The present invention concerns a method and device for the application of reflective road markings.

In particular, the present invention concerns a method and device for the application of road markings which are provided with glass beads, often also called micro glass beads .

Such micro glass beads concern spherical and translucent particles intended to ensure the night visibility of road markings by retroflection of incident light beams from vehicle lights towards the driver.

Often, mixtures of micro glass beads and roughening granules are provided on the road markings.

A known method consists in mixing the glass beads in the paint beforehand and then spraying this mixture on the road surface .

In order to obtain immediate retroflection, however, glass beads are scattered immediately after the application of the paint on the surface to be marked, on the applied paint .

Paint sprayers are presently used whose operation is based on the combined atomizing of paint and air. The glass beads are presently usually scattered manually on the marking product, immediately following the application of the latter on the road. However, experience shows that this method often does not result in a uniform distribution of the glass beads, is time-consuming and, more importantly, is often performed too late. The latter has the particular disadvantage that a film is already formed on the paint during the first drying, whereas the glass beads should be distributed on the paint layer while no film has been formed yet on the paint. A glass bead which settles in the paint by 60% and protrudes from the paint by 40% is considered to be an ideally applied glass bead.

If they are scattered too late, the glass beads will not settle sufficiently in the paint, with numerous adverse effects .

The retroflection of the incident light beams of the vehicle lights towards the driver is not ideal, and the loss of after-scattered glass beads increases considerably.

The present invention aims to remedy one or several of the above-mentioned and other disadvantages. To this end, the present invention concerns a method for the application of reflective road markings, which method comprises the steps of supplying paint or the like up to near a spray gun, supplying air via a primary air circuit to the same spray gun, initiating the throughput and mixing of paint and air by operating the spray gun, and thus atomizing the paint or the like mixed with air via a first nozzle on the zone to be marked, subsequently scattering glass beads or the like over the applied paint or the like, which method differs from the existing methods in that the glass beads or the like automatically obtain a passage, initiated by a recorded parameter fluctuation or parameter value, for example a pressure or flow fluctuation in the primary air circuit, from a reservoir to what is called a bead caster, where the glass beads are mixed with air being supplied via a secondary air circuit, which mixture is further supplied up to near the first nozzle of the mixture of paint and air, and whereby the glass beads are scattered via a second nozzle.

The nozzle is preferably appropriately oriented, for example at an angle between 15° and 75° in relation to the first nozzle.

Alternatively, deviation means are provided in the extension of the nozzle, so that by moving the spray gun, the paint or the like is first provided on the zone to be marked, after which the glass beads are immediately scattered over the applied paint.

It is clear that the paint may be any marking product whatsoever, and that the glass beads may also be other reflective particles and/or may possibly be mixed with other particles, such as for example roughening granules. A major advantage is related to time-saving, a more uniform distribution of the glass beads and the guaranteed quality of the placement of the glass beads in the paint. The present invention also concerns a device for the application of reflective road markings, which device comprises at least one spray gun with a supply pipe for paint or the like connected thereto, or what is called a paint line, and a primary air line connected to the spray gun which is part of a primary air circuit, which spray gun also comprises an operating device to start and stop the throughput and mixing of paint with air, which mixture can be atomized via a first nozzle, whereby the device comprises a glass bead reservoir, a bead caster for mixing the glass beads with air, which bead caster is provided with a controllable sealing device, a secondary air circuit connected to the bead caster, detection and control means for detecting a parameter fluctuation or parameter value, for example a pressure or flow fluctuation, in the primary air circuit and, when said parameter fluctuation or parameter value is detected, opening or closing the controllable sealing device and thus providing a passage to or stopping the glass beads from the glass bead reservoir to the bead caster and also providing a passage to or stopping the air through the secondary air circuit, whereby the device also comprises a glass bead line between the bead caster and the spray gun for the throughput of the glass beads mixed with air up to near the spray gun, which spray gun is provided with a glass bead feed-through channel, connected to the glass bead line at one end and provided with a second nozzle at the other end. The second nozzle is preferably directed at an angle in relation to the first nozzle, and/or deviation means are provided in the extension thereof, for example a small plate .

The advantages correspond to the above-mentioned advantages of the method according to the invention.

In order to better explain the characteristics of the present invention, the following preferred embodiment of a device for the application of reflective road markings according to the invention is described with reference to the accompanying drawings, in which: figure 1 schematically represents a spray gun which is part of the device according to the invention for the application of reflective road markings;

figure 2 schematically represents other components which are part of the device according to the invention for the application of reflective road markings .

Figures 1 and 2 together represent the device according to the invention.

Figure 1 shows a spray gun 1 which is connected to three supply lines: a primary air line 2 which is part of a primary air circuit 3, a paint line 4 and a glass bead line 5 for the throughput of glass beads mixed with air. The spray gun 1 includes a handle 6 and a control handle 7 and further a paint feed-through channel 8A, an air feed- through channel 8B and a glass bead feed-through channel 9. The paint feed-through channel 8A is connected to the paint line 4, the air feed-through channel 8B is connected to the primary air line 2, and both channels 8A and 8B open into an atomization chamber 10 which is connected to a first nozzle 11.

The glass bead feed-through channel 9 is connected to the glass bead line 5 at one far end and is provided with a second nozzle 12 at the other far end, and is provided with a deviation plate 13 in its extension.

It should be noted that the glass bead feed-through channel 9 with the possibly associated housing is detachably connected here to the paint feed-through channel 8A and the air feed-through channel 8B and the possibly associated housing of the latter throughput channels 8A and 8B.

Figure 2 schematically represents other components of the device according to the invention for the application of reflective road markings.

The bottom left of figure 2 represents the primary air line 2, the paint line 4 and the glass bead line 5 for the throughput of glass beads mixed with air, whereby the representation is interrupted here but which continue up to the spray gun 1. For clarity's sake, the pipes are represented here as single lines.

More particularly, the air pressure lines such as the primary air line 2 are represented by means of a dash-dot line, the paint line 4 is represented by means of a full line, and the glass bead line 5 for the throughput of glass beads mixed with air is represented by means of a dash-dot- dot line.

Finally, the measure and control lines are represented by means of a dashed line.

The device further comprises, as shown in figure 2, a paint reservoir 14 which is connected to an air pressure line 15 at the top on the one hand, provided with a pressure regulator 16 in this case, and connected to the paint line 4 at the bottom on the other hand. The device also comprises a glass bead reservoir 17 which is connected to an air pressure line 18 at the top on the one hand, in this case provided with a pressure regulator 19, and which is connected to a controllable sealing device 20 at the bottom which is provided in a bead caster 21 on the other hand.

This bead caster 21 is connected to a secondary air circuit 22 by means of a secondary air line 23 on the one hand, which is provided with a pressure regulator 24 in this case, and the bead caster 21 is connected to the glass bead line 5 for the throughput of glass beads mixed with air on the other hand. The air lines 15, 18 and 23, save for the aforesaid pressure regulators 16, 19 and 24 respectively, are directly connected to an air compressor 25.

The primary air circuit 3 of which the primary air line 2 forms part is also connected to the air compressor 25 and is also provided with a pressure regulator 26, but passes downstream thereof through a control module 27 where, according to the invention, detection and control means 28 are provided for detecting a parameter fluctuation or parameter value, in this case for detecting a flow rate or flow increase in the primary air circuit 3 and for controlling the controllable sealing device 20.

In particular, the detection and control means 28 comprise a flow sensor 28A which is electrically coupled to an electrically powered, controlled valve 28B. The detection and control means 28 are schematically represented here and their operation is simple and as follows .

The pressure sensor 28A generates a first electric signal when an adjustable pressure decrease is recorded, and it generates a second electric signal when an adjustable pressure increase is recorded.

These signals are the control signals for the electrically controlled valve 28B. In particular, in order to obtain a laminar air flow upstream the flow rate sensor 28A, one or several air filters are provided, for example a first air filter 28C class 40μπι and a second air filter 28D class 5μπι, and a distribution block or the like 28E is provided between these filters and the flow rate sensor 28A from which compressed air is obtained, used to provide the electrically controlled valve 28B with a constant pressure. As soon as a first electrical signal is transmitted from the flow sensor 28A to the electrically controlled valve 28B, it will let compressed air through which is in turn supplied to the bead caster 21. Stated differently, if the set air flow is reached in the primary air circuit 3, the valve 28B will let air pass through from the primary air circuit 3, which air is directed via a control line 29 to the controllable sealing device 20.

As a result, the controllable sealing device 20 is opened for the passage of air through the secondary air circuit 22 and for the passage of glass beads from the glass bead reservoir 17 to the bead caster 21.

Vice versa, when the air flow drops, or more generally when a second adjustable value is reached in the primary circuit 3, the valve 28B will close the passage of air from the primary air circuit 3, more particularly through the agency of a second electrical signal or the interruption of the first electrical signal from the flow sensor 28A to the electrically controlled valve 28B, as a result of which the controllable sealing device 20 is closed, such that the passage of air through the secondary air circuit 22 and the passage of glass beads from the glass bead reservoir 17 to the bead caster 21 stop.

As a result, the working of the device according to the invention and the method according to the invention for the application of reflective road markings are greatly simplified and improved, and they proceed as follows.

The user operates the spray gun 1 with the handle 6 and operates the control handle 7 as desired.

As a result, paint and air are fed through the paint feed- through channel 8A and the air feed-through channel 8B respectively into the atomization chamber 10, and they are mixed there and fed further through the first nozzle 11 to thus be applied on the zone to be marked by appropriately directing the spray gun 1.

As a result of the sudden air flow in the primary air circuit 3, a flow increase or a flow value is recorded in the primary circuit 3 by the detection and control means 28.

As illustrated above, thanks to the detection and control means 28, the adjustable sealing device 20 is then opened for the passage of air and glass beads respectively to the bead caster 21.

Note that air flows through the glass bead reservoir 17 as well as through the secondary air circuit 22. The mixture of glass beads and air leaves the bead caster 21 via the glass bead line 5, which mixture is carried up to the spray gun 1 and further through the glass bead feed- through channel 9 and the second nozzle 12.

The glass beads are immediately deviated somewhat here through the agency of the deviation plate 13. When the user lets go of the control handle 7, the air flow through the primary circuit 3 will decrease or become zero, as a result of which, thanks to the detection and control means 28, the adjustable sealing device 20 is closed. Note that the air pressure line 15, in this case provided with a pressure regulator 16, keeps the paint reservoir 14 at a suitable pressure for the throughput of the paint from the reservoir 14 up to the spray gun 1. Similarly, the air pressure line 18, in this case provided with a pressure regulator 19, will keep the glass bead reservoir 17 at an appropriate pressure for the throughput of the glass beads from the glass bead reservoir 17 up to the bead caster 21.

The throughput of the beads mixed with air up to the spray gun 1 and through the glass bead feed-through channel 9 and the second nozzle 12 is partly accomplished by the air flow in the air circuit 22 when the controllable sealing device 20 allows for it. The method and device according to the invention result in that, as soon as paint is atomized on the zone to be marked by appropriately directing the spray gun 1 and appropriately controlling the control handle 7, the glass beads will be automatically supplied as well and scattered on the paint. By appropriately moving the spray gun 1, paint is provided first, and immediately thereafter glass beads are scattered over the applied paint. It is clear that recording a parameter fluctuation or parameter value in the primary air circuit 3 may alternatively also concern a pressure fluctuation or pressure value, and that possibly also other parameters may be indicative.

The present invention is by no means restricted to the embodiments described by way of example and represented in the accompanying figures; on the contrary, such a method and device for the application of reflective road markings according to the invention can be made in all sorts of shapes and dimensions while still remaining within the scope of the invention.