IE940350A1 - A spray bar assembly - Google Patents

Abstract

A spray bar assembly, for use with a vehicle carrying a supply of liquid, comprises a tubular spray bar (1) having an inlet port (3) facilitating the in-flow of liquid from a reservoir and a plurality of sealable nozzles (7) for discharging a spray of liquid from the spray 10 bar, and individual actuating means (8) associated with each of said nozzles, characterised in that the spray bar further comprises an outlet port (4) allowing liquid to return to the reservoir, the inlet and outlet ports being located at opposite ends of the spray bar, and a pressure relief valve (5) at the outlet port for controlling the 15 pressure of liquid in the spray bar. The valve (5) will permit a leak off of excess liquid while maintaining a substantially uniform pressure in the spray bar (1) regardless of the number of nozzles (7) open. The pressure relief valve (5) comprises a bobbin type valve 20 controlled by compressed air at a pressure determined by reference to the desired operating pressure in the spray bar. The actuating means (8) associated with each spray nozzle (7) may comprise a remotely operable pneumatic actuator (20) or an induced 25 pressure actuator. The tubular spray bar is of square cross-section and defines first and second sets of apertures (18, 19) in opposite sides, arranged in pairs, the first set of apertures (18) being discharge apertures each 30 mounting a nozzle (7) and the second set of apertures each mounting an individual actuating means (20), each nozzle connected to its associated actuating means by an actuating shaft (14). The spray bar assembly may be used in conjunction with a tar or road binder spreading vehicle for road surface dressing.

Description

A SPRAY BAR ASSEMBLY The present invention relates to a spray bar assembly for applying a coat of liquid to a surface. In particular the invention relates to a spray bar assembly for use with a vehicle carrying a supply of tar or road making binder for spreading on a road surface at high temperature during re-surfacing or repair work.

It is known for a spray bar assembly to comprise a tubular spray bar having a plurality of spray nozzles with individual manual activation means, usually a tap, and an inlet port on the spray bar connected via a pump to a reservoir of liquid to be applied. The reservoir is carried by a vehicle to which the spray bar assembly is attached and the liquid is supplied to the spray bar by the pump at an approximately constant pressure. In practice, if a variation in the width of application is desired, a person is required to walk along close to the spray bar to actuate the appropriate nozzles.

There are a number of disadvantages with spray bar assemblies of this type. The fact that the individual nozzle actuation means are manually operated means that actuation of two or more nozzles simultaneously is difficult. Also, since the liquid is applied to the spray bar at an approximately constant pressure the spraying pressure 1107S applied to an open nozzle during use will vary according to the number of nozzles opened at any particular time. This can lead to non-uniformity in the thickness of the coat of liquid applied.

It is an object of the present invention to provide a spray bar assembly which allows precise control of coat width and thickness and permits automated and co-ordinated control of spray nozzles.

Accordingly, a spray bar assembly of the present invention, for use with a vehicle carrying a supply of liquid, comprises a tubular spray bar having an inlet port facilitating the in-flow of liquid from a reservoir and a plurality of sealable nozzles for discharging a spray of liquid from the spray bar, and individual actuating means associated with each of said nozzles, characterised in that the spray bar further comprises an outlet port allowing liquid to return to the reservoir, the inlet and outlet ports being located at opposite ends of the spray bar and a pressure relief valve at the outlet port for controlling the pressure of liquid in the spray bar.

The valve is preferably adapted to permit a leak off of excess liquid while maintaining a substantially uniform pressure in the spray bar regardless of the number of nozzles open.

Preferably, the pressure relief valve is variably controllable. More preferably it comprises a bobbin type valve controlled by compressed air at a pressure determined by reference to the desired operating pressure in the spray bar.

Typically, the actuating means associated with each spray nozzle may comprise a remotely operable pneumatic actuator or induced pressure actuator.

In a preferred embodiment the tubular spray bar is of square cross-section and defines first and second sets of apertures, in opposite sides, arranged in pairs, the first set of apertures being discharge apertures each mounting a nozzle and the second set of apertures each mounting an individual actuating means, each nozzle connected to its associated actuating means by an actuating shaft.

The pressure relief valve and/or the actuating means may be provided with a leak detection adaptor, comprising a cylinder having an axial bore for housing an actuating shaft and a radial bore leading from the axial bore to the outer surface.

The invention will now be described in more detail with reference to the accompanying drawings in which: Figure 1 is a plan view from above of a preferred embodiment of the spray bar assembly; Figure 2 is an elevation of the spray bar, viewed in the direction of arrow A (shown in Figure 1); Figure 3 is a sectional perspective view of the valve controlling the flow of liquid through the spray bar; Figure 4 is a sectional perspective view of the spray bar with a spray nozzle and one embodiment of the actuating means; Figure 5 is a sectional perspective view of a spray nozzle; and Figure 6 is a sectional perspective view of the spray bar with a spray nozzle and alternative actuating means.

With reference to Figures 1 and 2 the spray bar assembly comprises a tubular spray bar 1 attachable to a vehicle (not shown), by means of brackets 2, and having an inlet 3 and an outlet 4 at opposite ends thereof facilitating the flow of liquid through the spray bar 1. The inlet 3 is connected by suitable conduits to a conventional pump (not shown) which in turn is connected to a conventional tank on the vehicle holding a supply of liquid, particularly road-surfacing binder. The spray bar 1 defines a plurality of discharge apertures 18 in its lower face each mounting a spray nozzle 7. Each spray nozzle 7 has actuating means 8 associated therewith, the actuating means being mounted in apertures 19 in the spray bar above the discharge apertures.

The flow of liquid through the spray bar 1 is controlled by a valve 5 shown in more detail in Figure 3. The valve 5 comprises a pressure relief chamber 12 having an entry port 10 and exit port 11 and a bobbin 9 connected to a direct push type air cylinder 6 outside the chamber by a rod 12a. The entry port 10 is connected to the spray bar outlet 4 and the exit port 11 is connected by a suitable conduit to the tank on the vehicle. The crown 9a of the bobbin seals against a seat 9b in the entry port 10. The rod 12a passes out of the chamber through a sealing gland 25 and passes through a leak detection adaptor 26 (also described below with reference to Figure 4) before entering the cylinder 6 where it is connected to a conventional piston (not shown). The cylinder 6 is actuated from an auxiliary air tank supplied by the pneumatic system of the sprayer unit. Air pressure on the piston of the cylinder 6 is regulated to a fixed working pressure approximately 4 times that of the spray bar operating pressure. The ratio of the surface area of the crown 9a of the bobbin valve to the area of the piston in the cylinder 6 is approximately 4 to 1. Allowing for friction at the gland 25, this will result in a consistent operating pressure in the spray bar.

The bobbin valve will be closed initially. The liquid in the spray bar will be blocked by the crown 9a of the bobbin until the pressure builds up to that selected. The bobbin will then move against the air pressure in the cylinder 6 and will be unseated so that excess liquid can leak through into the chamber 12 and then circulate via the exit port 11 back to the tank. Thus, the valve 5 ensures that the spraying pressure in the spray bar does not exceed the optimum pressure, regardless of the number of nozzles which are open. The optimum pressure may be pre-set by means of an adjustable pressure regulator.

Referring now to Figure 4, the actuating means 8 associated with each spray nozzle 7 may comprise a remotely operable pneumatic actuator. In the preferred embodiment shown in Figure 4 the spray bar 1 is of square box cross section and as well as defining a plurality of discharge apertures 18 on the lower face, also defines a second set of associated apertures 19 on the upper face of the spray bar 1 so that the apertures occur in pairs with each discharge aperture 18 having a ΤΙ - 5 second associated aperture 19. Each discharge aperture 18 mounts a spray nozzle 7, and each spray nozzle 7 has actuating means 8 communicating through the associated aperture 19. As shown in Figure 4 and in more detail in Figure 5, each nozzle comprises a hollow cylindrical neck 30, a disc shaped flange 31 with holes 32 therein for attachment of the nozzle by screws 33 to the lower face 34 of the tubular bar, and a cylindrical head 35 having a slot type jet 36 cut therein with the lateral axis of the slot arranged so that when the nozzle is screwed onto the spray bar the axis of the slot is at an angle to the axis of the bar. The passage 37 inside the neck 30 extends through the flange 31 and head 35 to communicate with the slot 36. The angle of the slot is machined to a specific angle of 5 to 25 degrees, for example, to allow correct overlap of the spray from one jet to the next. The slot type jets give a fan shape spray without atomising the binder and cut down on mist pollution. However conventional cone type jets may be used if desired for other end uses.

In the embodiment shown in Figure 4 the actuating means 8 comprises a remotely operable pneumatic actuator 20 having an actuating stem 14 connected to a spigot 15 which seats on the top of the neck 30 of the nozzle 7 forming a valve 38. The pneumatic actuator 20 causes the actuating stem 14 and thus the spigot 15 to move up and down in relation to the spray nozzle 7, causing the valve 38 to be opened or sealed closed. The pneumatic actuator 20 is a pull-type air cylinder with a spring return and positive cut-off valve. Thus the rest position of the actuator holds the valve 38 closed. When air pressure is applied to the cylinder 20 (by an air system parallel to that which activates the pressure control valve 5) a piston inside the cylinder 20 is lifted against the pressure of a spring inside the cylinder, thus opening the valve 38 to allow liquid to flow through the nozzle 7 to the jet 36. By control of the individual pneumatic actuators 20, the jets can be opened or closed in any order and in any number as desired, to control the width and location of the liquid sprayed.

Figure 4 also shows a leak detection adaptor 13 located between the aperture 19 and the pneumatic actuator 20. A similar device 26 may be fitted to the valve 5 as shown in Figure 3. The leak detection adaptor 13 is designed to detect air leaking from the pneumatic actuator 20 (or the air cylinder 6 shown in Figure 3) and liquid 940360 - 6 leaking from the spray bar 1. The leak detection adaptor 13 comprises a cylindrical body 21 having an axial bore 22 for receiving the actuating stem 14 slidably therein and a side port 16 leading from the axial bore 22 to the outer cylindrical surface 17 of the body 21. The body is in screw threaded engagement with the pneumatic actuator 20 at its first end.

At the second end of the body 21 the radius of the axial bore 22 is greater than that of the actuating stem 14. The second end of the body 21 has an external thread 25 and an internal thread 26. The leak detection adaptor 13 is mounted in the aperture 19 and held therein by the external thread 25. A plug 23 engages the internal thread 26 and screws into the second end of the body 21 around the actuating stem 14, locating a sealing gland 24 around the actuating stem 14 and between the body 21 and the plug 23. If air is leaking from the system, soapy water or aerosol spray foam applied to the side port 16 will indicate a leak if bubbles form, or a stream of air from the side port may be felt or heard.

The embodiment shown in Figure 6 is similar to that of Figure 4 except that the pneumatic actuator is of the induced pressure type. Instead of a pull type air cylinder 20, the actuator 40 comprises a diaphragm 41 which is secured to the stem 14 by plates 42, 43 which capture the diaphragm, and whose periphery is held in a cap 44 fixed to the top of the spray bar in an aperture 19a which is considerably larger than the aperture 19 in Figure 4. A spring 45 between the top plate 42 and the head of the cap 44 urges the stem 14 downwardly to close the valve 38. The diaphragm 41 lifts valve 38 by the pressure of liquid applied to it as liquid is pumped through the spray bar when the pressure relief valve 5 has been activated.

The actuators 20, 40 can be pneumatically operated from the cab of the vehicle on which the spray bar assembly is mounted, and no external moving parts such as levers or taps are required. Remote control is also an option. The flow system can be totally controlled by electrical and/or pneumatic means. The jets can be easily changed for ease of maintenance and/or to vary the size and type of jet. The valves are kept in the closed position by means of springs which are load-rated to protect against premature opening. - 7 The cylinder may be fitted with seals of temperature resistant material such as that sold under the Trade Mark VITON.

If desired, heat from the coolant of the vehicle engine may be transferred to the pump by means of a jacket around the pump, so that it is kept hot before use.

Because of the consistent operating pressure regardless of how many jets are open, the sprayer can be coupled to a microprocessor since an established output per jet can be relied upon to give an accurate input figure. The microprocessor can be used to monitor the flow of liquid and/or to control the operation of the pneumatic actuators and/or the pump. The microprocessor may be used to coordinate the forward speed of the vehicle and the spray output in litres per minute, the width of the spray at any given time, and to calculate the rate of spread of the binder and thickness of film applied to the road surface. It would also record elapsed time, and indicate job starting and stopping times. Job instructions could be keyed in before the start of a job, so that driver performance could be monitored, i.e., the supervisor would have a record of when, and by what factor the rate of spread has varied from the instructions given. Sensors linked to the microprocessor could be used to measure temperature and pressure of the binder in the spray bar and give a continual reading. All information from the onboard microprocessor could be downloaded to a floppy disc to enable performance monitoring to be carried out on a P.C. or portable computer.

Claims (5)

1. A spray bar assembly of for use with a vehicle carrying a supply of liquid, comprises a tubular spray bar having an inlet port facilitating the in-flow of liquid from a reservoir and a plurality of sealable nozzles for discharging a spray of liquid from the spray bar, and individual actuating means associated with each of said nozzles, characterised in that the spray bar further comprises an outlet port allowing liquid to return to the reservoir, the inlet and outlet ports being located at opposite ends of the spray bar, and a pressure relief valve at the outlet port for controlling the pressure of liquid in the spray bar.

2. A spray bar assembly according to claim 1 wherein the pressure relief valve comprises a bobbin type valve controlled by compressed air at a pressure determined by reference to the desired operating pressure in the spray bar.

3. A spray bar assembly according to claim 1 wherein the actuating means associated with each spray nozzle comprises a remotely operable pneumatic actuator or induced pressure actuator.

4. A spray bar assembly according to any of the preceding claims wherein the tubular spray bar is of square cross-section and defines first and second sets of apertures, in opposite sides, arranged in pairs, the first set of apertures being discharge apertures each mounting a nozzle and the second set of apertures each mounting an individual actuating means, each nozzle connected to its associated actuating means by an actuating shaft.

5. A spray bar assembly substantially as described herein with reference to and/or as illustrated in the accompanying drawings.