CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to United Kingdom Patent Application No.

GB1502167.8 filed 10 February 2015, and titled "Interconnecting Mats and Connectors for Interconnecting Mats" which is incorporated herein by this reference in its entirety.

TECHNICAL FIELD

The present invention relates to interconnecting mats and connectors therefor. In particular, it relates to mats for use as load supporting surfaces, more particularly as roadways for vehicles and heavy plants.

BACKGROUND

Interlocking mats for use as roadways for vehicles and heavy plants over soft or unstable terrain are well known. US 6 511 257 discloses one such mat, in which two rectangular panels are overlaid offset to two adjacent sides to form an upper continuous peripheral extension along two adjacent edges and a lower continuous peripheral extension along the other two adjacent edges. Adjacent mats are then laid with the peripheral extensions overlapping and secured together by fastening devices in the form of pegs. The pegs are simple elongate structures, generally oval in cross- section. As such, they are prone to movement with movement of heavy vehicles over the mats, with the result that they can easily work loose, such that adjacent mats are no longer secured together. This situation endangers the roadway becoming disassembled as vehicles use the roadway.

US 6 722 831 seeks to overcome this problem by providing a mat in combination with a resilient fastening device. The fastening device includes an elongate body engageable with a pair of overlaid mats in the same manner as US 6 511 257. However, the elongate body of the fastening device is provided with a central bore to receive a rod, rotatable within the bore, and having a footed keeper at a lower end of the rod, the footed keeper extending axially beyond the body of the device. The upper end of the rod includes a driver recess to receive a driver to rotate the rod axially within the central bore. Footed keeper is elongate, corresponding with the elongatedness of the body, such that a 90° rotation of the rod causes the footed keeper to extend outwardly from the elongate body into a recess or cavity formed in the lower of the two overlapping peripheral mat portions.

DISCLOSURE OF THE INVENTION

The present invention seeks to provide an alternative solution to the problem of the fastening devices of US 6 511 257.

In its broadest sense, the present invention provides an interlocking mat system comprising a plurality of mats interconnectable by means of at least one fastening device. Each mat comprises a polygonal panel having at least one upper peripheral flange and at least one lower peripheral flange wherein each flange is formed with a through aperture; and wherein said plurality of mats are adjacently arrangeable in a configuration such that upper and lower peripheral flanges of adjacent mats respectively overlap and at least one through aperture of an upper peripheral flange is coincident with at least one through aperture of a lower peripheral flange to form a through-bore; and wherein the fastening device comprises a body shaped and dimensioned to fit the through-bore, a foot axially rotatable with respect to the body between an insertion position for insertion of the fastening device to the through-bore and a locking position in which removal of the fastening device from the through-bore is prevented; characterised in that the apertures of the mats and the body of the fastening device are generally square in plan view and the foot is generally triangular having two sides of substantially the same dimension as an edge of the generally square body and a third side of substantially the same dimension as a diagonal of the generally square body.

Preferably, at least one side of each of the body, apertures and foot is curved, preferably concave. Preferably, each side of the body and of each aperture is concave.

Preferably, the fastening device further includes a stop arrangement to limit rotational movement of the foot.

Preferably, the stop arrangement includes a stop pin associated with the body and an arcuate recess associated with the foot, wherein the pin engages the arcuate recess.

Preferably, the system further comprises a drive pin operatively connected to the foot for rotation of the foot.

Preferably, the arcuate recess associated with the foot is formed in the drive pin.

Preferably, the arcuate recess describes an angle of 45°.

Preferably, the system further comprises a detent assembly adapted to bias the foot into at least one of the insertion and locking positions.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the present invention will now be described in further detail, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of an embodiment of a mat in accordance with the present invention;

Figure 2 is a perspective view of an embodiment of a fastening device in accordance with the present invention; Figure 3 is a cross-sectional view of an embodiment of an interlocking mat system in accordance with the present invention comprising two mats of Figure 1 and the fastening device of Figure 2; Figure 4 is a series of views of the foot of the fastening device of Figures 2 and 3;

Figure 5 is a series of views of the pin of the fastening device of Figures 2 and 3;

Figure 6 is a schematic part underside view of an embodiment of a mat system of the present invention with a fastening device in an insertion position;

Figure 7 is a schematic part underside view of an embodiment of a mat system of the present invention with a fastening device in a locking position; and Figure 8 is a cross-sectional view of the body of the fastening device of Figures 2 and 3.

BEST MODE(S) FOR CARRYING OUT THE INVENTION Referring to Figure 1, there is shown a mat 10 for an interlocking mat system in accordance with the present invention. The mat 10 is of a generally similar construction to those well known in the art, such as that of US 6511257 or US 2006/0010830. Conveniently, the mat is formed of two identical rectangular planar mat elements, 11,12 secured together in an off-set manner to provide a central mat region 13 and upper and lower peripheral flanges 14,15. As a consequence of this construction, the flanges are half the thickness of the mat as a whole. Other constructions to achieve the same design are equally suitable, such as moulding the mat as a single unit.

Upper peripheral flange 14 is of generally L-shaped form, projecting laterally from two adjacent edges of central mat region 13 of the upper (as viewed in Figure 1) rectangular mat element 11; and lower peripheral flange 15 is correspondingly L- shaped, projecting laterally from the opposite two adjacent edges of central mat region 13 of the lower (as viewed in Figure 1) rectangular mat element 12.

Flanges 14, 15 allow a plurality of mats 10 to be arranged adjacently to one another to form a continuous surface. Typically, an array of mats is arranged in a stretcher bond type pattern, to provide a stable connection between adjacent rows of mats to form a strong surface for support of heavy loads.

Adjacent mats are held together in the desired relationship by means of fastening devices coupling the upper peripheral flange 14 of one mat to the lower peripheral flange 15 of an adjacent mat. Each mat of an adjacent pair is formed with a plurality of apertures 20 spaced around upper and lower peripheral flanges 14,15. The plurality of apertures are spaced such that apertures in adjacent mats are aligned when adjacent mats are fully aligned (i.e., directly side-by-side) and partially aligned, such as in a stretcher bond type pattern. The apertures 20 are also positioned such that the rectangular mats 10 can be orientated axially or orthogonally and also such that the mats can be connected with either surface uppermost. This avoids the need for installers of support surfaces formed from mats of this type having to be concerned with laying mats with a correct side facing upwardly.

In accordance with the present invention, apertures 20 are generally square in plan view. An embodiment of a fastening device 21 in accordance with the present invention is shown in Figure 2. The device comprises a generally square cross-section body 22 corresponding to the shape and dimensions of apertures 20 of mats 10. Body 22 acts to maintain the fastening device 21 in the correct orientation within an aperture 20. Suitably, body 22 has a correspondingly square head or cap 23. In alternative embodiments, as shown in Figure 2, head or cap 23 is circular.

Fastening device 21 has a keeper or foot 24 rotatable with respect to body 22. Foot 24 is generally triangular in plan view, suitably having the general shape of an isosceles triangle in which the two equal sides are orientated at 90° to each other and have generally the same dimensions as the sides of the generally square body. The unequal side of the triangular foot has a dimension generally corresponding to the diagonal of the body. In the preferred embodiment shown, apertures 20, body 22 and foot 24 are not square but, rather, follow the general regular quadrilateral shape of a square, but with concave edges to provide corners in the form of curved lobes 25,26,27 rather than 90° or 45° angles. This can allow the provision of enlarged lobes (compared with the area of the corner of a square) and thereby provides greater surface area overlap between the foot 24 and the aperture 20 in use in the locking position, as will be seen below. Additionally, the curved surfaces provide for easier insertion and rotation.

As already stated, foot 24 is rotatable with respect to body 22. Foot 24 is caused to rotate through rotation of a pin 30 terminating within cap 23 to which foot 24 is coupled. In the embodiment shown, pin 30 is formed with a hexagonal aperture 31 for receipt of a correspondingly hexagonally shaped key or driver (not shown) as is well known in the art. In certain embodiments, pin 30 is formed integrally with foot 24, such as by casting or milling. Body 22 can be moulded around the integral combination of foot 24 and pin 30. However, in preferred embodiments such as that shown in Figure 3, for ease of manufacture, assembly, servicing and repair, foot 24 and pin 30 are formed as separate elements, preferably by milling, and secured together, through body 22 which is formed as a separate moulding, by a fixing bolt 32. Foot 24 is shown in more detail in Figure 4 and pin 30 in more detail in Figure 5. As shown, foot 24 and pin 30 are formed with generally triangular male and female mating surfaces 33,34 to prevent rotation of the pin with respect to the foot.

Figure 3 is a cross-sectional view showing the essential elements of the mat system of the present invention in use. Two mats 10 are placed together with their upper and lower peripheral flanges 14,15 overlapping and respective apertures 20 aligned. Fastening device 21 has been inserted through the aligned apertures 20. Rotation of fastening device 21 with respect to aperture 20 is prevented due to the generally square design of body 22 engaging the correspondingly shaped aperture 20. Figure 6 is a schematic view showing the underside of the lower mat 10 with the foot 24 of fastening device 21 in its insertion position. After insertion through both mats, foot 24 is rotated through 45° to a locking position in which lobes 27 of foot 24 overlap edges of the aperture 20 of the lower of the two mats, thereby securing the two mats together. This arrangement is viewed schematically in Figure 7 and shown in cross- section in Figure 3. It will be appreciated that developing the generally square shape to the aperture and body and triangular form of the foot by forming them with concave rather than planar surfaces provides an increased surface area to the overlap between foot 24 and the surface of flange 15 against which foot 24 bears, thereby increasing the strength and resilience of the fastening action.

As is most clearly seen in Figures 3 and 4, foot 24 has a planar lower surface 35 which, in use, becomes co-planar with the lower surface of the overlapping mats, and an inclined upper surface. Inclined upper surface has a first surface portion 40 having a shallow frusto-conical form which, in use, bears against a correspondingly inclined frusto-conical surface 41 of that portion of the underside of the lower peripheral flange 15 that surrounds aperture 20. The inclined upper surface of foot 24 has a second portion 41, of frusto-conical form, having a greater angle of inclination with respect to the planar lower surface 35 of foot 24. Second portion 41 fits within a correspondingly shaped socket within a lower portion of body 22.

Pin 30 and foot 24 are typically formed of stainless steel to avoid corrosion, since mats and fastening devices of the present invention are typically used in environmentally challenging conditions, such as continuous damp and mud. Body 22 is suitably moulded from a chemically and mechanically resilient polymeric material such as polyoxymethylene, also known as acetal.

In the preferred embodiment shown, the fastening device includes a stop pin arrangement to constrain rotational movement of pin 30 ( and thereby foot 24) within body 22. A stop pin 43 (Figure 3) is mounted in body 22, orientated parallel with the axis of rotation of pin 30. Pin 30 has a head which includes a circumferential arcuate recess 44 (Figures 2 and 3) which, in the assembled fastening device, engages stop pin

43 to constrain rotation of pin 30 within the limits of arcuate recess 44. Arcuate recess

44 describes a 45° angle, corresponding to the angular movement of foot 24 between the insertion and locking positions.

As shown in Figure 3, preferred embodiments of the fastening device of the present invention also include a spring detent member to guide and urge pin 30 between the insertion and locking positions, to provide a positive indication to the user that the correct position has been achieved. In the embodiment shown, a spring biased detent pin 45 is mounted within body 22 and engages one of a pair of detent recesses 46 formed in a lower surface of pin 30. Each recess 46 is associated with the insertion position of the pin 30 or with the locking position. Suitably, each detent recess is positioned at 180° to a respective limit of arcuate recess 44. However, alternative positioning is equally suitable.