EP0604741A2 - Swirl nozzle for spraying a liquid - Google Patents

Abstract

In order to improve a swirl nozzle for spraying a liquid, with a swirl chamber rising above a swirl-chamber bottom and narrowing to a nozzle-outlet orifice located opposite the swirl-chamber bottom, with at least one swirl channel opening into the swirl chamber in a manner offset laterally relative to a mid-axis of the latter, and with a swirl parameter of 1, in such a way that the swirl nozzle allows an increase in the entry swirl pulse, along with the same or lower swirl losses, it is proposed that there rises from the swirl-chamber bottom a displacement body which prevents the formation of an air core in a swirl-chamber region located near the bottom and which is arranged concentrically relative to the mid-axis and has, in the part located near the bottom, an outside diameter corresponding at least to a diameter of the nozzle-outlet orifice. <IMAGE>

Description

The invention relates to a swirl nozzle for atomizing a liquid with a swirl chamber rising above a swirl chamber floor and tapering towards a nozzle outlet opening opposite the swirl chamber floor, with at least one swirl channel offset laterally with respect to a central axis of the swirl chamber and having a swirl parameter of> 1 a displacement body which rises from the swirl chamber base and prevents the formation of an air core in a base-side swirl chamber region, which is arranged concentrically to the central axis and has an outer diameter in the base part which corresponds to at least one diameter of the nozzle outlet opening.

In such known swirl nozzles, the liquid to be atomized flows through the swirl channel, preferably in a tangential direction into the swirl chamber, in which it moves in the direction of the central axis of the swirl chamber, increasing its peripheral speed. Since the liquid cannot flow to the central axis with a swirl parameter of the swirl nozzle of> 1 due to the centrifugal forces, an air core extends around the central axis, which extends over the entire height of the swirl chamber, around which the liquid flows and thus passes through the nozzle outlet opening as a rotating liquid film ring and then forms a liquid film cone, which due to its own instability disintegrates into small liquid droplets.

A swirl nozzle of the type mentioned in the opening paragraph is disclosed in FR-A-1 560 603. This also shows a swirl nozzle in which the swirl parameter is very likely to be> 1 and which also has a conical displacement body.

The swirl nozzles known from US-A-2,065,161, GB-A-162 172 and DE-A-175 561 are not relevant to the present invention in that the swirl parameter is <1 or not at all in accordance with these constructions Air core results.

In US-A-2,065,161, for example, the inventor determined a swirl parameter of <0.7.

A swirl parameter <0.5 was determined in GB-A-162 172 and in DE-A-175 561 it can be assumed that there is no air core at all. In addition, it emerges from this document that the cone body serves to change the opening angle of the spray cone, which speaks against the displacement of an air core. In addition, a swirl parameter of approximately 0.4 was determined.

In order to achieve liquid droplets that are as fine as possible, a large air core diameter is desired, which can only be achieved with a correspondingly large input swirl pulse of the liquid jet. On the one hand, this could be increased by increasing the tangential velocity of the liquid jet. However, this tangential speed is practically determined by a sensibly maximum pressure and a minimal cross section due to the risk of blockage. On the other hand the input swirl pulse could be increased by increasing the so-called swirl channel eccentricity, that is to say the distance of a center line of the swirl channel from the central axis. In the known swirl nozzles, however, this measure increases the swirl losses which depend on an air core diameter and an air core length, so that in practice no improvements are possible with regard to the swirl channel eccentricity in the known swirl nozzles.

The invention is therefore based on the object of improving a swirl nozzle of the generic type in such a way that it permits an increase in the input swirl pulse with constant or lower swirl losses.

This task in the case of a swirl nozzle for atomizing a liquid with a swirl chamber rising above a swirl chamber floor and tapering towards a nozzle outlet opening opposite the swirl chamber floor, with at least one swirl channel offset laterally with respect to a central axis of the swirl chamber and having a swirl parameter of> 1 a displacement body rising from the swirl chamber floor and preventing the formation of an air core in a floor-side swirl chamber area, which is arranged concentrically to the central axis and has an outer diameter in the bottom part which corresponds to at least one diameter of the nozzle outlet opening, the swirl nozzle having an outer body which has the nozzle outlet opening and comprises a recess adjoining this, extending along the central axis and having a larger cross section with increasing extension, and in this recess form-fitting an inner body can be used with a swirl chamber floor perpendicular to the central axis, so that the swirl chamber floor and wall surfaces of the recess lying between the latter and the nozzle outlet opening limit the swirl chamber, achieved according to the invention in that the wall surfaces of the recess are formed by lateral surfaces of truncated cones that are coaxial with the central axis, that a partial area the wall surfaces of the recess form a conical seat surface for the frustoconical inner body and that the conical seat surface has a smaller cone angle than a further portion of the swirl chamber wall adjoining the nozzle outlet opening.

As a result, the swirl nozzle according to the invention can be manufactured particularly easily, since a conical surface can be easily produced using conventional methods.

Furthermore, in the swirl nozzle according to the invention, the height of the swirl chamber and thus the length of the air core can be kept as small as possible that the swirl chamber wall forms a conical surface with the largest possible cone angle, but which would result in a poor positive fit of the inner part, so that the wall surfaces of the recess which form the conical seat surface for the frustoconical inner part has a smaller cone angle than a portion of the swirl chamber wall adjoining the nozzle outlet opening.

In particular in connection with the last-mentioned embodiment of the swirl nozzle according to the invention, it has proven to be expedient if the displacement body is a Is a cone with a cone angle corresponding to the section adjoining the nozzle outlet opening.

In the context of the solution according to the invention, it has proven to be particularly advantageous if the displacement body extends with a mean diameter corresponding at least to the diameter of the nozzle outlet openings over at least approximately half the height of the swirl chamber in the direction of the nozzle outlet opening.

However, it is even more favorable if the displacement body extends over at least approximately two thirds of the height of the swirl chamber with a mean diameter corresponding at least to the diameter of the nozzle outlet openings.

In order to achieve flow conditions in the swirl chamber which are as uniform as possible, it has proven to be extremely expedient if a surface of the displacement body facing an outer swirl chamber wall has a constant distance from it in each cross-sectional plane with respect to the central axis all around.

In a development of the above-mentioned solution, it is expedient if, in a part of the displacement body facing the nozzle outlet opening, the surfaces facing the swirl chamber wall run at a constant distance therefrom, so that the swirl chamber in this area is an annular channel with a constant hydraulic diameter, which distributes the pressure evenly circulating liquid causes.

When dimensioning the distance, it has proven to be particularly advantageous if the distance corresponds approximately to a width of the swirl channel.

With regard to the shape of the swirl chamber, it has proven to be expedient if it is designed to be rotationally symmetrical to the central axis, so that this has the consequence that the displacement body must also be designed to be rotationally symmetrical.

In the exemplary embodiment described so far, it was not explained in more detail how the swirl channels open into the swirl chamber. The junction can be provided as desired. With regard to the production of a swirl nozzle according to the invention, however, it has proven to be advantageous if the orifices of the swirl channels are located in an annular region of the swirl chamber base which extends around the displacement body.

Since, as already explained at the outset, as large an eccentricity as possible of the swirl channels opening out is desired, in a preferred exemplary embodiment it is provided that a width of the annular region corresponds to an extension of the mouth opening from an outer edge of this region in the radial direction inwards, that is to say that this ring-shaped area is only so wide that it can accommodate the opening of the swirl channel.

As already described at the beginning, it is expediently provided that the swirl channel in the mouth region with its center line is essentially tangential to the swirl chamber wall runs. A particularly large swirl channel eccentricity can, however, be achieved if the swirl channel with a mouth opening designed as a segment of a circle opens into the swirl chamber along an outer edge region of the swirl chamber floor, since in this case the radial extent of the mouth opening in the direction of the central axis only corresponds to a width of the swirl channel and the liquid jet thus flows along the swirl chamber wall when entering the swirl chamber and flows into the swirl chamber at the greatest possible distance from the central axis for a given swirl chamber diameter.

Particularly with a view to making the swirl nozzle according to the invention as simple as possible, it is expedient if the swirl duct runs in a straight line from a pressure chamber to the swirl chamber. However, it is even more advantageous if the swirl channel runs spirally with respect to the central axis from a pressure chamber to the swirl chamber, since in this case the swirl channel can be provided with a smaller slope with respect to the central axis, and thus based on a constant flow rate of the liquid in this swirl channel this emerging jet of liquid has the largest possible tangential velocity component in a plane perpendicular to the central axis and the smallest possible velocity component parallel to the central axis.

In all cases, the swirl channels will preferably have a substantially constant cross section.

It is also advantageous if the displacement body is provided with a return bore.

The provision of the displacement body according to the invention has the advantage that the swirl chamber in the bottom area has the shape of an annular space surrounding the displacement body, so that no air core can form in this area, which leads to the swirl losses already described. Thus, in the swirl nozzle according to the invention, the swirl channel eccentricity can be selected to be larger without overall increasing the swirl losses, so that a good atomization quality of the swirl nozzles according to the invention can be achieved. It is even possible to increase the swirl channel eccentricity to such an extent that the tangential velocity of the liquid jet can be reduced and thus a cross section of the swirl channels can be chosen larger, so that the risk of clogging of the nozzle is reduced.

However, it is also within the scope of the present invention if the displacement body is provided with a central return bore, the further features of which are described, for example, in German patent application P 37 03 075.2.

As an alternative to arranging the return bore centrally to the displacement body, the solution according to the invention offers the possibility of arranging the return bore eccentrically to the displacement body. It is particularly advantageous here if the return bore is arranged at a distance from the central axis of the displacement body, which is at least one radius of the nozzle outlet opening corresponds so that a residual air core possibly arising in the area of the outlet opening does not stand above the return bore and thus influences it.

Finally, it is expedient if the return bores are arranged at a distance from the central axis which is smaller than the distance from the mouth opening of the swirl channels.

Fig. 1

einen Schnitt durch eine bekannte Dralldüse;

Fig. 2

eine Ansicht in Richtung des Pfeiles A in Fig. 1;

Fig. 3

einen Schnitt durch ein erstes Ausführungsbeispiel der erfindinngsgemäßen Dralldüse;

Fig. 4

eine Ansicht in Richtung des Pfeiles B in Fig. 3;

Fig. 5

eine perspektivische Darstellung eines erfindungsgemäßen Innenteils;

Fig. 6

einen Schnitt ähnlich Fig. 3 durch ein zweites Ausführungsbeispiel;

Fig. 7

eine perspektivische Ansicht ähnlich Fig. 5 des zweiten Ausführungsbeispiels;

Fig. 8

einen Schnitt ähnlich Fig. 3 durch ein drittes Ausführungsbeispiel;

Fig. 9

eine Ansicht in Richtung des Pfeiles C in Fig.8;

Fig. 1O

einen Schnitt ähnlich Fig. 3 durch ein viertes Ausführungsbeispiel;

Fig. 11

eine Ansicht in Richtung des Pfeiles D in Fig.1O;

Fig. 12

einen Schnitt ähnlich Fig. 3 durch ein fünftes Ausführungsbeispiel und

Fig. 13

eine Ansicht in Richtung des Pfeiles E in Fig. 12.

Fig. 14

eine Ansicht ähnlich Fig. 3 eines sechsten Ausführungsbeispiels;

Fig. 15

eine Draufsicht ähnlich Fig. 4 auf das sechste Ausführungsbeispiel;

Fig. 16

einen Schnitt längs Linie 16-16 in Fig.15;

Fig. 17

eine Ansicht ähnlich Fig. 3 eines siebten Ausführungsbeispiels;

Fig. 18

eine Draufsicht ähnlich Fig. 4 auf das siebte Ausführungsbeispiel.

Further features and advantages are the subject of the following description and the drawing of some exemplary embodiments. The drawing shows:

Fig. 1

a section through a known swirl nozzle;

Fig. 2

a view in the direction of arrow A in Fig. 1;

Fig. 3

a section through a first embodiment of the swirl nozzle according to the invention;

Fig. 4

a view in the direction of arrow B in Fig. 3;

Fig. 5

a perspective view of an inner part according to the invention;

Fig. 6

a section similar to Figure 3 through a second embodiment.

Fig. 7

a perspective view similar to Figure 5 of the second embodiment.

Fig. 8

a section similar to Figure 3 through a third embodiment.

Fig. 9

a view in the direction of arrow C in Figure 8;

Fig. 10

a section similar to Figure 3 through a fourth embodiment.

Fig. 11

a view in the direction of arrow D in Fig.1O;

Fig. 12

a section similar to FIG. 3 through a fifth embodiment and

Fig. 13

a view in the direction of arrow E in Fig. 12.

Fig. 14

a view similar to Figure 3 of a sixth embodiment.

Fig. 15

a plan view similar to Figure 4 of the sixth embodiment.

Fig. 16

a section along line 16-16 in Figure 15;

Fig. 17

a view similar to Figure 3 of a seventh embodiment.

Fig. 18

a plan view similar to FIG. 4 of the seventh embodiment.

A swirl nozzle for atomizing a liquid, as is known from the prior art, shown in FIGS. 1 and 2, shows an outer body 10, from the outside 12 of which a nozzle outlet opening 14 designed as a cylindrical bore extends into an interior of the outer body 10 extends into it. This nozzle outlet opening 14 is followed by an essentially conical recess 16, the wall surfaces 18 of which form the lateral surfaces of a truncated cone which is arranged coaxially to the nozzle outlet opening 14 and is rotationally symmetrical with respect to a central axis 20. An inner body 22 is inserted into this recess 16, which has a circular-cylindrical region 24, to which a frustoconical region 26 connects, the base 28 of which is identical to the circular surface. This frustoconical region 26 is formed in such a way that lateral surfaces 30 are the same section of the conical surface on which the wall surfaces 18 of the recess 16 also lie. Thus, the inner body 22 is held in a form-fitting manner in the recess 16 by a conical seat, the region of the wall surfaces 18 of the recess 16, in which the lateral surfaces 30 of the frustoconical region 26 of the inner body 22 abut, are referred to as conical seat surfaces 32 of the recess 16.

A surface of the frustoconical region 26 of the inner body 22 opposite the base surface 28 and oriented parallel thereto extends perpendicularly to the central axis 20O and forms a swirl chamber floor 34. A region of the recess 16 lying above this swirl chamber floor 34 is referred to as the swirl chamber 36, which is the swirl chamber 36 delimiting wall surfaces 18 of the recess 16 are referred to as swirl chamber walls 38. A space enclosed by the recess 16 and arranged on a side of the inner body 22 opposite the swirl chamber 36 is referred to as the pressure space 40, in which the liquid intended for atomization is kept under pressure. A plurality of swirl channels 42 lead from this pressure chamber 40 into the swirl chamber 36, whereby these swirl channels 42, as can be seen in particular from FIG. 2, are preferably designed as notches in the lateral surfaces 30, which have a rectangular and approximately square cross-section in the pressure chamber 40 open in the circular cylindrical region 24 of the inner body 22 and open in the swirl chamber 36 in the region of the swirl chamber base 34 and preferably in a region radially outward with respect to the central axis 20, a center line 44 of each swirl duct 42, at least in the region of an opening 46 thereof, in the swirl chamber base 34 has a distance e from the central axis 20 and thus from the mouth opening 46 a liquid jet 48 emerges which, when leaving the orifice 46, lies in a plane 50 which is parallel to the central axis 20 and extends at a distance e therefrom and in this case has a speed component 52 parallel to the swirl chamber floor 34 and a speed component 54 parallel to the central axis 20. The distance e is generally referred to as the eccentricity e of the swirl nozzle. Thus, in the swirl chamber 36, a fluid vortex 56 arises about the central axis 20, in the center of which a cylinder-like air core 58 remains coaxial to the central axis 20, around which the fluid vortex 56 flows, so that a fluid film cone 6O which emerges from the nozzle outlet opening 14 finally its own instability breaks down into small liquid droplets.

wobei γ die Steigung der Drallkanäle 42 gegenüber dem Drallkammerboden 34 bedeutet, der Austrittsradius τ_a der Radius der der Düsenaustrittsöffnung 14 ist und f₁, f₂, f₃, f₄ die Querschnittsflächen der Drallkanäle 42 sind. Eine Definition des Drallparameters ist außerdem aus dem Forschungsbericht DFVLR-FB 87-25 (ISSN O171-1342), Seite 22 zu entnehmen.A swirl parameter S _o of such a nozzle is defined as follows

where γ is the slope of the swirl channels 42 relative to the swirl chamber base 34, the exit radius τ _{a is} the radius of the nozzle outlet opening 14 and f₁, f₂, f₃, f₄ are the cross-sectional areas of the swirl channels 42. A definition of the swirl parameter can also be found in the research report DFVLR-FB 87-25 (ISSN O171-1342), page 22.

An air core always occurs with a swirl nozzle if the swirl parameter So> 1. Alternatively, the occurrence of an air core can also be made dependent on the ratio of the sum of all swirl channel areas f 1, f 2, f 3, f₄ to the cross-sectional area of the nozzle outlet opening, which should be less than 5 for this purpose.

Based on this known design of a known swirl nozzle, a first exemplary embodiment of a swirl nozzle according to the invention, shown in FIGS. 3 to 5, shows the same parts and features, which are therefore also provided with the same reference numerals in FIGS. 3 to 5.

With regard to the description, reference is made to the above statements.

In contrast to the known swirl nozzle, in the first exemplary embodiment of the swirl nozzle according to the invention, a displacement body 62 is placed on the swirl chamber base 34, which has a cylindrical base 64, to which a cone-shaped tip 66 adjoins, with a base 68 of the cone-shaped tip 66 having the end face 70 of the cylindrical base 64 facing this is identical.

The entire displacement body 62 is designed to be rotationally symmetrical with respect to the central axis 20, the cylindrical base 64 extending in the radial direction with respect to the central axis 20 up to the mouth openings 46 of the swirl channels 42, so that the displacement body 62 covers the swirl chamber base 34 in its central region 72 and a cylindrical outer surface 74 of the cylindrical base 64 delimits a free annular region 76 of the swirl chamber base 34 towards the inside.

Thus, the cylindrical outer surface 74 of the cylindrical base and a section of the swirl chamber wall 38 arranged on the opposite side of the swirl chamber bottom as well as the circular region of the swirl chamber base 34 form an annular space 80 into which the liquid jet 48 is injected tangentially to the outer surface 74 of the cylindrical base 64.

As shown in FIG. 3, a surface 82 of the conical tip 66 designed as a conical surface preferably runs at a distance b from and parallel to an outlet-side section 84 of the swirl chamber wall 38, the width b preferably corresponding approximately to a width b of the swirl channels 42 .

Thus, in the first exemplary embodiment of the swirl nozzle according to the invention, the swirl chamber 36 comprises an annular space 8O arranged on the swirl chamber bottom which is followed by a conical jacket-shaped space 86 delimited by the conical surface 82 of the displacement body 62 and the outlet-side section 84 of the swirl chamber wall, which in turn merges into the cylindrical bore of the nozzle outlet opening 14.

It was thus achieved by the displacement body 62 that there is no longer any air core 58 in the swirl chamber 36 itself, which could have a negative effect on the liquid flow in the swirl chamber 36. Only in the area of the nozzle outlet opening 14 does a residual area of an air core form, around which the liquid film cone emerges from the nozzle outlet opening 14.

A second exemplary embodiment of a swirl nozzle according to the invention, shown in FIGS. 6 and 7, is provided with the same reference numerals insofar as it is identical to the first exemplary embodiment of FIGS. 3 to 5, so that the description of the corresponding parts is based on the above statements is referred.

In contrast to the first exemplary embodiment, the displacement body 62 no longer shows a conical tip, but rather a truncated cone 88 sitting on the cylindrical base 64 with a front surface 90 opposite the base surface 68 and parallel to the swirl chamber base 34, which lies in the swirl chamber 36 and has a diameter, which is bigger than a diameter of the nozzle outlet opening 14. Thus, in this exemplary embodiment, the displacement body 62 does not extend over the entire height of the swirl chamber from the swirl chamber floor 34 to a transition 92 of the swirl chamber walls 38 into the nozzle outlet opening 14, but ends with the front surface 90 at a distance therefrom. Thus, above this front surface 90 in the swirl chamber 36 there are the same flow conditions as in the prior art above the swirl chamber floor 34, so that an air core 58 forms over the front surface 90, which is still to a small extent, namely over a distance from the front surface 90 from the transition 92 between the swirl chamber wall 38 and the nozzle outlet opening 14 corresponding distance in which swirl chamber 36 extends. Nevertheless, the advantages according to the invention are achieved with this second exemplary embodiment, since the area of the air core 58 along which the undesired properties thereof have an effect is considerably shorter than when the displacement body 62 according to the invention is not present.

In a third exemplary embodiment of the swirl nozzle according to the invention, shown in FIGS. 8 and 9, the same reference numerals are used insofar as the same parts are present as in the exemplary embodiments described above, so that reference can be made to the above description.

In contrast to the exemplary embodiments described above, the swirl channels 42 are no longer notches with a straight center line 44, but instead run Although along the circumferential surfaces 30 of the inner body 22 as a straight line, but they show an opening 46 designed as a circular ring segment 94, which thus offers the possibility of reducing the circular region 76 of the swirl body base 34 to the width b of the swirl channel 42, so that the distance e of the beam 48 emerging from the orifice 46 from the central axis 20 is almost identical to an outer radius of the swirl chamber base 34.

The displacement body 62 can thus only be designed as a conical tip 66, the base surface 68 of the conical tip 66 having a radial extension with respect to the central axis 20 that extends as far as an inner edge 96 of the mouth openings 46 of the swirl channels 42 designed as a circular ring segment. In this third exemplary embodiment, the swirl chamber is thus reduced to the cone-shaped space 86, which lies between the conical surface 82 of the displacement body 62 and the swirl chamber wall 38.

A fourth exemplary embodiment of a swirl nozzle according to the invention, shown in FIGS. 10 and 11, shows the same parts as the exemplary embodiments described above insofar as the same reference numerals are used.

In contrast to the previously described exemplary embodiments, the fourth exemplary embodiment differs in that the wall surfaces of the recess 16 have two different partial areas 98 and 100, the partial area 98 directly adjoining the nozzle outlet opening 14 corresponding to a truncated cone surface whose taper angle is greater than that of a truncated cone surface of the partial area 100 adjacent to the partial area 98, the truncated cone lateral surface of the partial area 98 along a line of contact 1O2 merges into the truncated cone surface of sub-area 100.

The conical seat surface 32, against which the inner body 22 with its outer surfaces 30 lies, is formed by the partial region 100. This inner body 22 is identical to the inner body 22 of the third exemplary embodiment with regard to the design of the swirl channels 42 and their mouth openings 46. In addition, the displacement body 62 seated on the swirl chamber base 34 is designed as a conical tip 66, just as in the third exemplary embodiment. However, the conical surface 82 now runs parallel to the partial area 98 at a distance b, which corresponds approximately to the width of the swirl channels 42.

In order that the annular area 76 of the swirl chamber base 34 can be kept in the width of the swirl channel 42 and also that the conical surface 82 of the displacement body 62 can run at a distance b from the partial area 98 corresponding to the width of the swirl channels 42, the partial area 100 extends advantageously the conical seat surface 32 in the direction of the nozzle outlet opening 14 up to the contact line 10 2, so that the swirl chamber 36 In the fourth exemplary embodiment, an annular space 10 4, formed by the partial area 100 extending beyond the conical seat surface 32 as far as the line of contact 10 02, the annular area 76 and part of the surface 82 of the displacer 62 and the conical jacket-shaped space 86, delimited by the partial area 98 and the remaining part of the surface 82 of the displacer 62.

A fifth embodiment of the swirl nozzle according to the invention, shown in FIGS. 12 and 13, is largely identical to the fourth embodiment, so that the same parts are also provided with the same reference numerals. In contrast to the fourth exemplary embodiment, however, the swirl channels 42 run from the pressure chamber 40 to the swirl chamber 36 in the region of the lateral surface 30 of the inner body 22 in a spiral with respect to the central axis 20, so that these swirl channels 42 have a smaller gradient than the central axis 20 the swirl channels 42 in the fourth embodiment. The result of this is that the jet 48 emerging from the orifice 46 has a smaller component 54 perpendicular to the swirl chamber base 34 and a larger speed component parallel to the swirl chamber base 34 and thus a larger tangential flow component with respect to the flow velocity as in the swirl duct 42 of the previous embodiment the central axis 2O can be reached in the swirl channel 36.

In a particularly advantageous variant of the fifth exemplary embodiment, a return bore 1O4 is additionally provided, which is arranged concentrically to the central axis 2O and opens into the swirl chamber 36 opposite the nozzle outlet opening 14 in the region of the displacement body 62. The displacement body 62 is no longer a cone, but merely a truncated cone, the front surface of which is now formed by an opening 10 6 of the return bore 10 4. This return bore 10 4 thus extends through the entire displacement body 62 and also through the inner body 22 and is connected to a conventional return flow path, which is described, for example, in German patent application P 37 03 075.2.

A sixth exemplary embodiment, shown in FIGS. 14 to 16, represents a variant of the first exemplary embodiment, shown in FIGS. 3 to 5. Insofar as the same parts are used, they are also provided with the same reference numerals, so that with regard to their description can be referred to the explanations of the first embodiment.

In contrast to the first exemplary embodiment, this sixth exemplary embodiment shows return bores 11O machined into the conical surface 82 of the conical tip 66, which with longitudinal axes 112 perpendicular to the conical surface 82 penetrate into the displacement body 62 towards its central axis 20, whereby they coaxially to Central axis arranged return channel 114 open out, which is of the conical Tip 66 of the displacer leads in the opposite direction into an interior of the nozzle.

According to the invention, the return bores 11O are not arranged in the region of the nozzle outlet opening 14, but rather in a region overlapped by the outlet-side section 84 of the swirl chamber wall 38, so that the return bore 11O is not in the region of an air core which arises in the nozzle outlet opening 14.

By choosing a certain eccentricity of the return bores 11O, that is, their distance from the central axis 2O, the so-called return mass flow ratio can be regulated in an advantageous manner without having to change a diameter of the return bore, as in the known arrangements of a return bore, which makes sense for the possible dimensions and viscosity ratios are always associated with difficulties.

A fifth embodiment of the swirl nozzle according to the invention, shown in FIGS. 17 and 18, has similarities to the second embodiment, so that the same parts are also provided with the same reference numerals.

In contrast to the second exemplary embodiment, however, the swirl channels 42 run from the pressure chamber 40 to the swirl chamber 36 in the region of the lateral surface 30 of the inner body 22 in a spiral manner with respect to the central axis 20, so that these swirl channels 42 have a smaller gradient than the central axis 20 Swirl channels 42 in the second embodiment. This has the consequence that the jet emerging from the orifice 46 has a smaller component 54 perpendicular to the swirl chamber floor 34 and a larger speed component parallel to the swirl chamber floor 34 and thus a larger tangential component with respect to the central axis at the same overall flow velocity as in the swirl duct 42 of the previous embodiment 2O can be reached in swirl channel 36.

Furthermore, the orifices 46 are expanded to form a ring segment cutout 120, the width of which corresponds to the width of the annular swirl chamber base 34 between the frustoconical displacement body 62 and the swirl chamber walls 38.

In contrast to the second exemplary embodiment, the displacement body 62 rises directly from the swirl chamber base 34 without the cylindrical shoulder as a truncated cone 88 and extends to the front surface 90, which has a diameter approximately corresponding to the diameter of the nozzle outlet bore 14.

Particularly advantageous in the seventh embodiment is the fact that it is easy to manufacture and that the cross-sectional area of the orifices 46 is large, which leads to relatively low pressure losses due to viscosity.

Claims (13)

Swirl nozzle for atomizing a liquid with a swirl chamber (36) rising above a swirl chamber floor (34) and tapering towards a swirl chamber floor (34) opposite the swirl chamber floor (34), with at least one swirl chamber laterally offset in relation to a central axis of the swirl chamber (36) opening swirl channel, with a swirl parameter of> 1, with a displacement body (62) rising from the swirl chamber base (34) and preventing the formation of an air core (58) in a bottom-side swirl chamber area, which is arranged concentrically to the central axis (20) and in the bottom side Part has an outer diameter which corresponds to at least one diameter of the nozzle outlet opening (14), the swirl nozzle having an outer body (10) which has the nozzle outlet opening (14) and an adjoining one, extending along the central axis (20) and increasing with it Extension of a larger cross section tt having recess (16), and in this recess (16) an inner body (22) with a perpendicular to the central axis (20) perpendicular swirl chamber floor (34) can be inserted so that the swirl chamber floor (34) and between this and the nozzle outlet opening (14) lying wall surfaces (18) of the recess (16) delimit the swirl chamber (36), characterized in that the wall surfaces (18) of the recess (16) are formed by lateral surfaces of truncated cones coaxial to the central axis (20), that a partial area (100) of the wall surfaces (18) of the recess (16) form a conical seat surface (32) for the frustoconical inner body (22) and that the conical seat surface (32) has a smaller cone angle than a further portion (98) of the swirl chamber wall (38) adjoining the nozzle outlet opening (14). Swirl nozzle according to claim 1, characterized in that the displacement body (62) extends with an average diameter corresponding at least to the diameter of the nozzle outlet opening (14) over at least half the height of the swirl chamber (36) in the direction of the nozzle outlet opening (14). Swirl nozzle according to claim 2, characterized in that the displacement body (62) extends with an average diameter corresponding at least to the diameter of the nozzle outlet opening (14) over at least two thirds of the height of the swirl chamber (36) in the direction of the nozzle outlet opening (14). Swirl nozzle according to one of the preceding claims, characterized in that a surface (74, 82) of the displacement body (62) facing a swirl chamber wall (38) has a constant distance from the swirl chamber wall (38) all round in each cross-sectional plane with respect to the central axis (20) . Swirl nozzle according to claim 4, characterized in that in a part of the displacement body (62) facing the nozzle outlet opening (14) the surface (82) facing the swirl chamber wall (38) runs at a constant distance therefrom. Swirl nozzle according to claim 5, characterized in that the distance approximately corresponds to a width (b) of the swirl duct (42). Swirl nozzle according to one of the preceding claims, characterized in that an orifice (46) of the swirl channel (42) lies in an annular region (76) of the swirl chamber base (34) which extends around the displacement body (62). Swirl nozzle according to claim 7, characterized in that the width of the annular region (76) is selected so that it corresponds to the extent of the mouth opening (46) from an outer edge of this region (76) in the radial direction inwards. Swirl nozzle according to Claim 8, characterized in that the swirl duct (42) opens into the swirl chamber (36) with an opening formed as a circular segment (94) along an outer edge region of the swirl chamber base (34). Swirl nozzle according to one of the preceding claims, characterized in that the displacement body (62) is provided with a central return bore (104). Swirl nozzle according to one of the preceding claims, characterized in that the displacement body (62) is provided with at least one eccentrically arranged return bore (110). Swirl nozzle according to claim 11, characterized in that the return bore (110) is arranged at a distance from the central axis (20) which corresponds to at least one radius of the nozzle outlet opening (14). Swirl nozzle according to claim 12, characterized in that the return bore (110) is arranged at a distance from the central axis (20) which is smaller than the distance of the mouth opening (46) of the swirl duct (42).

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