GB2335938A

GB2335938A - A reinforced manhole cover

Info

Publication number: GB2335938A
Application number: GB9806928A
Authority: GB
Inventors: Anthony Charles Fox
Original assignee: HIGH CROSS FORECOURT PRODUCTS; HIGHCROSS FORECOURT PRODUCTS L
Current assignee: HIGH CROSS FORECOURT PRODUCTS; HIGHCROSS FORECOURT PRODUCTS L
Priority date: 1998-03-31
Filing date: 1998-03-31
Publication date: 1999-10-06
Anticipated expiration: 2018-03-31
Also published as: GB2335938B; GB9806928D0

Abstract

A manhole ever comprises a top 1 and a base 4 which define a space therebetween, and at least one reinforcing wall 10 which extends at least partially between the top and base, wherein said at least one reinforcing wall 10 has a tortuous, for example a zig-zag, configuration. The manhole cover may fit into a flame 20 which is set into the floor or area to which access is required. The reinforcing wall 10 may be provided by an insert which may have different corrugations. The parts are preferably made of a glass reinforced plastics matrial.

Description

2335938 MANHOLE COVER DESCRIPTION is The present invention relates to a

manhole cover for closing an opening in a surface, such as a road or garage forecourt surface, the cover being receivable within a f rame set in the surface to surround the opening.

Manhole covers known in the art take many varied forms and have been constructed of various different materials. One known form employs glass reinforced plastics (GRP) andlor carbon f ibre material. In known manhole covers employing these materials. the structure of the cover presents a dish-shaped base closed by a generally flat top, to define therebetween a space which is filled with a suitable reinforcing material, typically a foamed plastics material.

Some of these know manhole covers also include a criss-cross structure of reinforcing walls within the space between the top and base, which provides the covers with added strength. Alternatively, a structure having reinforcing walls extending radially outwardly of the centre of the cover, has been used.

However these known forms of manhole cover tend to be insufficiently strong and rigid to withstand deformation of the top and compression of any internal reinforcing material, particularly when made of plastics materials.

It is an object of the present invention to provide a manhole cover which overcomes, or at least substantially reduces, the foregoing disadvantages associated with the known manhole covers discussed above.

According to the present invention, there is provided a manhole cover comprising which define a space therebetween, and at least one reinforcing wall which extends at least partially between the top and base, wherein said reinforcing wall has a tortuous configuration, such as a zig-zag configuration, when viewed in plan.

It has been found that, a top and a base because tortuous reinforcing walls provide greater contact 'Length with, and hence support for, the top of the cover than conventional covers with criss-cross or radiating reinforcing walls, the strength, particularly in vertical compression, of the inventive manhole covers is far greater than -that of existing manhole covers.

The or each reinforcing wall may define voids which may or may not be filled with a suitable filler.

The top and base of the cover are preferably joined together at their peripheries and in a preferred embodiment of the inventive manhole cover, the tortuous reinforcing wall (s) may be provided by an insert, preferably preformed, which can be corrugated by alternating crests and troughs between which any extending voids are defined. In this manner, the crests and troughs of the reinforcing wall(s) may provide alternately inverted channel sections.

The corrugations provided by the alternating and radiating crests and troughs of the tortuous reinforcing walls, may be of any suitable crosssection, for example, rectangular, square or sinusoidal (arcuate).

The manhole cover preferably has a peripheral wall which may depend from the periphery of the top or upstand from the periphery of the base. The base may be dish-shaped to provide it, and hence the cover, with additional rigidity.

Preferably, the top, base arid tortuous reinforcing walls, such as the preformed insert, of the cover are formed of a glass reinforced plastics (GRP a carbon fibre material, or any other suitable composite material or any combination thereof.

Any preformed insert providing the tortuous reinforcing walls, may be of such a thickness, measured from trough to crest, that, with the troughs resting on the internal surface of the base, the crests support the internal surface of the top. Such _nternal surfaces of the base and tops, respectively, may be adhered, for example by a polyester adhesive, to the troughs and crests which provide the tortuous reinforcing walls of the preformed insert.

The manhole cover of the present invention may take any desired shape when seen in plan view. Typically, it may be either polygonal, such as square, or circular.

Although the preferred embodiment of cover utilises a preformed insert, any other suitable form of structure may be used for the tortuous reinforcing walls.

4 - The manhole cover may have its peripheral wall shaped to be received in, and engage, an internal peripheral wall of a complementary frame.

An embodiment of manhole cover in accordance with the present invention will now be described in detail by way of example only and with reference to the accompanying drawings in which:

Figure 1 is an exploded view, in perspective, of the embodiment of manhole cover, in association with a corresponding frame; and Figure 2 is a cross-sectional elevation of the. manhole cover shown in Figure 1, when assembled and installed in a cor-responding frame set in concrete.

Referring firstly to Figure 1 of the drawings, a generally square manhole cover comprises: a substantially flat top 1 having a downturned peripheral lip 2 and a roughended non-slip upper surface 3; a dish-shaped base 4 having a substantially flat bottom 5 and a tapering, upstanding peripheral wall 6; and, receivable within the dish-shaped base 4, to be just encompassed within the overall height of the peripheral wall 6 thereof, a preformed insert 7 formed as a unitary member having integral alternating crests 8 and troughs 9 which are of corresponding tortuous configuration, when viewed in plan, namely, zig-zag configurations, to define a plurality of upstanding zig-zag reinforcing walls 10.

Generally triangular portions 10', 101f01 of otherwise full zig-zag reinforcing walls are provided at respective opposed edges of the preformed insert 7, to complete the zig-zag reinforcing wall configuration.

The underside flat surfaces of the troughs 9 are able to rest on the internal topside surface of the bottom 5 of the base 4 and the preformed insert 7 is preferably secured in position with respect to the base 4 by a suitable adhesive, for example a polyester adhesive, applied between those underside flat surf aces of the troughs 9 of the insert 7 and the internal topside flat surface of the bottom 5 of the base 4.

Assembly of the manhole cover is completed by attachment of the top 1, such that its peripheral lip 2 lies in superposition with the periphery of the base 4, and the internal flat underside surface of the top 1 rests upon, and is at least partially supported by, the upper flat surfaces of the crests 8 of the preformed insert 7. A suitable adhesive, for example a polyester adhesive, is also applied between tile peripheral lip 2 and the periphery of the base 4, as well as between the internal flat underside surface of the top 1 and upper flat surfaces of the crests 8, in order to secure the top 1 in f irm engagement with the base 4 and internal, preformed insert 7. In this manner, the so-defined zig-zag reinforcing walls 10, as well as the triangular portions 101, 10", of the insert 7 provide considerable strengthening to the manhole cover by supporting and reinforcing the top 1 in proper spaced relationship with respect to the base 4.

Also, and in such assembled condition of the manhole cover, the preformed insert 7 rests in the J 6 space defined between the top 1 and base 4, whilst the voids def ined between the alternating crests 8 and troughs 9 are preferably left unfilled. However, in certain circumstances those voids may be filled with a suitable filler, such as wood or an expanded plastics material.

is Preferably, the top 1, base 4, and preformed insert 7 are formed, for example moulded, from a glass reinforced plastics (GRP) material, a carbon fibre material, or any other suitable composite material or any combination thereof.

Thus, the inventive manhole cover is of generally square outline shape, this being determined by the outline shape of the square base 4, with the preformed insert 7 formed to fit therewithin and having a plurality of alternating zig-zag crests 8 and troughs 9 which provide upstanding zigzag reinforcing walls 10 defining therebetween spaces which, in the completed assembly of manhole cover form respective unfilled voids.

The manhole cover, when assembled from the top 1, base 4 and insert 7, as described above, is arranged to be fitted into a correspondingly-shaped frame, indicated generally at 20 in both Figures 1 and 2 of the drawings.

As shown in Figure 2, the frame 20 is set in concrete 30, or other suitable material, with its periphery 21 lying generally flush with the upper surface 31 thereof.

The inclined inner walls 22 of the square frame define, at their lower peripheries, a square aperture 23 which lies in register with a correspondingly-shaped vertical opening 33 in the concrete 30, which provides access to, underground petrol storage tank of a petrol forecourt.

say. an station Whilst the present invention has been described above in detail related to the currently preferred embodiments thereof, it is to be understood that any variations or modifications such as fall within the broadest scope of the invention defined within this specification are to be regarded as falling within the scope of the present invention. Thus, the preformed insert 7 of the embodiment is not limited to the precise detailed construction illustrated in the drawings. For example, the alternating zig-zag crests 8 and troughs 9 of the zig-zag reinforcing walls 10 may be of waveform configuration, such as, sinusoidal, rather than being formed by a series of linear configurations.

Thus, manhole covers according to the present invention, afford a lightweight, yet very strong, construction which is easy and relatively economic to manufacture. By virtue of the internal supports provided by the zig-zag or other tortuous reinforcing walls 10 in whatever form, the manhole covers are stronger and less susceptible to deformation and destruction than known manhole covers in the art constructed of GRP and/or carbon fibre materials or any other composite material. The strength and rigidity of the inventive manhole covers arise primarily from the presence and form of the tortuous reinforcing walls and to this extent it is usually - 8 unnecessary for any internal reinforcing filling materials, such as the foamed plastics of the prior art constructions, to be used. However, in certain circumstances, such as very heavy duty usage, at least some of the voids defined between the tortuous reinforcing walls could be filled at least partially with an internal filling material, such as a foamed plastics material or wood.

As indicated above, it has been found that, because tortuous reinforcing walls provide greater contact length with, and hence support for, the top of the cover than conventional covers with criss-cross or radiating reinforcing walls, the strength, particularly in vertical compression, of the inventive manhole covers is far greater than that of existing manhole covers.

9 -

Claims

CLAINIIS

1. A manhole cover comprising a top and a base which define a space therebetween, and at least one reinforcing wall which extends at least partially between the top and base, wherein said at least one reinforcing wall has a tortuous configuration, when viewed in plan.

2. A manhole cover according to claim 1 wherein the tortuous configuration has a zig-zag configuration.

3. A manhole cover according to claim 1 or 2, wherein the at least one reinforcing wall defines voids.

4. A manhole cover according to claim 3 or 4, wherein the voids are filled.

5. A manhole cover according to any preceding claim, wherein the at least one reinforcing wall is provided by an insert, preferably preformed.

6. A manhole cover according to claim 5, wherein the insert defines corrugations.

7. A manhole cover according to claim 6, wherein the corrugations are of rectangular, square or sinusoidal (arcuate) cross-section.

8. A manhole cover according to claim 6 or 7, wherein the amplitude of corrugations is such that, with the troughs thereof resting on the internal surface of the base, the crests thereof support the internal surface of the top.

9. A manhole cover according to any preceding clairn, wherein the top and base of the cover are joined together at their peripheries.

1O.A manhole cover according to any preceding claim wherein the cover comprises a peripheral wag.

11. A manhole cover according to claim 10, wherein the wall depends from the periphery of the top.

12, A manhole cover according to claim 10, wherein the wall upstands from the periphery of the base.

13. A manhole cover according to claim 10, 11 or 12 wherein the peripheral wall is received in, and engages, an internal peripheral wall of a complementary frame.

is

14. A manhole cover according to any preceding claiR wherein the base is dish shaped to provide it, and hence the cover, with additional rigidity.

15. A manhole cover according to any preceding claim, wherein the top, base and the at least one tortuous reinforcing wall are formed of a glass reinforced plastics (GRP), a carbon fibre material, or any other suitable composite material or any combination thereof

16. A manhole cover according to any of claims 6 or 7 to 15 when dependent upon claim 6, wherein the internal surfaces of the base and tops, respectively, may be adhered, for example by a polyester adhesive, to the corrugations.

17. A manhole cover according to any preceding claim, wherein the manhole cover when seen in plan view is polygonal, such as square, or circular.

18. A manhole cover as substantially herein described and with reference to Figures 1 and 2 of the accompanying drawings.