DE20008820U1 - Shaft arrangement - Google Patents

Description

Dipl.-Chem. EL FRITZ 00/162

Dr. Dipl.-Phys. R. BASFELD 15.05.2000/HZ/Rh

Dipl.-Phys. E. HARAZIM Patent Attorneys M. HOFFMANN Attorney Mühlenberg 74 59759 Arnsberg

company

Heinrich Meier Iron Foundry GmbH & Co. KG Auf der Welle 5-7 32369 Rahden

" Shaft arrangement"

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The present invention relates to a shaft arrangement with a shaft cover that can be attached to a shaft pipe, which has a shaft frame with a tubular extension that can be inserted into the opening of the shaft pipe, which has inwardly projecting fastening elements that can be brought into engagement with an axial support surface on the tubular extension. A shaft cover for such a shaft arrangement is also the subject of the invention.

Manhole pipes, for example those of inspection shafts in sewer systems for building drainage, are closed with a manhole cover that is flush with the floor surface and is suitable for absorbing the expected traffic loads. For smaller manhole diameters, manhole pipes made of plastic are increasingly being used. The manhole opening is preferably provided with a manhole cover made of cast iron. This is usually made from a manhole frame that is connected to the pipe opening and into which a manhole cover can be inserted. Manhole covers made of cast iron have the advantage that they are extremely robust and yet can be manufactured efficiently.

In a known design, the shaft frame has a tubular attachment on its underside, which is inserted into the shaft opening from above and fastened to the plastic pipe. In the prior art, it is known to provide the tubular attachment on its lower edge with an outwardly protruding, circumferential projection, which is provided with an undercut, which forms an axial support surface. The shaft pipe, which is usually made of plastic, has inwardly protruding fastening elements, which are designed as tongues protruding into the pipe cross-section 5 in the manner of barbs with respect to the aforementioned undercut. To attach the shaft frame, it is simply inserted into the opening of the plastic pipe until these tongues engage behind this axial support surface, i.e. snap into place. This secures the

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Shaft frame secured against lifting out and fixed to the shaft pipe.

This connection, which is known in the state of the art, does have the advantage that it ensures a sufficiently firm and secure fit. However, the disadvantage is that the pipe attachment is undercut on the retaining projection to form the support surface, which requires subsequent machining of the cast iron shaft frame, which significantly increases the manufacturing effort and costs.

In view of this problem, the present invention is based on the object of specifying a shaft arrangement with a shaft pipe and a shaft cover which has a lower manufacturing cost.

To solve this problem, the invention proposes that the tubular extension be provided with openings in its outer circumference into which the fastening elements protruding inwards in the shaft pipe can be snapped. A shaft cover and a shaft pipe for forming this shaft arrangement are also the subject of the invention.

A significant difference between the shaft arrangement according to the invention and the prior art mentioned at the outset is that the tubular extension of the shaft frame can be inserted into the opening of the shaft pipe in such a way that the axial fixation is achieved by form-fitting connections which are formed by the corresponding openings and fastening elements on the tubular extension of the shaft frame or in the shaft pipe. This achieves a whole series of advantages in production and assembly.

A particular advantage of the shaft arrangement according to the invention is that it can be used for a wide range of applications

Fasteners, these are the openings at the base of the shaft frame and the fastening elements that can be snapped into the cross-section of the shaft pipe, are particularly easy to install. The tubular attachment can be easily inserted into the pipe opening. The fastening,

i.e. the axial fixation on the shaft pipe is achieved by locking the fastening elements with the axial inner surfaces of the openings according to the invention, which can occur automatically during the insertion process, as will be explained in detail later. The openings according to the invention offer a further advantage over the prior art in that the relatively large radial play between the tubular extension and the shaft pipe, which is unavoidable in the area of the circumferential undercut, can be reduced. This results in a better fit of the tubular extension in the shaft pipe, without compromising ease of assembly.

Another particular advantage is that the manufacturing effort involved in producing the manhole cover, in particular the manhole frame made of cast iron, is significantly reduced. The openings in the tubular extension according to the invention can be formed using casting technology. Relatively complex machining, such as with the turned undercut in the prior art, is thus largely superfluous. This results in particularly efficient and cost-effective production.

0 Compared to the undercut screwed into the attachment in the prior art, which is necessarily designed to be rotationally symmetrical all the way around, the arrangement of individual openings according to the invention has the further advantage that the fastening elements engaging therein provide protection against rotation. When the locking tongues engage, an axial and radial positive connection is formed at the same time.

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Preferably, the openings in the tubular extension are designed as radial windows. These can be easily made from cast iron, and their shape, number and arrangement can be coordinated with the fastening elements on the shaft pipe.

The design of the openings as radial windows has the additional advantage that the shaft frame can be dismantled from the shaft pipe with little effort. To unlock, the locking elements or locking tongues that engage in the windows from the outside only have to be pushed outwards from the inside of the pipe, which unlocks the opening and allows the shaft frame to be lifted out of the opening. This enables the shaft cover to be replaced, which is not possible with the undercut running around the outside using the current technology.

A secure hold is achieved by arranging several 0 openings around the circumference.

It is particularly advantageous if three windows are evenly arranged in a circle, thus creating a defined and stable support or holder.

In a preferred embodiment of the invention, the fastening elements are designed as spring-loaded locking tongues. These locking tongues are the fastening or locking elements on the shaft pipe, which protrude radially into the pipe cross-section under elastic pre-tension, whereby they can be pressed outwards against their spring pre-tension so that they release the entire pipe cross-section. For the assembly of the shaft frame, this has the particular advantage that the tubular attachment is simply inserted into the opening of the shaft pipe, whereby the 5 locking tongues are initially pressed apart in a spring-loaded manner.

However, as soon as the locking tongues line up with the recesses, i.e. the windows in the tubular attachment, they snap into place due to their spring preload from the outside.

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and thereby automatically ensure that the shaft frame is securely locked in the shaft pipe. To attach the shaft cover, all you have to do is insert the tubular attachment into the opening of the shaft pipe until the locking tongues engage or snap into place. This connection can be made easily by hand and without the use of tools, which makes assembly particularly quick and easy.

The aforementioned locking tongues are implemented in a plastic shaft pipe by forming partially cut-out, inwardly bent areas of the pipe wall. A tab is first formed by an essentially U-shaped cut in the pipe wall, which is then pressed into the interior of the pipe with its free end. In a plastic pipe, the locking tongue is plastically deformed in this way, so that due to the inherent elasticity of the plastic, a locking tongue is formed that protrudes inwards from the pipe wall in a spring-like manner in the sense of the invention. One advantage of these locking tongues is that they protrude axially into the pipe cross-section like a barb in relation to the pipe opening. This means that the tubular extension of the shaft frame can be easily inserted and is securely locked axially once the locking tongues have snapped into place.

The openings in the manhole cover according to the invention are preferably adapted to the shape of the fastening elements in the manhole tube, i.e. the locking tongues. In the case of rectangular or trapezoidal windows, rectangular locking tongues are also provided, the dimensions of which are selected so that on the one hand they easily lock into place, and on the other hand their protruding, axial front edge ensures secure support when engaging in the window. In this way, secure fixing is achieved by an axial positive connection between the locking tongues and the receptacles or windows.

The shaft arrangement according to the invention is particularly advantageous for combining a shaft cover with a shaft frame and a shaft cover made of cast iron with a shaft pipe made of plastic. The inventive design of the shaft cover and the shaft pipe makes the specific usage advantages of the different materials particularly effective.

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The present invention is explained in more detail below using exemplary embodiments with reference to the accompanying drawings. These show in detail

Fig. 1 is a longitudinal section through a shaft arrangement according to the invention;

Fig. 2 a top view of the shaft arrangement according to

Figure 1;
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Fig. 3 a longitudinal section through the manhole cover of the

Shaft arrangement according to Figure 1;

Fig. 4 is a longitudinal section through the shaft pipe of the shaft arrangement according to Figure 1.

In Figure 1 and Figure 2, a shaft arrangement according to the invention is shown once in axial longitudinal section and once in plan view and is provided as a whole with the reference number 1. This is formed by a vertically arranged shaft pipe 2, on the upper opening of which a shaft frame 3 is attached. This shaft frame 3 consists in one piece of cast iron, while the shaft pipe 2 is a plastic pipe.

The shaft frame 3 has a tubular extension 4 which extends downwards and is inserted into the shaft tube 2 from above.

The tubular extension 4 of the shaft frame 3 is provided with openings according to the invention in the form of continuous windows 5. A total of three of these windows 5, which are rectangular in shape, are evenly distributed over the circumference of the tubular section 4, as can be seen particularly well in Figure 2.

The plastic pipe 2 is provided with locking tongues 6 which protrude inwards into the pipe cross-section. These are thereby

formed in such a way that the wall of the plastic pipe 2 is cut in a U-shaped manner and the tongues formed thereby are permanently pre-bent into the interior of the pipe, as can be seen particularly well in the illustration in Figure 4. Due to the elasticity of the plastic, these locking tongues are spring-loaded radially inwards, i.e. they represent an elastic locking pawl directed into the interior of the pipe, which springs back inwards when it is pressed outwards. The arrangement as well as the shape and dimensions of these locking tongues 6 are coordinated with the windows 5 so that they can be locked into them, as shown in Figure 1. In the wall area of the shaft pipe 2 shown in section, it can be seen how this locking tongue 6 engages the windows with its protruding part like a barb, so that the shaft frame 3 is fixed against axial displacement and at the same time is held securely against rotation.

The assembly of the shaft frame 3 shown in Figure 3 onto the shaft pipe 2 shown in Figure 4 is carried out by inserting the tubular extension 4 into the pipe opening from above. This can be done without tools, since this pipe extension 4 has a smaller outer diameter than the inner diameter of the plastic pipe 2. When inserted, the inwardly protruding locking tongues 6 are initially pressed elastically outwards by the pipe extension 4. However, as soon as they line up with the windows 5, they snap into them with a spring, so that the shaft arrangement 1 is fully assembled, as shown in Figure 1.

The illustrated shaft arrangement 1 is completed by inserting and securing a shaft cover 7, also made of cast iron, into the shaft frame 3, as shown in Figure 3.

As already explained above, the cast iron shaft frame 3 can be particularly efficiently installed without

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This also applies to the shaft tube 2 with the locking tongues 6 according to the invention. The assembly is extremely simple because the shaft frame simply has to be inserted into the shaft tube with its tubular attachment until the locking tongues snap into the windows. A further advantage of this shaft arrangement 1 is that the shaft frame 3 can be easily dismantled again by pushing the locking tongues 6 outwards from the inside through the windows 5 and thereby unlocking them. The shaft frame 3 can then be easily lifted off for replacement or renewal.

Claims (8)

1. Shaft arrangement, with a shaft cover which can be attached to a shaft pipe and which has a shaft frame with a tubular extension which can be inserted into the opening of the shaft pipe, which has inwardly projecting fastening elements which can be brought into engagement with an axial support surface on the tubular extension, characterized in that the tubular extension ( 4 ) is provided in its outer circumference with openings ( 5 ) into which the fastening elements ( 6 ) projecting inwards in the shaft pipe ( 2 ) can be snapped. 2. Shaft arrangement according to claim 1, characterized in that the shaft pipe ( 2 ) is a plastic pipe. 3. Shaft arrangement according to claim 1 or 2, characterized in that the shaft frame ( 3 ) consists of cast iron. 4. Shaft arrangement according to one of claims 1 to 3, characterized in that the openings are designed as radial windows ( 5 ). 5. Shaft arrangement according to one of claims 1 to 4, characterized in that several openings ( 5 ) are arranged distributed over the circumference. 6. Shaft arrangement according to one of claims 1 to 5, characterized in that the openings ( 5 ) are adapted to the shape of the fastening elements ( 6 ). 7. Shaft arrangement according to one of claims 1 to 6, characterized in that a shaft cover ( 7 ) can be inserted into the shaft frame ( 3 ). 8. Manhole cover, in particular for a manhole arrangement according to one of the preceding claims 1 to 7, which has a manhole frame with a tubular extension which can be inserted into the opening of a manhole tube, characterized in that the tubular extension ( 4 ) has openings ( 5 ) in its outer circumference into which fastening elements ( 6 ) projecting inwards in a manhole tube ( 2 ) can be snapped.