DE10254681A1 - Injection nozzle, especially for gasoline engines, has asymmetrical space between valve needle end, valve seat so shape of needle end only follows shape of valve seat in sub-region - Google Patents

Abstract

The nozzle has a nozzle body (H) with a hollow chamber whose inner wall (L) is formed into a valve seat (A) in one region and a needle (C) for insertion into the hollow volume whose end (B) rests on the valve seat in an end position to make a seal (F'). An asymmetrical space between the needle end and the valve seat is provided so that the shape of the needle end only follows the shape of the valve seat in a sub-region AN Independent claim is also included for the following: (a) a method of manufacturing an inventive injection nozzle (b) and a method of injection for an injection nozzle.

Description

The invention relates to an injection nozzle and a Injection process, especially for gasoline engines.

An optimal mixture preparation of a fuel and stability a combustion process in a cylinder of a motor vehicle usually advance that in terms of the amount injected and the beam cone angle as possible rotationally symmetrical fuel cone jet leads into the combustion chamber. It is a beam-guided combustion process, too Stratified charge operation called, where possible in time late in Compression cycle is injected and the injector centrally in the combustion chamber roof (collinear to the cylinder axis) between the intake and exhaust valves is positioned. The requirement can be explained from the installation position a rotationally symmetrical cone beam, otherwise in the case of a asymmetrical cone beam of the injector in the angular direction relative to the position of the spark plug would have to be installed precisely aligned.

The call for one among all compression pressures typical of the engine have a stable beam cone angle to get comes from the need for the spark plug at the time of ignition from a stoichiometric composite cloud of air and fuel got to. This takes place, for example, from a second, later injection a lean mixture of the stratified charge, for example by a first one 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 5 to 10 times at high compression pressure denser medium, with the penetration depth decreasing significantly and due to the central position of the injector in the combustion chamber roof a cylinder wall wetting is avoided.

The above procedures are each based on the 1 shown. The injection valve or injector 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 mode, whereby the piston P effects a compression within the combustion chamber BK and a late ignition in the compression cycle is triggered by the spark plug SP. The figure on the right shows a homogeneous gas-air Mixing preparation 1 the injection fluid is symmetrically conical.

In a Formula 1 engine, on the other hand, the injector is installed in the central position, in 1 marked with the dashed line, not possible in the combustion chamber roof due to the overall cylinder head structure, so that the installation must be moved to a decentralized location away from the cylinder axis. In addition, the Formula 1 engine is operated with a homogeneously prepared air-fuel mixture. For racing engines, it is common to carry out an early injection in the intake and at the beginning of the compression cycle in order to ensure optimal mixture formation. At an early injection point, the pressure in the cylinder 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 is deep. The shape of the injection jet during this process is shown in 2 shown. It is clearly visible that the deep penetration of the injection jet and one side of the jet profile 1 Even before ignition, piston P hits 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 Eine Zylinderwandbenetzung mit Kraftstoff sollte aber unbedingt vermieden werden da
• – Der an der Wand niedergeschlagener 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 neidergeschlagener Kraftstoff wird durch die Kolbenringe des Zylinders nicht vollständig abgestriffen 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.

There is therefore wall wetting with fuel in the homogeneously operated Formula 1 engine, in particular for the following reasons:

• - due to the non-taxial installation position of the injector
• - by injecting the fuel into a gas with a low density which leads to excessive penetration. Wetting the cylinder wall with fuel should be avoided, however
• - The fuel deposited on the wall does not evaporate at a sufficient speed to be burned in the following combustion cycle. An incorrect dosage and a drop in performance that results in poor driveability or "driveability" result.
• - The fuel jammed on the wall is not completely stripped off by the piston rings of the cylinder and affects the piston lubrication, which can lead to greater wear between the inner wall of the cylinder and the piston and, in the worst case, to a piston seizing effect or etching effect of the piston
• - The fuel gets into the lubricating oil circuit and endangers the lubrication of other internal engine units, which can lead to their damage and failure
• - The fuel on the inner wall of the cylinder and on the piston rings carbonized due to the heat of combustion. This affects the sealing function of the piston rings. This results in a loss of compression and a loss of engine power.

A common geometry of an injector of an injector is based on the 3 to 6 shown. The fluid injection is typically carried out in the form of a cone jet.

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

4 shows a truncated cone-shaped closing element B with a needle C, a symmetrical side G with a steep angle, a sealing line F and a blunt end face E. The closing element B is thus in the form of a truncated cone-shaped he further needle end, and enables one in combination with the valve seat A. generated a symmetrical conical spray pattern of a fuel fluid into a combustion chamber.

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

In the cross-sectional representation of the 6 with valve seat A according to example 3 is the rotationally symmetrical fit of the closing element B. 4 in the nozzle body house 3 to recognize. The side G of the closing element B thus bears against the valve seat A when the valve is closed. The inner wall L forms the basis of the valve seat.

The extension of the needle C upwards and the needle shaft C 'itself are concentric to the lower valve sealing line F. This general geometrical condition is explained by the 7 shown. The concentric positions 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 is the present invention based on the task of an injection nozzle and an injection method especially for injector positions not centrally located on a combustion chamber indicate what an optimal burning performance with increased efficiency guaranteed.

The task is regarding injector, the manufacturing process of the injector and the injection process solved 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 die gesamte die Form des Ventilsitzes A folgt
• – der asymmetrischer Raum stromaufwärts oberhalb der Dichtfläche F' positioniert ist
• – ein Bereich des asymmetrischen Raums einen vergrößerten Volumen aufweist und somit als Drosselungsbereich J für ein Fluid dient
• – die Stärke eines an und nach der Dichtfläche F erzeugten Einspritzstrahls in einen Brennraum vom asymmetrischen Raum und von den durch den asymmetrischen Raum erzeugten asymmetrischen Druckverhältnissen abhängig ist.

The injection nozzle according to the invention comprises a nozzle body H whose inner wall L is formed in a region as a valve seat A and a needle C which can be inserted into the cavity of the nozzle body, the needle end B of the needle C pressing against the valve seat A in an end position and thus for one A fluid suitable closed sealing surface F 'can be produced between the nozzle body H and the needle end B, wherein:

• - An asymmetrical space between the needle end B and the valve seat A is provided such that the shape of the needle end B follows the shape of the valve seat A only in a partial area
• - The asymmetrical space is positioned upstream above the sealing surface F '
• - An area of the asymmetrical space has an increased volume and thus serves as a throttling area J for a fluid
• - The strength of an injection jet generated on and after the sealing surface F in a combustion chamber is dependent on the asymmetrical space and on the asymmetrical pressure conditions generated by the asymmetrical space.

The invention uses an asymmetrical beam path of an injection fluid in order to achieve an optimal combustion process. Instead of suppressing an asymmetrical beam path, instead the asymmetrical beam path 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 has the following advantages:

• - An asymmetrical beam path ensures an optimal penetration characteristic of an injection fluid for a combustion process with a decentralized injector position
• - Since the sealing surface between the needle end and the valve seat can still be made rotationally symmetrical, it is possible to continue to manufacture the nozzle body using conventional manufacturing methods such as turning and grinding
• - Since the manufacture of the needle takes place in a separate work process, this process can be used without any problems in order to produce the needle end asymmetrically.

In the production according to the invention the injector the inner wall L of the nozzle body H provided with a valve seat A and an asymmetrical material take-off M, M 'of the valve seat executed in a partial area and / or at a needle end B which can be inserted into the injection nozzle a decrease in material M, M 'in a section. Thus, an asymmetrical between the needle end and the valve seat Room J '' provided.

It can be the material of the valve seat alone a section or the material of the needle end be sanded in a partial area. It must be between the Needle end and the valve seat at least one sealing line F when pressing the End of the needle on the valve seat.

In the injection method for an injection nozzle, an asymmetrical beam path of an injection fluid is generated in that when a needle end B is removed from a valve seat A, an annular gap is generated between the needle end and the valve seat A, so that the pressure gradient generated thereby causes the injection fluid to flow through the asymmetrical space described above Let the needle end and the valve seat and finally flow through the annular gap. The “annular gap” is understood to mean the space between the periphery of the needle end at the height of its maximum diameter and the region of the valve seat against which the said periphery of the needle end presses. In particular, the widened space J between the needle end and the valve seat means that the Fluid flow generated with the valve open. The asymmetrical space through the Expansion of space J thus leads to asymmetrical pressure ratios of the injection fluid at the annular gap and consequently to the asymmetrical shape of the beam path of the injection fluid.

Especially in engines where the injector is a non-central location opposite the combustion chamber axis has an asymmetrical spray pattern Advantage, as they at least partially compensate for the decentralized position of the nozzle can achieve a more homogeneous mixture preparation while “Piston To avoid wetting ".

The invention is based on the following embodiments explained in more detail. 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 inserted 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 ground section

14 Variant of a needle end after 13

15 Needle end with a 2/3 ground area

16 Side view of the needle end after 15

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

18 the inventive injection method with an asymmetrical injection jet

8th to 12 relate to an embodiment of the invention, where a truncated cone-shaped needle end, which is guided by a nozzle body and serves as a closing element, is sheared. In all exemplary embodiments, the needle end should basically have a widened end for producing a sealing surface F between the valve seat and the needle end. The position of the sealing surface F is determined by the area of the maximum diameter of the expanded needle end. In the following exemplary embodiments, this is the height or the sealing surface F.

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

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

10 shows the sheared needle end B 'on a valve seat A, an unthrottled area K with a narrow flow volume and a throttled area J above line F' being formed and recognizable when the valve is open or the needle C is pressed down. The throttled area J results from 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 dethrottled area K, on the other hand, shows a smaller space between the needle end B 'and the inner wall L des Nozzle body H. The space created by the two rooms of different volume around the needle end B 'thus has an asymmetrical characteristic. In general, with 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 vary so that, for example, the angle α is smaller in the throttled area than the angle in the unthrottled area K.

11 shows a variant with a steep truncated cone shape B '', i.e. 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 designed such that a space J 'of selectable volume is given between the frustoconical shape B''and the inner wall L' of the nozzle body. This space J 'still serves to throttle the fuel flow in accordance with 10 , The nozzle body H 'of this figure is in particular for a needle end shape B''according to 11 suitable.

The production of a sheared The end of the needle can be welded on of the needle end to the needle shaft or by suitable material removal of the Needle end.

An inventive manufacturing process for a Nozzle body with corresponding needle end is that the needle end B or B 'and the valve seat A symmetrical, i.e. unsheared, and then material selectable extent above a sealing edge F of the needle end is removed to a general To reach deepening of the needle end. Alternatively, instead of of the needle end B or B ' Inner wall L or L 'of Nozzle body H, or the Ven tilsitzes A removed or sanded off material to provide a choked zone, the remaining a circular Sealing edge F is essential.

13 shows a truncated cone shape B which has a region M of removed material. Similar shows 14 a truncated cone shape B which has a region M 'of removed material. The shape of the material removal is immaterial, it being preferred to select shapes that are easy to incorporate with a milling cutter of a suitable size, such as a spherical or elliptical shape, the latter shape being able to 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 for the beam profile. The process of spark erosion is suitable for producing these shapes. The removal of material takes place above a sealing surface F relative to the direction of fuel flow, it being irrelevant whether the sealing surface F is part of the valve seat or part of the needle end. In the removal areas M and M ', when the nozzle body is used, the fluid flow is throttled. Larger throttled areas can easily be created with a milling cutter and a 3D travel table. In 15 2/3 of the total area of truncated cone shape B is throttled (area N1), but area N2 of 1/3 size is dethrottled. It is also essential here 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, a dethrottled region J '' according to the in 11 to 14 shown material removals M, M 'and N1 is formed.

The asymmetrical 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 laterally from the cylinder axis as part of an injector. The method thus brings about a flat contact of the injection jet on the piston P parallel to the piston surface P, thereby avoiding premature wetting of the piston with fuel.

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 injection valve or needle end, the shorter side 1'a of the jet profile 1' leads, has a throttled area, for example according to the areas M, M 'or J. In contrast, the longer side is 1'b of the beam profile 1' through a dethrottled area according to N2 ( 15 ) or K ( 10 ) can be generated. The throttling of the fluid flow thus leads, for example, to the covering of a distance 1'a to the piston P, during which a longer distance 1'b through the dethrottled fluid flow back to the piston. This asymmetry makes a beam profile schematic 1' generated, which is not isosceles within a certain, considered period of time .DELTA.t. There is also the advantage that with a low density, for example in a suction process of the piston, where a deeper penetration of the fluid is generally achieved, through the throttled side 1'a of the jet profile 1' no premature contact of the injection fluid with the piston surface is caused.

The injection process is basically not limited to a special form of an injection jet rather with all types of seat valves with or without a downstream Element of a needle for shaping the injection jet, e.g. Baffle plate, beam deflection bead, applicable, provided only the upstream the throttling and unthrottling generated by the valve seat and thereby caused volume flow density dependent on the angle of rotation the possibly downstream beam shaping element bezüg Lich the Rotation angle not again completely is homogenized or balanced.

Claims (9)

Injection nozzle comprising a nozzle body H with a cavity, the inner wall L of which is formed in a region as a valve seat A and a needle C which can be inserted into the cavity, the needle end B of the needle C pressing against the valve seat A in an end position and thus a closed sealing surface suitable for a fluid F 'can be generated between the nozzle body and the needle, characterized in that - an asymmetrical space is provided between the needle end B and the valve seat A in such a way that the shape of the needle end B follows the entire shape of the valve seat A only in a partial area - the asymmetrical space is positioned upstream above the sealing surface - an area of the asymmetrical space has an increased volume and thus serves as a throttling area J for a fluid - the strength of an injection jet generated on and after the sealing surface from the asymmetrical space and from the asymmetries generated by the asymmetrical space 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 is a truncated cone shape is. injection according to any preceding claim, characterized in that the asymmetrical space by a recess M, M 'in the needle end is formed. Injection nozzle according to one of the preceding claims 2 to 4, characterized in that the needle end relative to the needle axis in this way is designed sheared 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, the center of which is not on the needle axis lies. Method for producing an injection nozzle according to a of claims 1 to 6, in which the inner wall L of a nozzle body with a valve seat A is provided and an asymmetrical material removal M, M 'of the valve seat A executed in one area and / or at a needle end B which can be inserted into the injection nozzle a material acceptance is carried out in one area and thus between an asymmetrical space is provided for the needle end B and the valve seat A. becomes. Injection method for an injection nozzle in which, when a needle end B is removed from a valve seat A, an injection fluid flows through an asymmetrical space between the needle end B and the valve seat A, which leads to asymmetrical pressure ratios of the fluid between the valve seat A and the needle end B and thus an asymmetrical one beam profile 1' of an injection fluid is generated. Injection method according to claim 8, in which in a widened space J of the asymmetrical space between the needle end B and the valve seat A, the injection fluid is throttled and dethrottling in a narrower space K of the asymmetrical space of the injection fluid takes place.