DE10254681B4 - Injection nozzle and injection method, and a manufacturing method for an injection nozzle - Google Patents

Abstract

Injection nozzle with outwardly opening valve, comprising a nozzle body (H) with a cavity whose inner wall (L) is formed in a region as a valve seat (A), and a needle (C) guided through the cavity, wherein the needle end (B) the needle (C) in an end position on the valve seat (A) presses and thus a suitable for a fluid closed sealing surface (F ') between the nozzle body and the needle can be generated,
in which
An asymmetrical space is provided between the needle end (B) and the valve seat (A) such that the shape of the needle end (B) follows only in a partial region of the entire shape of the valve seat (A),
The asymmetrical space is positioned upstream above the sealing line or sealing surface,
The area of the asymmetrical space has an enlarged volume in relation to the symmetrical space and thus serves as a throttling area (J) for a fluid,
whereby the asymmetrical jet pattern of the generated injection jet is separated from the asymmetrical space and the ...

Description

The The invention relates to an injection nozzle and an injection method, especially for Gasoline engines.

A optimal mixture preparation of a fuel and stability of a Combustion in a cylinder of a motor vehicle sets in usually precede that in terms of the amount injected and the beam angle as possible rotationally symmetric fuel cone jet leads into the combustion chamber. It this is a spray-guided combustion process, too Stratified charge operation called in the temporally possible late in the morning Compression stroke is injected and the injector centrally in the combustion chamber roof (collinear to the cylinder axis) between the inlet and outlet valves is positioned. The installation position explains the requirement for a rotationally symmetrical cone beam, otherwise in the case of asymmetric cone jet of the injector in the angular direction relative to the position of the spark plug would have to be installed precisely aligned.

The Demand for a compression pressure that occurs under all typical engine types Beam cone angle comes from the need for that the spark plug at the ignition point from a stoichiometric be enveloped composite air and fuel mixture cloud got to. This takes place, for example, from a second, later injection a lean mixture of the layer charge, for example by a first previous injection to be able to ignite. Smallest deviations in the beam symmetry or fluctuations in the beam cone angle of one injection to the next to lead inevitably to misfires or for wetting the spark plug. The Injection takes place at a high compression pressure in a 5 to 10-fold denser medium, the jet penetration depth decreases significantly and due to the central location of the injector in the combustion chamber roof a cylinder wall wetting is avoided.

The prior art discloses the following:
The publication DE 198 55 568 A1 describes, for example, a fuel injection valve. This has a spherical valve closing body and a valve needle which is axially movable. The valve closing body has at least one flattening on the surface, wherein a channel for a fuel flow is formed between the at least one flattening and an inner wall of a closing body carrier. Such a fuel injection valve is particularly suitable for use in fuel injection systems of mixture compressed, externally ignited internal combustion engines.

The DE 100 55 483 A1 discloses a fuel injector for fuel-engines, wherein an actuator via a valve needle actuates a valve closing body. This acts together with a valve seat surface, wherein the valve needle and / or the valve closing body have at least one circumferentially mounted swirl passage. This has a variable cross-section. Upon actuation of the valve by the movement of the valve needle, an axial shortening of the throttling length is achieved.

From the GB 2 211 548 A an injection nozzle is known which also comprises a ball element. This has annular sealing zones. The control of the spherical sealing element is done by a control via a nozzle needle, wherein recesses are controlled on the ball sealing body a corresponding dosage.

Out all three cited references is the formation of the injection jet through fixed channels causes. Thus, the respective characteristic of injection jets for these injector types.

The above procedures are each based on the 1 shown. The injection valve or the injection nozzle H is positioned centrally on the cylinder axis. The figure on the left shows a "Spray Guided Central Injection Stratified Form" in a stratified charge operation wherein the piston P has a compression within the combustion chamber BK and a compression stroke in the late ignition by the spark plug SP is triggered. The figure on the right shows a homogeneous gas-air mixture preparation. The beam profile 1 of the injection fluid is symmetric conical.

In a Formula 1 engine, however, the injector is installed in the central position, in 1 characterized by the dashed line, in the combustion chamber roof for reasons of total cylinder head assembly is not possible, so the installation must be avoided on a decentralized location away from the cylinder axis. In addition, the Formula 1 engine is operated with a homogeneously processed air-fuel mixture. For racing engines, it is customary to carry out an early injection in the intake and at the beginning of the compression stroke in order to ensure optimum mixture formation. At an early injection time, there is a pressure in the cylinder which deviates only slightly from the ambient air pressure. The air in the cylinder is of low density and the penetration of the injection jet into the cylinder deep. The shape of the injection jet in this process is in 2 shown. It is clearly visible that the deep penetration of the injection jet and one side of the jet profile 1 already before an ignition already hits the piston P and wets (Piston Wetting).

• – durch die nichtaxiale Einbauposition des Injektors
• – durch die Einspritzung des Kraftstoffs in ein Gas mit geringer Dichte welche zu einer zu großen Penetration führt

So it comes in particular for the following reasons to a wall wetting with fuel in homogeneously operated Formula 1 engine:

• - by the non-axial installation position of the injector
• - By injecting the fuel into a gas with low density which leads to an excessive penetration

• – Der an der Wand niedergeschlagene Kraftstoff nicht mit hinreichender Geschwindigkeit verdampft, um im folgenden Verbrennungstakt verbrannt zu werden. Eine hiermit erzeugte Fehldosierung und ein Leistungsabfall haben eine schlechte Fahrbarkeit oder "Driveability" zur Folge.
• – Der an der Wand niedergeschlagene Kraftstoff wird durch, die Kolbenringe des Zylinders nicht vollständig abgestreift und beeinträchtigt die Kolbenschmierung, welches zu einem stärkerem Verschleiß zwischen Zylinderinnenwand und Kolben und im schlimmsten Fall zu einem Kolbenfresser-Effekt, oder Ätzeffekt des Kolbens führen kann.
• – Der Kraftstoff in den Schmierölkreislauf gelangt und die Schmierung andere motorinterner Aggregate gefährdet, welches zu deren Schädigung und Ausfall führen kann.
• – Der Kraftstoff an der Zylinderinnenwand und an den Kolbenringen aufgrund der Verbrennungshitze verkokt. Die Dichtfunktion der Kolbenringe wird dadurch beeinträchtigt. Es ergibt sich dadurch ein Kompressionsverlust und ein Leistungsverlust des Motors.

But a cylinder wall wetting with fuel should be avoided, since

• - The fuel deposited on the wall does not evaporate with sufficient speed to be burned in the following combustion cycle. An incorrect dosage and a loss of performance caused by this result in poor driveability or "driveability".
• The fuel deposited on the wall is not completely stripped off, the piston rings of the cylinder and affects the piston lubrication, which can lead to increased wear between the cylinder inner wall and piston and in the worst case to a piston seizure effect, or etching effect of the piston.
• - The fuel enters the lubricating oil circuit and the lubrication endangers other engine-internal aggregates, which can lead to their damage and failure.
• - The fuel coked on the cylinder inner wall and on the piston rings due to the heat of combustion. The sealing function of the piston rings is impaired. This results in a compression loss and a power loss of the engine.

A common geometry of an injector of an injector is based on the 3 to 6 shown. Typically, the fluid injection is in the form of a cone beam.

3 shows a rotationally symmetrical, hollow cone-shaped incorporated in a nozzle body H valve seat A.

4 shows a frusto-conical closing element B with a needle C, a symmetrical side G with a steep angle, a sealing line D and a blunt end face E. The closing element B is thus in the form of a frusto-conical enlarged needle end, and allows a com bination with the valve seat A. created symmetric conical spray pattern of a fuel fluid in a combustion chamber.

5 shows the view of the frustoconical needle end in the direction of fuel flow which is marked by arrows.

In the cross-sectional representation of 6 with valve seat A according to, for example 3 is the rotationally symmetric fit of the closing element B from 4 in the nozzle body house 3 to recognize. The side G of the closing element B is therefore at the valve seat A with the valve closed. The inner wall L forms the base of the valve seat.

The extension of the needle C upwards and the needle shaft C 'itself are concentric with the lower valve line D. This general geometric condition is determined by the 7 shown. The concentric layers of surfaces E and F are clearly visible. The sealing line of the valve seat A thus coincides with the outer edge of the closing element B.

It The present invention is based on the object, an injection nozzle and a Injection method especially for non-central to a combustion chamber Specify arranged injector positions, which is an optimal combustion performance with increased efficiency guaranteed and a method for producing such an injection nozzle.

The Task is with regard to the injection nozzle, the manufacturing process the injector and of the injection method by the features of the respective independent claims.

• – ein asymmetrischer Raum zwischen dem Nadelende B und dem Ventilsitz A derart bereitgestellt ist, dass die Form des Nadelendes B nur in einem Teilbereich der gesamten Form des Ventilsitzes A folgt,
• – der asymmetrische Raum stromaufwärts oberhalb der Dichtlinie oder Dichtfläche positioniert ist,
• – der Bereich des asymmetrischen Raums gegenüber dem symmetrischen Raum ein vergrößertes Volumen aufweist und somit als Androsselungsbereich J für ein Fluid dient,

wobei das asymmetrische Strahlbild des erzeugten Einspritzstrahls vom asymmetrischen Raum und von den durch den asymmetrischen Raum erzeugten asymmetrischen Druckverhältnissen abhängig ist.The injector with outwardly opening valve according to the invention comprises a nozzle body H with a cavity whose inner wall L is formed in a region as a valve seat A and a guided through the cavity needle C with the needle end B of the needle C seated in an end position on the valve A presses and thus a suitable for a fluid closed sealing surface F 'between the nozzle body and the needle can be generated,
in which

• An asymmetrical space is provided between the needle end B and the valve seat A such that the shape of the needle end B follows only in a partial region of the entire shape of the valve seat A,
• The asymmetrical space is positioned upstream above the sealing line or sealing surface,
• The area of the asymmetrical space has an enlarged volume in relation to the symmetrical space and thus serves as a throttling area J for a fluid,

wherein the asymmetric beam pattern of the generated injection beam is from the asymmetric space and from the asymmetric space generated asymmetric pressure conditions.

The Invention uses an asymmetrical beam path of an injection fluid to achieve an optimal combustion process. Instead of an unbalanced one To suppress the beam path Instead, the unbalanced beam path is cultivated.

• – ein asymmetrischer Strahlengang gewährleistet eine optimale Eindringcharakteristik eines Einspritzfluids für ein Brennverfahren mit einer dezentralen Einspritzdüsenposition
• – da die Dichtfläche zwischen Nadelende und Ventilsitz auch weiterhin rotationssymmetrisch ausgebildet werden kann, ist es möglich, unter Verwendung herkömmlicher Herstellungsverfahren wie Drehen und Schleifen weiterhin den Düsenkörper herzustellen
• – da die Herstellung der Nadel in einem separaten Arbeitsvorgang erfolgt, kann dieser Vorgang problemlos ausgenutzt werden, um das Nadelende asymmetrisch herzustellen.

The injection nozzle offers the following advantages:

• An asymmetric beam path ensures optimum penetration characteristics of an injection fluid for a combustion process with a decentralized injection nozzle position
• - Since the sealing surface between the needle end and valve seat can continue to be rotationally symmetrical, it is possible to continue to produce the nozzle body using conventional manufacturing processes such as turning and grinding
• - Since the production of the needle is done in a separate operation, this process can be easily used to produce the needle end asymmetrically.

at the preparation according to the invention the injector becomes the inner wall L of the nozzle body H provided with a valve seat A and an asymmetric material removal M, M 'of the valve seat executed in a subarea and / or at a needle end B which is insertable into the injection nozzle a material decrease M, M 'in a subarea executed. Thus, between the needle end and the valve seat is an asymmetric Room J "provided.

It alone the material of the valve seat can be ground in a partial area be ground or the material of the needle end in a partial area become. In this case, at least between the needle end and the valve seat a sealing line D when pressed be assured of the needle end on the valve seat.

At the Injection method for an injection nozzle becomes an asymmetrical beam path of an injection fluid thereby produces that upon removal of a needle end B from a valve seat A generates an annular gap between the needle end and the valve seat A. so that the pressure gradient generated thereby the injection fluid through the above-described asymmetric space between the needle end and the valve seat and finally flow through the annular gap leaves. Under "annular gap" is the space between the periphery of the needle end at the height of its maximum diameter and the area of the valve seat on the said periphery of the needle end presses, Understood. In particular, by the expanded space J between the needle end and the valve seat at a throttling of the fluid flow at open valve generated. The asymmetric space through the space expansion J thus leads to asymmetric pressure conditions the injection fluid at the annular gap and therefore to the asymmetric Shape of the beam path of the injection fluid.

Especially in engines where the injector a non-central Location opposite the combustion chamber axis has an asymmetric jet pattern of particular Advantage, since they compensate for the decentralized position of the nozzle at least partially can achieve a more homogeneous mixture preparation while avoiding "Piston Wetting".

The Invention will be explained in more detail with reference to the following embodiments. It shows

8th Displacement of an end face of a needle end relative to the needle axis

9 Needle end after 8th in three-dimensional view with offset

10 Needle end after 9 which is introduced in a nozzle body

11 Variant of a sheared needle end

12 Needle end after 11 in a corresponding nozzle body

13 Needle end with an elliptically abraded portion

14 Variant of a needle end after 13

15 Needle end with a 2/3 ground area

16 Side view of the needle end behind 15

17 one after the 11 to 14 trained needle end, inserted in a symmetrical valve seat

18 the inventive injection method with asymmetrical injection jet

8th to 12 refer to an embodiment of the invention, where a frusto-conical guided by a nozzle body, serving as a closing element needle end sheared is. In all embodiments, the needle end should basically have a flared end for creating a sealing surface F between the valve seat and the needle end. The position of the sealing surface F is determined by the range of the maximum diameter of the expanded needle end. In the following embodiments, this is the height or the sealing surface F.

8th shows a sheared geometry, where an upper, aligned transversely to the needle axis end face E 'and a lower cross-sectional area F' non-concentric. By shifting dx of the upper and lower circles E 'in its plane, a sheared truncated cone shape is achieved. The asymmetry caused by the displacement dx determines the steepest angle α occurring in the truncated cone, which at the same time is responsible for the spray pattern after leaving the sealing surface F of the injected fuel. Nevertheless, there is a mounting condition that the axis of the needle C is at least concentric with the lower circle F '.

The three-dimensional view 9 shows the offset by dx between the needle axis C and the truncated cone shape B '.

10 shows the sheared needle end B 'on a valve seat A, wherein with the valve open or with the needle C depressed, a deflated area K with a narrow flow volume and a choked area J above the line D arise and can be seen. The throttled area J is due to the asymmetry of the needle end B 'as a larger volume space between the needle end B' and the inner wall L of the nozzle body H. The Entschrosselte area K, however, shows a smaller space between the needle end B 'and the inner wall L of Nozzle body H. The space created by both rooms of different volume around the needle end B 'thus has an asymmetric characteristic. Generally, in this sheared design of the needle end, the inclination of the surface of the needle end from the sealing surface F to the needle axis will have a variation such that, for example, in the throttled region, the angle α will be smaller than the angle in the de-throttled region K.

11 shows a variant with a steep truncated cone shape B '', ie with a small radius difference between the upper and lower circles E '' and F '', or with a larger angle α and with a smaller offset dx compared to the previous example.

12 shows a nozzle body H 'whose inner wall L' is formed such that a space J 'of selectable volume between the truncated cone shape B''and the inner wall L' of the nozzle body is given. This space J 'is still used for throttling the fuel flow according to 10 , The nozzle body H 'of this figure is in particular for a Nadelendenform B''according to 11 suitable.

The Production of a sheared needle end can be achieved by welding the Needle end to the needle shaft or by suitable material removal of Needling done.

One inventive manufacturing method for a nozzle body with a corresponding needle end is that the needle end B or B 'and the valve seat A symmetrical, ie unskilled, made and then material of selectable magnitude above a sealing edge D of the needle end is taken to a general To achieve deepening of the needle end. Alternatively, instead of of the needle end B or B 'the Inner wall L or L 'des Nozzle body H, or the valve seat A removed from material or abraded are to provide a throttled zone, the remaining a circular one Sealing edge D is essential.

13 shows a truncated cone shape B which has a portion M of removed material. Similar shows 14 a truncated cone shape B which has a portion M 'removed material. The form of material removal is immaterial, it being preferred to select shapes that are easy to incorporate with a cutter of suitable size, such as a spherical or elliptical shape, the latter form can be achieved for example by multiple material removal. In principle, however, the shape of the material removal can be designed as desired, ie in accordance with the respective requirements of the beam profile. Among others, the method of spark erosion is suitable for the production of these forms. The material removal takes place above a sealing surface F relative to the fuel flow direction, it does not matter if the sealing surface F is part of the valve seat or part of the needle end. In the removal areas M and M 'comes when using the nozzle body for throttling the fluid flow. Larger choked areas are easily generated with a milling cutter and a 3D traversing table. In 15 If 2/3 of the total area of the truncated cone shape B is throttled (area N1), however, the area N2 of 1/3 size is throttled. It is essential here, too, that a sealing edge or sealing surface F remains. A side view of this device offers 16 ,

The insertion of the needle end into a nozzle body is in 17 shown, wherein a de-throttled area J "according to the in 11 to 14 formed Materialabnehmungen M, M 'or N1 is formed.

The asymmetric injection method according to the invention is described in 18 shown. The method is particularly suitable for a combustion chamber BK, in which the nozzle body is positioned as part of an injector laterally of the cylinder axis. The method thus causes a flat, parallel to the piston surface P contact of the injection jet on the piston P. An early wetting of the piston with fuel is thereby avoided.

The injection nozzle according to the independent claim and the above embodiments or the 8th to 17 is regarding the 18 to understand that the side of the injector or needle end, the shorter side 1'a the beam profile 1' leads, for example, according to the areas M, M 'or J has a throttled area. In contrast, the longer side 1'b the beam profile 1' through a derenched region according to N2 ( 15 ) or K ( 10 ) can be generated. The throttling of the fluid flow thus leads, for example, to cover a distance 1'a to the piston P, in their time a longer distance 1'b is returned to the piston through the de-throttled fluid flow. Due to this asymmetry is schematically a beam profile 1' which is not isosceles within a certain period Δt considered differential. There is also the advantage that at a low density, for example, in a Ansaugverfahren the piston, where in principle a deeper penetration of the fluid is achieved through the throttled side 1'a the beam profile 1' no early contact of the injection fluid with the piston surface is caused.

The Injection method is basically not limited to a special form of injection jet but rather, with all types of poppet valves with or without a downstream one Element of a needle for shaping the injection jet, e.g. Baffle plate, Strahlablenkwulst, applicable, provided that only upstream the valve seat he testified rotation angle-dependent supply and Entdrosselung and thereby caused by rotation angle-dependent volume flow density the possibly downstream beam-shaping element with respect to Rotation angle is not completely again is homogenized or balanced.

Claims (9)

injection with outward opening Valve comprising a nozzle body (H) with a cavity whose inner wall (L) in an area as a valve seat (A) is formed, and a guided through the cavity needle (C), wherein the needle end (B) of the needle (C) in an end position Press on the valve seat (A) and thus one for a fluid suitable closed sealing surface (F ') between the nozzle body and the needle generated is in which - one asymmetric space between the needle end (B) and the valve seat (A) is provided such that the shape of the needle end (B) only in a partial area of the entire shape of the valve seat (A) follows - of the asymmetric space upstream is positioned above the sealing line or sealing surface, - the area opposite to the asymmetrical space the symmetrical space an enlarged volume and thus as a throttling region (J) for a fluid serves, wherein the asymmetrical jet pattern of the generated injection jet from the asymmetrical space and from the asymmetric space generated asymmetric pressure conditions. injection according to claim 1, characterized in that the needle end a has expanded area. injection according to one of the claims 1 or 2, characterized in that the needle end has a truncated cone shape is. injection according to any preceding claim, characterized in that the asymmetrical space through a depression (M, M ') in the end of the needle is formed. injection according to one of the preceding claims 2 to 4, characterized in that formed the needle end sheared relative to the needle axis is that the inclination of the surface of the needle end from the sealing surface to the needle axis has a variation. injection according to claim 5, characterized in that the needle end a Face across to the needle axis, whose center is not on the needle axis lies. Method for producing an injection nozzle according to the claims 1 to 6, wherein the inner wall L of a nozzle body with a valve seat A is provided and an asymmetric material removal (M, M ') of the valve seat (A) executed in one area is and / or at a needle end (B), which is insertable into the injection nozzle, a material decrease is carried out in an area and thus between the needle end (B) and the valve seat (A) an asymmetric space provided. Injection method for an injector, wherein upon removal of a needle end (B) from a valve seat (A), an injection fluid flows through an asymmetric space between the needle end (B) and the valve seat (A) resulting in asymmetric pressure ratios of the fluid between the valve seat (A). A) and the needle end (B) leads and thus an asymmetric S beam profile ( 1' ) of an injection fluid is produced. An injection method according to claim 8, wherein in a expanded space (J) of the asymmetric space between the needle end (B) and the valve seat (A), a throttling of the injection fluid takes place and in a narrower space (K) of the asymmetric space one Entdrosselung the injection fluid takes place.