WO2000028154A1

WO2000028154A1 - Drop mass soil compaction apparatus

Info

Publication number: WO2000028154A1
Application number: PCT/IB1999/001785
Authority: WO
Inventors: Eric Johnstone Cook; Christoffel Avril Mijburgh
Original assignee: Compaction Technology (Soil) Limited
Priority date: 1998-11-09
Filing date: 1999-11-08
Publication date: 2000-05-18
Also published as: AU6362099A

Abstract

The invention concerns a drop mass soil compaction apparatus (10) which can be used to compact relatively small areas of a soil surface. The apparatus includes a drop mass soil compactor (12) and a mounting arrangement (14) for mounting the compactor on a wheeled vehicle (16) such as a trailer or truck. The compactor (12) includes a foot pad (30) which can be located on the soil surface, a mass (34) and a control system for repeatedly raising the mass and dropping it onto the foot pad structure to compact the soil surface. The compactor (12) can be moved between a transportation condition in which it is located in a prone orientation on the vehicle and an operational condition in which the compactor is located upright adjacent the vehicle. In the operational condition, the foot pad (30) can be lowered into contact with the soil surface or raised clear of that surface. In the former position, impacts of the mass (34) on the foot pad (30) are transmitted to the soil surface. The apparatus also includes a drive which is operable to move the compactor laterally relative to the vehicle.

Description

DROP MASS SOIL COMPACTION APPARATUS

BACKGROUND TO THE INVENTION

THIS invention relates to a drop mass soil compaction apparatus.

There are numerous applications where it is necessary to compact a relatively small area of soil but where the use of conventional soil compaction machinery, typically employing rollers of one type or another, is inappropriate. One important example is in the compaction of soil adjacent bridge abutments, where limited space makes it impossible to compact with conventional large rollers or other machines. Another example is in the compaction of soil in relatively narrow trenches for pipes, strip foundations or the like. Yet another example is in road maintenance where local failure of a section of a road may have taken place in a relatively small area.

Although small vibratory rollers and impactors are available and are widely used in such applications, the level of soil compaction which can be achieved with such devices is limited. The result is often that undue settlement and or structural failure can take place after a relatively short period of time. SUMMARY OF THE INVENTION

According to the invention there is provided a drop mass soil compaction apparatus comprising:

a drop mass soil compactor,

means for mounting the drop mass soil compactor on a wheeled vehicle, the mounting means being operable to move the compactor relative to a vehicle on which it is mounted between a transportation condition in which the compactor is located at a prone orientation on the vehicle and an operational condition in which the compactor is located at an upright orientation adjacent the vehicle, and

positioning means operable to move the compactor laterally relative to the vehicle when the compactor is in the operational condition,

the compactor comprising a foot pad, means operable when the compactor is in the operational condition to move the foot pad between a compacting position contacting a soil surface which is to be compacted and a non- compacting position elevated above the soil surface, a mass and mass control means for repeatedly raising the mass and dropping it to transmit an impact blow to the foot pad when the foot pad is in the compacting position, thereby to compact the soil surface

In the preferred embodiment, the mounting means is operable to move the compactor to an operational condition in which the compactor is located at an upright orientation adjacent a rear end of the vehicle and the positioning means is operable to move the compactor, in its operational condition, from side to side relative to the end of the vehicle. The mounting means may serve to mount the compactor on the chassis of a wheeled trailer or truck. Alternatively it may include a frame and means mounting the compactor to the frame, the frame being mountable on the chassis of a wheeled trailer or truck. Typically, the positioning means comprises a traverse beam structure on which the compactor is supported and drive means, possibly a chain and sprocket drive, for driving the compactor along the traverse beam structure.

Other features of the invention are described below and set forth in the appended claims.

RRTEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a diagrammatic side view of a drop mass soil compaction apparatus, according to this invention, mounted on a trailer and in an inoperative, transportation position;

Figure 2 shows a diagrammatic plan view of the apparatus in the inoperative position;

Figure 3 shows a diagrammatic side view of the apparatus in an operative, soil compaction position with the foot pad raised;

Figure 4 shows a diagrammatic side view of the apparatus in the operative position with the foot pad lowered; Figure 5 shows a diagrammatic perspective view of the apparatus in the operative position;

Figure 6 shows a diagrammatic side view, corresponding to that of Figure 3, of a second embodiment of the invention;

Figure 7 shows a diagrammatic plan view, corresponding to that of Figure 2, of the second embodiment;

Figure 8 shows a diagrammatic end view of the second embodiment;

Figure 9 shows a diagrammatic perspective view of the second embodiment;

Figure 10 diagrammatically illustrates the relationship between the mass, shield and guide beams in the second embodiment; and

Figure 11 diagrammatically illustrates the ball joint suspension of the foot pad in the second embodiment.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Figures 1 to 5 show a drop mass soil compaction apparatus 10 according to a first embodiment of this invention. The apparatus 10 includes a drop mass soil compactor, indicated generally with the numeral 12, and mounting means, indicated with the numeral 14, which mounts the compactor 12 to a wheeled vehicle.

The vehicle in this case is a trailer 16 having a chassis 18 with a hitch 20 at its front end enabling it to be hitched to a towing vehicle such as a truck or tractor.

The drop mass soil compactor 10 is now described with reference to its operative position, as shown in Figures 3 to 5. It includes an open ended box structure 22 and a pair of channel-section posts 24 which extend vertically through the box structure and which are connected to one another at their upper ends by horizontal beams 26. At their lower ends, the posts 24 carry a foot pad structure 28 which includes a curved foot pad 30 suspended from a curved support block 32 to which the posts 24 are connected. The suspension of the foot pad 30 allows for limited free pivotal movement of the foot pad relative to the block 32.

The compactor 10 also includes a mass 34 which can slide up and down, through the box structure 22, guided by the posts 24. A vertical, double acting hydraulic cylinder 36 is connected between the beams 26 with its piston rod 38 connected to the upper end of the mass 34. A further, vertical double-acting hydraulic cylinder 40, seen for instance in Figure 4, acts between the box structure 22 and a bracket 42 carried by one of the beams 26.

The mounting means 14 of the apparatus 10 includes a traverse beam structure 44 which is pivoted to the rear end of the trailer. A pair of double- acting hydraulic cylinders 48 act between the chassis 18 of the trailer 16 and brackets 50 on the traverse beam structure 44. A connecting bracket 52 on the box structure 22 connects the compactor 12 to the traverse beam structure 44 and is slidable in a horizontal direction thereon. Although not visible in Figures 1 to 5, a lateral drive is provided to drive the box structure from side to side on the traverse beam structure. The lateral drive is in the form of an hydraulically driven sprocket on the box structure 22 and a chain on the traversebeam structure 44 with which the sprocket engages. Rotation of the sprocket drives the box structure and its associated components from left to right, or vice versa, depending on the direction of sprocket rotation.

The various hydraulic components described above are powered from an hydraulic power pack, indicated generally in Figure 4 with the reference numeral 54, mounted on the chassis 18 of the trailer 16. Manual controls for the various hydraulic circuits are also accessible on the trailer.

Figures 1 and 2 show the compactor 12 generally in an inoperative, transportation position and Figures 3 to 5 show the compactor in an operative, soil compaction position.

Commencing with the inoperative position, the operative position is attained by extending the hydraulic cylinders 48 to pivot the traverse beam structure 44 and, with it, the box structure 22 and associated components in a clockwise direction as viewed in Figures 1, 3 and 4. In the operative, soil compaction position, it will be seen that the compactor 12 is oriented vertically behind the rear end of the trailer 16.

To return the compactor 12 from the operative to the inoperative position, the cylinders 48 are contracted to pivot the support structure and, with it, the box structure 22 and associated components in an anticlockwise direction. In the inoperative position, it will be seen that the compactor 12 is located largely over the trailer for transportation purposes.

When compaction of an area of a soil surface is to be carried out, the trailer is parked with its rear end adjacent the relevant area and outriggers 56 on the chassis 18 are extended into contact with the ground. With reference to Figure 1 it will be appreciated that in the inoperative, transportation position, the outriggers are withdrawn. The compactor 12 is then moved from the inoperative to the operative position by extension of the cylinders 48. At this stage, the foot pad 30 is elevated above the soil surface as shown in Figure 3. The lateral drive is operated to move the compactor 12 sideways to locate the foot pad 30 directly over a specific zone of the soil surface area which is initially to be compacted. The foot pad is then brought into firm contact with the soil surface by extension of the cylinder 40 which lowers the posts 24 and foot pad structure 28 relative to the box structure 22, as shown in Figure 4.

A compacting force is now applied to soil surface by repetitively raising the mass 34 on the posts 24 and releasing it to fall onto and impact the foot pad structure 28, which transmits the impact energy to the soil. In each cycle, the mass is raised by contraction of the cylinder 36, which pulls the mass upwardly through the box structure 22. When the mass has reached a predetermined elevation, pressure is vented from the cylinder 36, allowing the mass to fall unimpeded to impact on the foot pad structure.

The elevation to which the mass is raised on each cycle will in practice be selected to generate a level of potential energy, to be converted to kinetic energy as the mass accelerates downwardly when dropped, commensurate with a desired impact force to be applied to the soil surface. The relevant parameters will in turn be determined with reference to the specific soil conditions at the compaction site. In practice, the repetitive raising and dropping of the mass 34 will be controlled automatically, the automatic control including sensors, possibly proximity switches or ultrasonic sensors (not illustrated) mounted at an appropriate elevation on the posts to sense the mass as it is raised to the selected elevation. Conveniently, the sensors are movable up and down the posts to control the elevation to which the mass is raised to a level to suit the soil conditions.

When a suitable level of compaction of the soil beneath the foot pad 30 has been attained, the raising and dropping of the mass is terminated. If necessary, the lateral drive is again actuated to move the compactor 12 sideways to a position over an adjacent zone of the soil surface which is to be compacted, whereafter the above procedure is repeated.

It will accordingly be understood that by moving the compactor sideways it is possible to compact a given lateral strip of the soil surface behind the trailer. Should it be necessary to compact another strip, adjacent to the first strip in the fore and aft direction of the trailer, the trailer can be reversed or moved forward as necessary to align the foot pad 30 with the new strip.

The drop mass compaction apparatus 10 is suitable for compacting smaller soil surface areas. One important application is in the compaction of soil adjacent bridge abutments where the described manoeuvrability enables the compactor to operate on a strip of soil close to the abutment. An added advantage here is that the compacting force is applied vertically to the soil without substantial lateral components of force which could affect the bridge abutment structure. Another important application is in remedial road maintenance work where the lateral manoeuvrability of the compactor enables a strip of soil to be compacted without moving the trailer. Other applications include compaction of soil in relatively narrow trenches. In such applications, a length of the trench can be compacted, by sideways movement of the compactor, without changing the position of the vehicle.

Although specific mention has been made of a vehicle in the form of a trailer, it is within the scope of the invention for the apparatus 10 to be used on a self-propelled vehicle such as a truck. Also, although mention has been made of the mounting and operation of the compactor at the rear of the vehicle, it will be understood that it is also within the scope of the invention for the apparatus to be mounted adjacent a side, and to operate alongside, the vehicle.

Whereas the embodiment described above may be largely manually controlled an automatic control system is also within the scope of the invention. Control may, for instance, be by way of a microprocessor-based PLC (programmable logic controller) which is pre-programmed to generate a specific compaction sequence. For instance, depending on the nature of the soil and the eventual compaction which is required, the PLC may be preprogrammed to generate a series of impact blows at relatively high energy, where the mass is dropped from a relatively high position and thereafter one or more series of blows at one or more relatively lower energy levels, where the mass is dropped from one or more relatively low positions. Alternatively the control imposed by the PLC may be such that relatively high energy blows are alternated with relatively low energy blows, and so on. In each case, the actual number of blows at each energy level will also be controlled by the PLC. Many other variations are possible within the scope of the invention. For instance, a flat foot pad could be used in place of the illustrated, curved foot pad 30. Also, any suitable drive other than the described sprocket and chain drive could be used to move the compactor from side to side on the traverse beam structure.

Figure 6 to 11 illustrate a second embodiment of the invention. Components in these Figures corresponding to components in the earlier Figures are designated with the same reference numerals.

One difference between the second embodiment of Figures 6 to 11 and the first embodiment of the earlier Figures is the fact that in the second embodiment, the mounting means 14 includes a frame 100 which can be mounted on the chassis of a wheeled trailer or on the chassis of a self- powered vehicle such as a truck. In this regard, the second embodiment is somewhat more versatile than the first embodiment, in that it can be mounted as desired on a range of different wheeled vehicles either of trailer or self- powered type.

The closed box structure 22 of the first embodiment is replaced in the second embodiment by a frame structure 102. A bracket structure 106 carried by the frame structure 102 is shaped to embrace and slide along the traverse beam structure 44. A sprocket and chain type drive is once again used to achieve the lateral drive. A portion of the chain, carried by the traverse beam structure, is indicated by the numeral 108 in Figure 7. The sprocket which engages the chain is concealed from view within the bracket structure 106.

As in the first embodiment, the upper end of the double-acting cylinder 40 acts on a bracket 42 carried by the posts 24. The cylinder section of the double-acting cylinder 40 is mounted to the frame structure 102 so that, as before, extension and retraction of the cylinder serves to lower and raise the posts 24 respectively. The lower ends of the posts are attached to a shield 110 and to the foot pad structure 28. It will accordingly be understood that the double-acting cylinder 40 can be retracted to lower the foot pad structure into contact with the ground from the raised position seen in Figures 6, 8 and 9. Lowering of the foot pad structure 28 also lowers the shield 110 correspondingly.

The shield 110 is primarily a protection measure. It encloses the zone in which impact takes place between the drop mass 34 and the foot pad structure and prevents access to this impact zone.

As in the first embodiment, a double-acting cylinder 36 is used to raise the drop mass 34 relative to the posts 24.

Figures 10 and 11 diagrammatically illustrate further features of the second embodiment. Referring firstly to Figure 10 it will be seen that the drop mass 34 has recesses 112 on either side and that the frame structure 102 has corresponding recesses 114. In combination, the recesses 112, 114 provide a cavity accommodating the posts 24 which, in use, guide the vertical movements of the mass. The recesses 114 also serve to guide vertical movement of the posts 24 between their raised and lowered positions.

Figure 11 diagrammatically illustrates the foot pad structure itself and shows that the drop mass 34 has a projection portion 116 on its underside which can pass through an opening 118 in a plate 120 carried by the lower ends of the posts 24. The foot pad structure 28 includes an anvil 122 carrying upwardly directed, tapered pins 124 which can slide through correspondingly tapered apertures 126 in the plate 120. Collars 127 are locked to the pins above the plate 120 to hold the anvil 122 captive relative to the plate. The underside of the anvil 122 carries a ball 128 which locates in universally rotatable manner in a socket 130 in a block 132 on the foot plate 30 itself. A flexible boot 134 surrounds the space between the anvil and the block 132 to prevent ingress of dust and the like.

In operation, with the foot pad 30 in contact with the soil surface, the drop mass 34 is raised by the cylinder 36 to a predetermined height and is then dropped. It falls downwardly under gravity and the projecting portion 116 passes through the opening 118 to impact on the upper surface of the anvil 122. The impact is transmitted through the ball joint to the foot pad 30 and hence to the soil surface on which the foot pad rests. The pins 124 slide freely through the apertures 126 to accommodate the downward movement of the anvil as a result of the impact applied to it. It will be understood that the pins, with the collars 27, allow the mass to be raised when the cylinder 36 is retracted.

A layer of shock absorbing material 136 may be provided on the upper surrface of the anvil which is impacted by the mass 34. This effectively spreads the impact on the anvil out of a longer period of time and this may, depending on the soil conditions, be advantageous from the point of view of improved compaction. Instead of a layer of shock absorbing material gas dampers or other shock absorbing means could be provided. It will be understood that irrespective of whether damping means is provided, the same compaction energy is transmitted to the soil surface.

The second embodiment may also include an automatic control to regulate the number of impact blows, the energy of each blow and so on. Ultrasonic or other sensors (not show may again be used for control of the elevation to which the drop mass is raised for each blow. The numerals 138, 140 indicate rigid and flexible cable trays which are used to support electrical cables and hydraulic hoses.

As shown in Figure 6, the frame 100 includes an upstanding cradle 142 which, in the transportation position of the compactor, supports the operatively upper end of the compactor structure. The numeral 144 indicates a control panel, possibly including a PLC as described previously, located on the frame alongside an hydraulic tank 146.

The frame 100 is shown to have upper and lower parts 100.1 and 100.2. In practice, these parts may be arranged to be capable of sliding in a fore and aft direction relative to one another. The traverse beam structure is mounted to the upper frame part 100.1 so with this feature it is possible to extend the compactor further behind the vehicle to which it is mounted via the frame. Alternatively, the whole frame 100 could be mounted in fore and aft slidable manner relative to the vehicle.

Either of the embodiments described above may also include vraious lock-out features. For instance the PLC may be programmed to prevent operation of the compaction system if the compactor has not bee brought to a substantially upright orientation, or if the foot plate 30 is not in contact with the soil surface.

Claims

1.

A drop mass soil compaction apparatus comprising:

a drop mass soil compactor,

2.

An apparatus according to claim 1 wherein the mounting means is operable to move the compactor to an operational condition in which the compactor is located at an upright orientation adjacent a rear end of the vehicle and the positioning means is operable to move the compactor, in its operational condition, from side to side relative to the end of the vehicle.

3.

An apparatus according to either one of the preceding claims wherein the mounting means serves to mount the compactor on the chassis of a wheeled trailer or truck.

4.

An apparatus according to either one of claims 1 or 2 wherein the mounting means includes a frame and means mounting the compactor to the frame, the frame being mountable on the chassis of a wheeled trailer or truck.

5.

A drop mass compactor according to any one of the preceding claims wherein the positioning means comprises a traverse beam structure on which the compactor is supported and drive means for driving the compactor along the traverse beam structure.

6.

A drop mass compactor according to claim 5 wherein the drive means comprises a chain and sprocket drive.

7.

An apparatus according to any one of the preceding claims wherein the foot pad is pivotally suspended from an anvil which is impacted in use by the mass.

8.

An apparatus according to claim 7 wherein the compactor includes guide posts to guide up and down movements of the mass, the guide posts carrying the foot pad, and means for raising the lowering the guide posts and foot pad.

9.

An apparatus according to any one of the preceding claims wherein the mass control means comprises an hydraulic cylinder operable to raise the mass and drop it.

10.

An apparatus according to claim 9 wherein the mass control means also comprises microprocessor means to control the raising and dropping of the mass.

11.

An apparatus according to claim 10 wherein the microprocessor means is arranged to control the number of times that the mass is raised and dropped and/ or the elevation to which the mass is raised.