Pipe joints or couplings – With fluid pressure seal – Expansible internal sleeve-type gasket
Patent
1985-10-30
1987-08-11
Scanlan, Jr., Richard J.
Pipe joints or couplings
With fluid pressure seal
Expansible internal sleeve-type gasket
285235, 285236, 285370, 285397, F16L 3316
Patent
active
046857044
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a cuff for sealing joints of pipes, adhering inside at the two ends of pipes by a plurality of annular ribs, formed in one piece with the rest of the cuff, made of elastic material and which is pressed outwardly by expanding collars on its inner side in the region of the annular ribs.
Preferably the pipes are passable.
At known cuffs of this kind (GB-PS No. 20 38 976, GB-PS No. 12 00 225) the profile of the ribs in the cross-section and in an unloaded state describes a steady curve curved away from the pipe wall to the center of the curve. If one inserts the cuff loosely into the pipes (in order to press it afterwards against the pipes by means of the expanding collars) the upper part of the cuff must be held in place since on the other hand it would collapse. This also applies if it had been pressed before by hand towards the pipe wall.
It is the task of the invention to develop the cuff mentioned above in a way that it keeps its required position after it has been inserted loosely into the pipes and pressed against the pipe wall by hand.
According to the invention this task is solved in that in its unloaded state the profile of the annular ribs forms in cross-section two curvatures towards the pipe wall.
If such a cuff is put into the pipes and is pressed by hand against the pipe walls, it keeps its position due to the fact that the annular ribs adhere to the pipe wall (which has been smoothed by grinding in the region of the sealing) by sucking:
During the pressing process the two curvatures allow some air to escape from the space between them. If subsequently the cuff is released in this space there originates a certain vacuum which holds the cuff. This is different in the known case. Here the air cushion between the pipe wall and rib is larger than in the present case. Thus it can be compared with a soft or elastic spring. In consequence the annular ribs can move easier at a change of force for instance in case that they are left alone after a first pressing than in the case according to the invention. Such movements, however, lead to a shifting with the consequence that air can enter into the hollow space. The vacuum which exists there first is being reduced and the cuff cannot be kept in place.
A further advantage is that the cuff according to the invention has a better sealing effect than the known one: At pressure by the expanding collars the pre-curved regions of the ribs are pressed into the finest grooves and recesses of the pipe wall, in fact deeper and over a larger area than in the known case the corresponding rib surfaces, this for the following reason: As against the known solution the areas of the ribs that first meet the pipe wall cannot evade laterally.
A further development of the invention consists therein that the annular ribs in their unloaded state have such a distance from each other that they do not touch each other in the loaded state. This further improves the sealing effect.
It is further expedient according to the invention that on both sides of the annular ribs with two curvatures there is located one ring rib each, the surface orientated towards the pipe wall of which forms a curve in cross-section, which is a straight line or approximately a straight line.
It is advantageous if this curve in the unloaded state of the cuff extends in oblique direction from the pipe wall, starting from its end facing the other annular ribs.
It is exteremely advantageous however if this curve in the unloaded state of the cuff, starting from the end facing the other ring ribs, extends in oblique direction towards the pipe wall.
It is also advantageous if in the unloaded state of the cuff the flanks of the outer ring ribs extend parallely and obliquely to the pipe wall and to the other ribs.
A further development of the invention consists therein that the flanks of the outer ring ribs facing the other ribs are located in the height of the edges of the expanding collar. If the expanding collar is being pressed onto the cuff and the cuff is thus being pressed against the
REFERENCES:
patent: 3521913 (1970-07-01), Verhein et al.
patent: 3558164 (1971-01-01), Havell
patent: 4346922 (1982-08-01), Ohtsuga et al.
patent: 4426106 (1984-01-01), McCoy
Scanlan, Jr. Richard J.
Steinburg Aktiengesellschaft
Stone Mark P.
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