The invention relates to a coupling device for coupling with a tube, comprising a sleeve part with an insert end for the tube and pressure elements for exerting a clamping force on the tube, wherein the said pressure elements have radially converging surfaces that radially converge towards each other in a direction away from the longitudinal axis of the device, and wherein the sleeve part has tapering support surfaces that cooperate which said radially converging surfaces of the pressure elements for pressing the pressure elements towards the tube, and wherein a sealing ring is applied to provide a seal around the tube, of which sealing ring at least a first portion is placed between the tube and the pressure elements and at least a second portion is placed between the pressure elements and at least one selected tapering support surface of the said tapering support surfaces of the sleeve part .

Such a coupling device is known from EP-A-0 794 378 in the name of the applicant. The pressure elements as applied in this known coupling device are embodied as substantially wedge-shaped elements in order to provide the radially converging surfaces that radially converge towards each other in a direction away from the longitudinal axis of the device. The said pressure elements slidably abut to each other to form a substantially closed ring around the tube in order to effectively press the sealing ring against the tube. The construction with these slidably abutting pressure elements enables the coupling device to accommodate and automatically adjust to different tube diameters without modification of the coupling device and its constituting elements.

A problem with the known coupling device is that it is sensitive to the dimensions of the sealing ring, usually a rubber ring. When the sealing ring is too thick its deformation may become problematic when applying the coupling device to smaller diameter tubes. Eventually this may result in leakage due to the large deformations of the thick sealing ring that are required when applying the coupling device on smaller diameter tubes. The large deformations may lead to rupture of the sealing ring. When on the other hand the sealing ring is too thin the effectivity of the sealing may become less than optimal when the tube has an irregular outer surface. In relative terms the required deformation of a thin sealing ring to avoid leakage is then larger than in case the sealing ring can be designed with a thicker dimension.

Still another problem is that particularly with relatively thick sealing rings the pressure of the medium in the tube may cause the sealing ring to be pressed out from between the pressure elements and the cooperating tapering support surfaces for these pressure elements.

Consequently in the prior art the selection of the thickness of the sealing ring is a delicate compromise aimed at avoiding the above noted problems. As one of the measures that is used in the prior art to alleviate these problems it is known to provide the sealing ring with superficial irregularities at least on the surface that abuts to one of the ta ^¬ pering support surfaces for the pressure elements. A problem with this solution is however that the thinner parts of the sealing ring are then subjected to excessive strain which eventually may also result in rupture of the sealing ring and leakage problems.

It is an object of the invention to provide an alternative solution to the above problems.

It is a further object of the invention to make the sealing ring less sensitive to relative movement caused by the pressures of the medium in the tube that connects to the coupling device.

It is still a further object of the invention to ena ^¬ ble the selection of a wider range of thickness dimensions of the sealing ring of the coupling device.

These and other objectives of the invention that may become clear from the following disclosure are provided by a coupling device having the features of one or more of the appended claims .

According to a first aspect of the invention the selected tapering support surface of the tapering support surfaces of the sleeve part is provided with irregularities so as to counter movement of the second portion of the sealing ring relative to this selected tapering support surface. Surprisingly this solution brings about a huge amount of flexibility in the selection of the thickness of the sealing ring and its application with a large variety of dimensions of the tube without compromising its prime function to avoid leakage. Man forms of irregularities can be applied and their selection should be based on a proper evaluation of the requirements in a particular situation.

A generally applicable form of the said irregularities on the selected tapering support surface is to provide them as protruding ridges extending from this selected tapering support surface.

Advantageously the said irregularities on the selected tapering support surface are provided as concentric ridges relative to the longitudinal axis of the device. Such concentric ridges are easy to manufacture. This ease of manufacturing is particularly promoted when the concentric ridges are uninterrupted. From the perspective of effective sealing it may however also be beneficial that the concentric ridges are interrupted .

Another suitable form of the irregularities is if they exhibit the shape of a Belgian waffle. This Belgian waffle shape is also easy to manufacture and may be particularly effective with a sealing ring of relatively soft rubber.

In most cases it suffices that the irregularities an shaped symmetrically, yet they can also be selected with an asymmetrical shape depending on the circumstances of the case

With reference to the appended drawing of some typical exemplary embodiments of the coupling device of the inven tion, the invention is further elucidated.

In the drawing:

-figure 1 generally depicts the construction of the coupling device of the invention;

-figure 2 and figure 3 show a sectional view of one of the slanted or tapered support surfaces construed in accordance with the invention; and

-each of figures 4-7 provides a frontal view of respective exemplary embodiments of the slanted or tapered sup- port surfaces construed in accordance with the invention.

Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

Turning first to figure 1 the coupling device 1 of the invention is shown in a longitudinal sectional view. This coupling device 1 for tube 10 comprises a sleeve part 2 with an insert end 3 for the tube 10 and pressure elements 4 for exerting a clamping force on the tube 10.

The pressure elements 4 have radially converging sur- faces 5, 6 that radially converge towards each other in a direction away from the longitudinal axis 11 of the device. The sleeve part 2 on the other hand has tapering support surfaces 7, 8 that cooperate which said radially converging surfaces 5, 6 of the pressure elements 4 for pressing the pressure ele- ments 4 towards the tube 10. A sealing ring 9 is applied to provide a seal around the tube 10, of which sealing ring 9 at least a first portion 9' is placed between the tube 10 and the pressure elements 4 and at least a second portion 9' ' is placed between the pressure elements 4 and at least one se- iected tapering support surface 8 of the said tapering support surfaces 7, 8 of the sleeve part 1.

Turning now also to figures 2 and 3, the said selected tapering or slanted support surface 8 of the sleeve part 1 is provided with irregularities 12 so as to counter movement of the second portion 9' ' of the sealing ring 9 relative to this selected tapering support surface 8.

The figures 4-7 shows several possibilities of implementing the irregularities 12, each case showing that the irregularities 12 on the slanted or tapering support surface 8 are provided as protruding ridges extending from the selected tapering support surface 8.

Figures 4 and 7 provide a frontal view showing that the said irregularities 12 on the selected tapering support surface 8 are provided as concentric ridges relative to the longitudinal axis 11 of the device. In figure 4 the concentric ridges 12 are uninterrupted. In figure 5 the concentric ridges 12 are interrupted.

Figure 6 shows the option that the irregularities 12 exhibit the shape of a Belgian waffle. Figure 5 still shows another possible embodiment. The examples shown in the figures 4-7 all relate to irregularities that are shaped symmetrically. It is however also feasible to shape the irregularities asymmetricall .

The above given explanation with reference to the coupling device according to the invention is to be understood as non-limiting with regard to the protective scope due the invention as specified in the appended claims.