DE102006011721A1 - Injector for controlled injection of a gaseous fuel stream into a predetermined combustion zone and associated method for controlled injection - Google Patents

Abstract

Along the exit-side end portion of the nozzle channel (NC1) of an injector (IN1) for gaseous fuels (GA) is from the outer wall contour section the axially movable injector needle (NE1) of the injector (IN1) and from the inner wall contour section of the injector housing (CAS1) an outlet nozzle (LN1) for the gaseous Fuel flow (GA) formed, which has a converging inflow passage section (CV1) and a subsequent downstream, divergent outflow channel section (DV1).

Description

at Fuel-burning engines operating on the gasoline engine principle, can liquid or gaseous Fuels are burned. liquid Fuels were earlier volatilized in a carburetor and are now mostly in the channel of a suction pipe before the inlet or injection valve of the respective cylinder of the internal combustion engine injected. This fuel injection into the intake manifold is referred to as so-called port injection. An alternative to the port injection is the direct injection of the fuel into the combustion chamber of the respective cylinder. The direct injection allows other combustion processes, in particular the so-called fuel stratification. This allows a throttle-free load control, reducing the efficiency of the thermal Fuel combustion process in the respective cylinder of the internal combustion engine can be increased, since pumping losses are eliminated or reduced become.

at The fuel stratification becomes a good combustible fuel / air mixture only locally nearby the spark plug generated in the combustion chamber of the respective cylinder while in other parts of the combustion chamber of the combustion chamber, the intake air only serves as an inert gas. The fuel stratification is at liquid fuels with the help of a finely atomized Mixture cloud causes. The goal is to make the mixture cloud in one narrow time window in the combustion chamber to deposit so that the the time from injection to ignition to evaporation the liquid Kraftstofftröpfen sufficient in the mixture cloud and on the other hand a global mixing the fresh air with the fuel is avoided as possible. The Penetration depth of the liquid Fuel in the interior of the combustion chamber into it from the momentum of the injected fuel droplets as well as from the boundary conditions in the combustion chamber. The used for it Injectors with liquid Fuels operating on the diesel principle usually have the form of multi-hole nozzles. Because a self-ignition of the fuel at a given, present temperature in Contact with oxygen is a prior mixing not mandatory. The combustion is in this case mixture-controlled. at spark ignition As in the gasoline engine, a combustible mixture cloud is required at the ignition point. This requires local mixing of liquid fuel and charge air.

Such injectors for liquid fuels are usually designed so that a so-called cavitation, ie gas bubble formation, is largely avoided when injecting or injecting the liquid fuel particles into the combustion chamber. This is the example of the injector US 6,173,912 B1 provided to reduce the passage cross-section of the nozzle channel of the injector in the direction of the outlet opening. In the injection of gaseous fuels, however, this cavitation problem does not occur because there is no phase transition from the liquid state to the gaseous state as with injected liquid fuel particles.

Compared to liquid fuels deleted at gaseous Fuels the time limit of evaporation. Here is already the achievement of a good combustible air / fuel mixture near the spark plug sufficient in the combustion chamber of the respective cylinder. For this is a local mix of sunken, fresh air taken in or in general terms of an exothermic combustion reaction incoming gas with the gaseous Fuel in the area of the spark plug required. Exactly this is however in practice more difficult, since the penetration depth gaseous Fuel particles during injection by injector at the same exit velocity in comparison to liquid Fuel particle is lower. Because of the lower density gaseous Fuel particles compared to liquid fuel particles can the gaseous Fuel particles only a lesser pulse at the same Exit velocity from the injector are given.

The object of the invention is to provide an injector for the controlled injection of gaseous fuel particles into a predetermined, locally limited combustion zone in a combustion chamber filled with air or with another exothermically reacting charge gas. This object is achieved with the aid of the following injector according to the invention:
Injector for the controlled injection of a gaseous fuel flow in a predetermined combustion zone in a combustion chamber of an internal combustion engine through a nozzle channel between its arranged inside, Axialhubbeweglich mounted Injektornadel and the inner wall of its outer injector housing, along the exit-side end portion of the nozzle channel from there outer wall contour portion of the axially movable Injektornadel and from the inner wall contour section of the injector housing there is formed an outlet nozzle for the gaseous fuel stream, which has a converging inflow channel section and a downstream, diverging outflow channel section.

Due to this geometry, a supersonic flow can be advantageously achieved at the injector outlet generate power. Due to the combination of converging inflow channel section and adjoining downstream, diverging outflow channel section of the outlet nozzle of the injector, the gaseous fuel particles can thus be injected or blown into the interior of the combustion chamber at such a high speed that the fuel quickly reaches the vicinity of the spark plug, without mixing by diffusion with the entire charge air. In particular, with the aid of the cross-sectional geometry of the converging inflow passage section and the outflow passage section of the exit nozzle downstream therefrom, the internal energy of the gaseous fuel particles can be efficiently converted into an increase in impulse and concomitantly into a higher penetration speed in the supersonic range. This is advantageously accompanied by a drop in temperature of the injected gaseous fuel particles. A lowering of the charge air temperature advantageously allows an extension of the ignition window with regard to the knocking behavior. Thus, an improved efficiency of the internal combustion engine is achieved.

There the cross-sectional geometry shape of the outlet nozzle of the injector set flexible by a corresponding Axialhub the Injektornadel leaves, let yourself for one Variety of practical conditions in an advantageous way always such a high pressure difference between the high pressure side of the injector and the internal pressure side of the combustion chamber generate the gaseous fuel particles have a sufficiently high pulse to counter to the filling pressure the combustion chamber to the desired, local combustion zone in sufficient quantity to arrive.

The The invention also relates to a method for the controlled injection of a gaseous Fuel flow in a given combustion zone in a combustion chamber an internal combustion engine through a nozzle channel between an inside arranged, Axialhub- movably mounted Injektornadel and the Interior wall of an exterior arranged injector housing an injector, in particular according to one of the preceding claims is formed by along the exit-side end portion of the nozzle channel from there outer wall contour section the axially movable Injektornadel and from there inner wall contour section of the injector housing an outlet nozzle is formed, through the inflow channel section the gaseous Fuel flow converges and arranged downstream Ausströmkanalabschnitt the gaseous Fuel flow diverges and thereby in the direction of the given Combustion zone is accelerated in the combustion chamber.

other Further developments of the invention are given in the dependent claims.

The Invention and its developments are described below with reference to Drawings closer explained.

It demonstrate:

1 in a schematic and enlarged view of a first embodiment of an injector according to the invention, the injector needle assumes a blocking position,

2 in a schematic and enlarged view of the injector of 1 in an injection position of its injector needle, in order to be able to inject gaseous fuel particles through its outlet nozzle with supersonic acceleration into the interior of a combustion chamber,

3 a schematic representation of an exemplary control of the axial stroke of the injector needle of the injector 1 and 2 by means of an engine control unit, which detects a multiplicity of combustion parameters for the thermal fuel combustion taking place in the combustion chamber and, depending on at least one combustion parameter, adapts the geometry shape of the outlet nozzle of the injector, and

4 in schematic and enlarged view, a second, modified embodiment of an injector according to the invention.

Elements with the same function and mode of action are in the 1 4 each provided with the same reference numerals.

The 1 and 2 each show in a schematic and enlarged longitudinal sectional view of a first injector IN1 according to the inventive design principle for the injection of gaseous fuel particles GA in the interior of a combustion chamber CC of the respective cylinder of a fuel internal combustion engine with supersonic. For example, natural gas (so-called CNG = compressed natural gas) or so-called LPG (liquid-filled petroleum gas) can be used as gaseous fuels. The draw for the sake of clarity, is in the 1 and 2 only one half of the rotationally symmetrical with respect to its central axis constructed injector IN1 shown. The central axis of the injector IN1 is shown in each case dash-dotted lines and designated AX. With regard to this central axis AX, the injector IN1 is thus constructed concentrically in terms of space. It has a substantially cylindrical injector housing CAS1, in the interior of which an injector needle NE1 is accommodated axially symmetrically with respect to the central axis AX and is mounted movably up and down along it in the axial direction.

This axial lifting movement of the Injektornadel IN1 is effected by means of an actuator or actuator AC. The upward movement is symbolized by an arrow US, the downward movement by an arrow DS. The operation, ie the activation in the upward or downward direction, as well as the stop or stopping, the Injektornadel NE1 by means of the actuator AC are in the 1 . 2 each indicated by an action arrow WP1. The actuator AC is connected to an engine control unit ECU via a control line SL1. This transmits via the control line SL1 control signals or control signals SS1 for actuation, ie Axialhubbewegung or to stop the Injektornadel NE1 of the injector IN1.

The injector needle NE1 is accommodated in the injector housing CAS1 with play such that an elongated gap as a nozzle channel NC1 is present between its outer wall and the inner wall of the injector housing CAS1 along its axial longitudinal extent. This nozzle channel NC1 has an overall substantially annular or toroidal cross-sectional shape in a viewing plane of the injector IN1, which is perpendicular to the plane of 1 respectively. 2 and to which the central axis AX forms a surface normal. The Injektornadel NE1 is viewed in longitudinal section in first approach to its end portion, which protrudes from the opening of the receiving chamber of the injector CAS1, anchor-like manner. The 1 shows the Injektornadel NE1 in a blocking position in which it shuts off the nozzle channel NC1 in the region of its outlet-side end portion, ie, the injector IN1 assumes a closed position. The 2 shows the Injektornadel NE1 in an axial stroke position in which the nozzle channel NC1 output side is maximally open. In other words, that means that in this open position of the injector IN1 of 2 the injector needle NE1 is brought into a predetermined injection end position. The injector needle NE1 is actuated by its actuator AC between its Eindüs end position of 2 and their blocking position of 1 in the axial direction according to the cycle of the thermal combustion process in the combustion chamber reciprocally moved to preferably inject into the interior of the combustion chamber CC of the respective cylinder before and / or at its power stroke or compression stroke, the gaseous gas particles in a suitable amount. The combustion chamber CC is in the 1 and 2 the drawing simplicity indicated only by a dot-dashed frame. In particular, it is part of a cylinder of a fuel-burning engine. In the exemplary embodiment, a spark plug IP projects into the combustion chamber CC. The near zone around this spark plug IP defines a local combustion zone CCL, only within which a mixture cloud CL between the injected gaseous fuel particles and aspirated air is desired.

In order to achieve that the gaseous fuel particles in the interior of the combustion chamber CC as concentrated as possible be introduced only in the predetermined combustion zone or ignition zone CCL and thereby a global mixing of the injected gaseous fuel particles with the compressed air in the combustion chamber is largely avoided in the entire combustion chamber space, is formed for the input side into the nozzle channel NC1, gaseous fuel flow GA along the outlet side end portion of the nozzle channel NC1 from there outer wall contour portion of the axially movable Injektornadel NE1 and the local inner wall contour portion of the Injektorgehäuses CAS1 an outlet nozzle LN1, which has a converging inflow passage CV1 and one downstream has subsequent, diverging outflow channel DV1. The converging inflow channel section CV1 has a cross-sectional geometry shape which continuously or continuously tapers in the flow direction, while the divergent outflow channel section DV1, viewed in longitudinal section, continuously widens in the outflow direction. The transition zone or saddle zone NA1 between the exit of the converging inflow passage section CV1 and the entrance of the downstream adjoining divergent outflow passage section DV1 is in the open injection position of the injector needle NE1 of FIG 2 denoted NA1. In this transitional zone, the exit nozzle LN1 has a minimum passage cross-sectional area. In particular, their passage cross-sectional area is substantially constant there.

In this way, the outlet-side outer wall contour section of the injector needle NE1 forms such a movable inner wall contour section for the outlet nozzle LN1 that its flow cross-sectional geometry is variable over its flow length when the injector needle NE1 changes from its blocking position into a predeterminable injection position. In particular, due to the axial stroke movement of the injector needle NE1, the flow cross-sectional geometry of the outlet nozzle can be at least flexibly adapt an existing combustion parameter that is relevant to the thermal combustion process in the combustion chamber. These include, in particular, the fuel pressure in the nozzle channel CE1 before its outlet nozzle LN1, the combustion chamber pressure in the combustion chamber CC, and / or the fuel quantity of gaseous fuel particles GA to be injected into the combustion zone CCL.

By be arranged in advance, the converging inflow passage portion CV1 the gaseous Fuel particle GA accelerates and their speed against their Speed upstream of the inlet into the converging inflow passage section elevated. Due to the combination of this converging inflow passage section with the downstream subsequent, diverging Kanalausströmkanalabschnitt it is particular allows that from the outlet OP of the outlet nozzle LN1 exhausted or blown gaseous Fuel flow JS Sound or supersonic speed reached. to Generation of a supersonic flow for the gaseous fuel particles is along the exit-side end portion of the nozzle channel NC1 through the outer wall contour section the axially movable Injektornadel NE1 and through the inner wall contour portion of the injector housing CAS1 expediently a Laval nozzle as outlet nozzle LN1 formed. Here, the cross-sectional geometry shape of the convergent Einströmkanalabschnitts CV1 and at the same time the divergent outflow channel DV1 this Laval nozzle through the axial stroke of the Injektornadel NE1 and the associated change of position its outer wall contour adjustable or flexibly adjustable.

On this way it is possible the gaseous Fuel particles GA with such a high penetration rate Sound, in particular supersonic speed, at the exit from the outlet nozzle Indicate that LN1 their penetration into the space of the combustion chamber sufficient in sufficient number to the given local Combustion zone CCL inside the combustion chamber CC to achieve. Their penetration rate is so high that their momentum bigger than that Counterpulse of the sucked, compressed air in the combustion chamber CC is.

In lavaldüsenartiger cross-sectional geometry of the outlet nozzle LN1 arise for the gaseous fuel flow GA following flow conditions with regard to its velocity profile and pressure curve:

there M is the Mach number M = c / a with c as gas velocity and with a as the speed of sound at the inlet of the Laval nozzle. A is the passage area at the respective location of the longitudinal extent the Laval nozzle.

• 1.) für Unterschallströmung mit M < 1, dass dA/A < 0 sein muss, sich die Düse also verengen muss,
• 2.) für Überschallströmung mit M > 1, dass dA/A > 0 sein muss, sich die Düse also erweitern muss, und
• 3.) für Schallströmung mit M = 1, dass die Düse einen konstanten Durchlassquerschnitt aufweisen muss.

Assuming A (x) as given, c (x) and M (x) as unknown, the relation (1) allows a qualitative discussion of the flow in the nozzle. If a flow is to be accelerated, ie dc / c> 0, then it follows from the formula (1):

• 1.) for subsonic flow with M <1, that dA / A <0 must be, so the nozzle must be narrowed,
• 2.) for supersonic flow with M> 1, that dA / A> 0 must be, so the nozzle must expand, and
• 3.) for sound flow with M = 1, that the nozzle must have a constant passage cross-section.

from that follows the geometry of the Laval nozzle. In her converging Einströmkanalabschnitt becomes the subsonic flow the gaseous Fuel particles accelerated. At the narrowest cross-section, that is in the transition area NA1 between the inflow passage section Reach CV1 and the following divergent outflow channel section DV1 the gaseous Fuel particle GA speed of sound, that is, there is approximately M = 1. In the diverging outflow channel section DV1 become the gaseous ones Fuel particles GA finally accelerated further and finally reach supersonic speed, i. where M> 1.

With the aid of the laval nozzle-like geometry of the outlet nozzle LN1 and a sufficient pressure gradient between the injector interior and the combustion chamber, a supersonic flow JS can thus be generated at the injector outlet, ie at the outlet opening OP of the injector IN1. Due to the higher flow rate of the gaseous fuel particles after exiting the outlet nozzle LN1 compared to conventional injectors, the gaseous fuel particles can reach the predetermined combustion zone CCL in the vicinity of the spark plug IP improved and only there generate a good combustible fuel-air mixture cloud CL. Their penetration depth is thus increased in relation to the conditions in a purely convergent nozzle. With the aid of the outlet nozzle LN1, it is possible to achieve a sufficiently high pressure difference between the injector interior and the combustion chamber for blowing in the gaseous fuel particles directed to provide the predetermined combustion zone CCL. A flow JS at the speed of sound or supersonic velocity at the injector outlet can then occur when the ratio between the pressure in the injector and the pressure in the combustion chamber is equal to or greater than the critical pressure ratio of the Laval nozzle. The critical compression ratio of the Laval nozzle depends on the isotropic constant of the gaseous fuel used. For a supersonic flow at the injector outlet in particular a cross-sectional geometry corresponding to the outlet nozzle LN1 of 1 and 2 expedient, in which the flow cross-section initially tapers. This increases the velocity of the gaseous fuel particles GA with respect to their velocity in the preceding nozzle channel NC1. Due to the cross-sectional reduction in the downstream downstream, converging inflow passage section CV1, there is an increase in the speed of the gaseous fuel particles GA to supersonic because their mass flow rate must remain the same. For what flows into the converging inflow channel section CV1 at the front must also come out at the back (continuity theorem). However, since the density of the gaseous fuel stream increases considerably at high speeds in the Mach range of M = 1, gas particles increasingly move closer to the throat NA1 and impart an even stronger impulse to the upstream gas particles so that they finally accelerate to supersonic in the diverging channel outflow section DV1 become. As a result of the cross-sectional widening in the diverging outflow channel section DV1, at supercritical pressure conditions, a further acceleration is thus preferably carried out to a multiple speed of sound as a function of the respective geometry guide.

In the outward opening injector IN1 the 1 and 2 a part of the laval-shaped discharge nozzle LN1 is formed through the injector housing CAS1 and the other part through the injector needle NE1. In order to obtain a sufficient penetration depth even with the smallest amounts of fuel gas, it is expedient that already at the smallest possible opening needle stroke already creates a favorable outlet nozzle geometry. This can be achieved in the outwardly opening injector IN1 in that the sealing surface SR1 is retracted between the injector housing CAS1 and the injector needle NE1 into the injector interior and is not provided on the outer surface of the injector housing. In this case, in the case of the injector needle NE1, downstream of this, a gap GA is formed between the sealing surface SR1 (see FIG 1 ) and the injector exit opening OP. In other words, this means that in the blocking position of the injector needle NE1, the annular sealing surface SR1 in the region of the saddle zone of the Laval nozzle is set back relative to its end-side outlet opening OP upstream in the nozzle channel NC1.

For the practice it is particularly appropriate that Injector needle and the injector housing along an exit side End section of her nozzle channel to shape and to dimension such that the cross section of the Annular gaps or nozzle channels between the outer wall the Injektornadel and the inner wall of the injector after Outside grows so steadily that when open Injector needle the perfused cross section larger at the exit point OP, in particular twice larger than which flowed through Cross sectional area in the area of the sealing surface at the narrowest point or rejuvenation point, i.e. Saddle is. At this minimum aspect ratio is the axial needle stroke adjusted in an advantageous manner.

in the divergent exit channel section DV1, the gaseous fuel particles finally expand, whereby their internal energy is converted into kinetic energy.

There up to the outlet OP is the cross-sectional area in the diverging outflow channel section DV1 will be enlarged the gaseous Fuel particles in the interior of the combustion chamber towards the desired Combustion zone in particular injected at supersonic velocity.

The 3 schematically illustrates how the engine control unit ECU as input variables various combustion parameters that are relevant for the thermal combustion process in the combustion chamber, detected and used to control or control the axial stroke of the injector needle of the respective injector. Here in the embodiment of 3 receives the engine control unit ECU as input signals, for example, the fuel pressure (P_Injektor) in the nozzle channel NC1 in front of the end-side outlet nozzle LN1. This input signal is designated PI. The combustion chamber pressure (P combustion chamber) PC can be estimated by means of a model on the isentropic compression, valve timing and intake manifold pressure. As the third combustion parameter, the engine control unit ECU determines the quantity of fuel GM to be injected, which is requested for the combustion cycle for optimal combustion in the combustion chamber. Based on these three combustion parameters PI, PC, GM, the engine control unit ECU determines, based on its blocking position (see 1 ) then the axial stroke (lift needle) HU1 for the injector needle NE1 to adjust the geometry shape of the outlet nozzle LN1 suitable. In general terms, therefore, the axial stroke of the injector needle between the blocking position and its injection end position is variably adjusted such that the flow cross-sectional geometry of the outlet nozzle along the Durchströ mung length is adapted to at least one parameter of the combustion process for the gaseous fuel flow GA.

The 4 shows as an alternative to the outwardly opening Injektornadel NE1 of the injector IN1 the 1 and 2 a second, modified injector IN2, the injector needle NE2 is now movably mounted to the inside in the injector CAS2 opening. Its injector CAS2 is cylindrical in shape corresponding to the housing CAS1 of the first injector IN1. In contrast to this, however, now its injector walls converge towards one another at its front end, where they form an outlet nozzle NA2, which has a converging inflow channel section CV2 and a downstream, diverging outflow channel section DV2. The transition region between the converging inflow passage portion CV2 and the downstream adjoining divergent outflow passage portion DV2 is shown in FIG 4 denoted by NA2. The injector needle NE2 is movably supported in the interior of the injector housing CAS2 such that its end wall contour section and the inner boundary of the converging inflow passage section CV2 form the outlet nozzle LN2. For this purpose it may be expedient to round off the injector needle on its end face. Preferably, it has a semicircular outer contour on its front side. In the closed position of the injector IN2, the inwardly opening injector needle NE2 contacts the inner wall of the injector housing CAS2 in the region of the converging inflow passage section CV2 with an annular sealing surface SR2. This is in the 4 indicated by dash-dotted lines. The annular sealing surface SR2 is set back upstream relative to the end-side outlet opening OP of the outlet nozzle LN2. It is located upstream of the tapering area or saddle area NA2 of the outlet nozzle LN2. The axial stroke of the inwardly opening Injektoradel NE2 is in the 4 indicated by a double arrow LI. It is also activated or deactivated in accordance with the first injector IN1 by means of an actuator by the engine control unit ECU and thus in each case brought into a suitable injection position or into a blocking position as a function of the combustion conditions of the combustion process in the combustion chamber. The statements made previously on the outwardly opening injector IN1 for the variable adjustment of the flow-through geometry of the outlet nozzle therefore apply accordingly. In particular, the axial stroke for the injector needle NE2 for properly injecting the gaseous fuel particles GA taking into account the internal pressure in the nozzle channel NC2 before the discharge nozzle, the internal pressure in the combustion chamber, and / or the respective metered amount of fuel can be considered. Of course, other combustion parameters and environmental factors can also be included in the appropriate adjustment of the geometry of the outlet nozzle to give the gaseous fuel particles a sufficiently high penetration rate with at least sonic velocity, so that they reach a sufficient penetration depth and targeted in the predetermined, local combustion zone in the combustion chamber Arrive.

In summary is thus considered in an inwardly opening injector or valve such as. IN2 the Laval nozzle such as. LN2 through the outflow area behind the sealing seat of the needle, e.g. NE2 formed. It is it is appropriate that the flowed through opening cross-section at the needle, e.g. NE2 greater than the cross-section at the saddle location, e.g. NA2 is the Laval nozzle. This leaves can be achieved by the fact that the sealing seat far out in the entry area of the converging inflow passage section CV2 is already at low axial stroke of the injector needle greater Flow area is released.

Generally considered By setting the axial Nadelhubs the penetration rate from the outlet nozzle outflowing gaseous Fuel particles improved control and at least on sonic, in particular to supersonic speed increase. With an outward-opening valve let yourself advantageously by the needle stroke, the injection amount per Time vary.

At the same time changes with the Nadelhub also advantageously the cross-sectional profile the outlet nozzle, so that with a smaller needle stroke a larger cross-sectional ratio between the Injektoraustritt and sealing seat as at full Nadelhub arises. This larger aspect ratio results in supercritical pressures to higher speeds at the injector outlet than at larger needle strokes. This let yourself to use advantageously for controlling the mixture formation. The same applies to the inward opening Injector based on the inlet opening of its converging Einströmdüsenabschnitts.

In the injector according to the invention, a local mixing with the injection of the gaseous fuel particles by high speeds, in particular supersonic speeds, ensured. This produces only locally high turbulence rates, but globally low turbocharging rates, so that the wall heat transfer to the inner walls of the combustion chamber far less than at exit velocities fails only with subsonic. Furthermore, the pressure difference between the high-pressure side on the combustion chamber side becomes the injector more efficient than conventional injectors in a high speed. Another advantage is the implementation of the internal energy of the injected gaseous fuel particles in pulse and thus a temperature drop. The fact that the geometry shape of the outlet nozzle of the injector is designed in particular as a Laval nozzle, advantageously a sonic or preferably supersonic flow can be generated at the nozzle exit. It thus becomes possible to generate such a large pressure difference between the internal pressure in the injector and the internal pressure in the combustion chamber that the momentum of the fuel particles is sufficient to reach the desired local combustion region inside the combustion chamber in sufficient quantity. The supersonic flow is achieved in particular by the fact that the injector in the open state has an outlet nozzle with an inlet-side converging inflow channel section and an adjoining, downstream diverging outlet channel section whose outlet opening opens into the combustion chamber. In the closed state of the injector opening outward, for example, a sealing ring between the outer wall surface of the injector needle and the inner wall surface of the injector housing is formed in the region of the saddle surface or taper surface between the converging inflow channel section and the diverging outflow channel section, upstream of the front outlet opening of the outlet nozzle is set back. Accordingly, in the closed state of the injector, which opens inwardly, for example, in the area of the end face of the injector needle and the inner wall of the converging inflow passage, a sealing ring is formed between the outer wall surface of the injector needle and the inner wall surface of the injector housing, which is set back upstream of the front outlet opening of the ejection nozzle.

Claims (15)

Injector (IN1) for controlled injection of a gaseous Fuel flow (GA) into a given combustion zone (CCL) in a combustion chamber (CC) of an internal combustion engine a nozzle channel (NC1) between its inside, Axialhub- movably mounted Injector needle (NE1) and the inner wall of its outer injector housing (CAS1), wherein along the exit-side end portion of the nozzle channel (NC1) from the outer wall contour section the axially movable Injektornadel (NE1) and the local inner wall contour section of the injector housing (CAS1) an outlet nozzle (LN1) for the gaseous Fuel flow (GA) is formed, which has a converging inflow passage section (CV1) and one down the river subsequent, divergent outflow channel section (DV1). Injector according to claim 1, characterized in that the exit-side outer wall contour section of the Injector needle (NE1) such a movable Annenwandkontur portion for the exhaust nozzle (LN1) forms their flow cross-sectional geometry over their Viewed flow length is changeable, when the injector needle (NE1) from its blocking position, in which they the flow channel the outlet nozzle (LN1) locks, in a predefinable Eindüsstellung changes, in which the flow channel the outlet nozzle (LN1) for injecting of the gaseous Fuel flow (GA) is opened in the combustion chamber (CC). Injector according to one of the preceding claims, characterized characterized in that the cross-sectional geometry shape of the outlet nozzle (LN1) chosen like that is that up for the gaseous Fuel flow (GA) a supersonic flow (JS) at the exit opening of the nozzle channel (NC1) is formed. Injector according to one of the preceding claims, characterized characterized in that along the exit-side end portion of the nozzle channel (NC1) through the outer wall contour portion the axially movable injector needle (NE1) and the inner wall contour section of the injector housing (CAS1) a Laval nozzle as outlet nozzle (LN1) is formed, and wherein the cross-sectional geometry of the convergent Einströmkanalabschnitts and / or the diverging outflow passage portion (DV1) thereof Laval by the axial lifting movement of the Injektornadel (NE1) and the so accompanying change in position its outer wall contour is variably adjustable. Injector according to one of the preceding claims, characterized characterized in that in the blocking position of the injector needle (NE1) for blocking the flow channel the outlet nozzle (LN1) between the outer wall contour portion the injector needle (NE1) and the inner wall contour section of the injector housing (CAS1) a sealing surface (SR1) is formed opposite the frontal outlet opening (OP) of the outlet nozzle (LN1) upstream in the nozzle channel (NC1) reset is. Injector according to one of the preceding claims, characterized in that the actuator (AC) of the Injektornadel (NE1) via at least one control line (SL1) is connected to an engine control unit (ECU) which generates a control signal (SS1) and via the control line (SL1 ) to the actuator of the Injektorna del (NE1) for controlled adjustment of their axial stroke movement (DS, US) transmitted. Injector according to claim 6, characterized that in the generation of the control signal of the engine control unit (ECU) at least one parameter of the gaseous fuel stream combustion process (GA), in particular the fuel pressure of the nozzle channel (NC1), the combustion chamber pressure the combustion chamber (CC), and / or the respective amount of fuel to be injected, received. Injector according to one of the preceding claims, characterized in that the injector needle (NE1) is opposite to the injector (CAS1) opening outward movable is stored. Injector according to claim 8, characterized that the outer wall contour section the injector needle (NE1) along the exit end portion of the nozzle channel (NC1) a longitudinal wall of the converging inflow passage section (CV1) and at the same time downstream, divergent outflow channel section (DV1) of the outlet nozzle (LN1) forms. Injector according to one of claims 8 or 9, characterized that the Injektornadel (NE1) in its locked position, the inner wall of the injector housing (CAS1) in a rejuvenation area between the converging inflow passage section (CV1) and the divergent outflow channel section (DV1) of the outlet nozzle (LN1) with an annular sealing surface (SR1) contacted the opposite the frontal outlet opening the outlet nozzle (LN1) upstream set back is. Injector according to one of claims 1 to 7, characterized in that the injector needle (NE2) opposite the converging, inlet-side inflow channel section (CV2) of the outlet nozzle (LN2) opening inward is movably mounted. Injector according to claim 11, characterized in that the front-side outer wall contour section of the openable to the inside Injector needle (NE2) the inner boundary of the converging inflow channel section (CV2) of the outlet nozzle (LN2) forms. Injector according to one of claims 11 or 12, characterized that the inwardly opening Injektornadel (NE2) in its blocking position the inner wall of the injector housing (CAS2) in the region of the converging inflow channel section (CV2) of exhaust nozzle (LN2) with an annular sealing surface (SR2) contacted the opposite the frontal outlet opening the outlet nozzle (LN2) upstream set back is. Method for the controlled injection of a gaseous Fuel flow (GA) into a given combustion zone (CCL) in a combustion chamber (CC) of an internal combustion engine a nozzle channel (NC1) between an internally arranged, Axialhub- movably mounted Injector needle (NE1) and the inner wall of an external injector housing (CAS1) an injector (IN1), in particular according to one of the preceding claims is formed by along the exit-side end portion of the nozzle channel (NC1) from the outer wall contour section the axially movable Injektornadel (NE1) and the local Annenwandkonturabschnitt of the injector housing (CAS1) an outlet nozzle (LN1) is formed, through whose inflow passage portion (CV1) of the gaseous fuel stream (GA) converges and through its downstream Aunströmkanalabschnitt (DV1) the gaseous Fuel flow (GA) diverges and thereby towards the accelerated predetermined combustion zone (CCL) in the combustion chamber (CC) becomes. Method according to claim 14, characterized in that that the axial stroke of the injector needle (NE1) between the blocking position and their injection end position is set so variable that the flow cross-sectional geometry the outlet nozzle (LN1) along its flow length at least a parameter of the gaseous fuel stream (GA) combustion process, in particular to the fuel pressure of the gaseous fuel stream (GA), to the combustion chamber pressure of the combustion chamber, and / or to the respective quantity of fuel to be metered in the gaseous fuel stream (GA), is adjusted.