HK1101642B - A covering for an access aperture, and related assemblies - Google Patents

Description

Cover for manhole and related assembly

Technical Field

The invention relates to a cover for an access opening and related assembly.

Background

Manholes, including but not limited to manholes, are commonly formed in, for example, roads, floors, bridge decks, parking lots, shopping centers, sports stadiums, and sidewalks.

One known manhole cover 10 comprises a pair of cover plates 11, 12, as shown schematically in the bottom plan view of figure 1. The cover plate is usually made of cast iron or of steel.

In fig. 1, the rectangular aperture is delimited by a cast iron or steel frame 13, in which frame 13 the cover plates 11, 12 lie acceptably side by side along a diagonal line 14 defined by the respective cover plate edge. The plate is horizontally disposed when in use. When so positioned, the cover closes the aperture defined by the frame 13.

The cover plates 11, 12 visible in fig. 1 are identical to one another at least when viewed from the bottom (as in fig. 1).

Each cover plate is triangular in plan, with the shape being slightly altered by diagonal lines 14 intersecting the diagonals of the rectangular aperture to intersect the opposite edges of the rectangular aperture at short distances from each corner of the rectangular aperture. Each cover plate 11, 12 thus resembles a triangle, wherein the apex of one triangle is cut away along a line 16 placed parallel to the non-adjacent sides 17 of the triangle.

The use of substantially triangular cover plates 11, 12 has well-known advantages.

The main advantage of these is that the triangular cover plate can be easily manufactured to be "wobble free". In other words, it is easily possible to arrange the triangular cover plates to contact the frame 13 at three points. Objects supported at three spaced locations generally maintain inherent stability even when the contact points are unevenly worn.

Metal decking supported in this manner is less likely to generate noise when in use, for example when a vehicle and/or pedestrian passes over it, than decking supported at four spaced locations for example.

In practice, the non-rocking nature of manholes and other manhole cover plates can be achieved by three ridges on the bottom surface of each cover plate, generally included at the vertices of the triangle defined by the plate. When the covers 11, 12 are inserted into the frame, the ridges engage structural members on the frame 13 to support the covers.

The triangular cover plates 11, 12 need to be strong, especially when made of cast iron. The total weight of a pair of cast iron plates designed to cover the 600mm by 600mm square holes shown in fig. 1 is about 50 kg.

As the main purpose of the cover plate is to allow inspection and/or passage through the hole, the cover plate is frequently lifted manually, removed and then replaced.

Repeated lifting of heavy metal plates may cause spinal or other injuries to workers opening manholes. These activities are occasionally also dangerous, simply due to the risk of injury from accidental falls of the plate. This risk is present even in the case where the cover is hingedly fixed to the frame to facilitate its opening, as is the case today.

Disclosure of Invention

According to a first aspect of the present invention, there is provided a cover for an access opening, comprising at least one pair of cover plates of different sizes, the cover plates being positionable adjacent to one another along a diagonal line to define at least a portion of the cover, the larger of the pair of cover plates comprising one or more primary reinforcing members of the cover and at least one first secondary reinforcing member; the smaller of the pair of cover plates includes a lesser number of primary reinforcing members than the larger cover plate; or the main reinforcement member is omitted.

The use of two cover plates of different sizes and the inclusion of one (large) primary stiffening member on only one of the cover plates means that one of them is lighter than the other (assuming that under normal conditions both cover plates are made of the same material). Thus, the lighter of the two cover panels lifts more easily than the heavier, facilitating this type of service which does not require a fully open aperture.

Preferably, the smaller of the pair of cover plates includes one or more secondary reinforcing members. Therefore, the smaller of the pair of cover plates contributes to the overall strength of the cover.

Preferably the or each reinforcing member comprises an elongate rib projecting from the underside of the cover plate in use. While this is the preferred way of embodying the reinforcement member of the present invention, other arrangements are possible.

The primary reinforcing member is adapted to extend generally parallel to the diagonals. Also preferably, the primary reinforcing member is placed closer to the diagonal line than any other edge of the larger of the pair of cover plates. As in the preferred embodiment of the invention, when the pair of cover plates are both triangular, this arrangement provides good rigidity while minimizing the mass of the metal constituting the cover.

In one embodiment of the invention, three or more cover plates are provided. The arrangement preferably includes one or more further diagonal lines along which at least a respective pair of cover plates may be located adjacent to each other.

It is also preferred that the cover plates define a rectangular cover when the cover plates are properly positioned adjacent to each other along one or more diagonal lines. Thus, the cover may comprise one or more pairs of, for example, triangular or rectangular cover plates; or it may comprise a combination of different cover plate shapes, for example a circular portion.

The cover preferably comprises a diagonal line which is a straight line intersecting two adjacent sides of the rectangular cover formed by said cover plate.

In a particularly preferred embodiment of the invention, a diagonal line is provided which intersects a diagonal line of the rectangular cover. Optionally, a diagonal line is provided diagonally spaced from the nearest rectangular cover.

More generally, the diagonal line is a straight line intersecting two adjacent sides of the rectangular cover.

It has been found that the foregoing features of embodiments of the invention provide good strength and considerable portability.

When the cover defined by the cover plate is rectangular, the smaller of the cover plates is preferably triangular when viewed in plan; and the larger is preferably a five-sided profile with four sides perpendicular to each other and a fifth side interconnecting two of the aforementioned sides at a corner.

The larger of the pair of cover plates conveniently comprises two reinforcing protrusions; and the smaller of the pair of cover plates comprises a single said protrusion.

This arrangement results in fewer reinforcing projections for a given size of lid than the lid plate shown in fig. 1, where each lid plate has the same number of projections since the projections are the same.

Thus, the lid of the present invention requires less effort to lift, remove and replace than prior art lids.

The cover conveniently comprises a connection securing the cover plates to each other. This connection preferably allows the board to pivot along the diagonal line.

A generally smaller panel is therefore easily opened from its closed position by hinging it about the diagonal line.

As an alternative, a so-called "loose joint" connection is provided between the panels, which loose joint is known per se in the field of manhole design.

The invention also relates to a surface service assembly comprising a frame defining a bore boundary; and a cover as defined above, movably received in the frame to allow closing and opening of the aperture.

And the assembly preferably includes a hinge pivotally securing one of the cover panels to the frame.

Thus, when forming part of an assembly, a cover, for example the larger, is also easily opened from the closed position by hinging it around the edge of the frame.

In a preferred embodiment of the invention, the frame and each of said cover plates engage each other at three mutually spaced locations to form a non-rocking support for each cover plate. Thus, the known advantages of a non-rocking support of the cover plate apply to the arrangement of the present invention.

When the aperture is rectangular, it is also preferred that the elongate direction of the primary reinforcing member generally coincides with the diagonal of the rectangular aperture.

This ensures that the larger of the cover plates is reinforced adjacent its longest edge, thereby maximizing its strength.

Drawings

Preferred embodiments of the present invention will now be described, by way of non-limiting example, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic bottom plan view of a prior art cover and frame assembly;

FIG. 2 is a schematic bottom plan view of an assembly incorporating a cover in accordance with the present invention;

FIG. 3 is a partially cut-away perspective view of the bottom side of the arrangement shown in FIG. 2;

4-6 show, in perspective view, one possible arrangement for hingedly securing one or more cover plates to a frame defining an aperture; and

figures 7-9 illustrate various preferred embodiments of the present invention.

Detailed Description

Fig. 2 and 3 illustrate the main principle of the invention.

In fig. 2 and 3, a cover 20 for a hole, such as a manhole, comprises a pair of cover plates 21, 22 of different sizes. In the embodiment shown, the cover plate 21 is significantly larger than the plate 22.

The plates 21, 22 are made of, for example, cast iron, in particular so-called "nodular cast iron", or steel.

When placed side by side along the diagonal line 23, the panels 21, 22 define a generally rectangular cover 20 when viewed in plan.

In the embodiment shown, the cover plates 21, 22 define a square. In other embodiments, other rectangular and indeed non-rectangular shapes are possible.

The diagonal lines extend from the first side 24 to the adjacent side 26 of the rectangle so defined, close to but spaced from the diagonal 27 of the rectangle.

Thus, in the illustrated embodiment, the diagonal line can also be thought of as a line along which the cover plates separate without crossing the adjacent diagonal of the rectangle when one of the cover plates is moved relative to the other.

However, such crossing of the diagonals is also possible within the scope of the invention, so that the diagonal lines may intersect a third side 28 of the rectangle, wherein the third side 28 is opposite the first side 24. Although the arrangement shown as such is still preferred.

As mentioned, the use of cover plates 21, 22 of different sizes gives the lid of the invention a very significant advantage in terms of ease of use.

The cover plate comprises several reinforcement elements in the form of reinforcement protrusions. The larger cover plate 21 comprises more reinforcement members than the smaller cover plate 22.

More specifically, the larger cover plate 21 includes two elongate ribs 29, 31 which project downwardly from its underside in use. The smaller cover plate 22 includes a single such rib 32. The ribs 29, 31, 32 are typically cast to the underside of the cover plate.

In the preferred embodiment shown, the ribs 29, 31, 32 are parallel to each other and extend parallel to the diagonal 27 of the rectangle defined when the cover plates 21, 22 are placed adjacent as shown. Furthermore, the elongate ribs 29 are the primary reinforcing members of the larger of the pair of cover plates, coinciding with the said diagonal 27, to reinforce the longest span of the larger cover plate 21 when the latter is supported across the hole.

Although the ribs 29, 31 are shown as being straight when viewed in plan, other shapes are possible within the scope of the invention. For example, curved ribs are also possible, such as "arrow" shaped ribs.

The primary stiffening member ribs 29 are sized and positioned to provide a significant portion of the stiffening of the lid 20. Thus, for example, the rib 29 is larger and longer than the ribs 31 and 32, the latter thus acting as an auxiliary reinforcing element.

This arrangement, in which the number of primary reinforcing members formed on the larger cover plate is greater than the number of primary reinforcing members formed on the smaller cover plate, gives the cover 20 very good strength and lightweight properties.

In the embodiment of fig. 2, the larger cover plate 21 comprises one main reinforcement member and the smaller cover plate 22 comprises one reinforcement member, but it is also possible to provide other numbers of reinforcement members if desired. Thus, for example, it is possible within the scope of the invention to provide two stiffening elements on the larger cover plate 21 and a further main stiffening element on the cover plate 22.

As can be seen in fig. 3, each cover plate 21, 22 includes a peripheral wall 33, 34 that is presented as a downward overhang to provide further reinforcement. The respective ribs 29, 31, 32 intersect said peripheral walls 33, 34 and are fixed thereto, providing a particularly robust structure.

However, other arrangements of ribs are possible. For example, they need not be parallel to each other, and the present invention, which is simply implemented using different cover plates by including "asymmetrically" arranged stiffening members (as described herein), reduces the number of ribs required.

In other words, while in the preferred embodiment of the invention the inequality of the cover plate dimensions is evident from a top view of the manhole assembly, this need not necessarily be the case. Conversely, inequality may result, for example, in the number or size of ribs on the underside of two cover plates, the plan views of which are substantially or completely identical.

In the embodiment shown, the cover plates 21, 22 are fixed to each other by a connection in the form of a hinge, wherein the hinge allows the cover plates to pivot relative to each other about a diagonal line.

The assembly according to the invention comprises a rectangular frame 36, for example as shown in fig. 3, also made of cast iron or steel. In fig. 3, the frame 36 is inverted compared to its orientation in use for ease of illustration.

The frame 36 is square in the illustrated embodiment, although other shapes (including, but not limited to, non-square rectangles) are possible within the scope of the invention.

The frame 36 includes a rectangular peripheral flange 37 at its lowermost extent. In use, the flange is embedded in embedding medium, particularly grout, in a road or similar surface as mentioned above, thereby securing the frame 36 relative to the surface.

Upstanding from the flange 37 is a rectangular wall 38 defining the mouth of the aperture which needs to be closed by the lid of the present invention. The cover plates 21, 22 may be inserted into the space defined by the wall 38 to close the aperture as desired.

Four contoured shoulders 39 are included adjacent the rectangular corners defined by the walls 38 of the frame 36, three of which are visible in fig. 3, with one of the shoulders being hidden from view in partial section in this figure.

The shoulders define three mutually spaced support points for each cover plate 21, 22 engageable by respective feet 41 depending downwardly from the underside of the cover plates 21, 22 adjacent respective apexes of the generally triangular shape defined by the respective apexes in use.

Between them, the shoulder 39 and the foot 41 thus provide a non-rocking support for the respective cover plate 21, 22 when the respective cover plate 21, 22 is inserted into the wall 38 inside the frame.

The larger cover 21 is optionally hingedly secured along one edge to the frame 36. Thus, the cover 21 may be hinged out of the frame 36 so as to be in an open position.

One possible hinge arrangement is shown in figures 4, 5 and 6.

Figure 4 shows the parts of the hinge separated from each other.

In fig. 4-6, the hinge yoke 51, which is separate from the cover plates, is shown in use secured (e.g., by welding or more preferably by being integrally cast therewith) to one of the cover plates 21, 22 (preferably the larger cover plate 21).

The hinge yoke 51 is releasably and rotatably received in a socket 52 that is typically cast into the wall 38 of the frame 36.

As best seen in fig. 4 and 5, the in-use lower end 53 of the yoke 51 includes arcuate bearing surfaces 54, 56 on axially offset opposite sides.

The support surface 54 is a curved recess formed at the lower end of the yoke 51 on the plate-like center portion 57 side. The support surface 56 is constituted by a pair of arcuate surfaces 56a, 56b formed on upper shoulders of respective ear portions 56c, 56d protruding from either side of the central portion 57.

Cuboidal limiting members 58, 59 project in a similar manner from the upper end 61 of the yoke 51 to the ears 56c, 56d, respectively.

As best seen in fig. 5, which is a vertical cross-sectional view of the hinge member, the socket 52 includes a recess 62, the recess 62 including a component (described below) that cooperates with the yoke 51 when the yoke 51 is received in the recess 62.

At its lowermost end, the recess 62 includes inwardly projecting wall portions 63, 64 opposed to each other, the wall portions 63, 64 engaging opposite sides of the lower end 53 of the yoke 51 when the lower end 53 of the yoke 51 is fully inserted into the recess 62 in the vertical direction as shown in fig. 5.

At its uppermost end, the recess 62 includes, on each side, a respective laterally extending notch 66 defined by a peripheral wall 67 and an inwardly extending wall 68 as shown. When yoke 51 is inserted as shown in fig. 5, notch 66 engages cube members 58, 59 to prevent rotation of the hinge.

When the yoke 51 is lifted (by pulling upwardly on the cover plate secured thereto), the cuboidal limiting members 58, 59 rise above the top edge of the respective inwardly extending wall 68. At the same time, the lower end 53 of the yoke 51 is raised above the wall portions 63, 64 and occupies a wider portion of the socket 52 placed above the wall portions 63, 64.

From this position, the yoke 51 can either be lifted completely off the socket 52 (as shown in fig. 4) or can be rotated so that the restricting members 58, 59 pass over the wall 68. During the latter movement, the offset support surfaces 54, 56 bear in the wider part of the groove 62.

The socket 52 includes a laterally extending shoulder 69. The limiting members 58, 59 and the interconnecting portion of the central portion 57 engage the shoulder 69 after the yoke 51 is rotated as described above. This engagement limits any further rotation of the yoke 51 relative to the socket 52 so that the yoke 51 then remains in a horizontal orientation as shown in fig. 6.

The shape of the yoke 51 and the recess 62 is such that the yoke 51 does not lift from the socket 52 when oriented as shown in fig. 6. This is because the lower end 53 of the yoke 51 (when pulled upwardly) engages the ridges 71, 72 overlying the upper open end of the recess 62, preventing the bearing surfaces 54, 56 from passing out of the open end of the recess 62. Only when the yoke 51 is aligned as shown in fig. 5, the yoke 51 has a sufficiently narrow cross section corresponding to the opening at the upper end of the recess 62, thereby allowing the yoke 51 to be removed from the recess 62.

The dimensions of the yoke 51 and the socket 52 are such that when oriented as shown in fig. 6, the central portion 57 of the yoke 51 is recessed below the upper edge of the socket 52. This provides space for a cover plate which is secured to the central portion 57 when closed so as to be flush with the upper edge.

In practice, for each cover plate hingedly secured to the frame, two hinge assemblies are provided as shown, one at either end of each cover plate edge positioned adjacent the frame 36.

The above-mentioned hinged fixing of the cover allows the cover to be supported in the open position when the yoke occupies the position shown in fig. 5. In this orientation, the yoke 51 and socket 52 cooperate to prevent the cover from falling from a vertical orientation to a horizontal orientation.

If preferred, the smaller cover 22 is hingedly secured to the larger cover, it being possible to move both covers simultaneously when desired.

When the cover plates 21, 22 are inserted into the frame 36, they close the apertures as shown in fig. 3. This need not be the case in other embodiments of the present invention. For example, perforated cover plates are possible, as are cover plate arrangements in which not the entire aperture is placed.

Inspection through the hole and, for example, passage of an elongate tool through the hole can be performed with minimal effort by merely hingedly rotating the smaller cover 22 about the diagonal 23 to open the smaller cover 22 to its open position.

If it is then necessary to open the entire aperture, it involves hinging the larger cover plate 21, with the smaller cover plate to which it is secured, to maintain the plate 21 in a constrained condition relative to the frame 36 about the hinge. As mentioned above, it is possible to remove the cover plate from the frame after these hinging movements.

Closing the aperture is the reverse of these steps.

The illustrated embodiment includes a pair of cover plates 21, 22. Two pairs of cover plates housed side by side in a frame similar to frame 36 may be used to close the more elongated rectangular aperture. This is illustrated in fig. 7, where the larger cover plates are indicated by 21a, 21b and the smaller cover plates are indicated by 22a, 22 b.

Fig. 8 shows an example of a perforated cover plate, which shows that the principles of the invention can be applied to drain holes, so that the cover plates 21, 22 can be replaced with grids 21 ', 22' as shown, if desired. Fig. 9 illustrates another embodiment of the invention in which a frame having a conventional square flange, generally designated 136, has a circular aperture formed therein, the aperture portion being defined by an upstanding generally circular wall 138.

In this arrangement, the larger and smaller cover plates 121, 122 are each defined by portions of the final circular cover. The diagonal line 123 is therefore a chord that does not conform to the diameter of a circle.

As shown in FIG. 9, wall 138 may include four radially outwardly extending cubical grooves 139 formed therein. Each of the cover plates 121, 122 includes a cubical protrusion 141 occupying the groove as shown. Thus, the protrusions 141 and recesses 139 prevent rotation of the cover plates 121, 122 relative to the frame 136 and also provide a location for the provided hinge and/or locking arrangement if desired.

All of these arrangements are within the scope of the present invention, with the significant reason being to include the asymmetric arrangement of the primary and secondary reinforcement members as described above.

In addition, while the triangular cover plates 21, 22 shown in FIGS. 1-3 are particularly well suited for being supported by a three-point, non-rocking arrangement, other support arrangements (e.g., four-point support) are possible within the scope of the present invention.

Furthermore, the cover plate need not be triangular or circular when viewed in plan. It is thus possible within the scope of the invention, for example, to provide a series of rectangular cover plates of different sizes and to combine the above-described asymmetrical arrangement of the primary and secondary stiffening members. Such rectangular cover panels may be positioned side-by-side in the frame and may be hingedly secured along one or more edges of the frame if desired.

As an alternative to hingedly fixing the cover plates to each other, it is possible to omit any connection between the plates; or connect them by means of a "loose connection". These connections are known per se.

One form of loose connection is a ridge formed protruding (e.g., by casting) from one of the cover plates so as to be receivable in a loosely restrained manner in a recess in the adjacent cover plate. The shape of the ridges and grooves may be such as to prevent separation of the plates when they are pushed or pulled in one direction and to allow such disengagement when they are pushed or pulled in a different direction.

In another arrangement, a connecting element can be provided which is shaped such that it can be loosely received in recesses formed in the respective adjacent cover plates.

Claims (21)

1. A cover for an access opening comprising at least one pair of cover plates of different sizes positionable adjacent one another along a diagonal line to define at least a portion of the cover, the larger of the pair of cover plates comprising one or more primary reinforcing members and at least one first secondary reinforcing member of the cover; the smaller of the pair of cover plates includes a lesser number of primary reinforcing members than the larger cover plate; or the smaller of the pair of cover plates omits the primary reinforcing member.

2. The lid of claim 1, wherein the smaller of the pair of lid panels includes one or more secondary stiffening members.

3. A lid according to claim 1, wherein the or each reinforcing member comprises an elongate rib projecting from the underside of the lid plate in use.

4. A lid according to claim 2, wherein the or each reinforcing member comprises an elongate rib projecting from the underside of the lid plate in use.

5. The cover of claim 1, wherein the larger of said pair of cover plates comprises at least a pair of pedestals for supporting said cover plates in a frame; and wherein a primary stiffening member is interconnected with the base.

6. The cover of claim 1, wherein the primary stiffening member extends parallel to the diagonal line.

7. The cover of claim 1, wherein a primary stiffening member is placed closer to the diagonal line than any other edge of the larger of the pair of cover plates.

8. The lid of claim 1, wherein three or more lid panels are included.

9. A lid according to claim 8, comprising one or more further diagonal lines along which at least one pair of respective lid panels may be located adjacent to each other.

10. A lid according to any preceding claim, wherein the lid panels define a rectangular lid when positioned adjacent to one another along one or more diagonal lines.

11. The lid of claim 10, wherein a diagonal line is included that intersects two adjacent sides of the rectangular lid defined by the cover panel, the diagonal line being a straight line.

12. The cover of claim 10, wherein including diagonal lines intersecting diagonals of a rectangular cover.

13. The cover of claim 10, including diagonal lines diagonally spaced from the nearest rectangular cover.

14. The cover of claim 10, wherein the larger of the pair of cover plates includes two reinforcing members; the smaller of the pair of cover plates includes a single reinforcing member.

15. The lid as in claim 10, including a connection securing the lid panels to one another.

16. The cap of claim 15, wherein the connection is a loose connection.

17. The cover of claim 15, wherein the connection allows the panel to pivot along a diagonal line.

18. A surface service assembly comprising a frame defining a bore boundary; and a cover according to any preceding claim, movably received in the frame to allow the aperture to be closed and opened.

19. The assembly of claim 18, including a hinge pivotally securing one of the cover plates to the frame.

20. An assembly according to claim 18 or 19, wherein the frame and each said cover plate engage one another at three mutually spaced locations to define a non-rocking support for each cover plate.

21. A service assembly according to claim 18 when dependent on claim 3 or 4 wherein the aperture is rectangular; and the extension direction of the main reinforcing member coincides with the diagonal line of the rectangular hole.