WO1999066132A1

WO1999066132A1 - Road surface dressing machine and control apparatus therefor

Info

Publication number: WO1999066132A1
Application number: PCT/AU1999/000474
Authority: WO
Inventors: James Hector Dunlop
Original assignee: Jetpatcher Australia Pty. Ltd.
Priority date: 1998-06-15
Filing date: 1999-06-15
Publication date: 1999-12-23
Also published as: AUPP411898A0

Abstract

There is provided control apparatus for a system of the type comprising a first conveying apparatus (11) for conveying bulk material, and a second conveying apparatus (13) located downstream of said first conveying apparatus (11) for continuing conveying of the bulk material; said control apparatus comprising sensing means for measuring the load applied to said second conveying apparatus (13) by the conveying of the bulk material, and control means associated with said sensing apparatus and adapted for the control of the feed rate of said first conveying apparatus (11) for the maintenance of a substantially constant load on said second conveying apparatus (13). The first and second conveying apparatus (11 and 13) may suitably be a first longitudinal conveyor (11) on a mobile road surface dressing machine (23) and arranged to receive aggregate from a hopper (12) and to deliver same to a second conveyor (15) extending laterally and disposed in a spreader box (13) to deliver aggregate to the road through a delivery slot (14) extending along the bottom of the box (13).

Description

"ROAD SURFACE DRESSING MACHINE AND CONTROL APPARATUS THEREFOR"

TECHNICAL FIELD OF THE INVENTION

This invention relates to road surface dressing machines and control apparatus therefor, and it has particular but not exclusive application to the control of conveyor systems for bulk granular materials such as aggregate or gravel to be distributed as road surface dressing. For illustrative purposes reference will be made principally to such application.

BACKGROUND ART

The invention arises principally from the desire to increase the range of road surface dressing functions available with road repair machines of the type currently used most successfully, such as that disclosed in Australian patent specification No. 685975, and it is to be understood that the disclosures of that specification are deemed to be part of the disclosure herein to the extent that the same may be pertinent and/or desirable.

It is an object of the invention to provide a conveyor system and control apparatus therefor which will enable wider usages of existing road repair machines as aforementioned. Another object of the invention is to provide a novel conveyor system and control apparatus therefor, as abovedescribed, which will permit road-width spreading of materials without encountering difficulties of the types usually associated with wide distribution systems . The invention aims to provide apparatus as abovedescribed which will prove reliable and efficient in use, while other objects and advantages of the invention will hereinafter become apparent.

DISCLOSURE OF THE INVENTION

With the foregoing and other objects in view, the invention in one aspect resides broadly in control apparatus for a system of the type comprising:- a first conveying apparatus for conveying bulk material, and a second conveying apparatus located downstream of said first conveying apparatus for continuing conveying of the bulk material ; said control apparatus comprising: - sensing means for measuring the load applied to said second conveying apparatus by the conveying of the bulk material , and control means associated with said sensing apparatus and adapted for the control of the feed rate of said first conveying apparatus for the maintenance of a substantially constant load on said second conveying apparatus.

Suitably, the second conveying apparatus is a screw conveyor, whereby the load applied by the conveying of the bulk material is substantially dependent on the depth to which the screw conveyor is immersed in the bulk material. Of course, if desired, the second conveying apparatus may be a belt conveyor, a feeder, or a chute.

The first conveying apparatus may also be of any type, such as a screw conveyor or a chute. It is preferred however that it be a belt conveyor whereby the feed rate may be varied conveniently by varying the speed of the first motor driving the first conveying apparatus .

The screw conveyor may be driven by any suitable screw conveyor drive means, such as an electric motor, in which case, the current drawn by the electric motor may be measured by the sensing means and used to determine the load applied by conveying the bulk material. Preferably, however, the screw conveyor drive means is in the form of a hydraulic motor, whereby the oil pressure applied to the motor by conveying of the bulk material (back pressure) may be measured by the sensing means as a measure of the loading applied.

The control means may be of any desired form. If the screw conveyor drive means and the first motor are electric, the control means may be an electric or electronic speed controller or a variable-ratio mechanical drive. In a preferred embodiment, the screw conveyor drive means and the first motor are hydraulic motors, and the control means is a hydraulic valve capable of varying the oil flow through the first motor and thus altering the feed rate of the first conveying apparatus, the flow variation being controlled by the back pressure from the screw conveyor drive motor. Where the first motor is driven by a substantially-constant flow source, the hydraulic valve suitably is in the form of a bypass valve which diverts oil flow away from the first motor, but if desired, the hydraulic valve may take the form of a flow-control valve in series with the first motor. In both cases, the sensing means and the control means may be combined within the same hydraulic valve.

According to another aspect of the invention, there is provided a mobile road surface dressing machine having a first longitudinal conveyor arranged to receive bulk material in the form of aggregate from an aggregate hopper and to deliver same to a second conveyor extending laterally and disposed in a spreader box to deliver aggregate to the road through a delivery slot in the box transverse to the line of motion of the machine.

The aggregate spreader box may be selectively adjusted to vary the delivery widths, and means may be provided for varying the position of the box relative to its length so that it may have either operative extremity located laterally outside the line of the vehicle edge portions.

The second conveyor is preferably a screw-conveyor or auger having two flights oppositely directed and discharging through a slot parallel to its axis of rotation, the effective width of the slot being adjustable by a movable parallel control bar, while discharge of material past the slot is augmented by a rotatable roller drivably mounted adjacent thereto. Other features of the invention will become clearer from the following descriptions of preferred embodiments, while the sensing apparatus and control means associated therewith may suitably be along the lines described above in relation to the first aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which show one practical form of the invention and wherein:- Fig. 1 is an overall perspective pictorial view of a machine according to the invention incorporated in a road repair vehicle;

Fig. 2 is a pictorial view showing the spreader box and auger as well as the feed hopper, eductor and adjacent components ;

Fig. 3 show pictorially the aggregate delivery mechanisms including the control flaps, actuator, levers and linkages; Fig. 4 is a pictorial view showing the drive arrangements for the spreader box and the actuator to move it from side to side;

Fig. 5 illustrates schematically in plan view the gravel control system and distribution apparatus according to the invention;

Fig. 6 shows diagrammatically the relationship of the delivery components at the discharge end of the first conveyor and at the spreader box thereunder;

Figs. 7 and 8 show in more detail diagrammatically in side view the operation of the delivery roller beneath the spreader box;

Fig. 9 illustrates diagrammatically the venturi system of the machine; and

Fig. 10 is a schematic diagram of an hydraulic control system for the aggregate or gravel distribution apparatus as shown broadly in Fig. 5.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to Figure 5, the gravel-distribution assembly 10, according to the first aspect of the invention and shown schematically, comprises a belt conveyor 11 feeding gravel from the base of a storage hopper 12 into the centre of a transverse gravel distribution box 13 which has a narrow slot 14 along its base. In the upper part of the distribution box 13 is a two-way screw conveyor 15. The belt conveyor 11 is driven by a first hydraulic motor 16 and the screw conveyor 15 is driven by a second hydraulic motor 17. Referring now to Figure 10, the first hydraulic motor 16 and the second hydraulic motor 17 are driven from constant-flow oil sources 18 and 20 such as fixed-flow pumps or flow-control valves. A pilot-operated bypass valve 21 is fitted across the flow path through the first hydraulic motor 16. The bypass valve 21 is spring-loaded into the closed position, and the pilot- pressure port is connected to the pressure port on the second hydraulic motor 17. The hydraulic motors 16 and 17 are positive- displacement types, where the output speed is directly related to oil flow rate and the output torque is directly related to applied oil pressure.

In use, the first and second hydraulic motors 16 and 17 are energised to drive the belt conveyor 11 and the screw conveyor 15 to feed gravel into the distribution box 13 and to distribute it into a uniform layer within the latter. At this stage the bypass valve 21 is held closed by an internal spring 22, and the belt conveyor 11 operates at its maximum feed rate. As the box 13 fills up, the load applied to the second hydraulic motor by the screw conveyor increases, and the pressure at the pressure port on the second hydraulic motor 17 rises. When a preset pressure level is reached, the pilot pressure applied to the bypass valve 21 overcomes the internal spring 22 and begins to open the valve 21, bypassing hydraulic fluid flow away from the first hydraulic motor 16, reducing its operating speed and thus reducing the flow rate of the belt conveyor 11 until an equilibrium level of gravel is reached within the distribution box 13. If the latter begins to empty, the pilot pressure applied to the bypass valve 21 decreases, and this begins to close, reducing the oil flow bypassing the first hydraulic motor 16. This allows the first hydraulic motor 16 to speed up, maintaining the gravel at the desired level around the screw conveyor 15.

The aforementioned apparatus including the transverse distribution box 13 (hereinafter called "the spreader box") may be incorporated very easily into a road repair machine of the type described and illustrated in the aforementioned Australian patent specification No. 685975, as will be apparent from the following descriptions in relation to Figs. 1 to 9 which show a road repair vehicle 23 for repairing roads and other asphalt surfaces, wherein high pressure air, liquid emulsion and solid aggregate such as gravel can be discharged separated or in a mixture through a single nozzle 24 on a swinging arm 25, and wherein a venturi valve (indicated generally at 26 in Fig. 9) is used to draw the solid aggregate into the outlet hose 27 to the nozzle 24 from an eductor 28 having an inlet 29 for the aggregate. The eductor 28 is comprised of the inlet 29, an air jet 30 and a constriction tube 31 immediately downstream of the jet 30.

The road repair vehicle 23 includes a hydraulic pump and oil tank; an air compressor; an emulsion tank 32, an uppermost aggregate hopper 12, a feed conveyor 11 powered by the hydraulic motor 16. As usual a large aggregate and air hose and a smaller emulsion hose are joined at the nozzle 24 which is preferably supported by the jointed swinging arm 25. As shown in Fig. 5 in particular there is also a sand hopper 33 from which sand can be delivered when desired a the downstream end 34 of the conveyor 11 which in this case is a belt conveyor disposed medially of the machine and extending longitudinally relative to the direction of motion. There is also shown the transverse spreader box 13 containing the two-way screw conveyor or auger 15, and in this case a selector chute 35 is provided so that all delivery can be made to the eductor 28 - passing over the auger assembly - when manual road repair service are required. On the other hand, the selector chute can when desired be disposed to direct the materials to above the auger 15 in the spreader box 13.

The additional components as illustrated enable the machine to be used for road sealing and the like when manually controlled road "patching" is not being followed, the relative positions of the components being apparent from Fig. 6. When the eductor 28 and selector chute 35 are not begin used, the longitudinal belt conveyor 11 can deliver medially or to either side of middle in relation to the two-way screw conveyor 15 and will be moved along the spreader box 13 and towards each end thereof so that uniform distribution can be achieved through the narrow slot 14 along the base of the box 13. As will be seen from Fig. 6, the slot 14 is defined between a rear rubber sealing flap 36 and an adjustable front control bar 37 and linkage assembly 38, while beneath the slot 14 there is a rotatable roller 39 having its uppermost periphery guidedly dispelling the aggregate rearwardly in conjunction with a rearwardly disposed control bar 40, these components being shown in more detail in Figs . 7 and 8 which also show the location of the spray nozzles 41 on a transversely extending emulsion manifold 42. Fig. 7 shows the components when stationary, the front control bar 37 being downmost by virtue of its mounting rods 43 being extended from their guide sleeves 44 when the linkage assembly 38 is down when the link arms 45 thereof are held by the lever arms 46 when the latter are in the illustrated disposition. On the other hand, Fig. 8 shows the arrangements at the slot 14 when the auger or two-way screw conveyor 15 is being rotated and the bottom roller 39 is being rotated, while the front control bar 37 is raised to open the slot by means of the linkage assembly 38. The aggregate control bar 40 is rotatably adjustable as indicated by dotted outline in Fig. 8 and it has a rear lip 45a to operate with the roller 39 to define the "thickness" of aggregate flowing therebetween, while a top lip 46a acts to prevent overflow. It will be clear from Fig. 8 that the rates of flow and speeds of rotation can be used to ensure delivery to the road of a predetermined thickness of aggregate to be placed on the emulsion delivered ahead thereof from the jets at the emulsion manifold 42. The front bar or gate

37 will be seen to be movably adjustable in such manner as to achieve major control of aggregate at the four components of rear flap 36, front bar 37, rotatable roller 39 and control bar 40. Figs. 2 and 4 show the spreader box 13 in more detail from the same end thereof but at rear and front sides respectively, while Fig. 3 shows the adjustment means for the linkage assembly

38 in detail at the other end of the spreader box 13. As shown in Fig. 4 the machine has a frame structure 47 directly in rear of the rear truck wheel 48 and mudguard 49 to permit adjustable sliding of the spreader box 13 lengthwise to extend to the desired vehicle side limit, and for this purpose the box 13 has slide bars 50 and hydraulic actuator rod 51 to move the auger hopper or box side to side. Fig. 4 also shows the auger drive motor 17 with chain and sprockets drive 52 to rotate the journalled shaft 53 of the auger. Likewise, mounted on the box 13 is a motor 54 with chain and sprockets drive 55 to the journalled shaft 56 of the rotatable roller 39 beneath the delivery slot 14. The emulsion manifold 42 is shown with its nozzles and also an emulsion feed line 57. This view also shows more detail of the roller 39, as well as a front adjustment screw mechanism 58 to adjust the aggregate control bar 40 which is pivotable about its longitudinal axis by raising or lowering the screw handle 59 to transmit pivotable movement through a pivot block 60 at the lower end.

While Figs. 7 and 8 illustrate diagrammatically the adjustment of the front aggregate gate 37, more detail will be apparent from Fig. 3 which shows not only the front side of the spreader box 13 as well as the roller 39 and front control bar 37 but also the rods 43 and guide sleeves 44 and links and levers to raise or lower the bar 37 by virtue of an hydraulic actuator 61 pivotally turning a main control shaft 62 connected through the parallel linkage to the secondary shaft 63 which is divided into sections as shown, while the gate or bar 37 is itself divided into separate sections . These arrangements permit the unhooking of linkages when desired to deactivate one or more gate sections. Thus the spreader box 13 could be designed for a width of 2400mm, for example, but have a variety of sealing widths available if so desired.

Finally, Fig. 1 shows the overall pictorial view of the total machine ready for whatever operation may be selected, and it will be noted that the spreader box 13 is safely housed directly behind the rear wheels 48 and ahead of the eductor 28 which may be rendered "inoperative" by means of the selector chute 35 when sealing functions are to be utilised. Components at the rear end are more clearly seen in Fig. 2, it being noted that if the eductor 28 is to be used for manual road repairing, the selector chute 35 will be so disposed as to ensure that materials pass from the conveyor 11 directly to the eductor 28. If desired, the selector chute 35 may be replaced by two removable chute assemblies adapted to be fitted according to whether patching or sealing functions are required. For patching, a simple direct chute could be employed, whereas for sealing it may be preferred to have a swinging chute adapted to convey materials from the belt conveyor to a desired distance, as selected, at either side of the middle of the two-part auger. Then again, it might be preferred to remove part of each flight of the auger at its middle where an auger-type action is less necessary that at more outward locations.

Various other modifications can be made, as will be readily apparent to persons skilled in the art, without departing from the scope and ambit of the invention, as defined by the appended claims .

Claims

1. Control apparatus for a system of the type comprising :- a first conveying apparatus for conveying bulk material, and a second conveying apparatus located downstream of said first conveying apparatus for continuing conveying of the bulk material; said control apparatus comprising: - sensing means for measuring the load applied to said second conveying apparatus by the conveying of the bulk material, and control means associated with said sensing apparatus and adapted for the control of the feed rate of said first conveying apparatus for the maintenance of a substantially constant load on said second conveying apparatus .

2. Control apparatus according to Claim 1, wherein the second conveying apparatus is a screw conveyor, whereby the load applied by the conveying of the bulk material is substantially dependent on the depth to which the screw conveyor is immersed in the bulk material .

3. Control apparatus according either of to Claims 1 and 2, wherein the first conveying apparatus is a belt conveyor whereby the feed rate may be varied conveniently by varying the speed of the first motor driving the first conveying apparatus.

4. Control apparatus according to Claim 2, wherein the screw conveyor is driven by conveyor drive means including an electric motor, the current drawn by the electric motor being measured by the sensing means and used to determine the load applied by conveying the bulk material .

5. Control apparatus according to Claim 2, wherein the screw conveyor drive means is in the form of a hydraulic motor, whereby the oil pressure applied to the motor by conveying of the bulk material (back pressure) may be measured by the sensing means as a measure of the loading applied.

6. Control apparatus according to Claim 2, wherein the screw conveyor drive means and the first motor are hydraulic motors, and the control means is a hydraulic valve capable of varying the oil flow through the first motor and thus altering the feed rate of the first conveying apparatus, the flow variation being controlled by the back pressure from the screw conveyor drive motor .

7. Control apparatus according to Claim 6, wherein the first motor is driven by a substantially-constant flow source, the hydraulic valve suitably being in the form of a bypass valve which diverts oil flow away from the first motor.

8. Control apparatus according to Claim 6, wherein the hydraulic valve is a flow-control valve in series with the first motor, the sensing means and the control means being combined within the same hydraulic valve.

9. A mobile road surface dressing machine having a first longitudinal conveyor arranged to receive bulk material in the form of aggregate from an aggregate hopper and to deliver same to a second conveyor extending laterally and disposed in a spreader box to deliver aggregate to the road through a delivery slot in the box transverse to the line of motion of the machine.

10. A mobile road surface dressing machine according to Claim 9, wherein the aggregate spreader box may be selectively adjusted to vary the delivery widths , means being provided for varying the position of the box relative to its length so that it may have either operative extremity located laterally outside the line of the vehicle edge portions.

11. A mobile road surface dressing machine according to Claim 9 , wherein the second conveyor is a screw-conveyor or auger having two flights oppositely directed and discharging through a slot parallel to its axis of rotation, the effective width of the slot being adjustable by a movable parallel control bar, while discharge of material past the slot is augmented by a rotatable roller drivably mounted adjacent thereto.

12. A mobile road surface dressing machine substantially as hereinbefore described with reference to the accompanying drawings .