DE102012203621A1 - fuel injector - Google Patents

Abstract

A fuel injector (1) having an injector (10), a switching valve (20) and a connecting sleeve (30) disposed between the injector (10) and the switching valve (20), the injector at a longitudinal end portion (11) thereof predetermined nozzle outer contour (12) and the switching valve at a longitudinal end portion (21) having a predetermined Ventilaußenkontur (22), and wherein the connecting sleeve has a predetermined sleeve inner contour (33) into which from a first longitudinal end 31 of the connecting sleeve from the injection nozzle with its Nozzle outer contour is fitted positively, so that the injection nozzle is fixed in a defined orientation to the connecting sleeve, and in which from a second longitudinal end (32) of the connecting sleeve from the switching valve with its valve outer contour is positively fitted, so that the switching valve in a defined orientation to the connecting sleeve is fixed.

Description

The invention relates to a multipart fuel injector for an internal combustion engine.

Conventionally known internal combustion engines, such as marine diesel engines, have a plurality of cylinders each having at least one fuel injector associated therewith to supply fuel to the respective cylinder. Such fuel injectors are usually constructed from a plurality of parts or components mounted longitudinally one behind the other, which must be fixed or fixed to one another in a specific orientation (for example with regard to their longitudinal axis and their rotational position).

In the case of fuel injectors known from practice, this alignment of the several components takes place with the aid of so-called dowel pins, which engage in dowel pin bores of the components. Out DE 2 309 134 A For example, such a multi-part fuel injector is known, wherein a nozzle assembly is aligned by a dowel pin to a nozzle holder.

However, dowel pins have the disadvantage that they easily abort or shear during assembly or disassembly of the fuel injector as a result of mechanical overloading, which usually requires extensive repair work on the individual components, in particular with regard to the application of the destroyed dowel pins required.

Another disadvantage of the dowel pins is that, because the dowel holes receiving the dowel pins are usually inserted in sealing surfaces between the components, the dowel pins protrude after mounting from the sealing surfaces, which is why a reworking (eg lapping) of the sealing surfaces only the dowel pins consuming removed Need to become.

The invention has for its object to provide a multi-part fuel injector, wherein the components are aligned in a simpler and easier to maintain.

This is achieved with a fuel injector according to claim 1. Further developments of the invention are defined in the dependent claims.

According to the invention, a fuel injector as the plurality of interconnected components includes a fuel injection injector, a fuel injection controlling valve, and a connection sleeve disposed between the injector and the switching valve, the injector at a longitudinal end portion thereof predetermined nozzle outer contour and the switching valve at a longitudinal end portion thereof having a predetermined outer contour of the valve, and wherein the connecting sleeve has a predetermined sleeve inner contour into which from a first longitudinal end of the connecting sleeve of the injection nozzle with its nozzle outer contour is positively fitted, so that the injector in a defined orientation is set to the connecting sleeve, and in which from a second longitudinal end of the connecting sleeve from the switching valve with its valve outer contour is positively fitted, so that the Switching valve is set in a defined orientation to the connecting sleeve.

In other words, the valve outer contour is adapted to form the sleeve inner contour, so that a first positive shaft-hub connection is created as alignment, and the nozzle outer contour is positively adapted to the sleeve inner contour, so that created a second positive shaft-hub connection as alignment is. Accordingly, the valve outer contour and the nozzle outer contour are each formed complementary to the sleeve inner contour.

The axial cohesion of the individual components of the fuel injector is accomplished as is conventional in the art, e.g. ensured by one or more union nuts, which act on the corresponding annular collars and external threads of the components.

The inventive positive fit mating the nozzle outer contour and the valve outer contour with the sleeve inner contour, the components of the fuel injector are aligned in a particularly simple and easy to maintain each other.

If the components of the fuel injector are to be disassembled and, if necessary, reworked, after release of the axial cohesion, only the shaft-hub connections need to be released via the individual components to be removed from the connection sleeve. There is no need to remove dowel pins for reworking the sealing surfaces.

The fuel injector according to the invention with the shaft-hub connections realized via polygonal profiles is significantly less sensitive to mechanical stress, so that there is less risk of damage to the alignment means during assembly and disassembly.

Furthermore, by the component design described above, the transmission of a much larger torque with, for example, or the union nut (s) possible, which is increasingly necessary in view of constantly increasing injection pressures in order to achieve sufficient tightness.

Preferably, the connection sleeve is dimensioned or configured such that it forms the weakest part of the components. Thus, in the case of mechanical overloading, only the connecting sleeve is destroyed or damaged, so that only this has to be exchanged in a simple manner and without various tools.

According to one embodiment of the invention, the sleeve inner contour can have a different inner diameter at a longitudinal end section matched with the outer contour of the nozzle than at a longitudinal end section matched with the valve outer contour. This embodiment of the invention has the advantage of dimensioning the components injection nozzle and switching valve, taking into account the space available and still be able to fit into the common connecting sleeve.

According to a further embodiment of the invention, the nozzle outer contour and the valve outer contour are fitted so positively into the sleeve inner contour that the injection nozzle and the switching valve in each case with respect to their longitudinal axis and its rotational position defines the connection sleeve, which is in particular a centering connection sleeve, aligned.

In other words, the longitudinal axes of the injection nozzle and the switching valve are aligned and centered by the shaft-hub connections to the longitudinal axis of the connecting sleeve and thus to each other and also in their respective rotational positions about the longitudinal axes and thus.

According to yet another embodiment of the invention, the sleeve inner contour has a polygonal shape. Such a polygon shape, as it is then to be provided in a complementary manner also on the nozzle outer contour and on the valve outer contour, is e.g. can be produced by non-circular or non-circular grinding or by milling.

Preferably, the polygonal shape is at least triangular (such as in Gleichdickform P3G after DIN 32711 ) and in particular hexagonal or heptagonal.

According to one embodiment of the invention, the sleeve inner contour is formed symmetrically with respect to the longitudinal axis of the connecting sleeve.

In this case, a first projection-recess fitting is preferably provided between the sleeve inner contour and the nozzle outer contour, which defines a single possible rotational orientation of the injection nozzle to the connection sleeve, and between the sleeve inner contour and the valve outer contour, a second projection-recess-fitting is provided only possible Drehausrichtung the switching valve defined to the connection sleeve.

In this way, a clear rotational positioning between the injector, the switching valve and the connecting sleeve is created.

According to an alternative embodiment of the invention, the sleeve inner contour is formed asymmetrically with respect to a longitudinal axis of the connecting sleeve.

In this case, the polygon-shaped polygon shape preferably has at least one side that has a different length than the other polygonal-shape sides. More preferably, the polygon shape has a first side smaller in length than the other sides of the polygon shape and a second side longer in length than the other sides of the polygon shape.

In this way, a clear rotational positioning between the injection nozzle, the switching valve and the connecting sleeve is created here.

According to yet another embodiment of the invention, a fuel throttle is positively fitted in the sleeve inner contour between the injection nozzle and the switching valve. In other words, a throttle outer contour is adapted in a form-fitting manner to the sleeve inner contour or is designed to be complementary to the sleeve inner contour, so that a third form-fitting shaft-hub connection is created.

Between the throttle outer contour and the sleeve inner contour can be provided in the case of a symmetrical design of this to the longitudinal axis of a projection-recess-fit. In the case of an asymmetrical design of the sleeve inner contour to the longitudinal axis, the throttle outer contour simply needs to be formed only complementary to this.

Thus, a clear rotational positioning is achieved with respect to the fuel injector to the other components of the fuel injector also with respect to the fuel throttle.

Preferably, all shaft-hub connections or positive fits are designed as a slight clearance fit or as a transition fit.

According to the invention, an internal combustion engine, in particular a marine diesel engine, with a fuel injector according to one, several or all of the previously described embodiments of the invention is provided in every possible combination.

In conclusion, according to embodiments of the invention, centering and unambiguous positioning (i.e., a defined orientation) of the injector and, optionally, fuel choke is provided to the switching valve of a fuel injector with switching valve, the alignment being accomplished by means of a polygonal profile.

Through the centering sleeve or connecting sleeve as a connecting piece between the injection nozzle, the switching valve and possibly the fuel throttle of a fuel injector with switching valve dowels are superfluous. This reduces the number of additional parts required for alignment from four to one.

The breaking or shearing of dowel pins in case of mechanical overload during disassembly or assembly entailed a complicated repair of the switching valve or the injection nozzle during the application of the destroyed dowel pins. In the case of mechanical overloading of the connecting sleeve, however, replacement is possible without further tools.

By performing the polygonal profile as axisymmetric geometry with a projection-recess fit (such as an alignment of a dowel pin and an associated dowel recess transverse to the longitudinal direction of the connection sleeve) or as a single-ended geometry, a unique positioning or alignment of the injector, the fuel throttle, and the switching valve possible.

The prior art dowel pins have often been shown to be overloaded in practice. With the same size of the injection nozzle, a higher torque can be transmitted via the polygonal connection than via the dowel pins previously used in the prior art.

The alignment (preferably including centering) of the injection nozzle relative to the fuel throttle and the switching valve by means of a polygonal shaft-hub connection, such as the shaft-hub connection - polygonal profile P3G ( DIN 32711 ). By slightly different modification of the radii at least two corners of the at least triangular polygonal profile or by providing an axisymmetric profile with a centering pin or an asymmetrical profile, such as a hexagon with at least one shortened side L - Y and at least one extended side L + X (preferred X = Y), accidental mis-assembly, which would be possible by, for example, a 120 degree rotation about the longitudinal axis of the components of the fuel injector, can be excluded. Thus, the omission of the dowel pins in their original form is possible.

The invention expressly extends to such embodiments, which are not given by combinations of features of explicit back references of the claims, whereby the disclosed features of the invention - as far as is technically feasible - can be combined with each other.

In the following the invention will be described with reference to preferred embodiments and with reference to the accompanying figures.

1 shows an exploded perspective view of a fuel injector according to an embodiment of the invention.

2 shows a perspective view of a connecting sleeve of a fuel injector according to another embodiment of the invention.

3 shows a cross-sectional view and end view of the connecting sleeve of 2 ,

4 shows a longitudinal sectional view of the connecting sleeve of 2 , seen along a line AA in 3 ,

1 shows an exploded perspective view of a trained according to a first embodiment of the invention fuel injector 1 a here designed as a marine diesel engine internal combustion engine (not fully shown).

The fuel injector 1 has an injection nozzle 10 for injecting fuel (here diesel fuel), a switching valve 20 for controlling (allowing / inhibiting) the injection of fuel and a connecting sleeve or centering sleeve 30 on that between the injector 10 and the switching valve 20 is arranged.

The injector 10 points to one of the connection sleeve 30 facing longitudinal end portion 11 this one predetermined nozzle outer contour 12 on, and the switching valve 20 points to one of the connection sleeve 30 facing longitudinal end portion 21 whose a predetermined valve outer contour 22 on.

The connection sleeve 30 in turn has a predetermined sleeve inner contour 33 on, in from a first longitudinal end 31 the connection sleeve 30 out of the injector 10 with its nozzle outer contour 12 is fitted form-fitting, so that the injection nozzle 10 in a defined orientation to the connection sleeve 30 is fixed.

In the sleeve inner contour 33 is also from a second longitudinal end 32 the connection sleeve 30 out of the switching valve 20 with its valve outer contour 22 fitted in a form-fitting manner, so that the switching valve 20 in a defined orientation to the connection sleeve 30 is fixed.

In other words, the valve outer contour 22 positive fit to the sleeve inner contour 33 adapted so that a first positive shaft-hub connection is provided as an alignment, and is the nozzle outer contour 12 positive fit to the sleeve inner contour 33 adjusted so that a second positive shaft-hub connection is created as alignment.

Accordingly, the valve outer contour 12 and the nozzle outer contour 22 each complementary to the sleeve inner contour 33 educated.

In addition, in the sleeve inner contour 33 between injector 10 and switching valve 20 a fuel throttle 40 in a defined orientation to the connection sleeve 30 firmly fitted form fit.

In other words, a choke outer contour 41 the fuel throttle 40 positive fit to the sleeve inner contour 33 adapted or complementary to the sleeve inner contour 33 formed, so that a third positive shaft-hub connection is provided as alignment.

Preferably, all shaft-hub connections or positive fits are designed as a slight clearance fit or as a transition fit.

How out 1 can be seen, the injector 10 a longitudinal axis L1, the switching valve 20 a longitudinal axis L2, the connecting sleeve 30 a longitudinal axis L3 and the fuel throttle 40 a longitudinal axis L4.

According to the invention, the nozzle outer contour 12 , the valve outer contour 22 and the throttle outer contour 41 so form-fitting in the sleeve inner contour 33 fitted that injector 10 , the switching valve 20 and the fuel throttle 40 each with respect to their longitudinal axis L1, L2 and L4 and their rotational position about the respective longitudinal axis L1, L2 and L4 defines the connection sleeve 30 are aligned. In other words, the longitudinal axes L1, L2 and L4 of the injection nozzle 10 , the switching valve 20 and the fuel throttle 40 through the shaft-hub connections to the longitudinal axis L3 of the connection sleeve 30 and thus to each other and also in their respective rotational positions about the longitudinal axes L1, L2 and L4 and thus aligned or centered.

To realize the alignment, the valve outer contour 12 , the nozzle outer contour 22 and the throttle outer contour 41 each have a polygonal shape and has the sleeve inner contour 33 one to these outer contours (valve outer contour 12 , Nozzle outer contour 22 and throttle outer contour 41 ) complementary polygon shape. The inner and outer polygonal shapes can be produced for example by non-circular or non-circular grinding or by milling.

According to the invention, the respective polygonal shapes are the components of the fuel injector 1 at least triangular and according to 1 especially designed with a heptagon.

The axial (in the longitudinal direction) cohesion of the individual components of the fuel injector 1 As is conventional in the art, for example, by one or more union nuts (not shown), the corresponding ring collars (such as a collar 13 the injector 10 ) and external threads (not shown) of the components attack guaranteed.

Although in 1 not shown, according to an embodiment of the invention, the sleeve inner contour 33 at one with the nozzle outer contour 12 matched longitudinal end section 31.1 this one other inner diameter than at one with the valve outer contour 22 matched longitudinal end section 32.1 have this. This embodiment of the invention has the advantage, in particular the components injection nozzle 10 and switching valve 20 dimensioning taking into account the space available and still in the common connection sleeve 30 to be able to fit in

How out 1 can be seen, the respective polygon shapes (valve outer contour 12 , Nozzle outer contour 22 , Sleeve inner contour 33 and throttle outer contour 41 ) of the components of the fuel injector 1 each formed asymmetrically with respect to their longitudinal axis L1, L2, L3 and L4, respectively, to a clear rotational positioning between the injection nozzle 10 , the switching valve 20 , the fuel throttle 40 and the connection sleeve 30 to ensure. In other words, the components of the fuel injector 1 only in a single predefined rotary positioning in the connecting sleeve 30 used.

In detail, each polygon shape has a plurality of sides S, S ', S "and these connecting corners E and at least one side S', S" (in FIG 1 three sides), which has a different length than the other sides S of the polygonal shape.

According to 1 For example, each polygon shape has three sides S ', S "that are smaller in length than the other sides S of the polygon shape, with one side S" of these smaller length sides S', S "being shorter in length than the others Has sides S 'of this smaller length formed sides S', S '' of the polygonal shape.

The 2 to 4 show views of a formed according to a second embodiment of the invention connecting sleeve 30a a fuel injector 1a (not fully shown) of a designed as a marine diesel engine internal combustion engine (not fully shown).

The fuel injector 1a According to the second embodiment of the invention is identical to the fuel injector except for some differences 1 formed according to the first embodiment of the invention. Therefore, only these differences are shown below, with the same or similar components as in 1 are denoted by the same or similar reference numerals, and wherein the reference numerals of modified components, the small letter "a" is readjusted. Like from the 2 - 4 As can be seen, the respective polygon shapes are the components of the fuel injector 1a at least triangular and here in particular hexagonal formed.

The respective polygon shapes (valve outer contour, nozzle outer contour, inner sleeve contour 33a and throttle outer contour) of the components of the fuel injector 1a are again each formed asymmetrically with respect to their longitudinal axis to a clear rotational positioning between the injection nozzle, the switching valve, the fuel throttle and the connecting sleeve 30a to ensure. These are the components of the fuel injector 1a only in a single predefined rotary positioning in the connecting sleeve 30a used. In detail, each polygon shape has the components of the fuel injector 1a a plurality of sides S, S ', S''and these connecting corners E and at least one side S', S '' (in the 2 - 4 two sides), which has a different length than the other sides S of the polygonal shape.

According to the 2 - 4 indicates each polygon shape of the components of the fuel injector 1a a first side S '' having a smaller length (L - Y) than the other sides S of the polygonal shape, and a second side S 'having a greater length (L + X) than the other sides S (having the Length dimension L) of the polygonal shape. The length dimension X is preferably equal to the length dimension Y.

According to variations of the first and second embodiments of the invention not shown in the figures, the respective polygonal shapes (valve outer contour, nozzle outer contour, inner sleeve contour and throttle outer contour) may be formed symmetrically with respect to their longitudinal axes.

In this case, a first projection-recess-fit is provided between the sleeve inner contour and the nozzle outer contour, which defines a single possible rotational orientation of the injection nozzle to the connection sleeve. Furthermore, a second projection-recess fit is provided between the sleeve inner contour and the valve outer contour, which defines a single possible rotational orientation of the switching valve to the connecting sleeve. Finally, a projection-recess fit is then also provided between the throttle outer contour and the sleeve inner contour, which defines a single possible rotational alignment of the fuel throttle to the connecting sleeve.

Each projection-recess fit may be e.g. in the form of an arrangement of a depthwise extending transversely to the longitudinal axis (of injection nozzle, switching valve or fuel throttle) in the respective outer contours Passstiftausnehmung and a transverse to the longitudinal axis radially inwardly from the inner sleeve contour projecting into the Passstiftausnehmung engaging dowel. Preferably, the passport recess has an open end in the longitudinal direction of the respective component, via which the dowel pin can be pushed into the respective dowel recess when inserting the component into the connection sleeve.

LIST OF REFERENCE NUMBERS

1

 fuel injector

1a

 fuel injector

10

 injection

11

 longitudinal end

12

 Nozzle outer contour

13

 collar

20

 switching valve

21

 longitudinal end

22

 Valve outer contour

30

 connecting sleeve

30a

 connecting sleeve

31

 longitudinal end

31.1

 longitudinal end

31.1a

 longitudinal end

32

 longitudinal end

32.1

 longitudinal end

32.1a

 longitudinal end

33

 Sleeve inner contour

33a

 Sleeve inner contour

40

 Fuel throttle

41

 Throttle outer contour

L1, L2

 longitudinal axis

L3, L4

 longitudinal axis

L

 measure of length

X, Y

 measure of length

S, S ', S' '

 page

e

 corner

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2309134 A [0003]

Cited non-patent literature

• DIN 32711 [0020]
• DIN 32711 [0037]

Claims (10)

Fuel injector ( 1 ; 1a ) with an injection nozzle ( 10 ) for injecting fuel, a switching valve ( 20 ) for controlling the injection of fuel and a connecting sleeve ( 30 ; 30a ), which between the injection nozzle ( 10 ) and the switching valve ( 20 ) is arranged, wherein the injection nozzle ( 10 ) at a longitudinal end portion ( 11 ) this a predetermined nozzle outer contour ( 12 ) and the switching valve ( 20 ) at a longitudinal end portion ( 21 ) whose a predetermined valve outer contour ( 22 ), and wherein the connection sleeve ( 30 . 30a ) a predetermined sleeve inner contour ( 33 ; 33a ), in which from a first longitudinal end ( 31 ) of the connection sleeve ( 30 . 30a ) from the injection nozzle ( 10 ) with its nozzle outer contour ( 12 ) is fitted form-fitting, so that the injection nozzle ( 10 ) in a defined orientation to the connection sleeve ( 30 . 30a ) and in which a second longitudinal end ( 32 ) of the connection sleeve ( 30 . 30a ) from the switching valve ( 20 ) with its valve outer contour ( 22 ) is fitted form-fitting, so that the switching valve ( 20 ) in a defined orientation to the connection sleeve ( 30 . 30a ). Fuel injector ( 1 ; 1a ) according to claim 1, wherein the nozzle outer contour ( 12 ) and the valve outer contour ( 22 ) so positively in the sleeve inner contour ( 33 ; 33a ) are fitted so that the injection nozzle ( 10 ) and the switching valve ( 20 ) in each case with regard to their longitudinal axis (L1, L2) and their rotational position defined to the connecting sleeve ( 30 . 30a ) are aligned. Fuel injector ( 1 ; 1a ) according to claim 1 or 2, wherein the sleeve inner contour ( 33 ; 33a ) has a polygon shape. Fuel injector ( 1 ; 1a ) according to claim 3, wherein the polygonal shape is at least triangular, in particular hexagonal or heptagonal. Fuel injector ( 1 ; 1a ) according to claim 3 or 4, wherein the sleeve inner contour ( 33 ; 33a ) symmetrically with respect to a longitudinal axis (L3) of the connecting sleeve ( 30 . 30a ) is trained. Fuel injector ( 1 ; 1a ) according to claim 5, wherein between the sleeve inner contour ( 33 ; 33a ) and the nozzle outer contour ( 12 ) is provided a first projection-recess-fitting, which a single possible Dreichterichtung the injection nozzle ( 10 ) to the connection sleeve ( 30 ; 30a ), and wherein between the sleeve inner contour ( 33 ; 33a ) and the valve outer contour ( 22 ) is provided a second projection-recess-fit, which a single possible Drehausrichtung of the switching valve ( 20 ) to the connection sleeve ( 30 ; 30a ) Are defined. Fuel injector ( 1 ; 1a ) according to claim 3 or 4, wherein the sleeve inner contour ( 33 ; 33a ) asymmetrically with respect to a longitudinal axis (L3) of the connecting sleeve ( 30 ; 30a ) is trained. Fuel injector ( 1 ; 1a ) according to claim 7, wherein the polygonal shape has a plurality of sides (S, S ', S'') and at least one side (S', S '') having a different length than the other sides (S) of the polygonal shape , Fuel injector ( 1a ) according to claim 8, wherein the polygon shape has a first side (S '') having a smaller length than the other sides (S) of the polygonal shape, and a second side (S ') having a greater length than the other sides (S) has the polygonal shape. Fuel injector ( 1 ; 1a ) according to one of claims 1 to 9, wherein in the sleeve inner contour ( 33 ; 33a ) between injector ( 10 ) and switching valve ( 20 ) a fuel throttle ( 40 ) is fitted form-fitting.

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