Tube seal

Abstract

A tube seal (1) having a longitudinal axis (A) and a first open end (10a) and a second open end (10b) configured to fluidically connect and seal a first and a second tube (2a, 2b) said tube seal (1) comprising an outer rigid sleeve portion (3) defining an inner sleeve surface (30) between the first end (10a) and the second end (10b), and an inner tube-like sealing body (4) of elastomeric material attached to the inner sleeve surface (30) of the sleeve portion (3) and comprising a circumferential inner sealing bead (41a, 41b) at each end (10a, 10b) of the tube seal (1); wherein the outer rigid sleeve portion (3) comprises an inner circumferential rib (31) protruding from the inner sleeve surface (30), and wherein the inner sealing body (4) comprises a first section (42a) and a second section (42b) extending along the longitudinal axis (A) of the tube seal (1) on both sides of the inner circumferential rib (31) and covering the entire inner surface (30) of the sleeve portion (3), and wherein the inner circumferential rib (30) radially extends over an inner surface (40) of the sealing body (4).

Description

[0001] Tube seal

[0002] Technical Field

[0003] The invention relates to a tube seal having a longitudinal axis and a first open end and a second open end configured to fluidically connect and seal a first and a second tube or conduit.

[0004] Technical Background

[0005] Tube seals for connecting and sealing ends of two tubes or conduits are known mainly in two variants, either with a sealing function on an outer surface of the tube seal or a sealing function on the inner side of the tube seal.

[0006] WO14148992 A1 discloses a tube seal for sealingly connecting two pipe sections. The tube seal is designed with a sleeve portion and an element of elastic material mounted inside the sleeve. The elastic element comprises a flange portion to abut the two pipe sections.

[0007] Over time and upon movement or vibration of the pipe sections the connection between the sleeve and the elastic element may loosen and the sleeve may move away from the elastic element leading to failure of the seal. The flange portion may also wear off due to the sharp edges of the pipe ends. And, due to the flexibility of the flange the entire tube seal may be mispositioned with respect to the tube ends.

[0008] GB904622 shows a tube seal with a support tube having an inner sealing element including a flange portion. The inner sealing element is positioned in annular recesses of the support tube to avoid axial relative movement. Such a design of the support tube is very complex to manufacture and therefore leads to high manufacturing costs. In addition, the inner flange is also subject to increased wear off. And, due to the flexibility of the flange the entire tube seal may be mispositioned with respect to the tube ends.

[0009] FR1534902 discloses a tube seal with an outer supporting tube and two inner sealing rings (O-rings) arranged in a groove. The rigid tube comprises a central, inner and circumferential rib, which protrudes radially over the sealing element and acts as a positioning ring when the seal is placed onto the two free tube ends to be sealed. Because the O-rings are accommodated in a groove the tube seal can hardly compensate for misalignment to the tube end to be sealed. Summary of the Invention

[0010] It is an objective of the invention to avoid at least some of the problems of the known tube seals. It is another objective to provide a tube seal, which is able to connect two free tube ends in sealing manner even when the tube ends are misaligned. Such misalignment may occur in a sealing assembly by lateral or angular misalignment of the tube ends. It is another objective to provide a tube seal with high sealing reliability, which allows cost efficient manufacturing.

[0011] At least one of the objectives is achieved by a tube seal according to claim 1. The seal having a longitudinal axis and a first open end and a second open end configured to fluidically connect and seal a first and a second tube or conduit comprises: an outer rigid sleeve portion defining an inner sleeve surface between the first end and the second end, and an inner tube-like sealing body of elastomeric material attached to the inner sleeve surface of the sleeve portion and comprising a circumferential inner sealing bead at each end of the tube seal. The outer rigid sleeve portion comprises an inner circumferential or annular rib protruding from the inner sleeve surface. The inner sealing body comprises a first section and a second section extending along the longitudinal axis of the tube seal on both sides of the inner circumferential rib and covering the entire inner surface of the sleeve portion. The inner circumferential rib radially extends over an inner surface of the sealing body (i.e. it is not covered by the elastomeric material).

[0012] Typically, the inner circumferential rib is centred between the first end and the second end of the tube seal and functions as a retention rib, when the tube seal is positioned on the first tube end and the second tube end. Therefore, the inner diameter of the rib may be chosen slightly smaller than the outer diameter of the tubes to be sealed. Misplacement of the tube seal over only one end is thereby avoided. Furthermore, the tube seal cannot wander off one of the tube ends and wear off of the inner rib is also greatly reduced, because the inner rib is free of elastomeric material.

[0013] The actual sealing occurs at the annular sealing beads radially extending inwards. However, the inner tube-like elastomeric sealing body covers the entire inner surface of the sleeve between the first end and the second end, thereby providing enough room for the tube ends even upon misalignment of the tube ends with respect to each other. The tube seal may compensate a later misalignment of up to 10 % of the outer tube diameter or an angular misalignment of up to 2 degrees.

[0014] The tube seal may be tilted with respect to the tube end while proper sealing is maintained. Further embodiments of the invention are set forth in the dependent claims.

[0015] In some embodiments the inner circumferential rib radially extends also over the inner sealing beads.

[0016] In some embodiments the rigid sleeve and the sealing body may be directly chemically bonded or chemically bonded by using an adhesive. The chemical bonding leads to a very strong connection of the two parts to avoid any delamination.

[0017] In some embodiments the circumferential rib may comprise at least one opening and the first and second section of the inner sealing body are connected via the at least one opening.

[0018] In some embodiments the rigid sleeve, which may be formed in one piece, and / or the elastomeric sealing body may be injection moulded. The injection moulding may be performed by first moulding the rigid sleeve and secondly over-moulding the rigid sleeve with the elastomeric sealing body. The process may be performed in separate moulding tools or within the same moulding tool. The rigid sleeve and the elastomeric sealing body may be injection moulded with one injection point each arranged on opposite sides in axial direction of the tube seal.

[0019] The at least one opening in the circumferential rib may allow injection moulding the elastomeric sealing body from one side of the tube seal only and thereby simplifying the manufacturing process.

[0020] In some embodiments the rigid sleeve portion at each end may comprise an inner annular shoulder. Thereby the inner diameter of the tube seal at its ends can be enlarged to avoid contact of the connecting tubes with an edge of the tube seal when the tube seal is tilted due to misalignment of the connecting tubes (lateral and / or angular). Also, the end face of the elastomeric sealing body may be enlarged to provide sufficient space for an injection point when injection moulding the elastomeric sealing element.

[0021] In some embodiments the inner diameter of the elastomeric sealing body between the sealing bead and the circumferential rib may be smaller than the inner diameter at both ends of the elastomeric sealing body.

[0022] In some embodiments the rigid sleeve portion may be made of thermoplastic material having good bonding behaviour with the material of the elastomeric sealing body. Preferably, the thermoplastic material has also good resistance properties with respect to the fluid conducted by the sealing assembly. Good results may be achieved withpolybutylene terephtalate (PBT), polyamide (PA) or polyphenylene sulfide (PPS). In some embodiments the elastomeric material of the elastomeric sealing body may be liquid silicone rubber (LSR). The LSR may be of self-adhesive type to avoid delamination between sleeve and sealing body upon de-moulding the tube seal. The adhesion must be strong enough to counteract the pulling forces on the sealing body due to an undercut in the mould for the sealing beads. The LSR may have a 60 shore A hardness.

[0023] In some embodiments the rigid sleeve portion may comprise at one end an outer circumferential flange. Separate or in combination, the rigid sleeve portion may comprise an inner circumferential groove. The groove may be arranged near the outer circumferential flange. These features facilitate the injection moulding process by allowing retention in a specified mould half and facilitating demoulding / ejecting of the final product.

[0024] In some embodiments the rigid sleeve portion may comprise an annular depression in its outer surface to facilitate automatization processes when assembling the tube seal to the connecting tube ends.

[0025] The invention further relates to a sealing assembly comprising a tube seal as described above and two tubes or conduits sealingly connected at respective tube or conduit ends via the tube seal.

[0026] In some embodiments the tube ends may be tapered and have decreasing outer diameter towards the ends.

[0027] In some embodiments the inner circumferential rib may have a smaller inner diameter than the outer diameter of the connecting tubes. Thereby the connecting tubes abut at the inner circumferential rib when the sealing assembly is assembled, facilitating correct positioning of the tube seal.

[0028] Brief Explanation of the Figures

[0029] The invention is described in greater detail below with reference to embodiments that are illustrated in the figures. The figures show:

[0030] Fig. 1 a side view of a sealing assembly comprising a tube seal mounted on connecting tubes;

[0031] Fig. 2 a perspective view onto a first open end of the tube seal of Fig. 1 ;

[0032] Fig. 3 a perspective view onto a second open end of the tube seal of Fig. 1 ;

[0033] Fig. 4 a sectional view of the tube seal of Fig. 1 ; Fig. 5 a sectional view of the tube seal of Fig. 1 under (a) including aligned connecting tubes and under (b) including mis-aligned connecting tubes;

[0034] Fig. 6 a perspective view of the rigid sleeve;

[0035] Fig. 7 a sectional view of the rigid sleeve.

[0036] Embodiments of the Invention

[0037] Fig. 1 shows a side view of a sealing assembly comprising a tube seal 1 mounted on tube ends of a first and second tube 2a, 2b to be connected in sealing manner. Fig. 2 and Fig. 3 show the tube seal of Fig. 1 in a perspective view onto a first open end 10a and a second open end 10b, respectively.

[0038] The tube seal 1 comprises a rigid sleeve portion 3 made e.g. of polybutylene terephtalate (PBT) and an elastomeric inner sealing body 4 made e.g. of liquid silicone rubber (LSR). The rigid sleeve 3 comprises a central, inner and circumferential rib 31, which protrudes radially over the sealing body 4 and acts as a positioning or retaining ring when the tube seal is placed onto the two free tube ends 2a, 2b to be sealed. Thereby an axial misalignment along a longitudinal axis A of the tube seal 1 relative to the two tube ends 2a, 2b is avoided. The elastomeric inner sealing body 4 covers and is chemically bonded with the entire inner surface 30 of the rigid sleeve 3 except for the part of the circumferential inner rib 31 extending over the inner surface 40 of the elastomeric sealing body 4.

[0039] The sealing body 4 extends on both sides of the circumferential rib 31 and aligns with both ends 10a, 10b of the rigid sleeve. The sealing body 4 further comprises at each axial ends a circumferential inner sealing bead 41a, 41b providing the actual sealing surface towards the tube ends 2a, 2b to be sealed. Thus, the circumferential rib 31 divides the elastomeric sealing body 4 into a first and second section 42a, 42b.

[0040] The faces of the circumferential inner sealing beads 41a, 41b may be formed with different angles. The outer face may have a steeper angle than the inner face towards the circumferential rib 31.

[0041] Fig. 4 shows a sectional view of the tube seal of Fig. 1. As can be clearly seen, the rigid sleeve portion is formed as one piece. Fig. 5 shows a sectional view of the tube seal of Fig. 1 in a sealing assembly under (a) including aligned connecting tubes and under (b) including mis-aligned connecting tubes. The rigid sleeve 3 as shown in the figures comprises at both ends an inner annular shoulder 32a, 32b. Thereby the elastomeric body 4 extending to both ends 10a, 10b of the tube seal 1 may have an increased inner diameter as compared to the portion between the sealing beads 41a, 41b and the central rib 31. With the enlarged inner diameter at the ends 10a, 10b a contact between the edge of the tube seal 1 and the connecting tubes 2a, 2b may be avoided when the tube ends 2a, 2b are laterally misaligned (see Fig. 5b) or angularly misaligned, while maintaining proper sealing of the sealing beads 41a, 41b towards the tube ends 2a, 2b.

[0042] The inner diameter of the circumferential rib 31 may be adjusted to allow an edge of the tube ends 2a, 2b to extend over the circumferential rib 31 in a lateral or angular misaligned configuration of the sealing assembly (see Fig. 5b). Therefore, the tube ends 2a, 2b may also be tapered.

[0043] Fig. 6 shows a perspective view of the rigid sleeve 3. Fig. 7 shows a sectional view of the rigid sleeve 3.

[0044] The rigid sleeve 3 may comprise at least one opening 33 (see Fig. 6) in the circumferential rib 31 located adjacent to the inner surface 30 of the rigid sleeve 3 and having a maximal size in radial direction not more than the thickness of the elastomeric sealing body 4 near the circumferential rib 31. The two sections 42a, 42b of the elastomeric sealing body 4 are connected with each other via this opening 33.

[0045] The tube seal 1 may be manufactured by injection moulding. The rigid sleeve 3 may be over-moulded with the elastomeric sealing body 4 using a single injection point 43 (see Fig. 2). Due to the opening 33 the material for the elastomeric sealing body may flow across the circumferential rib 31 and form both sections 42a, 42b of the elastomeric sealing body 4.

[0046] The rigid sleeve 3 may further comprise an outer circumferential flange 35 and an inner circumferential groove 36 (see e.g. Fig. 7). These features optimize the manufacturing process by facilitating the retention of the rigid sleeve 3 in a desired mould half and the ejection of the final tube seal 1 after over-moulding the rigid sleeve 3 with the elastomeric sealing body 4.

[0047] The rigid sleeve 3 may further comprise an annular depression 37 on its outer surface 38. The annular depression 37 may form a defined gripping area for automatic robotic assembling of the sealing assembly or for external fixation of the tube seal 1 in the sealing assembly e.g. with a retaining clamp. Reference Signs

[0048] 1 tube seal

[0049] 10a first open end

[0050] 10b second open end

[0051] 2a first tube / tube end

[0052] 2b second tube / tube end

[0053] 3 outer rigid sleeve portion

[0054] 30 inner sleeve surface

[0055] 31 inner circumferential rib

[0056] 32a, 32b inner annular shoulder

[0057] 33 opening

[0058] 35 outer circumferential flange

[0059] 36 inner circumferential groove

[0060] 37 annular depression

[0061] 38 outer surface

[0062] 4 inner tube-like sealing body

[0063] 40 inner surface of sealing body

[0064] 41a, 41b circumferential inner sealing bead

[0065] 42a first section of sealing body

[0066] 42b second section of sealing body

[0067] 43 injection point / mark

[0068] A longitudinal axis

Claims

Claims1. Tube seal (1) having a longitudinal axis (A) and a first open end (10a) and a second open end (10b) configured to fluidically connect and seal a first and a second tube (2a, 2b), said tube seal (1) comprising an outer rigid sleeve portion (3) defining an inner sleeve surface (30) between the first end (10a) and the second end (10b), and an inner tube-like sealing body (4) of elastomeric material attached to the inner sleeve surface (30) of the sleeve portion (3) and comprising a circumferential inner sealing bead (41a, 41b) at each end (10a, 10b) of the tube seal (1); characterized in that the outer rigid sleeve portion (3) comprises an inner circumferential rib (31) protruding from the inner sleeve surface (30), and in that the inner sealing body (4) comprises a first section (42a) and a second section (42b) extending along the longitudinal axis (A) of the tube seal (1) on both sides of the inner circumferential rib (31) and covering the entire inner surface (30) of the sleeve portion (3), and wherein the inner circumferential rib (30) radially extends over an inner surface (40) of the sealing body (4).

2. Tube seal according to claim 1, wherein the inner circumferential rib (30) radially extends over the inner sealing beads (41a, 41b).

3. Tube seal according to one of the preceding claims, wherein the rigid sleeve (3) and the sealing body (4) are chemically bonded.

4. Tube seal according to one of the preceding claims, wherein the circumferential rib (31) comprises at least one opening (33) and the first and second section (42a, 42b) of the inner sealing body (4) are connected via the at least one opening (33).

5. Tube seal according to one of the preceding claims, wherein the rigid sleeve (3) and / or the elastomeric sealing body (4) are injection moulded.

6. Tube seal according to claim 5, wherein the rigid sleeve (3) and the elastomeric sealing body (4) are injection moulded with one injection point (43) each arranged on opposite sides in axial direction (A).

7. Tube seal according to one of the preceding claims, wherein the rigid sleeve portion (3) at each end comprises an inner annular shoulder (32a, 32b).

8. Tube seal according to one of the preceding claims, wherein the inner diameter of the elastomeric sealing body (4) between the sealing bead (41a, 41b) and the circumferential rib (31) is smaller than the inner diameter at both ends (10a, 10b) of the elastomeric sealing body (4).

9. Tube seal according to one of the preceding claims, wherein the rigid sleeve portion (3) is made of thermoplastic material and / or the elastomeric material of the elastomeric sealing body (4) is liquid silicone rubber (LSR).

10. Tube seal according to one of the preceding claims, wherein the rigid sleeve portion (3) at one end comprises an outer circumferential flange (35).

11. Tube seal according to one of the preceding claims, wherein the rigid sleeve portion (3) comprises an inner circumferential groove (36).

12. Tube seal according to one of the preceding claims, wherein the rigid sleeve portion (3) comprises an annular depression (37) in its outer surface (38).

13. Sealing assembly comprising a tube seal (1) according to one of the preceding claims and two tubes (2a, 2b) sealingly connected at respective tube ends via the tube seal (1).

14. Sealing assembly according to claim 13, wherein the tube ends are tapered and have decreasing outer diameter towards the end.

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