GB2250557A

GB2250557A - Clamped hose to pipe connection with auxiliary sealant

Info

Publication number: GB2250557A
Application number: GB9122265A
Authority: GB
Inventors: Heinz Sauer
Original assignee: Rasmussen GmbH
Current assignee: Norma Germany GmbH
Priority date: 1990-12-07
Filing date: 1991-10-18
Publication date: 1992-06-10
Anticipated expiration: 2011-10-18
Also published as: JPH04290696A; ITTO910945A1; ITTO910945A0; FR2670267A1; CA2056583A1; GB2250557B; DE4039054C1; IT1250354B; FR2670267B1; GB9122265D0

Description

2 2-305 37 Hose-to-Pipe Connection and a Method of Making Such a

Connection pipe is The invention relates to a hose-to-pipe connection in which the provided with at least one retaining rib adjacent its end and the hose has an end portion which is pushed over the retaining rib and onto the pipe and is secured by a clip or the like which surrounds the hose behind the retaining rib. The invention also relates to a method of making such a connection.

In the case of a prior art hose-to-pipe connection of this type, in which the hose is of ethylene-propylene-terpolymer with a fabric interlining and the pipe is made of metal, the connection becomes unretentive particularly where there is a high internal pressure and the temperatures are far below freezing point. Investigations conducted over a wide range of temperatures and fluid pressures lead to the conclusion that with falling temperature the contraction of the hose material leads to a relaxation in the hose in the region between the clip and the pipe, i.e. the thickness of the hose material finally diminishes to such an extent that the hose material no longer exerts any counter-pressure on the clip. The clip therefore becomes ineffectual and although the hose grips more firmly around the pipe by virtue of its contraction, it is able nevertheless, with increasing fluid pressure in the hose - so long as its elasticity has not been adversely affected by the cooling - to widen out radially in the region of the clip so that the pressurised fluid is able to escape between the pipe and the hose. With increasing temperature, it is true that the hose material expands so that the hose material is subject to more intense pressure particularly in the region of the clip, because its volume increases, but the effect of high temperature, particularly of more than 900C, and a high clamping pressure, can result in a lasting deformation and therefore an impaired elasticity of the hose material with the result that also in the middle temperature range there is a reduction in the sealing-tightness of the joint.

According to the invention there is provided a hose-to-pipe connection in which the pipe is provided with at least one retaining rib adjacent its end and the hose has an end portion which is pushed over the retaining rib and onto the pipe and is secured by a clip or the like which surrounds the hose behind the retaining rib, wherein, between the hose and the pipe, at least in the region between the retaining rib and the clip, there is a sealing material which retains its sealing capacity over a temperature range of at least -400C to +1400C.

Thus, there is provided a hose-to-pipe connection of the type mentioned at the outset and also a method of making such a connection which ensures adequate sealing-tightness over wider ranges of temperatures and fluid pressures than have hitherto been possible.

With this solution, since the sealing material is also disposed axially outside the clamping range of or the region clamped by the clip, the sealing-tightness of the connection outside the clamping zone is independent of the clamping force exerted by the clip. Therefore, when the hose material contracts due to falling temperature, then even with increasing fluid pressure in the hose or pipe this can contribute to a sufficient sealing-tightness because by virtue of the sealing material altogether more material is available between the clip and the retaining rib. In the event of excessive heating, the connection still remains tight, because, in the clamping region of the clip, the hose material expands, so enlarging its volume and consequently increasing the clamping force; and because more material is available in the area between the clip and the retaining rib and this expands when heated and increases the sealing pressure in this zone.

Preferably, the sealing material is elastic. In the case of an increase in fluid pressure the elasticity constitutes an additional contribution to the sealing effect as the hose expands while the temperature remains the same, because the sealing material may possibly become elastically relaxed and so continue to fill the intermediate space between hose and pipe, particularly the intermediate space adjcent the root of the retaining rib, without any gap being created or remaining open.

Thus, it is possible to ensure that the sealing material does not adhere to the hose. If desired, then, once the clip has been undone, the hose can be withdrawn more readily from the pipe because the total available area for adhesion between hose and pipe, such as is frequently observed after a prolonged period, is correspondingly smaller.

If the sealing material is disposed in the total area located between the retaining rib and the hose end, no surface is left on the pipe to which the hose can adhere. Therefore, if required (and after the clip has been undone), the hose can be even more easily withdrawn from the pipe.

Furthermore, it is favourable for the sealing material to be an adhesive which only clings to the pipe. In this way, a still greater sealingtightness is assured because no pressurised fluid can escape at least between the pipe and the sealing material.

Preferably, it is envisaged that the sealing material be applied to the pipe while still in a viscous state, becoming locked onto the pipe as it hardens out. In this case, the sealing material applies itself particularly tightly to the pipe, also compensating for any surface roughness on the pipe such as burrs from mould removal, particularly in an axial direction. Therefore, there is no need for the surface of the pipe to be machined, particularly in order to remove burrs.

Additionally, provision can be made for the hose to consist of EPDM or silicone rubber, particularly with a fabric interlining, the pipe consisting of metal or synthetic plastics material, particularly polyamide, while the sealing material consists of synthetic rubber, particularly silicone rubber or fluoroelastomer. This results in a particularly favourable combination of materials for hose, sealing material and pipe.

According to the invention, a method of making the connection consists in the material, while a semi-fluid or viscous state, being applied in the form of an accumulation of material surrounding the pipe between the retaining rib and the clip clamping zone at least up to the radial height of the retaining rib and in the vicinity thereof, the hose being pushed over the retaining rib and the sealing material onto the pipe before the sealing material hardens out. With this method the still viscous sealing material facilitates pushing the hose onto the pipe. At the same time, the sealing material is distributed virtually over the entire length of the portion of hose disposed between the retaining rib and the pushed-on end of the hose without being pushed away for the most part in front of the hose end while this is being pushed onto the pipe.

Another method of making the connection may reside in that the sealing material is applied to the pipe in a shaping tool surrounding the pipe, and after the sealing material has hardened out, the hose is pushed onto the pipe. This makes it possible to pre-assemble the connection, e.g. if the pipe is a pipe socket which can only be attached on site.

There now follows a description of preferred ernbodiments of the invention, by way of example, with reference being made to the accompanying drawings, in which:

Fig. 1 shows a pipe and hose of a hose-to-pipe connection according to the invention prior to the hose being pushed onto the pipe, partially in cross-section, with viscous sealing material accumulated alongside the retaining rib of the pipe; F19.2 shows one half of a completed hose-to-pipe connection according to the invention; Fig. 3 shows a part of a modified hose-to-pipe connection according to Fig. 2 with two restraining ribs instead of just one; and Fig. 4 shows another method according to the invention for applying viscous sealing material to the pipe by means of a shaping tool.

According to Figs. 1 and 2 a hose-to-pipe connection according to the invention consists of a pipe 1 having at least one retaining rib 2 at its end, a hose 3, a sealing material 4 and a clampable clip 5 consisting of a clamping strip 6 with a clamping jaw 7 and a clamping screw 8.

The sealing material 4 is a silicone rubber which retains its properties and also its sealing capacity in a temperature range from about -800C up to about +2600C. It may be a hot-vulcanising silicone rubber which is vulcanised with peroxides at 20011C. However, also coldvulcanisable silicone rubbers may be used. Cold-vulcanisable silicone rubbers are solvent-free paste-like preliminary products used as bicomponent compounds with special vulcanising agents or as a singlecomponent mixture which is vulcanised by the influx of air. In the present case, the sealing material is a dimethyl polysiloxane with a vulcanising agent and special fillers.

The pipe 1 consists of metal and the hose 3 consists of an ethylenepropylene-terpolymer (EPDM) with a fabric interlining.

According to Fig. 1, the sealing material 4 while in a viscous state is applied in the form of an accumulation of material surrounding the pipe 1 between the retaining rib 2 and the clamping zone of the clip 5, at least up to the radial height of the retaining rib 2 and preferably somewhat higher, in the vicinity of the retaining rib 2. Then, before the sealing material 4 hardens out, the hose 3 is pushed onto the pipe 1 over the retaining rib 2 and the sealing material 4, as shown in Fig. 2. After hardening out, the clip 5 is applied and tightened. It is however also possible to apply the clip 5 and tighten it prior to hardening. When the hose 3 is pushed on, the sealing material 4 spreads out into a thin film which extends over the entire area disposed between the retaining rib 2 and the hose end, an even thicker accumulation resulting in the groove formed by the retaining rib 2 between the latter and the clip 5. After hardening out, the sealing material 4 forms an elastic silicone rubber which clings relatively firmly or rigidly to the outer surface of the pipe 1 but much less firmly to the inner surface of the hose 3.

- 6 The pipe 1 may be, for example, the connection socket on the radiator of an internal combustion engine of a motor vehicle and the hose may be the cooling water hose between the radiator and the engine block.

When the temperature of the hose-to-pipe connection drops below freezing point (when the engine is stationary in winter), the hose material contracts (reducing its volume), so that the clamping force of the clip without the sealing material 4 - would in the absence of the apparatus and method of the invention disappear for want of back pressure and the hose 3 would similarly be loose between the pipe 1 and the clip 5. However the practising of the invention ensures that the connection remains sealingtight even when the engine is switched on and the cooling water pressure rises, even before the cooling water has warmed up. This is attributable to the sealing material 4, particularly in the area between the clip 5 and the retaining rib 2, since even at very low temperature at which the hose material is virtually hard, it still retains its elasticity and the clamping pressure in the region of the clip 5 is substantially maintained and in the region between the clip 5 and the retaining rib 2, as the hose 3 widens out due to the increasing fluid pressure, the residual elasticity in the sealing material causes it to expand radially when relaxed, so that it continues to provide adequate sealing-tightness. The elastic expansion of the sealing material is most pronounced in the region between the clip 5 and the retaining rib 2 because it is there that the sealing material 4 is thickest.

With increasing cooling water temperature, also the connection becomes heated. Consequently, the hose material expands again so that the clip 5 again exerts a greater clamping force so that at least in the clamping area of the clip 5, adequate sealing tightness is provided even if the increasing internal pressure causes the hose 3 to be lifted radially away somewhat from the retaining rib 2.

As long as the sealing a material 4 is serni-fluid, it compensates for all surface roughness on the pipe 1, particularly for axial burrs created upon removal from the mould, so that there is no need for any suface finishing of the pipe 1. In addition, the sealing material 4 adheres firmly to the surface of the pipe 1 so that even at very low temperature the pressurised fluid cannot escape between the sealing material 4 and the pipe 1.

The example of the embodiment shown in Fig. 3 differs from that shown in Figs. 1 and 2 solely in that two retaining ribs 2 are provided and the sealing material while in a semi-fluid or viscous state is applied between the axially inner retaining rib 2 and the clamping or tightening zone of the clip 5 in an accumulated form as in the case of the example shown in Fig. 1, the groove or channel between the two retaining ribs 2 substantially serving only to accommodate excess sealing material 4 which, after the hose 3 has been pushed onto the pipe 1 and the clip 5 has been tightened prior to hardening, is forced against the direction in which the hose 3 is pushed on, towards the end of the pipe 1 so that it does not penetrate the interior of the hose 3 or of the pipe 1.

Fig. 4 diagramatically shows a further method of applying the sealing material 4. In this case, a shaping tool 9 which is largely adapted to the shape of the pipe I and the desired shape of the hardened sealing material 4 is used. It comprises encircling knife edges 10 and 11 and serves to provide an axial sealing effect, the shaping tool 9 consisting of two halves to facilitate removal and being coated on its inside with a material adapted to prevent adhesion between the shaping tool 9 and the sealing material 4. While in a semi-fluid state, the sealing material 4 is injected into the shaping tool 9 through a filling aperture not shown. Then, it remains until it has hardened out in the mould. After removal of the mould, the hose 3 is pushed on as shown in Fig. 2 and the clip 5 is placed around the hose 3 and is tightened. This method permits preassembly of the connection if the pipe 1 is a connection union which will subsequently be fixed for instance to a water pump.

In all cases, the pipe 1 may also be a portion of pipe which constitutes a hose coupling and which has a retaining rib 2 at each end and which is used for connecting two hoses.

-a- Further modified forms of the embodiments illustrated may consist for example, in that also the hose is produced from silicone rubber, particularly with a fabric interlining. Furthermore, the pipe may consist not only of metal but also synthetic plastics material, particularly a polyamide. Then the sealing material may consist of a different synthetic rubber of a fluorelastomer, e.g. an elastomer marketed under the trade marks TeflonR or VitonR of Messrs. Dupont de Nemour.

Claims

1. A hose-to-pipe connection in which the pipe is provided with at least one retaining rib adjacent its end and the hose has an end portion which is pushed over the retaining rib and onto the pipe and is secured by a clip or the like which surrounds the hose behind the retaining rib, wherein, between the hose and the pipe, at least in the region between the retaining rib and the clip, there is a sealing material which retains its sealing capacity over a temperature range of at least -400C to +1400C.

2. A connection according to Claim 1, wherein the sealing material is elastic.

3. A connection according to Claim 1 or 2, wherein the sealing material does not adhere to the hose.

4. A connection according to one of Claims 1 to 3, wherein the sealing material is disposed in the entire region between the retaining rib and the hose end.

5. A connection according to one of Claims 1 to 4, wherein the sealing material is an adhesive which clings only to the tube.

6. A connection according to one of Claims 1 to 5, wherein the sealing material is applied to the pipe in a semi-fluid state and, after hardening out, is located on the pipe.

7. A connection according to one of Claims 1 to 6, wherein the hose is formed of EPDM or silicone rubber, particularly with a fabric inner lining, the pipe is formed of metal or synthetic plastics material, particularly polyamide, and the sealing material is formed of synthetic rubber, particularly silicone rubber or of a fluoroelastomer.

8. A method of producing the connection according to Claim 6 or 7, wherein while in the semi-fluid state, the sealing material is applied in the form of an accumulation of material surrounding the pipe between the retaining rib and the clamping area of the clip at least up to the radial height and in the vicinity of the retaining rib, the hose being pushed over the retaining rib and the sealing material and onto the pipe before the sealing material has hardened.

9. A method of producing the connection according to Claim 6 or 7, wherein the sealing material is applied to the pipe in a shaping tool surrounding the pipe, the hose being pushed onto the pipe after the sealing material has hardened.

10. A connection generally as herein described, with reference to or as illustrated in the accompanying drawings.

11. A method generally as herein described, with reference to or as illustrated in the accompanying drawings.

12. Any novel combination or sub-combination disclosed and/or illustrated herein.