AU2017201954A1 - A Cover for a Manhole - Google Patents

Abstract

A cover 10, for a manhole structure 12 having a body 14 made of a non-rigid material, has a frame 22 which is configured to be mounted on a peripheral edge 20 of a manhole structure 12, and a lid 24. The lid 24 is configured to be removably located 5 within the frame 22. A securing mechanism 38 is configured to releasably secure the lid 24 to the frame 22. The securing mechanism 38 has: one or more members 42 provided on the frame and one or more apertures 44 provided on a first end 22a of the lid which are configured to engage each other when the lid 24 is located within the frame 22; and a locking system 40 provided at an opposed end 24b of the lid 24. 8814258_3 (GHMatters) P102592.AU.1 Figure 1 24a 10 24b

Description

A COVER FOR A MANHOLE FIELD OF INVENTION

The present invention relates to a cover for a manhole.

BACKGROUND ART

Many utility services utilise infrastructure that runs in underground tunnels and conduits. Such services include the provision of electricity, telecommunications, sewerage and storm water. Access to these underground passages is provided by manholes so that service personnel can make connections, inspections, valve adjustments or perform maintenance as needed. The manhole provides an opening into the tunnel, typically from a street or walkway, which is then closed by a manhole lid.

Manholes have been used for centuries. Originally such manholes and their lids were made of stone or concrete, but in modern times the manholes and their lids are made of cast iron, concrete, reinforced plastics or other composite materials. When made of stone or concrete, the manhole lids can be made relatively cheaply and exhibit the structural advantages of being strong and heavy. A heavy manhole lid assists in keeping the lid in place when traffic passes over it, but it does make it difficult to remove the lid without special tools when access is required. However, in many countries, modern occupational health and safety regulations restrict the weight of the manhole lid. A further problem that is encountered is theft - cast iron lids are often stolen and melted down for resale of the metal. Also, it often happens that vagrants manage to open the manholes and use the tunnels for shelter or storage of their personnel items. This can cause problems in maintaining the efficiency of the municipal services.

For these reasons manhole lids are now often made of lightweight materials, such as reinforced plastics or other composite materials. However, these lightweight materials do not always have the same structural strength as the cast iron lids. When such lightweight manholes are installed in a walkway or street, the poured concrete or bitumen can press in laterally on the top surround of the manhole and the lid, causing the manhole opening to be deformed. This can lead to difficulties in properly seating the lid in place, or, in worst cases, even prevent the lid from being used at all.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a cover for a manhole having a body made of a non-rigid material, the cover comprising: a frame being configured to be mounted on or about a peripheral edge of a manhole structure; a lid configured to be removably located within the frame; and a securing mechanism being configured to releasably secure the lid to the frame.

The frame may be made of metal. The metal may be iron, cast iron, galvanised iron, steel, stainless steel or brass.

The securing mechanism may comprise one or more members provided on one of the frame and a first end of the lid; and one or more apertures provided on the other of the frame and the first end of the lid, the one or more members and the one or more apertures configured to engage each other when the lid is located within the frame.The securing system comprises a locking system having a slide bolt provided on the lid, wherein the slide bolt being reciprocally movable along a path of travel between an extended position in which the slide bolt engages the frame and a retracted position in which the slide bolt is disengaged from the frame enabling the lid to be removed from the frame.

The slide bolt may be biased into its extended position. The bias may be imparted by a spring, a compression spring, a leaf spring or a resiliently compressible material. A cam may extend laterally from the slide bolt.

The cover may further comprise a key for engaging the cam to move the slide bolt into its retracted position.

The key comprises a shaft having a handle at one end and being configured at an opposite end to engage the cam

The lid may comprise a keyhole for receiving the key, and wherein the keyhole forms a rotation axis for the key.

The key may be configured for use as a handle to lift the lid from the frame.

According to one aspect of the present invention, there is provided a manhole comprising: a manhole structure including a body defining a chamber, wherein the body has a peripheral edge surrounding an opening into the chamber, and wherein the body is made of a non-rigid material; a frame being configured to be mounted on a peripheral edge of a manhole structure; a lid configured to be removably located within the frame; and a locking system configured to releasably secure the lid to the frame.

The manhole structure may be made of plastics, reinforced plastics, fibreglass or other lightweight composite materials.

The frame may be made of iron, cast iron, galvanised iron, steel, stainless steel or brass.

BRIEF DESCRIPTION OF DRAWINGS

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

Figure 1 is a perspective view of a cover for a manhole according to an embodiment of the invention, wherein the cover comprises a lid supported in a frame mounted on a manhole structure;

Figure 2 is a perspective view of the manhole structure and cover, but shown with the lid spaced from the frame;

Figure 3 is a perspective view of the manhole structure and cover shown in use ready to be opened with a key;

Figure 4 is a sectional side through the manhole structure and cover of Figure 3 after insertion of the key;

Figure 5 is an enlarged sectional side view of the region indicated by arrow V in Figure 4;

Figure 6 is an enlarged sectional side view of the region indicated by arrow VI in Figure 4;

Figure 7 is a perspective view of the manhole structure and cover, shown with the lid partially lifted for removal from the frame; and

Figure 8 is an enlarged end side view of the manhole structure and cover of Figure 7.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to the drawings, there is shown a cover 10 according to an embodiment of the invention being mounted on a manhole structure 12.

The manhole structure 12 comprises a body 14 forming a chamber 16 with an opening 18 leading into the chamber 16 to permit access thereto. The body 14 has a peripheral edge 20 surrounding the opening 18. Although the body 14 is shown being generally brick shaped with the opening 18 being substantially rectangular, it will be appreciated that the body 14 can have other appearances and that the opening 18 can be square, round or oval. Further, the manhole structure 12 need not be enclosed but can have one or more conduits or tunnels leading into the chamber, either through sidewalls of the body 14 or via its base.

The manhole structure 12 can be made from any type of material. Flowever, in the context of this invention the manhole structure 12 will be made of a non-rigid material, such as plastics, reinforced plastics, fibreglass or other lightweight composite materials. Due to being non-rigid, the manhole structure 12 may experience some flexibility or movement in the body 14, particularly near to the peripheral edge 20, when pressure is applied laterally to the body 12, i.e. inwards towards the chamber 16. Such pressure may, for example, be exerted after installation of the manhole structure 12 by surrounding material of a road or walkway.

The cover 10 comprises a frame 22 configured to removably locate a lid 24.

The frame 22 has a generally inverted U-shape having a transverse top wall 26 from which depends an outer side wall 28 and an inner side wall 30. A flange 32 extends inwardly of the frame 22 from the inner side wall 30. The frame 22 is configured to be complementary in shape to the peripheral edge 20 so that it can be mounted over the peripheral edge 20 to locate the frame 22 onto the manhole structure 12.

The frame 22 may be provided with a plurality of downwardly projecting connection plates 23 to enable fastening of the frame 22 to the body 14. The plates 23 are provided with holes 25 for receiving mechanical fasteners (not shown) to attach the frame 22 to the body 14.

The frame 22 is made of a substantially rigid material so that it will not experience any flexibility or movement when pressure is applied thereto. In this regard it should be appreciated that normal operating pressures are envisioned as would normally be exerted on a manhole in use and not excessive pressures. In the exemplary embodiment the frame 22 will be made of hard metal, such as iron, cast iron, galvanised iron, steel, stainless steel or brass. Accordingly, the frame 22 is configured to provide support to the peripheral edge 20 of the manhole structure 12 so that the body 14 will be able to resist flexing or movement in the body 14 near to the peripheral edge 20 when pressure is applied thereto.

The lid 24 comprises a substantially rectangular sheet 34 from which an annular foot 36 projects. The foot 36 is configured to rest on the flange 32 when the lid 24 is located in the frame 22. The foot 36 has a height being substantially the same as the inner side wall 30 so that, when the lid 24 is located in the frame 22, the sheet 34 will be substantially co-planar with the top wall 26.

The cover 10 includes a securing mechanism to prevent unwanted removal of the lid 24 by unauthorised persons and also avoid accidental displacement of the lid 24 should it be impacted, e.g. by a vehicle driving over it. The securing mechanism 38 comprises one or more members 42 (in this particular embodiment there are two members 42) provided at one end 24a of the lid 24, and associated apertures 44; with a locking system 40 provided at an opposed end 24b of the lid 24.

In this embodiment the members 42 are in the form of two spaced apart knobs or bosses extending from the inner side wall 28 at a height approximately midway between the flange 32 and the top wall 26. The members 42 are configured to be received in the complimentary associated apertures or recesses 44 provided in the foot 32. The apertures or recesses 44 are formed inboard of the height of the foot 32.

In the exemplary embodiment the members 42 and apertures or recesses 44 are cylindrical in shape. But it should be appreciated that other shapes can be provided and that the number of members 42 could be one or more and is not solely limited to two as shown in the present drawings. In particular the members 42 may be in the form of one or more plates or tabs that lie in a vertical plane and extend into the opening 18 from the inner side wall 30. Thus the plates or tabs would be in the form are similar to the strike plate 46 (described later) but rotated through 90°.

The apertures 44 may simply be recesses in the foot 32 and thus need not extend fully through the thickness of the foot 32. In use, when the lid 24 closes the opening 18, the members 38 are slidably received in the slots 44. Also the slots 44 are slightly larger than the members 38 so that there is a slight but sufficient leeway for the lid to be tilted for removal (see Figures 7 and 8). Thus when the lid 24 is to be removed the lid 24 can be tilted upwards until it is substantially removed from the frame 22 and then pulled off the members 38.

It will be appreciated that the members 42 and slots 44 can be inversed such that the members 42 extend from the foot 36 and the slots 44 are formed in the inner side wall 30. Clearly, in such case the slots 44 would likely need to be extended through the body 14 near the peripheral edge 20 in order to accommodate the knobs 42. However, this configuration may encounter difficulties in use if the ground or concrete surrounding the manhole structure 12 is compact around the body a then the ground would block the slots 44 in the body 14.

The locking system 40 comprises a strike plate 46 extending from the frame 22, with the strike plate 46 being orientated substantially parallel to the flange 32. The locking system 40 further comprises a slide bolt 48 housed in a bracket 50 that is joined to the sheet 34 of the lid 24. The slide bolt 48 is reciprocally movable along a path of travel between an extended position (its locking position) and a retracted position (its unlocking position). Figure 5 shows the slide bolt 48 in its extended position. The slide bolt 48 is biased within the bracket 50 into its extended position. The bias can be imparted by a spring, such as a compression spring or a leaf spring. Alternatively the bias can be imparted by: a resiliently compressible material, such a foam or thermoplastic material; or by a pressurised pneumatic ram. The slide bolt 48 has a bevelled edge 52 configured to abut the strike plate 46 when the lid 24 is closed to slide the slide bolt 48 into its retracted position enabling the slide bolt 48 to pass beyond the strike plate 46 and subsequently lockingly engage with the strike plate 46. A cam 54 extends laterally from the slide bolt 48 and is configured to be engaged by a key 56. The key 56 has a relatively simple configuration having a shaft 58 provided with a handle 60 at one end. In this embodiment the handle 60 is formed by bending the shaft 58 at right angles at the one end. The shaft 58 is further configured at an opposite end to engage the cam 54. This can be achieved by bending the shaft at right angles at that end to form a key blade 62. In the exemplary embodiment the handle 60 and the key blade 62 are perpendicular to each other. A circular keyhole 64 is cut through the sheet 34 in the vicinity of the cam 54 so that the key blade 62 can be inserted through the keyhole 64 to contact the cam 54. The keyhole 64 forms an axis of rotation for the shaft 58 such the appropriate rotation of the key 56 causes the key blade 62 to press against the cam 54 to overcome the bias and to move the slide bolt 48 into its retracted position.

Although the exemplary embodiment of the locking system 40 is rudimentary in design, it can be substituted with more intricate locks if required. However, one advantage provided by the exemplary embodiment is that the blade 62 can be used for a secondary function as a tang to engage the sheet 34 for lifting the lid 24 when the slide bolt 46 is retracted to remove the lid 24 from the frame 22.

In use, when the manhole structure 12 is initially installed in a road or walkway, the frame 22 is placed over the peripheral edge 20 to make it more sturdy and rigid so that the body 14 does not flex while the surrounding concrete or bitumen is poured. The lid 24 can be kept in place within the frame 22 during installation, but it would be equally practical to remove the lid 24 during installation.

It should be appreciated that the frame 22 can be easily retrofitted to an existing manhole structure 12 by excavating a region of concrete or bitumen surrounding the manhole structure 12 to enable the frame 22 to be placed over the peripheral edge 20 and then to reseal the surrounding region with concrete or bitumen. In this way, it is possible to replace existing concrete lids with the lid 24.

Normally the lid 24 will be located in the frame 22 to close off the opening 18 into the chamber 16. When access is required to the chamber 16, the key 52 will be placed down flat onto the lid 24 so that its’ bent off end forming the blade 62 is axially aligned with the keyhole 64. After the blade 62 is inserted into the keyhole, the key is rotated through about 90° into a position where the shaft 58 is axially aligned with the keyhole 64, which should normally bring the blade 62 into contact with the cam 54. If immediate contact is not made, then the key 56 can be rotated (anti-clockwise in the exemplary embodiment) until contact is made. Further anti-clockwise rotation will cause the blade 62 to press against the cam 54 to overcome the bias to retract the slide bolt 48. Once the slide bolt 48 fully is retracted, the cam 54 abuts against the bracket 50 - this prevents over-rotation of the key 56 that may lead to the blade sliding off the cam 54 resulting in release of the slide bolt 48.

Finally the key 56 is pulled upwardly to lift the lid 24 away from the frame 22. When lifted sufficiently, i.e. whereby the end 24b is clear of the flange 22, the lid 24 can be slid away from the end 24a to disengage the foot 36 from the knobs 44, which allows the lid 24 to be fully removed and placed aside and the key 56 removed.

After work in the chamber 16 is completed, the lid 24 can be replaced by inserting the end 24a into the frame 22 and engaging the members 38 into the slots 44. Thereafter the end 24b is lowered and dropped or pressed into place so that the slide bolt 48 moves past the strike plate 46 to engage or activate the locking system 40, effectively locking the lid 24 to the frame 22.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. For example in the event that the members 42 are placed on the lid 24 and the apertures are formed in the frame 22, holes or other apertures could be formed in the adjacent portion of the body 14 into which the members 42 can project. This provides an additional means of locking or attaching the frame 22 to body 14. Also the locking system 40 is described as including the strike plate 46 which projects inwardly from the inner side wall 30 of the frame 22. In an alternate embodiment the strike plate 46 could be replaced with an aperture or slot formed within the inner side wall 30 for receiving the slide bolt 48. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims (16)

1. A cover for a manhole having a body made of a non-rigid material, the cover comprising: a frame being configured to be mounted on a peripheral edge of a manhole structure; a lid configured to be removably located within the frame; and a securing mechanism being configured to releasably secure the lid to the frame.

2. A cover as claimed in claim 1, wherein the frame is made of metal.

3. A cover as claimed in claim 2, wherein the metal is iron, cast iron, galvanised iron, steel, stainless steel or brass.

4. A cover as claimed in any one of the preceding claims, wherein the securing mechanism comprises one or more members provided on one of the frame and a first end of the lid; and one or more apertures provided on the other of the frame and the first end of the lid, the one or more members and the one or more apertures configured to engage each other when the lid is located within the frame.

5. A cover as claimed in claim 4, wherein the members extend from the frame and the apertures are provided in the lid.

6. A cover as claimed in any one of the preceding claims, wherein the securing mechanism comprises a locking system provided at a second end of the lid for releasably locking the lid to the frame.

7. A cover as claimed in claim 6 wherein the locking system comprises a slide bolt provided on the lid, wherein the slide bolt is reciprocally movable along a path of travel between an extended position in which the slide bolt engages the frame and a retracted position in which the slide bolt is disengaged from the frame enabling the lid to be removed from the frame.

8. A cover as claimed in claim 7, wherein the slide bolt is biased into its extended position.

9. A cover as claimed in claim 7 or 8, comprising a cam extends laterally from the slide bolt.

10. A cover as claimed in claim 9, wherein the locking system comprises a key for engaging the cam to move the slide bolt into its retracted position.

11. A cover as claimed in claim 10, wherein the key comprises a shaft having a handle at one end and being configured at an opposite end to engage the cam.

12. A cover as claimed in claim 10 or 11, wherein the lid comprises a keyhole for receiving the key, and wherein the keyhole forms a rotation axis for the key.

13. A cover as claimed in any one of claims 10 to 12, wherein the key is configured for use as a handle to lift the lid from the frame.

14. A manhole comprising: a manhole structure including a body defining a chamber, wherein the body has a peripheral edge surrounding an opening into the chamber, and wherein the body is made of a non-rigid material; a frame being configured to be mounted on a peripheral edge of a manhole structure; a lid configured to be removably located within the frame; and a locking system configured to releasably secure the lid to the frame.

15. A manhole as claimed in claim 14, wherein the manhole structure is made of plastics, reinforced plastics, fibreglass or other lightweight composite materials.

16. A manhole as claimed in claim 14 or 15, wherein the frame is made of iron, cast iron, galvanised iron, steel, stainless steel or brass.