MEANS FOR SEALING THE GAP BETWEEN TWO AXIALLY DISPLACEABLE SEALING SURFACES

Abstract: An annular gasket of a soft elastic material is fixed in a groove in a socket (14) which is to receive a pipe end (9). Attached to the annular leading edge (A) of the main gasket body relative to the pipe end (9) is a closed, annular hollow jacket (22) which during insertion of the pipe end (9) is entrained so as to form a double layer over the adjacent surface (4) of the main gasket body, the surface (4) being presented to the pipe end (9) by a sliding part (2) of the main gasket body. When fully inserted, the pipe end (9) compresses the main gasket body between the double layer formed by the jacket (22) and the socket (14).

Description: The present invention relates to a gasket of elastic resilient material having a substantially uniform cross-section for sealing a gap between two elements having sealing surfaces which are substantially uniformly spaced. The gasket according to the invention is of a type comprising a sealing body adapted to be stationary with respect to one of the sealing surfaces during assembly where relative movement of the elements is provided in a direction substantially parallel to the sealing surfaces and transverse to the longitudinal direction of the gasket, and further comprising a hollow jacket defined by a wall having reduced thickness in relation to the sealing body and forming a closed cavity having lubricated surfaces, the hollow jacket being connected with the forward end of the sealing body and being wholly positioned in fornt of the sealing body in the starting position for the assembly by relative movement of the elements, the hollow jacket being adapted at the assembly to roll from the position in front of the sealing body in a manner similar to a caterpillar belt to a position in which the hollow jacket is at least partially positioned between the sealing body and the opposite sealing surface. W0-A-8103214 discloses a gasket of the above type for pipes having a spigot and a socket end. The gasket comprises a compression member and a surrounding hose. Part of this hose is stationary with respect to the spigot end by being held thereon by the compression member. The remaining part of the hose will move together with the socket end of another pipe while sliding over the compression member. A secondary compression member may be provided outside the hose, and the part of the hose sliding over the main compression member will form a double layer over the secondary compression member, the outer layer of said double layer sliding relatively to the inner layer thereof. An object of the invention is to provide an improved gasket of the kind described above. In order to comply with this object there is according to the invention provided a gasket which is characterized in that the hollow jacket defines an empty cavity which is adapted to be flattened with two opposite inner surfaces of said wall contacting each other essentially along their entire length during assembly and in the assembled position in which the jacket is at least partially positioned between the sealing body and the opposite sealing surface. The invention will be further described in the following in conjunction with the drawing figures which illustrate a conventional gasket as well as embodiments of the gasket according to the present invention. Figures 1a and 1b illustrate an embodiment of a known annular gasket according to a previous development leading to the present invention, said gasket being adapted for use on the bottom ring of a mold so as to be positioned in a groove in the socket end of the molded pipe. Figures 2 and 3 illustrate an embodiment of a gasket according to the present invention, Figure 2 depicting the gasket in a position prior to the assembly of the elements, and Figure 3 depicting the gasket after the assembly of, the elements. Figure 4 illustrates a modification of the embodiment according to Figures 2 and 3. Shown in Figures 1a and 1b is a gasket of a previously known type for example as disclosed in US-A-4,299,399. The gasket comprises a first gasket portion or sealing body 19 and a second gasket portion in the shape of a jacket 18. The gasket is mounted on a bottom ring 16 constituting a part of a mold for a concrete pipe of which only the lower or socket end 14 is illustrated and with which the gasket is to be used. The gasket is mounted on the bottom ring 16 with the jacket 18 facing the ring. After curing of the concrete the ring 16 is removed from the socket 14, whereby the compression of the gasket is released, the gasket taking a shape which is shown in Figure 1b and which is suitable for the introduction of a spigot end 9 of another pipe in the socket 14. To make the gasket protrude into the cavity of the socket when the ring 16 has been removed, it is compressed onto the bottom ring 16. The compression is obtained by means of a non-stretchable hoop 17. The use of the known sliding type jacket 18 illustrated in Figures 1a and 1b requires a lubricant to be supplied to the closed cavity defined between the first gasket portion and the sliding jacket 18. During the assembly of the pipe elements 14 and 9, the jacket 18 will slide along the surface 19a of the first gasket portion 19 facing the jacket and enter the gap 20 between the pipes axially inside the first gasket portion 19, forming therein a double buffer layer preventing contact between the coaxial surfaces of the spigot end and the socket. The invention will now be described with reference to Figures 2 and 4. In particular, Figure 2 illustrates a gasket 2 having a sealing body 19 of Z-shaped cross-section and a reinforcement hoop or ring 17. The gasket also includes a hollow jacket 22 having a cross-section of closed annular shape. This jacket will in the following be referred to merely as being "hollow", which is meant to imply that it surrounds a cavity by being of closed annular cross-sectional shape, said cavity being "empty" to allow the jacket to be flattened with its inner walls contacting each other. The jacket 22 has an increasing thickness, the thickest end being connected to the front edge A of the sealing body, similar to what is the case with respect to the gasket shown in Figures 1a and 1b. The other end of the wall of said jacket 22 is also connected to the front edge A of the sealing body, closely adjacent to, but radially inside said first end 5, and said other end is shaped so as to bulge inwardly as shown at 25. The smallest diameter 26 of the jacket 22 is less that the diameter of the spigot end 9 to be inserted in the socket 14. The jacket 22 flares forwardly and outwardly towards the socket opening. The inner surfaces of the walls of the jacket 22 are provided with locking ribs 29 and with a suitable lubricant. When a spigot end 9 (Figures 3 and 4) is pushed into the socket 14 and engages said jacket 22 at the bulge 25 thereof, said jacket 22 will be entrained by the pipe and will follow the movement thereof, while forming a double layer over the sealing body, the lubricated inner surfaces of the walls of the jacket 22 sliding along each other. The double layer jacket will roll into the gap between the pipe 9 and the sealing body 19, and in fact the jacket 22 behaves like a caterpillar belt rolling onto the sealing body 19. The total thickness of the material of the gasket and the compression thereof in the sealing gap between the pipe 9 and the socket 14, will then increase corresponding to twice the thickness of the jacket 22. By appropriate selection of the length of the walls of the jacket 22 viewed in cross-section and of the length of the assembly movement, buffer layers 30 and 31 can result which extend outside and inside the sealing area 32 defined by the sealing body 19 as shown in Figure 3. In addition, with this embodiment it is possible to avoid such buffer layers, if desirable, by making said walls sufficiently short to prevent the jacket 22 from rolling beyond the sealing body 19. The jacket 22 will then be positioned only across the sealing width 32 provided by the section of the first portion having the greatest thickness, and such a gasket can be used also with pipes providing too narrow or too short a gap axially inside the sealing body to accomodate said jacket. Such pipes and such gaskets are illustrated in Figure 4. Whereas in Figures 2 to 4 a hollow jacket performing a rolling movement has been shown in connection with a Z-shaped sealing body and in an embodiment intended for premounting in the socket end of the pipe, it should be understood that the invention is not limited to use with this type of sealing body and can, of course, be used in connection with any appropriate configuration of the sealing body as well as on gaskets intended for mounting on the spigot end of the pipe. For example, a hollow jacket 22 can be used to build up an increased thickness of the type of lamellae gasket which has been discussed with reference to Figures 1a and 1b. Again, the inner surfaces of the jacket 22 when flattened will slide relative to each other, a first layer of the jacket 22 adjacent to the sealing body 19 being stationary relative to the sealing body 19, whereas the layer in contact with the spigot end will slide along the first layer, the entire jacket 22 performing a rolling movement similar to a caterpillar belt rolling into the gap between the sealing body and one of the pipes (the spigot end in the embodiment shown in Figures 1a and 1b).

Claims: A gasket having a substantially uniform cross-sectional shape and comprising elastically resilient material for sealing a gap between two elements (9, 14) having sealing surfaces which are substantially uniformly spaced, the gasket comprising a sealing body (2) adapted to be stationary with respect to one of the sealing surfaces during assembly where relative movement of the elements (9, 14) occurs in a direction substantially parallel to the sealing surfaces and transverse to the longitudinal direction of the gasket, and further comprising a hollow jacket (22) defined by a wall having reduced thickness in relation to the sealing body (2) and forming a closed cavity having lubricated surfaces, the hollow jacket (22) being connected with the forward end (A) of the sealing body and being wholly positioned in front of the sealing body in the starting position for the assembly by relative movement of the elements (9, 14), the hollow jacket being adapted at the assembly to roll from the position in front of the sealing body in a manner similar to a caterpillar belt to a position in which the hollow jacket is at least partially positioned between the sealing body and the opposite sealing surface, characterized in that the hollow jacket (22) defines an empty cavity which is adapted to be flattened with two opposite inner surfaces of said wall contacting each other essentially along their entire length during assembly and in the assembled position in which the jacket is at least partially positioned between the sealing body and the opposite sealing surface. A gasket according to claim 1, characterized in that the cross-sectional shape of the hollow jacket (22) is adapted to provide that the jacket will be carried along by a sealing surface during assembly. A gasket according to claim 1 or 2, characterized in that the circumference of the cross-section of the hollow jacket (22) has a restricted length so as to prevent any substantial part of said jacket (22) from rolling past the said region of the sealing body (2) during assembly of the elements (9,14). A gasket according to claim 1 or 2, characterized in that the circumference of the cross-section of the hollow jacket (22) is of sufficient length either to leave a substantial part of said jacket (22) in front of the said region of the sealing body (2) when the elements (9, 14) are assembled, or to permit a substantial part of said jacket (22) to roll past the cross-section of the sealing body (2), thereby to form a supporting layer in front of an/or beyond the cross-section of the sealing body (2), said supporting layer preventing contact between the elements (9, 14) when subjected to transverse forces. A gasket according to any of the preceiding claims, characterized in that the gasket is annular and has a diameter adapted to fit into annular, generally coaxial sealing surfaces of two pipe elements (9, 14) A gasket according to claim 5, characterized in that said pipe elements (9, 14) have a spigot end and a socket end having exterior and interior sealing surfaces, respectively.

Inventors: HAALAND, PER
Applicants: FORSHEDA AB
Application year: 1984
Main classification: F16L17
IPC codes: B28B21, F16L17, F16L21, F16J15