EP2917417B1

EP2917417B1 - Manhole cover frame for manholes

Info

Publication number: EP2917417B1
Application number: EP13801741.3A
Authority: EP
Inventors: Bruno Zanatta
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-09-19
Filing date: 2013-09-17
Publication date: 2016-11-16
Anticipated expiration: 2033-09-17
Also published as: ITPD20120273A1; EP2917417A2; CN104520510B; CN104520510A; WO2014045198A3; WO2014045198A2

Description

The present invention relates to a manhole cover frame for manholes of the type including the features mentioned in the preamble of the main claim and to the kit comprising the same.
Manholes, particularly for sewers, use manhole covers of a suitable shape for closing the manhole and allowing access thereto when maintenance is necessary. Manhole covers are usually formed of a framework, generally made of cast iron, placed so as to bear on the mouth of the manhole, on which a lid, i.e. a manhole cover, bears so as to prevent access to the sewer system and allow vehicles to pass over said manhole cover.
It should be noted that a very important characteristic of installing manhole covers consists in placing the lid level with the road surface.
This operation is in fact necessary in order to prevent the passengers in a vehicle from noticing the presence of the manhole cover, leading to discomfort and, if the difference in level is excessive, the passage of the vehicle over the manhole cover can damage the vehicle itself. Moreover, a difference between the level of the manhole cover and of the road surface can be particularly dangerous for bicycles and mopeds, since this can easily cause the driver to fall off.
In general, the utmost care is therefore paid when creating the road surface so as to avoid such problems; however, on subsequent resurfacing, or in the case of ground subsidence, it is not possible to maintain the surface at the same initial level and therefore a difference in level is generated between the manhole cover and the road surface.
If, after successive surfacing operations, it is wished to restore the level of the manhole covers, it is necessary to remove and reinstall them, an operation that is, however, very costly, time-consuming and labour-intensive.
To remedy these drawbacks some designs have been made for manhole covers provided with height adjustment means, such as those described by the same inventor as this patent application, in European patent application EP2084333 and Italian patent application PD2011A000118 .
The European patent application relates to a kit for lifting a manhole cover, in which a lifting device is inserted into apertures defined between the frame of a manhole cover and the associated manhole.
In particular, the frame has engagement means, in the form of a pair of walls bearing on the edge of the manhole, performing the function of guides into which the lifting device is inserted.
The kit therefore lifts manhole cover, specifically its frame, the lifting device being operated without the need for any fixed threaded elements in the manhole cover structure.
This solution, while certainly being simple and effective, requires a degree of precision in positioning the lifting device in apertures between the frame and the manhole and, consequently, the operation can sometimes prove excessively long and complex.
Furthermore, because of the shape of the engagement means and the weight of the vehicles travelling over the manhole cover, said engagement means can damage the edge of the manhole on which they rest, hollowing out and becoming inserted therein. When the engagement means are inserted into the grooves thus produced on the edge of the manhole, they reduce the size of the apertures between the frame of the manhole cover and the associated manhole, making it more difficult or, in the worst case, impossible to position the lifting device.
With reference to the Italian patent application, this describes a frame and a device for lifting a manhole cover including lifting elements that can be inserted into apertures between the frame and the manhole on which the device is placed so as to bear.
These apertures, produced by milling the edge of the manhole or by pouring cement onto suitable formwork, must be made accurately, so as to obtain a shape that aids insertion of the lifting device. This solution, while being effective, requires a degree of accuracy in producing the apertures, making the operation somewhat long and complex.
Moreover, so that the lifting elements can be inserted into the apertures, the former need to have a curved shape and, during the lifting operation, are subjected to a bending moment that may bend and damage the lifting element. Furthermore, the insertion device comprises a threaded body connected to the lifting element, precisely in line with the end opposite the one inserted between the frame and the manhole.
Therefore, the technical problem addressed by the present invention is that of providing a manhole cover frame that makes it possible to remedy the drawbacks mentioned above with reference to the prior art.
This problem is solved by the manhole cover frame for manholes according to claim 1 and the kit according to claim 9.
The present invention has some outstanding advantages. The main advantage is that the manhole cover frame according to the present invention allows the manhole cover to be installed simply and rapidly, while being extremely easy and economical to produce.
Other advantages, features and methods of use of the present invention will emerge from the following detailed description of some embodiments, presented for the purpose of non-restrictive illustration. Reference will be made to the Fig. in the attached drawings, in which:

Fig. 1 is an exploded perspective view of a manhole cover frame according to the present invention;
Fig. 2A-B is a detail of the perspective view of a manhole cover frame according to the present invention;
Fig. 3 is a view from below of the manhole cover frame according to the present invention;
Fig. 4 is a further detail of the perspective view of a manhole cover frame according to the present invention;
Fig. 5A is a side view of the manhole cover frame according to the present invention;
Fig. 5B is a plan view of the manhole cover frame according to the present invention;
Fig. 6A-B-C are perspective views of elements of a device for lifting the manhole cover frame according to the present invention; and
Fig. 7 and 8 are respectively a perspective view and a related detail of a lifting device for frames produced according to the prior art.

With reference first to Fig. 1, this shows an exploded perspective view of a manhole cover frame 1 for manholes 2, intended to be placed so as to bear on the same.
In a preferred embodiment, the frame 1 is formed of a box-shaped structure which is defined mainly by a perimeter wall 12 and a framework 11 within the latter. The perimeter wall 12 extends substantially parallel to the direction of the outer walls of the manhole 2, on which the frame 1 will bear, and defines a perimeter of a sufficient extent to enclose the manhole 2. The framework 11 extends from the perimeter wall 12 towards the inside of the frame in a direction which is substantially perpendicular to that of the wall 12, and has a lower surface intended to be placed so as to bear on an edge 21 of the manhole 2 and an upper surface capable of receiving a lid (not shown) for the manhole cover. It should be understood that, in this context and in general in the following description, the term "upper" refers to a direction corresponding to the direction towards the outside of the manhole cover, while "lower" refers to the opposite direction.
As an alternative to the embodiment shown in the figure, the box-shaped structure may also be formed of a main frame and a counter-frame, concentric with the latter. However, as will be understood from the following, the device according to the present invention advantageously does not require the use of a counter-frame, and therefore lends itself to simple, economical production.
As shown more clearly by Fig. 2A and 2B, the upper surface of the frame 1 can comprise a plurality of ribs 8 which extend between the perimeter wall 12 and an inner shoulder 14 - concentric with the perimeter wall - and are placed perpendicular to said wall and also to the framework 11.
Accordingly, the ribs 8 allow the rigidity of the frame to be increased, countering any possible deformation when subjected to external stresses generated by the passage of vehicles over the manhole cover.
As can be seen in Fig. 1, 2A and 2B, the shoulder 14 extends over the upper surface of the framework 11 in a direction perpendicular thereto and substantially parallel to the perimeter wall 12, defining an inner portion of the framework 11 on which the lid is placed so as to bear, with the interposition of damper elements 10, as will be shown more clearly below.
A layer of concrete of up to 4 cm thick will be applied over the framework 11 and then covered with asphalt or bituminous conglomerates.
With reference now to Fig. 1 and 3, the frame 1 in the present embodiment has a substantially square section and, what is more, the inner framework has bevelling at the four corners. Specifically, the inner framework 11 comprises three rounded corners, whereas the fourth corner 9 is defined by the intersection of the two sides of the framework 11 with a straight line transverse thereto, as shown more clearly in Fig. 2A. This corner acts as an orientation element, indicating the correct positioning of the lid on the frame 1, which will have a complementary shape for that purpose, to fit the cast iron lids now commercially available.
As outlined above, when the frame 1 bears on the manhole 2, the box-shaped structure envelops the manhole 2 in part, so as to hold the manhole cover in a stable position.
With reference to Fig. 3, a series of holes 13 are formed on the surface of the frame 1, the holes 13 being made substantially close to the inner perimeter of the frame 1.
In the assembly phase for the frame 1, the holes 13 thus produced, which are, however, visible on the lower surface of the framework 11, permit simple, fast fixing of the shoulder 14 to the inner framework 11. It should be noted that this expedient makes it possible to avoid producing a monobloc type of frame 1, thereby reducing manufacturing time and costs.
Preferably, during installation of the manhole cover, one or more shims 7 can be interposed between the edge 21 of the mouth of the manhole 2 and the frame 1 placed so as to bear on the latter.
Clearly, the more shims 7 are used, the higher the manhole cover will be relative to the road surface.
Furthermore, a series of seats 22, visible in Fig. 1, the purpose of which will be explained more fully below, are made by milling the edge 21 of the manhole 2 or by another, equivalent system.
As will be illustrated in greater detail below, these first cavities 4 are suitable for the removable insertion of a lifting element 61 of a device for lifting the manhole cover frame 1, like the one indicated in Fig. 8 with the numeral 70.
With reference to the embodiment described in the present patent application, the manhole cover frame 1 for manholes 2 comprises a plurality of pairs of intercommunicating cavities, specifically four pairs of cavities positioned in line with the four corners of the frame 1.
More specifically, as can be noted in particular from Fig. 5A and 5B, each pair of cavities comprises, in addition to the first cavity 4, a second cavity 5, both cavities 4, 5 being through-cavities. In detail, the first cavity 4 extends in a direction which is substantially parallel to a plane defined by the mouth of the manhole 2, therefore also to the lower surface of the framework 11, and is defined by two protrusions 41 extending below said framework 11 and by a base 42 connecting said protrusions 41. The first cavity 4 will therefore have a parallelepipedal shape, with a through-aperture between the frame 1 and the base 42 along its longitudinal extension.
Additionally, in the installation phase of the frame 1 onto the edge 21 of the mouth of the manhole 2, the protrusions 41 and the base 42 that define each first cavity 4 will be inserted into a respective seat 22 made by milling the edge 21 of the manhole 2, which will therefore have a suitable shape and size for that purpose.
Consequently, it will be enough for the section of the seat 22 to be shaped so that it can house inside it the respective first cavity 4, without the protrusions 41 or the base 42 fitting the surface of the seat 22 perfectly. In fact, it is clear that the section of the seat 22 does not necessarily have to be complementary to the shape of the first cavity 4, thus permitting less accurate, and hence faster, production of the manhole 2 than the milling phase described in Italian patent application PD2011A000229 .
It should also be noted that the second cavity 5, in each pair of cavities, extends close to the corners defined by the outer framework 12 in a direction which is perpendicular to the longitudinal extension of the first cavity 4. Furthermore, in the preferred embodiment, the protrusions 41 and the base 42 extend in such a way that one end of the first cavity 4 is close to a hole 51 in the second cavity 5 defined on the lower surface of the frame 1.
With reference to Fig. 4 and 5A-B, the shape of the first cavity 4 aids the removable insertion, into its end facing the mouth of the manhole 2, of a lifting element 61 of substantially parallelepipedal shape.
Fig. 7 and 8 show a device for lifting frames according to the prior art, the production and functioning of which are described in Italian patent application PD2011A000118 . In these drawings, the device is indicated as a whole by the numeral 70 and the set of elements which is made up of the threaded portion 72, the lifting arm 73 and the elongated portion 71, which elements are comprised within the lifting device 70 of the prior art, is realised in the present patent by the lifting element 61 and by a lifting bar 62, as will be described in detail below. Specifically, with reference to Fig. 6A-B-C, the lifting element 61 comprises a shank 611 extending between a near end 612 and a far end 613, the far end 613 being concave relative to the longitudinal axis of the shank 611. The lifting element 61 also comprises an appendage 614, which extends from the far end along its longitudinal axis, defined by a cross section with a smaller dimension than the cross-section of the shank 611 and by a pointed end 615.
The lifting device further comprises a lifting bar 62 defined by a threaded body 621 connected to a rectangular parallelepipedal head 622. Moreover, the head 622 has a through-hole 623 extending transversely relative to its longitudinal extension. This through-hole 623, having a complementary shape to the appendage 614 of the lifting element 61, defines an aperture in line with two opposite corners of the parallelepiped for the insertion of the appendage 614.
In order to adjust the height of the manhole cover 1, the second cavity 5 permits the insertion, i.e. the housing, of the lifting bar 62 in such a way that the through-hole 623 of the head 622 faces the through-aperture between the frame 1 and the base 42 of the first cavity 4.
Furthermore, the lifting element 61 will be inserted into the first cavity 4 so that the appendage 614 is completely introduced into the through-hole 623, thus being engaged in the head 622 of the lifting bar 62.
Consequently, in order to adjust the height of the manhole cover 1, use will be made of the lifting device according to the methods described in patent application PD2011A000118.
Specifically, using the lifting device, the lifting element 61, being inside and in contact with the first cavity 4, is lifted while pushing the manhole cover frame 1 vertically upwards.
Additionally, it is clear that the lower surface of the insertion element 61, when inserted in the first cavity 4, faces the base 42 comprised in the frame 1, unlike in European patent application EP2084333 . This feature carries an important advantage, i.e. the possibility of easy insertion of the lifting element 61 into the first cavity 4, the latter being complementary in shape to the lifting element 61. It should be noted that, in the installation phase of the manhole cover 1, or where the manhole 2 is constructed on site, the seats 22 may not be made on the edge 21 of the manhole 2. In that case, with reference to the manhole cover frame and the lifting device described in Italian patent application PD2011A000118 , lifting the manhole cover is precluded since the device suitable for lifting it has to be inserted into the apertures, i.e. the seats, made between manhole and cover. Furthermore, the irregular surface of the edge 21 of the manhole 2 might not, despite the apertures being produced, ensure that the lifting device can be easily and completely inserted.
These drawbacks outlined above are therefore remedied by the frame 1 providing the first cavities 4 shaped according to the present patent.
It is particularly advantageous for the lifting bar 62 to be housed in the second cavity 5, made close to the corners defined by the outer framework 12 of the frame 1, since it permits the alignment of and connection between the threaded body 621 and the appendage 614 of the lifting element 61 without the aid of other elements, thereby optimising the distribution of forces in play while the frame 1 is being lifted and permitting the application of a greater force than the solutions proposed in the documents previously discussed, to lift manhole covers. It should also be noted that the space between the frame 1 and the manhole 2 can thus be increased, so that further shims 7 can be inserted or they can be removed if they are no longer necessary or where the asphalt is milled, as will be described below.
Moreover, the lifting means also allow the frame 1 to be easily removed for maintenance purposes.
After the further shims 7 are positioned, the lifting device can easily be removed, by extracting the lifting element 61 from the first cavity 4 and removing the lifting bar 62. This system advantageously allows this lifting device to be used as the only piece of equipment for removing various manhole covers, so as to achieve a considerable cost-saving compared with the manhole covers provided with known adjustment means.
Moreover, the lifting device can easily be operated by a single operator and without the aid of special external equipment.
In particular, the technical features of the manhole cover frame 1 for manholes 2 according to the present invention allow the frame 1 both to be quickly and easily lifted, by means of the lifting device, for the purposes of removing the shims 7 placed between the edge 21 of the mouth of the manhole 2 and the frame 1, and also to be lowered below the road surface to allow unimpeded milling of the asphalt, or road maintenance operations in general. At the end of the procedure, levelling of the manhole cover will therefore be carried out by inserting the shims 7 removed earlier and applying a new layer of asphalt for asphalting the road surface.
It should further be noted that, owing to the use of the manhole cover frame 1 and the lifting device, the phases of raising and lowering the manhole cover 1 can be performed quickly and easily, allowing the milling and subsequent asphalting of the road surface to be performed in a single operation. The advantage of carrying out in a single operation all the procedures necessary for maintaining the road surface is that it makes it possible to reduce the inconvenience of restricting traffic several times, thereby saving considerable costs such as for bringing the manhole covers to the level of the new layer of asphalt, a problem encountered in the prior art. It is also particularly advantageous to use the damper elements 10 in the portions of the inner framework 11 on which the lid bears, as illustrated in Fig. 1 and 2A-B.
It should be understood that the damper elements 10 are fixed to the framework 11 in the production phase of the frame 1. This solution allows the damper element 10 to be fixed stably and positioned precisely on the frame 1, thereby helping the lid to be accommodated. In this way, the position of the lid, placed so as to bear on the frame 1, is coplanar with the plane defined by the mouth of said frame, thereby avoiding the presence of a step between the lid and the frame 1, which would represent an unpleasant obstacle to the passage of vehicles over the manhole cover. These damper elements 10 have an elongated shape with a U-shaped cross section and make it possible to eliminate or at least reduce the noise from vehicles passing over the manhole cover, this being particularly welcome characteristic for urban centres.
More specifically, through the effect of the pressure exerted by the weight of the vehicles, the damper elements 10 tend to become compressed and therefore to expand into the cavity defined by their U-shape, permitting a considerable reduction in noise when vehicles pass over the manhole cover.
With reference to European patent application EP2084333 , while manhole covers are being installed, damper elements can be fixed, or bonded, to the sides of the framework of the frame, on which the lid will later bear. The installation of the frame may therefore provide for two alternatives, i.e. the application or otherwise of the damper elements between the frame and the lid. It follows that, where damper elements are applied, the lid, since it does not bear directly on the frame but on the damper elements, will be in a raised position relative to the plane defined by the mouth of the frame, thereby making it more difficult to level the manhole cover correctly compared with levelling a manhole cover according to the present invention.
Moreover, while in general manhole cover frames are made of cast iron, the manhole cover frame 1 of the present patent can advantageously be made of COR-TEN steel, which proves particularly effective against the corrosive action caused by the presence of liquids and gases within the manhole 2 and also reduces the cost of manufacturing the manhole cover frame 1.

Claims

Manhole cover frame (1) for manholes (2), capable of being placed so as to bear on an edge (21) of the mouth of said manhole (2), comprising a plurality of pairs of intercommunicating cavities (4, 5), wherein a first cavity (4) extends in a direction which is substantially parallel to a plane defined by the mouth of the manhole (2), said first cavity (4) being insertable into a seat (22) formed on said edge (21) of the manhole (2), and a second through-cavity (5) extending in a direction which is perpendicular to the longitudinal extension of said first cavity (4), characterized in that said first cavity (4) is suitable for the removable insertion of a lifting element (61) and said second cavity (5) is suitable for the insertion of a lifting bar (62), the lifting bar (62) having a head (622) in which at least part of said lifting element (61) can be engaged so as to lift said frame (1) from the manhole (2).
Manhole cover frame (1) for manholes (2) according to claim 1, wherein said first cavity (4) is defined by protrusions (41) that extend below said frame (1) and by a base (42) connecting said protrusions (41).
Manhole cover frame (1) for manholes (2) according to claim 2, wherein said first cavity (4) is of parallelepipedal shape and has a through-aperture between said frame (1) and said base (42) along its longitudinal extension.
Manhole cover frame (1) for manholes (2) according to any of the preceding claims, wherein said frame (1) comprises a plurality of ribs (8) extending perpendicularly between a perimeter wall (12) and a shoulder (14) facing the latter.
Manhole cover frame (1) for manholes (2) according to claim 4, wherein said frame (1) comprises an inner framework (11) extending from said perimeter wall (12) towards the inside of said frame (1) in a direction which is substantially perpendicular to that of said perimeter wall (12).
Manhole cover frame (1) for manholes (2) according to claim 5, wherein said frame (1) comprises damper elements (10) close to said inner framework (11).
Manhole cover frame (1) for manholes (2) according to claim 6, wherein said damper elements (10) have an elongate shape with a U-shaped cross section.
Manhole cover frame (1) for manholes (2) according to any of the preceding claims, wherein said frame (1) has a substantially square cross-section.
Manhole cover frame (1) for manholes (2) according to claim 8, wherein said frame (1) comprises an orientation element (9) indicating the correct positioning of a manhole cover on said frame (1), this orientation element (9) being positioned at one of the corners of the frame (1).
Manhole cover frame (1) for manholes (2) according to any of the preceding claims, wherein said frame (1) is made of COR-TEN material.
Kit for adjusting the height of a manhole cover for manholes (2), comprising a frame according to any of claims 1 to 10, and a lifting element (61) insertable into said first cavity (4) and a lifting bar (62) insertable into said second cavity (5), the lifting bar (62) having a head (622), in which at least a part of said lifting element (61) can be removably engaged, and a threaded body (621) placed in a position which is longitudinally opposite said head (622).
Kit for adjusting the height of a manhole cover for manholes (2) according to claim 11, wherein the head (622) has a through-hole (623) that extends transversely to its longitudinal extension, said through-hole (623) having a shape which is complementary to that of an appendage (614) of the lifting element (61).