EP2390491B1 - Device for injecting fuel into a combustion chamber - Google Patents

Description

The invention relates to a device for injecting fuel into a combustion chamber, in particular for injecting fuel into a cylinder of an internal combustion engine according to the preamble of claim 1.

Injection devices in internal combustion engines have been known for a long time. So in the publication DE 369 670 an injection device is described in which two or more jets are generated in an injection nozzle, which intersect in the combustion chamber. The purpose of this arrangement is that the high velocity fuel jets collide in the combustion chamber, causing extremely intense atomization of the fuel.

This type of injector was, as from the document DE 44 07 360 A1 emerges, later evolved. In this document, a corresponding injection nozzle with fan-shaped jet is further developed in that the jet can be rotated in the combustion chamber, so that the injected fuel quantity can be distributed to the desired amount of air. Although a better distribution of the fuel is possible by twisting a fan beam, but this is a corresponding time required. For optimal engine operation, however, is a short and complete Combustion advantageous to use the resulting increase in pressure as efficiently as possible.

From the publication DE 10 2009 035 027 A1 can be removed with two jet channels multi-jet nozzles, wherein the steel channels are arranged distributed on the peripheral surface of a nozzle body, said injector generates a conical jet.

In addition, the DE 10 2006 041 476 A1 a disc-shaped fuel injections by means of flat fan beams known. This injector injects in the longitudinal direction of the nozzle body.

It has been shown that such injections are not optimal or lead to optimal combustion.

Compared to this prior art, the present invention has the object to optimize the injection or to optimize the combustion, in particular to reduce fuel consumption and to reduce the generation of adverse exhaust emissions.

This object is achieved by a device according to the preamble of claim 1 by its characterizing features.

Accordingly, a device according to the invention is characterized in that the jet channels are arranged distributed over the peripheral surface of a nozzle body and that the fan levels of the multi-jet nozzles are aligned transversely and / or inclined to the geometric axis of the nozzle body, with regularly distributed double jet nozzles are provided so that a uniform planar distribution of fan beams, each delimiting narrow free zones, resulting in a free zone by omission or other positioning of a double jet nozzle can be increased and / or an entire fan beam can be spared.

According to the invention, the jet channels are distributed over the peripheral surface of the nozzle chamber in order to achieve a corresponding good spatial distribution of the spray region of the fuel.

A baffle zone according to the invention is already present when two or more fuel jets only touch or overlap in some regions, which already partly causes the inventive effect.

The use of a multi-jet nozzle, for example a double-jet nozzle, takes advantage of the fine atomization of such nozzles. A fine atomization causes a rapid evaporation of the fuel with a largely homogeneous fuel-air mixture ratio. The fine atomization provides a large surface area of the liquid fuel which is advantageous for such evaporation. The large surface area is also advantageous when ignition has already taken place, since even with any existing liquid surface of fuel droplets, the combustion takes place considerably more effectively with a correspondingly large surface,

By using a plurality of such multiple jet nozzles, the combustion chamber can be spatially defined and sprayed in a short time, so that in a correspondingly small time interval, a good fuel air distribution in the combustion chamber is reached.

It has been found that such double-jet nozzles form a fan beam which spans substantially at the angle at which the partial beams impinge on one another. When colliding occurs a fine atomization, wherein the propagation direction of the fuel droplets almost completely away from the nozzle, which in turn is advantageous for a combustion process, since thus a load on the nozzles by soot or the like particles that may arise during combustion, is avoided , It has also been found that a very flat fan beam can be formed by a double jet nozzle, whose extension, e.g. as angular expansion, in the fan plane defined by the two fuel jets is significantly larger than in the transverse direction to this fan level.

This circumstance can be advantageously used to selectively fill a shallow combustion chamber with a fuel mist. With an appropriate arrangement of the multi-jet nozzles or double jet nozzles can be achieved in a sense a nearly disc-shaped fuel distribution with very fine atomization. This is particularly advantageous in reciprocating engines, which have such a disc-shaped combustion chamber at the top dead center of the lifting movement.

Such a quasi disk-shaped fuel distribution is preferably achieved with multiple jet nozzles, the fan levels are aligned substantially parallel to the disk.

By means of multi-jet nozzles according to the invention, however, any other fuel distribution can also be achieved by appropriate arrangement of the fan levels. Thus, a fan level may well be aligned parallel to the cylinder axis or to a center axis of an injector. Even inclined fan levels in oblique angle arrangements are possible.

By different nozzle openings can also Penetration depth of the fuel can be influenced in the combustion chamber. In this case, different multi-jet nozzles with different nozzle openings can also be used, as are multiple jet nozzles which have jet-dependent different nozzle openings.

Advantageously, an injection device according to the invention is provided with a nozzle chamber common to two or more multiple jet nozzles from which the jet channels of the two or more multiple jet nozzles emanate. This allows a compact design while maintaining two or more multiple jet nozzles or double jet nozzles, with the associated advantages of improved spatial distribution of the spray area.

Preferably, in a device according to the invention a closure for the separation of the jet channels of the fuel supply is provided. This allows clocked operation of the injector in a compact design.

In a further development of this embodiment, a common closure for the fuel supply of two or more multi-jet nozzles is provided. As a result, the design effort is reduced and in turn created the possibility of a compact design with common timing of the multi-jet nozzles.

In a particular embodiment of the invention, the nozzle chamber is formed with a closure element as a closable blind hole, wherein the jet channels in the flow direction behind the closure element pass through the wall of the nozzle chamber.

By this construction, it is possible to install a plurality of jet channels in the wall of the nozzle chamber, wherein the fuel supply is simultaneously clocked with only one closure element.

Advantageously, at least two multi-jet or double-jet nozzles with mutually parallel fan planes are arranged offset transversely to the fan planes. By the measure adjacent multi-jet nozzles or double jet nozzles can be formed very close to each other. In an extreme case, an embodiment is possible in which jet channels of two double-jet nozzles intersect in the wall of the injection device, but the intersecting flow channels are separated from one another by this offset.

Basically, it is by the fuel supply from a common fuel pressure chamber, although conceivable that jet channels actually meet in the wall of the nozzle, d. H. communicate with each other, since all outgoing from the same nozzle chamber jet channels are subjected to the same pressure. For a defined beam characteristic, however, a corresponding guide length of the liquid in the jet channel is advantageous. In particular, with low wall thicknesses, it is therefore advisable to form each beam channel separately from the other beam channels. This is also advantageous from the viewpoint that to produce the desired beam characteristic high precision and quality in the production of the jet channels is required, which is to ensure better in separate production of each beam channel, for example by mechanical drilling, but also by other manufacturing processes.

In principle, although slit-shaped jet channels are conceivable, which produce a more three-dimensional spray pattern, for the production of a flat spray pattern, however, the use of circular beams, which are to be produced by beam channels with a round cross section, is recommended.

In a particular embodiment of the invention, the fan levels of all multi-jet or double-jet nozzles are arranged in parallel. This results in a nearly disc-shaped spray area with the advantages indicated above. Although the slight offset between individual fan levels transversely to the fan levels entails a certain height extent of the spray area, it is still a substantially flat pronounced spray area of multiple multi-jet or double jet nozzles in different angular directions possible by such a configuration.

Preferably, the multi-jet or double-jet nozzles are arranged so that they are distributed substantially uniformly over an angle of 360 °. As a result, for example, a flat cylindrical combustion chamber can be sprayed out well.

As already mentioned above, however, other orientations of the subject level can be provided, for. B. to achieve a larger volume fuel distribution in depth.

It can also different fan orientations, z. B. combined in the vertical and horizontal directions, based on the injector or the cylinder axis, are provided. Also intermediate positions with inclined, oblique fan level, based on the injector or cylinder axis, are conceivable.

Preferably also predetermined free spaces are recessed from the spray area of the multi-jet nozzles. This can be advantageous, for example, in the area of inlet or outlet valves or also in the region of a spark plug in order to protect these components against contamination, in particular against coking or sooting. The recess from the spray area can be achieved by appropriate spatial arrangement of the multi-jet or double jet nozzles. Also by different angles of the jet channels of a multi-jet or double jet, a specific Area can be excluded from the spray area.

The angle between the flow channels of a multi-jet nozzle, which at the same time forms the impact angle (for example as an angle between two jets) under which the fuel jets produced thereby collide, is preferably selected to be greater than 10 ° or 20 °. This has proven to be advantageous for the expression of a fan-shaped fuel distribution among the pressures prevailing in internal combustion engines, in particular reciprocating piston engines, and the corresponding short-term dynamics of the injection process. A particularly good spray pattern has at impact angles between 30 ° and 50 °, z. B. 40 °. The impact angle can be adapted to the desired fuel distribution. If, for example, a greater penetration depth is desired in the combustion chamber, smaller impact angles can be selected. On the other hand, a larger impact angle gives a wider fan beam.

In addition, the distance between the beams to each other and the impact angle, the distance of the baffle zone, d. H. of the place where the rays collide at the impact angle, are set to the nozzle body.

For example, the injection device according to the invention is well suited for operating pressure differences between the high-pressure side in the interior of the nozzle chamber and the low-pressure side outside greater than 100 bar, preferably greater than 150 bar. Above these pressure differences, the desired spray range is formed with a dynamics and atomization that is well suited for operation in an internal combustion engine. For use in other combustion devices, the distribution and the fineness of the fuel atomization of a device according to the invention can be used even with smaller pressure differences.

The injection device according to the invention is integrated in an advantageous manner in a so-called injector, which can be mounted as a unit to combustion devices is. Such injectors can for example be mounted in the cylinder head of reciprocating engines. They are preferably electronically controllable in order to carry out the fuel metering in the desired amount in the required time sequence.

As a rule, such injectors are connected to a common pressure line (common rail). In principle, however, they can also be provided individually with a corresponding pressure generator (pump / nozzle).

The invention is basically usable in a variety of combustion processes. These may require continuous or discontinuous combustion. Continuous combustion would be conceivable, for example, when used in turbines or heating burners.

Depending on the application and the shape of the combustion chamber, the arrangement and orientation of the multi-jet nozzles can vary. So z. B. multiple multi-jet nozzles offset with respect to a geometric axis of the nozzle body in the axial direction and / or distributed circumferentially and / or the fan levels of the multiple nozzles transversely and / or parallel and / or be aligned to the axis of the nozzle body. The fan levels of two or more multiple jet nozzles can also be aligned with each other inclined.

Preferably, the invention is used in clocked combustion devices, in which the good, spatially defined and quickly established fuel distribution at a high Zerstäubungsgrad is of particular use.

In particular, in reciprocating engines usually a disc-shaped fuel distribution in the flat combustion chamber at the top dead center of the reciprocating piston is desirable. For this application, a plurality of multi-jet or double-jet nozzles are advantageously arranged so that they In the mounted state of the injectors spray parallel to the main plane of the combustion chamber. In the case of an installation of such an injector parallel to the reciprocating piston or to the cylinder axis, this means that the jet channels of the multi-jet or double-jet nozzles exit transversely to the longitudinal axis of the injector. In oblique mounting position of the injector or the nozzle chamber from which depart the jet channels, the jet channels relative to the axis of the injector or the fuel pressure chamber can also be inclined, so that the emission in the combustion chamber again takes place largely parallel to the main plane of the combustion chamber.

An embodiment of the invention is illustrated in the drawing and will be explained in more detail with reference to FIGS.

Fig. 1

eine Seitenansicht auf eine erfindungsgemäße Einspritzvorrichtung,

Fig. 2

eine Draufsicht auf eine Vorrichtung gemäß Fig. 1,

Fig. 3

eine Schnittdarstellung entlang Schnittlinie III in Fig. 2,

Fig. 4

eine Detaildarstellung aus Fig. 1,

Fig. 5

eine Schnittdarstellung entlang Schnittlinie V in Fig. 4,

Fig. 6

eine Schnittdarstellung entlang Schnittlinie VI in Fig. 4,

Fig. 7

eine Schnittdarstellung durch eine erfindungsgemäße Einspritzvorrichtung mit Verschlussnadel,

Fig. 8a und 8b

Vergleichsdarstellungen zum grundsätzlichen Aufbau zwischen Sacklochdüse und Sitzlochdüse,

Fig. 9

eine schematische Darstellung des Sprühbildes einer erfindungsgemäßen Einspritzvorrichtung in perspektivischer Darstellung und

Fig. 10

eine schematische Darstellung einer erfindungsgemäßen Einspritzvorrichtung beim Einsatz in einem Verbrennungsmotor.

Show in detail

Fig. 1

a side view of an injection device according to the invention,

Fig. 2

a plan view of a device according to Fig. 1 .

Fig. 3

a sectional view along section line III in Fig. 2 .

Fig. 4

a detailed view Fig. 1 .

Fig. 5

a sectional view along section line V in Fig. 4 .

Fig. 6

a sectional view along section line VI in Fig. 4 .

Fig. 7

a sectional view through an injection device according to the invention with a needle valve,

Fig. 8a and 8b

Comparative views of the basic structure between blind-hole nozzle and seat hole nozzle,

Fig. 9

a schematic representation of the spray pattern of an injection device according to the invention in a perspective view and

Fig. 10

a schematic representation of an injection device according to the invention when used in an internal combustion engine.

The injection device 1 according to Fig. 1 comprises a substantially cylindrical injector head 2 with a truncated cone 3 for cross-sectional tapering at the outlet end of the injection device 1, to which a dome-shaped nozzle body 4 connects, which forms a nozzle chamber in its interior. The nozzle body 4 is hollow for this purpose and comprises jet channels, which are described in more detail below. The injection device 1 is also formed round and centric of a major axis H.

In the detail enlargement according to Fig. 4 are angular recesses 5 in the nozzle body 4 can be seen in which jet channels 6 open. As in the sectional view according to the FIGS. 5 and 6 It can be seen that the angular recesses 5 serve to provide a surface arranged at right angles to the respective exit surface for drilling round beam channels 6, 7. This is particularly advantageous if the jet channels 6, 7 are mechanically drilled. The diameters of the bores for the jet channels 6, 7 are preferably selected to be clearly <500 μm, for example <150 μm, preferably in the range of 100 μm. Such jet channels offer a good distribution and atomization of the fuel under the operating conditions prevailing in internal combustion engines.

As in the FIGS. 5 and 6 can be seen, in pairs two beam channels 6, 7 are arranged at an angle α to each other. The vertex S of this angle α defines the impingement zone of a double jet nozzle 8 formed from two jet channels 6, 7. Such a configuration of jet channels 6, 7 results in a fan jet 9, the geometry thereof, behind the vertex S or behind the impingement zone S in the jet direction is essentially given by the rectilinear extension of the beam channels 6, 7.

In principle, instead of a double-jet nozzle 8 as a multiple jet nozzle, a nozzle with more than two jets, for example a triple-jet nozzle, could be used in which three or more jets converge in a common vertex S. For example, in the middle of the rays 6, 7, a third ray could be directed to the vertex S. By means of such multiple jet nozzles, for example, the velocity distribution in the fan jet can be influenced compared to a double jet nozzle.

The cross sections of the jet channels (6, 7) are chosen equal in the illustrated embodiment for all multi-jet nozzles 8. However, this can also be varied. The cross sections of various flow channels 6, 7 of a multi-jet nozzle 8 can also be chosen differently, as are the cross sections of jet channels 6, 7 of different multi-jet nozzles 8.

However, it has been shown in the experiment that with the use of double jet nozzles according to the embodiment, the advantages of the invention are well feasible.

The impact angle α, which at the same time forms the angle between the two beams 6, 7 of a double-jet nozzle and defines the plane of the fan beam 9, should preferably not be too small. Experiments have angles> 10 ° or> 20 °, preferably> 30 ° and ideally around 40 ° Results provided.

Like from the FIGS. 1 to 6 As can be seen, the fan beams 9 can be generated with parallel fan planes. In Fig. 5 For example, four double jet nozzles 8 lie in a plane corresponding to the sectional plane V Fig. 4 equivalent. Another four double-jet nozzles 8 are arranged in a plane corresponding to the sectional plane VI in Fig. 4 equivalent. All of these double-jet nozzles are arranged such that their specialist levels are parallel and, in the illustrated embodiment, perpendicular to the main axis H of the injection device 1.

In principle, however, the fan levels can also be at an angle β (see Fig. 4 ) are arranged to the main axis H with injection device 1, so that the fan plane or the flat spray pattern, which is generated by the double jet nozzles 8, is also inclined to the main axis H. The exact geometric configuration depends, inter alia, on the installation position of an injector head 2 in the respective combustion chamber. The use of different β-angle is conceivable, as for example, based on the angle β ₁ and β ₂ in FIG. 8a is shown.

As in Fig. 4 can be seen, in the illustrated embodiment, double jet nozzles 8 in two different, offset by the offset or distance A planes V, VI mounted, ie they are arranged transversely to the fan plane of the fan beams 9. By this arrangement, a larger number of double-jet nozzles can be circumferentially distributed without the jet channels 6, 7 meet in the wall of the nozzle body 4. Despite the small offset A, however, a substantially flat spray pattern is generated by the totality of all double-jet nozzles 8. If necessary, but by a plurality of such levels and / or by a larger offset A and a more extensive in the axial direction, z. B. columnar spray pattern can be generated.

Fig. 7 shows one of the Fig. 3 corresponding representation of the Device 1, wherein additionally an injector needle 10 is provided as a closure element. The Injektornadel 10 sits on a valve seat 11 which is mounted in the transition of the nozzle body 4 to the truncated cone 3. The injector needle 10 thus seals the nozzle body 4 with respect to the injector head 2.

In this embodiment, one speaks of a so-called blind hole nozzle, as in other expression in Fig. 8a is shown. In a blind hole, a blind hole is closed by a closure element 12, wherein the jet channels 13 remain open with respect to the interior 14 of the nozzle body. The interior 14 of the nozzle body forms a certain dead volume.

In principle, an injection device 1 according to the invention can also be designed as a so-called seat hole nozzle, as in Fig. 8b shown. In this case, the closure element 12 closes immediately the jet channels 13, which accordingly open in the region of the valve seat 15.

It has been shown that a more uniform injection behavior can be realized in the embodiment as a blind-hole nozzle, which is particularly important for the micro-quantity metering in the pre- and post-injections of internal combustion engines. In the case of a seat-hole nozzle, an uneven spray pattern can occur with small strokes, which is due to production-related tolerances. However, with an increased expenditure in the range of these tolerances, a seat hole nozzle can also provide good results. The seat hole nozzle offers the advantage over the blind hole nozzle of a smaller dead volume.

In the case of a blind hole nozzle, the dead volume by the arrangement and shape of the closure element, for. B. the Injektornadel 10 can be influenced. Advantageously, the injector needle 10 is designed so that it minimizes the dead volume in the region of the nozzle body in the closed state.

The leadership of the beam channels 13 in the embodiments according to Fig. 8a and 8b is such that they are slightly opposite to the main axis H at an angle. This has the consequence that the spray zone generated by fan nozzles is no longer flat, but slightly pyramidal designed. This may be intended depending on the application.

In a reciprocating engine will usually be strive for a flat spray pattern, as for example in Fig. 9 is shown. In an injection device 1 according to Fig. 9 with regularly circumferentially distributed double jet nozzles 8 results in a uniform planar distribution of fan beams 9, each narrow narrow zones 15 limit, in which no or little fuel is sprayed. As based on Fig. 9 can be clearly seen, the geometry of the spray pattern can be designed defined by arrangement and design of the double jet nozzles 8. By a smaller impact angle in a double jet nozzle, for example, a certain free zone 15 can be increased. By eliminating or otherwise positioning a double jet nozzle, the free zone 15 can also be designed. For example, an entire fan jet 9 can be recessed to save at this point, for example, an inlet or outlet valve or a spark plug from the spray area.

This in Fig. 9 spray pattern shown is particularly suitable for use in a reciprocating engine. To illustrate this is in Fig. 10 a cylinder 16 and the associated piston 17 of a reciprocating engine shown schematically. The piston 17 is at top dead center. The cylinder head is not shown to release the view into the cut cylinder 16. The cylinder head would close the combustion chamber 18 at the level of the sealing surface 19, so that the injector 20 projects through the cylinder head into the combustion chamber 18. This corresponds to a conventional geometry in reciprocating engines, which results in a flat disc-shaped combustion chamber 18.

In this case, a correspondingly flat configuration of the spray pattern of the injector 20 is advantageous. This in Fig. 10 spray pattern shown corresponds to the spray pattern according to Fig. 9 , as for example, by an injection device according to the Fig. 1 to 6 is achievable. In the execution according to Fig. 10 The injector 20 projects centrally into the cylinder 16 in parallel and concentric manner. In this case, it is advantageous to arrange the double-jet nozzles 8 in fact transversely to the main axis H of the injector, as shown in FIG Fig. 4 is indicated by the angle β. If desired, however, the injector 20 may be inclined to the main axis of the cylinder 16 are introduced into the combustion chamber, wherein a corresponding inclination of the fan planes of the double jet nozzles 8 is possible to produce a transverse to the main axis of the cylinder 16 spray pattern. In this case, the angle would be β, as in Fig. 4 is drawn, deviating from the right angle to choose.

As already indicated several times, by appropriate arrangement and design of the multi-jet nozzles, the spray pattern can be adapted to the respective combustion chamber of the combustion device. Essential for the invention is the fact that with multiple, simultaneously acted multi-jet nozzles, in particular double jet nozzles on the one hand excellent atomization with the smallest droplets and the associated large surface area of the fuel can be achieved, at the same time an excellent adaptation to the geometry of the combustion chamber and thus a very uniform and fast distribution of the fuel in the combustion chamber is possible.

LIST OF REFERENCE NUMBERS

1

Injector

2

injector

3

truncated cone

4

nozzle body

5

recess

6

beam channel

7

beam channel

8th

Doppelstrahldüse

9

fan beam

10

injector needle

11

valve seat

12

closure element

13

beam channel

14

inner space

15

free zone

16

cylinder

17

piston

18

combustion chamber

19

sealing surface

20

injector

Claims (14)

1. A device for injecting fuel into a combustion chamber, particularly for injecting fuel into a cylinder of an internal combustion engine, wherein a multiple jet nozzle (8) is provided having at least two jet channels (6, 7) for generating at least two fuel beams at least partially colliding in an Impact zone (S), wherein two or several such multiple jet nozzles are provided and wherein through the at least two jet channels (6, 7) the multiple jet nozzles (8) form a fan nozzle for generating a fan jet (9), the extension of which in a fan plane is greater than in the transverse direction to said fan plane, characterized in that the jet channels (6, 7) are arranged distributed over the circumferential surface of a nozzle body (4) and that the fan planes of the multiple jet nozzles (8) are oriented transverse and/or inclined to the geometrical axis of the nozzle body (4), wherein double jet nozzles (8) regularly distributed on the circumferential side are provided as multiple jet nozzles, so that a uniformly even distribution of fan jets (9), which in each case define narrow free zones (15), result, wherein a free zone (15) can be enlarged by omission or another positioning of a double jet nozzle (8) and/or an entire fan jet (9) can be omitted.
2. A device according to claim 1, characterized in that a common nozzle chamber (4) is provided, from which the jet channels (6, 7) of two or several multiple jet nozzles (8) emanate.
3. A device according to one of the aforementioned claims, characterized in that a closing element (10) is provided for closing the fuel supply.
4. A device according to one of the aforementioned claims, characterized in that a common closing element (10) is provided for closing the fuel supply for two or several, particularly for all multiple jet nozzles (8).
5. A device according to one of the aforementioned claims, characterized in that the nozzle chamber forms a blind hole which can be closed with a closing element (10), wherein the jet channels (6, 7) push through the wall of the nozzle chamber in the direction of flow behind the closing element (10).
6. A device according to one of the aforementioned claims, characterized in that the jet channels (6, 7) are designed as round channels.
7. A device according to one of the aforementioned claims, characterized in that at least two multiple jet nozzles (8) are arranged with fan planes parallel to each other.
8. A device according to one of the aforementioned claims, characterized In that at least two multiple jet nozzles (8) are arranged with fan planes not parallel to each other.
9. A device according to one of the aforementioned claims, characterized in that at least two multiple jet nozzles (8) are arranged with fan planes parallel to each other offset transversely to the fan plane.
10. A device according to one of the aforementioned claims, characterized in that the fan planes of all multiple jet nozzles (8) are parallel to each other.
11. A device according to one of the aforementioned claims, characterized In that predetermined free spaces (15) are omitted from the spray zone of the multiple jet nozzles (8).
12. A device according to one of the aforementioned claims, characterized in that the impact angle of two colliding jets is designed 10° or > 20°, preferably between 30° and 50°.
13. An injector for a combustion device for injecting fuel into a combustion chamber, particularly of an internal combustion engine, characterized in that it includes an injector (1) according to one of the aforementioned claims.
14. An internal combustion engine with a device for injecting fuel Into a combustion chamber, characterized in that a device (1) is provided according to one of the aforementioned claims for injecting fuel into the combustion chamber.

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