DE102013016703B4 - Fuel injector with a combustion chamber pressure sensor and an assembly and disassembly method for such - Google Patents

Abstract

Fuel injector (1) for an internal combustion engine, wherein the fuel injector (1) has a nozzle body (3) in which a nozzle needle (5) of the fuel injector (1) is accommodated and on which a nozzle arrangement (9) of the injector (1) is formed ; wherein an injector housing assembly (15a, b, c) is further connected to the nozzle body (3), the fuel injector (1) having an optical combustion chamber pressure sensor (19) with a sensor head (19a) and a fiber optic strand (19b) connected thereto; wherein the sensor head (19a) is received in a conical seat bore (21) in the nozzle body (3) and fixed in the seat bore (21) by means of wedge pieces (29a, 29b) surrounding the sensor head; and wherein a channel (25) for receiving the optical fiber strand (19b) extends from the seat bore (21) through the nozzle body (3) to an inlet (27) on the fuel injector (1). Also proposed is an assembly method and a dismantling method for the fuel injector (1).

Description

The present invention relates to a fuel injector with a combustion chamber pressure sensor according to the preamble of claim 1. Furthermore, the present invention relates to a mounting method for such a fuel injector according to the preamble of claim 9. Still further, the present invention relates to a disassembly method for such a fuel injector according to the preamble of claim 12.

To improve the diesel engine combustion control, the reduction of cyclic fluctuations as well as the compensation of injector drift and specimen scattering (scattering injector-to-injector), the cylinder pressure curve is measured in cranked angle resolution in serial passenger cars and commercial vehicle engines. About the pressure increase, the burning rate can be calculated, which gives information about the amount of fuel introduced. In series applications, the cylinder pressure sensor is integrated either in the glow plug or, if there is sufficient space at the combustion chamber, as a screw-in sensor in the cylinder head.

The pamphlets DE 697 33 279 T2 and US 2012/0 073 361 A1 In addition, solutions that make use of optical sensors on the injector show.

In the prior art, it is also known, for. B. from the publications JP 2001 108 556 A . JP 2007 285 133 A . DE 101 27 932 A1 . US 2010/0 050 991 A1 and US 8,375,924 B2 To provide pressure sensors directly on the injector, which are subject to either a piezoelectric or magnetostrictive principle, insofar as they are housable with low space requirements and still reasonable assembly and cost of the injector. However, Piezoaufnehmer regularly need a charge amplifier, their long-term stability is poor and their long-term use hardly possible. Magnetostrictive sensors may have disadvantageously large magnetomechanical hysteresis and be susceptible to electromagnetic interference.

Proceeding from this, it is an object of the present invention to propose a fuel injector, which makes use of a combustion chamber pressure sensor of an alternative measuring principle, in particular a sensor which is advantageously mounted as a prefabricated assembly on the injector and in a simple manner can also be disassembled. It is another object of the invention to provide an assembly method for producing such an injector formed in an advantageous manner, as well as a corresponding dismantling method.

This object is achieved with regard to the fuel injector by the features of claim 1, with regard to the assembly method by the features of claim 9 and with respect to the dismantling method by the features of claim 12.

Advantageous developments and embodiments of the invention are specified in the further claims.

According to the invention, a fuel injector for internal combustion engine or an internal combustion engine is proposed. The injector can be operated with diesel fuel or with a different fuel, for example, with another fuel in the form of heavy oil, biofuel or z. B. mixed fuel. The injector is preferred for use with a large diesel engine, for example for a motor vehicle such as a ship or a commercial vehicle, or, for example, for a stationary device such as a combined heat and power plant, an emergency generator or z. B. intended for industrial applications.

The fuel injector has a nozzle body in which (axial bore) a nozzle needle of the fuel injector is accommodated (in particular axially displaceable) and on which a nozzle arrangement of the injector is formed. The nozzle arrangement may comprise one or more injection holes, in particular formed on a nozzle tip of the nozzle body.

The fuel injector further has an injector housing assembly, which is connected to the nozzle body, in particular (axially) braced. The housing assembly may include, for example, a valve plate, an intermediate plate, a lid member or a single pressure accumulator.

According to the invention, the fuel injector has an optical pressure sensor for detecting the combustion chamber pressure or an optical combustion chamber pressure sensor with a sensor head and a light conductor strand connected thereto, wherein the sensor head is received in a conical seat bore in the nozzle body and fixed in the seat bore by means of wedge pieces surrounding the sensor head, in particular pressed and wherein a channel for receiving the optical fiber strand extends from the seat bore through the nozzle body to an inlet on the fuel injector. In particular, the wedge pieces enclose the sensor head in the context of the invention around its entire circumference, that is, as it were a cuff.

The optical combustion chamber pressure sensor, which is formed with sensor head and light guide ( fiber optic combustion chamber pressure sensor), preferably operates according to the following, briefly explained measuring principle: in the sensor head via the light guide (eg., At least a first optical fiber) supplied light which irradiates a (recorded in the sensor head) deflectable membrane, ie at the rear side , On the front of the membrane acts from the combustion chamber side of the combustion chamber pressure, depending on which pressure the membrane deforms. The deformation of the membrane changes the intensity of the reflected light, which in this respect (taking into account a temperature correction) is correlated with the combustion chamber pressure.

The intensity of the reflected light can detect a coupling unit connected to the light guide (optical fiber cable) (eg via at least one second optical fiber of the light guide) (at the sensor head far end of the light guide). A coupling module which, in addition to the coupling of light into the optical waveguide, is ideally also set up for outputting electrical measuring signals based on the detected light intensity, is preferably attached to the injector or its housing assembly and can be z. B. also include a signal evaluation unit.

The proposed fuel injector allows extremely accurate combustion chamber pressure detection, insofar as the optical combustion chamber pressure sensor is advantageously insensitive to electromagnetic interference and also able to meet the high requirements for temperature compatibility. Furthermore, the proposed fuel injector advantageously makes possible the use of combustion chamber pressure sensors, which are preferably provided in the context of the invention as a prefabricated unit (not separable non-destructively) from sensor head, optical waveguide and coupling module. Due to the possible with the fuel injector centric arrangement of the sensor head on the combustion chamber, a high-quality combustion chamber pressure detection is further advantageously provided, is provided in the invention to form the seat bore for receiving the sensor head on or adjacent to a nozzle tip of the nozzle body.

In the context of the invention it is further provided that the preferably cylindrical sensor head together with the wedge pieces of an outer or combustion chamber side of the nozzle body inserted into the seat bore in the seat bore (the cross section thereof in the direction of the nozzle near end of the nozzle body to the nozzle distal end of the nozzle body tapered) is fixed and next to it, that the channel over its entire length has a diameter which is suitable to push the sensor head, starting from the inlet into the seat bore (non-destructive).

In preferred embodiments of the invention, the wedge pieces fixing the sensor head in the seat bore also seal against the wall of the correspondingly dimensioned seat bore and / or the sensor head dimensioned correspondingly, in this case preferably gas-tight. For a further improved sealing, sealing compound may be provided between the seat bore wall and the wedge pieces and / or between the wedge pieces and the sensor head. Alternatively or additionally, use may also be made of sealing elements such as at least one O-ring (ring seal) or circumferential elevations, which allow the representation of defined sealing lines with increased pressure.

In further preferred embodiments of the fuel injector, the wedge pieces fixing the sensor head in the seat bore have at least one parting line (between two wedge pieces), in particular fissured negative and positive structure and / or at least one parting line, which is produced by means of fracture separation as a negative and positive structure. Such a parting line supports accurately fitting pre-assembly (prior to introduction into the conical seat bore) and also ensures a very good sealing effect, in particular in the case of an inventive seal against fuel gas.

Preferably, the sensor head is fixed in the seat bore by means of a first and a second wedge piece, wherein the fixing wedge pieces are in particular half-cone pieces. By using only two wedge pieces advantageously simple handling during assembly is achieved. According to an advantageous development, the wedge pieces arranged in the seat bore can have a collar at the end remote from the nozzle, against which the sensor head can be supported, and thus can advantageously be secured against axial slippage.

Furthermore, it is conducive to the intended gas seal on the wedge pieces, and advantageously also anti-slip, is preferred in the invention that the sensor head on a circumferential surface, which is provided for engagement with the wedge pieces, a circumferential raised continuous structuring and / or a grooving having. In particular, structuring is provided in such a way that penetration into the preferably softer wedge piece material is made possible.

In the context of the present invention, a method for assembling a fuel injector as described above is also proposed, wherein in a first step the optical fiber - with the sensor head in advance - is inserted from the inlet into the channel until the sensor head emerges from the conical seat bore. After leaving From the seat bore, the wedge pieces are now arranged around the (now exposed) sensor head in a second step. In a subsequent third step, the wedge pieces are inserted with the recorded on the same sensor head in the conical seat bore or seat (opposite to the exit direction) and fixed, in particular pressed.

The proposed assembly method allows easy mounting and reliable fixation of the optical combustion chamber pressure sensor, in particular a pre-assembled combustion chamber pressure sensor as described above. In addition, a fixation is achieved with the proposed method, which - in particular in the context of the disassembly method described below - also allows a non-destructive release from the injector and thus reuse the combustion chamber pressure sensor.

As part of the assembly process is provided that the wedge pieces are inserted with the same recorded on the sensor head in the third step of an outer / combustion chamber side of the nozzle body into the conical seat bore and / or pressed for fixing to the wall of the seat bore. For pressing, a predetermined press-in force, in particular a force which corresponds approximately to the force with applied cylinder pressure in the combustion chamber, can be provided. In the context of the method it is provided that the wedge pieces surround the sensor head when arranged on the sensor head over its entire circumference, that is uninterrupted.

In the context of the assembly method, a fourth step may further be provided, in which the channel between the seat bore and the inlet is sealed and / or sealed by means of backfilling and / or sealed by means of a received in a recording on the injector sealing element, in particular a sealing bolt becomes. For example, a grease filling introduced in the optical waveguide channel can advantageously protect the optical fiber strand from vibration and scrubbing. By means of a sealing bolt (or throttle pin), which obstructs the channel between the inlet and seat bore, the light guide can continue to be fixed radially, thus advantageously protected against wear and tear during engine operation. Preferably, a sealing bolt is slotted here.

In a fifth step of the proposed method, it may further be provided to mount a coupling module of the combustion chamber pressure sensor or an evaluation unit on the fuel injector or its housing.

As already mentioned above, in the context of the present invention, a method for dismantling a fuel injector as described above is proposed, wherein the arrangement of the wedge pieces and the sensor head fixed or received in the seat bore is acted on in a first step by a release pressure on the part of the channel is, wherein the release pressure is introduced by means of a pressure medium in the channel. The process step is preferably ended when the sensor head together with the wedge pieces out of the seat bore (towards the combustion chamber side of the nozzle body) was (d) moved.

As the pressure medium is preferably provided grease or oil. For example, grease for disengaging the sensor head (from the seat bore to the combustion chamber side on the nozzle body) can be pressed into the channel in an advantageously simple manner (eg via a grease gun), thus building up the release pressure, alternatively, for example, pressure oil can be provided.

It is envisaged in the context of the dismantling process, that the release pressure or the pressure medium is introduced in the first step via an in the channel between the inlet and seat bore stifling pressure channel into the channel, wherein the channel between the intake and inlet is blocked. In this case, a sealing element may preferably be provided, as described above for the assembly method, which, in addition to the fixing of the light guide in the channel, advantageously also permits the pressure build-up for a disengagement of the sensor head.

Further features and advantages of the invention will become apparent from the following description of embodiments of the invention, with reference to the figures of the drawings, which show details essential to the invention, and from the claims. The individual features can be realized individually for themselves or for several in any combination in a variant of the invention.

Preferred embodiments of the invention are explained below with reference to the accompanying drawings. Show it:

1 exemplary and schematically a fuel injector for an internal combustion engine according to a possible embodiment of the invention.

2 Exemplary and schematically taken in an enlarged view of the nozzle body components of the fuel injector according to 1 with sensor head and optical fiber.

3a exemplary and schematically a detailed view of a detail according to 2 , ie, the sensor is received in wedge pieces on the nozzle body.

3b exemplary and schematically an alternative embodiment of the arrangement according to 3a ,

4 exemplary and schematically possible embodiments of the wedge pieces according to the invention.

5 exemplary and schematically a sealing bolt.

6a an example and schematically a view showing the sensor head with light guide after the first step of the assembly process and the subsequently to be arranged in the second step on the sensor head wedge pieces.

6b exemplary and schematically another view according to 6a which illustrates the sensor head with wedge pieces disposed thereon after completing the second process step of the assembly process.

6c exemplary and schematically another view according to 6a and 6b , which fixes the sensor head in the seat bore illustrated in completed third step of the assembly process.

7a an enlarged view of a detail 6a ,

7b an enlarged view of a detail 6b ,

8th by way of example and schematically an illustration showing the disassembly method according to the invention on the fuel injector according to FIG 1 illustrated in more detail.

In the following description and the drawings, the same reference numerals correspond to elements of the same or comparable function.

In the context of the invention, the term seat bore can also encompass or designate a seat or a corresponding opening which was not made by means of a drilling method but otherwise.

1 shows a fuel injector 1 for an internal combustion engine, in particular for use with diesel fuel.

The fuel injector 1 has a nozzle body 3 on, in which a nozzle needle 5 of the fuel injector 1 is included, that is in an axial bore 7 of the nozzle body 3 axially displaceable. In the axial bore 7 (Nozzle space) opens a fuel high-pressure channel of the fuel injector 1 (not shown), wherein a flow path from the axial bore 7 towards a nozzle arrangement 9 on the nozzle body 3 by suitable stroke control of the nozzle needle 5 is selectively releasable for an injection mode (nozzle valve). In the nozzle body 3 are still a closing spring 11 and a needle guide sleeve 13 in the known active compound with the nozzle needle 5 recorded for the stroke control, wherein the fuel injector shown 1 in the present case for indirect Nadelhubsteuerung is set up (via a pilot valve).

The fuel injector 1 further includes an injector housing assembly 15a , b, c, which by means of a single-pressure accumulator 15a , a valve plate 15b and an intermediate plate 15c or z. B. individual elements thereof is formed. The injector housing assembly 15a , b, c is with the nozzle body 3 clamped, including a nozzle chip nut 17 of the fuel injector 1 is provided.

According to the invention, the fuel injector 1 an optical combustion chamber pressure sensor 19 with a sensor head 19a and a fiber optic string connected thereto 19b on (fiber optic combustion chamber pressure sensor).

The sensor head 19a is substantially cylindrical and includes (in particular at a light conductor remote or near the nozzle end) a membrane (eg. 3a ), which is for a pressure measurement at a the light guide 19b (preferably fiber optic cable) facing side over the light guide 19b is irradiated (including at least a first optical fiber of the light guide 19b and in particular a coupling module 19c for the combustion chamber pressure sensor 19 is provided).

The opposite side of the membrane is provided for acting on the combustion chamber pressure and is in the inventive arrangement of the sensor head 19a on the nozzle body 3 positioned in the cylinder head (combustion chamber deck) directly in the combustion chamber (especially barrier-free), thus the transducer (transducer) in the form of the membrane can detect the measured variable with high quality and advantageously unabated. This allows - in addition to the already advantageous measurement accuracy of the sensor 19 - a maximized accurate measurement.

As part of a combustion chamber pressure measurement takes the light guide 19b the reflected light from the membrane, the intensity of which changes due to deformation of the membrane when exposed to the combustion chamber pressure (including at least a second optical fiber of the optical fiber strand 19b is provided). Over the light guide 19b For example, the light signal modulated with the deformation can be removed for signal processing or evaluation via the coupling module 19 for example one with the sensor 19 connected evaluation unit, which may be implemented in an engine control unit, for example.

According to the invention, the fuel injector 1 or its nozzle body 3 furthermore a conical seat bore 21 on which is provided, the sensor head 19a on the nozzle body 3 to be able to fix. The seat bore 21 is from the outside (from the combustion chamber side A of) in the nozzle body 3 introduced, preferably adjacent to a nozzle tip 23 or to the nozzle arrangement 9 ,

Starting from the conical seat bore 21 whose cross-section tapers from the nozzle-near end to the nozzle-distal end (continuously), a channel continues to extend 25 - Preferably formed as a drilling channel - for receiving the fiber optic strand 19b through the nozzle body 3 ie, starting from the conical seat bore 21 from the nozzle end 3a of the nozzle body 3 up to its nozzle-distant end 3b , seat bore 21 and channel 25 In this regard, they form a passageway through the nozzle body 3 ,

2 and 3a illustrate the above in more detail.

Furthermore, according to z. B. 1 the channel sits down 25 in communication and aligned over a portion of the injector housing 15a , b, c and preferably flows laterally on the Injektorgehäusebaugruppe 15a , b, c, for example, the pressure accumulator housing 15a , from (preferably at a freely accessible location for an electrical connection of the sensor 19 ), ie at a (duct) inlet 27 at the fuel injector 1 , Adjacent to the inlet 27 is preferred the arrangement of the coupling module 19c (For example, with integrated evaluation) provided. It should be mentioned that the channel 25 over its entire length has a diameter and a shape which is suitable, the sensor head 19a from the inlet 27 intact in the seat bore 21 to push.

As in particular z. B. the 2 and 3a can be removed is the sensor head 19a according to the invention in the conical seat bore 21 in the nozzle body 3 added. In the seat bore 21 is the sensor head 19a here by means of the sensor head 19a surrounding wedge pieces 29a . 29b fixed.

With the proposed arrangement, on the one hand, an advantageously simple mounting of the sensor on the fuel injector 1 allows as well as a simple release of the sensor (head) 19a for example for the purpose of reusing it. In addition, advantageously, a reliable seal against fuel gas can be achieved. In particular, it should not be neglected that the possibility is created by this arrangement, a pre-assembled sensor module, which further the coupling module 19c at the sensor head far end of the fiber optic line 19b to provide the fuel injector 1 to be able to use.

In the proposed fuel injector 1 is the sensor head 19a with the surrounding wedge pieces 29a . 29b in particular from the outside, that is from the combustion chamber side A (with respect to the intended arrangement of the injector 1 at a combustion chamber), introduced into the seat bore or inserted and fixed (press fit, explained below in the context of the proposed assembly method).

In the context of the invention, only two wedge pieces are preferred 29a . 29b for fixing the sensor head 19a in the seat bore 19a provided, in particular two half-cone pieces 29a . 29b , As a result, handling during assembly can be facilitated and the seal can be optimized. It is also conceivable, more than two wedge pieces 29a . 29b to use, for example, 3 or 4 wedge pieces. Preferably, the outer circumferential surface of the wedge pieces 29a . 29b Finely machined for a good gas-tight effect.

3a and 3b illustrate details of possible embodiments of the fuel injector 1 closer.

The half-cone pieces are clearly visible 29a . 29b at its nozzle-far end ever a bunch 31 on, which is intended, in the half-cone pieces 29a . 29b recorded sensor head 19a To secure against unintentional axial displacement, especially in the course of installation. The Bund 31 can continue to absorb axial forces, so that a permanently good seal without significant seal wear on the seal partners sensor head 19a and wedge piece 29a . 29b is possible. The sensor head 19a indicates a good seal on the butt joints of the wedge pieces 29a . 29b besides a diameter which is slightly smaller than the inner diameter of the assembled and the sensor head 19a surrounding wedge pieces 29a . 29b ,

Preference is given to grooving 33 on the lateral surface 35 of the sensor head 19a provided surrounding it in the circumferential direction, wherein the grooving 33 is provided in the preferred softer material of the wedge pieces 29a . 29b penetrate and at the sensor head 19a against the wedge pieces 29a . 29b seal, in particular gas-tight. The grooving 33 protrudes, for example, about 0.2 mm from the lateral surface 35 out.

To fall out of the seat bore 21 To avoid lying, the conical slope of the half-cone pieces 29a . 29b ever in the field of self-locking.

3b shows a variant in which, in contrast to the embodiment according to 3a a paragraph 37 at the nozzle distal end of the seat bore 21 which is capable of overstressing, for example cracking, the nozzle body 3 due to the interference fit of the sensor head 19a comprehensive wedge pieces 29a . 29b to avoid (especially due to engine operation). Through the heel or step 37 the possible Einpressweg is limited, the gap s before fixing the sensor head 19a can be adjusted by means of pressing, for example by inserting shims.

4 illustrates various design options of the wedge pieces 29a . 29b even closer.

The wedge pieces 29a . 29b , which are intended, in addition to the fixation of the sensor head 19a also against the wall of the seat bore 21 and the sensor head 19a To seal, to improve their sealing effect circumferentially a ring seal 39 exhibit. Such a ring seal 39 can by means of at least one O-ring 41 , a rubberized bead and / or raised material cuts 43 Be (few micrometers high) be formed, which allow each defined sealing lines with an increased surface pressure, thus a further improved sealing in particular against gas passage (fuel gas). In addition, the use of sealing compound can be provided with which shock and lateral surfaces can be wetted before mounting.

As 4 illustrated further, it may further be preferred that the sensor head 19a in the seat bore 21 fixing wedge pieces 29a . 29b between each other at least one parting line 45 form rugged structure (eg, also toothing), which is designed in particular as a negative / positive structure. The parting line is preferred 45 by fracture separation of a cone body resulting in the wedge pieces 29a . 29b produced. Such a parting line 45 allows easy and accurate pre-assembly, as far as the over the parting line 45 toothed wedge pieces 29a . 29b to prevent each other from slipping.

Furthermore, an excellent sealing effect, in particular in connection with sealing compound, via a respective parting line thus formed 45 achievable.

5 schematically illustrates a fuse element 47 for mounting on the injector 1 ,

The safety pin or locking pin 47 is for placement in a corresponding bore on the injector housing assembly 15a provided to the in the channel 25 received fiber optic strand 19b to prevent slipping and thus abrasion or possible damage. For this purpose is the bolt 47 slotted on the front, Bz. 49 , The bolt 47 also serves the channel 25 after mounting the sensor 19 at the injector 1 seal.

6a to 7b illustrate aspects of the method explained in more detail below for mounting a fuel injector as explained above 1 ,

In a first step of the assembly process, the optical fiber strand 19b with the sensor head 19a ahead of the inlet 27 in the channel 25 pushed in until the sensor head 19a from the conical seat bore 21 exit. It should be noted that when using the above-described prefabricated sensor 19 the length of the fiber optic line 19b is to be measured so that at one point the connection with the coupling module 19c on the housing assembly 15a is ensured while the sensor head 19a at the other end from the seat bore 21 exit. As it exits the nozzle body 3 is provided that the sensor head thereafter about 10 mm from the nozzle body 3 protrudes, see eg. 6a and 7a ,

In a second step of the assembly process according to the invention, see also 6a i. V. m. 6b and 7a i. V. m. 7b , the wedge pieces become 29a . 29b around the sensor head 19a arranged. 6a and 7a illustrate the sensor head 19a immediately before the wedge pieces are placed 29a . 29b , the 6b and 7b the sensor head 19a with the wedge pieces arranged thereon in the second step 29a . 29b , As part of the arrangement of the wedge pieces 29a . 29b become the wedge pieces 29a . 29b with the covenant 31 at the light guide end of the sensor head 19a brought to the plant and at the butt joints 45 accurately merged. In preferred embodiments of the injector 1 in which a grooving 33 at the sensor head 19a is provided, in the second step, one for the penetration of the grooving 33 in the wedge material required (radial) force (after merging the wedge pieces 29a . 29b ) are applied by means of an engagement tool, for example a pair of pliers. Alternatively it can be provided that the force is applied thereto by the insertion itself in the subsequent third step.

In the second step may - for the production of an intended gas tightness - also the attachment of sealant on butt joints or surfaces on the seat bore 21 and / or the gores 29a . 29b and / or the sensor head 19a respectively.

In the third step of the assembly process, the wedge pieces become 29a . 29b with the sensor head received 19a , s. 6b or 7b , in the conical seat bore 21 inserted, see arrow B in 6b , and in this case fixed, ie by pressing. 6c shows the sensor head 19a including wedge pieces 29a . 29b after completing the third step in the seat bore 21 fixed recorded.

Obvious, see arrow B in 6b , the wedge pieces become 29a . 29b with the sensor head received on it 19a inserted in the third step, in particular from the outer / combustion chamber side A in the conical seat bore (axially) and for fixing to the wall of the seat bore 21 pressed. For fixing a press-in force F is provided which corresponds approximately to the force at adjacent cylinder pressure.

As part of the proposed assembly process, a fourth step is provided in which the channel 25 between the seat bore 21 and the inlet 27 is sealed. A seal may, for example, in the manner described above by means of the bolt 47 take place, which in this case in a corresponding bore on the injector (housing) is arranged. Alternatively or additionally, the channel 25 be sealed by means of a backfilling, preferably by means of a fat filling, which can protect the optical fiber strand from vibration and scrubbing.

The third or fourth step below is in particular the attachment of the coupling module 19c (optionally with evaluation unit) on the injector 1 or housing 15a provided, for example in a protective housing 51 , s. 1 ,

8th shows a representation of the fuel injector 1 , on the basis of which the dismantling method will be explained in more detail below.

The inventively proposed method for disassembly of a fuel injector as described above 1 Provides that in the seat bore 21 fixed arrangement of sensor head 19a and the wedge pieces 29a . 29b in a first step with a release pressure from the channel 25 is applied, wherein the release pressure by means of a pressure medium in the channel 25 is initiated. As the pressure medium is particularly preferably provided grease or oil, woneben of course, further print media are conceivable.

With the proposed dismantling method, the previously on the nozzle body 3 fixed sensor head 19a including the wedge pieces 29a . 29b in an advantageous simple manner from the seat bore 21 be disengaged, arrow C in 8th , That is, wherein the release pressure is less than the maximum occurring combustion chamber pressure or as the pressure at which the sensor head 19a including the wedge pieces 29a . 29b was pressed. After removal (d), after removal of the wedge pieces 29a . 29b can the sensor head 19a including the fiber optic line 19b through the seat bore 21 and the channel 25 through the inlet 27 from the fuel injector 1 pulled out and exchanged for example or used elsewhere.

In the context of the proposed dismantling process is further provided, the release pressure in the first step via a in the channel 25 between inlet 27 and seat bore 21 one-branch channel 53 in the channel 25 to initiate and the channel 25 (during the release pressure initiation) between receipt 55 and inlet 27 to block (in particular via sealing bolts 47 ). As a result, the release pressure build-up can be done quickly.

For the admission of the - preferably selectively closable branch channel 53 - With the release pressure, the use of a grease gun, an oil pump or, for example, a hydraulic percussion cylinder (pressure pulse) may be provided in the context of dismantling preferred, Bz. 57 , Such a device is used for the Lösedruckbeaufschlagung with a junction 59 then the pressure channel to be opened 53 connected.

It should also be noted in conclusion that the coefficient of thermal expansion of the cone piece material in the context of the invention is preferably chosen to be greater than or equal to that of the nozzle body material. Thus, the pressing action when heating the nozzle body 3 do not subside, thus a consistently good seal can be achieved.

LIST OF REFERENCE NUMBERS

1

fuel injector

3

nozzle body

3a

near the nozzle

3b

nozzle-far end

5

nozzle needle

7

Axial bore (nozzle space)

9

nozzle assembly

11

closing spring

13

Needle guide sleeve

15a

Single accumulator

15b

valve plate

15c

intermediate plate

15a, b, c

Injektorgehäusebaugruppe

17

Nozzle clamping nut

19

Combustion chamber pressure sensor

19a

sensor head

19b

Optical fiber strand

19c

coupling module

21

seat bore

23

injector cap

25

channel

27

inlet

29a, b

wedge pieces

31

Federation

33

grooving

35

lateral surface

37

step

39

ring seal

41

O-ring

43

material section

45

parting line

47

bolt

49

slot

51

casing

53

Stichkanal

55

Einzweigung

57

contraption

59

junction

Claims (15)

Fuel injector ( 1 ) for an internal combustion engine, wherein the fuel injector ( 1 ) a nozzle body ( 3 ), in which a nozzle needle ( 5 ) of the fuel injector ( 1 ) and on which a nozzle arrangement ( 9 ) of the injector ( 1 ) is formed; wherein with the nozzle body ( 3 ) further comprises an injector housing assembly ( 15a , b, c), characterized in that - the fuel injector ( 1 ) an optical combustion chamber pressure sensor ( 19 ) with a sensor head ( 19a ) and an associated optical fiber strand ( 19b ) having; - wherein the sensor head ( 19a ) in a conical seat bore ( 21 ) in the nozzle body ( 3 ) and in the seat bore ( 21 ) by means of the sensor head ( 19a ) surrounding wedge pieces ( 29a . 29b ) is fixed; - where a channel ( 25 ) for receiving the optical fiber strand ( 19b ) from the seat bore ( 21 ) through the nozzle body ( 3 ) through to an inlet ( 27 ) at the fuel injector ( 1 ). Fuel injector ( 1 ) according to claim 1, characterized in that - the sensor head ( 19a ) together with the wedge pieces ( 29a . 29b ) from an outer / combustion chamber side (A) of the nozzle body ( 3 ) into the seat bore ( 21 ) inserted in the seat bore ( 21 ) is fixed. Fuel injector ( 1 ) according to one of the preceding claims, characterized in that - the conical seat bore ( 21 ) on or adjacent to a nozzle tip ( 23 ) of the nozzle body ( 3 ) is formed. Fuel injector ( 1 ) according to one of the preceding claims, characterized in that - the channel ( 25 ) has over its entire length a formation which is suitable, the sensor head ( 19a ) starting from the inlet ( 27 ) into the seat bore ( 21 ). Fuel injector ( 1 ) according to one of the preceding claims, characterized in that - the sensor head ( 19a ) in the seat bore ( 21 ) fixing wedge pieces ( 29a . 29b ) against the wall of the seat bore ( 21 ) and / or the sensor head ( 19a ) and / or gas-tight. Fuel injector ( 1 ) according to one of the preceding claims, characterized in that - the sensor head ( 19a ) in the seat bore ( 21 ) fixing wedge pieces ( 29a . 29b ) at least one parting line ( 45 ) form a fissured structure and / or at least one parting line ( 45 ), which is produced by means of fracture separation. Fuel injector ( 1 ) according to one of the preceding claims, characterized in that - the sensor head ( 19a ) in the seat bore ( 21 ) fixing wedge pieces ( 29a . 29b ) are two half-cone pieces. Fuel injector ( 1 ) according to one of the preceding claims, characterized in that - the sensor head ( 19a ) on a peripheral surface ( 35 ), which engage in engagement with the wedge pieces ( 29a . 29b ), a raised, continuously circumscribing structuring and / or a grooving ( 33 ) having. Method for assembling a fuel injector ( 1 ) according to one of the preceding claims, characterized in that - in a first step, the optical fiber strand ( 19b ) with the sensor head ( 19a ) ahead of the inlet ( 27 ) into the channel ( 25 ) is inserted until the sensor head ( 19a ) from the conical seat bore ( 21 ) exit; - in a second step, the wedge pieces ( 29a . 29b ) around the sensor head ( 19a ) to be ordered; - in a third step, the wedge pieces ( 29a . 29b ) with the sensor head ( 19a ) in the conical seat bore ( 21 ) are inserted and fixed. Method according to claim 9, characterized in that - the wedge pieces ( 29a . 29b ) with the sensor head ( 19a ) in the third step from an outer / combustion chamber side (A) into the conical seat bore ( 21 ) and / or to a fixation in the seat bore ( 21 ) are pressed. Method according to one of claims 9 and 10, characterized in that - the channel ( 25 ) in a fourth step between the seat bore ( 21 ) and the inlet ( 27 ) is sealed and / or sealed by means of a backfilling and / or by means of a in a receptacle on the injector ( 1 ) received sealing element ( 47 ) is sealed. Method for dismantling a fuel injector ( 1 ) according to one of claims 1 to 8, characterized in that - in the seat bore ( 21 ) fixed wedge pieces ( 29a . 29b ) and the sensor head ( 19a ) in a first step with a release pressure on the part of the channel ( 25 ) be charged; - wherein the release pressure by means of a pressure medium in the channel ( 25 ) is initiated to effect disengagement of the sensor head ( 19a ) together with the wedge pieces ( 29a . 29b ) from the seat bore ( 21 ). A method according to claim 12, characterized in that - is used as the pressure medium fat or oil. Method according to one of claims 12 and 13, characterized in that - the release pressure in the first step via a into the channel ( 25 ) between inlet ( 27 ) and seat bore ( 21 ) branching channel ( 53 ) into the channel ( 25 ), the channel ( 25 ) between acknowledgment ( 55 ) and inlet ( 27 ) is blocked. Internal combustion engine, characterized by a fuel injector ( 1 ) according to one of claims 1 to 8.

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