CLAMPING COLLAR

Abstract: Clamping collar (1) for connecting two parts having a cylindrical cross section, designed, in particular, to form a vehicle exhaust conduit, comprising: a strip bent into an open loop whereof the ends (3, 4), spaced from one another, have substantially radially extending bearing lugs (5, 6); clamping means (7) pressing in the area of the ends (3, 4) to exert a circumferential stress tightening the collar (1) upon the parts. According to the invention, the clamping means (7) comprise means (8) for separating the two ends (3-4) when they are slackened with a view to facilitating the opening and removal of the collar (1). Application to the field, in particular, of manufacture of motor vehicle parts.

Description: CLAMPING COLLOR The present invention relates to a clamping collar for hermetically connecting two parts, in particular those designed to form the exhaust conduit of a vehicle exhaust pipe. It will find an application in all those sectors of economic activity in which it is necessary to have recourse to a clamping collar in order to ensure the hermetic connection of two parts, in particular of circular cross-section and, more particularly, in the field of motor vehicle construction for the manufacture of exhaust pipes. Such clamping collars further have the function of exerting tangential stress upon the member about which they are placed in order, in particular, to cause a reduction of their radial dimensions and thus to ensure clamping. There are currently various types of clamping collar in existence, the shape and constitution of which are, furthermore, adapted to their intended use. In particular, in certain specific applications, such clamping collars further have to possess properties enabling them to ensure the hermetic connection of the parts. Such a characteristic is required, in particular, in the case of their application to the hermetic connection of conduits constituting the exhaust system of a vehicle. It should also be noted that, in such applications and, in particular, in the exhaust systems of engines and most especially those of vehicles, such collars also have to withstand high temperatures, as well as considerable temperature variations. Furthermore, they also have to withstand substantial mechanical forces and stresses resulting, in particular, from the vibrations and dynamic stresses arising from the operation of the engine. To enable these different forces and stresses to be withstood, the connection between the two successive portions of an exhaust system can be provided by a clamping collar having a substantially V-shaped cross- section and into which the ends to the two portions of the exhaust system that are in contact are intended to fit, these two ends further having substantially conical matching bearing surfaces projecting perpendicularly to their cylindrical outer surfaces. Such clamping collars are constituted, for example, by two rigid semi-cylindrical parts each terminating at their end in a fixing ring and being held together by means of screws passing through the facing lugs of the collar. There is thus obtained a close, strong contact between the collar and the two portions of the exhaust system. However, in practice, such collars do not give satisfaction since they are of complex design, and they are not always easy to put into place or remove, which, it will be appreciated, leads to added costs when assembling or disassembling a vehicle exhaust system. Furthermore, such collars necessitate the fitting of at least two bolts so as to assemble and clamp the two rings of the collar. The clamping forces are thus poorly exploited and, especially, poorly distributed, since they tend to draw together the two semi-circular members constituting the relatively rigid collar without exerting uniform traction distributed over its periphery, which is detrimental to the sealing characteristics of the clamping of the two parts of the exhaust system. To remedy these drawbacks there has been devised a collar that is constituted by an open ring, the cross- section of which is in the shape of an inverted V and the ends of which comprise bearing lugs, for clamping means, which lugs extend radially into the vicinity of the internal periphery of the ring. For this purpose there has been devised a ring that is deformable for tightly pressing against one another the conically shaped matching bearing surfaces of the tubes, and which has means for clamping and holding the ring in closed position, constituted in a manner known per se by a nut and screw assembly. On its periphery, the head of the screw has a V-shaped notch corresponding to the cross- section of the ring so as to come to bear on a first lug at least in the area of connection thereof to the ring. There is also provided, between the nut and the second lug, a stop analogous to that of the head of the screw, slidingly mounted on the screw and designed to come to bear on the said second lug at least in the area in which it is connected to the ring. In practice, such clamping collars are also difficult to remove, which gives rise to numerous drawbacks, particularly when it is necessary to replace a vehicle exhaust system. Now, vehicle exhaust members are generally subject to rusting phenomena, all the more swiftly in that they are heated to high temperatures. Moreover, they are placed beneath the vehicle and, as a result, through their arrangement and their positioning, they are also liable to receive all sorts of projections, so that their different component parts tend to jam, thus making their disassembly a delicate matter. Furthermore, with such currently used collars, the replacement of one of the parts in a vehicle exhaust system necessitates the replacement of the clamping collar which, in addition to the cost increase arising from the difficulty of dismounting it, generates an increase in the price of such operations. The object of the present invention is to remedy the drawbacks of presently known collars by providing a clamping collar for hermetically connecting two parts intended, in particular, to form the exhaust conduit of a vehicle, which is easy to install and/or remove, while, at the same time, ensuring hermetic connection of the different members in the exhaust system. Furthermore, with a collar according to the invention, the mechanical fixing and hermetic properties are obtained together with ease of assembly and disassembly. These hermetic properties also make for a reduction of undesirable noise, which broadens its potential applications. Another object of the invention is that it should be possible for the clamping collar to be mass produced without necessitating the implementation of complex means, thus reducing its cost and its cost price. A further object of the invention is that it should be possible to re-use the clamping collar if necessary after removal and, in particular, after the replacement of thouse parts of the exhaust system that have to be changed. Another object of the present invention is to provide a clamping collar that is of a robust design so that it can withstand the various phenomena of rusting and/or mechanical stress resulting from its use for the hermetic connection of parts such as, in particular, those of the exhaust conduits of a vehicle exhaust pipe. Further objects and advantages of the present invention will emerge in the course of the following description, which is given only by way of illustration and is not intended to limit same. For this purpose, the invention provides a clamping collar for connecting two parts having a circular cross- section, designed, in particular, to form a vehicle exhaust conduit, comprising: - a strip bent into an open loop whereof the ends, spaced from one another, have substantially radially extending bearing lugs; - clamping means pressing in the area of the ends to exert a circumferential stress clamping the collar onto said parts. It is characterized by the fact that the clamping means comprise means for separating the two ends when they are undamped with a view to facilitating its opening and removal. The present invention will be more readily understood upon reading the following description accompanied by the annexed drawings, wherein: - figure 1 is a front view schematically illustrating a collar according to the invention; - figure 2 is a schematic view in the direction of arrow F- of figure 1 illustrating a bearing lug of the clamping collar which cooperates with the head of the tightening screw; - figure 3 is a schematic view in the direction of arrow ~ of figure 1 schematically representing a bearing lug of the collar according to the invention which cooperates with the head of the tightening screw; - figure 4 is a schematic view illustrating a tightening screw according to the invention; - figure 5 is a schematic exploded view illustrating the component parts of the tightening screw according to the invention; - figure 6 is a view in partial cross-section schematically illustrating a bearing lug which cooperates with the tightening screw in non-locked position; - figure 7 is a view similar to that of figure 6 schematically illustrating the tightening screw in locked position; - figure 8 is a partially cross-sectional view schematically illustrating a bearing lug which cooperates with a tightening screw; - figure 9 is a front view schematically illustrating an alternative form of embodiment of a collar according to the invention; - figure 10 is a schematic view in the direction of arrow F- of figure 9 schematically representing a bearing lug of the collar according to the alternative form of embodiment which cooperates with the head of the tightening screw; - figure 11 is a schematic view in the direction of arrow F. in figure 9 schematically representing a bearing lug of the collar according to the alternative form of embodiment, which cooperates with the head of the tigh¬ tening screw. The present invention relates to a clamping collar 1 for hermetically connecting two parts of circular cross- section, designed, in particular, to constitute the exhaust system of a vehicle exhaust pipe. It will find an application, in particular, in the automotive industry for the purpose of connecting and clamping the various exhaust members, but it is also perfectly feasible to have recourse to this clamping collar in any other sectors of economic activity in which two parts, in particular having a circular cross-section, have to be connected hermeti¬ cally. Furthermore, such parts to be connected have, in the type of application described, facing ends to be assembled which have matching bearing surfaces of substantially conical shape projecting substantially perpendicularly in relation to their cylindrical outer surfaces. To assemble such parts collar 1 according to the invention takes the form, herein, of an open ring 2 made of a metallic material, the cross-section of which is V- shaped. Such a collar is generally produced using con¬ ventional manufacturing techniques and, in particular, by the forming of a flat sheeet of metal. The thickness of the metal sheet will depend, of course, upon the applications, and it is further determined to afford appropriate resistance to the torsional stresses that will be applied to the collar during its clamping. For the purpose of producing vehicle exhaust systems use is made of two tubes manufactured from a metallic material, possessing adequate strength, but of small thickness and the ends for assembly of which have substantially conical matching bearing surfaces projecting substantially perpendicularly in relation to their cylindrical outer surfaces. That is the reason for which it is advantageous for the internal angle of the inverted V-section of the collar to match the angle formed by the conical sides of the facing conical surfaces of the parts to be assembled, so that it is possible to obtain, with such an arrangement, a sufficiently hermetic connection between these two tubes. Each of the free ends, 3 et 4, of the ring 2 comprises a substantially radially extending bearing lug 5, 6. According to the invention, this clamping collar 1 comprises clamping means applied in the area of the ends 3 and 4 to exert a circumferential stress clamping the collar, constituted by a screw-nut assembly 7 which comprises means 8 for separating the ends 3 and 4 and for enabling them to be slackened in order to facilitate the opening and removal of collar 1. These means 8 for slackening the collar are formed, on one hand, by an oblong orifice 9, provided in at least one of the bearing lugs 5, inside which is placed a screw 10 and, on the other hand, by a stop 11, provided subs¬ tantially at one of the ends of the threaded shank 12 of screw 10, with a shape matching the oblong orifice 9, and which delimits, with head 13 of screw 10, an annular groove 14, as illustrated in figure 4. It will be noted that stop 11 delimits two protuber¬ ances 15 and 16 which ensure that the clamping means are locked in translation when it is necessary to arrange the ring 2 in the area of connection of the two members of the exhaust system, and thus ensure hermetic connection between them. It should also be emphasized that bearing lugs 5 and 6 have, on either side of a vertical median plane, a reinforcing side piece 17 which can be produced by appro¬ priately upsetting the metal sheet during manufacture of ring 2. These reinforcing side pieces 17 delimit in lug 5 a housing 18 and inside lug 6 a housing 19. Inside housing 19 is placed a bearing ring 20 which is substantially square in shape and in which is provided, substantially in its central portion, an orifice 21 designed to take up position facing an oblong orifice 22 provided in bearing lug 6. This bearing ring 20 cooperates with a nut 23, such as the one that is more particularly illustrated in figure 5, and which comprises a cylindrical body 24 with an outside diameter substantially smaller than the inside diameter of orifice 21 and of oblong orifice 22, so as to be able to pass through them. This cylindrical body 24 is hollow and it has an internal threaded portion 25 designed to cooperate with the thread of threaded shank 12. The other end of body 24 of nut 23 comprises an annular ring 26 and ends in a head 27 which is, here, a hexagon head. To ensure that the nut 23 is maintained in mounted position, as more particularly illustrated in figure 2, the end 24a of cylindrical body 24 is bent back forming an annular skirt 28 which prevents any possibility of its displacement to cause it to leave oblong orifice 22. This annular skirt 28 is produced, in particular, by swaging or upsetting the end 24a of the cylindrical body 24 of nut 23 after the latter has been placed in a position such that it passes, on one hand, through orifice 21 and, on the other hand, oblong orifice 22 provided in lug 6, this operation being carried out during the manufacture of the collar in accordance with the invention prior to its being put into place so that this nut 23 is already held in a working position illustrated in figure 8 such as the one that will now be described. To enable the collar 1 according to the invention to be put into place, it suffices firstly to position the body of ring 2 in the conical area of connection of the two members of the exhaust system. By exerting a tightening action, for example through the use of a spanner on the head of nut 27, one acts on the clamping means 7 and tightens the two ends, 3 and 4, of ring 2 so as to ensure hermetic connection of the two pieces of the exhaust system. Furthermore, as a result of the tightening action, head 13 which is, in particular, square, of screw 10 becomes rotationally locked inside housing 19 provided in bearing lug 6, and translationally locked via protuber¬ ances 15 and 16 and by the annular groove 14 that is located in a position such as illustrated in figure 7, so that efficient and appropriate clamping of the collar is obtained, ensuring hermetic, efficient connection of the two pieces. It should be noted that, owing to the immobilization of screw 10 and of the tigtening action exerted upon nut 27, regular homogenous distribution of the mechanical clamping forces and stresses is obtained, thus making it possible to ensure that the two pieces of the exhaust system are held efficiently and appropriately, while at the same time preventing localized deformation thereof prejudicial to their correct use. It should also be noted that, owing to the special shape of oblong orifices 9, 22, provided respectively in bearing lugs 5 and 6, it is possible to ensure easy, swift installation, as well as good positioning of the different clamping members and, in particular, of screw 10 which further makes it possible to make up for the play that sometimes exists between the two pieces to be assembled. According to the invention, collar 1 is also easy to dismount, which widens its potential uses and, in particular, permits its possible re-use when, for example, one of the pieces that has been assembled has to be replaced. Furthermore, such dismounting of the collar 1 is simple, as it suffices to exert a slackening action, throught the use of a spanner on head 27 of nut 23. This operation is facilitated, moreover, by the fact that the screw 10 is in a position, represented in figure 7, translationally locked via protuberances 15 and 16 and by groove 14, and rotationally locked via head 13, which is locked in housing 19 in bearing lug 5. Thus, by applying a slackening action to the head of nut 27, using a spanner, one releases the thread 12 of screw 10 which is inserted inside the tapped portion 25 of nut 23 and through this action the two ends 3 and 4 of ring 2 are separated in order to be able to remove the collar 1 and release the two pieces that had been connected together in their conical portions. With more particular reference to figures 9 to 11, an alternative embodiment of the collar according to the invention is represented whereof the elements common to those of the form of embodiment described previously bear the same references. More precisely, here, means 8 are constituted by at least one curved portion 30 of lug 5 which delimits, with the body of ring 2, a housing 34 designed to receive the head 36 of a screw and by a curved portion 31 of lug 6 which also delimits, with the body of ring 2, a housing 35 designed to receive a nut 37. Each lug 5, 6 comprises an orifice 38, 39, the inside diameter of which is slightly greater than the outside diameter of screw 10, and each curved portion 30, 31 also comprises an orifice 40, 41 having a diameter such as to facilitate the passage and putting into place of screw 10 and which is, in particular, oblong to facilitate the positioning of the tightening tool. As regards curved portions 30, 31, these are obtained by machining and forming a flat metal sheet, as more especially illustrated in dotted lines in figure 9, wherein orifices 40 and 41 have been previously pierced. This operation is carried out after putting screw 10 into place through holes 38, 39 provided in each lug 5, 6 and the lock nut 37. To prevent the body of the screw from passing through orifice 38 provided in lug 5 head 36 of the screw has a diameter far greater than that of the orifice. To ensure that nut 37 is held and rendered integral with curved portion 31, the curved portion 31 of lug 6 is swaged, during manufacture of the collar, so that nut 37 is crimped in the strip of sheet metal and can no longer move translationally or rotationally. Of course, is it also conceivable to ensure that this nut 37 is immobilized using weld spots, but this technique would necessitate the implementation of far more complex means, which would increase the cost of manufacturing the collars. This method of immobilization further makes it possible to hold and put the screw 10 into place in an appropriate position. It should also be noted that curved portions 30 and 31 make it possible to enhance the mechanical rigidity of this portion of the collar, which increases its potential applications, particularly under difficult conditions. The diameter of orifice 40 of curved portion 30 is adapted to permit the passage of a tightening tool suitable for cooperating with the screw head 36 such as, for example, a head commonly known as a "torx" or "6 point socket" . Through the use of this tool, when a slackening action is applied to screw 10 by unscrewing the screw head 36, the tool holds the curved portion 30 in a given position and the screw head 36 comes into abutment with the curved portion inside housing 34, which makes it possible to slacken the collar more easily. To re-tighten it suffices, using the tool, to apply a screwing action to the screw head 36 so as to cause the parts of the strip bent into an open loop, and in particular of the two spaced apart ends 3 and 4, to come together. It goes without saying that the present invention is not limited to this form of embodiment as described hereabove but that it extends, on the contrary, to all alternative forms of embodiment. Other implementations of the present invention, within the grasp of a man of the art, could have been contemplated without thereby departing from the scope thereof.

Claims: CLAIMS 1. Clamping collar (1 ) for connecting two parts having a circular cross-section, designed, in particular, to form a vehicle exhaust conduit, comprising: - a strip bent into an open loop whereof the ends (3, 4), spaced from one another, have substantially radially extending bearing lugs (5, 6) ; - tightening means (7) pressing in the area of said ends (3, 4) to exert a circumferential stress tightening the collar (1) upon said parts, c h a r a c t e r i z e d in that said means (7) comprise means ( 8 ) for separating the two ends (3, 4) when they are slackened with a view to facilitating the opening and removal of the collar ( 1 ) . 2. Clamping collar according to claim 1, c h a r - a c t e r i z e d in that the means (8) are constituted by a curved portion (30) of the lug (5) which delimits with the body of the ring (2) a housing (34) designed to receive the head (36) of a screw, and by a curved portion (31) of the lug (6), which also delimits with the body of the ring (2) a housing (35) designed to receive a nut (37). 3. Clamping collar according to claim 2, c h a r ¬ a c t e r i z e d in that the nut (37) is rendered inte¬ gral with the curved portion (31). 4. Clamping collar according to claim 2, c h a r ¬ a c t e r i z e d in that each curved portion (30 and 31) comprises an orifice (40, 41). 5. Clamping collar according to claim 1, c h a r ¬ a c t e r i z e d in that the means (8) are constituted at least, on one hand, by an oblong orifice (9) provided in at least one of the bearing lugs ( 5 ) inside which is placed a screw (10) and, on the other hand, by a stop (11) provided substantially on one of the ends of the threaded shank (12) of the screw (10) of a shape matching that of the oblong orifice (9) and which delimits with the head (13) of the screw (10) an annular groove (14). 6. Clamping collar according to claim 5, c h a r ¬ a c t e r i z e d in that the stop (11) delimits two protuberances (15, 16) which ensure translational locking of the said clamping means. 7. Clamping collar according to claim 5, c h a r ¬ a c t e r i z e d in that it further comprises a nut (23) which has a body (24) designed to be housed in an oblong orifice (22) provided in one of the bearing lugs (6), one of the ends of which has an upset portion delimiting an annular skirt (28) with a view to maintaining the nut (23) inside the orifice (22). 8. Clamping collar according to claim 7, c h a r ¬ a c t e r i z e d in that each bearing lug (5, 6) comprises on either side of a vertical median plane a reinforcing side piece (17). 9. Clamping collar according to claim 7, c h a r ¬ a c t e r i z e d in that it comprises a bearing ring (20) disposed in a housing (18) provided between the rein¬ forcing side pieces (17) of the lug (8). 10. Clamping collar according to claim 7, c h a r ¬ a c t e r i z e d in that the nut (23) comprises an annular ring (26) designed to bear against the ring (20). 11. Clamping collar according to claim 7, c h a r ¬ a c t e r i z e d in that the head (13) of the screw (10) is square so as to be accommodated inside a housing (19) provided between reinforcing side pieces (17) of the lug (5). 12. Clamping collar according to claim 1, c h a r ¬ a c t e r i z e d in that it takes the form of an open ring (2) with a substantially V-shaped cross-section, the ends of which comprise substantially radially extending bearing lugs (5, 6).

Inventors: BECHLER PHILIPPE, ELIASSON ROGER, RYHMAN MORGAN, BECHLER, PHILIPPE, ELIASSON, ROGER, RYHMAN, MORGAN
Applicants: ABA SWEDEN AB, BECHLER PHILIPPE, ELIASSON ROGER, RYHMAN MORGAN, ABA OF SWEDEN AB, BECHLER, PHILIPPE, ELIASSON, ROGER, RYHMAN, MORGAN
Application year: 1993
Main classification: F16L23
IPC codes: F01N7, F16L21, F16L23, F16L33