second channel is formed between the outlet opening and a second inlet opening at the acute angle with respect to the first channel.

Subsequently, the electrode can be withdrawn again and optionally continued to form a further injection channel and a further inlet opening at an additional angle in a corresponding manner.

It should be noted that the separate injection channels in their imaginary extension do not have to cut the longitudinal axis of the nozzle body. As an angle between the injection channels and the longitudinal axis of the nozzle body is therefore to be understood in the context of this application, a Pro ektion a skewed angle to the longitudinal axis of the nozzle body.

In the following, the invention will be explained in more detail with reference to the exemplary embodiments illustrated in FIGS. 1 to 3. They show schematically:

Figure 1: a first embodiment of the invention

Nozzle body in partial sectional view along the longitudinal axis of the nozzle body;

FIG. 2 shows a detail enlargement of the view from FIG. 1; and

FIG. 3 shows a second embodiment of the invention

Nozzle body in partial sectional view perpendicular to the longitudinal axis of the nozzle body.

FIG. 1 shows a nozzle body 1 according to the invention in a partial sectional view, cut through the longitudinal axis 8 of FIG Nozzle body. The base body of the nozzle body 1 is arranged in ^¬ We sentlichen rotationally symmetrical about the longitudinal axis 8 of the nozzle body. Inside is a nozzle body recess 2 with a conical sealing surface, which opens into a blind hole 9 towards the nozzle tip. On the wall of the blind hole 9 go from the Düsenkörperausnehmung 2 two injection channels 7.1 and 7.2 of an injection hole 4 from. These extend to the outer surface 3 of the nozzle body. The two injection channels 7.1 and 7.2 are rectilinear and are inclined under the elevation angles .1 and .2 with respect to the longitudinal axis 8 of the nozzle body.

FIG. 2 shows the region of the injection hole 4 from FIG. 1 in an enlarged detail. The two injection channels 7.1 and 7.2 each have an inlet opening 6.1 and 6.2. The two channels 7.1 and 7.2 are rectilinear and are substantially cylindrical. The two injection channels 7.1 and 7.2 open into one another at an acute angle. In the mouth region 10, the partial flows of the two injection channels 7.1 and 7.2. united. The cross section of the combined injection channels in the mouth region 10 decreases steadily in the direction of the outlet opening 5, so that the narrowest point with a minimal cross section is formed at the outlet opening 5. In the first, separate region 11 of the two injection channels 7.1 and 7.2, the fuel flow can thus cavitate and take place with a relatively low flow coefficient. The coking tendency can be kept low in this area 11. By combining the two partial streams in the mouth region 10 close to the injection hole outlet 5, the total throughput of the injection hole 4 is formed by the sum of the two partial streams. As a result, a high fuel pressure prevail in the injection hole shortly before the outlet opening 5, as a result of which a high flow coefficient can be achieved.

3 shows a sectional view of a second variant of a nozzle body according to the invention in a section perpendicular to the longitudinal axis of the nozzle body in the region of the blind hole 9. All around the axis 8 of the nozzle body seven injection holes 4 are arranged radially uniformly distributed about the axis 8. The injection holes 4 each have an outlet opening 5 and two separate inlet openings 6.1 and 6.2. From the separate inlet openings 6.1. and rectilinear injection channels 7.1 and 7.2 to the common outlet opening 5. The rectilinear channels 7.1 and 7.2 meet in the mouth region 10 just before the outlet opening at an acute angle of 8 ° to each other, so that a pressure drop in the injection hole are kept low and a high flow coefficient can be achieved.

With the idea according to the invention of opening a plurality of injection channels into a common injection hole with a common outlet opening, both the flow coefficient and the coking resistance can be improved compared with the solutions known from the prior art. Thus, with the invention, the conflict of objectives known from the prior art between a high coking resistance and a high flow coefficient can be mitigated.

Claims

claims

1. nozzle body (1) for an injection valve, comprising a Düsenkörperausnehmung (2) and at least one of the Düsenkörperausnehmung (2) to an outer surface (3) of the nozzle body extending injection hole (4) with an off ^¬ outlet opening (5) on the outer surface (3) the nozzle body (1),

characterized,

the at least one injection hole (4) has at least two inlet openings (6.1, 6.2) which are separate from one another at its inner end pointing toward the nozzle body recess (2).

2. nozzle body (1) according to claim 1, wherein between the separate inlet openings (6.1, 6.2) and the outlet opening (5) of the at least one injection hole (4) each separate injection channels (7.1, 7.2) extend, which in a Mün- dungsbereich ( 10) open into one another near the outlet opening (5), wherein a minimal cross-section of the injection hole (4) is formed in the mouth region (10) of the two injection channels (7.1, 7.2) at the outlet opening (5).

3. nozzle body (1) according to one of the preceding claims, wherein the at least one injection hole (4) has three or more mutually separate inlet openings.

4. nozzle body (1) according to one of the preceding claims, wherein the channels (7.1, 7.2) between the inlet openings (6.1, 6.2) and the outlet opening (5) are substantially rectilinear.

5. nozzle body (1) according to one of the preceding claims, wherein the channels (7.1, 7.2) between the inlet openings

(6.1, 6.2) and the outlet (5) cut at an acute angle.

6. nozzle body (1) according to one of the preceding claims, wherein the channels (7.1, 7.2) between two inlet openings (6.1, 6.2) and the outlet opening (5) each have the same elevation angle relative to a longitudinal axis of the nozzle body.

7. nozzle body (1) according to one of the preceding claims, wherein the channels (7.1, 7.2) between two inlet openings (6.1, 6.2) and the outlet opening (5) each have different elevation angles (al, .2) relative to a longitudinal axis (8) of the Have nozzle body (1).

8. Nozzle body (1) according to one of the preceding claims, wherein a plurality of injection holes (4) are arranged radially uniformly distributed about a longitudinal axis (8) of the nozzle body.

9. Injector for an internal combustion engine with a nozzle body (1) according to one of the preceding claims.

10. A method for producing a nozzle body (1) according to one of the preceding claims, comprising the steps:

Providing a main body for a nozzle body (1) with a nozzle body recess (2),

Forming at least one first injection channel (7.1) between an outlet opening (5) and an inlet opening (6.1) of an injection hole (3) at a first angle (al) with respect to the nozzle body axis (8) by electrolytic erosion by means of an electrode, retracting the electrode and then tilting the electrode at an acute angle with respect to the first angle (α.1),

Forming a second channel (7.2) between the outlet opening (5) and a second inlet opening (6.2) of the injection hole (4) at the acute angle to the first angle (.1).