A DEVICE AND A METHOD FOR APPLYING MARKINGS ON A SOLID CARRIAGE WAY INSTALLATION; SUCH AS APPLICATION OF ROAD MARKING LINES

Abstract: A system for the application of markings to a fixed traffic-bearing substrate, such as road marking lines, comprising a supply tank (2) for the marking material. The material is fed from the tank to applicator means (20a-20c), such as an applicator, an extruder or a spray head, by means of which the material is applied to the substrate. Two feed containers (4a, 4b) are inserted between the supply tank and the applicator, which feed containers are alternately filled and feed the applicator. This provides an even flow of marking material in contrast to known structures based on a mechanical pump which may give a pulsating flow. With level meters in the feed containers it is possible to record and adjust the applied amount of material per unit of area.

Description: A DEVICE AND A METHOD FOR APPLYING MARKINGS ON A SOLID CARRIAGE WAY INSTALLATION; SUCH AS APPLICATION OF ROAD MARKING LINES The invention relates to a system for the application of markings to a fixed traffic-bearing substrate, such as application of road marking lines, and comprising a supply tank for the material and an applicator for producing the markings as well as means for supplying the applicator with material from the tank. The invention moreover relates to a method of applying markings to a fixed traffic-bearing structure, such as application of road marking lines, and to a method of setting or adjusting the laying-out amount for the application of markings to a fixed traffic-bearing structure, such as application of road marking lines. Further, the invention relates to a control system for performing one of the methods on the system. The markings are typically the markings which are found on asphalted roads, parking sites, in airport and harbour areas, e.g. solid or broken lines, road side lines, mandatory stop lines ("shark's teeth"), etc. In principle, there are two forms of road marking materials, viz. one- component and two-component paints, e.g. acrylic polyester which is sprayed and thermoplastic materials which are applied as a band by means of an extruder head. The latter may also be sprayed. The viscosity of the materials varies very widely. Some materials are heated to about 200 °C, while other materials may be used down to about 5 °C . Further, the materials may contain large amounts of fillers, such as calcined flint, to achieve specific properties. The systems are typically provided as a special purpose vehicle or mounted on a truck chas- sis. Owing to the nature of the marking materials, the equipment has to satisfy huge requirements. In addition to the immediate requirements, it is required these days that the quality of the marking works performed should be documented, typically expressed by the amount of applied material per unit of area. Material is fed from the tanks to the spray or applicator head by means of a specially constructed gear wheel pump. For a uniform thickness of the markings to be achieved, it is decisive that the ma- terial is fed to the applicator in an even flow. On the face of it, a mechanical pump supplies an even flow, but on closer inspection the flow may be pulsating in reality. The pulsating flow may result in a disuniform thickness of the markings. Many stoppages and interruptions may occur in mechanical pumps because the moving parts are in contact with the highly abrasive material which is handled m the pump, just as mechanical pumps contain many individual parts which wear. Furthermore, so-called drag drawers are known, said drawers being formed with a slot opening at the bottom of a container which is normally provided with a slidable plate so that the slot opening may be adjusted to a given application thickness. This type, however, is extremely slow in use and is therefore unsuitable for the application of markings over long stretches and on coarse road surfaces . US-A-3 373 938 discloses a device for the application of line markings by spraying. This device contains a tank with paint to which a pressure is applied from a compressor so that the paint is pressed out through a spray nozzle and is applied to the substrate. The device, however, is a manually driven device, which thus makes it unsuitable for the application of markings over long stretches . An example of a system for the application of two-compo ¬ nent paint is e.g. French Patent Specification No. 1 492 468, which describes a process and a mobile device for the application of two-component paint to a road. The two paint components are stored in their respective containers, from which they are pressed out by means of simultaneously acting pressure pistons and are joined in a mixing chamber, following which the mixed paint is ap- plied to the road. The amount applied may be difficult to control in this device. This is a problem particularly when applying paint over long stretches and when the rate of application varies. Furthermore, for two-component paint types it is extremely critical to the quality of the road markings if the proper mixing proportion is not obtained. Accordingly, the invention is intended to provide a sys ¬ tem for the application of marking material to a road surface which obviates the above-mentioned drawbacks. Further, the object is to provide a system which enables the applied thickness of layer to be dosed and controlled so that its thickness on the road may be kept constant irrespective of the speed of the vehicle, just as the thickness may be changed. The invention realizes that an even flow may be obtained in a particularly simple manner by inserting two feed containers between the supply tank and the applicator, and the system in general is moreover arranged such that the applicator is alternately fed from the two containers which are filled in opposite step from the supply container. Suitable switching between the two feed containers makes it possible to feed the applicator with an even flow of material. To ensure a uniform and unaffected flow of material in connection with the switch between the two feed containers, a distributor is interposed between the feed containers and the applicator means in the preferred embodiment of the invention. Furthermore, the switch between the containers will be able to avert flow interruptions, if any, by using a switching valve with delay, which means that the second container is opened before the first container is closed. When the feed containers, which are considerably smaller than the supply tank, are provided with level sensors, current control, adjustment and recording of the applied amount of material are enabled with suitable control and recording equipment. When the distance travelled and the width of the markings are additionally measured and recorded, it is possible to print out a certificate which, in addition to said information, gives information on the applied amount measured in marking material per unit of area. When several level measurements are performed dur ¬ ing emptying of the container, or when current level measurement is performed, it is possible to carry out adaptation to the desired accuracy. .An example with floats is given below, but, of course, other forms of level sensors may be used, e.g. ultrasound and gamma sensors, optical or pressure difference meters. As the feed containers are relatively small, the measurements and the system in general are not affected notice- ably by the ripples that might occur m the liquid during the movement of the vehicle. If a pressure tank is used as a supply container, a feed pump, which is the most vulnerable component in the known structures, may be omitted completely in the structure. In some cases it is preferred to omit pressure tanks, as it requires special measures, particularly when they are transported on the roads. The invention makes it possible to use a pressure-less supply tank, but then it is neces- sary to use a pump for supplying the feed containers. But in that situation the pump does not have to meet special requirements, except that it has to serve as a supply pump, thereby allowing more sturdy pump types to be used, e.g. a hose pump. The preferred embodiment, however, uses a pressure tank, the paint being alternately transferred to the one or the other container by means of a feed pressure from a source of compressed air. In respect of two-component paints it is important that the components get in contact with each other as shortly before the application as possible, otherwise the system "cakes". For this purpose the system is built as a double system with two supply tanks, viz. one for each component, there being two feed containers for each supply tank. Only after the feed containers are the two components joined. These as well as further embodiments of a system according to the invention are defined in subclaims 2-11. The invention moreover relates to a method for the application of markings to a fixed traffic-bearing structure, such as application of road marking lines, wherein the marking material is conveyed from a supply tank alter- nately to two smaller feed containers, from which the material is fed alternately from the one and the other container to an applicator by means of which the material is applied to the substrate, and discharge from the one container takes place while the other container is being filled, and to a method for the setting or adjustment of the application amount of material from a system for the application of markings to a fixed traffic-bearing substrate, such as application of road marking material, and comprising a supply tank for marking material from which the material is fed to applicator means, such as a nozzle or an extruder, wherein the applicator means are temporarily closed and the fed material is returned to the supply tank, the amount thus returned being recorded as a function of the feed pressure for the calibration of the settings for the application. A further aspect of the invention is a control system for controlling the application in the system comprising recording means for measuring application parameters, such as application rate, application amount, feed pressure, viscosity of the material, temperature of the material, air temperature, air humidity and/or liquid level in the feed containers, data processing means for processing the recorded data, a control panel for operating the system, and control signal carrying connections to the valve and pressure regulation means in the system for the control of these means. The invention will be described more fully below with reference to the accompanying drawing, in which: fig. 1 shows a diagram of a system according to a first embodiment of the invention, fig. 2 shows a diagram of a system according to a pre- ferred embodiment of the invention, fig. 3 shows a detailed view of a constructional detail in connection with the venting of the feed containers, and fig. 4 shows a fraction of a float structure, special to the invention, for use in the feed containers . As will appear from fig. 1, the main components of the system are formed by a supply tank 2 for the road marking material and two smaller feed containers 4a, 4b. The supply tank 2 may be a pressure tank which communicates with a source 5 of compressed air, such as a compressed air container, via the line 6 so that the contents in the tank are under pressure. The supply tank 2 is connected with the feed containers 4a, 4b via a filling reservoir and further via a filling line 8 which branches 10a, 10b. A valve 12a, 12b is inserted in each of the branches 10a, 10b. The feed containers 4a, 4b are additionally connected with the source 5 of compressed air via the line 6, the line 14 and the branches 16a, 16b, so that also the contents in the feed containers 4a, 4b are under pressure, but a regulatable pressure (the feed pressure) , which may be different from the pressure in the supply tank 2, controlled by a pressure regulator 18 in the line 14 and a pressure regulator 19 in the line 6, respectively. The material is fed from the feed containers 4a, 4b via the lines 22a, 22b to a distributor container/retainer 44, from which it is distributed to one or more applicator nozzles 20a-c, which each are connected to the retainer 44 by a feed line 24. A valve 26a, 26b is inserted in the lines 22a, 22b, and a metering valve 28a-c for the adjustment of the discharge amount is inserted in each of the feed lines 24a-c, each of said applicator nozzles 20a-c being connected with a cut-off valve 29a-c. The valves 12a, 12b; 17a, 17b; 26a, 26b; 28a-c; 29a-c; 48a, 48b, the pressure regulators 18, 19, 19a and the sensors 7a-7j are connected to a control system for the system. The control system adjusts the valve and pressure regulation means in accordance with the selected program for the application. The control system is moreover pro- vided with programs for valve adjustment for the emptying, cleaning and/or pressure relief of the system. The control system is moreover adapted to correct for changes in the application parameters, such as application rate, application amount per unit of area, feed pressure, vis- cosity of the material, temperature of the material, air temperature, air humidity and/or liquid level in the feed containers . When material is applied from the feed container 4b, the venting valve 48b is closed so that the liquid in the container is under pressure. The valve 17a is closed while the valve 17b is open. The valve 12b is closed and the valve 26b is open, and 26a is closed. When application from the feed container 4b is started, the sensor 7a is moreover affected to indicate that the liquid level m the first feed container 4a is at the lowest permissible level . While pamtmg/application from the second feed container 4b is performed, the contacts are broken/the sensors 7j~ 7f are affected currently. These signals are used for current ckeck of the applied amount and control of this through possible correction of the feed pressure. The lower sensor 7f in the container 4b is used, like 7a, for initiating a container change and for subsequent main check of the application amount. When the sensor 7a is affected, the venting valve 48a opens so that the container 4a is relieved of pressure. With a time delay of between about 0 and 2 seconds - for carrying out the venting - the valve 12a opens in the filling system, thereby initiating the filling of the feed container 4a. As the filling proceeds and the liquid level in the container 4a rises, the sensors 7a to 7d are affected. Activation of the sensor 7e indicates that the container 4a is filled with paint, following which the valves 48a and 12a close, venting ceases and filling is interrupted. Then the valve 17a opens with a time delay of about 0-1 second to prevent air from being blown from the valve 17a out through the venting valve 48a. The con- tainer 4a now filled is thus subjected to the same air pressure as the other container 4b, and the paint in the container 4a is ready to be applied. When the sensor 7f in the container 4b is then affected and the container is thus getting empty, feeding of paint to the retainer 44 from the container 4a, ust filled, is allowed by opening the valve 26a. Feeding from the almost empty container 4b is cut off with a time delay of about 0-1 second by closing the valve 26b. While the first container 4a then paints, a corresponding filling process is carried out for the second feed con ¬ tainer 4a by precisely the same method. For the system to be emptied, the control system according to this aspect of the invention makes it possible to empty both feed containers 4a, 4b of paint. This takes place by blowing air into the container 4a through the valve 17a, whereby the paint from the container 4a, be- cause of the feed pressure from the compressed air tank 5, is simultaneously pressed out through the valve 26a and back into the supply tank 2 again by the calibration nozzle 20a arranged in connection with the supply tank 2. Then a corresponding operation is performed to empty the second container 4b, the valves 17a and 26 in connection with the first container 4a being closed again so that the feed pressure cannot escape through the empty first container 4a and stop the emptying of the second container 4b. The metering valves 28a-c, preferably made as ball faucets, are closed during the emptying process. In order to empty the supply string, the valves 12a and 12b open, thereby pressing the paint back to the paint filter and further back into the supply tank 2, following which the ball valve 8a closes. When the system is left, it is important that both containers and all hoses and strings are filled with paint, so that no dried paint residues settle in valves and the like. This takes place in that the valve 48a opens for venting, following which the valve 12a opens for filling of the container 4a. This filling takes place until the sensor 7e is affected, whereby the filling valve 12a closes. Then the venting valve 48a closes. The corresponding operation is then repeated for the second container 4b. All valves are hereby closed and the system is filled with paint and is pressure-less. The control system is arranged such that the various programs may be selected, following which the control unit in the form of e.g. a PLC control itself executes the valve setting sequences of the program. Furthermore, the control unit is equipped with a facility for toggling through a program sequence, preferably by means of a confirmation from the user on continuing to the next step. In addition to the above-mentioned programs, it is moreover considered advantageous that the system is provided with a "start program", so that no matter how much paint is left in the containers 4a or 4b, or no matter whether they are empty, the control system will provide for fill- ing of both containers and apply pressure to the system, thereby making the system ready to begin applying a road marking. The invention thus provides a constructionally simple system, which also enables data to be collected to determine the applied amount of marking material per unit of area. In a further aspect of the invention the top of the con- tamers may be provided with a safety valve, e.g. constructed as outlined m fig. 3. This figure shows a top flange 54 for a feed container, there being provided con ¬ necting branches 56, 58. All the venting and compressed air valves 48a, 48b and 17a, 17b are connected with the valve top 62 at the connecting branches 56, 58. The safety valve is composed of a float m the form of a ball 60 capable of floating on the surface of the paint when it rises above a certain level. The ball 60 is connected via a valve rod 61 with a valve head 64 which co-operates with a valve seat 62. The valve head 64 closes the opening m the valve seat 62 when the ball 60 is raised to a certain level, following which a pressure will be built up m the container 4a, 4b. The valve arrangement is mounted vertically slidably in a valve top member 70 on the flange 54. Downwardly, in its part protruding into the container, the valve top member is provided with one or more openings 60, so that the pressure in the container is always the same as m the valve top member 70. The valve seat 62 and the valve head 64 are arranged at the top of this top member 70. This pressure counteracts further filling. The ball 60 is constructed with a density which is much smaller than the density of the material, which is typically of about 1.0-2.0 g/cm . The ball 60 is hollow in the shown embodiment. The valve rod 61 is constructed as a pipe which is provided with a pressure equalization hole approximately at the centre, thereby ensuring that the same pressure prevails inside the ball 60 as in the container outside the ball 60. This prevents the ball from collapsing during the build-up of pressure in the feed container. It is realized in connection with the invention that this embodiment of a safety arrangement may be used in other types of pressure containers or tanks, in which a simple and reliable safety device is needed to prevent overflow.

Claims: P a t e n t C l a i m s : 1. A system for the application of markings to a fixed traffic-bearing substrate, such as application of road marking lines, and comprising a supply tank (2) for marking material, from which the material is fed to applicator means, such as a nozzle, an applicator or an extruder, c h a r a c t e r i z e d m that at least two feed containers (4a, 4b) are inserted between the supply tank (2) and the applicator means (20) , and that the system is arranged such that the applicator is alternately fed from one of the two containers, while the other or others are filled in the meantime. 2. A system according to claim 1, c h a r a c t e r i z e d m that the supply tank (2) is a pressure tank, from which the feed containers (4a, 4b) are filled by means of the pressure prevailing in the tank. 3. A system according to claim 1, c h a r a c t e r i z e d in that the supply tank (2) is a pressure-less tank, from which the feed containers (4a, 4b) are filled by means of a pump. 4. A system according to one of claims 1-3, c h a r a c t e r i z e d in that each feed container (4a, 4b) is provided with means for level measurement in the containers (4a, 4b) for measuring and recording the liquid level therein. 5. A system according to claim 4, c h a r a c t e r i z e d in that several level sensors m the form of floats (30-40) are arranged with the same mutual spacing in the height of the feed containers (4a, 4b) . 6. A system according to claim 4, c h a r a c t e r i z e d in that the level measurement means comprise a plurality of sensors (7a-7 ) so arranged on each feed container (4a, 4b) as to correspond to various liquid levels therein. 7. A system according to claims 1-6, c h a r a c t e r i z e d in that the feed containers (4a, 4b) are connected at the top with pressure means for feeding ate- rial from a container (4a, 4b) to the applicator means. 8. A system according to claims 1-7, c h a r a c t e r i z e d m that the applicator means comprise one or more applicator nozzles (20) , and that a distributor con- tamer (44) is inserted between the feed containers (4a, 4b) and the nozzle or nozzles (20a-20c) . 9. A system according to claim 8, c h a r a c t e r i z e d in that the distributor container (44) is con- nected with an applicator nozzle (20d) arranged in the supply tank (2) for setting or adjusting the application amount . 10. A system according to claim 9, c h a r a c t e r - l z e d m that it includes means for setting or adjusting the application amount through regulation of the feed pressure in the feed containers (4a, 4b) on the basis of recordings of parameters, such as feeα rate, temperature of material and air, and/or air humidity. 11. A system according to any one of the preceding claims, c h a r a c t e r i z e d in that, particularly for two-component marking paint, it comprises two supply tanks (2), one for each component, and that two feed con- tamers (4a, 4b) are associated with each supply tank, and that the system m general is arranged such that the two components are joined only after the feed containers (4a, 4b). 12. A method for the application of markings to a fixed traffic-bearing substrate, such as application of road marking lines, c h a r a c t e r i z e d in that the marking material is fed from a supply tank (4) alternately to two smaller feed containers (4a, 4b) , from which the material is fed alternately from the one and the other container to at least one applicator (20a-20c) by means of which the material is applied to the substrate, and that the discharge from the one container (4a, 4b) takes place while the other container (4a, 4b) is being filled. 13. A method for the setting or adjustment and calibration of the application amount of material from a system for the application of markings to a fixed traffic-bearing substrate, such as application of road marking lines, and comprising a supply tank (2) for marking material, from which the material is fed to applicator means, such as a nozzle or an extruder, c h a r a c t e r i z e d in that the applicator means are temporarily closed and the fed material is returned to the supply tank, the amount thus returned being recorded as a function of the feed pressure for the calibration of the settings for the application. 14. A control system for the control of the performance of a method according to claim 12 or 13 on a system according to any one of claims 1-11, comprising recording means for metering application parameters, such as application rate, application amount, feed pressure, viscosity of the material, temperature of the material, air tem- perature, air humidity and/or liquid level m the feed containers, data processing means for processing the re- corded data, a control panel for operating the system, and control signal carrying connections to the valve and pressure regulation means in the system for the control of these means. 15. A control system according to claim 14, c h a r a c t e r i z e d in that the system may be relieved of pressure completely or partly for storage or service of the system. 16. A vehicle on which a system for the application of markings to a road according to claims 1-11 is mounted. 17. A marking on a fixed traffic-bearing substrate, such as road marking lines on asphalted roads, applied by a system according to any one of claims 1-11 or the method of claim 12.

Inventors: JENSEN JOHN LETH, OLSEN CLAUS ENGFRED, JENSEN, JOHN, LETH, OLSEN, CLAUS, ENGFRED
Applicants: BORUM IND A S, JENSEN JOHN LETH, OLSEN CLAUS ENGFRED, BORUM INDUSTRI A/S, JENSEN, JOHN, LETH, OLSEN, CLAUS, ENGFRED
Application year: 1997
Main classification: E01C23
IPC codes: E01C23