WO2007077289A1

WO2007077289A1 - Cover construction

Info

Publication number: WO2007077289A1
Application number: PCT/FI2006/000424
Authority: WO
Inventors: Erkki Lehtonen
Original assignee: SUUNNITTELUTOIMISTO BESTDAN Oy
Current assignee: SUUNNITTELUTOIMISTO BESTDAN Oy
Priority date: 2005-12-30
Filing date: 2006-12-28
Publication date: 2007-07-12
Anticipated expiration: 2008-06-30
Also published as: FI20051344A0; FI117763B; NO20083329L

Abstract

Cover construction, particularly a cast-iron manhole-cover construction, which is placed usually with the aid of a suitable installation collar (11) on the desired surface, such as a street surface, and which is formed generally of a plate-like component (1) equipped or not equipped with holes, and which comprises a spring component to ensure that it remains in place. The spring component (2) is formed of a separate spring piece, which can be combined with the cover construction to be permanently in place, without fastening means between the cover (1) and the spring. In particular, the fastening takes place by pushing the spring component (2) into grooves formed in the cover.

Description

Cover construction

The present invention relates to a cover construction and more specifically to s construction, which is used to ensure that a manhole cover will remain in place despite the stresses caused by traffic, for example, or despite attempts by children to open the cover. The cover construction is suitable for use in both large and small covers.

Traditionally, the covers of drain, inspection, and other manholes, which a located, for example, in streets, are made from cast iron. The casting technology has been used for a long time and cast iron is, as such, an economical material. Dimensioning is also easy, as the thickness of the material can be increased and various reinforcements can be easily added as required/

A problem is that, even though the covers are placed quite tightly in various collar constructions, traffic often lifts the covers into the wrong position, where they form a direct danger to both traffic and all other road users. Another safety aspect is that the covers of the smallest manholes are of such a weight that even a child can lift them out of place and cause danger to both itself and the environment.

Attempts have been made to solve the aforementioned problem by making covers such that a tool is required to open them and that the cover will remain in place by being anchored in the collar by means of a suitable spring force. Once solution has been to cast some kind of protrusion during the casting of the cover, which protrusion presses against the collar constructions with a certain force. The problem is that conventional cast iron does not permit repeated bending, instead the protrusion easily breaks off, thus making the solution inoperable.

It has also been proposed that the aforementioned spring force can be created by replacing the material with one that will withstand bending. The solution is otherwise functional, except that it is expensive to implement on account of the choice of material, thus leading to a reduction in its competitive situation.

In both of the above attempts, there is still the drawback that the casting mould and the casting event are difficult to implement, due to the complexity of the model. This results in a large number of failed casting pieces and also many material and labour costs.

The present invention is intended to create an improvement over the drawbacks afflicting the aforementioned prior art and create construction, which is economical to manufacture, but which nevertheless overcomes all the aforementioned drawbacks-

In the following, the invention is examined with reference to the accompanying patent drawings, which show one functional solution according to the invention.

Figure 1 shows an axonometric view of the separate parts of the manhole cover;

Figure 2 shows the parts of the cover according to Figure 1 , when combined; and

Figure 3 shows a cross-section, in which the cover is placed in the 'collar'.

It can be seen from Figures 1 and 2 that the cover 1 and the spring 2 are two separate pieces. The combination of the pieces 1 and 2 to form a functioning totality is arranged to take place without rivets or other fastenings means.

In the cover 1 there are conventional reinforcements 3, which ensure sufficient durability. Also in the conventional manner, the edge 4 of the cover 1 is slightly conical, in order to ensure that it will sit tightly, and also to ensure that the cover will not easily become stuck in the collar. The reference number 5 is used to mark a slot, which permits a crowbar-like object to be put between the cover and the collar, in order to crowbar the cover open. The spring 2 is manufactured from a suitable material, which has sufficient flexible properties. The material can be steel, aluminium, or even plastic. The spring is shaped in such a way that, when set in place, it sits with its full spring force against the slightly bevelled surface of the collar. This can be seen clearly in the cross-section in Figure 3.

In the casting situation, grooves 6. 6, into which the spring 2 is pushed, are formed in the cover for the spring 2. The front part 7 of the spring is bent slightly, so that the fastening to the groove 6 will be tight. The friction forces hold the spring in place without rivets, screws, or other fastening means. If necessary, installation can be assisted by using a suitable pin-like object, which can be pushed through the slot 10 to correspond to the front edge of the curved part 8. Lugs 9 also go into the grooves 6, which prevents the spring from moving in such a way that it could go into the wrong position.

Figure 2 shows the spring 2 set in place and is self-explanatory on the basis of the above.

Figure 3 shows the manhole collar component 11 , which is of a type that is mainly similar to standard collars that are on the market at present too. The cover 1 is placed on the collar, when the spring 2 sits with a certain force against the sloping surface 12 of the collar. In order to remove the cover, some pin or bar that acts as a lever must be placed in the slot 5 opposite to the spring, and used to crowbar the cover up, using the edge of the collar as a fulcrum, when the spring will release its grip on the edge 12 of the collar and the cover can be removed. Installation in place takes place simply by first of all setting the spring edge in place and then stamping down on the other edge, after which the fastening will be ready.

In small covers, the single-spring arrangement described above is very suitable for use. However, covers are of very different sizes and for this reason, as the size of the cover increases, the number of springs can be increased. Thus, in the largest covers it is possible to use, for example, three or four springs on different sides of the cover. It is obvious that the strength of the spring can be dimensions and should be dimensioned in such a way as to correspond to the intended use. Thus, for covers of different size, or for different use locations the springs can be thicker, wider, or made from a material giving a greater spring force, than in conventional use.

The invention can be varied in many ways. While remaining within the basic idea, i.e. that a separate spring that is set in place without fastening means is used to ensure the fastening, it is possible to use many other kinds of solution for attaching the spring. Many such solutions can be found in different fields of technology.

Claims

Claims:

1. Cover construction, particularly a cast-iron manhole-cover construction, which is placed usually with the aid of a suitable installation collar (11) on the desired surface, such as a street surface, and which is formed generally of a plate-like component (1) equipped or not equipped with holes, and which comprises a spring component to ensure that it remains in place, characterized in that the spring component (2) is formed of a separate spring piece, which can be combined with the cover construction to be permanently in place, without fastening means between the cover (1) and the spring.

2. Cover construction according to Claim 1, characterized in that the spring component (2) is manufactured from a material other than cast iron.

3. Cover construction according to Claim 2, characterized in that the spring component (2) is manufactured from steel.

4. Cover construction according to any of the above Claims, characterized in that there are grooves (6, 6) in the cover (1) for fastening by pushing the spring (2) into the grooves.

5. Cover construction according to any of the above Claims, characterized in that the spring component (2) is shaped to remain in place with the aid of the friction forces in the grooves.

6. Cover construction according to any of the above Claims, characterized in that the grooves (6, 6) are formed in the reinforcing constructions of the cover.

7. Cover construction according to any of the above Claims, characterized in that there are springs (2) on at least two different sides of the cover.

8. Cover construction according to Claim 7, characterized in that there are four springs (2) at essentially equal intervals relative to the cover.