Apparatus for marking paved surfaces

Abstract

A new marking apparatus for applying fusible organic-based particulate marking material through a flame to form a continuous marking on a paved surface. In this apparatus, forced air means forces a fuel-air mixture at high velocity through a chute means directed toward the paved surface. A set of kindling nozzles, also connected to the fuel supply, is disposed circumferentially around the end of the chute means, and ignites the fuel-air mixture passing through the chute means. Marking material is fed from a supply hopper into the chute means.

Description

Crosswalk stripes and other markings on paved surfaces are presently provided in a convenient and rapid manner by application through a flame of fusible organic-based particulate marking material. Once on the paved surface, the marking material forms a coalesced film that almost instantly hardens to a traffic-bearing condition. Harrington, U.S. Pat. No. 3,410,185 and Harrington et al, U.S. Pat. No. 3,664,242 describe the method used, and Eaton et al, U.S. Pat. No. 3,279,336 and Micheln, U.S. Pat. No. 3,393,615 describe equipment used for such marking operations.

The present invention provides a new apparatus for marking paved surfaces by the methods described in the Harrington and Harrington et al patents. This new apparatus is of a simplified construction that may be operated reliably over a long period of time with little maintenance; the apparatus develops a large volume of heat which is useful in causing the particulate marking material to form a smooth uniform coalesced film on the roadway; and the apparatus is inexpensive to manufacture.

Briefly, a marking apparatus of the invention comprises a frame supported by wheels and, mounted on the frame,

1. forced air means;

2. chute means connected to the forced air means and directed toward a paved surface over which the apparatus is moved;

3. a set of kindling nozzles disposed circumferentially around the end of the chute means and connected to the forced air means;

4. container means for particulate marking material disposed above said chute means and connected through metering means to said chute means so as to supply particulate marking material to said chute means; and

5. gaseous fuel means comprising a supply tank and conduit means connected between the supply tank and the chute means and the set of kindling nozzles so as to introduce gaseous fuel into the air stream moving through the chute means and kindling nozzles;

The forced air means supplying air through the chute means at a velocity such that a flame ignited at the end of the chute means is spaced from the end of the chute means.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation view of a marking apparatus of the invention, shown schematically for the most part;

FIG. 2 is a side elevation view of the marking apparatus shown in FIG. 1;

FIG. 3 is an end view of a nozzle of the apparatus shown in FIGS. 1 and 2; and

FIG. 4 is a section along the lines 4--4 in FIG. 2.

DETAILED DESCRIPTION

As shown in FIGS. 1 and 2, an illustrative marking apparatus 10 of the invention includes a frame 11 that comprises side beams 12 and cross beams 13. Wheels 14 carried on axles 15 attached to the side beams 12 by journals 16 support the frame 11 for movement along a paved surface. In this illustrative embodiment of the invention, movement is accomplished manually by an operator who grips a handle assembly 17 that is attached to the frame 11. The handle assembly is desirably off-center on the apparatus, so that an operator does not walk on an applied stripe and so that the operator has a better view of the marking operation.

Vertical struts 19 are attached to the frame 11, and floor panels 20 and 21 are attached between the struts. An air blower means 22 is mounted on one floor panel 20 and a pressurized supply tank 23 of liquified, normally gaseous (at atmospheric pressure) fuel is mounted on the other floor panel 21. The air blower means 22 comprises a generally cylindrical housing 24 in which a fan blade 25 rotates under the driving force of an internal combustion engine 26 (see FIG. 1) acting through a gear train. In other embodiments of the invention, forced air means other than an air blower means are used, such as a source of compressed air; but an air blower means is a preferred and economical way to provide a self-contained unit.

A supply hopper 28 for particulate marking material is supported by a frame assembly 27 and attached through passage means 29 and metering means 30 to a chute means 31 that comprises two barrels 32, 33 arranged side-by-side and at an inclined angle to the paved surface on which the marking apparatus moves. In the illustrated embodiment, particulate marking material moves by gravity from the supply hopper through the metering means into the chute means, but in other embodiments the particulate material is driven or drawn into the chute means. The barrels 32, 33 are connected directly to the air blower means 22, so that air put in motion by the fan blade 25 enters directly into the barrels. In the illustrated embodiment, the barrels are open to the air blower means over their whole cross-sectional area so that air moves through the barrels over that whole area, and particulate material is entrained in a stream moving through that whole area. In other embodiments the barrels are constricted to control velocity through the barrels (as with an orifice, at the connection to the air blower means, but more preferably with a screen or the like that permits fuel and air to move through the barrel over essentially its whole cross-sectional area), but before the moving stream reaches the end of the barrels it has preferably spread to the full cross-sectional area of the barrels.

Gaseous fuel is conducted from the supply tank 23 through a pressure regulator 36 and main conduit 37, then through branch conduits 38 and 39 having needle valves 40 and 41 adjustable from off to on, and then into the barrels 32, 33. The ends of the branch conduits 38 and 39 extend into the barrels (as shown in FIG. 4) and have openings 42 (perpendicular to the moving air stream in this embodiment) through which the gaseous fuel is drawn into the moving air stream. Good mixing is achieved before the fuel and air reach the end of the barrels. The positioning of the ends of the conduits 38 and 39 in the path of the air stream creates a venturi effect that enhances movement of the particulate into the moving stream.

The fuel-air mixture moves through the barrels at such a high velocity that any flame supplied by the fuel-air mixture would be spaced from the end of the barrels 32, 33, and preferably at such a high velocity that a flame could not normally be maintained at the end of the barrel. In the latter case it may be said that the velocity of the fuel-air mixture is higher than the rate at which a flame can be propogated back toward the barrels, and therefore the flame would normally be blown out. To achieve a flame fed by the fuel-air mixture moving through the barrels 32, 33, a set of nozzles 43 is provided around the end of the barrels. These nozzles extend from a manifold 44 which is supplied with a fuel-air mixture through a feed line 45 that is connected both to the air blower means 22, and through an adjustable needle valve, 46, to the fuel line. The gaseous fuel-air mixture moves from the manifold 44 into the nozzles 43 at a much lower velocity than the fuel-air mixture moves through the barrels 32, 33. In addition, as shown in FIG. 3, the burner nozzles 43 have an internal structure 50 that divides the fuel-gas mixture into three components. The fuel-air mixture travels through the apertures 51 and 52 so slowly that a flame fed principally through the central orifice 53 is always maintained within the nozzles in the area in front of the aperture-defining structure 50, with the flame extending out of the nozzles to the fuel-air mixture moving through the barrels 32, 33. The flames from the nozzles are hereinafter called kindling flames, and the nozzles are called kindling nozzles, since the flames ignite or kindle the fuel-air mixture traveling through the barrels 32, 33, which would otherwise be blown out.

Because of the high velocity of the fuel-air mixture through the barrels 32, 33, the flame created when the mixture is ignited by the kindling flames is spaced a finite distance--preferably at least about 1 inch--from the end of the barrels. The result is that the barrels are kept cool enough so that the particulate marking material will not soften and adhere to the inside of the barrels. In addition, because of the high velocity, the flame impinges on and heats the paved surface, even though the ends of the barrels are spaced from the paved surface being marked (to allow the marking material conducted through the flame to soften and to allow the stream of marking material to spread).

Sufficient kindling nozzles 43 are arranged around the end of the barrels 32, 33 so as to keep the fuel-air gas mixture at the end of the barrels ignited. The kindling nozzles 43 can be integrated into one or more housings providing one or more continuous ribbon-type flames around the end of the barrels. But despite integration of the nozzle structure, the nozzles must be thermally insulated from the barrels. The nozzles are typically ignited by an electric lighter (connected to the handle assembly by electric wiring that is not illustrated) or alternatively by a pilot flame connected to the gaseous fuel supply.

As shown in the illustrated embodiment, the passageways through the chute means are preferably straight-line and preferably of constant diameter to achieve a desired stream of fuel, air, and particulate marking material. The illustrated barrels are of rather large cross-sectional diameter (about one square inch or more). The exit end of the barrels may be shaped, as by the converging of the adjacent walls of the barrels in the illustrated embodiment, to control the amount of particulate marking material deposited over the width of a marking. The chute means can consist of a set of substantially parallel side-by-side barrels as in the illustrated embodiment, or of one or more unitary barrels of a wide or oblong cross-sectional area. In some embodiments of the invention the barrels are arranged to slightly converge as they near the paved surface so that the particulate marking material is discharged into the central portion of the flame emanating from the barrels. Plates 48 shield the flame at the ends of the barrels 32, 33.

In the illustrated embodiment, an air conduit 47 runs from the air blower means 22 to the supply hopper 28 to apply a positive pressure above the particulate marking material in the hopper; this positive air pressure assures that gaseous fuel entering the chute means 31 from the conduit means 37 does not enter into the hopper 28.

The metering means for the supply hopper 28 of this illustrative embodiment generally comprises a valve, such as a poppet valve or butterfly valve, which may be moved between an open and shut condition by the handle 49. In other embodiments, the valve is adjustable to allow different amounts of particulate material to be metered into the chute means 31, the amount metered depending on such factors as the thickness of marking that is desired and the rate at which the marking apparatus is to be advanced.

Claims

What is claimed is:

1. Apparatus for applying a fusible organic-based particulate marking material to paved surfaces to form instantly traffic-bearing markings on the paved surfaces, comprising a frame supported by wheels and, mounted on the frame,

1. forced air means,

2. chute means connected to the forced air means and directed toward a paved surface over which the apparatus is moved;

3. a set of kindling nozzles disposed circumferentially around the end of the chute means and connected to the forced air means;

4. container means for particulate marking material disposed above said chute means and connected through metering means to said chute means so as to supply particulate marking material to said chute means; and

5. gaseous fuel means comprising a supply tank and conduit means connected between the supply tank and the chute means and the set of kindling nozzles so as to introduce gaseous fuel into the air stream moving through the chute means and kindling nozzles;

the forced air means supplying air through the chute means at a velocity such that a flame ignited at the end of the chute means is spaced from the end of the chute means.

2. Apparatus of claim 1 in which the forced air means is an air blower that comprises a fan blade enclosed in a generally cylindrical housing.

3. Apparatus of claim 1 in which the forced air means is connected to the container means so as to apply a positive pressure within the container means.

4. Apparatus of claim 1 in which the downstream ends of the kindling nozzles terminate slightly downstream from the end of the chute means and are directed inwardly toward the axis of the chute means.

5. Apparatus for applying a fusible organic-based particulate marking material to paved surfaces to form instantly traffic-bearing markings on the paved surfaces, comprising a frame supported by wheels and, mounted on the frame,

1. air blower means comprising a fan enclosed in a generally cylindrical housing;

2. chute means having a straight passageway connected directly over its whole cross-sectional area to the housing of the air blower means and directed at an inclined angle toward a paved surface over which the apparatus is moved;

3. a set of kindling nozzles disposed circumferentially around the end of the chute means, terminating downstream from the end of the chute means, directed inwardly toward the axis of the chute means, and connected to the air blower means through an annular manifold arranged coaxially around the chute means;

4. container means for particulate marking material disposed above said chute means and connected through metering means to said chute means so as to supply particulate marking material to said chute means; and

5. gaseous fuel means comprising a supply tank and conduit means connected between the supply tank and the chute means and the set of kindling nozzles so as to introduce gaseous fuel into the air stream moving through the chute means and kindling nozzles;

the air blower means supplying air through the chute means at a velocity such that a flame ignited at the end of the chute means is spaced from the end of the chute means.

6. Apparatus of claim 5 in which the air blower means is connected to the container means so as to apply a positive pressure within the container means.

7. Apparatus of claim 5 in which the chute means comprises a set of barrels of large cross-sectional area.

8. Apparatus of claim 5 in which the conduit to the chute means terminates in needle-size openings inside the chute means.