SEALING RING FOR USE IN A PIPE COUPLING

Abstract: Sealing ring of an elastic material, for use in a pipe coupling in which the ring is placed in a radially inward open peripheral groove and is retained in said groove by means of a supporting ring(6) which sealing ring in each radial cross-section is the shape of an inwardly open, essentially rectangular trough with a circular bottom (2), a projecting lip (8) being provided which runs inwards at an angle from the end of the first circumferential wall of the trough, the free end of which lip lies at a radial distance from the axis of symmetry of the ring which is smaller than the external radius of the push-in end part of a pipe to be coupled and at the end of the second side wall of the trough, the free end of which lip lies at a greater distance from the above-mentioned axis than the free end of the first lip, the second lip being provided with a run-on face (10) which runs from a point near the bottom of the lip in the direction of said axis to an end point which lies at a distance from said axis which is smaller than the distance between the axis and the free end of the second lip, while the trough is of a depth which is greater than the radial thickness of the supporting ring, so that in the fitted state and with a push-in end part pushed through the ring an open space (14) is present between the supporting ring and the outward facing faces of the first and second lip.

Description: The invention relates to a sealing ring of an elastic material, for example a rubber, for use in a pipe coupling in which the ring is placed in a radially inwardly open peripheral groove at the receiving end part of a pipe and is retained in said groove by means of a supporting ring, so that the ring can form a seal between the inside of said pipe and the external periphery of the push-in end part of a second pipe pushed into the ring, and in the fitted and coupled state the axis of symmetry lying at right angles to the plane of the ring coincides with the central axes of the pipe openings of the coupled pipes, which sealing ring in each radial cross-section is the shape of an inwardly open, essentially rectangular trough with a bottom, in which the supporting ring can be accommodated in such a way that it rests against the bottom, a projecting lip being provided which runs inwards at an angle from the end of a first circumferential end wall of the trough, which wall forms the outer wall in fitted state of the sealing ring, the free end of which lip lies at a radial distance from the above-mentioned axis of symmetry of the ring which is smaller than the external radius of the push-in end part of a pipe to be coupled. Such a sealing ring is disclosed in GB-A-2052661 Sealing rings of the above-mentioned type are used particularly for the coupling of sewer pipes, or in general pipes for the discharge of effluent, which are dug in to below ground level and can therefore lie below groundwater level, so that the sealing rings have to be capable of sealing not only relative to an internal, but also relative to an external excess pressure. In the case of the known sealing ring, when the push-in end part of a pipe is being inserted into the ring the single lip present there is pressed against the supporting ring, so that said lip is compressed between the external surface of the push-in end part and the supporting ring. The disadvantage of the known sealing ring is that in order to bring about the coupling between two pipes in which the push-in end part of one pipe must be pushed through the sealing ring fitted in the other pipe great axially directed forces must be exerted, which makes the production of the pipe coupling unacceptably difficult. Besides, in the coupling which has been made the seal relative to an external excess pressure leaves something to be desired. The object of the invention is to provide an improved sealing ring of the above-mentioned type which does not have these disadvantages. This object is achieved by the features of the characterising part of claim 1. In a sealing ring designed in this way, when fitted and during the insertion of a push-in end part, the first lip is pressed only slightly outwards, so that the inward facing surface thereof nestles against the external surface of the push-in end part, which movement of the first lip requires the exertion of only a relatively slight axially directed force, while on further insertion of the push-in end part this part comes up against the run-on face, as a result of which the second lip is swung inwards and is thereby pressed against the external surface of the push-in end part, which movement also requires only a relatively slight axial force. If an external excess pressure now occurs as a result of the groundwater, then this water will possibly be able to penetrate between the push-in end part and the first lip resting against it until it is in the above-mentioned open space, but then, as said excess pressure increases, will press the second lip more forcefully against the push-in end part, so that said water cannot flow into the sewer pipe. On the occurrence of an internal excess pressure, sewer water may be able to penetrate between the push-in end part and the second lip lying against it until it reaches the above-mentioned open space, but this will cause the first lip to be pressed more forcefully against the push-in end part, as said excess pressure increases, so that the sewer water cannot flow outwards out of the sewer pipe. A step is advantageously formed in the part of the trough adjacent one of its walls, so that a bottom part is present, lying a shorter distance from the axis of symmetry than the remainder of the bottom part, while the supporting ring rests against this remaining bottom part, with the result that the entire part of the sealing ring lying adjacent the supporting ring is more flexible. A circular groove is preferably provided in the external face of the second wall of the trough, so that the second lip is formed on a thinned wall part of the trough. In this way the hinged action of the fixing of the second lip is improved. The invention is explained in greater detail with reference to the example of an embodiment shown in the drawing, in which: Figure 1 shows a sealing ring according to the invention, when fitted; and Figure 2 shows the sealing ring of Figure 1 with a push-in end part pushed through it. As shown in the drawing, the sealing ring 1 according to the invention is in each radial cross-section the shape of a trough with a circular, bottom 2 and two side walls 3 and 4. The ring 1 is accommodated in a peripheral groove 5 which is formed at the sleeve-shaped receiving end part of a pipe 5', the ring 1 being held fast by means of a supporting ring 6. Sawtooth-shaped projections 7 are provided in the external surface of the bottom 2, for the purpose of obtaining a good seal between the ring 1 and the internal surface of the peripheral groove 5. A first inward slanting lip 8 is formed at the free end of the wall 3, and a second slanting lip 9 is formed at the free end of the wall 4. The external surface of the lip 9 merges into a run-on face 10, which in turn merges into an outward slanting face 11. A circular groove 12 is formed in the external surface of the wall 4, so that the lip 9 is connected by means of a thinned wall part to the remaining part of the wall 4. An inward facing step 13 is formed in the bottom 2, so that the supporting ring 6 is accommodated only in the part of the bottom 2 lying adjacent said step 13. As shown in Figure 2, when a push-in end part 15 of a second pipe is being pushed through the sealing ring 1, from the right in the drawing, the lip 8 is first pressed outwards and the inward facing surface of said lip nestles against the external surface of the push-in end part 15, following which, on further pushing in of the push-in end part, this part slides along the lip 9 and then goes against the run-on face 10, as a result of which the lip 9 is swung inwards about a hinge pin which is determined by the groove 12. In this way, in the coupled position shown in Figure 2, an open space 14 is formed between the supporting ring 6 and the outward facing faces of the lips 8 and 9. If an external excess pressure now occurs, as a result of groundwater, then this water will possibly be able to penetrate between the push-in end part 15 and the first lip 8 lying against it, in the direction of the arrow A, until it reaches the open space 14, but then, as this excess pressure increases, the lip 9 will be pressed more forcefully against the push-in end part 15, so that this water cannot flow into the sewer pipe. If, on the other hand, an internal excess pressure occurs, then sewer water will possibly be able to penetrate between the push-in end part 15 and the lip 9 resting against it, in the direction of the arrow B, until it reaches the open space 14, but as a result the lip 8 will be pressed more forcefully against the push-in end part 15 as said excess pressure increases, so that the sewer water cannot flow out of the sewer pipe to the outside.

Claims: Sealing ring (1) of an elastic material, for example a rubber, for use in a pipe coupling in which the ring is placed in a radially inward open peripheral groove at the receiving end part of a pipe and is retained in said groove by means of a supporting ring (6), so that the ring (1) can form a seal between the inside of said pipe and the external periphery of the push-in end part of a second pipe pushed into the ring, and in the fitted and coupled state the axis of symmetry lying at right angles to the plane of the ring coincides with the central axes of the pipe openings of the coupled pipes, which sealing ring in each radial cross-section is the shape of an inwardly open, essentially rectangular trough with a bottom (2), in which the supporting ring (6) can be accommodated in such a way that it rests against the bottom (2), a projecting lip (8) being provided which runs inwards at an angle from the end of a first circumferential end wall (3) of the trough, which wall forms the outer wall in fitted state of the sealing ring, the free end of which lip lies at a radial distance from the above-mentioned axis of the ring, characterized in that a second lip (9) projecting obliquely inward towards the first lip (8) is formed at the end of the second or inner side wall (4) of the trough, the free end of which second lip (9) lies at a greater distance from the above-mentioned axis of symmetry of the ring than the free end of the first lip, the second lip having an external surface which merges into a run-on face (10) on a further lip (11), said face running from a point near the bottom of the second lip in a direction towards said axis to a terminal end point which lies at a distance from said axis which is smaller than the distance between the axis and the free end of the second lip, while the trough is of a depth which is greater than the radial thickness of the supporting ring, so that in the fitted state and with a push-in end part pushed through the ring an open space is present between the supporting ring and the outward facing faces of the first and second lip. Sealing ring according to claim 1, characterized in that a circular groove (12) is provided in the external face of the second wall (4) of the trough, so that the second lip (9) is formed on a thinned wall part of the trough. Sealing ring according to claim 1 or 2, characterized in that a step (13) is formed in the part of the trough adjacent one of its walls (3;4), so that a bottom part is present, lying a shorter distance from the axis than the remainder of the bottom part, while the supporting ring rests against this remaining bottom part.

Inventors: LEEUWENBURG, EWOUT, VAN KOOIJ, ROBERT JUSTUS
Applicants: NYLOPLAST EUROPE B.V.
Application year: 1991
Main classification: F16L17
IPC codes: F16L21, F16L47, F16L17