EP3085835B1 - Sprinkler and method for watering a road surface - Google Patents

Description

The invention relates to a sprinkler for irrigating a roadway such as a driving technique track or a test track with outlet openings for dispensing a liquid.

The invention further relates to a method for irrigating a roadway, in particular a driving technique route or a test route, with a sprinkler.

Sprinklers for irrigating a road have become known from the prior art, for example in order to artificially produce a reduced coefficient of friction between the road and a tire of a motor vehicle for driving technique training or a test of vehicles.

From the document JP S62199152U is known a sprinkler with water outlet openings, which have a cross-section increasing from an interior to an exterior.

From the document EP 2 843 132 A2 a sprinkler with a spray insert which is detachably and movably arranged in a nozzle of the sprinkler is known in order to change a spraying direction of the sprinkler in a simple manner by rotating the spray insert.

However, it has been shown that sprinklers known from the prior art do not allow irrigation of a carriageway which leads to realistic conditions or a realistic coefficient of friction of the carriageway.

This is where the invention comes in. The object of the invention is to provide a sprinkler of the type mentioned, with which a particularly realistic wet road surface can be achieved.

Furthermore, a method of the type mentioned at the beginning is to be specified, with which irrigation of a roadway is possible which leads to corresponding, particularly realistic conditions.

The first object is achieved according to the invention by a sprinkler according to claim 1.

The fact that at least one outlet opening of the sprinkler has a cross-section that increases from the inside to the outside results in a fanning out of a water jet flowing out of the outlet opening of the sprinkler, which leads to a particularly good and uniform liquid distribution and thus to realistic conditions. It is preferably provided that a spray insert is arranged in the sprinkler, recesses in the spray insert at least partially defining the outlet openings of the sprinkler. As a rule, the spray insert is positioned in a nozzle of the sprinkler, the outlet openings, which are partially defined by recesses, connecting a central space or an interior of the sprinkler to an exterior, in which central space the water pressure is present when the sprinkler is in operation.

As a rule, the cross section of the recess increases along a longitudinal axis of the recess, usually in a direction in which a liquid flows through the spray insert when the spray insert is inserted in the sprinkler. The increase in cross section can be provided continuously and continuously over an entire length of the recess from an inner end to an outer end. However, it can also be provided that only a region of an outer end of the recess has a cross-section which increases from the outside or an outside opening angle which leads to a fanning out of the water jet according to the invention when it exits the outlet opening.

If the sprinkler outlet openings are positioned approximately at the level of the road to be watered, a spray pattern with a spray angle of maximum 180 ° results at a water pressure of approximately 1 bar, a ratio of a length of the spray pattern to a width of the spray pattern 2 to 4 , preferably 2.5 to 3.5, in particular 2.8 to 3.2.

It has been shown that particularly realistic conditions can be achieved with such a spray pattern, and the behavior of vehicles on wet roads can be determined very precisely. A region of the roadway is defined as the spray pattern, which area is wetted directly with liquid by water or another liquid emerging from the sprinkler when the sprinkler is in operation. The length of the spray pattern and the width of the spray pattern make it a thought Rectangle described, which, with a minimal size of the rectangle, circumscribes an area on the roadway in which the sprinkler is arranged on the one hand and within which liquid escaping from the sprinkler hits or within which water jets emerging from the sprinkler directly hit the roadway. It is therefore understood that the spray pattern itself generally has no rectangular shape, but can be characterized by a circumscribing rectangle.

For an advantageous liquid distribution, the length of the spray pattern is generally at a sprinkler supply pressure of 0.5 bar to 1.5 bar, generally 3.5 m to 12 m, preferably 5 m to 8 m and a width preferably 1 m to 4 m, in particular 2 m to 3 m. As a result, favorable wetting of the road is achieved even with simultaneous evaporation.

It has proven useful that the spray pattern has a spray angle of at most 180 °, preferably 150 ° to 180 °, in particular 160 ° to 175 °, preferably approximately 170 °. This results in an advantageous liquid distribution on the road to achieve realistic conditions. The spray angle is essentially determined by an arrangement of the outlet openings, so that a defined spray angle can be achieved in a simple manner by corresponding arrangement of the recesses defining the outlet openings.

A particularly favorable spray characteristic or water distribution results if the recesses have an approximately rectangular, in particular an approximately square, cross section. As a rule, the recesses are covered by a component with a flat or conical surface when installed in the sprinkler, the flat side of the component, for example a fixing screw connecting the spray insert with a nozzle body, covering an open long side of the recess, as a result of which the outlet opening is formed. In this case, a cross section of an outlet opening is geometrically determined by a corresponding recess in the spray insert.

To achieve a favorable liquid distribution, it has proven useful that a minimum cross-sectional width and a cross-sectional height of the recesses are 1 mm to 3 mm, in particular 1.5 mm to 2.3 mm.

A particularly uniform wetting of the road is possible with a structurally simple construction of the spray insert if 10 to 15, in particular 11 to 13, recesses are provided.

Favorable flow conditions in an interior of the sprinkler result when the longitudinal axes of the recesses intersect an imaginary, central axis of rotation of the spray insert, in particular at a common intersection. This also results in a uniform liquid distribution in the respective directions. The spray insert is usually designed as a spray ring with a contour that is essentially rotationally symmetrical about an axis of rotation, in which contour the recesses are arranged. For example, the recesses can be made by milling into a rotationally symmetrical basic structure of the spray insert.

If several recesses are provided in the spray insert, a desired spray pattern can be achieved in a particularly simple manner in that an angle which includes a longitudinal axis of a first recess with a longitudinal axis of a last recess corresponds to the spray angle. The first recess and the last recess are those recesses between which further, in particular middle, recesses may be arranged.

A spray pattern that is favorable for test tracks can be achieved, for example, by different inclination angles of the individual outlet openings with respect to the roadway. Water jets then emerge from all outlet openings at approximately the same speed, but the individual water jets reach different throwing heights or ground clearances, which also results in different throwing distances of the individual water jets.

To achieve a spray pattern that leads to realistic conditions, a central outlet opening is provided between a first outlet opening and a last outlet opening and has a larger opening angle than the first outlet opening and the last outlet opening. It has proven to be advantageous if at least one central recess is provided in the spray insert, which is arranged between the first recess and the last recess and has a larger minimum cross-sectional area and / or a larger opening angle than the first recess and the last recess. Advantageously, the ratio of the minimum cross-sectional area of the at least one central recess to the minimum cross-sectional area of the first recess is approximately 1.1 to 1.8, particularly preferably 1.2 to 1.3, in particular approximately 1.23. The recesses usually connect a central space or an interior of the sprinkler, to which an operating pressure of usually 0.5 bar to 1.5 bar is present, with an exterior. Different cross-sectional areas of the individual recesses result in different speeds at which water emerges from the individual outlet openings formed by the recess or co-defined by it. This results in different throwing distances or spraying distances of the water jets emerging from the individual outlet openings, so that a spray pattern with a ratio of length to width that is particularly favorable for test purposes can be achieved in a simple manner. Different throwing distances of the individual water jets can thus be achieved with the same and low throwing height of the individual water jets. It is thus prevented in a simple manner that vehicle parts such as headlights or brake discs are wetted directly by water from vehicles passing through the sprinkler and thus lighting or a braking effect of the vehicles are not influenced in a manner that is not realistic. The cross-section or the cross-sectional area of a recess, which has a cross-section increasing from an interior to an exterior or an opening angle of more than 0 °, is minimal at an inner end of the recess, at which the water pressure or operating pressure usually occurs during operation is present. In the case of a recess which has a constant cross section from the inside to the outside or an opening angle of 0 °, the minimum cross section consequently also corresponds to a maximum cross section.

Different throwing distances can also be achieved by different opening angles of the recesses. In addition, the water jet is also fanned out by recesses which have an opening angle or a cross section which increases from the inside to the outside. Thereby a particularly uniform wetting of the road is guaranteed. An angle between the boundary surfaces of the recess, usually between the lateral boundary surfaces of the recesses, is defined as the opening angle, so that an opening angle of more than 0 ° results in a lateral or approximately horizontal fanning out of a water jet.

To achieve the preferred spray pattern with a low throwing height of the water jets, it is usually provided that minimum cross-sectional areas and / or opening angles of the recesses increase from the first recess to at least one central recess and decrease from the at least one central recess to the last recess. It can be provided that all recesses have different cross-sectional areas or opening angles. An embodiment is also possible in which all the recesses between the first recess and the last recess have an identical minimum cross section, which is larger than a minimum cross section of the first recess and a minimum cross section of the last recess. It can further be provided that all the recesses between the first and the last recess have an identical opening angle which is greater than an opening angle of the first recess and the last recess or greater than 0 °.

To achieve a particularly favorable throwing distance of the water jet emerging from the first recess, it is preferably provided that a minimum cross-sectional area of the first recess is 3 mm ² to 5 mm ² , in particular approximately 3.24 mm ² . As a rule, the first recess and the last recess have approximately identical cross-sectional areas. The first recess and the last recess usually have a cross-section or a constant cross-sectional area that is approximately constant from the inside to the outside, so that an opening angle for these recesses is 0 ° and a minimum cross-section also corresponds to a maximum cross-section of these recesses.

In order to achieve the preferred spray pattern with a low throwing height of the water jets, it is usually provided that a minimum cross-sectional area of the at least one central recess is 3 mm ² to 5 mm ² , in particular approximately 4 mm ² , is. These recesses advantageously have an increasing cross-sectional area from an interior of the spray insert, which is usually subjected to water pressure during operation, to an exterior along longitudinal axes, so that the recesses have a minimal cross-sectional area in an interior of the spray insert. A maximum cross-sectional area of the at least one central recess on an outer edge of the spray insert is generally 5 mm ² to 10 mm ² , in particular 6 mm ² to 8 mm ² .

For a favorable fanning out of at least one water jet, it is provided according to the invention that at least one recess, in particular a central recess arranged between a first recess and a last recess, has an opening angle of 5 ° to 15 °, in particular 10 ° to 12 °. With this opening angle, both a good fanning out and a sufficient throw range can be achieved.

In order to achieve large throwing distances of individual water jets, at least one recess is generally provided which has a constant cross section from the inside to the outside. Usually, the lateral recesses or the first recess and the last recess have a constant cross section or a constant cross-sectional area, so that an opening angle of these recesses is 0 ° or boundary surfaces of the recesses are parallel.

Wetting vehicle parts such as headlights or brake disks from vehicles passing the sprinklers with water is prevented in a simple manner if at least one, preferably all, the longitudinal axes of the recesses have a pitch angle of 9 ° to 18 °, preferably 11 ° to 16 °, in particular 12.5 ° to 13.5 °, with respect to a plane which is perpendicular to an imaginary vertical axis of the spray insert. When the spray insert is installed in a sprinkler in the operating position, the imaginary vertical axis of the spray insert is generally approximately perpendicular to a road surface, so that the angle of inclination corresponds to an angle of the recesses with the road surface when installed, ready for use. In the case of an approximately rotationally symmetrical spray insert such as a spray ring, the vertical axis corresponds to the axis of rotation of the spray insert.

According to the invention, the outlet openings are only distributed over part of a circumference of the sprinkler, and a central outlet opening is provided between a first outlet opening and a last outlet opening and has a larger opening angle than the first outlet opening and the last outlet opening. The outlet openings are distributed over a part of the circumference of the sprinkler of a maximum of 180 °.

The sprinkler can be easily adapted to different environmental conditions if the spray insert in the sprinkler is arranged to be detachable, in particular rotatable about an axis of rotation. Different characteristics of the sprinkler and a rotation of the spray insert around an imaginary axis of rotation can thus be used to achieve a different spray direction in a simple manner by exchanging the spray insert.

However, it can also be provided that the sprinkler and the spray insert are formed in one piece, the sprinkler and the spray insert in particular being integrally connected. As a result, a sprinkler is achieved with fewer individual parts and thus with a reduced assembly effort. The spray insert can also be part of a nozzle arranged detachably in the sprinkler, wherein the spray insert can be detachably connected to the nozzle or can be an integral part thereof, so that outlet openings of the sprinkler are at least partially defined by the spray insert.

In the case of a roadway, in particular a driving technique route or a test route, with a sprinkler for irrigating the roadway, it is expedient if a sprinkler according to the invention is arranged in the roadway in such a way that a spray pattern with a spray angle occurs when the water pressure at the sprinkler is approximately 1 bar of preferably at most 180 °, a ratio of a length of the spray pattern to a width of the spray pattern being 2 to 4, preferably 2.5 to 3.5, in particular 2.8 to 3.2. As a result, particularly realistic conditions for checking vehicle dynamic properties in wet weather can be achieved.

The further object is achieved by a method of the type mentioned at the outset, wherein water emerges from at least one outlet opening of the sprinkler, which has a cross section which increases from the inside to the outside. The associated fanning out of the water jet results in particularly uniform irrigation.

In order to achieve a desired spray pattern, it can be expedient if water emerges from at least one outlet opening which has a cross section which is constant from the inside to the outside. This ensures a long throw of a corresponding water jet.

Irrigation is carried out at a water pressure of about 0.5 bar to 1.5 bar, in particular about 1 bar, and a spray pattern with a spray angle of preferably at most 180 °, a ratio of a length of the spray pattern to a width of the spray pattern 2 to 4, preferably 2.5 to 3.5, in particular 2.8 to 3.2, is. As a rule, the width of the spray pattern is 1 m to 4 m, preferably 2 m to 3 m.

In order to prevent vehicle parts such as headlights or brake discs of a vehicle passing the sprinkler from being wetted with water, it is advantageous if the water from the sprinkler is inclined at an angle of 9 ° to 18 °, preferably 11 ° to 16 °, in particular 12 5 ° to 13.5 °, opposite the road.

For adequate wetting of the roadway, it is advantageously provided that the irrigation with a water flow of 20 dm ³ / min to 60 dm ³ / min, preferably 30 dm ³ / min to 50 dm ³ / min, in particular about 35 dm ³ / min up to 40 dm ³ / min. This corresponds to the amount of water delivered by the sprinkler to the road.

• Fig. 1 ein bevorzugtes Sprühbild;
• Fig. 2 bis 6 einen Sprüheinsatz des erfindungsgemäßen Sprinklers in verschiedenen Darstellungen;
• Fig. 7 und 8 einen erfindungsgemäßen Sprinkler.

Further features, advantages and effects of the invention result from the exemplary embodiments shown below. In the drawings, to which reference is made, show:

• Fig. 1 a preferred spray pattern;
• 2 to 6 a spray application of the sprinkler according to the invention in different representations;
• Fig. 7 and 8 a sprinkler according to the invention.

Fig. 1 schematically shows a spray pattern 2 of a sprinkler according to the invention in a plan view. The spray pattern 2 has a spray angle α of approximately 170 ° and is formed by 13 water jets 19, which usually emerge from a sprinkler 3 with a spray insert 1. With a water pressure in an interior or a central space 11 of the sprinkler 3 of approximately 1 bar, the length 6 of the spray pattern 2 is 6 m with a width 7 of approximately 2 m. As can be seen, the length 6 and width 7 of the spray pattern 2 indicate dimensions of a rectangle circumscribing an outer contour 18 of the spray pattern 2. The outer contour 18 of the spray pattern 2 is essentially determined by the points of impact at which the individual water jets 19 impinge on the carriageway and the position of the in FIG Fig. 1 Sprinklers 3 not shown formed.

The spray pattern 2 is achieved, as shown, in that the individual water jets 19 have different throwing distances 10, a throwing distance 10 corresponding to a distance from a point from the sprinkler 3 at which the respective water jet 19 touches the roadway or strikes the roadway. As can be seen, lateral water jets 19 have larger throwing distances 10 than middle water jets 19, which emerge from middle outlet openings of the sprinkler 3. Cross-sections of the outlet openings are essentially defined by cross-sectional areas of recesses 4a, 4b, 4c, 4d of the spray insert 1. The different spray widths are achieved by means of different cross sections and different opening angles ϕ of recesses 4a, 4b, 4c, 4d in the spray insert 1, which with the same pitch angle δ of all recesses 4a, 4b, 4c, 4d at different speeds and an at least partial fanning out of the water jets 19 lead when they exit the sprinkler 3.

2 to 5 show a spray insert 1 for a sprinkler 3 according to the invention in different views, wherein 2 and 3 show the spray insert 1 in a perspective view. Fig. 4 shows a top view of the spray insert 1. Fig. 5 shows a sectional view along the line VV in Fig. 4 . As shown, the spray insert 1 is approximately rotationally symmetrical about an axis of rotation 5, with recesses 4a, 4b, 4c, 4d not being distributed over an entire circumference.

To achieve the desired spray pattern 2, the spray insert 1 has recesses 4a, 4b, 4c, 4d, which are arranged distributed over an angle β of approximately 160 °. All of the recesses 4a, 4b, 4c, 4d have an approximately square cross section in an interior of the spray insert 1, in which essentially the water pressure of the central space 11 is present. An inner cross-sectional width 8i and a cross-sectional height 9 each amount to approximately 1.8 mm in a first recess 4a and in a last recess 4c. Furthermore, the first recess 4a and the last recess 4c have an approximately constant cross section from the inside to the outside, so that an opening angle ϕ of 0 ° results in these recesses 4a, 4c. With these recesses 4a, 4c, an inner cross-sectional width 8i consequently corresponds to an outer cross-sectional width 8a.

Additional recesses 4b, 4d, in particular middle recesses 4b, are provided between the first recess 4a and the last recess 4c. In order to ensure smaller throwing distances 10 in the case of the middle water jets 19 which emerge from the middle outlet openings than in the case of lateral water jets 19, the recesses 4b, 4d arranged between the first recess 4a and the last recess 4c have an inner cross-sectional width 8i and a cross-sectional height 9 of approximately each 2 mm on. This results in a larger minimum cross-sectional area of these recesses 4b, 4d in an interior of the spray insert than the first recess 4a and the last recess 4c.

Furthermore, the recesses 4b, 4d arranged between the first recess 4a and the last recess 4c have an opening angle ϕ which is greater than 0 ° and is usually between 2 ° and 30 °. These recesses 4b, 4d thus have a cross section which increases from the inside to the outside. In the case of middle recesses 4b, which have a maximum opening angle ϕ, the opening angle ϕ in the exemplary embodiment is approximately 11 °. Due to the opening angle ϕ which differs from 0 °, an outer cross-sectional width 8a in these recesses 4b, 4d is larger than an inner cross-sectional width 8i, which means that a cross-sectional area of these recesses 4b, 4d is also larger on the outside than in an interior of the spray insert 1. A cross-sectional height 9 with all recesses 4a, 4b, 4c, 4d, as a rule, constant from the inside to the outside. This results in a along the longitudinal axes 22 of the recesses increasing cross section and thus an approximately horizontal fanning out of a water jet 19 flowing through recesses 4b, 4d with an opening angle ϕ of more than 0 °.

In the spray insert 1 shown, an outer cross-sectional width 8a at the first recess 4a and the last recess 4c is approximately 1.8 mm and increases up to three central recesses 4b, in which the outer cross-sectional width 8a is approximately 3.5 mm. A maximum cross-sectional area of the central recess 4b on an exterior of the spray insert is therefore 7 mm ² . The recesses 4d arranged between the first recess 4a and the middle recesses 4b have an outer cross-sectional width 8a which is between 1.8 mm and 3.5 mm.

In the exemplary embodiment shown, all the recesses 4b, 4d between the first recess 4a and the last recess 4c, that is to say also the middle recesses 4b, have an identical inner cross-sectional width 8i of 2 mm. An alternative embodiment is also possible, in which an inner cross-sectional width 8i of the central recesses 4b is larger than an inner cross-sectional width 8i of the first recess 4a and the last recess 4c, recesses 4d arranged between them having an inner cross-sectional width 8i which is larger than the inner one Cross-sectional width 8i of the first recess 4a and the last recess 4c and smaller than an inner cross-sectional width 8i of the central recesses 4b.

The spray insert 1 has an outer diameter 20 of approximately 41.5 mm and an inner diameter 21 of approximately 24 mm. In order to avoid that, in addition to a roadway to be irrigated, vehicle parts such as headlights, brake disks or brake shoes are also wetted with water by the vehicles passing the sprinkler 3, the spray insert 1 has an inclination angle δ of longitudinal axes 22 of the recesses 4a, 4b, 4c, 4d from about 13 °. The spray insert 1 shown has 11 recesses 4a, 4b, 4c, 4d, which are arranged distributed over an angle β of approximately 160 °. This angle β is preferably 140 ° to 180 °. In a particularly preferred embodiment, 13 recesses 4a, 4b, 4c, 4d are provided, an angle β between a longitudinal axis 22 of the first recess 4a and a longitudinal axis 22 of the last Recess 4c is approximately 170 °. This can result in Fig. 1 spray pattern 2 shown are formed in a particularly simple manner.

In order to achieve the desired spray pattern 2 with the spray insert 1, the spray insert 1 is generally arranged in a sprinkler 3 or in a nozzle 16 of a sprinkler 3.

Fig. 7 and 8 show a sprinkler 3 according to the invention, wherein Fig. 7 the sprinkler 3 in a perspective view and FIG. 8 shows a sectional view of the sprinkler 3. Like the one in the document EP 2 843 132 A2 The sprinkler 3 described and illustrated also has a sprinkler 3 with a connection 12 for a water supply line, a cladding tube 13, an intermediate part 14, an upper part 15 and a nozzle 16 arranged in the sprinkler 3. The sprinkler 3 according to the invention is used to achieve a Fig. 1 shown spray pattern 2 formed. For this purpose, a spray insert 1 is arranged in the nozzle 16 and fixed by a fixing screw 17. Outlet openings for individual water jets 19 are formed in that an elongated, open side of the recesses 4a, 4b, 4c, 4d is covered by a conical surface of the fixing screw 17. Channels are thus formed which connect an interior or a central space 11 of the sprinkler 3, in which the water pressure is present during operation, to an exterior and have outlet openings with a cross section corresponding to a cross section of the respective recesses 4a, 4b, 4c, 4d. The sprinkler 3 is normally arranged in a roadway in such a way that an upper end of the sprinkler 3 is approximately flush with the roadway, so that the outlet openings are positioned approximately at a height of the roadway. An axis of rotation 5 of the sprinkler 3, about which the spray insert 1 is preferably rotatably arranged in the sprinkler 3, is approximately perpendicular to a road surface in a working position of the sprinkler 3.

In order to achieve a uniform irrigation of the roadway, it is advantageous if the sprinkler 3 is operated at a water pressure of approximately 1 bar. Of course, another liquid can be used instead of water to achieve a wet road or a desired coefficient of friction.

A spray pattern 2 that can be achieved with the sprinkler according to the invention enables particularly favorable conditions for vehicle dynamics checking by fanning out water jets, with influences being avoided both in a lighting system and in a braking system of vehicles due to a low throwing height.

Claims (10)

1. A sprinkler (3) for the watering of a road surface, such as a driving technique track or a test track, with outlet openings for the delivery of a liquid, wherein at least one outlet opening has a cross-section that increases from an interior of the sprinkler (3) to an exterior of the sprinkler (3), and thus has an opening angle of more than 0°, wherein the outlet openings are arranged distributed over only part of a periphery of the sprinkler (3), and a central outlet opening is provided, arranged between a first outlet opening and a last outlet opening, which has a larger opening angle (ϕ) than the first outlet opening and the last outlet opening,
   characterised in that the outlet openings are designed and arranged in such a way that, if the outlet openings are positioned approximately at the level of the road surface to be watered, a spray pattern (2) with a maximum spray angle (α) of 180° results, when a water pressure of approximately 1 bar is applied to the sprinkler (3), wherein a ratio of a length (6) of the spray pattern (2) to a width (7) of the spray pattern (2) is 2 to 4, preferably 2.5 to 3.5, in particular 2.8 to 3.2, wherein at least one outlet opening, in particular the central outlet opening, has an opening angle (ϕ) of 5° to 15°.
2. The sprinkler (3) according to Claim 1, characterised in that a spray insert (1), in particular a spray ring, is arranged in the sprinkler (3), with recesses (4a, 4b, 4c, 4d), which at least partially define the outlet openings for the formation of a spray pattern (2), wherein at least one recess (4a, 4b, 4c, 4d) has a cross-section increasing from an interior to an exterior.
3. The sprinkler (3) according to Claim 2, characterised in that the recesses (4a, 4b, 4c, 4d) have an approximately rectangular, in particular an approximately square, cross-section.
4. The sprinkler (3) according to one of the Claims 2 or 3, characterised in that a minimum cross-sectional width (8i) and a cross-sectional height (9) of the recesses (4a, 4b, 4c, 4d) are 1 mm to 3 mm, in particular 1.5 mm to 2.3 mm.
5. The sprinkler according to one of the Claims 2 to 4, characterised in that at least one central recess (4b) is provided, which is arranged between a first recess (4a) and a last recess (4c), and has a larger minimum cross-sectional area, and/or a larger opening angle (ϕ), than the first recess (4a) and the last recess (4c).
6. The sprinkler (3) according to one of the Claims 2 to 5, characterised in that minimum cross-sectional areas, and/or opening angles (ϕ), of the recesses (4d) increase from the first recess (4a) towards the at least one central recess (4b), and decrease from the at least one central recess (4b) towards the last recess (4c).
7. The sprinkler (3) according to one of the Claims 1 to 6, characterised in that at least one recess (4a, 4b, 4c, 4d), in particular a central recess (4b) arranged between a first recess (4a) and a last recess (4c), has an opening angle (ϕ) of 10° to 12°.
8. The sprinkler (3) according to one of the Claims 2 to 7, characterised in that at least one recess (4a, 4b, 4c, 4d) is provided, which has a constant cross-section from an interior to an exterior.
9. A road surface, in particular a driving technique track or a test track, with a sprinkler (3) for watering the roadway, characterised in that a sprinkler (3) according to one of the Claims 1 to 8 is arranged in the road surface.
10. A method for watering a road surface, in particular a driving technique track or a test track, with a sprinkler (3), wherein water emerges from at least one outlet opening of the sprinkler (3), which has a cross-section increasing from an interior to an exterior, characterised in that the sprinkler is a sprinkler according to one of the Claims 1 to 8, and the watering takes place at a water pressure of approximately 0.5 bar to 1.5 bar, and with a spray pattern (2) with a spray angle (α) of preferably a maximum of 180°, wherein a ratio of a length (6) of the spray pattern (2) to a width (7) of the spray pattern (2) is 2 to 4.

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