The present invention relates to a circumferentially exten _d ing joint-sealing element according to the preamble of _C laim 1, an _d to a method of producing a circumferential joint-sea _l in accordance with the preamble of Claim 5.

_A circumferential joint-sealing element of the kind in question is _d isposed on the end of an extension piece or a connector, such as a pipe extension or a tubular channel extension which is to be joined sealingly to another tu _b ular elemnet, such as a pipe or channelling, the exten- sion piece having a relatively shallow channel extending circumferentially inwardly of its free end-edge.

T _h ere is a great need in ventilation techniques and in air-processing installations for a method which will ena _bl e tu _b ular channelling or pipes to be joined together in a simple and reliable fashion, and which will also ena _b le various types of apparatus (such as air supply an ^d air exhaust terminal devices) to be connected sealingly to such channeling or pipes.

Such sealing joints, connections and the like between mutually coacting pipes or channels, in which one en ^d o ^f a first pipe or channel is inserted slightly into the end of an a _d jacent, second pipe or channel of somewhat larger cross-section _d imension than said first pipe or channel, are often achieved with the aid of a circumferential ring seal mounte _d adjacent the end of the pipe or channel having the smaller dimension. Normally, such a ring seal comprises at least one radially projecting, elastic ^b ea ^d or elastic sealing lip, which can be respectively com-

pressed together radially inwards or bent down into seal¬ ing abutment with the inner surface of the end part of the connecting pipe or channel having the larger dimension.

The object of the present invention is to provide a novel type of circumferential (i.e. disposed in the form of a ring) joint-sealing element which is constructionally simple, which can be fitted readily to the end of the extension piece concerned, which will remain positively seated in its intended fitting and functional position while pushing the jointed pipe elements together and when pulling said pipe elements apart. The joint-sealing ele¬ ment shall also provide a good sealing effect in its functional position and shall be cheap to manufacture and to fit onto the end of the extension piece. In addition, the joint-sealing element shall be such that prior to being fitted, the sealing element does not constitute an endless, closed annular sealing element, but that this configuration is, instead, achieved in conjunction with fitting said element, said element being formed from a continuous strip-like rubber profiled-element from which a suitable length is taken in conjunction with fitting the seal to one end of the extension piece or connector.

This object is achieved with a joint-sealing element of the kind set forth in the preamble of Claim 1, in that the sealing element is a strip-like, elastic profiled element, e.g. a rubber element, which presents in cross-section a foot-part by means of which the profiled element is an- chored to the free end-edge of the extension piece, said foot-part having a forward, ϋ-shaped rearwardly bent toe part which grips around the end-edge of said extension piece, and said cross-

section also presenting a rearwardly located heel-part which is disposed on the bottom of the channel at the forward part of said channel, in abutment with the forward side wall of said channel, and a sealing-lip part which projects from the rearward part of said foot-part and which is made of a softer material than said foot-part, said sealing-lip part being intended for sealing abutment with the other defining surface of said tubular element or pipe, and in that the foot-part is provided with retention means which function to hold said foot-part in abutment with the outer surface of the extension piece.

Because of the forwardly located, U-shaped and rearwardly bent toe part of said foot-part, said toe part gripping around the end-edge of the extension piece, it is ensured that the sealing element will not be displaced axially in the shallow channel when the extension piece is pushed into the end of the surrounding pipe, against the inner surface of which the sealing lip part comes into abutment and provides the desired sealing effect.

In turn, the rearwardly located heel-part of said foot-part, due to abutment of said heel part with the forward side-edge wall of the channel, it is ensured that the sealing element will not be drawn loose from the end of the extension piece as said extension piece is with¬ drawn from the end-part of the surrounding pipe, when the two pipes or channels joined together are again separated from one another.

Because the sealing-lip part is manufactured from a softer material than the foot-part, anchoring of the foot-part at one end of the extension piece will be highly effective,

at the same time as the sealing-lip part, due to its greater elasticity, will provide an optimum sealing effect against the inner surface of the surrounding pipe or channel.

Because of the presence of the retention means on the foot-part, the profiled element need not consist of a preformed ring sealing element (endless) but that the profiled element can, instead, consist of a suitable length of a profiled element whose both end surfaces will, admittedly, come into abutment with one another when the joint-sealing element is fitted to one end of the exten¬ sion piece but which need not be joined together by, e.g., vulcanization.

For instance, the retention means may consist of a retain¬ ing wire (see Claim 2) or may have the form of an adhesive (see Claim 3), such as glue.

In order for the sealing element to provide the best sealing effect possible against the inner surface of the surrounding pipe or like tubular element, the two mutually adjacent end regions of the sealing-lip part should over¬ lap one another at the position on the circumference of the extension piece at which the two end surfaces of the foot-part are in end-to-end abutment. This is achieved with a joint-sealing element having the features set forth in the characterizing clause of Claim 4.

The procedural advantages associated with the aforesaid inventive object are achieved with a method of the kind set forth in the preamble of Claim 5 and characterized by the following steps:

A. Forming a sealing element from a continuous strip¬ like, elastic profiled element, e.g. a rubber element, which, in cross-section, presents a foot-part made of a relatively hard, elastic material, and a sealing-lip part which projects outwardly from a rearwardly located heel- part of the foot-part and is made of a relatively soft, elastic material.

B. Taking from the continuous strip-like profiled element a profiled-element length which corresponds to the cir¬ cumferential dimension of the tubular extension piece.

C. Placing the thus obtained profiled-element length around the edge of the extension piece such that a rear- wardly bent toe-part of said foot-part is anchored over the free end-edge of the extension piece, said toe-part having a U-shaped cross-section, while the heel-part is placed on the bottom of the channel at its forward part and in abutment with the forwardly located channel defin- ing surface.

D. Bringing the mutually parallel end-surfaces of the free-ends of said profiled-element length into mutual end- to-end abutment without generating elastic tension in the profiled element.

E. Applying a retention means to the profiled-element length so as to retain said profiled element length in its intended position on the outside of the extension piece.

The circumferential joint-seal thus obtained affords, inter alia, the advantage that there is no need to keep a

large number of different sized joint-sealing elements in store to suit all dimensions of extension pieces that need fitting with this kind of joint-sealing element.

The sealing element required for a given extension piece is, instead, formed directly on the extension piece it¬ self, by cutting from a stored length of the strip-like profiled element a length which corresponds to the circum¬ ferential dimension of the extension piece concerned, said storage length being many times greater than the length required to produce the joint seal in question. A joint seal whose size corresponds exactly to the extension piece concerned can be readily produced when practicing the inventive method. Thus, the requisite length of profiled- element is produced at the time of forming the joint seal at the end of the extension piece.

Various retention means can be used; two such means are defined in Claims 6 and 7, although other means or a combination of these means can be used.

The invention will now be described in more detail with reference to an exemplifying embodiment of an inventive joint-sealing element illustrated in the accompanying drawings, in which

Figure 1 is an axial sectional view through the end-parts of two tubular channel elements which are to be joined sealingly together with the aid of an inventive sealing element;

Figure 2 illustrates in larger scale that part of the channel elements contained within the oval II in Figure 1;

Figure 3 is a sectional view corresponding to the view of Figure 2, but illustrates the channel elements subsequent to having pushed the part fitted with the sealing element into a surrounding channel element;

Figure 4 illustrates the situation in which withdrawal of the channel element to which the sealing element is fitted from the surrounding channel element has commenced; and

Figure 5, finally, is a spread-view, from above, of the region in which the two end surfaces of the foot-part of said profiled-element length lie in end-to-end abutment.

Figure 1 illustrates the situation which prevails when an extension piece or tubular connector 1 is to be connected sealingly to a pipe 2, by inserting the left end of the extension piece 1, fitted with a circumferential, inven- tive seal 3, slightly into the right-hand end of the pipe 2, the internal diameter of which is somewhat larger than the outer diameter of the extension piece 1. Thus, the joint is produced by pushing the extension piece 1 into the pipe 2 (in the direction of the arrow A) to an extent such that the sealing-lip part 4 of the seal 3 will come into sealing abutment with the inner surface of the pipe 2, as illustrated in larger scale in Figure 3.

As illustrated in the larger scale illustrations of Fig- ures 2-4, the annular seal 3 comprises a sealing element 5 which is fitted to the conical end-part 6 of the extension piece 1, which has a relatively shallow circumferential channel 7 provided immediately inwardly of the end-part 6.

The sealing element 5 comprises a strip-like profiled- element length which is disposed in the form of a ring around the end-part 6 and in the forward part of the channel 7. When seen in cross-section, this profiled element 5 presents a foot-part 8, by means of which said profiled element is anchored to the conical end-part 6, a sealing-lip part 4 which in an unloaded state extends outwardly and upwardly from the rear part of said foot- part 8 and which is made of a softer material than said foot-part. Although the foot-part and sealing-lip part 4 will preferably be made of rubber of mutually different hardnesses, it is conceivable that said parts may also be formed from plastics materials having appropriate elastic properties.

The forwardly located portion of the foot-part 8 is con¬ figured as a toe-part 10 which grips around the end-edge 9 of the end-part 6 and which is bent rearwardly in a U- shape slightly in beneath the edge of the end-part 6. The rearwardly located portion of the foot-part 8 is config¬ ured as a heel-part 11 which is placed on the bottom of the channel 7 at the forward part thereof, the front part of said heel-part 11 supporting against the forwardly located side-wall 12 of the channel 7.

For the purpose of retaining the sealing element 5 in the illustrated, functional position (see Figure 3) at the end-part 6, the foot-part 8 is provided with retention means in the form of a retaining wire or thread 13 mounted on the upper side of the profiled element at the junction between the rearwardly located portion of the foot-part 8 and the sealing-lip part 4. The wire, or thread 13, may be

made of metal, textile, plastics or like material. Alter¬ natively, the retention means may consist of a glue joint between the outer surface of the conical end-part 6 and the undersurface of the area of the foot-part in abutment with said-part, i.e. the area between the end-edge 9 and the heel-part 11. In those instances when the retention means has the form of a thread or wire 13, the ends of the thread or wire may be appropriately joined together, for instance by knotting or welding said ends together, or in some other way.

The profiled element length from which the sealing element is formed is thus placed in the form of a ring around the conical end-part 6 and positioned in the forwardly located part of the channel 7. The two ends of the profiled-ele¬ ment length are brought into face-to-face abutment with one another at a location on the circumference of the extension piece l, as illustrated in the spread view of Figure 5. At this abutment location (in the centre of Figure 5), the mutually parallel and abutting end-surfaces of the foot-part 8 lie in the contact plane B shown in Figure 5, this plane extending perpendicularly to the longitudinal edge 14 of the profiled-element length. The sealing-lip part 4, on the other hand, has end surfaces 15 and 15' respectively which project obliquely outwards from said plane B in mutually opposite directions, which means that the sealing-lip part 4 will overlap on itself within a triangular region C located between said end-surfaces 15 and 15'. Thus, the overlapping end-regions of the sealing- lip part can move mutually by virtue of the fact that they are able to slide on one another in the overlapping region C. This enables the sealing-lip part 4 to provide a good sealing effect against a surrounding pipeor like tubular

element, even should the sealing-lip part 4 have varying degrees of crookedness. This crookedness or sloping of the sealing-lip part 4 in its sealing position is quite natu¬ ral, inter alia, because of the differences in diameter between the pipe 2 and the extension piece 1, or as a result of the free height of the channel 7, calculated from the bottom of the channel to the inner surface of the pipe 2. This free height cannot always be predetermined with any high degree of accuracy, and hence the ability of the sealing-lip part 4 to "accept" certain variations in dimensions without impairing the sealing effect is of significant importance.