DISPENSING HEAD FOR A BOOM OF A ROAD REPAIR VEHICLE

Field

The present invention is related to road repairs, and specifically to a dispensing head for a road repair vehicle for dispensing road repair material.

Background Of The Invention

GB2368084 discloses a boom for a road repair vehicle of the type including a dispensing head 26 at the free end of the boom for dispensing a road repair material and at least one hose extending along the boom for delivering said material to the head from a supply of said material on the vehicle. The boom comprises a deflection member 36 movably mounted on the boom from a first state in which it is, in use, deployed beneath the head, to a second state in which it is substantially clear of the head. The operation of such a vehicle is described in GB2368084.

Figure 1 of the present application shows the material being pneumatically conveyed horizontally through a hose 25 and changing direction to vertical before it exits a mixing chamber 26a. Referring to Figure 1 , behind a spray jet 47, a pneumatically controlled plunger 55 controls a blocking mechanism 57 which determines whether binder, or tar, will flow to a horizontally disposed jet 59 located within the dispensing head 26, where it will spray dispensed gravel, or to the spray jet 47 which may be employed to spray a road surface directly. An operator can select a number of modes of operation of the boom according to the state of the various pneumatic, or alternatively electric or hydraulic controls. For example, binder only can be sprayed. In this case, in order to supply binder to the spray jet 47 its controls 49 are used to turn on the spray jet 47. This is used to prepare a road surface to be re-dressed. A deflection plate 36 can either be deployed or retracted as it preferably does not interfere with binder being sprayed from the spray jet 47. In another mode, gravel only is dispensed through the head 26. In this case, binder is available to the spray jet 47 and its controls 49 are actuated to cut off the spray jets 47. A cylinder 39 can be extended or retracted according to whether or not the operator wants the gravel to be dispensed widely or locally. Usually, the operator would deploy the deflection plate to spread gravel widely over a pre-tarred surface. In another mode, tarred gravel is dispensed through the dispensing head. The plunger 55 is set to supply tar only to a spray jet 59 within the dispensing head 26. The deflection plate 36 can be either deployed or retracted. Usually, it will be retracted to fill a pothole with tarred gravel and deployed to re-dress either a pre-tarred road or an untarred road.

The material, or aggregate, passes through a spray of bitumen binder in the dispensing head 26. The dispensing head 26 defines the mixing chamber 26a for mixing aggregate and binder. Construction aggregate, or simply "aggregate", is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. The aggregate is coated with binder as is passes through the spray mist. As the aggregate exits the mixing chamber 26a of the dispensing head 26, it does so by travelling downward along the front wall of the mixing chamber 26a. It is necessary that the aggregate travels in this position to allow the aggregate to gain maximum contact with the binder spray. The binder spray is a fan-shaped spray from a single spray jet. However, not all of the spray mist is captured by the aggregate, and the remainder of the spray mist is blown out along the same front wall. Figure 2 shows the path of the aggregate in the mixing chamber 26a, indicated by broken parallel lines, and how it exits at the front side of the chamber 26a. Figure 2 also shows the binder mist globules, shown as dots, blowing to the front, while the main mass of air expands in all directions as it exits, shown as short arrows.

After it exits the mixing chamber 26a, the aggregate, having greater mass than the spray mist globules, will travel in a straight line to the ground, while the mist globules will change direction as a result of the decompressing air mass. This separation results in overspray, wherein mist globules get blown away from the work and are liable to cause damage elsewhere. It also affects the quality of the mixture, as the globules blown away result in a leaner mix.

A phenomenon known as "blobbing" can occur when the aggregate contains tiny particles of dust in suspension, (as a result of incomplete washing of the aggregate), and those wet dust particles become attached to particles of binder in the chamber, causing a blob to form (through anionic and cationic attraction). This blob can obviously affect the quality of the finished product. Another type of dispensing head includes a "sprayring" apparatus. A sprayring is a circular chamber with usually about eight small holes drilled to point inwards at an angle down, which when pressurised with binder will spray inwards from all sides. As the aggregate passes through the spray mist, it is coated. Figure 3 illustrates a dispensing head including a typical sprayring apparatus. In operation, referring to Figure 3, aggregate 9 is conveyed pneumatically through a rubber hose 6 and a distributor 5, and is sprayed as it passes through a mixing chamber 8, by a spray of binder from a sprayring 3. As the airflow exits the chamber, it expands, allowing the smaller particles of binder from the spray ring to separate from the stream of aggregate, which will continue in a straight line to the road surface. These globules of binder are liable to drift, thereby potentially causing damage to property or the like.

The sprayring apparatus has the drawback that the spray holes are very small; larger holes would provide too much binder for the capacity of the machine, and would overwhelm the operator. As a result, sprayring apparatus are very susceptible to blockage, and typically a number of the holes will become blocked before an operator can see that there is a problem. At this stage, the operator may well have laid a substantial volume of material which will be too lean, i.e., not enough binder present. Because the material begins to disperse or spread immediately it leaves the mixing chamber, a poorly defined patch can result with irregular edges, and there may be difficulty in carrying out small repairs in a neat manner. In view of the above, there is a need to provide an improved dispensing mechanism for road repar vehicles. Summary

According to the present disclosure there is provided a dispensing head as detailed in claim 1 . Also provided is a boom for a road repair vehicle according to claim 26. Advantageous features are recited in the dependent claims. The present disclosure involves providing a shroud to create an "air curtain" at an exit point of the dispensing head. The air curtain directs air at an angle towards the sprayed material, forcing or directing mist globules back into the mixture, and helping to condense the stream of mixture so it can be focused more accurately. The airflow may be obtained by drawing air from above the mixing chamber and ducting that air to feed into the "air curtain" shroud. Pressure may be balanced by restricting the airflow through the mixing chamber.

Brief Description Of The Drawings

The present application will now be described with reference to the accompanying drawings in which:

Figure 1 illustrates a detailed side view of a dispensing head of a boom for a road repair vehicle;

Figure 2 shows the path of material in the boom of Figure 1 and how it exits at the front side of a mixing chamber;

Figure 3 illustrates another dispensing head including a typical sprayring apparatus;

Figure 4 illustrates a detailed top perspective view of a dispensing head of a boom for a road repair vehicle, including a shroud used to direct air and form an air curtain, according to an embodiment of the present disclosure; Figure 5 illustrates a detailed bottom perspective view of the dispensing head of Figure 4, including a shroud used to direct air and form an air curtain, according to an embodiment of the present disclosure;

Figure 6 illustrates a detailed side view of the dispensing head of Figure 4, according to an embodiment of the present disclosure;

Figure 7 illustrates a detailed front view of the dispensing head of Figure 4, according to an embodiment of the present disclosure;

Figure 8 illustrates a detailed side view of the dispensing head of Figure 4, according to an embodiment of the present disclosure;

Figure 9 illustrates a detailed top view of the dispensing head of Figure 4, according to an embodiment of the present disclosure;

Figure 10 illustrates a detailed perspective view of the dispensing head of Figure 4, according to an embodiment of the present disclosure; and

Figure 1 1 illustrates a dispensing head for a boom of a road repair vehicle, according to another embodiment of the present disclosure.

Detailed Description Of The Drawings

The present disclosure provides a dispensing head for a boom of a road repair vehicle for dispensing a road repair material. The boom may be configured for delivering the material to the dispensing head from a supply of said material on the vehicle. The dispensing head defines a mixing chamber for mixing aggregate and binder. The dispensing head comprises a shroud mounted on at least a portion of the mixing chamber adjacent to a dispensing end of the mixing chamber to define an airflow path for creating an air curtain extending from at least a portion of a periphery of the dispensing end of the mixing chamber. The present disclosure involves creating an air curtain on one or more sides of the dispensing head. The air curtain directs air at an angle towards the sprayed material, forcing or directing the mist globules back into the mixture, and condensing the mixture stream. Figures 4 and 5 illustrate detailed top and bottom perspective views of a dispensing head 100 of a boom 400 for a road repair vehicle. The dispensing head 100 includes a shroud 150 used to direct air and form an air curtain, according to an embodiment of the present disclosure. Referring to Figures 4 and 5, the shroud 150 may be provided on at least three sides, for example front and both lateral sides, of the dispensing head 100. As illustrated in Figure 5 and explained above, the dispensing head 100 defines a mixing chamber 105 for mixing the aggregate and the binder before exiting the dispensing end of the mixing chamber 105. The mixing chamber 105 may have a rectangular prism shape defining four sides of the mixing chamber 105. A rear of the mixing chamber 105 may already have enough air from the air provided into the mixing chamber 105 to contain the globules. The airflow may be obtained by drawing air from above the mixing chamber 105 and ducting that air to feed into the shroud 150. Pressure may be balanced by restricting the airflow through the mixing chamber 105.

Figures 6 to 10 illustrate other views of the dispensing head of Figure 4, according to embodiments of the present disclosure. Referring to the side view of Figure 6, a heavy dotted line 170 shows a path along which aggregate travels in the mixing chamber 105. The aggregate may be supplied through the boom in a substantially horizontal direction to the dispensing head 100 where it changes direction to a substantially vertical direction as it passes through the mixing chamber 105. Optionally, a wear plate 102 may be provided at a front wall 100a of the mixing chamber 105 for protecting the front wall 100a. The aggregate may hug the wear plate 102 as it changes direction from horizontal to vertical. Referring to Figure 6, a restrictor plate 1 10 may be provided in the mixing chamber 105. The restrictor plate 1 10 may extend from a rear of the mixing chamber 105 to a position toward a front of the mixing chamber 105. The restrictor plate 1 10 is positioned to force air fed to the dispensing head 100 to the front of the mixing chamber 105, as illustrated by the dotted line 170. Referring to Figure 6, the restrictor plate 1 10 may be configured to be hinged about the rear of the mixing chamber 105 so as to adjust the width of the width of the spray as it is applied. Material exits the mixing chamber 105 at a dispensing end 106, which will be understood to be an open end of the mixing chamber 105. The shroud 150 may be provided on an outer surface of the mixing chamber 105. The shroud 150 may be provided on one or more sides of the mixing chamber 105. The shroud 150 may be configured to define an airflow path along the outer surface of the mixing chamber 105. In this regard, the shroud 150 may be a curtain, cover, screen, or any suitable component for providing an airflow path along the outer surface of the mixing chamber 105. As the aggregate exits the mixing chamber 105 defined by the dispensing head 100, it does so by travelling downward along a front wall 101 of the mixing chamber 105. It is important that the aggregate travels along this route to allow the aggregate to gain maximum contact with a binder spray 161 provided from a rear of the mixing chamber 105. The binder spray 161 may comprise a fan- shaped spray from a single spray jet. However, not all of the spray mist is captured by the aggregate, and the remainder of the spray mist is blown out along the same front wall 101 .

Referring to Figure 6, the shroud 150 may comprise a substantially planar portion 151 . The shroud 150 may be configured to be disposed a distance from the outer sidewalls of the mixing chamber 105 so as to define an airflow path 155 between the mixing chamber 105 and the shroud 150. Referring to Figure 6, 7 or 8, the shroud 150 is configured in relation to the mixing chamber 105 so as to define an airflow exit point 154 between a base of the shroud 150 and a base of the mixing chamber 105. In this manner, air provided along the airflow path 155 exits the shroud 150 and extends below at least a portion of a periphery of the dispensing end 106 of the mixing chamber 105. The periphery of the dispensing end 106 of the mixing chamber 105 may be understood to be a bottom edge of the mixing chamber 105. In this manner, an air curtain is provided below the dispensing head 100. Referring to Figure 6, the shroud 150 may be configured to provide a funnel in the airflow path 155 at the airflow exit point 154, so as to compress the airflow slightly at the airflow exit point 154. To this end, the shroud 150 may be configured to be inclined at an angle to the outer sidewalls of the mixing chamber 105. The airflow path 155 provides for an air curtain at the airflow exit point 154. The air curtain directs air at an angle towards the sprayed material, forcing or directing the mist globules back into the mixture. Referring to Figure 6, the shroud 150 may protrude beyond a bottom of the dispensing end 106 of the mixing chamber 105. The shroud 150 may define a bottom lip 153 at a distal end thereof. The bottom lip 153 may protrude beyond a bottom of the dispensing end 106 of the mixing chamber 105. The distal end of the shroud 150 will be understood to be the end of the shroud 150 corresponding to the dispensing end 106 of the mixing chamber 105. The bottom lip 153 may be provided at a distal end of the substantially planar portion 151 . The bottom lip 153 may constitute an end section of the substantially planar portion 151 . In one embodiment, the bottom lip 153 may be co-planar with the substantially planar portion 151 . That is, the shroud 150 may be substantially planar throughout and protrude beyond a bottom of the dispensing end 106 of the mixing chamber 105. However, in another embodiment, the bottom lip 153 may be configured to be disposed at an angle to the substantially planar portion 151 . The bottom lip 153 of the shroud 150 may be angled inwards towards the mixing chamber 105 so as to direct airflow between the shroud 150 and the mixing chamber 105 into the middle of the material exiting the mixing chamber 105. The bottom lip 153 may be integrally formed with the substantially planar portion 151 . The bottom lip 153 itself may have a planar shape, or in other embodiments may have a curved shape. In another embodiment, the angle at which the bottom lip 153 is inclined can be varied so as to adjust the angle of inclination of the air curtain. Adjusting the angle of inclination of the air curtain has the effect of controlling the width of the spray as it is applied. For example, the bottom lip 153 may be configured to be hinged with the substantially planar portion 151 so as to rotate about the hinged point. The angle of rotation of the bottom lip 153 may be controlled by an operator of the vehicle using any suitable control mechanism as would be understood by one skilled in the art. Figure 6 also shows a duct 175 used to convey air into the airflow path 155. The dispensing head may comprise at least one duct 175 for conveying air into the airflow path 155. The at least one duct 175 is disposed to correspond to the position of the shroud 150. It will be understood that the at least one least one duct 175 will be configured to be fluid communication with the airflow path 155 defined by the shroud 150. Referring to Figure 9, the at least one duct 175 may comprise two ducts 175, one on each lateral side, for balancing the airflow into the airflow path. An airflow balancing mechanism may be fitted to balance the airflow between the mixing chamber 105 and the shroud 150. The perspective view of Figure 4 also illustrates two ducts 175, one on each lateral side of the dispensing head 100, for balancing the airflow into the airflow path.

Figure 7 illustrates a detailed front view of the dispensing head 100 of Figures 4 and 5, according to an embodiment of the present disclosure. Referring to Figure 7, the shroud 150 is provided on both sides of the mixing chamber 105. Figure 8 is another side view of the dispensing head 100 of Figures 4 and 5, according to an embodiment of the present disclosure. Figure 9 is a detailed plan view of the dispensing head 100, according to an embodiment of the present disclosure. Referring to Figure 9, the binder spray 161 is illustrated. As mentioned previously, the binder spray 161 may comprise a fan-shaped spray. The binder spray 161 may emanate from a binder spray jet 162 disposed at the rear of the dispensing head 100. The shroud 150 may be provided on one or more sides of the dispensing head 100. In the embodiment illustrated in Figure 9, the shroud 150 is provided on the front 100a and lateral sides 100b and 100c of the mixing chamber 105. The aggregate is mixed with the binder spray 161 in a mixing area 105a of the mixing chamber 105. The material is then expelled from the dispensing head 100 at the portion of the dispensing end 106 corresponding to the mixing area 105a. Figure 1 1 illustrates a dispensing head 200 for a boom 400 of a road repair vehicle, according to another embodiment of the present disclosure. Referring to Figure 1 1 , the dispensing head 200 comprises a distributor 205 and a mixing chamber 208. In operation, aggregate 209 may be conveyed pneumatically through a hose 206 and the distributor 205. The aggregate may be sprayed as it passes through the mixing chamber 208, by a spray of binder from a sprayring 203.

As the airflow exits the mixing chamber 208, it expands, allowing the smaller particles of binder from the sprayring 203 to separate from the stream of aggregate, which will continue in a straight line to the road surface. The globules of binder are liable to drift, thereby potentially causing damage to property. By fitting at least one of a first restrictor 201 and a second restrictor 202, and creating a number of small apertures in the distributor 205, air will exit the apertures. The first restrictor 201 may be positioned at an entrance to the distributor 205. The second restrictor 202 may be positioned in the distributor 205 at an entrance to the mixing chamber 208. A shroud 204 is provided on an outer surface of at least a portion of the mixing chamber 208 and the distributor 205. This airflow can be contained by the shroud 204 over the distributor 205, so that the air which has exited can be directed inwards at an angle from one or more sides. This enables finer elements of the binder to be directed and contained back into the mixture, thereby lowering the risk of drift, and adding to the quality of the mixture by forcing the fine mist of binder back into the aggregate stream. It also provides better control of the mixture stream by containing and condensing it, allowing more accurate placement, with less scattered material in the vicinity of the repair work. The second restrictor 202 may be configured to provide enough restriction to balance the airflow within the distributor 202 and the shroud 204. The first restrictor 201 may be configured to provide enough restriction to prevent the aggregate 209 from exiting the apertures, potentially blocking them. The present disclosure also provides a boom for a road repair vehicle for dispensing a road repair material, the boom comprising the dispensing head as described above, the dispensing head being provided at the free end of the boom. Referring to Figures 4 and 1 1 , the boom 400 may be configured to direct said material to the dispensing heads 100 and 200. The boom 400 may comprise at least one hose 206 extending along the boom 400 for delivering said material to the dispensing head 100 or 200 from a supply of said material on the vehicle. Referring to Figure 4, the boom 400 may also comprise an airflow supply. Airflow may be drawn from the boom 400 and ducted into the shroud 150.

The words comprises/comprising when used in this specification are to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.