Dual fuel fuel-injector

A dual fuel fuel-injector including a first nozzle body having a plurality of respective receptacles, a plurality of nozzle needles, each having a stroke that is controllable by a control fluid and at least one associated control chamber. The plurality of nozzle needles include a plurality of first nozzle needles, each being axially displaceable in the first nozzle body of the dual fuel fuel-injector for selective discharge of a first fuel, whereby the plurality of first nozzle needles are arranged in the first nozzle body in the plurality of respective receptacles. The dual fuel fuel-injector also includes a mixed leakage collecting channel communicatively connected to the plurality of respective receptacles, and a mixed leakage discharge channel on the dual fuel fuel-injector and in communication with the mixed leakage collecting channel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fuel injectors, and, more particularly, to a dual fuel fuel-injector1. The dual fuel fuel-injector can be used, for example, with pilot injection engines, including the type that in addition to pilot injection operation with burnable fuel (and a diesel or heavy oil pilot injection) provide a pure diesel or heavy oil operation. Instead of heavy oil, bio-oil or bio fuel may be used.

2. Description of the Related Art

Gaseous fuels are increasingly gaining importance in the (large) engine sector, in particular with stationary engines for power generation. Natural gas for example, is ideally suited for economical and environmentally friendly engine operation due to its excellent availability and its excellent emission potential compared to diesel fuel.

With dual fuel fuel-injectors of this type, including indirectly controlled injectors (according to the known control principle of “pilot valve-actuator-control chamber”) that use liquid fuel as the control fluid not only for control of a liquid fuel nozzle needle, but also for control of at least one gas nozzle needle, leakage occurs regularly, generally on the guides of the gas nozzle needles. Especially in the case of multi-component multi-needle nozzles, the necessity of collecting and discharging such gas-containing liquid leakage from the fuel injector causes considerable constructional effort.

What is needed in the art is a dual fuel fuel-injector on which treatment of mixed leakage is easily possible from a design point of view.

SUMMARY OF THE INVENTION

The present invention provides a dual fuel fuel-injector which may be used with a first fuel in the form of a liquid fuel, for example diesel fuel, bio fuel or heavy oil and in addition for use with a second fuel in the form of a gaseous fuel or burnable fuel, for example natural gas. The dual fuel fuel-injector can be provided for pilot-injection operation of an internal combustion engine (liquid fuel pilot-injection for ignition of the gaseous fuel), and in addition also for an exclusive liquid fuel operation. The dual fuel fuel-injector is intended for use, for example, with a large engine, for example in a motor vehicle such as a ship or a utility vehicle, or in a stationary device, for example for a cogeneration unit, for a (emergency) power generator, for example also for industrial applications.

The dual fuel fuel-injector includes numerous nozzle needles whose strike is controllable via the control fluid and an associated control chamber. The control fluid—for indirect control of the needle stroke as provided by the invention, according to the principle “control chamber-actuator-pilot valve” is herein liquid fuel (usable with the dual fuel fuel-injector).

Included in the nozzle needles of the dual fuel fuel-injector is multiple first nozzle needles, for example 2, 3, 4 or more first nozzle needles that are arranged in a first nozzle body of the dual fuel fuel-injector, each for selective delivery of a first fuel. The first nozzle needles can deliver a gaseous first fuel, such as natural gas, in this respect representing for example gas nozzle needles.

The thus designed dual fuel fuel-injector includes a mixed leakage collecting channel that connects receptacles (of the first nozzle needles) in a communicating manner, for example, two or more receptacles, or all of the receptacles (of first nozzle needles). In other words, the mixed leakage collecting channel may be a common collecting channel for the receptacles.

Within the scope of the current invention the mixed leakage collecting channel can serve the collection of mixed leakage, generally the mixed leakage treatment on the dual fuel fuel-injector. The mixed leakage consists regularly of mixed control fluid and first fuel (e.g. burnable fuel) whereby the leakage can occur at the respective receptacles of the first nozzle needles (along respective slow leakage paths, progressing from a nozzle-near needle end to a respective needle end remote from the nozzle).

Also located on the dual fuel fuel-injector, for example, on the first nozzle body is a mixed leakage discharge channel that is in communication with the mixed leakage collecting channel. Within the scope of the mixed leakage treatment, the mixed leakage can be transferred via the discharge channel—that is, for example, in the embodiment of a bore—from the mixed leakage collecting channel into an injector housing, for example for discharge from the dual fuel fuel-injector.

Within the scope of a fuel system or fuel injection system the discharge channel (discharge side) can be directed to a pressure regulating device or can communicate with such, by means of which within the scope of the mixed leakage treatment in addition to a discharge from the mixed leakage collecting channel, for example also the adjustment of a target pressure level in the mixed leakage collection channel is made possible. A pressure regulating device of this type, including associated possibilities in mixed leakage treatment that are at least partially also applicable for the current invention are disclosed in another application by the applicant of the current invention and can be found under file DE 10 2013 017 853.3, the disclosure content of which is herein included by reference.

The dual fuel fuel-injector designed in this manner evidently opens up a mixed leakage treatment for first nozzle needles with the possibility of structurally simple design.

Within the scope of the current invention, the first nozzle needles are arranged in the first nozzle body which may be distributed in a circumferential direction of the first nozzle body, in the manner of a rotary magazine. The first nozzle needles may be arranged at equal distances from one another in circumferential direction, so that a uniform delivery of first fuel into a combustion chamber can be achieved with complete coverage around 360°. In further development of the invention, in an arrangement where the nozzle needles are arranged distributed in circumferential direction of the first nozzle body the mixed leakage collecting channel is designed as an annular channel which connects for example all receptacles in a communicating manner.

In a further design of the invention, the plurality of nozzle needles of the dual fuel fuel-injector moreover includes a second nozzle needle that is arranged in a second nozzle body of the dual fuel fuel-injector for selective delivery of a second fuel, such as a liquid fuel (which also serves as the control fluid for the first nozzle needles).

It should be noted that embodiments having a second nozzle body offer the possibility within the scope of the invention of defining the mixed leakage collecting channel via the first and second nozzle body—simply at the interfaces of the same. The mixed leakage collecting channel may be created for example by an indentation or recess that is introduced into a circumferential surface of one of the nozzle bodies of the first and second nozzle body and is covered or closed on an open side by the further nozzle body of the first and second nozzle body, which may be an (outer) circumferential surface or shell surface of the second nozzle body. The indentation may be an easily produced groove or, in the case of a circular mixed leakage collecting channel or annular channel, a circumferential groove.

Within the scope of the invention, the second nozzle body is for example a central nozzle body that is surrounded for example over a section by the first nozzle body with the therein located first nozzle needles. With such preferred concentric arrangement, the first nozzle body has in this respect a ring shaped cross section. Due to the fact that the indentation forming the mixed leakage collecting channel can be introduced into an easily accessible (inside) circumferential surface or shell surface of the first nozzle body, inventive solutions for the design of the duel fuel fuel-injection are achieved.

To achieve good control of the first nozzle needles in the receptacles which communicate with one another, the mixed leakage collecting channel may be located in a longitudinally central region of the receptacles. The nozzle needle can thus be placed above (remote from the nozzle) as well as below (nozzle-near) the mixed leakage collecting channel over a section, for example continuously in the receptacle.

In an alternative design that permits another needle control in addition to simple structural implementation, the mixed leakage collecting channel can moreover be defined between the first nozzle body and a cover plate (remote from the nozzle) on the first nozzle body. The cover plate may, for example, be arranged as an intermediate plate between the first and the second nozzle body, or may also be formed directly by the second nozzle body.

With the current invention, embodiments of the dual fuel fuel-injector are generally provided, whereby the mixed leakage collecting channel communicates to produce radial recesses and/or bores with the receptacles that are connected therewith in a communicating manner, as well as embodiments whereby the mixed leakage channel intersects the receptacles of the first nozzle needles that are connected in a communicating manner, for example directly.

In addition to the mixed leakage collecting channel a mixed leakage collecting chamber—increasing the collecting volume—can be provided at a respective first nozzle needle and/or receptacle (communicating with the receptacle), via which chamber the receptacles are connected via the mixed leakage collecting channel in a communicating manner.

In embodiments where the mixed leakage collecting channel is arranged on the first nozzle body, on the front or more specifically at the end away from the nozzle, a mixed leakage collecting chamber can be provided on a respective receptacle which is connected in a communicating manner with the mixed leakage collecting channel and which can be established at the end away from the nozzle of the first nozzle needle that is accommodated in the receptacle (and in addition for example also around a needle guide sleeve arranged thereupon). This enables good control of the nozzle needle in the receptacle over a substantial part of its length, for example at the end remote from the nozzle, additionally via a needle guide sleeve and/or in addition a formation of the collecting channel via front-side material removal (on the first nozzle body) including simple formation of the mixed leakage collecting chamber as a cross-sectionally enlarged receptacle section ((step-)bore) and furthermore an optional dimensioning of the top end of the nozzle needles for simple provision of an intended control cross section for the (hydraulic) stroke control of the nozzle needle.

Additional embodiments can provide formation of a mixed leakage collecting chamber for example also additionally over a section of a respective receptacle of a gas nozzle needle and/or over a section of a respective gas nozzle needle, for example, via a cross section enlargement at the receptacle or a sectional tapering on a gas nozzle needle.

The invention also suggests an internal combustion engine, including the type referred to at the beginning that has at least one dual fuel fuel-injector as previously described. The dual fuel fuel-injector can be connected with a mixed leakage treatment device via the discharge channel, for example with a pressure regulating device of a mixed leakage treatment device as previously mentioned.

DETAILED DESCRIPTION OF THE INVENTION

Referring now toFIG. 1there is shown an inventive dual fuel fuel-injector (dual fuel nozzle or more specifically dual fuel injector)1that can be provided for injection operation with a first liquid fuel (e.g. diesel fuel, bio fuel, or heavy oil) as well as for delivery of a second, gaseous fuel (burnable fuel, for example natural gas) for burnable fuel injection. Dual fuel fuel-injector1can be used with a dual fuel fuel-injection system, for example, with a gas common rail system, furthermore with an internal combustion engine which is arranged or pilot injection operation (with injected burnable fuel and injected liquid fuel pilot injection) as well as for exclusive liquid fuel operation via dual fuel fuel-injector1.

Dual fuel fuel-injector1includes a (first) nozzle body3in which several first needles5are arranged axially movable. First nozzle needles5are provided for selective delivery of a first gaseous fuel, for example for delivery of burnable fuel (within the scope of a burnable fuel injection into a combustion chamber of an internal combustion engine) and in this respect are also referred to below as gas nozzle needles5. Gas nozzle needles5are mounted and controlled axially movable in first nozzle body3, respectively in an associated seat7, created by a respective axial bore9in first nozzle body3.

First nozzle needles5are arranged, for example equidistant, and distributed in first nozzle body3in circumferential direction of dual fuel fuel-injector1or more specifically of first nozzle body3that is along a circular path (whereby first nozzle body3is quasi in the embodiment of a rotary magazine for gas nozzle needles5). In the illustrated dual fuel fuel-injector1, four gas nozzle needles5are for example arranged in first nozzle body3, distributed in circumferential direction, whereby advantageously uniform gas delivery into a combustion chamber can be achieved completely around 360°. Embodiments are also conceivable with two, three, five or another different number of gas nozzle needles5.

Dual fuel fuel-injector1moreover includes one second nozzle body11in which one additional nozzle needle13is provided for injection processes that provide selective delivery of a second fuel, for example a liquid fuel (into a combustion chamber of an internal combustion engine). Second nozzle needle13that is subsequently referred to also as liquid fuel nozzle needle13is also axially stroke-controllable and mounted in a corresponding receptacle15of second nozzle body11. The receptacle15of second nozzle body11is formed by an axial bore17in second nozzle body11.

Dual fuel fuel-injector1moreover includes a high pressure channel19that leads from a liquid fuel inlet21of dual fuel fuel-injector1to a liquid fuel nozzle chamber23supplied by a high pressure (HD) supply device25of a fuel injection system, including for example of a high pressure pump27and a rail29and/or also a single pressure accumulator, for example originating from a liquid fuel storage, for example a tank.

For selective delivery of liquid fuel, dual fuel fuel-injector1is moreover designed to deliver high pressure liquid fuel that—depending on the (stroke) setting of second nozzle needle13—is introduced into liquid fuel nozzle chamber23via a liquid fuel nozzle arrangement31of dual fuel fuel-injector1. In an injection operation (for example pure liquid fuel operation or pilot-injection operation) the duel fuel fuel-injector1is designed in particular to inject into a combustion chamber of an internal combustion engine.

For stroke control of the second nozzle needle13within the scope of the fuel injection processes, dual fuel fuel-injector1that in the current example is operated indirectly actuated—as illustrated inFIG. 1—includes in particular a pilot valve (control or servo valve)33that can be controlled by a solenoid actuator (or for example a piezo actuator). Via pilot valve33that is accommodated with its actuator system in an injector housing35, a control chamber37of dual fuel fuel-injector1that is associated with second nozzle needle13can be relieved depending upon valve position; via a leakage flow path39of the injector-internal fuel system. Originating from control chamber37, leakage flow path39leads to a leakage outlet41on low pressure side (ND) of the dual fuel fuel-injector1, that is via pilot valve (by throttling)33, for example, to a leakage collecting tank.

In addition, a high pressure path43of the injector-internal fuel system (with throttling) leads to control chamber37for second nozzle needle13, through which control chamber37is chargeable—via highly pressurized liquid fuel—originating from high pressure channel19. Control chamber37is defined by a needle guide sleeve45(and injector housing35). The needle guide sleeve45is accommodated at the nozzle-remote end of axial bore17in second nozzle body11, whereby moreover a closing spring47can be arranged in axial bore17which pushes second nozzle needle13into the closed position, in other words against a valve seat or nozzle needle seat adjacent to liquid fuel nozzle arrangement31.

In order to deliver liquid fuel in a liquid fuel fuel-injection operation through liquid fuel nozzle arrangement31—for example via liquid fuel nozzle chamber23—the (closing) balance of power at second nozzle needle13can be terminated through relief of control chamber37via pilot valve33(leakage flow path39open), so that second nozzle needle13can lift off the valve seat and can open the flow path to the spray holes of liquid fuel nozzle arrangement31. In order to close the nozzle valve, pilot valve33is switched to the blocked position (seeFIG. 1), following which the pressure in control chamber37is again built up via high pressure path43and second nozzle needle13returns into the needle seat aided by the closing spring force.

Liquid fuel may be used to charge and relieve control chamber37or for (hydraulic) stroke control of second nozzle needle13.

For operation with gaseous fuel (natural gas, bio gas, etc.), dual fuel fuel-injector1comprises a high pressure gas channel49that leads from a burnable fuel inlet51on dual fuel fuel-injector1to a common nozzle chamber53for the plurality of first nozzle needles5(or alternatively to a plurality of branched gas nozzle chambers53). Burnable fuel inlet51can be supplied via a supply arrangement54of a fuel injection system, for example at a pressure level to approx. 350 bar.

From nozzle chamber53highly pressurized burnable fuel that was introduced into same via high pressure gas channel49can be delivered depending on the stroke position of first nozzle needles5. A respective flow path leading from gas nozzle chamber53to at least one gas nozzle opening associated with gas nozzle needle5of a gas nozzle arrangement55of dual fuel fuel-injector1can hereby be selectively closed via a respective gas nozzle needle5. In regard to gas nozzle arrangement55, one or several, for example two each gas nozzle openings can herein be assigned to a respective first gas nozzle needle5which can be opened selectively by the same.

For stroke control of the plurality of gas nozzle needles5, dual fuel fuel-injector1is configured analog to the operating principle described previously for stroke control of liquid fuel nozzle needle13, for example for indirect control of first nozzle needles5. In this respect—as illustrated inFIG. 1—each of the first nozzle needles5on dual fuel fuel-injector1has allocated to it a control chamber65for activation with a control fluid. The control fluid for indirect control of gas nozzle needles5—as is the case for liquid fuel nozzle needle13—is the liquid fuel that is supplied to dual fuel fuel-injector1via liquid fuel inlet21.

In order to be able to control gas nozzle needles5advantageously, easily, and moreover in totality and synchronously, dual fuel fuel-injector1includes a control channel59that is provided as a common pre-control chamber for the first nozzle needles5and which can be charged and relieved via the control fluid (liquid fuel). Control chambers57for first nozzle needles5are connected in a communicating manner with control channel59, that is, in each case via an inlet throttle device, formed for example by a throttle bore61. An outlet branch63for relief of control channel59, and consequently for common relief of control chambers57of first nozzle needles5is via side of control channel59over an outlet throttle device65toward the low-pressure side (ND).

In addition to the stroke control of first nozzle needle5via selective relief of control channel59or more specifically control chambers57of first nozzle needles5—analog to the liquid fuel operation—an additional pilot valve (control valve)67can be provided on dual fuel fuel-injector1. Additional pilot valve67(including its actuators) is also accommodated in injector housing35. Depending on the valve position of additional pilot valve67, control channel59can be discharged via control fluid outlet63which is controlled via additional pilot valve67, that is to low pressure side (ND) leakage outlet69, for example to a leakage collection tank.

To now deliver burnable fuel for a burnable fuel injection operation via second gas nozzle arrangement55, i.e. via gas nozzle chamber53, the (closing) balance of power on a respective first nozzle needle5can be terminated through relief of control channel59and to that extent of respective control chamber57for first nozzle needle5that is connected in a communicating manner via additional pilot valve67(outlet63open), so that respective first nozzle needle5can lift off a valve seat and can open the flow path to a nozzle opening on gas nozzle arrangement55. To close the nozzle valve, additional pilot valve67is switched into the locked position (seeFIG. 1), as a consequence of which the pressure in control channel59and in this respect, in control chamber57for first nozzle needle5that is connected in a communicating manner builds up again via a liquid fuel high pressure path71with an infeed throttle72, and respective first nozzle needle5returns to the needle seat aided by the spring force.

According toFIG. 1and favoring a compact arrangement, second nozzle body11has a stepped profile, that is with a first nozzle-near segment11A and in contrast with a second cross section enhanced segment11B, remote from the nozzle. First nozzle body3—that has a ring-shaped cross section—surrounds the first cross section adapted segment11A of second nozzle body11, whereby—viewed in axial direction—between first3and second11nozzle body an element73in the embodiment of an intermediate plate, covering first nozzle body3is arranged.

With this arrangement, a respective control chamber57for first nozzle needles5can be formed via first nozzle body3and intermediate plate73(and the end of respective gas nozzle needles5), in other words at the end away from the nozzle on each receptacle7for a first nozzle needle5. Control channel59can also be defined as being simple to manufacture with intermediate plate73and/or second nozzle body11. A closing spring can be optionally provided on a respective first nozzle needle5that pushes gas nozzle needle5—for example during down-time of dual fuel fuel-injector1—into the closed position.

During operation of the inventive dual fuel fuel-injector1, mixed leakage in the form of gas-containing liquid leakage may occur regularly along or on respective receptacles7of first nozzle needles5. A cause for the mixed leakage emergence can be liquid fuel, originating from a respective control chamber57on the outside circumference of a first nozzle needle5in the associated receptacle7moving slowly in the direction toward gas nozzle chamber53(along a slow leakage gap between nozzle needle5and receptacle7), whereas burnable fuel along such a slow leakage gap or guide gap between receptacle7and gas nozzle needle5can be displaced toward the associate control chamber57.

To make available such mixed leakage to a mixed leakage treatment, the inventive dual fuel fuel-injector1includes a mixed leakage collecting channel75which connects the receptacles7in a communicating manner. In the design according toFIG. 1, mixed leakage collecting channel75is in the embodiment of an annular channel extending in circumferential direction and connecting all receptacles7of first nozzle needles5in a communicating manner.

Furthermore, according to the invention a mixed leakage discharge channel77that is in communication with mixed leakage collecting channel75is provided on dual fuel fuel-injector1for the intended treatment of the mixed leakage. Via mixed leakage discharge channel77and mixed leakage collecting channel75the mixed leakage occurring at receptacles7can be reliably removed from receptacles7and furthermore from first nozzle body3or respectively from fuel injector1, and can be transferred via a (discharge side) outlet78of discharge channel77to a downstream treatment device, in the embodiment of a pressure regulating device of the type referred to previously.

A design of dual fuel fuel-injector1according toFIG. 1—wherein first nozzle body3surrounds second nozzle body11over a section11a—allows for a structurally simple provision of mixed leakage collecting channel75. This will be addressed in further detail below.

On dual fuel fuel-injector1according toFIG. 1—see alsoFIGS. 1A to 5—mixed leakage collecting channel75is formed by an indentation or recess, for example by an annular groove. The annular groove is worked into inside circumferential surface79of first nozzle body3, whereby the annular groove on its side opposite the groove bottom, or more specifically opening side is covered by second nozzle body11through formation of an all-around enclosed annulus, or more specifically annular channel (that is via the (tapered) end section11A of second nozzle body11(or more specifically its circumferential outside surface), which penetrates the (through) opening of first nozzle body3). Mixed leakage collecting channel75, thus formed in a simple manner communicates with a respective receptacle7of a first nozzle needle5via a bore81, formed by an easily producible bore (that can be in the form of a diagonal bore, extending radially away from mixed leakage collecting channel75toward respective receptacle7). As is the case with the annular groove, bores81can also be laid out in such a design of dual fuel fuel-injector1to be easily accessible, originating from inside shell surface79of first nozzle body3.

In increasing the mixed leakage collection volume, it is moreover provided in the embodiment as shown inFIGS. 1-5to reduce the cross section of a respective first nozzle needle5guided in receptacle7over its longitudinal center section83, whereby between the wall of receptacle7and tapered section83a mixed leakage collecting chamber85is provided in the embodiment of an annular chamber. Receptacle7communicates with the thus formed mixed leakage collecting chamber85and diagonal bore81branching off therefrom.

FIG. 1Aillustrates more closely the mixed leakage collecting chamber85on a first nozzle needle7, complete with diagonal bore81.

FIG. 2shows an additional sectional view of dual fuel fuel-injector1according toFIG. 1, in particular its nozzle body module that consists of its first3and second11nozzle body as well as intermediate plate73. As can be seen inFIG. 2, mixed leakage discharge channel77that is in communication with mixed leakage collecting channel75is formed through a section in first nozzle body3as a diagonal bore, whereby mixed leakage discharge channel77extends furthermore through intermediate plate73and through second nozzle body11, each in the form of an axial bore channel.

FIGS. 3-5illustrate more closely additional sectional views of first nozzle body3of dual fuel fuel-injector1as shown inFIGS. 1 and 2, in particular the cross section of mixed leakage collecting channel75or more specifically the ring shaped indentation worked into first nozzle body3for the purpose of its formation. In this design, wherein mixed leakage collecting channel75has only a small cross section and the connection of receptacles7occurs via bores81, the stability of nozzle body3is not appreciably affected, so that mixed leakage collecting channel75can be configured advantageously also in structurally weaker regions on first nozzle body3. First nozzle needle5can also be guided over a section above and a section below mixed leakage collecting channel85or respectively mixed leakage channel75in receptacle7, along with an effective seal on receptacle7.

An additional embodiment of dual fuel fuel-injector1is explained in further detail below with reference toFIGS. 6-8.

FIG. 6shows first nozzle body3of the additional embodiment in a sectional view. In contrast to the previously described embodiment according toFIGS. 1-5, first nozzle body3is herein provided with a mixed leakage collecting channel75that is formed by an annular groove in first nozzle body3that directly intersects receptacles7of gas needles5, for example in a longitudinal central region of the same. Separate bores81for respective receptacles7originating from mixed leakage collecting channel75can be dispensable, besides which a large mixed leakage collecting volume in the form of collecting channel75is provided.

In contrast to the preceding embodiment, the collecting channel groove with its rectangular shaped cross section is worked deeper into first nozzle body3, in this respect in a relatively strong material region of nozzle body3—in the current example in the region of a nozzle body flange. With a simplified manufacture, high stability at continuously reliable control below and above mixed leakage collection channel75and good sealing at first nozzle needles5is achieved.

Further, in contrast to the embodiment according toFIGS. 1-5, mixed leakage discharge channel77in first nozzle body3is provided over a section77A as an axial bore channel that communicates with mixed leakage channel75and which subsequently is connected in a communicating and simple manner via a radial section77B—that is worked into the nozzle-remote end of first nozzle body3—with an additional axial section in intermediate plate73and second nozzle body11.

FIG. 7shows a top view of a thus formed first nozzle body3.

FIG. 8is a sectional view through the plane of mixed leakage annular channel75, showing in particular the communicating section of receptacles7of first nozzle needles5via mixed leakage collecting channel75.

An additional design of dual fuel fuel-injector1is described in further detail below with reference toFIGS. 9 and 10.

FIG. 9shows a side view of first nozzle body3of the additional embodiment of dual fuel fuel-injector1with the therein accommodated first nozzle needles5.

In this embodiment, mixed leakage channel75is formed by a groove that connects receptacles7in a communicating manner, this groove is worked into the nozzle-remote face side of first nozzle body3. The communicating connection of the groove with receptacles7is herein realized via mixed leakage collecting chambers85which are formed at a respective end away from the nozzle on a receptacle7by a cross section enlargement of the same for the provision of a mixed leakage collecting volume.

A respective mixed leakage collecting chamber85can herein be worked in a simple manner into first nozzle body3originating from the nozzle-remote face side of same, for example as a bore or a different kind of material removal. In this embodiment of dual fuel fuel-injector1, needle guide sleeves87are evidently provided in respective receptacles7or more specifically mixed leakage collecting chambers85that guide first gas nozzle needles at the end away from the nozzles. Via needle guide sleeves87and correspondingly dimensioned end sections of respective first nozzle needles5, varied control cross sections and/or control chambers57can be defined in a more simple manner for first nozzle needles5.

In order to ensure that gas leakage moving slowly potentially over the leading section of receptacle7on receptacle7, or liquid fuel moving slowly from control chamber57in direction toward gas nozzle arrangement55can reliably enter into mixed leakage collecting chamber85, needle guide sleeve87can be designed over one section—for example outside control chamber57—with at least one through-opening89, for example on its nozzle-near end that is supported on a step of the enlarged cross sectional region. As shown inFIG. 9, a clamping sleeve91can be provided alternatively, that pushes needle guide sleeve87that is accommodated in the enlarged cross sectional region of receptacle7against a covering element73, for example against intermediate plate73. Through one of several radial through-openings89of clamping sleeve91the respective gas or liquid leakage can hereby enter into respective leakage collecting chamber85and via the same can enter into mixed leakage channel75.

To discharge the mixed leakage, mixed leakage collecting channel75is again connected in a communicating manner with a mixed leakage discharge channel77. One section of mixed leakage discharge channel77is also formed on the face side of first nozzle body3by a radial branch77B originating from mixed leakage collecting channel75.

FIG. 10shows first nozzle body3as shown inFIG. 9with an intermediate plate73and a second nozzle body11, again assembled into a nozzle body module of dual fuel fuel-injector1. As illustrated inFIG. 10, first nozzle body3is covered on the nozzle-remote end by intermediate plate73, so that mixed leakage collecting channel75is formed between first nozzle body3and intermediate plate73. Mixed leakage collecting chambers85are hereby further defined in a simplified manner (as surrounded volume); alongside control chamber57of first nozzle needles5as well as radial section77bof mixed leakage discharge channel77. As further illustrated inFIG. 10, mixed leakage discharge channel77continues over bore sections further through intermediate plate73and second nozzle body11.