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(11) | EP 0 164 242 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Method of machine filling a trench and apparatus for effecting same |
| (57) @ The invention relates to a method and apparatus for the machine filling of a trench
with a flowable filler e.g., asphalt. The method comprises introducing filler 12 into
the trench 18 from a mould 1, the latter being advanceable along the trench 18, and
the mould 1 precluding forward spreading of filler 12 to trench area 18B, with advancement
of the mould 1 commencing when a pre-determined filler pressure is sensed, the filler
12 firstly being shaped and/or skimmed to a level L above the top of the trench 18,
and thereafter being pressed to a level contiguous with surfaces 17 to either side
of the trench 18 by means of a pressure plate 23. The mould 1 comprises leading, intermediate
and trailing mould portions 4, 5, 6, the leading portion 4 being provided with restraining
wall(s) 7, the intermediate portion being provided with shaping/skimming surface 21,
and the trailing portion 6 being provided with a transition surface 22 and pressure
plate 23. |
[0001] This invention relates to a method of machine filling a trench and apparatus for effecting same, with a flowable filler such as asphalt or concrete intended to form a surfacing layer.
[0002] Conventionally, trenches, or at least the upper levels of trenches, are surface layered, e.g. with asphalt etc., by hand, in circumstances where a trench has been dug into a previously asphalted road or pavement surface. Such hand filling is labour intensive, requiring the filler to be barrowed from a dumped supply and also usually requiring additional plant in the form of a tamping roller to ensure that the filler and indeed other filling material in the trench is adequately compacted and that the final level of the trench is contiguous with the original road or pavement surface to either side of the trench. Whilst for small scale operations hand filling is economically viable, for large scale operations such as the requirement to meet the extensive underground cable installations demanded when cable T.V. networks are installed, a mechanised syst em would be highly advantageous, and the present invention is aimed at providing such a mechanised method and apparatus for trench filling with asphalt etc.
[0003] According to a first aspect of the present invention, a method of machine filling a trench with a flowable filler comprises:-
(a) introducing the filler into the trench from a mould itself supplied froma filler supply source, and the mould being progressively advanceable along the trench;
(b) allowing the filler upon being discharged from the mould into the trench to spread from the mould into pressure contact with the sides of the trench, whilst precluding forward spreading of the filler, to any appreciable extent, to an area of the trench in advance of the mould, and whilst allowing a build up in pressure of the filler within the mould and/or trench to a pre- determined amount;
(c) commencing advancement of the mould along the trench when the pre-determined filler pressure is sensed so as to achieve progressive filling of the trench;
(d) shaping and/or skimming the filler by means of the mould to a level projecting from the top of the trench by a predetermined amount; and
(e) maintaining at least a trailing end of the mould (with respect to the direction of mould advance) in pressure contact with the filler by means of a pressure plate to compress the filler to a level contiguous with surfaces to either side of the trench.
[0004] According to a second aspect of the present invention, there is provided apparatus for carrying out the above defined method, the apparatus comprising a mould attachable to a vehicle (so as to be advanceable with respect to a trench to be filled) by means of an attachment member, the mould being elongate, and at least partially of inverted "U"_ section, and comprising:-(a) a leading mould portion (having regard to the direction of advance of the mould, in use) incorporating an inlet orifice for the introduction into the mould of filler from a supply source, and at least one restraining wall extending at least laterally to preclude, in use, entry of filler to any appreciable extent into an area of trench in advance of the mould, with the restraining wall(s) being so dimensioned as to penetrate, in use, at least an upper portion of the trench;
(b) an intermediate mould portion extending from the leading mould portion and comprising a shaping/skimming surface serving, in use, to shape/skim the filler to a predetermined level above the top of the trench; and
(c) a trailing mould portion comprising a downwardly inclined transition surface extending contiguously from a trailing end of the shaping/skimming surface, and a pressure plate extending contiguously from the trailing end of the transition surface to define a downstream, outlet end of the mould to compress or displace the filler such that the trench is surfaced to a level contiguous with surfaces to either side of the trench.
[0005] The invention thus provides a method and apparatus for mechanising the filling, or surfacing, of a trench, with the operation being continuous, so long as a source of filler material remains available, in contrast to the intermittent, hand filling technique. The sensing of the pressure of the filler encourages filler density consistency, whilst the pressure plate is intended to squeeze out any voids remaining in the filler and to produce a satisfactory surface finish to the filler at the level of the original surfaces to each side of the trench.
[0006] Pressure filling of the trench with filler results not only from continuously charging the mould with pressurised filler, but also constraining the pressurised filler between the sides of the trench, the restraining wall of the leading mould portion and the shaping/skimming surface of the intermediate mould portion.
[0007] It will be appreciated that the mould needs to have lateral dimensions determined by the width of the trench to be filled, the method and apparatus in accordance with the invention being particularly suitable for filling relatively small width trenches, e.g. 100 mm, as would be required for the laying of underground cables for a cable T.V. network, and with such a trench the depth of fill would be approximately 60 mm for example.
[0008] The mould in accordance with the invention may be mounted on a vehicle generally of the kind described in my GB Patent 2116620. Thus, the vehicle may comprise basically a wheeled chassis, a power unit mounted on the chassis, a bulk filler receiving hopper mounted on the chassis, an auger located at the bottom of the hopper to work and.compact the filler, and a compaction tube associated with the lower end of the auger. The compaction tube is conveniently vehicle mounted, with the mould attachable to the vehicle at an outlet end of the compaction tube.
[0009] The mould, over its leading and intermediate portions is preferably opened bottomed and of generally inverted "U"-shape, so that filler is discharged into the trench from the open bottom of the leading mould portion.
[0010] The attachment member of the mould may comprise an attachment plate with a plurality of bolt holes for releasably attaching the mould to the vehicle. The mould, and in particular the leading mould portion, may comprise a relatively large inlet orifice e.g., a circular through hole, corresponding in cross section to the outlet end of the compaction tube, the leading mould portion gradually being reduced in cross section from the inlet orifice.
[0011] The mould may comprise two parallel, spaced apart, side plates extending over at least the length of the intermediate and leading m'ould portions and over the intermediate mould portion interconnected by the shaping/skimming plate, which is preferably planar. The side plates may also extend along part of the transition surface. The side plates at the leading mould portion are preferably 'provided with downwardly extending webs at the leading end of the leading mould portion, and at their terminal ends are conveniently combined with the lateral restraining wall, so that all three plates constitute the restraining wall, all three plates projecting downwardly so as to be able to penetrate as far as possible, in use, towards the bottom of the trench, e.g.. by up to 55 mm (for a trench requiring a 60 mm deep filling of asphalt etc). The side plates are preferably spaced apart by a distance slightly less than the width of the trench so as to leave marginal edges between the outsides of the side plates, and the inside of the trench, to accommodate any irregularities in trench width. It follows that filler can spread into these marginal edges and the filler can finally be compacted by the pressure plate into these marginal edges. With this arrangement'the pressure plate is preferably fan-shaped in plan extending from the narrower, shaping/skimming plate to a dimension approximating to, or just exceeding, the width of the trench. The pressure plate may be located in a plane which is parallel to that in which the shaping/skimming surface is located. It is also preferred to provide the mould with a pair of outer, parallel side plates, spaced apart by a distance exceeding the width of the trench, so that lower edges of these outer side plates may constitute slide shoes to slide along the road or pavement surface beyond the trench and hence dictate the position of the mould, and in particular its shaping/skimming surface and pressure plate, with respect to the trench. If the mould in accordance with the invention is intended for use with asphalt, the mould is preferably provided with a burner mounting, whereby a burner nozzle, e.g. for propane, may be mounted on the mould to heat the latter.
[0012] The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which:-
Figure 1 is a side elevation of a mould for use with the method and apparatus in accordance with the first and second aspects of the invention;
Figure 2 is an enlarged axial section through Figure 1;
Figure 3 is an underneath plan view of Figure 1;
Figure 4 is an end elevation of Figure 1 in the direction of arrow A; and
Figure 5 is an end elevation of Figure 1 in the direction of arrow B.
[0013] In the drawings, a mould 1 is attachable to a vehicle (not shown), such as that described in GB patent 2116620, by an attachment member in the form of an inclined attachment plate 2 provided with a plurality of attachment bolt holes 3, the vehicle incorporating a hopper from which trench filler e.g., asphalt, is conveyed to the mould 1 e.g., by a screw auger, the vehicle, and hence the mould 1, being movable in the direction of arrow C.
[0014] The mould 1 comprises a leading mould portion 4, an intermediate mould portion 5 and a trailing mould portion 6, with the leading and intermediate portions having an open bottom and being generally of inverted "U"- shape.
[0015] A leading end of the leading mould portion 4 is defined by the attachment plate 2 which incorporates a restraining wall formed partly by a tongue 7 on a lower edge of the attachment plate 2, the tongue 7 extending transversely of the trench to be filled, as will be described in detail later. The leading mould portion 4, and in particular its attachment plate 2, also comprises a relatively large asphalt inlet orifice in the form of a circular through hole 8 corresponding in diameter to outlet end 9 of a compaction tube 10 of the vehicle, the other end of the compaction tube 10 being in communication with the vehicle hopper and the compaction tube 10 also housing an auger (not shown) rotatable about longitudinal axis 11 to displace asphalt, which is indicated at 12 by the randomly dotted area of Figures 2 and 4. The leading mould portion 4 behind the hole 8 is gradually reduced in cross section by means of an inclined plate 13 extending over the length of the .leading mould portion 4.
[0016] The'mould 1 comprises a first pair of parallel side plates 14 spaced apart by almost the width of the trench to be f illed as can be seen from Figure 4, and extending over the length of both the leading and intermediate mould portions 4 and 5, the side plates 14 being downwardly extended at webs 14a at the leading end of the leading mould portion 4, and the webs 14a being attached to the lateral tongue 7, so that the two webs 14 and the tongue 7 all constitute restraining walls.
[0017] As can be seen from Figure 3, the mould 1 also comprises a second pair of parallel side plates 15 spaced apart by a distance exceeding the width of the trench, so that lower edges 16 of these outer side plates 15 constitute slide shoes, to slide along the road or pavement surface indicated at 17 beyond the trench, indicated at 18. It would normally be the case that the trench 18 is initially filled with hardcore etc., to a surface level 19, with the method and apparatus of the invention being employed to provide an asphalt, finishing layer 20 to a depth D of only 60mm for example.
[0018] The intermediate mould portion 3 is provided with a shaping/skimming surface indicated at 21, which surface is planar, and to opposite edges of which surface are attached one each of the inner side plates 14. As can best be seen in Figure 2, the inner side plates 14 extend beyond the intermediate mould portion 5 over a part of inclined transition surface 22 which extends contiguously from the skimming surface 21 to pressure plate 23 of the trailing mould portion 6, the pressure plate 23 being generally planar an being generally fan-shaped in plan, extending from the shaping/skimming surface 21, which is less than the trench width w, to a dimension just exceeding the width of the trench. A terminal end of the pressure plate 23 is defined by an upwardly extending end wall 24 which carries a mounting holder 25 for a propane burner nozzle (not shown) but available to heat the mould 1 and hence to maintain the asphalt within the mould 1 within an optimum workable and mouldable temperature range.
[0019] Considering now the method by which the apparatus and in particular the mould 1 operates, as mentioned previously asphalt 12 is discharged into the trench and inparticular onto a surface level 19 from the open bottom of the leading mould portion 4, with discharge of asphalt into an area 18B of the trench 18 in advance of the mould 1 being constrained by the retaining wall 7 and webs 14.a of the leading mould portion 4 and with asphalt making pressure contact with sidewalls 18A of the trench 18. In accordance with the method of the invention, mould advance is commenced when a pre-determined fluid pressure is sensed. This is preferably achieved by the arrangement described in my patent GB2116620 i.e. the auger is fluid driven and the auger drive fluid pressure is sensed and/or monitored, so that hydraulic drive to road wheels of the associated vehicle is coupled to the auger drive. In other words, the rate of advance of the mould 1 along the trench 18, and hence the rate of trench filling is controlled in accordance with the prevailing asphalt conditions, including ambient temperature. In general, the mould 17 of my GB Patent 2116620 is simply replaced by the special mould 1 shown in Figures 1 - 5 of this application to attain the trench filling method and 'apparatus herein described. As the vehicle and hence the mould 1 progresses along the trench 18, the skimming surface 21 of the intermediate mould portion 5, together with the side plates 14 of the intermediate mould portion 5, compress and shape the asphalt 12 to a level L slightly above that of the surface 17 to either side of the trench 18. Continued advancement of the mould 1 brings the transition surface 22 into engagement with the elevated asphalt L, thus beginning compression of the elevated asphalt, and finally the pressure plate 23 of the trailing mould portion 6 compresses the asphalt layer 20, removing any remaining voids, and ensures that the fill is only to the level of the surfaces 17 to each side of the trench 18.
(a) introducing the filler (12) into the trench (18) from a mould (1) itself supplied from a filler supply source, and the mould (1) being progressively advanceable along the trench (18);
(b) allowing the filler (12) upon being discharged from the mould (1) into the trench (18) and to spread from the mould (1) into pressure contact with the sides (18A) of the trench (18), whilst precluding forward sprea.ding of the filler (12), to any appreciable extent, to an area (18B) of the trench (18) in advance of the mould (1), and whilst allowing a build up in pressure of the filler (12) within the mould (1) and/or trench (18) to a pre-determined amount;
(c) commencing advancement of the mould (1) along the trench (18) when the pre- determined filler pressure is sensed so as to achieve progressive filling of the trench (18);
(d) shaping and/or skimming the filler (12) by means of the mould (1) to a level (L) projecting from the top of the trench (18) by a predetermined amount; and
(e) maintaining at least a trailing end (6) of the mould (1) (with respect to the direction of mould advance) in pressure contact with the filler (12) by means of a pressure plate (23) to compress the filler (12) to a level contiguous with surfaces (17) to either side of the trench (18).
(a) a leading mould portion (4) (having regard to the direction of advance of the mould (1), in use) incorporating an inlet orifice (8) for the introduction into the mould (1) of filler (12) from a supply source, and at least one restraining wall (7) extending at least laterally to preclude, in use, entry of filler (12) to any appreciable extent into an area (18B) of trench (18) in advance of the mould (1), with the restraining wall(s) (7) being so dimensioned as to penetrate, in use, at least an upper portion of the trench (18);
(b) an intermediate mould portion (5) extending from the leading mould portion (4) and comprising a shaping/skimming surface (21) serving, in use, to shape/skim the filler (12) to a predetermined level (L) above the top of the trench (18); and
(c) a trailing mould portion (6) comprising a downwardly inclined transition surface (22) extending contiguously from a trailing end of the shaping/skimming surface (21), and a pressure plate (23) extending contiguously from the trailing end of the transition surface (22) to define a downstream, outlet end of the mould (1) to compress or displace the filler (12) such that the trench (18) is surfaced to a level contiguous with surfaces (17) to either side of the trench (18).