The present invention relates to a device for coupl¬ ing pipe sections whose one end has an outwardly directed bead or a plurality of projections positioned along the circumference. More specifically, the invention relates to a device of the type defined in the preamble of claim 1. Pipe sections, to which the invention is applic¬ able, are shown in, for instance, Danish Design Registra¬ tion MR 0508/89.

The invention is particularly directed to a device with a clamping band of the type which preferably is used for the coupling of pipes of thin metal sheet, of which the front ends have flanges or outwardly directed beads, such as spiral-fold ventilating pipes and grain conveying pipes, or for the clamping of, for instance, end covers on electric motors or the like.

Prior-art clamping bands of this type are usually fitted with a clamping device, which can consist of, for instance, a handle with a wire or leaf spring (snap loc ), the handle and the spring being directly inte- grated with the clamping band by bending or like opera¬ tion, or attached by means of mountings which are mounted on the band by riveting or welding.

There are also prior-art clamping bands whose ends are bent perpendicularly away from the band and formed with through holes, the band being clamped by a screw being passed through the outwardly bent ends and a pre¬ ferably square nut being put on the screw, whereupon the screw and the nut are clamped, thereby moving the ends of the clamping band together. These prior-art devices are, however, provided with rather complicated clamping mechanisms. Usually, the abutment means cooperating with the straining screw are specially designed and positioned in specially construct¬ ed spaces or pockets which are defined by flanges of the clamping band. For instance, the pockets may be formed by

the two end portions of the clamping band being rearward- ly bent and riveted, soldered or welded to the outer cir¬ cumference of the clamping band. This makes the construc¬ tion of the clamping device expensive. Therefore, the object of the invention is to provide a simple and inexpensive coupling device which eliminates the drawbacks inherent in prior-art clamping bands. More¬ over, the invention aims at providing a coupling device having a good sealing effect. According to the invention, these and other objects, which will appear from the description below, are now achieved by means of a device which is of the type men¬ tioned by way of introduction and which besides has the features stated in the characterising clause of claim 1. Owing to the cylindrically designed pockets at the ends of the clamping band and the cylindrical elements arranged therein, the clamping band is subjected mainly to tangential forces while being drawn together, since the two cylindrical elements have the possibility of turning as the band is drawn together to a smaller dia¬ meter. In prior-art clamping bands of the type in which flanges are bent perpendicularly away from the bands, these flanges are, however, subjected to heavy stress during drawing together, since they are not perpendicular to the direction of drawing together.

The inventive clamping band has the additional advantage that it is easy to manufacture, since no rivet¬ ing, soldering, welding or other fastening of the clamp¬ ing parts is required, and that the used cylindrical ele- ments and the screw can be of standard type and are available on the market.

The pockets, which are preferably formed in a simple bending operation, can be of, for instance, circular- cylindrical or square cross-section, and the correspond- ing cylindrical elements can be of square and circular- cylindrical cross-section, respectively.

The device according to the invention has the advan¬ tage in respect of manufacturing technique that the two cylindrical elements can be readily inserted sideways into the respective pockets in the ends of the clamping band. The clamping band is preferably supplied with the cylindrical elements positioned in the pockets and the straining screw inserted through and in engagement with the holes in the cylindrical elements.

According to a preferred embodiment, both the pockets and the cylindrical elements are of circular- cylindrical cross-section. This results in the cylin¬ drical elements having a larger engagement surface in the pocket such that the clamping force is distributed over a greater part of the inside of the pocket. For preventing leakage in the joint between the pipe sections, the clamping band is, according to a preferred embodiment, fitted with an internal circumferential seal which preferably is made of rubber and which has two cross-sectionally cup-shaped portions for engaging the two beads of the pipe sections.

Further features of the invention are defined in the appended subclaims.

The invention will now be described in more detail below with reference to the accompanying drawing which illustrates various embodiments and in which

Fig. 1 shows a pipe coupling with a clamping band according to the invention seen in the direction of arrows I-I in Fig. 3,

Fig. 2 is a side view of an end of the clamping band in Fig. 1,

Fig. 3 is a side view of part of the clamping band, whose ends are prepared to be clamped, the pipes in the pipe coupling, however, being excluded for the sake of clearness, Figs 3a and 3b illustrate two alternative embodi¬ ments of pockets and cylindrical elements,

Fig. 4 is a side view, on a smaller scale, of the entire coupling device, and

Fig. 5 is a view, corresponding to Fig. 1, of an embodiment with an internal seal on the clamping band. Fig. 1 shows a coupling device according to the invention, comprising a clamping band 1 being of U-shaped cross-section and having two flanges la, lb which here encompass two schematically illustrated pipe sections 10, 20 with circumferential end beads 11 and 21, respective- ly, which are formed by bending. The flanges la, lb diverge slightly in order to facilitate the mounting of the clamping band 1 on the beads 11, 21.

The clamping band 1 shown in Figs 1-3 has end por¬ tions 2 which are bent to partially circular shape, form pockets and are each provided with an unthreaded hole 3 whose axis is substantially parallel to the tangent line of the clamping band 1 in the position concerned.

As best seen in Fig. 3, there is in one end portion 2 arranged a nut-shaped abutment in the form of a short cylindrical element 4 having a transverse threaded hole 4a. In the other end portion there is arranged a further element, which is also in the shape of a short cylindri¬ cal element 5 but which has a transverse unthreaded hole 5a for a straining screw 6. The components and parts 2-6 thus form a simple, but efficient clamping mechanism for displacing the end por¬ tions 2 of the clamping band 1 relative to each other, whereby the band 1 can be tightened and the desired clamping around the beads 11, 21 can be achieved. As shown in Figs 3a and 3b, as variants, a cylin¬ drical element of square cross-section can be arranged in a circular-cylindrical pocket, or a circular-cylindrical element can be arranged in a pocket of square cross-sec¬ tion. To accommodate the straining screw 6, the end por- tions of the clamping band 1 are in this case fork-shaped at the free ends.

According to a preferred embodiment, the clamping band 1 has an internal circumferential seal 25, as shown in Fig. 5, consisting of a polymer, preferably rubber. The surface of the seal 25 facing the beads 11, 21 (Fig. 1) has two cup-shaped portions 26 for providing reliable abutment against the beads 11, 21. It will be appreciated that the seal may have other cross-sectional shapes as long as a satisfactory sealing function is achieved.