WO2005073546A1

WO2005073546A1 - Nozzle member, and valve

Info

Publication number: WO2005073546A1
Application number: PCT/EP2005/050278
Authority: WO
Inventors: Wolfgang Bloching; Robert Kuchler; Eberhard Kull
Original assignee: Siemens Aktiengesellschaft
Priority date: 2004-02-02
Filing date: 2005-01-24
Publication date: 2005-08-11

Abstract

Disclosed is a valve comprising a housing in which a valve actuating member and a nozzle member are disposed. Said nozzle member (2) is provided with at least one first injection nozzle (28), at least one second injection nozzle (30), and a first nozzle needle (13) which prevents a fluid from flowing through the at least one first injection nozzle (28) in the closed position thereof while allowing fluid to flow through the at least one first injection nozzle (28) in other positions. A second nozzle needle (14) is also provided which prevents a fluid from flowing through the at least one second injection nozzle in the closed position thereof while allowing fluid to flow through the at least one second injection nozzle (30) in other positions. The at least one first injection nozzle (28) is embodied such that the fluid is metered therethrough at an angle of spray (α) of 120° and less. The at least one second injection nozzle (30) is configured such that the fluid is apportioned therethrough at an angle of spray (a) of 140° and more. Furthermore, a valve actuating member, preferably a piezo actuator, which acts upon the first and second (13, 14) nozzle needle, is assigned to the valve.

Description

description

Nozzle body and valve

The invention relates to a nozzle body and a valve with a housing in which a valve drive and a nozzle body are arranged. The nozzle body has at least one first injection nozzle and at least one second injection nozzle, a first nozzle needle, which prevents the fluid flow through the at least first injection nozzle in its closed position and enables the fluid flow through the at least first injection nozzle to the other positions. Furthermore, a second nozzle needle is provided, which prevents fluid flow through the at least second injection nozzle in its closed position and releases the fluid flow through the at least second injection nozzle in the other positions. The valve drive is designed such that it acts directly or indirectly on the first and second nozzle needles.

Ever stricter legal regulations regarding the permissible pollutant emissions from internal combustion engines, which are arranged in motor vehicles, make it necessary to take various measures by which the pollutant emissions are reduced. One starting point here is to reduce the pollutant emissions generated by the internal combustion engine. Another starting point is to convert the pollutant emissions generated by the internal combustion engine into harmless substances by means of exhaust gas aftertreatment systems. The formation of soot is heavily dependent on the processing of the air / fuel mixture. In order to achieve a correspondingly improved mixture preparation, fuel is increasingly metered in under very high pressure. In the case of diesel Internal combustion engines have fuel pressures of up to 2,000 bar.

In addition, so-called register nozzle injection valves have become known, in the nozzle body of which two injection nozzle circuits are formed. The two injection nozzle circuits are assigned first and second nozzle needles. Such a nozzle body and such a valve are known from EP 0 976 649 A2. The valve has a housing in which a valve drive designed as a piezo actuator and a nozzle body are arranged. The nozzle body has a first row of injection holes and axially spaced therefrom a second row of injection holes. A nozzle needle is guided in a recess of the nozzle body and acts via an entraining mechanism on an insert body which forms an inner nozzle needle. The first nozzle needle is arranged in a recess of the valve body in such a way that, in its closed position, it prevents fluid flow through the at least first row of injection holes and in other positions it releases the fluid flow through the at least first row of injection holes. In its closed position, the second nozzle needle prevents fluid flow through the second row of injection holes and, in other positions, releases the fluid flow through the second row of injection holes.

To further reduce pollutant emissions, combustion processes have become known in which diesel fuel is metered in such a timely manner before top dead center of the respective piston of the cylinder that a largely homogeneous air / fuel mixture is produced. For this purpose, it is desirable that a large part of the fuel evaporate. Such combustion processes are used particularly in the part-load range of the internal combustion engine and have the advantage that load range, the soot emissions of the diesel engine are very much reduced. For maximum performance in full-load operation of the internal combustion engine, however, it is desirable to measure the fuel shortly before top dead center of the piston of the cylinder and at the start of the combustion of the air / fuel mixture, and thus to obtain an inhomogeneous mixture.

The object of the invention is to provide a nozzle body and a valve which is suitable both for fluid metering for an inhomogeneous gas / fluid mixture and for forming a homogeneous gas / fluid mixture.

The object is achieved by the features of the independent claims. Advantageous embodiments of the invention are characterized in the subclaims.

The invention is characterized by a nozzle body with at least one first injection nozzle and with at least one second injection nozzle, with a first nozzle needle, which in its closed position prevents fluid flow through the at least first injection nozzle and, in other positions, the fluid flow through the at least first injection nozzle releases. A second nozzle needle is provided which prevents fluid flow through the at least second injection nozzle in its closed position and releases the fluid flow through the at least second injection nozzle in other positions. The at least first injection nozzle is designed such that it measures the fluid at a jet cone angle of 120 ° and smaller. The at least second injection nozzle is designed such that it measures the fluid at a jet cone angle of 140 ° and larger. The invention is further characterized by a valve with a housing in which a valve drive and the nozzle body are arranged, the valve drive possibly acting indirectly on the first and second nozzle needles.

In the context of the invention, the jet cone angle is understood to mean that angle which corresponds to the double angle at which the fluid is metered through the at least first or second injection nozzle in relation to the axis of the respective nozzle needle. The at least first injection nozzle is advantageously designed as a first row of injection nozzles. The at least second injection nozzle is advantageously designed as a second row of injection nozzles. The first and second row of injection nozzles are then preferably arranged in such a way that the fluid is metered conically into the respective combustion chamber of the cylinder.

The at least second injection nozzle ensures that the fluid can be metered to form an inhomogeneous gas / fluid mixture. By at least the first

Injection nozzle ensures that when the fuel is suitably metered earlier with respect to the top dead center of the piston of the respective cylinder, on the one hand a homogeneous gas / fluid mixture is formed and on the other hand the metered fluid has a penetration depth that is less than that

Way to a cylinder inner wall or the piston and so it can be ensured that an oil film present there is not washed off.

In an advantageous embodiment of the invention, the position of the first nozzle needle can be set independently of the position of the second nozzle needle. Furthermore, the at least first injection nozzle is designed such that the fluid flows through it is measured at a beam cone angle of 90 ° and smaller. As a result, virtually complete evaporation of the fluid can be ensured particularly effectively for a homogeneous gas / fluid mixture formation. On the other hand, by appropriately closing the at least first injection nozzle in the event of a desired inhomogeneous gas / fluid mixture formation, it can be ensured that the fluid is not injected into an area of the piston of the respective cylinder which is unfavorable for wetting with fluid.

In a further advantageous embodiment of the invention, the cross section released by the at least second injection nozzle is at least twice as large as the cross section released by the at least first injection nozzle. This then ensures that the amount of fluid which is metered through the at least first injection nozzle when the at least second injection nozzle is released is so significantly lower that in this case it is disadvantageous for the inhomogeneous gas / fluid mixture formation. flow is negligible.

The nozzle body is particularly compact if the second nozzle needle is guided coaxially in the first nozzle needle or the first nozzle needle is guided coaxially in the second nozzle needle.

Embodiments of the invention are explained below with reference to the schematic drawings. Show it:

1 shows a valve,

Figure 2 shows a first embodiment of a nozzle body of the valve according to Figure 1 and FIG. 3 shows a second embodiment of the nozzle body of the valve according to FIG. 1.

Elements of the same construction and function are provided with the same reference symbols in all figures.

A valve (FIG. 1), which is preferably designed as an injection valve, in particular for metering diesel fuel into the combustion chamber of a cylinder of an internal combustion engine, comprises an injector housing 1, a nozzle body 2 and an injector body 4. The injector body 4 takes an actuator on, which is preferably designed as a piezo actuator 6. The piezo actuator 6 preferably consists of a stack of piezoelectric elements which expand in relation to the valve in the axial direction when electrical energy is supplied.

The piezo actuator 6 acts on a transformer 8, which in turn acts on a servo valve 10. A pressure in a control chamber 12 can be adjusted by means of the servo valve 10 by appropriately controlling fluid in a leakage chamber 11 which is formed in the injector body 4. Depending on the pressure in the control chamber 12, an outer nozzle needle 13 and / or an inner nozzle needle 14, which are arranged in a recess 16 of the injector body 4, then give a first row of injection nozzles 28 and / or a second row of injection nozzles 30 free or close them. The inner and outer nozzle needles 14, 13 and the drive mechanism assigned to them are designed such that at least the

Fuel flow can be controlled by the first row of injectors 28 if at the same time the fuel flow through the second row of injectors 30 is prevented. With a corresponding design of the drive mechanism, the inner nozzle needle 14 can also control the fluid flow through the first row of injection nozzles 28 and then the outer nozzle needle 13 can control the fluid flow through the second row of injection nozzles 30.

A spring 18 is also preferably provided, which prestresses the outer nozzle needle 13 into its closed position, in which it closes, for example, the first row of injection nozzles 28. The outer nozzle needle 13 has a seat surface 20 which, in the closed position of the outer nozzle needle 13, lies sealingly on a seat area 22 of the nozzle body 2 and thus prevents the fuel flow through the first row of injection nozzles 28. The inner nozzle needle 14 has a seat surface 24, which seals a further seat region 26 of the nozzle body 2 in the closed position of the inner nozzle needle 14 and thus prevents the fuel flow through the second row of injection nozzles 30.

The valve also includes the drive mechanism for actuating the inner nozzle needle and also the outer nozzle needle 14, 13. For example, a corresponding driver can be assigned to the inner nozzle needle 14, which is arranged and cooperates with the outer nozzle needle 13 such that after a predetermined stroke of the outer nozzle needle 13 away from its closed position, the inner nozzle needle 14 is carried along by the outer nozzle needle 13 and so also releases the second row of injectors 30. If necessary, however, a plurality of servo valves or also a plurality of piezo actuators or other corresponding drive mechanisms for preferably also independently actuating the outer and inner nozzle needles 13, 14 can be provided. The valve further includes a high pressure bore 36 through which fuel is supplied under high pressure, for example 2,000 bar.

The first row of injection nozzles 28 is designed such that it measures fuel at a jet cone angle of 120 ° and less. In the present exemplary embodiment, the jet cone angle of the first row of injection nozzles 28 is, for example, 100 °.

The second row of injection nozzles 30 is designed such that fuel at a jet cone angle of 140 ° and larger, e.g. 160 ° is measured.

The first row of injection nozzles 28 is preferably designed such that only a maximum of half of the fuel is metered through it, which is metered by the latter when the second row of injection nozzles 30 is open at the same time.

The jet cone angle of the first row of injection nozzles 28 is selected such that when the first row of injection nozzles 28 is released accordingly early in relation to a crankshaft angle of the internal combustion engine in which the nozzle body and thus the valve are arranged before the top dead center of the cylinder assigned to the valve, it is ensured that the penetration depth of the fuel is such that an existing oil film on the inside wall of the cylinder is not washed off. The fuel can thus be injected much more strongly in the direction of the piston crown of the piston of the cylinder by setting a corresponding jet cone angle and can be evaporated substantially before reaching the piston crown. For a homogeneous air / fuel mixture formation, it is essential that the fuel jet is essentially mixed with the air in the cylinder before it strikes a part of the piston or the inner wall of the cylinder. The fuel is then preferably already evaporated in the air. Depending on the geometry of the cylinder and the range of the crankshaft angle during which the fuel is metered into the cylinder, a different jet cone angle can thus be best suited for metering the fuel for homogeneous air / fuel mixture formation. However, tests have shown that a sufficiently good homogeneous air / fuel mixture formation is guaranteed at a jet cone angle of ≤ 120 ° and that there is still no significant fuel precipitation on the cylinder inner walls or the piston crown.

The correspondingly small dimensioning of the cross section of the first row of injection nozzles 28 in comparison to the second row of injection nozzles 30 can then ensure that when both the first row and the second row of injection nozzles 28, 30 are released, no relevant portion is present Fuel hits an area of the piston that is unfavorable for it.

The second row of injection nozzles 30 is preferably designed such that it measures the fuel at a jet cone angle of 140 140 °. As a result, a region of the piston which is favorable for the inhomogeneous air / fuel mixture formation is then hit by the fuel jet.

In a further embodiment of the nozzle body according to FIG. 3, the outer nozzle needle 13 and the inner one are preferred Nozzle needle 14 can be actuated such that at least the first row of injectors can be released separately from the second row of injectors 28, 30 and vice versa. In this case, the jet cone angle of the first row of injection nozzles 28 90 90 ° can be selected in a particularly advantageous manner, and a particularly favorable jet cone angle can thus be achieved, under which the path to the cylinder inner wall or the piston is particularly long if the fuel is metered in early and thus a fuel deposit on the piston or the cylinder inner wall can be reliably prevented. In this case, it may also be irrelevant how the cross sections of the first row of injection nozzles are dimensioned in comparison to the second row of injection nozzles.

Claims

claims

1. Nozzle body with at least one first injection nozzle and with at least one second injection nozzle, with a first nozzle needle, which prevents fluid flow through the at least first injection nozzle in its closed position and releases the fluid flow through the at least first injection nozzle in other positions, and a second Nozzle needle, which prevents fluid flow through the at least second injection nozzle in its closed position and releases the fluid flow through the at least second injection nozzle in other positions, the at least first injection nozzle being designed such that through it the fluid at a jet cone angle (ex) of 120 ° and is metered in smaller, and the at least second injection nozzle is designed such that it measures the fluid at a jet cone angle (α) of 140 "and larger.

2. Nozzle body according to claim 1, in which the position of the first nozzle needle is adjustable independently of the position of the second nozzle needle and in which the at least first injection nozzle is designed such that the fuel at a beam cone angle () of 90 ° and is measured smaller.

3. Nozzle body according to one of the preceding claims, wherein the cross-section released by the at least first injection nozzle is at least twice as large as the cross-section released by the at least second injection nozzle.

4. Nozzle body according to one of the preceding claims, in which the second nozzle needle is guided coaxially in the first nozzle needle or in which the first nozzle needle is guided coaxially in the second nozzle needle.

5. Valve with a housing (1) in which a valve drive and a nozzle body (2) are arranged according to one of the preceding claims, wherein the valve drive acts on the first and the second nozzle needle, given all indirectly.